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981.
Both integrating sphere reflectometry (ISR) as well as laser polarimetry have their advantages and limitations in their ability to determine the normal spectral emissivity of metallic samples. Laser polarimetry has been used for years to obtain normal spectral emissivity measurements on pulse-heated materials. The method is based on the Fresnel equations, which describe reflection and refraction at an ideally smooth interface between two isotropic media. However, polarimetry is frequently used with surfaces that clearly deviate from this ideal condition. Questions arise with respect to the applicability of the simple Fresnel equations to non-specular surfaces. On the other hand, reflectometry utilizing integrating spheres provides a measurement of the hemispherical spectral reflectance, from which the normal spectral emissivity can be derived. ISR provides data on spectral-normal-hemispherical reflectance and, hence, normal spectral emissivity for a variety of surfaces. However, the resulting errors are minimal when both the sample and the reference have a similar bidirectional reflectance distribution function (BRDF). In an effort to explore the limits of polarimetry in terms of surface roughness, room temperature measurements on the same samples with various degrees of roughness were performed using both ISR and a laser polarimeter. In this paper the two methods are briefly described and the results of the comparison are discussed. 相似文献
982.
Quinjiao Wang Kenji Itaka Hideki Minami Hitoshi Kawaji Hideomi Koinuma 《Science and Technology of Advanced Materials》2004,5(5-6):543
La1−xCaxVO3 composition-spread film library was fabricated by combinatorial pulsed laser deposition and their thermoelectric properties were evaluated paralelly by the multi-channel probes of Seebeck coefficient and electric conductivity. Concurrent X-ray analysis verified the formation of solid soluted films in the full composition range (0x1) as judged from the linear variation of the lattice constants. The Seebeck coefficients of La1−xCaxVO3 changed from a large negative value to almost zero with the increase of x, due presumably to the variation of valence in vanadium ions.The power factor in this library was as high as 0.6 μW/cm K2, which was obtained at x=0, i.e. pure LaVO3 grown at 800 °C. 相似文献
983.
废弃产品的拆卸回收是绿色制造中的关键技术。运用Petri网作为数学工具描述产品的拆卸树,并用自定义的语法作形式化的表达,重点研究了选择性拆卸问题。这对于废弃产品的回收、重用以及日常的维修,都具有重要作用。基于拆卸Petri网,提出了两种评价函数,并运用反向启发式搜索策略,形成了一个改进型的算法。最后对一个工程实例作了具体研究,验证了方法的可行性,使得选择性拆卸序列具有供现场机器人实用的价值。 相似文献
984.
985.
986.
李宏伟 《数值计算与计算机应用》2004,25(1):36-47
引言 区域分裂方法起源于古老的schwarz交替方法[l].八十年代末期,法国数学家P.L.LionS提出了schwarz交替方法的投影解释[2一4],使得人们对schwarz交替方法有了全新的认识,为其进一步发展奠定了理论基础.由于并行计算环境的逐渐成熟以及预处理技术的兴起和大规模科学计算的需要,由严格串行的scliwarz交替方法发展了多种可完全并行的 相似文献
987.
Networked Manufacturing is the trend evolution for manufacture enterprise to gain core competence in the networked economy environment. In this paper, the definition of the strategic alliance is introduced and its life cycle is described. As the selection of suitable partners is of vital importance to the success for strategic alliance in Networked Manufacturing environment, also in this paper, the definition, criteria and process for partner selection are introduced. Then the fuzzy-AHP (Analytic Hierarchy Process) method, as a fuzzy extension of analytic hierarchical approach for partner selection, is given. In the end, a case study is provided. 相似文献
988.
Cemalettin Kubat Harun Taşkin Bayram Topal Safiye Turgay 《Journal of Intelligent Manufacturing》2004,15(4):517-526
Since 1950s the techniques of Operations Research (OR) and Optimization have been utilized to increase the efficiency of the production systems. With the widespread use of computers, it has even become easier to deal with industrial problems. However the complexity of the problems still reveals the difficulty in providing solutions. The use of artificial intelligence (AI) seems to attract the attention of the researcher to overcome to the difficulties. This has already been realized with several successful applications. In this study, the use of AI and OR techniques is compared using fuzzy logic. The progress of manufacturing systems, characteristics of production processes, system managements and system behavior are taken into account. The study is focussed on only discrete manufacturing. 相似文献
989.
This paper represents a first attempt at a systematic study of sensitivity analysis for scheduling problems. Because schedules contain both combinatorial and temporal structures, scheduling problems present unique issues for sensitivity analysis. Some of the issues that we discuss have not been considered before. Others, while studied before, have not been explored in the context of scheduling. The applicability of these issues is illustrated using well-known scheduling models. We provide fast methods to determine when a previously optimal schedule remains optimal. Other methods restore an optimal schedule after a parameter change. The value of studying the sensitivity of an optimal sequence instead of the sensitivity of an optimal schedule is demonstrated. We show that, for some problems, sensitivity analysis results depend on the positions of jobs with changed parameters. We identify scheduling problems where performing additional or different computations during optimization facilitates sensitivity analysis. To improve the robustness of an optimal schedule, selection among multiple optimal schedules is considered. We discuss which types of sensitivity analysis questions are intractable because the scheduling problem itself is intractable. We also study how heuristic error bounds vary when the data of a scheduling problem is continuously modified. Although we focus on scheduling problems, several of the issues we discuss and our classification scheme can be extended to other optimization problems. 相似文献
990.
Borosilicate glass and borosilicate glass matrix composites reinforced with 10, 15 and 30 vol.% alumina platelets have been indented and the subsurface lateral cracking examined by confocal scanning laser microscopy (CSLM). The suitability of the CSLM technique as a quick and nondestructive method of obtaining three-dimensional information of subsurface damage in dispersion reinforced brittle matrix composite materials was demonstrated. The addition of alumina platelets to the glass matrix has resulted in a reduction in the extent and depth of subsurface damage due to indentation, and hence may make the material more resistant to erosive wear. This damage development may be a consequence of the presence of residual compressive stresses in the matrix and the strong platelet/matrix interfacial bonding. 相似文献