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排序方式: 共有294条查询结果,搜索用时 15 毫秒
31.
提出了一种新型同轴慢波系统——紧密缠绕螺旋线介质棒加载盘荷波导,解析推导了其色散方程和耦合阻抗的表达式,并给出了数值计算结果。结果表明:新型导波结构作为行波管的慢波系统,不但可使行波管具有相对较宽的频带,又可使其具有较高的耦合阻抗。 相似文献
32.
论述了一种成功运用于122cm背投式彩色投影电视机阴极射线管(CRT)中的磁聚焦电子枪。该枪采用了预聚焦发射系统和磁聚焦主透镜构成的双聚焦系统。经测试发现,当阴极电流为0.5~1.0mA时,其上屏束斑直径仅为0.065~0.080mm。 相似文献
33.
本文简要叙述了红磷形成烟雾的过程及性质,并用 Mie 理论计算了不同温度条件下红磷烟雾对10.6μm 激光的质量消化系数α_c 和质量散射系数α。理论计算与实验测得的α_c 有较好的一致性。 相似文献
34.
本文应用弯曲光波导耙合系统中的广义耦合模方程来分析弯曲单模弱导光纤耦合结构,导出了在模式间的耦合系数、非正交系数及耦合功率式,与经典的耦合模理论相比较,本文提出的公式显得更精确,同时与实验结果一致。 相似文献
35.
In regression analysis, it is assumed that the response (or dependent variable) distribution is Normal, and errors are homoscedastic and uncorrelated. However, in practice, these assumptions are rarely satisfied by a real data set. To stabilize the heteroscedastic response variance, generally, log-transformation is suggested. Consequently, the response variable distribution approaches nearer to the Normal distribution. As a result, the model fit of the data is improved. Practically, a proper (seems to be suitable) transformation may not always stabilize the variance, and the response distribution may not reduce to Normal distribution. The present article assumes that the response distribution is log-normal with compound autocorrelated errors. Under these situations, estimation and testing of hypotheses regarding regression parameters have been derived. From a set of reduced data, we have derived the best linear unbiased estimators of all the regression coefficients, except the intercept which is often unimportant in practice. Unknown correlation parameters have been estimated. In this connection, we have derived a test rule for testing any set of linear hypotheses of the unknown regression coefficients. In addition, we have developed the confidence ellipsoids of a set of estimable functions of regression coefficients. For the fitted regression equation, an index of fit has been proposed. A simulated study illustrates the results derived in this report. 相似文献
36.
介绍了一种激光束空间能量分布的快速测量新方法,该方法采用电荷耦合器件(CCD)作为探测器,并采用微型计算机进行数据采集和处理,具有自动、实时、准确、直观等优点。文中还给出了He-Ne激光束(0.6328μm)的实验结果。 相似文献
37.
Composite quantile regression models have been shown to be effective techniques in improving the prediction accuracy [H. Zou and M. Yuan, Composite quantile regression and the oracle model selection theory, Ann. Statist. 36 (2008), pp. 1108–1126; J. Bradic, J. Fan, and W. Wang, Penalized composite quasi-likelihood for ultrahighdimensional variable selection, J. R. Stat. Soc. Ser. B 73 (2011), pp. 325–349; Z. Zhao and Z. Xiao, Efficient regressions via optimally combining quantile information, Econometric Theory 30(06) (2014), pp. 1272–1314]. This paper studies composite Tobit quantile regression (TQReg) from a Bayesian perspective. A simple and efficient MCMC-based computation method is derived for posterior inference using a mixture of an exponential and a scaled normal distribution of the skewed Laplace distribution. The approach is illustrated via simulation studies and a real data set. Results show that combine information across different quantiles can provide a useful method in efficient statistical estimation. This is the first work to discuss composite TQReg from a Bayesian perspective. 相似文献
38.
39.
Efficient composite heuristics for total flowtime minimization in permutation flow shops 总被引:2,自引:0,他引:2
In this paper, permutation flow shops with total flowtime minimization are considered. General flowtime computing (GFC) is presented to accelerate flowtime computation. A newly generated schedule is divided into an unchanged subsequence and a changed part. GFC computes total flowtime of a schedule by inheriting temporal parameters from its parent in the unchanged part and computes only those of the changed part. Iterative methods and LR (developed by Liu J, Reeves, CR. Constructive and composite heuristic solutions to theP∥ΣCi scheduling problem, European Journal of Operational Research 2001; 132:439–52) are evaluated and compared as solution improvement phase and index development phase. Three composite heuristics are proposed in this paper by integrating forward pair-wise exchange-restart (FPE-R) and FPE with an effective iterative method. Computational results show that the proposed three outperform the best existing three composite heuristics in effectiveness and two of them are much faster than the existing ones. 相似文献
40.
刘凤鳌 《绍兴文理学院学报》1994,(6)
本文摒弃了气体分子运动论中诸多不必要的简化假设,引入了分子束矢量的概念。应用分子束矢量解决问题简捷严谨并能避免出现“1/6与1/4”“2”等迷惑问题。 相似文献