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IEEE Aerospace Conference

作者： Aakarsh Rao Minsik Hong Akash Shankaran Wolfgang Fink Jerzy Rozenblit Model Based Design Laboratory Department of Electrical & Computer Engineering University of Arizona Visual and Autonomous Exploration Systems Research Laboratory Systems Departments of Electrical & Computer Engineering Biomedical Engineering Systems & Industrial Engineering Aerospace & Mechanical Engineering Ophthalmology & Vision Science Universi Department of Surgery University of Arizona

ISBN: (纸本)9781479916191

Medical surgeries in the space environment, including long term space travel (e.g., to Mars) and permanent presence on other planetary bodies (e.g., Moon and Mars), are posing an inherent logistical, and in the absence of appropriately trained personnel (i.e., surgeons), even a potentially life-threatening challenge. As a potential mitigation the use of an existing surgical trainer tool that would allow crewmembers to acquire basic surgical skills is proposed, and to train space station personnel both in space and on the Moon and Mars to hone these skills long-term. Furthermore, this tool would potentially allow for tele-conducted surgeries, akin to the da Vinci Surgical System, controlled from Earth but executed onboard, e.g., the International Space Station. On Earth the surgical trainer can be used to train surgeons and flight surgeons. The efficiency of any surgical training system plays a significant role in its reduction of operative risks and stress associated with insufficient experience of the trainee. The primary goal of such systems is to raise the trainee to a higher level of proficiency without putting patients at risk in the operating room. The prototype for the computer Assisted Surgical Trainer (CAST) being developed at the University of Arizona realizes an optimal motion-planning algorithm. The underlying system consists of mechanical fixtures equipped with encoders and DC motors. This hardware provides a means to accurately track the tip movements of laparoscopic instruments used in minimally invasive surgery. Furthermore it provides haptic and visual feedback to trainees by using a PID controller and augmented reality visualization. Examples of surgical guidance and the improvement of surgeon performance over time using CAST are presented.

关键词： Surgery Instruments Training Visualization Haptic interfaces Space stations Aerospace electronics

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Ultraviolet Photodetector Fabricated from 3D WO3 Nanowires/Reduced Graphene Oxide Composite Material

Ultraviolet Photodetector Fabricated from 3D WO3 Nanowires/R...

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2013 MRS Fall Meeting

作者： Shao, Dali Yu, Mingpeng Lian, Jie Sawyer, Shayla Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy NY 12180 United States Department of Mechanical Aerospace and Nuclear Engineering Rensselaer Polytechnic Institute Troy NY 12180 United States Department of Chemistry Laboratory of Bio-organic Phosphorus Tsinghua University Beijing 100084 China

An Ultraviolet (UV) photodetector with high responsivity and relative fast response speed was fabricated from three dimensional WO3 nanowires/reduced graphene oxide (3D WO3 NWs/RGO) composite materials. The 3D WO3 NDs/GN composite was synthesized using a facile three-step synthesis. First, the Na2WO4/Graphene Oxide (GO) precursor was synthesized by homogeneous precipitation. Second, the Na2WO4/GO precursor was transformed into H2WO4/GO composites by acidification. Finally, the H2WO4/GO composites were reduced to 3D WO3 NWs/RGO via hydrothermal reduction process. A maximum photoresponsivity of 4.2 A/W at 374 nm was observed under 20 V bias. The UV photodetector showed relative fast transient response, which is at least 2 orders of magnitude faster than UV photodetectors fabricated from WO3 nanowires. The good photoresponsivity and fast transient response are attributed to improved carrier transport and collection efficiency through graphene. Copyright © 2014 Materials Research Society.

关键词： Composite materials

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Measuring phase derivatives in digital holographic interferometry

Measuring phase derivatives in digital holographic interfero...

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Digital Holography and Three-Dimensional Imaging, DH 2014

作者： Rajshekhar, Gannavarpu Rastogi, Pramod Quantitative Light Imaging Laboratory Department of Electrical and Computer Engineering Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign Urbana-61801 IL United States Applied Computing and Mechanics Laboratory Ecole Polytechnique Fédérale de Lausanne 1015 Lausanne Switzerland

We discuss pseudo Wigner-Ville distribution based phase derivative estimation techniques in digital holographic interferometry. These techniques address the major challenges associated with measuring phase derivatives... 详细信息

ISBN: (纸本)9781557523082

关键词： Wigner-Ville distribution

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3D printed parts for cubesats;experiences from KySat-2 and printsat using Windform XT 2.0 2nd

3D printed parts for cubesats;experiences from KySat-2 and p...

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2nd International Academy of Astronautics Conference on Dynamics and Control of Space systems, DyCoSS 2014

作者： Clements, Twyman Moore, Gil Clements, Alex Davis, Stewart White, Jim Wilt, David Holemans, Walter Rexroat, Jason Fite, Nathan Klumpar, Dave Malphrus, Benjamin Lumpp, James Kentucky Space LLC 200 W Vine St. LexingtonKY40507 United States Project PrintSat 3955 Sierra Vista Rd MonumentCO80132 United States Helios Aerosystems 163 E. Main St LexingtonKY40502 United States CRP USA LLC 119 Poplar Pointe Drive Unit A MooresvilleNC28117 United States Colorado Satellite Services LLC 45777 Rampart Rd ParkerCO80138 United States Air Force Research Laboratory AlbuquerqueNM United States Planetary Systems Corporation 2303 Kansas Ave Silver SpringMD20910 United States University of Kentucky LexingtonKY United States Space Science and Engineering Laboratory Montana State University BozemanMT59717 United States Department of Earth and Space Sciences Morehead State University MoreheadKY United States Department Electrical and Computer Engineering University of Kentucky LexingtonKY United States

ISBN: (纸本)9780877036173

The recent predominance of consumer level 3D printers has brought much attention towards the additive manufacturing process. On November 19th 2013 29 small satellites were launched from NASA's Wallops Flight Facility including KySat-2, a 1U CubeSat. KySat-2 was built with 10 additively manufactured, also called 3D printed, parts made from Windform XT 2.0, a material whose previous uses were mainly for automotive racing. Another 1U CubeSat, PrintSat, will be launched in 2014 and whose entire structure is built from the same material. This paper will discuss how each satellite used 3D printing, an overview of Windform XT 2.0, pros, cons and design considerations of 3D printing, and its future potential uses in the design and construction of spacecraft.

关键词： 3D printers

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Reactive Power Control of DFIG Wind Farm Using Online Supplementary Learning Controller Based on Approximate Dynamic Programming

Reactive Power Control of DFIG Wind Farm Using Online Supple...

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International Joint Conference on Neural Networks

作者： Wentao Guo Feng Liu Dawei He Jennie Si Ronald Harley Shengwei Mei State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University School of Electrical and Computer Engineering Georgia Institute of Technology Department of Electrical Engineering Arizona State University

ISBN: (纸本)9781479914821

Dynamic reactive power control of doubly fed induction generators (DFIGs) plays a crucially important role in maintaining transient stability of power systems with high penetration of DFIG based wind generation. Based on approximate dynamic programming (ADP), this paper proposes an optimal adaptive supplementary reactive power controller for DFIGs. By augmenting a corrective regulation signal to the reactive power command of rotor-side converter (RSC) of a DFIG, the supplementary controller is designed to reduce voltage sag at the point of common connection (PCC) during a fault, and to mitigate output active power oscillation of the wind farm after a fault. As a result, the transient stability of both DFIG and the power grid is enhanced. An action dependent cost function is introduced to provide real-time online ADP learning control. Furthermore, a policy iteration algorithm using high-efficiency least square method is employed to train the supplementary controller in an online model-free manner. By using such techniques, the supplementary reactive power controller is endowed with capability of online optimization and adaptation. Simulations carried out on a benchmark power system integrating a large DFIG wind farm show that the ADP based supplementary reactive power controller can significantly improve the transient system stability in changing operation conditions.

关键词： Reactive power Wind farms Reactive power control Cost function Rotors Training Voltage control

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A Frequency-Sensing Readout using Piezoelectric Sensors for Sensing of Physiological Signals

A Frequency-Sensing Readout using Piezoelectric Sensors for ...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society

作者： Dilpreet Buxi Jean-Michel Redoute Mehmet Rasit Yuce Biomedical Integrated Circuits and Sensors (BICS) Laboratory at the Department of Electrical and Computer Systems Engineering Monash University

ISBN: (纸本)9781424479276

Together with a charge or voltage amplifier, piezoelectric sensors are commonly used to pick up physiological vibrations from the body. As an alternative to chopper or auto-zero amplifiers, frequency sensing is known in literature to provide advantages of noise immunity, interfacing to digital readout systems as well as tunable range of sensing. A frequency-sensing readout circuit for sensing low voltage signals from piezoelectric sensors is successfully developed and tested in this work. The output voltage of a piezoelectric sensor is fed to a varactor, which is part of an Colpitts LC oscillator. The oscillation frequency is converted into a voltage using a phase locked loop. The circuit is compared to a reference design in terms of linearity, noise and transfer function. The readout has a input-referred noise voltage of 2.24μV/{the square root of}(Hz) and consumes 15 mA at 5V supply. Arterial pulse wave signals and the cardiac vibrations from the chest are measured from one subject to show the proof of concept of the proposed readout. The results of this work are intended to contribute towards alternative low noise analog front end designs for piezoelectric sensors.

关键词： Sensors Noise Phase locked loops Frequency modulation Voltage-controlled oscillators Electrocardiography

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Listen-and-Talk: Full-duplex Cognitive Radio Networks

Listen-and-Talk: Full-duplex Cognitive Radio Networks

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IEEE Global Communications Conference

作者： Yun Liao Tianyu Wang Lingyang Song Zhu Han State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electrical Engineering and Computer Science Peking University Electrical and Computer Engineering Department University of Houston

ISBN: (纸本)9781479935130

In traditional cognitive radio networks, secondary users (SUs) typically access the spectrum of primary users (PUs) by a two-stage "listen-before-talk" (LBT) protocol, i.e., SUs sense the spectrum holes in the first stage before transmit in the second stage. In this paper, we propose a novel "listen-and-talk" (LAT) protocol with the help of the full-duplex (FD) technique that allows SUs to simultaneously sense and access the vacant spectrum. Analysis of sensing performance and SU's throughput are given for the proposed LAT protocol. And we find that due to self-interference caused by FD, increasing transmitting power of SUs does not always benefit to SU's throughput, which implies the existence of a power-throughput tradeoff. Besides, though the LAT protocol suffers from self-interference, it allows longer transmission time, while the performance of the traditional LBT protocol is limited by channel spatial correction and relatively shorter transmission period. To this end, we also present an adaptive scheme to improve SUs' throughput by switching between the LAT and LBT protocols. Numerical results are provided to verify the proposed protocol and the theoretical results.

关键词： cognitive radio protocols radio networks radio spectrum management radiofrequency interference FD technique LAT protocol LBT protocol PUs SU throughput channel spatial correction full-duplex cognitive radio networks listen-and-talk protocol power-throughput tradeoff primary users secondary users self-interference sensing performance analysis spectrum holes two-stage listen-before-talk protocol vacant spectrum Correlation Protocols Sensors Signal to noise ratio Switches Throughput Transmitting antennas

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Independent component analysis: Embedded LTSA 7

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7th International Conference on Intelligent systems and Knowledge engineering, ISKE 2012 with 1st International Conference on Cognitive systems and Information Processing, CSIP 2012

作者： Yang, Qianwen Li, Yuan Sun, Fuchun Yang, Qingwen State Key Laboratory of Intelligence Technology and Systems Department of Computer Science and Technology Tsinghua University Beijing100084 China School of Information Engineering University of Science and Technology Beijing China School of Electrical and Information Engineering Beijing Jiao Tong University Beijing China

ISBN: (纸本)9783642378287

In order to solve the adaptability problem of local tangent space alignment (LTSA) with potential higher-order information loss in manifolds, a novel algorithm is proposed to optimize the extraction of local neighborhood information. The algorithm is based on LTSA and ICA algorithms, which is called the IELTSA algorithm. By optimizing the extraction of the tangent vectors, the algorithm can improve dimension reduction in high-dimensional and unevenly distributed manifolds. The proposed algorithm is feasible in carrying out manifold learning, and the reconstruction error is no more than that of LTSA. Experiments show that IELTSA can be applied to changed-density 3D curves and face images targeted at lower dimensions, showing highest performance over LTSA and other improved methods based on LTSA, and achieving the highest recognition rate in lower-dimensional embedding. The algorithm can effectively reconstruct low-dimensional coordination in curves with changed-density and also shows adaptability in high-dimensional images targeted at lower dimensions. © Springer-Verlag Berlin Heidelberg 2014.

关键词： Independent component analysis

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Enabling decentralised microblogging through P2PVPNs

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International Journal of Security and Networks 2013年第3期8卷 169-178页

作者： St Juste, Pierre Eom, Heungsik Woodruff, Benjamin Baker, Corey Figueiredo, Renato Advanced Computing and Information Systems Lab Wireless and Mobile Systems Laboratory Department of Electrical and Computer Engineering Florida United States

The need for user privacy in social networks has prompted the exploration of social networking designs which do not rely on the common centralised client-server model. Many peer-to-peer microblogging solutions have been proposed and/or implemented utilising various technologies such as DHTs, multicast trees, and/or gossip protocols. We propose a decentralised microblogging service that leverages available Peer-to-Peer Virtual Private Networking (P2PVPN) technologies. By leveraging the private IP connectivity of P2PVPNs, our design utilises both IP multicasting and data replication through high degree nodes to ensure that peers are able to publish messages with varying degree of scope. We study the implications of our data dissemination model for a decentralised microblogging service through simulation-based analysis using a 3-million user social graph from Orkut. We also developed a prototype implementation to demonstrate the feasibility of our design choices along with a small deployment on FutureGrid to test its performance on the internet. Copyright © 2013 Inderscience Enterprises Ltd.

关键词： Multicasting

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A Fast EMT Simulation Method for Control and Protection Studies of Microgrids

A Fast EMT Simulation Method for Control and Protection Stud...

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IEEE Power and Energy Society General Meeting

作者： Yin Xu Haixiang Gao Ying Chen Chen-Ching Liu School of Electrical Engineering and Computer Science Energy Systems Innovation Center Washington State University Department of Electrical Engineering State Key Laboratory of Power Systems Tsinghua University

ISBN: (纸本)9781479964161

In this work, ac-dc hybrid microgrids are studied, which contains inverter-interfaced distributed generators (DGs) and storages (DSs). As an effective way, electromagnetic transient (EMT) simulations are widely adopted for studies on control and protection strategies of these microgrids. However, detailed EMT simulations are time-consuming, especially for microgrids with many inverter-interfaced DGs/DSs. Based on model reduction, this paper proposes a fast EMT simulation method for microgrids. A piecewise averaged model (PAM) of inverter-interfaced DGs/DSs is established and integrated into the Electromagnetic Transient Program (EMTP). Using a microgrid with 2 PV generators and 1 battery energy storage system (BESS) as test system, the proposed method is verified by comparing simulation results with those obtained from a detailed model built in PSCAD/EMTDC. The results indicate that the proposed method can effectively speed up EMT simulation of microgrids with negligible lost in accuracy.

关键词： Microgrid Distributed energy resource (DER) Power electronics converter Averaged model Electromagnetic transient program (EMTP)

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