The controllability and the stability of the blood clotting system are examined with the linear system analysis. The dynamic behavior of the clotting system consisting of a cascade of ten proteolytic reactions of the clotting factors with multiple positive feed back and feed forward loops is represented by the rate equations in a system of non linear ordinary differential equations with 35 variables. The time courses of concentration change in every factor are revealed by numerical integration of the rate equations. Linearization of the rate equations based on the dynamic behavior of the chemical species relevant to the nonlinear terms leads to the linear systems analysis of the clotting system to clarify the essential features of blood coagulation. It follows from the analysis that the clotting system is uncontrollable regardless of changes in any system parameters and control input and that all the chemical species of the system are uncontrollable so that the sequential reactions in the cascade proceed irreversibly, once they are activated. More over by the analysis of the eigen values, the clotting reaction as a total system was shown to be unstable which was insensitive to changes in the system parameters. These characteristic natures of clotting system must be derived in the sequential cascade reaction pattern and the inherent multiple positive feed back and feed forward regulation.

It is important to analyze a tracking or synchronizing process in Spread Spectrum (SS) receiving system. The most common SS tracking system considered here consists of pseudorandom (PN) generator, Lowpass Filter (LPE) and Voltage Controlled Oscillator (VCO). The SS receiver is to track or synchronize its local PN generator to the received PN waveform by VCO. The fundamental equation of the system is known by a second order nonlinear differential equation in terms of phase difference between local PN generator and received PN waveform. The differential equation is nonautonoumous due to PN function of time t with period T. Picking up the gain of VCO as the main parameter in the system we show that the system has bifurcation from the normal oscillation through subharmonic oscillation to finally chaos. In the final case, chaos is confirmed by investigating maximum Liapunov number and both stable and unstable manifolds.

On a simple model, the quality of the security tag is simulated theoretically and experimentally. A simple correction makes both results correspond exactly and a simulation formula is provided. By using novel insulating film, a small-sized tag of high quality is developed.

This paper proposes a new multistage switch architecture for large-scale multicast ATM switching. The proposed architecture uses routing schemes both at the connection level and the cell level. This results in the reduction of the memory capacity required in the trunk number translators of the copy network modules. If Connection Splitting algorithm is used, a nonblocking switch can be constructed under the same nonblocking condition as that of point-to-point Clos network. It is shown that the memory requirements in the new switching network are less than the previous architectures.

This paper presents a new learning method to improve noise tolerance in Fuzzy ART. The two weight vectors: the top-down weight vector and the bottom-up weight vector are differently updated by a weighted sum and a fuzzy AND operation. This method effectively resolves the category proliferation problem without increasing the training epochs in noisy environments.

The complex refractive indices n-jχ of typical magnetic fluids were evaluated for the sake of utilizing them as optical materials. Transmission and reflection spectra were measured in the wavelength range of 0.6-1.6 µm by using monochromators. Magnetic fluids were put into glass cells of 2.5-14-µm thickness for transmission measurement. Due to the absorption by magnetic fluids, the transmittance decreased notably with the increase of the sample thickness. The extinction coefficient χ was evaluated from the dependence of the transmittance on the sample thickness. χ was found to vary between 0.003 and 0.03 depending upon wavelength. The refractive index n was evaluated by fitting theoretical curves to the reflectances that were measured for various incident angles. n was found to vary between 1.6 and 1.7 depending slightly on wavelength. Since a magnetic fluid is a composite of ferrite particles and a solvent, the refractive index can be calculated by using the effective medium theory. The calculated value agreed well with the experimental value. Preliminary experiment of optical switching was also demonstrated by utilizing the mobility of a magnetic fluid.

Portable terminals have the potential of providing information and communication services not only to computer experts at their offices but also to many users being in a variety of daily life situations. The current user interfaces (UIs) of portable terminals are not suitable for a novice user of computers; they require some knowledge on computers from a user. To overcome this problem, the authors tried to implement their knowledge on the daily life in the design of a UI for novice users. As a result, two UI mechanisms, called Novice Interface and Graphical Metaphor Interface, which provide operations, expressions, and data structures in a way similar to those usually used in daily life are proposed. Novice Interface is to provide easy to use environment. It adopts a direct manipulation device with three buttons and a model of data structures, called Small World Model, that limits the number of functions and the depth of hierarchical menu. Graphical Metaphor Interface, being an extension of Novice Interface, is to provide services with a display screen that makes them well-understandable for any user. The proposed UI mechanisms were implemented in a prototype terminal and its software platform. The former offers several applications of the information services (like teleshopping, home banking, or database retrieval) and the communication services (like pen-based image mail, software fax, or telewriting); the latter enables those application programs to provide a consistent UI.

Dynamic Programming based elastic pattern matching method called Branched Reference Rubber String Matching was investigated. As in Rubber String Matching, the reference pattern is represented as a sequence of direction specified vectors and the input pattern as two dimensional dot pattern. In order to improve the coping of topological variations in input pattern, the reference patterns allow partial pattern alternatives and misses. Effect on the recognition time is almost negligible. Experimental results show the effectiveness of the proposed algorithm.

This paper proposes a masked data transferring method for the write-back controlled disk cache system employing a fixed-length recording disk drive, enabling data transfer of discontinuous sectors on the same track between the cache and the disk. This paper also evaluates the method. In write-back controlled disk cache sytems, random write requests cause dirty data (write-pending data on a cache) on discontinuous areas on the cache. It is likely that several sectors on the same track become dirty. These dirty sectors must be written onto the disk according to the cache management scheme. In conventional data transferring methods between a disk cache and a disk drive, plural sectors can be transferred in one single operation when the sectors are adjacent, but discrete sectors must be transferred by individual operations. In the methods, an address of the head sector and number of sectors to be transferred are given to the transfer unit. For example, when two sectors on the same track are located closely but not adjacently, and data transfer is requested for those two sectors, the transfer operation for the second sector must be prepared after the first transfer had completed and before the second sector arrives under the disk head. Although the time for the head to pass by the uninterested sector is often too short for the software overhead for the first transfer to be completed and the second transfer to be prepared, which leads to an unwanted extra rotation of the disk. With the masked transferring method proposed in this paper, the micro program creates a bit-map specifying the target sectors to be transferred and passes it to the data transfer unit, enabling to transfer the discontinuous sectors without latency. The method was evaluated using OLTP warkloads. Results show an improvement in random I/O throughput of between 8% and 27%. The masked transferring method is adopted in Hitachi's A-6521 disk subsytems, shipped since December 1993.

A new algorithm for multiple-precision modular multiplication is proposed. It is fast and uses a small amount of main memory, and hence, is useful for application of a public-key cryptosystem to small computers, such as card computers.

Theoretically, corresponding pairs of feature points between two stereo images can determine their 3-D locations uniquely by triangulation. In the presence of noise, however, corresponding feature points may not satisfy the epipolar equation exactly, so we must first correct the corresponding pairs so as to satisfy the epipolar equation. In this paper, we present an optimal correction method based on a statistical model of image noise. Our method allows us to evaluate the magnitude of image noise a posteriori and compute the covariance matrix of each of the reconstructed 3-D points. We demonstrate the effectiveness of our method by doing numerical simulation and real-image experiments.

We present basic strategies for memory-restricted forgetting mechanisms of cases and propose a forgetting strategy which is a combination of the basic strategies. The effectivness of the proposed strategy for improving the performance of case-based reasoning systems is demonstrated through simulations in the electric power systems.

In this study, we propose a system of N Wien-bridge oscillators with the same natural frequency coupled by one resistor, and investigate synchronization phenomena in the proposed system. Because the structure of the system is different from that of LC oscillators systems proposed in our previous works, this system cannot exhibit N-phase oscillations but 3-phase and in-phase oscillations. Also in this system, we can get an extremely large number of steady phase states by changing the initial states. In particular, when N is not so large, we can get more phase states in this system than that of the LC oscillators systems. Because this system does not include any inductors and is strong against phase error this system is much more suitable for applications on VLSI compared with coupled system of van der Pol type LC oscillators.

A folded short in parallel-plate waveguide is investigated using the Fourier transform and the mode-matching. A fast-converging series solution for scattering from the folded short is obtained and its characteristics are presented. Our solution for the E-plane short agrees well with measurements and is numerically more efficient than the existing moment-method solution. The presented scattering characteristics are useful for the design of the E- and H -plane shorts in rectangular waveguide.

A hybrid analysis of the electromagnetic scattering by an open cavity containing an interior obstacle when it is illuminated by an external source is presented so that it is valid for high frequencies. This hybrid approach breaks down the problem into three basic parts which can be analyzed separately, via methods best suited for each part, and these separate solutions are then combined systematically via generalized recipricity relations to obtain the total solution. The three separate analyses deal with the scattering by the open end being illuminated, the wave propagation within the cavity, and the scattering by the interior obstacle. The propagation region analysis is based on the use of the generalized ray expansion that employs a new elliptic ray tube basis set which makes this expansion far more efficient in that it requires significantly fewer number of these than is possible with conventional ray tubes. Numerical results illustrating the utility of this hybrid approach are presented.

In this paper, a new optimum input encoding algorithm with m-out-of-2m code which is called Half-Hot Code is presented. By applying Half-Hot Code to the input encoding in PLA-based digital system, the logic functions of the system turn out to be unate functions, thus, the number of bit-lines of PLA may be reduced. The proposed method further reduces the number of product-lines of PLA optimally. In this code assignment procedure, computed Boolean subspaces satisfying suggeset two conditions are assigned to each partitioned subset of digital input variables which are obtained by disjoint minimization or other techniques. As an experiment to evaluate the method, the state assignment for finite state machines of two-lavel implementation is considered. Specifically, the proposed Half-Hot Code assignment is compared with arbitrary Half-Hot Code assignment. The results show that the optimum encoding is superior to an arbitrary assignment up to about 24% in the number of product-lines of PLA.

The integration of both real-time systems and fault-tolerant systems has been emerged as one of the greatest challenges of this decade. It is called a responsive system, which has the objective to optimeze both timeliness and reliability. The performance measure in responsive systems is responsiveness that tells how probable a system executes correctly on time with faults occurred. While there have been some achievements in communication protocols and specification, we believe that scheduling problems in responsive systems are not understood deeply and sufficiently, yet. In this paper, we discuss the scheduling problem in responsive systems. At first, we investigate the issues in the scheduling and propose the precise definition of the responsiveness. We also suggest a scheduling algorithm called Responsive Earliest Deadline First (REDF) for preemptive aperiodic tasks in a uniprocessor system. We show that REDF is optimal to obtain the maximum responsiveness, and the time complexity is analyzed to be (N 2N). By illustrating a contradictory example, it is shown that REDF can be enhanced if a constraint on tasks is released.

In this paper, we propose algorithm of deterministic nonlinear prediction, or a modified version of the method of analogues which was originally proposed by E.N. Lorenz (J. Atom. Sci., 26, 636-646, 1969), and apply it to the artificial time series data produced from nonlinear dynamical systems and further corrupted by superimposed observational noise. The prediction performance of the present method are investigated by calculating correlation coefficients, root mean square errors and signature errors and compared with the prediction algorithm of local linear approximation method. As a result, it is shown that the prediction performance of the proposed method are better than those of the local linear approximation especially in case that the amount of noise is large.

This paper discusses crystal-growth and device-design issues associated with the development of high-performance InP/InGaAs heretostructure bipolar transistors (HBTs). It is shown that a highly Si-doped n+-subcollector in the HBT structure causes anomalous Zn redistribution during metalorganic vapor phase epitaxial (MOVPE) growth. A thermodynamical model of and a useful solution to this big problem are presented. A novel hybrid structure consisting of an abrupt emitter-base heterojunction and a compositionally-graded base is shown to enhance nonequilibrium base transport and thereby increase current gain and cutoff frequency fT. A double-heterostructure bipolar transistor (DHBT) with a step-graded InGaAsP collector can improve collector breakdown behavior without any speed penalty. We also elucidate the effect of emitter size shrinkage on high-frequency performance. Maximum oscillation frequency fmax in excess of 250 GHz is reported.

This paper describes, from a system architectural viewpoint, how knowledge-based technologies have been utilized in developing EXLOG (an LSI circuit synthesis system) and SOFTEX (a software synthesis system) inside the authors' projects. Although the system architectures for EXLOG and SOFTEX started from the same production systems, consisting of transformation rules in the middle of the 1980's, both branched off in different directions in the 1990's. Based on experiences with EXLOG and SOFTEX, the differences between LSI and software design models are discussed, and the future directions are indicated for the knowledge-based design system architectures.