多端直流汇流母线差动保护的整定逻辑、配合原则和工程应用研究

随着两端直流日臻成熟,多端直流逐渐得到应用,尤其是最近几年相继建成了多条多端直流,可预见三端乃至多端直流将在电力系统中起到越来越重要的作用。三端直流的工程应用为电力系统的发展带来了许多前沿课题。以禄高肇直流汇流母线差动保护为例,分析了汇流母线差动保护的判据、整定逻辑和保护配合原则,以及在工程中的应用情况,并提出改进建议。

香洲区开关站备用电源自投改造CSB-21A装置手动方式下的整定

备用电源自投装置在越来越多的变电所得到应用,微机控制装置采用经过可编程控制器编写动作程序,以适应不同变电所、不同主接线情况下的使用,针对某一动作可以有若干种实现方法。但是这种较为灵活的整定也带来了定值及接线因人而异的缺点,现通过我在香洲区农网改造工程中开关站备用电源自投实现方式,规范和统一电网备用电源自投的应用和整定。由此使开关站级的备用电源自投方式统一规范为日后的运行、维护及检修带来方便。

气象灾害形式概念分析模型

为解决气象灾害领域概念及隐含关系难以发现、语义描述准确度不够的问题,将形式概念分析与本体理论相结合,提出气象灾害形式概念分析模型,开展气象灾害领域知识的发现、表示和应用研究。利用逻辑定标定义谓词逻辑属性,实现多值背景转换,结合形式化语言表达对象间关系,实现气象灾害领域概念内涵和外延在本体知识库下的逻辑表达和智能推理应用。利用该模型给出寒潮气象灾害形式概念分析及应用过程实例。

The Logical Properties of Filters of Lattice Implication Algebra

In this paper, we discuss some propertie s of lattice implication algebra and difine the transitivity of implication in a set, we show the transitivity of implication and the substitution Theorem hold i n filters. So every filter of lattice implication algebra satisfies the Syllogis m and substitution Theorem of propositional logic.

Determination of coal mine mechanization using fuzzy logic

Two of the most important tasks in coal mines are to improve efficiency and to increase production besides keeping safety constantly in mind.In order to obtain these goals,mine mechanization is required.Mine mechanization needs high levels of investment and should therefore be studied carefully before final decisions about mechanization are made.When analysizing the potential for mechanization the following,rather imprecise,factors should be considered:seam inclination and thickness,geological disturbances,seam floor conditions,roof conditions,water at the working face and the extension of seams.In our study we have used fuzzy logic,membership functions and created fuzzy rule-based methods and to considered the ultimate objective:mechanization of mining.As a case study,the mechanization of the Takht coal seams in Iran was investigated.The results show a high potential for mechanization in most of the Takht coal seams.

TABULAR TECHNIQUES FOR OR-COINCIDENCE LOGIC

The map folding method for the conversion between Boolean expression and COC expansions is analyzed. Based on it, the tabular techniques are proposed for the conversion between Boolean expression and COC expansion and for the derivation of GOC expansions with fixed polarities. The Fast Tabular Technique (FTT) for the conversion from the Boolean expression to the GOC expansion with the required polarity is also proposed. The simulative result shows this FTT is faster than others in references because of its inherent parallelism.

Design of an optimal active stabilizer mechanism for enhancing vehicle rolling resistance

Improving rollover and stability of the vehicles is the indispensable part of automotive research to prevent vehicle rollover and crashes.The main objective of this work is to develop active control mechanism based on fuzzy logic controller(FLC) and linear quadratic regulator(LQR) for improving vehicle path following,roll and handling performances simultaneously.3-DOF vehicle model including yaw rate,lateral velocity(lateral dynamic) and roll angle(roll dynamic) were developed.The controller produces optimal moment to increase stability and roll margin of vehicle by receiving the steering angle as an input and vehicle variables as a feedback signal.The effectiveness of proposed controller and vehicle model were evaluated during fishhook and single lane-change maneuvers.Simulation results demonstrate that in both cases(FLC and LQR controllers) by reducing roll angle,lateral acceleration and side slip angles remain under 0.6g and 4° during maneuver,which ensures vehicle stability and handling properties.Finally,the sensitivity and robustness analysis of developed controller for varying longitudinal speeds were investigated.

Multi-Embed Nonlinear Scale-Space for Image Trust Root Generation

An image trust root is a special type of soft trust root for trusted computing. However,image trust root generation is difficult,as it needs a corresponding stable logic feature generation model and algorithm for dynamical and sustained authentication. This paper proposes a basic function of constructing new scale-spaces with deep detecting ability and high stability for image features aimed at image root generation. According to the heat distribution and spreading principle of various kinds of infinitesimal heat sources in the space medium,a multi-embed nonlinear diffusion equation that corresponds to the multi-embed nonlinear scale-space is proposed,a HARRIS-HESSIAN scale-space evaluation operator that aims at the structure acceleration characteristics of a local region and can make use of image pixels' relative spreading movement principle was constructed,then a single-parameter global symmetric proportion(SPGSP) operator was also constructed. An authentication test with 3000 to 5000 cloud entities shows the new scale-space can work well and is stable,when the whole cloud has 5%-50% behavior with un-trusted entities. Consequently,it can be used as the corresponding stable logic feature generation model and algorithm for all kinds of images,and logic relationships among image features for trust roots.

Determination of Causal Effect in Observational Studies： Analysis of Correlated Data with Binary End-Points

Identifying the causal impact of＇ some intervention challenging when one is faced with correlated binary end-points in observational studies is a challenging task, and it is even more The statistical literature on analyzing such data is well documented. Dependence between observations from the same study subject in correlated data renders invalid the usual chi-square tests of independence and inflates the variance ofparameter estimates. Disaggregated approaches such as hierarchical linear models which are able to adjust for individual level covariate：s are favoured in the analysis of such data, thereby gaining power over aggregated and individual-level analyses. In this article the authors, therefore, address the issue of analyzing correlated data with dichotomous end-points by using hierarchical logistic regression, a generalization of the standard logistic regression model for independent outcomes.

Deduction Theorem and Hypothetical Syllogism Rule on Fuzzy Logic System

Cancelled the first axiom L1) or the third axiom L3) of the classical formal logic system we established two kinds of quasi-formal deductive system, LG-R^* and LG^* respectively. In LG-R^* we proved that neither the deduction theorem nor the hypothetical syllogism (HS) rule held but a deduction theorem and an HS rule are obtained in a weak sense. We also proved that both the deduction theorem and the hypothetical syllogism(HS) rule hold in LG^*.

Virtual Reality Simulation of Fuzzy-logic Control during Underwater Dynamic Positioning

In this paper, graphical-user-interface （GUI） software for simulation and fuzzy-logic control of a remotely operated vehicle （ROV） using MATLABTM GUI Designing Environment is proposed. The proposed ROV＇s GUI platform allows the controller such as fuzzy-logic control systems design to be compared with other controllers such as proportional-integral-derivative （PID） and sliding-mode controller （SMC） systematically and interactively. External disturbance such as sea current can he added to improve the modelling in actual underwater environment. The simulated results showed the position responses of the fuzzy-logic control exhibit reasonable performance under the sea current disturbance.

Underdetermination, Multiplicity, and Mathematical Logic

Whether a collection of scientific data can be explained only by a unique theory or whether such data can be equally explained by multiple theories is one of the more contested issues in the history and philosophy of science. This paper argues that the case for multiple explanations is strengthened by the widespread failure of models in mathematical logic to be unique, i.e., categorical. Science is taken to require replicable and explicit public knowledge; this necessitates an unambiguous language for its transmission. Mathematics has been chosen as the vehicle to transmit scientific knowledge, both because of its ＂unreasonable effectiveness＂ and because of its unambiguous nature, hence the vogue of axiomatic systems. But mathematical logic tells us that axiomatic systems need not refer to uniquely defined real structures. Hence what is accepted as science may be only one of several possibilities.

Customization Using Fuzzy Recommender Systems

We discuss some methods for constructing recommender systems. An important feature of the methods studied here is that we assume the availability of a description, representation, of the objects being considered for recommendation. The approaches studied here differ from collaborative filtering in that we only use preferences information from the individual for whom we are providing the recommendation and make no use the preferences of other collaborators. We provide a detailed discussion of the construction of the representation schema used. We consider two sources of information about the users preferences. The first are direct statements about the type of objects the user likes. The second source of information comes from ratings of objects which the user has experienced.

Frege＇s and Russell＇s Contributions to Logic： A Comparative Exposition and Critique

Our ability to arrive at knowledge by chains of judgment is constitutive of our rationality, likewise our ability to discern the self-evidence of logical and arithmetical laws. To count an activity as ＂thinking about the physical world＂ is to hold it assessable in the light of the laws of physics; whereas to count an activity as ＂thinking at all＂ is to hold it assessable in the light of the laws of logic. Thus, the kind of generality that distinguishes logic from the special sciences is a generality in the applicability of the norms it provides. Logical laws are more general than laws of the special sciences because they prescribe universally the way in which one ought to think, if one is to think all. Logicism is usually understood to be the thesis that all, or at least large parts of, mathematics can be reduced to logic. This thesis has two sides： （1） all mathematical concepts can be defined in terms of basic logical concepts; （2） all mathematical theorems can be deduced from basic logical truths. According to logicism all terms, including all mathematical terms, are to be given a definite meaning within the basic system. This paper aims at a comparative analysis of the contributions of Frege and Russell to the development of modem logic by reviewing in some detail their essential features and derivations. Without making any pretensions to proffering a definitive resolution of any puzzles, the discussion will, however, raise some fundamental questions, and offer a critical evaluation of the putative success or failure of the logicist programmes of Frege and Russell.

The Fundamental Theorem of Ultraproducts in Lattice valued Model for L_α Logic

In this paper we add some new corcollary and theorems to [1],in particular,we show the fundamental theorem of ultraproducts in lattice valued model for L α logic. As a corollary,we get the α compactness theorem for L_α logic.

Path-tracking Control of a Tractor-aircraft System

An aircraft tractor plays a significant role as a kind of important marine transport and support equipment. It＇s necessary to study its controlling and manoeuvring stability to improve operation efficiency. A virtual prototyping model of the tractor-aircraft system based on Lagrange＇s equation of the first kind with Lagrange mutipliers was established in this paper, According to the towing characteristics, a path-tracking controller using fuzzy logic theory was designed. Direction control herein was carried out through a compensatory tracking approach. Interactive co-simulation was performed to validate the path-tracking behavior in closed-loop, Simulation results indicated that the tractor followed the reference courses precisely on a flat ground.

Minimizing Tardy Jobs in a Single Machine Scheduling Problem with Fuzzy Processing Times and Due Dates

The optimality of a fuzzy logic alternative to the usual treatment of uncertainties in a scheduling system using fuzzy numbers is examined formally. Processing times and due dates are fuzzified and presented by fuzzy numbers. With introducing the necessity measure, we compare fuzzy completion times of jobs with fuzzy due dates to decide whether jobs are tardy. The object is to minimize the numbers of tardy jobs. The efficient solution method for this problem is proposed. And deterministic counterpart of this single machine scheduling problem is a special case of fuzzy version.

浅谈蕴涵推演法与双蕴涵推演法

蕴涵推演法与双蕴涵推演法是数学证明中常用的方法。在《集合论与逻辑代数初步》中,要求学员掌握并会运用这种方法。本文谈谈蕴涵推演法与双蕴涵椎演法的理论依据、所使用的逻辑定律以及它们在集合论中的运用,供同学参考。

一例SEL-311L纵差保护误动作分析

光纤保护作为线路的主保护已经得到普及,在故障时可快速动作切除故障,保障了电网的安全可靠运行。本文针对一起纵差保护误动作事件进行了分析,找出了全进口SEL-311L纵差保护误动的原因,并提出了解决方案,实现了SEL-311L纵差保护的可靠运行。