Modeling Predictors of Latent Classes in Regression Mixture Models

The purpose of this study is to provide guidance on a process for including latent class predictors in regression mixture models. We first examine the performance of current practice for using the 1-step and 3-step approaches where the direct covariate effect on the outcome is omitted. None of the approaches show adequate estimates of model parameters. Given that Step 1 of the 3-step approach shows adequate results in class enumeration, we suggest using an alternative approach: (a) decide the number of latent classes without predictors of latent classes, and (b) bring the latent class predictors into the model with the inclusion of hypothesized direct covariate effects. Our simulations show that this approach leads to good estimates for all model parameters. The proposed approach is demonstrated by using empirical data to examine the differential effects of family resources on students’ academic achievement outcome. Implications of the study are discussed.     

Measurement Invariance Testing with Many Groups: A Comparison of Five Approaches

With the increasing use of international survey data especially in cross-cultural and multinational studies, establishing measurement invariance (MI) across a large number of groups in a study is essential. Testing MI over many groups is methodologically challenging, however. We identified 5 methods for MI testing across many groups (multiple group confirmatory factor analysis, multilevel confirmatory factor analysis, multilevel factor mixture modeling, Bayesian approximate MI testing, and alignment optimization) and explicated the similarities and differences of these approaches in terms of their conceptual models and statistical procedures. A Monte Carlo study was conducted to investigate the efficacy of the 5 methods in detecting measurement noninvariance across many groups using various fit criteria. Generally, the 5 methods showed reasonable performance in identifying the level of invariance if an appropriate fit criterion was used (e.g., Bayesian information criteron with multilevel factor mixture modeling). Finally, general guidelines in selecting an appropriate method are provided.     

油品顺序输送混油量控制方法初探

本文根据巴陵石化油品顺序输送管道的实际运行情况,从隔断介质、首尾站工艺条件以及环境温度等方面分析了影响混油量的因素,提出了减少混油量的控制方法。     

开罗夜未眠

During the last few years, my neighborhood in Cairo has experienced such an influxof refugees from the Iraq war that longtime residents have begun, with a mixture of     

Identifying Unobserved Hazard Functions in Discrete-Time Survival Mixture Analysis

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.     

天台宗伦理思想的现代阐释--从动物权利论伦理到生态伦理

佛教天台宗含有丰富的伦理思想，智顗的“十界互具”本质上是动物权利论伦理观；湛然的“无情有性”说本质上是生态伦理观。当我们把以辛格、雷根为代表的动物权利论伦理和以罗尔斯顿为代表的生态伦理与智顗和湛然的伦理观同放在人类思想发展史的纵轴线上加以比较考察时，不难发现，它们都属于非人类中心论(或泛主体论)伦理观。并且后者方佛是前者的回复，是高级的回复，正好体现了否定之否定规律。     

关于阶级社会里是否存在民族融合的思考

阶级社会里是否存在民族融合 ,历史上有两种不同的观点 :存在论与不存在论。二者中存在论是值得肯定的 ,但以往的存在论又过于绝对化。阶级社会里的民族融合并不等于共产主义社会的民族融合 ,实际上在民族发展的不同阶段 ,民族融合表现形式各不相同。在阶级社会里由于历史的局限性 ,它以特殊的形式———民族同化体现出来。民族同化是民族处于低级发展阶段对民族融合的历史表现形式和基本特征 ,蕴含着民族融合的逻辑旨归 ;民族融合是民族同化的逻辑结果 ,两者是历史与逻辑的辩证统一。     

应用线性光谱混合模型快速评价土地退化的方法研究

利用不同时相的ＴＭ 数据,采用线性光谱混合模型的方法,对内蒙古中西部半干旱地区的土地退化进行了以快速评价为目标的研究．在选用沙地、裸地、农耕地、牧草地作为基本组分的基础上,提取了反映土地退化的定量指标．相比其他遥感定量提取的方法,在干旱、半干旱地区进行土地快速分析和评价上,线性光谱混合模型分析不失为一种好的选择     

冷轧煤气加压站混合煤气配比调节系统改造

分析了冷轧煤气加压站混合煤气配比调节系统原设计方案中在在的问题,并提出了相应的解决方法,改进控制方案。     

金属-有机骨架K-MOF的合成及性质表征

以硝酸钾为中心金属离子,1,4-苯二甲酸（H2BDC）、1,3,5-苯三甲酸（H3BTC）及混合物（H2BDC+H3BTC）为有机配体,N,N-二甲基甲酰胺（DMF）为溶剂,采用溶剂热法合成三种K-MOF晶体。通过X射线粉末衍射(PXRD)、红外光谱(FT-IR)、扫描电镜（SEM）及热重(TG)等方法对样品进行表征,考察不同配体对K-MOF的影响。结果表明:K+与H2BDC配位得到的长条状晶体,与H3BTC配位得到粉末状晶体,H2BDC与H3BTC同时存在时,K+优先与H3BTC配位得到粉末状晶体。K-MOF具有良好的热稳定性,在350℃内能保持结构的热稳定性。