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Experimental study of multiphase flow in a model gearbox

Experimental study of multiphase flow in a model gearbox

6th International conference on Computational and Experimental Methods in Multiphase and Complex Flow -Multiphase Flow 2011, MPF11

作者： Chernoray, v. Jahanmiri, M. Division of Fluid Dynamics Department of Applied Mechanics Chalmers University of Technology Göteborg Sweden Department of Mechanical and Aerospace Engineering Shiraz University of Technology Iran

ISBN: (纸本)9781845645182

This study concerns dynamics of a two-phase flow around a rotating solid body. Under consideration is a model of a gear wheel in a gearbox which rotates and is partially submerged in oil. The flow of interest is complex and involves effects of free surface dynamics, rotation, and formation of bubbles and drops. Occurring flow regimes include laminar, transitional and turbulent. The major focus of the investigation is on details of the developed flow, and the purpose is validation of numerical methods developed for design and optimization of such components. current experiments are performed in a test rig which is modelling a generic simplified gearbox with a single isolated rotating wheel. The flow measurements are carried out by using particle image velocimetry (PIv) and the test rig is specially designed for this purpose with the optical access maximized. The flow similarity with respect to a real gearbox is fully maintained and the working fluid is a transparent mineral oil. The PIv measurements are performed at four different rotation speeds for two different wheel configurations in order to cover a spectrum of operational conditions needed for numerical modelling. The emphasis is on the result of experiments on a smooth wheel. The measurements are providing velocity distribution around the wheel and details on bubble and drop distribution. © 2011 WIT Press.

关键词： Wheels

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Generating ultra-short high-energy pulses using dissipative soliton resonance: Pulse compression schemes

Generating ultra-short high-energy pulses using dissipative ...

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conference on Lasers and Electro-Optics Europe

作者： Chang, Wonkeun Grelu, Philippe Ankiewicz, Adrian Soto-Crespo, Jose M. Akhmediev, Nail Optical Sciences Group Research School of Physics and Engineering Australian National University Canberra ACT 0200 Australia Max Planck Institute for the Science of Light Guenther-Scharowsky-Strasse I 91058 Erlangen Germany Labarotoire Interdisciplinaire Carnot de Bourgogne UMR 5209 CNRS Université de Bourgogne 9 Avenue A. Savary Dijon Cedex 21078 France Instituto de Ptica CSIC Serrano 121 Madrid 28006 Spain

ISBN: (纸本)9781457705335

Dissipative soliton resonance (DSR) refers to a phenomenon where the energy of the stable soliton solution increases to extremely large values in a nonlinear dissipative system modeled by the complex cubic-quintic Ginzburg-Landau equation (CGLE) [1]. It occurs in the vicinity of a specific hyper-surface in the multi-dimensional space of the CGLE parameters. The phenomenon has applications in designing laser oscillators generating ultra-high energy pulses, since the dynamics of such lasers can be well-modeled by the CGLE. The DSR was first found in normally-dispersive media, in concordance with the current design trend for high-energy mode-locked laser oscillators [2-4]. However, we have shown recently that they also exist in anomalous media, opening the possibility of generating ultra-high energy pulses with anomalous path-averaged cavity dispersion [5, 6]. © 2011 IEEE.

关键词： Nonlinear equations

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design of a multiplexer to characterize individual optics at a concentrating photovoltaic test site

Design of a multiplexer to characterize individual optics at...

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conference on Photonics North

作者： Wilkins, Matthew Beal, Richard Haysom, Joan E. Wheeldon, Jeffrey F. Mulet, Philippe Jamieson, Graeme Youssef, Nashed Balachandreswaran, Dhan Fan, Jennifer Hall, Trevor Myrskog, Stefan Hinzer, Karin Univ Ottawa Ctr Res Photon Ottawa ON K1N 6N5 Canada Morgan Solar Inc Ottawa ON Canada

ISBN: (纸本)9780819485816

An on-sun Concentrating Photovoltaic (CPv) test site with a multiplexed current-voltage measurement capability has been installed at the University of Ottawa. Herein, we present details of the instrumentation, which is designed to provide in-situ I-v measurements of individual solar cells within a functioning, series connected, string. A 4-wire multiplexing system enables current-voltage measurements of individual cells. Where other multi-cell test systems have left cells at open-circuit or connected to a fixed resistor when not selected by the multiplexer, in this system each test cell operates within a string of cells controlled by a maximum power point tracker. This allows us to maintain the test cells at realistic operating conditions for all irradiance conditions. Using the current-voltage data, a range of parameters of interest can be monitored over time, including the solar cell temperature, photovoltaic efficiency and optical efficiency. This information is correlated with time-synchronized spectrometer and pyrheliometer data, allowing automated collection of performance data from several strings of optic/solar cell assemblies. The test site includes two 20m(2), dual-axis, ring mounted solar trackers and is being used to test new CPv systems which incorporate novel light-guiding optics designed and manufactured by Morgan Solar Inc.

关键词： photovoltaic multiplexer on-sun characterization CPv cell temperature

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Automatic contactless mobile fingerprinting system

Automatic contactless mobile fingerprinting system

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作者： Baier, M. Foret, S. Oliyil, v. Kunnil Paradis, M. Bustos, P. Mil'shtein, S. Advanced Electronic Technology Center Department of Electrical and Computer Engineering University of Massachusetts Lowell MA 01854 United States

ISBN: (纸本)9789898425485

Increased security requirements relevant to the worldwide war against terrorism and cyber crime recently prompted the development of biometric systems for use in identifying individuals at commercial facilities, border crossings, airports, and government building access points. Fingerprinting is one of the oldest means of biometric identification;however, the current methods of fingerprint capture carry inherent limitations on image quality. The current study describes the development of a novel, mobile, and contactless fingerprinting system. This system combines the advantages of contactless fingerprinting with the ability to create a digital map of the blood vessels within a finger for use as a second data set for use in biometric identification. The distinguishing feature of the system is the use of line scanning technology which allows for the acquisition of nearly distortion-less 180° or "nail-to-nail" fingerprints. The study describes a fully automatic system and assesses the technical aspects of this novel device. We describe the design of the subsystems: adaptive lighting, optical image formation, power management methods, wireless data transfer, and subsystem synchronization techniques. We will also discuss the system's embedded software, which synchronizes the operation of all subsystems and allows for fingerprint visualization on an onboard touch screen display.

关键词： Adaptive optics

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CMOS integrated avalanche photodiodes and frequency-mixing optical sensor front end for portable NIR spectroscopy instruments

CMOS integrated avalanche photodiodes and frequency-mixing o...

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Annual International conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Ruida Yun Chirag Sthalekar valencia M. Joyner Department of Electrical and Computer Engineering Tufts University Medford MA USA

This paper presents the design and measurement results of two avalanche photodiode structures (APDs) and a novel frequency-mixing transimpedance amplifier (TIA), which are key building blocks towards a monolithically integrated optical sensor front end for near-infrared (NIR) spectroscopy applications. Two different APD structures are fabricated in an unmodified 0.18 \im CMOS process, one with a shallow trench isolation (STI) guard ring and the other with a P-well guard ring. The APDs are characterized in linear mode. The STI bounded APD demonstrates better performance and exhibits 3.78 A/W responsivity at a wavelength of 690 nm and bias voltage of 10.55 v. The frequency-mixing TIA (FM-TIA) employs a T-feedback network incorporating gate-controlled transistors for resistance modulation, enabling the simultaneous down-conversion and amplification of the high frequency modulated photodiode (PD) current. The TIA achieves 92dSΩ conversion gain with 0.5 v modulating voltage. The measured IIP 3 is 10.6/M. The amplifier together with the 50 Ω output buffer draws 23mA from a1.8v power supply.

关键词： CMOS integrated circuits current measurement voltage measurement Gain optical sensors Frequency modulation Breakdown voltage

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System-Software Co-engineering: Dependability and Safety Perspective

System-Software Co-Engineering: Dependability and Safety Per...

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IEEE International conference on Space Mission Challenges for Information Technology, SMC-IT

作者： Y. Yushtein M. Bozzano A. Cimatti J.-P. Katoen v.Y. Nguyen Th. Noll X. Olive M. Roveri Systems Software & Technology Department European Space Agency Noordwijk Netherlands Embedded Systems Research Unit Fondazione Bruno Kessler (FBK) Trento Italy Software Modeling and Verification Group RWTH Aachen University Denmark Research Department Thales Alenia Space Cannes-La-Bocca France

The need for an integrated system-software co-engineering framework to support the design of modern space systems is pressing. The current tools and formalisms tend to be tailored to specific analysis techniques and are not amenable for the full spectrum of required system aspects such as safety, dependability and performability. Additionally, they cannot handle the intertwining of hardware and software interaction. As such, the current practices lack integration and coherence. We recently developed a coherent and multidisciplinary approach towards developing space systems at architectural design level, linking all of the aforementioned aspects, and assessed it with several industrial evaluations. This paper reports on the approach, the evaluations and our perspective on current and future developments.

关键词： Software Safety Analytical models Hardware Compass Heating Fault trees

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validation of a Device for Fluorescence Sensing of Rare Circulating Cells with Diffusive Light in an optical Flow Phantom Model

Validation of a Device for Fluorescence Sensing of Rare Circ...

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

作者： Eric Zettergren Dwayne vickers Judith Runnels Charles P. Lin Mark J. Niedre Department of Electrical and Computer Engineering Northeastern University Department of Chemical Engineering Northeastern University Advanced Microscopy Program Center for Systems Biology and Wellman Center for Photomedicine Massachusetts General Hospital

ISBN: (纸本)9781424441211

Detection and quantification of rare circulating cells in biological tissues is an important problem and has many applications in biomedical research. current methods normally involve extraction of blood samples and counting of cells ex vivo, or the use of microscopy-based fluorescence in vivo flow cytometry. The goal of this work is to develop an instrument for non-invasively enumerating very rare circulating cells in small animals with diffuse light with several orders of magnitude sensitivity improvement versus current approaches. In this work, we describe the design of our system and show that single, fluorescent microspheres can be detected in limb-mimicking optical flow phantoms with varying optical properties chosen to simulate in vivo conditions. Further, we demonstrate single cell counting capabilities using fluorescently (vybrant-DiD) labeled Jurkat and Multiple Myeloma cells. Ongoing work includes in vivo testing and characterization of our system in mice.

关键词： Imaging Phantom Optic Flow Cell Count diffuse light in vivo test optical properties TISSUES (BIOLOGY) EX-vIvO Fluorescence Myeloma cell blood specimen

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Stability region adaptation using transmission power control for transport capacity optimization in IEEE 802.16 wireless mesh networks

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COMPUTER NETWORKS 2011年第16期55卷 3694-3704页

作者： vejarano, G. Wang, D. McNair, J. Wireless and Mobile Systems Laboratory Department of Electrical and Computer Engineering University of Florida United States

Transmission power control in multihop wireless networks is a challenging problem due to the effects that different node transmission powers have across the layers of the protocol stack. In this paper, we study the problem of transmission power control in IEEE 802.16 mesh networks with distributed scheduling. We consider the effects of transmission power control on the link-scheduling performance when a set of end-to-end flows established in the network are given. The problem is approached by means of the stability region of the link-scheduling policy. Specifically, the stability region is adapted using transmission-power control to the paths of the flows. This adaptation enables the flows to support higher levels of data traffic under lower levels of end-to-end delay. To the best of our knowledge, the approach of stability-region-based transmission power control has not been studied before. We propose a heuristic transmission-power-control algorithm for solving the problem of adapting the stability region to the flows. It is shown, by means of simulation, that the algorithm outperforms the transmission power control based on spatial reuse, which is a widely used approach. Also, it is shown that the solution of the algorithm has performance close to the optimal solution for moderate-sized networks, i.e., networks with no more than 25 nodes and 25 flows. (C) 2011 Elsevier B.v. All rights reserved.

关键词： Power control Transport capacity Throughput maximization Stability region Wimax

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A CMOS equalizer for short-reach optical communications

A CMOS equalizer for short-reach optical communications

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Ph.D. Research in Microelectronics and Electronics (PRIME)

作者： C. Gimeno C. Aldea S. Celma Electronic Design Group (GDE) Aragón Institute of Engineering Research (I3A) University of Zaragoza Zaragoza Spain

This paper presents a new CMOS analog equalizer for short-reach optical communications with tuning range between 300 MHz and 3.6 GHz. The prototype has been designed in a standard 0.18 μm CMOS process. This equalizer uses a current-mode process to decrease the supply voltage and the power consumption. Thus, it operates with a supply voltage of 1 v and has a power consumption of 1.1 mW.

关键词： optical fibers CMOS integrated circuits Bandwidth Adaptive equalizers optical fiber communication Solid state circuits

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A monolithic 3.125 Gbps fiber optic receiver front-end for POF applications in 65 nm CMOS

A monolithic 3.125 Gbps fiber optic receiver front-end for P...

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Custom Integrated Circuits conference (CICC)

作者： Yunzhi Dong Ken Martin Department of Electrical and Computer Engineering University of Toronto Toronto ONT Canada

This paper describes the design of an analog receiver front-end targeting multi-gigabit data communications over large-core plastic optical fibers. A receiver front-end with an integrated photo detector has been implemented in a standard TSMC 65 nm low-power bulk-silicon CMOS process. A novel hybrid current buffer based transimpedance amplifier has been proposed to drive the 14 pF photo capacitance presented by the large-area photo detector to multi-gigahertz range. A digitally controlled slow-slope equalizer has also been integrated in the receiver front-end to compensate the high-frequency losses due to the integrated photo detector. The receiver front-end consumes 50 mW dc power from a 1.2 v supply (excluding output buffer) and achieves an NRZ data rate up to 3.125 Gbps.

关键词： CMOS integrated circuits optical fibers optical receivers Equalizers Detectors Gain

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