共查询到20条相似文献，搜索用时 308 毫秒
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L.O. Chua 《Journal of The Franklin Institute》1973,296(2):91-113
This paper presents a novel graph theoretic approach for deriving various stationary principles for single-element type nonlinear networks. The concepts of total content, co-content and hybrid content are generalized to that of total parametric content for resistive nonlinear networks containing multivalued elements. The results by Brayton and Moser on potential functions for complete m-ports are generalized to non-complete m-ports in terms of three pseudopotential functions; namely, the pseudo-content, pseudo- co-content and the pseudo-hybrid content. The precise criterion for which each of these pseudo-potential functions reduces to a legitimate potential function is shown to be the unique solvability of an implicit set of equations given explicitly in terms of standard topological matrices. Simple circuit theoretic sufficient conditions are given which require merely the positive-definiteness of the incremental resistance matrix of an auxiliary complete current-controlled p-port and the incremental conductance matrix of an auxiliary complete voltage-controlled q-port. These conditions also guarantee that a non-complete dynamic nonlinear network can be represented by a system of normal form differential equations in terms of a single mixed potential function. 相似文献
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《Journal of The Franklin Institute》2022,359(18):10510-10524
This paper investigates the problem of finite-time attack detection for nonlinear complex cyber-physical networks under false data injection (FDI) attacks. Firstly, a Takagi-Sugeno (T-S) fuzzy model is used to approximate nonlinear complex cyber-physical networks in which the measurement channels are injected by FDI attacks. Secondly, based on adding a power integrator technique, a finite-time fuzzy observer is designed to achieve the rapid state observation of complex cyber-physical networks within a finite time by adjusting the observer parameters. Then, an attack detection mechanism consisting of the finite-time fuzzy observer and an attack detector is developed to detect FDI attacks, which can trigger an alarm within a finite time when FDI attacks occur. Finally, simulation results are given to show the effectiveness and superiority of the proposed method. 相似文献
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基于Struts,Spring和Hibernate的科研信息管理查询系统是集科研信息查询、汇总、图表显示为一体的系统,对于单一框架中查询应用结构复杂、扩展性差的问题给出了解决的实例。 相似文献
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Kabekode V.S. Bhat 《Journal of The Franklin Institute》1982,313(5):299-312
In this paper we pursue the graph theoretic approach to the switching function minimization problem which is still important in view of today's technological innovations such as programmable logic arrays. We use switching functions graphs (SFG) for studying the structure of switching functions and the minimization problem. The graph theoretic interpretation of the classical minimization problem leads to an alternative and powerful approach to logic design that is suitable for computer implementations. The approach is particularly useful in the analysis and design of suboptimum algorithms for minimization of arbitrarily complex switching functions arising in practice for which exact algorithms are known to be computationally intractable. A few graph theoretic algorithms leading to minimization of switching functions are presented and examples indicating the power of our approach, and algorithms are worked out. Further work needed in the area is indicated. 相似文献
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This paper studies synchronization of a dynamical complex network consisting of nodes being generalized Lorenz chaotic systems and connections created with transmitted synchronizing signals. The focus is on the robustness of the network synchronization with respect to its topology. The robustness is analyzed theoretically for the case of two nodes with two-sided (bidirectional) connections, and numerically for various cases with large numbers of nodes. It is shown that, unless a certain minimal coherent topology is present in the network, synchronization is always preserved. While for a minimal network where synchronization is global, the resulting synchrony reduces to semi-global if redundant connections are added. 相似文献
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This paper mainly presents Routh-type table test methods for zero distribution of polynomials with commensurate fractional degrees on the left-half plane, right-half plane and imaginary axis in the complex plane. The proposed tabular methods are derived for extension and generalization of the Routh test, which is widely used in controls for zero distribution of polynomials with integer degrees. Singular cases are discussed and handled efficiently and simply. Necessary and sufficient conditions for the second singular case are completely analyzed in terms of symmetric zeros. A particular property is revealed that a polynomial with commensurate fractional degrees without pure imaginary zero may still be stable in the presence of the second singular case, which is impossible for a real polynomial with integer degrees. Furthermore, we present a test to solve the zero distribution problem with respect to general sector region for polynomials with commensurate fractional degrees and real/complex coefficients. Finally, numerical examples are given to illustrate the correctness and effectiveness of the results. The proposed methods have broad application areas, including various systems, circuits and control. 相似文献
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In this paper, a novel approach for the design of an indirect adaptive fuzzy output tracking excitation control of power system generators is proposed. The method is developed based on the concept of differentially flat systems through which the nonlinear system can be written in canonical form. The flatness-based adaptive fuzzy control methodology is used to design the excitation control signal of a single machine power system in order to track a reference trajectory for the generator angle. The considered power system can be written in the canonical form and the resulting excitation control signal is shown to be nonlinear. In case of unknown power system parameters due to abnormalities, the nonlinear functions appearing in the control signal are approximated using adaptive fuzzy systems. Simulation results show that the proposed controller can enhance the transient stability of the power system under a three-phase to ground fault occurring near the generator terminals. 相似文献
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Luciano Floridi 《Ethics and Information Technology》1999,1(1):33-52
The essential difficulty about Computer Ethics' (CE) philosophical status is a methodological problem: standard ethical theories cannot easily be adapted to deal with CE-problems, which appear to strain their conceptual resources, and CE requires a conceptual foundation as an ethical theory. Information Ethics (IE), the philosophical foundational counterpart of CE, can be seen as a particular case of “environmental” ethics or ethics of the infosphere. What is good for an information entity and the infosphere in general? This is the ethical question asked by IE. The answer is provided by a minimalist theory of deseerts: IE argues that there is something more elementary and fundamental than life and pain, namely being, understood as information, and entropy, and that any information entity is to be recognised as the centre of a minimal moral claim, which deserves recognition and should help to regulate the implementation of any information process involving it. IE can provide a valuable perspective from which to approach, with insight and adequate discernment, not only moral problems in CE, but also the whole range of conceptual and moral phenomena that form the ethical discourse. 相似文献
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Wei Zheng Hongbin Wang Changchun Hua Zhiming Zhang Hongrui Wang 《Journal of The Franklin Institute》2018,355(16):7962-7984
This paper addresses the interval type-2 fuzzy robust dynamic output-feedback control problem for a class of nonlinear continuous-time systems with parametric uncertainties and immeasurable premise variables. First, the parametric uncertainties are assumed to be a subsystem based on the control input matrix and output matrix, and described as a linear fractional. Secondly, the nonlinear continuous-time systems are described by the interval type-2 fuzzy model. Thirdly, the new dynamic output feedback controller is designed based on the interval type-2 fuzzy model and the linear fractional (parametric uncertainties), the sufficient conditions for robust stabilization are given in the form of linear matrix inequalities (LMIs). Compared with previous work, the developed methods not only have abilities to handle the fuzzy system with immeasurable premise variables but also can deal with the parametric uncertainties effectively. The results are further extended to a mobile robot case and a chemical process case. Finally, two simulation examples are performed to show the effectiveness of the propose methods. 相似文献
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T. de Heer 《Information processing & management》1979,15(2):89-98
Good information storage and retrieval systems should not only meet the looseness of human memory but also the looseness of natural language. Our information trace method allows for the creation of mechanical systems that combine looseness with indulgence. In accordance with this method, information records consisting of pieces of natural language are attached to each other, leaving fuzzy semantic traces behind in the form of sets of three-letter-strings which have been derived from the original texts. The system calculates an “importance value” for each possible answer to a user query. Queries also may be given in the form of a simple piece of natural language. Answers are communicated to the user, if he so wishes, in descending order of “importance value” as calculated by the system. 相似文献
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This paper provides the closed form analytical solution to the problem of minimizing the material volume required to support a given set of bending loads with a given number of discrete structural members, subject to material yield constraints. The solution is expressed in terms of two variables, the aspect ratio, ρ-1, and complexity of the structure, q (the total number of members of the structure is equal to q(q+1)). The minimal material volume (normalized) is also given in closed form by a simple function of ρ and q, namely, V=q(ρ-1/q-ρ1/q). The forces for this nonlinear problem are shown to satisfy a linear recursive equation, from node-to-node of the structure. All member lengths are specified by a linear recursive equation, dependent only on the initial conditions involving a user specified length of the structure. The final optimal design is a class 2 tensegrity structure. Our results generate the 1904 results of Michell in the special case when the selected complexity q approaches infinity. Providing the optimum in terms of a given complexity has the obvious advantage of relating complexity q to other criteria, such as costs, fabrication issues, and control. If the structure is manufactured with perfect joints (no glue, welding material, etc.), the minimal mass complexity is infinite. But in the presence of any joint mass, the optimal structural complexity is finite, and indeed quite small. Hence, only simple structures (low complexity q) are needed for practical design. 相似文献
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New active distributed RC-structures utilizing exponential RC-lines and operational amplifiers are proposed for realizing band-pass transfer functions and transfer functions having both a pair of complex poles and a pair of complex zeros. It is shown that the magnitude of the amplifier gain for a given pole Q decreases with increasing taper. In the case of the structures realizing both complex poles and zeros, it is shown that the sensitivity with respect to the gain of the pole-determining amplifier is considerably lower than that of the previously proposed structures. 相似文献
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Mengmeng Wang Jinpeng Yu Yumei Ma Haisheng Yu Chong Lin 《Journal of The Franklin Institute》2019,356(12):6145-6159
A discrete-time adaptive fuzzy control method is introduced to achieve the speed regulation for induction motors (IMs) with input saturation via command filtering in this paper. First, the continuous model of IMs drive system is transformed into discrete-time form by using Euler formula. Then, the fuzzy logic systems are used to approximate the unknown nonlinear functions in the discrete-time drive system. In addition, the command filtering control method is introduced to overcome the “explosion of complexity” problem in the design process of traditional backstepping method. It is verified that all the closed-loop signals are bounded and the outputs can track the given reference signals well. Finally, simulation results illustrate the validity of the discrete-time control method. 相似文献
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在扫描电镜下观察了毛冠菊属Nannoglottis 8种植物舌片的微形态特征,以探讨其颇有争议的系统位置。所有种类舌片近轴面的细胞为板状,长圆形;径向、切向壁直;外壁特征性突起,外壁中央为纵向皱纹,相邻细胞之间的纹饰无系统连接。这些特征表明毛冠菊属和紫菀族Astereae关系密切,但它在紫菀族内的系统位置可能比较特殊。这些结果和依据ITS序列推测的紫菀族系统发育的结果相吻合。文中还讨论了一些微形态性状的演化趋势以及微形态性状在毛冠菊属部分种类分类中的应用。 相似文献
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This paper addresses the problem of local exponential stabilization via boundary feedback controllers for a class of nonlinear distributed parameter processes described by a scalar semi-linear parabolic partial differential equation (PDE). Both the domain-averaged measurement form and the boundary measurement form are considered. For the boundary measurement form, the collocated boundary measurement case and the non-collocated boundary measurement case are studied, respectively. For both domain-averaged measurement case and collocated boundary measurement case, a static output feedback controller is constructed. An observer-based output feedback controller is constructed for the non-collocated boundary measurement case. It is shown by the contraction semigroup theory and the Lyapunov’s direct method that the resulting closed-loop system has a unique classical solution and is locally exponentially stable under sufficient conditions given in term of linear matrix inequalities (LMIs). The estimation of domain of attraction is also discussed for the resulting closed-loop system in this paper. Finally, the effectiveness of the proposed control methods is illustrated by a numerical example. 相似文献
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D.D. Šiljak 《Journal of The Franklin Institute》1973,296(2):115-122
A purely algebraic algorithm is developed for testing positive real character of real rational functions and matrices relative to the unit circle in the complex plane. Since the algorithm is entirely recursive and is performed in a finite number of steps, it is suitable for machine computations. 相似文献