Digchip : Database on electronics components
Electronics components database



 
Filter:  
  Select journal:
 
  Search word:
 
  Search author:
 

 
Pages: 01234567891011121314151617181920212223


Electrical and Electronics Engineering publications abstract of: 01-2011 sorted by title, page: 3
» Air-spaced GaN nanopillar photonic band gap structures patterned by nanosphere lithography
Abstract:
We report on the fabrication of ordered hexagonal arrays of air-spaced GaN nanopillars by nanosphere lithography. A self-assembled two-dimensional silica nanosphere mask was initially formed by spin-coating. Prior to pattern transfer to the GaN substrate, a silica-selective dry etch recipe was employed to reduce the dimensions of the nanospheres, without shifting their equilibrium positions. This process step was crucial to be formation of air-spaced hexagonal arrays of nanospheres, as opposed to closed-packed arrays normally achieved by nanosphere lithography. This pattern is then transferred to the wafer to form air-spaced nanopillars. By introducing air gaps between pillars, a photonic band gap (PBG) in the visible region can be opened up, which is usually nonexistent in closed-packed nanopillar arrays. The PBG structures were designed using the plane wave expansion algorithm for band structure computations. The existence and positions of band gaps have been verified through optical transmittance spectroscopy, which correlated well with predictions from simulations. From photoluminescence (PL) spectroscopy, a fourfold increase in PL intensity was observed and compared to an as-grown sample, demonstrating the effectiveness of well-designed self-assembled PBG structures for suppressing undesired optical guiding mode via PBG and for promoting light extraction. The effects of defects in the nanopillar array on the optical properties are also critically assessed.
Autors: Li, K. H.;Choi, H. W.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 023107 - 023107-6
Publisher: IEEE
Full litterature document
 
» Airline group proposes security tunnels
Abstract:
Airline trade group International Air Transport Association, has proposed a new type of security checkpoint comprising a set of three tunnels (or enclosed pathways) that are equipped with sensors, X-ray machines, cameras or other security equipment to speed clearance for travellers deemed low-risk.
Autors: [No author name available]
Appeared in: Biometric Technology Today
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» Airport Detection From Large IKONOS Images Using Clustered SIFT Keypoints and Region Information
Abstract:
This letter presents a new method for airport detection from large high-spatial-resolution IKONOS images. To this end, we describe airport by a set of scale-invariant feature transform (SIFT) keypoints and detect it using an improved SIFT matching strategy. After obtaining SIFT matched keypoints, to both discard the redundant matched points and locate the possible regions of candidates that contain the target, a novel region-location algorithm is proposed, which exploits the clustering information from matched SIFT keypoints, as well as the region information extracted through the image segmentation. Finally, airport recognition is achieved by applying the prior knowledge to the candidate regions. Experimental results show that the proposed approach outperforms the existing algorithms in terms of detection accuracy.
Autors: Tao, C.;Tan, Y.;Cai, H.;Tian, J.;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jan 2011, volume: 8, issue:1, pages: 128 - 132
Publisher: IEEE
Full litterature document
 
» ALD grown NbTaOx based MIM capacitors
Abstract:
NbTaOx mixed oxides were deposited by ALD in ASM Pulsar® 2000 R&D reactor using TaF5 and NbF5 as metal precursors. Two deposition processes were evaluated, one with only H2O as the oxidizer, and the other with a combination of H2O and O3. The depositions where done at 225 °C on Si (200mm, p-type (100) with native oxide), Ru(AVD), TiN(ALD) and TaN(PVD) bottom electrodes. After the dielectric depositions, N2 PDA's were applied on the samples and finally Au dot (e-beam evaporation with shadow mask) top electrodes were deposited for electrical characterization. Best electrical results (bottom electrode injection) achieved for the different...
Autors: T., Blomberg , Ch., Wenger , C. Baristiran, Kaynak , G., Ruhl , P., Baumann
Appeared in: Microelectronic Engineering
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» Alignment of non-texture video frames using kalman filter
Abstract:
Video registration in the presence of several segments of non-texture frames remains a challenging issue, although a wide repertoire of image registration algorithms was developed over the last two decades. In this study, the authors proposed an effective causal scheme of video frames registration, and implemented it by the modified two frames intensity match algorithm. In order to achieve its real-time performance, the authors avoid handling a much more complex appearance model in this causal system by using registration parameters as measurement values, which are estimated directly from two consecutive frames via intensity matching. The simple linear and Gaussian system is thus derived and an efficient Kalman filter algorithm can be utilised. As the Kalman filter naturally incorporated the temporal information contained in a video into the estimation of registration parameters, the algorithm developed in this study is quite robust and has good performance even if the processed video contains several segments of non-texture frames.
Autors: Jianchao, Y.;
Appeared in: IET Computer Vision
Publication date: Jan 2011, volume: 5, issue:1, pages: 77 - 85
Publisher: IEEE
Full litterature document
 
» All-fiber polarimetric electric field sensing using liquid crystal infiltrated photonic crystal fibers
Abstract:
The operation of an all-fiber polarimetric electric field sensor based on nematic liquid crystal infiltrated photonic crystal fiber is demonstrated. A section less than 1mm long of a selectively infiltrated polarization maintaining photonic crystal fiber is used as the probe. The transmission properties are studied for different lengths of the infiltrated section of the fiber subjected to an electric field. It is shown that the phase birefringence of the fiber can be controlled by adjusting the length of the infiltrated section subjected to an electric field, which allows for the sensor to have a linear transmittance response with the applied...
Autors: Sunish, Mathews , Gerald, Farrell , Yuliya, Semenova
Appeared in: Sensors and Actuators A: Physical
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» All-Optical -Bits Shift Register Exploiting a Ring Buffer Based on Semiconductor Optical Amplifier
Abstract:
The design and experimental characterization of an all-optical circular shift register are presented. The proposed scheme consists of a fiber loop optical buffer and a bit selecting circuit. A semiconductor optical amplifier (SOA) is used as an active element in the buffer structure, while the bit selecting circuit exploits Kerr effect in a highly nonlinear medium. The scheme is designed to store an -bit sequence and to return the bits one by one at a lower clock rate, achieving proper circulating shift register functionality. Photonic integration is possible thanks to the presence of SOA in the buffer loop and to the absence of erbium-doped fiber amplifier-based feedbacks. Moreover, the increase in the number of bits to be stored does not increase the scheme complexity. Experimental validation is demonstrated for , and a signal-to-noise ratio per bit penalty equal to 5.6 dB is achieved at a bit error rate equal to with respect to the input sequence.
Autors: Lazzeri, E.;Berrettini, G.;Meloni, G.;Bogoni, A.;Poti, L.;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jan 2011, volume: 23, issue:1, pages: 45 - 47
Publisher: IEEE
Full litterature document
 
» All-optical integrated micro logic gate
Abstract:
In this paper we present a novel approach for realizing an integrated all-optical logic gate. The basic principle is based upon stimulated emission process generated in an active gain medium while special interferometric photonic wave-guiding structure allows the realization of an integrated micro scale device. The operation rate of the proposed device structure can theoretically reach tens of Tera-Hertz.
Autors: Arkady, Rudnitsky , Asaf, Shahmoon , Menachem, Nathan , Moshe, Nazarathy , Bar, Larom , ...
Appeared in: Microelectronics Journal
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» All-Optical Logic Minterms for Three-Input Demodulated Differential Phase-Shift Keying Signals at 40 Gb/s
Abstract:
The 40-Gb/s all-optical logic minterms generation of three input demodulated return-to-zero differential phase-shift-keying signals is demonstrated based on two delayed interferometers and a semiconductor optical amplifier cascaded with two bandpass filters. Experimental demonstration verifies the logic integrity of this scheme. The final results are derived in the on–off keying format with clear open eyes and extinction ratios over 10 dB. The proposed scheme could be extended to realize arbitrary complex logic gates.
Autors: Chen, X.;Yu, Y.;Zhang, X.;
Appeared in: IEEE Photonics Technology Letters
Publication date: Jan 2011, volume: 23, issue:2, pages: 118 - 120
Publisher: IEEE
Full litterature document
 
» Almost-Periodic Higher Order Statistic Estimation
Abstract:
In this paper, stochastic processes with higher order statistical functions decomposable into an almost-periodic function plus a residual term not containing finite-strength additive sinewave components are considered. These processes arise in mobile communications when almost-cyclostationary (ACS) processes pass through time-varying channels. They include as special case the generalized almost-cyclostationary processes which, in turn, include the ACS processes. In the paper, the problem of estimating the Fourier coefficients of the (generalized) Fourier series expansion of the almost-periodic component of higher order statistical functions is addressed. Estimators are proposed for cyclic temporal cross moment and cumulants. They are proved to be mean square consistent and asymptotically complex Normal under mild assumptions on the memory of the processes expressed in terms of summability of cross cumulants. Numerical results confirm the theoretical results and the derived rate of convergence to zero of bias and standard deviation of the estimators.
Autors: Napolitano, A.;Tesauro, M.;
Appeared in: IEEE Transactions on Information Theory
Publication date: Jan 2011, volume: 57, issue:1, pages: 514 - 533
Publisher: IEEE
Full litterature document
 
» Alpha-particle-induced effects in partially depleted silicon on insulator device: With and without body contact
Abstract:
With the continuous downscaling of CMOS technologies, reliability has become one of the major bottlenecks in the evolution of next generation systems. The radiation-induced soft errors have become one of the most important and challenging failure mechanisms in the modern semi-conductor devices. The authors present an in-depth analysis of alpha-particle-induced effects in deep submicron partially depleted silicon on insulator (PD-SOI) device. Device with body contact as well as device without body contact is analysed. The process and device simulations are done with the latest models. Electrical parameter extraction under different energies of an alpha particle is carried out.
Autors: Rathod, S.S.;Saxena, A.K.;Dasgupta, S.;
Appeared in: IET Circuits, Devices & Systems
Publication date: Jan 2011, volume: 5, issue:1, pages: 52 - 58
Publisher: IEEE
Full litterature document
 
» Alternating current impedance spectroscopy measurement under high pressure
Abstract:
A microcircuit was designed and fabricated on a diamond anvil cell for alternating current impedance spectroscopy measurement under high pressure. Sputtered molybdenum film on a diamond anvil was used as an electrode, maintained the contact between the sample and the electrode stable, and reduced the electrode effect on the impedance measurement. By the empty cell and short circuit tests, the parasitic capacitive impedance from the sample chamber wall was observed to be larger than 105 Ω at a frequency lower than 1.0 MHz and could be ignored for samples with higher conductivity. The wire inductance was only 1.0 μH and just appeared at frequency higher than 20 kHz, which could be subtracted from measured impedance for the samples with higher impedance than several hundred ohms. Using this apparatus, the impedances of the II–VI group cadmium sulfide were measured. The pressure dependence of the grain interior conductance of CdS crystal was obtained, which reflected that the phase transitions of CdS under high pressure are the same as the single crystal measurement results.
Autors: He, Chunyuan;Liu, Bingguo;Li, Ming;Gao, Chunxiao;
Appeared in: Review of Scientific Instruments
Publication date: Jan 2011, volume: 82, issue:1, pages: 015104 - 015104-4
Publisher: IEEE
Full litterature document
 
» Ambipolar charge transport in microcrystalline silicon thin-film transistors
Abstract:
Hydrogenated microcrystalline silicon c-Si:H) is a promising candidate for thin-film transistors (TFTs) in large-area electronics due to high electron and hole charge carrier mobilities. We report on ambipolar TFTs based on μc-Si:H prepared by plasma-enhanced chemical vapor deposition at temperatures compatible with flexible substrates. Electrons and holes are directly injected into the μc-Si:H channel via chromium drain and source contacts. The TFTs exhibit electron and hole charge carrier mobilities of 30–50 cm2/Vs and 10–15 cm2/Vs, respectively. In this work, the electrical characteristics of the ambipolar μc-Si:H TFTs are described by a simple analytical model that takes the ambipolar charge transport into account. The analytical expressions are used to model the transfer curves, the potential and the net surface charge along the channel of the TFTs. The electrical model provides insights into the electronic transport of ambipolar μc-Si:H TFTs.
Autors: Knipp, Dietmar;Chan, Kah-Yoong;Gordijn, Aad;Marinkovic, M.;Stiebig, Helmut;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 024504 - 024504-8
Publisher: IEEE
Full litterature document
 
» Ambipolar Silicon Nanowire FETs with Stenciled-Deposited Metal Gate
Abstract:
We report on a fully CMOS compatible fabrication method for ambipolar silicon nanowire FinFETs. The low thermal budget processing, compatible with monolithic 3D device integration, makes use of low pressure chemical vapor deposition (LPCVD) of amorphous Si (a-Si) and SiO2 layers as well as metal gate patterning using stencil lithography, demonstrated for the first time. FinFETs with stenciled Al gates are successfully co-fabricated with polycristalline silicon ?-gated devices. Stencil lithography is envisaged as a key enabler for gate patterning on 3D structures, such as vertically-stacked nanowire transistors.
Autors: Davide, Sacchetto , Veronica, Savu , Giovanni, De Micheli , Jürgen, Brugger , Yusuf, Leblebici
Appeared in: Microelectronic Engineering
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» Ampacity Calculation for DLO Cable Used in Permanent Installations
Abstract:
DLO is a railroad industry designation given to flexible cables certified for use in diesel locomotives. For use outside the railroad industry, these cables may be labeled with a UL insulation-type certification such as RHW-2. Carried over from the cables' railroad lineage are sizes such as 535 kcmil that are absent from NEC tables. While interpolation of NEC tables may appear as a logical means of calculating ampacity, the NEC limits ampacity calculation options to the formula provided in 310.15(C). Applications of the 310.15(C) formula for cables in underground duct banks are well documented, but constants for duplicating conditions of NEC Table 310.16 are absent from the NEC. For application of nonstandard cable sizes in conditions matching those of NEC Table 310.16, this paper provides ampacity calculations while also clarifying the delineation between permanent building wiring and temporary cords as defined by the NEC.
Autors: Cardinal, P. G.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2011, volume: 47, issue:1, pages: 281 - 285
Publisher: IEEE
Full litterature document
 
» An Accurate Closed-Form Approximation of the Distributed MIMO Outage Probability
Abstract:
The mutual information (MI) of multiple-input multiple-output (MIMO) system over Rayleigh fading channel is known to asymptotically follow a normal probability distribution. In this paper, we first prove that the MI of distributed MIMO (DMIMO) system is also asymptotically equivalent to a Gaussian random variable (RV) by deriving its moment generating function (MGF) and by showing its equivalence with the MGF of a Gaussian RV. We then derive an accurate closed-form approximation of the outage probability for DMIMO system by using the mean and variance of the MI and show the uniqueness of its formulation. Finally, several applications for our analysis are presented.
Autors: Heliot, Fabien;Hoshyar, Reza;Tafazolli, Rahim;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2011, volume: 10, issue:1, pages: 5 - 11
Publisher: IEEE
Full litterature document
 
» An Adaptive Electric Differential for Electric Vehicles Motion Stabilization
Abstract:
This paper proposes a traction drive system for electric vehicles (EVs) with two separate induction motor drive-based wheels. In this case, an electric differential (ED) is developed. To handle EV stability while cornering or under slippery road condition, the proposed traction drive uses direct torque control and an adaptive-flux-and-speed-observer-based algorithm. EV-specific experimental tests on a digital signal processor TMS320LF2407 are carried out to show the effectiveness of the proposed adaptive ED in terms of robustness and stability.
Autors: Tabbache, B.;Kheloui, A.;Benbouzid, M. E. H.;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2011, volume: 60, issue:1, pages: 104 - 110
Publisher: IEEE
Full litterature document
 
» An Adaptive Energy Storage Technique for Efficiency Improvement of Single-Stage Three-Level Resonant AC/DC Converters
Abstract:
The use of single-stage power-factor-corrected (SSPFC) three-level resonant ac/dc converters solves many problems that present SSPFC converters face today, namely, high component stresses, high circulating currents, and low efficiency. This makes single-stage three-level resonant ac/dc converters a good candidate for high-power applications. These converters provide the flexibility of simultaneously using two control variables. They can operate with a combined variable-frequency and asymmetrical pulsewidth modulation or with a combined variable-frequency phase-shift modulation. This provides good regulation of the output voltage, dc-bus voltage, and input current. The drawback of these methods is that the efficiency of the converter drops as the load is reduced because the converter starts to drift away from its resonance frequency, thus leading to more circulating currents and conduction losses. Therefore, a load-adaptive energy storage technique is proposed in this paper to guarantee the converter operation near its maximum efficiency point for a wide range of loading. This leads to almost constant converter efficiency from full load to 40% load. The use of interleaved converters is also proposed to extend the constant efficiency range of operation to lighter loads (15%–20% of full load). Analytical simulation and experimental results are presented to verify the proposed methods.
Autors: Agamy, M. S.;Jain, P. K.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2011, volume: 47, issue:1, pages: 176 - 184
Publisher: IEEE
Full litterature document
 
» An Adaptive Filter to Approximate the Bayesian Strategy for Sonographic Beamforming
Abstract:
A first-principles task-based approach to the design of medical ultrasonic imaging systems for breast lesion discrimination is described. This study explores a new approximation to the ideal Bayesian observer strategy that allows for object heterogeneity. The new method, called iterative Wiener filtering, is implemented using echo data simulations and a phantom study. We studied five lesion features closely associated with visual discrimination for clinical diagnosis. A series of human observer measurements for the same image data allowed us to quantitatively compare alternative beamforming strategies through measurements of visual discrimination efficiency. Employing the Smith–Wagner model observer, we were able to breakdown efficiency estimates and identify the processing stage at which performance losses occur. The methods were implemented using a commercial scanner and a cyst phantom to explore development of spatial filters for systems with shift-variant impulse response functions. Overall we found that significant improvements were realized over standard B-mode images using a delay-and-sum beamformer but at the cost of higher complexity and computational load.
Autors: Nguyen, N. Q.;Abbey, C. K.;Insana, M. F.;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jan 2011, volume: 30, issue:1, pages: 28 - 37
Publisher: IEEE
Full litterature document
 
» An Adaptive-Filter-Based Torque-Ripple Minimization of a Fuzzy-Logic Controller for Speed Control of IPM Motor Drives
Abstract:
This paper presents an adaptive-filter-based torque-ripple minimization (TRM) of a fuzzy-logic controller (FLC) for speed control of an interior permanent magnet (IPM) motor drive. A simple and effective first-order digital infinite impulse response filter is utilized to reduce the torque ripples introduced by the FLC. The gain of the filter is adapted online based on the magnitude of the torque ripple. The optimal position of the filter in the complete drive is also determined for effective TRM. The various sources of torque pulsations in a practical electric-machine drive are described. The main causes of the torque ripple in an FLC are also explained. A simulation model for closed vector control of an FLC-based IPM motor drive incorporating the proposed TRM technique is developed in Matlab/Simulink. The complete drive is also experimentally implemented using digital signal processor board DS1102 for a laboratory 1-hp IPM motor. The effectiveness of the proposed technique is investigated, both in simulation and experiment, at different operating conditions. It is found that the performance of the FLC-based IPM drive is improved significantly with the proposed TRM technique.
Autors: Uddin, M. N.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2011, volume: 47, issue:1, pages: 350 - 358
Publisher: IEEE
Full litterature document
 
» An ambipolar to n-type transformation in pentacene-based organic field-effect transistors
Abstract:
image

Autors:

Graphical abstract

 Graphical abstract: ???. Highlights: ? An ambipolar to n-type transformation in pentacene OFETs of Al S-D electrodes. ? The hole currents of OFETs were decreased, but the electron currents unchanged. ? The interfacial inte
Appeared in: Organic Electronics
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» An apparatus for simultaneous measurement of electrical conductivity and thermopower of thin films in the temperature range of 300–750 K
Abstract:
An automated apparatus capable of measuring the electrical conductivity and thermopower of thin films over a temperature range of 300–750 K is reported. A standard dc resistance measurement in van der Pauw geometry was used to evaluate the electrical conductivity, and the thermopower was measured using the differential method. The design of the instrument, the methods used for calibration, and the measurement procedure are described in detail. Given the lack of a standard National Institute of Standards and Technology (Gaithersburg, Md.) sample for high temperature thermopower calibration, the disclosed calibration procedure shall be useful for calibration of new instruments.
Autors: Ravichandran, J.;Kardel, J. T.;Scullin, M. L.;Bahk, J.-H.;Heijmerikx, H.;Bowers, J. E.;Majumdar, A.;
Appeared in: Review of Scientific Instruments
Publication date: Jan 2011, volume: 82, issue:1, pages: 015108 - 015108-4
Publisher: IEEE
Full litterature document
 
» An Architecture for FACTS Controllers to Deal With Bandwidth-Constrained Communication
Abstract:
Bandwidth constraints could have an adverse impact on the flexible AC transmission system (FACTS) controllers relying on signals communicated from distant locations. An observer-driven system copy (OSC) architecture is adopted here to deal with low data rates caused by the limited bandwidth availability. The basic idea is to use the knowledge of the nominal system to approximate its actual behavior during the intervals when data from the remote phasor measurement units (PMUs) are not available. This is corrected whenever the most recent states are obtained from the reduced-order observer at the PMU location. The closed-loop behavior deteriorates as the operating condition drifts away from the nominal. Nonetheless, significantly better response is achieved under limited bandwidth availability compared to the conventional approach of communicating the measured outputs. The deterioration is quantified in terms of the difference between the nominal and the offnominal condition.
Autors: Chaudhuri, N. R.;Chakraborty, D.;Chaudhuri, B.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Jan 2011, volume: 26, issue:1, pages: 188 - 196
Publisher: IEEE
Full litterature document
 
» An atmospheric-pressure nitrogen-plasma jet produced from microdischarges in a porous dielectric
Abstract:
This report presents an atmospheric-pressure nitrogen-plasma jet generated from microdischarges in a porous dielectric. A plasma jet with a length of 42 mm was produced by feeding nitrogen gas through a porous alumina installed between an outer electrode and a hollow inner electrode and by applying 60 Hz sinusoidal voltage wave to the electrodes. Microdischarges in the porous alumina are ejected as a plasma jet from the outer electrode through a 1 mm hole by increasing the applied voltage, showing that the temperature of the jet decreases to a value close to room temperature. Even at a frequency as low as 60 Hz, the...
Autors: Yongcheol, Hong , Seungryul, Yoo , Bongju, Lee
Appeared in: Journal of Electrostatics
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» An Augmented Echo State Network for Nonlinear Adaptive Filtering of Complex Noncircular Signals
Abstract:
A novel complex echo state network (ESN), utilizing full second-order statistical information in the complex domain, is introduced. This is achieved through the use of the so-called augmented complex statistics, thus making complex ESNs suitable for processing the generality of complex-valued signals, both second-order circular (proper) and noncircular (improper). Next, in order to deal with nonstationary processes with large nonlinear dynamics, a nonlinear readout layer is introduced and is further equipped with an adaptive amplitude of the nonlinearity. This combination of augmented complex statistics and enhanced adaptivity within ESNs also facilitates the processing of bivariate signals with strong component correlations. Simulations in the prediction setting on both circular and noncircular synthetic benchmark processes and real-world noncircular and nonstationary wind signals support the analysis.
Autors: Xia, Y.;Jelfs, B.;Van Hulle, M. M.;Principe, J. C.;Mandic, D. P.;
Appeared in: IEEE Transactions on Neural Networks
Publication date: Jan 2011, volume: 22, issue:1, pages: 74 - 83
Publisher: IEEE
Full litterature document
 
» An Automated Hirschberg Test for Infants
Abstract:
A novel automated method to measure eye misalignment in infants is presented. The method uses estimates of the Hirschberg ratio (HR) and angle Kappa (the angle between the visual and optical axis) for each infant to calculate the angle of eye misalignment. The HR and angle Kappa are estimated automatically from measurements of the direction of the optical axis and the coordinates of the center of the entrance pupil and corneal reflexes in each eye when infants look at a set of images that are presented sequentially on a computer monitor. The HR is determined by the slope of the line that describes the direction of the optical axis as a function of the distance between the center of the entrance pupil and the corneal reflexes. The peak of the distribution of possible angles Kappa during the image presentation determines the value of angle Kappa. Experiments with five infants showed that the 95% limits of agreement between repeated measurements of angle Kappa are 0.61 . The maximum error in the estimation of eye alignment in orthotropic infants was 0.9 with 95% limits of agreement between repeated measurements of 0.75 .
Autors: Model*, D.;Eizenman, M.;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: Jan 2011, volume: 58, issue:1, pages: 103 - 109
Publisher: IEEE
Full litterature document
 
» An effective biophysical indicator for opium yield estimation
Abstract:
 Research highlights: ? LAI is an effective biophysical indicator for opium yield estimation. ? LAI in flowering and harvesting stages has linear relationship with opium yield. ? Providing a potential way for estimating opium yield using remote sensing.

Autors: Opium is a narcotic obtained from opium poppy and raw materials of heroin for illegal drug trade. Information on opium production is important for governments and international communities to understand the scale of illegal drug trade and to implemen
Appeared in: Computers and Electronics in Agriculture
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» An effective matrix poling characteristics of 1-3-2 piezoelectric composites
Abstract:
An analytical model is developed to evaluate the performance of 1-3-2 piezoelectric composite where both matrix and fiber materials are piezoelectrically active. A parametric study is conducted to investigate the effects of variations in the poling characteristics of the matrix phase on the overall thermo-electro-mechanical behavior of a 1-3-2 piezocomposite. The figures of merit (FOM) of the 1-3-2 composite as a transducer for underwater acoustics and biomedical imaging applications has been analyzed. It is demonstrated that the effective electromechanical coupling coefficient (Kt) can be enhanced by poling the polymer matrix at 180 degree poling direction for low ceramic rod volume...
Autors: M., Sakthivel , A., Arockiarajan
Appeared in: Sensors and Actuators A: Physical
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» An Efficient High-Step-Up Interleaved DC–DC Converter With a Common Active Clamp
Abstract:
This paper presents a high-efficiency and high-step-up nonisolated interleaved dc–dc converter with a common active-clamp circuit. In the presented converter, the coupled-inductor boost converters are interleaved. A boost converter is used to clamp the voltage stresses of all the switches in the interleaved converters, caused by the leakage inductances present in the practical coupled inductors, to a low voltage level. The leakage energies of the interleaved converters are collected in a clamp capacitor and recycled to the output by the clamp boost converter. The proposed converter achieves high efficiency because of the recycling of the leakage energies, reduction of the switch voltage stress, mitigation of the output diode's reverse recovery problem, and interleaving of the converters. Detailed analysis and design of the proposed converter are carried out. A prototype of the proposed converter is developed, and its experimental results are presented for validation.
Autors: Dwari, S.;Parsa, L.;
Appeared in: IEEE Transactions on Power Electronics
Publication date: Jan 2011, volume: 26, issue:1, pages: 66 - 78
Publisher: IEEE
Full litterature document
 
» An Efficient Method for Supervised Hyperspectral Band Selection
Abstract:
Band selection is often applied to reduce the dimensionality of hyperspectral imagery. When the desired object information is known, it can be achieved by finding the bands that contain the most object information. It is expected that these bands can provide an overall satisfactory detection and classification performance. In this letter, we propose a new supervised band-selection algorithm that uses the known class signatures only without examining the original bands or the need of class training samples. Thus, it can complete the task much faster than traditional methods that test bands or band combinations. The experimental result shows that our approach can generally yield better results than other popular supervised band-selection methods in the literature.
Autors: Yang, H.;Du, Q.;Su, H.;Sheng, Y.;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jan 2011, volume: 8, issue:1, pages: 138 - 142
Publisher: IEEE
Full litterature document
 
» An electrically detected magnetic resonance study of performance limiting defects in SiC metal oxide semiconductor field effect transistors
Abstract:
In this study, we utilize electrically detected magnetic resonance (EDMR) techniques and electrical measurements to study defects in SiC based metal oxide semiconductor field effect transistors (MOSFETs). We compare results on a series of SiC MOSFETs prepared with significantly different processing parameters. The EDMR is detected through spin dependent recombination (SDR) in most cases. However, in some devices at a fairly high negative bias, the EDMR likely also involves spin dependent trap-assisted tunneling (SDT) between defects on both sides of the SiC/SiO2 interface. At least three different defects have been detected in the magnetic resonance measurements. The defects observed include two at the SiC/SiO2 interface or on the SiC side of the SiC/SiO2 interface: one is very likely a vacancy center with a distribution which extends into the bulk of the SiC and the other is likely a “dangling bond” defect. A third defect, located on the SiO2 side of the SiC/SiO2 interface, has a spectrum very similar to that previously reported for an oxygen deficient silicon coupled to a hydrogen atom. In nearly all cases, we observe a strong dominating single line EDMR spectrum with an isotropic g≈2.0027. In some samples, this strong central line is accompanied by two pairs of considerably weaker side peaks which we link to hyperfine interactions with nearby Si and C atoms. The pattern is physically reasonable for a silicon vacancy in SiC. We therefore tentatively assign it to a silicon vacancy or silicon vacancy associated defect in the SiC. In one set of devices with very high interface trap density we observe another dominating spectrum wi- - th g=2.0026 and g=2.0010 with the symmetry axis coincident with the [0001] and nearly the SiC/SiO2 interface normal. We ascribe this EDMR spectrum to a “dangling bond” defect. A third EDMR spectrum shows up in some devices at a fairly large negative gate bias. The phase of this spectrum is quite consistently opposite to that of the SDR detected EDMR at other biases. Part of this inverted phase spectrum involves two narrow lines which are separated by ≈10.5 G. Since the center responsible for this spectrum is almost certainly in the SiO2, it is likely due to the so called 10.4 G doublet center, an unpaired electron residing on an oxygen deficient silicon atom coupled to a hydrogen in SiO2. The likely presence of one oxygen deficient silicon defect suggests that other oxygen deficient silicon atom defect sites in the oxide may also be important in SiC/SiO2 devices. Oxygen deficient silicon defects in SiO2 are typically called E centers. Our results collectively demonstrate considerable complexity in both the chemical composition and physical distribution of performance limiting defects in SiC transistors, with defects observed on both sides of the SiC/SiO2 interface. Our results most strongly indicate that fairly high densities of intrinsic deep-level defects, likely due to a Si vacancy or a closely related defect, extend into the bulk of the SiC in all but one of the devices prepared utilizing a fairly wide range of processing parameters.
Autors: Cochrane, C. J.;Lenahan, P. M.;Lelis, A. J.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 014506 - 014506-12
Publisher: IEEE
Full litterature document
 
» An electrode-free method of characterizing the microwave dielectric properties of high-permittivity thin films
Abstract:
A thin dielectric resonator consisting of a dielectric substrate and the thin film deposited upon it is shown to suffice for microwave characterization and dielectric parameter measurement of high-permittivity thin films without electrodes. The TE01δ resonance mode was excited and measured in thin (down to 0.1 mm) rectangular- or disk-shaped low-loss dielectric substrates (D∼10 mm) with permittivity ε≥10 inserted into a cylindrical shielding cavity or rectangular waveguide. The in-plane dielectric permittivity and losses of alumina, DyScO3, SmScO3, and (LaAlO3)0.29(SrAl1/2Ta1/2O3)0.71 (LSAT) substrates were measured from 10 to 18 GHz. The substrate thickness optimal for characterization of the overlying thin film was determined as a function of the substrate permittivity. The high sensitivity and efficiency of the method, i.e., of a thin dielectric resonator to the dielectric parameters of an overlying film, was demonstrated by characterizing ultrathin strained EuTiO3 films. A 22 nm thick EuTiO3 film grown on a (100) LSAT substrate and strained in biaxial compression by 0.9% exhibited an increase in microwave permittivity at low temperatures consistent with it being an incipient ferroelectric; no strain-induced ferroelectric phase transition was seen. In contrast, a 100 nm thick EuTiO3 film grown on a (110) DyScO3 substrate and strained in biaxial tension by 1% showed two peaks as a function of temperature- - in microwave permittivity and loss. These peaks correspond to a strain-induced ferroelectric phase transition near 250 K and to domain wall motion.
Autors: Bovtun, V.;Pashkov, V.;Kempa, M.;Kamba, S.;Eremenko, A.;Molchanov, V.;Poplavko, Y.;Yakymenko, Y.;Lee, J. H.;Schlom, D. G.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 024106 - 024106-6
Publisher: IEEE
Full litterature document
 
» An Empirical Model for Propagation Loss Through Tropical Woodland in Urban Areas at UHF
Abstract:
A vegetation path loss model was derived from measurements performed in a downtown park in Rio de Janeiro city, from 0.9 to 1.8 GHz. The resulting equation followed the general formulation in ITU-R Recommendation P.833. A comparative analysis was carried out with other empirical models, assessing statistical adherence to the available data. Coherent results were observed.
Autors: Dias, M. H. C.;de Assis, M. S.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2011, volume: 59, issue:1, pages: 333 - 335
Publisher: IEEE
Full litterature document
 
» An Estimation Method of Rotational Direction and Speed for Free-Running AC Machines Without Speed and Voltage Sensor
Abstract:
This paper presents an estimation method of rotational direction and speed for free-running ac machines driven by an inverter without speed and voltage sensor. The method has four estimation modes, and it utilizes only the measured phase current of machines. The performance of the proposed method is verified through the experiments for both permanent-magnet synchronous motor and asynchronous machines.
Autors: Iura, H.;Ide, K.;Hanamoto, T.;Chen, Z.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2011, volume: 47, issue:1, pages: 153 - 160
Publisher: IEEE
Full litterature document
 
» An explanation for laser-induced spallation effect in a-C:H films: Altered phase evolution route caused by hydrogen doping
Abstract:
The laser-induced spalling effect has been recognized as a unique phenomenon for amorphous carbon (a-C) films during laser processing. In this work, the origin of spalling effect was investigated by ablating two different types of a-C film: hydrogenated a-C (a-C:H) and nonhydrogenated a-C with an Nd-yttrium aluminum garnet laser system. Comparisons of ablating results demonstrated that the spalling effect only occurred in a-C:H rather than nonhydrogenated a-C. Laser heating simulation indicated that the temperature distributions in both films after laser pulse are similar with a high temperature gradient in depth direction. Annealing test results, Raman spectra and nanoindentation show that with the increase in annealing temperature, a-C film transforms into grassy carbon directly, while a-C:H experiences two subprocess under heating: the hydrogen mobilization and rearrangement of CC network at a relatively low temperature range resulting in a denser CC network and raised film density; the graphitization at high temperature which would lower the film density. We propose that the reason of laser-induced spalling effect in a-C:H might depend on two aspects: (1) the heat source like laser pulse which could produce a high temperature gradient in depth direction within ultrashort time and (2) the unique evolution process of film microstructure under heating. Based on above model, the spalling effect is ascribed to the concentrated stress caused by different structu- - re evolution subprocess at different depth in a-C:H during the laser irradiation. It is remarkable that the conclusions deduced from our model are proven to be in good agreement with our experimental results and the previous articles reported by others.
Autors: Ding, Qi;Wang, Liping;Hu, Litian;Hu, Tianchang;Wang, Yunfeng;Zhang, Yaonan;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 013501 - 013501-9
Publisher: IEEE
Full litterature document
 
» An Impedance-Based Approach for Identifying Interharmonic Sources
Abstract:
This paper proposes a new method for identifying the interharmonic source location in power systems. The method is based on the interharmonic impedances measured at the metering points, and is inspired by the fact that the impedance of interharmonic-generating loads at that frequency is much higher than that of the utility system. This method represents an improvement over the traditional power-direction method, as the new method is more robust and less prone to erroneous identification. The issues associated with data reliability are addressed, and a set of data reliability criteria is presented. The effectiveness of the new method has been verified through simulation studies and field measurements.
Autors: Nassif, A. B.;Yong, J.;Mazin, H.;Wang, X.;Xu, W.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Jan 2011, volume: 26, issue:1, pages: 333 - 340
Publisher: IEEE
Full litterature document
 
» An Implantable Optical Stimulation Delivery System for Actuating an Excitable Biosubstrate
Abstract:
The use of light-activated modulation techniques, such as optogenetics, is growing in popularity for enabling basic neuroscience research. It is also being explored for advancing more applied applications like therapeutic neuromodulation. However, current hardware systems are generally limited to acute measurements or require external tethering of the system to the light source. This paper presents an implantable prototype for use in techniques that modulate neurological state through optically-activated channels and compounds. The prototype system employs a three chip custom IC architecture to manage information flow into the neural substrate, while also handling power dissipation and providing a chronic barrier to the tissue interface. In addition to covering the details of the IC architecture, we discuss system level design constraints and solutions, and in-vitro test results using our prototype system with an optogenetic model. Potential technical limitations for the broader adoption of these techniques will also be considered.
Autors: Paralikar, K.;Cong, P.;Yizhar, O.;Fenno, L. E.;Santa, W.;Nielsen, C.;Dinsmoor, D.;Hocken, B.;Munns, G. O.;Giftakis, J.;Deisseroth, K.;Denison, T.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Jan 2011, volume: 46, issue:1, pages: 321 - 332
Publisher: IEEE
Full litterature document
 
» An Improved Image Compression Algorithm Using Binary Space Partition Scheme and Geometric Wavelets
Abstract:
Geometric wavelet is a recent development in the field of multivariate nonlinear piecewise polynomials approximation. The present study improves the geometric wavelet (GW) image coding method by using the slope intercept representation of the straight line in the binary space partition scheme. The performance of the proposed algorithm is compared with the wavelet transform-based compression methods such as the embedded zerotree wavelet (EZW), the set partitioning in hierarchical trees (SPIHT) and the embedded block coding with optimized truncation (EBCOT), and other recently developed “sparse geometric representation” based compression algorithms. The proposed image compression algorithm outperforms the EZW, the Bandelets and the GW algorithm. The presented algorithm reports a gain of 0.22 dB over the GW method at the compression ratio of 64 for the Cameraman test image.
Autors: Chopra, G.;Pal, A. K.;
Appeared in: IEEE Transactions on Image Processing
Publication date: Jan 2011, volume: 20, issue:1, pages: 270 - 275
Publisher: IEEE
Full litterature document
 
» An Improved Maximum Power Point Tracking for Photovoltaic Grid-Connected Inverter Based on Voltage-Oriented Control
Abstract:
In this paper, an improved maximum power point (MPP) tracking (MPPT) with better performance based on voltage-oriented control (VOC) is proposed to solve a fast-changing irradiation problem. In VOC, a cascaded control structure with an outer dc link voltage control loop and an inner current control loop is used. The currents are controlled in a synchronous orthogonal frame using a decoupled feedback control. The reference current of proportional–integral (PI)  -axis controller is extracted from the dc-side voltage regulator by applying the energy-balancing control. Furthermore, in order to achieve a unity power factor, the -axis reference is set to zero. The MPPT controller is applied to the reference of the outer loop control dc voltage photovoltaic (PV). Without PV array power measurement, the proposed MPPT identifies the correct direction of the MPP by processing the -axis current reflecting the power grid side and the signal error of the PI outer loop designed to only represent the change in power due to the changing atmospheric conditions. The robust tracking capability under rapidly increasing and decreasing irradiance is verified experimentally with a PV array emulator. Simulations and experimental results demonstrate that the proposed method provides effective, fast, and perfect tracking.
Autors: Kadri, R.;Gaubert, J.-P.;Champenois, G.;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: Jan 2011, volume: 58, issue:1, pages: 66 - 75
Publisher: IEEE
Full litterature document
 
» An Improved Methodology for the CAD Optimization of Multiple Floating Field-Limiting Ring Terminations
Abstract:
We derive an efficient and accurate computer-aided-design-based design methodology for the optimization of floating field-limiting ring terminations. The proposed approach is based on an iterative optimization of the ring-to-ring spacings starting from the outermost ring and proceeding back toward the main junction. Physics-based simulations show that each optimization step does not impair the previous one, thus allowing to easily identify the minimum number of rings needed to achieve the desired termination efficiency yet minimizing the number of simulation steps. The accuracy of the method is thoroughly discussed on the basis of comparisons against either literature results or experimental data.
Autors: El Baradai, N.;Sanfilippo, C.;Carta, R.;Cappelluti, F.;Bonani, F.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2011, volume: 58, issue:1, pages: 266 - 270
Publisher: IEEE
Full litterature document
 
» An Improved Scheme for Target Discrimination in High-Resolution SAR Images
Abstract:
To design a highly automatic and practical method for target discrimination in synthetic aperture radar images, we propose in this paper an improved scheme consisting of the framework and algorithms for target discrimination. Our main contribution in this scheme comprises four aspects. First, an integrative frame sequentially combining the algorithm based on feature extraction and the knowledge of target group has been presented. Second, three new features for target discrimination have been introduced. Third, a genetic algorithm-based feature-selection algorithm has been presented. The results show that this algorithm can evaluate the goodness-of-feature better. Finally, to improve the accuracy of the discriminator, we have designed a weighted quadratic distance discriminator, which has been observed to improve the performance of target discrimination. We have analyzed the performance of the proposed scheme comprehensively and specifically using some measured data, and carried out comparisons of the existing algorithms. The results show that the proposed scheme could improve the application ability in target discrimination.
Autors: Gao, G.;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Jan 2011, volume: 49, issue:1, pages: 277 - 294
Publisher: IEEE
Full litterature document
 
» An Improved Square-Root Algorithm for V-BLAST Based on Efficient Inverse Cholesky Factorization
Abstract:
A fast algorithm for inverse Cholesky factorization is proposed, to compute a triangular square-root of the estimation error covariance matrix for Vertical Bell Laboratories Layered Space-Time architecture (V-BLAST). It is then applied to propose an improved square-root algorithm for V-BLAST, which speedups several steps in the previous one, and can offer further computational savings in MIMO Orthogonal Frequency Division Multiplexing (OFDM) systems. Compared to the conventional inverse Cholesky factorization, the proposed one avoids the back substitution (of the Cholesky factor), and then requires only half divisions. The proposed V-BLAST algorithm is faster than the existing efficient V-BLAST algorithms. The expected speedups of the proposed square-root V-BLAST algorithm over the previous one and the fastest known recursive V-BLAST algorithm are 3.9 ∼ 5.2 and 1.05 ∼ 1.4, respectively.
Autors: Zhu, Hufei;Chen, Wen;Li, Bin;Gao, Feifei;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Jan 2011, volume: 10, issue:1, pages: 43 - 48
Publisher: IEEE
Full litterature document
 
» An Integrated Framework for Smart Microgrids Modeling, Monitoring, Control, Communication, and Verification
Abstract:
The microgrid (MG) paradigm is a new concept which is considered as a solution for addressing technical, economical, and environmental issues of modern power systems. The application of MG is the subject of extensive studies and experimental tests. It is recognized that there are a number of technical challenges concerning the operation, monitoring, control, and protection of MGs systems. In this respect, the rapid development of the information and communication technologies (ICTs) has opened the door for feasible and cost-effective solutions allowing more extensive intra- and interutility information exchange, diffusion, and open access to a wide range of real-time information. Consequently, the ICTs could represent a strategic tool in supporting effective MG operation. According to this statement, the paper proposes an advanced framework based on the service-oriented architectures for integrated MG modeling, monitoring, and control. The proposed framework is platform, language, and vendor independent, and thus it is an ideal candidate for an effective integration in existing energy management systems and distribution management systems (EMSs/DMSs).
Autors: Vaccaro, A.;Popov, M.;Villacci, D.;Terzija, V.;
Appeared in: Proceedings of the IEEE
Publication date: Jan 2011, volume: 99, issue:1, pages: 119 - 132
Publisher: IEEE
Full litterature document
 
» An Integrated Laser Radar Receiver Channel Utilizing a Time-Domain Walk Error Compensation Scheme
Abstract:
An integrated receiver channel for a pulsed time-of-flight (TOF) laser rangefinder has been designed and fabricated in a 0.35- SiGe BiCMOS process. The receiver channel generates a timing mark for the TDC by means of a leading-edge timing discriminator that detects the crossover of the received pulse with respect to a set reference level. The walk error generated by the amplitude variation is compensated in the time domain on the basis of the measured dependence of the walk on the length of the received pulse. The measurement accuracy is 15 ps with compensation within a dynamic range of 1:100 000, and the single-shot precision and power consumption are 120 ps for a minimum detectable signal of and 115 mW, respectively.
Autors: Kurtti, S.;Kostamovaara, J.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2011, volume: 60, issue:1, pages: 146 - 157
Publisher: IEEE
Full litterature document
 
» An integrated on chip organic optical source based on electrochemiluminescence
Abstract:
We report here on an original "glass-PDMS-glass" electrochemiluminescence optofluidic device that integrates 32 electrodes on a large surface. This organic electrically powered light source has been integrated on chip using an alternative process based on a photopatternable silicone resist. Under a continuous flow rate, this device allows electrogenerated chemiluminescence for several minutes which would be very useful for future ?TAS systems.
Autors: Sébastien, Méance , Kévin, Papin , Jean, Gamby , Guillaume, Aubry , Qingli, Kou , ...
Appeared in: Microelectronic Engineering
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» An Integrated SiGe HBT Pulselength Modulator for Class-S Power Amplifiers in the UHF Range
Abstract:
Switch-mode amplifiers have gained interest in the RF-frequency range, due to their promising features of high linearity and especially high efficiency, compared to conventional class-AB amplifiers. For the operation of a class-S amplifier, it is necessary to convert the arbitrarily modulated RF signal into a pulselength modulated signal. This can be accomplished by delta–sigma modulation or by pulselength modulation. Here, the classical design of a pulselength modulator circuit is presented and applied to the UHF frequency range, which converts digitally modulated 450 MHz RF-signals, with a clock rate of 1.8 GHz. The developed integrated circuit features a forward structure without any feedback, which makes the modulator inherently stable and offers a high degree of frequency flexibility. The modulator was manufactured in a 0.25 m SiGe-BiCMOS technology (IHP, Frankfurt/Oder, Germany). Measurement results for a 64-QAM test signal show promising results like minimum error vector magnitudes of about 1% and a carrier-to-noise ratio of up to 60 dB.
Autors: Hartmann, C.;Blau, K.;Hein, M. A.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jan 2011, volume: 58, issue:1, pages: 62 - 69
Publisher: IEEE
Full litterature document
 
» An Inter-Landmark Approach to 4-D Shape Extraction and Interpretation: Application to Myocardial Motion Assessment in MRI
Abstract:
This paper presents a novel approach to shape extraction and interpretation in 4-D cardiac magnetic resonance imaging data. Statistical modeling of spatiotemporal interlandmark relationships is performed to enable the decomposition of global shape constraints and subsequently of the image analysis tasks. The introduced descriptors furthermore provide invariance to similarity transformations and thus eliminate pose estimation errors in the presence of image artifacts or geometrical inconsistencies. A set of algorithms are derived to address key technical issues related to constrained boundary tracking, dynamic model relaxation, automatic initialization, and dysfunction localization. The proposed framework is validated with a relatively large dataset of 50 subjects and compared to existing statistical shape modeling methods. The results indicate increased adaptation to spatiotemporal variations and imaging conditions.
Autors: Lekadir, K.;Keenan, N. G.;Pennell, D. J.;Yang, G.-Z.;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Jan 2011, volume: 30, issue:1, pages: 52 - 68
Publisher: IEEE
Full litterature document
 
» An Interleaved Flyback Converter Featured With Zero-Voltage Transition
Abstract:
This paper proposes an interleaved flyback converter, which is remarked with zero-voltage-switched active switches and reduced reverse-recovery loss on the rectifying diodes. The converter is composed of two parallel-operated identical flyback converters and an auxiliary inductor shunted between the diodes. This converter can provide up to 500 W power with highest efficiency as high as 91%. In addition, burst-mode control is equipped to drive the converter at low load. Even at 50-W output, the efficiency is higher than 83%.
Autors: Hsieh, Y.;Chen, M.;Cheng, H.;
Appeared in: IEEE Transactions on Power Electronics
Publication date: Jan 2011, volume: 26, issue:1, pages: 79 - 84
Publisher: IEEE
Full litterature document
 
» An Internal Calibration Scheme for Polarimetric Synthetic Aperture Radar System
Abstract:
Two important aspects of internal calibration of polarimetric synthetic aperture radar are discussed, i.e., system gain calibration and individual transmit/receive module (TRM) calibration. System gain variation is measured, utilizing the internal calibration loop. A dual-channel TRM gain and phase calibration is carried out using orthogonal phase coding, where a signal of individual TRM is phase encoded according to a set of orthogonal codes in order to be separated from the composite calibration signal of all TRMs. Calibration results are developed both theoretically and through simulation in the case of TRM failure. Error introduced by phase-shifter toggling inaccuracy is discussed. A cross talk model is used to investigate the effect of imperfect isolation between the two polarization channels of each TRM on the calibration error.
Autors: Wang, S.;Qi, H.;Yu, W.;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Jan 2011, volume: 49, issue:1, pages: 15 - 20
Publisher: IEEE
Full litterature document
 
» An investigation of reliability of solder joints in microelectronic packages by high temperature moiré method
Abstract:
In this study, novel high temperature moiré interferometry was applied to assess the long-term reliability of solder joints in Ball Grid Array (BGA) packages. Actual in situ deformation of the solder joints was measured as the joints were subjected to thermal loading and unloading processes. Quantitative strain analysis provided subtle details on shear strain concentrations at multi-material junctures and within interconnections. The measured thermal deformation was then substituted into fatigue models, which enabled the fatigue lives of the packages to be predicted. Comparisons between performances of the eutectic (63wt%Sn/37wt%Pb) and Pb-free SAC387 (95.5wt%Sn/3.8wt%Ag/0.7wt%Cu) solder joints were made on individual components....
Autors: Haixia, Shang , Jianxin, Gao , P., Ian Nicholson , Steve, Kenny
Appeared in: Microelectronics Reliability
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» An Iterative Decoding Algorithm with Backtracking to Lower the Error-Floors of LDPC Codes
Abstract:
Error-floors are the main reason for excluding LDPC codes from applications requiring very low bit-error rate. They are attributed to a particular structure in the codes' Tanner graphs, known as trapping sets, which traps the message-passing algorithms commonly used to decode LDPC codes, and prevents decoding from converging to the correct codeword. A technique is proposed to break trapping sets while decoding. Based on decoding results leading to a decoding failure, some bits are identified in a previous iteration and flipped and decoding is restarted. This backtracking may enable the decoder to get out of the trapped state. A semi-analytical method is also proposed to predict the error-floor after backtracking. Simulation results indicate the effectiveness of the proposed technique in lowering the error-floor. The technique, which has moderate complexity overhead, is applicable to any code without requiring a prior knowledge of the structure of its trapping sets.
Autors: Kang, Jingyu;Huang, Qin;Lin, Shu;Abdel-Ghaffar, Khaled;
Appeared in: IEEE Transactions on Communications
Publication date: Jan 2011, volume: 59, issue:1, pages: 64 - 73
Publisher: IEEE
Full litterature document
 
» An Iterative Hungarian Algorithm Based Coordinated Spectrum Sensing Strategy
Abstract:
Coordinated spectrum sensing ensures Cognitive Radio systems to get the usability of every channel within the entire spectrum of interest by assigning terminals to detect different channels simultaneously. This letter proposes an optimized channel-assignment strategy for coordinated spectrum sensing based on an Iterative Hungarian Algorithm. Simulation results show that the proposed strategy performs excellently in improving the overall sensing performance of the system.
Autors: Wang, Zaili;Feng, Zhiyong;Zhang, Ping;
Appeared in: IEEE Communications Letters
Publication date: Jan 2011, volume: 15, issue:1, pages: 49 - 51
Publisher: IEEE
Full litterature document
 
» An Obfuscation-Based Approach for Protecting Location Privacy
Abstract:
The pervasive diffusion of mobile communication devices and the technical improvements of location techniques are fostering the development of new applications that use the physical position of users to offer location-based services for business, social, or informational purposes. In such a context, privacy concerns are increasing and call for sophisticated solutions able to guarantee different levels of location privacy to the users. In this paper, we address this problem and present a solution based on different obfuscation operators that, when used individually or in combination, protect the privacy of the location information of users. We also introduce an adversary model and provide an analysis of the proposed obfuscation operators to evaluate their robustness against adversaries aiming to reverse the obfuscation effects to retrieve a location that better approximates the location of the users. Finally, we present some experimental results that validate our solution.
Autors: Ardagna, C.A.;Cremonini, M.;De Capitani di Vimercati, S.;Samarati, P.;
Appeared in: IEEE Transactions on Dependable and Secure Computing
Publication date: Jan 2011, volume: 8, issue:1, pages: 13 - 27
Publisher: IEEE
Full litterature document
 
» An Objective Approach to Measuring Video Playback Quality in Lossy Networks using TCP
Abstract:
In this work, we investigate a new objective measurement for assessing the video playback quality for services delivered in networks that use TCP as a transport layer protocol. We define the new metric as pause intensity to characterize the quality of playback in terms of its continuity since, in the case of TCP, data packets are protected from losses but not from delays. Using packet traces generated from real TCP connections in a lossy environment, we are able to simulate the playback of a video and monitor buffer behaviors in order to calculate pause intensity values. We also run subjective tests to verify the effectiveness of the metric introduced and show that the results of pause intensity and the subjective scores made over the same real video clips are closely correlated.
Autors: Porter, Timothy;Peng, Xiao-Hong;
Appeared in: IEEE Communications Letters
Publication date: Jan 2011, volume: 15, issue:1, pages: 76 - 78
Publisher: IEEE
Full litterature document
 
» An Octagonal Dual-Gate Transistor With Enhanced and Adaptable Low-Frequency Noise
Abstract:
As the low-frequency noise of a transistor grows nonnegligible in advanced technologies, the possibility of using noise for computation is becoming an alternative, receiving more and more attention. The ability to control the noise level would further enrich the flexibility of the circuit design. Therefore, this letter presents a dual-gate field-effect transistor in an octagonal shape. By changing the voltage of an extra gate above the shallow trench isolation, the transistor is able to adapt its low-frequency noise over several decades and in a power-efficient manner. The octagonal geometry further makes sufficient a voltage range from 0 to 5 V for the noise adaptation. Moreover, the transistor is fabricated with the standard CMOS logic process without additional masks. All the features underpin the development of large-scale noisy computation in integrated circuits.
Autors: Chiu, T.-J.;Gong, J.;King, Y.-C.;Lu, C.-C.;Chen, H.;
Appeared in: IEEE Electron Device Letters
Publication date: Jan 2011, volume: 32, issue:1, pages: 9 - 11
Publisher: IEEE
Full litterature document
 
» An ontology-based context inference service for mobile applications in next-generation networks
Abstract:
Context enabled mobile applications are considered to provide a richer experience and to enhance the user interaction by acquiring information that allows the identification of the user¿s current situation. Modern context inference infrastructures can source, process and deliver user information. However, a commercialization towards a context service has still been prohibited by the need for global service coverage and accurate context identification. With the advent of Next Generation Networks, telecom operators can leverage All-IP networks to design external service interfaces that integrate a diverse set of sources and context inference processes that are easily scalable, extendable, and robust at the same time. This article presents a telecom operator service that supplies mobile applications with context information to illustrate how context infrastructures can leverage NGN capabilities. The article introduces an innovative context inference approach involving third Party applications within the inference process itself. This is done by structuring the ontology context model in layers of complexity and inferring particular context information via modules, which are designed in collaboration with third party developers. Furthermore, the service is compliant with state-of-the-art IP Multimedia Subsystem infrastructures and provides an interface that uses HTTP/SOAP and HTTP/REST communication as well as the Session Initiation Protocol of the IMS. A first proof of concept indicates an increased service adoption, a higher accuracy of context, and an increased robustness towards errors.
Autors: Gutheim, P.;
Appeared in: IEEE Communications Magazine
Publication date: Jan 2011, volume: 49, issue:1, pages: 60 - 66
Publisher: IEEE
Full litterature document
 
» An overview of an illuminator of opportunity passive radar research project and its signal processing research directions
Abstract:
In this paper, an overview of an Illuminator of Opportunity (IOO) Passive Radar research project being conducted at DSTO is presented, with a specific focus on the signal processing research directions that are being investigated. The overview provides a discussion on the selection of transmitters as well as a description of the multi-channel receiver. The signal processing research direction discussion will cover such topics as: the development of a computationally efficient approximation to the 2D Woodward Cross-ambiguity function; improving the cross-ambiguity SNR by exploiting the transmitted waveform's inbuilt Forward Error Correction; as well as signal processing means for suppressing the...
Autors: J., Palmer , S., Palumbo , A., Summers , D., Merrett , S., Searle , ...
Appeared in: Digital Signal Processing
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» An SVD audio watermarking approach using chaotic encrypted images
Abstract:
This paper presents a new approach for audio watermarking using the Singular Value Decomposition (SVD) mathematical technique. The proposed approach can be used for data hiding in the audio signals transmitted over wireless networks and for multi-level security systems as will be stated in the applications section. This approach is based on embedding a chaotic encrypted watermark in the singular values of the audio signal after transforming it into a 2-D format. The selection of the chaotic encryption algorithm for watermark encryption is attributed to its permutation nature, which resists noise, filtering, and compression attacks. After watermark embedding, the audio...
Autors: Waleed, Al-Nuaimy , Mohsen A.M., El-Bendary , Amira, Shafik , Farid, Shawki , A.E., Abou-El-azm , ...
Appeared in: Digital Signal Processing
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» An ultralow noise current amplifier based on superconducting quantum interference device for high sensitivity applications
Abstract:
An integrated ultrahigh sensitive current amplifier based on a niobium dc superconducting quantum interference device (SQUID) has been developed. The sensor design is based on a multiturn signal coil coupled to a suitable SQUID magnetometer. The signal coil consists of 60 square niobium turns tightly coupled to a superconducting flux transformer of a SQUID magnetometer. The primary coil (pick-up coil) of the flux transformer has been suitably designed in order to accommodate the multiturn input coil. It has a side length of 10 mm and a width of 2.4 mm. In such a way we have obtained a signal current to magnetic flux transfer coefficient (current sensitivity) as low as 62 nA/Φ0. The sensor has been characterized in liquid helium by using a direct coupling low noise readout electronic and a standard modulated electronic in flux locked loop configuration for the noise measurements. Beside the circuit complexity, the sensor has exhibited a smooth and free resonance voltage-flux characteristic guaranteeing a reliable and a stable working operation. Considering a SQUID magnetic flux noise of SΦ1/2 = 1.8 μΦ0/Hz1/2 at T = 4.2 K, a current noise as low as 110 fA/Hz1/2 is obtained. Such a value is about a factor two less than the noise of other SQUIDs of the same category. As an application, Nyquist noise measurements of integrated test resistors using the current sensing noise thermometer technique are reported. Due to its high performance such a sensor can be employed in all applications requiring an extremely current sensitivity like the readout of the gravitational wave detectors and the current sensing noise thermometry.
Autors: Granata, C.;Vettoliere, A.;Russo, M.;
Appeared in: Review of Scientific Instruments
Publication date: Jan 2011, volume: 82, issue:1, pages: 013901 - 013901-5
Publisher: IEEE
Full litterature document
 
» An Unconditionally Stable 1-D FDTD Algorithm for Modeling Chiral Media Based on Similar LOD Method
Abstract:
An unconditionally stable scheme, which employs a similar technique to the locally one-dimensional (LOD) method, is proposed to study the one-dimensional (1D) nondispersive chiral media. In the proposed scheme, the recent new mesh-dividing method for bi-isotropic media is used. The method regards the two terms on the right-hand side of the rearranged curl equations as two directions and uses the LOD algorithm to deal with the equivalent two-dimensional (2D) problem. Through Fourier stability analysis and numerical simulation, it is found that the time-step size is not restricted by the Courant-Friedrich-Levy (CFL) stability condition, hence the proposed scheme is unconditionally stable. Compared with the similar Alternating Direction Implicit (ADI) method, the proposed scheme has lighter calculation burden and higher accuracy.
Autors: Chu, Q.-X.;Cao, D.-A.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2011, volume: 59, issue:1, pages: 320 - 323
Publisher: IEEE
Full litterature document
 
» An x86-64 Core in 32 nm SOI CMOS
Abstract:
This paper describes the 32 nm implementation of an AMD x86-64 core , , . It occupies 9.69 , contains more than 35 million transistors (excluding L2 cache), and operates at frequencies in excess of 3 GHz. This AMD chip is fabricated in Global Foundries' 32 nm SOI and uses high-K metal gate technology. The process uses dual strain liners and eSiGe (embedded Silicon Germanium) to improve performance. Transistors are fabricated in various threshold voltages and lengths to facilitate performance/leakage tradeoffs. The core incorporates numerous design and power improvements to enable an operating range of 2.5 W to 25 W and a near zero-power gated state, which makes the core well-suited to a broad range of mobile and desktop products including multicore SOC designs.
Autors: Jotwani, R.;Sundaram, S.;Kosonocky, S.;Schaefer, A.;Andrade, V. F.;Novak, A.;Naffziger, S.;
Appeared in: IEEE Journal of Solid-State Circuits
Publication date: Jan 2011, volume: 46, issue:1, pages: 162 - 172
Publisher: IEEE
Full litterature document
 
» Analogue modulation characteristics of InP membrane microdisc laser for in-building networks
Abstract:
Using thin membrane InP microdisc lasers heterogeneously integrated on a silicon on insulator (SOI) substrate having a broadband analogue modulation bandwidth of 11 GHz, analogue direct modulation with radio data signals (64 and 256 QAM, 20M symbols/s at 5 GHz RF carrier) is demonstrated. The demonstration shows the potential of the microdisc laser as a low-energy analogue optical transmitter with error-vector magnitude penalties of 3.6 and 4.2% for 64 and 256 QAM, respectively, and the low biasing currents for both DC (4 mW) and RF (0.1 mW) signals, which are compatible with signals and currents which can be supplied by a simple CMOS driving chip.
Autors: Jung, H.-D.;Kumar, R.;Regreny, P.;Dorren, H.;Koonen, T.;Raz, O.;
Appeared in: Electronics Letters
Publication date: Jan 2011, volume: 47, issue:2, pages: 121 - 123
Publisher: IEEE
Full litterature document
 
» Analysis and Characterization of a Multipole Reconfigurable Transmitarray Element
Abstract:
A reconfigurable transmitarray element is presented that operates at 5.5 GHz and is low-profile, low-cost and easy to fabricate. The design consists of a three-layer structure implementing two slot-coupled patch antennas. Varactor diodes are used to load the patches and slot to create a third-order resonant structure. A simple circuit-based analysis approach is used to predict the response of the unit cell based on the location of its poles and zeros. Simulation and experimental results are presented, with experimental results achieving 245 of phase agility with less than 3 dB of variation in transmission magnitude throughout the tuning range. The effects of diode loss, angle of incidence, and mutual coupling are investigated. The element is also capable of functioning as a low-loss reconfigurable reflectarray element, making it particularly versatile for different scanning configurations.
Autors: Lau, J. Y.;Hum, S. V.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2011, volume: 59, issue:1, pages: 70 - 79
Publisher: IEEE
Full litterature document
 
» Analysis and Design of a High Performance and Low Cost Bio-mass Sensor based on the Radial Contour Mode Disk Resonator
Abstract:
A high performance and cost effective biosensor is designed based on a radial contour-mode disk resonator. Filling a dielectric material within the capacitive gap, we can achieve low motional resistance (Rx) in a cost-effective manner. The motional resistance of the new device is characterized analytically and validated using 3D-multiphysics simulation. Compared with other biosensors, the introduced biosensor may detect the smaller mass changes with mass sensitivity of -74.68 ?m2/ng (-1617 Hz/ng).
Autors: Amir, Heidari , Yong-Jin, Yoon , Hae-Jin, Choi
Appeared in: Microelectronic Engineering
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» Analysis and Implementation of Half-Bridge Series–Parallel Resonant Converter for Battery Chargers
Abstract:
This paper presents a novel application of half-bridge series–parallel resonant converter (HBSPRC) for dc source and secondary battery interface. The converter practically eliminates both low- and high-frequency current ripple on the battery, thus maximizing battery life without penalizing the volume of the charger circuit. Moreover, operation above resonance is preferred, because the power switches turn on at zero current and zero voltage; thus, the freewheeling diodes do not need to have very fast reverse-recovery characteristics. The proposed battery charger circuit has few components and low-energy conversion loss, which enhance the system's overall efficiency. Circuit operation modes are determined from the conduction profiles. Operating equations and an operating theory are also developed. Experimental results based on a 12-V 48-Ah battery charger are proposed to validate the analysis and to demonstrate the performance of the proposed approach. The maximum charging efficiency of the proposed topology during the overall charging period is 93.98%. Satisfactory performance is obtained from the measured results.
Autors: Chuang, Y.-C.;Ke, Y.-L.;Chuang, H.-S.;Chen, Y.-M.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2011, volume: 47, issue:1, pages: 258 - 270
Publisher: IEEE
Full litterature document
 
» Analysis and Improvement of Linkage Transfer Position for the Operating Mechanism of MCCB
Abstract:
Linkage transfer phenomenon, which exists in the opening process of the operating mechanism of the molded case circuit breaker MCCB, is introduced. The influence of the linkage transfer position on the behavior of the mechanism is analyzed. According to the analysis result, the linkage transfer position of an actual operating mechanism is improved with virtual prototype technology software ADAMS. Simulation and experiment results show that after improvement, the opening time of the mechanism is shortened by about 1 ms. Short-circuit tests demonstrate that the operating mechanism with its linkage transfer position improved is helpful for enhancing the interruption performance of MCCB while breaking the low-current faults.
Autors: Ji, L.;Chen, D.;Liu, Y.;Li, X.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Jan 2011, volume: 26, issue:1, pages: 222 - 227
Publisher: IEEE
Full litterature document
 
» Analysis and Optimization of Compact Suspended Plate MIMO Antennas
Abstract:
This paper presents the analysis and optimization of compact suspended plate antennas for multiple-input-multiple-output (MIMO) wireless local area network (WLAN) applications. First, instead of using the conventional average envelope correlation coefficients, a performance metric using the two- and three-dimensional patterns of the envelope correlation coefficients are proposed to evaluate the diversity performance of antennas in MIMO systems. Following this, a compact three-element suspended plate antenna array with a bent ground plane is presented for WLAN MIMO applications. The diversity performance of the design is experimentally and numerically analyzed. Last, the design guidelines for the optimization of multiple suspended plate antennas in terms of their orientation and feed configuration is provided for achieving the upper bound of the diversity performance with minimum inter-element mutual coupling.
Autors: Chen, Z. N.;Low, X. N.;See, T. S. P.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2011, volume: 59, issue:1, pages: 263 - 270
Publisher: IEEE
Full litterature document
 
» Analysis and Optimization of Transformer-Based Series Power Combining for Reconfigurable Power Amplifiers
Abstract:
Transformer-based series power combiners are analyzed within the context of reconfigurable, watt-level, wideband digital envelope tracking transmitters. A model is developed for designing and analyzing transformer-based switchable series combiners. This model takes into account losses in the windings and nonideal mutual coupling, as well as the effect of switching and scaling the input amplifiers on the combiner efficiency, input impedance, and power combining ratio. Optimum combining efficiency is derived for a combiner with scaled sources. Based on the developed model, a four-element 29.5-dBm power amplifier with 31% peak efficiency at 1.9 GHz, using a 1.5-V supply is designed and simulated in IBM 130-nm CMOS technology. The efficiency drops to 14% at 12 dB power back-off when elements are turned off. The amplifier maintains an output power 25 dBm from 1.8 GHz to 2.5 GHz. The studies presented in this paper can be extended to any series combiner implementation and any frequency range, which can be effective in the design of watt-level power amplifiers in submicrometer CMOS technologies.
Autors: Pye, A. D.;Hella, M. M.;
Appeared in: IEEE Transactions on Circuits and Systems I: Regular Papers
Publication date: Jan 2011, volume: 58, issue:1, pages: 37 - 50
Publisher: IEEE
Full litterature document
 
» Analysis elastic??plastic behaviour and anisotropy properties of copper film from nanoindentation using numerical computation method
Abstract:
The determination of mechanical properties of nanoscale structures is becoming increasingly important as micro-system and ultra-large-scale integrated circuit technologies continue to mature. Traditional experimental methods cannot avoid the influence on the hardness measurement from the presence of the substrate. Numerical computation method of finite-element modelling with molecular dynamics simulation is used to determine the mechanical properties of copper thin film from indentation, quantifying the difference between load against displacement-intosurface curves obtained from different length scale. The results show that the materials deformation exhibits strong size dependence when the relevant physical length scales fall into the range of microns or below. The P??H graph justifies that the permanent plastic deformation quickly decreased while the elastic deformation gradually increased in the range of nanometre level which means increasing of material microhardness. The different deformation behaviour of crystal layers inside the films may be the potential key factor of its breaking off from the substrate. There is little anisotropy phenomenon in the elastic deformation stage whereas there is obvious anisotropy phenomenon in the plastic deformation process. The anisotropy of thin film has strict preferred orientation distribution and symmetry. The anisotropy deformation gradually minimised accompanying the increasing of plastic deformation illuminates the copper thin film is a nonlinear anisotropy elastic??plastic material.
Autors: Han, X.;Wang, S.;Gan, Y.X.;Zhang, L.;Yu, S.;
Appeared in: IET Micro & Nano Letters
Publication date: Jan 2011, volume: 6, issue:1, pages: 13 - 18
Publisher: IEEE
Full litterature document
 
» Analysis of ac-dc conversion for energy harvesting using an electrostrictive polymer P(VDF-TrFE-CFE)
Abstract:
Harvesting systems capable of transforming unused environmental energy into useful electrical energy have been extensively studied for the last two decades. The recent development of electrostrictive polymers has generated new opportunities for harvesting energy. The contribution of this study lies in the design and validation of electrostrictive polymer- based harvesters able to deliver dc output voltage to the load terminal, making the practical application of such material for self-powered devices much more realistic. Theoretical analysis supported by experimental investigations showed that an energy harvesting module with ac-to-dc conversion allows scavenging power up to 7 μW using a bias electric field of 10 V/μm and a transverse strain of 0.2%. This represents a power density of 280 μW/cm3 at 100 Hz, which is much higher than the corresponding values of most piezo-based harvesters.
Autors: Cottinet, P.-J.;Lallart, M.;Guyomar, D.;Guiffard, B.;Lebrun, L.;Sebald, G.;Putson, C.;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Jan 2011, volume: 58, issue:1, pages: 30 - 42
Publisher: IEEE
Full litterature document
 
» Analysis of Access and Connectivity Probabilities in Vehicular Relay Networks
Abstract:
IEEE 802.11p and 1609 standards are currently under development to support Vehicle-to-Vehicle and Vehicle-to-Infrastructure communications in vehicular networks. For infrastructure-based vehicular relay networks, access probability is an important measure which indicates how well an arbitrary vehicle can access the infrastructure, i.e. a base station (BS). On the other hand, connectivity probability, i.e. the probability that all the vehicles are connected to the infrastructure, indicates the service coverage performance of a vehicular relay network. In this paper, we develop an analytical model with a generic radio channel model to fully characterize the access probability and connectivity probability performance in a vehicular relay network considering both one-hop (direct access) and two-hop (via a relay) communications between a vehicle and the infrastructure. Specifically, we derive close-form equations for calculating these two probabilities. Our analytical results, validated by simulations, reveal the tradeoffs between key system parameters, such as inter-BS distance, vehicle density, transmission ranges of a BS and a vehicle, and their collective impact on access probability and connectivity probability under different communication channel models. These results and new knowledge about vehicular relay networks will enable network designers and operators to effectively improve network planning, deployment and resource management.
Autors: Ng, Seh Chun;Zhang, Wuxiong;Zhang, Yu;Yang, Yang;Mao, Guoqiang;
Appeared in: IEEE Journal on Selected Areas in Communications
Publication date: Jan 2011, volume: 29, issue:1, pages: 140 - 150
Publisher: IEEE
Full litterature document
 
» Analysis of Brillouin Precursor Propagation Through Foliage for Digital Sequences of Pulses
Abstract:
In this letter, we investigate the propagation of Brillouin precursors through dispersive foliage media, using leafy vegetation dielectric models proposed by Fung–Ulaby, El Rayes–Ulaby, Brown–Curry–Ding, Maetzler, and Pearce. A fast-Fourier-transform-based formulation is used to analyze the peak amplitude decay and pulse broadening effect (or effective oscillation frequency) related to the precursor formation for both single pulse and sequence of pulses traveling through the leafy vegetation. The influence of the Brillouin precursor on the receiver structure is also investigated. Simulations have been carried out in frequency bands between 100 MHz and 6 GHz allocated for remote sensing applications and digital satellite communications.
Autors: Alejos, A. V.;Dawood, M.;Mohammed, H. U.;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Jan 2011, volume: 8, issue:1, pages: 59 - 63
Publisher: IEEE
Full litterature document
 
» Analysis of Collection Efficiency in Wire-Duct Electrostatic Precipitators Subjected to the Applied Magnetic Field
Abstract:
This paper describes a strongly coupled calculation procedure for the particle dynamics in electrostatic precipitators (ESPs) subjected to the applied magnetic field with the statistical particle size distribution taken into account. The turbulent gas flow and the particle motion under external forces are modeled by using the commercial computational fluid dynamics code FLUENT. Numerical calculations for the gas flow are carried out by solving the Reynolds-averaged Navier–Stokes equations, and the turbulence is modeled by using the turbulence model. An additional source term, which is obtained by solving a coupled system of the electromagnetic field and charge transport equations, is added to the gas flow equation to capture the effect of the electromagnetic field. The particle phase is simulated by using a discrete phase model. Different kinds of particles which follow the Rosin–Rammler distribution were simulated under different conditions, and the influence of the magnetic field density on the capture of a fine particle was investigated. In order to show the dust removal effect, the collection efficiency and the escaped particle size distribution were discussed in case of different applied magnetic fields. The particle trajectories inside the ESP were also given under the effect of both aerodynamic and electromagnetic forces. Numerical results in the wire-duct ESP show that the collection efficiency increases with the increase of the applied magnetic field, that the particle trajectory is more visible to the direction of the dust collection duct, and that the collection efficiency varies smoothly when the absolute value of the applied magnetic field trends to a certain size. Furthermore, the average diameter of escaping particles decreases and the dispersion for dust particles in different sizes increases with increasing applied magnetic field, and particle sizes are linearly decreasing with the magnetic field before the particle diameter is up to- - a certain size.
Autors: Zhang, J.-P.;Ding, Q.-F.;Dai, Y.-X.;Ren, J.-X.;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jan 2011, volume: 39, issue:1, pages: 569 - 575
Publisher: IEEE
Full litterature document
 
» Analysis of elastic waves transmitted through a 2-D phononic crystal exhibiting negative refraction
Abstract:
A two-dimensional phononic crystal (PC) made of a square lattice of air holes in an aluminum matrix is studied. The band structure calculated in the irreducible Brillouin zone of the PC exhibits a branch with a negative slope that allows negative refraction. This phenomenon has been numerically verified using a prism-shaped PC for plane waves entering the PC with two different incidences. A detailed study of the waves at the exit of the PC shows that the plane wave is reconstructed after several wavelengths. Finally, the description of the refracted waves is interpreted using a point source array, giving information about the angular spreading and the relative amplitude of each refracted beam.
Autors: Croenne, C.;Morvan, B.;Vasseur, J.;Dubus, B.;Hladky-Hennion, A.-C.;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Jan 2011, volume: 58, issue:1, pages: 178 - 186
Publisher: IEEE
Full litterature document
 
» Analysis of Information Dissemination in Vehicular Ad-Hoc Networks With Application to Cooperative Vehicle Safety Systems
Abstract:
Cooperative vehicle safety systems (CVSSs) rely on vehicular ad-hoc networks (VANETs) for the delivery of critical vehicle tracking information. The wireless channel in such systems is shared by vehicles within the transmission range of each other. Due to the near-linear spatial distribution of vehicles in a highway scenario, the vehicular broadcast network is heavily affected by the hidden node interference phenomenon, which considerably limits its capacity. The performance of vehicle tracking application that is the basis for CVSS is therefore significantly affected by the performance of the underlying network. The two main parameters that affect the network condition and performance are the range and rate (frequency) of transmission of safety and tracking messages. In this paper, we analyze the effect of different choices of rate and range and present models that quantify network performance in terms of its ability to disseminate tracking information. Following a thorough analysis of the hidden node affected VANET, we show that channel occupancy or busy ratio can be used as a feedback measure that quantifies the success of information dissemination and, consequently, the CVSS, under different network conditions. These findings are used to design feedback control schemes for transmission range adaptation, which are robust to variations of road and network traffic.
Autors: Fallah, Y. P.;Huang, C.-L.;Sengupta, R.;Krishnan, H.;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: Jan 2011, volume: 60, issue:1, pages: 233 - 247
Publisher: IEEE
Full litterature document
 
» Analysis of Interference in Air-to-Ground CDMA Cellular Systems Under Idealized Assumptions
Abstract:
In this paper, we study the air-to-ground cellular systems with no frequency reuse. We provide an analysis of the inter-cell interference under idealized assumptions: 3D hexagonal cell planning, a line of sight channel model with no shadowing and idealized antenna patterns. Based on this model, we derive approximate bounds for the inter to intra-cell interference ratio for the air-to-ground link. In addition, we provide upper bounds on the interference and the outage probability for the ground-to-air link. Simulation results are provided to validate the accuracy of the analytical results.
Autors: Smida, Besma;Tarokh, Vahid;
Appeared in: IEEE Transactions on Communications
Publication date: Jan 2011, volume: 59, issue:1, pages: 258 - 267
Publisher: IEEE
Full litterature document
 
» Analysis of major failures in Europe's power grid
Abstract:
Power grids are prone to failure. Time series of reliability measures such as total power loss or energy not supplied can give significant account of the underlying dynamical behavior of these systems, specially when the resulting probability distributions present remarkable features such as an algebraic tail, usually considered the footprint of self-organization and the existence of critical points. In this paper, 7years (from 2002 to 2008) of Europe's transport of electricity network failure events have been analyzed and the best fit for this empirical data probability distribution is presented. With the actual span of available data and although there exists...
Autors: Martí, Rosas-Casals , Ricard, Solé
Appeared in: International Journal of Electrical Power & Energy Systems
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» Analysis of Optimum Detector of Trellis Coded MPSK in Phase Noise Channels
Abstract:
This paper presents a novel analytical expression which approximates the bit error rate (BER) of the joint phase and symbol maximum a posteriori (JMAP) sequence estimator for: trellis code modulation (TCM) with M-ary phase shift keying (MPSK) modulation; any arbitrary phase noise model (i.e., not limited to the Wiener process); and either a matched or mismatched decoder. First, we derived convenient closed-form expressions for approximating the pairwise error probability of two code sequences for both matched and mismatched decoders. Since the expressions are formulated either in the time or in the frequency domain, it is possible to indicate the contribution of every frequency in the phase noise spectrum. We then applied the union bound on the code sequence pairwise errors. The analytical expression was tight (usually <1dB) for MPSK constellations with M ≥ 4 and code rates ≥ 0.5. Once developed, the expressions will assist designers to consider the influence on receiver performance of the code characteristics, decoder implementation and RF synthesizer phase noise. It further enables joint optimization of the RF synthesizer, the code and the decoder for achieving the lowest error rate or other design targets.
Autors: Bialer, Oded;Raphaeli, Dan;
Appeared in: IEEE Transactions on Communications
Publication date: Jan 2011, volume: 59, issue:1, pages: 130 - 140
Publisher: IEEE
Full litterature document
 
» Analysis of Signal Reconstruction With Jittered Sampling
Abstract:
We consider the linear estimation of square integrable signals from jittered noisy samples. We establish an expression for the integrated mean-square error for correlated jitter and noise processes. We also find the optimal weights of the linear filter. For the case of independent identically distributed (i.i.d.) noise and jitter processes, and a suboptimal filter, we derive the asymptotic distribution of the estimate of the signal. Numerical examples are presented.
Autors: Masry, E.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Jan 2011, volume: 59, issue:1, pages: 27 - 34
Publisher: IEEE
Full litterature document
 
» Analysis of the DC Bias Phenomenon by the Harmonic Balance Finite-Element Method
Abstract:
An Epstein frame-like core model is set up to study the dc-biased problem of the power transformer. The harmonic phenomenon of the model under the dc bias condition is investigated by using the harmonic-balance finite-element method (HBFEM). The harmonic-balance finite element equation is coupled with the external electric circuit. Each harmonic component of the magnetizing current and magnetic field can be calculated directly in the harmonic frequency domains. Comparing the calculated results with the experimental data shows consistency. The dc bias effects on the magnetizing current and the magnetic induction are analyzed through the harmonic solutions.
Autors: Zhao, X.;Lu, J.;Li, L.;Cheng, Z.;Lu, T.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Jan 2011, volume: 26, issue:1, pages: 475 - 485
Publisher: IEEE
Full litterature document
 
» Analysis of the hysteresis in organic thin-film transistors with polymeric gate dielectric
Abstract:
image

Autors:

Graphical abstract

 Graphical abstract:  Research highlights: ? A relationship between the hysteresis in the Id-Vg curves and the Ig was found. ? We studied transistors using either PVA or PVA cross-linked as the gate dielectric. ? The charge
Appeared in: Organic Electronics
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» Analysis, simulation and measurement of square periodic H-guide structures
Abstract:
A simple and accurate method for the S-parameter analysis of square periodic H-guide structures is presented and compared to numerically simulated and measured results. For these structures, the H-guide's rectangular dielectric column is supported by thin, periodic dielectric vanes, forming rectangular air holes. Such a structure is closely related to, but performs over a much wider bandwidth than electromagnetic band gap bordered non-radiative dielectric waveguides that operate in a small band gap region. A power-corrected multiple reflection model capable of accurately predicting the square-periodic H-guide's frequency response up to its first resonant frequency using a simple analytical closed form model for vanes of finite thickness is discussed here.
Autors: Wong, M.;Sebak, A.R.;Denidni, T.A.;
Appeared in: IET Microwaves, Antennas & Propagation
Publication date: Jan 2011, volume: 5, issue:2, pages: 220 - 231
Publisher: IEEE
Full litterature document
 
» Analytical approach to optimise the efficiency of switching mode power amplifiers loaded with distributed matching networks
Abstract:
This study describes the design methodology of optimising the power-added efficiency (PAE) of switching mode power amplifiers (SMPAs). To maximise efficiency, design optimisation of the harmonic loading networks using an analytical analysis approach is proposed. Indeed, by carefully designing a distributed harmonic control network at the output of the SMPA, the insertion loss through the load network can be minimised. To validate the PAE optimisation approach, two 10 W inverse class F power amplifiers (PAs) were designed, manufactured and tested at a frequency of 2.45 GHz using a GaN HEMT transistor. The first PA prototype was matched with a standard distributed harmonic loading network and the second with the proposed distributed harmonic loading network. The measured PAE and gain for the second prototype were improved by 3% and 0.17 dB to reach 73% and 14 dB, respectively.
Autors: Ebrahimi, M.M.;Helaoui, M.;Ghannouchi, F.;
Appeared in: IET Microwaves, Antennas & Propagation
Publication date: Jan 2011, volume: 5, issue:1, pages: 57 - 67
Publisher: IEEE
Full litterature document
 
» Analytical Determination of Optimal Split Ratio of E-Core Permanent Magnet Linear Oscillating Actuators
Abstract:
The split ratio, i.e., the ratio of stator bore radius to stator outer radius, is an important design parameter for permanent-magnet (PM) linear machines, as it significantly influences the thrust force capability and efficiency. The optimal split ratio for maximum thrust force is investigated analytically for both surface-mounted PM (SPM) and interior PM (IPM) E-core linear oscillating actuators. It utilizes simple lumped magnetic circuit models and accounts for the magnetic saturation, the curvature effect, the fringing effect, and the armature reaction effect which may greatly affect the accuracy of the analytical model for the optimal split ratio. The optimal split ratio for both SPM and IPM prototype actuators is found to be around 0.55. The developed analytical models are validated by both finite-element analyses and measurements.
Autors: Chen, X.;Zhu, Z. Q.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Jan 2011, volume: 47, issue:1, pages: 25 - 33
Publisher: IEEE
Full litterature document
 
» Analytical model of thermal-stress induced cracking in two-component material with anisotropic components
Abstract:
This paper deals with an analytical model of cracking in an anisotropic matrix and anisotropic spherical particles with the radius R which are periodically distributed in the infinite matrix. This model multi-particle-matrix system with the particle volume fraction v??0,?/6? is applicable to a two-component material of the precipitate-matrix type with anisotropic components. The cracking which is induced by thermal stresses is investigated within a cubic cell with a central spherical particle. This cubic cell represents such infinite matrix part which is related to one particle. The analytical model of cracking in the spherical particle (q=p) and cell matrix (q=m) includes...
Autors: Ladislav, Ceniga
Appeared in: International Journal of Engineering Science
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» Analytical Models and Performance Evaluation of Drive-thru Internet Systems
Abstract:
Drive-thru Internet systems are multiple-access wireless networks in which users in moving vehicles can connect to a roadside access point (AP) to obtain Internet connectivity for some period of time as the vehicles pass through the AP's coverage range. In order to evaluate the type of communication services and the quality-of-service that these systems can provide, in this paper, we investigate the data communication performance of a vehicle in Drive-thru Internet systems. In particular, we derive analytical models with tractable solutions to characterize the average and the distribution of the number of bytes downloaded by a vehicle by the end of its sojourn through an AP's coverage range, in the presence of other vehicles contending for the same AP's resources. Our models are able to quantify the impact of road traffic density, vehicle speed, service penetration rate, AP's transmission range and the corresponding bit rate, on the amount of data downloaded by an individual vehicle. In terms of analysis technique, we map the study of our vehicular data downloading process into the transient analysis of a series of Markov reward processes. Our use of Markov reward model is novel in the sense that we only select from the corresponding Markov chain, a subset of relevant sample paths that matches the required behavior of our vehicular flow model. We also validate our proposed analytical models through extensive simulations, driven by empirical vehicular traffic traces. We believe our work offers a unique analytical framework based on which the interplay between vehicular traffic parameters and a vehicle's data communication performance in a Drive-thru Internet system can be studied and optimized in a systematic, quantitative manner.
Autors: Tan, Wee Lum;Lau, Wing Cheong;Yue, OnChing;Hui, Tan Hing;
Appeared in: IEEE Journal on Selected Areas in Communications
Publication date: Jan 2011, volume: 29, issue:1, pages: 207 - 222
Publisher: IEEE
Full litterature document
 
» Android: Changing the Mobile Landscape
Abstract:
Autors: Butler, Margaret;
Appeared in: IEEE Pervasive Computing
Publication date: Jan 2011, volume: 10, issue:1, pages: 4 - 7
Publisher: IEEE
Full litterature document
 
» Andy Witkin: From Computer Vision to Computer Graphics
Abstract:
The article is a retrospective on Andy Witkin, who helped merge the fields of computer vision and computer graphics through his work at Schlumberger, Carnegie Mellon University, and Pixar.
Autors: De Rose, Tony;
Appeared in: IEEE Computer Graphics and Applications
Publication date: Jan 2011, volume: 31, issue:1, pages: 102 - 104, c3
Publisher: IEEE
Full litterature document
 
» Angle insensitive enhancement of organic solar cells using metallic gratings
Abstract:
We explore the optical enhancement of organic photovoltaic cells by incorporating a metallic grating as the back contact. We numerically demonstrate a strongly enhanced light absorption exploiting a complex interplay between multiple electromagnetic wave phenomena, among which surface plasmon polariton (SPP) resonances, waveguide mode resonances, Fabry–Perot modes, and scattering. We focus on a triangular grating structure and describe the particular opportunities to obtain a good angular performance. In addition we introduce a novel multiperiodic geometry that incorporates multiple types of SPP resonances. Our triangular structure shows an increased absorption of 15.6% with the AM1.5G spectrum in the 300–800 nm wavelength range. For the multiperiodic grating case a significant further increase to 20.7% is shown.
Autors: Abass, Aimi;Shen, Honghui;Bienstman, Peter;Maes, Bjorn;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 023111 - 023111-7
Publisher: IEEE
Full litterature document
 
» Angular and Shadowing Characteristics of Dense Multipath Components in Indoor Radio Channels
Abstract:
The dense multipath components (DMC) represent the part of the radio channel that cannot be characterized by using the specular components (SC). In this paper, the propagation characteristics of the DMC are analyzed in indoor environments based on extensive channel measurements. The results show that the contribution of the DMC to the total received power can vary as much as between 10% and 95%, being generally higher in non-line-of-sight than in line-of-sight scenarios. However, it was found that the DMC have a well distinguishable structure in the angular domain in all the investigated scenarios and, furthermore, the propagation mechanisms of the SC and DMC have large similarities. In addition, the effect of shadowing objects on the SC and DMC has been investigated.
Autors: Poutanen, J.;Salmi, J.;Haneda, K.;Kolmonen, V.-M.;Vainikainen, P.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2011, volume: 59, issue:1, pages: 245 - 253
Publisher: IEEE
Full litterature document
 
» Angular constraint on light-trapping absorption enhancement in solar cells
Abstract:
Light trapping for solar cells can reduce production cost and improve energy conversion efficiency. Understanding some of the basic theoretical constraints on light trapping is therefore of fundamental importance. Here, we develop a general angular constraint on the absorption enhancement in light trapping. We show that there is an upper limit for the angular integration of absorption enhancement factors. This limit is determined by the number of accessible resonances supported by an absorber.
Autors: Yu, Zongfu;Fan, Shanhui;
Appeared in: Applied Physics Letters
Publication date: Jan 2011, volume: 98, issue:1, pages: 011106 - 011106-3
Publisher: IEEE
Full litterature document
 
» Anisotropic diffusion for noise removal of band pass signals
Abstract:
A noise removal method for band pass signals based on the anisotropic diffusion algorithm originally put forward by Perona and Malik is proposed in this paper. The anisotropic smoothing algorithm proposed here is for band pass signals modulated with a constant carrier frequency. A partial differential equation to smooth band pass noisy signals is derived. The propagator of this differential equation is also analytically calculated in this paper. An appropriate linear operator is then considered here for such band pass signals to form an anisotropic diffusion algorithm. The algorithm proposed here demonstrates better performance for band pass noisy signals containing...
Autors: Sasan, Mahmoodi
Appeared in: Signal Processing
Publication date: Jan 2011
Publisher: Elsevier B.V.
Full litterature document
 
» Anisotropic field-effect hole mobility of liquid crystalline conjugated polymer layers formed on photoaligned polyimide films
Abstract:
We have fabricated organic field-effect transistors (OFETs) with a highly oriented active layer of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-bithiophene] (F8T2), which was formed with the help of a photoaligned polyimide film. Photoalignment is an attractive technique for integrating OFETs with aligned active layers on the same substrate, because of its potential capability of two-dimensional alignment patterning. The F8T2 layer formed on the photoaligned polyimide film showed an absorption dichroic ratio greater than 15 after annealing at 285 °C. Top-gate/bottom-contact-type OFETs with a parylene gate insulating layer exhibited an enhanced hole mobility (0.016 cm2V-1s-1) along the alignment direction of the F8T2 backbone structure and a suppressed one (0.002 cm2V-1s-1) along the perpendicular direction. This result shows that the photoaligned polyimide film is an attractive alignment layer for fabricating and integrating OFETs with aligned active layers. Current-direction-dependent bias stress effect was observed for those OFETs; when the current flowed parallel to the alignment direction of the F8T2 backbone structures, a larger negative threshold voltage shift was observed. This anisotropic bias stress effect was discussed on the basis of a microstructure model of aligned F8T2 films.
Autors: Sakamoto, Kenji;Yasuda, Takeshi;Miki, Kazushi;Chikamatsu, Masayuki;Azumi, Reiko;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 013702 - 013702-7
Publisher: IEEE
Full litterature document
 
» Anisotropic mechanism on distinct transition modes of tip-activated multipolorizaion switching in epitaxial BiFeO3 films
Abstract:
Based on the extended Kittel’s law, an anisotropic mechanism has been developed to investigate the complex multipolarization switching in (001) and (110) epitaxial BiFeO3 films, under a biased-tip field. Switching inhomogeneity and domain wall width evolution have been specifically accounted for. It has been found that distinct switching modes, i.e., the breakdown mode of 71°-switched domain and the activation mode of 180°/109° switching, exist and dominate the switching orders within switching process. Our predicted switching orders show excellent agreements with the existing experimental data and phase-field results. A two-step procedure is also proposed to fabricate single-phase 71° ferroelastic domain array of controllable density using (001) BiFeO3 films, which is favored in practice to significantly enhance the magnetoelectric coupling and photovoltage.
Autors: Shi, Y. P.;Soh, A. K.;Weng, G. J.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:2, pages: 024102 - 024102-6
Publisher: IEEE
Full litterature document
 
» Anisotropic Morphological Filters With Spatially-Variant Structuring Elements Based on Image-Dependent Gradient Fields
Abstract:
This paper deals with the theory and applications of spatially-variant discrete mathematical morphology. We review and formalize the definition of spatially variant dilation/erosion and opening/closing for binary and gray-level images using exclusively the structuring function, without resorting to complement. This theoretical framework allows to build morphological operators whose structuring elements can locally adapt their shape and orientation across the dominant direction of the structures in the image. The shape and orientation of the structuring element at each pixel are extracted from the image under study: the orientation is given by means of a diffusion process of the average square gradient field, which regularizes and extends the orientation information from the edges of the objects to the homogeneous areas of the image; and the shape of the orientated structuring elements can be linear or it can be given by the distance to relevant edges of the objects. The proposed filters are used on binary and gray-level images for enhancement of anisotropic features such as coherent, flow-like structures. Results of spatially-variant erosions/dilations and openings/closings-based filters prove the validity of this theoretical sound and novel approach.
Autors: Verd-Monedero, R.;Angulo, J.;Serra, J.;
Appeared in: IEEE Transactions on Image Processing
Publication date: Jan 2011, volume: 20, issue:1, pages: 200 - 212
Publisher: IEEE
Full litterature document
 
» Anisotropic transport of two-dimensional electron gas modulated by embedded elongated GaSb/GaAs quantum dots
Abstract:
Geometrically anisotropic GaSb/GaAs quantum dots (QDs) that are elongated along the [110] direction are embedded in the vicinity of a modulation-doped AlGaAs/GaAs heterointerface. At 4.2 K, the electron mobilities μ|| and μ, which are parallel and perpendicular to the QD elongation axis, respectively, are systematically investigated as a function of the electron concentration NS by both experimental measurements and theoretical simulations. In the experiments, the mobility ratio μ|| increased with increasing NS. The mobility anisotropy, attributed to the anisotropic scattering potential of the elongated GaSb QDs, is calculated under the theoretical model of a rectangular scattering potential of GaSb QDs.
Autors: Li, Guodong;Jiang, Chao;Zhu, Qinsheng;Sakaki, Hiroyuki;
Appeared in: Applied Physics Letters
Publication date: Jan 2011, volume: 98, issue:3, pages: 032103 - 032103-3
Publisher: IEEE
Full litterature document
 
» Annealing effects on the magnetic dead layer and saturation magnetization in unit structures relevant to a synthetic ferrimagnetic free structure
Abstract:
The changes in the magnetic dead layer (MDL) and saturation magnetization of the CoFeB layers are investigated as a function of the annealing temperature for four different unit structures, that are relevant to the synthetic ferrimagnetic free structure in MgO-based magnetic tunnel junctions. The MDL results for these unit structures are then converted into those for the constituent interfaces of the free structure. Most of the changes in the MDL thickness occur during annealing at a low temperature of 150 °C while those in the saturation magnetization occur at a high annealing temperature of 350 °C. These results for the MDL and saturation magnetization are critically tested by using the synthetic ferrimagnetic free structures with various thickness asymmetries. The observed switching properties of these tested structures are in good agreement with those expected from the results for the MDL and saturation magnetization, confirming the accuracy of the present results. The accuracy of the saturation magnetization is further confirmed by ferromagnetic resonance experiments.
Autors: Jang, Soo Young;You, Chun-Yeol;Lim, S. H.;Lee, S. R.;
Appeared in: Journal of Applied Physics
Publication date: Jan 2011, volume: 109, issue:1, pages: 013901 - 013901-5
Publisher: IEEE
Full litterature document
 
» Annealing-Induced Changes in Electrical Characteristics of Al/Al-Rich Diodes
Abstract:
Al-rich thin films are synthesized by radio-frequency magnetron sputtering, followed by thermal annealing at 500 for different durations to form Al/Al-rich diodes. The annealing causes reactions at the Al-rich interface, leading to an increase in Al concentration in the interface region. As a result, the current conduction of the diode is significantly enhanced, which results in anomalous capacitance–voltage ( ) characteristics. The anomalous behaviors can be eliminated by reconstructing the curve based on a four-element circuit model. The resistance of the Al-rich layer extracted from the reconstruction shows power-law voltage dependence correlated with the current-conduction measurement.
Autors: Liu, Z.;Chen, T. P.;Liu, Y.;Cen, Z. H.;Zhu, S.;Yang, M.;Wong, J. I.;Li, Y. B.;Zhang, S.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Jan 2011, volume: 58, issue:1, pages: 33 - 38
Publisher: IEEE
Full litterature document
 
» Announcing the IEEE Transactions on Plasma Science Special Issue on Spacecraft Charging Technology January 2012
Abstract:
Autors: Lai, S. T.;Cooke, D.;Payan, D.;Hilgers, A.;Cho, M.;Garrett, H.;Ferguson, D.;Roussel, J.-F.;Wheelock, A.;
Appeared in: IEEE Transactions on Plasma Science
Publication date: Jan 2011, volume: 39, issue:1, pages: 628 - 628
Publisher: IEEE
Full litterature document
 
» Antenna Miniaturization Using Slow Wave Enhancement Factor from Loaded Transmission Line Models
Abstract:
Miniaturization of slow wave antennas exploiting the slow wave enhancement factor is presented. The printed antennas are periodically loaded with shunt capacitors to slow down the guided wave in the structures. In this paper, the loaded unit cell of the equivalent transmission line model is utilized to extract the slow wave enhancement factor, the ratio of the loaded to the unloaded propagation constants of the wave in the antennas. From this model, the slow wave enhancement factor of a loaded antenna agrees very well with the miniaturization factor, and therefore load parameters in the circuit model can be readily obtained when a specific size reduction is attempted. This claim was substantiated by demonstrating two small radiators, a high-frequency (HF) slot-loop antenna and a planar inverted F antenna (PIFA), to achieve the desired size reductions. Experimental results show that both of the antennas demonstrate greater than ten-times size reduction from their unloaded counterparts at the expense of the degraded gains and impedance bandwidths. Specifically, the loaded slot loop presents the predicted gain and measured bandwidth on the order of and 0.38% for , respectively. Therefore, a matching network derived from filter design techniques is proposed to increase the antenna bandwidth so that a measured fractional bandwidth of 1.78% is achieved. The slot loop combined with the impedance matching circuit occupies a footprint size of at the operating frequency. On the other hand, the measured radiation gain and bandwidth of the loaded PIFA are reduced to and 0.15% for ${rm VSWR} le 2$, respectively, with a footprint of at the operating frequency.
Autors: Chi, P.-L.;Waterhouse, R.;Itoh, T.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Jan 2011, volume: 59, issue:1, pages: 48 - 57
Publisher: IEEE
Full litterature document
 


Publication archives by date
    2014:   January     February     March     April     May     June     July     August     September     October     November     December    
    2013:   January     February     March     April     May     June     July     August     September     October     November     December    
    2012:   January     February     March     April     May     June     July     August     September     October     November     December    
    2011:   January     February     March     April     May     June     July     August     September     October     November     December    
    2010:   January     February     March     April     May     June     July     August     September     October     November     December    
    2009:   January     February     March     April     May     June     July     August     September     October     November     December