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Frontiers of Massively Parallel Computation

作者： S.A. Fineberg T.L. Casavant B.H. Pease Computer Science Corporation USA Parallel Processing Laboratory Department of Electrical and Computer Engineering University of Iowa Iowa IA USA

The communication latency problem is presented with special emphasis on RISC (reduced instruction set computer) based multiprocessors. An interprocessor communication model for parallel programs based on locality is presented. This model enables the programmer to manipulate locality at the language level and to take advantage of currently available system hardware to reduce latency. A hardware node architecture for a latency-tolerant RISC-based multiprocessor, called Seamless, that supports this model, is presented. The Seamless architecture includes the addition of a hardware locality manager to each processing element, as well as an integral runtime environment and compiler.< >

关键词： Hardware Delay Yarn Parallel processing Reduced instruction set computing Costs Coprocessors Communication system control Parallel architectures Synchronization

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A new robust approach to diffuse edge detection

A new robust approach to diffuse edge detection

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MILCOM, Military Communications Conference

作者： T.-H. Yu S.K. Mitra Department of Electrical and Computer Engineering Signal and Image Processing Laboratory University of California Santa Barbara CA USA

The authors outline an edge-prediction-adjustment strategy for the detection of diffused edges using an image pyramid structure. An initial edge map is obtained from an appropriate high-level image of the pyramid using a conventional edge detection method. Next, using a simple linear interpolation, the predicted edge map for the adjacent low-level image is determined. Based on the information of the predicted edges, edge adjustment is carried out using a sequential search in a small neighborhood of each of the predicted edges with the aid of a dynamic programming based method. Simulation results on both synthetic and medical images indicate that the performance of the proposed approach is much better than that of the commonly used differential of a Gaussian-based approach.< >

关键词： Robustness Image edge detection Band pass filters Smoothing methods Shape Interpolation Gradient methods Laplace equations Signal processing Image processing

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Optical Properties and Structure of Microcrystalline Silicon

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MRS Online Proceedings Library 1992年第1期258卷 235-240页

作者： Hien V. Nguyen Ilsin An Youming Li C.R. Wronski R.W. Collins Materials Research Laboratory The Pennsylvania State University University Park USA Department of Physics USA Department of Electrical and Computer Engineering and the Center for Electronic Materials and Processing USA

The optical properties of thin film microcrystalline silicon (μc-Si:H) prepared by plasma-enhanced chemical vapor deposition (PECVD) have been studied by real time spectroscopie ellipsometry in the nucleation regime as isolated crystalline particles increase in size. A simple geometric model of nucleation allows us to remove the dominant effect of voids and extract the dielectric functions of the crystallites themselves. We find that the results can be understood in terms of a classical size effect whereby limitations on the electron mean free path by scattering at crystallite surfaces control the absorption onset from 2.0 to 3.0 eV. Finally, we describe how well-ordered, continuous 15 Å c-Si films can be prepared on metal substrates.

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Design recovery for relay ladder logic

Design recovery for relay ladder logic

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IEEE Conference on Control Technology and Applications (CCTA)

作者： A. Falcione B.H. Krogh Department of Electrical and Computer Engineering Laboratory of Automatic Systems and Information Processing Carnegie Mellon University Pittsburgh PA USA

An algorithm for converting relay ladder logic (RLL) programs for programmable logic controllers (PLCs) into sequential function chart (SFC) programs is introduced. Since an SFC (a standardization of Grafcet) better represents the sequential flow of control logic, it is considerably easier to understand and modify SFC programs. Existing RLL programs are converted into SFC programs by recovering the underlying sequential control logic. This conversion of the program representation is referred to as design recovery. A basic design recovery algorithm is presented and applied to a simple RLL program for one stage of a batch chemical process. Several fundamental issues in discrete control logic representation and analysis are also identified as fertile areas for future research.< >

关键词： Relays Logic design Programmable control Logic programming Algorithm design and analysis computer languages Chemical processes Laboratories Information processing Automatic logic units

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Ultra-Shallow P+/N Junctions Formed by SiF4 Preamorphization and BF3 Implantation Using Plasma Immersion Ion Implantation

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MRS Online Proceedings Library 1992年第1期279卷 255-259页

作者： Erin C. Jones Seongil Im Nathan W. Cheung Plasma Assisted Materials Processing Laboratory Department of Electrical Engineering and Computer Sciences University of California Berkeley USA Department of Materials Science and Mineral Engineering University of California Berkeley USA

Sub-100 nm P+/N junctions are fabricated by implanting wafers in the plasma immersion ion implantation system (PIII). Ions from SiF4 and BF3 plasmas are implanted at energies from 4-6 keV and 2 keV, respectively. The amorphous region formed by SiF4 im-plantion is shown to be effective in slowing B diffusion during a 10 sec, 1060°C rapid thermal anneal step. Channeling and transmission electron microscopy studies show the recrys-tallized amorphous region is comparable in quality to an unprocessed Si wafer, and the implantation and annealing sequence has no detrimental effects on the physical or electrical characteristics of fabricated devices. Diodes have forward ideality factors of 1.05 to 1.06 and reverse leakage as low as 2 nA/cm2 in the diode bulk at -5 V applied bias.

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Proximity effect reduction in x‐ray mask making using thin silicon dioxide layers

Journal of Vacuum Science & Technology B: Microelectronics a...

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Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures processing, Measurement, and Phenomena 1992年第6期10卷 3062-3066页

作者： Kee W. Rhee David I Ma Martin C. Peckerar R. A. Ghanbari Henry I. Smith Nanoelectronics Processing Facility Naval Research Laboratory Washington DC 20375 Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139

A novel method is reported for reducing the proximity effect in high‐resolution electron beam patterning of high atomic number materials such as tungsten. The method involves interposing a thin (50–400 nm) layer of SiO2 between the resist and the underlying high‐Z substrate. Examples are shown in which gratings of 0.2 μm lines with a 0.5 μm period were written without proximity effect compensation. Optimal intermediate layer thickness for the best resolution of the gratings is determined to be 200 nm. A Monte Carlo model of electron scattering including inelastic processes has been implemented to interpret our experimental results. The model presented shows that having the low atomic number SiO2 layer between the resist and the tungsten prevents the fast secondary electrons being generated at the surface of the tungsten from propagating back into the resist, suggesting a mechanism for proximity effect reduction. The results presented here have important practical applications for x‐ray mask making.

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Limit cycles in floating-point implementations of recursive filters-a review

Limit cycles in floating-point implementations of recursive ...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： T.I. Laakso B. Zeng Laboratory of Signal Processing and Computer Technology Helsinki University of Technology Espoo Finland Department of Electrical Engineering University of Toronto Toronto ONT Canada

Results on limit cycle oscillations in floating-point implementations of recursive filters are reviewed. Special attention is paid to structures with a single floating-point nonlinearity in the recursive filter loop, for which efficient criteria are proposed to guarantee the absence of limit cycles. Both unlimited exponent range limit cycles and underflow limit cycles are considered. Also results on wave digital filters and related structures are discussed.< >

关键词： Limit-cycles Quantization Laboratories Signal processing Digital filters Feedback loop Information analysis Information filtering Information filters Hardware

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Multiple branch FIR filters for sampling rate conversion

Multiple branch FIR filters for sampling rate conversion

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： T. Saramaki S.K. Mitra Signal Processing Laboratory Tampere University of Technology Tampere Finland Department of Electrical and Computer Engineering University of California Santa Barbara CA USA

A class of linear-phase finite impulse response (FIR) digital filters for sampling rate conversion is introduced. These filters consist of two cascaded parts. The first part is a parallel connection of two or three branches with transfer function of the form A/sub k/(z)B/sub k/) (z/sup D/), where D is the sampling rate conversion ratio. The second part has a transfer function of the form C(z/sup D/). The advantage of these designs is that they provide a significant reduction in the multiplication and addition rates as well as in the number of required multipliers over the equivalent conventional direct-form designs also in cases where D is a prime number. In these cases, the sampling rate conversion cannot be performed in several stages and many of the other existing designs lose their advantages. Special multiplier-free solutions are generated for implementing the filters A/sub k/(z), resulting in dramatic savings. Several examples are included showing the efficiency of the proposed filters compared to other existing designs.< >

关键词： Finite impulse response filter Sampling methods Delay Passband Niobium USA Councils Baseband Shape Transfer functions Interpolation

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A software engineering, visualization methodology for parallel processing systems

A software engineering, visualization methodology for parall...

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IEEE Annual International computer Software and Applications Conference (COMPSAC)

作者： J.A. Kohl T.L. Casavant Parallel Processing Laboratory Department of Electrical and Computer Engineering University of Iowa Iowa IA USA Iowa Univ. Iowa City IA USA

The authors focus on techniques for enhancing the feasibility of using graphic visualization in analyzing the complexities of parallel software. The central drawback to applying such visual techniques is the overhead in developing analysis tools with flexible, customized views. The PARADISE system alleviates some of this design overhead by providing an abstract, object-oriented, visual modeling environment which expedites custom visual tool development. PARADISE is a visual tool which is used to develop other visual tools, or a meta-tool. The authors complement previous work on PARADISE by describing the philosophy behind its design, and how that philosophy leads to a methodology for constructing visual models which characterize parallel systems in general. The emphasis is on the crucial issues in utilizing visualization for parallel software development, and on how PARADISE deals with these issues.< >

关键词： Software engineering Visualization Parallel processing Animation Object oriented modeling Power system modeling Debugging Programming Laboratories Cities and towns

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Coprime receding horizon feedback control of hot isostatic pressing

Coprime receding horizon feedback control of hot isostatic p...

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IEEE Conference on Control Technology and Applications (CCTA)

作者： D.G. Meyer H.N.G. Wadley Real-Time and Asynchronous Control Laboratory Department of Electrical and Computer Engineering University of Colorado Boulder CO USA Intelligent Processing of Materials Laboratory Department of Material Science and Engineering University of Virginia Charlottesville VA USA

A closed-loop feedback scheme for obtaining a goal microstructure during hot isostatic pressing of powders is described. The control scheme relies on previously developed process models describing the process dynamics during a pressing run and sensors which can measure density and grain size. Constantly updated linearization and coprime factorization are used, so the control can be implemented by convex programming. Simulation results showing the performance of the control scheme are presented.< >

关键词： Feedback control Pressing Microstructure Powders Size control Sensor phenomena and characterization Density measurement Size measurement Grain size Linear programming

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