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Electrical and Electronics Engineering publications abstract of: 05-2011 sorted by title, page: 0
» "Study of the influence of particles irradiation on the electronic behavior of AlGaAs/GaAs/AlGaAs heterojunctions"
Abstract:
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Autors: Aim of the present work is to study the influence of radiation of ?-particles (5MeV) and temperature on the electronic behavior of AlGaAs/GaAs/AlGaAs heterojunction structures. The samples were irradiated with a fluence up to 1.6x1012cm-2 and assesse
Appeared in: Microelectronic Engineering
Publication date: May 2011
Publisher: Elsevier B.V.
 
» 10-Gbit/s BPSK Modulator and Demodulator for a 120-GHz-Band Wireless Link
Abstract:
This paper presents 10-Gbit/s binary phase-shift keying modulator and demodulator modules for a 120-GHz-band millimeter-wave wireless link. To reduce system complexity, we selected differentially coherent detection for the demodulator and designed the modulator and demodulator without IF circuits. The direct-conversion modulator consists of a 180 hybrid coupler, gain-control amplifiers, and a Wilkinson combiner. The demodulator has a 100-ps delay line made with coplanar waveguides and a variable phase shifter. The modulator and demodulator were fabricated with 0.1- m-gate HEMTs lattice-matched to an InP substrate. A test element of the modulator exhibited a static vector error magnitude of 5%. We also mounted the modulator and demodulator in WR-8 waveguide modules and evaluated the characteristics of 10-Gbit/s data transmission. The bit-error rate for 10-Gbit/s pseudorandom binary sequence data is at a received power of dBm.
Autors: Takahashi, H.;Kosugi, T.;Hirata, A.;Murata, K.;Kukutsu, N.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: May 2011, volume: 59, issue:5, pages: 1361 - 1368
Publisher: IEEE
 
» 1200-V Normally Off GaN-on-Si Field-Effect Transistors With Low Dynamic on -Resistance
Abstract:
This letter reports high-voltage GaN field-effect transistors fabricated on Si substrates. A halide-based plasma treatment was performed to enable normally off operation. Atomic layer deposition of gate insulator was adopted to reduce the gate leakage current. Incorporation of multiple field plates, with one field plate connected to the gate electrode and two field plates connected to the source electrode successfully enabled a high breakdown voltage of 1200 V and low dynamic on-resistance at high-voltage operation.
Autors: Chu, R.;Corrion, A.;Chen, M.;Li, R.;Wong, D.;Zehnder, D.;Hughes, B.;Boutros, K.;
Appeared in: IEEE Electron Device Letters
Publication date: May 2011, volume: 32, issue:5, pages: 632 - 634
Publisher: IEEE
 
» 2-D-Recursive Modelling of Homogeneous Discrete Gaussian Markov Fields
Abstract:
A 2-D-stochastic realization is obtained for an homogeneous discrete Gaussian Markov-field in two dimensions. In specific, it is shown that such Markov fields can be represented as the (unique) pathwise solution of a 2-D-recursive system of equations, with a locally-correlated “forcing-noise.” The idea of stochastic “dynamic” system in two dimensions gets realized this way. Two types of domain are considered: spheric and rectangular.
Autors: Carravetta, F.;
Appeared in: IEEE Transactions on Automatic Control
Publication date: May 2011, volume: 56, issue:5, pages: 1198 - 1203
Publisher: IEEE
 
» 2.4 W room temperature continuous wave operation of distributed feedback quantum cascade lasers
Abstract:
We demonstrate high power continuous-wave room-temperature operation surface-grating distributed feedback quantum cascade lasers at 4.8 μm. High power single mode operation benefits from a combination of high-reflection and antireflection coatings. Maximum single-facet continuous-wave output power of 2.4 W and peak wall plug efficiency of 10% from one facet is obtained at 298 K. Single mode operation with a side mode suppression ratio of 30 dB and single-lobed far field without beam steering is observed.
Autors: Lu, Q. Y.;Bai, Y.;Bandyopadhyay, N.;Slivken, S.;Razeghi, M.;
Appeared in: Applied Physics Letters
Publication date: May 2011, volume: 98, issue:18, pages: 181106 - 181106-3
Publisher: IEEE
 
» 2010 Radio Frequency Integrated Circuits (RFIC) Symposium Mini-Special Issue
Abstract:
Autors: Ponchak, G. E.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: May 2011, volume: 59, issue:5, pages: 1189 - 1189
Publisher: IEEE
 
» 2011 IMS/RFIC/ARFTG Workshops
Abstract:
Autors: Qiu, J.X.;Ivanov, T.;Nueslein, M.;St. John, M.;Augustine, G.;Floyd, B.;Wang, A.;
Appeared in: IEEE Microwave Magazine
Publication date: May 2011, volume: 12, issue:3, pages: 52 - 57
Publisher: IEEE
 
» 25-nm Gate Length nMOSFET With Steep Channel Profiles Utilizing Carbon-Doped Silicon Layers (A P-Type Dopant Confinement Layer)
Abstract:
Steep channel profiles of scaled transistors are a promising approach for advancing transistor generation in bulk complementary metal–oxide–semiconductor (MOS). In this paper, a carbon-doped Si (Si:C) layer under an undoped Si layer is proposed to form steep p-type channel profiles in n-channel MOS field-effect transistors (nMOSFETs) due to extremely low diffusivity of boron and indium in Si:C layers. This structure with low channel impurity improves mobility and suppresses threshold voltage variation. Both items are essential for aggressively scaled MOSFETs with a gate length less than 25 nm. We demonstrated well-controlled, high-performance, and low variability nMOSFETs with a Si:C-Si epitaxial channel structure.
Autors: Hokazono, A.;Itokawa, H.;Kusunoki, N.;Mizushima, I.;Inaba, S.;Kawanaka, S.;Toyoshima, Y.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: May 2011, volume: 58, issue:5, pages: 1302 - 1310
Publisher: IEEE
 
» 3-D Pain Drawings and Seating Pressure Maps: Relationships and Challenges
Abstract:
Mobility impaired people constitute a significant portion of the adult population, which often experience back pain at some point during their lifetime. Such pain is usually characterized by severe implications reflected on both their personal lives, as well as on a country's health and economic systems. The traditional 2-D representations of the human body often used can be limited in their ability to efficiently visualize such pain for diagnosis purposes. Yet, patients have been shown to prefer such drawings. However, considering that pain is a feeling or emotion that is subjective in nature, the pain drawings could be consequently regarded as a subjective means of communicating such pain. As a result, the study described in this paper proposes an alternative, which encompasses a 3-D pain visualization solution, developed in a previous work of ours. This alternative is complemented with the upcoming technique of pressure mapping for more objectivity in the pain data collection. The results of this study have shown that the proposed approach is a promising solution for the purpose intended, and it could generally prove to be a significant complementary method in the area of medical practice for the mobility impaired community.
Autors: Spyridonis, F.;Ghinea, G.;
Appeared in: IEEE Transactions on Information Technology in Biomedicine
Publication date: May 2011, volume: 15, issue:3, pages: 409 - 415
Publisher: IEEE
 
» 3-D Reconstruction of Encephalic Tissue in MR Images Using Immune Sphere-Shaped SVMs
Abstract:
In the brain MR images, the boundary of each encephalic tissue is highly irregular. Traditional 3-D reconstruction algorithms are challenged. Owing to its powerful capacity in solving nonlinearity problems, the sphere-shaped support vector machines (SSSVMs) is applied in the 3-D reconstruction. Selecting parameters for SSSVM and the kernel function, however, is a complicated issue. Appropriate parameters can make the model more flexible and help to obtain more accurate data description. In this study, immune algorithm (IA) is used in searching for the optimal parameters. Immune SSSVM (ISSSVM) is proposed to reconstruct the 3-D encephalic tissues in MR images. As shown by the experiment of this study, each encephalic tissue can be reconstructed efficiently, and satisfied accuracy and visual effect can be obtained.
Autors: Guo, L.;Li, Y.;Miao, D.;Zhao, L.;Yan, W.;Shen, X.;
Appeared in: IEEE Transactions on Magnetics
Publication date: May 2011, volume: 47, issue:5, pages: 870 - 873
Publisher: IEEE
 
» 3-D Stochastic Spectral Finite-Element Method in Static Electromagnetism Using Vector Potential Formulation
Abstract:
Stochastic spectral finite-element method can be used to take into account some random aspects in the input data (material characteristic, source terms) involved in static electromagnetism problems. Similarly to the deterministic case, two potential formulations can be used in the stochastic case. The vector potential formulation applied to static problems is developed and compared to the scalar potential one, previously developed.
Autors: Beddek, K.;Le Menach, Y.;Clenet, S.;Moreau, O.;
Appeared in: IEEE Transactions on Magnetics
Publication date: May 2011, volume: 47, issue:5, pages: 1250 - 1253
Publisher: IEEE
 
» 355-nm UV Generation by Intracavity Frequency Tripled Passively -Switched Nd:YAG/Cr :YAG Laser
Abstract:
In this letter, intracavity frequency-tripling of a diode-end-pumped passively -switched composite laser has been demonstrated for the first time. Under the absorbed pump power of 7.2 W, the maximum UV output power of 110 mW is obtained with the beam quality parameter of 2.95. The minimum pulsewidth and the highest repetition rate are 23.9 ns and 19.6 kHz, respectively. The corresponding single pulse energy and pulse peak power are 5.6 and 0.23 kW. The fluctuation of the average output power at 110 mW within an hour operation is tested and determined to be 4.7%.Pub _bookmark Command="[Quick Mark]"
Autors: Zhang, B.;Du, N.;He, J.;Liu, S.;Yang, J.;Huang, H.;
Appeared in: IEEE Photonics Technology Letters
Publication date: May 2011, volume: 23, issue:10, pages: 612 - 614
Publisher: IEEE
 
» 3D Full-Maxwell Simulations of Very Fast Transients in GIS
Abstract:
This study presents a detailed analysis of very fast electromagnetic transients (VFTs) initiated by disconnector switching operations in gas insulated switchgears (GIS). The results of the full-Maxwell electromagnetic simulations performed on real-life GIS geometries along with the modeling details are presented. The verification of the simulation results was performed by comparison against both measurements and circuit-equations-based transient simulations with the aim to quantify the achieved simulations' accuracy. The obtained results show a highly accurate shape and acceptably accurate amplitude prediction of dominant VFT waves in GIS, allowing for better understanding of the VFT phenomenon and a significant reduction of the product development time and prototyping costs.
Autors: Smajic, J.;Holaus, W.;Kostovic, J.;Riechert, U.;
Appeared in: IEEE Transactions on Magnetics
Publication date: May 2011, volume: 47, issue:5, pages: 1514 - 1517
Publisher: IEEE
 
» 3D Shape Reconstruction of Loop Objects in X-Ray Protein Crystallography
Abstract:
Knowledge of the shape of crystals can benefit data collection in X-ray crystallography. A preliminary step is the determination of the loop object, i.e., the shape of the loop holding the crystal. Based on the standard set-up of experimental X-ray stations for protein crystallography, the paper reviews a reconstruction method merely requiring 2D object contours and presents a dedicated novel algorithm. Properties of the object surface (e.g., texture) and depth information do not have to be considered. The complexity of the reconstruction task is significantly reduced by slicing the 3D object into parallel 2D cross-sections. The shape of each cross-section is determined using support lines forming polygons. The slicing technique allows the reconstruction of concave surfaces perpendicular to the direction of projection. In spite of the low computational complexity, the reconstruction method is resilient to noisy object projections caused by imperfections in the image-processing system extracting the contours. The algorithm developed here has been successfully applied to the reconstruction of shapes of loop objects in X-ray crystallography.
Autors: Strutz, T.;
Appeared in: IEEE/ACM Transactions on Computational Biology and Bioinformatics
Publication date: May 2011, volume: 8, issue:3, pages: 797 - 807
Publisher: IEEE
 
» 40 Gb/s NRZ Wavelength Conversion Using a Differentially-Biased SOA-MZI: Theory and Experiment
Abstract:
We present theoretical and experimental performance analysis of 40 Gb/s Non-Return-to-Zero (NRZ) All-Optical Wavelength Conversion (AOWC) using a differentially-biased SOA-MZI. A frequency domain transfer function model for both the standard single-control SOA-MZI-based AOWC and for the differentially-biased SOA-MZI is analytically derived, exploiting first order perturbation theory techniques and showing that only the differentially-biased scheme can yield an almost flat low-pass filtering response enabling wavelength conversion at 40 Gb/s. The theoretically obtained results are also confirmed through experiments that demonstrate successful 40 Gb/s AOWC functionality for NRZ data signals only when a differentially-biased SOA-MZI configuration is employed, whereas an error-floor is obtained when 40 Gb/s NRZ AOWC with the standard single-control SOA-MZI scheme is attempted. The 1.7 dB negative power penalty obtained by the differentially-biased SOA-MZI architecture confirms its enhanced regenerative properties and its potential for extending 40 Gb/s optical transparent network dimensions by means of cascaded 2R AOWC stages.
Autors: Spyropoulou, M.;Pleros, N.;Vyrsokinos, K.;Apostolopoulos, D.;Bougioukos, M.;Petrantonakis, D.;Miliou, A.;Avramopoulos, H.;
Appeared in: Journal of Lightwave Technology
Publication date: May 2011, volume: 29, issue:10, pages: 1489 - 1499
Publisher: IEEE
 
» 40 Gbit/s transimpedance amplifier with high linearity range in 0.13 μm SiGe BiCMOS
Abstract:
A 40 Gbit/s transimpedance amplifier (TIA) implemented in 0.13 μm SiGe BiCMOS with high linearity range is presented. The TIA features 24.2 dB (65.2 dB ω) gain, a bandwidth of 34.2 GHz and a power consumption of only 80 mW from a 2.5 V supply. Total harmonic distortion is less than 5% up to an input current of 1.3 mApp.
Autors: Knochenhauer, C.;Sedighi, B.;Ellinger, F.;
Appeared in: Electronics Letters
Publication date: May 2011, volume: 47, issue:10, pages: 605 - 606
Publisher: IEEE
 
» and Low-Gain Feedback: Their Properties, Characterizations and Applications in Constrained Control
Abstract:
Low-gain feedback has found several applications in constrained control, robust control, and nonlinear control. In this paper, we first generalize the existing low-gain design methods by introducing the notion of -vanishment and by providing a full characterization of feedback gains that achieve such a property. We observe that low-gain feedback can lead to energy peaking, namely, the control energy required by low-gain feedback increases toward infinity as the low-gain parameter decreases to zero. Motivated by this observation, we consider the notion of -vanishment and establish several of its characterizations, based on which a new design approach referred to as the low-gain feedback approach for linear systems is developed. Different from the low-gain feedback, the low-gain feedback is instrumental in the control of systems with control energy constraints. As an application of low-gain feedback, the problem of semiglobal stabilization of linear systems with control energy constraints is solved in this paper. The notions of and -vanishment also allow us to establish a systematic approach to the design of and $L_{2}$ low-gain feedback. The advantage of this new design approach is that it results in a family of control laws, including those resulting from the existing design methods.
Autors: Zhou, B.;Lin, Z.;Duan, G.-R.;
Appeared in: IEEE Transactions on Automatic Control
Publication date: May 2011, volume: 56, issue:5, pages: 1030 - 1045
Publisher: IEEE
 
» -Based MSM Ultraviolet Detectors With Pt Electrodes
Abstract:
In this letter, visible-blind ultraviolet (UV) photodetectors based on thin films with Pt electrodes were fabricated. The thin films were prepared via the sol–gel method and characterized by means of X-ray diffraction, scanning electron microscopy, XPS, and UV-visible absorption spectra. At 5-V bias, the dark current of the detector was only 6 nA. Under the irradiation of 300-nm UV light, a high responsivity of 702.5 A/W was achieved due to the high internal gain. The high gain is caused by the introduction of zirconia. The rise and fall times of the device were 896.6 and 578.1 ms, respectively. Compared with -based detectors, the -based detector with Pt electrodes exhibits a much higher responsivity, a faster recovery time, and a wider detection range.
Autors: Zhang, H.;Ruan, S.;Xie, T.;Feng, C.;Qu, P.;Chen, W.;Dong, W.;
Appeared in: IEEE Electron Device Letters
Publication date: May 2011, volume: 32, issue:5, pages: 653 - 655
Publisher: IEEE
 
» Nanocrystal Metal Oxide Semiconductor Field Effect Transistor Memory
Abstract:
A nanocrystal (NC) memory was fabricated. NCs were synthesized on SiO by annealing Ti covered Si NCs. Compared to the reference Si NC memory, both experiment and simulation results show that NC memory exhibits larger memory window, faster writing and erasing, and longer retention lifetime as a result of the metallic property of the silicide NCs. Due to thermally stable, CMOS compatible properties, NCs are highly promising for nonvolatile memory device application.
Autors: Zhou, H.;Li, B.;Yang, Z.;Zhan, N.;Yan, D.;Lake, R. K.;Liu, J.;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: May 2011, volume: 10, issue:3, pages: 499 - 505
Publisher: IEEE
 
» A 0.5-20 GHz Bandwidth Enhanced Distributed Amplifier
Abstract:
In this work a 0.5-23 GHz three-stage broadband distributed amplifier designed in a standard 0.18 ?m RF CMOS process is presented. A Darlington connection is used in the design to further increase the bandwidth of the amplifier. Gate and drain transmission lines use small size circular spiral inductors provided by the process. S-parameter simulation results show 8±1 dB small signal gain from 0.5-20 GHz and a unity-gain bandwidth of 23 GHz. Input and output return losses are better than -10 dB from 1 to 23 GHz and -8 dB from 1 to 24 GHz respectively. The improved performance of the...
Autors: Maria, Drakaki , Stylianos, Siskos , Alkis, Hatzopoulos
Appeared in: Microelectronic Engineering
Publication date: May 2011
Publisher: Elsevier B.V.
 
» A 0.5-V 0.4–2.24-GHz Inductorless Phase-Locked Loop in a System-on-Chip
Abstract:
A phase-locked loop (PLL) is proposed for low-voltage applications. A new charge pump (CP) circuit, using gate switches affords low leakage current and high speed operation. A low-voltage voltage-controlled oscillator (LV-VCO) composed of 4-stage delay cells and a low-voltage segmented current mirror (LV-SCM) achieves low voltage-controlled oscillator gain , a wide tuning range, and good linearity. A LV-SCM generates more current with small area by switching the body rather than the gate. The PLL is implemented in standard 90-nm CMOS with regular (RVT) devices. Its output jitter is 2.22 ps (rms), which is less than 0.5% of the output period. The phase noise is at 1-MHz offset from a 2.24-GHz center frequency. Total power dissipation at 2.24-GHz output frequency, and with 0.5-V power supply is 2.08 mW (excluding the buffers). The core area is 0.074 .
Autors: Cheng, K.-H.;Tsai, Y.-C.;Lo, Y.-L.;Huang, J.-S.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: May 2011, volume: 58, issue:5, pages: 849 - 859
Publisher: IEEE
 
» A 0.77 ps RMS Jitter 6-GHz Spread-Spectrum Clock Generator Using a Compensated Phase-Rotating Technique
Abstract:
This study demonstrates a 6-GHz triangular-modulated spread-spectrum clock generator (SSCG) based on a fractional- PLL in a 90-nm CMOS process. This paper presents a phase-rotating technique to create the fractional- topology for the SSCG and implement spread-spectrum clocking (SSC) by modulating the fractional- ratios. The proposed phase-rotating technique consists of virtual multiphase generation and the phase compensation approach. This technique effectively compensates the instantaneous timing error and shows the ignorable quantization error. Unlike the delta-sigma technique commonly used for SSCGs, the proposed SSCG realizes non-dithered fractional division ratios. In terms of SSC, this approach suppresses the RMS jitter to less than 1 ps, showing a significant improvement in the jitter performance in this work. The measured power attenuation of electromagnetic interference (EMI) is 16.12 dB, with a deviation of less than 0.5% (5000 ppm). Operating at a 6-GHz clock rate, the measured RMS jitter with and without the down-spreading spectrum are 0.77 and 0.71 ps, respectively. The chip core area is less than 0.55 0.45 mm and the core power consumption is 27.7 mW at a supply of 1.0 V.
Autors: Cheng, K.-H.;Hung, C.-L.;Chang, C.-H.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: May 2011, volume: 46, issue:5, pages: 1198 - 1213
Publisher: IEEE
 
» A 10-Gb/s OEIC with Meshed Spatially-Modulated Photo Detector in 0.18- CMOS Technology
Abstract:
This paper describes the design of a 10-Gb/s fully integrated CMOS optical receiver, which consists of a novel spatially-modulated photo detector (SMPD), a low-noise trans-impedance amplifier (TIA), and a post-limiting amplifier on a single chip. The bandwidth of proposed meshed SMPD can be boosted up to 6.9 GHz under a reverse-biased voltage of 14.2 V. The measured responsivity of the meshed SMPD is 29 mA/W as illuminated by 850-nm light source. To compensate the relatively low responsivity of on-chip CMOS photo detector (PD), a high-gain TIA with nested feedback and shunt peaking is proposed to achieve low-noise operation. The optical receiver is capable of delivering 25-k conversion gain when driving 50- output loads. For a PRBS test pattern of 2 1, the 10-Gb/s optoelectronic integrated circuit (OEIC) has optical sensitivity of 6 dBm at a bit-error rate (BER) of 10 . Implemented in a generic 0.18- m CMOS technology, the chip area is 0.95 mm by 0.8 mm. The trans-impedance amplifier, post amplifier, and output buffer respectively drain 38 mW, 80 mW, and 27 mW from the 1.8-V supply.
Autors: Huang, S.-H.;Chen, W.-Z.;Chang, Y.-W.;Huang, Y.-H.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: May 2011, volume: 46, issue:5, pages: 1158 - 1169
Publisher: IEEE
 
» A 11-Transistor Nanoscale CMOS Memory Cell for Hardening to Soft Errors
Abstract:
This paper proposes a new hardening design for an 11 transistors (11T) CMOS memory cell at 32 nm feature size. The proposed hardened memory cell overcomes the problems associated with the previous design by utilizing novel access and refreshing mechanisms. Simulation shows that the data stored in the proposed hardened memory cell does not change even for a transient pulse of more than twice the charge than a conventional memory cell. Moreover it achieves 55% reduction in power delay product compared to the DICE cell (with 12 transistors) providing a significant improvement in soft error tolerance. Simulation results are provided using the predictive technology file for 32 nm feature size in CMOS.
Autors: Lin, S.;Kim, Y.-B.;Lombardi, F.;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: May 2011, volume: 19, issue:5, pages: 900 - 904
Publisher: IEEE
 
» A 130- W, 64-Channel Neural Spike-Sorting DSP Chip
Abstract:
Spike sorting is an important processing step in various neuroscientific and clinical studies. Energy-efficient spike-sorting ASICs are necessary to allow real-time processing of multi-channel, wireless neural recordings. Spike-sorting ASICs have to meet stringent power-density constraints and must provide significant data-rate reduction for wireless transmission. Most existing designs either provide only spike detection for multi-channel processing, or they provide detection and feature extraction only for a single channel. In this paper, we demonstrate the design of a spike-sorting DSP chip that can perform detection, alignment, and feature extraction simultaneously for 64 channels. Spike-sorting algorithms chosen based on a complexity–performance analysis were implemented on ASIC using a MATLAB/Simulink-based architecture design framework. Energy–delay tradeoffs of the design were analyzed to identify the optimal degree of interleaving. The chip was implemented with a modular architecture, and can be configured to process 16, 32, 48, or 64 channels. Inactive cores are power-gated when the chip is operated to process a reduced number of channels. The chip, implemented in a 90-nm CMOS process, has a power dissipation of 130 W (power density of 30 W/mm ) when processing all 64 channels and provides a data-rate reduction of 91.25% (11.71 Mb/s to 1.02 Mb/s).
Autors: Karkare, V.;Gibson, S.;Markovic, D.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: May 2011, volume: 46, issue:5, pages: 1214 - 1222
Publisher: IEEE
 
» A 325 GHz InP HBT Differential-Mode Amplifier
Abstract:
An MMIC amplifier operating at the highest reported frequency up to date for indium-phosphide double-heterojunction bipolar (DHBT) transistor technology is presented. The amplifier chain consists of seven unit-cell stages that contain differential-pair common-base HBTs and compact inverted microstrip matching networks. Amplifier operation in differential mode generates a virtual RF ground at a convenient location inside the unit cell. The measurements at 325 GHz show a small signal gain of 25 dB and a maximum output power of 1.5 dBm. An amplifier gain of greater than 20 dB is observed over 60 GHz bandwidth extending from 285 to 345 GHz.
Autors: Hacker, J. B.;Lee, Y. M.;Park, H. J.;Rieh, J.-S.;Kim, M.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: May 2011, volume: 21, issue:5, pages: 264 - 266
Publisher: IEEE
 
» A 4-Port Diversity Antenna With High Isolation for Mobile Communications
Abstract:
A novel wideband four-port diversity antenna that is capable of exciting four different radiation patterns is presented. The antenna consists of four magnetoelectric dipoles arranged in a ring configuration above a ground plane and a vertical electric monopole at the center of the ground plane. A matching network is used to combine the signals from the four magnetoelectric dipoles to produce two orthogonal broadside modes and one conical mode with horizontal polarization. The electric monopole is used to generate a conical beam with vertical polarization in electric feed. The performance of the antenna is studied computationally. A prototype operated at around 2.4 GHz was constructed and tested. Experimentally, the antenna exhibits about 22.2% overlapped bandwidth of the four ports. The two orthogonal broadside modes have about 11 dBi average gain. Whereas for the two orthogonal conical modes, an average gain of 6 dBi is achieved. The measured radiation patterns of the four degenerate modes are stable within the operating band. The measured isolations between different ports are generally less than dB within the overlapped bandwidth. The measured radiating efficiencies of the four modes are all over 80% within the operating band.
Autors: Wu, B.;Luk, K.-M.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: May 2011, volume: 59, issue:5, pages: 1660 - 1667
Publisher: IEEE
 
» A 45 GHz CMOS VCO Adopting Digitally Switchable Metal-Oxide-Metal Capacitors
Abstract:
A 45 GHz millimeter-wave (MMW) VCO adopting digitally switchable metal-oxide-metal (MOM) capacitors as the tuning element is described in this work. The MOM capacitor is designed to have discrete capacitance values in order to extend frequency tuning range. The MMW VCO with the switchable MOM capacitor demonstrates an operation frequency ranging from 43.5 to 45.5 GHz. The measured phase noise at 3 MHz offset is less than -97 dBc/Hz across the entire frequency band. The VCO core consumes 4 mW power under a 1 V supply. The measured is -173.
Autors: Huang, G.;Kim, S.-K.;Gao, Z.;Kim, S.-Y.;Fusco, V.;Kim, B.-S.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: May 2011, volume: 21, issue:5, pages: 270 - 272
Publisher: IEEE
 
» A 6.25 Gb/s Voltage-Time Conversion Based Fractionally Spaced Linear Receive Equalizer for Mesochronous High-Speed Links
Abstract:
Fractionally spaced linear receive equalization (FSE) is shown in this work as an effective method to perform joint equalization and phase-synchronization in mesochronous high-speed links. Given an arbitrary receive sampling phase, a modified sign-sign least mean squares (M-SSLMS) adaptive algorithm is developed to tune the FSE tap weights to mitigate the inter-symbol interference (ISI), avoiding the divergence issue in the standard sign-sign least mean squares (SSLMS) algorithm. To achieve the desired linearity with good energy efficiency and large input dynamic range, an FSE is implemented using a voltage-time conversion technique by inverter-based threshold detectors with auto-zeroing function. The two-tap quad-rate FSE receiver with one-tap DFE is fabricated in 90 nm bulk CMOS technology, occupying 0.03 mm active area. With a 1.2 V supply, it achieves a 6.25 Gb/s rate, 3.6 mW/Gb/s efficiency and over 4 bits of linearity.
Autors: Song, S.;Stojanovic, V.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: May 2011, volume: 46, issue:5, pages: 1183 - 1197
Publisher: IEEE
 
» A 65nm CMOS fully-integrated dynamic reconfigurable differential power amplifier with high gain in both bands?
Abstract:
A fully-integrated dual-band dynamic reconfigurable differential power amplifier with high gain in 65nm CMOS is presented. A switchable shunt LC network is proposed to implement the dual-band reconfigurable operation and achieve high gain at both low and high frequency bands, and the high quality on-chip transformers are utilized to implement input/output impedance matching and single-ended to differential conversion. Measured results show that the dual-band dynamic reconfigurable power amplifier can provide 23dB gain at 2.15GHz and 21dB gain at 4.70GHz, and achieve more than 19dBm saturated output power at 2.15GHz and 13dBm saturated output power at 4.70GHz, respectively. The die area...
Autors: Baoyong, Chi , Kasra, Omid-Zohoor , Zhihua, Wang , S., Simon Wong
Appeared in: Microelectronics Journal
Publication date: May 2011
Publisher: Elsevier B.V.
 
» A 78.4 dB Photo-Sensitivity Dynamic Range, 285 T Hz Transimpedance Bandwidth Product BiCMOS Optical Sensor for Optical Storage Systems
Abstract:
An optical sensor with variable transimpedance for optical storage systems in 0.6 BiCMOS technology is presented. A PIN photodiode, a voltage-controlled current amplifier, and a current-to-voltage converter are monolithically integrated. A balanced type of the BJT translinear loop based voltage-controlled current amplifier is used. A linearity error smaller than 3.6%, a transimpedance dynamic range of 8323 (78.4 dB) with the largest transimpedance of 12.9 , a maximum photo-sensitivity of 6824 at 675 nm, an offset voltage below 2.2 mV, a maximum power consumption of 9.1 mW, a bandwidth up to 463 MHz, a transimpedance bandwidth product up to 285 , and an output noise power down to 72.5 dBm (at 50 MHz and a resolution bandwidth of 30 kHz) are achieved.
Autors: Tadic, N.;Zogovic, M.;Gaberl, W.;Zimmermann, H.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: May 2011, volume: 46, issue:5, pages: 1170 - 1182
Publisher: IEEE
 
» A 90 nm-CMOS, 500 Mbps, 3–5 GHz Fully-Integrated IR-UWB Transceiver With Multipath Equalization Using Pulse Injection-Locking for Receiver Phase Synchronization
Abstract:
A fully-integrated, 3–5 GHz Impulse-Radio UWB transceiver with on-chip flash ADC is designed in 90 nm-CMOS. A new scheme for receiver phase acquisition is proposed that uses pulse injection-locking to synchronize the receive clock with the transmitted data, eliminating the need for clock/data recovery (CDR), requiring only static receiver phase alignment with the transmitted pulses at startup. Transmitter pre-emphasis equalization is utilized to mitigate the effect of multipath on bit-error rate (BER). Occupying 2 die area, the transceiver achieves a data rate of 500 Mbps, energy efficiency of 0.18 nJ/b at 500 Mbps, and a RX raw BER of across a distance of 10 cm at 125 Mbps. In a real multipath environment, BER improves by 2.35x after equalization of the first multipath reflection.
Autors: Hu, C.;Khanna, R.;Nejedlo, J.;Hu, K.;Liu, H.;Chiang, P. Y.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: May 2011, volume: 46, issue:5, pages: 1076 - 1088
Publisher: IEEE
 
» A 405-MHz All-Digital Fractional- Frequency-Locked Loop for ISM Band Applications
Abstract:
Several wireless biomedical transceivers, including medical implants communication systems (MICSs), require ultra-low-power low-complexity frequency synthesizers. This paper presents an all-digital frequency-locked loop (ADFLL)-based frequency synthesizer with a built-in frequency-shift keying modulator for MICS and industrial–scientific–medical band applications. Unlike all-digital phase-locked loops that rely on a power-hungry time to digital converter, the proposed ADFLL employs a high-resolution single-bit frequency discriminator in the feedback path and a noise-cancelling phase-accumulator-based frequency controller in the reference path, achieving fractional resolution with low power consumption. The loop compensation is implemented digitally using an infinite impulse response filter followed by a digital-intensive current-steering DAC driving a ring-oscillator-based voltage-controlled oscillator. The ADFLL achieves 9.5-Hz frequency resolution, spanning the ISM 400–410-MHz band. A worst case near-integer spur of and a phase noise of at 300-kHz offset are measured. The ADFLL is fabricated on a CMOS process, occupying a die area, with a quiescent current consumption of .
Autors: Khalil, W.;Shashidharan, S.;Copani, T.;Chakraborty, S.;Kiaei, S.;Bakkaloglu, B.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: May 2011, volume: 59, issue:5, pages: 1319 - 1326
Publisher: IEEE
 
» A Back EMF Optimization of Double Layered Large-Scale BLDC Motor by Using Hybrid Optimization Method
Abstract:
This paper presents an optimization method of the back EMF for the double layered (double air gap) large-scale BLDC motor by using a Latin-hypercube sampling strategy. In order to drive the large-scale BLDC motors in parallel and multiphases, the back EMF of inner stator is equal to the back EMF of the outer. A new configuration of the double layered BLDC motor is also proposed for the compactness and high efficiency of the system. By the optimization, it is concluded that the skew angle and the thickness difference between the outer and inner magnets have important roles in synchronization and same magnitude of the back EMF, respectively.
Autors: Kim, Y. B.;Choi, H. S.;Koh, C.-S.;Shin, P. S.;
Appeared in: IEEE Transactions on Magnetics
Publication date: May 2011, volume: 47, issue:5, pages: 998 - 1001
Publisher: IEEE
 
» A BE-SOI MEMS for Inertial Measurement in Geophysical Applications
Abstract:
In this paper, an inertial transducer developed in bulk and etch silicon-on-insulator microelectromechanical-system technology is presented. The device is suitable for low-frequency observation and could represent an interesting solution to implement low-cost monitoring systems for applications requiring a large number of monitoring sites and disposable devices. In particular, the sensor design and the technology adopted are presented here along with models describing the device operation. In addition, an experimental sensor prototype is proposed, and experimental results confirming the suitability of the proposed architecture and its consistence with the predicted behavior are discussed.
Autors: Ando, B.;Baglio, S.;L'Episcopo, G.;Marletta, V.;Savalli, N.;Trigona, C.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: May 2011, volume: 60, issue:5, pages: 1901 - 1908
Publisher: IEEE
 
» A Beamforming Codebook Restriction for Cross-Tier Interference Coordination in Two-Tier Femtocell Networks
Abstract:
This paper examines a novel multichannel multi-antenna-based cross-tier interference coordination strategy for two-tier femtocell networks. To reduce the cross-tier interference and improve the aggregate throughput of two-tier femtocell networks without exchanging feedback information by backhauling, we propose a beamforming codebook restriction strategy. The beamforming codebook restriction strategy enables the femtocell users to select the best channel that is robust to cross-tier interference before the transmission by reducing the size of the macrocell beamforming codebook. Although restricting the beamforming codebook increases the quantization error for macrocell users, the opportunistic channel selection strategy and the proportional fair scheduler compensate for the increased quantization error by exploiting the channel selection diversity gain and the multiuser diversity gain. Both analytical and numerical results demonstrate that the proposed strategies collaboratively improve the aggregate throughput of two-tier femtocell networks.
Autors: Park, S.;Seo, W.;Choi, S.;Hong, D.;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2011, volume: 60, issue:4, pages: 1651 - 1663
Publisher: IEEE
 
» A Brief History of Multiprocessors and EDA
Abstract:
The Last Byte takes a brief look at the recent history of multiprocessor design and EDA to see where the community stands today. Turning sophisticated systems into commodity items has presented its share of problems, but innovation continues to thrive, nonetheless, and offers considerable promise for validation and testing solutions.
Autors: Shukla, Sandeep;Mishra, Prabhat;Zilic, Zeljko;
Appeared in: IEEE Design & Test of Computers
Publication date: May 2011, volume: 28, issue:3, pages: 96 - 96
Publisher: IEEE
 
» A cDNA Microarray Gene Expression Data Classifier for Clinical Diagnostics Based on Graph Theory
Abstract:
Despite great advances in discovering cancer molecular profiles, the proper application of microarray technology to routine clinical diagnostics is still a challenge. Current practices in the classification of microarrays' data show two main limitations: the reliability of the training data sets used to build the classifiers, and the classifiers' performances, especially when the sample to be classified does not belong to any of the available classes. In this case, state-of-the-art algorithms usually produce a high rate of false positives that, in real diagnostic applications, are unacceptable. To address this problem, this paper presents a new cDNA microarray data classification algorithm based on graph theory and is able to overcome most of the limitations of known classification methodologies. The classifier works by analyzing gene expression data organized in an innovative data structure based on graphs, where vertices correspond to genes and edges to gene expression relationships. To demonstrate the novelty of the proposed approach, the authors present an experimental performance comparison between the proposed classifier and several state-of-the-art classification algorithms.
Autors: Benso, A.;Di Carlo, S.;Politano, G.;
Appeared in: IEEE/ACM Transactions on Computational Biology and Bioinformatics
Publication date: May 2011, volume: 8, issue:3, pages: 577 - 591
Publisher: IEEE
 
» A Cellular Automaton Approach to Spatial Electric Load Forecasting
Abstract:
A method for spatial electric load forecasting using a reduced set of data is presented. The method uses a cellular automata model for the spatiotemporal allocation of new loads in the service zone. The density of electrical load for each of the major consumer classes in each cell is used as the current state, and a series of update rules are established to simulate -growth behavior and the complementarity among classes. The most important features of this method are good performance, few data and the simplicity of the algorithm, allowing for future scalability. The approach is tested in a real system from a mid-size city showing good performance. Results are presented in future preference maps.
Autors: Carreno, E. M.;Rocha, R. M.;Padilha-Feltrin, A.;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2011, volume: 26, issue:2, pages: 532 - 540
Publisher: IEEE
 
» A characterization of the generalized spectral radius with Kronecker powers?
Abstract:
Based on Turán's power sum theory, we extend a recent result obtained by Blondel and Nesterov [Blondel, V. D., & Nesterov, Y. (2005). Computationally efficient approximations of the joint spectral radius, SIAM Journal on Matrix Analysis and Applications, 27, 256-272], by deriving a new characterization of the generalized spectral radius in terms of Kronecker powers.
Autors: Jianhong, Xu , Mingqing, Xiao
Appeared in: Automatica
Publication date: May 2011
Publisher: Elsevier B.V.
 
» A Circuit and Architecture Codesign Approach for a Hybrid CMOS–STTRAM Nonvolatile FPGA
Abstract:
Research efforts to develop a novel memory technology that combines the desired traits of nonvolatility, high endurance, high speed, and low power have resulted in the emergence of spin–torque transfer RAM (STTRAM) as a promising next-generation universal memory. Although industrial efforts have been made to design efficient embedded memory arrays using STTRAM, the prospect of developing a nonvolatile field-programmable gate array (FPGA) framework with STTRAM exploiting its high integration density remains largely unexplored. In this paper, we propose a novel CMOS–STTRAM hybrid FPGA framework, identify the key design challenges, and propose optimization techniques at circuit, architecture, and application mapping levels. We show that intrinsic properties of STTRAM that distinguish it from conventional static RAM (SRAM), such as asymmetric readout power, where a cell storing “0” has 5 less read power than a cell storing “1”, can be leveraged to skew lookup table contents for FPGA power reduction. We also argue that the proposed framework should operate on static voltage-sensing-based logic evaluation. We identify static power dissipation during logic evaluation and read noise margin as key design concerns and present an optimized resistor–divider design for voltage sensing to reduce static power and noise margin. Finally, we investigate the effectiveness of Shannon-decomposition-based supply gating to reduce static power. Simulation results show improvement of 44.39% in logic area and 22.28% in delay of a configurable logic block (CLB) and average improvement of 16.1% dynamic power over a conventional CMOS FPGA design for a set of benchmark circuits.
Autors: Paul, S.;Mukhopadhyay, S.;Bhunia, S.;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: May 2011, volume: 10, issue:3, pages: 385 - 394
Publisher: IEEE
 
» A CMOS 1.6 GHz Dual-Loop PLL With Fourth-Harmonic Mixing
Abstract:
A 1.5–1.6 GHz dual-loop phase-locked loop in 0.18- CMOS locks in 40 and draws only 26 mA from 1.8 V . The proposed techniques include a fourth-harmonic mixer that relaxes the secondary PLL requirements, and an auxiliary charge pump that speeds acquisition without affecting steady-state operation. The integrated RMS phase error is 1.1 and the phase noise spectral density is at an offset frequency of 600 kHz. The largest in-band and reference spurs are and at frequency offsets of 500.5 kHz and 37.9 MHz, respectively.
Autors: Aniruddhan, S.;Shekhar, S.;Allstot, D. J.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: May 2011, volume: 58, issue:5, pages: 860 - 867
Publisher: IEEE
 
» A CMOS Low-Power Transceiver With Reconfigurable Antenna Interface for Medical Implant Applications
Abstract:
A low-power transceiver for medical implant communication service is presented. The device consists of three subsystems, which perform wake-up signal reception, data-link binary frequency-shift keying (BFSK) reception, and transmission, respectively. A common antenna interface is reused in the three subsystems, reducing circuit complexity and number of external components. Super-regenerative architecture is used for wake-up reception, and -boosted common-gate stages are used to optimize receiver (RX) performance with low power consumption. The transmitter employs an all-digital frequency-locked loop to directly drive a class AB power amplifier. The transmitter can alternatively use an injection-locked power oscillator for lower bit rates and power consumption. The integrated circuit is designed and fabricated on a 0.18- CMOS process. The wake-up RX achieves a 80-dBm sensitivity for a 50-kb/s signal and a 280- dissipation. The BFSK RX achieves a 97-dBm sensitivity for a 75-kb/s signal and a 2-mW power consumption. Finally, the transmitter achieves an output power of 5 dBm for a power consumption of 2.9 mW.
Autors: Copani, T.;Min, S.;Shashidharan, S.;Chakraborty, S.;Stevens, M.;Kiaei, S.;Bakkaloglu, B.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: May 2011, volume: 59, issue:5, pages: 1369 - 1378
Publisher: IEEE
 
» A CMP Model Including Global Distribution of Pressure
Abstract:
In this paper, we consider the chemical–mechanical planarization (CMP) of adjacent line-space structures with different pattern density. Such structures are used on test-chips for process characterization and provide similar features like typical DRAM layouts. The predictions of previous chip-scale models based on a local balance of forces for this case are scrutinized and it is found that the distribution of the applied pressure between the different density regions is not treated sufficiently accurate in these models. We propose a simple way to include the global force balance and show that the resulting model is able to capture behavior which is more in line with general expectations for the time-evolution of typical CMP processes. The model is calibrated with data obtained for a set of test-structures with varying density and found to give a better match compared to the models described above. Especially, the prediction of the total indicated range, which is a measure for the global planarity after CMP is improved. Additionally, a parametric study shows that qualitatively different removal rate diagrams that confirm engineering experience can be obtained with the new model.
Autors: Bott, S.;Rzehak, R.;Vasilev, B.;Kucher, P.;Bartha, J. W.;
Appeared in: IEEE Transactions on Semiconductor Manufacturing
Publication date: May 2011, volume: 24, issue:2, pages: 304 - 314
Publisher: IEEE
 
» A compact extended cavity laser using a micromachined silicon flexure for atomic spectroscopy
Abstract:
We report a novel compact extended cavity diode laser (ECDL) system for applications in atomic physics. It employs a 6.5mm invar cavity, a volume holographic grating (VHG), and a micromachined silicon flexure integrated with a pair of piezoelectric transducer (PZT) actuators, and the overall laser system has a size of 26.3×20×20mm. The advantages of using a silicon flexure are its high material rigidity and simple microfabrication process with designable displacement. The measured spring constant of the silicon flexure is 1.56×105N/m, and its deflection is 157.45nm. This displacement alters the laser cavity length, leading to a frequency tuning range of 9.31GHz....
Autors: Ho-Chiao, Chuang , Kuo-Yuan, Huang
Appeared in: Sensors and Actuators A: Physical
Publication date: May 2011
Publisher: Elsevier B.V.
 
» A Compact Hybrid Current/Voltage Sense Amplifier With Offset Cancellation for High-Speed SRAMs
Abstract:
A hybrid current/voltage sense amplification scheme is proposed for high speed SRAMs. The scheme includes an offset cancellation technique which makes it robust against the current sense amplifier (CSA) mismatch. The offset cancellation allows for fast open loop operation of the differential CSA. A fourfold reduction of the cell access time is achieved compared to the conventional scheme under similar cell current and bitline capacitance. Thanks to its automatic turn off nature, the proposed CSA incurs zero static power without an auxiliary turn off circuit. The reduction of the charge redistribution on the bitlines offers a low bitline dynamic power consumption as well. In this work, the proposed scheme is rigorously analyzed and compared to the conventional scheme. The analysis is verified using circuit level simulations and compared to the conventional scheme as a reference analytically and using simulations.
Autors: Sharifkhani, M.;Rahiminejad, E.;Jahinuzzaman, S. M.;Sachdev, M.;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: May 2011, volume: 19, issue:5, pages: 883 - 894
Publisher: IEEE
 
» A Compact UWB Bandpass Filter With Embedded SIR as Band Notch Structure
Abstract:
In this letter, an ultrawideband (UWB) bandpass filter with a band notch is proposed. The UWB BPF (3.1–10.6 GHz) is realized by cascading a distributed high-pass filter and an elliptic low-pass filter with an embedded stepped impedance resonator (SIR) to achieve a band notch characteristic. The notch band is obtained at 5.22 GHz. It is shown that the notch frequency can be tuned by changing the impedance ratio of the embedded SIR. A fabricated prototype of the proposed UWB bandpass filter is developed. The inband and out-of-band performance obtained by measurement, EM simulation, and that with an equivalent circuit model are in good agreement.
Autors: Ghatak, R.;Sarkar, P.;Mishra, R. K.;Poddar, D. R.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: May 2011, volume: 21, issue:5, pages: 261 - 263
Publisher: IEEE
 
» A Compact, Low-Power 40-GBit/s Modulator Driver With 6-V Differential Output Swing in 0.25- m SiGe BiCMOS
Abstract:
This paper presents a high-speed, low-power modulator driver featuring a novel modified breakdown voltage doubler (BVD) topology. Further speed enhancement and reduction of power consumption is achieved by multiple frequency compensation methods. An optimization method combining small and large-signal analyses is presented. The driver was fabricated in a 0.25- SiGe BiCMOS technology with of up to 180 GHz. It features 13-dB differential gain, a small-signal bandwidth of 33.7 GHz and delivers a single-ended output swing of 3 Vpp (6 Vpp differential) at 40 GBit/s into a 50- load consuming only 1.35 W of DC power.
Autors: Knochenhauer, C.;Scheytt, J. C.;Ellinger, F.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: May 2011, volume: 46, issue:5, pages: 1137 - 1146
Publisher: IEEE
 
» A Comparative Analysis of Preprocessing Methods for the Parametric Loudspeaker Based on the Khokhlov–Zabolotskaya–Kuznetsov Equation for Speech Reproduction
Abstract:
Based on the Berktay's farfield solution, various preprocessing methods were proposed to reduce the distortion of the highly directional audible signal in the parametric loudspeaker. However, the Berktay's farfield solution is an approximated model of nonlinear acoustic propagation. To determine the effectiveness of these methods, we analyze various preprocessing methods theoretically for directional speech reproduction using the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation, which provides a more accurate model of nonlinear acoustic propagation. In order to reduce the distortion effectively in the parametric loudspeaker with these preprocessing methods, the initial sound pressure level of the carrier frequency is found to be less than 132 dB according to the KZK equation. Unlike the Berktay' farfield solution that results in a +12 dB/octave gain slope, different gain slopes are derived using the KZK equation and appropriate equalizers are proposed to improve the frequency response of the parametric loudspeaker. The optimal preprocessing method for directional speech reproduction is established based on the KZK equation, which has a relatively flat frequency response of the desired speech signal and the best total harmonic distortion performance.
Autors: Peifeng Ji;Ee-Leng Tan;Woon-Seng Gan;Jun Yang;
Appeared in: IEEE Transactions on Audio, Speech, and Language Processing
Publication date: May 2011, volume: 19, issue:4, pages: 937 - 946
Publisher: IEEE
 
» A Comparative Study Between Novel Witricity and Traditional Inductive Magnetic Coupling in Wireless Charging
Abstract:
A non-radiative energy transformer, commonly referred as Witricity and based on ‘strong coupling’ between two coils which are separated physically by medium-range distances, is proposed to realize efficient wireless energy transfer. The distance between the resonators can be larger than the characteristic sizes of each resonator. Non-radiative energy transfer between the first resonator and the second resonator is facilitated through the coupling of their resonant-field evanescent tails. The proposed system operates as traditional inductive magnetic coupling devices when the operating frequencies are not the resonant frequency. Corresponding finite element analysis (FEA) and experiments have been carried out to facilitate quantitative comparison. Compared with typical magnetic inductive coupling energy transmission devices, the efficiency of the proposed system is much higher. This investigation indicates that it is feasible to use wireless energy transfer technology to recharge batteries, particularly in implant devices.
Autors: Ho, S. L.;Wang, J.;Fu, W. N.;Sun, M.;
Appeared in: IEEE Transactions on Magnetics
Publication date: May 2011, volume: 47, issue:5, pages: 1522 - 1525
Publisher: IEEE
 
» A Comparative Study on Control Algorithm for Active Front-End Rectifier of Large Motor Drives Under Unbalanced Input
Abstract:
This paper investigates unbalance compensating control algorithms for the active front-end rectifier employed in high-power motor drive systems. The generic voltage-source-converter topology of the three-level neutral-point clamped rectifier is selected for the comparative study. Three different control algorithms have been formulated based on the symmetrical components and synchronous frames under generalized unbalanced operating conditions. Control algorithms have been investigated with respect to major design factors in large drive systems: fault ride-through capability, harmonic distortions, and efficiency. The control algorithm having zero amplitude of negative-sequence input current shows the most optimized and cost-effective performance regarding the fault ride-through capability and efficiency aspects. The control algorithm nullifying the oscillating components of the instantaneous active power generates the least harmonic distortions. A combination of these two control algorithms depending on system requirements and operating modes provides improved performance factors of fault ride-through capability, low harmonic distortions, and efficiency under generalized unbalanced operating conditions.
Autors: Suh, Y.;Go, Y.;Rho, D.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2011, volume: 47, issue:3, pages: 1419 - 1431
Publisher: IEEE
 
» A Comparison of Control and Modulation Schemes for Medium-Voltage Drives: Emerging Predictive Control Concepts Versus PWM-Based Schemes
Abstract:
Control and modulation schemes for ac electrical drives synthesize switched three-phase voltage waveforms that control the electrical machine. Particularly in medium-voltage applications, the aim is to minimize both the switching losses in the inverter and the harmonic distortions of the stator currents and the torque. For a given modulation scheme, lower switching losses usually imply higher distortion factors and vice versa. This tradeoff can be described by a hyperbolic function, as shown in this paper for pulsewidth modulation (PWM). A number of predictive control concepts are rapidly emerging. Their characteristic hyperbolic tradeoff functions are derived, compared with each other, and benchmarked with respect to PWM and offline optimized pulse patterns (OPPs). It is shown that predictive schemes with long prediction horizons shift the performance tradeoff curve toward the origin, thus lowering both the switching losses and the harmonic distortions. As a result, at steady-state operating conditions, these predictive schemes achieve a performance similar to OPPs, while providing a superior dynamic performance during transients.
Autors: Geyer, T.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2011, volume: 47, issue:3, pages: 1380 - 1389
Publisher: IEEE
 
» A Comprehensive Statistical Model for Cell Signaling
Abstract:
Protein signaling networks play a central role in transcriptional regulation and the etiology of many diseases. Statistical methods, particularly Bayesian networks, have been widely used to model cell signaling, mostly for model organisms and with focus on uncovering connectivity rather than inferring aberrations. Extensions to mammalian systems have not yielded compelling results, due likely to greatly increased complexity and limited proteomic measurements in vivo. In this study, we propose a comprehensive statistical model that is anchored to a predefined core topology, has a limited complexity due to parameter sharing and uses micorarray data of mRNA transcripts as the only observable components of signaling. Specifically, we account for cell heterogeneity and a multilevel process, representing signaling as a Bayesian network at the cell level, modeling measurements as ensemble averages at the tissue level, and incorporating patient-to-patient differences at the population level. Motivated by the goal of identifying individual protein abnormalities as potential therapeutical targets, we applied our method to the RAS-RAF network using a breast cancer study with 118 patients. We demonstrated rigorous statistical inference, established reproducibility through simulations and the ability to recover receptor status from available microarray data.
Autors: Yoruk, E.;Ochs, M.F.;Geman, D.;Younes, L.;
Appeared in: IEEE/ACM Transactions on Computational Biology and Bioinformatics
Publication date: May 2011, volume: 8, issue:3, pages: 592 - 606
Publisher: IEEE
 
» A Computationally Efficient Method to Place Critical Measurements
Abstract:
This paper investigates a very practical and commonly encountered problem in state estimation. It is related to the placement of measurements in order to make an otherwise unobservable system observable. Typically, this is a situation that is frequently encountered during the daily operation as one or more of the measurements become unavailable due to various unexpected reasons. Under such circumstances, the state estimator resorts to the use of pseudo-measurements in order to recover observability and solve the state estimation problem. Pseudo-measurements that will make the system observable can be selected by applying one of the well-developed network observability analysis techniques in a repetitive fashion adding one candidate measurement at a time until the system is no longer unobservable. As the system size increases, this approach may prove computationally expensive. A nonrepetitive solution has also been proposed. However, its computational requirements grow rapidly with increasing number of observable islands that may exist in large scale systems. This paper presents an alternative approach which will be shown to be suitable for large scale power systems providing a compromise between the two existing techniques. Examples are given to highlight the main benefits of the proposed method.
Autors: Donmez, B.;Abur, A.;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2011, volume: 26, issue:2, pages: 924 - 931
Publisher: IEEE
 
» A Concise Representation for the Soft-in Soft-out LMMSE Detector
Abstract:
An alternative simple derivation for the well-known soft-in soft-out LMMSE (linear minimum mean square error) detector in a turbo system is presented. The derivation leads to a concise representation for the LMMSE detector in terms of the extrinsic means and extrinsic variances of the data symbols, and provides new perspectives for its implementation.
Autors: Guo, Qinghua;Huang, Defeng David;
Appeared in: IEEE Communications Letters
Publication date: May 2011, volume: 15, issue:5, pages: 566 - 568
Publisher: IEEE
 
» A Converter-Based Starting Method and Speed Control of Doubly Fed Induction Machine With Centrifugal Loads
Abstract:
The adjustable-speed drive is attractive for pump, compressor, and other centrifugal load applications due to its flexibility and high operating efficiency, compared with the conventional constant-speed drive system. This paper has developed a converter-based starting method for a doubly fed induction machine (DFIM) with centrifugal loads by constant volts/hertz control, instead of using the additional starting resistors or autotransformer. A grid synchronization scheme is then developed to complete the transition from motor starting to vector-controlled speed regulation in the high-speed region. Therefore, the machine can successfully operate in the full speed range by combining constant volts/hertz control and vector control. Since the centrifugal load torque reduces quickly with speed (square relationship), the partially rated converter may provide enough torque at low speeds. Two starting alternatives can be used according to different turns ratios between the machine stator and rotor windings. The proposed control scheme can be simply implemented with a one-quadrant partially rated power converter. The voltage and current ratings of the converter are carefully designed considering the centrifugal load characteristic and the operating speed range. Some important application issues such as “soft grid connection” and rotor position estimation are also discussed. The proposed control scheme has been validated by simulation and experimentally verified through a DSP-controlled 30-kW DFIM system by starting from the rotor side. The drive system can successfully run in the full speed range with the proposed control method and control sequences.
Autors: Yuan, X.;Chai, J.;Li, Y.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2011, volume: 47, issue:3, pages: 1409 - 1418
Publisher: IEEE
 
» A Cooperation Stimulation Strategy in Wireless Multicast Networks
Abstract:
Cooperative multicast is an effective technique to provide reliable multicast service in wireless networks. However, selfish nodes may act as free riders to maximize their payoffs, and an incentive mechanism is needed to stimulate cooperation. In this paper, we employ a game theoretic approach to analyze the interactions among selfish mobile nodes in wireless multicast networks. The cooperation process is modeled as an infinite repeated game and the desired cooperation state that achieves absolute fairness and Pareto optimality is derived. A Worst Behavior Tit-for-Tat (WBTFT) incentive strategy is proposed to stimulate cooperation at the desired cooperation state. In the proposed strategy, a node monitors others' behaviors and makes decisions according to the worst behaved node. With perfect monitoring, we analyze the conditions for the proposed strategy to be subgame perfect. To address the issue of imperfect monitoring, an interval based estimation method is proposed and the subgame perfect equilibrium conditions are derived under the assumption that nodes are bounded rational. Simulation results show that the proposed strategy can efficiently enforce cooperation even with imperfect monitoring, and its performance is close to that when all nodes fully cooperate with each other and when they can perfectly monitor each other's behavior without errors.
Autors: Niu, B.;Zhao, H. V.;Jiang, H.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: May 2011, volume: 59, issue:5, pages: 2355 - 2369
Publisher: IEEE
 
» A Copula Model of Wind Turbine Performance
Abstract:
The conventional means of assessing the performance of a wind turbine is through consideration of its power curve which provides the relationship between power output and measured wind speed. In this letter, it is shown how the joint probability distribution of power and wind speed can be learned from data, rather than from examination of the implied function of the two variables. Such an approach incorporates measures of uncertainty into performance estimates, allows inter-plant performance comparison, and could be used to simulate plant operation via sampling. A preliminary model is formulated and fitted to operational data as an illustration.
Autors: Stephen, B.;Galloway, S. J.;McMillan, D.;Hill, D. C.;Infield, D. G.;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2011, volume: 26, issue:2, pages: 965 - 966
Publisher: IEEE
 
» A Corpus-Based Approach to Speech Enhancement From Nonstationary Noise
Abstract:
Temporal dynamics and speaker characteristics are two important features of speech that distinguish speech from noise. In this paper, we propose a method to maximally extract these two features of speech for speech enhancement. We demonstrate that this can reduce the requirement for prior information about the noise, which can be difficult to estimate for fast-varying noise. Given noisy speech, the new approach estimates clean speech by recognizing long segments of the clean speech as whole units. In the recognition, clean speech sentences, taken from a speech corpus, are used as examples. Matching segments are identified between the noisy sentence and the corpus sentences. The estimate is formed by using the longest matching segments found in the corpus sentences. Longer speech segments as whole units contain more distinct dynamics and richer speaker characteristics, and can be identified more accurately from noise than shorter speech segments. Therefore, estimation based on the longest recognized segments increases the noise immunity and hence the estimation accuracy. The new approach consists of a statistical model to represent up to sentence-long temporal dynamics in the corpus speech, and an algorithm to identify the longest matching segments between the noisy sentence and the corpus sentences. The algorithm is made more robust to noise uncertainty by introducing missing-feature based noise compensation into the corpus sentences. Experiments have been conducted on the TIMIT database for speech enhancement from various types of nonstationary noise including song, music, and crosstalk speech. The new approach has shown improved performance over conventional enhancement algorithms in both objective and subjective evaluations.
Autors: Ji Ming;Srinivasan, R.;Crookes, D.;
Appeared in: IEEE Transactions on Audio, Speech, and Language Processing
Publication date: May 2011, volume: 19, issue:4, pages: 822 - 836
Publisher: IEEE
 
» A Course in Simulation and Demonstration of Humanoid Robot Motion
Abstract:
An introductory course for humanoid robot motion realization for undergraduate and graduate students is presented in this study. The basic operations of AX-12 motors and the mechanics combination of a 16 degrees-of-freedom (DOF) humanoid robot are presented first. The main concepts of multilink systems, zero moment point (ZMP), and feedback control are then introduced such that the students can understand the relationship between the ZMP position and the stability of the robot. Finally, the students can simulate the desired motion trajectory and realize the motion practically on the real humanoid robot. Taking this course, the students can not only learn robotic theories and control techniques for humanoid robot motion, but can also enhance their experience in hands-on experiments in executing the motion of a humanoid robot. The proposed educational strategy will enable students to progress easily to more advanced work on robot design and control in their future study or careers.
Autors: Liu, H.-Y.;Wang, W.-J.;Wang, R.-J.;
Appeared in: IEEE Transactions on Education
Publication date: May 2011, volume: 54, issue:2, pages: 255 - 262
Publisher: IEEE
 
» A critical survey and analysis of RFID anti-collision mechanisms
Abstract:
The anti-collision mechanism is an important part of RFID systems. Many algorithms were proposed in the literature, but most of them were designed based on the theory of Random Access (RA) systems. In this article, we review the various types of anti-collision systems and their corresponding algorithms. Different reading strategies are critically analyzed and compared by computer simulation. By comparing the different working mechanisms of RA and RFID systems, we show that a new theory is needed for the design and analysis of RFID anti-collision algorithm.
Autors: Zhu, Lei;Yum, Tak-Shing Peter;
Appeared in: IEEE Communications Magazine
Publication date: May 2011, volume: 49, issue:5, pages: 214 - 221
Publisher: IEEE
 
» A Cross-Layer Framework for Overhead Reduction, Traffic Scheduling, and Burst Allocation in IEEE 802.16 OFDMA Networks
Abstract:
IEEE 802.16 orthogonal frequency-division multiple access (OFDMA) downlink subframes have a special 2-D channel-time structure. Allocation resources from such a 2-D structure incur extra control overheads that hurt network performance. Existing solutions try to improve network performance by designing either the scheduler in the medium access control layer or the burst allocator in the physical layer, but the efficiency of overhead reduction is limited. In this paper, we point out the necessity of “codesigning” both the scheduler and the burst allocator to efficiently reduce overheads and improve network performance. Under the partial-usage-of-subcarriers model, we propose a cross-layer framework that covers overhead reduction, real-time and non-real-time traffic scheduling, and burst allocation. The framework includes a two-tier priority-based scheduler and a bucket-based burst allocator, which is more complete and efficient than prior studies. Both the scheduler and the burst allocator are tightly coupled together to solve the problem of arranging resources to data traffic. Given available space and bucket design from the burst allocator, the scheduler can well utilize the frame resource, reduce real-time traffic delays, and maintain fairness. On the other hand, with priority knowledge and resource assignment from the scheduler, the burst allocator can efficiently arrange downlink bursts to satisfy traffic requirements with low complexity. Through analysis, the cross-layer framework is validated to give an upper bound to overheads and achieve high network performance. Extensive simulation results verify that the cross-layer framework significantly increases network throughput, maintains long-term fairness, alleviates real-time traffic delays, and enhances frame utilization.
Autors: Liang, J.-M.;Chen, J.-J.;Wang, Y.-C.;Tseng, Y.-C.;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2011, volume: 60, issue:4, pages: 1740 - 1755
Publisher: IEEE
 
» A Current mode CMOS noise generator using multiple Bernoulli maps
Abstract:
image

Autors: This paper presents the analysis and design of a chaotic noise generator using statistical mechanic tools. The noise generator is a CMOS analog circuit operating in current mode, which generates chaotic signals using four Bernoulli chaotic maps with
Appeared in: Microelectronic Engineering
Publication date: May 2011
Publisher: Elsevier B.V.
 
» A Data-Driven Sparse GLM for fMRI Analysis Using Sparse Dictionary Learning With MDL Criterion
Abstract:
We propose a novel statistical analysis method for functional magnetic resonance imaging (fMRI) to overcome the drawbacks of conventional data-driven methods such as the independent component analysis (ICA). Although ICA has been broadly applied to fMRI due to its capacity to separate spatially or temporally independent components, the assumption of independence has been challenged by recent studies showing that ICA does not guarantee independence of simultaneously occurring distinct activity patterns in the brain. Instead, sparsity of the signal has been shown to be more promising. This coincides with biological findings such as sparse coding in V1 simple cells, electrophysiological experiment results in the human medial temporal lobe, etc. The main contribution of this paper is, therefore, a new data driven fMRI analysis that is derived solely based upon the sparsity of the signals. A compressed sensing based data-driven sparse generalized linear model is proposed that enables estimation of spatially adaptive design matrix as well as sparse signal components that represent synchronous, functionally organized and integrated neural hemodynamics. Furthermore, a minimum description length (MDL)-based model order selection rule is shown to be essential in selecting unknown sparsity level for sparse dictionary learning. Using simulation and real fMRI experiments, we show that the proposed method can adapt individual variation better compared to the conventional ICA methods.
Autors: Lee, K.;Tak, S.;Ye, J. C.;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: May 2011, volume: 30, issue:5, pages: 1076 - 1089
Publisher: IEEE
 
» A delay-dependent approach to robust generalized H2 filtering for uncertain continuous-time systems with interval delay?
Abstract:
 Highlights: ? The model is more general than zero lower bound case considered in the literature. ? Less conservative analysis conditions for GH2 filters have been proposed. ? Less conservative design for GH2 filters has been proposed.

Autors: This paper is interested in the problem of robust generalized H2 (GH2) filtering for uncertain continuous-time systems with a delay in the state and polytopic uncertainty in system matrices. The delay is assumed to vary in an interval with a nonzero
Appeared in: Signal Processing
Publication date: May 2011
Publisher: Elsevier B.V.
 
» A Digital Interface for Gaussian Relay and Interference Networks: Lifting Codes From the Discrete Superposition Model
Abstract:
For every Gaussian network, there exists a corresponding deterministic network called the discrete superposition network . We show that this discrete superposition network provides a near-optimal digital interface for operating a class consisting of many Gaussian networks in the sense that any code for the discrete superposition network can be naturally lifted to a corresponding code for the Gaussian network, while achieving a rate that is no more than a constant number of bits lesser than the rate it achieves for the discrete superposition network. This constant depends only on the number of nodes in the network and not on the channel gains or SNR. Moreover the capacities of the two networks are within a constant of each other, again independent of channel gains and SNR. We show that the class of Gaussian networks for which this interface property holds includes relay networks with a single source-destination pair, interference networks, multicast networks, and the counterparts of these networks with multiple transmit and receive antennas. The code for the Gaussian relay network can be obtained from any code for the discrete superposition network simply by pruning it. This lifting scheme establishes that the superposition model can indeed potentially serve as a strong surrogate for designing codes for Gaussian relay networks. We present similar results for the Gaussian interference network, MIMO Gaussian interference networks, MIMO Gaussian relay networks, and multicast networks, with the constant gap depending additionally on the number of antennas in case of MIMO networks.
Autors: Anand, M.;Kumar, P. R.;
Appeared in: IEEE Transactions on Information Theory
Publication date: May 2011, volume: 57, issue:5, pages: 2548 - 2564
Publisher: IEEE
 
» A Distributed Measurement Scheme for Internet Latency Estimation
Abstract:
Estimating latency between the hosts in the Internet can play a significant role in the improvement of the performance of many services that use latency among hosts to make routing decisions. A popular example is peer-to-peer networks that need to build an overlay between peers in a way that minimizes the message exchange delay among the peers. Acquisition of latency information requires a considerable amount of measurements to be performed at each node in order for that node to keep a record of its latency to all the other nodes. Moreover, measured latency values are frequently subject to change and need to be regularly repeated in order to be updated against network dynamics. This has motivated the use of techniques that alleviate the need for a large number of empirical measurements and try to predict the entire network latency matrix using a small set of latency measurements. Coordinate-based approaches are the most popular solutions to this problem. The basic idea behind coordinate-based schemes is to model the latency between each pair of nodes as the virtual distance among those nodes in a virtual coordinate system. This paper proposes a new decentralized coordinate-based solution to the problem of Internet delay measurement. The simulation results demonstrate that the proposed system provides relatively accurate estimations.
Autors: Hariri, N.;Hariri, B.;Shirmohammadi, S.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: May 2011, volume: 60, issue:5, pages: 1594 - 1603
Publisher: IEEE
 
» A Dual Band Microstrip-Fed Slot Antenna
Abstract:
A simple new design method to achieve a dual band microstrip-fed slot antenna is presented. It is shown that when two slot antennas are placed in series, the spacing between the two antennas can be adjusted to achieve an effective secondary resonance. The new resonance is found to be due to the mutual coupling between the two slot antennas. An approximate circuit model for the dual band antenna is presented to explain the dual band mechanism and to provide a design guideline. The model is validated with a prototype antenna that operates at 4.22 GHz and 5.26 GHz, which are commonly used as the downlink and uplink in satellite communications. Measured results show good return loss at both frequencies, and radiation patterns agree well with the simulations. The proposed antenna has a simple geometry can be easily produced using printed circuit board techniques for applications where compactness and multiband operation are of interest.
Autors: Mahmoud, M. N.;Baktur, R.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: May 2011, volume: 59, issue:5, pages: 1720 - 1724
Publisher: IEEE
 
» A Dual-Channel Ferroelectric-Gate Field-Effect Transistor Enabling nand -Type Memory Characteristics
Abstract:
We demonstrate here an oxide memory (OxiM) transistor as a new type of ferroelectric-gate field-effect transistor (FeFET), provided with a dual (top and bottom) channel, which can memorize channel conductance with a dynamic range exceeding . This new transistor consists entirely of the following oxide-based thin films: (bottom gate electrode); (ferroelectric); ZnO (semiconductor); and SiON (gate insulator). A notable feature of the OxiM transistor is that two types of FET, i.e., a top gate-type thin-film transistor (top-TFT) and a bottom gate-type FeFET (bottom-FeFET), are stacked with a conduction layer of thin ZnO film in common. The channel conductance of the top-TFT and the bottom-FeFET can be controlled independently by the top gate and the bottom gate, respectively. We were successful in fabricating a nand memory circuit using serially connected OxiM transistors. The dual-gate structure allows disturb-free reading. Multivalued data can also be memorized in an OxiM transistor with a retention time of over 3.5 months.
Autors: Kaneko, Y.;Tanaka, H.;Ueda, M.;Kato, Y.;Fujii, E.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: May 2011, volume: 58, issue:5, pages: 1311 - 1318
Publisher: IEEE
 
» A Dual-Input Digitally Driven Doherty Amplifier Architecture for Performance Enhancement of Doherty Transmitters
Abstract:
In this paper, the novel architecture of a dual-input and digitally driven Doherty amplifier is proposed with the aim of improving the performance of gallium–nitride (GaN) Doherty transmitters. In this work, the power efficiency is enhanced by using digital adaptive phase alignment to compensate for performance degradation due to bias and power-dependant phase misalignment between the carrier and peaking branches. For experimental validation, the proposed dual-input digital Doherty power amplifier (PA) was implemented using a 10-W GaN transistor. Measurement results demonstrate that the dual-input Doherty prototype exhibited a power-added efficiency (PAE) higher than 50% over an 8-dB output power back-off (OPBO) range. In comparison with the conventional fully analog Doherty PA, this represents a 10% improvement in PAE over the same OPBO range. Using a one-carrier Worldwide Interoperability for Microwave Access signal with a 7-dB peak-to-average power ratio, the dual-input Doherty PA, with digital adaptive phase alignment applied at the input of its peaking path, achieved a PAE of 57% at an average output power of 37.8 dBm, along with a adjacent channel power ratio (ACPR). This corresponds to an improvement of 7% in PAE and 1 dB in average output power for the same ACPR level in comparison with a conventional fully analog Doherty PA.
Autors: Darraji, R.;Ghannouchi, F. M.;Hammi, O.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: May 2011, volume: 59, issue:5, pages: 1284 - 1293
Publisher: IEEE
 
» A dye functionalized silver-silica core-shell nanoparticle organic light emitting diode
Abstract:
image

Autors:

Graphical abstract

 Graphical abstract:  Highlights: ? Rhodamine dye functionalized silver-silica core-shell nanoparticles were synthesized. ? They were used into an organic light emitting device (OLED). ? Much stable luminescence from the rh
Appeared in: Organic Electronics
Publication date: May 2011
Publisher: Elsevier B.V.
 
» A Dynamic Piecewise Linear Model for DC Transmission Losses in Optimal Scheduling Problems
Abstract:
This paper proposes a dynamic piecewise linear model to represent dc transmission losses in optimal scheduling problems. An iterative procedure is proposed, where the linear cuts to approximate quadratic losses in each transmission line are adjusted iteratively as the optimization problem is solved. Applications of this approach to the network constrained short-term hydrothermal scheduling problem and to static dc optimal power flow problems yield a higher accuracy in representing line transmission losses as compared to other approaches, such as a priori iterative estimation, static piecewise liner model and successive linear programming. Study cases for a large-scale system also show reasonable results regarding CPU times.
Autors: dos Santos, T. N.;Diniz, A. L.;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2011, volume: 26, issue:2, pages: 508 - 519
Publisher: IEEE
 
» A dynamic punch method to quantify the dynamic shear strength of brittle solids
Abstract:
Shear strength is an important material parameter for brittle solids. This parameter has been extensively used in material failure models. Although a few methods have been proposed to quantify this parameter under the static loading condition, there is no such a method available to measure it under dynamic loading conditions. This paper presents a punch shear device to measure the dynamic shear strength of brittle solids. In this method, a split Hopkinson pressure bar system (SHPB) is used to exert the dynamic load to a thin disc sample, which is placed in a specially designed holder to minimize the bending stress induced by punching. The sample holder also allows the punch head to load the sample directly and in combination with momentum-trap technique in SHPB, it enables soft recovery of the rock plug and rock ring produced by the punching test. The flexibility and applicability of this method is demonstrated by the application of an isotropic and fine-grained sandstone. Within the theoretical framework of the classical Mohr-Coulomb failure model, the obtained dynamic shear strengths are consistent with the dynamic tensile strengths for the same rock from the literature.
Autors: Huang, S.;Feng, X. T.;Xia, K.;
Appeared in: Review of Scientific Instruments
Publication date: May 2011, volume: 82, issue:5, pages: 053901 - 053901-5
Publisher: IEEE
 
» A Failure-Detection Strategy for IGBT Based on Gate-Voltage Behavior Applied to a Motor Drive System
Abstract:
In this paper, a novel failure-detection technique and its analog circuit for insulated gate bipolar transistors (IGBTs), under open- and short-circuit failures, are proposed. This technique is applied to a three-phase induction-motor (IM) drive system. The detection technique is adapted to detect failures of short-circuit and open-circuit in the IGBT, which is based on gate-signal monitoring. The most important issue of this technique is the reduction of time for fault detection. This is very important in a failure-tolerant IM drive based on the material-redundancy approach or protection systems since the detection must be done before the device is damaged, in approximately less than 10 . The experimental test and simulations are presented in order to validate the proposed fault-detection technique, and it is validated, achieving replacement of the damaged element in the most suitable time.
Autors: Rodriguez-Blanco, M. A.;Claudio-Sanchez, A.;Theilliol, D.;Vela-Valdes, L. G.;Sibaja-Teran, P.;Hernandez-Gonzalez, L.;Aguayo-Alquicira, J.;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: May 2011, volume: 58, issue:5, pages: 1625 - 1633
Publisher: IEEE
 
» A Family of Piezoelectric-Transformer-Based Bridgeless Continuous-Conduction-Mode Charge-Pump Power-Factor-Correction Electronic Ballasts
Abstract:
This paper presents a family of the piezoelectric-transformer (PT)-based bridgeless continuous-conduction-mode (CCM) charge-pump (CP) power-factor-correction (PFC) electronic ballasts for a 32-W 4-ft linear fluorescent lamp, including the voltage-source (VS) type, current-source (CS) type, and VS–CS (VSCS) type. By replacing the resonant tank and high-voltage transformers in discrete CCM VS, CS, and VSCS CP-PFC electronic ballasts with PTs, the cost and volume can be reduced. The experimental results compare the presented electronic ballasts according to the performance of power factor, total harmonic distortion, crest factor, dc-bus voltage stress, and efficiency.
Autors: Lin, R. -L.;Shih, H. -M.;Liu, C. -Y.;Liu, K. -B.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2011, volume: 47, issue:3, pages: 1149 - 1158
Publisher: IEEE
 

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