The connection admission control is one of preventive traffic control in ATM networks. The one objective of connection admission control is to keep the network load moderate so as to achieve a performance objective associated with quality of services (QOS). Because the cell loss rate is more sensitive to offered load than the average queuing delay in ATM networks, QOS requirement associated with cell loss rate is considered. The connection admission control acts as one of the major roles in traffic control. The job of connection admission control is to make an acceptance decision for connection set-up request to control the network load. This paper proposed and evaluated a connection admission control method. The proposed method is suitable for real time operation even in large diversity of connection types, because the amount of calculation for connection admission control is reduced remarkably compared to conventional algorithms. Moreover, the amount of calculation for the algorithm does not increase even when the number of connection types increases. The proposed method uses probability function for the number of cells transferred from multiplexed connections and uses recursive equations in estimating cell loss rate.

A new effect of barrier metal laid under 1st aluminum layer on electromigration has been found in interconnect vias. This effect can be explained by Si nodules at vias. Stress induced open failure occurred at viaholes and depends on the size of the vias. Stress-migration at vias can be prevented by TiN barrier metal between 1st and 2nd metals. Reliability of electro- and stress-migration at interconnect vias can be explosively improved by using TiN barrier metal.

It is recognized in Japan that reformation of the national research institutions is urgently necessary. Present situation and constraints are shown and the action items are discussed.

It has been 15 years since we started producing the electric double-layer capacitors (also known as Super Capacitor) in 1978. Over the years we have introduced improvements that increased reliability and increased life. For example, after subjecting capacitors manufactured in 1984 and 1990 to load life tests (70, 5.5 V) for 2,000 hours, we discovered that the rate of change in capacitance (ΔC/C) of capacitors manufactured in 1990 was less than one-half that of capacitors manufactured in 1984. This shows that we have successfully increased the life of our electric double-layer capacitors. We conducted investigations regarding factors that contribute to volume of the electrolyte solution and better sealing properties. In the load life test, we observed that when the ratio of the weights of the electrolyte solution and the powdered activated carbon (hereinafter referred to as LB) was increased, the time it took before ΔC/C reached -30% was lengthened. This means that increasing LB also increases life. Furthermore, we also observed that when the gas permeability rate of the collector's rubber material was decreased in the load life test (70, 5.5 V), the time it took befor (ΔC/C) reached -30% was longer. Therefore life is dependent on the gas permeability rate (sealing property) of the collector rubber.

This paper points out that there are two types of claw free families with respect to a level of claw freeness. We formulate them as weak claw free families and strong claw free families. Then, we present sufficient conditions for each type of claw free families. (A similar result is known for weak claw free families.) They are represented as some algebraic forms of one way functions. A new example of strong claw free families is also given.

Mean Time Between Failures (MTBF) is an important measure of practical repairable systems, but it has not been obtained for a repairable linear consecutive-k-out-of-n: F system. We first present a general formula for the (steady-state) availability of a repairable linear consecutive-k-out-of-n: F system with nonidentical components by employing the cut set approach or a topological availability method. Second, we present a general formula for frequency of system failures of a repairable linear consecutive-k-out-of-n: F system with nonidentical components. Then the MTBF for the repairable linear consecutive-k-out-of-n: F system is shown by using the frequency of system failure and availability. Lastly, we derive some figures which show the relationship between the MTBF and repair rate µorρ(=λ/µ) in the repairable linear consecutive-k-out-of-n: F system. The figures can be easily used and are useful for reliability design.

In this paper, we propose a plausible software reliability growth model by applying a mathematical technique of stochastic differential equations. First, we extend a basic differential equation describing the average behavior of software fault-detection processes during the testing phase to a stochastic differential equation of ItÔ type, and derive a probability distribution of its solution processes. Second, we obtain several software reliability measures from the probability distribution. Finally, applying a method of maximum-likelihood we estimate unknown parameters in our model by using available data in the actual software testing procedures, and numerically show the stochastic behavior of the number of faults remaining in the software system. Further, the model is compared among the existing software reliability growth models in terms of goodness-of-fit.

New focused ion beam (FIB) methods for microscopic cross-sectioning and observation, microscopic crosssectioning and elemental analysis, and aluminum film microstructure observation are presented. The new methods are compared to the conventional methods and the conventional FIB methods, from the four viewpoints such as easiness of analysis, analysis time, spatial resolution, and pinpointing precision. The new FIB methods, as a result, are shown to be the best ones totally judging from the viewpoints shown above.

A new pattern synthesis method for multibeam reflector antennas is described. The Directional Constrained Minimum Power (DCMP) method, which was developed as an adaptive array algorithm, has been applied to reflector antennas with cluster feeds. The main objective of this pattern synthesis is to optimize the excitation distribution of the cluster primary feed in order to reduce the sidelobe level and to attain a high main beam gain. A desired contour beam pattern has also been attained by modifying this method. Furthermore, this paper describes other applications of this method, such as pattern optimization taking account of the frequency characteristics and the change in the radiation pattern due to an antenna pointing system, cross-polarization reduction, and monopulse pattern synthesis for an RF sensor.

In this paper, we present some novel concepts and photonic devices for use in optical interconnects. First, we review the progress of surface emitting lasers while featuring materials and performances including thresholds, power output, RIN, linewidth, and so on. Advanced technology for aiming at spontaneous emission control, photon recycling, polarization control, wavelength tuning, integration etc. will be considered. Then we touch on some other possible devices for optical interconnects. Lastly, we discuss on lightwave subsystems applying these devices and concepts.

When we use the finite-difference time-domain (FD-TD) method to study time-domain electromagnetic fields in the unbounded surroundings, we frequently use a radiation boundary condition (RBC) by means of one-way wave equations. The reflection coefficient by the RBC is independent of frequency, but the reflection coefficient of the finite difference approximation for the RBC depends on a frequency also; this study examines how the reflection characteristics are affected by the frequency, and the study presents the coefficients used in the RBC which gives expected reflection characteristics for a frequency, and presents the application to simulation of the matched termination of a rectangular waveguide.

This paper applies the principle of radar polarimetry to the synthetic aperture frequency modulated continuous wave radar. First, the principle of monochromatic wave radar polarimetry using scattering matrix and polarization ratio necessary for introducing polarimetric imaging is given. In order to accommodate this principle to a wideband radar, a scattering matrix must be introduced, because FM-CW radar utilizes a wideband signal. This paper points out that the polarimetric target reflection coefficient obtained by the synthetic aperture FM-CW radar works as the scattering matrix element. This replacement, i.e., polarimetric reflection coefficient = the scattering matrix element, was verified by an experiment based on the polarization ratio which maximizes and minimizes a target. A radar system operative in the microwave X-band was successfully applied to the polarimetric detection of a metallic pipe of different orientations, demonstrating the validity of FM-CW radar polarimetry, and indicating an establishment of full polarimetric radar system.

Expressions for electromagnetic fields generated by vertical and horizontal electric dipoles located in the air or in a lossy half-space near its boundary with air are obtained from Hertz vectors by the method of operators under the condition |n|31, where 1/n is the refractive constant of the lossy space. These can be applied up to the near fields under the additional conditions, |n|21 and cos2θ1, where θ is the zenith angle of the point of observation. As for recent works inclusive of expressions of lateral waves their weak points are pointed out.

This paper describes the current situations and future directions of intelligent CAI researches/development in Japan. Then necessity of intelligence in CAIs/Educational systems are thought over corresponding to the model of teaching and the cognitive model of human learning like the situated learning, knowledge construction and so on. Originally, the main aims of ITSs/ICAIs are to tealize the high level environment of individual teaching/learning. So it is the most important to incorporate the intellectual function of teaching into the system. Whatever kinds of teaching purposes ITSs have, they have the quite complex structure which consists of the domain knowledge base (Expert system), student model, the tutoring knowledge base, the powerful human interface, and sophisticated inference engine with plural functions by artificial intelligence technology. In this paper, the technological and educational points of view are discussed, surveyed and summarized based on intelligent teaching functions of ITSs/ICAIs. Moreover, the meaning of new paradigm from ITSs to ILE are mentioned under the new technology of networking and multi-media.

For systems in which the probability that an incorrect output is observed differs with input values, we adopt the redundant usage of n copies of identical systems which we call the n-redundant system. This paper presents a method to find the optimal redundancy of systems for minimizing the probability of dangerous errors. First, it is proved that a k-out-of-n redundancy or a mixture of two kinds of k-out-of-n redundancies minimizes the probability of D-errors under the condition that the probability of output errors including both dangerous errors and safe errors is below a specified value. Next, an algorithm is given to find the optimal series-parallel redundancy of systems by using the properties of the distance between two structure functions.

Optical waveguides are one of the key devices for photonic integrated circuits considered to be one of the candidates for optical interconnects. In particular lossless bend type waveguides are necessary to integrate different optical devices monolithically. In this paper, we report on the bending loss characteristics of the multi-quantum well bend waveguide with respect to the bend radius and lateral optical mode confinement. We show that to decrease the bending loss to less than 0.5 dB, it is necessary to increase either the confinement or the bend radius. For an example, when the confinement is around 85%, the bend radius should be more than 2 mm. We also show the application of the S-bend waveguides to directional coupler type optical switch.

This paper presents a novel model of optical associative memory using an optoelectronic neurochips, which detects and processes a two-dimensional input image at the same time. The original point of this model is that the optoelectronic neurochips allow direct image processing in terms of parallel input/output interface and parallel neural processing. The operation principle is based on the nonlinear transformation of the input image to the corresponding the point attractor of a fully connected neural network. The learning algorithm is the simulated annealing and the energy of the network state is used as its cost function. The computer simulations show its usefulness and that the maximum number of stored images is 150 in the network with 64 neurons. Moreover, we experimentally demonstrate an optical implementation of the model using the optoelectronic neurochip. The chip consists of two-dimensional array of variable sensitivity photodetectors with 8 16 elements. The experimental results shows that 3 images of size 8 8 were successfully stored in the system. In the case of the input image of size 64 64, the estimated processing speed is 100 times higher than that of the conventional optoelectronic neurochips.

Koblitz and Miller proposed a method by which the group of points on an elliptic curve over a finite field can be used for the public key cryptosystems instead of a finite field. To realize signature or identification schemes by a smart card, we need less data size stored in a smart card and less computation amount by it. In this paper, we show how to construct such elliptic curves while keeping security high.

This paper describes an error-correcting parser (ec-parser) for context-free languages that is an extension of the Leiss's parser. Since the ec-parser uses precomputed informations and a pruning technique by lookahead, the ec-parser is always faster than the Lyon's parser. Several examples are shown.

The development of highly accurate and durable control system is becoming a must for todays high performance automobiles. For example, it is necessary to up-grade todays materials and methods creating more sensitive sensors, higher speed processors and more accurate actuators, while also being more durable. Thus, the development of a CMOS time-to-digital converter LSI with half-nanosecond resolution, which controls only pulse signals was achieved by employing 1.5 µm CMOS technology. The new signal detecting circuit, 1.1 mm2 in size, converts time to numerical values over a wide measurement range (13 bits). The compact digital circuit employs a newly developed "ring gate delay system". Within the LSI the fully digital circuit is highly durable. This allows it to be utilized even under severe conditions (for example an operating ambient temperature of 130). In order to measure time accurately, a method of correcting the variation of measurement time data employing a real-time conversion fully digital circuit is described. This method allows for fully automatic correction with a microcomputer, so no manual adjustment is required. In addition to sensor circuit applications, the LSI has great potential for Application Specific Integrated Circuit, (ASIC) such as a function cell with is a completely new method of measuring time.