排序方式: 共有93条查询结果,搜索用时 31 毫秒
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借助于 Web,异地分布的异构关系数据进行融合与交互成为可能 ,提出具有不同模式描述的关系数据自动地进行融合和交互的第一步是对关系模式进行基于语义信息的等价性评价这一概念 ;提出关系模式等价的定义、及其具有自反性、传递性和对称性的性质 ;提出关系模式描述文件这一元数据的定义和生成规则、并给出其 DTD;最后给出并实现了算法 相似文献
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Saranadasa H 《Drug development and industrial pharmacy》2000,26(11):1213-1216
A formula for calculating the equivalent relative standard deviation (RSD) for different sample sizes other than the Office of Generic Drugs (OGD) draft guidance was derived. These critical values vary with the population RSD and the sample size and guarantee the same confidence of passing a batch similar to the OGD blend uniformity test. Simulation results showed that the normal approximations give very close results to the simulation results. An assessment of the proposed OGD blend uniformity criteria against the first-stage USP content uniformity (CU) criteria for tablets was also made. 相似文献
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High power switch is one of the most important components in pulsed power technology. The RSD (Reversely Switched Dynistor), turned on by a thin layer of an electron-hole plasma, is a high power semiconductor switch. In this study, the RSD turn-on conditions were investigated by numerical analysis and device simulation as well as the experiments conducted to validate the turn-on conditions. A design of a triggering high-voltage RSD is presented based on a saturable transformer. 相似文献
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H. Karutz W. B. Kraetzig 《International journal for numerical methods in engineering》2002,53(2):375-391
In the present paper, we derive an efficient data structure for the organization of the nodes in the coupled finite element/element‐free Galerkin method. With respect to its implementation, we compare various approaches of recursive spatial discretizations that facilitate most flexible handling of the nodes. The goal of the paper is to refine the implementation issues of the data structure which is fundamental to the element‐free Galerkin method and thus to speed‐up this otherwise computationally rather expensive meshfree method. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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《Drug development and industrial pharmacy》2013,39(1):37-43
The relative SD is a measure that is now in common use in the pharmaceutical industry, for example, in pharmaceutical development and analytical chemistry, pharmacology, and quality control. This article comments on the usual point estimate of the true value; presents seven interval estimation methods, easily implemented on a desktop computer; and compares their individual merits and drawbacks. Finally, the question of determining an adequate sample size is addressed, and a possible solution is indicated. 相似文献
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Catrin S. Günther Adam J. MatichKen B. Marsh Laura Nicolau 《Food research international (Ottawa, Ont.)》2011,44(5):1331-1338
Minor fruit volatiles are likely to be missed using sampling techniques optimized for the extraction of major compounds. This can be a disadvantage if these minor compounds contribute to characteristic fruit flavors. In this comparative study, headspace solid-phase microextraction (HS-SPME) and dynamic headspace sampling (DHS) parameters were systematically optimized to ensure highest extraction yields of methylsulfanyl-volatiles from kiwifruit tissue samples. A significant “salting-out” effect from the fruit matrix was observed using both sampling techniques after (NH4)2SO4 saturation. HS-SPME at optimized conditions (polydimethylsiloxane-divinylbenzene-coated fiber, (NH4)2SO4 saturation, 5 min equilibration and 20 min sampling at 40 °C) was faster and more convenient to use than DHS for qualitative purposes. Despite this, the qualitative and quantitative methylsulfanyl-volatile profile was improved using optimized DHS ((NH4)2SO4 saturation; sampling time 20 h; flow rate 30 mL min− 1) compared with HS-SPME, making this the more sensitive and preferred method for quantitative studies. The optimization strategies for increasing headspace extraction yields of trace compounds presented in this study can easily be applied to tissue samples from other fruit. 相似文献
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风功率预测能够为电网规划设计提供一项重要依据,因而研究如何精准进行风功率预测对保证电网的安全稳定运行具有重要意义。针对正则化系数C和核参数λ作为模型参数,对核极限学习机预测模型精度产生影响的问题,提出了运用PSO对核极限学习机进行参数优化的PSO-KELM预测方法。将正则化系数C和核参数λ作为优化对象,利用PSO方法对参数共同优化,建立PSO-KELM风功率预测模型。对3组实测数据进行了实验研究,引入均方根误差、平均绝对误差和相对标准差作为评价指标,结果显示该方法预测误差好于直接应用KELM方法,并进一步将结果与常用的SVM以及PSO-SVM方法进行了比较。结果表明,PSO-KELM方法具有更好的预测精度和稳定性,能够作为提高风功率预测准确性以及风电并网安全性方面的一种科学有效的参考。 相似文献