In this paper we apply a finite difference lattice Boltzmann model to study the phase separation in a two-dimensional liquid-vapor system. Spurious numerical effects in macroscopic equations are discussed and an appro...
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In this paper we apply a finite difference lattice Boltzmann model to study the phase separation in a two-dimensional liquid-vapor system. Spurious numerical effects in macroscopic equations are discussed and an appropriate numerical scheme involving flux limiter techniques is proposed to minimize them and guarantee a better numerical stability at very low viscosity. The phase separation kinetics is investigated and we find evidence of two different growth regimes depending on the value of the fluid viscosity as well as on the liquid-vapor ratio.
We describe the design and implementation of a hybrid intelligent surveillance system consisting of an embedded system and a personal computer (PC)-based system. The embedded system performs some of the image processi...
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We describe the design and implementation of a hybrid intelligent surveillance system consisting of an embedded system and a personal computer (PC)-based system. The embedded system performs some of the image processing tasks and sends the processed data to a PC. The PC tracks persons and recognizes two-person interactions by using a grayscale side-view image sequence captured by a stationary camera. Based on our previous research, we explored the optimum division of tasks between the embedded system and the PC, simulated the embedded system using dataflow models in Ptolemy, and prototyped the embedded systems in real-time hardware and software using a 16-bit CISC microprocessor. This embedded system processes one frame image in 89 ms, which is within three frame-cycle periods for a 30 Hz video system. In addition, the real-time embedded system prototype uses 5.7 Kbytes of program memory, 854 Kbytes of internal data memory and 2 Mbytes external DRAM.
Three-dimensional real-time digital sonar beamforming requires 4 to 12 GFLOPS, 1 to 2 GB of memory, and about 100 MB/s of I/O bandwidth. G.E. Allen and B.L. Evans have implemented a 4-GFLOP sonar beamformer in real-ti...
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ISBN:
(纸本)0780365143
Three-dimensional real-time digital sonar beamforming requires 4 to 12 GFLOPS, 1 to 2 GB of memory, and about 100 MB/s of I/O bandwidth. G.E. Allen and B.L. Evans have implemented a 4-GFLOP sonar beamformer in real-time on a Sun UltraSPARC II server with 16 333-MHz processors by utilizing the Visual Instruction Set (VIS) single-instruction multiple-data (SIMD) extensions. In this paper, we rewrite the horizontal and vertical beamforming kernels to use AltiVec SIMD extension for the PowerPC. AltiVec can execute up to four 32-bit floating-point multiply and accumulate (MAC) operations per instruction. In the PowerPC implementation, we prefetch and realign data for the I28-bit SIMD registers of AltiVec. We evaluate the performance of these beamforming kernels on the PowerPC and the UltraSPARC-II to evaluate the impact of the compiler, SIMD word alignment, and cache block alignment on performance.
Image indexing is the process of image retrieval from databases of images or videos based on their contents. Specifically histogram-based algorithms are considered to be effective for color image indexing. We suggest ...
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Image indexing is the process of image retrieval from databases of images or videos based on their contents. Specifically histogram-based algorithms are considered to be effective for color image indexing. We suggest a new method of color space quantization in the CIELUV color space, named weighted LUV quantization. With this method, each bin in the LUV space has a different weighting factor, which is applied to the histogram intersection. The weighted LUV histogram intersection provides the advantage of perceptual uniformity of the CIELUV color space. An additional advantage is the consideration of perceptual sensitivity to more saturated colors by the use of a weighting factor.
The Rapid Prototyping of Application Specific signal Processors (RASSP) program is a multi-year DARPA/Tri-Service initiative intended to dramatically improve the process by which complex digital systems, particularly ...
The Rapid Prototyping of Application Specific signal Processors (RASSP) program is a multi-year DARPA/Tri-Service initiative intended to dramatically improve the process by which complex digital systems, particularly embedded digital signal processors, are designed, manufactured, upgraded, and supported. This paper reviews the genesis of the RASSP program, considering both the problems that defined the need for the program, and the historical conditions under which it began. The RASSP program is then presented from two viewpoints. The first is programmatic, covering the goals and constraints of the program, and describing the roles of the various program participants. The second is technical, covering the major concepts upon which the developing RASSP approach to design is based and showing how the detailed technical discussions contained in the other papers in this issue of the Journal of VLSI signalprocessing relate to one another and fit into an overall development concept. The paper closes with a review of the status of the program as of this writing (Summer 1996).
We have developed a new signal-dependent representation which captures, with a few KL vectors and transform coefficients, the perceptually and phonetically important structure of the spectral envelope. Together with a...
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Two computationally efficient algorithms for digital cyclic spectral analysis, the FFT accumulation method (FAM) and the strip spectral correlation algorithm (SSCA), are developed from a series of modifications on a s...
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Two computationally efficient algorithms for digital cyclic spectral analysis, the FFT accumulation method (FAM) and the strip spectral correlation algorithm (SSCA), are developed from a series of modifications on a simple time smoothing algorithm. The signalprocessing, computational, and structural attributes of time smoothing algorithms are presented with emphasis on the FAM and SSCA. As a vehicle for examining the algorithms the problem of estimating the cyclic cross spectrum of two complex-valued sequences is considered. Simplifications of the resulting expressions to special cases of the cross cyclic spectrum of two complex-valued sequences, such as the cyclic spectrum of a single real-valued sequence, are easily found. Computational and structural simplifications arising from the specialization are described.
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