Alternative approaches to structural modeling of ordinal data: A Monte Carlo study

In practice, several measures of association are used when analyzing structural equation models with ordinal variables: ordinary Pearson correlations (PE approach), polychoric and polyserial correlations (PO approach), and conditional polychoric correlations (CPO approach). In the case of structural equation models without latent variables, the literature has shown that the PE approach is outperformed by the alternatives. In this article we report a Monte Carlo study showing the comparative performance of the aforementioned alternative approaches under deviations from their respective assumptions in the case of structural equation models with latent variables when attention is restricted to point estimates of model parameters. The CPO approach is shown to be the most robust against nonnormality. It is also robust to randomness of the exogenous variables, but not to the existence of measurement errors in them. The PO approach lacks robustness against nonnormality. The PE approach lacks robustness against transformation errors but otherwise it can perform about as well as the alternative approaches.     

基于块间关系的鲁棒视频水印算法设计

为了提高视频文件中水印算法的透明性和鲁棒性,在此提出了一种基于数据块间关系的水印嵌入算法,该方法以数据块之间的特定关系表示水印的比特值,从而避免了将水印值直观地嵌入原始的视频文件中。在介绍该水印算法的详细设计过程后,给出了水印的嵌入过程和提取过程,最后对设计的水印算法进行了透明性和鲁棒性的测试,测试结果表明该算法在高比特率的情况下具有较高的透明性。对于大部分常见的水印攻击方法具有较强的鲁棒性,但对于降低视频图像分辨率的攻击方法,水印的鲁棒性还有待提高。     

鲁棒性数字图像水印算法研究

为了有效保护多媒体信息的版权,研究利用离散余弦变换的算法对整个数字水印图像进行数字变换,将水印加载在中低频分量上以保护原多媒体信息,对数字水印图像的嵌入、提取和攻击进行鲁棒性测试,试验表明该方法不仅可以从攻击后的图像中完整提取水印,而且水印的鲁棒性及抗攻击性较好,可经受一定程度的有损信号处理和一般的数字几何变换,有较强的推广价值.     

数字电路系统设计与制作的一般方法

介绍一种数字电路系统设计与制作的一般方法。分析数字电路系统的各组成电路作用和设计原则,把复杂的数字电路系统逐步划分成不同层次、相对独立的子系统;通过对子系统的逻辑关系、时序等的分析,选用合适的各种中大规模集成数字电路器件来实现;按照由大到小,由整体到局部,再由小到大,由局部到整体的设计方法进行系统设计,实现利用现有的数字电路器件来设计与制作具有各种复杂逻辑关系的数字电路系统。     

基于FPGA的数字音响均衡器的设计与实现

介绍采用FPGA（现场可编程逻辑阵列）为数据处理和控制核心的新型数字音响均衡器的设计原理和实现方法.所设计的均衡器能在不同的环境下实现稳定、高效的幅频均衡,采用全数字的均衡方法,均衡精度较高,有较高的实用价值.     

Scientific reasoning during adolescence: The influence of instruction in science knowledge and reasoning strategies

The mechanism linking instruction in scientific topics and instruction in logical reasoning strategies is not well understood. This study assesses the role of science topic instruction combined with logical reasoning strategy instruction in teaching adolescent students about blood pressure problems. Logical reasoning instruction for this study emphasizes the controlling-variables strategy. Science topic instruction emphasizes variables affecting blood pressure. Subjects receiving logical reasoning instruction link their knowledge of blood pressure variables to their knowledge of controlling variables more effectively than those receiving science topic instruction alone—their specific responses show how they attempt to integrate their understanding.     

稳健性极点配置自适应设计的实现

提出一种稳健性极点配置自适应控制算法，该算法由精选一优化ＩＶ参数估计器和稳健性极点配置控制器构成．算法的稳健特性在于当系统存在未建模动力学及不可测量有界噪声时，被控对象的输出能被镇定．     

基于混沌置乱的DWT域语音水印算法的研究

作为信息隐藏技术中的数字水印技术是信息时代的一个热门研究课题。语音水印技术由于受到人的听觉特性的限制,使得传统数字水印技术在实现上有一定难度。研究并实现了一种基于混沌置乱技术引入传统的DWT域语音水印算法,该算法可以实现向宿主语音信号嵌入具有特定意义的数字水印,且由于引入了混沌置乱技术极大地提高了水印的安全性和鲁棒性,并同时具有易于提取和高透明性的特点。     

基于Multisim结合编程设计复杂逻辑电路

采用卡诺图法和代数法设计逻辑电路时,随着变量的增加,其表达式的冗长让人应接不暇,化简工作难以为继.而利用Multisim结合编程设计复杂的逻辑电路是可行的,不但能解决常规方法无法解决或难以解决的问题,而且效率大大提高,最终生成的逻辑电路准确、完备.     

A Simulation Study of Polychoric Instrumental Variable Estimation in Structural Equation Models

Data collected from questionnaires are often in ordinal scale. Unweighted least squares (ULS), diagonally weighted least squares (DWLS) and normal-theory maximum likelihood (ML) are commonly used methods to fit structural equation models. Consistency of these estimators demands no structural misspecification. In this article, we conduct a simulation study to compare the equation-by-equation polychoric instrumental variable (PIV) estimation with ULS, DWLS, and ML. Accuracy of PIV for the correctly specified model and robustness of PIV for misspecified models are investigated through a confirmatory factor analysis (CFA) model and a structural equation model with ordinal indicators. The effects of sample size and nonnormality of the underlying continuous variables are also examined. The simulation results show that PIV produces robust factor loading estimates in the CFA model and in structural equation models. PIV also produces robust path coefficient estimates in the model where valid instruments are used. However, robustness highly depends on the validity of instruments.     

动态知识表达系统的鲁棒性

定义了知识表达系统的成熟度、规则频率比和规则重要度的概念,并从这些概念出发讨论知识表达系统的鲁棒性能,分析了成熟度与规则频度以及规则重要度的关系,并给出了具有鲁棒性的知识表达系统或概念的构建算法,分析表明这种构建算法具有良好的鲁棒性能和实用价值．     

多输出组合逻辑电路的简化设计

大多数的组合逻辑电路属于多输出电路 ,在进行多输出电路的设计时 ,由于输出变量增多 ,情况较单输出电路复杂 ,采用一般的设计方法分别对每个输出函数进行设计 ,尽管各个输出电路是最简的 ,但对整个系统来说并不一定最简 ,这时可以从系统整体来考虑 ,采取利用公共项、利用部分输出结果以获得另一些输出和分解成小系统等方法使系统设计简化     

模拟/混合信号设计流程自动化实现的障碍与解决方案

近几年来,人们对模拟/混合信号(A/MS)设计流程自动化的发展给予了极大的关注并将目光逐渐集中在A/MS标准语言、逻辑综合、模拟与数字协同仿真、模拟与数字电路的集成及物理综合等五个主要方面。经过多年的努力,在这些方面的研究虽取得了一定的进展,但是离成功地研制出全自动的、易使用的 A/MS设计流程确还有一段距离,仍存在一些值得探讨和研究的问题。     

A robust tolerance design method based on process capability

This paper presents a method for robust tolerance design in terms of Process Capability Indices (PCI). The component tolerance and the suitable manufacturing processes can be selected based on the real manufacturing context. The robustness of design feasibility under the effect of uncertainties is also discussed. A comparison between the results obtained by the proposed model and other methods indicates that robust and reliable tolerance can be obtained.     

A robust tolerance design method based on process capability

INTRODUCTIONTolerancedesignisabridgetolinktherequirementofproductperformanceandthemanufacturingprocess;andaffectsnotonlytheproductperformance,butalsothecostoftheproductandthemanufacturingprocess.There foreComputerAidedTolerancing (CAT)be comesthekeytechniqueforintegratingCAD CAPP CAM (WuandYang,1999) .Tradition ally,thetoleranceisassignedtothecomponentdimensionsaccordingtotheminimumcost.Therestrictionofthemanufacturingabilityoftoolsthatthefactoryownsisneglected (Jietal.,1999) .Asa…     

民间美术色彩在数码设计中的应用研究

这里针对具有地域性特色的民间美术色彩在现代数码设计中的借鉴和应用进行深入研究和分析,探讨民间美术与数码设计之间的关系,将民问美术中丰富多彩的色彩元素加以系统的研究、整理,探讨如何将民间美术中的精神元素与现代设计语言重新组合,使它具有新的时代特征,并丰富现代设计的艺术语言和思想内涵。     

增强功能电子线路模拟制作测试——数字电路逻辑仿真

本论文在对相关数字逻辑电路、TTL集成电路和VisualBasic数据库知识作简要介绍的基础上 ,用VisualBasic数据库语言设计数字逻辑真值表 ,利用查真值表对电子线路类制作测试模拟实验课中PCJK部分的地址译码及缓冲锁存电路的线路分析部分进行模拟逻辑分析其原理 ,最后通过逻辑信号的时序图来显示其运行结果 ,实现数字电路逻辑仿真     

Robust design and optimization for autonomous PV-wind hybrid power systems

This study presents a robust design method for autonomous photovoltaic （PV）-wind hybrid power systems to obtain an optimum system configuration insensitive to design variable variations. This issue has been formulated as a constraint multi-objective optimization problem, which is solved by a multi-objective genetic algorithm, NSGA-II. Monte Carlo Simulation （MCS） method, combined with Latin Hypercube Sampling （LHS）, is applied to evaluate the stochastic system performance. The potential of the proposed method has been demonstrated by a conceptual system design. A comparative study between the proposed robust method and the deterministic method presented in literature has been conducted, The results indicate that the proposed method can find a large mount of Pareto optimal system configurations with better compromising performance than the deterministic method. The trade-off information may be derived by a systematical comparison of these configurations, The proposed robust design method should be useful for hybrid power systems that require both optimality and robustness.     

Curriculum sensitive assessment: Content does make a difference

This chapter explores the use of rankings and total test scores in large-scale international comparative studies and some of the issues related to them. It examines their value as a basis for policy decisions and educational research. Country ranks on total test scores have been seen to be relatively robust to changes in test content, even changes directed at greater curriculum relevance. Unfortunately, other analyses suggest this robustness is likely a consequence of high levels of aggregation and broad, shallow domain sampling. Student achievement in mathematics and science is inherently multi dimensional. Highly aggregated scores of broadly sampled domains are inherently misleading and mask fundamental, educationally relevant diversities at more specific levels of the curriculum.     

Empirical evaluation of different classroom spaces on students' perceptions of the use and effectiveness of 1‐to‐1 technology

This study explored the effect of different classroom spatial layouts on student perceptions of digital technology in a secondary schooling environment. A quasi‐experimental approach facilitated by a Single Subject research design (SSRD) isolated the impact of two learning spaces—traditional' classrooms, and ‘new generation learning spaces’ (NGLS), on students' perceived effectiveness, use and value of one‐to‐one technology as a learning tool. Results from quantitative analyses over the period of a school year indicated that different spatial configurations had a measurable effect on how students' perceived the effectiveness of the affordances of digital technology, with improvements often linked to NGLS. However, the evidence suggests that a change in learning space alone will not increase learning. A change in space supports those teachers who are able and willing to integrate the affordances of technology into their practice. Building on the collective methodologies of earlier work this analysis has reinforced the credibility of this unique methodological approach, arguing this evaluative strategy offers the capacity to generate much needed robust empirical data on evaluation of learning environments in a secondary school setting.