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首先以 HERMLE C1200 U 为例分析了五轴铣削加工中心的基本结构,然后据此给出了涉及多轴铣削加工中心后置处理角度分配和坐标变换的数学模型,最后介绍了以此数学模型为核心,为UG 软件开发的后置处理软件 UG-HERP1.0的解决方案。 相似文献
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The corrosion mechanism and microstructural characteristics of yttria (Y2 O3 ) exposed to uranium hexafluoride (UF4 ) and uranium tetrafluoride gases at temperatures above 900°C were investigated. Processed yttria samples were exposed for times ranging from 5 to 40 min. A weight increase was observed after each test exposure. An outer corrosion scale composed of UO2 and YF3 , and an inner corrosion layer of YF3 , were observed following the UF6 reaction at nearly 1200 K. During the UF4 exposure, an outer layer containing a liquid mixture of fluoride, oxygen, yttrium, uranium compounds, a secondary reaction layer of UO2 followed by an inner layer composed of a solution of Y2 O3 and YF3 , possibly in the form of YOF inner layer, were observed. It was found that the corrosion process is controlled by the diffusion which is evidenced by the parabolic growth rate of the secondary layer. After completion of the solidification process, the formation of a eutectic region and dendrites were observed throughout the outer scale. In general, at temperatures above 1173 K, high corrosion rates were observed, and yttria did not appear to be a viable containment material for UF4 and UF6 . 相似文献
4.
BATCH SEQUENCING 总被引:1,自引:0,他引:1
Consider the single machine scheduling problem where there are a number of part types to be processed. A part type is defined as follows: Two parts are of the same part type if the machine does not require a setup in between the processing of these parts. The problem investigated in this paper is to find a sequence of batches of parts (if there are any) where all the requirements for parts are met. A heuristic and an exact algorithm are developed, and computational analysis is performed to measure the performance of the heuristic. The time complexity function of the heuristic is O(n2), and the exact algorithm runs in polynomial time given a fixed upper bound on the number of setups. 相似文献
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Tamer Rabie 《IEEE transactions on image processing》2005,14(11):1755-1765
This work develops a new robust statistical framework for blind image denoising. Robust statistics addresses the problem of estimation when the idealized assumptions about a system are occasionally violated. The contaminating noise in an image is considered as a violation of the assumption of spatial coherence of the image intensities and is treated as an outlier random variable. A denoised image is estimated by fitting a spatially coherent stationary image model to the available noisy data using a robust estimator-based regression method within an optimal-size adaptive window. The robust formulation aims at eliminating the noise outliers while preserving the edge structures in the restored image. Several examples demonstrating the effectiveness of this robust denoising technique are reported and a comparison with other standard denoising filters is presented. 相似文献
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Development of a suitable model for characterizing photovoltaic arrays with shaded solar cells 总被引:2,自引:0,他引:2
The aim of this study is to investigate the effects of non-uniform solar irradiation distribution on energy output of different interconnected configurations in photovoltaic (PV) arrays. In order to find which configuration is less susceptible to mismatch effects, a PV module model is developed. This model can take into consideration the effects of bypass diodes and the variation of the equivalent circuit parameters with respect to operating conditions. The proposed model can provide sufficient degree of precision as well as solar cell-based analysis in analyzing large scale PV arrays without increasing the computational effort. In order to produce more reliable and robust simulations, improved and extended algorithms are presented. Some results are discussed in detail and some recommendations are extracted by testing several shading scenarios. 相似文献
9.
Thermoplastic polyolefin (TPO) films with permanent, silicone‐rich, low‐friction, low‐abrasion surfaces were obtained by melt blending of high‐density polyethylene (HDPE) and polypropylene (PP) with polydimethylsiloxane (PDMS)‐containing block copolymers. Two different block copolymers, a siloxane–urea segmented copolymer and a polycaprolactone‐b‐PDMS triblock copolymer were used as modifiers at levels between 0.1 and 5.0% by weight. Blends were prepared in a twin‐screw extruder. Modified films displayed surfaces with very low friction coefficients and high abrasion resistance, which depended on the type and the level of additive incorporated into the system. Bulk properties of these modified systems, such as crystallization and melting behavior or tensile properties, were not affected. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 535–540, 2002; DOI 10.1002/app.10279 相似文献
10.
This paper presents a genetic based incremental neural network (GINeN) for the segmentation of tissues in ultrasound images. Performances of the GINeN and the Kohonen network are investigated for tissue segmentation in ultrasound images. Feature extraction is carried out by using continuous wavelet transform. Pixel intensities at the same spatial location on 12 wavelet planes and on the original image are considered as features, leading to 13-dimensional feature vectors. The same training set is used for the training of the Kohonen network and the GINeN.
This paper proposes the use of wavelet transform and genetic based incremental neural network together in order to increase the segmentation performance. It is observed that genetic based incremental neural network gives satisfactory segmentation performance for ultrasound images. 相似文献