We have analyzed the electromagnetic field with the aid of the method of mode matching in the case that the conducting screen is placed on an infinite conducting plane and that the electric or magnetic line source is set in the neighbourhood of the screen. We have revealed numerically the effects of the screen on the radiation patterns and the equi-amplitude contours of the field in the vicinity of the screen and line source.

Nb3 (Ge, Si)/a-Si oxide/Pb junctions have been fabricated and their I-V characteristics have been investigated. Δsum gap, Rsub gap/RNN and IcRNN take excellent values of 4.7 mV, 18 and 4 mV, respectively, by oxidizing surface layer of a-Si before exposure to air until barrier thickness becomes 2025 .

The paper is concerned with solutions to permutation layout problems such that i) no wire passes the upper area of the upper horizontal line, and ii) no wire intersects the lower horizontal line more than once. A necessary and sufficient condition for a problem to have such a solution is given. The set of all the solutions to the given problem is characterized in a graph theoretical way. A linear time algorithm is also given.

This paper presents the equations for the AM and FM noise in IMPATT diode oscillators under two-frequency operation. In these equations, the contributions of fluctuations from the fundamental and the 2nd harmonic components are represented as differential coefficients.

Polarization mode properties of a polarization-preserving fiber having elliptical stress-cladding with barrier layer around the core are clarified theoretically and experimentally. Normalized frequency dependence of modal birefringence and polarization mode dispersion were measured for the polarization-preserving fiber. It is found from theoretically and experimentally evaluated results that the elliptical stress-cladding fiber has polarization-mode properties similar to those of the polarization-preserving fiber having isolated stress-producing lobes. Stress profiles of the elliptical stress-cladding fiber were measured and calculated for confirming the polarization-mode properties of the fiber. It is known from the measured results that the similarities of polarization-mode properties between the elliptical stress-cladding fiber and the fiber will stress-producing lobes are caused by those of differential stress profiles around the core regions between them.

This paper describes a computing algorithm for the tree distance based on the structure preserving mapping. The distance is defined as the minimum sum of the weights of edit operations needed to transform tree Tα to tree Tβ under the restriction of the structure preserving mapping. The edit operations allow substituting a vertex of a tree to another, deleting a vertex of a tree and inserting a vertex to a tree. The proposed algorithm computes the distance between Tα and Tβ in time OT( mβ Nα Nβ) and in space OS( Nα Nβ), where Nα, Nβ, mα and mβ are the number of vertices of Tα, that of Tβ, the maximum number of children of a vertex in Tα and that in Tβ, respectively. Possible applications are to pattern recognition, syntactic error detection and correction for natural and artificial languages, and information retrieval for tree-structure data.

In this paper existing software reliability growth models are reviewed by an error detection rate theory which is based on a nonhomogeneous Poisson process. The underlying concept of a software reliability growth model is summarized under general conditions. And the related software reliability measures and the maximum likelihood estimation of the model parameters are presented. The error detection rate theory is developed on the summary above of a software reliability growth model. As a software reliability growth index the error detection rate per error playes an important role in reviewing and classifying existing software reliability growth models. The models discussed here are the exponential, modified exponential, delayed S-shaped, and inflection S-shaped reliability growth models. Numerical illustrations for actual software error data are presented to show the relationship between the software reliability growth and the error detection rate.

This paper reports the measurements for the axial mode competition in the 636.0 nm He-Cd II laser at several He pressures. The beginning conditions for the actual mode competition are examined experimentally, and discussed qualitatively from the viewpoints of the broadening mechanisms of the spectral lines. As a result, the axial mode separation at the beginning point of the mode competition gives the upper laser level decay rate γa under the actual lasing condition at 636.0 nm Cd II line. Based on experiments, the upper and lower laser level decay rates γa and γb, and hence the γab (mean value of γa and γb), are all determined along with the collision cross sections of the excited lasing state Cd atoms with buffer gas (He) atoms. The derived values of γa (0)49.5 MHz at the zero-pressure limit, which yields the radiative life time of the upper laser level at 3.2 ns, and the collision corss section σHe1.710-16 cm2 are roughly consistent with those reported based on the theoretical calculations. The experimentally determined He pressure dependence of the γa is expressed by γa49.51PHe(MHz), where PHe is the He pressure. For example, at PHe6 Torr, γa56.5 MHz, γb121 MHz, and then γab(γaγb)/288.8 MHz.

This paper introduces a new method of deriving high-speed FFT based on two-dimensional parallel processing, and describes its VLSI hardware implementation. With the development of VLSI technology, research on special processors for high-speed processing is on the increase and studies are focused on designing VLSI-oriented processors for signal processing. Among them, subjects concerning the development of a new FFT algorithm to handle extremely large volumes of data, and the design of special hardware using that algorithm are pointed out. This paper proposes a two-dimensional systolic array hardware structure and also proposes a new computing algorithm for performing data permutation by a two-dimensional systolic array to solve the above stated problem. The proposed array structure and the algorithm provide highly parallel processing suited for high speed FFT on a large number of data. In addition, a new algorithm to process arbitrary sampling points without hardware modification is suggested. Finally, the comparison of performance among the proposed FFT method by two-dimensional systolic array, systolic DFT array proposed by Kung and the existing general unity FFT processor is investigated.

A design method of rate-distortion optimum scalar quantizer is developed, and performance of the optimum quantizer is compared with those of linear quantizers using mean square error and output entropy, for a simple class of probability density function (pdf.). The simple class means that pdf. is unimodal and symmetric about its mode value, and is differentiable in both sides of symmetry. The method proposed here is based on solving Kuhn-Tucker condition and is essentially the same as those reported before (by Berger or by Farvardin and Modestino), but is shown to be a more advantageous method. Moreover, it has the rules in what region the initial value must be given and how one stop of iteration is solved, and checkpoints for the existence and number of solutions, those have not been shown before except empirically. Without these rules, it seems to be very perplexed problem to check upon the solutions, and algorithm of calculation would be very complicated and time consuming, for even a pdf. of the simple class. Performance of the optimum quantizer is obtained for standard normal distribution and Laplacian distribution with unit variance. It is compared with two kinds of linear quantizers. One is ordinary linear quantizer and the other is equi-interthreshold quantizer with optimized reconstruction levels. Detailed comparisons seem to show that equi-interthreshold quantizer has the most recommendable performance, at least for the pdf's examined here.

Intensity noise of an injection laser enhanced by the optical feedback was reduced by application of electric negative feedback. The reduced noise level was lower than that under operation free from the optical feedback.

A new design method for transversal filters having nonuniform tap spacings is presented. The method has two special features: i) the maximum length of delay-line can be specified arbitrarily, ii) the convergence to the desired characteristics is guaranteed as the number of taps is increased infinitely.

An adaptive antenna array system with phase-only control and under the principle of DCMP (directionally constrained minimization of power) is discussed. A new penalty function is introduced for the system in order to take into consideration the protection of the desired signal while minimizing the unwanted interference and/or noise. Because of the analytical limitation, computer simulation experiments are extensively carried out. The constraint coefficient that is the most important factor of the penalty function is especially investigated, and the optimum choice is given. It is also shown that the theoretical consideration leads to the same value. Finally, the quantization of phaseshifters is attempted, and the limit of its performance is shown.

Sub-linear system" is a name proposed for the systems which are non-linear in the usual addition rule but can be brought to be linear by some modification of the addition rule. The purpose of this paper is to provide a theory for a special kind of sub-linear systems in which the modified addition rule is u1u2(u1+u2)/(1u1u2) instead of u1u2. Such sub-linear systems are found to be saturable systems obtainable through mapping by hyperbolic tangent function from linear systems. They can be treated as exactly and explicitly with the mathematics remaining tractable as the corresponding linear systems, so that our accumulated knowledge on linear systems may successfully be applied to them. The sub-linear systems, however, are the systems quite different from the linear systems. The latter suffer from unavoidable or unexpected saturation or overflow of the actual hardware, but the former can be specially synthesized to take advantage of their saturating characteristic. The present theory treats the sub-linear systems with lumped constants, distributed constants, scalar fields and vector fields. And the proposed theory is expected to be applied in circuits, automatic control, communication, instrumentation, magnetics, non-linear optics, high energy-density engineering etc.

Rademacher transform image coding has been investigated for monochrome image coding. This paper presents a experimental extension of the technique to the coding of NTSC signals obtained from still pictures. A computer simulation shows that good coding performance has been obtained.

The current dependence of the contact resistance was analyzed with special attention given to Joule heating. It was found that as the hardness of the real contact area was proportional to I-2, the real contact area was proportional to I. Therefore, the contact resistance has I-1 characteristic at the contact temperature of 2θs or 0.62θm.

Loss increase due to hydroxyl group formation of a fiber expose to hydrogen gas in measured. Experimental result shows that the loss increase is proportional to 0.57 power of exposure time. Temperature dependence of the loss increase is also estimated from the result.

The crosstalk and the distortion of the optical pulse due to the random polarization coupling is calculated for the birefringent optical fiber from the random mechanical bending and twist, by using the generalized expression of the coupling coefficients. A long-tailed" crosstalk pulse is found to appear as a result of the random polarization coupling. The improvement of the polarization instability from the random deformation by increasing the birefringence is discussed.

A newly developed current injection logic circuit is described. Input signal currents are directly injected into the inductor of a Josephson interferometer instead of being magnetically coupled to it. This circuit realizes excellent isolation characteristics between input and output signals. The additional offset-bias circuit increases the drivability and extends the operating margin. Experimental circuits forming cascade chains of 100 gates were fabricated using 10 µm-square lead-alloy Josephson junctions. The measured switching delay time was about 30 ps at a power dissipation of 15 µW.

As a thickness measurement using the resonance of microwaves, a method using a cylindrical type resonator has been reported. It offers the measurement with high accuracy. But since this method requires a very close separation between the object and the resonator, it seems inconvenient in the case of high temperature objects. Therefore the present authors fix their eyes on Fabry-Perot resonator as a method with little limitation of the distance from the resonator to the object, and have developed a thickness meter which consists of two displacement meters using a Fabry-Perot resonator. The manufactured thickness meter offered good performance as follows: (1) Accuracy is 20 µm, (2) resolution is 2 µm, and (3) maximum distance between a plate and thickness meter is 107 mm. The meter was applied to the transformation measurement of steels, and it is found that the meter can be used for measuring the transformation. The behavior of the transformation was clearly detected.