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作者： Xiang, Lin Kwan Ng, Derrick Wing Islam, Toufiqul Schober, Robert Vincent, W.S. Wang, Jiaheng Institute for Digital Communications Friedrich-Alexander University of Erlangen-Nuremberg Erlangen91058 Germany School of Electrical Engineering and Telecommunications University of New South Wales SydneyNSW2052 Australia Huawei Canada Research Center OttawaONK2K 3J1 Canada Department of Electrical and Computer Engineering University of British Columbia VancouverBCV6T 1Z4 Canada National Mobile Communications Research Laboratory Southeast University Nanjing210018 China

In this paper, we investigate the cross-layer optimization of caching and fast video delivery for enhanced video streaming quality of experience in two-hop relaying networks, where a base station supplies video data to multiple users with the help of relays. Different from conventional systems, each half-duplex relay node is equipped with a cache and a buffer to facilitate joint scheduling of video fetching and delivery. This introduces channel diversity gains and facilitates fast video delivery. In particular, we investigate two-stage caching and delivery control schemes for the minimization of the overall video delivery time. An offline caching and delivery optimization problem, which assumes full knowledge of user requests and channel state information (CSI), is formulated but turns out to be functional and nonconvex. However, we unveil a hidden quasi-convexity and convexity in the two layers of the decomposed problem and, hence, solve the offline problem optimally and efficiently. Moreover, online video delivery control exploiting statistical CSI is investigated under a stochastic dynamic programming (DP) framework. To mitigate the high computational complexity of DP, we further propose a low-complexity online video delivery algorithm, which achieves close-to-optimal performance in the high buffer capacity regime. Simulation results show that our offline and online schemes can significantly reduce the overall video delivery time due to the degrees of freedom enabled by caching and buffering. Besides, an interesting tradeoff between caching and buffering gains in exploiting the diversity of the wireless channel is revealed. © 2017 IEEE.

关键词： Channel state information

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Computational study of amplitude-to-phase conversion in a Modified Uni-Traveling Carrier (MUTC) photodetector

arXiv

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arXiv 2017年

作者： Hu, Yue Menyuk, Curtis R. Xie, Xiaojun Hutchinson, Meredith N. Urick, Vincent J. Campbell, Joe C. Williams, Keith J. Computer Science and Electrical Engineering Department University of Maryland Baltimore County BaltimoreMD21250 United States Electrical and Computer Engineering University of Virginia CharlottesvilleVA22904 United States Naval Research Laboratory Photonics Technology Branch WashingtonDC20375 United States

We calculate the amplitude-to-phase (AM-to-PM) noise conversion in a modified uni-traveling carrier (MUTC) photodetector. We obtained two nulls as measured in the experiments, and we explain their origin. The nulls appear due to the transit time variation when the average photocurrent varies, and the transit time variation is due to the change of electron velocity when the average photocurrent varies. We also show that the AM-to-PM conversion coefficient depends only on the pulse energy and is independent of the pulse duration when the duration is less than 500 fs. When the pulse duration is larger than 500 fs, the nulls of the AM-to-PM conversion coefficient shift to larger average photocurrents. This shift occurs because the increase in that pulse duration leads to a decrease in the peak photocurrent. The AM-to-PM noise conversion coefficient changes as the repetition rate varies. However, the repetition rate does not change the AM-to-PM conversion coefficient as a function of input optical pulse energy. The repetition rate changes the average photocurrent. We propose a design that would in theory improve the performance of the device. Copyright © 2017, The Authors. All rights reserved.

关键词： Pulse repetition rate

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Robust sonar ATR through bayesian pose corrected sparse classification

arXiv

引用

arXiv 2017年

作者： McKay, John Monga, Vishal Raj, Raghu G. Department of Electrical and Computer Engineering Pennsylvania State University University ParkPA United States U.S. Naval Research Laboratory WashingtonDC United States

Sonar imaging has seen vast improvements over the last few decades due in part to advances in synthetic aperture Sonar (SAS). Sophisticated classification techniques can now be used in Sonar automatic target recognition (ATR) to locate mines and other threatening objects. Among the most promising of these methods is sparse reconstruction-based classification (SRC) which has shown an impressive resiliency to noise, blur, and occlusion. We present a coherent strategy for expanding upon SRC for Sonar ATR that retains SRC's robustness while also being able to handle targets with diverse geometric arrangements, bothersome Rayleigh noise, and unavoidable background clutter. Our method, pose corrected sparsity (PCS), incorporates a novel interpretation of a spike and slab probability distribution towards use as a Bayesian prior for class-specific discrimination in combination with a dictionary learning scheme for localized patch extractions. Additionally, PCS offers the potential for anomaly detection in order to avoid false identifications of tested objects from outside the training set with no additional training required. Compelling results are shown using a database provided by the United States Naval Surface Warfare Center. Copyright © 2017, The Authors. All rights reserved.

关键词： Automatic target recognition

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Fast integral histogram computations on GPU for real-time video analytics

arXiv

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arXiv 2017年

作者： Poostchi, Mahdieh Palaniappan, Kannappan Li, Da Becchi, Michela Bunyak, Filiz Seetharaman, Guna Department of Electrical Engineering and Computer Science University of Missouri-Columbia ColumbiaMO65211 United States Air Force Research Laboratory RomeNY13441 United States

In many Multimedia content analytics frameworks feature likelihood maps represented as histograms play a critical role in the overall algorithm. Integral histograms provide an efficient computational framework for extracting multi-scale histogram-based regional descriptors in constant time which are considered as the principle building blocks of many video content analytics frameworks. We evaluate four different mappings of the integral histogram computation onto Graphics Processing Units (GPUs) using different kernel optimization strategies. Our kernels perform cumulative sums on row and column histograms in a cross-weave or wavefront scan order, use different data organization and scheduling methods that is shown to critically affect utilization of GPU resources (cores and shared memory). Tiling the 3-D array into smaller regular data blocks significantly speeds up the efficiency of the computation compared to a strip-based organization. The tiled integral histogram using a diagonal wavefront scan has the best performance of about 300.4 frames/sec for 640 × 480 images and 32 bins with a speedup factor of about 120 using GTX Titan X graphics card compared to a single threaded sequential CPU implementation. Double-buffering has been exploited to overlap computation and communication across sequence of images. Mapping integral histogram bins computations onto multiple GPUs enables us to process 32 giga bytes integral histogram data (of 64MB Image and 128 bins) with a frame rate of 0.73 Hz and speedup factor of 153X over single-threaded CPU implementation and the speedup of 45X over 16-threaded CPU implementation. Copyright © 2017, The Authors. All rights reserved.

关键词： Wavefronts

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A game-theoretic taxonomy and survey of defensive deception for cybersecurity and privacy

arXiv

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arXiv 2017年

作者： Pawlick, Jeffrey Colbert, Edward Zhu, Quanyan Department of Electrical and Computer Engineering New York University Tandon School of Engineering 5 MetroTech Center BrooklynNY United States Us Army Research Laboratory 2800 Powder Mill Road AdelphiMD United States Us Army Research Laboratory Virgina Tech Intelligent Systems Laboratory Hume Center for National Security and Technology 900 N. Glebe Road ArlingtonVA United States Department of Electrical and Computer Engineering New York University Tandon School of Engineering

Cyberattacks on both databases and critical infrastructure have threatened public and private sectors. Ubiquitous tracking and wearable computing have infringed upon privacy. Advocates and engineers have recently proposed using defensive deception as a means to leverage the information asymmetry typically enjoyed by attackers as a tool for defenders. The term deception, however, has been employed broadly and with a variety of meanings. In this paper, we survey 24 articles from 2008-2018 that use game theory to model defensive deception for cybersecurity and privacy. Then we propose a taxonomy that defines six types of deception: perturbation, moving target defense, obfuscation, mixing, honey-x, and attacker engagement. These types are delineated by their information structures, agents, actions, and duration: precisely concepts captured by game theory. Our aims are to rigorously define types of defensive deception, to capture a snapshot of the state of the literature, to provide a menu of models which can be used for applied research, and to identify promising areas for future work. Our taxonomy provides a systematic foundation for understanding different types of defensive deception commonly encountered in cybersecurity and privacy. Copyright © 2017, The Authors. All rights reserved.

关键词： Surveys

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A core-shell nanowire platform for silicon photonics

A core-shell nanowire platform for silicon photonics

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Frontiers in Optics, FiO 2017

作者： Wang, Zhihuan Dianat, Pouya Montazeri, Kiana Taskin, Baris Currie, Marc Prete, Paola Lovergine, Nico Nabet, Bahram Electrical and Computer Engineering Department Drexel University PhiladelphiaPA19104 United States Center for Quantum Devices Northwestern University EvanstonIL60208 United States Optical Sciences Division Naval Research Laboratory WashingtonDC20375 United States IMM-CNR Institute for Microelectronics and Microsystems Via Monteroni LecceI-73100 Italy Department of Innovation Engineering University of Salento Via Arnesano LecceI-73100 Italy

Core-shell nanowires are versatile optoelectronic devices that can serve as light emitters, detectors, and modulators. Here we offer a high-performance low-cost platform for heterogeneous photonic integrated circuits ... 详细信息

ISBN: (纸本)9781943580330

关键词： Silicon photonics

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Evolution of Metallicity in Vanadium Dioxide by Creation of Oxygen Vacancies

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Physical Review Applied 2017年第3期7卷 034008-034008页

作者： Zhen Zhang Fan Zuo Chenghao Wan Aveek Dutta Jongbum Kim Jura Rensberg Ronny Nawrodt Helen Hejin Park Thomas J. Larrabee Xiaofei Guan You Zhou S. M. Prokes Carsten Ronning Vladimir M. Shalaev Alexandra Boltasseva Mikhail A. Kats Shriram Ramanathan School of Materials Engineering Purdue University West Lafayette Indiana 47907 USA Department of Electrical and Computer Engineering Department of Materials Science and Engineering University of Wisconsin-Madison Madison Wisconsin 53706 USA School of Electrical and Computer Engineering and Birck Nanotechnology Center Purdue University West Lafayette Indiana 47907 USA Institute for Solid State Physics Friedrich Schiller University Jena 07743 Jena Germany United States Naval Research Laboratory Washington D.C. 20375 USA American Society for Engineering Education Research Associate at the Naval Research Laboratory Washington D.C. 20375 USA National Research Council Research Associate at the Naval Research Laboratory Washington D.C. 20375 USA John A. Paulson School of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 USA Department of Chemistry and Chemical Biology Harvard University Cambridge Massachusetts 02138 USA

Tuning of the electronic state of correlated materials is key to their eventual use in advanced electronics and photonics. The prototypical correlated oxide (VO2) is insulating at room temperature and transforms to a metallic state when heated to 67 °C (340 K). We report the emergence of a metallic state that is preserved down to 1.8 K by annealing thin films of VO2 at an ultralow oxygen partial pressure (PO2∼10−24 atm). The films can be reverted back to their original state by annealing in oxygen, and this process can be iterated multiple times. The metallic phase created by oxygen deficiency has a tetragonal rutile structure and contains a large number of oxygen vacancies far beyond the solubility at equilibrium (greater than approximately 50 times). The oxygen starvation reduces the oxidation state of vanadium from V4+ to V3+ and leads to the metallization. The extent of resistance reduction (concurrent with tuning of optical properties) can be controlled by the time-temperature envelope of the annealing conditions since the process is diffusionally driven. This experimental platform, which can extensively tune oxygen vacancies in correlated oxides, provides an approach to study emergent phases and defect-mediated adaptive electronic and structural phase boundary crossovers.

关键词： Defects Insulators Metal-insulator transition Annealing

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Electro-optically sampled time response of core- shell nanowires

Electro-optically sampled time response of core- shell nanow...

引用

Frontiers in Optics, FiO 2017

作者： Currie, M. Persano, A. Taurino, A. Quaranta, F. Cola, A. Prete, P. Lovergine, N. Dianat, P. Wang, Z. Nabet, B. Optical Sciences Division Naval Research Laboratory WashingtonDC20375 United States IMM-CNR Institute for Microelectronics and Microsystems Via Monteroni LecceI-73100 Italy Department of Innovation Engineering University of Salento Via Arnesano LecceI-73100 Italy Center for Quantum Devices Northwestern University EvanstonIL60208 United States Electrical and Computer Engineering Department Drexel University PhiladelphiaPA19104 United States

We present time response measurements of single GaAs/AlGaAs core-shell nanowire using high-resolution electro-optic sampling technique. These nanowires show high quantum efficiency and a response speed faster than com... 详细信息

ISBN: (纸本)9781943580330

关键词： Nanowires

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Shape-independent hardness estimation using deep learning and a GelSight tactile sensor

Shape-independent hardness estimation using deep learning an...

引用

IEEE International Conference on Robotics and Automation (ICRA)

作者： Wenzhen Yuan Chenzhuo Zhu Andrew Owens Mandayam A. Srinivasan Edward H. Adelson Department of Mechanical Engineering Computer Science and Artificial Intelligence Laboratory (CSAIL) Cambridge MA USA CSAIL MIT Cambridge MA USA Department of Electronical Engineering Tsinghua University Beijing China Electrical Engineering and Computer Science Department MIT Cambridge MA USA Computer Science Department UCL TouchLab London UK Department of Mechanical Engineering Research Laboratory of Electronics Cambridge MA USA Department of Brain and Cognitive Sciences and CSAIL MIT Cambridge MA USA

Hardness is among the most important attributes of an object that humans learn about through touch. However, approaches for robots to estimate hardness are limited, due to the lack of information provided by current tactile sensors. In this work, we address these limitations by introducing a novel method for hardness estimation, based on the GelSight tactile sensor, and the method does not require accurate control of contact conditions or the shape of objects. A GelSight has a soft contact interface, and provides high resolution tactile images of contact geometry, as well as contact force and slip conditions. In this paper, we try to use the sensor to measure hardness of objects with multiple shapes, under a loosely controlled contact condition. The contact is made manually or by a robot hand, while the force and trajectory are unknown and uneven. We analyze the data using a deep constitutional (and recurrent) neural network. Experiments show that the neural net model can estimate the hardness of objects with different shapes and hardness ranging from 8 to 87 in Shore 00 scale.

关键词： Force Tactile sensors Force measurement Shape Geometry

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Brain perfusion mediates the relationship between miRNA levels and postural control

arXiv

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arXiv 2019年

作者： Chen, Yufen Herrold, Amy A. Martinovich, Zoran Blood, Anne J. Vike, Nicole Walter, Alexa E. Harezlak, Jaroslaw Seidenberg, Peter H. Bhomia, Manish Knollmann-Ritschel, Barbara Reilly, James L. Nauman, Eric A. Talavage, Thomas M. Papa, Linda Slobounov, Semyon Breiter, Hans C. Center for Translational Imaging Department of Radiology Feinberg School of Medicine Northwestern University ChicagoIL60611 United States Edward Hines Jr. VA Hospital Research Service HinesIL60141 United States Warren Wright Adolescent Center Department of Psychiatry and Behavioral Sciences Feinberg School of Medicine Northwestern University ChicagoIL60611 United States Mental Health Services and Policy Program Department of Psychiatry and Behavioral Sciences Northwestern University Feinberg School of Medicine ChicagoIL60611 United States Mood and Motor Control Laboratory Departments of Neurology and Psychiatry Massachusetts General Hospital Harvard Medical School BostonMA02129 United States Laboratory of Neuroimaging and Genetics Department of Psychiatry Massachusetts General Hospital Harvard Medical School BostonMA02129 United States Martinos Center for Biomedical Imaging Department of Radiology Massachusetts General Hospital Harvard Medical School BostonMA02129 United States School of Electrical and Computer Engineering Purdue University West LafayetteIN47907 United States Weldon School of Biomedical Engineering Purdue University West LafayetteIN47907 United States Department of Kinesiology Pennsylvania State University University ParkPA16802 United States Department of Epidemiology and Biostatistics Indiana University BloomingtonIN47405 United States Departments of Orthopaedics & Rehabilitation and Family & Community Medicine Penn State College of Medicine HersheyPA17033 Department of Pathology Uniformed Services University of the Health Sciences BethesdaMD United States Department of Basic Medical Sciences Purdue University West LafayetteIN47907 United States Department of Emergency Medicine Orlando Regional Medical Center OrlandoFL United States

Transcriptomics, regional cerebral blood flow (rCBF), and a spatial motor virtual reality task were integrated using mediation analysis in a novel demonstration of "imaging omics". Data collected in NCAA Division I football athletes cleared for play before in-season training showed significant relationships in a) elevated levels of miR-30d and miR-92a to elevated putamen rCBF, (b) elevated putamen rCBF to compromised balance scores, and (c) compromised balance scores to elevated miRNA levels. rCBF acted as a mediator variable (minimum 70% mediation, significant Sobel's test) between abnormal miRNA levels and compromised balance scores. Given the involvement of these miRNAs in inflammation and immune function, and that vascular perfusion is a component of the inflammatory response, these findings support a chronic inflammatory model of repetitive head acceleration events (HAEs). rCBF, a systems biology measure, was necessary for miRNA to affect behavior. These results suggest miRNA as a potential diagnostic biomarker for repetitive HAEs. Copyright © 2019, The Authors. All rights reserved.

关键词： Sports

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