旋转二次曲面透镜基点和基面的位置确定

在光学仪器中,非球面透镜具有一定的实用价值,故对旋转二次曲面透镜光学性质的研究将有重要意义．根据等效光学系统理论和旋转二次曲面折射的焦距公式,并考虑了透镜两曲面的不同形状及不同曲率,导出了旋转二次曲面透镜的主距公式和焦距公式,统称为旋转二次曲面的基点位置公式．这些公式具有一般性,该文进行了分类讨论,最后给出了应用实例     

Decomposing trait and state variability in general and specific subjective task value beliefs

Expectancy-value researchers have theorized about the extent to which subjective task value components are more trait-like or more state-like. Using a bifactor representation of subjective task value data, the current study aimed to examine the degree of trait-state variation in general subjective task value, specific attainment value, specific intrinsic value, and specific utility value. The relations of both between and within components of the subjective task value constructs with academic self-efficacy beliefs were also examined. Results indicate that, in an undergraduate life science learning context (n = 169), the general subjective task value factor was the most trait-like of the subjective task value constructs. With respect to specific value beliefs, attainment value was composed of nearly equal amounts of trait and state variation, intrinsic value was composed of the largest amount of trait variation, and utility value exhibited the most state-like variation. Additionally, findings suggest that trait-like and state-like general subjective task value, trait-like specific intrinsic value, and state-like attainment value were positively associated with self-efficacy. Finally, we propose a model of trait- state dynamics in subjective task value.     

Seeing the Forest and the Trees: Comparison of Two IRTree Models to Investigate the Impact of Full Versus Endpoint-Only Response Option Labeling

In this study, we examined the results and interpretations produced from two different IRTree models—one using paths consisting of only dichotomous decisions, and one using paths consisting of both dichotomous and polytomous decisions. We used data from two versions of an impulsivity measure. In the first version, all the response options had labels; in the second version, only the endpoints were labeled. Based on past research, we hypothesized that the endpoints would be selected more frequently in the endpoint-only labeled condition, and the midpoint response option would be selected more frequently in the fully labeled condition. Results from the two models (dichotomous and polytomous) were similar and indicated that our hypotheses were partially supported—specifically, there was no consistent pattern in terms of which condition saw a higher frequency of midpoint response selection. However, our hypotheses regarding extreme responding in the endpoint-only labeling condition were supported.     

Parameter Estimation Accuracy of the Effort-Moderated Item Response Theory Model Under Multiple Assumption Violations

As low-stakes testing contexts increase, low test-taking effort may serve as a serious validity threat. One common solution to this problem is to identify noneffortful responses and treat them as missing during parameter estimation via the effort-moderated item response theory (EM-IRT) model. Although this model has been shown to outperform traditional IRT models (e.g., two-parameter logistic [2PL]) in parameter estimation under simulated conditions, prior research has failed to examine its performance under violations to the model’s assumptions. Therefore, the objective of this simulation study was to examine item and mean ability parameter recovery when violating the assumptions that noneffortful responding occurs randomly (Assumption 1) and is unrelated to the underlying ability of examinees (Assumption 2). Results demonstrated that, across conditions, the EM-IRT model provided robust item parameter estimates to violations of Assumption 1. However, bias values greater than 0.20 SDs were observed for the EM-IRT model when violating Assumption 2; nonetheless, these values were still lower than the 2PL model. In terms of mean ability estimates, model results indicated equal performance between the EM-IRT and 2PL models across conditions. Across both models, mean ability estimates were found to be biased by more than 0.25 SDs when violating Assumption 2. However, our accompanying empirical study suggested that this biasing occurred under extreme conditions that may not be present in some operational settings. Overall, these results suggest that the EM-IRT model provides superior item and equal mean ability parameter estimates in the presence of model violations under realistic conditions when compared with the 2PL model.     

玉雕专业职业教育的探索

结合教学实际,以中国玉石文化的发展为切入口,对玉文化观念、玉的发展和繁荣进行了探讨,进而对玉雕造型能力的教学培养、以及在玉雕绘画、技法、加工教学中的实际问题提出了建议.     

基于驻留时间受限的分布参数切换系统的指数稳定性分析

将有限维切换系统指数可稳性结果推广至无穷维Hilbert空间中的分布参数切换系统．以半群理论为基础,通过利用多Lyapunov函数方法,推导了指数可镇定的充分条件．这些条件以线性算子不等式的形式给出,其决定变量是Hilbert空间中的算子;同时系统的可稳性依赖于驻留时间受限的切换规则．在应用到带Dirichlet边界条件的二维热传导切换系统时,这些线性算子不等式被转化成标准的线性矩阵不等式．最后,通过2个例子说明给出结果的有效性．     

基于UML的办公设备网上报修系统的建模

我院自2006年开始启用OA系统,初步实现了无纸化办公。自动化办公系统为我们提供了编制文件、发布通知、收发内部邮件、工资管理,短信息服务等功能,既节约了办公成本,又提高了办公效率。为进一步落实无纸化办公的理念,我们将办公设备报修系统融入了 OA中,本文叙述了报修系统的分析与设计流程,重点突出了建模过程。     

“Top-Down-Top”机械制图Ⅱ教学改革研究

基于"整体—部分—整体"的认识论,按照"Top-Down-Top"组织架构将机械制图、机械测绘、三维建模进行知识融合对机械制图Ⅱ进行教学改革,形成"项目式"课程。根据新的教学内容组织进行了教学大纲与教学计划的修订,借助一体化的教学环境与教学资源,采用多样化教学手段进行教学实施,提高了学生的学习兴趣,促进了理论知识的掌握,提高了学生的绘图技能,培养了学生的创新实践意识。     

供应商参与对新产品开发效率的影响:以知识获取为中介

本文密切结合新产品开发情境,细分了新产品开发需要获取的三类知识,探讨了供应商参与对获取新产品开发所需要三类知识的影响,进而影响新产品开发效率的机理。以广东省158家企业为研究对象,应用结构方程方法实证了研究假设。结果表明,供应商参与对获取新产品开发所需的三类知识具有显著的正向影响,但是对新产品开发效率没有显著的直接影响;获取新产品开发所需的三类知识对新产品开发效率有显著的正向影响。揭示了知识获取是供应商参与影响新产品开发效率的中介变量。