A low-sensitivity bandpass switched-capacitor filter (SCF) using two-path and voltage inversion techniques is proposed. The worstcase sensitivity of this SCF becomes zero at the center frequency. The proposed SCF is fully parasitic insensitive and requires a four-phase clock.

This letter describes a method to estimate the power-spectrum of speech signals with additive white noise, based on the maximum likelihood principle and numerical maximization of the likelihood function. Some examples of the estimated spectral patterns for Japanese vowels are presented.

A distributed clocking scheme for ANSI FDDI- is considered. To compensate for clock variability, a frame proceeding through a series of stations has its preamble bits added or deleted. The necessary preamble size for stable operation is calculated, based on a Gumbel distribution fitted to a simulation result.

Scattering of plane electromagnetic wave by a semi-infinite strip grating has been analyzed under the assumption that the strip is narrow relative to the wavelength. Numerical results are given for some diffraction patterns.

A new type of dual-band microstrip antenna was presented and tested. The experimental results had high performance in both the radiation pattern and gain within the desired frequency range. The antenna presented here is, therefore, considered to be effectively applicable as a new type of dual-band antennas.

This paper presents a mathing circuit of a T-shaped ridge waveguide by means of loaded probes. The reactance of the loaded probes for the matching between the ridged waveguide and the coaxial-cable is calculated by the impedance matrix of a source and loaded probes.

A quaternary Boolean ring structure is introduced to the four-element set L={0,,,1}, which is the only Boolean ring structure possible on it; the set of logic functions on L and L² expressible over the ring is extended from the Boolean polynomials to the entire logic functions; the extension becomes possible after inclusion of two non-Boolean polynomials in the basis, where the number is the smallest possible one. A one-to-one mapping between L and {0,1,2,3} is made, and resulting arithmetic operations on L are make explicit in the form of monadic or dyadic functions.

The paper deals with a single server queue with two priority classes of customers. The arrival process for the high-priority class is assumed to be Poisson, while the interarrival time for the low-priority class is allowed to have a general distribution. Work-conserving rules, especially the non-preemptive rule and the preemptive-resume rule, are studied. A relationship between the unfinished work and the waiting times for both priority classes is derived. Numerical calculation for the unfinished work is not so easy, because the queueing model considered here contains the GI/G/1 model. Using a diffusion approximation for the unfinished work process, new approximate formulas for the performance measures are obtained explicitly. If the arrival process for the low-priority class is also Poisson, the formulas are consistent with the classical exact results. Numerical examples and comparisons with simulation results are presented. They indicate that the approximate formulas proposed here are accurate as compared with those presented in the previous works.

A method has been investigated for calculating the material constants for piezoelectric ceramics under the one-dimensional stress, using a bolted Langevin resonator, which can apply compressive stress to the ceramics. For this method, the piezoelectric, dielectric and elastic constants under the static compressive stress can be determined, by measuring the resonant and antiresonant frequencies and the capacitance at constant stress for the resonator, in the same method as used under stress-free condition. Also, four types of lead zirconate titanate piezoelectric ceramics for transducers, NEPEC-1, NEPEC-6, NEPEC-63 and NEPEC-21, have been measured as a function of one-dimensional compressive stress parallel to the polar axis up to a 176 MPa maximum. The hysteresis loops for dielectric constants /ε₀, electromechanical coupling factors k₃₃, piezoelectric constants d₃₃ and g₃₃, and elastic constants and for these ceramics have been presented. These measurement results show inclinations analogous to those reported by Krueger and Meeks. The experimental feasibility and practicability of using a bolted Langevin resonator to measure the piezoelectric ceramic material constants have been established.

Simple and closed form expressions for reflection and transmission coefficients of a thin strip grating on a dielectric sheet are presented for the use of antenna application. In the analysis, a set of integral equations for the aperture fields between strips are derived from the three dimensional boundary value problem. Upon use of the low frequency approximation, closed form expressions are obtained for reflection and transmission coefficients. The accuracy of our approximation results is examined numerically by making use of the Point Matching Method. It is shown that the accuracy is excellent provided 1) the period of gratings is smaller than about 0.3 free space wavelength, and 2) the thickness of the dielectric sheet is greater than about 0.3 times the grating period.

Recently, with development of microwave technology, striplines with various shapes have been used and the analysis for these striplines has become complex. In this paper, we deal with the microstrip side-coupled filter that should be analyzed in three-dimensional space and time by Bergeron's method. The transient analysis of the electromagnetic field is not only useful in clarifying the field response but also yields information on the mechanism by which the distribution of the electromagnetic field in the stationary state is brought about. Firstly in order to know fundamental property of the parallel striplines, the characteristic impedance and the relative phase velocity of the lines are evaluated. Then, the appearance of the band-pass characteristics of the filter is successively shown by the presentation of the electromagnetic field distribution and the Poynting vector in time domain.

A new burner with a multi-flame structure is proposed for high-rate fabrication of optical fiber preforms in the vapor-phase axial deposition process (VAD). In this multi-flame VAD process, the synthesis of fine glass particles was clarified and the fabrication of soot preforms was investigated together with the consolidation process. As a result, a deposition rate of 4.5g/min was achieved using one double-flame burner. Graded-index core preform size was increased to 2500g. In addition, fibers with a high numerical aperture (N.A.) of 0.28 were fabricated using a double-flame burner. A transmission loss at 1.62µm was 0.54dB/km and the bandwidth at 1.3µm was 440 MHz km.

A partitioning automaton which is a modified version of the alternating automaton is introduced. The machine can partition the input string into some blocks and check them universally. The classes of languages accepted by partitioning finite automata and partitioning pushdown automata are shown to be equivalent to the classes of CFL and Aho's indexed languages, respectivery.

Many software reliability growth models have been proposed in the last decade, based on software error data observed during testing phase in the software development. However, the existing models are insufficient to represent the time-dependent behavior of testing-effort expenditures in the actual environment of the software testing. For this reason we develop and investigate a testing-effort dependent reliability model incorporating the testing-effort spent on software testing into the software reliability growth. The model is described by a non-homogeneous Poisson process, assuming that the error detection rate to the amount of testing-effort spent at an arbitrary testing time is proportional to the current error content. The time-dependent behavior of testing-effort expenditures is described by a Weibull curve due to the flexibility. From this model, the quantitative software reliability measures are derived. The estimations for the testing-effort parameters and the reliability growth parameters in the model are given by a method of least-squares and by a method of maximum-likelihood, respectively. Then, statistical inferences on the model parameters and the software reliability measures, and analyses of actual software error data and studied.

Structure runlength coding encodes reversibly digital multi-color images. This coding processes the original images efficiently along raster scan lines. Two-dimensional structure of multi-color images is used to enhance its efficiency. The use of the structure makes the coding much more efficient than conventional runlength coding schemes. Even various gradational areas are coded effectively. This paper presents the precise coding method and compares its efficiency with that of a conventional runlength coding scheme.

Magnetic particles such as Fe₃O₄ and - Fe₂O₃ introduced into hamster pulmonary macrophages were used as a probe for intracellular motility and the rate of phagocytosis. Magnetic particles within the macrophages produce a weak magnetic field around the cells when magnetized with a strong external magnetic field. The field decays with time with a half time less than 5-6 minutes. This decay called relaxation has been recently associated with intracellular movements of microstructures of the cells. In this paper we present the results of relaxation measurements under the influence of inhibitors of ATP synthesis. We also measured the change of relaxation rate during phagocytosis (taking up of the particles by the cells.) The inhibitors notably decreased the rate of relaxation as had been expected. The decrease in the rate of relaxation corresponded well to the decrease in intracellular ATP concentration which was measured by the luciferin-luciferase method. The change of relaxation during phagocytosis of magnetic particules by pulmonary macrophages was clearly seen.