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41.
介绍了国家标准GB 7000.217-2008/IEC 60598-2-17:1984+A2:1990《灯具第2-17部分:特殊要求舞台灯光、电视、电影及摄影场所(室内外)用灯具》的特殊要求,阐述了对该标准特殊要求条文的理解和解释以及其对LED舞台灯具的适用性,以帮助舞台灯具行业的设计、生产、检验和使用人员正确理解和应用舞台灯具国家标准。 相似文献
42.
《Water research》1986,20(10):1273-1279
The methanogenic phase of anaerobic digestion is often considered to be the most sensitive step in the overall process. Chloroform, a model industrial toxicant was assayed with methane fermentation, acetate enrichment cultures. Commonly, microbial toxicity response studies have observed the toxicity response over a relatively short time span, on the order of a few hours or days. In addition, cessation of observed cell function has often been assumed to be equated with death of the cells. The purpose of this study was to determine the toxicity response under various conditions over prolonged periods, on the order of months, with major emphasis on the recovery pattern. The following parameters were observed: concentration of toxicant, solids retention time, biomass concentration, toxicant exposure time, cell age, toxicant administration pattern and temperature.The methane fermentation culture was able to acclimate to the presence of chloroform while fermenting acetate to methane. Inhibition of unacclimated cultures was noted at 0.5 mg l−1, but with acclimation 15 mg l−1 could be tolerated. There was a clear correlation between dose and inhibition. Recovery from inhibition was a function of SRT and biomass concentration. Younger cells were more resistant than older cells. The duration of chloroform exposure was directly related to the degree of residual inhibition. Reduced temperature delayed recovery of gas production from slug doses of chloroform. Radio tagged chloroform studies indicated that recovery of methane production occurred due to acclimation of the methanogens to the presence of chloroform and not from the disappearance of chloroform by microbial degradation. 相似文献
43.
When the reactor coolant pump (RCP) was tested on test bench, the vibration amplitude was too large. The vibration exceeded the limit of specification. The frequency in spectrum of RCP vibration was mainly in low frequency range. The vibration characteristics of RCP were analyzed by finite element method. The cause of vibration from bearing and rotor was excluded by comparing the vibration characteristics and the spectrum. It was proposed that the whole test bench should be included in the vibration analysis of RCP. Considering RCP, test loop and test bench as a whole, the vibration characteristics were analyzed. By combining the data from knock test, it is concluded that the wide-band of pressure fluctuation in test loop excites the natural frequency of test bench. This conclusion was verified by low-speed operation test. On this basis modifications were proposed such as adding energy absorption damper, starting buffer tank in advance and adding vibration filter. The vibration of RCP was attenuated obviously after test restarting. 相似文献
44.
美国动能拦截弹红外成像导引头的发展分析 总被引:3,自引:0,他引:3
概述了美国弹道导弹防御系统的核心要求和红外制导型动能拦截弹在该系统中的重要地位.介绍了美国正在部署、试验和研制的几种大气层外和大气层内弹道导弹防御动能拦截器的红外成像导引头的作战使命、拦截目标、任务特性、设计方案和发展现状,简要分析了美国正在和即将部署的动能拦截弹难以有效地对付不断发展的弹道导弹威胁的突防对抗措施的弱点,概述了近年来发展的满足多对多拦截需求的多拦截弹头(MKV)的红外成像导引头的发展现状,并介绍了近年来重点探索的旨在提高对小间距物体的区辨能力和对弹道导弹弹头的识别能力的新概念红外成像导引头,包括多波段红外成像导引头和主/被动红外成像导引头. 相似文献
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L.D. Scintilla L. Tricarico M. Brandizzi A.A. Satriano 《Journal of Materials Processing Technology》2010,210(15):2206-2214
Laser welding process using a Nd:YAG laser of maximum power of 2 kW was investigated and reported. Magnesium alloy AZ31 sheets with thickness of 3.3 mm have been butt welded with Helium and Argon used as shielding gases. The effect of processing parameters including laser power, welding speed, focal point position, nozzle configuration and protection gas flow was researched. Microstructure and mechanical properties of butt joints welded without filler were studied using optical microscopy, morphological analysis and mechanical tests (tensile, hardness). The first phase of experimental tests consisted in penetration tests (bead on plate) with the aim of identify the range of input parameters. In the second phase butt welding tests were performed in order to determine the optimal conditions. Tensile tests were realized using extensometers and an optical system based on digital image correlation techniques for acquisition and analysis of local deformation. Static tensile tests revealed an increase in the yield strength of all welded specimen in relation to the not welded material. Morphological analysis and mechanical characterization showed a threshold of heat input value below which, even when there is sufficient irradiance, the ultimate tensile strength and the elongation to fracture of the joint decade heavily. The local strain analysis revealed that the fracture occurs due to localization of deformation on weld bead as a result of defects on the surface of the bead. Metallographic analysis of cross-sections did not show defects like porosity, inclusions and cracks, within the weld bead. 相似文献
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工厂企业供电系统谐波治理研究 总被引:1,自引:0,他引:1
指出工厂企业具有低压配电系统普遍具有的特点,其电能质量最突出和普遍的问题是电网谐波。阐述了谐波的危害并对其进行了分析,指出主要的谐波源为各种电机拖动中的电力电子装置,可以通过装设无源滤波器和有源滤波器进行治理。提出了一种模块化配置方案,易于扩容和安装,且具有机柜式有源滤波器所不具备的优点。 相似文献
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