Electrical and Electronics Engineering publications abstract of: 11-2017 sorted by title, page: 11

» Low Delay Random Linear Coding and Scheduling Over Multiple Interfaces
Abstract:
High-performance real-time applications, expected to be of importance in the upcoming 5G era, such as virtual and augmented reality or tele-presence, have stringent requirements on throughput and per-packet in-order delivery delay. Use of multipath transport is gaining momentum for supporting these applications. However, building an efficient, low latency multipath transfer mechanism remains highly challenging. The primary reason for this is that the delivery delay along each path is typically uncertain and time-varying. When the transmitter ignores the stochastic nature of the path delays, then packets sent along different paths frequently arrive out of order and need to be buffered at the receiver to allow in-order delivery to the application. In this paper, we propose Stochastic Earliest Delivery Path First (S-EDPF), a generalization of EDPF which takes into account uncertainty and time-variation in path delays yet has low-complexity suited to practical implementation. Moreover, we integrate a novel low-delay Forward Error Correction (FEC) scheme into S-EDPF in a principled manner by deriving the optimal schedule for coded packets across multiple paths. Finally, we demonstrate, both analytically and empirically, that S-EDPF is effective at mitigating the delay impact of reordering and loss in multipath transport protocols, offering substantial performance gains over the state of the art.
Autors: Andres Garcia-Saavedra;Mohammad Karzand;Douglas J. Leith;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Nov 2017, volume: 16, issue:11, pages: 3100 - 3114
Publisher: IEEE
 
» Low Power Microwave Signal Detection With a Spin-Torque Nano-Oscillator in the Active Self-Oscillating Regime
Abstract:
A spin-torque nano-oscillator (STNO) driven by a ramped bias current can perform spectrum analysis quickly over a wide frequency bandwidth. The STNO spectrum analyzer operates by injection locking to external microwave signals and produces an output dc voltage that temporally encodes the input spectrum. We found, via numerical analysis with a macrospin approximation, that an STNO is able to scan a 10 GHz bandwidth in less than 100 ns (scanning rate exceeds 100 MHz/ns). In contrast to conventional quadratic microwave detectors, the output voltage of the STNO analyzer is proportional to the amplitude of the input microwave signal with sensitivity . The minimum detectable signal of the analyzer depends on the scanning rate and, at low , is about 1 pW.
Autors: Steven Louis;Vasyl Tyberkevych;Jia Li;Ivan Lisenkov;Roman Khymyn;Elena Bankowski;Thomas Meitzler;Ilya Krivorotov;Andrei Slavin;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Low-Complexity Early Termination Method for Rateless Soft Decoder
Abstract:
We propose a new early termination method (ETM) with low computational complexity for Luby transform belief propagation (BP) decoder. The proposed method, which we call least reliable messages (LRM) ETM, observes only sign alterations of a small cluster in log-likelihood ratio messages passing between nodes in BP decoder. Simulation results and complexity analyzes show that LRM ETM has quite low computational complexity and small average iteration amounts without any performance degradation compared with conventional ETMs in literature. The method can be applied to code families which can be decoded by BP such as low density parity check codes, polar codes, and Raptor codes.
Autors: Cenk Albayrak;Cemaleddin Simsek;Kadir Turk;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2356 - 2359
Publisher: IEEE
 
» Low-Complexity Methodology for Complex Square-Root Computation
Abstract:
In this brief, we propose a low-complexity methodology to compute a complex square root using only a circular coordinate rotation digital computer (CORDIC) as opposed to the state-of-the-art techniques that need both circular as well as hyperbolic CORDICs. Subsequently, an architecture has been designed based on the proposed methodology and implemented on the ASIC platform using the UMC 180-nm Technology node with 1.0 V at 5 MHz. Field programmable gate array (FPGA) prototyping using Xilinx’ Virtex-6 (XC6v1x240t) has also been carried out. After thorough theoretical analysis and experimental validations, it can be inferred that the proposed methodology reduces 21.15% slice look up tables (on FPGA platform) and saves 20.25% silicon area overhead and decreases 19% power consumption (on ASIC platform) when compared with the state-of-the-art method without compromising the computational speed, throughput, and accuracy.
Autors: Suresh Mopuri;Amit Acharyya;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Nov 2017, volume: 25, issue:11, pages: 3255 - 3259
Publisher: IEEE
 
» Low-Frequency and Broadband Vibration Energy Harvesting Using Base-Mounted Piezoelectric Transducers
Abstract:
Piezoelectric vibration energy harvesters often consist of a cantilevered beam composed of a support layer and one or two piezoelectric layers with a tip mass. While this configuration is advantageous for maximizing electromechanical coupling, the mechanical properties of the piezoelectric material can place limitations on harvester size and resonant frequency. Here, we present numerical and experimental results from a new type of piezoelectric energy harvester in which the mechanical properties and the resonant frequency of the cantilever beam resonator are effectively decoupled from the piezoelectric component. Referred to as a base-mounted piezoelectric (BMP) harvester in this paper, this new design features a piezoelectric transducer mounted beneath the base of the cantilevered beam resonator. The flexibility in the material choice for the cantilever beam resonator means that the resonant frequency and the beam dimensions are essentially free parameters. A prototype made with a 1.6 mm mm mm polyurethane beam, a PZT-5H piezoelectric transducer, and an 8.36-g tip mass is shown to produce an average power of 8.75 and at 45 Hz across a 13.0- load under harmonic base excitations of constant peak acceleration at 0.25 and 1.0-g, respectively. We also show an increase in full-width half-maximum bandwidth approximately from 1.5 to 5.6 Hz using an array of four individual BMP harvesters of similar dimensions with peak power generation of at 37.6 Hz across a 1.934- load at 0.25-g peak base excitation. Finite elements-based numerical simulations are shown to be in reasonable agreement with experimental results, indicating that the harvester behaves like a damped mass–spring system as proposed in this paper. Fabricated using casting and laser machining techniques, this harvester shows potential as a low-cost option for powering small, low-power wireless sensor nodes and other low-power devices.
Autors: Robert Koven;Matthew Mills;Richard Gale;Burak Aksak;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Nov 2017, volume: 64, issue:11, pages: 1735 - 1743
Publisher: IEEE
 
» Low-Frequency Noise in High-Mobility a-InGaZnO/InSnO Nanowire Composite Thin-Film Transistors
Abstract:
In this letter, high-performance amorphous indium–gallium–zinc-oxide (a-InGaZnO) and indium–tin-oxide (ITO) nanowire (NW) composite thin-film transistors (TFTs) are fabricated via a sol–gel approach. By incorporating 0.5 wt% ITO NWs into the a-InGaZnO thin film, the composite TFTs can achieve an enhanced field-effect mobility of 76.5 cm2/ and a high current density of with 10- channel length. The low-frequency noise (LFN) characteristic of the composite TFTs fits the classical 1/ noise model very well in the frequency range 1 to 1000 Hz. The subthreshold slope and LFN results provide an alternative explanation to the enhanced performance of the composite TFTs due to the decreased interfacial trap density. The a-InGaZnO/ITO NW composite TFTs are one of the promising candidates for the development of high-speed low-cost electronics.
Autors: Da Wan;Ablat Abliz;Meng Su;Chuangsheng Liu;Changzhong Jiang;Guoli Li;Huipeng Chen;Tailiang Guo;Xingqiang Liu;Lei Liao;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1540 - 1542
Publisher: IEEE
 
» Low-Frequency Noise in III–V Nanowire TFETs and MOSFETs
Abstract:
We present a detailed analysis of low-frequency noise (LFN) measurements in vertical III–V nanowire tunnel field-effect transistors (TFETs), which help to understand the limiting factors of TFET operation. A comparison with LFN in vertical metal-oxide semiconductor field-effect transistors with the same channel material and gate oxide shows that the LFN in these TFETs is dominated by the gate oxide properties, which allowed us to optimize the TFET tunnel junction without deteriorating the noise performance. By carefully selecting the TFET heterostructure materials, we reduced the inverse subthreshold slope well below 60 mV/decade for a constant LFN level.
Autors: Markus Hellenbrand;Elvedin Memišević;Martin Berg;Olli-Pekka Kilpi;Johannes Svensson;Lars-Erik Wernersson;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1520 - 1523
Publisher: IEEE
 
» Low-Noise Amplifier Protection Switch Using p-i-n Diodes With Tunable Open Stubs for Solid-State Pulsed Radar
Abstract:
In this letter, a tunable protection switch device using open stubs for -band low-noise amplifiers (LNAs) is proposed. The protection switch is implemented using p-i-n diodes. As the parasitic inductance in the p-i-n diodes may degrade the protection performance, tunable open stubs are attached to these diodes to obtain a grounding effect. The performance is optimized for the desired frequency band by adjusting the lengths of the microstrip line open stubs. The designed LNA protection switch is fabricated and measured, and sufficient isolation is obtained for a 200 MHz operating band. The proposed protection switch is suitable for solid-state power amplifier radars in which the LNAs need to be protected from relatively long pulses.
Autors: Se-Yeon Jeon;Konstantin Nikitin;Aulia Dewantari;Jaeheung Kim;Min-Ho Ka;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Nov 2017, volume: 27, issue:11, pages: 1004 - 1006
Publisher: IEEE
 
» Low-Power 19-Transistor True Single-Phase Clocking Flip-Flop Design Based on Logic Structure Reduction Schemes
Abstract:
In this paper, an ultralow-power true single-phase clocking flip-flop (FF) design achieved using only 19 transistors is proposed. The design follows a master–slave-type logic structure and features a hybrid logic design comprising both static-CMOS logic and complementary pass-transistor logic. In the design, a logic structure reduction scheme is employed to reduce the number of transistors for achieving high power and delay performance. Despite its circuit simplicity, no internal nodes are left floating during the operation to avoid leakage power consumption. In this design, a virtual design technique, which facilitates a faster state transition in the slave latch, is devised to enhance time performance. In circuit implementation, transistor sizes are optimized with respect to the power-delay product (PDP). A TSMC 90-nm CMOS process was selected as the implementation technology. In this paper, the performance levels of seven FF designs were compared. The timing parameters of each FF were first characterized. Post-layout simulation results indicated that the proposed design excelled in various performance indices such as PDP, clock-to-Q delay, average power consumption, and leakage power consumption. Moreover, the design was determined to have the smallest layout area. Compared with the conventional transmission-gate-based FF design, the PDP improvement in the proposed design was up to 63.5% (at 12.5% switching activity) and the area saving was approximately 10%. Further simulations on process corners, supply voltage settings, and working frequencies were conducted to study the design reliability.
Autors: Jin-Fa Lin;Ming-Hwa Sheu;Yin-Tsung Hwang;Chen-Syuan Wong;Ming-Yan Tsai;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Nov 2017, volume: 25, issue:11, pages: 3033 - 3044
Publisher: IEEE
 
» Low-Power Highly Sensitive pH Sensor With $mu$ dots Protective Structures for Monitoring Rumen in Cows in Real-Time
Abstract:
In this paper, we describe the development of a solid-type pH sensor with an ultra-low power consumption of mAh per measurement and a reasonably high accuracy of 0.1 pH for the real-time monitoring of the rumen of a cow. The sensor combines a metal-oxide-semiconductor field-effect transistor with a separate gate as the sensing electrode, and was fabricated using indium tin oxide with an optimized capture structure that incorporates protective micro-fabricated dots. The evaluation results show that the sensor has high-sensitivity of /pH, and maintains a stable baseline at pH 7 over the course of several days in the rumen. We performed a comprehensive calibration of the solid pH sensor, and carried out a field test, which clearly demonstrated that the pH values are strongly dependent on the activities of the cow, as recorded by a camera. The developed pH sensor is believed to be of significance for preventing disease, as well as for improving the efficiency of food production.
Autors: Lan Zhang;Jian Lu;Hironao Okada;Hirofumi Nogami;Toshihiro Itoh;Shozo Arai;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7281 - 7289
Publisher: IEEE
 
» Low-Profile Two-Arm Inverted-L Antenna Design for Vehicular HF Communications
Abstract:
Design of an electrically small, low-profile vehicular on-the-move (OTM) wideband high frequency antenna with 24 kHz instantaneous-tuned bandwidth is discussed for near vertical incidence skywave (NVIS) communications. Improvement in performance is obtained by applying multiarming and offset feed antenna modifications. These allow for attaining the desired gain >−20 dBi at 3 MHz with a lower profile compared to traditional OTM 3 kHz bandwidth antennas. Specifically, the addition of the second arm improves the bandwidth, whereas NVIS gain is enhanced by offset feeding. The electrical dimensions of the proposed two-arm design over the platform are (H) at the lowest frequency of operation. Antenna performance and achieved benefits under the condition of mechanical breakdown are also discussed. The scaled prototype of the proposed antenna mounted on a selected vehicular platform is built using additive manufacturing. Measurement results agree well with simulations thereby verifying the design procedure and all the discussed findings.
Autors: Saurabh A. Sanghai;Maxim Ignatenko;Dejan S. Filipovic;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Nov 2017, volume: 65, issue:11, pages: 5710 - 5719
Publisher: IEEE
 
» Machine Learning and Financial Planning
Abstract:
One of the top recent events in machine learning (ML) involves Google's Alpha Go System beating the world's best player Ke Jie, while experts had predicted that Go (which is considered by many to be the world's most advanced board game) was too complex to be conquered by a computer for a decade or more. What are the main ideas underlying ML algorithms? What can be expected in the area of financial planning vis-a-vis ML? Will there be major disruptions in financial services?
Autors: John M. Mulvey;
Appeared in: IEEE Potentials
Publication date: Nov 2017, volume: 36, issue:6, pages: 8 - 13
Publisher: IEEE
 
» Machine Vision-Based Positioning and Inspection Using Expectation–Maximization Technique
Abstract:
Precision positioning is very important for automatic assembly and inspection in the electronic manufacturing process. In this paper, we propose a fast image alignment method using the expectation-maximization (E-M) technique. The proposed algorithm is especially applied to positioning and defect inspection of printed circuit boards (PCBs). It can well handle deformed or incomplete object shapes with translation, rotation, and scale changes. The Canny edge detector is used to generate the edge maps of images. The E-step of the E-M procedure finds mutual edge points in both compared images by assigning weights to individual edge points. The mutual edge points give larger weights, while the foreign edge points in two images have smaller weights. The M-step then calculates the geometric transformation parameters using the weighted edge points in individual images. For an edge point in one image, a fast spiral search is proposed to find its corresponding edge point with the shortest distance in the other image. The spiral search is carried out by a predetermined lookup table, and no computation is involved in the search process. The weight of each edge point is inversely proportional to the neighboring distance. Experimental results indicate that the proposed E-M positioning method can achieve a translation error less than 1 pixel and a rotation error smaller than 1° for PCB positioning.
Autors: Du-ming Tsai;Yi-chun Hsieh;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Nov 2017, volume: 66, issue:11, pages: 2858 - 2868
Publisher: IEEE
 
» Magnet Eddy-Current Loss Analysis of Interior PM Machines for Electric Vehicle Application
Abstract:
The magnet eddy-current losses of six interior permanent magnet (IPM) machines are investigated for electric vehicle applications in this paper. The armature field, eddy-current density of magnet, the influence of PM depth, the distance of PM layers, and the number of PM segmentation are studied by finite-element analysis. It is demonstrated that increasing the PM depth of first layer and the distance of PM layers can provide more soft iron space for the armature-reaction flux, which can reduce the magnet eddy-current loss. PM segmentation can effectively reduce the PM eddy-current loss, because the eddy-current paths are divided into smaller loops, increasing the effective resistance. An IPM machine with segmented PM is prototyped to verify the analysis.
Autors: Yaohua Hu;Shushu Zhu;Chuang Liu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Behavior of Polycrystalline Gadolinium Subjected to a Magneto-Thermal Protocol
Abstract:
Magneto-thermal (M-T) hysteresis is studied in polycrystalline gadolinium (Gd). The change of the sign of the first anisotropy constant leads to easy cones of magnetization below the spin-reorientation temperature ( K). Cooling a polycrystalline Gd sample in a magnetic field through the spin-reorientation temperature creates magnetic structures which persist to temperatures close to the Curie temperature, if these structures are not erased by going to fields larger than the cooling field. An M-T protocol is applied to give some systematics to these complex processes.
Autors: Virgil Provenzano;Anthony S. Arrott;Hatem ElBidweihy;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Magnetic Characteristics of CuCr2S4 Nanospinels Obtained by Mechanical Alloying and Heat Treatment
Abstract:
Chalcogenide bulk spinels with general formula CuCr2X4 (X = S, Se, and Te) are ferromagnetic and p-type metallic materials with the thermoelectric figure of merit of 0.15. They can be used to dope or alloy with related semiconducting spinels. Therefore, it is expected that their nanosized crystallites display also unique properties and new potential applications. This paper presents the results of dc and ac magnetic measurements, including the higher harmonics of ac magnetic susceptibility as well as electrical conductivity and thermoelectric power of the CuCr2S4 nanospinels. These studies showed that decreasing the size of crystallites to nanometer scale leads to a dramatic change in their physical properties.
Autors: E. Maciążek;E. Malicka;M. Karolus;J. Panek;Z. Stokłosa;T. Groń;A. Gudwański;B. Sawicki;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Magnetic Composite Hydrodynamic Pump With Laser-Induced Graphene Electrodes
Abstract:
A polymer-based magnetohydrodynamic pump capable of actuating saline fluids is presented. The benefit of this pumping concept to operate without any moving parts is combined with simple and cheap fabrication methods and a magnetic composite material, enabling a high level of integration. The operating principle, fabrication methodology, and flow characteristics of the pump are detailed. The pump electrodes are created by laser printing of polyimide, while the permanent magnet is molded from an NdFeB powder–polydimethylsiloxane (PDMS) composite. The cross section area of the pump is 240 mm2. The electrode length is 5 mm. The magnetic characteristics of the NdFeB–PDMS composite indicate high degree of magnetization, which increases the pump efficiency. Using a saline solution similar to seawater, the pump produces 3.4 mm/s flow velocity at a voltage of 7.5 V and a current density of 30 mA/cm2.
Autors: Mohammed Asadullah Khan;Ilija R. Hristovski;Giovanni Marinaro;Jürgen Kosel;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Core-Size Distribution of Magnetic Nanoparticles Estimated From Magnetization, AC Susceptibility, and Relaxation Measurements
Abstract:
The magnetic core-size distribution of magnetic nanoparticles (MNPs) was estimated from three independent measurements, i.e., magnetization, ac susceptibility (ACS), and magnetic relaxation (MRX). First, distribution of magnetic moment m in MNP sample was estimated by analyzing the static magnetization (– curve of the MNP sample in suspension. Next, distribution of anisotropy energy E was estimated by analyzing the ACS of immobilized MNP sample measured from 10 Hz to 1 MHz. The ACS measurement in much lower frequency range was substituted by the MRX measurement. MRX of immobilized MNP sample was measured from 2 to s, corresponding to the frequency range from to 0.5 Hz in ACS measurement. The relaxation curve was analyzed using a newly developed analytical method to estimate the E distribution of the MNPs in the range of large E values. Then, the estimated distributions of m and E were transferred to the distributions of magnetic core size. Core-size distributions obtained from m and E distributions reasonably agreed with each other. Namely, we obtained similar core-size distribution from static and dynamic properties of MNP sample, confirming the validity of the present method. Therefore, the present method can be useful to estimate the core-size distribution of MNP sample.
Autors: Ahmed L. Elrefai;Teruyoshi Sasayama;Takashi Yoshida;Keiji Enpuku;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Magnetic Dead Layers in La0.7Sr0.3MnO3 Revisited
Abstract:
The magnetic dead layers in films a few nanometers thick are investigated for La0.7Sr0.3MnO3 on SrTiO3(STO), LaAlO3(LAO), and (LaAlO3)0.3(Sr2TaAlO6)0.7 (LSAT) substrates. An anomalous moment found to persist above the Curie temperature of the La0.7Sr0.3MnO3 films is not attributed to the films, but to oxygen vacancies at or near the surface of the substrate. The contribution to the moment from the substrate is as high as /nm2 in the case of STO or LSAT. The effect is increased by adding an STO cap layer. Taking this d-zero magnetism into account, extrapolated magnetic dead-layer thicknesses of 0.8, 1.5, and 3 nm are found for the manganite films grown on LSAT, STO, and LAO substrates, respectively. An STO cap layer eliminates the LSMO dead layer.
Autors: S. B. Porter;M. Venkatesan;P. Dunne;B. Doudin;K. Rode;J. M. D. Coey;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Field Analysis for Dimensional Resonance in Mn–Zn Ferrite Toroidal Core and Comparison With Permeability Measurement
Abstract:
This paper studies the calculation method of core loss and magnetic state in Mn–Zn ferrites under an arbitrary waveform excitation. The effective dielectric constant, which is caused by a thin high-resistive layer at the grain boundary, is treated as a modification of Ohm’s law by using an equivalent circuit. This procedure enables us to calculate both the dimensional resonance and eddy-current loss. To confirm the accuracy of the proposed model, the size dependence of the complex permeability and core loss of the toroidal core is analyzed. These results show a good agreement with the experimental measurement in the megahertz region. By using the same model, the core loss mechanism excited by a triangular-wave current is analyzed. In the low-frequency region, the core loss is suppressed by the reduction of a steep change in magnetic flux. However, the core loss near the resonant frequency is increased at the turning point of the current wave, where the time derivative of the current changes discontinuously and a higher harmonic component is induced.
Autors: Atsushi Furuya;Yuji Uehara;Koichi Shimizu;Jun Fujisaki;Tadashi Ataka;Tomohiro Tanaka;Hirotaka Oshima;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Field Dependence of Ni Nanorod Brownian Relaxation
Abstract:
AC magnetic susceptibility and optical transmission measurements were performed on Ni nanorod suspensions for ac and superimposed dc magnetic fields up to 9 mT. With the comparably large magnetic moment per nanorod, these field values correspond to Langevin parameters up to about 80. These wide range of values, the narrow size distribution, and the absence of Néel relaxation make these single-domain ferromagnetic nanorods ideally suited for the experimental verification of the dependence of the Brownian relaxation time on ac and dc magnetic fields. Consistent results for the magnetic moment m and the zero-field Brownian relaxation time were obtained for all measurement modalities and the valid field range of alternative models for the ac susceptibility was evaluated.
Autors: Hilke Remmer;Micha Gratz;Andreas Tschöpe;Frank Ludwig;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Field Distortion From Conductive Layers for High-Frequency Speed Sensor Applications
Abstract:
In previous works, the known scalar approach for the vector potential was extended to determine the influences of eddy currents in metallic layers in a closed form, based on a connection between infinite integrals of Bessel functions and the complete elliptic integrals. While the original idea treats only thin layers with respect to the penetration depth, in this paper, the formalism is extended to the opposite limit of thick layers. It was shown that the developed formalism can be used as a framework to analyze and classify the development of eddy currents in speed sensor systems and even to advocate on chip layout. This extension to thick layers is of great interest in this context as it describes the regime where eddy currents strongly influence the sensor output signal.
Autors: Bernd Filipitsch;Michael Ortner;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Fluorescent Nanoparticles Binding to Amyloid-Beta Peptide: Silica-Coated, Thioflavin-T Functionalized Iron Oxide
Abstract:
Formation and accumulation of extracellular amyloid-beta ( peptide aggregates in the brain are associated with Alzheimer’s disease, a widespread age-related form of dementia, for which there is no effective treatment at present. It is essential to discover ways of visualizing and monitoring the progress of aggregation toward amyloidic plaques while at the same time therapeutic methods inhibiting the aggregation can be explored. Iron oxide nanoparticles Fe3O4 with size ~10 nm have been coated with silica SiO2 and Thioflavin-T (ThT), a non-toxic fluorescent dye binding to the amyloid- structures with a possible effect on fibril formation, and then added to phosphate-buffered saline solution, incubated for 30 min and extracted by magnetic separation. The magnetic ThT silica-coated nanoparticles with size ~20 nm have been characterized structurally and magnetically by powder X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and vibrating sample magnetometer. Their affinity to peptide, examined by fluorescence microscopy and protein concentration measurements using the BCA Protein Assay Kit has been verified. Successful binding of magnetic silica nanoparticles, doped with ThT, to peptide provides a nanocarrier potentially exemplifying multiple functions, such as magnetic imaging, magnetic handling, drug delivery, fluorescence imaging, $text{A}beta $ binding, and aggregation inhibition.
Autors: Apostolos C. Tsolakis;Eleftherios Halevas;Nikolaos Vouroutzis;George G. Koliakos;Athanasios Salifoglou;George Litsardakis;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Flux Analysis of a New Field-Excitation Flux Switching Motor Using Segmental Rotor
Abstract:
Recently, a three-phase field-excitation flux switching motor (FEFSM) with salient rotor structure has been introduced with their advantages of easy rotor temperature removal and controllable field excitation coil (FEC) magnetic flux particularly suitable for high torque, high power, and high-speed diverse performances. Nevertheless, the salient rotor structure is found to lead a longer magnetic flux path between stator and rotor producing weak flux linkage along with low torque performances. Besides, the overlap armature coil and FEC windings yield high coil end length, producing much high copper loss and large motor size. In this paper, a new FEFSM using segmental rotor with non-overlap armature coil and FEC windings is proposed. The shorter magnetic flux path of the proposed segmental rotor is noticeably more focused to produce much higher torque while the non-overlap armature and FEC will reduce the copper loss and motor weight. Both FEFSMs with salient and segmental rotors are designed using 2-D-FEA JMAG Designer version 14.1 for comparison. As a result, magnetic flux of the segmental rotor design is 11 times higher than the salient rotor structure mainly due to shorter magnetic flux linkage between two stator teeth and single rotor segment. The torque and power of 0.91 Nm and 293 W, respectively, are obtained from the new FEFSM which are much higher than salient rotor design. In addition, the simulation and experimental results show a good agreement in back-electromotive force amplitude and waveform at various speeds, as well as similar increment of torque versus FEC current characteristics. As the conclusion, the proposed FEFSM with non-overlap and segmental rotor structure has produced much higher flux, with significant improvement of torque and power performances compared with existing FEFSM with salient rotor.
Autors: M. F. Omar;E. Sulaiman;M. Jenal;R. Kumar;R. N. Firdaus;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Loss Versus Frequency in Non-Oriented Steel Sheets and Its Prediction: Minor Loops, PWM, and the Limits of the Analytical Approach
Abstract:
The pulsewidth modulation (PWM) technique is commonly used to supply modern high-speed electrical machines. The fundamental frequency is typically in the kilohertz range, with switching frequencies of several tens of kilohertz, as determined by the new SiC- or GaAs-based power transistors modules. Switching introduces minor loops in the major hysteresis cycle, with durations of the order of or lower, with the resulting magnetization dynamics influenced by strong skin effect. However, since these minor loops have relatively small amplitude, their constitutive equation may be described by an equivalent permeability (real or complex), depending on the mean slope of the minor loop and its static energy loss. By retrieving this permeability, the classical loss is straightforwardly calculated by analytical solution of Maxwell's equations. In this paper, we measure and calculate, according to the quasi-linear approximation for the minor loops, the magnetic energy losses of 0.194 mm thick non-oriented Fe–Si 3.2% sheets subjected to PWM induction waveform. Minor loop peak amplitudes ranging between 50 mT and 0.2 T and frequencies up to 10 kHz are investigated. The results are consistent with the proposed model, to within 5%.
Autors: Hanyu Zhao;Carlo Ragusa;Olivier de la Barrière;Mahmood Khan;Carlo Appino;Fausto Fiorillo;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Materials Used in Electrical Machines: A Comparison and Selection Guide for Early Machine Design
Abstract:
This article presents an up-to-date magnetic material investigation and overview on soft magnetic materials used in rotating electrical machines. The focus is on small-to-medium-sized high-performance and high-efficiency permanent-magnet and induction motors for different application scenarios. The investigated materials include fully processed silicon-iron (SiFe), nickel-iron (NiFe), and cobalt-iron (CoFe) lamination steels as well as soft magnetic composites (SMCs) and amorphous magnetic materials. This article focuses on the magnetic properties and iron losses as well as the manufacturing influence and required thermal treatments during the manufacturing process. A new loss-to-flux-density factor is introduced to compare the magnetization curve and the iron losses of different materials within the same diagram. This article provides a review and comparison of magnetic substances for use in high-performance machines.
Autors: Andreas Krings;Marco Cossale;Alberto Tenconi;Juliette Soulard;Andrea Cavagnino;Aldo Boglietti;
Appeared in: IEEE Industry Applications Magazine
Publication date: Nov 2017, volume: 23, issue:6, pages: 21 - 28
Publisher: IEEE
 
» Magnetic Modeling of a Linear Synchronous Machine With the Spectral Element Method
Abstract:
The field calculus for electrical machines (EMs) is realized solving subdomain problems. Most often, the latter are solved using either finite element analysis (FEA) or the semi-analytical solution of a Laplace or Poisson equation obtained by separation of variables. The first option can capture complex geometries but becomes slow for high accuracy, whereas the second is fast but limited to simple periodic geometries and linear or infinite permeable materials. This paper presents the 2-D implementation of the spectral element method (SEM) for the modeling of EMs. The polynomial basis functions used to approximate the solution in each domain are reaching exponential convergence similar to the semi-analytical solution. Moreover, each element can be represented by a non-square shape resulting in the possibility to model complex geometries. Following the results in this paper, significantly fewer degrees of freedom are needed for the SEM to achieve the approximation similar to the FEA, and consequently less memory and computational time are required.
Autors: M. Curti;J. J. H. Paulides;E. A. Lomonova;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 6
Publisher: IEEE
 
» Magnetic Noise and Spin-Wave Eigenmodes in a Magnetic Tunnel Junction Read Head
Abstract:
With read-head structures becoming very small (<30 nm typical size), thermal fluctuations of the free and reference layers, occurring in the gigahertz range of frequencies, may become relatively large (>20°) and cause the appearance of considerable magnetic noise in the read-back function. For instance, the experimental test of a read-head sensor shows that a considerable low-frequency noise appears in the measured signal in coincidence with the superposition of high-frequency eigenmodes of the stack. To shed light on these experimental data, we perform extensive micromagnetic simulations to analyze the spin-wave spectrum of the read-head sensor and its evolution under the application of an external magnetic field. We show that the nonuniformity of both the bias field and the demagnetizing field induces pronounced spatially dependent dynamics within each layer. Moreover, the derived read-back function is characterized by different peaks that reflect the underlying eigenmodes spectrum, as suggested also by simple macrospin approach. However, for large precession amplitude, nonlinear and mixing effects appear, leading to the presence of extra peaks and of a low-frequency tail in the readback signal, in qualitative agreement with experiments.
Autors: M. Pauselli;A. Stankiewicz;Y. Zhang;G. Carlotti;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 6
Publisher: IEEE
 
» Magnetic Orientational Properties of Monosodium Urate Crystals
Abstract:
Monosodium urate (MSU) crystals are the cause of gout and are formed from uric acid and sodium. Because they can be rotated by the torque induced by an applied magnetic field, we have characterized their detailed magnetic orientational properties to improve the detection sensitivity from outside the body using the magnetic orientation. The MSU crystals were precipitated by dissolving uric acid powder in aqueous sodium hydroxide. In serum, the MSU crystals were small and uniformly sized, similar to those obtained from gout patients. The MSU crystals were not completely oriented perpendicular to the magnetic-field direction, but rather the c-axis of the crystal was inclined with respect to the field direction. Specifically, they were inclined at a mean of 69.3° under a magnetic field of 500 mT. The MSU crystals were not perfectly oriented in magnetic fields <200 mT. The inclination results from the molecular structure of the MSU crystal.
Autors: Y. Takeuchi;M. Sekiya;A. Hamasaki;M. Iwasaka;M. Matsuda;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Particle Spectrometry of Fe3O4 Multi-Granule Nanoclusters
Abstract:
Magnetic particle imaging (MPI) is a novel high-resolution medical imaging method that does not use ionizing radiation, but safe iron oxide nanoparticles as contrast agents. By employing magnetite (Fe3O4) multi-granule nanoclusters (MGNCs), one has two control parameters: the diameter of the particles and that of granules in single particles. Here we investigate the effect of the size of the particles at constant granule size, as well as the effect of granule size at constant particle size on the magnetization reversal. The saturation magnetization Ms value increases with increasing granule diameter and particle diameter, while the coercivity Hc value reaches a maximum at a particle size of about 60 nm. MGNCs with an average particle size of 77 nm and granule diameter of 17 nm show a larger response in the higher harmonics compared to the commercial reference, FeraSpin R dispersion, at both 20 and 30 mT. This result demonstrates that the MGNC concept allows tailoring of the magnetic properties of the particles to the imaging conditions in MPI.
Autors: Lijun Pan;Bum Chul Park;Micheal Ledwig;Leon Abelmann;Young Keun Kim;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Properties and Columnar Structure for CoPt Alloy Granular Media With Grain Boundary Oxides of Various Melting Points
Abstract:
Investigation of the effect of the melting point ( of various single oxides on the columnar growth and generation of the nucleation site for CoPt granular media deposited at room temperature were conducted. When oxide with from 1857 °C to 2410 °C is added to the granular media, thickness of the heteroepitaxial growth of the magnetic grains on the Ru underlayer (columnar structure) decreases from 13 to 5.5 nm. The employment of oxide with of the range from 450 °C to 2410 °C to the granular media will lead to the reduction of grain size from 5.6 to 3.0 nm, due to the suppression of the lateral grain growth by the high oxide.
Autors: Ryosuke Kushibiki;Kim Kong Tham;Shintaro Hinata;Shin Saito;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Properties and Microstructure of FePt Films With MgTiON Intermediate Layer
Abstract:
The magnetic properties and microstructure of FePt films grown on MgTiON intermediate layer were studied. The MgTiON layer was deposited by sputtered (MgTi)ON target at 395 °C. The MgTiON (002) texture was formed on CrRu (002)/glass. Furthermore, the 10 nm thick FePt film was deposited on MgTiON at 450 °C. The FePt shows perpendicular magnetization with out-of-plane coercivity of 3.62 kOe. Smaller FePt out-of-plane coercivity may come from lower ordering degree and continuous layer structure, which provides easy domain wall motion. To promote the ordering of FePt film, thinner MoC layer with thickness of 1 to 3 nm was capped on MgTiON (30 nm) layer during sputtering process. The FePt films with thickness from 4 to 10 nm show perpendicular magnetic anisotropy and the out-of-plane coercivities were increased to 11.9–15.3 kOe. The significant change of FePt out-of-plane coercivity was explained by ordering degree and microstructure. The island growth was dominated when FePt film prepared on thinner MoC interface and the excess carbon from MoC layer was diffused up to promote the ordering of FePt during sputtering. As a result, higher FePt out-of-plane coercivity on MoC/MgTiON intermediate layer was due to higher ordering degree and domain wall pinning effect in separated FePt islands.
Autors: Jai Lin Tsai;Hsu Kang Li;Zu Yu Pan;Yuan Shuo Chang;Yu Ren Chen;Chen Pi;Yu Ting Wu;Ching Wei Chang;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Properties of L10 FeNi Phase Developed Through Annealing of an Amorphous Alloy
Abstract:
Chemically ordered L10 FeNi phase observed in Fe-based meteorite has the potential to replace high-cost rare-earth-based permanent magnets in the future. However, artificial production of this phase is extremely difficult due to negligible atomic diffusion around order–disorder transition temperature (~320 °C). Here, we report a method for producing high-quality L10 FeNi phase and its magnetic properties. We show that a highly disordered metastable state, that is, amorphous can be utilized to produce a highly ordered state, which is not possible with the conventional processing techniques. Amorphous Fe42Ni41.3SixB12−xP4Cu0.7 ( to 8 at.%) alloy ribbons were studied. Crystallization of amorphous ribbons at 400 °C results in adequate atomic diffusion at low temperatures to precipitate L10 FeNi grains. Structural characterization revealed a high degree of chemical ordering (), but the volume fraction of precipitated L10 grains is low. The crystallized ribbons of FeSiBPCu are composed of two magnetic phases (hard magnetic L10 FeNi grains embedded in a soft magnetic matrix). Alloys with higher concentration of Si are shown to produce high coercivity (–750 Oe). The soft magnetic matrix strongly influences the Hc. The actual switching field (≥3.7 kOe) of L10 FeNi has been found to be much higher than that of Hc. In this paper, the L10 FeNi phase is s- own to form at temperatures higher than the reported order–disorder temperature. Our results of temperature-dependent magnetization and thermal analyses suggest that the L10 FeNi phase can survive at temperatures ≤550 °C. The magnetization reversal mechanism was understood by angular dependence of , and it is shown to be a domain-wall pinning type. Due to structural and magnetic similarities between L10 FeNi and L10 FePt, ribbon samples with low-volume fraction of L10 FePt grains in a soft magnetic matrix were prepared with a similar technique. Magnetization behavior of L10 FeNi is shown to be similar to that of L10 FePt.
Autors: Parmanand Sharma;Yan Zhang;Akihiro Makino;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 10
Publisher: IEEE
 
» Magnetic Properties of Nanocrystalline N-NFO Thin Films
Abstract:
The pure as well as nitrogen incorporated nickel ferrite (NFO and N-NFO) thin films were grown by radio frequency magnetron sputtering technique. The structural investigations of as-grown N-NFO films using GIXRD and Raman spectroscopy revealed nanocrystalline nature of the films. The microstructural and surface studies of the films using SEM and atomic force microscope micrographs showed increase in crystallite size and decrease in surface roughness with increase of sputtering power. The magnetization (M-H) measurements at 20 and 300 K revealed an increase in magnetization and decrease in coercivity values with increase of sputtering power. However, no saturation of magnetization () was visible for the thin film samples, indicating superparamagnetic behavior due to nanocrystallinity. The comparison of in-plane and out-of-plane magnetizations of the N-NFO film (both at 20 and 300 K) showed that the easy magnetization direction lied in the plane of the film. The optical transmission spectra revealed decrease of direct band gap with increase of sputtering power.
Autors: K. B. Anoop Baby;G. Markandeyulu;A. Subrahmanyam;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Magnetic Properties of Pure Iron Soft Magnetic Composites Coated by Manganese Phosphates
Abstract:
Soft magnetic composites using metallic magnetic powders have extensively been investigated for the application to mobile electromagnetic devices, particularly motor cores. These metal powders are strongly required to be insulated from one another for low eddy-current losses. In addition, the insulation layer of the powders should possess high thermal stability for low hysteresis losses. Despite poor thermal stability, the iron phosphate coating on iron powders is still widely used because of a well-established technology. In this paper, we focused on the development of manganese phosphate coating on iron powders to overcome the low thermal stability of iron phosphate. It was shown that manganese phosphate insulation layers were thermally stable up to 600 °C. The core loss of composites with manganese phosphate-coated powders annealed at 600 °C measured 35.67 W/kg and the eddy-current loss 5.65 W/kg, indicating that excellent insulation coating layers were formed.
Autors: Sounghun Lee;Moosung Choi;Jongryoul Kim;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Property Enhancement of Melt Spun YCo5 Ribbons by Fe and C Doping
Abstract:
Magnetic properties and microstructure of melt spun YCo5–xyFexCy (–0.3 and –0.3) ribbons are studied. Magnetic properties of YCo5 ribbons (iHc = 144 kA/m and (BH) kJ/m3 are slightly improved to iHc = 160–224 kA/m and (BH)–27.2 kJ/m3 by Fe-doping, and are increased to iHc = 560–1128 kA/m and (BH)–51.2 kJ/m3 by C-doping, respectively. Most interestingly, the optimal (BH) of 72.8 kJ/m3 with high iHc of 1200 kA/m achieved for Fe and C-co-doped YCo4.6Fe0.3C0.3 ribbons is the highest value in Y–Co alloy ribbons ever reported. The structural and thermo-magnetic analysis confirm that Fe and C enter the YCo5 (5:1) crystal structure and lead to the increase of Curie temperature. Besides, C-doping uniformly refines grain size and, therefore, improves the squareness of demagnetization curve and (BH). The formation of YCo, Fe)5Cx phase and the microstructure refinement are the main reasons to result in the enhancement of hard magnetic properties for the YCo4.4Fe0.3C0.3 ribbons. The presented results suggest that the YCo5 ribbons optimized by co-doping with Fe and C are promising candidate materials for making bonded magnets.
Autors: H. W. Chang;W. C. Ou;Y. I. Lee;C. W. Shih;W. C. Chang;C. C. Yang;C. C. Shaw;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Reader Instability as a Source of Low-Frequency Noise
Abstract:
Detecting and characterizing magnetic stability is one of the main goals in hard drive reader testing. A simple model of a bi-stable system leads to random telegraph noise, and reveals spectral characteristics of unstable readers, which may be used for instability detection in standard reader testing. In particular, it proves that unstable devices may show noise reduction with temperature increase, which has been confirmed experimentally. Furthermore, characterization of the telegraph noise in magnetic readers is achieved by high bandwidth time-domain measurements, followed by waveform analysis based on a hidden Markov model. An example of actual reader analysis leads to the estimation of activation energy.
Autors: Andrzej Stankiewicz;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetic Subsurface Imaging Systems in a Smartphone Based on the Built-In Magnetometer
Abstract:
We present a magnetic subsurface imaging system on a smart-phone that employs the built-in magnetometer. The smart-phone’s sensor measures magnetic field strength at sparse locations on a user-defined grid of the surveyed area. Based on the collected data, magnetic field distribution of the entire area is then reconstructed by using an interpolation algorithm, which yields field values in all of three-axial directions. Since the field shows the influence of the buried objects within the surveyed area to the background magnetic fields, the shape and size of the objects can be derived from the image representing the field. An implementation of the system as an application software on Android smart-phone, which consists of data measurement and reconstruction subsystems, is also described. We demonstrate the capability of the proposed system by performing subsurface imaging of small hidden objects in a laboratory test-range.
Autors: Andriyan B. Suksmono;Donny Danudirdjo;Antonius D. Setiawan;Dien Rahmawati;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Magnetoconductivity of the La1–xSrxMnO3@TiO2 Nanocomposite
Abstract:
The study deals with tunneling magnetoresistance in a composite system of so-called 0-3 connectivity, in which ferromagnetic metallic nanoparticles La1–xSrxMnO3 (0-dim objects) are embedded in the (3-dim) insulating matrix of TiO2. The sample fabrication included the sol-gel preparation of manganite particles of the x = 0.35 composition and 25 nm mean crystallite size, their coating by TiO2, and compacting the products by spark plasma sintering. A comparative nanogranular sample was prepared by spark plasma sintering of bare manganite particles. The resistivities of the composite and comparative sample are 100,000 and 100 times higher compared to bulk metallic La1–xSrxMnO3. Otherwise, the temperature dependence observed in the nanogranular La1–xSrxMnO3 sample is similar to single crystal data, and marked localization is absent also in the La1–xSrxMnO3@TiO2 nanocomposite. The data taken in applied fields up to 4 Tesla reveal effects typical for grain-boundary tunneling in manganites, namely the coexistence of the low-field magnetoconductance (LFMC), reflecting the field-induced alignment of FM cores, and high-field linear magnetoconductance (HFMR) that is generally ascribed to the effect of spin canting at localized Mn4+ sites in the interface. This is considered as a signature for resonant tunneling of spin-polarized carriers, theoretically treated by S. Lee et al. [1]. The present results show that the total extent of LFMC makes 45% in the La1–xSrxMnO3@TiO2 nanocomposite and 21% in the La1–xSrxMnO3 nanogranular sample. The slope of HFMC has been determined to 5.4% and 4.9% per Tesla, respectively. The large LFMC effect observed in the nanocomposite exceeds the theo- etical prediction of 33% for the second-order tunneling, which might suggest for higher-order tunneling via resonant states.
Autors: Jakub Koktan;Graziella Goglio;Jiří Hejtmánek;Zdeněk Jirák;Karel Knížek;Jarmila Kuličková;Miroslav Maryško;Ondřej Kaman;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 6
Publisher: IEEE
 
» Magnetoelastic Properties of Epitaxially Grown Co2Fe0.4Mn0.6Si and Co2FeGa0.5Ge0.5 Heusler Alloys Thin Films
Abstract:
The out-of-plane magnetocrystalline anisotropy and magnetoelastic properties of series of epitaxially grown layers of Co2Fe0.4Mn0.6Si (CFMS) and Co2FeGa0.5Ge0.5 (CFGG) Heusler alloys thin films deposited on MgO with chromium buffer layer were investigated by means of the ferromagnetic resonance (FMR), SQUID magnetometer, and by the strain modulated FMR technique. The magnitude of the magnetocrystalline anisotropy constant was found to decrease with increasing layer thickness. The change of the anisotropy is caused mainly by the surface effects. However, for some of the samples series, the change of chemical ordering with the change of the magnetic layer thickness was also observed. An additional silver buffer layer influence on the properties of the magnetic layer was also investigated. For all three of the investigated series of the Heusler alloys, i.e., CFMS without Ag, CFMS with Ag, and CFGG, the experimentally observed magnitude of the magnetoelastic constant increases with the increase of the magnetic layer thickness.
Autors: O. M. Chumak;A. Nabiałek;R. Zuberek;I. Radelytskyi;T. Yamamoto;T. Seki;K. Takanashi;L. T. Baczewski;H. Szymczak;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 6
Publisher: IEEE
 
» Magnetoimpedance in Samples With Patterned Surfaces for the Detection of Magnetic Particles and Ferrofluids
Abstract:
Magnetoimpedance (MI) has been proposed as a sensible detection method for quantifying the concentration of magnetic microparticle and nanoparticle. The use of samples with severe surface roughness, induced by acid treatments, seems to enhance the detection power. Here, we clarify the role of surface modification in the detection of magnetic particles and ferrofluids. Experimentally, lithography is used to produce a regular pattern of pits in an amorphous ribbon. The influence of the patterning on the MI of the sample, in the presence of magnetic nanoparticles, is analyzed. Contrary to what has been published previously, the patterning seems to worsen the particle detection capability. To clarify the situation, a thorough study is performed with numerical simulations using a finite-element analysis resembling the experimental conditions in a 2-D geometry. The presence of magnetic particles is simulated as a continuum medium with a given permeability, which is a realistic assumption for the case for ferrofluids. The conclusion is that the effect of the magnetic particles on MI depends strongly on the characteristics of the patterning and on the concentration of particles. The simulation results not only qualitatively explain ours experimental results, but also help interpreting previous reports and hints the optimal conditions for the surface patterning in order to maximize the sensibility of the sample to the presence of magnetic particles.
Autors: Alfredo García-Arribas;Maite Goiriena-Goikoetxea;Eduardo Fernández;José Manuel Barandiarán;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 6
Publisher: IEEE
 
» Magnetorheology of Snowman-Like Anisotropic Microparticle Added Carbonyl Iron Suspension
Abstract:
The improvement of the magnetorheological (MR) performance of a carbonyl iron (CI)-based MR fluid was assessed by adding nonmagnetic anisotropic snowman-like polymethyl methacrylate (PMMA) particles as an additive. The snowman-like PMMA particles were synthesized by a seed emulsion polymerization method. The rheological properties of the MR fluids with and without the additives were examined by using a rotational rheometer under various applied magnetic-field strengths. Enhanced rheological properties and improved sedimentation stability of the CI/snowman-like PMMA-based MR fluid were observed compared to those of the pure CI-based MR fluid.
Autors: Ha Young Kim;Seung Hyuk Kwon;Hyoung Jin Choi;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetostriction Behaviors of Ni100−xFex and Ni100−yCoy (001) Single-Crystal Films with fcc Structure under Rotating Magnetic Fields
Abstract:
Ni100–xFex (x = 0, 20 at. %) and Ni100–yCoy (y = 0, 25, 50, 75, 100 at. %) alloy single-crystal films of fcc(001) orientation are prepared through hetero-epitaxial growth on Cu(001) single-crystal underlayers at 300 °C. The effects of Fe/Ni and Co/Ni compositions on the magnetic anisotropy and the magnetostriction behavior under rotating magnetic fields are investigated. The Ni single-crystal film shows a nearly isotropic in-plane magnetic property. The Ni80Fe20 and the Ni100–yCoy (y = 25–100) single-crystal films show four-fold symmetries in in-plane magnetic anisotropy. The easy magnetization direction is observed along [110] and [11 _ 0] for the Ni80Fe20 and the Ni100–yCoy (y = 50–100) films, whereas that is recognized along [100] and [010] for the Ni75Co25 film. The easy magnetization axis varies depending on the Co/Ni composition. The in-plane magnetic anisotropy increases with increasing the Co content. Triangular output waveforms of magnetostriction appear when the Ni80Fe20 and the Ni100–yCoy (y = 25–100) films are measured under low rotating magnetic fields. The magnetostriction behavior is related with the magnetization direction in a magnetically unsaturated film with inplane magnetic anisotropy. As the rotating magnetic field increases, the magnetization approaches saturation and the waveform gradually changes to a usual sinusoidal shape. As the in-plane anisotropy increases, a higher rotating field is required to obtain a sinusoidal waveform. On the contrary, sinusoidal waveforms are observed for the Ni film, even when the magnetization is not saturated. The waveform of magnetostriction is affected by the symmetry and the strength of in-plane magnetic anisotropy.
Autors: Kana Serizawa;Tetsuroh Kawai;Mitsuru Ohtake;Masaaki Futamoto;Fumiyoshi Kirino;Nobuyuki Inaba;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetotransport in Ultrathin 2-D Superconducting Mo2C Crystals
Abstract:
Ultrathin transition metal carbides are a class of emerging 2-D materials with many intriguing properties and applications. Here, we report the transport measurements on high-quality ultrathin Mo2C crystals, which are synthesized by a chemical vapor deposition method. We demonstrate 2-D nature of the observed superconductivity in ultrathin Mo2C crystals, being consistent with a Berezinskii–Kosterlitz–Thouless transition. As the sample thickness decreases, the Mo2C crystals exhibit negative magnetoresistance behavior at low magnetic fields deep in the superconducting state. We attribute these results to strong phase fluctuations of the superconducting order parameters near the superconductor–insulator transition. Our results demonstrate that these high-quality ultrathin Mo2C crystals provide an appealing platform to gain insights into 2-D superconductivity in a clean system.
Autors: Shuang Song;Libin Wang;Chuan Xu;Hui-Ming Cheng;Wencai Ren;Ning Kang;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Magnetron Coupling to Sulfur Plasma Bulb
Abstract:
Sulfur plasma lamps are a convenient, table-top system for the study of acoustics in dense, weakly ionized plasmas. Herein, we describe the construction and tuning of a passive waveguide circuit capable of igniting and sustaining the sulfur plasma and exciting acoustic modes within it.
Autors: John P. Koulakis;Alexander L. F. Thornton;Seth Putterman;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Nov 2017, volume: 45, issue:11, pages: 2940 - 2944
Publisher: IEEE
 
» Maintaining Balance: The Increasing Role of Energy Storage for Renewable Integration
Abstract:
For nearly a century, global power systems have focused on three key functions: generating, transmitting, and distributing electricity as a real-time commodity. Physics requires that electricity generation always be in real-time balance with load-despite variability in load on time scales ranging from subsecond disturbances to multiyear trends. With the increasing role of variable generation from wind and solar, the retirement of fossil-fuel-based generation, and a changing consumer demand profile, grid operators are using new methods to maintain this balance.
Autors: Derek Stenclik;Paul Denholm;Babu Chalamala;
Appeared in: IEEE Power and Energy Magazine
Publication date: Nov 2017, volume: 15, issue:6, pages: 31 - 39
Publisher: IEEE
 
» Making a Difference [From the Editor's Desk]
Abstract:
Presents the introductory editorial for this issue of the publication.
Autors: Lanny Floyd;
Appeared in: IEEE Industry Applications Magazine
Publication date: Nov 2017, volume: 23, issue:6, pages: 4 - 5
Publisher: IEEE
 
» Making Sense of the Ransomware Mess (and Planning a Sensible Path Forward)
Abstract:
It started out as a seemingly isolated event. Reports early during the morning of 12 May 2017 talked about an unknown piece of ransomware attacking systems within the British National Health System (NHS) hospital network. Well over 50,000 NHS systems were infected, forcing affected hospitals to divert pat ients to other facilities. As hours passed, however, it became clear that this event was not isolated, and systems spanning more than 150 countries quickly succumbed to what would come to be known as WannaCry (which is known by multiple names including WanaCry, WannaCrypt, and WannaCrypt0r, among others.)
Autors: Nolen Scaife;Patrick Traynor;Kevin Butler;
Appeared in: IEEE Potentials
Publication date: Nov 2017, volume: 36, issue:6, pages: 28 - 31
Publisher: IEEE
 
» Making the Leap to Electric Motors and Adjustable-Speed Drives: A Case Study of a 20,000-hp Gas Turbine-Driven Compressor
Abstract:
Compressors of all forms, types, and sizes are the workhorses of the oil and gas industry. Historically, the petrochemical industry has been dominated by mechanical prime movers, such as gas turbines, steam turbines, and diesel engines for multimegawatt rotating machinery. Some installations date back almost 40-50 years. In recent times, the prime movers have become difficult and expensive to service and maintain. They often have lower efficiencies than new equipment, and spare parts can be difficult to find. When U.S. Environmental Protection Agency (EPA) permits expire, and because strict emission compliance is mandatory, many end users face the challenging task of decommissioning their entire compressor train and procuring a new one. However, a workable and cost-effective solution is to retrofit existing mechanical-based prime movers while retaining the functioning gas compressor.
Autors: Manish Verma;Derrick Parker;Izhak Ike Grinbaum;James Nanney;
Appeared in: IEEE Industry Applications Magazine
Publication date: Nov 2017, volume: 23, issue:6, pages: 29 - 38
Publisher: IEEE
 
» MALM: Mobility-Aware Location Management Scheme in Femto/Macrocell Networks
Abstract:
Recently, femtocells are widely deployed to offload the traffic from the macrocell. Since conventional location management schemes of femto/macrocell networks do not consider mobility pattern of the mobile node (MN), unnecessary location updates can occur. Specifically, when an MN moves along the contour of the femtocell coverage, the MN frequently executes location update procedures, which causes significant location update cost. To address this problem, we propose a mobility-aware location management (MALM) scheme, where the MN conducts location update only at specific femtocells in which it is expected that the MN stays for a long time. To optimize MALM, a Markov decision process (MDP) problem is formulated and the optimal policy is determined. Evaluation results demonstrate that MALM with the optimal policy can reduce the number of location updates while providing sufficient offloading gain.
Autors: Haneul Ko;Jaewook Lee;Sangheon Pack;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Nov 2017, volume: 16, issue:11, pages: 3115 - 3125
Publisher: IEEE
 
» MAMR Frequency Selection on [CoX/Pt]4 Media
Abstract:
In microwave-assisted magnetic recording (MAMR), the frequency selection of the assisted microwave magnetic field is important. In this paper, we set up a micromagnetic model of [CoX/Pt]4 media with a different anisotropy configuration to study the frequency selection based on media signal-to-noise ratio (SNR) by the simulation of writing performance. By evaluating each layer’s SNR, we find that the four-layer integrated SNR- relationship is more influenced by the top two layers, and the interlayer exchange coupling strength plays a dominant role on the consistent SNR- curve in each media layer. When Hiec = 2000 Oe, the optimum frequency in each layer is coherent; when Hiec = 1000 Oe, the optimum frequency has a 2 GHz difference in four layers. When the average anisotropy field is in a range of 19–25 kOe, the integrated optimum frequency with highest media SNR increases versus with a slope of 1.87 GHz/kOe, smaller than the ferromagnetic resonant frequency coefficient of around 3 GHz/kOe, which is beneficial for MAMR applications. With optimized intergrain exchange strength and optimum frequency GHz, an areal writing density limit of 3 Tbit/in2 can be achieved.
Autors: Zhen Zhao;Dan Wei;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Manufacturing of Die-Upset Rare Earth–Iron–Boron Magnets With (Ce,La)-Mischmetal
Abstract:
Utilization of the relatively abundant and inexpensive (Ce,La)-mischmetal in manufacturing die-upset R–Fe–B magnets (R = rare earth) from melt-spun nanocrystalline alloys was attempted via: 1) the standard single-alloy process; 2) the diffusion of Nd and Pr from low-melting-temperature alloys blended into the magnet; and 3) the diffusion of Nd and Pr by infiltrating the magnet through its surface. No practically viable magnetic properties could be obtained without the introduction of Nd(Pr). Blending with the (Nd,Pr)-rich alloys was found to be less efficient for the development of coercivity than the single-alloy process; so was the infiltration of those precursors which had been alloyed with 0.5 at.% Ga. More efficient than the single-alloy process was infiltration of those precursors which had been alloyed with 2 at.% Si or with 1 at.% Zn. Coercivities of 7–10 kOe and energy products of 17–20 MGOe were obtained for magnets having 43%–55% of the R elements represented by Ce0.65La0.35 and containing overall 7.5–9.7 at.% Nd(Pr). The coercivity of the significantly hyper-stoichiometric (17–19 at.% R) (Ce,La)-containing alloys was found to decline 80% or more as a result of the deformation process, but partially recover after subsequent annealing. The latter improvement is likely to be caused by redistribution of the R-rich phases.
Autors: Alexander M. Gabay;George C. Hadjipanayis;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Maritime Traffic Probabilistic Forecasting Based on Vessels’ Waterway Patterns and Motion Behaviors
Abstract:
Maritime traffic prediction is critical for ocean transportation safety management. In this paper, we propose a novel knowledge assisted methodology for maritime traffic forecasting based on a vessel’s waterway pattern and motion behavior. The vessel’s waterway pattern is extracted through a proposed lattice-based DBSCAN algorithm that significantly reduces the problem scale, and its motion behavior is quantitatively modeled for the first time using kernel density estimation. The proposed methodology facilitates the knowledge extraction, storage, and retrieval, allowing for seamless knowledge transfer to support maritime traffic forecasting. By incorporating both the vessel’s waterway pattern and motion behavior knowledge, our solution suggests a set of probable coordinates with the corresponding probability as the forecasting output. The proposed forecasting algorithm is capable of accurately predicting maritime traffic 5, 30, and 60 min ahead, while its computation can be efficiently completed in milliseconds for single vessel prediction. Owing to such a high computational efficiency, an extensive predictive analysis of hundreds of vessels has been reported for the first time in this paper. A web-based prototype platform is implemented for Singapore waters to demonstrate the solution’s feasibility in a real-world maritime operation system. The proposed approaches can be generalized for other marine waters around the world.
Autors: Zhe Xiao;Loganathan Ponnambalam;Xiuju Fu;Wanbing Zhang;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: Nov 2017, volume: 18, issue:11, pages: 3122 - 3134
Publisher: IEEE
 
» MARTA GANs: Unsupervised Representation Learning for Remote Sensing Image Classification
Abstract:
With the development of deep learning, supervised learning has frequently been adopted to classify remotely sensed images using convolutional networks. However, due to the limited amount of labeled data available, supervised learning is often difficult to carry out. Therefore, we proposed an unsupervised model called multiple-layer feature-matching generative adversarial networks (MARTA GANs) to learn a representation using only unlabeled data. MARTA GANs consists of both a generative model and a discriminative model . We treat as a feature extractor. To fit the complex properties of remote sensing data, we use a fusion layer to merge the mid-level and global features. can produce numerous images that are similar to the training data; therefore, can learn better representations of remotely sensed images using the training data provided by . The classification results on two widely used remote sensing image databases show that the proposed method significantly improves the classification performance compared with other state-of-the-art methods.
Autors: Daoyu Lin;Kun Fu;Yang Wang;Guangluan Xu;Xian Sun;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 2092 - 2096
Publisher: IEEE
 
» Max–Min Fair Resource Allocation for SWIPT in Multi-Group Multicast OFDM Systems
Abstract:
Simultaneous wireless information and power transfer is considered for multi-group multicasting OFDM systems. Each user has the energy harvesting capability through a power splitter (PS). The power and subcarrier allocation at the base station is done such that the minimum signal-to-noise ratio among the users for each subcarrier is maximized while user needs for harvested power are satisfied. The optimization of PS ratios in addition to resource allocation is realized in a joint manner. It is shown that the problem can be cast in a convex optimization form for the given subcarrier sets. In order to determine the subcarrier sets, an efficient subcarrier allocation algorithm is proposed. It is shown that the proposed method performs very close to the exhaustive search, which gives the optimum solution.
Autors: Özlem Tuğfe Demir;Temel Engin Tuncer;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2508 - 2511
Publisher: IEEE
 
» Maximization of Wind Energy Utilization Through Corrective Scheduling and FACTS Deployment
Abstract:
The paper proposes a probabilistic methodology for minimizing wind spillage and maximizing capacity of the deployed wind generation, whilst improving system reliability. Capacities of the connected wind units are initially determined by using a method developed by the industry. A probabilistic approach is applied for the day-ahead planning to find maximum deployable wind sources so that the prescribed wind spillage is not exceeded. This is done using the optimum power flow, where wind spillages are prioritised with the probabilistic “cost coefficients.” Further improvement of wind energy utilization is achieved by installing FACTS devices and making use of real-time thermal ratings. Two ranking lists are developed to prioritize location of SVCs and TCSCs, and they are then combined into a unified method for best FACTS placement. The entire methodology is realized in two sequential Monte Carlo procedures, and the probabilistic results are compared with the state enumeration ones. Results show improved wind utilization, network reliability, and economic aspects.
Autors: Alexandra Kapetanaki;Victor Levi;Muhammad Buhari;Jonathan Alexandre Schachter;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4764 - 4773
Publisher: IEEE
 
» Maximum Likelihood Estimation of Optical Path Length in Spectral Interferometry
Abstract:
Optical path length demodulation is a subject of fundamental importance in spectral interferometry applications. We propose an algorithm based on maximum likelihood estimation to achieve absolute optical path length demodulation with high sensitivity and noise resistance and to elucidate the cause and behavior of undesirable demodulation discontinuity. From an interference spectrum model with additive Gaussian noise, a maximum likelihood estimator is derived in Fourier domain to determine the optical path length. To assess its sensitivity performance, the Cramer–Rao bound of sensitivity is derived from Fisher information matrix. By simulations and experimental validations, the proposed method demonstrates its capability of achieving the Cramer–Rao bound over a large dynamic range of optical path lengths, initial phases, and signal-to-noise ratios. When compared with some state-of-the-art demodulation methods, it also demonstrates improved resistance to demodulation jumps at low signal-to-noise ratios. Importantly, the mechanism of such jumps can be readily explained from a new, intuitive perspective, which may permit the quantification of jump occurrences in the future.
Autors: Chengshuai Li;Shichao Chen;Yizheng Zhu;
Appeared in: Journal of Lightwave Technology
Publication date: Nov 2017, volume: 35, issue:22, pages: 4880 - 4887
Publisher: IEEE
 
» Maximum Limit of Superconducting Persistent Current for Superconducting Magnetic Suspension System
Abstract:
Superconducting technique is applied to a superconducting magnetic suspension system. The suspension system is composed of a superconducting coil, a copper coil, a suspended object, a photo sensor, a PID controller, and power amplifiers. Persistent current in a superconducting coil and control current in a copper coil are used for suspending object and controlling object, respectively. In this paper, large-gap trial on the system is performed, and the static and dynamic characteristics of the suspended object are performed. As a result, it is found that the suspended object continues to suspend at a distance 43 mm for s. It is found that there is a maximum limit of superconducting persistent current for the system. The details of the superconducting persistent current are discussed. This may be the first trial that superconducting persistent current is used for a magnetic suspension system.
Autors: M. Komori;A. Minoda;K. Nemoto;K. Asami;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Mean Bit Error Rate Evaluation of MC-CDMA Cellular Systems Employing Multiuser-Maximum-Likelihood Detector
Abstract:
In this paper, we evaluate the uplink bit error rate (BER) of multicarrier-code-division-multiple-access (MC-CDMA) cellular systems with multiuser-maximum-likelihood detector (MU-MLD). The scenario considers perfect power control, own-cell interference (or multiple access interference—MAI), interference from co-cells (or co-cell interference—CCI), additive white Gaussian noise, exponential path-loss and slow frequency-selective Rayleigh fading. Upper bound expressions to evaluate the mean BER are obtained, which are functions of the signal-to-noise ratio (SNR), the number of users, the spreading factor, and the channel reuse factor. For BPSK and 4-QAM (quadrature amplitude modulation), closed-form expressions involving the analytical calculation of pairwise error probabilities are obtained. For 16-QAM and 64-QAM, we show that the number of pairwise error probabilities needed to obtain the BER can be simplified through the constellations symmetry. The procedure for obtaining this simplification is detailed. Also, by considering BER asymptotes, expressions for the SNR penalty due to MAI are derived. Monte Carlo simulations verify the analytical expressions accuracy. In the simulations, the MU-MLD is implemented through the sphere decoder algorithm with MMSE QR factorization. Results show that MC-CDMA does not lose diversity due to MAI. Moreover, CCI significantly affects the system performance. As a consequence, it produces floors in the BER curves.
Autors: Henry Ramiro Carvajal Mora;Nathaly Verónica Orozco Garzón;Celso de Almeida;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Nov 2017, volume: 66, issue:11, pages: 9838 - 9851
Publisher: IEEE
 
» Measurements of Sea Clutter at Low Grazing Angle in Mediterranean Coastal Environment
Abstract:
Results of a coastal measurement campaign called MediterraneAn Rfc and cLutter ENvironmental Experiment (MARLENE) are presented and studied. The campaign was held in spring 2014, on a DGA site in the Mediterranean Sea region of Toulon, France. Three coastal measurement radar systems, Millimeter wave Experimental Multifrequency Polarimetric High Resolution Interferometric System (Fraunhofer FHR), MARSIG (WTD 71), and MEDYCIS (ONERA), were deployed to simultaneously acquire sea clutter measurements. During the campaign, the in situ oceanic and meteorological conditions were characterized from the RV PLANET meteorological ship deployed by WTD 71 and by modeling from WAVEWATCH III and SWAN wave models. Radar measurements were performed at the C-, X-, Ku-, Ka-, and W-bands. The measurement results are presented in terms of reflectivity and mean Doppler spectrum according to low grazing angle and azimuth variations. Reflectivity variations are compared with the empirical GIT model and close results are obtained at the C- and Ka-bands. At the same frequency bands, mean Doppler Spectrum velocity is presented and analyzed according to grazing and azimuth angles. Physical interpretations of electromagnetic interaction with sea surface are discussed.
Autors: V. Fabbro;G. Biegel;J. Förster;J.-B. Poisson;A. Danklmayer;C. Böhler;J.-P. Marcellin;T. Brehm;M. Gallus;L. Castanet;A. Ulland;Y. Hurtaud;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6379 - 6389
Publisher: IEEE
 
» Measuring Scale-Up and Scale-Out Hadoop with Remote and Local File Systems and Selecting the Best Platform
Abstract:
MapReduce is a popular computing model for parallel data processing on large-scale datasets, which can vary from gigabytes to terabytes and petabytes. Though Hadoop MapReduce normally uses Hadoop Distributed File System (HDFS) local file system, it can be configured to use a remote file system. Then, an interesting question is raised: for a given application, which is the best running platform among the different combinations of scale-up and scale-out Hadoop with remote and local file systems. However, there has been no previous research on how different types of applications (e.g., CPU-intensive, data-intensive) with different characteristics (e.g., input data size) can benefit from the different platforms. Thus, in this paper, we conduct a comprehensive performance measurement of different applications on scale-up and scale-out clusters configured with HDFS and a remote file system (i.e., OFS), respectively. We identify and study how different job characteristics (e.g., input data size, the number of file reads/writes, and the amount of computations) affect the performance of different applications on the different platforms. Based on the measurement results, we also propose a performance prediction model to help users select the best platforms that lead to the minimum latency. Our evaluation using a Facebook workload trace demonstrates the effectiveness of our prediction model. This study is expected to provide a guidance for users to choose the best platform to run different applications with different characteristics in the environment that provides both remote and local storage, such as HPC cluster and cloud environment.
Autors: Zhuozhao Li;Haiying Shen;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Nov 2017, volume: 28, issue:11, pages: 3201 - 3214
Publisher: IEEE
 
» Measuring Target Range and Velocity: Developments in Chip, Antenna, and Packaging Technologies for 60-GHz and 122-GHz Industrial Radars
Abstract:
Increasing demand for industrial radars has spurred research aimed toward designing better transceiver (TRx) integrated circuits (ICs) combined with advanced packaging technologies [1]-[6], innovative antenna concepts, very precise wirebonding schemes [5]-[8], and high-performance baseband processing systems [9]. With a well-optimized package of such products, the resulting application fields can vary from avionics and robotics to automotive, monitoring, level-tracking, and vital-sign-detection systems, among many others. All these applications will require that the final product satisfy certain metrics such as range, resolution, accuracy, power consumption, and (as always) production cost, which is ultimately the most crucial criterion.
Autors: Efe Ozturk;Dieter Genschow;Uroschanit Yodprasit;Berk Yilmaz;Dietmar Kissinger;Wojciech Debski;Wolfgang Winkler;
Appeared in: IEEE Microwave Magazine
Publication date: Nov 2017, volume: 18, issue:7, pages: 26 - 39
Publisher: IEEE
 
» Medical Optical Imaging: Signal Processing Leads to New Methods of Detecting Life-Threatening Situations [Special Reports]
Abstract:
Autors: John Edwards;
Appeared in: IEEE Signal Processing Magazine
Publication date: Nov 2017, volume: 34, issue:6, pages: 17 - 20
Publisher: IEEE
 
» Medium Stack Optimization for Microwave-Assisted Magnetic Recording
Abstract:
In this paper, we present systematic micromagnetic modeling investigation on recording process of segmented thin-film media with circularly polarized magnetic field at microwave frequencies. This paper provides insightful understanding about the segmented medium stack design in microwave-assisted magnetic recording (MAMR) by exploring the impact of signal-to-noise (SNR) ratio and recording track width. By utilizing segmentation of grains with exchange breaking layers, the ac magnetic field generated from spin torque oscillator can be best exploited. Via optimized medium stack design, MAMR is able to achieve both high SNR and areal density gain with the proposed notched-structure medium (top and bottom segments have the strongest crystalline anisotropy) compared with conventional graded medium (with gradually increasing anisotropy from top to bottom). By tuning crystalline anisotropy strength in top and bottom segment, we studied the MAMR behavior of SNR and track width under different ac frequencies. This provides a novel view for future segmented media design.
Autors: Xiaoyu Bai;Jian-Gang Zhu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Medium-Resolution Soil Moisture Retrieval Using the Bayesian Merging Method
Abstract:
The National Aeronautics and Space Administration’s Soil Moisture Active Passive (SMAP) mission, launched in January 2015, was designed to provide a global soil moisture product at medium resolution (~9 km), by combining observations from its radar and radiometer. Several downscaling methods have been proposed by the SMAP team for this purpose. This paper evaluates another candidate downscaling method, namely, the Bayesian merging approach. While this has been tested using a synthetic data set across the USA, it is imperative that it can also be tested using the experimental data for a comprehensive range of land surface conditions (i.e., in different hydro-climatic regions) prior to a global application. Consequently, this paper applies this method using the data collected from SMAP experiments field campaigns in south-eastern Australia that closely simulated the SMAP data stream for a single SMAP radiometer pixel over a three-week interval. The method studied here differs from the linear downscaling methods of the SMAP mission, in that it uses a nonlinear method based on Bayes’ theorem. The medium-resolution soil moisture product is obtained using background soil moisture estimates that are updated according to the difference between the observed and predicted brightness temperatures and backscatter coefficients, relating the high- and low-resolution data. Results were assessed against a reference soil moisture map derived from high-resolution airborne radiometer observations. The root-mean-square-error and for the Bayesian merging method were found to be 0.02 cm3/cm3 and 0.55, respectively, at 9-km resolution, being similar to the SMAP’s “optional” downscaling method.
Autors: Xiaoling Wu;Jeffrey P. Walker;Christoph Rüdiger;Rocco Panciera;Ying Gao;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6482 - 6493
Publisher: IEEE
 
» Meetings calendar
Abstract:
Provides a listing of future meetings.
Autors: Davide Fabiani;
Appeared in: IEEE Electrical Insulation Magazine
Publication date: Nov 2017, volume: 33, issue:6, pages: 61 - 63
Publisher: IEEE
 
» Memory-in-Pixel Circuit for Low-Power Liquid Crystal Displays Comprising Oxide Thin-Film Transistors
Abstract:
We propose a new memory-in-pixel (MIP) circuit with only oxide thin-film transistors (Ox-TFTs) for a low-power liquid crystal display with flicker-free feature. The proposed MIP circuit is composed of two new memory circuit units comprising two Ox-TFTs and a capacitor. The proposed memory circuit can modulate the threshold voltage via a simple driving scheme. When the threshold voltage is shifted properly, Ox-TFTs maintain the ON or OFF state by virtue of their extra low leakage current, which enables the MIP operation. By applying the black or white voltage to the pixel directly, flicker can be eliminated. We fabricated the MIP circuit and investigated the circuit performance depending on the capacitance and TFT sizes. Finally, we verified the feasibility of the proposed MIP circuit for low power operation.
Autors: Seung-Hyuck Lee;Byung-Chang Yu;Hoon-Ju Chung;Seung-Woo Lee;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1551 - 1554
Publisher: IEEE
 
» Merge Mode for Deformable Block Motion Information Derivation
Abstract:
Motion estimation (ME) plays an important role in most video coding standards since it can improve the coding performance significantly. Block matching ME (BMME) based on translation motion model is employed in both H.264/Advanced Video Coding and High Efficiency Video Coding (HEVC), which assumes that all the pixels in a block undergo the same motion. However, BMME cannot represent the complex motion accurately, such as rotation, zoom, and deformation motion. To resolve the problem, a merge mode for deformable block motion information derivation is proposed, which considers bilinear interpolation model, six-parameter affine model, and four-parameter affine model simultaneously. The sum of absolute transformed differences criterion is used to select the best model for a block. In the proposed merge mode, the motion information of the current block is derived from the motion information of its neighbors. It does not need to perform ME and transmit motion parameters. The proposed merge mode is integrated into HEVC test model (HM) 14.0. The simulation results show that compared with HM14.0, the proposed merge mode can bring 1.3%, 1.7%, and 2.7% Bjøntegaard delta (BD) bitrate savings on average for test sequences of HEVC, and 11.0%, 15.2%, and 17.4% BD bitrate savings for deformation sequences in random access main, low-delay B main, and low-delay P main test conditions, respectively, while the increased encoding and decoding complexities are moderate.
Autors: Na Zhang;Xiaopeng Fan;Debin Zhao;Wen Gao;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Nov 2017, volume: 27, issue:11, pages: 2437 - 2449
Publisher: IEEE
 
» meSchup: A Platform for Programming Interconnected Smart Things
Abstract:
In a future where hundreds of smart networked devices will be embedded in our everyday environments, the question of how to program the world around us arises. An abstraction layer and web-based integrated development environment can interweave available smart things’ capabilities into a collective orchestration of smart behavior.
Autors: Thomas Kubitza;Albrecht Schmidt;
Appeared in: Computer
Publication date: Nov 2017, volume: 50, issue:11, pages: 38 - 49
Publisher: IEEE
 
» Metal Sulfates Enhanced Plasma Oxidization of Diesel Particulate Matter
Abstract:
The activities for nonthermal plasma-induced oxidation of diesel particulate matter (DPM) with various metal sulfates were investigated. It was found that the metal sulfates, MgSO4, K2SO4, and CaSO42H2O, enhanced the energy yield of DPM oxidation while other sulfates, Na2SO4, Fe2(SO4)3, and Al2(SO4)8H2O, did not affect the energy yield. The addition of water vapor caused a promotion of DPM oxidation regardless of a metal sulfate was presented. The effect of temperature and sulfate adding amount was also investigated. The metal sulfates enhanced DPM oxidation is possibly due to the adsorption of O atoms onto the sulfates. The positive effects of H2O might be thought of as due to the formation of reactive OH radicals and the promotion of the hydrolysis of the oxygen-containing compounds on DPM surface.
Autors: Shuiliang Yao;Xing Shen;Haiquan Lu;Danwei Ni;Xiujuan Tang;Zuliang Wu;Jingyi Han;Xuming Zhang;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Nov 2017, volume: 45, issue:11, pages: 2984 - 2987
Publisher: IEEE
 
» Method for Simulating Dose Reduction in Digital Breast Tomosynthesis
Abstract:
This paper proposes a new method of simulating dose reduction in digital breast tomosynthesis, starting from a clinical image acquired with a standard radiation dose. It considers both signal-dependent quantum and signal-independent electronic noise. Furthermore, the method accounts for pixel crosstalk, which causes the noise to be frequency-dependent, thus increasing the simulation accuracy. For an objective assessment, simulated and real images were compared in terms of noise standard deviation, signal-to-noise ratio (SNR) and normalized noise power spectrum (NNPS). A two-alternative forced-choice (2-AFC) study investigated the similarity between the noise strength of low-dose simulated and real images. Six experienced medical physics specialists participated on the study, with a total of 2 160 readings. Objective assessment showed no relevant trends with the simulated noise. The relative error in the standard deviation of the simulated noise was less than 2% for every projection angle. The relative error of the SNR was less than 1.5%, and the NNPS of the simulated images had errors less than 2.5%. The 2-AFC human observer experiment yielded no statistically significant difference (=0.84) in the perceived noise strength between simulated and real images. Furthermore, the observer study also allowed the estimation of a dose difference at which the observer perceived a just-noticeable difference (JND) in noise levels. The estimated JND value indicated that a change of 17% in the current-time product was sufficient to cause a noticeable difference in noise levels. The observed high accuracy, along with the flexible calibration, make this method an attractive tool for clinical image-based simulations of dose reduction.
Autors: Lucas R. Borges;Igor Guerrero;Predrag R. Bakic;Alessandro Foi;Andrew D. A. Maidment;Marcelo A. C. Vieira;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Nov 2017, volume: 36, issue:11, pages: 2331 - 2342
Publisher: IEEE
 
» Metrics and Quantification of Operational and Infrastructure Resilience in Power Systems
Abstract:
Resilience to high impact low probability events is becoming of growing concern, for instance to address the impacts of extreme weather on critical infrastructures worldwide. However, there is, as yet, no clear methodology or set of metrics to quantify resilience in the context of power systems and in terms of both operational and infrastructure integrity. In this paper, the resilience “trapezoid” is therefore introduced which extends the resilience “triangle” that is traditionally used in existing studies, in order to consider the different phases that a power system may experience during an extreme event. The resilience trapezoid is then quantified using time-dependent resilience metrics that are specifically introduced to help capture the critical system degradation and recovery features associated to the trapezoid for different temporal phases of an event. Further, we introduce the concepts of operational resilience and infrastructure resilience to gain additional insights in the system response. Different structural and operational resilience enhancement strategies are then analyzed using the proposed assessment framework, considering single and multiple severe windstorm events that hit the 29-bus Great Britain transmission network test case. The results clearly highlight the capability of the proposed framework and metrics to quantify power system resilience and relevant enhancement strategies.
Autors: Mathaios Panteli;Pierluigi Mancarella;Dimitris N. Trakas;Elias Kyriakides;Nikos D. Hatziargyriou;
Appeared in: IEEE Transactions on Power Systems
Publication date: Nov 2017, volume: 32, issue:6, pages: 4732 - 4742
Publisher: IEEE
 
» mHealth Dipstick Analyzer for Monitoring of Pregnancy Complications
Abstract:
Dipstick-based urinalysis is routinely used for the detection of early signs of such pregnancy complications, as preeclampsia and gestational diabetes. Usually it is done in doctor’s office using an automatic dipstick analyzer. Here, we present a novel smartphone-based colorimeter and demonstrate its application to the measurements of glucose and protein concentrations in biological samples. The key innovations of our approach was to combine powerful image processing encoded into a mobile phone application with a low cost 3-D printed sample holder that allowed to control lighting conditions and significantly improved sensitivity. Different solutions with protein and glucose concentrations ranging from 0 to 2000 mg/dL were prepared and analyzed using our system. The detection limit for glucose was 40 mg/dL and for protein −6mg/dL The smartphone-based colorimeter always correctly classified the corresponding reagent strip pads, what confirms that it can be used as a low cost alternative for commercial dipstick analyzers.
Autors: Karthik Raj Konnaiyan;Surya Cheemalapati;Michael Gubanov;Anna Pyayt;
Appeared in: IEEE Sensors Journal
Publication date: Nov 2017, volume: 17, issue:22, pages: 7311 - 7316
Publisher: IEEE
 
» Micro-Focused Pulse Laser-Induced Propagating Spin Waves in Permalloy Films With Different Thicknesses
Abstract:
Propagating spin waves excited by a micro-focused ultra-short pulse laser were investigated in Permalloy films with the thicknesses of 20, 50, and 100 nm by means of an all-optical space-and-time-resolved magneto-optical Kerr effect. Although various perpendicular standing spin-wave modes were excited, the propagating magneto-static surface spin wave was clearly detected in each film, where the group velocities of approximately 4, 8, and 12 km/s and the propagation lengths of 3.8, 6.6, and 13 for the 20, 50, and 100 nm-thick films, respectively, were evaluated. The evaluated group velocities were consistent with the theoretical values, whereas the propagation lengths were smaller than the theoretical values with the Gilbert damping constant of 0.008.
Autors: Akira Kamimaki;Satoshi Iihama;Yuta Sasaki;Yasuo Ando;Shigemi Mizukami;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Microbubble Axial Localization Errors in Ultrasound Super-Resolution Imaging
Abstract:
Acoustic super-resolution imaging has allowed the visualization of microvascular structure and flow beyond the diffraction limit using standard clinical ultrasound systems through the localization of many spatially isolated microbubble signals. The determination of each microbubble position is typically performed by calculating the centroid, finding a local maximum, or finding the peak of a 2-D Gaussian function fit to the signal. However, the backscattered signal from a microbubble depends not only on diffraction characteristics of the waveform, but also on the microbubble behavior in the acoustic field. Here, we propose a new axial localization method by identifying the onset of the backscattered signal. We compare the accuracy of localization methods using in vitro experiments performed at 7-cm depth and 2.3-MHz center frequency. We corroborate these findings with simulation results based on the Marmottant model. We show experimentally and in simulations that detecting the onset of the returning signal provides considerably increased accuracy for super-resolution. Resulting experimental cross-sectional profiles in super-resolution images demonstrate at least 5.8 times improvement in contrast ratio and more than 1.8 times reduction in spatial spread (provided by 90% of the localizations) for the onset method over centroiding, peak detection, and 2-D Gaussian fitting methods. Simulations estimate that these latter methods could create errors in relative bubble positions as high as at these experimental settings, while the onset method reduced the interquartile range of these errors by a factor of over 2.2. Detecting the signal onset is, therefore, expected to considerably improve the accuracy of super-resolution.
Autors: Kirsten Christensen-Jeffries;Sevan Harput;Jemma Brown;Peter N. T. Wells;Paul Aljabar;Christopher Dunsby;Meng-Xing Tang;Robert J. Eckersley;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Nov 2017, volume: 64, issue:11, pages: 1644 - 1654
Publisher: IEEE
 
» Micromagnetic Analysis of Statistical Switching in Perpendicular STT-MRAM With Interfacial Dzyaloshinskii–Moriya Interaction
Abstract:
The technological implementation of STT-magnetic random-access memory (MRAM) in real devices needs a complete description of the statistical switching behavior at room temperature. In this paper, we investigate, by means of a full micromagnetic model, the effect of the interfacial Dzyaloshinskii–Moriya interaction (IDMI) on the critical current density and probability density function (PDF) of the switching time in perpendicular STT-MRAMs. We show that for large enough values of the symmetric exchange interaction, the negative effect of the IDMI on the critical current is strongly reduced. In addition, a comprehensive analysis of the four main statistical moments (mean, standard deviation, skewness, and kurtosis) points out that to fit the switching time PDF in order to maintain a quadratic error at least one order of magnitude smaller than skew normal PDF, a Pearson type IV PDF has to be used also in presence of the IDMI.
Autors: G. Siracusano;R. Tomasello;V. Puliafito;A. Giordano;B. Azzerboni;A. La Corte;P. Burrascano;G. Finocchio;M. Carpentieri;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Micromagnetic Model Analysis of Various Spin-Torque Oscillators With Write Head for Microwave-Assisted Magnetic Recording
Abstract:
A micromagnetic model analysis was carried out considering two types of write heads and three types of spin-torque oscillators (STOs). For write heads, we considered a small-sized head to reduce calculation time and a large-sized head with dimensions close to commercial heads. For STOs, we used a double-layered STO with reflection spin torque, a double-layered STO with transmission spin torque, and a tri-layered STO with two spin injection layers. We also carried out micromagnetic simulations of the STOs without the write heads (isolated STO) to compare the oscillation states. It was found that, compared with isolated STOs in a uniform applied field, a larger applied field was necessary for STOs integrated into a write head. This result shows that the write head should be designed to generate a large, well-shaped gap field to ensure stable STO oscillation.
Autors: Yasushi Kanai;Ryo Itagaki;Simon J. Greaves;Hiroaki Muraoka;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Micromagnetic Simulation of Microwave-Assisted Magnetization Switching Process for Granular Films
Abstract:
Microwave-assisted magnetization switching (MAS) processes for granular films were demonstrated by time integration of the Landau–Lifshitz–Gilbert equation. At low microwave frequencies, hysteresis loops become narrower, and at higher frequencies, an extra step occurs in the curves. In the case when the extra step occurs, saturation field increases to be comparable to that for non-MAS case, although switching field decreases. The occurrence of the extra step possibly originates from “unstable switching process” predicted by Bertotti et al., and the magnetization contour maps indicated large un-switched agglomerates remains when MAS proceeds through the unstable switching process. The unstable switching processes are also observed even when dc incident angles are large.
Autors: Terumitsu Tanaka;Yukio Nozaki;Kimihide Matsuyama;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Micromagnetic Simulations for Coercivity Improvement Through Nano-Structuring of Rare-Earth-Free L10-FeNi Magnets
Abstract:
In this paper, we investigate the potential of tetragonal L10-ordered FeNi as the candidate phase for rare-earth-free permanent magnets considering anisotropy values from recently synthesized, partially ordered FeNi thin films. In particular, we estimate the maximum energy product (BH)max of L10-FeNi nanostructures using micromagnetic simulations. The maximum energy product is limited due to the small coercive field of partially ordered L10-FeNi. Nano-structured magnets consisting of 128 equi-axed, platelet-like, and columnar-shaped grains show a theoretical maximum energy product of 228, 208, and 252 kJm, respectively.
Autors: Alexander Kovacs;Johann Fischbacher;Harald Oezelt;Thomas Schrefl;Andreas Kaidatzis;Ruslan Salikhov;Michael Farle;George Giannopoulos;Dimitris Niarchos;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 5
Publisher: IEEE
 
» Micromagnetic Simulations of Magnetization Spatial Distribution in Ultrathin Cobalt Layers With Gradient Magnetic Anisotropy
Abstract:
Spatial distribution of magnetization in an ultrathin ferromagnetic Co layer with a lateral gradient of magnetic anisotropy, while approaching spin reorientation transition (SRT) (from perpendicular to in-plane magnetization alignment), has been investigated by means of micromagnetic simulations in the 2-D mode, using OOMMF software. The geometry of the out-of-plane-magnetized domains (parallel stripes, labyrinth, and bubbles) has been found to be dependent on both the initial distribution of magnetization and the direction of the applied magnetic field. A fast decrease in the domain size has been observed while moving toward SRT. In the experiment, Pt/Co/Pt layers with initial in-plane magnetization orientation have been irreversibly modified by femtosecond laser pulses. In the irradiated spot, rings with induced perpendicular magnetic anisotropy have been formed, resulting in an appearance of several local SRTs. Magnetic domain structure in the SRT regions has been visualized using magnetic force microscopy. The experimental observations are qualitatively explained by the results of the micromagnetic simulations.
Autors: Marek Kisielewski;Jan Kisielewski;Iosif Sveklo;Andrzej Wawro;A. Maziewski;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Micromagnetic Studies at Finite Temperature on FePt–C Granular Films
Abstract:
A new micromagnetic method using the hybrid Monte Carlo (HMC) algorithm has been developed, and the magnetic properties at finite temperature can be simulated. In this paper, the HMC micromagnetics are applied on the polycrystalline FePt–C granular films for heat-assisted magnetic recording, where the significant parameters such as the temperature-dependent saturation magnetization (T) are measured by experiments. The Voronoi polycrystalline microstructure is built upon a regular mesh of micromagnetic cells. The magnetization (M–H) loops below the Curie temperature are calculated; they agree well with experiments at 300, 400, 500, and 600 K, respectively, which have confirmed the validity of the HMC micromagnetic method. Besides, the M–H loop at 700 K, which currently cannot be measured by experiments, can also be simulated using the HMC algorithm, which shows superparamagnetic properties.
Autors: Junjie Song;J. Wang;Dan Wei;Y. K. Takahashi;K. Hono;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Micromagnetic Studies of Time-Dependent Coercivity
Abstract:
This paper has studied the time-dependent coercivity in both the constant-field model and changing-field model, based on a new micromagnetic method at finite temperature using the hybrid Monte Carlo (HMC) algorithm. By comparing the simulated time-dependent coercivity with Sharrock’s law, the scaling relationship between the fictitious simulation time in the Hamilton equations in the HMC micromagnetics and the real time t is derived, and the simulation time in a trajectory () is found to be close to 1 ns in the real-time scale. Furthermore, we have studied the effects of the magnetic anisotropy types on the parameter in Sharrock’s law, and it is found that the cubic anisotropy model exhibits a larger value than the uniaxial anisotropy model. Our simulation results agree well with the experiments and the results from other simulation methods under certain circumstances.
Autors: Jingyue Miao;Dan Wei;Chuan Liu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Microstructural Analysis During the Step-Cooling Annealing of Iron-Rich Sm(Co0.65Fe0.26Cu0.07Zr0.02)7.8 Anisotropic Sintered Magnets
Abstract:
Microstructural analysis during the step-cooling procedure of iron-rich Sm(Co0.65Fe0.26Cu0.07Zr0.02)7.8 anisotropic sintered magnets was investigated systematically. The sintered magnet exhibits the maximum energy product of about 32 MGOe together with a remanence of about 11.5 kGs. It is found that the cellular structure has formed at the stage of isothermal annealing (heat treating at 1103 K for 20 h). Moreover, the average cell size of the 2:17 cell phase in magnets decreases from ~150 to ~105 nm, and the density of the lamella phase increases from ~0.03 to ~0.05 1/nm during the step-cooling procedure. It is also found that the Cu concentration is homogeneous in the specimen quenched at a temperature of 1103 K and then becomes nonuniform, especially enriched in the cell boundaries during the step cooling to 873 K. Interestingly, the typical twining structure along the [010] zone of the main phase exists in the specimen quenched at 873 K. Furthermore, it is inferred that the magnetization mechanism of the specimens transforms from the nucleation-dominated type to the coexisting type of pinning and nucleation effect during the step-cooling procedure.
Autors: Kuikui Song;Yikun Fang;Wei Sun;Hongsheng Chen;Nengjun Yu;Minggang Zhu;Wei Li;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Microstructure and Magnetic Properties of CoFe Nanowires and Helical Nanosprings
Abstract:
Magnetic nanosprings have applications in various fields, e.g., in sensors, actuators, and biomedical applications. However, it is difficult to synthesize them due to their complicated structure. Here, we report the synthesis of CoFe nanosprings by electrodeposition using vanadium oxide ions and ascorbic acid. The nanosprings have a helical structure and exist in the form of the Co53Fe47 alloy. Hysteresis curves of CoFe nanowire and nanospring arrays show soft ferromagnetic characteristics. The CoFe nanowires have shape anisotropy with an easy axis parallel to the array direction, whereas the CoFe nanosprings exhibit an isotropic behavior.
Autors: Da Yeon Nam;Su Hyo Kim;Yoo Sang Jeon;Young Keun Kim;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Microstructure and Magnetic Properties of Recycled Nd–Fe–B Magnets with Blending of Ce-Rich Alloy
Abstract:
Waste Nd–Fe–B sintered magnets (grade 33H) were recycled to manufacture anisotropic sintered magnets by adding Ce-rich alloys. The influences of additive amounts of Ce-rich alloys on the microstructure and magnetic properties of the recycled sintered magnets were investigated. It showed that the recycled sintered Nd–Fe–B magnet without Ce-rich alloy addition has rather lower density; the density of the magnet is slightly raised with increased sintering temperature, but the recycled magnet is prone to oxidation, even cracking. For recycled sintered magnets with Ce-rich alloy addition, the densities of the magnets are upgraded with increasing amounts of Ce-rich alloy, and the magnetic properties are obviously improved. This suggests that Ce-rich alloy plays the important role of sintering-aid in the densification of the recycled magnet. However, the coercivity () of the recycled magnets is decreased, when the additive amounts of Ce-rich alloy are over 8 wt.%. This is probably because excessive Ce-rich alloy addition can cause RE-rich phase aggregation at the triple grain boundary junctions, and deteriorate the microstructure of the recycled magnets. The recycled magnet with 5 wt.% Ce-rich alloy, sintered at 1080 °C, exhibits the following optimal magnetic properties: of 11.67 kGs; of 18.94 kOe; and maximum energy product of 33.1 MGOe. The magnetic properties of the recycled magnets are comparative to those of the waste magnets. Recycled magnets have a hi- her coercivity and perfect squareness of demagnetization curve ().
Autors: Haibo Feng;Yueming Zhang;Anhua Li;Yang Zhao;Wei Li;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Microwave Passive Ground-Based Retrievals of Cloud and Rain Liquid Water Path in Drizzling Clouds: Challenges and Possibilities
Abstract:
Satellite and ground-based microwave radiometers are routinely used for the retrieval of liquid water path (LWP) under all atmospheric conditions. The retrieval of water vapor and LWP from ground-based radiometers during rain has proved to be a difficult challenge for two principal reasons: the inadequacy of the nonscattering approximation in precipitating clouds and the deposition of rain drops on the instrument’s radome. In this paper, we combine model computations and real ground-based, zenith-viewing passive microwave radiometer brightness temperature measurements to investigate how total, cloud, and rain LWP retrievals are affected by assumptions on the cloud drop size distribution (DSD) and under which conditions a nonscattering approximation can be considered reasonably accurate. Results show that until the drop effective diameter is larger than ~200 , a nonscattering approximation yields results that are still accurate at frequencies less than 90 GHz. For larger drop sizes, it is shown that higher microwave frequencies contain useful information that can be used to separate cloud and rain LWP provided that the vertical distribution of hydrometeors, as well as the DSD, is reasonably known. The choice of the DSD parameters becomes important to ensure retrievals that are consistent with the measurements. A physical retrieval is tested on a synthetic data set and is then used to retrieve total, cloud, and rain LWP from radiometric measurements during two drizzling cases at the atmospheric radiation measurement Eastern North Atlantic site.
Autors: Maria P. Cadeddu;Roger Marchand;Emiliano Orlandi;David D. Turner;Mario Mech;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Nov 2017, volume: 55, issue:11, pages: 6468 - 6481
Publisher: IEEE
 
» Microwave Signatures of Snow Cover Using Numerical Maxwell Equations Based on Discrete Dipole Approximation in Bicontinuous Media and Half-Space Dyadic Green's Function
Abstract:
A three-dimensional snowpack scattering and emission model is developed by numerically solving Maxwell's equations (NMM3D) over the entire snowpack on an underlying half-space. The solutions are crucial to microwave remote sensing that requires the preservation of coherent phase information. The heterogeneous snowpack is represented as a bicontinuous medium. Effects of the underlying half-space are included through a half-space Green's function in a volume integral equation formulation. The volume integral equation is then solved using the discrete dipole approximation. The fast Fourier transform is effectuated for all three dimensions with half-space Green's function rather than the conventional free space Green's function. To overcome the snow volume truncation in the finite numerical calculations, periodic boundary conditions are applied in the lateral extent. Thus, in NMM3D, the physical microwave scattering and emission problem is solved without using any radiative transfer equations. In this formulation, the scattering matrix of the snowpack accounts for both the magnitude and phase. The NMM3D simulations are demonstrated at Ku-band frequency for a snow cover up to 25-cm thick. The results are applicable to remote sensing of snow over sea ice, and thin layers of terrestrial snow. Quantitative values of backscattering and bistatic scattering coefficients are derived for active microwave remote sensing, and brightness temperatures for passive microwave remote sensing. The full wave simulation results are compared with those of the partially coherent approach of the dense media radiative transfer (DMRT). The NMM3D results capture effects of backscattering enhancement and coherent layering that are missed in DMRT. The full wave solution to Maxwell equations is important to advance radar polarimetry, interferometry, and tomography that require the preservation of the full - hase information and all interface interactions for applications to radar remote sensing of snow cover on land and on sea ice.
Autors: Shurun Tan;Jiyue Zhu;Leung Tsang;Son V. Nghiem;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: Nov 2017, volume: 10, issue:11, pages: 4686 - 4702
Publisher: IEEE
 
» Middle Managers’ Engagement in Autonomous Strategic Actions: Does It Really Matter How Top Managers Use Budgets?
Abstract:
Fostering middle managers’ entrepreneurial behavior is a key concern for established firms. Budgets are one of the most widely used management tools in organizations, and several conceptual articles claim that the way in which they are used, most notably in an interactive way, affects middle managers’ autonomous strategic actions (ASA). This type of entrepreneurial behavior in established firms focuses on opportunities outside the firms’ currently served product-market domains. Using structural equation modeling and a formative measurement instrument for interactive use of budgets, we test these claims advanced in conceptual literature within a broad sample of large firms. We find that the way in which budgets are used does not significantly impact middle managers’ engagement in ASA. In contrast, firms’ boundary systems and middle managers’ autonomy seem important antecedents to ASA.
Autors: Stefan Linder;Simon S. Torp;
Appeared in: IEEE Transactions on Engineering Management
Publication date: Nov 2017, volume: 64, issue:4, pages: 450 - 463
Publisher: IEEE
 
» Millimeter Wave Plasma Formation Within a 2D Photonic Crystal
Abstract:
Experiments demonstrate gas breakdown within a single point defect in a 2D photonic crystal at millimeter wave frequencies (43.44 GHz) using only 1.5 W of continuous wave input power. We show that after formation of the plasma within the defect, the transmission of energy through the crystal is decreased by two to four orders of magnitude for gas pressures from 30 to 750 torr. Time domain measurements of the transmitted energy through the device show plasma formation times ranging from 800 ns at 45 torr to 180 ns at 400 torr of argon gas. Electron density of the plasma is 1018 m−3 at low pressures and up to 1020 m−3 at 750 torr.
Autors: Stephen G. Parsons;Jeffrey Hopwood;
Appeared in: IEEE Electron Device Letters
Publication date: Nov 2017, volume: 38, issue:11, pages: 1602 - 1605
Publisher: IEEE
 
» Millimeter Wave Resistance of Metal-Dielectric $text{Co}_{rm x}(text{SiO}_{2})_{rm{1-x}}$ and $text{Co}_{rm x}(text{Al}_{2}text{O}_{3})_{rm{1-x}}$ Films
Abstract:
Transmission and reflection of millimeter waveband electromagnetic waves have been studied for thin-film metal-dielectric and nanocomposite materials, where cobalt nanoparticles are placed inside or films of 100 nm thickness. The microwave properties of the nanocomposite samples with different cobalt content have been measured in the frequency ranges from 26 to 38 GHz and from 53 to 77 GHz. Frequency dependencies of transmission and reflection coefficients have been measured. Power loss in the samples has been determined. An algorithm for recovering the conductivity from the frequency dependencies of the transmission and reflection coefficients has been worked out. It has been found that the microwave conductivity increases with increasing cobalt content and differs drastically from the dc conductivity. The obtained results have been compared to the actual measurements of magnetic properties.
Autors: Anatoly B. Rinkevich;Dmitry V. Perov;Vladimir O. Vaskovsky;Alexandr N. Gorkovenko;Evgeny A. Kuznetsov;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: Nov 2017, volume: 16, issue:6, pages: 1067 - 1072
Publisher: IEEE
 
» Miniature Tri-Axis Magnetometer With In-Plane GMR Sensors
Abstract:
A miniature tri-axis magnetometer with in-plane giant magnetoresistance (GMR) sensors and a fluxguide was designed, implemented, and characterized in this paper. Three GMR sensor dies were aligned on a printed circuit board with their sensing directions in the same plane. By using the flux bending effect of a fluxguide, the magnetic field components in the mounting plane of GMR sensors were generated, and hence, the effective sensing directions are not in the same plane. The tilt of effective sensing direction from the mounting plane allows the device to detect the out-of-plane field component. When the device was used as an electronic compass, the digitally demodulated sensor outputs were converted into the orthogonal geomagnetic field components by using a real-time conversion process with the voltage-to-field transfer matrix. The result shows that the device is suitable for compass application. Further works to implement the similar design on a CMOS chip with integrated GMR elements and a planar modulation coil will realize a compact and easy-to-fabricate tri-axis magnetic field sensor.
Autors: Xuan-Thang Trinh;Jen-Tzong Jeng;Chih-Cheng Lu;Min-Jia Lan;Bo-Chen Chen;Jen-Hwa Hsu;Van-Su Luong;Hua-Yi Hsu;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Minimizing and Managing Cloud Failures
Abstract:
Guaranteeing high levels of availability is a huge challenge for cloud providers. The authors look at the causes of cloud failures and recommend ways to prevent them and to minimize their effects when they occur.
Autors: Patricia Takako Endo;Guto Leoni Santos;Daniel Rosendo;Demis Moacir Gomes;André Moreira;Judith Kelner;Djamel Sadok;Glauco Estácio Gonçalves;Mozhgan Mahloo;
Appeared in: Computer
Publication date: Nov 2017, volume: 50, issue:11, pages: 86 - 90
Publisher: IEEE
 
» Minimizing Probing CostWith mRMR Feature Selection in Network Monitoring
Abstract:
Periodically monitoring the state of internal links is important for network diagnosis. In this letter, we consider the problem of minimizing probing cost in tomography-based network monitoring. We propose a new algorithm to select the informative probing paths by means of maximum relevance minimum redundancy (mRMR) method. mRMR has been widely used in the field of feature selection. Through the proposed scheme, the paths are regarded as features, and the ones that strongly relevant with link state are picked. We conduct simulation experiments of congested detection, demonstrating that the most useful paths for locating the congested links are chosen through the proposed scheme.
Autors: XiaoBo Fan;Xingming Li;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2400 - 2403
Publisher: IEEE
 
» Minimum-Based Sliding Window Detectors in Correlated Pareto Distributed Clutter
Abstract:
Recent investigations have resulted in the derivation of a multivariate Pareto model, which is consistent with the compound Gaussian model framework, allowing one to describe statistically a correlated Pareto distributed sequence. This has permitted the development of noncoherent sliding window detection processes, for operation in an X-band maritime surveillance radar context, which account for correlated clutter returns. Based upon this multivariate Pareto model, the structure of the sample minimum is investigated, which can then be used to produce decision rules robust to interference. Two such detectors will be examined, and their performance in real high-resolution X-band maritime radar clutter will be investigated. It will be shown that a number of avenues of future work are available.
Autors: Graham V. Weinberg;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Nov 2017, volume: 14, issue:11, pages: 1958 - 1962
Publisher: IEEE
 
» Mitigating Silent Data Corruptions in Integer Matrix Products: Toward Reliable Multimedia Computing on Unreliable Hardware
Abstract:
The generic matrix multiply (GEMM) routine comprises the compute and memory-intensive parts of many information retrieval, machine learning, and object recognition systems that process integer inputs. Therefore, it is of paramount importance to ensure that integer GEMM computations remain robust to silent data corruptions (SDCs), which stem from accidental voltage or frequency overscaling, or other hardware nonidealities. In this paper, we introduce a new method for SDC mitigation based on the concept of numerical packing. The key difference between our approach and all existing methods is the production of redundant results within the numerical representation of the outputs, rather than as a separate set of checksums. Importantly, unlike well-known algorithm-based fault tolerance approaches for GEMM, the proposed approach can reliably detect the locations of the vast majority of all possible SDCs in the results of GEMM computations. An experimental investigation of voltage-scaled integer GEMM computations for visual descriptor matching within state-of-the-art image and video retrieval algorithms running on an Intel i7-4578U 3 GHz processor shows that SDC mitigation based on numerical packing leads to comparable or lower execution and energy-consumption overhead in comparison with all other alternatives.
Autors: Ijeoma Anarado;Mohammad Ashraful Anam;Fabio Verdicchio;Yiannis Andreopoulos;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Nov 2017, volume: 27, issue:11, pages: 2476 - 2489
Publisher: IEEE
 
» Mitigation of Alien Crosstalk for Downstream DSL Impaired by Multiple Interferers
Abstract:
Alien crosstalk is one of the major impairments for copper-based transmissions. This letter outlines a method for mitigating alien crosstalk for digital subscriber line downstream transmissions impaired by multiple interference sources. The method requires a reference channel, and includes a post-processing stage in which induced correlation is applied to prepare the interference at the target channel to be reasonably removed by a prediction-based mitigation step. The results show that the proposed method outperforms published alien crosstalk mitigation methods as the number of interference sources increase in G.fast scenarios.
Autors: Diego Gomes;Eduardo Medeiros;Aldebaro Klautau;Evaldo Pelaes;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2380 - 2383
Publisher: IEEE
 
» Mitigation of TMR Using Energy Ratio and Bit-Flipping Techniques in Multitrack Multihead BPMR Systems
Abstract:
Track misregistration (TMR) in ultra-high density bit-patterned media recording (BPMR) is one of the crucial problems, because it can severely degrade the overall system performance. In practical, TMR can be detected and adjusted by a servo control loop system. However, this paper proposes to utilize multiple readback signals obtained from the optimized positioning of the two side read head closer to the main read head to improve the TMR prediction process in a multitrack multi-head BPMR system with position jitter noise. In addition, we also propose the soft-information exchange and the bit-flipping techniques for the multitrack data detection, so as to improve the bit-error rate (BER) performance of all three data tracks simultaneously. Simulation results indicate that the proposed system is superior to the conventional system, especially, when the amount of TMR and position jitter is high. Furthermore, we also found that the upper and lower read heads, which are moved closer to the center track by 25% of a track pitch, will provide the best BER performance with and without position jitter noise.
Autors: Chanon Warisarn;Wiparat Busyatras;Lin M. M. Myint;Santi Koonkarnkhai;Piya Kovintavewat;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 4
Publisher: IEEE
 
» Mixture-Based Modeling of Spatially Correlated Interference in a Poisson Field of Interferers
Abstract:
As the interference in PPP-based wireless networks exhibit spatial correlation, any joint analysis involving multiple spatial points either end up with numerical integrations over or become analytically too intractable. To tackle these issues, we present an alternate approach which not only offers a simpler analytical structure, but also closely mimics the PPP characteristics. This approach at its core models the correlated interferences using a correlation framework constructed using random variable mixtures. In addition, a correlation framework based on the more standard method of linear combination of random variables is also presented for comparison purpose. The performance of these models is studied by deriving the joint complementary cumulative distribution function of signal-to-interference ratios at arbitrary points. The plots are found to tightly approximate the exact PPP-based results, with the tightness depending on the values of (interferer intensity), (path loss exponent), and . The applicability of the mixture-based model is also shown for a multi-antennae MRC receiver where only major derivation steps that simplify the outage probability analysis are shown.
Autors: Arindam Ghosh;
Appeared in: IEEE Communications Letters
Publication date: Nov 2017, volume: 21, issue:11, pages: 2496 - 2499
Publisher: IEEE
 
» Mn–Zn Ferrite Nanoparticles With Silica and Titania Coatings: Synthesis, Transverse Relaxivity, and Cytotoxicity
Abstract:
Mn–Zn ferrite nanoparticles of composition Mn0.61Zn0.42Fe1.97O4 and mean size of crystallites nm are synthesized under hydrothermal conditions as a single-phase product. Subsequently, two coated samples are prepared by encapsulation of the ferrite particles into silica and titania. Transmission electron microscopy confirms the core–shell structure of the products and shows that the cores are actually formed by small clusters of ferrite crystallites. Powder X-ray diffraction, combined with experimental hydrothermal treatment of the titania-coated product, demonstrates that the titania coating is amorphous but can easily be transformed into anatase. The colloidal stability of nanoparticles in water is evidenced by dynamic light scattering, and the respective hydrodynamic sizes are and 157 nm for the silica-coated and titania-coated particles. The colloidal behavior is confirmed based on the measurements of zeta potential, whose negative values lead to strong Coulombic repulsion among coated particles. Magnetic measurements on bare and coated particles show high magnetization of Mn0.61Zn0.42Fe1.97O4 cores and superparamagnetic state at room temperature. The relaxometric study on aqueous suspensions in magnetic fields of 0.5 and 11.75 T reveals high transverse relaxivity of the samples and two distinct forms of its temperature dependence, which are analyzed with respect to the role of temperature-dependent parameters, that is, the diffusion of water and the magnetization of ferrite cores. Finally, careful evaluation of cytotoxicity of coated particles is carried out by using two different methods, namely, the determination of viability and proliferation o- Jurkat cells and the real-time monitoring of attachment and proliferation of A549 cells. In the studied range of concentrations, the viability and proliferation of suspension cells are not affected, and only negligible effects are detected in the cell index of adherent cells.
Autors: Ondřej Kaman;Jarmila Kuličková;Miroslav Maryško;Pavel Veverka;Vít Herynek;Radim Havelek;Karel Královec;Denisa Kubániová;Jaroslav Kohout;Petr Dvořák;Zdeněk Jirák;
Appeared in: IEEE Transactions on Magnetics
Publication date: Nov 2017, volume: 53, issue:11, pages: 1 - 8
Publisher: IEEE
 
» Mobile Unmanned Aerial Vehicles (UAVs) for Energy-Efficient Internet of Things Communications
Abstract:
In this paper, the efficient deployment and mobility of multiple unmanned aerial vehicles (UAVs), used as aerial base stations to collect data from ground Internet of Things (IoT) devices, are investigated. In particular, to enable reliable uplink communications for the IoT devices with a minimum total transmit power, a novel framework is proposed for jointly optimizing the 3D placement and the mobility of the UAVs, device-UAV association, and uplink power control. First, given the locations of active IoT devices at each time instant, the optimal UAVs’ locations and associations are determined. Next, to dynamically serve the IoT devices in a time-varying network, the optimal mobility patterns of the UAVs are analyzed. To this end, based on the activation process of the IoT devices, the time instances at which the UAVs must update their locations are derived. Moreover, the optimal 3D trajectory of each UAV is obtained in a way that the total energy used for the mobility of the UAVs is minimized while serving the IoT devices. Simulation results show that, using the proposed approach, the total-transmit power of the IoT devices is reduced by 45% compared with a case, in which stationary aerial base stations are deployed. In addition, the proposed approach can yield a maximum of 28% enhanced system reliability compared with the stationary case. The results also reveal an inherent tradeoff between the number of update times, the mobility of the UAVs, and the transmit power of the IoT devices. In essence, a higher number of updates can lead to lower transmit powers for the IoT devices at the cost of an increased mobility for the UAVs.
Autors: Mohammad Mozaffari;Walid Saad;Mehdi Bennis;Mérouane Debbah;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Nov 2017, volume: 16, issue:11, pages: 7574 - 7589
Publisher: IEEE
 

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