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Electrical and Electronics Engineering publications abstract of: 01-2013 sorted by title, page: 0
» “On-the-Fly” Monitoring With a Single-Shot Terahertz Time-Domain Spectrometer
Abstract:
We demonstrate the application of a new and ultrafast terahertz (THz) time-domain spectrometer for the nondestructive evaluation of targets that are optically opaque and are composed of several subunits. Thanks to the single-shot capability and the kilohertz acquisition rate of the spectrometer, objects can be analyzed during free fall. The integrity of the objects and their structural subunits as packaging material can be verified by the large amount of information available from THz time-domain spectroscopy. The time of flight, overall absorption, and spectrally resolved absorption can be used to reconstruct the 2-D image along the vertical axis of movement and the depth of the objects.
Autors: Jeunesse, P.;Schmidhammer, U.;
Appeared in: IEEE Sensors Journal
Publication date: Jan 2013, volume: 13, issue:1, pages: 44 - 49
Publisher: IEEE
 
» 2012??A Great Year in the Student Chapter Development [Chapter News]
Abstract:
Autors: Magyar, P.;
Appeared in: IEEE Industry Applications Magazine
Publication date: Jan 2013, volume: 19, issue:1, pages: 106 - 109
Publisher: IEEE
 
» 3D Convolutional Neural Networks for Human Action Recognition
Abstract:
We consider the automated recognition of human actions in surveillance videos. Most current methods build classifiers based on complex handcrafted features computed from the raw inputs. Convolutional neural networks (CNNs) are a type of deep model that can act directly on the raw inputs. However, such models are currently limited to handling 2D inputs. In this paper, we develop a novel 3D CNN model for action recognition. This model extracts features from both the spatial and the temporal dimensions by performing 3D convolutions, thereby capturing the motion information encoded in multiple adjacent frames. The developed model generates multiple channels of information from the input frames, and the final feature representation combines information from all channels. To further boost the performance, we propose regularizing the outputs with high-level features and combining the predictions of a variety of different models. We apply the developed models to recognize human actions in the real-world environment of airport surveillance videos, and they achieve superior performance in comparison to baseline methods.
Autors: Ji, Shuiwang;Xu, Wei;Yang, Ming;Yu, Kai;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jan 2013, volume: 35, issue:1, pages: 221 - 231
Publisher: IEEE
 
» ??An Idea for Your Next Paper [From the Editor's Desk]
Abstract:
Autors: Floyd, L.;
Appeared in: IEEE Industry Applications Magazine
Publication date: Jan 2013, volume: 19, issue:1, pages: 2 - 2
Publisher: IEEE
 
» A Coaxial Time Constant Standard for the Determination of Phase Angle Errors of Current Shunts
Abstract:
This paper describes a new method to determine the phase angle errors of ac shunts by measuring the inductance and distributed capacitance. A 1- shunt of coaxial design has been developed as the time constant standard. A coaxial inductor with identical structure as the time constant standard has been developed. A four-terminal mutual inductor has also been built for the measurement of the inductance of the time constant standard. The method is based on the use of a binary inductive current divider to compare the inductor with the mutual inductor. The standard uncertainty of the inductance measurement of the time constant standard is within 28 pH at frequencies up to 200 kHz. The expanded uncertainty of the phase angle errors is from 0.4 at 1 kHz to 80.0 at 200 kHz at 1 A.
Autors: Pan, X.;Zhang, J.;Ma, X.;Gu, Y.;Liu, W.;Wang, B.;Lu, Z.;Zhang, D.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2013, volume: 62, issue:1, pages: 199 - 204
Publisher: IEEE
 
» A Data Fusion Technique for Wireless Ranging Performance Improvement
Abstract:
The increasing diffusion of mobile and portable devices provided with wireless connectivity makes the problem of distance measurement based on radio-frequency technologies increasingly important for the development of next-generation nomadic applications. In this paper, the performance limitations of two classic wireless ranging techniques based on received signal strength (RSS) and two-way time-of-flight (ToF) measurements, respectively, are analyzed and compared in detail. On the basis of this study, a data fusion algorithm is proposed to combine both techniques in order to improve ranging accuracy. The algorithm has been implemented and tested on the field using a dedicated embedded prototype made with commercial off-the-shelf components. Several experimental results prove that the combination of both techniques can significantly reduce measurement uncertainty. The results obtained with the developed prototype are not accurate enough for fine-grained position tracking in Ambient Assisted Living applications. However, the platform can be successfully used for reliable indoor zoning, e.g., for omnidirectional and adjustable hazard proximity detection. Most importantly, the proposed solution is absolutely general, and it is quite simple and light from the computational point of view. Accuracy could be further improved by using a more isotropic antenna and by integrating the ToF measurement technique at the lowest possible level on the same radio chip used for communication. Usually, this feature is not available in typical low-cost short-range wireless modules, e.g., for wireless sensor networks. Thus, the results of this research suggest that combining RSS with ToF measurements could be a viable solution for chip manufacturers interested in adding ranging capabilities to their radio modules.
Autors: Macii, D.;Colombo, A.;Pivato, P.;Fontanelli, D.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2013, volume: 62, issue:1, pages: 27 - 37
Publisher: IEEE
 
» A Derivation of the Recursive Solution to the Autocorrelation Normal Equations [Lecture Notes]
Abstract:
Norbert Wiener's formulation of extrapolation, interpolation, and smoothing of time series [8] naturally led to a set of linear equations referred to as autocorrelation normal equations (ACNE). In an appendix in [8], which was originally published as [4], Levinson presented an efficient recursive solution to ACNE later modified somewhat by Durbin [1]. This class of recursive solutions is typically referred to as the Levinson recursion or the Levinson Durbin recursion. The structure and efficiency of this class of solutions derives from the basic structure of the associated matrix, specifically the fact that it is a symmetric Toeplitz matrix, together with the relation of the righthand side of the matrix equation to the elements in the Toeplitz matrix. In this article, we derive a recursive solution to ACNE without reference to any of the motivating applications but exploiting the basic structure of the equations and straightforward properties of linear time-invariant (LTI) systems.
Autors: Baran, T.A.;Oppenheim, A.V.;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jan 2013, volume: 30, issue:1, pages: 142 - 144
Publisher: IEEE
 
» A Fast Clustering-Based Feature Subset Selection Algorithm for High-Dimensional Data
Abstract:
Feature selection involves identifying a subset of the most useful features that produces compatible results as the original entire set of features. A feature selection algorithm may be evaluated from both the efficiency and effectiveness points of view. While the efficiency concerns the time required to find a subset of features, the effectiveness is related to the quality of the subset of features. Based on these criteria, a fast clustering-based feature selection algorithm (FAST) is proposed and experimentally evaluated in this paper. The FAST algorithm works in two steps. In the first step, features are divided into clusters by using graph-theoretic clustering methods. In the second step, the most representative feature that is strongly related to target classes is selected from each cluster to form a subset of features. Features in different clusters are relatively independent, the clustering-based strategy of FAST has a high probability of producing a subset of useful and independent features. To ensure the efficiency of FAST, we adopt the efficient minimum-spanning tree (MST) clustering method. The efficiency and effectiveness of the FAST algorithm are evaluated through an empirical study. Extensive experiments are carried out to compare FAST and several representative feature selection algorithms, namely, FCBF, ReliefF, CFS, Consist, and FOCUS-SF, with respect to four types of well-known classifiers, namely, the probability-based Naive Bayes, the tree-based C4.5, the instance-based IB1, and the rule-based RIPPER before and after feature selection. The results, on 35 publicly available real-world high-dimensional image, microarray, and text data, demonstrate that the FAST not only produces smaller subsets of features but also improves the performances of the four types of classifiers.
Autors: Song, Qinbao;Ni, Jingjie;Wang, Guangtao;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jan 2013, volume: 25, issue:1, pages: 1 - 14
Publisher: IEEE
 
» A Geometrical Interpretation of Exponentially Embedded Families of Gaussian Probability Density Functions for Model Selection
Abstract:
Model selection via exponentially embedded families (EEF) of probability models has been shown to perform well on many practical problems of interest. A key component in utilizing this approach is the definition of a model origin (i.e. null hypothesis) which is embedded individually within each competing model. In this correspondence we give a geometrical interpretation of the EEF and study the sensitivity of the EEF approach to the choice of model origin in a Gaussian hypothesis testing framework. We introduce the information center (I-center) of competing models as an origin in this procedure and compare this to using the standard null hypothesis. Finally we derive optimality conditions for which the EEF using I-center achieves optimal performance in the Gaussian hypothesis testing framework.
Autors: Costa, R.;Kay, S.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Jan 2013, volume: 61, issue:1, pages: 62 - 67
Publisher: IEEE
 
» A Graph-Based Consensus Maximization Approach for Combining Multiple Supervised and Unsupervised Models
Abstract:
Ensemble learning has emerged as a powerful method for combining multiple models. Well-known methods, such as bagging, boosting, and model averaging, have been shown to improve accuracy and robustness over single models. However, due to the high costs of manual labeling, it is hard to obtain sufficient and reliable labeled data for effective training. Meanwhile, lots of unlabeled data exist in these sources, and we can readily obtain multiple unsupervised models. Although unsupervised models do not directly generate a class label prediction for each object, they provide useful constraints on the joint predictions for a set of related objects. Therefore, incorporating these unsupervised models into the ensemble of supervised models can lead to better prediction performance. In this paper, we study ensemble learning with outputs from multiple supervised and unsupervised models, a topic where little work has been done. We propose to consolidate a classification solution by maximizing the consensus among both supervised predictions and unsupervised constraints. We cast this ensemble task as an optimization problem on a bipartite graph, where the objective function favors the smoothness of the predictions over the graph, but penalizes the deviations from the initial labeling provided by the supervised models. We solve this problem through iterative propagation of probability estimates among neighboring nodes and prove the optimality of the solution. The proposed method can be interpreted as conducting a constrained embedding in a transformed space, or a ranking on the graph. Experimental results on different applications with heterogeneous data sources demonstrate the benefits of the proposed method over existing alternatives. (More information, data, and code are available at http://www.cse.buffalo.edu/~jing/integrate.htm.)
Autors: Gao, Jing;Liang, Feng;Fan, Wei;Sun, Yizhou;Han, Jiawei;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jan 2013, volume: 25, issue:1, pages: 15 - 28
Publisher: IEEE
 
» A Hybrid Multiview Stereo Algorithm for Modeling Urban Scenes
Abstract:
We present an original multiview stereo reconstruction algorithm which allows the 3D-modeling of urban scenes as a combination of meshes and geometric primitives. The method provides a compact model while preserving details: Irregular elements such as statues and ornaments are described by meshes, whereas regular structures such as columns and walls are described by primitives (planes, spheres, cylinders, cones, and tori). We adopt a two-step strategy consisting first in segmenting the initial mesh-based surface using a multilabel Markov Random Field-based model and second in sampling primitive and mesh components simultaneously on the obtained partition by a Jump-Diffusion process. The quality of a reconstruction is measured by a multi-object energy model which takes into account both photo-consistency and semantic considerations (i.e., geometry and shape layout). The segmentation and sampling steps are embedded into an iterative refinement procedure which provides an increasingly accurate hybrid representation. Experimental results on complex urban structures and large scenes are presented and compared to state-of-the-art multiview stereo meshing algorithms.
Autors: Lafarge, Florent;Keriven, Renaud;Br\édif, Mathieu;Vu, Hoang-Hiep;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jan 2013, volume: 35, issue:1, pages: 5 - 17
Publisher: IEEE
 
» A Low-Cost High-Performance Digital Radar Test Bed
Abstract:
This paper describes the design of a dual-channel S-band digital radar test bed. The test bed combines stretch processing with a novel and cost-effective hardware architecture that enables it to achieve an in-band dynamic range of 60 dB over 600 MHz of instantaneous bandwidth. The dual digital receiver channels allow for adaptive digital beamforming which can be used to mitigate a directional source of interference. Experimental test and verification results are presented to demonstrate system performance.
Autors: Mir, H. S.;Albasha, L.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2013, volume: 62, issue:1, pages: 221 - 229
Publisher: IEEE
 
» A Low-Cost, Disposable, and Contactless Resonant Mass Sensor
Abstract:
Low-cost and disposable sensors are becoming strategic for several applications particularly when devices must operate in hostile environments involving contaminants or irreversible processes. The device presented in this paper is a low-cost contactless mass sensor realized by a rapid prototyping technique. The sensor can be suitable for chemical and biomedical applications due to the disposable nature of the sensing element. The latter is a flexible cantilever beam partially covered by a paramagnetic nanoparticle layer and driven into an oscillating regime by a magnetic actuation. The beam deflection, which is strictly correlated to the target mass, is estimated by a remote inductive readout strategy. The device architecture is presented along with models and simulations allowing the prediction of its sensing features. Moreover, the real behavior of the device is discussed through experimental results confirming the suitability of the proposed sensing strategy.
Autors: Ando, B.;Baglio, S.;L'Episcopo, G.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2013, volume: 62, issue:1, pages: 246 - 252
Publisher: IEEE
 
» A Model-Based Approach for Dual-Burst Processing of Laser Profile Velocimetry Signals
Abstract:
In order to characterize turbulent flows, correlation measurements are a common procedure. Laser Doppler sensors are often applied for this task, but in the case of high seeding concentrations, the so-called dual-burst signals occur. These are caused by multiple particles passing the measurement volume at the same time. In this paper, a model-based signal processing approach is presented which is able to evaluate such distorted signals. In order to assess the performance of dual-burst algorithms, the Cramér–Rao lower bound is calculated for the first time. A comparison of this new technique with conventional dual-burst algorithms reveals a systematic error which is at least seven times lower and even makes an evaluation of the complete signal in some cases possible in the first place. As a result, the total frequency estimation uncertainty of dual-burst signals, which is directly linked to the velocity uncertainty, is improved by a factor of five and more. Hence, this new technique enables the precise evaluation of correlation functions and instantaneous velocity gradients of complex flows.
Autors: Neumann, M.;Fischer, A.;Czarske, J.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2013, volume: 62, issue:1, pages: 83 - 94
Publisher: IEEE
 
» A New Measurement Method Based on Music Algorithm for Through-the-Wall Detection of Life Signs
Abstract:
A new measurement method for through-the-wall detection of life signs is proposed hereinafter. The method analyzes the phase modulation that a sinusoidal signal, generated by means of a proper continuous-wave microwave transceiver, undergoes when reflected by the chest periodic displacement associated with breathing. It takes advantage of a suitable spatial smoothing decorrelation strategy applied to the traditional algorithm for MUltiple SIgnal Classification (MUSIC), mandated to single out the spectral components of the received phase signal. With respect to other measurement solutions, already available in the literature and exploiting either the traditional discrete-time Fourier transform, or matched filters, or standard singular value decomposition, the proposed method assures competitive performance in detecting the respiratory activity from the received microwave signal and effective noise/clutter rejection. The results of several tests both in simulated and actual scenarios, i.e., people behind walls in a furnished room, prove the efficacy and reliability of the method also in the presence of critical measurement conditions such as low signal-to-noise ratios and chest displacement associated with shallow breathing.
Autors: Ascione, M.;Buonanno, A.;D'Urso, M.;Angrisani, L.;Schiano Lo Moriello, R.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2013, volume: 62, issue:1, pages: 13 - 26
Publisher: IEEE
 
» A Portable High-Resolution Surface Measurement Device
Abstract:
A high-resolution portable surface measurement device has been demonstrated to provide micrometer-resolution topographical plots. This device was specifically developed to allow in situ measurements of defects on the Space Shuttle orbiter windows but is versatile enough to be used on a wide variety of surfaces. This paper discusses the choice of an optical sensor and then the decisions required to convert a laboratory bench optical measurement device into an ergonomic portable system. The necessary tradeoffs between performance and portability are presented along with a description of the device developed to measure orbiter window defects.
Autors: Ihlefeld, C. M.;Burns, B. M.;Youngquist, R. C.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2013, volume: 62, issue:1, pages: 205 - 209
Publisher: IEEE
 
» A Probabilistic Approach to Spectral Graph Matching
Abstract:
Spectral Matching (SM) is a computationally efficient approach to approximate the solution of pairwise matching problems that are np-hard. In this paper, we present a probabilistic interpretation of spectral matching schemes and derive a novel Probabilistic Matching (PM) scheme that is shown to outperform previous approaches. We show that spectral matching can be interpreted as a Maximum Likelihood (ML) estimate of the assignment probabilities and that the Graduated Assignment (GA) algorithm can be cast as a Maximum a Posteriori (MAP) estimator. Based on this analysis, we derive a ranking scheme for spectral matchings based on their reliability, and propose a novel iterative probabilistic matching algorithm that relaxes some of the implicit assumptions used in prior works. We experimentally show our approaches to outperform previous schemes when applied to exhaustive synthetic tests as well as the analysis of real image sequences.
Autors: Egozi, Amir;Keller, Yosi;Guterman, Hugo;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jan 2013, volume: 35, issue:1, pages: 18 - 27
Publisher: IEEE
 
» A Quantitative Model and Analysis of Information Confusion in Social Networks
Abstract:
Information consumers in online social networks receive information from multiple information providers, which results in confusion. The amount of confusion depends on three main factors—(a) attributes of the source, (b) characteristics of the consumer and (c) trust relation between the information provider and the consumer. While information confusion has been qualitatively observed in social networks, no quantitative model or analysis was presented. We present the first quantitative model to analyze confusion in the presence of multiple information providers. We address the following fundamental issues—(i) What is a good model for confusion? (ii) How does the quality of information degrade due to confusion? (iii) What are good strategies for the information providers to control the power or the intensity with which the information is transmitted? The scenario is modeled as a non-cooperative game with pricing, whose Nash equilibrium provides the solution to the questions posed above. We use data from Twitter (e.g., on full body scan in airports) and diabetes outreach networks to illustrate the analysis. We use the solution of the non-cooperative game to study the confusion levels of consumers, in terms of the aggressiveness and passiveness of the information providers. Results indicate that confusion levels are high in in networks in which all information providers are equally trusted. In networks where information providers are unequally trusted, the confusion levels are moderate.
Autors: Anand, S.;Subbalakshmi, K. P.;Chandramouli, R.;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jan 2013, volume: 15, issue:1, pages: 207 - 223
Publisher: IEEE
 
» A Resource Allocation Scheme for Scalable Video Multicast in WiMAX Relay Networks
Abstract:
This paper proposes the first resource allocation scheme in the literature to support scalable-video multicast for WiMAX relay networks. We prove that when the available bandwidth is limited, the bandwidth allocation problems of 1) maximizing network throughput and 2) maximizing the number of satisfied users are NP-hard. To find the near-optimal solutions to this type of maximization problem in polynomial time, this study first proposes a greedy weighted algorithm, GWA, for bandwidth allocation. By incorporating table-consulting mechanisms, the proposed GWA can intelligently avoid redundant bandwidth allocation and thus accomplish high network performance (such as high network throughput or large number of satisfied users). To maintain the high performance gained by GWA and simultaneously improve its worst case performance, this study extends GWA to a bounded version, BGWA, which guarantees that its performance gains are lower bounded. This study shows that the computational complexity of BGWA is also in polynomial time and proves that BGWA can provide at least 1/ρ times the performance of the optimal solution, where rho is a finite value no less than one. Finally, simulation results show that the proposed BGWA bandwidth allocation scheme can effectively achieve different performance objectives with different parameter settings.
Autors: Sheu, Jang-Ping;Kao, Chien-Chi;Yang, Shun-Ren;Chang, Lee-Fan;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jan 2013, volume: 12, issue:1, pages: 90 - 104
Publisher: IEEE
 
» A Robust Technique for Motion-Based Video Sequences Temporal Alignment
Abstract:
In this paper, we propose a robust technique for temporal alignment of video sequences with similar planar motions acquired using uncalibrated cameras. In this technique, we model the motion-based video temporal alignment problem as a spatio-temporal discrete trajectory point sets alignment problem. First, the trajectory of the object of interest is tracked throughout the videos. A probabilistic method is then developed to calculate the ‘soft’ spatial correspondence between the trajectory point sets. Next, a dynamic time warping technique (DTW) is applied to the spatial correspondence information to compute the temporal alignment of the videos. The experimental results show that the proposed technique provides a superior performance over existing techniques for videos with similar trajectory patterns.
Autors: Lu, C.;Mandal, M.;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jan 2013, volume: 15, issue:1, pages: 70 - 82
Publisher: IEEE
 
» A Saliency Detection Model Using Low-Level Features Based on Wavelet Transform
Abstract:
Researchers have been taking advantage of visual attention in various image processing applications such as image retargeting, video coding, etc. Recently, many saliency detection algorithms have been proposed by extracting features in spatial or transform domains. In this paper, a novel saliency detection model is introduced by utilizing low-level features obtained from the wavelet transform domain. Firstly, wavelet transform is employed to create the multi-scale feature maps which can represent different features from edge to texture. Then, we propose a computational model for the saliency map from these features. The proposed model aims to modulate local contrast at a location with its global saliency computed based on the likelihood of the features, and the proposed model considers local center-surround differences and global contrast in the final saliency map. Experimental evaluation depicts the promising results from the proposed model by outperforming the relevant state of the art saliency detection models.
Autors: Imamoglu, N.;Lin, W.;Fang, Y.;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jan 2013, volume: 15, issue:1, pages: 96 - 105
Publisher: IEEE
 
» A Steerable, Multiscale Singularity Index
Abstract:
We propose a new steerable, multiscale ratio index for detecting impulse singularities in signals of arbitrary dimensionality. For example, it responds strongly to curvilinear masses (ridges) in images, but minimally to step discontinuities. The ratio index employs directional derivatives of gaussians, making it naturally steerable and scalable. Experiments on real images demonstrate the efficacy of the index for detecting multiscale curvilinear structures. A software version of the index can be downloaded from: http://live.ece.utexas.edu/research/SingularityIndex/SingularityIndex.zip.
Autors: Muralidhar, G. S.;Bovik, A. C.;Markey, M. K.;
Appeared in: IEEE Signal Processing Letters
Publication date: Jan 2013, volume: 20, issue:1, pages: 7 - 10
Publisher: IEEE
 
» A Survey of XML Tree Patterns
Abstract:
With XML becoming a ubiquitous language for data interoperability purposes in various domains, efficiently querying XML data is a critical issue. This has lead to the design of algebraic frameworks based on tree-shaped patterns akin to the tree-structured data model of XML. Tree patterns are graphic representations of queries over data trees. They are actually matched against an input data tree to answer a query. Since the turn of the 21st century, an astounding research effort has been focusing on tree pattern models and matching optimization (a primordial issue). This paper is a comprehensive survey of these topics, in which we outline and compare the various features of tree patterns. We also review and discuss the two main families of approaches for optimizing tree pattern matching, namely pattern tree minimization and holistic matching. We finally present actual tree pattern-based developments, to provide a global overview of this significant research topic.
Autors: Hachicha, Marouane;Darmont, J\ér\ôme;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jan 2013, volume: 25, issue:1, pages: 29 - 46
Publisher: IEEE
 
» A Tour of Modern Image Filtering: New Insights and Methods, Both Practical and Theoretical
Abstract:
Recent developments in computational imaging and restoration have heralded the arrival and convergence of several powerful methods for adaptive processing of multidimensional data. Examples include moving least square (from graphics), the bilateral filter (BF) and anisotropic diffusion (from computer vision), boosting, kernel, and spectral methods (from machine learning), nonlocal means (NLM) and its variants (from signal processing), Bregman iterations (from applied math), kernel regression, and iterative scaling (from statistics). While these approaches found their inspirations in diverse fields of nascence, they are deeply connected.
Autors: Milanfar, P.;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jan 2013, volume: 30, issue:1, pages: 106 - 128
Publisher: IEEE
 
» A Two Sweeping VCO Source for Heterodyne FMCW Radar
Abstract:
We propose and develop a heterodyne frequency modulated continuous wave (FMCW) radar system. The system operates at 14 GHz with a 500-MHz bandwidth in a 100- sweeping period, based on two wideband linear RF voltage-controlled oscillator (VCO) sweeping sources, which are controlled by a direct digital synthesizer (DDS) through a phase-locked scheme, leading to a high linearity of the frequency chirping signal. To achieve low phase noise, the RF signals are synthesized from low-noise baseband signals which are generated through a generation scheme of using phase-locked oscillators operating in the 800-MHz frequency range. Additionally, the proposed architecture can eliminate the phase noise contributions and/or frequency deviation due to the uncorrelation of different VCOs. The results are verified through measurements and derivation.
Autors: Dao, M.-T.;Shin, D.-H.;Im, Y.-T.;Park, S.-O.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2013, volume: 62, issue:1, pages: 230 - 239
Publisher: IEEE
 
» Adaptive Network Coding for Broadband Wireless Access Networks
Abstract:
Broadband wireless access (BWA) networks, such as LTE and WiMAX, are inherently lossy due to wireless medium unreliability. Although the Hybrid Automatic Repeat reQuest (HARQ) error-control method recovers from packet loss, it has low transmission efficiency and is unsuitable for delay-sensitive applications. Alternatively, network coding techniques improve the throughput of wireless networks, but incur significant overhead and ignore network constraints such as Medium Access Control (MAC) layer transmission opportunities and physical (PHY) layer channel conditions. The present study provides analysis of Random Network Coding (RNC) and Systematic Network Coding (SNC) decoding probabilities. Based on the analytical results, SNC is selected for developing an adaptive network coding scheme designated as Frame-by-frame Adaptive Systematic Network Coding (FASNC). According to network constraints per frame, FASNC dynamically utilizes either Modified Systematic Network Coding (M-SNC) or Mixed Generation Coding (MGC). An analytical model is developed for evaluating the mean decoding delay and mean goodput of the proposed FASNC scheme. The results derived using this model agree with those obtained from computer simulations. Simulations show that FASNC results in both lower decoding delay and reduced buffer requirements compared to MRNC and {cal N}-in-1 ReTX, while also yielding higher goodput than HARQ, MRNC, and {cal N}-in-1 ReTX.
Autors: Lin, Hui-Tang;Lin, Ying-You;Kang, Hung-Jung;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jan 2013, volume: 24, issue:1, pages: 4 - 18
Publisher: IEEE
 
» Advances in Electroencephalography Signal Processing [Life Sciences]
Abstract:
Over the past three decades of invention and refinement of neuroimaging techniques, our understanding of the brain has been remarkably enhanced. Today, there are several tools and methods by which neuroscientists and radiologists can discover more information about brain function. Yet, most of these methods have their roots in Walter Dandy's ventriculography (X-ray imaging of the brain) in the 1910s and the ground breaking work of Hans Beger in recording brain electrical activity [electroencephalography (EEG)] in the 1920s. Since then, the techniques in both acquisition and analysis of these signals have been significantly improved.
Autors: Sanei, S.;Ferdowsi, S.;Nazarpour, K.;Cichocki, A.;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jan 2013, volume: 30, issue:1, pages: 170 - 176
Publisher: IEEE
 
» Affinity Learning with Diffusion on Tensor Product Graph
Abstract:
In many applications, we are given a finite set of data points sampled from a data manifold and represented as a graph with edge weights determined by pairwise similarities of the samples. Often the pairwise similarities (which are also called affinities) are unreliable due to noise or due to intrinsic difficulties in estimating similarity values of the samples. As observed in several recent approaches, more reliable similarities can be obtained if the original similarities are diffused in the context of other data points, where the context of each point is a set of points most similar to it. Compared to the existing methods, our approach differs in two main aspects. First, instead of diffusing the similarity information on the original graph, we propose to utilize the tensor product graph (TPG) obtained by the tensor product of the original graph with itself. Since TPG takes into account higher order information, it is not a surprise that we obtain more reliable similarities. However, it comes at the price of higher order computational complexity and storage requirement. The key contribution of the proposed approach is that the information propagation on TPG can be computed with the same computational complexity and the same amount of storage as the propagation on the original graph. We prove that a graph diffusion process on TPG is equivalent to a novel iterative algorithm on the original graph, which is guaranteed to converge. After its convergence we obtain new edge weights that can be interpreted as new, learned affinities. We stress that the affinities are learned in an unsupervised setting. We illustrate the benefits of the proposed approach for data manifolds composed of shapes, images, and image patches on two very different tasks of image retrieval and image segmentation. With learned affinities, we achieve the bull's eye retrieval score of 99.99 percent on the MPEG-7 shape dataset, which is much higher than the state-of-the-art algorithms. When the data- points are image patches, the NCut with the learned affinities not only significantly outperforms the NCut with the original affinities, but it also outperforms state-of-the-art image segmentation methods.
Autors: Yang, Xingwei;Prasad, Lakshman;Latecki, Longin Jan;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jan 2013, volume: 35, issue:1, pages: 28 - 38
Publisher: IEEE
 
» Aluminum-doped zinc oxide formed by atomic layer deposition for use as anodes in organic light emitting diodes
Abstract:
Aluminum-doped zinc oxide films produced by atomic layer deposition were investigated for use as anodes in organic light emitting diode (OLED) devices. Al-doped ZnO (AZO) films (∼200 nm thick) were deposited at temperatures of 200, 230, and 260 °C and the AZO film deposited at 260 °C demonstrated carrier mobility, carrier concentration, resistivity, and transmittance values of 16.2 cm2 V-1 s-1, 5.18 × 1020 cm-3, 7.34 × 10-4 Ω cm, and 90%, respectively. OLED devices with a DNTPD/TAPC/Bebq2:10% doped RP-411/Bphen/LiF/Al structure on a glass substrate fabricated using an AZO anode formed at 260 °C showed turn-on voltage, maximum luminance, and current efficiency values of 5.3 V, 16680 cd/m2, and 4.8 cd/A, respectively.
Autors: Gong, Su Cheol;Choi, Yong-June;Kim, Hyuncheol;Park, Chang-Sun;Park, Hyung-Ho;Jang, Ji Geun;Chang, Ho Jung;Yeom, Geun Young;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A101 - 01A101-6
Publisher: IEEE
 
» An Access Point-Based FEC Mechanism for Video Transmission Over Wireless LANs
Abstract:
Forward Error Correction (FEC) is one of the most common means of performing packet error recovery in data transmissions. FEC schemes typically tune the FEC rate in accordance with feedback information provided by the receiver. However, the feedback and FEC rate calculation processes inevitably have a finite duration, and thus the FEC rate implemented at the sender may not accurately reflect the current state of the network. Thus, this paper proposes an Enhanced Random Early Detection Forward Error Correction (ERED-FEC) mechanism to improve the quality of video transmissions over Wireless Local Area Networks (WLANs). In contrast to most FEC schemes, the FEC redundancy rate is calculated directly at the Access Point (AP). Moreover, the redundancy rate is tuned in accordance with both the wireless channel condition (as indicated by the number of packet retransmissions) and the network traffic load (as indicated by the AP queue length). The experimental results show that the proposed ERED-FEC mechanism achieves a significant improvement in the video quality compared to existing FEC schemes without introducing an excessive number of redundant packets into the network.
Autors: Lin, C.-H.;Shieh, C.-K.;Hwang, W.-S.;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jan 2013, volume: 15, issue:1, pages: 195 - 206
Publisher: IEEE
 
» An Investigation on LTE Mobility Management
Abstract:
Mobility management in Long Term Evolution (LTE) is different from that in the third generation mobile telecom networks. In LTE, the Mobility Management Entity (MME) is responsible for the mobility management function. The MME is connected to a large number of evolved Node Bs (cells) that are grouped into the Tracking Areas (TAs). The TAs are further grouped into TA Lists (TALs). When a User Equipment (UE) moves out of the current TAL, it reports its new location to the MME. If the LTE network attempts to connect to the UE, the MME asks the cells in the TAL to page the UE. In LTE paging, the MME may sequentially page a cell, the TA of the cell, and/or the TAL of the cell. This paper investigates the performance of LTE paging, and provides the guidelines for the best paging sequence of cells.
Autors: Liou, Ren-Huang;Lin, Yi-Bing;Tsai, Shang-Chih;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jan 2013, volume: 12, issue:1, pages: 166 - 176
Publisher: IEEE
 
» Applications of Signal Processing in Engineering and Beyond [From the Editors]
Abstract:
IEEE Signal Processing Magazine (SPM) is a tutorial-style magazine that brings to the signal processing community bimonthly survey articles of the most recent advances in signal processing theory and applications. For this issue, the Editor-in-Chief invited Andrea Cavallaro and Andres Kwasinski, the area editors for columns and forum, to write a brief on their editorial work.
Autors: Zoubir, A.;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jan 2013, volume: 30, issue:1, pages: 2 - 2
Publisher: IEEE
 
» Atomic layer deposition of Al-doped ZnO thin films
Abstract:
Atomic layer deposition has been used to fabricate thin films of aluminum-doped ZnO by depositing interspersed layers of ZnO and Al2O3 on borosilicate glass substrates. The growth characteristics of the films have been investigated through x-ray diffraction, x-ray reflection, and x-ray fluorescence measurements, and the efficacy of the Al doping has been evaluated through optical reflectivity and Seebeck coefficient measurements. The Al doping is found to affect the carrier density of ZnO up to a nominal Al dopant content of 5 at. %. At nominal Al doping levels of 10 at. % and higher, the structure of the films is found to be strongly affected by the Al2O3 phase and no further carrier doping of ZnO is observed.
Autors: Tynell, Tommi;Yamauchi, Hisao;Karppinen, Maarit;Okazaki, Ryuji;Terasaki, Ichiro;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A109 - 01A109-4
Publisher: IEEE
 
» Atomic layer deposition of Al2O3 and AlxTi1-xOy thin films on N2O plasma pretreated carbon materials
Abstract:
A mild N2O plasma treatment technique (low power and low substrate temperature) for carbon materials' (including graphite and carbon nanotubes) functionalization followed by subsequent high-k dielectric atomic layer deposition (ALD) was developed. It was shown that N2O plasma carbon functionalization leads to the formation of epoxide and carboxylic groups on the carbon surface which act as active centers for ALD and, as a result, conformal and uniform Al2O3 and TixAl1-xOy films' growth occurred on the carbon surfaces. It was shown that the electrical properties of multinary TixAl1-xOy oxides are more promising in comparison to single Al2O3 oxide. Some electrical properties of the TixAl1-xOy films observed were a high dielectric constant ∼19, low leakage current density (<3 × 10-5 A/cm2 at 1 MV/cm), and high breakdown field (∼5.5 MV/cm).
Autors: Markeev, Andrey M.;Chernikova, Anna G.;Chouprik, Anastasya A.;Zaitsev, Sergey A.;Ovchinnikov, Dmitry V.;Althues, Holger;Dorfler, Susanne;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A135 - 01A135-5
Publisher: IEEE
 
» Atomic layer deposition of aluminum-doped zinc oxide films for the light harvesting enhancement of a nanostructured silicon solar cell
Abstract:
Anodic-aluminum-oxide (AAO) template lithography and atomic layer deposition (ALD) antireflection coating techniques have often been applied for the fabrication of wide-angle antireflection structures on silicon solar cells. In this study, an AAO template was fabricated as a mask to block the high density plasma dry etching from the crystalline silicon to form nanostructures on the surface of the crystalline silicon wafer. Then, a 55-nm-thick aluminum-doped zinc oxide (AZO) film was deposited on the silicon nanostructures using the ALD method. The results show that the application of a nanostructured AZO film can decrease the average reflectivity of the crystalline silicon to 0.83% in the wavelength range from 400 to 850 nm for an incident angle of 8°. The conversion efficiency of the nanostructured silicon solar cell can be enhanced from 6.93% to 8.37%.
Autors: Chen, Sheng-Hui;Chan, Shih-Hao;Chen, Chun-Ko;Tseng, Shao-Ze;Hsu, Chieh-Hsiang;Cho, Wen-Hao;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A125 - 01A125-5
Publisher: IEEE
 
» Atomic layer deposition of anatase TiO2 on porous electrodes for dye-sensitized solar cells
Abstract:
Thin TiO2 films were grown by atomic layer deposition on planar and porous substrates and characterized by Raman spectroscopy, x-ray diffraction, high resolution transmission electron microscopy, and spectroscopic ellipsometry. The growth conditions of anatase TiO2 are investigated, motivated by the application in dye-sensitized solar cells, where best results are achieved with electrodes based on anatase TiO2. To enforce an anatase TiO2 growth on substrates stimulating rutile growth, a symmetry breaking ultra thin buffer layer of five cycles Al2O3 was introduced. With this buffer layer anatase TiO2 deposition was demonstrated on planar rutile TiO2 substrates. However, it was found that the necessity of the buffer layer depends on the substrate structure. On porous TiO2 electrodes containing a mixture of anatase and rutile TiO2 domains, a direct anatase TiO2 growth was possible even without a buffer layer.
Autors: Dirnstorfer, Ingo;Mahne, Hannes;Mikolajick, Thomas;Knaut, Martin;Albert, Matthias;Dubnack, Kristina;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A116 - 01A116-5
Publisher: IEEE
 
» Atomic layer deposition of Ti-HfO2 dielectrics
Abstract:
Titanium-doped hafnium oxide films, TixHf1-xO2-δ, have been deposited with a Ti content of x = 0.1 and x = 0.5, by atomic layer deposition. The TixHf1-xO2-δ growth rate is lower compared with the growth rates of the individual binary oxides; however, the composition of the films is unaffected by the reduced growth rate. An 850  °C spike anneal and a 500  °C 30 min furnace anneal were performed, and the resulting film composition and structure was determined using medium energy ion scattering, x-ray diffraction, and transmission electron microscopy. The Ti0.1Hf0.9O2-δ films readily crystallize into a monoclinic phase during both types of annealing. By contrast, the Ti0.5Hf0.5O2-δ films remain amorphous during both annealing processes. Electrical characterization of the as-deposited Ti0.1Hf0.9O2-δ films yielded a dielectric constant of 20, which is slightly higher than undoped HfO2 films. The as-deposited Ti0.5Hf0.5O2-δ films showed a significant increase in dielectric constant up to 35. After a 500  °C 30 min anneal, the dielectric constant reduced slightly to 27. The leakage current density of the amorphous film remains relatively unaffected at 8.7×10-7 A/cm2 at -1 MV/cm, suggesting this composition/heat treatment is a candidate for future device dielectrics.
Autors: Werner, Matthew;King, Peter J.;Hindley, Sarah;Romani, Simon;Mather, Sean;Chalker, Paul R.;Williams, Paul A.;van den Berg, Jakob A.;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A102 - 01A102-7
Publisher: IEEE
 
» Atomic layer deposition of zinc indium sulfide films: Mechanistic studies and evidence of surface exchange reactions and diffusion processes
Abstract:
The authors present the elaboration of zinc indium sulfide (ZnInxSy) thin films in the context of a cadmium-free buffer layer development for copper indium gallium diselenide photovoltaic solar cells. The films were deposited by atomic layer deposition (ALD) from ZnEt2 (DEZ), In(acac)3 (acac = acetylacetonate), and H2S at 200 °C. In situ growth kinetics studies were performed with the quartz crystal microbalance technique to determine the respective mass gain per cycle of ZnS and In2S3 layers, allowing determination of the atomic compositions of the ZnInxSy thin films to be expected if the deposition strictly follows the rule of mixtures. As the experimental atomic compositions of the ZnInxSy films differ significantly from this rule, a comprehensive study of the growth mechanism was performed to determine the nature of the side reactions. First, an exchange reaction between In2S3 and the Zn precursor was identified, though this process is not sufficient to account for the experimental data, and therefore, a second process which corresponds to the diffusion of species within the film was also found to take place. Ultimately, the atomic compositions of the ZnInxSy films can be explained by a rate-limited exchange reaction at the surface between DEZ and the In2S3 layer, combined with diffusion of the species in the whole film. More generally, such side reactions should be considered in ALD of multinary compounds, even at low temperature.
Autors: Genevee, Pascal;Donsanti, Frederique;Schneider, Nathanaelle;Lincot, Daniel;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A131 - 01A131-6
Publisher: IEEE
 
» Atomic layer deposition of zinc sulfide with Zn(TMHD)2
Abstract:
The atomic layer deposition (ALD) of ZnS films with Zn(TMHD)2 and in situ generated H2S as precursors was investigated, over a temperature range of 150–375 °C. ALD behavior was confirmed by investigation of growth behavior and saturation curves. The properties of the films were studied with atomic force microscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, ultraviolet–visible–infrared spectroscopy, and extended x-ray absorption fine structure. The results demonstrate a film that can penetrate a porous matrix, with a local Zn structure of bulk ZnS, and a band gap between 3.5 and 3.6 eV. The ZnS film was used as a buffer layer in nanostructured PbS quantum dot solar cell devices.
Autors: Short, Andrew;Jewell, Leila;Doshay, Sage;Church, Carena;Keiber, Trevor;Bridges, Frank;Carter, Sue;Alers, Glenn;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A138 - 01A138-5
Publisher: IEEE
 
» Atomic layer deposition onto carbon fiber: From single layer deposition via multilayer structure to metal oxide microtubes
Abstract:
Layers of alumina, titania and double layers of alumina/titania (and reverse) were deposited onto bundles of carbon fibers in an atomic layer deposition process. Scanning electron microscopy (SEM) images of the coated carbon fibers revealed that each fiber of a bundle was coated homogenously and separately and that no bridges were formed between the fibers. Transmission electron microscopy and SEM images showed that the coating was conformal, uniform, had a good adhesion to the fiber surface and that the morphology of the coating surface was similar to that of fiber surface. In case of double layers, the average deposition rate of coatings did not depend on the sequence of layer deposition. After coating, the carbon fibers were selectively removed by thermal oxidation in air at temperatures of 550 °C and 900 °C, leading to metal oxide microtubes.
Autors: Knohl, Stefan;Kumar Roy, Amit;Goedel, Werner A.;Schulze, Steffen;Hietschold, Michael;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A139 - 01A139-7
Publisher: IEEE
 
» Atomically precise surface engineering of silicon CCDs for enhanced UV quantum efficiency
Abstract:
The authors report here on a new technique, combining the atomic precision of molecular beam epitaxy and atomic layer deposition, to fabricate back illuminated silicon CCD detectors that demonstrate world record detector quantum efficiency (>50%) in the near and far ultraviolet (155–300 nm). This report describes in detail the unique surface engineering approaches used and demonstrates the robustness of detector performance that is obtained by achieving atomic level precision at key steps in the fabrication process. The characterization, materials, and devices produced in this effort will be presented along with comparison to other approaches.
Autors: Greer, Frank;Hamden, Erika;Jacquot, Blake C.;Hoenk, Michael E.;Jones, Todd J.;Dickie, Matthew R.;Monacos, Steve P.;Nikzad, Shouleh;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A103 - 01A103-9
Publisher: IEEE
 
» Automatic Semantic Content Extraction in Videos Using a Fuzzy Ontology and Rule-Based Model
Abstract:
Recent increase in the use of video-based applications has revealed the need for extracting the content in videos. Raw data and low-level features alone are not sufficient to fulfill the user 's needs; that is, a deeper understanding of the content at the semantic level is required. Currently, manual techniques, which are inefficient, subjective and costly in time and limit the querying capabilities, are being used to bridge the gap between low-level representative features and high-level semantic content. Here, we propose a semantic content extraction system that allows the user to query and retrieve objects, events, and concepts that are extracted automatically. We introduce an ontology-based fuzzy video semantic content model that uses spatial/temporal relations in event and concept definitions. This metaontology definition provides a wide-domain applicable rule construction standard that allows the user to construct an ontology for a given domain. In addition to domain ontologies, we use additional rule definitions (without using ontology) to lower spatial relation computation cost and to be able to define some complex situations more effectively. The proposed framework has been fully implemented and tested on three different domains. We have obtained satisfactory precision and recall rates for object, event and concept extraction.
Autors: Yildirim, Yakup;Yazici, Adnan;Yilmaz, Turgay;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jan 2013, volume: 25, issue:1, pages: 47 - 61
Publisher: IEEE
 
» Bidirectional Optical Amplification in Long-Distance Two-Way Fiber-Optic Time and Frequency Transfer Systems
Abstract:
In this paper, the transmission of the time and/or frequency signals (e.g., 1 pulse per second and 10 MHz) coded on the optical carrier by means of an on–off intensity modulation in the two-way fiber-optic link is considered. It is assumed that the bidirectional optical amplification in the single piece of an erbium-doped fiber is exploited to compensate the attenuation of the optical path. Such configuration of the amplifiers, offering the highest possible symmetry of the propagation conditions in both directions, is well suited for the two-way transfer method exploiting the symmetry of the link. We proposed the method of estimating interfering signals and jitter, which appear at both sides of such bidirectional fiber link because of Rayleigh backscattering and amplified spontaneous emission. This method is further exploited for finding the gains of bidirectional amplifiers, allowing optimization of the performance of the link. The experiments done with 120- and 220-km-long links, incorporating one and three amplifiers, respectively, confirmed theoretical predictions and proved that the single-path bidirectional amplifiers without any components separating the directions are useful for time or RF frequency transfer. During the experiments, both field-deployed telecommunication cables and the fibers spooled in the laboratory were used. Presented methods of analysis and optimization are useful for designing and evaluating the fiber-optic links incorporating single-path bidirectional fiber-optic amplifiers and exploiting intensity modulation for time and/or frequency transfer.
Autors: Sliwczynski, Ł.;Kolodziej, J.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2013, volume: 62, issue:1, pages: 253 - 262
Publisher: IEEE
 
» Binary Tree Slotted ALOHA for Passive RFID Tag Anticollision
Abstract:
In order to enhance the efficiency of radio frequency identification (RFID) and lower system computational complexity, this paper proposes three novel tag anticollision protocols for passive RFID systems. The three proposed protocols are based on a binary tree slotted ALOHA (BTSA) algorithm. In BTSA, tags are randomly assigned to slots of a frame and if some tags collide in a slot, the collided tags in the slot will be resolved by binary tree splitting while the other tags in the subsequent slots will wait. The three protocols utilize a dynamic, an adaptive, and a splitting method to adjust the frame length to a value close to the number of tags, respectively. For BTSA, the identification efficiency can achieve an optimal value only when the frame length is close to the number of tags. Therefore, the proposed protocols efficiency is close to the optimal value. The advantages of the protocols are that, they do not need the estimation of the number of tags, and their efficiency is not affected by the variance of the number of tags. Computer simulation results show that splitting BTSA's efficiency can achieve 0.425, and the other two protocols efficiencies are about 0.40. Also, the results show that the protocols efficiency curves are nearly horizontal when the number of tags increases from 20 to 4,000.
Autors: Wu, Haifeng;Zeng, Yu;Feng, Jihua;Gu, Yu;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jan 2013, volume: 24, issue:1, pages: 19 - 31
Publisher: IEEE
 
» Bioinspired Design for Body Sensor Networks [Life Sciences]
Abstract:
At an age when information access is no longer limited by physical barriers or distances, the desire to have continuous sensing and monitoring, rather than simple episodic or snapshot measurements represents the current trend in almost all sensing applications ranging from environment, transport, and infrastructure to well being, sports, and health care. The term body sensor network (BSN) was coined to harness several allied technologies that underpin the development of pervasive sensing for health care, well being, sports, and other applications that require “ubiquitous” and “pervasive” monitoring of physical, physiological, and biochemical parameters in any environment without activity restriction or behavior modification [1].
Autors: Lo, B.;Thiemjarus, S.;Panousopoulou, A.;Yang, Guang-Zhong;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jan 2013, volume: 30, issue:1, pages: 165 - 170
Publisher: IEEE
 
» Bit Error-Rate Minimizing Detector for Amplify-and-Forward Relaying Systems Using Generalized Gaussian Kernel
Abstract:
In this letter, a new detector is proposed for amplify-and-forward (AF) relaying system when communicating with the assistance of relays. The major goal of this detector is to improve the bit error rate (BER) performance of the receiver. The probability density function is estimated with the help of kernel density technique. A generalized Gaussian kernel is proposed. This new kernel provides more flexibility and encompasses Gaussian and uniform kernels as special cases. The optimal window width of the kernel is calculated. Simulations results show that a gain of more than 1 dB can be achieved in terms of BER performance as compared to the minimum mean square error (MMSE) receiver when communicating over Rayleigh fading channels.
Autors: Ahmed, Q. Z.;Alouini, M.-S.;Aissa, S.;
Appeared in: IEEE Signal Processing Letters
Publication date: Jan 2013, volume: 20, issue:1, pages: 55 - 58
Publisher: IEEE
 
» Blistering of atomic layer deposition Al2O3 layers grown on silicon and its effect on metal–insulator–semiconductor structures
Abstract:
In this work, a study of the influence of the processing conditions on the blistering of Al2O3 layers grown by atomic layer deposition (ALD) on silicon substrates is presented. The phenomenon occurs when the as-deposited layers are annealed at high temperature in a N2 atmosphere. The characterization of the blistering in terms of density and dimensions indicates that the higher the annealing temperature the higher the density but also the smaller the blister diameter, while the thicker the oxide the larger the blisters. The processing of the blistered layers to obtain Al-Al2O3-Si structures enhances the blistering phenomenon and at the same time affects the silicon surface underneath the blister. This has been evidenced by chemical etching of the deposited layers that have revealed in circular silicon voids of the size of the blister. The influence of the oxygen precursor used in the ALD process has also been investigated, showing that the blister size is reduced when using O3 instead of H2O. Finally, the use of a thin thermally grown SiO2 layer is shown to avoid blistering of Al2O3 films.
Autors: Beldarrain, Oihane;Duch, Marta;Zabala, Miguel;Rafi, Joan Marc;Gonzalez, Mireia Bargallo;Campabadal, Francesca;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A128 - 01A128-6
Publisher: IEEE
 
» Cable Fault Localization Using Instantaneous Frequency Estimation in Gaussian-Enveloped Linear Chirp Reflectometry
Abstract:
This paper presents an application of a cable fault localization using an instantaneous frequency (IF) estimation in the Gaussian-enveloped linear chirp (GELC) reflectometry. The GELC reflectometry sends a GELC signal into a cable and measures the reflected signals from the faults. A fault distance is calculated by the estimated time delay between the incident and reflected signals. The cross-correlation method for estimating time delay can be affected by the propagation characteristics of the cable and this results in the time offset in the time delay estimation. To reduce the time offset, we propose an IF-estimation-based fault-localization method. The proposed method uses the statistical-model-based detection with the hidden Markov model and the constrained Kalman filtering for estimating the IF of the GELC. We can obtain the time delay between the incident and reflected signals by calculating the time delay between the center frequencies corresponding to the incident and reflected signals, respectively. Experimental results show that the proposed method estimates the accurate fault distance without the compensation term for the time offset. Therefore, the proposed method is an appropriate method for estimating the fault localization in a cable.
Autors: Lee, C. K.;Kwak, K. S.;Yoon, T. S.;Park, J. B.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2013, volume: 62, issue:1, pages: 129 - 139
Publisher: IEEE
 
» Can surface cracks and unipolar arcs explain breakdown and gradient limits?
Abstract:
The authors argue that the physics of unipolar arcs and surface cracks can help understand rf breakdown and vacuum arc data. They outline a model of the basic mechanisms involved in breakdown and explore how the physics of unipolar arcs and cracks can simplify the picture of breakdown and gradient limits in accelerators, tokamaks as well as laser ablation, micrometeorites, and other applications. Cracks are commonly seen in SEM images of arc damage and they are produced as the liquid metal cools. They can produce the required field enhancements to explain field emission data and can produce mechanical failure of the surface that would trigger breakdown events. Unipolar arcs can produce currents sufficient to short out rf structures, and can cause the sort of damage seen in SEM images. They should be unstable, and possibly self-quenching, as seen in optical fluctuations and surface damage. The authors describe some details and consider the predictions of this simple model.
Autors: Insepov, Zeke;Norem, Jim;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 011302 - 011302-10
Publisher: IEEE
 
» Capacity Management of Seed Servers in Peer-to-Peer Streaming Systems With Scalable Video Streams
Abstract:
To improve rendered video quality and serve more receivers, peer-to-peer (P2P) video-on-demand streaming systems usually deploy seed servers. These servers complement the limited upload capacity offered by peers. In this paper, we are interested in optimally managing the capacity of seed servers, especially when scalable video streams are served to peers. Scalable video streams are encoded in multiple layers to support heterogeneous receivers. We show that the problem of optimally allocating the seeding capacity to serve scalable streams to peers is NP-complete. We then propose an approximation algorithm to solve it. Using the proposed allocation algorithm, we develop an analytical model to study the performance of P2P video-on-demand streaming systems and to manage their resources. The analysis also provides an upper bound on the maximum number of peers that can be admitted to the system in flash crowd scenarios. We validate our analysis by comparing its results to those obtained from simulations. Our analytical model can be used by administrators of P2P streaming systems to estimate the performance and video quality rendered to users under various network, peer, and video characteristics.
Autors: Mokhtarian, K.;Hefeeda, M.;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jan 2013, volume: 15, issue:1, pages: 181 - 194
Publisher: IEEE
 
» Capacity of Hybrid Wireless Mesh Networks with Random APs
Abstract:
In conventional Wireless Mesh Networks (WMNs), multihop relays are performed in the backbone comprising of interconnected Mesh Routers (MRs) and this causes capacity degradation. This paper proposes a hybrid WMN architecture that the backbone is able to utilize random connections to Access Points (APs) of Wireless Local Area Network (WLAN). In such a proposed hierarchal architecture, capacity enhancement can be achieved by letting the traffic take advantage of the wired connections through APs. Theoretical analysis has been conducted for the asymptotic capacity of three-tier hybrid WMN, where per-MR capacity in the backbone is first derived and per-MC capacity is then obtained. Besides related to the number of MR cells as a conventional WMN, the analytical results reveal that the asymptotic capacity of a hybrid WMN is also strongly affected by the number of cells having AP connections, the ratio of access link bandwidth to backbone link bandwidth, etc. Appropriate configuration of the network can drastically improve the network capacity in our proposed network architecture. It also shows that the traffic balance among the MRs with AP access is very important to have a tighter asymptotic capacity bound. The results and conclusions justify the perspective of having such a hybrid WMN utilizing widely deployed WLANs.
Autors: Fu, Weihuang;Agrawal, Dharma P.;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jan 2013, volume: 12, issue:1, pages: 136 - 150
Publisher: IEEE
 
» Car Makers See Opportunities in Infotainment, Driver-Assistance Systems [Special Reports]
Abstract:
Remember James Bond and the Sony Ericsson cell phone he used to drive a BMW 750 iL in the 2008 Bond movie, Tomorrow Never Dies? Your smartphone and your car (and very likely you) aren't quite ready for that kind of driving experience, but the technology and automakers are getting closer to that level of capability
Autors: Schneiderman, R.;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jan 2013, volume: 30, issue:1, pages: 11 - 15
Publisher: IEEE
 
» Casual Stereoscopic Photo Authoring
Abstract:
Stereoscopic 3D displays become more and more popular these years. However, authoring high-quality stereoscopic 3D content remains challenging. In this paper, we present a method for easy stereoscopic photo authoring with a regular (monocular) camera. Our method takes two images or video frames using a monocular camera as input and transforms them into a stereoscopic image pair that provides a pleasant viewing experience. The key technique of our method is a perceptual-plausible image rectification algorithm that warps the input image pairs to meet the stereoscopic geometric constraint while avoiding noticeable visual distortion. Our method uses spatially-varying mesh-based image warps. Our warping method encodes a variety of constraints to best meet the stereoscopic geometric constraint and minimize visual distortion. Since each energy term is quadratic, our method eventually formulates the warping problem as a quadratic energy minimization which is solved efficiently using a sparse linear solver. Our method also allows both local and global adjustments of the disparities, an important property for adapting resulting stereoscopic images to different viewing conditions. Our experiments demonstrate that our spatially-varying warping technique can better support casual stereoscopic photo authoring than existing methods and our results and user study show that our method can effectively use casually-taken photos to create high-quality stereoscopic photos that deliver a pleasant 3D viewing experience.
Autors: Liu, F.;Niu, Y.;Jin, H.;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jan 2013, volume: 15, issue:1, pages: 129 - 140
Publisher: IEEE
 
» Channel Assignment for Throughput Optimization in Multichannel Multiradio Wireless Mesh Networks Using Network Coding
Abstract:
Compared to single-hop networks such as WiFi, multihop infrastructure wireless mesh networks (WMNs) can potentially embrace the broadcast benefits of a wireless medium in a more flexible manner. Rather than being point-to-point, links in the WMNs may originate from a single node and reach more than one other node. Nodes located farther than a one-hop distance and overhearing such transmissions may opportunistically help relay packets for previous hops. This phenomenon is called opportunistic overhearing/listening. With multiple radios, a node can also improve its capacity by transmitting over multiple radios simultaneously using orthogonal channels. Capitalizing on these potential advantages requires effective routing and efficient mapping of channels to radios (channel assignment (CA)). While efficient channel assignment can greatly reduce interference from nearby transmitters, effective routing can potentially relieve congestion on paths to the infrastructure. Routing, however, requires that only packets pertaining to a particular connection be routed on a predetermined route. Random network coding (RNC) breaks this constraint by allowing nodes to randomly mix packets overheard so far before forwarding. A relay node thus only needs to know how many packets, and not which packets, it should send. We mathematically formulate the joint problem of random network coding, channel assignment, and broadcast link scheduling, taking into account opportunistic overhearing, the interference constraints, the coding constraints, the number of orthogonal channels, the number of radios per node, and fairness among unicast connections. Based on this formulation, we develop a suboptimal, auction-based solution for overall network throughput optimization. Performance evaluation results show that our algorithm can effectively exploit multiple radios and channels and can cope with fairness issues arising from auctions. Our algorithm also shows promising gains over traditional routing- solutions in which various channel assignment strategies are used.
Autors: Chieochan, Surachai;Hossain, Ekram;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jan 2013, volume: 12, issue:1, pages: 118 - 135
Publisher: IEEE
 
» Characterization of atomic layer deposition HfO2, Al2O3, and plasma-enhanced chemical vapor deposition Si3N4 as metal–insulator–metal capacitor dielectric for GaAs HBT technology
Abstract:
Characterization was performed on the application of atomic layer deposition (ALD) of hafnium dioxide (HfO2) and aluminum oxide (Al2O3), and plasma-enhanced chemical vapor deposition (PECVD) of silicon nitride (Si3N4) as metal–insulator–metal (MIM) capacitor dielectric for GaAs heterojunction bipolar transistor (HBT) technology. The results show that the MIM capacitor with 62 nm of ALD HfO2 resulted in the highest capacitance density (2.67 fF/μm2), followed by capacitor with 59 nm of ALD Al2O3 (1.55 fF/μm2) and 63 nm of PECVD Si3N4 (0.92 fF/μm2). The breakdown voltage of the PECVD Si3N4 was measured to be 73 V, as compared to 34 V for ALD HfO2 and 41 V for Al2O3. The capacitor with Si3N4 dielectric was observed to have lower leakage current than both with Al2O3 and HfO2. As the temperature was increased from 25 to 150 °C, the breakdown voltage decreased and the leakage current increased for all three films, while the capacitance increased for the Al2O3 and HfO2. Additionally, the capacitance of the ALD Al2O3 and HfO2 films was observed to change, when the applied voltage was varied from -5 to +5 V, while no significant change was observed on the capacitance of the PECVD Si3N4. Furhermore, no significant change in capacitance was seen for these silicon nitride, aluminum oxide, and hafnium dioxide films, as the frequency was increased from 1 kHz to 1 MHz. These results show that the ALD films of Al2O3 and HfO2 have good electrical characteristics and can be used to fabricate high density- capacitor. As a result, these ALD Al2O3 and HfO2 films, in addition to PECVD Si3N4, are suitable as MIM capacitor dielectric for GaAs HBT technology, depending on the specific electrical characteristics requirements and application of the GaAs devices.
Autors: Yota, Jiro;Shen, Hong;Ramanathan, Ravi;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A134 - 01A134-9
Publisher: IEEE
 
» Chemistry of Cu(acac)2 on Ni(110) and Cu(110) surfaces: Implications for atomic layer deposition processes
Abstract:
The thermal chemistry of copper(II)acetylacetonate, Cu(acac)2, on Ni(110) and Cu(110) single-crystal surfaces was probed under vacuum by using x-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Some data for acetylacetone (Hacac, CH3COCH2COCH3) adsorbed on Ni(110) are also reported as reference. Chemical transformations were identified in several steps covering a temperature range from 150 K to at least 630 K. The desorption of Hacac and a 3-oxobutanal (CH3COCH2CHO) byproduct was observed first at 150 and 180 K on Ni(110) and at 160 and 185 K on Cu(110), respectively. Partial loss of the acetylacetonate (acac) ligands and a likely change in adsorption geometry are seen next, with the possible production of HCu(acac), which desorbs at 200 and 235 K from the nickel and copper surfaces, respectively. Molecular Cu(acac)2 desorption is observed on both surfaces at approximately 300 K, probably from recombination of Cu(acac) and acac surface species. The remaining copper atoms on the surface lose their remaining acac ligands to the substrate and become reduced directly to metallic copper. At the same time, the organic ligands follow a series of subsequent surface reactions, probably involving several C–C bond-scissions, to produce other fragments, additional Hacac and HCu(acac) in the gas phase in the case of the copper surface, and acetone on nickel. A significant amount of acac must nevertheless survive on the surface to high temperatures, because Hacac peaks are seen in the TPD at about 515 and 590 K and the C 1s XPS split associated with acac is seen up to close to 500 K. In terms of atomic layer deposition processes, this suggests that cycles could be design to run at such temperatures as long as an effective hydrogenation agent is used as the second reactant to remove the surface acac a- Hacac. Only a small fraction of carbon is left behind on Ni after heating to 800 K, whereas more carbon and additional oxygen remains on the surface in the case of Cu.
Autors: Ma, Qiang;Zaera, Francisco;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A112 - 01A112-10
Publisher: IEEE
 
» Clustering Sentence-Level Text Using a Novel Fuzzy Relational Clustering Algorithm
Abstract:
In comparison with hard clustering methods, in which a pattern belongs to a single cluster, fuzzy clustering algorithms allow patterns to belong to all clusters with differing degrees of membership. This is important in domains such as sentence clustering, since a sentence is likely to be related to more than one theme or topic present within a document or set of documents. However, because most sentence similarity measures do not represent sentences in a common metric space, conventional fuzzy clustering approaches based on prototypes or mixtures of Gaussians are generally not applicable to sentence clustering. This paper presents a novel fuzzy clustering algorithm that operates on relational input data; i.e., data in the form of a square matrix of pairwise similarities between data objects. The algorithm uses a graph representation of the data, and operates in an Expectation-Maximization framework in which the graph centrality of an object in the graph is interpreted as a likelihood. Results of applying the algorithm to sentence clustering tasks demonstrate that the algorithm is capable of identifying overlapping clusters of semantically related sentences, and that it is therefore of potential use in a variety of text mining tasks. We also include results of applying the algorithm to benchmark data sets in several other domains.
Autors: Skabar, Andrew;Abdalgader, Khaled;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jan 2013, volume: 25, issue:1, pages: 62 - 75
Publisher: IEEE
 
» Coaxial-Cable Wound Rogowski Coils for Measuring Large-Magnitude Short-Duration Current Pulses
Abstract:
In this paper, the design, calibration, and performance improvement of four self-integrating Rogowski coils are presented. These coils are wound in single and double layers by a coaxial cable without its polyvinyl chloride (PVC) jacket and with air and ferrite cores. Nonuniformities due to the variation of turn density and/or core deformation are compensated by using a one-turn return loop placed inside the helical winding in the opposite direction to the pitch advancement. Oscillatory and overdamped unidirectional current waveforms up to a 7-kA peak value are generated by using different linear and nonlinear loads and impulse-current generator configurations. These large-magnitude short-duration current pulses are measured by different methods, namely, a commercial impulse-current transformer, a commercial Rogowski coil, and the four newly designed self-integrating Rogowski coils. The distortion of the measured current pulses is studied by using the lumped-element model of Rogowski coil and its termination resistance and the signal cable and its matching resistance. The optimal coil termination resistance is obtained under these impulses, and the linearity of all newly designed self-integrating Rogowski coils' output voltages is also investigated. Results reveal that the magnitudes of measurement errors for the current peak and front and tail times are very low when using ferrite cores with a low termination resistance. The trend of the results is also explained in terms of coil termination resistance, transit time, and sensitivity bandwidth.
Autors: Metwally, I. A.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2013, volume: 62, issue:1, pages: 119 - 128
Publisher: IEEE
 
» Collaboration Benefits All [President's Message]
Abstract:
Autors: Lloyd, B.;
Appeared in: IEEE Industry Applications Magazine
Publication date: Jan 2013, volume: 19, issue:1, pages: 4 - 6
Publisher: IEEE
 
» Columns and Forum [From the Editors]
Abstract:
Autors: Cavallaro, A.;Kwasinski, A.;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jan 2013, volume: 30, issue:1, pages: 4 - 4
Publisher: IEEE
 
» Combining dynamic and static depth profiling in low energy ion scattering
Abstract:
The advantages of combining dynamic and static depth profiling in low energy ion scattering are demonstrated for an Si/SiOx/W/Al2O3 ALD stack. Dynamic depth profiling can be used to calibrate static depth profiling. Energy losses of 152 and 215 eV/nm were found for 3 keV 4He+ and 5 keV 4He+ primary ions, respectively, for the experimental configuration used. This is in good agreement with the values used in the field. Static depth profiling can be used to recognize sputter artifacts in dynamic depth profiles.
Autors: ter Veen, Rik;Fartmann, Michael;Kersting, Reinhard;Hagenhoff, Birgit;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A113 - 01A113-3
Publisher: IEEE
 
» Concentration of Measure Inequalities for Toeplitz Matrices With Applications
Abstract:
We derive Concentration of Measure (CoM) inequalities for randomized Toeplitz matrices. These inequalities show that the norm of a high-dimensional signal mapped by a Toeplitz matrix to a low-dimensional space concentrates around its mean with a tail probability bound that decays exponentially in the dimension of the range space divided by a quantity which is a function of the signal. For the class of sparse signals, the introduced quantity is bounded by the sparsity level of the signal. However, we observe that this bound is highly pessimistic for most sparse signals and we show that if a random distribution is imposed on the non-zero entries of the signal, the typical value of the quantity is bounded by a term that scales logarithmically in the ambient dimension. As an application of the CoM inequalities, we consider Compressive Binary Detection (CBD).
Autors: Sanandaji, B. M.;Vincent, T. L.;Wakin, M. B.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Jan 2013, volume: 61, issue:1, pages: 109 - 117
Publisher: IEEE
 
» Consistent Stereo Matching Under Varying Radiometric Conditions
Abstract:
A consistent stereo matching (CSM) algorithm under varying radiometric conditions, such as lighting and exposure variations, for intermediate view synthesis is proposed in this work. First, we transform the colors of stereo images adaptively so that they are similar at corresponding pixels. Since the correspondences are generally unknown before stereo matching, we estimate pseudo-disparity vectors by sorting pixels based on the cumulative color histograms and use those pseudo vectors in the color transform. Then, to improve the accuracy of stereo matching, we jointly estimate the disparity maps for virtual intermediate views as well as those for real views, based on the consistency criterion that an object point should have the same disparity through all the views. Specifically, we compute matching costs using the reliability term and aggregate the costs to obtain initial disparity maps. We then refine the initial disparity maps by minimizing an energy function, which includes the consistency term. Experimental results show that the proposed CSM algorithm significantly reduces the error rate of disparity estimation under different radiometric conditions and synthesizes high quality intermediate views.
Autors: Jung, I.-L.;Chung, T.-Y.;Sim, J.-Y.;Kim, C.-S.;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jan 2013, volume: 15, issue:1, pages: 56 - 69
Publisher: IEEE
 
» Continuous Wave Spectroscopic Terahertz Imaging With InGaAs Bow-Tie Diodes at Room Temperature
Abstract:
Continuous wave spectroscopic terahertz imaging with InGaAs bow-tie diodes is demonstrated at room temperature. Spectra and images of plastic explosive simulators prepared from tartaric acid and sucrose are recorded within the frequency range of 0.585–2.52 THz. The bow-tie diode performance and implementation for real-time imaging applications are discussed.
Autors: Kasalynas, I.;Venckevicius, R.;Valusis, G.;
Appeared in: IEEE Sensors Journal
Publication date: Jan 2013, volume: 13, issue:1, pages: 50 - 54
Publisher: IEEE
 
» Cooperative Secure Beamforming for AF Relay Networks With Multiple Eavesdroppers
Abstract:
This letter studies cooperative secure beamforming for amplify-and-forward (AF) relay networks in the presence of multiple eavesdroppers. Under both total and individual relay power constraints, we propose two schemes, namely secrecy rate maximization (SRM) beamforming and null-space beamforming. In the first scheme, our design problem is based on SRM. Using a suboptimal, but convex, technique—semidefinite relaxation (SDR), we show that this problem can be handled by performing a one-dimensional search which involves solving a sequence of semidefinite programs (SDPs). To reduce the complexity, in the second scheme, we instead maximize the information rate at the destination while completely eliminating the information leakage to all eavesdroppers. We prove that this problem can be exactly solved by SDR with one SDP only. Simulation results demonstrate the performance gains of the two proposed designs.
Autors: Yang, Y.;Li, Q.;Ma, W.-K.;Ge, J.;Ching, P. C.;
Appeared in: IEEE Signal Processing Letters
Publication date: Jan 2013, volume: 20, issue:1, pages: 35 - 38
Publisher: IEEE
 
» Costs and Benefits of API Motors and Generators: Comparison and Recommendation of Features
Abstract:
The American Petroleum Institute (API) 541, 546, and 547 large motor and generator standards require many features that are not found in other large electric machines. These features make the machine more reliable, but they also add to the initial cost. This article compares the costs and benefits of some of the more significant features that may be specified and makes recommendations about the optional features that should be purchased for specific situations.
Autors: Lockley, B.;Wood, B.;
Appeared in: IEEE Industry Applications Magazine
Publication date: Jan 2013, volume: 19, issue:1, pages: 91 - 100
Publisher: IEEE
 
» Covering Points of Interest with Mobile Sensors
Abstract:
The coverage of Points of Interest (PoI) is a classical requirement in mobile wireless sensor applications. Optimizing the sensors self-deployment over a PoI while maintaining the connectivity between the sensors and the base station is thus a fundamental issue. This paper addresses the problem of autonomous deployment of mobile sensors that need to cover a predefined PoI with a connectivity constraint. In our algorithm, each sensor moves toward a PoI but has also to maintain the connectivity with a subset of its neighboring sensors that are part of the Relative Neighborhood Graph (RNG). The Relative Neighborhood Graph reduction is chosen so that global connectivity can be provided locally. Our deployment scheme minimizes the number of sensors used for connectivity thus increasing the number of monitoring sensors. Analytical results, simulation results and practical implementation are provided to show the efficiency of our algorithm.
Autors: Erdelj, Milan;Razafindralambo, Tahiry;Simplot-Ryl, David;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jan 2013, volume: 24, issue:1, pages: 32 - 43
Publisher: IEEE
 
» Crystal AlN deposited at low temperature by magnetic field enhanced plasma assisted atomic layer deposition
Abstract:
In this paper, AlN films prepared at low temperature by magnetic field enhanced plasma assisted atomic layer deposition (PA-ALD) using trimethyl aluminum and the mixture gas of nitrogen and hydrogen were investigated. Two discharge modes were employed for PA-ALD AlN, i.e., radio-frequency (RF) discharge mode and microwave electron cyclotron resonance (ECR) mode. The structure of the film, compositions, crystallinity, surface roughness, and properties of refractive index as well as photoluminescence were studied by Fourier transform infrared spectroscope, x-ray photoelectron spectroscope, x-ray diffraction, atomic force microscope, spectroscopic ellipsometry, and photoluminescence spectrometer, respectively. Comparison of the as-deposited films prepared in two discharge modes, the authors result that temperature played an important role in in ECR mode, AlN films deposited in ECR mode at 250 °C is crystalline except a little bit of aluminum rich with the contamination of carbon and oxygen; whereas in RF discharge mode, the direct interaction of plasma, the all process parameters affect the properties of the AlN films, like the strength of magnetic field, deposition temperature. The intense emission band measured through photoluminescence spectrum of the as-deposited AlN suggests that there may be potential applications in electronic and optoelectronic nanodevices.
Autors: Lei, Wenwen;Chen, Qiang;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A114 - 01A114-7
Publisher: IEEE
 
» Delay Analysis of Max-Weight Queue Algorithm for Time-Varying Wireless Ad hoc Networks—Control Theoretical Approach
Abstract:
Max weighted queue (MWQ) control policy is a widely used cross-layer control policy that achieves queue stability and a reasonable delay performance. In most of the existing literature, it is assumed that optimal MWQ policy can be obtained instantaneously at every time slot. However, this assumption may be unrealistic in time varying wireless systems, especially when there is no closed-form MWQ solution and iterative algorithms have to be applied to obtain the optimal solution. This paper investigates the convergence behavior and the queue delay performance of the conventional MWQ iterations in which the channel state information (CSI) and queue state information (QSI) are changing in a similar timescale as the algorithm iterations. Our results are established by studying the stochastic stability of an equivalent virtual stochastic dynamic system (VSDS), and an extended Foster-Lyapunov criteria is applied for the stability analysis. We derive a closed form delay bound of the wireless network in terms of the CSI fading rate and the sensitivity of MWQ policy over CSI and QSI. Based on the equivalent VSDS, we propose a novel MWQ iterative algorithm with compensation to improve the tracking performance. We demonstrate that under some mild conditions, the proposed modified MWQ algorithm converges to the optimal MWQ control despite the time-varying CSI and QSI.
Autors: Chen, J.;Lau, V. K. N.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Jan 2013, volume: 61, issue:1, pages: 99 - 108
Publisher: IEEE
 
» Delay-Optimal Broadcast for Multihop Wireless Networks Using Self-Interference Cancellation
Abstract:
Conventional wireless broadcast protocols rely heavily on the 802.11-based CSMA/CA model, which avoids interference and collision by conservative scheduling of transmissions. While CSMA/CA is amenable to multiple concurrent unicasts, it tends to degrade broadcast performance significantly, especially in lossy and large-scale networks. In this paper, we propose a new protocol called Chorus that improves the efficiency and scalability of broadcast service with a MAC/PHY layer that allows packet collisions. Chorus is built upon the observation that packets carrying the same data can be effectively detected and decoded, even when they overlap with each other and have comparable signal strengths. It resolves collision using symbol-level interference cancellation, and then combines the resolved symbols to restore the packet. Such a collision-tolerant mechanism significantly improves the transmission diversity and spatial reuse in wireless broadcast. Chorus' MAC-layer cognitive sensing and scheduling scheme further facilitates the realization of such an advantage, resulting in an asymptotic broadcast delay that is proportional to the network radius. We evaluate Chorus' PHY-layer collision resolution mechanism with symbol-level simulation, and validate its network-level performance via ns-2, in comparison with a typical CSMA/CA-based broadcast protocol. Our evaluation validates Chorus's superior performance with respect to scalability, reliability, delay, etc., under a broad range of network scenarios (e.g., single/multiple broadcast sessions, static/mobile topologies).
Autors: Zhang, Xinyu;Shin, Kang G.;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jan 2013, volume: 12, issue:1, pages: 7 - 20
Publisher: IEEE
 
» Detecting Motion through Dynamic Refraction
Abstract:
Refraction causes random dynamic distortions in atmospheric turbulence and in views across a water interface. The latter scenario is experienced by submerged animals seeking to detect prey or avoid predators, which may be airborne or on land. Man encounters this when surveying a scene by a submarine or divers while wishing to avoid the use of an attention-drawing periscope. The problem of inverting random refracted dynamic distortions is difficult, particularly when some of the objects in the field of view (FOV) are moving. On the other hand, in many cases, just those moving objects are of interest, as they reveal animal, human, or machine activity. Furthermore, detecting and tracking these objects does not necessitate handling the difficult task of complete recovery of the scene. We show that moving objects can be detected very simply, with low false-positive rates, even when the distortions are very strong and dominate the object motion. Moreover, the moving object can be detected even if it has zero mean motion. While the object and distortion motions are random and unknown, they are mutually independent. This is expressed by a simple motion feature which enables discrimination of moving object points versus the background.
Autors: Alterman, Marina;Schechner, Yoav Y.;Perona, Pietro;Shamir, Joseph;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jan 2013, volume: 35, issue:1, pages: 245 - 251
Publisher: IEEE
 
» Detection and Localization of Multiple Spoofing Attackers in Wireless Networks
Abstract:
Wireless spoofing attacks are easy to launch and can significantly impact the performance of networks. Although the identity of a node can be verified through cryptographic authentication, conventional security approaches are not always desirable because of their overhead requirements. In this paper, we propose to use spatial information, a physical property associated with each node, hard to falsify, and not reliant on cryptography, as the basis for 1) detecting spoofing attacks; 2) determining the number of attackers when multiple adversaries masquerading as the same node identity; and 3) localizing multiple adversaries. We propose to use the spatial correlation of received signal strength (RSS) inherited from wireless nodes to detect the spoofing attacks. We then formulate the problem of determining the number of attackers as a multiclass detection problem. Cluster-based mechanisms are developed to determine the number of attackers. When the training data are available, we explore using the Support Vector Machines (SVM) method to further improve the accuracy of determining the number of attackers. In addition, we developed an integrated detection and localization system that can localize the positions of multiple attackers. We evaluated our techniques through two testbeds using both an 802.11 (WiFi) network and an 802.15.4 (ZigBee) network in two real office buildings. Our experimental results show that our proposed methods can achieve over 90 percent Hit Rate and Precision when determining the number of attackers. Our localization results using a representative set of algorithms provide strong evidence of high accuracy of localizing multiple adversaries.
Autors: Yang, Jie;Chen, Yingying (Jennifer);Trappe, Wade;Cheng, Jerry;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jan 2013, volume: 24, issue:1, pages: 44 - 58
Publisher: IEEE
 
» Digital Compensation of Rogowski Coil's Output Voltage
Abstract:
Due to inherent characteristics of Rogowski coils, measured signals by these transducers are distorted, and hence, it is a need to compensate their output voltages in order to reconstruct their input current. Using analog circuits for the reconstruction of the input current of a Rogowski coil is a very common technique, but this technique has no appropriate performance upon partial discharge signals. In this paper, digital techniques for the reconstruction of the input current of Rogowski coils have been presented and examined, and the best practical one that can be used for either unshielded or shielded coils has been proposed. The proposed method is a model-free compensation method; in other words, there is no need to extract any of the parameters of a given coil as long as its frequency response is measured and processed according to the proposed method.
Autors: Hemmati, E.;Shahrtash, S. M.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2013, volume: 62, issue:1, pages: 71 - 82
Publisher: IEEE
 
» Discovering Video Shot Categories by Unsupervised Stochastic Graph Partition
Abstract:
Video shots are often treated as the basic elements for retrieving information from videos. In recent years, video shot categorization has received increasing attention, but most of the methods involve a procedure of supervised learning, i.e., training a multi-class predictor (classifier) on the labeled data. In this paper, we study a general framework to unsupervisedly discover video shot categories. The contributions are three-fold in feature, representation, and inference: (1) A new feature is proposed to capture local information in videos, defined with small video patches (e.g., pixels). A dictionary of video words can be thus clustered off-line, characterizing both appearance and motion dynamics. (2) We pose the problem of categorization as an automated graph partition task, in that each graph vertex represents a video shot, and a partitioned sub-graph consisting of connected graph vertices represents a clustered category. The model of each video shot category can be analytically calculated by a projection pursuit type of learning process. (3) An MCMC-based cluster sampling algorithm, namely Swendsen-Wang cuts, is adopted to efficiently solve the graph partition. Unlike traditional graph partition techniques, this algorithm is able to explore the nearly global optimal solution and eliminate the need for good initialization. We apply our method on a wide variety of 1600 video shots collected from Internet as well as a subset of TRECVID 2010 data, and two benchmark metrics, i.e., Purity and Conditional Entropy, are adopted for evaluating performance. The experimental results demonstrate superior performance of our method over other popular state-of-the-art methods.
Autors: Duan, X.;Lin, L.;Chao, H.;
Appeared in: IEEE Transactions on Multimedia
Publication date: Jan 2013, volume: 15, issue:1, pages: 167 - 180
Publisher: IEEE
 
» Discriminative Multimanifold Analysis for Face Recognition from a Single Training Sample per Person
Abstract:
Conventional appearance-based face recognition methods usually assume that there are multiple samples per person (MSPP) available for discriminative feature extraction during the training phase. In many practical face recognition applications such as law enhancement, e-passport, and ID card identification, this assumption, however, may not hold as there is only a single sample per person (SSPP) enrolled or recorded in these systems. Many popular face recognition methods fail to work well in this scenario because there are not enough samples for discriminant learning. To address this problem, we propose in this paper a novel discriminative multimanifold analysis (DMMA) method by learning discriminative features from image patches. First, we partition each enrolled face image into several nonoverlapping patches to form an image set for each sample per person. Then, we formulate the SSPP face recognition as a manifold-manifold matching problem and learn multiple DMMA feature spaces to maximize the manifold margins of different persons. Finally, we present a reconstruction-based manifold-manifold distance to identify the unlabeled subjects. Experimental results on three widely used face databases are presented to demonstrate the efficacy of the proposed approach.
Autors: Lu, Jiwen;Tan, Yap-Peng;Wang, Gang;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jan 2013, volume: 35, issue:1, pages: 39 - 51
Publisher: IEEE
 
» Distributed Particle Filtering in Agent Networks: A Survey, Classification, and Comparison
Abstract:
Distributed particle filter (DPF) algorithms are sequential state estimation algorithms that are executed by a set of agents. Some or all of the agents perform local particle filtering and interact with other agents to calculate a global state estimate. DPF algorithms are attractive for large-scale, nonlinear, and non-Gaussian distributed estimation problems that often occur in applications involving agent networks (ANs). In this article, we present a survey, classification, and comparison of various DPF approaches and algorithms available to date. Our emphasis is on decentralized ANs that do not include a central processing or control unit.
Autors: Hlinka, O.;Hlawatsch, F.;Djuric, P.M.;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jan 2013, volume: 30, issue:1, pages: 61 - 81
Publisher: IEEE
 
» Distributed Processing of Probabilistic Top-k Queries in Wireless Sensor Networks
Abstract:
In this paper, we introduce the notion of sufficient set and necessary set for distributed processing of probabilistic top-k queries in cluster-based wireless sensor networks. These two concepts have very nice properties that can facilitate localized data pruning in clusters. Accordingly, we develop a suite of algorithms, namely, sufficient set-based (SSB), necessary set-based (NSB), and boundary-based (BB), for intercluster query processing with bounded rounds of communications. Moreover, in responding to dynamic changes of data distribution in the network, we develop an adaptive algorithm that dynamically switches among the three proposed algorithms to minimize the transmission cost. We show the applicability of sufficient set and necessary set to wireless sensor networks with both two-tier hierarchical and tree-structured network topologies. Experimental results show that the proposed algorithms reduce data transmissions significantly and incur only small constant rounds of data communications. The experimental results also demonstrate the superiority of the adaptive algorithm, which achieves a near-optimal performance under various conditions.
Autors: Ye, Mao;Lee, Wang-Chien;Lee, Dik Lun;Liu, Xingjie;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jan 2013, volume: 25, issue:1, pages: 76 - 91
Publisher: IEEE
 
» Dynamical Simulation Priors for Human Motion Tracking
Abstract:
We propose a simulation-based dynamical motion prior for tracking human motion from video in presence of physical ground-person interactions. Most tracking approaches to date have focused on efficient inference algorithms and/or learning of prior kinematic motion models; however, few can explicitly account for the physical plausibility of recovered motion. Here, we aim to recover physically plausible motion of a single articulated human subject. Toward this end, we propose a full-body 3D physical simulation-based prior that explicitly incorporates a model of human dynamics into the Bayesian filtering framework. We consider the motion of the subject to be generated by a feedback “control loop” in which Newtonian physics approximates the rigid-body motion dynamics of the human and the environment through the application and integration of interaction forces, motor forces, and gravity. Interaction forces prevent physically impossible hypotheses, enable more appropriate reactions to the environment (e.g., ground contacts), and are produced from detected human-environment collisions. Motor forces actuate the body, ensure that proposed pose transitions are physically feasible, and are generated using a motion controller. For efficient inference in the resulting high-dimensional state space, we utilize an exemplar-based control strategy that reduces the effective search space of motor forces. As a result, we are able to recover physically plausible motion of human subjects from monocular and multiview video. We show, both quantitatively and qualitatively, that our approach performs favorably with respect to Bayesian filtering methods with standard motion priors.
Autors: Vondrak, Marek;Sigal, Leonid;Jenkins, Odest Chadwicke;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jan 2013, volume: 35, issue:1, pages: 52 - 65
Publisher: IEEE
 
» Editor's Note
Abstract:
Autors: Stojmenovic, Ivan;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jan 2013, volume: 24, issue:1, pages: 1 - 3
Publisher: IEEE
 
» Editor's note
Abstract:
Jiri Matas has served two terms as Associate Editor in Chief, and the rules require he leave the role. His contribution to the smooth running of the journal has been spectacular. I know our community understands and appreciates the work that Jiri has done. As of writing, I cannot announce the name of a new AEIC, but I expect to do so shortly.
Autors: Forsyth, D.A.;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jan 2013, volume: 35, issue:1, pages: 3 - 4
Publisher: IEEE
 
» Editorial and changes to the Editorial Board
Abstract:
Our editorial board continues to perform outstanding service to the mobile computing community, and for this we are very grateful. The board has evolved this year, and we take this opportunity to welcome several new Associate Editors: Prithwish Basu, Carla Fabiana-Chiasserini, Ahmed Helmy, Vana Kalogeraki, Richard J. La, Xiang-Yang Li, Cecilia Mascolo, Tommaso Melodia, Guevara Noubir, Andrea Richa, Lakshminarayanan Subramanian, Karthikeyan Sundaresan, Xinbing Wang, Edmund Yeh, Yanyong Zhang, and Lin Zhong. Biographies are provided. They collectively strengthen our expertise in disruption-tolerant networking, vehicular networks, mobile computing systems, wireless security, mobile social networks, wireless network optimization, game theory, cognitive radios, and information theory. We are excited to have them on board and thank them for agreeing to serve. Finally, we'd also like to acknowledge several Associate Editors whose terms recently expired: Tajana Simunic-Rosing, Sajal Das, Paolo Santi, Terry Todd, Wade Trappe, Nalini Venkatasubramanian, Mary Ann Ingram, Ekram Hossain, Chiara Petrioli, Alex Snoeren, Prasant Mohapatra, and Yunhao Liu. This very distinguished group of researchers has contributed greatly to increasing the journal's quality and reputation, and they will be missed! We wish them the best in their future endeavors.
Autors: Govindan, Ramesh;Ramanathan, Ram;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jan 2013, volume: 12, issue:1, pages: 1 - 6
Publisher: IEEE
 
» Effect of in situ hydrogen plasma treatment on zinc oxide grown using low temperature atomic layer deposition
Abstract:
Zinc oxide (ZnO) films under in situ hydrogen plasma were deposited via atomic layer deposition (ALD) at an extremely low temperature (100 °C). Diethyl zinc ((C2H5)2Zn) and deionized water were used as the zinc and oxygen source, respectively. The growth rate of the ZnO films decreased to 1.26 and 1.06 Å/cycle due to changes in the hydrogen plasma treatment power and exposure time, respectively. The resistivity of the ZnO films decreased to 7.6 × 10-4 Ω cm, even at 100 °C, with a very high carrier concentration (1.4 × 1021 cm-3) due to the increasing oxygen deficiencies in the ZnO films. The carrier mobility was decreased slightly to 8.6 cm2/Vs via grain boundary scattering due to the enhanced polycrystallization. Based on the x-ray diffraction and x-ray photoelectron spectroscopy, the carrier concentration and mobility were strongly correlated to the oxygen deficiency and crystallinity, respectively. In addition, the in situ hydrogen plasma in the ZnO ALD had an important role in sequentially generating oxygen deficiencies and enhancing polycrystal growth.
Autors: Jung, Tae-Hoon;Park, Jin-Seong;Kim, Dong-Ho;Jeong, Yongsoo;Park, Sung-Gyu;Kwon, Jung-Dae;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A124 - 01A124-4
Publisher: IEEE
 
» Effect of the amido Ti precursors on the atomic layer deposition of TiN with NH3
Abstract:
The effect of the amide Ti precursors, tetrakis dimethyl amido titanium (TDMAT), tetrakis ethylmethyl amido titanium (TEMAT), and tetrakis diethyl amido titanium (TDEAT) on the atomic layer deposition of TiN film with ammonia was studied. Surface decomposition mechanism of each precursor was studied with in-situ Fourier transform infrared spectroscopy. It was confirmed that ethyl ligand in the precursor was more stable than methyl and the surface decomposition temperature of TDMAT, TEMAT, and TDEAT was 175, 200, and 250 °C on the SiO2 surface, respectively. The resistivity of the film was decreased with the increase in the substrate temperature due to the film crystallization. The TiN film deposited with TDMAT gave the lowest resistivity even though the atomic layer deposition temperature window was lowest due to the largest amount of carbon incorporation. It was confirmed that carbon incorporation leads to TiC formation and suppressed the postdeposition oxygen uptake possibly due to the elimination of vacancy in the film.
Autors: Cho, Gihee;Rhee, Shi-Woo;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A117 - 01A117-5
Publisher: IEEE
 
» Effects of the gas ambient in thermal activation of Mg-doped p-GaN on Hall effect and photoluminescence
Abstract:
The effects of thermal annealing in N2, O2, Ar or mixed gas ambient on the electrical and optical properties of metal-organic-chemical-vapor-deposition-grown Mg-doped p-type GaN were investigated by Hall effect and photoluminescence. A systematical study on optimizing annealing gas combination, time, and temperature for achieving high activation efficiency of Mg acceptors was conducted simultaneously. High hole concentration of 9.07 × 1017 cm-3 and low resistivity of 0.622 Ω-cm using the optimized annealing condition were achieved. In agreement with some previous studies, annealing in the mixed gas ambient of N2 and O2 provided significant improvements in activation efficiency of Mg acceptors compared with annealing in pure O2, N2, or Ar. The room- and low-temperature photoluminescence spectra measured from the samples annealed in N2-rich ambient showed significantly higher photoluminescence intensity at both 2.8- and 3.2-eV band transitions. Consistent with the study of others, the experimental results of this study indicated that when annealing in the mixed N2/O2 gas ambient O2 effectively helps activate Mg acceptors by releasing H from Mg-H complexes but also oxidizes GaN; it is likely that the presence of N2 is beneficial in reducing the formation of nitrogen vacancies.
Autors: Lu, Wei;Aplin, David;Clawson, Arthur R.;Yu, Paul K. L.;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 011502 - 011502-5
Publisher: IEEE
 
» Efficient Classification for Additive Kernel SVMs
Abstract:
We show that a class of nonlinear kernel SVMs admits approximate classifiers with runtime and memory complexity that is independent of the number of support vectors. This class of kernels, which we refer to as additive kernels, includes widely used kernels for histogram-based image comparison like intersection and chi-squared kernels. Additive kernel SVMs can offer significant improvements in accuracy over linear SVMs on a wide variety of tasks while having the same runtime, making them practical for large-scale recognition or real-time detection tasks. We present experiments on a variety of datasets, including the INRIA person, Daimler-Chrysler pedestrians, UIUC Cars, Caltech-101, MNIST, and USPS digits, to demonstrate the effectiveness of our method for efficient evaluation of SVMs with additive kernels. Since its introduction, our method has become integral to various state-of-the-art systems for PASCAL VOC object detection/image classification, ImageNet Challenge, TRECVID, etc. The techniques we propose can also be applied to settings where evaluation of weighted additive kernels is required, which include kernelized versions of PCA, LDA, regression, k-means, as well as speeding up the inner loop of SVM classifier training algorithms.
Autors: Maji, Subhransu;Berg, Alexander C.;Malik, Jitendra;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jan 2013, volume: 35, issue:1, pages: 66 - 77
Publisher: IEEE
 
» Efficient Eager Management of Conflicts for Scalable Hardware Transactional Memory
Abstract:
The efficient management of conflicts among concurrent transactions constitutes a key aspect that hardware transactional memory (HTM) systems must achieve. Scalable HTM proposals so far inherit the cache-based style of conflict detection typically found in bus-based systems, largely unaware of the interactions between transactions and directory coherence. In this paper, we demonstrate that the traditional approach of detecting conflicts at the private cache levels is inefficient when used in the context of a directory protocol. We find that the use of the directory as a mere router of coherence requests restricts the throughput of conflict detection, and show how it becomes a bottleneck under high contention. This paper proposes a scheme for conflict detection that decouples conflict detection from cache coherence in order to overcome pathological situations that degrade the performance of an eager HTM system. Our scheme places bookkeeping metadata at the directory, introducing it as a separate hardware module that leaves the coherence protocol unmodified. In comparison to a state-of-the-art eager HTM system, our design handles contention more efficiently, minimizes the performance degradation of false positives for signatures of similar hardware cost, and reduces the network traffic generated.
Autors: Titos-Gil, Rub\én;Acacio, Manuel E.;Garc\ía, Jos\é M.;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: Jan 2013, volume: 24, issue:1, pages: 59 - 71
Publisher: IEEE
 
» Electrical characterization of atomic-layer-deposited hafnium oxide films from hafnium tetrakis(dimethylamide) and water/ozone: Effects of growth temperature, oxygen source, and postdeposition annealing
Abstract:
The electrical properties of HfO2-based metal–insulator–semiconductor capacitors have been systematically investigated by means of I–V and C–V characteristics, admittance spectroscopy, deep level transient spectroscopy, conductance transient, and flat band voltage transient techniques. Attention is also given to the study of the temperature dependence of the leakage current. HfO2 films were grown on p-type silicon substrates by atomic layer deposition using hafnium tetrakis(dimethylamide) as hafnium precursor, and ozone or water as oxygen precursors. The growth temperature ranged from 150 to 350 °C. Low growth temperatures prevent decomposition and high growth rate, as well as high contamination levels. As a result, the leakage current is lower for lower deposition temperatures. Some of the deposited samples were submitted to a postdeposition annealing at 650 °C in N2 atmosphere, showing a decrease in the leakage current and an increase in the equivalent oxide thickness (EOT), whereas interfacial state density increases and defect density inside the dielectric bulk decreases. Regarding dielectric reliability, in our experimental conditions, HfO2 layers grown at 150 °C exhibit the largest EOT and breakdown voltage. The electrical behaviour is clearly linked with structural properties, and especially with the formation of an interfacial layer between the HfO2 layer and the silicon substrate, as well as with the presence of several impurities.
Autors: Garcia, Hector;Castan, Helena;Duenas, Salvador;Bailon, Luis;Campabadal, Francesca;Beldarrain, Oihane;Zabala, Miguel;Gonzalez, Mireia Bargallo;Rafi, Joan Marc;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A127 - 01A127-7
Publisher: IEEE
 
» EMAP: Expedite Message Authentication Protocol for Vehicular Ad Hoc Networks
Abstract:
Vehicular ad hoc networks (VANETs) adopt the Public Key Infrastructure (PKI) and Certificate Revocation Lists (CRLs) for their security. In any PKI system, the authentication of a received message is performed by checking if the certificate of the sender is included in the current CRL, and verifying the authenticity of the certificate and signature of the sender. In this paper, we propose an Expedite Message Authentication Protocol (EMAP) for VANETs, which replaces the time-consuming CRL checking process by an efficient revocation checking process. The revocation check process in EMAP uses a keyed Hash Message Authentication Code ({HMAC}), where the key used in calculating the {HMAC} is shared only between nonrevoked On-Board Units (OBUs). In addition, EMAP uses a novel probabilistic key distribution, which enables nonrevoked OBUs to securely share and update a secret key. EMAP can significantly decrease the message loss ratio due to the message verification delay compared with the conventional authentication methods employing CRL. By conducting security analysis and performance evaluation, EMAP is demonstrated to be secure and efficient.
Autors: Wasef, Albert;Shen, Xuemin;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jan 2013, volume: 12, issue:1, pages: 78 - 89
Publisher: IEEE
 
» Encrypted Signal Processing for Privacy Protection: Conveying the Utility of Homomorphic Encryption and Multiparty Computation
Abstract:
In recent years, signal processing applications that deal with user-related data have aroused privacy concerns. For instance, face recognition and personalized recommendations rely on privacy-sensitive information that can be abused if the signal processing is executed on remote servers or in the cloud. In this tutorial article, we introduce the fusion of signal processing and cryptography as an emerging paradigm to protect the privacy of users. While service providers cannot access directly the content of the encrypted signals, the data can still be processed in encrypted form to perform the required signal processing task. The solutions for processing encrypted data are designed using cryptographic primitives like homomorphic cryptosystems and secure multiparty computation (MPC).
Autors: Lagendijk, R.L.;Erkin, Z.;Barni, M.;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jan 2013, volume: 30, issue:1, pages: 82 - 105
Publisher: IEEE
 
» Epitaxial strontium titanate films grown by atomic layer deposition on SrTiO3-buffered Si(001) substrates
Abstract:
Epitaxial strontium titanate (STO) films have been grown by atomic layer deposition (ALD) on Si(001) substrates with a thin STO buffer layer grown by molecular beam epitaxy (MBE). Four unit cells of STO grown by MBE serve as the surface template for ALD growth. The STO films grown by ALD are crystalline as-deposited with minimal, if any, amorphous SiOx layer at the STO-Si interface. The growth of STO was achieved using bis(triisopropylcyclopentadienyl)-strontium, titanium tetraisopropoxide, and water as the coreactants at a substrate temperature of 250 °C. In situ x-ray photoelectron spectroscopy (XPS) analysis revealed that the ALD process did not induce additional Si–O bonding at the STO-Si interface. Postdeposition XPS analysis also revealed sporadic carbon incorporation in the as-deposited films. However, annealing at a temperature of 250 °C for 30 min in moderate to high vacuum (10-6–10-9 Torr) removed the carbon species. Higher annealing temperatures (>275 °C) gave rise to a small increase in Si–O bonding, as indicated by XPS, but no reduced Ti species were observed. X-ray diffraction revealed that the as-deposited STO films were c-axis oriented and fully crystalline. A rocking curve around the STO(002) reflection gave a full width at half maximum of 0.30° ± 0.06° for film thicknesses ranging from 5 to 25 nm. Cross-sectional transmission electron microscopy revealed that the STO films were continuous with conformal growth to the substrate and smooth interfaces between the ALD- and MBE-grown STO. Overall, the results indicate that thick, crystalline STO can be grown on Si(001) substrates by ALD with minimal formation of an amorphous SiOx layer using a four-unit-cell STO buffer layer grown by MBE to serve as the surface template.
Autors: McDaniel, Martin D.;Posadas, Agham;Ngo, Thong Q.;Dhamdhere, Ajit;Smith, David J.;Demkov, Alexander A.;Ekerdt, John G.;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A136 - 01A136-9
Publisher: IEEE
 
» Estimating Information from Image Colors: An Application to Digital Cameras and Natural Scenes
Abstract:
The colors present in an image of a scene provide information about its constituent elements. But the amount of information depends on the imaging conditions and on how information is calculated. This work had two aims. The first was to derive explicitly estimators of the information available and the information retrieved from the color values at each point in images of a scene under different illuminations. The second was to apply these estimators to simulations of images obtained with five sets of sensors used in digital cameras and with the cone photoreceptors of the human eye. Estimates were obtained for 50 hyperspectral images of natural scenes under daylight illuminants with correlated color temperatures 4,000, 6,500, and 25,000 K. Depending on the sensor set, the mean estimated information available across images with the largest illumination difference varied from 15.5 to 18.0 bits and the mean estimated information retrieved after optimal linear processing varied from 13.2 to 15.5 bits (each about 85 percent of the corresponding information available). With the best sensor set, 390 percent more points could be identified per scene than with the worst. Capturing scene information from image colors depends crucially on the choice of camera sensors.
Autors: Mar\ín-Franch, Iv\án;Foster, David H.;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jan 2013, volume: 35, issue:1, pages: 78 - 91
Publisher: IEEE
 
» Evaluating Al2O3 gas diffusion barriers grown directly on Ca films using atomic layer deposition techniques
Abstract:
Al2O3 gas diffusion barriers grown directly on Ca films using atomic layer deposition (ALD) techniques were evaluated using several methods based on Ca oxidation. The Al2O3 ALD films were grown on Ca films at 120 °C using trimethylaluminum and H2O as the reactants. The oxidation of the Ca films was then monitored versus time at 70 °C and ∼28% relative humidity either by measuring the electrical conductance of the Ca film or by recording the photographic image of the Ca film. In the photographic images, the Ca films revealed that the Al2O3 ALD films have a small number of pinhole defects that lead to Ca film oxidation areas that grow radially around the pinhole defect versus time. A burst of new oxidation areas also appeared suddenly at later times and grew radially versus time. This rapid “blooming” may be related to another type of defect caused by water corrosion of the Al2O3 ALD films. In the electrical conductance measurements, the conductance of the Ca film initially showed little change versus time. The conductance then dropped rapidly when the oxidation area in the photographic image was a noticeable fraction of the Ca film area. The conductance measurements yielded a water vapor transmission rate (WVTR) value of ∼2 × 10-2 g/(m2 day) prior to the rapid reduction of the conductance. The photographic images of the Ca film were also analyzed to obtain a WVTR value assuming radial oxidation of the Ca film around defects. The WVTR values obtained from the electrical conductance and the photographic images were in approximate agreement and increased versus Ca film oxidation until the rapid blooming of new circular oxidation areas. The WVTR values are larger than previous measurements and may indicate that Al2O3 ALD films grown directly on Ca a- e less stable and degraded by Ca film oxidation. This study reveals that a range of WVTR values can be obtained from different variations of the Ca test depending on the extent of Ca film oxidation.
Autors: Bertrand, Jacob A.;George, Steven M.;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A122 - 01A122-8
Publisher: IEEE
 
» Evaluating Data Reliability: An Evidential Answer with Application to a Web-Enabled Data Warehouse
Abstract:
There are many available methods to integrate information source reliability in an uncertainty representation, but there are only a few works focusing on the problem of evaluating this reliability. However, data reliability and confidence are essential components of a data warehousing system, as they influence subsequent retrieval and analysis. In this paper, we propose a generic method to assess data reliability from a set of criteria using the theory of belief functions. Customizable criteria and insightful decisions are provided. The chosen illustrative example comes from real-world data issued from the Sym'Previus predictive microbiology oriented data warehouse.
Autors: Destercke, Sebastien;Buche, Patrice;Charnomordic, Brigitte;
Appeared in: IEEE Transactions on Knowledge and Data Engineering
Publication date: Jan 2013, volume: 25, issue:1, pages: 92 - 105
Publisher: IEEE
 
» Evaluating Temporal Robustness of Mobile Networks
Abstract:
The application of complex network models to communication systems has led to several important results: nonetheless, previous research has often neglected to take into account their temporal properties, which in many real scenarios play a pivotal role. At the same time, network robustness has come extensively under scrutiny. Understanding whether networked systems can undergo structural damage and yet perform efficiently is crucial to both their protection against failures and to the design of new applications. In spite of this, it is still unclear what type of resilience we may expect in a network which continuously changes over time. In this work, we present the first attempt to define the concept of temporal network robustness: we describe a measure of network robustness for time-varying networks and we show how it performs on different classes of random models by means of analytical and numerical evaluation. Finally, we report a case study on a real-world scenario, an opportunistic vehicular system of about 500 taxicabs, highlighting the importance of time in the evaluation of robustness. Particularly, we show how static approximation can wrongly indicate high robustness of fragile networks when adopted in mobile time-varying networks, while a temporal approach captures more accurately the system performance.
Autors: Scellato, Salvatore;Leontiadis, Ilias;Mascolo, Cecilia;Basu, Prithwish;Zafer, Murtaza;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: Jan 2013, volume: 12, issue:1, pages: 105 - 117
Publisher: IEEE
 
» Excitation of radiative polaritons by polarized broadband infrared radiation in thin oxide films deposited by atomic layer deposition
Abstract:
This work contributes to the understanding of infrared radiation interaction with matter and its absorption for energy harvesting purposes. By exciting radiative polaritons in thin oxide films with polarized infrared radiation, a further evidence is collected that a link exists between radiative polaritons and the heat recovery mechanism hypothesized in previous research. In the voltage transient occurring when the infrared radiation is turned on, the observed time necessary to reach the maximum voltage and the voltage intensity versus angle of incidence exhibit a mismatch when generated by polarized and nonpolarized infrared radiation. The existence of collective charge oscillation modes in the semiconductor-based elements of the thermoelectric power generators supporting the heat recovery mechanism is suggested as the main source of the discrepancy.
Autors: Vincent-Johnson, Anita J.;Masters, Andrew E.;Hu, Xiaofeng;Scarel, Giovanna;
Appeared in: Journal of Vacuum Science & Technology A
Publication date: Jan 2013, volume: 31, issue:1, pages: 01A111 - 01A111-4
Publisher: IEEE
 
» Extending Network Operation Beyond Congestion Through Embedded Coding [In the Spotlight]
Abstract:
On 23 August 2011, the Washington, D.C., area experienced an earthquake that was unusually strong for that region and with an intensity enough to damage some of the monuments in the United States' capital city. While even stronger earthquakes are regular occurrences in other regions of the world, for many of the millions of people in the Washington, D.C., area, this was the first earthquake strong enough to be clearly felt. This was evident from the public's reaction, as the massive attempt to communicate though cell phones after the earthquake brought the networks down (an event that was reported by several media, including The Washington Post [1]).
Autors: Kwasinski, A.;
Appeared in: IEEE Signal Processing Magazine
Publication date: Jan 2013, volume: 30, issue:1, pages: 184 - 182
Publisher: IEEE
 
» Face Hallucination via Similarity Constraints
Abstract:
In this letter, we present a new face hallucination method based on similarity constraints to produce a high-resolution (HR) face image from an input low-resolution (LR) face image. This method is modeled as a local linear filtering process by incorporating four constraint functions at patch level. The first two constraints focus on checking if the training images are similar to the input face image. The third is defined in the HR face image, which is to impose the smoothness constraint between neighboring hallucinated patches. The final constraint computes the spatial distance to reduce the effect of patches that are far from the hallucinating patch. Experimental evaluation on a number of face images demonstrates the good performance of the proposed method on the face hallucination task.
Autors: Li, H.;Xu, L.;Liu, G.;
Appeared in: IEEE Signal Processing Letters
Publication date: Jan 2013, volume: 20, issue:1, pages: 19 - 22
Publisher: IEEE
 
» Farewell state of the journal
Abstract:
The current Editor-in-Chief announces that Professor David Forsyth will serve as the next Editor-in-Chief of the IEEE Transactions on Pattern Analysis and Machine Intelligence. David is well known within the computer vision community for the depth and breadth of his research contributions and interests. He has also served in a large number of leadership roles, including organizing the main vision conferences several times, coauthoring a widely used textbook, and running important committees. He has been an associate editor of TPAMI, and has been deeply involved in various discussions about the relationship between the computer vision community and the IEEE Computer Society. I have great confidence that David will uphold the high standards of the journal, and under his leadership it will continue to serve the community admirably. A breif professional biography of Prof. Forsyth is provided.
Autors: Zabih, Ramin;
Appeared in: IEEE Transactions on Pattern Analysis and Machine Intelligence
Publication date: Jan 2013, volume: 35, issue:1, pages: 1 - 2
Publisher: IEEE
 
» Fast FIR Algorithms for the Continuous Wavelet Transform From Constrained Least Squares
Abstract:
New algorithms for the continuous wavelet transform are developed that are easy to apply, each consisting of a single-pass finite impulse response (FIR) filter, and several times faster than the fastest existing algorithms. The single-pass filter, named WT-FIR-1, is made possible by applying constraint equations to least-squares estimation of filter coefficients, which removes the need for separate low-pass and high-pass filters. Non-dyadic two-scale relations are developed and it is shown that filters based on them can work more efficiently than dyadic ones. Example applications to the Mexican hat wavelet are presented.
Autors: Leigh, G. M.;
Appeared in: IEEE Transactions on Signal Processing
Publication date: Jan 2013, volume: 61, issue:1, pages: 28 - 37
Publisher: IEEE
 
» Fast Flux Linkage Measurement for Switched Reluctance Motors Excluding Rotor Clamping Devices and Position Sensors
Abstract:
It is essential to experimentally determine the profile of flux linkage, current, and position of a switched reluctance motor (SRM) in both design verifications and high-performance control implementations. In this paper, a fast measurement method of the flux linkage profile is proposed. In the proposed method, the rotor is first rotated to the aligned position, and then, the voltage pulses are applied to all phases simultaneously. The dc voltage and phase current waveforms are recorded to estimate the flux linkage curves at three different positions. These curves are used to calculate the coefficients of a second-order Fourier series flux linkage model, which represents the entire flux linkage profile of an SRM. The feasibility and accuracy of the proposed method are verified by experimental study with an 8/6 SRM. The impacts of rotor misalignment and phase couplings are investigated. A comparative study with the well-recognized rotor clamping method is given to demonstrate the advantages of the proposed method. The proposed method eliminates the requirements on rotor clamping devices or position sensors; therefore, it is suitable for product test in massive production and fast field measurement.
Autors: Shen, L.;Wu, J.;Yang, S.;Huang, X.;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: Jan 2013, volume: 62, issue:1, pages: 185 - 191
Publisher: IEEE
 

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