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.

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.

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.

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.

In speech output expected as an ideal man-machine interface, there exists an important issue on emotion production in order to not only improve its naturalness but also achieve more sophisticated speech interaction between man and machine. Speech has two aspects, which are prosodic information and phonetic feature. For the purpose of application to natural and high quality speech synthesis, the role of prosody in speech perception has been studied. In this paper, prosodic components, which contribute to the expression of emotions and their intensity, are clarified by analyzing emotional speech and by conducting listening tests of synthetic speech. The analysis is performed by substituting the components of neutral speech (i.e., one with no particular emotion) with those of emotional speech preserving the temporal correspondence by means of DTW. It has been confirmed that prosodic components, which are composed of pitch structure, temporal structure and amplitude structure, contribute to the expression of emotions more than the spectral structure of speech. The results of listening tests using prosodic substituted speech show that temporal structure is the most important for the expression of anger, while all of three components are much more important for the intensity of anger. Pitch structure also plays a significant role in the expression of joy and sadness and their intensity. These results make it possible to convert neutral utterances into utterances expressing various emotions. The results can also be applied to controlling the emotional characteristics of speech in synthesis by rule.

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.

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.

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 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.

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.

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.

We present a new apparent bandgap narrowing model for semiconductor device simulation. The new model is derived from revised data of previous measurements on the apparent bandgap narrowing by using a corrected intrinsic carrier concentration. The revised values reveal sufficient agreement with our theoretical calculation. The new model is implemented in a triangular mesh device simulator TRIMEDES. Simulated BJT current-voltage and current-temperature characteristics using the proposed model reveal excellent agreement with measurements.

This work describes a new analytical MOSFET model for analog circuit simulation based on the charge-sheet model. The current equation consists of diffusion and drift components, therefore Ids is a smooth function of the applied voltages. Since the original charge-sheet model is valid only for long-channel transistors, it has been further developed to describe quarter-micron MOSFETs by introducing the lateral electric field Ey into the theory. The new model includes these field contributions self-consistently, and describes the drain current of MOSFETs from long to quarter-micron channel lengths with a single model parameter set without discontinuities in derivatives of the drain current Ids. The mobility reduction due to Ey is described by an empirical equation with physical parameter values taken from literature. Only two fitting parameters, the impurity scattering and the surface roughness scattering in the mobility equation, are added to the physical parameters. The subdiffusion lengths are also taken as fitting parameters. Though the new model reduces the number of fitting parameters totally to four, it reproduces measured Ids excellently for MOSFETs with all channel lengths. The model has been included in the parameter extraction program JANUS, which extracts model parameters automatically. The algorithm for parameter extraction is summarized.

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.

This paper is concerned with the stress simulation of a LOCOS structure during not only oxidation but also the subsequent cooling down based on viscoelastic stress modeling. A viscoelastic model is successfully applied to the oxide, nitride and silicon substrate for a LOCOS structure. Thermal stress is also taken into account during the cooling down process. The viscoelastic deformation problem of all the three materials for the LOCOS structure are solved by a two-dimensional finite element method. It is the first time to show that the stress values after cooling down to room temperature are much higher than those right after oxidation. It is also shown that varying the cooling down rates results in the different stress values after cooling down.

In recent years, ion implantation has become one of the key techniques in semiconductor fabrication. The annealing of the damage produced during implantation is, however, not fully understood. Ion implantation at high temperatures allows the time-resolved study of implantation-enhanced diffusion. During the process, point defects are generated by the ion implantation and consumed by recombination in the bulk as well as by diffusion to the surface and recombination there. With increasing temperatures, the recombination of point defects, which are acting as diffusion vehicles, results in reduced effective diffusion. Profiles processed above 900 show marked uphill diffusion at the surface caused by large gradients of the point defect concentrations. This uphill diffusion affirms the generally accepted pair diffusion theories. Since the point defects are in steady state even after process times which are short compared to the total process time, we are able to give a qualitative analysis of the dose dependence of the diffusion. By extensive numerical simulations, we could estimate the product of bulk recombination rate and equilibrium concentrations of self-interstitials and vacancies as well as the interface recombination velocity for the self-interstitials. The results obtained are in qualitative agreement with previous work of others. The results demonstrate, in fact, clearly the advantages of the method presented. But due to experimental problems concerning the temperature measurement, which have not been fully resolved up to now, the results have to be considered as crude estimates.

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.

We have developed a new model to analyze the thermal failure mechanism due to electrical-over-stress (EOS) for two-dimensional planar pn-junction structures where the failure power is proportional to about 1/5 power of the failure time. We adopted a pseudo two-dimensional numerical simulation method where a pn-junction diode is divided into small elements and represented by a circuit network composed of many minute resistors and diodes. The failure mechanism studied by Wunsch and Bell, that is one of many studies for one-dimensional pn-diodes, is not valid for the case of two-dimensional pn-junction, such as a planar type junction. On the contrary, the failure mechanism was found to be much correlative with the junction structure, especially the impurity concentration in the substrate in the two-dimensional case. When the impurity concentration in the substrate is high enough (e.g. Nsub1017[cm-3]), the breakdown occurs at the whole junction. The heat transfer is one-dimensional and the failure power is proportional to about 1/2 power of the failure time, which is well known results reported by many researchers: e.g. Wunsch &Bell. On the other hand, when the impurity concentration in the substrate is low enough (e.g. Nsub1016[cm-3]), the breakdown occurs locally at the junction edge. The heat transfer is two-dimensional and the failure power is in proportion to about 1/5 power of the failure time.

Transmittance distribution along a horizontal line in LCDs addressed by amorphous silicon TFTs was investigated using measurements and calculations. Nonuniformity of the distribution, in which the transmittance increased with increasing distance from the left edge of the LCD, was observed in a 10 inch diagonal TFT-LCD. The cause of the nonuniformity was attributed to the decrease in voltage drop due to the gate source parasitic capacitance and the increase in gate voltage fall time due to large line resistance, based on the measurements of voltage drops in TFT test elements and calculations considering the decrease in voltage drop. The distribution could be improved by reducing the line resistance and parasitic capacitance in the actual LCD.

A fast Viterbi decoding technique with path reduction in optical channels is presented. This decoding exploits the asymmetric characteristic of optical channels. In the decoding trellis, the branches with low or no possibility being correct path are eliminated based on the detected signal level. The number of Add-Compare-Select (ACS) operations which occupy the dominant part of Viterbi decoding is considerably reduced due to branch eliminations, and fast decoding is realized by decoding asynchronously to received sequence. The reduction of the number of ACS operations is derived for the codes with rate 1/2. It is shown that the number of ACS operations is considerably reduced compared with the conventional Viterbi decoding. The bit error probability of the proposed decoding is derived for noiseless photon counting channel. It is also shown that the decoding technique can be applied to the cases using avalanche photo diode (APD) based receiver with dark current noise at a cost of negligible degradation on the bit error probability.