共查询到20条相似文献,搜索用时 46 毫秒
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近些年来,关于电子元器件的失效分析已逐渐发展成为一个专门的学科,作为专门的模拟集成电路设计、生产单位,在分析仪器、设备有限的条件下,通过失效分析发现产品设计、测试、以及生产制造过程中存在的问题,以不断改进产品的设计水平和制造工艺,提高产品的可靠性。通过对某中频控制器在用户处表现出来的低温下通断比异常的情况进行分析,发现该产品的设计存在的问题,文中不仅给出了失效机理,同时提出了改进措施。此次失效分析对于同类中频控制器的设计、提高其可靠性具有一定的借鉴意义。 相似文献
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塑封器件具有体积小、成本低的优点,逐步替代气密性封装器件,广泛地应用于我国军用产品中。军用塑封SIP(System In Package)产品集成度高、结构复杂、可靠性要求高等特点,对塑封工艺带来了挑战,目前国内工业级塑封产品不能完全满足军用可靠性要求,工业级塑封产品常在严酷的环境应力试验下表现出失效。本文针对工业级塑封SIP器件在可靠性试验过程中出现的失效现象进行分析研究,通过超声检测、芯片切面分析等手段,结合产品应力试验结果,分析导致塑封产品失效的关键原因,并针对失效机理提出优化改进方案。 相似文献
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电子产品的可靠性试验 总被引:1,自引:0,他引:1
"电子产品的可靠性试验"顾名思义为评价分析电子产品可靠性而进行的试验.其试验目的通常有以下几个方面:(1)在产品研制阶段用以暴露试制产品各方面的缺陷,评价产品可靠性达到预期指标的情况;(2)生产阶段为监控生产过程提供信息;(3)对定型产品进行可靠性鉴定或验收;(4)暴露和分析产品在不同环境和应力条件下的失效规律及有关的失效模式和失效机理;(5)为改进产品可靠性,制定和改进可靠性试验方案,为用户选用产品提供依据. 相似文献
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ABSTRACT: There are a large number of conceptual hydrological models available today. It is not easy to immediately identify the similarities and differences between the different models. The Swedish HBV model and the Chinese Xinanjiang model are two examples of conceptual, semi-distributed, rainfall-runoff models. The Xinanjiang model was designed for use in humid and semi-humid regions, with no routine for the snowmelt runoff, whereas the snow routine is an important part of the HBV model in many applications. The model structures of the two models may be described in four routines, compared in this paper. The integral structures of them are similar, but there are some differences, especially in the runoff production routine. The physical significance and physical definitions of some model parameters were analyzed. Both models were tested in two basins. Both models gave similar results, and both models performed well in the application. The similarity of the results obtained by different model structures leads to the following two conclusions. First, more effort should probably be spent on the improvement of input data quality and coverage than on the development of more detailed model structures only. Second, inference about basin behavior and characteristics from the values of calibrated model parameters must be made with great caution. 相似文献
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Christopher G. Uchrin Walter J. Weber 《Journal of the American Water Resources Association》1983,19(4):581-584
ABSTRACT A dynamic mathematical model was constructed to examine bacterial contamination problems affecting Ford Lake, a small recreational lake in Southeast Michigan. The model was calibrated and verified using summer dry weather averaged data and data from three wet weather surveys. Model simulations demonstrated that the major bacterial contamination was attributable to storm related perturbations affecting two point sources: the Huron River and the Ypsilanti Sewage Treatment Plant. The nonpoint source contribution was relatively minor. The Model is currently being used by the State of Michigan Department of Natural Resources as a management tool for assessing the effectiveness of planned pollution abatement strategies 相似文献
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ABSTRACT: Investigating natural, potential, and human-induced impacts on hydrologic systems commonly requires complex modeling with overlapping data requirements, plus massive amounts of one- to four-dimensional data at multiple scales and formats. Given the complexity of most hydrologic studies, the requisite software infrastructure must incorporate many components including simulation modeling and spatial analysis with a flexible, intuitive display. Integrating geographic information systems (GIS) and scientific visualization systems (SVS) provides such an infrastructure. This paper describes an integrated system consisting of an orographic precipitation model, a GIS, and an SVS. The results of this study provide a basis for improving the understanding of hydro-climatic processes in mountainous regions. An additional benefit of the integrated system, the value of which is often underestimated, is the improved ability to communicate model results, leading to a broader understanding of the model assumptions, sensitivities, and conclusions at a management level. 相似文献
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《Resources, Conservation and Recycling》2011,55(12):1362-1367
The methodology of mass and energy integration is widely applied for reduction of water consumption, which belongs to the area of mass integration, and is also energy integration problem if water is considered an energy source (cooling water and steam). This work presents a study of water-consumption reduction through optimization of the process superstructure. A petroleum refinery water network was analyzed and a solution is proposed to minimize the costs of fresh water and wastewater treatment. Three processes which use water, with three contaminants, were monitored and three potential treatment units are proposed. The procedure was based on relaxation of a non-convex non-linear programming problem into a mixed integer linear programming (MILP). The MILP model was further simplified using heuristic rules and solved by using MATLAB. 相似文献
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TWO STRATEGIES FOR LEARNING A ROUTE IN A DRIVING SIMULATOR 总被引:2,自引:0,他引:2
Vlada Aginsky Catherine Harris Ronald Rensink Jack Beusmans 《Journal of environmental psychology》1997,17(4):317-331
The study of human navigation has long been dominated by the so-called stage theory, i.e. the notion that there are three distinct types of spatial knowledge (landmark, route, and survey knowledge), that are acquired sequentially during spatial learning and development. Based on the results of a route learning experiment in a driving simulator, an alternative to the stage theory is proposed. The authors suggest that subjects follow either a visually dominated or a spatially dominated strategy to solve a route-learning problem. In the visually dominated strategy, subjects base their wayfinding decisions on visually recognizing decision points along a route; the decision points are not integrated into any kind of survey representation. In the spatially dominated strategy, on the other hand, subjects represent the environment as a survey map right from the start; that is, they do not pass through a landmark or route stage. These strategies may be subserved by different cortical areas recently characterized in neurophysiological studies of animals solving maze problems. 相似文献
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Shing-Fu Hsueh Robert C. Ahlert 《Journal of the American Water Resources Association》1978,14(6):1404-1416
ABSTRACT: An input-output method, using a network of ideal continuous stirred-tank and plug-flow tublar reactors, is adopted to analyze residence time distribution data for a separated mechanical aeration system. The usefulness of this modeling concept is enhanced by its simplicity, especially in the presence of a first-order reaction. This facilitates use of the model format for wastewater quality prediction. Moreover, first-order rate constants can also be estimated from the model, if conversions due to the reaction rate are available. 相似文献
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