Hiromasa Haneda

Computer generated Lyapunov functions for a class of nonlinear systems

The problem of constructing Lyapunov functions for a class of nonlinear dynamical systems is considered. The problem is reduced to the construction of a polytope satisfying some conditions. A generalization of the concept of sector condition that it makes possible to evaluate a given nonlinear function by using a set of piecewise-linear functions is proposed. This improvement greatly reduces the conservatism in the stability analysis of nonlinear systems. Two algorithms for constructing such polytopes are proposed, and two examples are shown to demonstrate the usefulness of the results. >

Learning Abductive and Nonmonotonic Logic Programs

We investigate the integration of induction and abduction in the context of logic programming. Our integration proceeds in a way that we learn theories for abductive logic programming (ALP) in the framework of inductive logic programming (ILP). Both ILP and ALP are important research areas in logic programming and AI. ILP provides theoretical frameworks and practical algorithms for inductive learning of relational descriptions in the form of logic programs (Muggleton, 1992; Lavrac and Džeroski, 1994; De Raedt, 1996). ALP, on the other hand, is usually considered as an extension of logic programming to deal with abduction so that incomplete information is represented and handled easily (Kakas et al., 1992). Learning abductive programs has also been proposed as an extension of previous work on ILP (Dimopoulos and Kakas, 1996b; Kakas and Riguzzi, 1997).1 The important question here is “how do we learn abductive theories?”

A general steady-state analysis program ANASP for thyristor circuits based on adjoint-network approach

Described is a new computer aided package program ANASP for computing the steady-state waveforms for any configuration of thyristor circuits. Newton-Raphson method is used to compute the initial state which generates the steady-state waveforms. For the efficient and accurate evaluation of the Jacobi an matrix the adjoint network is introduced into thyristor circuits containing power diodes and thyristors, and the method of sensitivity calculation is proposed. Using the program implemented, it is shown through examples that the computational time is considerably reduced to deter mine the steady state.

A new computer-aided method of distortion sensitivity-analysis and its elimination scheme for power electronic circuits

A new general computer-aided algorithm for computing parameter sensitivities of distortion in power electronic circuits and its elimination scheme are proposed. The adjoint network approach is employed for calculating parameter sensitivities of the distortion factor and the ripple factor of current and voltage waveforms. An optimal filter design-algorithm to reduce undesirable harmonics is also proposed. Their performance is shown to be superior through demonstrated numerical examples.

Computer-aided analysis of power-electronic DC-motor drives: transient and steady-state analysis

Described are new and efficient computer-aided analysis packages for general power-electronic dcmotor drive systems. They compute both transient and steady-state waveforms for arbitrary field excitations and any thyristor configuration automatically. Users are only required to input circuit parameters, thyristor gate timing, machine constants and their connections in a free format.

Distance based hybrid genetic algorithm: an application for the graph coloring problem

A hybrid genetic algorithm (GA) which combines the global search power of GA with the local search power of a local optimization algorithm is described for the graph coloring problem (GCP). Each solution of the GCP, which is called phenotype, is represented by a set of isomorphic genotypes conceptually. Then, a metric function between two phenotypes is defined by the least Hamming distance between the corresponding sets of isomorphic genotypes. The phenotypic distance is useful to analyze and control the behavior of genotypes in the search space from the view point of the problem space. A new crossover technique named harmonic crossover is proposed for the GCP. The phenotypic distance between two parents is considered in the harmonic crossover for preserving their common characteristics. Furthermore, the phenotypic distance between two parents is also used to predict promising regions in the problem space. In the proposed hybrid GA for the GCP, the local optimization algorithm is applied only in the most promising regions restrictedly and intensively. Consequently, the run of the local optimization algorithm does not hinder the performance of GA in its progress of global search.

Polygon interval arithmetic and design of robust control systems

Robust stability analysis and the robust controller design problem of multivariable control systems are considered. To represent and treat the uncertainty of frequency response of plants and controllers, a notion of polygon interval arithmetic (PIA) is introduced. By using PIA, the robust stability problem is solved more efficiently than the method based on the mapping theorem. Moreover, by using PIA, a robust sequential return difference (RSRD) method is proposed, which is an improved version of the traditional SRD method in the sense that it can treat uncertainty contained in both plants and controllers, and that it is possible to guarantee integrity if it is desired.<<ETX>>

Optimal design of three-IDT type SAW filter using local search

An optimal design approach for surface acoustic wave (SAW) filters is presented. First of all, the structural design of a three-IDT type SAW filter, which consists of three interdigital transducers (IDT) and two reflectors, is formulated as a combinatorial optimization problem. In order to simulate the frequency response of the SAW filter, the least equivalent circuit model of IDT is employed. Then, a new local search technique based on the k-degree-neighborhood is proposed and applied to the optimization problem successfully. The proposed local search is applicable generally to the structural design of various SAW devices.

Symbolic approach to the implementation of linearizing compensator for robotic manipulators

The authors propose a new method for practical implementation of linearizing compensators for robotic manipulators. A set of statements to compute inverse dynamics or outputs of the linearizing compensators is derived from closed-form symbolic equations generated using the algebraic computation system REDUCE. To remove redundant computations contained in closed-form symbolic equations, a factoring algorithm is proposed. Using a planar manipulator with two revolution joints, it is shown that the proposed method computes the inverse dynamics faster than the conventional method based on the recursive Newton-Euler formulation.<<ETX>>

A new metric function and harmonic crossover for symmetric and asymmetric traveling salesman problems

For the successful application of a genetic algorithm (GA) to the traveling salesman problem (TSP), a suitable distance between two Hamiltonian circuits on a complete graph is useful to estimate the problem landscape. This paper presents a new distance between two Hamiltonian circuits, or phenotypes. The phenotypic distance is defined by the least Hamming distance between isomorphic genotypes. Therefore, it is convenient to analyze and control the behavior of genotypes in the search space. In this paper, a new crossover technique based on the phenotypic distance is also proposed. The crossover technique works together the conventional crossovers arranged for the TSP such as partially mapped (PMX), order (OX) and cycle (CX) crossovers. Because a new child is sure to be located between two parents in the problem space, the local search performance of the conventional crossovers is enhanced with the proposed crossover technique.