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排序方式: 共有650条查询结果,搜索用时 78 毫秒
51.
In this article we consider the scalar transport governed by the convection-diffusion equation with linear production in two dimensions. The underlying idea in the development of a steady discretization scheme is to incorporate the analytical solution, obtained within a one-dimensional context, into the formulation. The method adopted here features exponential character in the weighted coefficients of the matrix equation, which generates a scheme with high accuracy. The analysis is followed by extending this discretization scheme to solve the convection-diffusion-production equation with a source term. In this article we present an analytical validation study of the method applied to two classes of model equations. Having verified that the method applies equally well for a transport scalar in either case with constant or variable flow velocity, we employ the one-dimensional scheme in the predictor and corrector steps to obtain the two-dimensional solution in an alternating direction-implicit fashion. The result obtained for the test considered in this article follows the trend of analytic data. 相似文献
52.
ABSTRACT Structure, Interaction, and phase transition of a vacuum residue fractions In various apolar solvents were Investigated, using viscosity measurements and small angle neutron scattering. Both light and heavy ended fractions form colloidal particles of spherical shape with average sizes of -40 and -60 A respectively. The size distributions follow a Schultz distribution function approximately. Rheological studies of these fractions indicated significant particle solvation. The solvation mechanism is through association of the solvent molecules with individual VR colloids, instead of through solvent entrapment between agglomerated colloids. The viscosity, as a function of temperature, suggested a glass-like transition at approximately 254?K for the heavy ended fraction at 0.5 volume fraction. The small angle neutron scattering measurements confirmed the colloidal structure determined from rheological study. It also provided the information about the total colloids/solvent Interfacial area, from which we found that VR colloids have a rough surface 相似文献
53.
The long-term current instability of AlGaAs/GaAs heterojunction bipolar transistor (HBT) is studied, and the physical mechanism contributing to such a behavior is investigated. Based on this, a model capable of predicting the HBT long-term current drift and mean time to failure (MTTF) is developed. In addition, such a model is implemented into SPICE circuit simulator, thus allowing the simulation of HBT circuits subjected to an electrical and thermal stress condition. 相似文献
54.
Sheu J.-P. Han-Lih Wang Chi-He Chang Yu-Chee Tseng 《Broadcasting, IEEE Transactions on》2004,50(2):120-125
Broadcasting is a prospective approach to support near video-on-demand services with light communication overhead. By letting clients share channels, such approaches involve partitioning a video into segments and repeatedly broadcasting these segments in multiple channels. An early paper proposed a broadcasting scheme called RFS (recursive frequency splitting), which can significantly reduce clients' waiting time. While efficient, RFS suffers from a high computational complexity of O(nlogn), where n is the number of segments of the video, which is typically very large. This paper proposes an efficient segmentation scheme, which can significantly reduce the computational overhead by slightly sacrificing the number of segments that can be arranged as compared to RFS. 相似文献
55.
Nitride-Based ultraviolet metal-semiconductor-metal photodetectors with a low-temperature GaN layer 总被引:1,自引:0,他引:1
J. K. Sheu C. J. Kao M. L. Lee W. C. Lai L. S. Yeh G. C. Chi S. J. Chang Y. K. Su J. M. Tsai 《Journal of Electronic Materials》2003,32(5):400-402
The GaN metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors with a low-temperature (LT)-GaN layer have been demonstrated.
It was found that we could achieve a two orders of magnitude smaller, photodetector-dark current by introducing a LT-GaN layer,
which could be attributed to the larger Schottky-barrier height between the Ni/Au metal contact and the LT-GaN layer. It was
also found that photodetectors with the LT-GaN layer could provide a larger photocurrent to dark-current contrast ratio and
a larger UV-to-visible rejection ratio. The maximum responsivity was found to be 3.3 A/W and 0.13 A/W when the photodetector
with a LT-GaN layer was biased at 5 V and 1 V, respectively. 相似文献
56.
Richard H. Tsai Bing J. Sheu Theodore W. Berger 《Analog Integrated Circuits and Signal Processing》1998,15(2):201-213
The hippocampal region of the brain system can be analyzed with the nonlinear system modeling approach. The input-output relationship of the neural units is best represented by the kernel functions of different complexities. The modeling expression of the first and second order kernels are computed in analog current-mode instead of digital data processing in order to fully explore massively parallel processing capability of the neural networks. Two distinct methods are utilized: the table-look-up approach and the model-based approach. The former can achieve high accuracy but consumes large silicon area while the latter saves silicon area and maintains moderately high accuracy. Circuit-level simulation results and experimental data from two test structures are presented. 相似文献
57.
Meng-Lieh Sheu 《Analog Integrated Circuits and Signal Processing》2002,31(3):191-192
58.
Shey-Huei Sheu 《Microelectronics Reliability》1992,32(5)
A system is subject to shocks that arrive according to a nonhomogeneous Poisson process. The system is replaced at age T at a fixed cost c0. If the k-th shock arrives at time Sk<T, it is either a fatal shock with probability p(Sk) or a nonfatal shock with probability 1−p(Sk). The fatal shock causes the system total breakdown, and the system is replacd at a cost c∞. The nonfatal shock weakens the system and makes it more expensive to run. The aim of the paper is to find the optimal T which minimizes the long run expected cost per unit time of the policy. Various special cases are considered. 相似文献
59.
Ming-Hwa Sheu Su-Hon Lin Chichyang Chen Shyue-Wen Yang 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2004,51(3):152-155
In this paper, we present a new four-moduli set (2/sup n/-3,2/sup n/+1,2/sup n/-1,2/sup n/+3) and an efficient residue to binary (R/B) converter design. The merits of the proposed four-moduli set include 1) larger dynamic range; 2) higher degree of parallelism for conversion; 3) balanced bit-width for internal RNS arithmetic operations; and 4) flexible moduli set selection. According to the relation between the proposed moduli, the divide-and-conquer technique is used to design a two-level converter architecture which has lower hardware cost and shorter critical delay. For the R/B converter designed with 12-b (n=3), our architecture has about 47% saving in hardware cost and 40% saving in critical delay compared to the last work. 相似文献
60.
EY Sheu 《Canadian Metallurgical Quarterly》1992,45(4):2428-2438