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Electrical and Electronics Engineering publications abstract of: 04-2010 sorted by title, page: 20
» Overview of the 2009 RFIC Symposium [Conference Report]
Abstract:
Autors: Quach, T.;
Appeared in: IEEE Microwave Magazine
Publication date: Apr 2010, volume: 11, issue:2, pages: 92 - 93
Publisher: IEEE
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» Oxygen-atmosphere heat treatment in spin-on doping process for improving the performance of crystalline silicon solar cells
Abstract:
Spin-on doping of phosphorus has been investigated and applied for the emitter fabrication of crystalline Si solar cells. Heat treatment in oxygen atmosphere at relatively low temperature of 550 °C prior to phosphorus diffusion is proved effective for improving solar cell performance, showing a conversion efficiency enhancement of more than 0.2% absolute. Internal quantum efficiency measurements show obvious enhancements at both short and long-wavelength regions. Secondary ion mass spectroscopy and Infrared absorption analysis reveal reduced C impurities after the heat treatment, possibly caused by burning the organic residues in the coated dopant source layer.
Autors: Liu, Zhengxin;Takato, Hidetaka;Togashi, Chiho;Sakata, Isao;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:15, pages: 153503 - 153503-3
Publisher: IEEE
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» P3HT/PCBM Bulk Heterojunction Solar Cells: Impact of Blend Composition and 3D Morphology on Device Performance
Abstract:
The performance of polymer solar cells (PSC) strongly depends on the 3D morphological organization of the donor and acceptor compounds within the bulk heterojunction active layer. The technique of electron tomography is a powerful tool for studying 3D morphology of the layers composed of poly(3-hexylthiophene) (P3HT) and a fullerene derivative ([6,6]-phenyl-C61-butyric acid methyl ester; PCBM), especially to quantify the amount and distribution of fibrillar P3HT nanocrystals throughout the volume of the active layer. In this study, electron tomography is used to characterize P3HT/PCBM layers with different blend compositions, both before and after thermal annealing. The power conversion efficiency of the corresponding PSCs is strongly dependent on the overall crystallinity of P3HT and the way P3HT crystals are distributed throughout the thickness of the active layer.
Autors: Svetlana S. van Bavel, Maik Bärenklau, Gijsbertus de With, Harald Hoppe, Joachim Loos
Appeared in: Advanced Functional Materials
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Packet Error Probability of a Transmit Beamforming System With Imperfect Feedback
Abstract:
Average packet error probability (PEP) is an important error statistic for wireless communication system designers. In this paper, we address the problem of analytically quantifying the effect of channel estimation errors, feedback delay and channel vector quantization on the PEP of transmit beamforming multiple-input-single-output (MISO) systems in a spatially independent slow-fading wireless channel environment. We develop an accurate characterization of estimation errors as well as errors due to feedback delay, and tools relevant for deriving analytical expressions for the PEP. The modeling highlights the distinction between errors that arise due to channel estimation from those that arise due to feedback delay and represents an important departure from past work. Analytical expressions are derived for the PEP with BPSK signaling. The derived approximated closed-form analytical expression is complemented by simulations.
Autors: Isukapalli, Y.;Rao, B. D.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Apr 2010, volume: 58, issue:4, pages: 2298 - 2314
Publisher: IEEE
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» Paper # 8387 - Scintillation particle detection based on microfluidics
Abstract:
A novel type of particle detector based on scintillation, with precise spatial resolution and high radiation hardness, is being studied. It consists of a single microfluidic channel filled with a liquid scintillator and is designed to define an array of scintillating waveguides each independently coupled to a photodetector. Prototype detectors built using an SU-8 epoxy resin have been tested with electrons from a radioactive source. The experimental results show a light yield compatible with the theoretical expectations and confirm the validity of the approach.
Autors: A., Mapelli , B., Gorini , M., Haguenauer , S., Jiguet , G. Lehmann, Miotto , ...
Appeared in: Sensors and Actuators A: Physical
Publication date: Apr 2010
Publisher: Elsevier B.V.
Full litterature document
 
» Parallel Two-Sided Matrix Reduction to Band Bidiagonal Form on Multicore Architectures
Abstract:
The objective of this paper is to extend, in the context of multicore architectures, the concepts of tile algorithms [Buttari et al., 2007] for Cholesky, LU, and QR factorizations to the family of two-sided factorizations. In particular, the bidiagonal reduction of a general, dense matrix is very often used as a preprocessing step for calculating the Singular Value Decomposition. Furthermore, in the Top500 list of June 2008, 98 percent of the fastest parallel systems in the world were based on multicores. This confronts the scientific software community with both a daunting challenge and a unique opportunity. The challenge arises from the disturbing mismatch between the design of systems based on this new chip architecture-hundreds of thousands of nodes, a million or more cores, reduced bandwidth and memory available to cores-and the components of the traditional software stack, such as numerical libraries, on which scientific applications have relied for their accuracy and performance. The many-core trend has even more exacerbated the problem, and it becomes critical to efficiently integrate existing or new numerical linear algebra algorithms suitable for such hardware. By exploiting the concept of tile algorithms in the multicore environment (i.e., high level of parallelism with fine granularity and high-performance data representation combined with a dynamic data-driven execution), the band bidiagonal reduction presented here achieves 94 Gflop/s on a 12,000 ÿ 12,000 matrix with 16 Intel Tigerton 2.4 GHz processors. The main drawback of the tile algorithms approach for the bidiagonal reduction is that the full reduction cannot be obtained in one stage. Other methods have to be considered to further reduce the band matrix to the required form.
Autors: Ltaief, H.;Kurzak, J.;Dongarra, J.;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Apr 2010, volume: 21, issue:4, pages: 417 - 423
Publisher: IEEE
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» Parallel-connected monolithic dye-sensitised solar modules
Abstract:
Light-soaking and high-temperature storage testing of monolithic dye-sensitised solar modules with total area module efficiencies above 5% have been performed. Our experiences from the development of a four-layer monolithic dye-sensitised solar test cell for comparative testing of material components for dye-sensitised solar cells have directed our module development to a novel device design consisting of parallel-connection of individual monolithic cells. The results from the accelerated testing of the modules (total area of 17.0 cm2) with four parallel-connected cells (active area of 3.38 cm2/cell) are equivalent to those obtained for the monolithic single test cells when using identical device components. The successful transfer from cell to module stability is an important milestone in our ambition to develop a low-cost Photovoltaic (PV) technology. Moreover, our results indicate that intensified research and development to define the procedures for relevant accelerated testing of dye-sensitised solar modules is urgently required. Copyright © 2010 John Wiley & Sons, Ltd.
Autors: Henrik Pettersson, Tadeusz Gruszecki, Christine Schnetz, Micha Streit, Yunhua Xu, Licheng Sun, Mikhail Gorlov, Lars Kloo, Gerrit Boschloo, Leif Häggman, Anders Hagfeldt
Appeared in: Progress in Photovoltaics: Research and Applications
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Parallelization of the Scale-Changing Technique in Grid Computing environment for the electronmagnetic simulation of multi-scale structures
Abstract:
A parallel computing approach to run fast and full-wave electromagnetic simulation of complex structures in Grid Computing environment is presented. In this study, we show how Grid Computing improves speed and/or reliability over that provided by a single computer, while typically being much more cost-effective than single computers of comparable speed or reliability. An efficient monolithic (unique) formulation for the electromagnetic modelling of complex (multi-scale) structures, i.e. structures that exhibit multiple metallic patterns whose sizes cover a large range of scales, is used here. This approach, named the Scale-Changing Technique, is based on the cascade of multi-modal Scale-Changing Networks, each network modelling the electromagnetic coupling between two successive scale levels. These networks can be first computed separately, in an adaptive use of Grid Computing architecture nature, and then cascaded for the global electromagnetic simulation. Based on this technique, a fast computer algorithm was developed and tested in the Grid-Computing environment. For illustration purposes, the electromagnetic analysis of multi-scale structures, applied to phase-shifter elements and an example of infinite passive reflectarray, was carried out. The obtained results have confirmed the effectiveness of such an approach compared with sequential computing. This approach shows very good computation performance while keeping the same accuracy. Besides, this method is very promising for optimizing circuit with multiple design parameters to handle and for the global electromagnetic simulation of multi-scale and/or oer-sized structures. Copyright © 2010 John Wiley & Sons, Ltd.
Autors: F. Khalil, C. J. Barrios-Hernandez, A. Rashid, H. Aubert, Y. Denneulin, F. Coccetti, R. Plana
Appeared in: International Journal of Numerical Modelling: Electronic Networks, Devices and Fields
Publication date: Apr 2010
Publisher: Wiley InterScience
Full litterature document
 
» Parameter estimation and comparison of the load models with considering distribution network directly or indirectly
Abstract:
In order to consider the effect of the distribution network on the load modeling, a synthesis load model (SLM) including the power load and the distribution network has been proposed. Using SLM, the accuracy of the load modeling can be improved. A strategy for parameter estimation of the SLM was proposed in this paper. The proposed parameter estimation strategy was based on the combination of the component based and the measurement based load modeling method. During parameter estimation, only the parameters playing very important roles in the dynamics of the load were estimated, while the other parameters playing limited roles...
Autors: Q., Chen , P., Ju , K.Q., Shi , Y., Tang , Z.Y., Shao , ...
Appeared in: International Journal of Electrical Power & Energy Systems
Publication date: Apr 2010
Publisher: Elsevier B.V.
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» Parameters influencing the market value of wind power - a model-based analysis of the Central European power market
Abstract:
In leading European wind power countries wind power generation affects wholesale power prices already today. First investigations indicate that the respective wind power-price relation lowers the market value of wind power relative to the baseload price with increasing penetration. The aim of this paper is to identify parameters that determine this effect based on simulations for the Central European Power Market (CEPM). We model wind power-price interactions and investigate the sensitivity of the market value on a number of wind power and system related parameters. The market value of wind power is sensitive to changes in wind share and variability, wind-demand correlation and the supply characteristics. Results further indicate that for expected wind capacities in 2020 the market value in the CEPM is significantly lower than the baseload price. The market value reducing effect varies among countries and is comparably low for wind power portfolios whose generation is weakly correlated with the overall wind power generation in the respective power market. Hence with rising wind shares it will become increasingly important to take this effect into account when assessing the economics of wind power projects. Future trends in the CEPM that may positively influence the market value are increasing electricity demand, fuel and CO2 prices, a better geographic distribution of onshore wind within the CEPM and an increasing utilization of offshore wind. Copyright © 2010 John Wiley & Sons, Ltd.
Autors: Carlo Obersteiner, Marcelo Saguan
Appeared in: European Transactions on Electrical Power
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Parametric history analysis of resonance problems via step-by-step eigenvalue perturbation technique
Abstract:
The Galerkin procedure to solve Maxwell¿s equations associated with a perturbed system approximately, yields a generalised eigenvalue perturbation problem. Instead of solving the generalised eigenvalue problem, perturbed eigenvalues and eigenvectors can be approximated in terms of unperturbed ones. Although solving the perturbed eigenvalue problem can be computationally attractive, the small perturbation requirement may be quite restrictive. This restriction can be relaxed using iterative perturbation techniques in which the problem is divided into small perturbation steps, and then each subsequent problem is solved depending on the solutions of the previous step. Besides, the step-by-step iterative solution also provides a parametric history of the system behaviour. In this study, the parametric history analysis of electromagnetic resonant structures has been accomplished using the step-by-step eigenvalue perturbation method. To illustrate the proposed method, the reanalysis of perturbation of a cylindrical cavity with a dielectric sample has been examined. The results obtained using the parametric history analysis are compared with the theoretical, the experimental and the results of the classical perturbation approach.
Autors: Gunel, S.;Zoral, E.Y.;
Appeared in: IET Microwaves, Antennas & Propagation
Publication date: Apr 2010, volume: 4, issue:4, pages: 466 - 476
Publisher: IEEE
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» Partial Least Squares: A Method to Estimate Efficient Channels for the Ideal Observers
Abstract:
We advocate a task-based approach to the assessment of image quality using the Bayesian ideal observer. The Bayesian ideal observer provides an absolute upper bound for performance estimates. However, using the full images as inputs to the observer is often infeasible due to their high dimensionality. A practical alternative is to reduce the dimensionality of the images by applying channels, while approximating the ideal observer by an observer constrained to the channels. Laguerre-Gauss (LG) channels and those derived from the singular value decomposition (SVD) of the system operator have previously been used with the Bayesian ideal observer. However, the channelized observer with LG and SVD channels was only applicable in situations with a rotationally symmetric signal or known system operator, respectively. We investigate a method using partial least squares (PLS) to compute efficient channels directly from the images, without prior knowledge of the background, signal, or system operator. Results show that the channelized ideal observer with PLS channels approximates the nonchannelized observer, and does so with fewer channels than the observer with either LG or SVD channels. The images are reduced from 4096 pixel values to 20 channel outputs, yet preserve the salient information. Furthermore, PLS reveals that the background image statistics provide important information necessary in signal-detection tasks. Overall, PLS is shown to be a viable channel generation method and may be applicable to real-life situations.
Autors: Witten, J. M.;Park, S.;Myers, K. J.;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: Apr 2010, volume: 29, issue:4, pages: 1050 - 1058
Publisher: IEEE
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» Partial-arc and spark models of the flashover of lightly polluted insulators
Abstract:
The established model of the flashover of an insulator, whose surface is covered with a moist, conducting layer of pollution, envisages that it develops from the formation and bridging of a dry band by a partial-arc pre-discharge. This pre-discharge is assumed to possess arc characteristics, so that the electric field across the dry band will fall as the partial arc current increases. Observations of insulators which are only lightly polluted, however, show that pre-discharges are of low luminosity and rich in ultraviolet, and resemble the spark leader inception and extension sequence in air gaps. This is because the current limitation by low values of surface-layer conductance can inhibit the transition to an arc at the pre-discharge stage. An alternative model using simplified voltage-current equations is developed to represent these spark properties rather than an arc characteristic. The predictions of the partial-arc model and this new approach are both tested here, using published experimental data from light-pollution fog tests in the authors¿ laboratory. For this purpose, the partial-arc theory is further developed in order to reveal its implied prediction for the increase of pre-discharge length with applied voltage before flashover. A corresponding relationship is obtained for the increase of spark leader length using the new model. It is found that for light pollution, the dry-band spark model better represents the test data than the partial-arc model. Consequent predictions are made for the variation of flashover voltage with pollution severity in this regime, which may account for anomalous insulation failures.
Autors: Waters, R. T.;Haddad, A.;Griffiths, H.;Harid, N.;Sarkar, P.;
Appeared in: IEEE Transactions on Dielectrics and Electrical Insulation
Publication date: Apr 2010, volume: 17, issue:2, pages: 417 - 424
Publisher: IEEE
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» Partial-Matching Technique in a Mixed-Mode BIST Environment
Abstract:
A mixed-mode built-in self-test (BIST) approach that deploys two new techniques is presented in this paper. Partial pattern matching allows the reduction of the number of patterns used for detecting random-pattern-resistant faults without relying on fault simulation. A multiple-control sequence is used to guide the linear feedback shift register (LFSR) to generate these patterns at application time. The advantages of this method include the reduction of the test data volume, the shortening of the test application time, and its reusability for logic cores on a system-on-chip (SOC).
Autors: Reungpeerakul, T.;Kay, D.;Mourad, S.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Apr 2010, volume: 59, issue:4, pages: 970 - 977
Publisher: IEEE
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» Particle size reduction: A way to enhanced dielectric properties of magnetocapacitive La2/3Ca1/3MnO3
Abstract:
We report the optimization of the dielectric properties of La2/3Ca1/3MnO3. This is achieved by synthesizing this material with small particle size, strategy that reduces the conductivity of the sample and its dielectric losses, while retaining a reasonably high dielectric permittivity and a good magnetocapacitive response. In order to further improve the properties of these nanoparticles, we have also prepared core-shell composites La2/3Ca1/3MnO3@SiO2 but in this case the magnetocapacitive effect is strongly reduced.
Autors: Yanez-Vilar, S.;Mira, J.;Sanchez-Andujar, M.;Castro-Garcia, S.;Fondado, A.;Rivas, J.;Senaris-Rodriguez, M. A.;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:16, pages: 162904 - 162904-3
Publisher: IEEE
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» Passive Filter Planning Using Simultaneous Perturbation Stochastic Approximation
Abstract:
Power quality in distribution systems may deteriorate due to an increase in nonlinear loads. The single-tuned passive filter is considered as one of the most economical and efficient approaches to reduce the harmonics. This paper presents a new method for studying passive filter planning using Simultaneous Perturbation Stochastic Approximation (SPSA). SPSA is an easily implemented and highly efficient gradient approximation that relies on two values of the objective function. The number (integer) of capacitor bank and tuned resonance frequency (real number) of the single-tuned passive filter are considered as unknowns. Simulation results from an 18-bus system with multiple nonlinear loads show the applicability of the proposed method. It can be found that the proposed method can obtain the optimal solution in a very short CPU time.
Autors: Hong, Y.-Y.;Chiu, C.-S.;
Appeared in: IEEE Transactions on Power Delivery
Publication date: Apr 2010, volume: 25, issue:2, pages: 939 - 946
Publisher: IEEE
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» Passive magnetic field cancellation device by multiple high-Tc superconducting coils
Abstract:
A passive magnetic field cancellation device (PMFCD) is designed. The PMFCD could automatically cancel the field as an active cancellation system did; however it requires no power sources and feedback systems. The capability of the PMFCD is based on the principle that a closed loop can resist flux variation and keep the flux constant inside. The closed loop in the PMFCD is formed by connecting two pairs of high temperature superconductor Helmholtz coils with different radii in series. More important thing is that the ratio of the radius and the turn number between the coils has to satisfy a number of conditions, with which 100% cancellation can be reached. Theoretical methods to obtain the turn number ratio and radius ratio are the major part of the paper. Numerical simulation was followed, aiming to evaluate field distribution under a cancellation state and correct the theoretical values.
Autors: Gu, C.;Zou, S.;Han, Z.;Qu, T.-M.;
Appeared in: Review of Scientific Instruments
Publication date: Apr 2010, volume: 81, issue:4, pages: 045101 - 045101-5
Publisher: IEEE
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» Passive sensor evaluation for unmanned ground vehicle mud detection
Abstract:
Detecting mud hazards is a significant challenge to unmanned ground vehicle (UGV) autonomous off-road navigation. A military UGV stuck in a body of mud during a mission may need to be sacrificed or rescued, both unattractive options. The Jet Propulsion Laboratory is currently developing a daytime mud detection capability under the U.S. Army Research Laboratory Robotics Collaborative Technology Alliances program using UGV-mounted sensors. To perform robust mud detection under all conditions, we expect that multiple sensors will be necessary. A passive mud detection solution is desirable to meet future combat system requirements. To characterize the advantages and disadvantages of candidate passive sensors, outdoor data collections have been performed on wet and dry soil using visible, multispectral (including near-infrared), shortwave infrared, midwave infrared, long-wave infrared, polarization, and stereo sensors. In this paper, we examine the cues for mud detection that each of these sensors provide, along with their deficiencies, and we illustrate localizing detected mud in a world model that can used by a UGV to plan safe paths. We mostly limit our examination to mud detection during the daytime under ideal conditions: isolated wet soil surrounded by dry soil during nominal weather, i.e., no precipitation, calm wind, and near-average temperatures. © 2010 Wiley Periodicals, Inc.
Autors: A. L. Rankin, L. H. Matthies
Appeared in: Journal of Field Robotics
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Passive switching scheme for two-way quantum key distribution setups
Abstract:
A simple design for Bob in two-way quantum key distribution schemes that employs only passive linear optical components to perform the necessary switching operations is presented. It is shown that, for some specific protocols and/or practical qubit implementations, the losses in Bob¿s station can be made negligible, hence increasing the maximum distance for secret key generation.
Autors: Temporao, G.P.;
Appeared in: Electronics Letters
Publication date: Apr 2010, volume: 46, issue:7, pages: 512 - 513
Publisher: IEEE
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» Passive-Set-Position-Modulation Framework for Interactive Robotic Systems
Abstract:
In this paper, we propose a novel framework, passive set-position modulation (PSPM), which enables us to connect a (continuous-time) robot’s position to a sequence of slowly updating/sparse (discrete-time) set-position signal via the simple (yet frequently used in practice) spring coupling with damping injection, while enforcing passivity of the closed-loop robotic system. The PSPM modulates the original set-position signal in such a way that the modulated signal is as close to the original signal as possible (i.e., maximum information recovery for better performance), yet only to the extent permissible by the available energy in the system (i.e., passivity constraints). We present its algorithm and theoretically show its passivity and performance. We also show how this PSPM can be applied for two applications, with some experimental results: Internet teleoperation with varying delay and packet loss; and haptics with slow and variable-rate data update.
Autors: Lee, D.;Huang, K.;
Appeared in: IEEE Transactions on Robotics
Publication date: Apr 2010, volume: 26, issue:2, pages: 354 - 369
Publisher: IEEE
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» Patch-Based Background Initialization in Heavily Cluttered Video
Abstract:
In this paper, we propose a patch-based technique for robust background initialization that exploits both spatial and temporal consistency of the static background. The proposed technique is able to cope with heavy clutter, i.e, foreground objects that stand still for a considerable portion of time. First, the sequence is subdivided in patches that are clustered along the time-line in order to narrow down the number of background candidates. Then, a tessellation is grown incrementally by selecting at each step the best continuation of the current background. The method rests on sound principles in all its stages and only few, intelligible parameters are needed. Experimental results show that the proposed algorithm is effective and compares favorably with existing techniques.
Autors: Colombari, A.;Fusiello, A.;
Appeared in: IEEE Transactions on Image Processing
Publication date: Apr 2010, volume: 19, issue:4, pages: 926 - 933
Publisher: IEEE
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» Pathological representation of the two-output CCII and ICCII family and application
Abstract:
The pathological mirror and nullor representation of the two-output current conveyor family is given. New pathological mirror and nullor representations of the two-output current conveyor family are given and compared with the corresponding nullator norator resistors' realizations. Simplified representations of the two-output current conveyors based on using two single-output current conveyors are given. Two examples are given, the first example demonstrates the importance of the pathological representation in the generation of a family of 16 oscillators from a two-output current conveyor-based current mode oscillator. A second example of a current mode low-pass filter using two single-output inverting current conveyors is considered. Its simplified modeling using a single balanced output inverting current conveyor is compared with the original current mode filter and the simulation results are given. Copyright © 2010 John Wiley & Sons, Ltd.
Autors: Ahmed M. Soliman
Appeared in: International Journal of Circuit Theory and Applications
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Patient-specific simulation for endovascular procedures: qualitative evaluation of the development process
Abstract:
Recent advancements in simulation permit patient-specific rehearsal of carotid artery stenting procedures. This study evaluates the feasibility of transferring patient-specific CT data into the simulator, creating a 3D reconstruction and performing a rehearsal. The face validity of the model was assessed.By thematic analysis of qualitative data, an algorithm was generated, focusing on simulation set-up, time of data transfer, software/compatibility issues and problem-solving strategies. The face validity of the simulated case was evaluated by 15 expert interventionalists: realism (median 4/5), training potential (median 4/5) and pre-procedure rehearsal potential for challenging CAS cases (median 4/5) were rated highly.Setting up a procedure rehearsal is feasible and reproducible for different patients in different hospital settings without major software compatibility issues. The time to create a 3D reconstruction of patient-specific CT data is a major factor in the total time necessary to set up a rehearsal. The face validity is highly rated by experts. Copyright © 2010 John Wiley & Sons, Ltd.
Autors: W. I. M. Willaert, R. Aggarwal, D. F. Nestel, P. A. Gaines, F. E. Vermassen, A. W. Darzi, N. J. Cheshire, (on behalf of the European Virtual Reality Endovascular Research Team, EVEResT)
Appeared in: The International Journal of Medical Robotics and Computer Assisted Surgery
Publication date: Apr 2010
Publisher: Wiley InterScience
Full litterature document
 
» Patterns in Effective Distributed Software Development
Abstract:
As with many other industries today, software development must increasingly adapt to teams whose members work together but are geographically distributed. Many factors have contributed to this rise in distributed software development (DSD), including companies' desires to leverage skilled resources wherever they can be found and to reduce costs by working in different labor markets. Its increasing popularity has led to diverse industrial experience, which has in turn led to some best practices and an initial body of knowledge.
Autors: Prikladnicki, R.;Audy, J.L.N.;Shull, F.;
Appeared in: IEEE Software
Publication date: Apr 2010, volume: 27, issue:2, pages: 12 - 15
Publisher: IEEE
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» Peaceful Coexistence: Agile Developer Perspectives on Software Architecture
Abstract:
A study of the relationship between agile methods and software architecture surveyed 72 IBM software developers. Results suggest that the two approaches are compatible. In particular, agile developers perceived architectural principles as important and supportive to agile values, rather than contrasting or neutral to them. This positive perception of software architectural principles and practice bodes well for future efforts to integrate agile and architecture practices.
Autors: Falessi, D.;Cantone, G.;Sarcia', S.A.;Calavaro, G.;Subiaco, P.;D'Amore, C.;
Appeared in: IEEE Software
Publication date: Apr 2010, volume: 27, issue:2, pages: 23 - 25
Publisher: IEEE
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» Peer-to-Peer 3D Streaming
Abstract:
Virtual worlds have become very popular in recent years, with trends toward larger worlds and more user-generated content. The growth of 3D content in virtual worlds will make real-time content streaming (or 3D streaming) increasingly attractive for developers. To meet the demands of a large user base while lowering costs, peer-to-peer (P2P) content delivery holds the promise for a paradigm shift in how future virtual worlds will be deployed and used. The authors define both the problem and solution spaces for P2P 3D streaming — by outlining its requirements and challenges — and categorize existing proposals.
Autors: Hu, Shun-Yun;Jiang, Jehn-Ruey;Chen, Bing-Yu;
Appeared in: IEEE Internet Computing
Publication date: Apr 2010, volume: 14, issue:2, pages: 54 - 61
Publisher: IEEE
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» Penalized Preimage Learning in Kernel Principal Component Analysis
Abstract:
Pub DtlFinding the preimage of a feature vector in kernel principal component analysis (KPCA) is of crucial importance when KPCA is applied in some applications such as image preprocessing. Since the exact preimage of a feature vector in the kernel feature space, normally, does not exist in the input data space, an approximate preimage is learned and encouraging results have been reported in the last few years. However, it is still difficult to find a “good” estimation of preimage. As estimation of preimage in kernel methods is ill-posed, how to guide the preimage learning for a better estimation is important and still an open problem. To address this problem, a penalized strategy is developed in this paper, where some penalization terms are used to guide the preimage learning process. To develop an efficient penalized technique, we first propose a two-step general framework, in which a preimage is directly modeled by weighted combination of the observed samples and the weights are learned by some optimization function subject to certain constraints. Compared to existing techniques, this would also give advantages in directly turning preimage learning into the optimization of the combination weights. Under this framework, a penalized methodology is developed by integrating two types of penalizations. First, to ensure learning a well-defined preimage, of which each entry is not out of data range, convexity constraint is imposed for learning the combination weights. More insight effects of the convexity constraint are also explored. Second, a penalized function is integrated as part of the optimization function to guide the preimage learning process. Particularly, the weakly supervised penalty is proposed, discussed, and extensively evaluated along with Laplacian penalty and ridge penalty. It could be further interpreted that the learned preimage can preserve some kind of pointwise conditional mutual information. Finally, KPCA with preimage - learning is applied on face image data sets in the aspects of facial expression normalization, face image denoising, recovery of missing parts from occlusion, and illumination normalization. Experimental results show that the proposed preimage learning algorithm obtains lower mean square error (MSE) and better visual quality of reconstructed images.
Autors: Zheng, W.-S.;Lai, J.;Yuen, P. C.;
Appeared in: IEEE Transactions on Neural Networks
Publication date: Apr 2010, volume: 21, issue:4, pages: 551 - 570
Publisher: IEEE
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» Penetration behaviour of individual hydrophilic particle at a gas-liquid interface
Abstract:
The penetration behaviour of a hydrophilic particle impacting on a gas-liquid interface was studied both experimentally and mathematically. The aim of this study was to determine the critical impact velocity below which a falling hydrophilic particle would remain on a horizontal liquid surface. A model to predict the critical velocity has been developed based on energy balance of both the particle and liquid volume in the vicinity of the impact zone. The model also includes the effect of hydrophobicitiy (contact angle) of the particle as well as the change in potential energy of the impacted liquid. Experiments were performed using...
Autors: D., Liu , Q., He , G.M., Evans
Appeared in: Advanced Powder Technology
Publication date: Apr 2010
Publisher: Elsevier B.V.
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» Perceptual Image Hashing Based on Virtual Watermark Detection
Abstract:
This paper proposes a new robust and secure perceptual image hashing technique based on virtual watermark detection. The idea is justified by the fact that the watermark detector responds similarly to perceptually close images using a non embedded watermark. The hash values are extracted in binary form with a perfect control over the probability distribution of the hash bits. Moreover, a key is used to generate pseudo-random noise whose real values contribute to the randomness of the feature vector with a significantly increased uncertainty of the adversary, measured by mutual information, in comparison with linear correlation. Experimentally, the proposed technique has been shown to outperform related state-of-the art techniques recently proposed in the literature in terms of robustness with respect to image processing manipulations and geometric attacks.
Autors: Khelifi, F.;Jiang, J.;
Appeared in: IEEE Transactions on Image Processing
Publication date: Apr 2010, volume: 19, issue:4, pages: 981 - 994
Publisher: IEEE
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» Perceptual improvement of Wiener filtering employing a post-filter
Abstract:
A major drawback of many speech enhancement methods in speech applications is the generation of an annoying residual noise with musical character. Although the Wiener filter introduces less musical noise than spectral subtraction methods, such noise, however, exists and is perceptually annoying to the listener. A potential solution to this artifact is the incorporation of a psychoacoustic model in the suppression filter design. In this paper a frequency domain optimal linear estimator with perceptual post-filtering is proposed, which incorporates the masking properties of the human hearing system to render the residual noise distortion inaudible. Proposed post-processing presents a modified way...
Autors: Md. Jahangir, Alam , Douglas, O'Shaughnessy
Appeared in: Digital Signal Processing
Publication date: Apr 2010
Publisher: Elsevier B.V.
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» Perfectly Complementary Relay Design for Digital Logic Applications
Abstract:
A dual-ended (“seesaw”) relay design is proposed for ultralow-power digital logic applications. Fabricated seesaw relays demonstrate a perfectly complementary switching behavior that is symmetric about , with extremely steep switching behavior ( 0.1 mV/dec) and low on -state resistance . The perfectly complementary and symmetric operation provides for maximum operating voltage margin and minimal crowbar current, as evidenced by an abrupt inverter voltage transfer characteristic.
Autors: Jeon, J.;Pott, V.;Kam, H.;Nathanael, R.;Alon, E.;Liu, T.-J. K.;
Appeared in: IEEE Electron Device Letters
Publication date: Apr 2010, volume: 31, issue:4, pages: 371 - 373
Publisher: IEEE
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» Performance analysis and modelling of single-step power control in finite state Markov channel under different feedback channels
Abstract:
We investigate a commonly used power control scheme called single-step power control (SSPC) in finite state Markov channel (FSMC). The performance of SSPC is highly affected by two major factors, the power control error (PCE) and the imperfect feedback of the SSPC commands. In the first part of this work, we aim at modelling the behavior of PCE in FSMC. Based on the proposed PCE model, BER and PER performance are evaluated. Simulation results have shown the validity of the proposed PCE model, derived PER and BER in this work. In the second part of this work, SSPC models under different scenarios are established in order to understand the impact of the imperfect feedback on SSPC commands and to obtain the interactions between SSPC and FSMC. We consider four scenarios, perfect feedback, command error, command loss and command delay. The associated transitional probabilities of each scenario are given. Extensive simulation has shown the accuracy of the proposed SSPC models in these four scenarios.
Autors: Chang, Min-Kuan;Lee, Shi-Yong;Chien, Chien-Hao;Kuo, Chih-Hung;
Appeared in: IEEE Transactions on Communications
Publication date: Apr 2010, volume: 58, issue:4, pages: 1280 - 1290
Publisher: IEEE
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» Performance analysis of distributed transmission schemes in cooperative random networks
Abstract:
In this paper, two distributed transmission schemes, namely Distributed Transmitter Maximal Ratio Combining (DTxMRC) and Distributed Space Time Block Coding (D-STBC) are analysed. The array and diversity gain inherent to the underlying Multiple Input Multiple Output (MIMO) technique are studied, both under independent and correlated fading scenario. It is shown that D-TxMRC is capable of achieving high array gain at the expense of complexity, while only limited array gain is attained using D-STBC scheme. As far as diversity gain is concerned, both schemes achieve full diversity in the order of total number of cooperating nodes under independent fading. The overall performance of the schemes under random network scenario is analysed using average outage probability as a performance metric. The averaging encompasses channel variation as well as network dependent parameters. Effects of different network parameters towards system performance are also analysed. Finally, the performance of cooperative schemes in a more practical network with regular node placements are also studied.
Autors: Kurniawan, E.;Madhukumar, A.S.;Chin, F.;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Apr 2010, volume: 9, issue:4, pages: 1390 - 1401
Publisher: IEEE
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» Performance analysis of fiber fault PON monitoring using optical coding: SNR, SNIR, and false-alarm probability
Abstract:
We evaluate the theoretical performance of recently proposed optical coding (OC) technology for fiber fault monitoring of a PON through the signal-to-noise ratio (SNR), the signal-to-noise-plus-interference ratio (SNIR), and the falsealarm probability. First, we develop a mathematical model and expressions for the detected monitoring signals considering a square law detector and using realistic parameters. Second, we address the effect of the transmitted pulse power, network size and light source coherence on the performance of both one-dimensional (1D) and two-dimensional (2D) OC monitoring systems. We show that the transmitted pulse width can be optimized to trade-off the interference and the detection noises. We give simple analytic equations for this optimal pulse width as a function of network parameters. Both 1D and 2D coding schemes are considered. We find that, under perfect dispersion compensation, an incoherent source performs better than lasers for 1D coding. In addition, 2D coding using lasers offer very good performance and supports networks up to 128 customers with SNIR¿10dB; a promising candidate for future high capacity PON. Finally, we apply Neyman-Pearson testing to the receiver of our monitoring system and investigate how coding and network size affect the operational expenses (OPEX) of our monitoring system.
Autors: Rad, M.M.;Fathallah, H.A.;Rusch, L.A.;
Appeared in: IEEE Transactions on Communications
Publication date: Apr 2010, volume: 58, issue:4, pages: 1182 - 1192
Publisher: IEEE
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» Performance analysis of IEEE 802.11e enhanced distributed channel access
Abstract:
Most of the recent analytical studies for IEEE802.11e quality of service (QoS)-aware enhanced distributed coordination function require a large degree of complexity that are difficult to apply to a wide range of parameter settings for the evaluation of service differentiation mechanisms supported in enhanced distributed channel access (EDCA), including the contention window (CW) and arbitrary inter-frame space (AIFS) mechanisms. The authors propose a novel analytical model to analyse the throughput of EDCA with AIFS and CW differentiation schemes. The model is simplified by decomposing the problem into two easily solved Markov chains that can jointly be solved by numerical method. The authors present simulation and analytical results over a broad range of system parameters to demonstrate the accuracy of the proposed model. Compared to the previous models, our model is simple to implement and can be applied to a general configuration circumstances for the evaluation of EDCA. The results are valuable to facilitate proper design of parameters in 802.11e EDCA for the QoS support required by specific applications.
Autors: Peng, F.;Peng, B.;Qian, D.;
Appeared in: IET Communications
Publication date: Apr 2010, volume: 4, issue:6, pages: 728 - 738
Publisher: IEEE
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» Performance analysis of LDPC codes with selection diversity combining over identical and non-identical rayleigh fading channels
Abstract:
Selection diversity combining employed in conjunction with low-density parity-check codes is able to mitigate the effects of fading. The closed-form bit-error rate expressions of this scheme over independent and non-identically distributed and independent and identically distributed flat Rayleigh fading channels are derived using the extrinsic information transfer chart and Gaussian approximation. The derived expressions are compared with simulation results as well as the Eb / N0 threshold using density evolution (DE). They are in good agreement with simulation results and have the advantage of reduced computational complexity over DE.
Autors: Tan, B.S.;Li, K.H.;Teh, K.C.;
Appeared in: IEEE Communications Letters
Publication date: Apr 2010, volume: 14, issue:4, pages: 333 - 335
Publisher: IEEE
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» Performance analysis of wireless hybrid-ARQ systems with delay-sensitive traffic
Abstract:
The design of wireless communication schemes tailored to real-time traffic requires an analysis framework that goes beyond the traditional criterion of data throughput. This work considers an approach that relates physical system parameters to the queueing performance of wireless links. The potential benefits of multi-rate techniques such as hybrid-ARQ are assessed in the context of delay-sensitive traffic using large deviations. A continuous-time Markov channel model is employed to partition the instantaneous data-rate received at the destination into a finite number of states, each representing a mode of operation of the hybrid-ARQ scheme. The proposed methodology accounts for the correlation of the wireless channel across time, which is computed in terms of level-crossing rates. The tail asymptote governing buffer overflow probabilities at the transmitter is then used to provide a measure of overall performance. This approach leads to a characterization of the effective capacity of the system which, in turn, is applied to quantify the performance advantages of hybrid-ARQ over traditional schemes.
Autors: Gunaseelan, Nirmal;Liu, Lingjia;Chamberland, Jean-Francois;Huff, Gregory H.;
Appeared in: IEEE Transactions on Communications
Publication date: Apr 2010, volume: 58, issue:4, pages: 1262 - 1272
Publisher: IEEE
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» Performance Comparisons Among Radial-Flux, Multistage Axial-Flux, and Three-Phase Transverse-Flux PM Machines for Downhole Applications
Abstract:
The aim of this paper is to provide performance comparisons among conventional radial-flux, multistage axial-flux, and three-phase transverse-flux permanent-magnet machines for downhole applications where the outer diameters are limited by well sizes, but the axial lengths can be relatively long. The comparison procedure is based on a high ambient temperature of 150 , a small outer diameter of 100 mm, a current density of 4 , an electrical loading of 20 kA/m, and a constant speed of 1000 r/min, with their output torques being from several newton meters to 105 and power up to 18 kVA. Three machine prototypes are chosen and optimized individually in terms of maximum torque density on the basis of some common constraints. The comparisons are focused on the torque density, machine efficiency, and power factor with respect to different pole numbers and axial lengths. For a specific downhole application without an external cooling system, the obtained results provide an indication of machines best suited with respect to performance and size.
Autors: Chen, A.;Nilssen, R.;Nysveen, A.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Apr 2010, volume: 46, issue:2, pages: 779 - 789
Publisher: IEEE
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» Performance improvement of AlGaN/GaN HEMTs using two-step silicon nitride passivation
Abstract:
We report fabrication of AlGaN/GaN high electron mobility transistor (HEMT) with improved DC, high frequency and microwave power performances by employing a two-step passivation approach. A pretreated AlGaN surface is provided by dry etching n+-GaN cap layer and RTA annealing ohmic contacts right before Si3N4 passivant is deposited. No additional process step is associated with the surface preparation for the passivation process. Pulsed I-V characteristics show that the proposed passivation process successfully eliminates trapping effect at Si3N4 and AlGaN interface and is considered to be the important factor for the performance enhancement. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1614-1619, 2010; DOI 10.1002/mop.25266
Autors: Heng-Kuang Lin, Hsiang-Lin Yu, F.-H. Huang
Appeared in: Microwave and Optical Technology Letters
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Performance Metrics for Single-Photon Laser Ranging
Abstract:
Airborne laser swath mapping systems collect thousands of range measurements per second, enabling high-resolution surface mapping. Low-signal-to-noise-ratio (LSNR) detection techniques allow for implementation of light detection and range (LIDAR) instrumentation aboard platforms with stringent power, size, and weight restrictions. The University of Florida has developed the coastal area tactical-mapping system, which is a prototype LSNR LIDAR system that is capable of single-photon laser ranging. Laser pulses of 532 nm, 3.5 , and 480 ps are transmitted at 8 kHz, with the outgoing footprint split into a 10 10 array of elements. Backscattered photons are imaged back onto separate anodes of a multistop microchannel plate photomultiplier tube. A 2-GHz event timer processes returns over the array. Ranges for known targets are accumulated for repeated laser shots, and statistical analysis is applied to evaluate performance metrics that are related to minimum separation distance, bathymetric mapping depth, and atmospheric scattering. An LSNR detection paradigm based on Poisson statistics has enabled topographic target detection and shallow-water bathymetry. Quantitative results are used to draw conclusions about feature detection in topographic and bathymetric mapping scenarios.
Autors: Shrestha, K. Y.;Slatton, K. C.;Carter, W. E.;Cossio, T. K.;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Apr 2010, volume: 7, issue:2, pages: 338 - 342
Publisher: IEEE
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» Performance of Common-Mode Chokes
Abstract:
A low-cost method for experimental investigation of common-mode chokes for reducing high-frequency motor ground-currents of inverter-based drive systems of several hundred kW is presented. It provides a powerful tool during the design stage of such chokes to verify their predicted performance. The method draws from the mainly capacitive behavior of machines at very high frequencies. Results of experimental tests for drives with peak ground-current amplitudes of more than 60 Amperes, carried out on a 4 kW test-bed, are presented. They confirm the feasibility of such tests as well as the capability of small, inexpensive, single-turn chokes to effectively reduce the ground-current.
Autors: Muetze, A.;Bee See Heng;
Appeared in: IEEE Industry Applications Magazine
Publication date: Apr 2010, volume: 16, issue:2, pages: 31 - 38
Publisher: IEEE
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» Performance of Flip-Chip Thin-Film GaN Light-Emitting Diodes With and Without Patterned Sapphires
Abstract:
We report on improved device performance of flip-chip (FC) GaN-based light-emitting diodes (LEDs) by combining patterned sapphire substrate (PSS) and thin-film techniques. It was found that an FC LED grown on a conventional planar sapphire exhibits a power enhancement factor of only 36.3% after the thin-film processes of substrate removal and surface roughening. In contrast, the as-fabricated FC LED grown on a PSS showed a power enhancement factor of up to 62.3% without any postprocess as compared with the light output power of an original conventional FC LED. Further intensity improvement to 74.4% could be achieved for the FC LED/PSS sample with the thin-film processes.
Autors: Horng, R.-H.;Hu, H.-L.;Chu, M.-T.;Tsai, Y.-L.;Tsai, Y.-J.;Hsu, C.-P.;Wuu, D.-S.;
Appeared in: IEEE Photonics Technology Letters
Publication date: Apr 2010, volume: 22, issue:8, pages: 550 - 552
Publisher: IEEE
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» Performance of hybrid-ARQ in block-fading channels: A fixed outage probability analysis
Abstract:
This paper studies the performance of hybrid-ARQ (automatic repeat request) in Rayleigh block-fading channels. The long-term average transmitted rate is analyzed in a fastfading scenario where the transmitter only has knowledge of channel statistics, and, consistent with contemporary wireless systems, rate adaptation is performed such that a target outage probability (after a maximum number of H-ARQ rounds) is maintained. H-ARQ allows for early termination once decoding is possible, and thus is a coarse, and implicit, mechanism for rate adaptation to the instantaneous channel quality. Although the rate with H-ARQ is not as large as the ergodic capacity, which is achievable with rate adaptation to the instantaneous channel conditions, even a few rounds of H-ARQ make the gap to ergodic capacity reasonably small for operating points of interest. Furthermore, the rate with H-ARQ provides a significant advantage compared to systems that do not use H-ARQ and only adapt rate based on the channel statistics.
Autors: Wu, P.;Jindal, N.;
Appeared in: IEEE Transactions on Communications
Publication date: Apr 2010, volume: 58, issue:4, pages: 1129 - 1141
Publisher: IEEE
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» Performance of Instantaneous Frequency Rate Estimation Using High-Order Phase Function
Abstract:
The high-order phase function (HPF) is a useful tool to estimate the instantaneous frequency rate (IFR) of a signal with a polynomial phase. In this paper, the asymptotic bias and variance of the IFR estimate using the HPF are derived in closed-forms for the polynomial phase signal with an arbitrary order. The Cramér-Rao bounds (CRBs) for IFR estimation, in both exact and asymptotic forms, are obtained and compared with the asymptotic mean-square error (MSE) of the HPF-based IFR estimator. Simulations are provided to verify our theoretical results.
Autors: Wang, P.;Li, H.;Djurovic, I.;Himed, B.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Apr 2010, volume: 58, issue:4, pages: 2415 - 2421
Publisher: IEEE
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» Performance of silicone rubber in DC inclined plane tracking tests
Abstract:
The inclined plane tracking and erosion test IEC-60587 is not specified for DC testing. A dc test has been developed from the current ac standard and three formulations of silicone rubber tested. These materials were tested under three voltage levels (2.3, 2.7 and 3.2 kV) for both polarities. Positive dc tests have the highest average and peak leakage current and exhibit a higher degree of surface damage. The observed surface degradation pattern is heavily dependant on polarity. Consistently higher levels of erosion have been observed in the higher voltage positive cases. Erosion of the surface always starts at the bottom electrode, and spreads toward the top electrode. Puncturing of the 6 mm thick samples or deep erosion over more than half the distance between electrodes has only been observed under 2.7 and 3.2 kV positive polarity tests. Results have been analysed using a variety of leakage current analysis techniques going beyond the criteria specified in the original ac standard. The low-frequency behaviour of the leakage current was monitored using a 15 sample per second current recorder. The leakage current magnitude is investigated in a case study and is shown to follow a normal distribution. Reversing the polarity of tests shows the leakage current seen in a test is largely independent of the surface degradation pattern present, but the surface degradation pattern over the first three hours may dictate the morphology of ensuing deep erosion
Autors: Bruce, G.P.;Rowland, S.M.;Krivda, A.;
Appeared in: IEEE Transactions on Dielectrics and Electrical Insulation
Publication date: Apr 2010, volume: 17, issue:2, pages: 521 - 532
Publisher: IEEE
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» Performance Prediction of Ultrascaled SiGe/Si Core/Shell Electron and Hole Nanowire MOSFETs
Abstract:
The performances of ultrascaled SiGe nanowire field-effect transistors (NWFETs) are investigated using an atomistic tight-binding model and a virtual crystal approximation to describe the Si and Ge atoms. It is first demonstrated that the band edges and the effective masses of both relaxed and strained SiGe bulk are accurately reproduced by our model. The band structure model is then coupled to a top-of-the-barrier quantum transport approach to simulate the output characteristics of ultrascaled n/p SiGe NWFETs and explore their viability for future high-performance CMOS applications. We predict a considerable improvement of SiGe nFETs and pFETs over their Si counterparts for SiGe/Si core/shell structures.
Autors: Paul, A.;Mehrotra, S.;Luisier, M.;Klimeck, G.;
Appeared in: IEEE Electron Device Letters
Publication date: Apr 2010, volume: 31, issue:4, pages: 278 - 280
Publisher: IEEE
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» Performance Simulation and Architecture Optimization for CMOS Image Sensor Pixels Scaling Down to 1.0
Abstract:
As the pixel dimensions of complementary metal–oxide–semiconductor sensors are approaching the wavelength of visible light, significant diffraction effects occur in the pixel architecture region, resulting in decreased optical efficiency and increased spatial crosstalk. By introducing the finite-difference time-domain approach, the performance of the typical 1.75-, 1.35-, and 1.05- pitch pixels is simulated and analyzed, respectively, in this brief. Several new approaches, which are beneficial to overcome the physical limitations of the conventional pixel architecture and providing better device characteristics for the sub-2- pixels, are developed by analyzing the simulation results. Among them, the optimization in microlens can decrease the optical power loss above the color filter array to a certain extent, and the dielectric stack height reduction and a novel metal light funnel structure can maximize the optical efficiency and minimize the spatial crosstalk. Finally, the performance comparisons demonstrate that the optical characteristics of the optimized 1.05- pixel are comparable to those of the conventional 1.75- pixel.
Autors: Zhang, F.;Zhang, J.;Yang, C.;Zhang, X.;
Appeared in: IEEE Transactions on Electron Devices
Publication date: Apr 2010, volume: 57, issue:4, pages: 788 - 794
Publisher: IEEE
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» Performing Nonlinear Blind Source Separation With Signal Invariants
Abstract:
Given a time series of multicomponent measurements , the usual objective of nonlinear blind source separation (BSS) is to find a “source” time series , comprised of statistically independent combinations of the measured components. In this paper, the source time series is required to have a density function in -space that is equal to the product of density functions of individual components. This formulation of the BSS problem has a solution that is unique, up to permutations and component-wise transformations. Separability is shown to impose constraints on certain locally invariant (scalar) functions of , which are derived from local higher-order correlations of the data's velocity . The data are separable if and only if they satisfy these constraints, and, if the constraints are satisfied, the sources can be explicitly constructed from the data. The method is illustrated by using it to recover the contents of two simultaneous speech-like sounds recorded with a single microphone.
Autors: Levin, D. N.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Apr 2010, volume: 58, issue:4, pages: 2131 - 2140
Publisher: IEEE
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» Periodic Analysis of MR-Safe Transmission Lines
Abstract:
In this paper, a theoretical analysis is presented of transmission lines that are periodically interrupted by isolation transformers. Such lines have application as safe interconnects in MRI with internal coils, where the transformers act to block common-mode signals excited by the transmitter while passing differential-mode signals from a detector. The dispersion characteristics are derived, and it is shown that the line is a form of metamaterial supporting magneto-inductive (MI) waves. Propagation can take place in a series of bands, each close to one of the standing wave resonances of an isolated segment. However, it is shown that additional series capacitors are required to implement the protection strategy correctly and the line then operates on a low-frequency lumped-element MI band. Lines operating at 63.8 MHz frequency are constructed using coaxial cables and printed circuit board transformers, and the existence of multiple propagating bands is confirmed.
Autors: Syms, R. R.;Solymar, L. R.;Young, I. R.;
Appeared in: IEEE Journal of Selected Topics in Quantum Electronics
Publication date: Apr 2010, volume: 16, issue:2, pages: 433 - 440
Publisher: IEEE
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» Perpendicular magnetic anisotropy in Co/Pt multilayers studied from a view point of anisotropy of magnetic Compton profiles
Abstract:
Magnetic Compton profiles (MCPs) of Co/Pt multilayers have been measured from a view point of perpendicular magnetic anisotropy (PMA). The PMA and the MCPs are discussed in the present Co/Pt results together with the previous Co/Pd results. The anisotropies of the MCPs have been decomposed into each magnetic quantum number |m|=0, 1, and 2. The decomposition analysis has suggested that the |m|=1 state contributes to the PMA when the multilayer films change in-plane magnetic anisotropy to the PMA, and that the |m|=2 state contributes to the PMA when the multilayer films have large PMA energy.
Autors: Ota, M.;Itou, M.;Sakurai, Y.;Koizumi, A.;Sakurai, H.;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:15, pages: 152505 - 152505-3
Publisher: IEEE
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» Perpendicularizing magnetic anisotropy of full-Heusler Co2FeAl films by cosputtering with terbium
Abstract:
In this letter, we fabricated Co2FeAl films with perpendicular-to-plane magnetic anisotropy by cosputtering with terbium (Tb). The as-prepared (Tb+Co2FeAl) films (TCFA) consists of nanocrystalline L21 Co2FeAl and amorphous alloy of Tb(Co, Fe, and Al). The coercivity field (Hc) of the TCFA films is adjustable from 200 to 800 Oe. After annealing, the Hc decreases to 70 Oe. A perpendicularly magnetized spin valve with the TCFA films as free and reference layers shows a current-perpendicular-to-plane magnetoresistance of 1.8% at room temperature. Our result opens a way to fabricate perpendicularly magnetized full-Heusler alloys and makes it possible to realize faster and simple structured magnetic storage bits in the future.
Autors: Li, X. Q.;Xu, X. G.;Zhang, D. L.;Miao, J.;Zhan, Q.;Jalil, M. B. A.;Yu, G. H.;Jiang, Y.;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:14, pages: 142505 - 142505-3
Publisher: IEEE
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» Persistent supercurrents in ring-shaped Bi2Sr2CaCu2Ox single crystal
Abstract:
A superconducting ring could be used to simulate the supercurrent conduction, and its interaction with magnetic vortices in a superconducting solenoid, allowing one to investigate the nature of the vortex structure and its pinning in the presence of the persistent supercurrent. The dissipation of the persistent supercurrent has been studied in a ring-shaped high purity single crystal of Bi2Sr2CaCu2Ox in order to obtain the information about the exponent μ, a parameter in the scaling relation between the effective energy barrier against vortex motion Ueff and the persistent current density J. The measurements of the persistent supercurrent decay show a transition from a strongly nonlogarithmic to a logarithmic decay regime with an increasing temperature. In response to a small increase in the concentration of oxygen vacancies μ decreases in the logarithmic decay regime but remains almost constant in the nonlogarithmic one.
Autors: Ma, Rongchao;Mansour, A. I.;Egilmez, M.;Winterfield, C. E.;Fan, I.;Chow, K. H.;Jung, J.;Prabhakaran, D.;Razavi, F.;
Appeared in: Journal of Applied Physics
Publication date: Apr 2010, volume: 107, issue:8, pages: 083909 - 083909-4
Publisher: IEEE
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» Personalized Service-Oriented E-Learning Environments
Abstract:
The social component of Web 2.0-related services is providing a new open and personal approach to how we expect things to solve problems in our information-driven world. In particular, students' learning needs require open, personal e-learning systems adapted to life-long learning needs in a rapidly changing environment. It therefore shouldn't be surprising that a new wave of ideas centered on pervasive systems has drawn so much attention. This article analyzes current trends in the evolution of e-learning architectures and describes a new architecture that captures the needs of both formal (instructor-led) and informal (student-led) learning environments.
Autors: Munoz Organero, Mario;Delgado Kloos, Carlos;Munoz Merino, Pedro;
Appeared in: IEEE Internet Computing
Publication date: Apr 2010, volume: 14, issue:2, pages: 62 - 67
Publisher: IEEE
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» PFC buck-boost converter based voltage controlled adjustable speed PMBLDCM drive for air-conditioning
Abstract:
In this paper a power factor correction (PFC) buck-boost converter based adjustable speed voltage controlled voltage source inverter (VSI) fed permanent magnet brushless DC motor (PMBLDCM) drive is employed for an air-conditioning system for the improved energy efficiency. A single-phase single-switch AC-DC converter topology based on the buck-boost converter is employed for PFC which ensures near unity power factor in wide speed range. The speed control scheme has a new concept of DC link voltage control proportional to the desired speed of the PMBLDC motor. Moreover, the control of VSI is used only for electronic commutation of PMBLDCM. Therefore, the number of sensors is reduced as compared to conventional PMBLDCM drive. The proposed control scheme with a PFC converter based PMBLDCM drive is designed, modelled and simulated in Matlab-Simulink environment for an air conditioner compressor. The results obtained are presented to validate the effectiveness of the proposed speed control scheme with PFC feature in wide range of the speed and an input AC mains voltage. Copyright © 2010 John Wiley & Sons, Ltd.
Autors: Sanjeev Singh, Bhim Singh
Appeared in: European Transactions on Electrical Power
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Phase II monitoring of covariance stationary autocorrelated processes
Abstract:
Statistical process control charts are intended to assist operators in detecting process changes. If a process change does occur, the control chart should detect the change quickly. Owing to the recent advancements in data retrieval and storage technologies, today's industrial processes are becoming increasingly autocorrelated. As a result, in this paper we investigate a process-monitoring tool for autocorrelated processes that quickly responds to process mean shifts regardless of the magnitude of the change, while supplying useful diagnostic information upon signaling. A likelihood ratio approach was used to develop a phase II control chart for a permanent step change in the mean of an ARMA (p, q) (autoregressive-moving average) process. Monte Carlo simulation was used to evaluate the average run length (ARL) performance of this chart relative to that of the more recently proposed ARMA chart. Results indicate that the proposed chart responds more quickly to process mean shifts, relative to the ARMA chart, while supplying useful diagnostic information, including the maximum likelihood estimates of the time and the magnitude of the process shift. These crucial change point diagnostics can greatly enhance the special cause investigation. Copyright © 2010 John Wiley & Sons, Ltd.
Autors: Marcus B. Perry, Gary R. Mercado, Joseph J. Pignatiello Jr
Appeared in: Quality and Reliability Engineering International
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Phase Margin Degradation of a Peak Current Controlled Converter at Reduced Duty Cycle
Abstract:
An inner current loop is frequently used in many switching power supplies to achieve higher stability and a good current sharing. Nevertheless, some problems derived from its practical implementation can be encountered. One problem is related to the need of filtering of the sensed current and was discovered by the authors in the implementation of a 500 W converter, when peak current control was applied by sensing the switch current. This paper will demonstrate mathematically that an filter not only filters out the noise but also can cause a degradation of the phase margin, especially, if the needed duty cycle is close to zero. The main reason for it is the severe distortion of the current waveform that results in an excessive phase loss. This phase loss is much larger than the expected from the filter and its delay. The problem becomes worse if we reduce the duty cycle and increase the load current. Therefore, the response to the on time slope of the current waveform is negligible, and we have only the response to a steep rising edge. We will also demonstrate that phase margin loss disappears if current is sensed at the inductor instead of the switch. In both cases, the filter results in a different frequency response than the one predicted with the classical peak current mode theory. These differences are analyzed in depth in this paper.
Autors: Ejea-Martí, J.;Sanchis-Kilders, E.;Maset, E.;Ferreres, A.;Blanes, J. M.;Garrigós , A.;Jordán, J.;Esteve, V.;
Appeared in: IEEE Transactions on Power Electronics
Publication date: Apr 2010, volume: 25, issue:4, pages: 863 - 874
Publisher: IEEE
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» Phase-locked ring-defect photonic crystal vertical-cavity surface-emitting laser
Abstract:
Phase-locked oxide-confined ring-defect photonic crystal vertical-cavity surface-emitting laser is presented. The coupled-mode theory is employed to illustrate the two supermodes of the device, in-phase and out-of-phase supermode. Experimental results verify the two supermodes by the characteristics of the spectra and the far field patterns. At the lower current, only the out-of-phase supermode is excited, whereas under the higher current, the in-phase supermode also appears at the shorter wavelength range. In addition, the measured spectral separation between the two supermodes agrees well with the theoretical result.
Autors: Liu, Anjin;Chen, Wei;Xing, Mingxin;Zhou, Wenjun;Qu, Hongwei;Zheng, Wanhua;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:15, pages: 151103 - 151103-3
Publisher: IEEE
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» PHASE-SHIFT DETECTION FOR CAPACITANCE SENSOR MEASURING VOID FRACTION IN TWO PHASE FLOW
Abstract:
Capacitance sensors are frequently applied for void fraction measurements in two-phase flow. A capacitance sensor is formed by two electrodes of various shapes, usually a fragment of a cylinder, mounted at the outside of the wall of a dielectric pipeline through which a two-phase medium flows. The capacitance of the sensor changes when the mean dielectric constant between the electrodes varies due to variations in the percentage of gas and liquid flowing in the pipe. For the detection of the measuring signal, an impedance bridge or a frequency-deviation counter are usually used. In this paper, a new measuring procedure was...
Autors: A., Jaworek , A., Krupa
Appeared in: Sensors and Actuators A: Physical
Publication date: Apr 2010
Publisher: Elsevier B.V.
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» Photoelectric performance of TiO2 nanotube array photoelectrodes cosensitized with CdS/CdSe quantum dots
Abstract:
The photoresponse of TiO2 nanotube-array films in the visible region is shown to have been significantly improved by sensitizing them with CdS and CdSe semiconductor quantum dots using a sequential chemical bath deposition method. These quantum dots served as cosensitizers, and the performance of corresponding photoelectrode was measured in a photoelectrochemical solar cell. A 13.0 mA/cm2 short circuit current density is achieved with the TiO2/CdS/CdSe photoelectrode under AM 1.5G illuminations, which is higher than the direct sum of CdS and CdSe sensitized TiO2.
Autors: Gao, Xian-Feng;Sun, Wen-Tao;Ai, Guo;Peng, Lian-Mao;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:15, pages: 153104 - 153104-3
Publisher: IEEE
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» Photoinduced charge-trapping phenomena in metal/high-k gate stack structures studied by synchrotron radiation photoemission spectroscopy
Abstract:
We have demonstrated photoinduced charge-trapping phenomena in metal/high-k gate stack structures using time-dependent photoemission spectroscopy with synchrotron radiation. Pt metal gate electrode with a large work function releases trapped negative charges near the surface of the HfSiON film while TiN metal gate electrode with a lower work function keeps negative charges in the HfSiON film. The release of negative trapped charges reveals a possibility of positive charge trapping at the interface in the HfSiON film. The location of energy level for negative charges is concluded to be between Pt and TiN Fermi-level in the band gap of the HfSiON film.
Autors: Tanimura, T.;Toyoda, S.;Kamada, H.;Kumigashira, H.;Oshima, M.;Sukegawa, T.;Liu, G. L.;Liu, Z.;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:16, pages: 162902 - 162902-3
Publisher: IEEE
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» Photoinduced deformation of azopolymer nanometric spheres
Abstract:
Nanometric spheres of an azopolymer are obtained by micellization from a solution. We observe photoinduced deformation of the individual nanospheres under white light illumination. The diameter expands up to 35% parallel to the substrate surface. The magnitude of the force that is necessary to produce the same effect is estimated.
Autors: Barille, R.;Tajalli, P.;Kucharski, S.;Ortyl, E.;Nunzi, J.-M.;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:16, pages: 163104 - 163104-3
Publisher: IEEE
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» Photoluminescence spectroscopy and positron annihilation spectroscopy probe of alloying and annealing effects in nonpolar m-plane ZnMgO thin films
Abstract:
Temperature-dependent photoluminescence characteristics of non-polar m-plane ZnO and ZnMgO alloy films grown by metal organic chemical vapor deposition have been studied. The enhancement in emission intensity caused by localized excitons in m-plane ZnMgO alloy films was directly observed and it can be further improved after annealing in nitrogen. The concentration of Zn vacancies in the films was increased by alloying with Mg, which was detected by positron annihilation spectroscopy. This result is very important to directly explain why undoped Zn1-xMgxO thin films can show p-type conduction by controlling Mg content, as discussed by Li etal [Appl. Phys. Lett. 91, 232115 (2007)].
Autors: Yang, A. L.;Song, H. P.;Liang, D. C.;Wei, H. Y.;Liu, X. L.;Jin, P.;Qin, X. B.;Yang, S. Y.;Zhu, Q. S.;Wang, Z. G.;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:15, pages: 151904 - 151904-3
Publisher: IEEE
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» Photonic Device Layout Within the Foundry CMOS Design Environment
Abstract:
A design methodology to layout photonic devices within standard electronic complementary metal–oxide–semiconductor (CMOS) foundry data preparation flows is described. This platform has enabled the fabrication of designs in three foundry scaled-CMOS processes from two semiconductor manufacturers.
Autors: Orcutt, J. S.;Ram, R. J.;
Appeared in: IEEE Photonics Technology Letters
Publication date: Apr 2010, volume: 22, issue:8, pages: 544 - 546
Publisher: IEEE
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» Photopatternable Superhydrophobic Nanocomposites for Microfabrication
Abstract:
In this paper, we first report on direct-photolithography-based microfabrication of transparent superhydrophobic micropatterns using novel photodefinable nanocomposites, combining the nanomorphology and hydrophobicity of polytetrafluoroethylene (PTFE) nanoparticles and the photopatternability and transparency of an SU-8 photoresist using both direct-mixing and coating-immobilization methods. The direct mixture of PTFE–SU-8 nanocomposite can be reliably spin-coated and photopatterned onto transparent substrates (e.g., glass or polymers) with a minimal feature resolution of 50 . The resulting nanocomposite film possesses a contact angle of water at 150 , although its optical transparency is less than 30%. Furthermore, a modified coating-immobilization approach, employing spray coating and thermal immobilization of PTFE nanoparticles onto an SU-8 polymer matrix, significantly enhances superhydrophobicity, lithography resolution, as well as optical transparency. The highest optical transparency of 80% and a minimal feature resolution of 10 have been achieved using the standard photolithography approach, while the contact angle of water above 165 enables extraordinary superhydrophobicity with low hysteresis. The novel PTFE–SU-8 nanocomposites provide a unique combination of superhydrophobicity, optical transparency, and photopatternability, along with excellent adaptability and simple processability, which offer great extension to rapidly evolving micro–nanoengineering applications. [2009-0224]
Autors: Hong, L.;Pan, T.;
Appeared in: Journal of Microelectromechanical Systems
Publication date: Apr 2010, volume: 19, issue:2, pages: 246 - 253
Publisher: IEEE
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» Physical mechanisms for hot-electron degradation in GaN light-emitting diodes
Abstract:
We report investigations on the degradation of GaN-based light-emitting diodes due to high dc current stress by examining two types of devices with the same fabrication procedures except for the growth conditions for the InGaN quantum wells (QWs). Higher trimethylindium and triethylgallium fluxes are used for type A devices resulting in a threefold increase in the InGaN QWs growth rate compared to type B devices. Detailed structural and optoelectronic properties of the devices are investigated by transmission electron microscopy, atomic force microscopy, thermal imaging, I-V measurements, and the low-frequency noise properties of the devices as a function of the stress time, tS. The experimental data show that the QWs in type B devices are dominated by spiral growth and they have substantially higher strain nonuniformity than type A devices. The highly strained GaN/InGaN interfaces in device B are also responsible for the faster increase in the defect density due to hot-electron injection. The defects enhance the trap-assisted tunneling in the multiple quantum wells (MQWs) resulting in the development of hot spots among type B devices after high current stressing of the MQWs. This in turn leads to an increase in the defect generation rate resulting in a thermal run-away condition that ultimately resulted in the failure of the device. The data show that an increase in the growth rate in the InGaN layer led to the domination by the step flow growth mode over the spiral growth mode in the MQWs. This is the main reason for the reduction in the dislocation density in type A devices and hence their increase in device reliability.
Autors: Leung, K. K.;Fong, W. K.;Chan, P. K. L.;Surya, C.;
Appeared in: Journal of Applied Physics
Publication date: Apr 2010, volume: 107, issue:7, pages: 073103 - 073103-6
Publisher: IEEE
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» Physical origin of dipole formation at high-k/SiO2 interface in metal-oxide-semiconductor device with high-k/metal gate structure
Abstract:
A physical model on dipole formation at high-k/SiO2 interface is proposed to study possible mechanism of flatband voltage (VFB) shift in metal-oxide-semiconductor device with high-k/metal gate structure. Dielectric contact induced gap states (DCIGS) on high-k or SiO2 side induced by high-k and SiO2 contact are assigned to dominant origin of dipole formation. DCIGS induced interface dipole is considered to cause VFB shift through charge transfer effect. Based on the proposed model, directions of dipoles at several high-k/SiO2 interfaces are predicted, and magnitudes of dipoles are approximately calculated. Both directions and magnitudes are in agreement with the reported results.
Autors: Wang, Xiaolei;Han, Kai;Wang, Wenwu;Chen, Shijie;Ma, Xueli;Chen, Dapeng;Zhang, Jing;Du, Jun;Xiong, Yuhua;Huang, Anping;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:15, pages: 152907 - 152907-3
Publisher: IEEE
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» Pi: A practical incentive protocol for delay tolerant networks
Abstract:
Delay Tolerant Networks (DTNs) are a class of networks characterized by lack of guaranteed connectivity, typically low frequency of encounters between DTN nodes and long propagation delays within the network. As a result, the message propagation process in DTNs follows a store-carryand- forward manner, and the in-transit bundle messages can be opportunistically routed towards the destinations through intermittent connections under the hypothesis that each individual DTN node is willing to help with forwarding. Unfortunately, there may exist some selfish nodes, especially in a cooperative network like DTN, and the presence of selfish DTN nodes could cause catastrophic damage to any well designed opportunistic routing scheme and jeopardize the whole network. In this paper, to address the selfishness problem in DTNs, we propose a practical incentive protocol, called Pi, such that when a source node sends a bundle message, it also attaches some incentive on the bundle, which is not only attractive but also fair to all participating DTN nodes. With the fair incentive, the selfish DTN nodes could be stimulated to help with forwarding bundles to achieve better packet delivery performance. In addition, the proposed Pi protocol can also thwart various attacks, which could be launched by selfish DTN nodes, such as free ride attack, layer removing and adding attacks. Extensive simulation results demonstrate the effectiveness of the proposed Pi protocol in terms of high delivery ratio and lower average delay.
Autors: Lu, R.;Lin, X.;Zhu, H.;Shen, X.;Preiss, B.;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: Apr 2010, volume: 9, issue:4, pages: 1483 - 1493
Publisher: IEEE
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» Pick, break, and placement of one-dimensional nanostructures for direct assembly and integration
Abstract:
A direct, simple, and versatile assembly method for the manipulation of one-dimensional nanostructures and their integration with microscale devices has been demonstrated. Using a probe station with an unbiased tungsten probe, the facile process has been employed to accurately pick, break, and place individual titanium dioxide nanoswords and zinc oxide nanowires under a room-temperature, dry environment. The surface morphology of the nanostructures, probe tips, and adhesion forces were characterized. As such, the technique could enable the rapid assembly of individual nanostructures with complementary metal-oxide-semiconductor-compatible or complex microscale devices.
Autors: Sosnowchik, Brian D.;Chang, Jiyoung;Lin, Liwei;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:15, pages: 153101 - 153101-3
Publisher: IEEE
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» Piezoelectric MEMS energy harvesting systems driven by harmonic and random vibrations
Abstract:
Switching power conditioning techniques are known to greatly enhance the performance of linear piezoelectric energy harvesters subject to harmonic vibrations. With such circuits, little is known about the effect of mechanical stoppers that limit the motion or about waveforms other than harmonic vibrations. This work presents SPICE simulations of piezoelectric micro energy harvester systems that differ in choice of power conditioning circuits and stopper models. We consider in detail both harmonic and random vibrations. The nonlinear switching conversion circuitry performs better than simple passive circuitry, especially when mechanical stoppers are in effect. Stopper loss is important under broadband vibrations. Stoppers limit the output power for sinusoidal excitations, but result in the same output power whether the stoppers are lossy or not. When the mechanical stoppers are hit by the proof mass during high-amplitude vibrations, nonlinear effects such as saturation and jumps are present.
Autors: Blystad, L.-C.J.;Halvorsen, E.;Husa, S.;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: Apr 2010, volume: 57, issue:4, pages: 908 - 919
Publisher: IEEE
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» Pigment Melanin: Pattern for Iris Recognition
Abstract:
Recognition of iris based on visible light (VL) imaging is a difficult problem because of the light reflection from the cornea. Nonetheless, pigment melanin provides a rich feature source in VL, which is unavailable in near-infrared (NIR) imaging. This is due to the biological spectroscopy of eumelanin, a chemical not stimulated in NIR. In this case, a plausible solution to observe such patterns may be provided by an adaptive procedure using a variational technique on the image histogram. To describe the patterns, a shape analysis method is used to derive the feature code for each subject. An important question is how the melanin patterns, which are extracted from VL, are independent of the iris texture in NIR. With this question in mind, the present investigation proposes fusion of features extracted from NIR and VL to boost recognition performance. We have collected our own database (UTIRIS), consisting of both NIR and VL images of 158 eyes of 79 individuals. This investigation demonstrates that the proposed algorithm is highly sensitive to the patterns of chromophores and improves the iris recognition rate.
Autors: Hosseini, M. S.;Araabi, B. N.;Soltanian-Zadeh, H.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Apr 2010, volume: 59, issue:4, pages: 792 - 804
Publisher: IEEE
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» Plasmonic enhanced quantum well infrared photodetector with high detectivity
Abstract:
We report a normal-incident quantum well infrared photodetector (QWIP) strongly coupled with surface plasmon modes. A periodic hole array perforated in gold film was integrated with In0.53Ga0.47As/InP QWIP to convert normal-incident electromagnetic waves into surface plasmon waves, and to excite the intersubband transition of carriers in the quantum wells. The peak responsivity of the photodetector at ∼8 μm was ∼7 A/W at the bias of 0.7 V at 78 K with the peak detectivity as high as ∼7.4×1010 cmHz1/2/W. The full width at half maximum of the response spectrum was only ∼0.84 μm due to a narrow plasmonic resonance.
Autors: Wu, Wei;Bonakdar, Alireza;Mohseni, Hooman;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:16, pages: 161107 - 161107-3
Publisher: IEEE
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» Plasmonic nanoparticle enhanced photocurrent in GaN/InGaN/GaN quantum well solar cells
Abstract:
We demonstrate enhanced external quantum efficiency and current-voltage characteristics due to scattering by 100 nm silver nanoparticles in a single 2.5 nm thkck InGaAn quantum well photovoltaic device. Nanoparticle arrays were fabricated on the surface of the device using an anodic alumina template masking process. The Ag nanoparticles increase light scattering, light trapping, and carrier collection in the III-N semiconductor layers leaqding to enhancement of the external quantum efficiency by up to 54%. Additionally, the short-circuit current in cells with 200 nm p-GaN emitter regions is increased by 6% under AM 1.5 illumination. AFORS-Het simulation software results were used to prdict cell performance and optimize emitter layer thickness.
Autors: Pryce, Imogen M.;Koleske, Daniel D.;Fischer, Arthur J.;Atwater, Harry A.;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:15, pages: 153501 - 153501-3
Publisher: IEEE
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» PML absorbing boundary condition for the integral-based high-order FV24 FDTD algorithm
Abstract:
An integral equations-based perfectly matched layers (PML) implementation is presented for the highly phase-coherent FV24 finite-difference time-domain (FDTD) algorithm. The implementation allows including field values off the grid axes in the split-field PML formulation conserving in the process the continuity and phase coherency of the FV24 algorithm when modeling absorbing boundary conditions (ABCs). It also eliminates the need for cumbersome subgridded low-order FDTD subregions that until now were required to model PML ABCs within integral-based high-order FDTD simulations. The developed approach was numerically tested and found to match the PML behavior of the standard FDTD method at normal wave incidence on ABC boundaries and exceeds it at highly oblique wave incidence. This development serves to improve the capability and practicality of the computationally efficient FV24 algorithm when modeling electrically large structures in 3-D space. Copyright © 2010 John Wiley & Sons, Ltd.
Autors: M. F. Hadi
Appeared in: International Journal of Numerical Modelling: Electronic Networks, Devices and Fields
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Polar Codes are Optimal for Lossy Source Coding
Abstract:
We consider lossy source compression of a binary symmetric source using polar codes and a low-complexity successive encoding algorithm. It was recently shown by Arıkan that polar codes achieve the capacity of arbitrary symmetric binary-input discrete memoryless channels under a successive decoding strategy. We show the equivalent result for lossy source compression, i.e., we show that this combination achieves the rate-distortion bound for a binary symmetric source. We further show the optimality of polar codes for various multiterminal problems including the binary Wyner-Ziv and the binary Gelfand-Pinsker problems. Our results extend to general versions of these problems.
Autors: Korada, S. B.;Urbanke, R. L.;
Appeared in: IEEE Transactions on Information Theory
Publication date: Apr 2010, volume: 56, issue:4, pages: 1751 - 1768
Publisher: IEEE
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» Polarimetric Characterization and Temporal Stability Analysis of Urban Target Scattering
Abstract:
This paper studies the polarimetric-dispersion properties of urban targets and their evolution along time in terms of the geometrical configuration. The relations between target geometry and the scattering behavior have been defined through the analysis of large stacks of simulated images. Scattering maps and synthetic aperture radar (SAR) images have been synthesized with the numerical tool GRaphical Electromagnetic COmputing SAR for different qualitative models of two real buildings. Ground-based SAR (GB-SAR) data acquired in a subsidence measurement campaign has been used to assess the simulator's realism. These data have permitted the identification of the critical simulation parameters and their range of recommended values for realistic simulations. In the context of very high resolution images, the results derived from this study may be crucial for making progress in urban-image postprocessing. As the different resolution cells comprise few scattering centers showing a quasi-deterministic scattering behavior, nonprobabilistic models based on target's geometry seem more suited for scattering modeling. In these models, the geometry-scattering (GS) links precisely inferred from simulated images can be very important. In addition to change detection and land classification, GS models may help in improving the interpretation of subsidence results with differential interferometry. Certainly, new processing algorithms can be developed exploiting the available scattering data with more physical sense. In addition, they can take more advantage of the fine resolution and polarimetric capabilities of the new sensors, like TerraSAR-X or RADARSAT-2.
Autors: Margarit, G.;Mallorqui, J. J.;Pipia, L.;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: Apr 2010, volume: 48, issue:4, pages: 2038 - 2048
Publisher: IEEE
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» Polarization Effects in Microfiber Loop and Knot Resonators
Abstract:
We theoretically investigate the polarization effect of three-dimensional (3-D) microfiber/nanofiber (MNF) loop resonators and knot resonators. Due to the lack of circular symmetry, the coupling at the joint regions of loop resonator and knot resonator are highly polarization-dependent. Using Jones matrices to express coupling coefficients, we suggest a matrix formula to describe the propagation of arbitrary polarized incidence through the resonator. Thereby, the polarization effect of 3-D loop resonators and knot resonators can be comprehensively investigated. We find that the polarization properties of the resonance spectrum and -factor are strongly dependent on the parameters of the twisted region. Results obtained in this work may serve as helpful guidelines for MNF resonator design and fabrication.
Autors: Wang, G.;Shum, P. P.;Tong, L.;Li, C. M.;Lin, C.;
Appeared in: IEEE Photonics Technology Letters
Publication date: Apr 2010, volume: 22, issue:8, pages: 586 - 588
Publisher: IEEE
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» Polarization Rotating Frequency Selective Surface Based on Substrate Integrated Waveguide Technology
Abstract:
A novel frequency selective surface based on substrate integrated waveguide technology (SIW) is proposed and studied theoretically and experimentally. Its primary function is the selection of a linear polarization of an incident wave and its 90-degree rotation in a given frequency band. The proposed structure is based on an SIW cavity, coupled to the input and output by two orthogonal slots, and is designed using a simulation code based on the method of moments boundary integral-resonant mode expansion method, especially developed for the accurate characterization of FSS structures. Moreover, a complete design procedure for the proposed structure and a parametric study of its performance are presented. Finally, in order to verify the proposed structure, a prototype is designed at an operation frequency of 35 GHz, exhibiting a relative bandwidth of 9.1% and an impedance matching of better than dB with a maximum insertion loss of 0.2 dB in the passband. Its performance is investigated in detail including the analysis of non-orthogonal incidence angles.
Autors: Winkler, S. A.;Hong, W.;Bozzi, M.;Wu, K.;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: Apr 2010, volume: 58, issue:4, pages: 1202 - 1213
Publisher: IEEE
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» Polarization-Independent All-Fiber Acousto-Optic Tunable Filter Using Torsional Acoustic Wave
Abstract:
The intrinsic polarization dependence of an all-fiber tunable wavelength filter based on polarization coupling by torsional acoustic wave is eliminated by employing a fiber loop configuration. In the fiber loop, two orthogonal polarizations split from input light propagate the single acousto-optic interaction region in opposite directions before being recombined to produce a polarization-independent filter spectrum. The polarization-dependent loss was estimated to be less than 0.1 and 0.3 dB within passband in bandpass and notch type filters, respectively.
Autors: Lee, K. J.;Hwang, I.-K.;Park, H. C.;Kim, B. Y.;
Appeared in: IEEE Photonics Technology Letters
Publication date: Apr 2010, volume: 22, issue:8, pages: 523 - 525
Publisher: IEEE
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» Polarization-independent multiple selective reflections from bichiral liquid crystal films
Abstract:
We have demonstrated polarization-independent multiple reflections covering overall visible region from a bichiral liquid crystal (LC) film with both chiral structures. The bichiral LC film was fabricated by an all-solution process using left-handed and right-handed polymeric cholesteric liquid crystal (CLC) films with a single pitch and an isotropic polymer film. The multiple reflections exceeding 50% reflectance were clearly observed at various polarizations of normally incident light. This characteristic can extend practical applications of CLCs to polarization-independent devices over broad-band regions.
Autors: Ha, Na Young;Jeong, Soon Moon;Nishimura, Suzushi;Takezoe, Hideo;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:15, pages: 153301 - 153301-3
Publisher: IEEE
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» Polarization-Multiplexed Optical Wireless Transmission With Coherent Detection
Abstract:
In this paper, we propose, analyze, and experimentally verify polarization-multiplexed optical wireless transmission with coherent detection as a means of improving performance and increasing the per-wavelength data rate in the presence of atmospheric turbulence. It is first shown that in terrestrial last-mile applications, the polarization state changes of the optical wireless signal are governed by optical source properties both in the absence and in the presence of mild to moderately severe turbulence. Under these conditions, it is shown that the polarization evolution is reduced to a polarization state rotation wherein the cross-polarization interference can be equalized with well-known blind algorithms. We also experimentally verify the analytical findings, demonstrating 112 Gb/s POLMUX-QPSK transmission with coherent detection in a non-fading free-space channel, and numerically extend the experimental results to turbulent settings by invoking the lognormal model for turbulence-induced fading. Performance gains of 5–14 dB along with a doubling of the data rate through polarization multiplexing are exhibited compared to legacy single-polarization intensity modulation/direct detection (IM/DD) optical wireless systems. The presented analytical and experimental results indicate that the proposed approach is promising for notably increasing the data rate in last-mile free-space optical transmission.
Autors: Cvijetic, N.;Qian, D.;Yu, J.;Huang, Y.-K.;Wang, T.;
Appeared in: Journal of Lightwave Technology
Publication date: Apr 2010, volume: 28, issue:8, pages: 1218 - 1227
Publisher: IEEE
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» Polarized pressure dependence of the anisotropic dielectric functions of highly oriented poly(p-phenylene vinylene)
Abstract:
In this work, we combined an experimental technique and a detailed data analysis to investigate the influence of an applied pressure on the anisotropic dielectric functions of highly oriented poly(p-phenylene vinylene) (PPV). The dielectric constants were derived from polarized reflectance spectra recorded through a diamond anvil cell up to 50 kbar. The presence of the diamond anvils strongly affects measured spectra requiring the development in an optical model able to take all spurious effects into account. A parametric procedure was then applied to derive the complex dielectric constants for both polarizations as a function of pressure. A detailed analysis of their pressure dependence allows addressing the role of intermolecular interactions and electron-phonon coupling in highly oriented PPV.
Autors: Morandi, V.;Galli, M.;Marabelli, F.;Comoretto, D.;
Appeared in: Journal of Applied Physics
Publication date: Apr 2010, volume: 107, issue:7, pages: 073106 - 073106-7
Publisher: IEEE
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» Policy gradient learning for quadruped soccer robots
Abstract:
In real-world robotic applications, many factors, both at low-level (e.g., vision, motion control and behaviors) and at high-level (e.g., plans and strategies) determine the quality of the robot performance. Consequently, fine tuning of the parameters, in the implementation of the basic functionalities, as well as in the strategic decisions, is a key issue in robot software development. In recent years, machine learning techniques have been successfully used to find optimal parameters for typical robotic functionalities.
Autors: A., Cherubini , F., Giannone , L., Iocchi , D., Nardi , P.F., Palamara
Appeared in: Robotics and Autonomous Systems
Publication date: Apr 2010
Publisher: Elsevier B.V.
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» PolInSAR Statistical Analysis and Coherence Optimization Using Fractional Lower Order Statistics
Abstract:
In this letter, the polarimetric synthetic aperture radar (SAR) interferometry (PolInSAR) statistical model is studied using the alpha-stable distribution. Based on this model, a vector coherence formulation using fractional lower order statistics is proposed. This vector coherence is the generalization of the vector coherence in the paper of Cloude and Papathanassiou when the PolInSAR data are non-Gaussian and conform to the symmetrical form of the alpha-stable distribution. The standard coherence optimization method in the aforementioned paper is modified based on this generalized vector coherence. Results were demonstrated using a small L-band PolInSAR data set and suggest that this proposed coherence optimization method reduces artifacts in the optimized phases in certain areas.
Autors: Bian, Y.;Mercer, B.;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: Apr 2010, volume: 7, issue:2, pages: 314 - 318
Publisher: IEEE
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» Pollution tests for polymeric insulators made of hydrophobicity transfer materials
Abstract:
There are no standardized methods available at present for artificial pollution testing of polymeric insulators. Modified Salt Fog and Solid Layer tests based on procedures described in IEC 60507, intended for ceramic insulators, are thus often applied. Among methods evaluated for polymeric insulators made of hydrophobicity transfer materials (HTM), a modified Solid Layer test with preconditioning by dry powder is considered as being representative and most promising for future standardization. Further, the proposed procedure allows for testing at different hydrophobic states of the polluted insulators via the introduction of defined time between the application of pollution and voltage test. Finally, if the 50% flashover voltage is determined using e.g. the up-anddown method, results of the tests can be directly applied for insulator selection and dimensioning by means of statistical or deterministic methods.
Autors: Gutman, I.;Dernfalk, A.;
Appeared in: IEEE Transactions on Dielectrics and Electrical Insulation
Publication date: Apr 2010, volume: 17, issue:2, pages: 384 - 393
Publisher: IEEE
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» Polydimethylsiloxane-enclosed liquid crystal lasers for lab-on-chip applications
Abstract:
We demonstrate the operation of a self-organized cholesteric liquid crystal laser confined between optically clear and elastic polydimethylsiloxane (PDMS) substrates. The formation of a planar helical texture in the cholesteric was supported by microsctructuring of PDMS layer surface, using the nanoembossing technique with glass substrates coated with conventional alignment layers as a template. The potential of combining miniature cholesteric laser sources and microfluidic devices for lab-on-chip applications is discussed.
Autors: Schmidtke, Jurgen;Terentjev, Eugene M.;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:15, pages: 151111 - 151111-3
Publisher: IEEE
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» Polygon-Based Fractals from Compressed Iterated Function Systems
Abstract:
This paper addresses the equivalence between iterative function systems (IFS). It also explains how to classify and reduce the parameter space for a particular class of IFS.The proposed method generates various fractal textures for regular polygons and allows the creation of polygon-based fractal flakes, polygon-based spirals, and many other forms. It employs sth-order restriction, a new version of recurrent iterated function systems. Level-specified symmetry in the fractals is controlled through rth-level symmetrization.
Autors: Van Loocke, P.;
Appeared in: IEEE Computer Graphics and Applications
Publication date: Apr 2010, volume: 30, issue:2, pages: 34 - 44
Publisher: IEEE
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» Polymer light emitting diodes containing nanoparticle clusters for improved efficiency
Abstract:
We realized polymer light emitting diodes (PLEDs) containing oxidic nanoparticle clusters between the emission layer and the cathode. Different PLEDs with SiO2 and SiO2/TiO2 nanoparticle blends were fabricated and characterized by electroluminescence (EL) and photoluminescence (PL) measurements. We found that the incorporation of pure SiO2 leads to the most efficient devices boosting the efficiency up to a factor of about 4 at 60 mA/cm2. Characterization shows that this is not a scattering effect but rather due to enhanced internal quantum efficiency. The underlying mechanism is attributed to the nanoparticles creating a randomly nanopatterned cathode layer which in turn increases the...
Autors: Boris, Riedel , Julian, Hauss , Markus, Aichholz , Andre, Gall , Uli, Lemmer , ...
Appeared in: Organic Electronics
Publication date: Apr 2010
Publisher: Elsevier B.V.
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» Pornographic image screening by integrating recognition module and image black-list/ white-list subsystem
Abstract:
A number of pornographic image detection techniques have been studied in the literature but the online error-correction method is rarely discussed. As some of the pornographic images on the Internet are duplicated, the online error-correction capability can prevent repeated misclassification occurring on the same image. An image black-list/white-list subsystem is presented to correct the classification errors of the recognition module. This subsystem uses the wavelet transform to extract the colour and texture features from images. However, images can be lossily compressed and the image features will be shifted. To be able to identify lossily compressed images, a support vector machine serves as a classifier to determine whether two image feature vectors represent the same image. The experimental result demonstrates that the proposed subsystem can remedy the errors of the recognition module and increase the recognition accuracy. 1 Introduction Because of the large amount of pornographic data (text, images, videos and so on) existing on World Wide Web sites, how to block them from children?s access has become an active research topic. Most of the relative works have focused on detecting pornographic images. Lee et al. [1] used the AdaBoost method to classify images as naked or not according to the features extracted from the skin regions. A similar approach is also adopted in the work of Zheng et al. [2]. Jones and Rehg [3] detected the skin pixels by calculating the skin likelihood ratio of each pixel. Then, seven features are extracted and input into a neural network to classify the image. Shih et al. [4] and Wang et al. [5] retrieved similar images from a pre-organised image database for an unknown image. If there is a certain portion of adult images in the retrieved images, the unknown image is recognised as an adult image. Forsyth and Fleck [6] connected the edge points of the skin areas to form limbs and segments and used a set of geometric constraints to deter- mine whether a human figure is present. The method of Yang et al. [7] extracted the regions of interest (ROI) from the image first.
Autors: Sun, H.-M.;
Appeared in: IET Image Processing
Publication date: Apr 2010, volume: 4, issue:2, pages: 103 - 113
Publisher: IEEE
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» Position dependent photodetector from large area reduced graphene oxide thin films
Abstract:
We fabricated large area infrared photodetector devices from thin film of chemically reduced graphene oxide (RGO) sheets and studied their photoresponse as a function of laser position. We found that the photocurrent either increases, decreases, or remain almost zero depending upon the position of the laser spot with respect to the electrodes. The position sensitive photoresponse is explained by Schottky barrier modulation at the RGO film-electrode interface. The time response of the photocurrent is dramatically slower than single sheet of graphene possibly due to disorder from the chemical synthesis and interconnecting sheets.
Autors: Ghosh, Surajit;Sarker, Biddut K.;Chunder, Anindarupa;Zhai, Lei;Khondaker, Saiful I.;
Appeared in: Applied Physics Letters
Publication date: Apr 2010, volume: 96, issue:16, pages: 163109 - 163109-3
Publisher: IEEE
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» Post-CMOS Fabrication of Working Electrodes for On-Chip Recordings of Transmitter Release
Abstract:
The release of neurotransmitters and hormones from secretory vesicles plays a fundamental role in the function of the nervous system including neuronal communication. High-throughput testing of drugs modulating transmitter release is becoming an increasingly important area in the fields of cell biology, neurobiology, and neurology. Carbon-fiber amperometry provides high-resolution measurements of amount and time course of the transmitter release from single vesicles, and their modulation by drugs and molecular manipulations. However, these methods do not enable the rapid collection of data from a large number of cells. To allow this testing, we have developed a complementary metal–oxide semiconductor (CMOS) potentiostat circuit that can be scaled to a large array. In this paper, we present two post-CMOS fabrication methods to incorporate the electrochemical electrode material. We demonstrate by proof of principle the feasibility of on-chip electrochemical measurements of dopamine, and catecholamine release from adrenal chromaffin cells. The measurement noise is consistent with the typical electrode noise in recordings with external amplifiers. The electronic noise of the potentiostat in recordings with 400– s integration time is 0.11 pA and is negligible compared to the inherent electrode noise.
Autors: Ayers, S.;Berberian, K.;Gillis, K. D.;Lindau, M.;Minch, B. A.;
Appeared in: IEEE Transactions on Biomedical Circuits and Systems
Publication date: Apr 2010, volume: 4, issue:2, pages: 86 - 92
Publisher: IEEE
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» Post-Manufacture Tuning for Nano-CMOS Yield Recovery Using Reconfigurable Logic
Abstract:
In this paper, an architectural framework for post-silicon tuning of nanoscale CMOS circuits is developed. The tuning methodology is driven by a “tunable” gate design that allows the gate to be switched from a high-speed/high-power mode to a low-speed/low-power mode under digital control. A small number of “critical” logic gates are replaced with tunable gates for post-silicon power-performance tuning. In addition, supply voltage and body bias can be employed as hardware “tuning knobs” as well to deal with delay and leakage variations. After silicon is manufactured, the hardware “knobs” are programmed through the use of an implicit self-test methodology that can be exercised by the proposed self-adaptation architectural framework. It is seen that the delay yield can be improved by an average of 40% with minimal impact on area.
Autors: Ashouei, M.;Chatterjee, A.;Singh, A. D.;
Appeared in: IEEE Transactions on Very Large Scale Integration Systems
Publication date: Apr 2010, volume: 18, issue:4, pages: 675 - 679
Publisher: IEEE
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» Postaccident Mine Communications and Tracking Systems
Abstract:
Recent mine disasters in the U.S. exposed various inadequacies and gaps in mine-safety technology. Congress responded to these tragedies by enacting the Mine Improvement and New Emergency Response Act of 2006 (MINER Act), which resulted in the most significant change to mine-safety laws in 30 years. To help meet the requirements of the MINER Act and to help eliminate future tragedies, the National Institute for Occupational Safety and Health initiated aggressive research programs for developing new, and enhancing existing, mine-safety technologies. A major research emphasis addressed the lack of postaccident communications, which surfaced as a critical deficiency in some disasters. As a result, three communications approaches emerged as viable technologies—enhanced leaky-feeder, wireless-mesh, and medium-frequency systems. This paper describes the operation, application, advantages, and disadvantages of each system, as well as the challenges associated with underground wireless communications.
Autors: Novak, T.;Snyder, D. P.;Kohler, J. L.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Apr 2010, volume: 46, issue:2, pages: 712 - 719
Publisher: IEEE
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» Power Conditioner for Variable-Frequency Drives in Offshore Oil Fields
Abstract:
The proliferation of variable-frequency ac motor drives (VFDs) as submersible pumps in oil exploration has aggravated many power-quality problems on the distribution network, for which VFDs are themselves susceptible to maloperation. The distortion in the input voltage waveform is a major issue, since the offshore power system cannot be regarded as a stiff source, and thus, distortions in the voltage waveform become more severe, which disturbs other loads connected at the point of common coupling (PCC). The oil fields require the operation of many parallel-connected VFDs on the same bus. Such a system significantly increases the power-quality problems on the distribution network. In this paper, an active power conditioner which is connected in series between the source and the PCC, and its dc bus shared with one of the VFDs connected to the bus, is proposed to mitigate a majority of power-quality problems for the whole bus. The proposed single power conditioner is sufficient to block the harmonic currents flowing toward the source, balance the currents from the source side, protect the VFDs on the bus against sag/swell at PCC, protect preinstalled passive filters connected with VFDs against series and parallel resonances, and maintain regulated balanced voltages at PCC. Investigations are carried out to validate the use of the proposed topology of a power conditioner to safeguard the distribution system and a set of VFDs against major power-quality problems. The proposed power conditioner employs a new control scheme based on an indirect current control for its effective operation under varying load conditions on different VFDs connected to the same bus.
Autors: Verma, V.;Singh, B.;Chandra, A.;Al-Haddad, K.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: Apr 2010, volume: 46, issue:2, pages: 731 - 739
Publisher: IEEE
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» Power generation confirmation of induction motors and influence on islanding detection devices
Abstract:
Photovoltaic generation systems must have protection devices and islanding detection devices if they are connected to utility lines of the electric power company. This is regulated in national technological requirement guidelines and the electric equipment technology standards. Islanding detection devices are installed to detect blackouts due to events such as ground faults and short circuits in utility lines. When an islanding detection device detects a power blackout, the photovoltaic generation system must be stopped immediately. It is known that islanding detection devices cannot detect islanding if induction motors are present among the loads. We investigated the influence of induction motors on islanding detection devices and found that when the frequency decreases after a utility line failure, induction motors change over to generator mode, thus compensating the active power imbalance and suppressing voltage variation. In addition, if the postfault frequency is adjusted by PLL control so as to maintain a fixed power factor, induction motors suppress this frequency change, thus extending islanding operation. It is clear from the above results that induction motors are more likely to produce islanding phenomena than static loads. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(4): 8-18, 2010; Published online in Wiley InterScience (). DOI 10.1002/eej.20962
Autors: Hironobu Igarashi, Takashi Sato, Kazunori Miyamoto, Kousuke Kurokawa
Appeared in: Electrical Engineering in Japan
Publication date: Apr 2010
Publisher: Wiley InterScience
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» Power Generation in Series Mode
Abstract:
This article presents the development and implementation of a 20-kW permanent magnet (PM) brushless dc (BLDC) machine starter/generator system for a series-parallel 2 x 2 hybrid electric vehicle.
Autors: Hasan, S.M.N.;Husain, I.;Veillette, R.J.;Carlotta, J.E.;
Appeared in: IEEE Industry Applications Magazine
Publication date: Apr 2010, volume: 16, issue:2, pages: 12 - 21
Publisher: IEEE
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» Power line communication networks for large-scale control and automation systems
Abstract:
Power line communications uses the existing power line infrastructure for communication purposes. While the majority of recent contributions have discussed PLC for high-data-rate applications like Internet access or multimedia communication serving a relatively small number of users, in this article we are concerned with PLC as an enabler for sensing, control, and automation in large systems comprising tens or even hundreds of components spread over relatively wide areas. Typical examples of such systems are energy management (Smart Grid) and facility automation systems. We provide a discussion of the communication network requirements common to such systems and present transmission concepts for PLC to make use of the existing infrastructure resources (i.e., power lines) to meet these requirements.
Autors: Bumiller, G.;Lampe, L.;Hrasnica, H.;
Appeared in: IEEE Communications Magazine
Publication date: Apr 2010, volume: 48, issue:4, pages: 106 - 113
Publisher: IEEE
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