Modeling Unobserved Heterogeneity Using Latent Profile Analysis: A Monte Carlo Simulation

Latent profile analysis (LPA) has become a popular statistical method for modeling unobserved population heterogeneity in cross-sectionally sampled data, but very few empirical studies have examined the question of how well enumeration indexes accurately identify the correct number of latent profiles present. This Monte Carlo simulation study examined the ability of several classes of enumeration indexes to correctly identify the number of latent population profiles present under 3 different research design conditions: sample size, the number of observed variables used for LPA, and the separation distance among the latent profiles measured in Mahalanobis D units. Results showed that, for the homogeneous population (i.e., the population has k = 1 latent profile) conditions, many of the enumeration indexes used in LPA were able to correctly identify the single latent profile if variances and covariances were freely estimated. However, for a heterogeneous population (i.e., the population has k = 3 distinct latent profiles), the correct identification rate for the enumeration indexes in the k = 3 latent profile conditions was typically very low. These results are compared with the previous cross-sectional mixture modeling studies, and the limitations of this study, as well as future cross-sectional mixture modeling and enumeration index research possibilities, are discussed.     

基于P3D的飞机飞行航迹数据回放演示程序设计

在传统的飞机飞控系统教学中,通常以曲线形式显示飞机的姿态、舵面等数据,直观性不强,学生的学习难度较大,针对这一问题,利用虚拟仿真技术,基于P3D平台,设计了飞机飞行航迹数据回放演示程序,能够直观地将飞机的飞行姿态、舵面等数据以真实形象的三维场景表现出来,降低了学生的抽象思维难度,提高了学习效率。     

基于调制随机共振大频率信号检测的仿真

研究了调制随机共振利用傅里叶变换的频移特性解决大频率输入信号（频率大于1）的检测问题。首先利用调制系统将信号的频率转换为产生随机共振适宜的频率,再利用随机共振系统中噪声和信号的协同作用,实现强噪声背景下大频率周期信号的检测。     

基于仿真技术的汽车能耗与质量关系的研究

为了研究汽车能耗和汽车质量之间的关系,本文首先建立了仿真的目标,即以内燃机驱动、混合动力驱动和氢燃料驱动的车辆为研究对象,对这3种不同的研究对象又分别选取了3种类型的车辆。根据仿真目标建立了汽车仿真模型,并在MATLAB/SIMULINK环境下实现。仿真结果表明,汽车能耗随着质量减少而减少,驱动方式、车型、传动等因素对油耗也有很大的影响。     

野外地质实习虚拟仿真实验教学平台建设与思考

野外实习是培养合格地质人才的重要环节和专业特色,对培养学生兴趣、巩固专业知识、提高实践能力等有着不可替代的作用。然而传统野外地质教学实习中存在效率低、成本高、互动性和共享性差等问题,虚拟仿真教学很好地弥补了此缺陷。通过以汉中梁山野外地质实习基地为例,介绍了长安大学地质学类专业野外地质实习的发展现状,实习目的和任务,分析了传统野外地质实习存在的问题,探讨了汉中梁山野外地质实习虚拟仿真教学平台建设的思路和拟解决的关键问题。     

基于交通仿真的拓宽交叉口服务通行能力研究

采用延误分析法研究路口拓宽后信号交叉口的服务通行能力，利用交通仿真软件VISSIM对拓宽交叉口进行交通流微观仿真，从而得到拓宽车道的延误曲线，建立了基于交通仿真的拓宽交叉口延误-流量模型．依据该模型提出了拓宽左转车道的基本服务通行能力的建议值，并给出了各修正系数以及实用服务通行能力的确定方法．     

EFL teachers’ perceptions of English language policy at the elementary level in Taiwan

Due in large part to the trends towards economic globalization, English has become the most widely disseminated and ubiquitous international language. The purpose of the study was to investigate what Taiwan’s EFL teachers at the elementary level believe about the policy of English as a compulsory subject and how they perceive the benefits and obstacles of the policy’s implementation. Ten elementary English teachers in Tainan City and its suburban areas participated in this study. Data were collected through teachers’ interviews, classroom observation and document analysis. Results found that all ten teachers agreed with the policy for English as a compulsory subject at the elementary level. They observed both positive and negative sides of this top‐down policy. Classroom observation and interview data revealed that EFL teachers had to plan their English classes with the constraints on a large class of students with mixed levels of proficiency, limited teaching hours and resources. Parents’ expectations of and attitudes towards English learning also became an obstacle.     

辅助教学平台在“光纤通信”课程中的应用

针对"光纤通信"课程讲授中"学生难学,教师难讲"的弊端,建立了基于光纤相关特性的辅助教学仿真平台。仿真平台的设计利用MATLAB的可视化用户界面,完成了对光纤通信性能参数的测量、光纤相关特性展示、光纤通信器件展示。结果表明结合仿真软件的教学手段有助于学生理解和掌握课程内容。     

脉动式CVT连杆机构的运动规律研究

本文对曲柄摇块式脉动无级变速的传动机构进行了运动分析,从运动学原理对机构进行深入研究,得出该机构的最佳参数,减小脉动及动载荷,降低功率损耗,进而改善其运动及动力性能,     

iSIM模式在普外临床实习教学中的应用

为检验优化医学模拟诊疗模式（iSIM）应用于普外科临床带教过程的应用效果,选取2020年6月—2021年6月在苏州大学附属第二医院实习的卓越班“5+3”实习医生共30人为主要对象,按学号随机分为两组,实验组15人,对照组15人。实验组采用iSIM模式联合标准化病人进行临床实习带教,对照组采用传统的临床带教方式。1年实习期结束后,对两组见习生的理论知识、实际操作能力进行考核,另外对实习医生的教学模式、带教效果进行评价。实验组理论考核评分与操作考核评分均显著高于对照组,差异具有统计学意义（P<0.05）。iSIM模拟教学方法结合社会化标准病人在普外科临床实习带教中,显著提高了临床教学的考核成绩,同时提高了实习医生的临床思维、实践操作能力、团队协作能力和自我反馈能力,值得推广。