A flexible, Product-structured stchastic process model may be represented by the modified Bessel pdf (probability density function) of the third kind and the Struve cdf (cumulative distribution function) which were formerly represented by a single integral and a double integral respectively. These transcendental functions representation may be used for a rapid and precise computation of the pdf and cdf. The explicit representation of moments by a gamma function is also given.

A new system for measuring sound velocity change in liquid is described. The experiment with water as a function of temperature has been demonstrated to clarify the effectiveness of the system. As a result, resolution of sound velocity change better than 10^-4 has been established with the system.

This paper presents a queueing system with a load balancing mechanism and an approximate model. We can get the utilization of servers and the distribution ratio from the model. The values agree well the results of simulations.

Switching characteristics of bistable distributed feedback lasers are analyzed theoretically. The results predict that switch-on speed as well as switch-off speed is improved by a factor of two or more by detuning the Bragg wavelength to shorter wavelength from the wavelength at which the gain is the maximum. This improvement is mainly due to enhancement of the differential gain through the detuning effect.

The Josephson triode is a superconducting three terminal device and is used as a heterodyne mixer which has the internal frequency-variable local oscillator. We have fabricated the Josephson triode by integrating the planar-type Josephson junctions and investigated their current-voltage characteristics.

In general, the analysis-synthesis systems are constructed on a linear frequency scale. On the other hand, the frequency resolution of human hearing system have non-linear characteristics. So, it is interesting to study about the analysis-synthesis system on such a non-linear frequency scale like MEL scale. And it is well known that LSP analysis-synthesis method is superior to LPC or PARCOR method in frame rate and quantization characteristics. In this paper, we describe an LSP analysis-synthesis system on MEL frequency scale. At first, we propose the way to obtain LSP parameters on Mel frequency scale (Mel LSP parameters) from the speech signal in linear time domain. Next we propose how to construct the analysis and synthesis filters in linear time domain using the MEL LSP parameters. Furthermore, we combine this system with the ordinary LSP analysis-synthesis system to improve the quality of the synthetic speech. We carried out some experiments to make clear the characteristics of the combined system. The results of tests show that the quality of synthetic speech with the combined system is higher than that with the ordinary LSP system and that with the MEL LSP system on condition that total prediction order is 10. Through the further experiments, we confirm that the synthetic speech quality with the combined system is as good as the that with the standard LSP system at prediction order 12.

Waveform moment describes one of the characteristics of the given signal wave. Though basic definitions are quite simple, use of waveform moment and extended waveform moment is shown in numerous areas of DSP. Expressions in both time domain and frequency domain are found and using these, criterion for excluding Nyquist filter possibility, evaluation of frequency characteristics for Elliptic filter, method for determining frequency response for not all points etc. are derived. It is shown that analysis using extended waveform moment method becomes simpler than the direct application of known standard methods.

Multi-server queueing systems with traffic intensity which vary according to an irreducible Markov chain are considered. We will show that the probability distribution for the number of customers in these systems can be expressed by an algebraic sum of geometric series with appropriate coefficients satisfying some interesting properties. To study these properties a detailed analysis of the denominator of the partial generating functions of the number of customers in the system is presented. These coefficients allow us to explain the behavior of the system under different traffic conditions. First, we derive a general expression for the probability distribution and then compare this result with that of the Zukerman and Rubin's model. One special section is devoted to the case of an arbitrary number of phases. Some numerical results are also provided and discussed to support the theoretical results.

This paper presents a numerical algorithm to calculate the first and second moments of the first passage times between states on a certain subset, which concern with the key measures of interests of the Markov renewal process with finite states. Since recursive formulas are the important part of the algorithm, it is very well suited to the computation of the moments and is easily programmed. The algorithm makes it possible to compute the key measure of interests on microprocessor even when the model comprised a quite large number of states.

Statistics for traffic congestion control in circuit-switched networks in which regulation changes periodically are analyzed. The powers of the statistics in testing for overloads are derived for time-variant offered loads. The most powerful tests are presented for a percentage control and a call density control under special conditions. Numerical examples show the effectiveness of all busy ratio in an incoming trunk circuit group. These results are significant for congestion control scheme design.

A high-density cable structure, containing fiber ribbons inserted tightly into slots, is proposed for a high-fiber-count feeder line. This paper describes theoretical and experimental investigations on the residual strain due to inserting ribbons into a helical slot in this cable. The residual strain caused by different insertion methods is clarified and a strain suppression method is discussed. Based on the results, 600-fiber cable is manufactured and the transmission and mechanical performances are confirmed to be excellent.

For grasping the electromagnetic environment, the visualization as a pattern of electromagnetic field distribution is effective. Generally, the electromagnetic field distribution pattern is composed of several fields caused by different electromagnetic wave sources. In this paper, a method of pattern decomposition of overlapped electric field pattern is proposed. This method is based on the least square estimation of intensity of electromagnetic wave sources under the assumption that the location of every source has been given. The estimation formula of electric field intensity of sources is derived. This method is applied to decompose the real patterns measured in semi-anechoic chamber. These experimental results show that the method of pattern decomposition can be used to eliminate or extract the unwanted reflected and scattered field with less error.

The effects of impurity atoms and energy gap profiles in the optical guiding layers of GaAs-AlGaAs Separate Confinement Hetero (SCH) structure on the threshold current density are theoretically analyzed. Impurity doping in the optical guiding layers is not effective in reducing the threshold current, because impurity atoms induce non-effective current in those layers. The threshold current densities in three types of band gap profiles of the optical guiding layers are examined to find the most profitable structre of the SCH laser. Examined shapes of the profile are step, parabolic and linear types. The lowest threshold current densities calculated in each profile are almost identical if the design parameters such as the thickness of each layer and the alloy ratio are suitably chosen.

A digital system for measurement of angular speed and acceleration or torque for motors is presented, which uses a usual flywheel method with a simple photo-sensor. In our system, an improved type of an inverse-time function generator is especially developed to obtain the accurate angular speed signal from the period of one revolution of the shaft. Despite of the simple form, this system has many advantage in measuring the wide speed range between 128 (or 12.8) and 32768 (or 3276.8) [r/min] with high accuracy of 3 (or 0.3) [r/min] and high acquisition rate (once a revolution). In addition to the digital output for the speed, the analog outputs for the speed and acceleration are also equipped for the torque-speed curve plotting of motors. As a practical application, the torque-speed curves of a two-phase servomotor and a hysteresis synchronous motor are measured.