安全约束最优潮流的实用模型及故障态约束缩减方法

针对大型电力系统安全约束最优潮流(SCOPF)问题具有的计算规模庞大、求解困难的特点,提出了基于潮流转移关系的SCOPF实用模型及故障态约束缩减方法。首先通过预想故障分析建立故障前后的有功潮流转移关系,将故障态支路有功潮流描述为基态支路有功潮流的函数,从而将故障态支路有功潮流约束描述为基态支路有功潮流的线性不等式约束;然后通过对并联线路或并列主变压器进行分组,利用组内支路的有功潮流分布关系减少需监视的支路规模;最后利用设备短时通流能力明显大于其长期通流能力的特征对故障态支路潮流约束进行过滤,以尽可能减小SCOPF问题的计算规模。IEEE 14节点测试系统和华东电网的仿真分析验证了所提模型及约束缩减方法的正确性和有效性。     

暂态稳定性事故筛选与排序方法研究

暂态稳定性事故的筛选与排序的目的是针对一组预想的事故集合挑选出严重事故或过滤掉无害的事故。本文对目前的暂态稳定性分析的事故筛选与排序方法,如能量函数法中的PEBS法、基于扩展等面积法则的EEAC法及集中反应事故性能指标的方法进行了总结,并对各类方法进行了对比。指出了各种方法优点和不足。     

基于直流潮流的发输电系统区间负荷N-K事故计算

从严格数学角度研究了基于直流潮流的发输电系统区间负荷K个元件事故评估。区间负荷N-K事故场景非常多,首先从优化角度建立了区间负荷N-K最好状态和最坏状态最小切负荷模型,其中最坏状态模型是典型的双层优化模型,上层决策变量是机组、线路和负荷状态,下层模型是直流潮流的最小切负荷模型。然后,使用强对偶理论和数学等效化简方法,把系统N-K区间负荷最坏状态最小切负荷双层优化模型转化为混合整数线性规划模型,该模型可使用成熟优化软件求解。最后,使用IEEE标准算例,测试了考虑区间负荷、机组和线路（或变压器）故障的区间负荷N-K事故最坏状态评估模型,测试结果显示了本文所提方法的有效性和可行性。     

Relative labelling index: a novel stereological approach to test for non-random immunogold labelling of organelles and membranes on transmission electron microscopy thin sections

Simple and efficient protocols for quantifying immunogold labelling of antigens localized in different cellular compartments (organelles or membranes) and statistically evaluating resulting labelling distributions are presented. Two key questions are addressed: (a) is compartmental labelling within an experimental group (e.g. control or treated) consistent with a random distribution? and (b) do labelling patterns vary between groups (e.g. control vs. treated)? Protocols rely on random sampling of cells and compartments. Numbers of gold particles lying on specified organelle compartments provide an observed frequency distribution. By superimposing test‐point lattices on cell profiles, design‐based stereology is used to determine numbers of points lying on those same compartments. Random points hit compartments with probabilities determined by their relative sizes and so provide a convenient internal standard, namely, the expected distribution if labelling is purely random. By applying test‐line lattices, and counting sites at which these intersect membrane traces, analogous procedures provide observed and expected labelling distributions for different classes of membranes. Dividing observed golds by expected golds provides a relative labelling index (RLI) for each compartment and, for random labelling, the predicted RLI = 1. In contrast to labelling densities of organelles (golds µm^?2) or membranes (golds µm^?1), RLI values are estimated without needing to know lattice constants (area per point or length per intersection) or specimen magnification. Gold distributions within a group are compared by chi‐squared analysis to test if the observed distribution differs significantly from random and, if it is non‐random, to identify compartments which are preferentially labelled (RLI > 1). Contingency table analysis allows labelling distributions in different groups of cells to be compared. Protocols are described and illustrated using worked specimen examples and real data.     

考虑期望损失的综合能源系统故障智能筛选和排序方法

综合能源系统实现了电、热、天然气等多种能源系统的耦合互联,相比于单一能源系统,其故障状态数目大幅增加,如何快速准确地从系统海量的故障状态中筛选出最严重的故障,从而提高风险评估效率,成为综合能源系统风险评估中的关键难题。针对这一问题,基于遗传算法提出了一种综合能源系统故障智能筛选和排序方法。首先,计及多种能源网络的约束条件,建立了综合能源系统故障期望损失双层优化模型,同时刻画了故障发生概率和故障损失对系统的影响。进而,基于遗传算法提出了故障期望损失双层模型的求解方法,并对传统遗传算法进行改进,使得方法能够同时筛选出期望损失最严重的多个故障状态。最后以修改的IEEE 33节点电力系统、巴厘岛供热系统和比利时天然气系统组成的综合能源系统为例,仿真结果表明所提方法的故障筛选效率明显优于常规枚举法和蒙特卡洛方法,证明了所提方法的有效性。     

计及需求侧响应日前-日内两阶段鲁棒备用优化

为增强电力系统应对不确定性因素的能力,提高电网运行效率,提出一种计及需求侧响应日前—日内两阶段鲁棒备用优化模型。一方面,在模型中协同优化价格型与激励型需求侧响应提高电网运行的灵活性;另一方面,综合考虑风电出力不确定性与电力设备N-k强迫停运,增强电力系统应对不确定性因素的鲁棒性。基于鲁棒模型对系统运行备用进行优化,最小化电网在最恶劣运行场景下的调整成本,保证电网的安全可靠运行,并采用列和约束生成算法对两阶段三层优化问题进行求解。修改的6节点系统与IEEE RTS-79测试系统算例验证了所提模型与算法的有效性。结果表明,综合考虑多重不确定性因素进行备用优化,可以提升电网应对极端运行场景的能力;同时,需求侧响应的实施可以大大提高电网运行的灵活性。其中,激励型需求侧响应通过直接控制负荷,对于增强电网运行鲁棒性的作用更加明显;而电价型需求侧响应在要求保障负荷供电的场景下更为适用。     

水电工程投资风险储备金估算数学模型研究

为提高我国水电工程项目管理水平,采用现代风险管理的理论和方法,对建国以来若干水电工程投资变更进行量化分析,分离出当前我国水电工程建设的风险要素。在此基础上,建立一种新型的水电工程投资风险储备金估算数学模型,并给出模型中各风险变量的确定方法。运用此模型,不仅可以提高风险储备金估算的准确性,而且工程投资主体可以在项目前期主动对关键风险进行处置和管理,有效降低项目投资变动风险。     

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.     

Choice and contingency in the development of behavioral autonomy during instrumental conditioning.

In two experiments hungry rats received extensive training to lever press for food outcomes before one outcome was devalued by aversion conditioning and responding tested in extinction. If the rats were trained on a concurrent schedule in which two responses yielded different outcomes, performance during the extinction test was reduced by devaluation of the associated outcome. By contrast, if a single response was trained concurrently with the noncontingent presentations of the other outcome, test performance was insensitive to devaluation of the contingent outcome. This finding demonstrates that training on a schedule that offers a choice between responses that yield different outcomes prevents the onset of behavioral autonomy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How much of protein sequence space has been explored by life on Earth?

We suggest that the vastness of protein sequence space is actually completely explorable during the populating of the Earth by life by considering upper and lower limits for the number of organisms, genome size, mutation rate and the number of functionally distinct classes of amino acids. We conclude that rather than life having explored only an infinitesimally small part of sequence space in the last 4 Gyr, it is instead quite plausible for all of functional protein sequence space to have been explored and that furthermore, at the molecular level, there is no role for contingency.