Stable inversion of LPTV systems with application in position-dependent and non-equidistantly sampled systems

Many control applications, including feedforward and learning control, involve the inverse of a dynamical system. For nonminimum-phase systems, the response of the inverse system is unbounded. For linear time-invariant (LTI), nonminimum-phase systems, a bounded, noncausal inverse response can be obtained through an exponential dichotomy. For generic linear time-varying (LTV) systems, such a dichotomy does not exist in general. The aim of this paper is to develop an inversion approach for an important class of LTV systems, namely linear periodically time-varying (LPTV) systems, which occur in, e.g. position-dependent systems with periodic tasks and non-equidistantly sampled systems. The proposed methodology exploits the periodicity to determine a bounded inverse for general LPTV systems. Conditions for existence are provided. The method is successfully demonstrated in several application cases, including position-dependent and non-equidistantly sampled systems.     

突破二元对立困境的社会资本理论研究——评林南的社会资本理论的理论视野

林南的社会资本理论从理性选择出发,在行动与结构的互动、微观与宏观的连接、个体与整体的同构中,建立了强调差别、选择和建构,突出实践、社会网络和制度场域的具有鲜明观点的社会资本理论,突破了社会学方法论的二元对立困境,为社会学研究开辟了新的途径,成为一个新的解释范式。     

外轮廓识别算法在纸箱打样机中的应用研究

提出以角度判别法对纸箱打样图形进行外轮廓识别,并介绍了识别多个外轮廓的算法步骤.同时,采用射线法识别外轮廓多边形中的内轮廓图形,为避免在判断过程的复杂运算,利用二分法对射线法进行了优化,并分析了算法的求解过程.相比传统的无序加工过程,外轮廓的识别功能提高了纸箱打样机的加工精度和加工效率.     

IMPLICATE FINAL CAUSES IN DEVELOPING MATERIAL SYSTEMS

Abstract

Causality in changing natural systems can be seen to involve all four Aristotelian causal categories—material, efficient, formal and final. Final causality of materialistic origin can be found in the need to maintain energy flow continuity within dissipative systems. Each interacting dissipative system acts finalistically so as to attract needed energy. In so acting, it continually disturbs its neighborhood by generating potential energy flow disruptions as results of its activities. Final causality based, in this way, on the energy requirements of dissipative systems will generate formal causes as well. In contrast, the emergence of formal causes in mechanistic systems driven solely by efficient causes is extremely unlikely. We suggest viewing the subordination of phenotypic dissipative systems by genotypic counterparts as an historical example of the emergence of formal causes out of the material necessity of maintaining flow continuity. Functional separation between genotypic and phenotypic dissipative systems can occur if the energies to be dissipated are localized, as is the chemical binding energy of molecules with respect to biological functions at a higher scalar level.     

Familiarity for associations? A test of the domain dichotomy theory.

Episodic recognition memory is mediated by functionally separable retrieval processes, notably familiarity (a general sense of prior exposure) and recollection (the retrieval of contextual details), whose relative engagement depends partly on the nature of the information being retrieved. Currently, the specific contribution of familiarity to associative recognition memory (where retrieval of the relationships between pairs of stimuli is required) is not clearly understood. In this study, we tested domain dichotomy theory, which predicts that familiarity should contribute more to associative memory when stimuli are similar (within-domain) than when they are distinct (between-domain). Participants studied stimulus pairs, and at test, discriminated intact from rearranged pairs. Stimuli were either within-domain (name–name or image–image pairs) or between-domain (name–image pairs). Across experiments we used 2 different behavioral measures of familiarity based on receiver operating characteristic curves and a modified remember–know procedure. Both experiments provided evidence that familiarity can contribute to associative recognition; however, familiarity was stronger for between-domain pairs, in direct contrast to the domain dichotomy prediction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

RBCC飞行器上升段飞行走廊规划方法

摘要：为解决火箭基组合动力飞行器上升段飞行过程中飞行走廊规划的问题,提出一种基于马赫数-高度参考曲 线的走廊规划方法。针对飞行器的飞行任务及飞行过程中的多约束问题,建立基于二分法求解迎角实现走廊规划的 算法流程,选择马赫数-高度曲线作为走廊剖面,依据二分法求解迎角最大值最小值的思路,对马赫数和迎角二分求 解,并对规划方法进行了仿真分析。仿真结果表明,该方法能够在满足各种约束的情况下求解出合理的走廊剖面。     

需求响应对配电网供电可靠性的影响

鉴于峰谷分时电价能够引导用户用电行为,促使用户积极参与到电力系统的削峰填谷行为中,而负荷与可靠性之间存在着复杂的非线性关系,文中重点研究了需求侧响应对配电网供电可靠性的影响。首先,建立分时电价优化模型:进行时段划分、确定电力价格弹性矩阵和制定各时段电价,再以峰负荷最小及峰谷负荷差最小确定多目标优化函数,考虑电网和电力市场基本约束条件建立分时电价优化模型;然后,在基于二分法的聚类负荷分析法中引入依据电力报价的负荷修正环节;最后,将不同负荷水平下的可靠性指标按持续时间进行加权平均,得到精确的可靠性指标。利用上述模型和方法,对改进的RBTS BUS6测试系统进行分时电价建模和可靠性评估。结果表明,需求响应策略改善了配电网的供电可靠性。     

电缆沟敷设方式下电缆载流量计算及其影响因素分析

根据传热学的基本原理,利用有限单元自动划分法,建立了一种基于有限元法的电缆载流量计算模型,能按照实际敷设情况的变化对模型参数进行修改。根据电缆的结构参数和周围敷设区域的物性参数分析了电缆沟中电缆区域温度场分布情况,并提出基于二分法计算电缆载流量的方法。对比分析结果表明,相对于IEC60287中的热路法,该模型不仅计算结果准确,而且能更方便地考虑外界环境因素对电缆载流量的影响。通过实例仿真得出不同影响因素对电缆温度场分布的影响规律,并验证了该模型的准确性和可靠性。     

光收发模块灵敏度测试方法探讨

针对光收发模块接收端灵敏度测试时间较长的问题,提出了先通过最小二乘法拟合出接收光功率与误码率的关系曲线,再利用该曲线通过外推法来近似估算基于PIN的光接收器灵敏度的方法。介绍了基于该方法的自动测试系统的架构,测试程序的执行流程和算法实现以及测试步骤。测试过程及结果表明,该测试系统在控制测试误差的基础上大大提高了测试效率。     

分岔隧道的围岩应力及变形数值分析

利用ABAQUS有限元程序,建立数值模型,模拟了分岔隧道不同洞段的开挖过程,分析了围岩变形与应力分布特点。基于数值分析,提出了针对不同洞段的支护形式。工程实例证明：这种支护形式有效地改善了围岩的应力分布,控制了围岩的变形。