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.

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.

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.

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.

It has been recognized that there exist some disparities between properties of continuous control systems and those of discrete ones which are obtained from their continuous counterparts by use of a sampler and zero order hold. This still remains true even if the sampling rate becomes fast enough and sometimes causes unfavorable effects in control systems design. To reconcile with this conflict, use of delta operator has been proposed in place of z-operator recently. This note formulates a delta domain Lyapunov matrix equation and shows that the equation actually mediates the discrete Lyapunov equation and its continuous counterpart.

We have developed an efficient general-purpose two-dimensional device simulation system which consists of a solver, and pre- and post-processors. This system can easily handle any complicated device having a non-rectangular shape. It can also be applied to compound semiconductor devices with heterojunctions, including optical devices such as laser diodes. In order to handle any device, a new program for construction of device geometry is developed as a preprocessor. It has an efficient graphic interface to reduce the time required to input data for simulations, which is a very time consuming task for complicated devices. A new efficient data structure representing device geometry is introduced in the program. During postprocessing, any physical quantity can be displayed on the multi-window screen. In addition, a general-purpose solver for basic semiconductor equations is implemented in the system. Using this system, any device can be successfully analyzed in a unified manner and the turn-around time for the simulation is significantly reduced.

Theoretical network analysis of a network constructed of "Interconnectable Star Couplers" whose all diagonal elements of transmission matrix are zero is investigated. Under certain connection rules, Interconnectable Star Coupler can be connected each other without oscillation and ghost formation. The rules are: (1) Network should not contain any loop. (2)Only single port pair should be connected between neighbor star couplers. (3)Network shold not contain any usual star coulpler. "Coupled Star Network", which is constructed under the connection rules, is able to form Cascade Star topology, Stratified Star topology and their mixed topology. It is shown that the Coupled Star Network is equivalent to a large Interconnectable Star Coupler so that bidirectional communication, which can add confidentiality to the broadcasting bus and doubles communication capacity, is available. A new configuration of Coupled Star Network using passive Interconnectable Star Couplers and optical amplifiers is proposed. This network has two separated bidirectional communication channel which can be applied for so-called Multimedia LAN. As a result of comparison between Cascade Star topology and Stratifide Star topology, it is shown that the latter topology is superior to former topology, from the view point of signal degeneration and maximum round trip delay time. Cascade Star topology, however, is superior to Stratified Star topology from the angle of total fiber length. Accordingly, optimized network topology is thought to be mixed topology of these.

In two-dimensional simulation of thin-base RHET, we combined three different simulation methods--the Schrödinger equation, the Monte Carlo simulation, and two-dimensional device simulation within a drift and diffusion model. We found that, in the thin-base RHET, the potential distribution differs from that expected from the thick-base RHET. In the thin-base RHET, the potential of the intrinsic base region does not equal that of the base electrode because the intrinsic base region is depleted and the negative emitter voltage (VEB0) raises the potential of both the intrinsic base and the nondoped region under the intrinsic base. There are also modified by the collector voltage. We also show emitter current-voltage characteristics, transfer ratio, and transit time calculated using this method and compare them with results for the one-dimensional case.

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.

In the coming information society, people will have to be engaged in the information environment for their everyday activities. We propose a new design concept of Contextual Metaphors for constructing a human interface. It introduces multiple metaphors and makes it easy for people to directly participate into the environment. The major part of the concept is to provide good contextual support for their everyday activities with a layered design of three cognitively distinct concepts. They are the use of everyday based object metaphors, the task oriented assignment of each of metaphors to system functions and the scenario based sequencings of scenes of those metaphors. A prototyping of the concept showed effectiveness of the concept together with some remarks on the actual design.

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 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.

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.

Binaural effects in two measures are studied. One measure is the detectable limen of click sounds under lateralization of diotic or dichotic noise signals, and the other is phoneme articulation score under localization or lateralization of speech and noise signals. The experiments use a headphones system with listener's own head related transfer function (HRTF) filters. The HRTF filter coefficients are calculated individually from the impulse responses due to the listener's HRTF measured in a slightly sound reflective booth. The frequency response of the headphone is compensated for using an inverse filter calculated from the response at the subject's own ear canal entrance point. Considering the speech frequency band in tele-communication systems is not sufficiently wide, the bandwidth of the HRTF filter is limited below 6.2 kHz. However, the experiments of the localization simulation in the horizontal plane show that the sound image is mostly perceived outside the head in the simulated direction. Under simulation of localization or lateralization of speech and noise signals, the phoneme articulation score increases when the simulation spatially separates the phonemes from the noise signals while the total signal to noise ratio for both ears is maintained constant. This result shows the binaural effect in speech intelligibility under the noise disturbance condition, which is regarded as a part of the cocktail party effect.

Modeling and numerical simulation of crystal growth of Si film and heat transport in 3D structure were made for optimization of physical and geometrical parameters used during laser recrystallization. Based on simulations a new concept called micro-absorber was introduced for obtaining defect-free Si films.

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.

To realize a highly efficient small antenna, high-Tc superconductors are adopted to fabricate both a self-resonating helical radiator and a quarter-wave matching circuit. The actual gain and bandwidth measured at 478 MHz using a 1/45-wavelength radiator were respectively 1.5 dBi and 0.35%, indicating that this type of antenna has a high radiation efficiency and a fairly wide bandwidth. It is also confirmed through experiments and theoretical simulations that a decrease in the surface resistance of the radiator more effectively improves the radiation efficiency than a decrease in the surface resistance of the matching circuit.

In this paper, a three part algorithm is employed to obtain stable convergence during stress dependent oxidation simulation using the finite element method is presented. By introducing (1) a reduced integration formulation, (2) an averaging procedure for the mid-side node velocities at the Si/SiO2 interface, and (3) a three-node element to discretize the oxidant diffusion equation, major improvements in achieving stable convergence are realized during stress dependent oxidation simulation. This technique is generally applicable for an oxidation simulator using the finite element method.

Low-field mobilities and velocity versus electric field relations are among the key input parameters for drift-diffusion simulations of field-effect and bipolar transistors. For example, most device simulations that treat scattering from ionized impurities contain mobilities or velocity versus field relations based on the Born approximation (BA). The BA is insensitive to the sign of the charged impurity and is especially poor for ionized impurity scattering because of the relatively strong scattering of long-wavelength carriers, which have low energies, and therefore violate the validity condition for the BA. Such carriers occur at high symmetry points in the Brillouin zone and are critical for device behavior. There has been a tendency in the past to assume that majority and minority mobilities are equal. This assumption can lead to incorrect interpretations of device data and thereby misleading design strategies based on such simulations. We have calculated the majority electron and minority hole mobilities in GaAs at 300 K for donor densities between 51016 and 11019 cm-3 and the majority hole and minority electron mobilities for acceptor densities between 51016 and 11020 cm-3. We have included all the important scattering mechanisms for GaAs: acoustic phonon, polar optic phonon, nonpolar optic phonon (holes only), piezoelectric, ionized impurity, carrier-carrier, and plasmon scattering. The ionized impurity and carrier-carrier scattering processes have been calculated with a quantum mechanical phase-shift analysis to obtain more accurate matrix elements for these two scattering mechanisms. We compare the total scattering rate for majority electrons due to ionized impurities based on exact phase shifts and on the BA used by Brooks-Herring. We also present additional data that show the differences between the exact phase-shift analyses and the BA for majority electron scattering rates as functions of carrier energy and scattering angle. These results show that the calculated low-field mobilities are in good agreement with experiment, but they predict that at high dopant densities minority mobilities should increase with increasing dopant density for a short range of densities. This effect occurs because of the reduction of plasmon scattering and the removal of carriers from carrier-carrier scattering because of the Pauli exclusion principle. Some recent experiments support this finding. These results are important for device modeling because of the need to have reliable values for the minority mobilities and velocity-field relations.