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991.
992.
993.
为了探讨长江上游流域水土流失及泥沙输移规律,选取嘉陵江中游的支流李子溪为典型流域进行分析研究,在实地调查,野外测验及应用1960年-1991年实测降雨、径流、输沙资料的基础上,利用单因子相关分析和多因子回归分析,分别建立了输水利沙量、最大输沙率计算方程。在此基础上,参照径流瞬时单位线原理,以线性时不变系统为基础,建立输沙瞬时单位线模型。通过输沙单位线与时段净侵蚀量的卷积得到流域出口断面的输沙率过程 相似文献
994.
Reorganisation and evolution of class hierarchies is important for object-oriented system development and has received considerable attention in the literature. The contributions of this paper are: (1) a formal study of a set of extension relations and transformations on class hierarchies; (2) a presentation of a small set of primitive transformations which form a minimal and complete basis for the extension relations; and (3) an analysis of the impact of these transformations at the object level.The study leads to a better understanding of evolution and reuse of object-oriented software and class hierarchies. It also provides a terminology and a means of classification for design reuse. The theory presented in this paper is based on the Demeter data model, which gives a concise mathematical foundation for classes and their inheritance and part-of relationships. Parts of the theory have been implemented in the Demeter System
TM
C++, a CASE tool for object-oriented design and programming. 相似文献
995.
微米级冷轧带钢厚度控制系统 总被引:2,自引:1,他引:1
分析、讨论了冷轧应用的各种厚度控制的优缺点,介绍质量流量厚度控制原理和控制精度极高的微米级带钢厚控(μAGC)系统及其可能产生的经济效益。 相似文献
996.
Cr12钢的预处理工艺研究 总被引:3,自引:0,他引:3
本文研究了Cr12钢经4种不同的预处理工艺处理后钢中碳化物的大小,数量,分布及钢的硬度,强度和韧性,试验结果表明,经调质处理,高温固溶淬火+高温退火处理后,Cr12钢中碳化物的大小,分布及其组织,性能均优于常规球化退火预处理的。通过扫描电镜对冲击断口的分析,初步探讨了新的预处理工艺提高韧性的原因。 相似文献
997.
Cu, In and Se have been codeposited in thin films by potentiostatic one-step electrodeposition. The as-deposited material has shown direct optical transitions attributable to the CuInSe2 semiconductor, but also additional absorption corresponding to another semimetallic phase. The secondary phases are selenium and copper selenide compounds which have been determined by composition measurements. In order to eliminate the semimetallic phases and to improve the semiconductor behaviour of the electrodeposited material, thermal and chemical treatments have been performed. After heat-treatment of the samples at 400°C in flowing argon, elemental selenium loss has been detected together with an enhancement of the allowed direct optical transition. The subsequent chemical etching of the layers in a KCN solution has showed to be successful in eliminating the copper selenide phases which were responsible of the remaining sub-bandgap absorption. 相似文献
998.
Josef Skrzypek 《Journal of Intelligent Manufacturing》1993,4(1):67-77
Computer vision algorithms for inspection or pick-and-place operations often depend on spatially uniform illumination of a workplace. This necessitates expensive lighting fixtures. To discount effects of uneven illumination we designed and tested a neural network that can adaptively control light sensitivity at the photosensor level. Our neural network architecture consists of multiple layers with hexagonally arranged nodes. All nodes have partially overlapping receptive fields of different spatial frequencies. Feedforward connections are excitatory while feedback pathways subserve lateral inhibition. The outputs of these nodes are combined so as to maximize the signal-to-noise ratio while constantly resetting thresholds to maintain high sensitivity. Our connectionist architecture can account for many characteristics attributed to the lightness constancy phenomenon observed in biological systems. The results suggest that our module maintains high sensitivity over the whole domain of intensities without interfering with transmission of visual information embedded in spatial discontinuities of intensity. 相似文献
999.
The general mixed μ problem has been shown to be NP hard, so that the exact solution of the general problem is computationally intractable, except for small problems. In this paper we consider not the general problem, but a particular special case of this problem, the rank one mixed μ problem. We show that for this case the mixed μ problem is equivalent to its upper bound (which is convex), and it can in fact be computed easily (and exactly). This special case is shown to be equivalent to the so-called ‘affine parameter variation’ problem (for a polynomial with perturbed coefficients) which has been examined in detail in the literature, and for which several celebrated ‘Kharitonov-type’ results have been proven. 相似文献
1000.