相空间中二阶非完整力学系统的形式不变性

研究相空间中二阶非完整力学系统的形式不变性．给出相空间中二阶非完整力学系统形式不变性的定义和判据,得到形式不变性的结构方程和守恒量形式,并举例说明结果的应用．     

量子场论中的时空特性分析

经典量子力学中粒子的基态场值,对应于量子场论中的真空期待值,场值的非零和零值,直接与背景空间的平坦性有关.当我们把坐标系建于运动的微观粒子之上时,坐标系的运动状态,又刚好与时空的平坦性相联系.匀速动的坐标系时空均匀而对称,加速运动的坐标系时空不均匀、不对称,有了这种联系,我们对量子场论中规范不变化的时空特征和真空对称性破缺机制就可做出合理的解释.     

Two-Step Approach to Partial Factorial Invariance: Selecting a Reference Variable and Identifying the Source of Noninvariance

To date, no effective empirical method has been available to identify a truly invariant reference variable (RV) in testing measurement invariance under a multiple-group confirmatory factor analysis. This study proposes a method that, in selecting an RV, uses the smallest modification index (min-mod). The method’s performance is evaluated using 2 models: (a) a full invariance model, and (b) a partial invariance model. Results indicate that for both models the min-mod successfully identifies a truly invariant RV (Study 1). In Study 2, we use the RV found in Study 1 to further evaluate the performance of item-by-item Wald tests at locating a noninvariant variable. The results indicate that Wald tests overall performed better with an RV selected in a partial invariance model than an RV selected in a full invariance model, although in certain conditions their performances were rather similar. Implications and limitations of the study are also discussed.     

Using multi-group confirmatory factor analysis to evaluate cross-cultural research: identifying and understanding non-invariance

Multi-group confirmatory factor analysis (MGCFA) allows researchers to determine whether a research inventory elicits similar response patterns across samples. If statistical equivalence in responding is found, then scale score comparisons become possible and samples can be said to be from the same population. This paper illustrates the use of MGCFA by examining survey results relating to practising teachers' conceptions of feedback in two very different jurisdictions (Louisiana, USA, n?=?308; New Zealand, n?=?518), highlighting challenges which can occur when conducting this kind of cross-cultural research. As the two contexts had very different policies and practices around educational assessment, it was considered possible that a common research inventory may elicit non-equivalent responding, leading to non-invariance. Independent models for each group and a joint model for all participants were tested for invariance using MGCFA and all were inadmissible for one of the two groups. Inspection of joint model differences in item loadings, scale reliabilities, and scale inter-correlations established the extent of non-invariance. This paper discusses the implications of non-invariance within this particular study and identifies difficulties in using an inventory in cross-cultural settings. It also provides suggestions about how to increase the likelihood that a common factor structure can be recovered.     

关于力学系统的对称性

力学系统有各种对称性。该文就完整力学系统举例说明各种对称性之间的关系。     

Mathematical equivalence assessment: Measurement invariance across six countries

Within mathematics education research, there has been a strong focus on students’ understanding of mathematical equivalence because of its key role in the development of mathematics skills. One of the most frequently used tools to assess students’ understanding of equivalence has been the Mathematical Equivalence Assessment (MEA) (Rittle-Johnson et al., 2011). In this study, we investigate for the first time the cross-cultural measurement invariance of an adaptation of the MEA. This included a sample (N = 2760) of students aged 8–12 years old from China, England, New Zealand, South Korea, Turkey, and US to examine whether the same construct is being measured across all countries. Configural and partial scalar invariance was established for a two-factor, 11-item version of the adapted MEA. There were significant mean differences across countries, with students from China performing better and students from New Zealand performing worse than the rest of the sample.     

物理规律(方程)的对称性、协变性、规范不变性

较为详细地论述了物理规律的对称性、协变性、规范不变性三之间的关系及其应用，揭示了物理规律的对称性在科研中所具有的重要作用。     

Rasch模型项目参数不变性的验证研究

Rasch模型具有被试参数和项目参数相互独立的性质,即被试能力与项目难度无关。本研究以某年度大学入学考试数学学科的实测成绩数据为例,在随机抽样、不同性别抽样、不同水平群体抽样等条件下,对Rasch模型项目参数不变性进行了验证研究。研究表明:Rasch模型项目参数不变性验证的前提条件较为严格,需要排除诸多干扰因素的影响;Rasch模型项目参数不变性的验证存在一定的误差,无法实现与理论一致的"不变性";Rasch模型项目参数不变性没有统一的标准,需依据实际问题确定。     

The potential of anchoring vignettes to increase intercultural comparability of non-cognitive factors

ABSTRACT

We investigate whether Anchoring Vignettes (AV) improve intercultural comparability of non-cognitive student-directed factors (e.g., procrastination). So far, correlation analyses for anchored and non-anchored scores with a criterion have been used to demonstrate the effectiveness of AV in improving data quality. However, correlation analyses are often used to investigate external validity of a scale. Nonetheless, before testing for validity, the reliability of the measurement of a construct should be examined. In the present study, we tested for measurement invariance across countries and languages and compared anchored and non-anchored student-directed self-reports that are highly relevant for the students’ self and their behaviour and performance. In addition, we apply further criteria for testing reliability. The results indicate that the data quality for some of the constructs can – in fact – be improved slightly by anchoring; whereas, for other self-reports, anchoring is less successful than was hoped. We discuss with regard to possible consequences for research methodology.     

基于光电混合系统的家用机器人视觉系统

指出家用机器人比工业机器人将具有更广泛的应用前景。构建一种基于光电混合系统的家用机器人的视觉系统,以联合变换相关器实现目标图像的平移不变性,以综合判别函数和WTA网络构成级联式神经网络实现目标图像的畸变不变性。讨论整个系统的原理及其实施方案,论证其可行性,为家用机器人提供了一种有效的多目标实时模式识别方法。