The resequencing delay for a queueing system with multiple servers under a threshold-type scheduling is analyzed. We first derive the general expressions for the average total delay which is the sum of resequencing delay and queueing delay. The expressions are also applicable to the conventional M/M/n queueing system as the special case of zero-threshold policy. Next, the numerical calculation is carried out for the queueing system with 3 servers under a threshold-type scheduling to consider the impact of the multiple thresholds on the average resequencing delay. It is found that the resequencing delay as well as the queueing delay for a queueing system with multiple servers of different service rates can be recuced under a threshold-type scheduling by selecting the threshold values appropriately. The threshold-type scheduling is more effective to reduce the resequencing delay compared to the queueing delay especially in the region of modest traffic intensity and as the difference of the service rates becomes larger.

This article discusses chaotic responses observed from a periodically forced neural-type oscillator introduced by Newcomb et al. Describing the circuit dynamics by an autonomous equation, we can derive a one-dimensional return map explicity and therefore can prove a sufficient condition of chaos generation in Lasota & Yorkes' sense. Also, our mapping procedure is valid for various other systems and seems to contribute for design of them.

After Diffie and Hellman's paper, there have been published many cryptosystems, where large composite numbers are used as the public keys, and the factorization of them are used as the secret keys. But, on the other hand, there also have been published many integer-factoring algorithms that factor composite numbers rapidly. So methodologies to construct primes that are strong for such algorithms are needed to guarantee the safety of such cryptosystems. Here we propose a randon polynomial time algorithm for constructing strong primes that uses a probabilistic primality testing algorithm.

This is the first to three expository articles, which aim to survey the chaos theory from an engineering point of view. This paper, in the first place, presents a brief introduction to chaos. Then, it is pointed out that the study of chaos from an engineering point of view is a challenging area in engineering science.

In ISDN and ATM, performance evaluation of packetized voice is an important problem. To analyse the superposed voice packets from a number of voice sources, the Markov modulated Poisson process (MMPP) has been used for approximating the superposed non-renewal process. In this approximation, a large computer time was needed for determining the MMPP parameters by the numerical inversion of Laplace transform. In this paper, introducing the index of skewness for counts as well as the index of dispersion, and using their conservation low, limiting property and differential coefficient at the origin, we propose a simplified method for determining the parameters.

The simultaneous measurement of five field components (three magnetic and two electric components) was carried out on board the ionospheric Aureol-3 satellite in a frequency range from 10 Hz to 1.5 kHz, and we have developed a systematic signal processing of direction finding for ionospheric and magnetospheric ELF emissions at eight selected frequencies mainly based on the likelihood concept. So, the purpose of this paper is to present the detailed description of those systematic direction finding measurements at frequencies above and below the proton gyrofrequency, but more emphasis is placed on the latter frequency range where two possible modes of propagation may coexist. This kind of systematic analyses will be of great use in the future wave analysis system on the spacecrafts.

This paper discusses the behavior of a dynamical system described by the extended Liénard equation with an external force e(t)f(x)g(x)e(t)where f and g are not necessarily even or odd with respect to x, respectively. First, basic theorems on the existence of limit cycles and properties of singularities are proved in the case where e(t) is equal to a constant bias denoted by e(t)const.A cos ωτ, and effects of f and g on the portrait of trajectories of the systems are clarified. Then, the dynamical behavior of the system, where the external force is periodic, i.e., e(t)A cos ωt, is represented in relation to the singularity which varies periodically in time; an obtained result makes it clear and easy to understand the dynamical behavior. Further, some conditions which are necessary for the system mentioned above to generate a chaotic solution are presented. Finally, the results of the argument above are applied to the periodically forced van der Pol equation, and it is concluded that chaotic solutions hardly exist in this case.

A hierarchical structure is observed in codimension 2, 1 and 0 homoclinic and heteroclinic bifurcations. Exact bifurcation equations make it possible to discern fine details of the bifurcation diagrams.

This letter describes the electrification properties of the human body by walking. A method is presented for measuring the electrified charge of the human body. The quantitative relationships between the electrified charge behaviors and the walking actions are also shown.

Electroencephalographic (EEG) potentials are analysed by the Lyapunov spectrum in order to evaluate the orbital instability peculiar to deterministic chaos quantitatively. First, the Lyapunov spectra are estimated to confirm the existence of chaotic behavior in EEG data by the optimal approximation of Jacobian matrix in the reconstructed statespace. Second, the same method is applied to a neural network model with chaotic dynamics, the macroscopic average activity of which is analysed as a simple model of EEG data. The first analysis shows that the largest Lyapunov exponent is actually positive in the EEG data. On the other hand, the second analysis on the chaotic neural network shows that the positive largest Lyapunov exponent can be obtained by observing only the macroscopic average activity. Thus, these results indicate the possibility that one can know the existence of chaotic dynamics in the brain by analysing the Lyapunov spectrum of the macroscopic EEG data.

Theoretical description with a potential is made for inhomogeneous structures of high field domain and current filament in semiconductors with a negative differential conductivity (NDC) appearing under voltage- and current-controlled conditions, respectively. The potential proposed here can describe systematically a route from homogeneous state to the patterned state through the instability of homogeneous state, whereas previously proposed potentials can describe only the patterned state. The potential is constructed from two internal variables: one is the variable dependent on the spatial coordinate which exhibits the spatial pattern in the NDC region, while another remains constant spatially but changes discontinuously its value when the patterned state bifurcates from a thermodynamic branch of the homogeneous state. The bifurcation to spatial pattern is examined in a similar way to the first-order phase transition in equilibrium systems. At the same time, the property of the resulting pattern is discussed from analogy with the phase separation.

It was unknown whether there exists a language accepted by a two-way nondeterministic one counter automaton, but not accepted by any nondeterministic rebound automaton. This paper solves this problem, and shows that there exists such a language.

The elliptically-polarized nonlinear beam propagation in a two-dimensional optical guided-wave system containing Kerr media is solved numerically by using the finite-element method. Computed results for a nonlinear substrate exhibit novel transverse effects such as spatially modulational instabilities for solitons emitted from a film. Sensitiveness of the beam propagation on the initial state of polarization suggests a possibility for constructing new photonic devices.

A design method of mode conversion type Y junction waveguides in lens-like media is proposed. The Y junction designed for reducing the mode conversion losses form the fundamental mode to higher order even modes can also reduce the mode conversion losses form the lowest odd mode to higher order odd modes.

Canard is a new phenomenon of slow-fast systems, which was found by the numerical computations. Our primary purpose of this paper is to study the canard from the experimental viewpoint. The following results are obtained by the experimental observation of a nonlinear circuit: (1) Canard really appears in the actual circuit. But canard's life in the circuit is extremely short. (2) When a canard vanished, an irregular oscillations or a cycle with period two is still there, which usually does not occur in the two dimensional autonomous systems.

This paper proposes a new technique for designing 2-D diamond-shaped half-band FIR filters with maximally flat amplitude property. First, a 2-D half-band FIR filter is defined and several interesting properties of this filter are explained. Then a design method using these properties is explained and some design examples are shown. Finally, we discuss the advantages of our method by comparing with the previously proposed method.

This letter demonstrates an experimental result on chaos observed in a very practical electronic circuits called the phase-locked loops. Namely, we report that chaos can in fact occur in a practical FM demodulator circuit made of a phase-locked loop IC module (MC14046B) operating under widely employed high-damping case as well as very low-damping case.

A new type of wide beamwidth antenna is proposed for mobile satellite communication systems. The microstrip crossed slot antenna consisting of four shorted quarter wave elements is one of the antenna elements of wide beamwidth. To widen the beamwidth still further, the antenna installed on a pyramidal ground plane is presented in this letter. The radiation pattern of this antenna is also measured and discussed.

It is well-known that the bit error rate (BER) of digital transmission through a mobile/portable communication channel is strongly dependent on the multipath delay spread. In this paper, we propose an antenna pattern diversity reception system with a new selection strategy based on the measurement of cross-channel-interference which has been confirmed to be a linear function of the multipath rms delay spread assuming BPSK as an example. The coherence bandwidth and BER performances using such a system are studied theoretically and considerable improvement is observed. In addition, the field experiment using a four-direction antenna in 400 MHz band was made to measure error patterns for an individual antenna pattern, and the proposed system was shown to work well even in a real urban area based on the measured data by computer simulation.

This paper proposes a new type of evanescent-mode waveguide filters consisting of two parallel cutoff waveguide paths, in which a number of swelled portions are provided as resonators. One of two paths (the subsidiary path), mechanically connected to the main path in parallel, achieves the negative coupling to exhibit an elliptic-like feature. This type of filters includes a number of complicated waveguide-junction discontinuities. They are analized accurately by the full-wave analytical method based on the mode-matching method. After deriving the generalized equivalent network, the main-path structure is designed to exhibit the specified passband response by using its approximated network. The specified overall characteristic is then synthesized by a computer-aided design method by using an equivalent network without approximations. Measurements on the filters modeled in both X- and U-bands show excellent agreement with the designed characteristics, and prove the feasibility of two-path cutoff-waveguides for filter applications in the microwave and millimeter-wave regions.