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Chemistry at Polyimide-Metal Interfaces: In Situ FTIR Studies of Polymer Curing Processes and Thermal Stability

MRS Online Proceedings Library (OPL) 2011年第1期282卷 581-581页

作者： Jiong-Ping Lu David Volfson Fred Trusell Klavs F. Jensen Electronics Packaging Program and Departments of Chemical Engineeringand Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA 02139

We report in-situ Fourier transform infrared (FTIR) reflection-absorption studies of curing chemistry of polyimide thin films on Crand Cu surfaces, and of the thermal stability of the resulting thin film interfaces when exposed to air at elevated temperatures. The polyimide investigated is based on 4,4'-(hexafluoroisopropylidene)bis(phthalicanhydride)-4,4'-bis(4-aminophenoxy)-biphenyl. The imidization process takes place at temperatures higher than 90°C anda small amount of anhydride is generated during curing. This by-product is converted to imide at temperatures above 250°C. Complete imidization is achieved after curing at 300°C on Cr substrates, while evidence for incomplete curing on Cu is observed under the same conditions. Thermal stability studies with Cr and Cu substrates show that thermal decomposition of thin (∼1000Å) polyimide filmsoccurs on Cu when the film is exposed to air at 200°C, while the polyimide is stable on Cr.

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A parallel Ray Tracing architecture suitable for application-specific hardware and GPGPU implementations

A parallel Ray Tracing architecture suitable for application...

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2011 14th Euromicro Conference on Digital System Design: Architectures, Methods and Tools, DSD 2011

作者： Nery, Alexandre S. Nedjah, Nadia Franca, Felipe M.G. Jozwiak, Lech LAM - Computer Architecture and Microelectronics Laboratory Systems Engineering and Computer Science Program COPPE Universidade Federal Rio de Janeiro Brazil Department of Electronics Engineering and Telecommunications Faculty of Engineering Universidade do Estado Rio de Janeiro Brazil Department of Electrical Engineering - Electronic Systems Eindhoven University of Technology Netherlands

ISBN: (纸本)9780769544946

The Ray Tracing rendering algorithm can produce high-fidelity images of 3-D scenes, including shadow effects, as well as reflections and transparencies. This is currently done at a processing speed of at most 30 frames per second. Therefore, actual implementations of the algorithm are not yet suitable for interactive real-time rendering, which is required in games and virtual reality based applications. Fortunately, the algorithm allows for massive parallelization of its computations. In this paper, we present a parallel architecture for ray tracing based on a uniform spatial subdivision of the scene and exploiting an embedded computation of ray-triangle intersections. This approach allows for a significant acceleration of intersection computations, as well as, a reduction of the total number of the required intersections checks. Furthermore, it allows for these checks to be performed in parallel and in advance for each ray. In this paper we discuss and analyze an ASIP-based implementation using FPGAs and a GPGPU-based parallel implementation of the proposed architecture. The performance of both implementations are reported and compared." © 2011 IEEE.

关键词： Ray tracing

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Adaptive rate transmission for spectrum sharing system with quantized channel state information

Adaptive rate transmission for spectrum sharing system with ...

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Annual Conference on Information Sciences and Systems (CISS)

作者： Mohamed Abdallah Ahmed Salem Mohamed-Slim Alouini Khalid A. Qaraqe Electrical and Computer Engineering Texas A and M University Qatar Doha Qatar Department of Electronics and Electrical Communication Cairo University Cairo Egypt Electrical Engineering Program KAUST Thuwal Saudi Arabia

The capacity of a secondary link in spectrum sharing systems has been recently investigated in fading environments. In particular, the secondary transmitter is allowed to adapt its power and rate to maximize its capacity subject to the constraint of maximum interference level allowed at the primary receiver. In most of the literature, it was assumed that estimates of the channel state information (CSI) of the secondary link and the interference level are made available at the secondary transmitter via an infinite-resolution feedback links between the secondary/primary receivers and the secondary transmitter. However, the assumption of having infinite resolution feedback links is not always practical as it requires an excessive amount of bandwidth. In this paper we develop a framework for optimizing the performance of the secondary link in terms of the average spectral efficiency assuming quantized CSI available at the secondary transmitter. We develop a computationally efficient algorithm for optimally quantizing the CSI and finding the optimal power and rate employed at the cognitive transmitter for each quantized CSI level so as to maximize the average spectral efficiency. Our results give the number of bits required to represent the CSI sufficient to achieve almost the maximum average spectral efficiency attained using full knowledge of the CSI for Rayleigh fading channels.

关键词： Interference channels Transmitters Receivers Fading Signal to noise ratio Interference constraints

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Efficient scheduling request algorithm for opportunistic wireless access

Efficient scheduling request algorithm for opportunistic wir...

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IEEE MTT-S International Microwave Workshop Series on Intelligent Radio for Future Personal Terminals

作者： Haewoon Nam Mohamed-Slim Alouini Department of Electronics and Communication Engineering Hanyang University Ansan Korea Electrical Engineering Program KAUST Thuwal Makkah Province Saudi Arabia

An efficient scheduling request algorithm for opportunistic wireless access based on user grouping is proposed in this paper. Similar to the well-known opportunistic splitting algorithm, the proposed algorithm initially adjusts (or lowers) the threshold during a guard period if no user sends a scheduling request. However, if multiple users make requests simultaneously and therefore a collision occurs, the proposed algorithm no longer updates the threshold but narrows down the user search space by splitting the users into multiple groups iteratively, whereas the opportunistic splitting algorithm keeps adjusting the threshold until a single user is found. Since the threshold is only updated when no user sends a request, it is shown that the proposed algorithm significantly alleviates the burden of the signaling for the threshold distribution to the users by the scheduler. More importantly, the proposed algorithm requires a less number of mini-slots to make a user selection given a certain scheduling outage probability.

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An electronically controlled current-mode triangular/square wave generator employing MO-CCCCTAs

An electronically controlled current-mode triangular/square ...

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International Conference on electrical engineering/electronics, Computer, Telecommunications and Information Technology

作者： Srisakul, T. Silapan, P. Siripruchyanun, M. Department of Electronics Phitsanulok Technical College Muang Phitsanulok 65000 Thailand Electrical and Industrial Program Faculty of Industrial Uttaradit Rajabhat University Muang Uttaradit 53000 Thailand Department of Teacher Training in Electrical Engineering Faculty of Technical Education King Mongkut's University of Technology North Bangkok Bangkok 10800 Thailand

ISBN: (纸本)9781457704246

A new current-mode triangular/square wave generator based on MO-CCCCTAs (Multiple output current controlled current conveyor transconductance amplifiers) is presented in this paper. The circuit description is very simple, its construction consists of 2 MO-CCCCTAs and 1 grounded capacitor without any external resistor. The output frequency and amplitude can be electronically/independently tuned via corresponding input bias currents. With mentioned features, it is very suitable to realize in a monolithic chip. The PSpice simulation results are depicted, and agree well with the theoretical anticipation. The maximum power consumption is approximately 1.62mW at ±1.5V power supply. © 2011 IEEE.

关键词： Square wave generators

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Hardware reuse in modern application-specific processors and accelerators

Hardware reuse in modern application-specific processors and...

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2011 14th Euromicro Conference on Digital System Design: Architectures, Methods and Tools, DSD 2011

作者： Nery, Alexandre S. Jozwiak, Lech Lindwer, Menno Cocco, Mauro Nedjah, Nadia França, Felipe M.G. LAM - Computer Architecture and Microelectronics Laboratory Systems Engineering and Computer Science Program COPPE Universidade Federal do Rio de Janeiro Brazil Department of Electronics Engineering and Telecommunications Faculty of Engineering Universidade do Estado do Rio de Janeiro Brazil Department of Electrical Engineering - Electronic Systems Eindhoven University of Technology Netherlands Silicon Hive - Intel UMG Netherlands

ISBN: (纸本)9780769544946

Effective exploitation of the application-specific parallel patterns and computation operations through their direct implementation in hardware is the base for construction of high-quality application-specific (re-) configurable application specific instruction set processors (ASIPs) and hardware accelerators for modern highly-demanding applications. Although it receives a lot of attention from the researchers and practitioners, a very important problem of hardware reuse in ASIP and accelerator synthesis is clearly underestimated and does not get enough attention in the published research. This paper is an effect of an industry and academic collaborative research. It analyses the problem of hardware sharing, shows its high practical relevance, as well as a big influence of hardware sharing on the major circuit and system parameters, and its importance for the multi-objective optimization and tradeoff exploitation. It also demonstrates that the state-of-the-art synthesis tools do not sufficiently address this problem and gives several guidelines related to enhancement of the hardware reuse. © 2011 IEEE.

关键词： Multiobjective optimization

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Electrophoretic deposition of high quality transparent conductive graphene films on insulating glass substrates

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Journal of Physics: Conference Series 2012年第1期352卷

作者： R Ishikawa P J Ko Y Kurokawa M Konagai A Sandhu Department of Electrical and Electronic Engineering Tokyo Institute of Technology G-COE Program on Evolving Education and Research Center for Spatio-Temporal Biological Network Tokyo Institute of Technology Department of Physical Electronics Tokyo Institute of Technology Photovoltaics Research Center (PVREC) Tokyo Institute of Technology Electronics-Inspired Interdisciplinary Research Institute (EIIRIS) Toyohashi University of Technology

Graphene is a promising material for transparent conductive films (TCFs) because of its high electrical conductivity and excellent optical transparency over a wide spectral range. We have previously reported on an inexpensive means of producing graphene-based TCFs using chemically derived graphene flakes. However, the deposition of chemically derived graphene can yield poor stacking of graphene flakes, which degrades the electrical conductivity of the resulting films. Here, we describe an alternative approach for producing large areas of TCFs based on electrophoretic deposition of graphene onto glass substrates using charged graphene oxide flakes. This method enabled the deposition of highly stacked graphene films onto insulating glass substrates with potential for TCFs.

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A Replicator Dynamics Weighted Control Technique for Two Coupled Pendulums

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IFAC Proceedings Volumes 2011年第1期44卷 12662-12667页

作者： Alejandro Betancur Eduardo Mojica-Nava Nicanor Quijano Department of Electrical and Electronics Engineering Universidad de Los Andes Carrera 1 Este No 19A – 40 Bogotá Colombia Electronics and Telecommunications Engineering Program Universidad Católica de Colombia Diagonal 47 No 15-50 Bogotá Colombia

Abstract By combining different control methods, we can obtain a desired performance in a control system. In this work, we introduce a novel technique that uses a controller that is based on an energy system for the inverted pendulum, combined dynamically with an optimal controller. The dynamic combination of these two controllers is based on a population dynamics approach, which gives more weight to the controller that is designed to perform better in a given region. The controller is tested on a classical experiment used to illustrate decentralized controllers: the two inverted pendulums coupled by a spring (TPCS) system. Some simulations comparing our novel technique and the one that has been used are shown.

关键词： Replicator Dynamics LQR

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An optical-coding method for scattering signal detection in microfluidic cytometers

An optical-coding method for scattering signal detection in ...

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15th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2011, MicroTAS 2011

作者： Wu, T.-F. Mei, Z. Pion-Tonachini, L. Zhao, C. Qiao, W. Arianpour, A. Lo, Y.-H. Materials Science and Engineering Program University of California at San Diego San Diego CA 92093-0418 United States Department of Electrical and Computer Engineering University of California at San Diego San Diego CA 92093-0407 United States School of Information and Electronics Beijing Institute of Technology Beijing 100081 China

ISBN: (纸本)9781618395955

In this article, we demonstrated an optical-coding method to detect forward scattering and large angle scattering signals within microfluidic devices. Using silicon photodetectors, we can effectively discriminate the mixture of unlabelled beads and obtain the spatial distribution of beads. The optical coding method improves the signal-to-noise and particle differentiation abilities for lab-on-a-chip flow cytometers. Copyright © (2011) by the Chemical and Biological Microsystems Society.

关键词： Microfluidics

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Memristor-based synaptic networks and logical operations using in-situ computing

Memristor-based synaptic networks and logical operations usi...

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Intelligent Sensors, Sensor Networks and Information Processing Conference (ISSNIP)

作者： Omid Kavehei Said Al-Sarawi Kyoung-Rok Cho Nicolangelo Iannella Sung-Jin Kim Kamran Eshraghian Derek Abbott School of Electrical & Electronic Engineering The University of Adelaide SA Australia College of Electronics & Information Engineering (WCU Program) Chungbuk National University South Korea

We present new computational building blocks based on memristive devices. These blocks, can be used to implement either supervised or unsupervised learning modules. This is achieved using a crosspoint architecture which is an efficient array implementation for nanoscale two-terminal mem-ristive devices. Based on these blocks and an experimentally verified SPICE macromodel for the memristor, we demonstrate that firstly, the Spike-Timing-Dependent Plasticity (STDP) can be implemented by a single memristor device and secondly, a memristor-based competitive Hebbian learning through STDP using a 1×1000 synaptic network. This is achieved by adjusting the memristor's conductance values (weights) as a function of the timing difference between presynaptic and postsynaptic spikes. These implementations have a number of shortcomings due to the memristor's characteristics such as memory decay, highly nonlinear switching behaviour as a function of applied voltage/current, and functional uniformity. These shortcomings can be addressed by utilising a mixed gates that can be used in conjunction with the analogue behaviour for biomimetic computation. The digital implementations in this paper use in-situ computational capability of the memristor.

关键词： Memristors Switches Arrays Resistance Logic gates Hebbian theory programmable logic arrays

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