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Electrical and Electronics Engineering publications abstract of: 07-2010 sorted by title, page: 0
» 'Operational health' monitoring for confidence in long term electric field measurements
Abstract:
The paper describes practical aspects of electrostatic fieldmeter instrumentation for long term monitoring of electric fields in adverse environmental conditions. Examples of applications have been in studies of tank washing on large crude oil tankers and measurement of atmospheric electric fields. Particular attention is drawn to the technique developed for continuous monitoring of operational health to justify confidence in observations.
Autors: John, Chubb , John, Harbour
Appeared in: Journal of Electrostatics
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» 0.8?W 12-bit SAR ADC sensors interface for RFID applications
Abstract:
The design and first measuring results of an ultra-low power 12 bit successive-approximation ADC for autonomous multi-sensor systems are presented. The comparator and the DAC are optmised for low power consumption. The power consumption is 0.52?W from a 1.2V supply with a sample clock of 3.125kHz and 0.85?W at 6.25kHz. This gives 136pJ per conversion or 66fJ per conversion step. As per authors' knowledge, 66fJ per conversion step is the best reported so far.The ADC was realised in the NXP CMOS 0.14?m technology; the area was 0.35mm2. Only four metal layers were used in order to allow 3D integration of...
Autors: Daniela, De Venuto , David Tio, Castro , Youri, Ponomarev , Eduard, Stikvoort
Appeared in: Microelectronics Journal
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» 100 Gb/s optical access based on optical orthogonal frequency-division multiplexing
Abstract:
The ever-increasing bandwidth demand in access systems is catalyzing research and development activity in future ultra high-speed 100 Gb/s passive optical networks. In this article we discuss the principles, key advantages, and most recent demonstrations of a record 100 Gb/s OFDM-based PON as a future PON candidate architecture. Moreover, we provide an analysis of primary cost factors in a practical DSP-based OFDMA-PON implementation and survey the most recent achievements in this domain. Due to the combination of highly attractive advanced features and favorable related trends in longhaul 100 Gb/s fiber transmission, OFDMA-PON can be regarded as a very promising solution for future PON-based access.
Autors: Cvijetic, N.;Dayou Qian;Junqiang Hu;
Appeared in: IEEE Communications Magazine
Publication date: Jul 2010, volume: 48, issue:7, pages: 70 - 77
Publisher: IEEE
 
» 100 gigabit Ethernet transport: Part 2 [Guest editorial]
Abstract:
Over the past year, the development of 100 Gb/s per wavelength systems have moved from laboratory demonstrations to field trials to commercial deployment. In two previous issues of IEEE Communications Magazine on 100 Gb/s Ethernet (100GbE), we covered the key enabling technologies, implementation issues, network requirements, and field experiments. In this third installment of our series on 100GbE, we continue our investigation, contributing articles on network design issues, access technology, digital signal processing requirements, and more field trial results. We also explore technology trends for next-generation systems beyond 100 Gb/s per wavelength.
Autors: Wellbrock, G.;Wang, T.;Ishida, O.;
Appeared in: IEEE Communications Magazine
Publication date: Jul 2010, volume: 48, issue:7, pages: 24 - 24
Publisher: IEEE
 
» 100G and beyond with digital coherent signal processing
Abstract:
The demand for increased bandwidth is ever present. Coherent technology coupled with advanced modulation formats and digital signal processing is a key enabler for optical communication systems at 100 Gb/s and beyond. This article reviews the attributes of coherent systems in light of the challenges faced by system designers to realize increased bit rates for next-generation optical systems.
Autors: Roberts, K.;Beckett, D.;Boertjes, D.;Berthold, J.;Laperle, C.;
Appeared in: IEEE Communications Magazine
Publication date: Jul 2010, volume: 48, issue:7, pages: 62 - 69
Publisher: IEEE
 
» 100G Ethernet and OTU4 testing challenges: From the lab to the field
Abstract:
The combination of digital media, personal computing, and global networking is creating a radical shift in the telecom industry. However, the transport backbone, which was built on 10G wavelengths, is nearing capacity and is driving the need for upgrades to 40G and 100G. 100G Ethernet and OTU4 bring new fundamental concepts, which require new training and new testing. 100G Ethernet and OTU4 equipment is currently in development or in trial, and the next phase is to deploy this equipment in the field. This article is mostly based on the work done by IEEE P802.3ba and ITU-T Study Group 15 to provide an overview of how 100G Ethernet and OTU4 are different from previous technologies, and includes guidance on which tests need to be performed with these emerging technologies. 112G line side testing is also briefly discussed.
Autors: Drolet, P.;Duplessis, L.;
Appeared in: IEEE Communications Magazine
Publication date: Jul 2010, volume: 48, issue:7, pages: 78 - 82
Publisher: IEEE
 
» 2:1 Candidate Position Subsampling Technique for Fast Optimal Motion Estimation
Abstract:
The candidate position subsampling technique (CPST) basically chooses candidates in a search window at a sampling rate. The 2:1 CPST chooses half the candidates, and then selects one or more candidates that are considered as to be close to the optimal motion vector before conducting a fine search. The fine search is conducted by checking four neighbors of the chosen candidate(s) referred to as winner(s). The CPST can be combined with a fast optimal block-matching algorithm, such as the multilevel successive elimination algorithm (MSEA), in order to reduce the number of computations used in rejecting the non-best candidate. We propose a new 2:1 CPST fitted to the MSEA. The proposed algorithm adopts a new condition for the winner which helps to find the best candidate efficiently. Moreover, a fast motion estimation step is used to reduce the number of computations of the MSEA, and the peak signal-to-noise ratio (PSNR) compensation step is adopted to guarantee that the PSNR performance of the proposed algorithm is very close to that of the full search. Experimental results show that the proposed algorithm reduces the computational loads of the MSEA by 47.26% on average with only PSNR degradation in the worst case.
Autors: Lee, H.-S.;Jung, J.-H.;Park, D.-J.;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Jul 2010, volume: 20, issue:7, pages: 1052 - 1056
Publisher: IEEE
 
» 3-D FIR Cone-Shaped Filter Design by a Nest of McClellan Transformations and Its Variable Design
Abstract:
In this paper, the technique of a nest of McClellan transformations is proposed for the design of 3-D FIR cone- shaped filters. First, a transformation subfilter for fan-type mapping is found. Then the cosine term of a frequency variable of the above transformation subfilter is replaced by an embedded transformation subfilter which possesses circular contours. The technique stated above is also extended to design 3-D FIR variable cone-shaped filters such that the inclination of the cone-shaped filters can be adjusted online. Moreover, an efficient structure is proposed for the implementation of the designed filters. Several examples will be presented to demonstrate the effectiveness of the proposed method.
Autors: Shyu, J.-J.;Pei, S.-C.;Huang, Y.-D.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jul 2010, volume: 57, issue:7, pages: 1697 - 1707
Publisher: IEEE
 
» 3-D medical image compression usiNG 3-D wavelet coders
Abstract:
This paper presents compression of 3-D medical images using 3-Dwavelet encoders. Four wavelet transforms, namely, Daubechies 4, Daubechies 6, Cohen-Daubechies-Feauveau 9/7 and Cohen-Daubechies-Feauveau 5/3 are used in the first stage with encoders such as 3D SPIHT, 3D SPECK and 3D BISK are used in the second stage for the compression and the optimal wavelet-encoder combination is identified. Two versions of wavelet transform, symmetric and decoupled wavelet transform are considered. Experiments are performed using medical test images such as magnetic resonance images (MRI) and x-ray angiograms (XA). The performances of the proposed scheme are evaluated in terms of peak signal to...
Autors: N., Sriraam , R., Shyamsunder
Appeared in: Digital Signal Processing
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» 3-D numerical analysis of EHD turbulent flow and mono-disperse charged particle transport and collection in a wire-plate ESP
Abstract:
The present study attempts to develop a detailed numerical approach and a simulation procedure to predict the motion of gas, ions and particles inside a simple parallel plate channel containing a single corona wire. A hybrid FEM-FCT-FVM method is used: the FEM-FCT numerical algorithm is applied for modeling the steady-state corona discharge, while the turbulent gas flow and the particle motion under electrostatic forces are modeled using the commercial CFD code FLUENT. Calculations for the gas flow are carried out by solving the Reynolds-averaged Navier-Stokes equations and turbulence is modeled using the k-? turbulence model. An additional source term is...
Autors: Niloofar, Farnoosh , K., Adamiak , G.S.P., Castle
Appeared in: Journal of Electrostatics
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» 325 GHz Single Layer Sub-Millimeter Wave FSS Based Split Slot Ring Linear to Circular Polarization Convertor
Abstract:
A single layer, frequency selective surface based, sub-millimeter wave transmission polarizer is presented that converts incident slant linear 45° polarization into circular polarization upon transmission. The polarization convertor consists of a 30 mm diameter 10 thick silicon reinforced metalized screen containing 2700 resonator cells and perforated with nested split ring slot apertures. The screen was designed and optimized using CST Microwave Studio and predictions were validated experimentally by transmission measurements over the 250-365 GHz frequency range. This frequency range is used for remote environmental monitoring and 325 GHz represents a molecular emission line for H2O. The results obtained show good agreement between measured and modeled predictions. The measured 3 dB axial ratio bandwidth was 11.75%, measured minimum Axial Ratio was 0.19 dB and the measured insertion loss of the single layer screen was 3.38 dB.
Autors: Euler, M.;Fusco, V.;Cahill, R.;Dickie, R.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2010, volume: 58, issue:7, pages: 2457 - 2459
Publisher: IEEE
 
» 3D Nonlinear Super-Resolution Microwave Inversion Technique Using Time-Domain Data
Abstract:
A nonlinear three-dimensional full-wave inverse scattering method using time-domain data and models is presented. It successfully reconstructs 3D images of various unknown objects using time-domain data. The method uses Born-type iterations and a constrained minimization to reconstruct successively improved images. The use of time-domain data allows very few transmitters and receivers to be used. It is shown that this technique achieves super-resolution, namely 0.1 wavelength. The method is able to recover contrasts of over 2:1. It can also recover objects with minute contrasts of as low as 10%, thus taking a step towards addressing recent findings in the breast cancer imaging community, for example, that some breast tumors have only a 10% contrast with respect to the glandular tissues. This method could present a promising tool for the early-stage breast cancer detection as well as other medical and subsurface imaging applications.
Autors: Ali, M.A.;Moghaddam, M.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2010, volume: 58, issue:7, pages: 2327 - 2336
Publisher: IEEE
 
» 60 GHz beamforming using in-package bondwire antenna array
Abstract:
An antenna array using in-package bondwire to perform beamforming for 60 GHz applications is presented. 1 mil gold bondwire designed to resonate at 60 GHz was employed as an antenna array to provide smaller area and a cheaper way to manufacture it. The overall size of the bondwire antenna array on a CMOS chip is 1 x 3 mm2 and its radiation pattern shows fair agreement with simulation results.
Autors: Jeong, Y.S.;Kang, M.K.;Kim, T.W.;
Appeared in: Electronics Letters
Publication date: Jul 2010, volume: 46, issue:15, pages: 1047 - 1048
Publisher: IEEE
 
» 68–110-GHz-Band Low-Noise Amplifier Using Current Reuse Topology
Abstract:
This paper proposes a new topology for a broadband low-noise-amplifier (LNA). A common-gate (CG) amplifier with a matching inductor composes a unit cell, and the unit cells are cascaded to increase gain. As both the input and output impedances of the unit cell are matched to 50 for a wide frequency range, it is possible to increase the gain while maintaining wide bandwidth. Thus, high-gain and broadband performance can be obtained using this topology. The other features of the amplifier are its small size, low power consumption, and current reuse topology. This paper presents the design methodology of a multistage CG amplifier with a matching inductor. Fabricated in an 80-nm InP HEMT process, we developed an ultra-broadband LNA. The LNA with a three-stage CG amplifier exhibited a gain of 18 dB and a noise figure of 3.5 dB from 68 to over 110 GHz. The power consumption was 12 mW under a power supply voltage of 3 V. The chip size is 0.55 0.75 mm . Furthermore, we developed a receiver for passive millimeter-wave imagers by integrating a six-stage LNA with a power detector. The chip size of the receiver is 1.1 0.75 mm . The sensitivity of the pre-amplified detector was more than 2 000 V/mW from 75 to 100 GHz. These results show that the topology is one of the best candidates for high-gain and broadband LNA with small size and low power consumption.
Autors: Sato, M.;Takahashi, T.;Hirose, T.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2010, volume: 58, issue:7, pages: 1910 - 1916
Publisher: IEEE
 
» In Situ Doped Source/Drain for Performance Enhancement of Double-Gated Poly-Si Nanowire Transistors
Abstract:
A poly-Si nanowire (NW) thin-film transistor configured with the double-gated scheme was fabricated and characterized. The fabrication process features the clever use of selective plasma etching to form a rectangular NW underneath a hard mask. In this paper, we show that replacing the original ion-implanted poly-Si with in situ doped poly-Si for the source/drain significantly enhances the device performance, including steeper subthreshold swing (SS), larger on/off current ratio, and reduced series resistance. In particular, the SS is improved to a record-breaking low value of 73 mV/dec, which, to the best of our knowledge, is the most ideal ever reported for a poly-Si based device. The new NW transistors with such excellent switching properties are highly promising for reducing power consumption and operational voltage in practical circuit applications.
Autors: Chen, W.-C.;Lin, H.-C.;Chang, Y.-C.;Lin, C.-D.;Huang, T.-Y.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jul 2010, volume: 57, issue:7, pages: 1608 - 1615
Publisher: IEEE
 
» -Channel Multiple Description Coding With Two-Rate Coding and Staggered Quantization
Abstract:
A low complexity -channel multiple description coding scheme is developed in this paper, in which each description carries one subset of the input with a higher bit rate and the rest with a lower bit rate. The lower-rate codings in different descriptions are designed to be mutually refinable using staggered scalar quantizers. For correlated sources, a two-rate predictive coding is used in each description. Closed-form expressions of the distortions are derived when different numbers of descriptions are received. The application of the proposed scheme in lapped transform based image coding is also investigated, and the optimal transform is obtained. Experimental results using both 1-D memoryless sources and 2-D images demonstrate the superior performance of the proposed scheme.
Autors: Samarawickrama, U.;Liang, J.;Tian, C.;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Jul 2010, volume: 20, issue:7, pages: 933 - 944
Publisher: IEEE
 
» A 0.5-Hz High-Pass Cutoff Dual-Loop Transimpedance Amplifier for Wearable NIR Sensing Device
Abstract:
This brief describes a fully integrated dual-loop transimpedance amplifier with bandpass response for wearable near-infrared (NIR) sensing operating at low frequency: one loop to lower the lower band cutoff frequency and another loop for self-regulating DC photocurrent to prevent saturation at later stages. The circuit was implemented in a 0.35- CMOS process and achieved a DC photocurrent rejection ranging from 2.7 to 15 and a 3-dB high-pass cutoff frequency from 0.5 to 110 Hz by using on-chip capacitors. Both total harmonic distortion and spurious-free dynamic range are better than 42 dB. It achieves an improvement of 390 times in capacitor reduction compared with the traditional DC rejection technique.
Autors: Wong, A. K. Y.;Leung, K. N.;Pun, K.-P.;Zhang, Y.-T.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2010, volume: 57, issue:7, pages: 531 - 535
Publisher: IEEE
 
» A 10-mW Submillimeter-Wave Solid-State Power-Amplifier Module
Abstract:
In this paper, we demonstrate a packaged sub-millimeter wave solid-state power amplifier (SSPA). The SSPA is implemented in coplanar waveguide (CPW) and uses an advanced high InP HEMT transistor with a sub 50-nm gate. A monolithically integrated CPW dipole-to-waveguide transition eliminates the need for wirebonding and additional substrates. On-chip compact tandem couplers are used for power combining. The amplifier demonstrates 15-dB small-signal gain at 340 GHz. Peak saturated output power of 10 mW at 338 GHz is obtained at the waveguide flange output for the SSPA module.
Autors: Radisic, V.;Deal, W. R.;Leong, K. M. K. H.;Mei, X. B.;Yoshida, W.;Liu, P.-H.;Uyeda, J.;Fung, A.;Samoska, L.;Gaier, T.;Lai, R.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2010, volume: 58, issue:7, pages: 1903 - 1909
Publisher: IEEE
 
» A 2-D Artificial Dielectric With for the Terahertz Region
Abstract:
We demonstrate a 2-D artificial dielectric medium suitable for the terahertz region by exploiting the characteristic frequency dependence in the phase velocity of the lowest order transverse-electric mode of the parallel-plate waveguide (PPWG). This artificial medium exhibits a plasma-like behavior having a frequency-dependent refractive index that varies between zero and unity. Using this medium, we demonstrate the optical phenomena of total internal reflection and Brewster's effect, and also demonstrate a convergent PPWG-lens.
Autors: Mendis, R.;Mittleman, D. M.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2010, volume: 58, issue:7, pages: 1993 - 1998
Publisher: IEEE
 
» A 20 GS/s 1.2 V 0.13 CMOS Switched Cascode Track-and-Hold Amplifier
Abstract:
A low voltage, low power, high sampling rate trackand-hold amplifier (THA) architecture is proposed. The THA samples at 20 GS/s and combines a distributed amplifier and a switched cascode stage. Power consumption for the circuit is 71 mW and it occupies 0.09 in 0.13 CMOS. The THA delivers up to 34 dB spur-free dynamic range (SFDR) and 32 dB total harmonic distortion (THD) at a supply voltage of 1.2 V. Input return loss remains below 10 dB over all frequencies of interest, while output return loss remains below 15 dB.
Autors: Orser, H.;Gopinath, A.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2010, volume: 57, issue:7, pages: 512 - 516
Publisher: IEEE
 
» A 3-D Ritz solution for free vibration of circular/annular functionally graded plates integrated with piezoelectric layers
Abstract:
This paper addresses three-dimensional (3-D) free vibration characteristic of thick circular/annular functionally graded (FG) plates with surface-bonded piezoelectric layers on the basis of 3-D Ritz solution. Three displacement components along with electrical potential field of the plate are expressed by a set of Chebyshev polynomials multiplied by geometry boundary functions. Both open-circuit and closed-circuit surface conditions are taken into account. The mechanical properties of the FG plates are assumed to vary continuously through the thickness of the plate and obey either exponent or power law distribution of the volume fraction of the constituents. The effect of thickness-to-radius ratio, inner-to-outer radius...
Autors: Sh., Hosseini-Hashemi , M., Azimzadeh-Monfared , H., Rokni Damavandi Taher
Appeared in: International Journal of Engineering Science
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» A 520–590 GHz Crossbar Balanced Fundamental Schottky Mixer
Abstract:
We report on the design and performance of a crossbar broadband, biasable, balanced fundamental 520-590 GHz fix-tuned frequency mixer that utilizes planar Schottky diodes. The suspended stripline circuit is fabricated on a GaAs membrane mounted in a split waveguide block. The chip is supported by thick beam leads that are also used to provide precise RF grounding, RF coupling and DC/IF connections. At room temperature, the mixer has a measured DSB noise temperature of 2200 K at the low end of the band, and less than 4000 K across the design band.
Autors: Schlecht, E.T.;Gill, J.J.;Lin, R.H.;Dengler, R.J.;Mehdi, I.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jul 2010, volume: 20, issue:7, pages: 387 - 389
Publisher: IEEE
 
» A 56.5–72.2 GHz Transformer-Injection Miller Frequency Divider in 0.13 CMOS
Abstract:
A V-band Miller frequency divider with a locking range of 15.7 GHz (f0 = 64 GHz) is realized in 0.13 μm CMOS technology. Using the proposed transformer-injection technique, the signal can be injected into the mixer core directly without the current and impedance limitations of the input stage. The divider also features a fully differential topology. Under the condition of VDD = 0.9 V, the divider can even function with a power dissipation of only 0.81 mW.
Autors: Wei-Sung Chang;Kai-Wen Tan;Hsu, S.S.H.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jul 2010, volume: 20, issue:7, pages: 393 - 395
Publisher: IEEE
 
» A 60 GHz-Standard Compatible Programmable 50 GHz Phase-Locked Loop in 90 nm CMOS
Abstract:
This letter presents, for the first time, a 60 GHz four-channel standard compatible heterodyne frequency synthesizer solution with low-cost reference signal. The presented PLL features a dual-core varactor-based LC cross-coupled voltage-controlled oscillator (VCO). The measured phase noise is -80.1 dBc/Hz at 1 MHz offset, and it is limited by the phase noise of the reference signal. The measured output spectrum shows spur suppression higher than 32 dBc. Using the lowest reference frequency to date (27 MHz), the presented PLL is suitable for applications in low cost fully integrated multi-gigabit 60 GHz CMOS radio transceivers.
Autors: Barale, F.;Sen, P.;Sarkar, S.;Pinel, S.;Laskar, J.;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: Jul 2010, volume: 20, issue:7, pages: 411 - 413
Publisher: IEEE
 
» A 800Mb/s CMOS detection scheme for UWB impulse-radio communication
Abstract:
A CMOS detection procedure for ultra-wideband impulse radio (UWB-IR) communication system, employing Bi-Phase Shift Keying (BPSK) modulation scheme, is presented here. The chip, designed and fabricated in a 0.18 CMOS process, requires a supply voltage of 1.8V and occupies a die area of 0.01mm2. A train of Gaussian monocycle pulses (GMP), modulated by a random data sequence of 800Mb/s, is detected successfully by the detector. The detection scheme employing a very simple architecture with a power consumption of 3mW is well suited for non-coherent wireless communication system.
Autors: Mohiuddin, Hafiz , Nobuo, Sasaki , Takamaro, Kikkawa
Appeared in: AEU - International Journal of Electronics and Communications
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» A 9-bit 80 MS/s Successive Approximation Register Analog-to-Digital Converter With a Capacitor Reduction Technique
Abstract:
A 9-bit 80 MS/s successive approximation register analog-to-digital converter (ADC), which is suitable for low power and a small area, is presented. The 9-bit capacitor array consists of only 16 unit capacitors and a coupling capacitor due to the proposed binary-weighted split-capacitor arrays with a merged-capacitor switching technique. The proposed ADC includes a comparator with offset cancellation and uses digital calibration for error correction. The ADC is implemented in a 65-nm complimentary metal–oxide–semiconductor technology and occupies an active area of 0.068 with a reference buffer. The differential and integral nonlinearities of the ADC are less than 0.37 and 0.40 LSB, respectively. The ADC shows a signal-to-noise-distortion ratio of 50.71 dB, a spurious-free dynamic range of 66.72 dB, and an effective number of bits of 8.13 bits with a 78 MHz sinusoidal input at 80 MS/s. The ADC consumes 3.4 mW with the reference buffer at a 1.0-V supply and achieves a figure of merit of 78 fJ/conversion step.
Autors: Cho, Y.-K.;Jeon, Y.-D.;Nam, J.-W.;Kwon, J.-K.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2010, volume: 57, issue:7, pages: 502 - 506
Publisher: IEEE
 
» A to Bidirectional I/O Buffer With a Dynamic Gate Bias Generator
Abstract:
This paper presents a wide-range I/O buffer able to transmit and receive signals of 0.9/1.2/1.8/3.3/5.0 V by using a typical CMOS process. The Dynamic gate bias circuit in the proposed I/O buffer is composed of two voltage converters, an EOS (Electrical Overstress) protector, and standard logic cells. A High voltage detector detects voltage level of VDDIO and then generates several bias voltages to the Dynamic gate bias circuit. By using the Dynamic gate bias generator to generate appropriate gate drives for the triple-stacked MOS transistors in the Output stage, the gate-oxide overstress and hot-carrier degradation are avoided. A Floating N-well circuit in the proposed I/O buffer is used to remove undesirable leakage current paths. The proposed I/O buffer can operate at 10/40/50/40/10 MHz when VDDIO are biased at 5.0/3.3/1.8/1.2/0.9 V, respectively. The maximum speed is 50 MHz given a 19 pF load. The maximum static power consumption is merely justified by the measurements on silicon.
Autors: Wang, C.-C.;Hsu, C.-H.;Liu, Y.-C.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jul 2010, volume: 57, issue:7, pages: 1642 - 1653
Publisher: IEEE
 
» A Bayesian Reconstruction Method with Marginalized Uncertainty Model for Camera Motion in Microrotation Imaging
Abstract:
Reconstruction of a 3-D structure from multiple projection images requires prior knowledge of projection directions or camera motion parameters that describe the relative positions and orientations of 3-D structure with respect to the camera. These parameters can be estimated using, for instance, the conventional correlation alignment and feature-based methods. However, the alignment methods are not perfect, where the inaccuracy of the estimated motion parameters causes artifacts in the reconstruction. To overcome this problem, we propose a Bayesian approach to reconstruct the object that takes the motion uncertainty distribution into account. Moreover, we consider the motion parameters as nuisance parameters and integrate them out from the posterior distribution, assuming a Gaussian uncertainty model, which yields a statistical cost function to be minimized. The proposed method is applied in microrotation fluorescence imaging, where we aim at 3-D reconstruction of a rotating object from an image series, acquired by an optical microscope. The experiments with simulated and real microrotation datasets demonstrate that the proposed method provides visually and numerically better results than the traditional reconstruction methods, which ignore the uncertainty of the motion estimates.
Autors: Laksameethanasan, D.;Brandt, S. S.;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Jul 2010, volume: 57, issue:7, pages: 1719 - 1728
Publisher: IEEE
 
» A Behavior Model of a Dickson Charge Pump Circuit for Designing a Multiple Charge Pump System Distributed in LSIs
Abstract:
This brief discusses how each of multiple charge pump circuits in LSIs is designed in case where the power and ground line resistance is not negligible. A behavior model for a charge pump, including the local power and ground voltages as input parameters, is proposed and a systematic design methodology is then presented. A system designer can use the behavior model to determine the specifications on each pump and power and ground resistance for minimizing overall area.
Autors: Tanzawa, T.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2010, volume: 57, issue:7, pages: 527 - 530
Publisher: IEEE
 
» A bend loss-based singlemode fiber microdisplacement sensor
Abstract:
An all-fiber displacement sensor with a simple configuration is proposed and investigated theoretically and experimentally. The proposed fiber displacement sensor consists of a half-loop structure of high-bend loss singlemode fiber-1060XP. A ratiometric power measurement system for interrogating the proposed sensor is also presented. By measuring the change in ratio of bend loss in the ratiometric measurement system, a change in displacement can be measured assuming the ratiometric system is calibrated. The proposed macrobending fiber-based displacement sensor achieves a competitive resolution of circa 0.3 [mu]m and also benefits from simplicity compared with conventional fiber Bragg grating-based displacement sensor. The displacement sensor is sensitive to temperature and an experimental investigation of this sensitivity is presented. It is found that the ratio response has a linear variation with temperature; therefore, temperature dependence can be mitigated by a suitable correction process. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2231-2235, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.25446
Autors: Pengfei Wang, Yuliya Semenova, Qiang Wu, Gerald Farrell
Appeared in: Microwave and Optical Technology Letters
Publication date: Jul 2010
Publisher: Wiley InterScience
 
» A bibliography of the literature on process capability indices: 2000-2009
Abstract:
This paper contains a bibliography of approximately 530 journal papers and books on process capability indices for the period 2000-2009. The related literature is classified into four major categories, namely, books, review/overview papers, theory- and method-related papers, and special applications. Theory- and method-related papers are further classified into univariate and multivariate cases, and special applications include acceptance sampling plans, supplier selection, and tolerance design and other optimizations. Copyright © 2010 John Wiley & Sons, Ltd.
Autors: Bong-Jin Yum, Kwan-Woo Kim
Appeared in: Quality and Reliability Engineering International
Publication date: Jul 2010
Publisher: Wiley InterScience
 
» A Broadband 835–900-GHz Fundamental Balanced Mixer Based on Monolithic GaAs Membrane Schottky Diodes
Abstract:
The development of a 835–900-GHz biasable fundamental balanced mixer using planar GaAs Schottky diodes is presented. The monolithic microwave integrated circuit integrates two planar Schottky anodes in a balanced configuration, stripline filtering elements, and on-chip capacitor on a thin GaAs membrane. At 850 GHz, double side-band (DSB) mixer noise temperature of 2660 K and conversion loss of 9.25 dB are measured, respectively, at room temperature. When the mixer is cooled to 120 K, the DSB mixer noise temperature and conversion loss improve to 1910 K and 8.84 dB, respectively.
Autors: Thomas, B.;Maestrini, A.;Gill, J.;Lee, C.;Lin, R.;Mehdi, I.;de Maagt, P.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2010, volume: 58, issue:7, pages: 1917 - 1924
Publisher: IEEE
 
» A Broadband Folded Printed Quadrifilar Helical Antenna Employing a Novel Compact Planar Feeding Circuit
Abstract:
A broadband printed quadrifilar helical antenna employing a novel compact feeding circuit is proposed in this paper. This antenna presents an excellent axial ratio over a wide beamwidth, with a 29% bandwidth. A specific feeding circuit based on an aperture-coupled transition and including two 90° surface mount hybrids has been designed to be integrated with the quadrifilar antenna. Over the bandwidth, the measured reflection coefficient of the antenna fed by the wideband compact circuit has been found to be equal to or lower than -12 dB and the maximum gain varies between 1.5 and 2.7 dBic from 1.18 to 1.58 GHz. The half-power beamwidth is 150°, with an axial ratio below 3 dB over this range. The compactness of the feeding circuit allows small element spacing in array arrangements.
Autors: Caillet, M.;Clénet, M.;Sharaiha, A.;Antar, Y.M.M.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2010, volume: 58, issue:7, pages: 2203 - 2209
Publisher: IEEE
 
» A Built-In-Test Circuit for RF Differential Low Noise Amplifiers
Abstract:
This paper presents an efficient, low-cost, built-in test (BIT) circuit for radio frequency differential low noise amplifiers (DLNAs). The BIT circuit detects amplitude alterations at the outputs of the DLNA, due to parametric or catastrophic faults, and provides a single digital Pass/Fail indication signal. A triple modular redundancy approach has been adopted for the BIT circuit design to avoid possible yield loss in case of a malfunctioning test circuitry. The technique has been evaluated on a typical CMOS RF DLNA and simulation results are presented.
Autors: Dermentzoglou, L.;Arapoyanni, A.;Tsiatouhas, Y.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jul 2010, volume: 57, issue:7, pages: 1549 - 1558
Publisher: IEEE
 
» A Case for Optimized Protocols in the Creation of a Smarter Grid
Abstract:
The design trades made in choosing an appropriate protocol for the conveyance of meter data are discussed. The paper identifies “context” as the mechanism by which communication efficiencies are sometimes obtained. This paper concludes that while generalized protocols are commonly used to communicate between utility back-office applications, specialized protocols can yield an optimum solution when reaching endpoints.
Autors: Haynes, D. D.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Jul 2010, volume: 25, issue:3, pages: 1476 - 1482
Publisher: IEEE
 
» A Century of Development in Applied Electrostatics [History]
Abstract:
To most electrical engineers, the term electrostatics brings to mind some hazy visions of early electrical experimentation involving an ancient Greek, a dead cat, and a piece of amber. Many of us recreated this quaint demonstration of triboelectric charging and its subsequent attraction in high school physics class. Perhaps some, in more enlightened schools, substituted modern materials such as plastics and synthetic fibers. In university electrical engineering programs, electrostatics is usually ignored or relegated to mathematical simplifications involving quasi-electrostatic approximations of important applications in electromagnetics. Meanwhile, a serious work involves the state-of-the-art study of topics such as electrodynamics and digital electronics. These fields have dominated so many important advances in the 20th century.
Autors: Castle, G.S.P.;
Appeared in: IEEE Industry Applications Magazine
Publication date: Jul 2010, volume: 16, issue:4, pages: 8 - 13
Publisher: IEEE
 
» A Channel-Estimation and Data-Detection Scheme for Multiuser MIMO-CDMA Systems in Fading Channels
Abstract:
In this paper, we examine the effect of channel estimation errors on the performance of multiple-input–multiple-output (MIMO) systems that employ code-division multiple-access (CDMA) transmission. Channel estimation based on training techniques has widely been considered throughout the literature. However, employing these training techniques in MIMO-CDMA systems degrades system performance due to multiuser interference. This degradation is clear as the diversity advantage of the MIMO system diminishes with the increased level of interference. As a remedy to this problem, we propose a channel-estimation and data-detection scheme based on the superimposed training technique for space-time spreading systems. The proposed scheme enhances the performance of the space-time system by eliminating the interference effect from both the channel and data estimates using two decorrelators: channel and data decorrelators. We investigate the performance of the proposed estimation technique considering an asynchronous CDMA uplink transmission over frequency-selective slow-fading channels. In particular, we analyze the bit-error-rate (BER) performance of the multiuser system with two-transmit-antenna and -receive-antenna configuration over Rayleigh fading channels. Compared with other conventional estimation techniques, our results show that the proposed estimation technique is more robust to channel-estimation errors. Furthermore, both simulations and analytical results indicate that full system diversity is achieved.
Autors: Assra, A.;Hamouda, W.;Youssef, A.;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2010, volume: 59, issue:6, pages: 2830 - 2844
Publisher: IEEE
 
» A Class of Constrained Adaptive Beamforming Algorithms Based on Uniform Linear Arrays
Abstract:
A new class of adaptive beamforming algorithms is proposed based on a uniformly spaced linear array by constraining its weight vector to a specific conjugate symmetric form. The method is applied to the well-known reference signal based (RSB) beamformer and the linearly constrained minimum variance (LCMV) beamformer as two implementation examples. The effect of the additional constraint is equivalent to adding a second step in the derived adaptive algorithm. However, a difference arises for the RSB case since no direction-of-arrival (DOA) information of the desired signal is available, which leads to a two-stage structure for incorporating the imposed constraint. Compared to the traditional algorithms, the proposed ones can achieve a faster convergence speed and a higher steady state output signal-to-interference-plus-noise ratio, given the same stepsize.
Autors: Zhang, L.;Liu, W.;Langley, R. J.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Jul 2010, volume: 58, issue:7, pages: 3916 - 3922
Publisher: IEEE
 
» A Closed-Form Solution to Asymmetric Motion Profile Allowing Acceleration Manipulation
Abstract:
In this paper, we propose a new complete closed-form formula for asymmetric motion profiles of long, medium, and short distances, which enables easy manipulation of jerks in arrival time for effectively reducing the acceleration and thus the overshoot. The design parameter named jerk ratio is newly introduced to scale down the jerks during the deceleration period so that the velocity profile is in an asymmetric S-curve. Owing to the jerk ratio, the motion formulas are remarkably simplified in analytic forms for short, medium, and long distances. The effectiveness of the proposed approach will be illustrated with the sledge movement control in an optical data storage system by experiments.
Autors: Rew, K.-H.;Kim, K.-S.;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jul 2010, volume: 57, issue:7, pages: 2499 - 2506
Publisher: IEEE
 
» A CMOS low-voltage low-power temperature sensor
Abstract:
Temperature sensing circuits are used in a wide range of applications such as in the biomedical area, cold chain monitoring and industrial applications. In the biomedical area, temperature patient monitoring systems can be found in a wide range of hospital applications such as the intensive care unit, surgery rooms and clinical analysis. When the systems also incorporate also communication features, they form a telemedicine system in which the patients can be remotely monitored. The need of portability promotes a demand for sensors and signal conditioners that can be placed directly on the patient or even implanted. Implanted systems provide comfort...
Autors: Paulo Cesar, Crepaldi , Tales Cleber, Pimenta , Robson Luiz, Moreno
Appeared in: Microelectronics Journal
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» A Collaborative Multiagent Taxi-Dispatch System
Abstract:
This paper presents a novel multiagent approach to automating taxi dispatch that services current bookings in a distributed fashion. The existing system in use by a taxi operator in Singapore and elsewhere, attempts to increase customer satisfaction locally, by sequentially dispatching nearby taxis to service customers. The proposed dispatch system attempts to increase customer satisfaction more globally, by concurrently dispatching multiple taxis to the same number of customers in the same geographical region, and vis-à-vis human driver satisfaction. To realize the system, a multiagent architecture is proposed, populated with software collaborative agents that can actively negotiate on behalf of taxi drivers in groups of size N for available customer bookings. Theoretically, an analysis of the boundary and optimal multiagent taxi-dispatch situations is presented along with a discussion of their implications. Experimentally, the operational efficiency of the existing and proposed dispatch systems was evaluated through computer simulations. The empirical results, obtained for a 1000-strong taxi fleet over a discrete range of N , show that the proposed system can dispatch taxis with reduction in customer waiting and empty taxi cruising times of up to 33.1% and 26.3%, respectively; and up to 41.8% and 41.2% reduction when a simple negotiation speedup heuristic was applied.
Autors: Kiam Tian Seow;Nam Hai Dang;Der-Horng Lee;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jul 2010, volume: 7, issue:3, pages: 607 - 616
Publisher: IEEE
 
» A Collaborative Recommender System Based on Space-Time Similarities
Abstract:
The Internet of Things (IoT) concept promises a world of networked and interconnected devices that provides relevant content to users. Recommender systems can find relevant content for users in IoT environments, offering a user-adapted personalized experience. Collaboration-based recommenders in IoT environments rely on user-to-object, space-time interaction patterns. This extension of that idea takes into account user location and interaction time to recommend scattered, pervasive context-embedded networked objects. The authors compare their proposed system to memory-based collaborative methods in which user similarity is based on the ratings of previously rated items. Their proof-of-concept implementation was used in a real-world scenario involving 15 students interacting with 75 objects at Carlos III University of Madrid.
Autors: Munoz-Organero, Mario;Ramíez-González, Gustavo A.;Munoz-Merino, Pedro J.;Delgado Kloos, Carlos;
Appeared in: IEEE Pervasive Computing
Publication date: Jul 2010, volume: 9, issue:3, pages: 81 - 87
Publisher: IEEE
 
» A Combinatorial Approach to X-Tolerant Compaction Circuits
Abstract:
Test response compaction for integrated circuits (ICs) with scan-based design-for-testability (DFT) support in the presence of unknown logic values (Xs) is investigated from a combinatorial viewpoint. The theoretical foundations of X-codes, employed in an X-tolerant compaction technique called X-compact, are examined. Through the formulation of a combinatorial model of X-compact, novel design techniques are developed for X-codes to detect a specified maximum number of errors in the presence of a specified maximum number of unknown logic values, while requiring only small fan-out. The special class of X-codes that results leads to an avoidance problem for configurations in combinatorial designs. General design methods and nonconstructive existence theorems to estimate the compaction ratio of an optimal X-compactor are also derived.
Autors: Fujiwara, Y.;Colbourn, C. J.;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2010, volume: 56, issue:7, pages: 3196 - 3206
Publisher: IEEE
 
» A Combinatorial Solution for Model-Based Image Segmentation and Real-Time Tracking
Abstract:
We propose a combinatorial solution to determine the optimal elastic matching of a deformable template to an image. The central idea is to cast the optimal matching of each template point to a corresponding image pixel as a problem of finding a minimum cost cyclic path in the three-dimensional product space spanned by the template and the input image. We introduce a cost functional associated with each cycle, which consists of three terms: a data fidelity term favoring strong intensity gradients, a shape consistency term favoring similarity of tangent angles of corresponding points, and an elastic penalty for stretching or shrinking. The functional is normalized with respect to the total length to avoid a bias toward shorter curves. Optimization is performed by Lawler's Minimum Ratio Cycle algorithm parallelized on state-of-the-art graphics cards. The algorithm provides the optimal segmentation and point correspondence between template and segmented curve in computation times that are essentially linear in the number of pixels. To the best of our knowledge, this is the only existing globally optimal algorithm for real-time tracking of deformable shapes.
Autors: Schoenemann, Thomas;Cremers, Daniel;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jul 2010, volume: 32, issue:7, pages: 1153 - 1164
Publisher: IEEE
 
» A Compact 100-PPS High-Voltage Trigger Pulse Generator
Abstract:
Innovative design of a compact 100-pulses-per-second high-voltage trigger pulse generator, based on an incorporated structure with a curled parallel-plate capacitor and a spiral-strip pulse transformer, is presented. The repetitive trigger pulse generator was developed to trigger a trigatron, which has been used to pulse a 500-kV intense electron beam accelerator (IEBA). The trigger pulse generator consists of a spiral-strip transformer, a curled parallel-plate capacitor, two sharpening spark gaps, a repetitive controlling module, and a charging module. The generator system was designed based on the circuit theory and the electromagnetic theory. Experimental results show that the trigger pulse generator can deliver a 100-kV pulse with 80-ns rise time and 200-ns duration of full-width at half-maximum at a maximum repetition rate of 100 Hz. Due to its good stability, compact structure, and low cost, the high-voltage trigger pulse generator is an excellent candidate to trigger the IEBA system.
Autors: Liu, J.;Zhang, Y.;Chen, Z.;Feng, J.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jul 2010, volume: 57, issue:7, pages: 1680 - 1686
Publisher: IEEE
 
» A compact butler matrix for WLAN application
Abstract:
In this article, a compact butler matrix for wireless communications is designed and implemented at 2.4 GHz using defected ground structures (DGS).The butler matrix consists of a 3-dB coupler, crossover (0-dB coupler), and phase shifter. The 3-dB coupler and crossover are compacted using T-model of transmission line and DGS. The size of proposed butler matrix is about 35% of a conventional matrix. To verify simulation results, designed matrix has been implanted and measured. Fortunately, there is very good agreement between simulation results and measured results. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2294-2298, 2010; DOI 10.1002/mop.25474
Autors: Mohsen Maddah-Ali, Keyvan Forooraghi
Appeared in: Microwave and Optical Technology Letters
Publication date: Jul 2010
Publisher: Wiley InterScience
 
» A Compact Parallel-Plane Perpendicular-Current Feed for a Modified Equiangular Spiral Antenna
Abstract:
The design and measurement is described of a compact (59.94 mm × 59.94 mm × 1.14 mm) bidirectional ultrawideband modified equiangular spiral antenna with an integrated feed internally matched to a 50-Ohm microstrip transmission line. An ultrawideband transition from microstrip to parallel-strip line soldered to a short (1.14 mm) twin-line transmission line feeds the spiral. The currents on the feed travel in a direction approximately perpendicular to the direction of the currents on the spiral at the points where the feed passes the spiral in close proximity (0.57 mm). Holes were etched from the metal arms of the spiral to reduce the impedance mismatch caused by coupling between the transmission line feed and the spiral. Measured and simulated radiation patterns and VSWR plots show good performance over the ultrawideband range (3.1-10.6 GHz) with a 2:1 VSWR everywhere in this range except for 3.33-3.95 GHz, which has a 3:1 VSWR. This spiral exhibits an elliptical polarization over the ultrawideband range.
Autors: Eubanks, T.W.;Kai Chang;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2010, volume: 58, issue:7, pages: 2193 - 2202
Publisher: IEEE
 
» A compact pentagonal monopole antenna for portable UWB systems
Abstract:
Design of a compact microstrip-fed ultra-wideband antenna suitable for USB dongle and other such space constraint applications is presented. The structure consists of a pentagonal monopole element and a modified ground plane that gives an impedance bandwidth from 2.8 to 12 GHz. Radiation patterns are stable and omni-directional throughout the band with an average gain of 2.84 dBi. The antenna occupies only 11 ◊ 30 mm2 on FR4 substrate with permittivity 4.4. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2390-2393, 2010; DOI 10.1002/mop.25449
Autors: Paulbert Thomas, M. Gopikrishna, C. K. Aanandan, P. Mohanan, K. Vasudevan
Appeared in: Microwave and Optical Technology Letters
Publication date: Jul 2010
Publisher: Wiley InterScience
 
» A Compact Printed Antenna With an Embedded Double-Tuned Metamaterial Matching Network
Abstract:
A compact antenna intended for use in a laptop computer is proposed with the antenna consisting of a simple radiating strip and a matching network based on a metamaterial particle. The matching network is used to increase the -10 dB bandwidth of the antenna. Double-tuned matching network theory is used to increase the bandwidth of the antenna by forming a loop on the Smith Chart inside a given VSWR circle. The matching network is implemented using a complementary-split-ring-resonator (CSRR) microstrip network to act as a shunt LC network. This is confirmed by means of a circuit model to model the CSRR-microstrip network. Finally the antenna is fabricated and tested with the measured and simulated results showing good agreement. The measured antenna has 560 MHz of bandwidth centered at 2.54 GHz with an efficiency of 89%.
Autors: Selvanayagam, M.;Eleftheriades, G.V.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2010, volume: 58, issue:7, pages: 2354 - 2361
Publisher: IEEE
 
» A Compact Repetitive Unipolar Nanosecond-Pulse Generator for Dielectric Barrier Discharge Application
Abstract:
Dielectric barrier discharge excitated by pulsed power is a promising approach for producing nonthermal plasma at atmospheric pressure, but pulsed power generators vary widely in performance and should be chosen according to application requirements. In this paper, a repetitive unipolar nanosecond-pulse generator is constructed using resonant charging and one-stage magnetic compression circuits, where IGBT and magnetic switches are the key units, respectively. The generator is capable of providing repetitive pulses with a voltage of up to 30 kV and duration of 70 ns at a 300 resistive load. Output pulse voltage can be adjusted by varying ac input voltage or trigger pulse-width. This compact and convenient generator has been used successfully to produce stable dielectric barrier discharge.
Autors: Tao Shao;Dongdong Zhang;Yang Yu;Cheng Zhang;Jue Wang;Ping Yan;Yuanxiang Zhou;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jul 2010, volume: 38, issue:7, pages: 1651 - 1655
Publisher: IEEE
 
» A Compact Wideband Leaky-Wave Antenna With Etched Slot Elements and Tapered Structure
Abstract:
A compact wideband leaky-wave antenna (LWA) with etched slot elements and tapered structure is studied. The proposed antenna is composed of an asymmetric-fed multi-section tapered short leaky-wave antenna with two embedded slots and a ground plane with etched slot elements. Base on the concept of LWA, the asymmetric-fed is utilized to excite the first higher order mode. By etching slot elements on the ground plane, the current distribution of this antenna can be influenced to compact the width of conventional LWA. In order to achieve the impedance matching, this multi-section tapered short leaky-wave antenna is embedded with two rectangular slots. This technique not only improves the impedance matching but also suppresses the back lobe. According to the measured results, the impedance bandwidth achieves about 1.30 GHz for 7-dB return loss, which covers the range from 3.30 to 4.60 GHz, and the scanning angle of the measured main beam is about 36°, which covers the range from 17° to 53°. This short LWA is only about 1.14 λ0 at 3.4 GHz, and the back lobe can be suppressed by 7.5 dB at 4.3 GHz. Due to the etched slot elements on the ground plane, the frequency of the radiation angle is shifted to lower frequency by 750 MHz, which can compact the width of LWA by more than 20%.
Autors: Jin-Wei Wu;Jou, C.F.;Chien-Jen Wang;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2010, volume: 58, issue:7, pages: 2176 - 2183
Publisher: IEEE
 
» A comparative analysis and design of quantum-dot cellular automata memory cell architecture
Abstract:
Quantum-dot cellular automata (QCA) nanotechnology is considered as the best candidate for memory system owing to its dense packages and low power consumption. This paper analyzes the drawbacks of the previous QCA memory architectures and improves memory cell that exploits regular clock zone layout by employing two new clocking signals and a compact Read/Write circuit. The proposed layout is verified with the modified QCADesigner simulator and is analyzed by considering the noise effect. This design, occupying only a fraction of the area compared with the previous memory design, has superior performance. It is shown that the clock circuitry is very regular, helping manufacturability for physical implementation. Comparisons show that Read/Write latency of the proposed design is mitigated, the overall cell number, control cell and layout area are reduced (100%), and its performance against random charge noise is presented to be better. Copyright © 2010 John Wiley & Sons, Ltd.
Autors: Xiaokuo Yang, Li Cai, Hongtu Huang, Xiaohui Zhao
Appeared in: International Journal of Circuit Theory and Applications
Publication date: Jul 2010
Publisher: Wiley InterScience
 
» A Comparative Study of Calderón Preconditioners for PMCHWT Equations
Abstract:
The Calderón identities are used to precondition the Poggio-Miller-Chang-Harrington-Wu-Tsai (PMCHWT) equations for wave scattering by dielectric objects. Based on the Calderón identities, several versions of preconditioners are presented and studied. The memory requirements and computational costs of different preconditioners are analyzed and discussed. The convergence properties of the iterative solutions and the solution accuracy of the Calderón preconditioned PMCHWT equations are also investigated and compared theoretically and numerically at different frequencies. With the help of the Calderón preconditioners, the convergence rate of the iterative solutions of the PMCHWT equations is significantly improved. Several numerical examples are given to show the performance of the Calderón preconditioners and to draw some conclusions.
Autors: Su Yan;Jian-Ming Jin;Zaiping Nie;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2010, volume: 58, issue:7, pages: 2375 - 2383
Publisher: IEEE
 
» A comparative study of self-heating effect of nMOSFETs fabricated on SGOI and SGSOAN substrates
Abstract:
In this work, for the first time, the electrical and thermal characteristics of strained Si/SiGe nanoscale n type metal-oxide-silicon field-effect transistors (MOSFETs) with silicon-on-aluminum nitride (SOAN) substrate are investigated by ISE TCAD. This novel structure is named as SGSOAN nMOSFET. A comparative study of self-heating effect (SHE) of nMOSFETs fabricated on SGOI and SGSOAN are presented in this paper. Numerical study results show that this novel SGSOAN structure can greatly eliminate excessive self-heating in devices, which gives a more promising application for SGOI to work at high temperature.
Autors: Hongxia, Liu , Bin, Li , Jin, Li , Bo, Yuan
Appeared in: Microelectronics Reliability
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» A comparison between LQR control for a long string of SISO systems and LQR control of the infinite spatially invariant version?
Abstract:
In this paper we consider a long string of SISO systems which in the limit becomes a scalar infinite spatially invariant system. We compare the LQR control for long-but-finite strings with the LQR control for the corresponding infinite strings. We give analytical and numerical examples where these are quite different and we investigate the cause. In addition, we obtain sufficient conditions for the LQR solutions to be similar as the length of the string increases.
Autors: Ruth, Curtain , Orest, Iftime , Hans, Zwart
Appeared in: Automatica
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» A Comparison of Two-Phase Computational Fluid Dynamics Codes Applied to the ITER First Wall Hypervapotron
Abstract:
Enhanced radial transport in the plasma and the effect of ELMS may increase the ITER first wall heat loads to as much as 4 to 5 over localized areas. One proposed heatsink that can handle these higher loads is a CuCrZr hypervapotron. One concept for a first wall panel consists of 20 hypervapotron channels, each measuring 1400 mm long and 48.5 mm wide. The nominal cooling conditions anticipated for each channel are 400 g/s of water at 3 MPa and 100 . This will result in boiling over a portion of the total length. A two-phase thermalhydraulic analysis is required to predict accurately the thermal performance. Existing heat transfer correlations used for nucleate boiling are not appropriate here because the flow does not reach fully developed conditions in the multi-segmented channels. Our design-by-analysis approach used two commercial codes, Fluent and Star-CCM+, to perform computational fluid dynamics analyses with conjugate heat transfer. Both codes use the Rensselear (RPI) model for wall heat flux partitioning to model nucleate boiling as implemented in user-defined functions. We present a comparison between the two codes for this Eulerian multiphase problem that relies on temperature dependent materials properties. The analyses optimized the hypervapotron geometry, including teeth height and pitch, as well as the depth of the back channel to permit highly effective boiling heat transfer in the grooves between the teeth while ensuring that no boiling could occur at the back channel exit. The analysis used a representative heat flux profile with the peak heat flux of 5 limited to a 50 mm length. The maximum surface temperature of the heatsink is 415 $^{circ}hbox{C}- - $. The baseline design uses 2 mm for the teeth height, a 3 mm width and 6 mm pitch, and a back channel depth of 8 mm. The teeth are detached from the sidewall by a 2-mm-wide slot on both sides that aids in sweep-out and quenching of the vapor bubbles.
Autors: Youchison, D. L.;Ulrickson, M. A.;Bullock, J. H.;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jul 2010, volume: 38, issue:7, pages: 1704 - 1708
Publisher: IEEE
 
» A comparison study on the dynamics of planar 3-DOF 4-RRR, 3-RRR and 2-RRR parallel manipulators
Abstract:
This paper presents a comparison study on the dynamics of three planar 3-DOF parallel manipulators, one with 3-RRR structure, and the other two with 2-RRR and 4-RRR structures. The inverse kinematics and Jacobian matrix of these mechanisms are analyzed. The dynamic formulations in the linear form are derived and a dynamic performance index is given to compare their dynamic performances. The results show that the 2-RRR parallel manipulator has the worst dynamic performance.
Autors: Jun, Wu , Jinsong, Wang , Zheng, You
Appeared in: Robotics and Computer-Integrated Manufacturing
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» A Complete Description of the QoS Feasibility Region in the Vector Broadcast Channel
Abstract:
We characterize the complete quality-of-service (QoS) feasibility region and present a simple feasibility test for given QoS requirements in the Gaussian vector broadcast channel. While most contributions in the literature recast the QoS constraints into requirements for the signal-to-interference-and-noise ratios (SINRs), we convert them into upper bounds for the minimum mean square errors (MMSEs) instead and test feasibility in the MMSE domain. Our main contribution is a complete description of the feasible MMSE region. Its closure is shown to be a polytope and we find the complete set of its bounding half-spaces noniteratively after a finite number of steps. The polytope can easily be converted into any other QoS domain like SINR or rate. However, the simple geometry of the MMSE domain is lost in other domains. Once the bounding half-spaces are determined, any target MMSE tuple can quickly be checked for feasibility by verifying its membership to the interior of the polytope. For nondegenerate channels, the only relevant bounding half-space is essentially the lower bound on the sum mean square error. No further computations are necessary contrary to existing feasibility checks which iteratively solve eigenproblems in an alternating optimization framework for every single QoS requirement to test. For two particular user/antenna configurations, we find a noniterative closed form solution for the optimum power allocation of the signal-to-interference ratio (SIR) balancing.
Autors: Hunger, R.;Joham, M.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Jul 2010, volume: 58, issue:7, pages: 3870 - 3878
Publisher: IEEE
 
» A Computer-Aided Diagnosis System of Nuclear Cataract
Abstract:
Cataracts are the leading cause of blindness worldwide, and nuclear cataract is the most common form of cataract. An algorithm for automatic diagnosis of nuclear cataract is investigated in this paper. Nuclear cataract is graded according to the severity of opacity using slit lamp lens images. Anatomical structure in the lens image is detected using a modified active shape model. On the basis of the anatomical landmark, local features are extracted according to clinical grading protocol. Support vector machine regression is employed for grade prediction. This is the first time that the nucleus region can be detected automatically in slit lamp images. The system is validated using clinical images and clinical ground truth on >5000 images. The success rate of structure detection is 95% and the average grading difference is 0.36 on a 5.0 scale. The automatic diagnosis system can improve the grading objectivity and potentially be used in clinics and population studies to save the workload of ophthalmologists.
Autors: Li, H.;Lim, J.;Liu, J.;Mitchell, P.;Tan, A.;Wang, J.;Wong, T.;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Jul 2010, volume: 57, issue:7, pages: 1690 - 1698
Publisher: IEEE
 
» A constraint programming approach to tool allocation and production scheduling in flexible manufacturing systems
Abstract:
This paper presents a constraint programming (CP) methodology to deal with the scheduling of flexible manufacturing systems (FMSs). The proposed approach, which consists of both a model and a search strategy, handles several features found in industrial environments, such as limitations on number of tools in the system, lifetime of tools, as well as tool magazine capacity of machines. In addition, it tackles the problem in a integrated way by considering tool planning and allocation, machine assignment, part routing, and task timing decisions altogether in the approach. The formulation, which is able to take into account a variety of objective...
Autors: L.J., Zeballos
Appeared in: Robotics and Computer-Integrated Manufacturing
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» A Context-Sensitive Technique Robust to Registration Noise for Change Detection in VHR Multispectral Images
Abstract:
This paper presents an automatic context-sensitive technique robust to registration noise (RN) for change detection (CD) in multitemporal very high geometrical resolution (VHR) remote sensing images. Exploiting the properties of RN in VHR images, the proposed technique analyzes the distribution of the spectral change vectors (SCVs) computed according to the change vector analysis (CVA) in a quantized polar domain. The method studies the SCVs falling into each quantization cell at different resolution levels (scales) to automatically identify the effects of RN in the polar domain. This information is jointly exploited with the spatial context information contained in the neighborhood of each pixel for generating the final CD map. The spatial context information is modeled through the definition of adaptive regions homogeneous both in spatial and temporal domain (parcels). Experimental results obtained on real VHR remote sensing multitemporal images confirm the effectiveness of the proposed technique.
Autors: Marchesi, S.;Bovolo, F.;Bruzzone, L.;
Appeared in: IEEE Transactions on Image Processing
Publication date: Jul 2010, volume: 19, issue:7, pages: 1877 - 1889
Publisher: IEEE
 
» A Control Scheme With Energy Saving and DC-Link Overvoltage Rejection for Induction Motor Drives of Electric Vehicles
Abstract:
This paper presents a control scheme for an induction motor that integrates, within a coherent solution, some of the features that are commonly required from an electric vehicle drive. The main features of the proposed control scheme are the capability to exploit the maximum torque in the whole speed range, a weak dependence on the motor parameters, a good robustness against the variations of the dc-link voltage, and, whenever possible, the maximum efficiency. The performance of the control scheme is verified by experimental tests.
Autors: Casadei, D.;Mengoni, M.;Serra, G.;Tani, A.;Zarri, L.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2010, volume: 46, issue:4, pages: 1436 - 1446
Publisher: IEEE
 
» A Control Strategy for Hybrid Power Filter to Compensate Four-Wires Three-Phase Systems
Abstract:
A control algorithm is proposed for a three-phase hybrid power filter constituted by a series active filter and a shunt passive filter. The control strategy is based on the dual formulation of the compensation system principles. It is applied by considering a balanced and resistive load as ideal load, so that the voltage waveform injected by the active filter is able to compensate the reactive power, to eliminate harmonics of the load current and to balance asymmetrical loads. This strategy improves the passive filter compensation characteristics without depending on the system impedance, and avoiding the series/shunt resonance problems, since the set load-filter would present resistive behavior. An experimental prototype was developed and experimental results are presented.
Autors: Salmerón, P.;Litrán, S. P.;
Appeared in: IEEE Transactions on Power Electronics
Publication date: Jul 2010, volume: 25, issue:7, pages: 1923 - 1931
Publisher: IEEE
 
» A convexity-based homotopy method for nonlinear optimization in model predictive control
Abstract:
This paper presents a convexity-based homotopy solution procedure to non-convex optimal control problems (OCPs) arising in model predictive control. The approach deals with a special class of OCP formulations, where the dynamic system involved is control-affine and the objective is a penalty on deviations from a state reference trajectory. The non-convex OCP is modified by introducing a penalized pseudo state and a homotopy parameter which gradually transforms the original problem into a convex one. The method solves first this convex formulation and uses the result to initialize the solution of the next problem on the zero path, recovering the original OCP. The proposed methodology is evaluated for the benchmark control problem of an isothermal chemical reactor with Van de Vusse reactions and input multiplicity. For the simple case with control horizon one, the method is able to find the global solution due to the convex initialization, while local optimization techniques only lead to a local minimum. Copyright © 2010 John Wiley & Sons, Ltd.
Autors: JuliŠn Bonilla, Moritz Diehl, Filip Logist, Bart De Moor, Jan F. M. Van Impe
Appeared in: Optimal Control Applications and Methods
Publication date: Jul 2010
Publisher: Wiley InterScience
 
» A Cooperative Multicast Strategy in Wireless Networks
Abstract:
Multicast is a bandwidth-efficient mechanism to provide wireless services for a group of terminals. Providing reliable wireless multicast is challenging due to packet loss and channel fading. In this research, we investigate the medium-access-control (MAC) layer cooperation to enhance the reliability of wireless multicast. We show that the optimal relaying strategy is a pure threshold policy, i.e., the optimal number of relays is bounded by a threshold. We also propose a simple and efficient algorithm to find the optimal time allocation for the direct and relay transmissions.
Autors: Niu, B.;Jiang, H.;Zhao, H. V.;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jul 2010, volume: 59, issue:6, pages: 3136 - 3143
Publisher: IEEE
 
» A Critical Cross-Examination on Load-Balancing Transformers for Distribution Systems
Abstract:
A load balancing transformer (LBT) has already been suggested for improving the unbalance of three-phase primary currents. Each phase includes one extra pair of coupling windings in addition to the usual primary and secondary windings. Two coupling windings, located on two different phases, are made in series, where the resulting circuit is then reversely paralleled with the secondary winding placed on the third phase. Under unbalanced conditions, the load currents are distributed between the coupling and secondary windings that are supplied through different primary phases. This paper proposes a method in order to define all possible LBTs, which paves the way to cross-examine and select the best connections of windings for the LBT. Starting from the original LBT, it is shown that the best LBT is practically connected, such as a zig-zag winding. Then, a novel idea is suggested in which a controller and some four-quadrant semiconductor switches contribute to the improvement of the performance of the LBT. These switches should control the amount of current transfer from one phase to another. A combinatorial selection problem is arranged to find the best way of switching modulation. Both simulations and experimental works (using a designed 12-kVA laboratory prototype) verify the studied examination and proposals, showing the switch-mode zig-zag LBT as having the best performance.
Autors: Ahmadi, D.;Bina, M. T.;Golkar, M. A.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Jul 2010, volume: 25, issue:3, pages: 1645 - 1656
Publisher: IEEE
 
» A Cross-Layer Approach-Based Gnutella for Collaborative Virtual Environments over Mobile Ad Hoc Networks
Abstract:
Collaborative Virtual Environments (CVEs) such as military training programs, emergency preparedness simulations, and online games place strict requirements on network performance when participating users share the 3D virtual environment through their mobile devices in an ad hoc network. However, most support systems for existing CVEs are confined to a desktop setting, thus preventing collaboration while users are mobile. In this work, we propose and evaluate a Gnutella peer-to-peer network over mobile ad hoc networks (MANETs) to support Mobile Collaborative Virtual Environment (MCVE) applications. Both architectures share some common features such as decentralization, self-reorganization, and self-healing. However, peer-to-peer networks and MANETs operate on different network layers, and thus, cause poor performance. To address this problem, we explore a novel cross-layer approach to improve the overall performance of CVEs over MANETs. The network layer should be aware of the user's physical position in the virtual environment (VE) in order to minimize network traffic and cope with a moderate workload between nodes. In this paper, we present a cross-layer approach model for collaborative virtual environment over MANET. We describe its implementation and evaluate its performance using NS2 simulator.
Autors: Boukerche, A.;Zarrad, A.;Araujo, R.B.;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jul 2010, volume: 21, issue:7, pages: 911 - 924
Publisher: IEEE
 
» A Cusum-Based Multilevel Alerting Method for Physiological Monitoring
Abstract:
Alerting systems used by current physiological monitors are designed to detect changes in the levels of vital signs, but they tend to be very sensitive to artifacts. This paper proposes a method to detect changes in the direction of trend and generate multilevel alerts according to the statistical significance of the detection. One-point-ahead signal predictions are calculated by averaging the historical data with the weights decreasing in the past. The two-sided cumulative sums (Cusum) of the prediction errors are tested against multiple thresholds to detect change points with two levels of certainty. The temporal shapes of the detected changes are analyzed using heuristics to determine whether to trigger an alert. The method was tested offline using 20 cases collected during surgery at a local hospital. The detection results were evaluated by two experienced anesthesiologists. The direction of trend was correctly detected in of the annotated changes for end-tidal carbon dioxide, for expiratory minute volume, for peak airway pressure, and for noninvasive blood pressure. The certainty levels of the true-positive alerts estimated by the algorithm have a high ratio of agreement with the anesthesiologists’ evaluations.
Autors: Yang, P.;Dumont, G.;Ansermino, J. M.;
Appeared in: IEEE Transactions on Information Technology in Biomedicine
Publication date: Jul 2010, volume: 14, issue:4, pages: 1046 - 1052
Publisher: IEEE
 
» A Data Capturing Method for Buses on Chip
Abstract:
In this paper, a new data reading technique for a bus of lines is proposed for fast operation. The proposed method utilizes multiple reference voltages available within a line's receiving logic and the initial conditions of wires in order to determine early and accurately the transmitted data of the current cycle. The presented technique does not require repeater insertion for reasonably long lines and it can significantly accelerate signal propagation. Experimental results are given in the 65 nm CMOS process for interconnects of various lengths.
Autors: Skoufis, M. N.;Karmarkar, K.;Tragoudas, S.;Haniotakis, T.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jul 2010, volume: 57, issue:7, pages: 1631 - 1641
Publisher: IEEE
 
» A delta-method technique in the wavelet domain to determine statistical quantities of the response of electromagnetic devices with uncertain parameters
Abstract:
In this paper a method to determine the mean value and the variance of the response of a system with uncertain parameters is proposed. With the term 'response of a system' we indicate either the value of a single parameter that represents a figure of merit of a device (e.g. the efficiency of a transmission system or the band width of a communication channel) or a characteristic function of the system (e.g. the impulse or the frequency response). In the latter case we estimate the mean value and the variance at every sample of the response. The estimate is performed by using the delta method, a technique for approximating expected values of functions of random variables when the direct evaluation is not feasible. Two examples of the application of the proposed procedure are reported and the results are compared with simulations performed by a Monte Carlo analysis. Copyright © 2010 John Wiley & Sons, Ltd.
Autors: Sami Barmada, Antonino Musolino, Marco Raugi, Mauro Tucci
Appeared in: International Journal of Numerical Modelling: Electronic Networks, Devices and Fields
Publication date: Jul 2010
Publisher: Wiley InterScience
 
» A differential quadrature analysis of dynamic and quasi-static magneto-thermo-elastic stresses in a conducting rectangular plate subjected to an arbitrary variation of magnetic field
Abstract:
A rapid, convergent and accurate differential quadrature method (DQM) is employed for numerical simulation of dynamic and quasi-static magneto-thermo-elastic stresses in a conducting rectangular plate subjected to an arbitrary variation of magnetic field. Fundamental equations of plane electromagnetic, temperature and elastic fields are formulated. To the best of the authors' knowledge, this is the first attempt to apply the DQM to magneto-thermo-elasticity and the first attempt to analyze a finite two-dimensional magneto-thermo-elastic problem. The fundamental equations and the inhomogeneous time-dependent boundary conditions are discretized in spatial and temporal domain by differential quadrature (DQ) rules. The unknowns satisfying the governing equations,...
Autors: Yufeng, Xing , Bo, Liu
Appeared in: International Journal of Engineering Science
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» A Digitally Controlled Unity Power Factor Compensator for Pulse-Burst-Modulated Loads
Abstract:
Pulse-burst-modulated (PBM) loads cause line losses that are significant when compared with equivalent loads that are compensated to operate with sinusoidal line currents. This study details the conceptual design of a system meant to compensate the power factor of a load power conditioned by means of PBM. The compensator controller is a digital controller that monitors the line current and voltage and adjusts the compensation current accordingly. Simulations of the proposed method confirm the effectiveness of such a compensator maintaining a nearly sinusoidal line current, even in the presence of an inductive load.
Autors: Ferreira, K. J.;Emanuel, A. E.;
Appeared in: IEEE Transactions on Power Electronics
Publication date: Jul 2010, volume: 25, issue:7, pages: 1888 - 1893
Publisher: IEEE
 
» A Direct Approach for the Frequency-Adaptive Feedforward Cancellation of Harmonic Disturbances
Abstract:
This paper is concerned with the robust rejection of harmonic disturbances with unknown frequency and amplitude affecting uncertain linear system. The developed control scheme combines the properties of adaptive feedforward cancellation (AFC) techniques with the phase and frequency detection capabilities provided by a nonlinear frequency estimation algorithm. Under mild assumptions on the nominal model of the system to be controlled, the proposed scheme is proven to achieve the complete rejection of harmonic disturbances at the input or at the output of the system. A detailed stability analysis based on averaging provides useful informations on the effect of the tuning parameters over the convergence of the estimator. The effectiveness of the proposed approach is demonstrated by a two-time scale averaging analysis.
Autors: Pin, G.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Jul 2010, volume: 58, issue:7, pages: 3523 - 3530
Publisher: IEEE
 
» A direct method for porous particle density characterization applied to activated carbons
Abstract:
A new method for setting the porous particle overall density is proposed. The apparent density of the particle including the solid matter as well as the different internal porosities (from microporous to macroporous pore size ranges) is currently needed for industrial applications as gas storage, heterogeneous catalysis... The technique proposed is based on the principle own immersion fluid applied to a granular medium consisting of extremely fine particles playing the role of non-wetting liquid. Here are presented the restrictive theoretical and experimental conditions, which have to be fulfilled by any granular medium before applying this principle. The conventional technique of...
Autors: G., Plantard , V., Goetz , X., Py
Appeared in: Advanced Powder Technology
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» A Discrete-Time Neural Network for Optimization Problems With Hybrid Constraints
Abstract:
Recurrent neural networks have become a prominent tool for optimizations including linear or nonlinear variational inequalities and programming, due to its regular mathematical properties and well-defined parallel structure. This brief presents a general discrete-time recurrent network for linear variational inequalities and related optimization problems with hybrid constraints. In contrary to the existing discrete-time networks, this general model can operate not only on bound constraints, but also on hybrid constraints comprised of inequality, equality and bound constraints. The model has dynamical properties of global convergence, asymptotical and exponential convergences under some weaker conditions. Numerical examples demonstrate its efficacy and performance.
Autors: Huajin Tang;Haizhou Li;Zhang Yi;
Appeared in: IEEE Transactions on Neural Networks
Publication date: Jul 2010, volume: 21, issue:7, pages: 1184 - 1189
Publisher: IEEE
 
» A disposable piezoelectric micropump with high performance for closed-loop insulin therapy system
Abstract:
This paper presents a novel and disposable piezoelectric micropump with high performance for a new closed-loop insulin therapy system. The micropump was designed by using four chambers in a serial connection structure, and was manufactured by using the materials with good bio-compatibility. The major advantages of the proposed micropump include: possessing high performance under lower working voltage, low cost, high resolution of flow rate. A maximum backpressure of 22 kPa was recorded at an applied voltage of 36Vpp and a driving frequency of 200Hz, the maximum resolution of outflow can obtain 6.23◊10-5ml per pulse. Through in vivo animal tests, the...
Autors: Guojun, Liu , Chuanliang, Shen , Zhigang, Yang , Xinxia, Cai , Honghai, Zhang
Appeared in: Sensors and Actuators A: Physical
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» A Distortion-Compensated Charge Transfer Amplifier for a 1.66-MHz Cyclic Pipeline ADC
Abstract:
A distortion-compensated charge transfer amplifier (DCCTA) is proposed to improve the linearity constraints of the differential charge transfer amplifier (DCTA). The proposed DCCTA effectively reduces distortion at its output by source degeneration, cross coupling, and making the drain-to-source voltage of the amplifying transistor independent of the applied input signal. This DCCTA yields an effective number of bits of 9.26 bits, compared with 6.05 bits for the DCTA at 40 MHz while consuming only 13.5 from a 1.2-V source. A 1.66-MHz cyclic pipeline analog-to-digital converter employing this DCCTA as a residue amplifier was simulated using 90-nm CMOS process, resulting in a peak resolution of 9.21 bits, without being limited by the thermal noise.
Autors: Sandhu, T. S.;El-Sankary, K.;El-Masry, E.;
Appeared in: IEEE Transactions on Circuits and Systems II: Express Briefs
Publication date: Jul 2010, volume: 57, issue:7, pages: 507 - 511
Publisher: IEEE
 
» A Distributed Contention Vector Division Multiple Access (D-CVDMA) Protocol for Wireless Networks
Abstract:
Traditional Time Division Multiple Access (TDMA) protocol provides deterministic periodic collision-free data transmissions. However, TDMA lacks flexibility and exhibits low efficiency in dynamic environments such as wireless LANs. On the other hand, contention-based MAC protocols such as the IEEE 802.11 DCF are adaptive to network dynamics but are generally inefficient in heavily loaded or large networks. To take advantage of the both types of protocols, a D-CVDMA protocol is proposed. It is based on the k-round elimination contention (k-EC) scheme, which provides fast contention resolution for Wireless LANs. D--CVDMA uses a contention mechanism to achieve TDMA-like collision-free data transmissions, which does not need to reserve time slots for forthcoming transmissions. These features make the D-CVDMA robust and adaptive to network dynamics such as node leaving and joining, changes in packet size and arrival rate, which, in turn, make it suitable for the delivery of hybrid traffic including multimedia and data content. D-CVDMA is designed for single-hop wireless ad hoc networks. Analyses and simulations demonstrate that D-CVDMA outperforms the IEEE 802.11 DCF and k-EC in terms of network throughput, delay, jitter, and fairness.
Autors: Bosheng Zhou;Marshall, A.;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jul 2010, volume: 9, issue:7, pages: 1049 - 1054
Publisher: IEEE
 
» A Dynamic Region-of-Interest Vision Tracking System Applied to the Real-Time Wing Kinematic Analysis of Tethered Drosophila
Abstract:
Tracking objects that move fast with respect to their size is challenging because it necessitates large field of views often incompatible with the required spatial and temporal resolutions. Here, we present a novel computer vision system that overcomes this tradeoff by employing a camera with dynamic region-of-interest (ROI) capabilities, combined with an efficient predictive approach. We apply this method to extract the wing kinematics of tethered flying fruit flies in real time. At each frame, only the pixels immediately surrounding the wing are exposed, and the wing position is extracted. It is then fed to an extended Kalman filter that extracts four key parameters of the measurement time-course and, therefore, provides real-time feedback of wing motion. Using this approach, we are able to sample the wing position of both wings at 7 kHz in a 2500 pixel ROI. Our methods promise new applications that can be implemented in general purpose digital hardware for high performance tracking and process control in a broad range of applications in technology and science.
Autors: Graetzel, C.F.;Nelson, B.J.;Fry, S.N.;
Appeared in: IEEE Transactions on Automation Science and Engineering
Publication date: Jul 2010, volume: 7, issue:3, pages: 463 - 473
Publisher: IEEE
 
» A Dynamic Search Range Algorithm for Stabilized Reduction of Memory Traffic in Video Encoder
Abstract:
Embedded compression is commonly employed in a video codec to reduce the data traffic to/from off-chip frame memory. We proposed a method for maintaining the memory bandwidth requirement at a significantly reduced level through dynamic search range adjustment for the motion estimation based on the observed relationship between the compression ratio and the motion vector. This, together with the so-called “center moving” to adjust the newly incoming macroblocks, helped significantly lower the requirement of the memory bandwidth without a fluctuation. Experimental results have shown that the memory bandwidth requirement can be finally stabilized to 20% of that of the full search. The image quality degradation was merely 0.02 dB.
Autors: Jung, J.;Kim, J.;Kyung, C.-M.;
Appeared in: IEEE Transactions on Circuits and Systems for Video Technology
Publication date: Jul 2010, volume: 20, issue:7, pages: 1041 - 1046
Publisher: IEEE
 
» A Dynamic Subspace Method for Hyperspectral Image Classification
Abstract:
Many studies have demonstrated that multiple classifier systems, such as the random subspace method (RSM), obtain more outstanding and robust results than a single classifier on extensive pattern recognition issues. In this paper, we propose a novel subspace selection mechanism, named the dynamic subspace method (DSM), to improve RSM on automatically determining dimensionality and selecting component dimensions for diverse subspaces. Two importance distributions are proposed to impose on the process of constructing ensemble classifiers. One is the distribution of subspace dimensionality, and the other is the distribution of band weights. Based on the two distributions, DSM becomes an automatic, dynamic, and adaptive ensemble. The real data experimental results show that the proposed DSM obtains sound performances than RSM, and that the classification maps remarkably produce fewer speckles.
Autors: Yang, J.-M.;Kuo, B.-C.;Yu, P.-T.;Chuang, C.-H.;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Jul 2010, volume: 48, issue:7, pages: 2840 - 2853
Publisher: IEEE
 
» A Dynamical Games Approach to Transmission-Rate Adaptation in Multimedia WLAN
Abstract:
This paper considers the scheduling, rate adaptation, and buffer management in a multiuser wireless local-area network (WLAN) where each user transmits scalable video payload. Based on opportunistic scheduling, users access the available medium (channel) in a decentralized manner. The rate adaptation problem of the WLAN multimedia networks is then formulated as a general-sum switching control dynamic Markovian game by modelling the video states and block fading channel qualities of each user as a finite states Markovian chain. A value iteration algorithm is proposed to compute the Nash equilibrium policy of such a game and the convergence of the algorithm is also proved. We also give assumptions on the system so that the Nash equilibrium transmission policy of each user is a randomization of two pure policies with each policy nondecreasing on the buffer state occupancy. Based on this structural result, we use the policy gradient algorithm to compute the Nash equilibrium policy.
Autors: Huang, J. W.;Mansour, H.;Krishnamurthy, V.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Jul 2010, volume: 58, issue:7, pages: 3635 - 3646
Publisher: IEEE
 
» A fast algorithm for the linear canonical transform
Abstract:
In recent years there has been a renewed interest in finding fast algorithms to compute accurately the linear canonical transform (LCT) of a given function. This is driven by the large number of applications of the LCT in optics and signal processing. The well-known integral transforms: Fourier, fractional Fourier, bilateral Laplace and Fresnel transforms are special cases of the LCT. In this paper we obtain an O(N log N) algorithm to compute the LCT by using a chirp-FFT-chirp transformation yielded by a convergent quadrature formula for the fractional Fourier transform. This formula gives a unitary discrete LCT in closed form....
Autors: Rafael G., Campos , Jared, Figueroa
Appeared in: Signal Processing
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» A Fast and High-Precision VCO Frequency Calibration Technique for Wideband Fractional-N Frequency Synthesizers
Abstract:
A VCO frequency calibration technique suitable for a wideband fractional-N PLL is presented. It provides a fast and high-precision search for an optimal discrete tuning curve of an VCO during the coarse tuning process in a fractional-N PLL. A high-speed frequency error detector (FED) converts the VCO frequency to a digital value and computes the exact frequency difference from a target frequency. A minimum error code finder finds an optimal code that is closest to the target frequency. Due to the pure digital domain operation, a modulator in PLL can be deactivated during the calibration process, which makes this technique fast and accurate especially for a fractional-N PLL. We achieve a single-bit calibration time of only for obtaining a frequency resolution of , and compared to the conventional techniques, which is the best performance in terms of the calibration time versus resolution. Such fast VCO frequency calibration can greatly reduce the total lock time in a PLL. A 2.3–3.9 GHz fractional-N PLL employing the proposed calibration technique is implemented in 0.13 CMOS. Successful operation is verified through experimental results. The measured calibration time for a 6-bit capbank is 1.09 and 2.03 for a frequency resolution of 19.2 and 4.8 MHz, respectively.
Autors: Shin, J.;Shin, H.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jul 2010, volume: 57, issue:7, pages: 1573 - 1582
Publisher: IEEE
 
» A Fault Diagnosis Method of Power Systems Based on Improved Objective Function and Genetic Algorithm-Tabu Search
Abstract:
Based on the improved optimization objective function of fault diagnosis, a genetic algorithm-Tabu search (GATS) method is introduced for the purpose of fault diagnosis of power systems. The genetic algorithm has good global search ability, while the Tabu search algorithm has good local search ability. Integrating the advantages of these two algorithms, a new hybrid algorithm, called GATS, can be obtained. Using the function of Shcaffer, the advantages of GATS are proven in this paper. The results of case studies show that GATS is superior to conventional methods in terms of the sensitivity of original solution and the dependency of original parameters. The satisfactory results can be obtained when the GATS method is applied in the event of abnormal operations of protective relays and circuit breakers or the multiple-fault scenarios.
Autors: Lin, X.;Ke, S.;Li, Z.;Weng, H.;Han, X.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Jul 2010, volume: 25, issue:3, pages: 1268 - 1274
Publisher: IEEE
 
» A feasibility study of pressure-retarded osmosis power generation system based on measuring permeation volume using reverse osmosis membrane
Abstract:
A pressure-retarded osmosis (PRO) power generation system is a hydroelectric power system which utilizes permeation flow through a semipermeable membrane. Permeation flow is generated by the potential energy of the salinity difference between sea water and fresh water. Since the cost of the membrane is high, the permeation performance of the membrane must be improved in order to realize PRO systems. We have investigated reverse osmosis (RO) membrane products as semipermeable membranes and measured the permeation volume of a few products. The generation power per unit membrane area calculated from the permeation volume is about 0.62 W/m2. But as a result of our improvements (greater salt water volume, spacers for fresh water channel with the function of discharging concentrated salinity, extralow-pressure type of membrane, washing the support layer of membrane when the generation power falls by half) the generated power may be 2.43 W/m2. Then the power system cost would be about 4.1 million yen/kW. In addition, if the support layer of the membrane is made thinner and a PRO system is applied to equipment where pumping power for another purpose is available (wastewater treatment plants located at the seaside, thermal and nuclear power plants, sea water desalination plants), the generated power may be increased. These improvements may enable PRO systems to be realized at a cost close to that of photovoltaic power systems. 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(2): 8-20, 2010; Published online in Wiley InterScience (). DOI 10.1002/eej.21000
Autors: Hiroshi Enomoto, Masashi Fujitsuka, Tomoyasu Hasegawa, Masatoshi Kuwada, Akihiko Tanioka, Mie Minagawa
Appeared in: Electrical Engineering in Japan
Publication date: Jul 2010
Publisher: Wiley InterScience
 
» A filter for a state space model with fractional Gaussian noise?
Abstract:
A filter for estimating the hidden signal and parameters in a state space model, where the noise in the observations is fractional Gaussian noise, is obtained.
Autors: Robert J., Elliott , Jia, Deng
Appeared in: Automatica
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» A Framework for RFID Deployment in Supply Chains
Abstract:
The proposed framework shows how the granularity of tagging and deployment scope affect RFID implementation, helping managers identify RFID benefits and barriers and align deployment with their company's business strategy and return-on-investment goals.
Autors: Bradley, James;Guerrero, Hector;
Appeared in: IT Professional
Publication date: Jul 2010, volume: 12, issue:4, pages: 44 - 50
Publisher: IEEE
 
» A Frequency-Multiplied Source With More Than 1 mW of Power Across the 840–900-GHz Band
Abstract:
We report on the design, fabrication, and characterization of an 840–900-GHz frequency multiplier chain that delivers more than 1 mW across the band at room temperature with a record peak power of 1.4 mW at 875 GHz. When cooled to 120 K, the chain delivers up to 2 mW at 882 GHz. The chain consists of a power amplifier module that drives two cascaded frequency triplers. This unprecedented output power from an electronic source is achieved by utilizing in-phase power-combining techniques. The first stage tripler uses four power-combined chips while the last stage tripler utilizes two power-combined chips. The source output was analyzed with a Fourrer transform spectrometer to verify signal purity.
Autors: Maestrini, A.;Ward, J. S.;Gill, J. J.;Lee, C.;Thomas, B.;Lin, R. H.;Chattopadhyay, G.;Mehdi, I.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2010, volume: 58, issue:7, pages: 1925 - 1932
Publisher: IEEE
 
» A fused system of sensing and communication with hetero-core spliced fiber optic sensors
Abstract:
We have developed an optical fiber network combining communication and sensing using a hetero-core spliced fiber optic sensor inserted into an existing communication line. The measurement uses the Internet infrastructure effectively, and the sensitivity characteristic by wavelength of the measurement was examined. In addition, six binary switch modules and one displacement sensor module using the hetero-core spliced fiber optic sensor were inserted into an actual communication line, and the influence on the communication was examined. The hetero-core spliced fiber optic sensor showed the characteristic of loss only. When the sensor is inserted into the communication line, if the loss can be controlled to within tolerance to the wavelength of 1.31 [mu]m of the communication line, a measurement function can be added to the communication line by a comparatively simple construction method. In addition, we realized a multiple binary switch measurement in real-time basis with tandem connection by simple addressing algorithm. The binary switches can be applied to a home security system to monitor the state of doors opening and closing. We have successfully fabricated and demonstrated the binary switch sensing system in tandem connection consisting of three binary switches using the proposed method. 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(3): 40-48, 2010; Published online in Wiley InterScience (). DOI 10.1002/ eej.21021
Autors: Norihiko Shinomiya, Hiroyuki Sasaki, Michiko Nishiyama, Emiko Kondo, Yuko Ito, Kazuhiro Watanabe
Appeared in: Electrical Engineering in Japan
Publication date: Jul 2010
Publisher: Wiley InterScience
 
» A fuzzy approach for multiple-receiver digital communication systems with data fusion
Abstract:
Many multiple-receiver diversity schemes employ hard decisions combining rules to achieve a diversity gain in digital communications. In this paper, a fuzzy combining approach in diversity systems is proposed. The confidence levels associated with the local receiver soft-decisions are modeled by means of fuzzy membership functions. The reliabilities of the local receivers are weighted by the soft-decision confidence levels and fused in a central digital receiver to decide which symbol was transmitted. The performance of the proposed approach is evaluated and compared to the performance of optimal diversity, majority voting, optimal partial decision, and selection diversity in case of binary...
Autors: Ashraf M., Aziz
Appeared in: AEU - International Journal of Electronics and Communications
Publication date: Jul 2010
Publisher: Elsevier B.V.
 
» A Fuzzy Rule-Based Approach for Islanding Detection in Distributed Generation
Abstract:
The proposed method develops a fuzzy rule-based classifier that was tested using features for islanding detection in distributed generation. In the developed technique, the initial classification boundaries are found out by using the decision tree (DT). From the DT classification boundaries, the fuzzy membership functions (MFs) are developed and the corresponding rule base is formulated for islanding detection. But some of the fuzzy MFs are merged based upon similarity the measure for reducing the fuzzy MFs and simplifying the fuzzy rule base to make it more transparent. The developed fuzzy rule-based classifier is tested using features with noise up to a signal-to-noise ratio of 20 dB and provides classification results without misdetection, which shows the robustness of the proposed approach for islanding detection for distributed generations in the distribution network.
Autors: Samantaray, S. R.;El-Arroudi, K.;Joos, G.;Kamwa, I.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Jul 2010, volume: 25, issue:3, pages: 1427 - 1433
Publisher: IEEE
 
» A Galois field-based logic synthesis with testability
Abstract:
In deep-submicron very-large-scale integration (VLSI) systems, efficient circuit testability is one of the most demanding requirements. An automatic synthesis technique for designing efficiently testable logic circuits is one of the ways to tackle the problem. To this end, this study introduces the generalised theory and a new fast efficient graph-based decomposition technique for the functions over finite fields defined over the set GF(N), where N is a power of a prime number, which utilises the data structure of the multiple-output decision diagrams. In particular, the proposed technique can decompose any N valued arbitrary function over the fields conjunctively and disjunctively. The proposed technique is capable of generating testable circuits. The experimental results show that the proposed method is more economical in terms of literal count compared to the existing approaches. Furthermore, the authors have shown that the basic block can be tested with only eight test vectors.
Autors: Mathew, J.;Jabir, A.M.;Singh, A.K.;Rahaman, H.;Pradhan, D.K.;
Appeared in: IET Computers & Digital Techniques
Publication date: Jul 2010, volume: 4, issue:4, pages: 263 - 273
Publisher: IEEE
 
» A General Model for Estimating the Laminated Steel Losses Under PWM Voltage Supply
Abstract:
The new model is based on a modified Steinmetz equation and employs a hysteresis-loss multiplicative coefficient and a combined coefficient for eddy-current and excess losses, both coefficients being variable with induction and frequency. The material model coefficients are first identified through multifrequency tests with sine-wave excitation. The iron-loss increase due to pulsewidth-modulation supply is estimated using global waveform parameters of the nonsinusoidal voltage. The study includes three different grades of non-grain-oriented electric steel. The data cover a wide range of fundamental frequency from 10 to 600 Hz and induction from 0.05 to 2 T. The errors of the computational model are small at relatively low fundamental frequency and increase thereafter. The main advantages of the model are its simplicity of use and minimal data requirements.
Autors: Popescu, M.;Ionel, D. M.;Boglietti, A.;Cavagnino, A.;Cossar, C.;McGilp, M. I.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jul 2010, volume: 46, issue:4, pages: 1389 - 1396
Publisher: IEEE
 
» A General Upper Bound on the Size of Constant-Weight Conflict-Avoiding Codes
Abstract:
Conflict-avoiding codes are used in the multiple-access collision channel without feedback. The number of codewords in a conflict-avoiding code is the number of potential users that can be supported in the system. In this paper, a new upper bound on the size of constant-weight conflict-avoiding codes is proved. This upper bound is general in the sense that it is applicable to all code lengths and all Hamming weights. Several existing constructions for conflict-avoiding codes, which are known to be optimal for Hamming weights equal to four and five, are shown to be optimal for all Hamming weights in general.
Autors: Shum, K. W.;Wong, W. S.;Chen, C. S.;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jul 2010, volume: 56, issue:7, pages: 3265 - 3276
Publisher: IEEE
 
» A Generalized Delayed Signal Cancellation Method for Detecting Fundamental-Frequency Positive-Sequence Three-Phase Signals
Abstract:
A novel scheme for obtaining the fundamental-frequency positive-sequence grid voltage vector based on a generalization of the delayed signal cancellation method is proposed in this paper. The technique is implemented by sampling and storing the instantaneous voltage vector. A mathematical transformation is then proposed through which the current and delayed voltage vectors are combined. It is shown that the proposed transformation has unity gain for the fundamental-frequency positive-sequence voltage vector, while its gain is equal to zero for some chosen components. Cascaded transformations can then be used for eliminating the fundamental-frequency negative-sequence vector, as well as chosen positive- and negative-sequence harmonic vector components and, thus, for accurately obtaining the fundamental-frequency positive-sequence voltage vector. The output of the last transformation block is input to a synchronous reference frame phase-locked loop for detecting frequency and position of the positive-sequence vector. A proposal for making the scheme frequency adaptive is also presented. The good performance of the proposed method is verified with simulations and experiments by using distorted and unbalanced signals, containing fundamental-frequency as well as positive- and negative-sequence harmonic components. The proposed method frequency adaptation capability is also verified.
Autors: Neves, F. A. S.;Cavalcanti, M. C.;de Souza, H. E. P.;Bradaschia, F.;Bueno, E. J.;Rizo, M.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Jul 2010, volume: 25, issue:3, pages: 1816 - 1825
Publisher: IEEE
 
» A Generalized Drift-Diffusion Model for Rectifying Schottky Contact Simulation
Abstract:
We present a discussion on the modeling of Schottky barrier rectifying contacts (diodes) within the framework of partial-differential-equation-based physical simulations. We propose a physically consistent generalization of the drift-diffusion model to describe the boundary layer close to the Schottky barrier where thermionic emission leads to a non-Maxwellian carrier distribution, including a novel boundary condition at the contact. The modified drift-diffusion model is validated against Monte Carlo simulations of a GaAs device. The proposed model is in agreement with the Monte Carlo simulations not only in the current value but also in the spatial distributions of microscopic quantities like the electron velocity and concentration.
Autors: Traversa, F. L.;Bertazzi, F.;Bonani, F.;Donati Guerrieri, S.;Ghione, G.;Perez, S.;Mateos, J.;Gonzalez, T.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jul 2010, volume: 57, issue:7, pages: 1539 - 1547
Publisher: IEEE
 
» A Generalized Synthesis Procedure for Low-Profile, Frequency Selective Surfaces With Odd-Order Bandpass Responses
Abstract:
We present a generalized synthesis procedure for designing low-profile frequency selective surfaces (FSS) with bandpass responses of odd-order (N = 3,5,7,...). The FSSs designed using this technique use a combination of resonant and non-resonant sub-wavelength constituting unit cells with unit cell dimensions and periodicities in the order of 0.15 λ0, where λ0 is the free space wavelength. The main advantage of using this technique, compared to traditional FSS design techniques, is that it allows for the design of low-profile and ultrathin FSSs that can provide sharp frequency selectivity. An Nth order FSS designed using this technique typically has an electrical thickness in the order of ~ (N - 1) λ0/50 which is significantly smaller than the overall thickness of a traditionally designed Nth order FSS (~ (N - 1) λ0/4). The proposed synthesis procedure is validated for two FSS prototypes having third- and fifth-order bandpass responses. Principles of operation, detailed synthesis procedure, and implementation guidelines for this type of FSS are presented and discussed in this communication.
Autors: Behdad, N.;Al-Joumayly, M.A.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jul 2010, volume: 58, issue:7, pages: 2460 - 2464
Publisher: IEEE
 
» A Generalized System for Photoresponsive Membrane Rupture in Polymersomes
Abstract:
Polymersomes are vesicles whose membranes comprise self-assembled block copolymers. It has recently been shown that co-encapsulating conjugated multiporphyrin dyes in a polymersome membrane with ferritin protein in the aqueous lumen confers photolability to the polymersome. In the present study, the photolability is shown to be extendable to vesicles containing dextran, an inert and inexpensive polysaccharide, as the luminal solute. How structural features of the polymersome/porphyrin/dextran composite affect its photoresponse is explored. Increasing dextran molecular weight, decreasing block copolymer molecular weight, and altering fluorophore-membrane interactions results in increasing the photoresponsiveness of the polymersomes. Amphiphilic interactions of the luminal encapsulant with the membrane coupled with localized heat production in the hydrophobic bilayer likely cause differential thermal expansion in the membrane and the subsequent membrane rupture. This study suggests a general approach to impart photoresponsiveness to any biomimetic vesicle system without chemical modification, as well as a simple, bio-inert method for constructing photosensitive carriers for controlled release of encapsulants.
Autors: Neha P. Kamat, Gregory P. Robbins, Jeff Rawson, Michael J. Therien, Ivan J. Dmochowski, Daniel A. Hammer
Appeared in: Advanced Functional Materials
Publication date: Jul 2010
Publisher: Wiley InterScience
 
» A Global Approach for Modeling and Analysis of Edge-Coupled Traveling-Wave Terahertz Photoconductive Sources
Abstract:
In this paper, a global and geometry-independent approach is proposed for accurate analysis of edge-coupled continuous wave (CW) traveling-wave terahertz photomixer sources. All major physical phenomena involved in the operation of such devices are included in three interconnected solvers, which are combined as a unified analysis tool. A photonic solver is developed to find the optical intensity across the fast photoabsorbing region from which the carrier generation rate is determined. A semiconductor solver is used to study the charge carrier transport inside the photoconductive region through drift-diffusion model, and to predict the generated photocurrent with the beat frequency of two CW lasers. An electromagnetic solver is introduced to rigorously calculate the coupled terahertz signal into the guiding transmission line through a Lorentz reciprocity theorem. Theoretical formulation behind each solver is discussed in detail, and numerical results from each solver are presented. The proposed approach is a powerful tool for global optimization of the photoconductive sources, especially for maximizing the optical-to-terahertz power conversion.
Autors: Neshat, M.;Saeedkia, D.;Rezaee, L.;Safavi-Naeini, S.;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: Jul 2010, volume: 58, issue:7, pages: 1952 - 1966
Publisher: IEEE
 

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