In this paper the problem of determining optimal workload for a load sharing system is considered. The system is composed of total n components and it functions until (n-k+1) components are failed. The works that should be performed by the system arrive at the system according to a homogeneous Poisson process and it is assumed that the system can perform sufficiently large number of works simultaneously. The system is subject to a workload which can be expressed in terms of the arrival rate of the work and the workload is equally shared by surviving components in the system. We assume that an increased workload induces a higher failure rate of each remaining component. The time consumed for the completion of each work is assumed to be a constant or a random quantity following an Exponential distribution. Under this model, as a measure for system performance, we derive the long-run average number of works performed per unit time and consider optimal workload which maximizes the system performance.

An inverse scattering problem of estimating the surface impedance for an inhomogeneous half-space is investigated. By virtue of the fact that the far field representation contains the spectral function of the scattered field, complex values of the function are estimated from a set of absolute values of the far field. An approximate function for the spectral function is reconstructed from the estimated complex values by the least-squares sense. The surface impedance is estimated through calculating the field on the surface of the half-space expressed by the inverse Fourier transform. Numerical examples are given and the accuracy of the estimation is discussed.

In this paper, we propose a new method for the electromagnetic fields with inhomogeneous media mixed a positive and negative regions by the combination of improved Fourier series expansion method using the extrapolation method which obtains the correct value of the eigenvalue and eigenvectors for the case of TM wave. Numerical results are given for the power reflection and transmission coefficient, the energy absorption, the electromagnetic fields, and the power flow in the inhomogeneous medium mixed the positive and negative regions including the case when the permittivity profiles touches zero for the TM wave. The results of our method are in good agreement with exact solution which is obtained the modified multilayer approximation method.

This paper proposes homogeneous neural networks (HNNs), in which each neuron has identical weights. HNNs can realize shift-invariant associative memory, that is, HNNs can associate not only a memorized pattern but also its shifted ones. The transition property of HNNs is analyzed by the statistical method. We show the probability that each neuron outputs correctly and the error-correcting ability. Further, we show that HNNs cannot memorize over the number,, of patterns, where m is the number of neurons and k is the order of connections.

Crosstalk or coupling phenomenon between two parallel conductors with a ground or reference conductor is well known in electromagnetic compatibility and microwave circuit fields. In this paper we consider the characteristics of a long two-conductor line embedded in an inhomogeneous medium while taking account of the difference between two phase constants in independent propagation modes of two parallel lines. The characteristics of near-end and far-end crosstalk and of through-end transmission are discussed for frequencies up to more than the frequency where the line length is 10 times the wavelength. Interesting properties, such as very strong and null crosstalk phenomena that occur at the far end and non-transmission at the through end, appear in the envelope characteristics. The reason for these properties is clarified by making theoretical and experimental investigations.

An iterative method is proposed to solve integral equations (IEs) of the second kind with Picard-kernel in linear complexity, i.e.O(N). The particular IE considered describes the process of scattering of a plane wave incident on an inhomogeneous slab. The collocation method with triangle basis functions is used to derive a linear system of equations, which is solved for a test problem with the BiCGSTAB method. To reduce the number of iterations, an efficient preconditioning operator is introduced.

The electromagnetic scattering of a plane wave by an inhomogeneous plane whose surface impedance changes locally on the plane is treated. A boundary-value problem is formulated to describe the scattering phenomenon, in which the boundary condition depends on the surface impedance of the plane. Application of the Fourier transform derives an integral equation, which is approximately solved by the method of least-squares. From the solution of the equation, the scattered field is obtained by the inverse Fourier transform. By the use of the incomplete Lipschitz-Hankel integral for the computation of the field, numerical examples are given and the scattering phenomenon is discussed.

We examine diagnosis of processor array systems formed as two-dimensional grids, with boundaries, and either four or eight neighbors for each interior processor. We employ a parallel test schedule. Neighboring processors test each other and report the results. Our diagnostic objective is to find a fault-free processor or set of processors. The system may then be sequentially diagnosed by repairing those processors tested faulty according to the identified fault-free set. We establish an upper bound on the maximum number of faults that can be sustained without invalidating the test results under worst case conditions. We give test schedules and diagnostic algorithms that meet the upper bound as far as the highest order term. We compare these near optimal diagnostic algorithms to alternative algorithms--both new and already in the literature.

An efficient numerical source model is proposed to calculate the induced current densities in the human body from low-frequency inhomogeneous magnetic fields emitted by electronic devices. Due to the complex geometrical structure of electronic devices (e.g. household appliances, power tools), an efficient equivalent source model based on magnetic elementary dipoles is used instead of the real device or the approximated source model (current loop). Subsequently, the validity of the method proposed is confirmed.

A delay-optimal technology mapping algorithm is developed on a general model of FPGA with hard-wired non-homogeneous logic block architectures which is composed of different sizes of look-up tables (LUTs) hard-wired together. This architecture has the advantages of short delay of hard-wired connections and area-efficiency of non-homogeneous structure. The Xilinx XC4000 is one commercial example, where two 4-LUTs are hard-wired to one 3-LUT. In this paper, we present a two-dimensional labeling approach and a level-2 node cut algorithm to handle the hard-wired feature. The experimental results show that our algorithm generates favorable results for Xilinx XC4000 CLBs. Over a set of MCNC benchmarks, our algorithm produces results with 17% fewer CLB depth than that of FlowMap in similar CPU time on average, and with 4% fewer CLB depth than that of PDDMAP on average while PDDMAP needs 15 times more CPU time.

We proposed a new model for non-stationary time series analysis based on an inhomogeneous AR (autoregressive) equation. Time series data is regarded as white noise plus output of an AR system excited by non-stationary input sequence represented in terms of a set of basis. A method of model parameter estimation was presented when the set of basis and the AR order are given. In order to extend the method, we present a method of parameter estimation when the AR order is unknown: we set two new criteria 1) minimize the root mean square error of the output sequence, and 2) minimize scattering of estimated frequencies. Then, we derive a procedure for the estimation of the AR order and the other unknown parameters.

We proposed a new model for non-stationary time series analysis based on the IAR (inhomogeneous autoregressive) model, and a method for model parameter estimation when the set of basis is given. In this paper, we further propose a method for parameter estimation including that of basis set: we set a new condition that power of the input sequence is concentrated in low-frequency domain, and developed an iterative estimation method. We firstly select an initial set of basis, from which new sets are created in order to minimize the difference between the model and data. Among new sets of basis, we select a good one that gives minimum standard deviation of estimated frequencies.

We propose a Generalized Order Statistic Cell Averaging (GOSCA) CFAR detector. The weighted sums of the order statistics in the leading and lagging reference windows are utilized for the background level estimate. The estimate is obtained by averaging the weighted sums. By changing the weighting values, various CFAR detectors are obtained. The main advantage of the proposed GOSCA CFAR detector over the GOS CFAR detector is to reduce a computational time which is critical factor for the real time operation. We also derive unified formulas of the GOSCA CFAR detector under the noncoherent integration scheme. For Swerling target cases, performances of various CFAR detectors implemented using the GOSCA CFAR detector are derived and compared in homogeneous environment, and in the case of multiple targets and clutter edges situations.

Gaussian beams constitute a very powerful tool to analyze radiation and scattering problems in high frequency regimes. The analysis of this kind of beams may be done by performing an analytical continuation of the real sources into the complex space. This is also a very powerful technique that arise, not only to this kind of solutions, but also to other solutions that may be very useful even for low frequency regimes. A complete parametrization of real propagation space in terms of the different type of complex beams solutions is presented in this paper. The analysis in the complex domain arises to different regions in the real space which may be anticipated and described through analytical transition regions. Some important conclusions may be derived from the results obtained, in particular the results related to the complex far field condition.

The supervisory control theory of discrete event dynamic systems was proposed in the framework of automata and formal languages. The concept of decentralized supervisory control was developed for the local supervisor Si whose concurrent operation results in the closed-loop language L (Si/G) equal to that of global supervisor, L (S/G). In this letter we extend this concept by considering the problem of optinal combination of decentralized with centralized control in case pure decentralized control happens to be inadequate. We introduce the concept of locally controllable complementary tuple and present an analytical framework for nonhomogeneous decentralized supervisory control systems.

This letter describes the power absorption of a cylindrical man model placed near a flat reflector exposed to TE microwave. The numerical results show that the absorption is in some cases an order of magnitude or more greater than that of the man model without a reflector.

In this paper, we developed the analytical method for the radiation field from a line current source placed in a stratified slab waveguide. This method is applicable to the analysis of excitation problem of inhomogeneous slab waveguide by increasing the number of layers. The numerical results are given for the cases of five layers, such as W and M type waveguides, and the inhomogeneous slab waveguide. The influence of guided and leaky modes on the radiation field are studied.

It is known that homogeneous networks are ones which perform parallel algorithms, and the dynamics of neural networks are applied to practical problems including combinatorial optimization problems. Both homogeneous and neural networks are parallel networks, and are composed of Boolean elements. Although a large number of studies have been made on the applications of homogeneous threshold networks, little is known about the relation of the dynamics of these networks. In this paper, some results about the dynamics, used to find the lengths of periodic and transient sequences, as built by parallel networks including threshold and homogeneous networks are shown. First, we will show that for non–restricted parallel networks, threshold networks which permit only two elements to transit at each step, and homogeneous networks, it is possible to build periodic and transient sequences of almost any lengths. Further, it will be shown that it is possible for triangular threshold networks to build periodic and transient sequences with short lengths only. As well, homogeneous threshold networks also seem to build periodic and transient sequences with short lengths only. Specifically, we will show a sufficient condition for symmetric homogeneous threshold networks to have periodic sequences with the length 1.

Non-homogeneous Poisson Processes (NHPP's) can be applied for analyzing reliability growth models for hardware and/or software. Evaluating the Mean Time Between Failures (MTBF's) for such processes, we can evaluate the present status (the degree of improvement). However, it is difficult to evaluate the MTBF's for such processes analytically except the simplest cases. The so-called instantaneous MTBF's which can be easily evaluated are applied in practice instead of the exact MTBF's. In this paper, we discuss both MTBF's analytically, and derive the conditions for the existence of both exact and instantaneous MTBF's. We further illustrate both MTBF's for the Weibull process and S-shaped reliability growth model numerically.

The propagation characteristics of nonlinear TE waves guided by planar optical waveguide whose guiding region has arbitrary inhomogeneous refractive-index profile are investigated theoretically by using the WKB method. The effects of inhomogeneous index profile of a guided region on the propagation characteristics such as the propagation constant and the field distribution are estimated numerically.