一类不确定中立时变时滞系统的自适应全局滑模控制

针对一类含有时变状态时滞和中立时滞的不确定性系统,提出一种新型滑模变结构控制方法.首先,基于全程滑模的思想,设计带有中立时滞项的积分型滑模面以消除趋近模态;然后,充分利用时滞下界的信息选取Lyapunov函数,采用线性矩阵不等式(linear matrix inequality-LMI)方法给出并证明滑动模态稳定的充分条件,降低时滞保守性;再次,与自适应结合设计滑模控制器,采用饱和函数代替符号函数,削弱系统抖振;最后,针对数值算例进行仿真研究,结果表明所提出的控制方法有效可行.     

现代自由主义的基本观点透析

自由主义作为西方政治文明的成果，在西方近现代史上有着极为广泛的影响，而现代自由主义是在传统自由主义理论的基础上形成和发展起来的崭新的政治哲学思想，它主张在保障个人自由的前提下，国家适当干预经济，关注社会福利，变消极自由为积极自由，变消极国家为积极国家，并在实践中获得极大成功，成为风靡整个西方世界的社会思潮。本文通过对现代自由主义的形成和发展过程的认识，粗浅地总结阐述了现代自由主义的一些基本观点和思想，以期对现代自由主义思想有一个正确的完整的认识。     

多时滞不确定电力系统的改进时滞依赖鲁棒稳定判据

针对现代电力系统中存在的传输信号延时问题,综合考虑实际系统中的多时滞耦合和不确定参数,给出适用于多时滞不确定电力系统的改进时滞依赖鲁棒稳定判据。其中Wirtinger不等式放缩技巧的应用和松散项的引入能够降低结果的保守性,特别是一些必要松散项的引入与Schur补的结合,可有效处理系统中的不确定参数。最后,分别以典型二阶时滞系统、单机无穷大时滞电力系统和WSCC 3机9节点电力系统为例,借助MATLAB中的线性矩阵不等式工具箱,对所提方法进行校验分析,得到系统所能承受的时滞稳定裕度。结果显示所提方法可以对含有不确定参数的多时滞电力系统进行有效的鲁棒稳定性分析,并且结果的保守性也得到了显著降低。     

基于G-范数和sum-范数的三相交流级联系统稳定性判据

在三相交流级联系统中,源模块以及负载模块之间的相互作用将导致整个系统性能下降,甚至有可能导致系统不稳定,尤其是在含有恒功率负载的系统中表现尤为明显。通过分析系统的小信号模型可以看出,模块之间由于相互耦合而产生的稳定性问题和子模块的端口阻抗以及导纳有着直接关系。因此,基于子模块端口阻抗以及导纳的稳定性判据是分析系统级稳定性问题的有效方法。目前,基于子模块阻抗以及导纳的稳定性判据已经广泛应用于直流系统。但是,由于交流系统和直流系统在系统特性上的内在差异,目前广泛应用于直流系统的稳定性判据无法直接使用于交流系统。根据交流系统的系统特性,提出一种基于端口阻抗以及导纳矩阵的G-范数和sum-范数的稳定性判据。且根据矩阵计算的特点,对所提出的稳定性判据做进一步改进,以减少判据的保守性。最终,将所提判据和现有的范数判据进行保守性的比较,可以看出,所提判据的保守性最小,更利于实际应用。     

Construction and validation of a Thurstone scale of liberalism—conservatism.

A 23-item scale of liberalism—conservatism was constructed by the Thurstone method of equal-appearing intervals and found to correlate highly (point-biserial r = .64) with a naturalistic behavioral criterion consisting of self-selected, actively campaigning political groups (Young Democrats and Young Republicans). The scale yielded an internal-consistency coefficient of .79, indicating substantial common variance among items, and a coefficient of reproducibility of .87, indicating quasiscalability. A considerably greater proportion of non-perfect scale types, as evidenced by a significantly greater number of errors of reproducibility (p     

风险投资对上市公司会计稳健性的影响研究

以2012—2014年我国创业板及中小板共978家公司为研究对象,对其在风险投资背景下上市公司的会计稳健性所受影响进行考察。研究结果表明:在我国创业板和中小板上市公司中,风险投资背景的存在会显著影响公司内部会计稳健性水平,相比于不具有风险投资背景的上市公司,具有风险投资背景的上市公司会计稳健性程度更低,即风险投资机构作为公司股东存在的情况会在一定程度上降低目标公司会计信息的稳健程度,在进行会计确认时可能未将可能发生的损失考虑完全,其利润可能存在高估的风险。因此上市公司应正视风险投资机构对其产生的影响,并注重对负面影响进行相应的预防与控制。     

Attribute criteriality and sex-linked conservatism as determinants of psychological similarity.

"Two hypotheses were proposed: 1… . One event is more likely to be judged similar to a standard event if the two differ on some property which… has not been learned as criterial for defining it, than if this property has been learned as criterial for its definition. 2… . When presented with events of varying criterial difference from a standard, females should judge fewer of these events as similar to the standard than males, on the ground that the former tend to categorize more narrowly… . It was concluded that recognition of similarity depends on learned classification rules and on individual differences in conceptual conservatism." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Political conservatism as motivated social cognition.

Analyzing political conservatism as motivated social cognition integrates theories of personality (authoritarianism, dogmatism-intolerance of ambiguity), epistemic and existential needs (for closure, regulatory focus, terror management), and ideological rationalization (social dominance, system justification). A meta-analysis (88 samples, 12 countries, 22,818 cases) confirms that several psychological variables predict political conservatism: death anxiety (weighted mean r=.50); system instability (.47); dogmatism-intolerance of ambiguity (.34); openness to experience (-.32); uncertainty tolerance (-.27); needs for order, structure, and closure (.26); integrative complexity (-.20); fear of threat and loss (.18); and self-esteem (-.09). The core ideology of conservatism stresses resistance to change and justification of inequality and is motivated by needs that vary situationally and dispositionally to manage uncertainty and threat. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The end of the end of ideology.

The "end of ideology" was declared by social scientists in the aftermath of World War II. They argued that (a) ordinary citizens' political attitudes lack the kind of stability, consistency, and constraint that ideology requires; (b) ideological constructs such as liberalism and conservatism lack motivational potency and behavioral significance; (c) there are no major differences in content (or substance) between liberal and conservative points of view; and (d) there are few important differences in psychological processes (or styles) that underlie liberal versus conservative orientations. The end-of-ideologists were so influential that researchers ignored the topic of ideology for many years. However, current political realities, recent data from the American National Election Studies, and results from an emerging psychological paradigm provide strong grounds for returning to the study of ideology. Studies reveal that there are indeed meaningful political and psychological differences that covary with ideological self-placement. Situational variables--including system threat and mortality salience--and dispositional variables--including openness and conscientiousness--affect the degree to which an individual is drawn to liberal versus conservative leaders, parties, and opinions. A psychological analysis is also useful for understanding the political divide between "red states" and "blue states." (PsycINFO Database Record (c) 2010 APA, all rights reserved)