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作者： Jeong, Intae Kwon, Jooseong Kim, Changsoon Park, Young June Program in Nano Science and Technology Graduate School of Convergence Science and Technology Seoul National University Seoul 151-742 Korea Republic of Department of Electrical and Computer Engineering School of Engineering Seoul National University Seoul 151-747 Korea Republic of Advanced Institutes of Convergence Technology Suwon Gyeonggi 443-270 Korea Republic of

Heavily-doped strained germanium (Ge) can emit light efficiently thanks to its pseudo direct band gap characteristic. This makes Ge a good candidate for on-chip monolithic light sources in silicon (Si) photonics systems. We propose fin-shaped Ge-Si heterojunction lightemitting diode (LED) with metal gates, which can enhance light emission by coupling with surface plasmon resonant modes and modulate light emission from the LED. We verify these two aspects through numerical analysis and device simulations. We develop the method to find the optimal device structure and specific device dimensions to maximize the spontaneous emission rate enhancement. Also we find that the LED can be modulated by a gate voltage bias. © 2014 Optical Society of America.

关键词： Surface plasmons

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Dirichlet tessellation for high-dimensional RSS clustering in Wi-Fi environment

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ICIC Express Letters 2014年第7期8卷 2043-2048页

作者： Zhou, Mu Tian, Zengshan Xu, Kunjie Tang, Xiaomou Chongqing Key Lab of Mobile Communications Technology Chongqing University of Posts and Telecommunications No. 2 Chongwen Road Nanan District Chongqing 400065 China Department of Electronic and Computer Engineering The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong Graduate Telecommunication and Networking Program School of Information Science University of Pittsburgh PA 15260 United States

The received signal strength (RSS) clustering has played a significant role in site surveying and data pre-processing for the location tracking in Wi-Fi environment. To this end, this paper presents a novel clustering algorithm to cluster the raw RSS vectors with large similarities in both the RSS and physical locations together. The clusters of RSS vectors are determined by the cells which are generated by the Dirichlet tessellation in a transformed low-dimensional space. Our algorithm consists of two steps. We first use the Laplacian embedding to transform the raw measurements into a low-dimensional space, while preserving the RSS and location neighborhood relations. Second, after the seeds of cells are carefully selected, we will tessellate the low-dimensional space by the Dirichlet cells to obtain the clustering results. The experiments conducted in an actual public Wi-Fi environment prove that our algorithm can achieve the smallest cluster scattering in both the RSS and locations compared with the existing affinity propagation clustering, K-means clustering and binary support vector classifier (SVC) algorithms. © 2014 ISSN 1881-803X.

关键词： Wi-Fi

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Flexible terahertz metamaterials for frequency selective surfaces

Flexible terahertz metamaterials for frequency selective sur...

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2013 Annual Conference on Experimental and Applied Mechanics

作者： Deibel, J.A. Jones, H.R. Fosnight, A. Shaver, R. Best, E. Langley, D. Starman, L.A. Coutu, R.A. Department of Physics and Engineering Physics Program Wright State University 3640 Colonel Glenn Highway Dayton OH 45435 United States Department of Electrical and Computer Engineering Air Force Institute of Technology Wright-Patterson AFB 2950 Hobson Way Dayton OH 45433 United States

ISBN: (纸本)9783319007793

While recent years have seen great advances in the generation, detection, and application of terahertz frequency radiation, this region of the electromagnetic spectrum still suffers from a lack of efficient and effective frequency specific optical components. While such terahertz devices do exist, they are often limited by the materials they are based on and a lack of frequency selectivity and tunability. Metamaterial devices can provide frequency resonant behavior in the form of transmissive and reflective filters. Such a frequency selective surface can also be made tunable via the use of a flexible substrate. In this talk, we will highlight work involving the design, fabrication, and characterization of terahertz metamaterial devices based on flexible substrates. Finite element method simulations have been utilized to design a split-ring resonator (SRR) structure on a flexible SU8 polymer substrate with a targeted 250 GHz resonant response. Multiple configurations of SRR arrays have been fabricated on free standing SU8 substrates. These devices have subsequently been characterized using terahertz time-domain spectroscopy and imaging systems. The metamaterial devices have shown selective transmission and reflection over a narrow range of frequencies near the targeted resonance at 250 GHz. Details of both the design, fabrication, and characterization will be discussed. © The Society for Experimental Mechanics, Inc. 2014.

关键词： Frequency selective surfaces

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Multi-radio over Fiber Architecture for Road Vehicle Communication in VANETs

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Procedia computer Science 2014年 32卷 1022-1029页

作者： H.H.R. Sherazi I. Raza M.H. Chaudary S.A. Hussain M.H. Raza Department of Computer Science COMSATS Institute of Information Technology Lahore 54000 Pakistan Department of Computer Science & IT Lahore Leeds University Lahore Pakistan Internetworking Program Faculty of Engineering Dalhousie University Canada

Vehicular Ad-hoc Networks (VANET) are employing heterogeneous technologies now a days to meet the increasing demands of Intelligent Transportation System (ITS) applications such as enriched multimedia, video conferencing, gaming and online collaboration. Deployment and maintenance cost for infrastructures are also a major concern. This work proposes a framework, capable of catering multiple technologies simultaneously (such as local area network, wide area networks and cellular networks), that deploys wired and wireless integrated technologies to exploit the advantages of both. Therefore, it offers the architecture based on radio over fiber technology to meet the future requirements of high data rate for Road Vehicle Communication (RVC) in VANETs and it comes up with the most important and perhaps desperately needed feature of ‘Future technology Support’ yielding very high data rates support. Several traditionally deployed architectures are striving to come up with the future needs but due to their various limitations they were unable to attain their expected outcomes. The proposed RoF based architecture justifies its need inducing a true value and powerful features to dramatically enhance the overall performance of the entire system. Several evaluation parameters have been chosen that clearly present the strength of proposed RoF framework and prove that RoF framework is the better option for the service providers in the area of ITS applications.

关键词： VANET intelligent transportation systems road vehicle communication radio-over-fiber radio access unit central site

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Using Stratified Attribute Tracking (SAT) Diagrams for Learning Analytics

Using Stratified Attribute Tracking (SAT) Diagrams for Learn...

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International Conference on Advanced Learning Technologies (ICALT)

作者： Rwitajit Majumdar Sridhar Iyer Inter-Disciplinary Program in Educational Technology Indian Institute of Technology Bombay Department of Computer Science and Engineering Indian Institute of Technology Bombay

We have created a visual representation called Stratified Attribute Tracking (SAT) Diagram to explicate trends that are otherwise implicit in learning analytics data. SAT Diagram is a unified graph that enables tracking individual attribute values in a dataset and stratifying them according to criteria set by the researcher. SAT diagram represents the transition of samples between strata across attributes. In this paper we introduce the SAT diagram and illustrate how to generate, interpret and analyze them. We believe the process of SAT diagram generation would enable exploring deeper research questions on learning data.

关键词： Educational technology Aggregates Visualization Data visualization Data mining Conferences Market research

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Improvement of Problem Solving Skills in engineering Drawing Using Blender Based Mental Rotation Training

Improvement of Problem Solving Skills in Engineering Drawing...

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International Conference on Advanced Learning Technologies (ICALT)

作者： Kapil Kadam Sridhar Iyer Inter-Disciplinary Program in Educational Technology Indian Institute of Technology Bombay Department of Computer Science and Engineering Indian Institute of Technology Bombay

First year undergraduate students in engineering often face difficulties in solving engineering drawing (ED) problems. The potential reasons for this could be either the students' deficiency in visualizing spatial relationships or the instructional method used. We have developed a three-hour MR training using Blender 3D, an open source 3D animation software. In this paper, we present experimental evidence of the effect of our training on the improvement of problem solving skills in ED. We analyzed the results and found them to be significant. Also, the qualitative analysis of students' responses to the open ended questions revealed that, they found training useful in resolving their difficulties in solving ED problems.

关键词： Training engineering drawings Problem-solving Visualization Three-dimensional displays engineering students

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Calibrationless parallel imaging reconstruction based on structured low-rank matrix completion

Calibrationless parallel imaging reconstruction based on str...

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作者： Shin, Peter J. Larson, Peder E. Z. Ohliger, Michael A. Elad, Michael Pauly, John M. Vigneron, Daniel B. Lustig, Michael Department of Radiology and Biomedical Imaging University of California at San Francisco San FranciscoCA United States UC Berkeley-UCSF Graduate Program in Bioengineering CA United States Department of Electrical Engineering and Computer Science University of California at Berkeley BerkeleyCA United States Department of Computer Science Technion'Israel Institute of Technology Haifa Israel Magnetic Resonance Systems Research Laboratory Department of Electrical Engineering Stanford University StanfordCA United States

Purpose: A calibrationless parallel imaging reconstruction method, termed simultaneous autocalibrating and k-space estimation (SAKE), is presented. It is a data-driven, coil-by-coil reconstruction method that does not require a separate calibration step for estimating coil sensitivity information. Methods: In SAKE, an undersampled, multichannel dataset is structured into a single data matrix. The reconstruction is then formulated as a structured low-rank matrix completion problem. An iterative solution that implements a projection-ontosets algorithm with singular value thresholding is described. Results: Reconstruction results are demonstrated for retrospectively and prospectively undersampled, multichannel Cartesian data having no calibration signals. Additionally, non-Cartesian data reconstruction is presented. Finally, improved image quality is demonstrated by combining SAKE with wavelet-based compressed sensing. Conclusion: Because estimation of coil sensitivity information is not needed, the proposed method could potentially benefit MR applications where acquiring accurate calibration data is limiting or not possible at all. © 2013 Wiley Periodicals, Inc.

关键词： Compressed sensing

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Optimal signal processing method in UWB radar for hidden human detection

Optimal signal processing method in UWB radar for hidden hum...

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作者： Karamzadeh, Saeid Kartal, Mesut Kent, Sedef Ashtiyani, A. Abed Informatics Institute Department of Advanced Technology Satellite Communication and Remote Sensing Program Istanbul Technical University Turkey Department of Electronics and Communications Faculty of Electrical and Electronic Engineering Istanbul Technical University Turkey Faculty of Electric and Computer University of Tabriz Iran

Today, human detection and tracking is important challenge for many aims. In this study, we are used Ultra Wide Band (UWB) radar for human respiratory detection behind a wall. The modulated system to get the breathing signal is introduced. The results of simulation part of the established system are presented. Suitable antenna for using as a transmitter and receiver is being discussed. Different signal processing methods are debated and optimal method is introduced for various environments. © VDE VERLAG GMBH · Berlin · Offenbach, Germany.

关键词： Antennas

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FPGA-based hardware/software implementation for MIMO wireless communications

FPGA-based hardware/software implementation for MIMO wireles...

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International Electrical engineering Congress (iEECON)

作者： Korkeart Boonyi Jukkrit Tagapanij Akkarat Boonpoonga Electrical Engineering Graduate Program Telecommunication Engineering Department Mahanakom University of Technology Bangkok Thailand Department of Electrical and Computer Engineering King Mongkut's University of Technology North Bangkok Bangkok Thailand

This paper proposes an efficient architecture for FPGA implementation of MGS-QRD in MIMO wireless communication systems. The proposed architecture is based on the Hardware/Software (HW/SW) design. To achieve the efficient architecture, the systolic architecture is applied to MGS-QRD and then the conventional QR triangular array of (2m 2 +2m+1) cells onto a linear architecture of m+1 cell is employed to reduce the number of required QR processors. The reduced cells are constructed with a number of basic processing elements such as multipliers and adders etc. The basic elements are constructed by HW architectures. The SW of PowerPC core is used to control to achieve the QR decomposition. In this paper, utilization resource and operation performance in term of equivalent gates and operating cycles are shown.

关键词： Matrix decomposition MIMO Field programmable gate arrays Wireless communication Detectors Silicon Random access memory

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Comparative study of leaf image recognition with a novel learning-based approach

Comparative study of leaf image recognition with a novel lea...

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Science and Information Conference (SAI)

作者： Jou-Ken Hsiao Li-Wei Kang Ching-Long Chang Chih-Yang Lin Department of Computer Science and Information Engineering National Yunlin University of Science and Technology Yunlin Taiwan Graduate School of Engineering Science and Technology-Doctoral Program National Yunlin University of Science and Technology Yunlin Taiwan Department of Computer Science and Information Engineering Asia University Taichung Taiwan

Automatic plant identification via computer vision techniques has been greatly important for a number of professionals, such as environmental protectors, land managers, and foresters. In this paper, we conduct a comparative study on leaf image recognition and propose a novel learning-based leaf image recognition technique via sparse representation (or sparse coding) for automatic plant identification. In our learning-based method, in order to model leaf images, we learn an overcomplete dictionary for sparsely representing the training images of each leaf species. Each dictionary is learned using a set of descriptors extracted from the training images in such a way that each descriptor is represented by linear combination of a small number of dictionary atoms. Moreover, we also implement a general bag-of-words (BoW) model-based recognition system for leaf images, used for comparison. We experimentally compare the two approaches and show unique characteristics of our sparse coding-based framework. As a result, efficient leaf recognition can be achieved on public leaf image dataset based on the two evaluated methods, where the proposed sparse coding-based framework can perform better.

关键词： Image recognition Dictionaries Training Feature extraction Shape Vectors Image coding

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