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IEEE International Workshop on Imaging Systems and Techniques (IST)

作者： Marios Antonakakis Stavros I. Dimitriadis Andrew C. Papanicolaou George Zouridakis Michalis Zervakis Digital Image and Signal Processing Laboratory School of Electronic and Computer Engineering Technical University of Crete Chania Greece Neuroinformatics Group Aristotle University Thessaloniki Greece Cardiff University Brain Research Imaging Centre (CUBRIC) School of Psychology Cardiff University Cardiff United Kingdom Departments of Pediatrics and Anatomy and Neurobiology University of Tennessee Health Science Center Memphis TN USA Neuroscience Institute Le Bonheur Children's Hospital Memphis TN USA Departments of Engineering Technology Computer Science Biomedical Engineering and Electrical and Computer Engineering University of Houston Houston TX USA

ISBN: (纸本)9781509018185

Diagnosis of mild Traumatic Brain Injury (mTBI) is difficult due to the variability of obvious brain lesions using imaging scans. A promising tool for exploring potential biomarkers for mTBI is magnetoencephalography which has the advantage of high spatial and temporal resolution. By adopting proper analytic tools from the field of symbolic dynamics like Lempel-Ziv complexity, we can objectively characterize neural network alterations compared to healthy control by enumerating the different patterns of a symbolic sequence. This procedure oversimplifies the rich information of brain activity captured via MEG. For that reason, we adopted neural-gas algorithm which can transform a time series into more than two symbols by learning brain dynamics with a small reconstructed error. The proposed analysis was applied to recordings of 30 mTBI patients and 50 normal controls in δ frequency band. Our results demonstrated that mTBI patients could be separated from normal controls with more than 97% classification accuracy based on high complexity regions corresponding to right frontal areas. In addition, a reverse relation between complexity and transition rate was demonstrated for both groups. These findings indicate that symbolic complexity could have a significant predictive value in the development of reliable biomarkers to help with the early detection of mTBI.

关键词： Complexity theory Time series analysis Sensitivity Integrated circuits Indexes Brain Laplace equations

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Improved Indoor VLC MIMO Channel Capacity Using Mobile Receiver with Angular Diversity Detectors

Improved Indoor VLC MIMO Channel Capacity Using Mobile Recei...

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IEEE Global Communications Conference

作者： P. Fahamuel J. Thompson H. Haas Institute for Digital Communications Joint Research Institute for Signal and Image Processing University of Edinburgh

ISBN: (纸本)9781479935130

A mobile receiver with angular diversity detectors in Visible Light Communication (VLC) Multiple Input Multiple Output (MIMO) channels is considered. The objective is to improve the rank of the channel matrix and hence system throughput. Repetition Coding, Spatial Multiplexing and Spatial Modulation concepts are used to evaluate throughputs across multiple locations in a small room scenario. Since the receiver is mobile, the channel gains are weak in some locations of the room due to the lack of Line of Sight (LOS) paths between transmitters and receivers. Therefore we use Adaptive Modulation and Per Antenna Rate Coding (PARC) are used to improve spectral efficiency. The throughputs for fixed transmitters and receivers are compared with the oriented/inclined detectors for different cases. The results shows that for the mobile receivers, oriented/inclined detectors with Adaptive modulation and PARC provides capacity improvement when compared with the fixed and vertically oriented receivers.

关键词： Angular diversity detectors Adaptive Spatial Modulation Per antenna Rate Control (PARC) Adaptive Modulation and Coding (AMC)

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LOOK WHO'S TALKING: DETECTING THE DOMINANT SPEAKER IN A CLUTTERED SCENARIO

LOOK WHO'S TALKING: DETECTING THE DOMINANT SPEAKER IN A CLUT...

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IEEE International Conference on Acoustics, Speech and signal processing

作者： Eleonora D'Arca Neil M. Robertson James R. Hopgood Joint Research Institute for Signal and Image Processing Heriot-Watt University & University of Edinburgh UK

ISBN: (纸本)9781479928941

In this work we propose a novel method to automatically detect and localise the dominant speaker in an enclosed scenario by means of audio and video cues. The underpinning idea is that gesturing means speaking, so observing motions means observing an audio signal. To the best of our knowledge state-of-the-art algorithms are focussed on stationary motion scenarios and close-up scenes where only one audio source exists, whereas we enlarge the extent of the method to larger field of views and cluttered scenarios including multiple non-stationary moving speakers. In such contexts, moving objects which are not correlated to the dominant audio may exist and their motion may incorrectly drive the audio-video (AV) correlation estimation. This suggests extra localisation data may be fused at decision level to avoid detecting false positives. In this work, we learn Mel-frequency cepstral coefficients (MFCC) coefficients and correlate them to the optical flow. We also exploit the audio and video signals to estimate the position of the actual speaker, narrowing down the visual space of search, hence reducing the probability of incurring in a wrong voice-to-pixel region association. We compare our work with a state-of-the-art existing algorithm and show on real datasets a 36% precision improvement in localising a moving dominant speaker through occlusions and speech interferences.

关键词： Correlation Speech Mel frequency cepstral coefficient Speech processing Acceleration Vectors

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Wavelet sparse representation based beam-forming for ultrasound imaging: Theory and simulation

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Metallurgical and Mining Industry 2015年第9期7卷 777-781页

作者： Zhang, Qiong Shen, Minfen Li, Bin Cheng, Cheng College of Engineering Shantou University Shantou Guangdong China Guangdong Provincial Key Laboratory of Digital Signal and Image Processing Techniques Shantou Guangdong China Shantou Polytechnic Shantou Guangdong China Shantou Institute of Ultrasonic Instruments Co. Ltd. Shantou Guangdong China Dept of Intelligent Multimedia Technology Research Center Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing China

In this paper, a wavelet sparse representation based beamforming is proposed to improve the resolution and contrast of plane wave emission ultrasound imaging. First, the received signals are described as the convolution of the target scatterers with the point spread function of the system. And then, the wavelet sparse representation model is deduced according to the fact that the target scatterers can be sparse represented in wavelet domain. The proposed algorithm was tested with simulated ultrasound data in plane wave emission. And the results demonstrated that the resolution was clearly improved and contrast ratio gains of 9.8 dB, 4.3 dB and 3.7 dB were obtained compared to delay-and-sum beamformer, minimum variance beamformer and phase coherence factor, respectively.

关键词： Optical transfer function

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A Performance Study of Spatial Modulation Systems Under Vehicle-to-Vehicle Channel Models

A Performance Study of Spatial Modulation Systems Under Vehi...

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IEEE Vehicular Technology Conference

作者： Yu Fu Cheng-Xiang Wang Raed Mesleh Xiang Cheng Harald Haas Yejun He Joint Research Institute for Signal and Image Processing Heriot-Watt University School of Information Science and Engineering Shandong University Electrical Engineering Department and SNCS Research Center University of Tabuk School of Electronics Engineering & Computer Science Peking University Joint Research Institute for Signal and Image Processing University of Edinburgh College of Information Engineering Shenzhen University

ISBN: (纸本)9781479944811

Spatial modulation (SM) is a relatively new multiple-input multiple-output (MIMO) technology that can provide high data rate with reasonable spectral efficiency. In this paper, the bit error rate (BER) performance of SM systems under vehicle-to-vehicle (V2V) channel models is investigated. The theoretical BER expression is given. The impact of some V2V channel model parameters on the underlying space-time correlation function (STCF) and the BER performance of SM systems are also studied. Simulation results indicate that modulation schemes, maximum Doppler frequency, the distance between the transmitter (Tx) and receiver (Rx), and antenna element spacings can affect the performance of SM systems.

关键词： Spatial modulation Vehicle-to-vehicle channel model Bit error rate Space-time correlation function

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Multiuser Massive MIMO Uplink Performance with Mutual Coupling Effects

Multiuser Massive MIMO Uplink Performance with Mutual Coupli...

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IEEE Global Communications Conference

作者： Ran Zi Xiaohu Ge Haichao Wang Jing Zhang Cheng-Xiang Wang Dept. Electronics & Information Engineering Huazhong University of Science & Technology Joint Research Institute for Signal and Image Processing School of Engineering & Physical Sciences Heriot-Watt University

ISBN: (纸本)9781479935130

A multiuser massive MIMO system with mutual coupling is investigated in finite-dimensional channel scenarios. The uplink ergodic achievable rate is analytically derived for a multiuser massive MIMO system equipped with a rectangular planar uniform antenna array at the base station (BS). Numerical results show that the mutual coupling effect reduces the uplink achievable rate of multiuser massive MIMO systems when the antenna distance decreases. But when the size of the antenna array is fixed, the uplink achievable rate increases with the growing of antenna number.

关键词： Massive MIMO Mutual coupling Multiuser MIMO Finite-dimensional channel

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Determining interval type-2 fuzzy set models for words using data collected from one subject: Person FOUs

Determining interval type-2 fuzzy set models for words using...

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IEEE International Conference on Fuzzy Systems (FUZZ-IEEE)

作者： Jerry M. Mendel Dongrui Wu Signal and Image Processing Institute University of Southern California Los Angeles CA USA Machine Learning Laboratory GE Global Research Niskayuna NY USA

This paper provides a new methodology for determining a word's interval type-2 fuzzy set model using only one subject, a Person FOU. It uses interval end-point uncertainty intervals instead of only the end-point intervals. Such uncertainty intervals are relatively easy to collect and they do not introduce methodological uncertainties during the data-collection process. This new method is applied to ten probability words. Person FOUs are obtained for these words, and the robustness of this new method to the choice of the probability distribution that is assigned to the interval end-point uncertainty intervals is examined and demonstrated.

关键词： Uncertainty Data models Fuzzy sets Frequency selective surfaces Robustness Computational modeling Standards

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A GRAPH-BASED joint BILATERAL APPROACH FOR DEPTH ENHANCEMENT

A GRAPH-BASED JOINT BILATERAL APPROACH FOR DEPTH ENHANCEMENT

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IEEE International Conference on Acoustics, Speech and signal processing

作者： Yongzhe Wang Antonio Ortega Dong Tian Anthony Vetro Signal and Image Processing Institute University of Southern California Los Angeles California USA Multimedia Group Mitsubishi Electric Research Labs (MERL) Cambridge Massachusetts USA

ISBN: (纸本)9781479928941

Depth images are often presented at a lower spatial resolution, either due to limitations in the acquisition of the depth or to increase compression efficiency. As a result, upsampling low-resolution depth images to a higher spatial resolution is typically required prior to depth image based rendering. In this paper, depth enhancement and up-sampling techniques are proposed using a graph-based formulation. In one scheme, the depth is first upsampled using a conventional method, then followed by a graph-based joint bilateral filtering to enhance edges and reduce noise. A second scheme avoids the two-step processing and upsamples the depth directly using the proposed graph-based joint bilateral upsampling. Both filtering and interpolation problems are formulated as regularization problems and the solutions are different from conventional approaches. Further, we also studied operations on different graph structures such as star graph and 8-connected graph. Experimental results show that the proposed methods produce slightly more accurate depth at the full resolution with improved rendering quality of intermediate views.

关键词： joints image edge detection Three-dimensional displays Laplace equations Noise reduction Conferences signal processing

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SU-E-T-436: Fluence-Based Trajectory Optimization for Non-Coplanar VMAT

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Medical Physics 2015年第6PART19期42卷 3434-3434页

作者： G Smyth PM Evans JC Bamber FH Saran HC Mandeville JL Bedford Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust London UK Centre for Vision Speech and Signal Processing University of Surrey Guildford UK The Royal Marsden NHS Foundation Trust Sutton UK

Purpose: To investigate a fluence-based trajectory optimization technique for non-coplanar VMAT for brain cancer. Methods: Single-arc non-coplanar VMAT trajectories were determined using a heuristic technique for five patients. Organ at risk (OAR) volume intersected during raytracing was minimized for two cases: absolute volume and the sum of relative volumes weighted by OAR importance. These trajectories and coplanar VMAT formed starting points for the fluence-based optimization method. Iterative least squares optimization was performed on control points 24° apart in gantry rotation. Optimization minimized the root-mean-square (RMS) deviation of PTV dose from the prescription (relative importance 100), maximum dose to the brainstem (10), optic chiasm (5), globes (5) and optic nerves (5), plus mean dose to the lenses (5), hippocampi (3), temporal lobes (2), cochleae (1) and brain excluding other regions of interest (1). Control point couch rotations were varied in steps of up to 10° and accepted if the cost function improved. Final treatment plans were optimized with the same objectives in an in-house planning system and evaluated using a composite metric - the sum of optimization metrics weighted by importance. Results: The composite metric decreased with fluence-based optimization in 14 of the 15 plans. In the remaining case its overall value, and the PTV and OAR components, were unchanged but the balance of OAR sparing differed. PTV RMS deviation was improved in 13 cases and unchanged in two. The OAR component was reduced in 13 plans. In one case the OAR component increased but the composite metric decreased - a 4 Gy increase in OAR metrics was balanced by a reduction in PTV RMS deviation from 2.8% to 2.6%. Conclusion: Fluence-based trajectory optimization improved plan quality as defined by the composite metric. While dose differences were case specific, fluence-based optimization improved both PTV and OAR dosimetry in 80% of cases.

关键词： Optimization Brain Auditory system Dosimetry Cancer Lenses

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Capacity Analysis of Finite Scatterer MIMO Wireless Channels

Capacity Analysis of Finite Scatterer MIMO Wireless Channels

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IEEE International Conference on Communications

作者： Shangbin Wu Cheng-Xiang Wang Bo Ai Yejun He Joint Research Institute for Signal and Image Processing Heriot-Watt University Edinburgh UK State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing China College of Information Engineering Shenzhen University Shenzhen Guangdong China

This paper analyzes the capacity of the finite scatterer (FS) multiple-input multiple-output (MIMO) channel model with finite angular resolution. The rank of the channel is bounded by not only the number of antennas but also the finite angular resolution of antenna arrays. The probability mass function (PMF) of rank is studied and derived based on the Stirling number of the second kind. As a result, the closed-form expression of the capacity of a FS MIMO channel model is obtained. Furthermore, asymptotic analyses such as the large-scale system analysis, infinite scatterer analysis, and the multiplexing gain analysis are investigated.

关键词： MIMO Antenna arrays Channel models Directive antennas Channel capacity Receivers Multiplexing

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