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41.
Assume that the probability density function for the lifetime of a newly designed product has the form: [H(t)/Q()] exp{–H(t)/Q()}. The Exponential(), Rayleigh, WeibullW(, ) and Pareto pdf's are special cases.Q() will be assumed to have an inverse Gamma prior. Assume thatm independent products are to be tested with replacement. A Bayesian Sequential Reliability Demonstration Testing plan is used to eigher accept the product and start formal production, or reject the product for reengineering. The test criterion is the intersection of two goals, a minimal goal to begin production and a mature product goal. The exact values of various risks and the distribution of total number of failures are evaluated. Based on a result about a Poisson process, the expected stopping time for the exponential failure time is also found. Included in these risks and expected stopping times are frequentist versions, thereof, so that the results also provide frequentist answers for a class of interesting stopping rules.This research was supported by NSF grants DMS-8703620 and DMS-8923071, and forms part of the Ph.D. Thesis of the first author, the development of which was supported in part by a David Ross grant at Purdue University. The authors thank the editors and a referee for insightful comments and suggestions. 相似文献
42.
The High Temperature Superconductors are characterized by a very anisotropical structure and by typical arrangements of Cu- and O-atoms within CuO2-planes. In studying the electronic structure of these compounds there is a strong demand for high resolution valence band spectroscopy. Using an electron probe microanalyzer we study the X-ray emission of O-Kga and Cu-L emerging from polycrystalline YBa2Cu3O7 and Tl2Ba2Ca2Cu3O10. The O-K emission band is analyzed using a chlinochlore crystal in (001) orientation (2d = 28.4 Å). For the Cu-L emission band we use a beryl crystal in (10¯10) orientation (2d = 15.9 Å). Furthermore, orientation dependent X-ray emission spectroscopy of single-crystalline YBa2Cu3O7 and Tl2Ba2Ca1Cu2O8 specimens was performed. We present the partial O-K spectra which represent the O-2p ( = x, y, z) electronic densities of states of the valence band and compare them with calculated data. 相似文献
43.
T. Rampke W. -D. Emmerich E. Post L. Giersig 《Journal of Thermal Analysis and Calorimetry》1996,47(2):633-642
The decomposition reactions of polystyrene, phenolic resin and a protective undercoating material for automobiles which contains PVC were tested using a new type of thermal analysis — mass spectrometry coupling system for measurements to 1500C or 2000C, which is based on the principle of a two-step skimmer orifice system. The results will be presented, with particular emphasis on the detection sensitivity of the new system for the products of decomposition.The capability of this coupling system to detect even heavy metals such as lead and silver in the waste gases from decomposition or after evaporation at high temperatures will also be demonstrated. 相似文献
44.
Céline Jousse-KarinthiFatima Zouhiri Jacqueline MahuteauDidier Desmaële 《Tetrahedron》2003,59(12):2093-2099
The palladium-catalyzed condensation of a variety of active methylene compounds with methyl 6-acetoxymethyl-hepta-2,6-dienoate was investigated. The six-membered adducts resulting from a η3 palladium complex alkylation-Michael addition sequence were obtained with moderate to good yields. In some cases, further evolution of the primary adduct was observed. The process has been expanded to access nitrogen heterocycles by using sodium p-toluenesulfonamide as the nucleophilic partner. 相似文献
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有机溶剂对镧和钇ICP光谱信号的增敏机理研究 总被引:2,自引:0,他引:2
本文考察了有机溶剂(乙酸丁酯)及有机试剂(PMBP)引入ICP-AES对稀土元素镧和钇光谱信号的影响。实验结果表明,有机溶剂的引入明显增大了待测物的传质效率,从而导致分析灵敏度的改善。与水相相比,有机相的引入对ICP激发温度未产生明显影响,但使线对强度比(LogI^ /I)增强,有利于待测物的电离。 相似文献
48.
用ICP研究鹿科动物骨质疏松症的微量元素特征 总被引:1,自引:0,他引:1
鹿科动物的骨质疏松症是近几年出现的一种疾病,它影响鹿的生长发育和繁殖,病重者死亡。我们采集梅花鹿和白唇鹿的毛,血样,用低温灰化方法和温法消解处理样品,用ICP分析了毛,血清中微量元素的含量。病梅花鹿毛样中Mg,Al,Ca,Ti,Fe,Cu,Zn的含量比正常组高,Ti,Cu,Zn的偏差率大于15%,而Si,Mn,P,P,Ag,Ba,La,Ce,Pb比正常组低,V,Ag,Ba,La,Ce,Pb存在... 相似文献
49.
在理学3064X荧光仪上采用十八烷基马来酸(OHM)晶体作为色散单元,通过改造电路,调整晶体倾角,获得对碳分析的良好线性,在流气正比计数器(FPC)窗膜分别为5μm和0.6μm条件下,碳元素的峰背比分别达到38.91和54.04。作者分析了白口铸铁和碳化硅中的碳,结果表明在理学3064X荧光仪上定量分析碳是可行了,具有快速、简便、准确、多元素同时分析的特点,可用于日常分析 相似文献
50.
本工作通过比较端视与侧视ICP的分析性能,研究了端视ICP系统对稀土元素的分析特性。高频发生器输出功率与载气流量对端视与侧视ICP激发特性的影响没有明显差异,取光方式的不同是二者分析性能差异的根本原因。端视ICP由于取光时避开了产生连续背景的环形热区和截取了整个中心通道的光谱,其背景减小,谱线强度增强,获得较好的测定下限。对14种稀土元素测定下限的比较表明:端视ICP比铡视ICP下降10-30倍。 相似文献