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21.
In latent growth modeling, measurement invariance across groups has received little attention. Considering that a group difference is commonly of interest in social science, a Monte Carlo study explored the performance of multigroup second-order latent growth modeling (MSLGM) in testing measurement invariance. True positive and false positive rates in detecting noninvariance across groups in addition to bias estimates of major MSLGM parameters were investigated. Simulation results support the suitability of MSLGM for measurement invariance testing when either forward or iterative likelihood ratio procedure is applied. 相似文献
22.
1 Introduction It is i mportant to study polymerization mechanisminpolymerization engineering. Obtaining kinetic data isthe key step for establishing polymerization mechanismand understanding elementary reactions . The kineticdata contains two groups of data ,i.e.,the rate andreaction order .The rate ,especially the rate constant ,is i mportant and to be esti mated assuming that the or-der of the reactionis known.Furthermore ,esti mationof rate constants for polymerization is an active anddif… 相似文献
23.
本文作出了北京谱仪主漂移室的径迹拟合程序包,阐述了该程序包的原理,并运用e~+e~-→i/Ψ→μ~+μ~-蒙得卡罗事例进行检验,动量分辨符合要求.该程序包目前已用于北京谱仪J/Ψ物理的研究之中. 相似文献
24.
谢林毅戴贵龙陈雪淇庄莹 《福建工程学院学报》2020,(1):69-74
采用蒙特卡洛射线踪迹法,ProE和TracePro软件技术,模拟分析了多棱台与一次抛物面、复合抛物面二次聚集器与一次抛物面两级聚集器的太阳光聚集传输特性。通过对比,发现多棱台二次聚集器的几何聚光比为1.4左右(约为复合抛物面聚集器的70%)。多棱台与一次抛物面、复合抛物面二次聚集器与一次抛物面两级聚集器圆筒侧壁和底面的太阳能流密度分布图像相当(沿圆周方向,复合抛物面两级聚集器相对比较平滑)。结论为反射二次聚集器技术发展提供理论依据。 相似文献
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SHI Jian JIA Yu-fu DONG Tian-lin LI Jiang 《重庆大学学报(英文版)》2006,5(3):143-151
1 Introduction a At present, the research work on wireless sensor networks is based on the assumption that the energy of a sensor node is provided by the battery and can not be regenerated. The lifetime of the node is limited and ephemeral. Hence research… 相似文献
27.
Opticalcoherencetomography (OCT)wasorigi nallydevelopedforimagingintransparenttissue[1] .Since1 995 ,OCThasbeenadvancedtoimagefromophthal mologytonontransparenttissuewithahighimagingres olution[2 ,3 ] .OCTdemonstratesitsgreatestpotentialinsituationswhereconventionalbiopsyiseitherdangerousorineffective[4] .Becauseofthecomplexityofthelightpropagationinnontransparenttissue,theapplicationofOCTinhighlyscatteringbiologicaltissuesuchasskintis suearenotoptimistic.Yadlowsky[5] explainedthatmul tip… 相似文献
28.
MplusAutomation is a package for R that facilitates complex latent variable analyses in Mplus involving comparisons among many models and parameters. More specifically, MplusAutomation provides tools to accomplish 3 objectives: to create and manage Mplus syntax for groups of related models; to automate the estimation of many models; and to extract, aggregate, and compare fit statistics, parameter estimates, and ancillary model outputs. We provide an introduction to the package using applied examples including a large-scale simulation study. By reducing the effort required for large-scale studies, a broad goal of MplusAutomation is to support methodological developments in structural equation modeling using Mplus. 相似文献
29.
This Monte Carlo simulation adds to the growing body of enumeration index performance research in continuous response variable mixture models by addressing the issue of the performance of these indexes in discrete-time survival mixture analysis (DTSMA) models. Results showed that although all enumeration indexes performed very well in identifying a homogeneous DTSMA model (i.e., k = 1 hazard function in the sample data), the findings also showed that the enumeration indexes performed poorly in identifying the correct number of unobserved hazard functions present in a heterogeneous (i.e., k = 3) DTSMA model. More important, the performance of the enumeration indexes for the heterogeneous DTSMA models did not improve as the sample size, the effect of time-invariant covariates, or adjacent hazard function separation distance increased, which is inconsistent with some previous Monte Carlo simulation results. The limitations of this Monte Carlo simulation study and future empirical investigation possibilities are both discussed. 相似文献
30.
基于蒙特卡罗模拟的不同聚合温度下的丙烯聚合动力学研究 总被引:4,自引:0,他引:4
在不考虑其他杂质参与聚合反应的情况下,并基于已有对丙烯聚合反应过程的普适化认识,提出了一个普适的丙烯聚合反应机理(基元反应).在已有的丙烯聚合反应机理基础上,为了证实该聚合反应过程总活性基是否满足“稳态假定”以及考察聚合反应温度对聚合过程的影响,采用蒙特卡罗模拟方法研究了传统Ziegler-Natta催化剂催化下的丙烯聚合动力学.模拟得到的总活性基数目在丙烯聚合初期快速增加到峰值,然后随聚合反应的进行保持恒定,证实了丙烯聚合过程中总活性基符合稳态假定.同时,模拟得到了聚合温度对丙烯聚合过程的转化率、分子量的影响.模拟结果表明:在聚合过程中,丙烯单体的消耗速率随聚合温度升高而增加;不同聚合温度下的数均聚合度峰值相同,但随温度增加,数均聚合度峰值来得早;随聚合温度增加,数均分子量减少,分子量分布变宽. 相似文献