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141.
This paper presents the development of an optimization and a computer-simulation model to evaluate the process plans of a manufacturing center by analyzing the effect of tool failure on system performance. The GPSS/PC simulation program that is used in this study has been built with variables, functions and matrices so that many experiments could be conducted with the model. Sensitivity analysis is presented and the developed model has proven to be useful in determining optimum sequencing of parts for various operating policies. 相似文献
142.
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145.
本文主要从土壤 pH ,重碳酸盐 ,和氮素形态等几方面综述了各种土壤因子对土壤缺铁失绿的影响 ,并提出了进一步加强研究的方向 相似文献
146.
J.-S. LiuJ.-H. Chuang 《Pattern recognition》2002,35(1):155-167
For choosing specific cross-ratios as 2D projective coordinates in various computer vision applications, a reasonable error analysis model is usually required. This investigation adopts the assumption of normal distribution for positioning errors of point features in an image to formulate the error variances of cross-ratios. Based on a geometry-based error analysis, a straightforward way of identifying the cross-ratios with minimum error variances is proposed. Simulation results show that the proposed approach, as well as a further simplified alternative, yield much better estimations of minimum error variances in terms of accuracy, cost, and stability compared with some other methods, e.g., the one based on the rule given by Georis et al. (IEEE Trans. Pattern Anal. Mach. Intell. 20 (4) (1998) 366). Some causes of the performance differences in the estimations are explained using a special configuration of point features. 相似文献
147.
We have used x-ray phase analysis to study the composition of the products of reaction between oxygen and nanocrystalline
powders with particle sizes 15, 40, 55, and 80 nm, and also specimens pressed (and sintered) from them. The powders were oxidized
in air at 100°C (400 h) to 500°C (5 min), while the sintered specimens were oxidized at 600–900°C for 15, 120, and 240 min.
In all cases, in the initial oxidation step the oxynitride Ti(OxNy) is formed, which over time is oxidized to TiO, Ti2O3, Ti3O5, TiO2 (anatase) and TiO2 (rutile). In the range 600–800°C, formation of a continuous oxide layer and conversion of anatase to rutile slows down diffusion
of oxygen in the scale. We have established that at 900°C, the growth rate of the scale thickness increases and so the reflections
from the oxynitride are barely noticeable on the diffraction patterns taken from the surface of the oxidized specimen. In
these diffraction patterns, along with strong reflections from the rutile, we also observed weak reflections from lower oxides
and anatase, which may be due to reaction between oxygen and the titanium ions diffused to the scale surface. We have concluded
that at T > 850°C, the mechanism for oxidation of TiN changes. This is due to superposition of counterdiffusion of titanium
ions on the diffusion of oxygen.
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Translated from Poroshkovaya Metallurgiya, Nos. 3–4(448), pp. 72–78, March–April, 2006. 相似文献
148.
Using the Internet, “public” computing grids can be assembled using “volunteered” PCs. To achieve this, volunteers download and install a software application capable of sensing periods of low local processor activity. During such times, this program on the local PC downloads and processes a subset of the project's data. At the completion of processing, the results are uploaded to the project and the cycle repeats. 相似文献
149.
An incremental iterative process based on direct energy minimization is presented for a limit analysis of nonlinear elastic lateral displacements and twists of reinforced and prestressed beams. Problems encountered with the constitutive relations are discussed and two possible material models are presented. 相似文献
150.
Many real-world problems are multi-objective optimization problems and evolutionary algorithms are quite successful on such problems. Since the task is to compute or approximate the Pareto front, multi-objective optimization problems are considered as more difficult than single-objective problems. One should not forget that the fitness vector with respect to more than one objective contains more information that in principle can direct the search of evolutionary algorithms. Therefore, it is possible that a single-objective problem can be solved more efficiently via a generalized multi-objective model of the problem. That this is indeed the case is proved by investigating the computation of minimum spanning trees.This work was supported by the Deutsche Forschungsgemeinschaft (DFG) as part of the Collaborative Research Center Computational Intelligence (SFB 531) and by the German-Israeli Foundation (GIF) in the project Robustness Aspects of Algorithms. 相似文献