Information technology equipment connected to telecommunications line can be a source of electromagnetic interference. Two sources of interference have been under evaluation. One is the digital pulses in the switching regulator and the clock oscillator, and the other is the signal's common mode voltage. In this paper, the interference-inducing mechanism for the signal's common mode voltage and a method for measuring the interference are described. An equivalent circuit representing both the equipment and the line is derived on the basis of the interference-inducing model. A method for estimating the signal's common mode voltage from the differential mode voltage and the line unbalance is obtained using the equivalent circuit. It is confirmed that the level difference between the estimated and the measured common mode level is less than 3dB.

The subject of the paper is to analyze time complexity of the minimum axiom set problem (MASHC) in the Horn clause propositional logic. MASHC is defined by "Given a set H of Horn clauses and a query Q, all in propositional logic, such that Q is provable over H, find an axiom set of minimum cardinality, HH, with respect to Q, where Q is provable over H if and only if Q can be shown to be true by repeating Modus Ponens starting from clauses of H under the assumption that all of them are originally assumed to be true". If Q is provable over H then H is called an axiom set (with respect to Q). As stated in the definition of MASHC, detecting if Q is provable over H is required. This leads us to a problem, called the provability detecting problem (PDPHC), defined by "Given a set H of Horn clauses and a query Q in propositional logic, determine if Q is provable over H". First an O(σ) algorithm BFSHC for PDPHC is given based on the breadth-first search, where σ is the formula size of a given set of Horn clauses. For MASHC, it is shown that the problem is NP-complete, and an O(σ) approximation algorithm FMAS is given. Its experimental evaluation is also presented.

The effect of the externally reflected light on the mode partition characteristics of 1.3 µm Fabry-Perot laser diodes is studied experimentally and numerically. It is observed that the k-value increases monotonically with the DC bias current and the external reflection coefficient. Based on these experimental results, a numerical model to study the mode partition characteristics of laser diodes in the presence of external reflections is developed. The results calculated using this model agree well with the experimental ones. It is found that the mode partition noise is mainly caused by the interference between the light in the laser diode and the reflected light, and also by the fluctuations of the induced emission and absorption. In the time domain, their contribution to the mode partition noise is almost localized in the time region within 0.1nsec at the time when the optical pulse turns on.

A new approach is proposed to evaluate total electromagnetic noise radiated from a printed circuit board (PCB), and a result of experimental verification is given. The purpose is to represent the total radiation noise by summing up noises from elemental sources on a PCB, such as signal traces or ICs. Each of the elemental noise is calculated by an a priori noise model for each component of a PCB. Parameters of each noise model should be determined experimentally. Radiation sources on a digital PCB were found to be not only signal traces between ICs, but also package-side loops each of which is composed of an IC and a decoupling capacitor. Radiation noises from these two kinds of sources were evaluated separately. Experimental PCBs, which are two-layer PCBs mounting a few high-speed CMOS (HC) ICs, were prepared and radiation power from them was measured. Each PCB has a ground plane on one side, which simulates an internal ground plane in a multilayer PCB, and signal traces on it have a configuration of a microstrip transmission line. Electromagnetic noise caused by a high-speed CMOS gate is radiated impulsively during transition time as short as about 10ns. No significant interference was found between the noises from separate traces because each of the noise is impulsive and rarely overlaps each other. It is concluded that the total radiated power is represented by a simple sum of radiations from each traces without any interference to be taken into account.

This paper presents an automatic creation method of 3D facial models which are needed for facial image generation by 3D computer graphics. A 3D facial model of a specific person is obtained from just the front and side view images without any human operation. The method has two parts; feature extraction and generic model modification. In the feature extraction part, the regions or edges which express the facial features such as eyes, nose, mouth or chin outline are extracted from the front and side view images. A generic head model is then modified based on the position and shape of the extracted facial features in the generic model modification part. As a result, a 3D model for persons is obtained. By using the specific model and the front and side view images, texture-mapped facial images can be generated easily.

Optical couplers which are composed of three channel waveguides arranged two-dimensionally are investigated numerically. The mode-matching method that matches the boundary conditions in the sense of least squares is applied to this problem, using the hybrid-modal representation. The precise numerical results of the dispersion relations and field distributions are presented for the lowest three modes near the cutoff. The arrangement of three waveguides can be optimized so as to satisfy the condition for maximum power-transfer efficiency.

LOTOS is a language developed within ISO for the formal description of communication protocols and distributed systems. In LOTOS, requirements for a distributed system are called a "service specification". Each node exchanges synchronization messages to ensure the temporal ordering for the execution of events in a service specification. The actions of each node are described as a "protocol specification". This paper gives a survey for a method to derive protocol specifications from a service specification written in a LOTOS based language. In order to derive the protocol specifications, we make the syntax tree of a given service specification and give some attributes for each node in the tree. The protocol specifications are derived automatically by evaluating these attributes. The derived protocol specifications satisfy the given service specification. We also explain a LOTOS simulator for the execution of derived protocol specifications. The related works are also summarized.

It is sometimes required to change the frequency characteristics of a digital filter during its operation. In this paper a new synthesis of variable even-order IIR digital filters is proposed. The cut-off frequency of the filter can be changed by a single parameter. The fundamental filter structure is a cascade of second-order sections. The multiplier coefficients of each section are determined by using the Taylor series expansion of the lowpass to lowpass frequency transformation. For this method any second-order section can be used as a prototype, but here in this paper only the direct form and the lattice form are described. Unlike the conventional method, any transfer functions can be used for the proposed method. Finally a designed example shows that the proposed filter has wider tuning range than the conventional filter, and the advantage of the proposed filters is confirmed.

Splice Loss of LP modes in multimode graded-index optical fibers is investigated. It becomes clear that splice loss of particular mode and the excitation rate of the other modes by mode conversion is predicted from the factor, e.g. fiber axis misalignment, fiber and face gap, end fiber end face inclination.

A layout system for mixed analog/digital standard cell LSI's is described. The system includes interactive floorplan and placement features and automatic global and channel router. In mixed analog/digital circuits, crosstalk noise causes chip performance degradation. Thus, the proposed global routing algorithm routes analog nets in areas that are free of digital nets as much as possible. The number of line crossovers, especially for analog nets, is minimized by both global and detailed routers, because these crossovers are the dominant factors in the crosstalk noise. Double width lines can be used to avoid unexpected voltage drops caused by parasitic resistances. A postprocess automatically puts up shield lines for very noise sensitive wirings to improve the S/N ratio. Experimental results show that the proposed algorithms are effective in reducing the number of crossovers and redundant vias.

New methods are needed for accessing very large information services. This paper proposes the use of a user model neural network to allow better access to a news service. The network is constructed on the basis of articles read, and articles marked as rejected. It adapts over time to better represent the user's interests and rank the articles supplied by the news service. Using an augmented keyword search we can also search for articles using keywords in conjunction with the user model neural network. Trials of the system in a USENET news environment show promising results for the use of this approach in information retrieval.

An automatic optimization system for semiconductor devices has been built-up by fully interfacing an optimizer and a device-analysis code supplemented with sensitivity analysis. The device-analysis code is thought of as a part of a pipeline of simulators. The latters are regarded as subprocesses by the optimizer, which controls their I/O stream. The action of the pipeline is iterated until the optimum set of design parameters is determined. An important feature of the system is that all the derivatives required in the sensitivity analysis are calculated analytically, this providing a substantial improvement in both the numerical accuracy and computational efficiency, and making the scheme attractive from the application standpoint. A few examples of optimization of MOS devices are shown and the performance is reported, indicating that a system of this kind can usefully be exploited in a design environment.

Suppose that there are terminals on two concentric circles, Cin and Cout, with Cin inside of Cout. We are given a set of nets each of which consists of a terminal on Cin and a terminal on Cout. The routing area is the annular region between the two circles. In this paper, we present an O(nk-1) time algorithm for testing whether the given net set is k-layer routable without vias, where k2 and n is the number of nets.

The groupware for new idea generation system, GUNGEN, has been developed. GUNGEN consists of a distributed and cooperative KJ method support system and an intelligent productive work card support system. The system was implemented on a network consisting of a number of personal computers. The distributed and cooperative KJ method is carried out on computers. The ideas proposed by participants are classified into several groups on the basis of similarity and then a conclusion is derived. The intelligent productive work card support system can be used as a multimedia database to refer to the previous data of the distributed and cooperative KJ method.

The objective of this paper is to provide an overview of the recent developments in the area of speech processing and in particular in the fields of speech coding and speech recognition. The speech coding review covers DPCM coders, model-based vocoders, waveform coders, and hybrid coders. The hybrid coders are described in some detail since they are the subject of current research. Our treatment of speech recognition techniques concentrates on the methodologies for voice recognition and the progress made in speaker independent recognition. In addition, we describe the efforts towards commercial deployment of this technology.

In this paper, a "hydrodynamic" version of the three-dimensional code HFIELDS-3D is used to achieve a detailed knowledge on the distribution of the substrate current inside a recessed-oxide MOSFET. The physical model features a temperature-dependent formulation of the impact-ionization rate, allowing non-local effects to be accounted for. The discretization strategy relies on the Box Integration scheme and uses suitable generalizations of the Scharfetter-Gummel technique for the energy-balance equation. The simulation results show that the narrow-channel effect has a different impact on drain and substrate currents. Further three-dimensional effects, such as the extra heating of the carriers at the channel edge, are demonstrated.

We present schemes for disseminating information in the n-dimensional hypercube with some faulty nodes/edges. If each processor can send a message to t neighbors at each round, and if the number of faulty nodes/edges is k(kn), then this scheme will broadcast information from any source to all destinations within any consecutive n+[(k+l)/t] rounds. We also discuss the case where the number of faulty nodes is not less than n.

A new monolithic transmit-receive GaAs FET switch has been developed, named the FET series-shunt connected TR switch and capable of switching high rf transmitting power. Both insertion loss and isolation limitations of this type TR switch have been analyzed using the switching cutoff frequency of the control FET, and the formula for calculating the rated power is provided. A unique feature of this switch is that the power handling of the switch is not limited by the FET gate break-down voltage but is limited by the saturation current, so higher handling power capability is available by using FETs with a larger gate periphery. A design example of the TR switch at a rated power of 8 W in the transmit mode as well as the results of an X band switch are presented.

In the delayed regulation medel, X(t+1)=AX(t){1-X(t-1)}, new bifurcation regions which have been overlooked in the past studies were found out for -1.01A0 and 2.27563A2.2838. In the former fixed point lying at 0 is destabilized at A=-1, and new type bifurcation is induced for A-1, where oscillation with saw-tooth waveform is observed. In the latter the stability once lost for A2.271 is restored for A2.27563, and the stable region continues up to A=2.2838.