共查询到17条相似文献,搜索用时 671 毫秒
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探讨并阐述了机电产品及材料高原自然环境和高原模拟环境曝露试验原理,试验方式,特殊的技术要求和试验方法。 相似文献
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探讨并阐述了机电产品及材料高原自然环境和高原模拟环境曝露试验原理、试验方式、特殊的技术要求和试验方法。 相似文献
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雷达环境试验是产品特定技术要求规定的。只有科学的试验方法,才能有效评价雷达在我国自然环境条件下贮存、运输和使用的适应性。自然环境是一个多变量的综合环境,如:温度、阳光、生物、风沙、雨水和机械环境应力等同时对产品作用。而雷达环境试验是用模拟的方法,在试... 相似文献
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Hanson N 《Journal of environmental management》2011,92(3):610-619
Field surveys of biological responses can provide valuable information about environmental status and anthropogenic stress. However, it is quite usual for biological variables to differ between sites or change between two periods of time also in the absence of an impact. This means that there is an obvious risk that natural variation will be interpreted as environmental impact, or that relevant effects will be missed due to insufficient statistical power. Furthermore, statistical methods tend to focus on the risks for Type-I error, i.e. false positives. For environmental management, the risk for false negatives is (at least) equally important. The aim of the present study was to investigate how the probabilities for false positives and negatives are affected by experimental set up (number of reference sites and samples per site), decision criteria (statistical method and α-level) and effect size. A model was constructed to simulate data from multiple reference sites, a negative control and a positive control. The negative control was taken from the same distribution as the reference sites and the positive control was just outside the normal range. Using the model, the probabilities to get false positives and false negatives were calculated when a conventional statistical test, based on a null hypothesis of no difference, was used along with alternative tests that were based on the normal range of natural variation. Here, it is tested if an investigated site is significantly inside (equivalence test) and significantly outside (interval test) the normal range. Furthermore, it was tested how the risks for false positives and false negatives are affected by changes in α-level and effect size. The results of the present study show that the strategy that best balances the risks between false positives and false negatives is to use the equivalence test. Besides tests with tabulated p-values, estimates generated using a bootstrap routine were included in the present study. The simulations showed that the probability for management errors was smaller for the bootstrap compared to the traditional test and the interval test. 相似文献
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本文从军工电子产品环境试验出发,介绍了环境试验的三种形式,分另4从四个方面阐述了环境试验与可靠性试验和环境应力筛选试验之间的区别和联系,并对环境试验中个试验项目顺序的选择进行了讨论,最后推荐了在军工电子产品定型试验和批次产品验收试验时的环境试验的项目顺序。 相似文献
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本文从环境试验技术的发展历程,论述了环境试验技术对工业领域尤其是航空航天领域的重要性,通过阐述环境试验技术的特点、作用、相互关系,分析了国内环境试验技术研究与应用的现状、存在的问题及其与国外的差距,提出了环境试验今后的发展趋势。 相似文献
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简单介绍了大气环境试验的发展历程。从不同技术角度,分析了大气环境试验的种类、应用、大气监测和样品检测、试验站、信息技术、加速试验及标准化等7个方面的国内外发展现状和趋势。最后提出几点建议。 相似文献
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