Sound field telecommunication describes a voice communication system, intended to implement a virtual meeting, in which participants at distant sites experience the sensation of sharing a single room for conversation. Binaural synthesis reconstructs the sound propagation pattern of a particular room or environment in the vicinity of each ear, which seems appropriate for a personal multimedia environment. Localization cues in spatial hearing comprise both the sink's transfer function and source attenuation. Sink directional cues are captured by binaural head related transfer functions (HRTFs). Source attenuation is modeled as a frequency-independent function of the direction, dispersion, and distance of the source, capturing sensitivity, amplification, and mutual position. Audio windows, aural analogues of video windows, can be thought of as a user interface to binaural sound presentation for a teleconferencing system. Exocentric representation of audio window entities allows manipulation of all teleconferees in a projected egalitarian medium. We are implementing a system that combines dynamically selected HRTFs with dynamically determined source and sink position, azimuth, focus, and size parameters, controlled via iconic manipulation in a graphical window. With such an interface, users may arrange a virtual conference environment, steering the virtual positions of teleconferees.

The new notion of "multiuser interface", an interface for groups working together in a shared workspace, originated from the expansion of CSCW research and the spread of the groupware concept. This paper introduces a new multiuser interface design approach based on the translucent video overlay technique. This approach was realized in the multimedia desktop conference system Team WorkStation. Team WorkStation demonstrates that this translucent video overlay technique can achieve two different goals: (1) fused overlay for realizing the open shared workspace, and (2) selective overlay for effectively using limited screen space. This paper first describes the concept of open shared workspace and its implementation based on the fused overlay technique. The shared work window of Team-WorkStation is created by overlaying translucent individual workspace images. Each video layer is originally physically separated. However, because of the spatial relationships among marks on each layer, the set of overlaid layers provides users with sufficient semantics to fuse them into one image. The usefulness of this cognitive fusion was demonstrated through actual usage in design sessions. Second, the problem of screen space limitation is described. To solve this problem, the idea of ClearFace based on selective overlay is introduced. The ClearFace idea is to lay translucent live face video windows over a shared work window. Through the informal observations of experimental use in design sessions, little difficulty was experienced in switching the focus of attention between the face images and the drawing objects. The theory of selective looking accounts for this flexible perception mechanism. Although users can see drawn objects behind a face without difficulty, we found that users hesitate to draw figures or write text over face images. Because of this behavior, we devised the "movable" face window strategy.

This paper deals with communication model in a software development project when there happens some trouble on it. First, we analyze a communication process in the real projects, and investigate what type of communication exists and which aspect is thought to be important by the members of the projects. Then we propose a communication model based on the analysis. We focus on the communication in case of troubles, and the process is modeled using charge, competence and knowledge of each member in the project. The features of the model lies in the ability to simulate communication route dynamically. The results of the simulation is compared with the real data, and also the use of the model for communication support system is discussed.

The heterointerfaces of Al0.3Ga0.7As/GaAs single quantum wells (SQWs) and the characteristics of SQW lasers grown on Si substrates with Al0.5Ga0.5As/Al0.55Ga0.45P intermediate layers (AlGaAs/AlGaP ILs) entirely by metalorganic chemical vapor deposition (MOCVD) are reported. The effects of thermal cycle annealing on the crystallinity and the lasing characteristics of GaAs/Si are also reported. By using the AlGaAs/AlGaP ILs, SQWs with a specular surface morphology and a smoother heterointerface can be grown on a Si substrate. Thermal cycle annealing is found to improve the crystallinity of GaAs/Si and to contribute to room-temperature continuous-wave operation of lasers on Si substrates. The combinations of the techniques of AlGaAs/AlGaP ILs and thermal cycle annealing improve the lasing characteristics: an average threshold current density of 1.83 kA/cm2, an average differential quantum efficiency of 52%, an internal quantum efficiency of 83%, an intrinsic mode loss coefficient of 23cm-1, a differential gain coefficient of 1.9cm/A, and a transparency current density of 266 A/cm2, which are superior to those of the two-step-grown laser on a Si substrate. The improvements of the lasing characteristics result from the smooth heterointerfaces of the AlGaAs/AlGaP ILs.

The heterointerfaces of Al0.3Ga0.7As/GaAs single quantum wells (SQWs) and the characteristics of SQW lasers grown on Si substrates with Al0.5Ga0.5As/Al0.55Ga0.45P intermediate layers (AlGaAs/AlGaP ILs) entirely by metalorganic chemical vapor deposition (MOCVD) are reported. The effects of thermal cycle annealing on the crystallinity and the lasing characteristics of GaAs/Si are also reported. By using the AlGaAs/AlGaP ILs, SQWs with a specular surface morphology and a smoother heterointerface can be grown on a Si substrate. Thermal cycle annealing is found to improve the crystallinity of GaAs/Si and to contribute to room-temperature continuous-wave operation of lasers on Si substrates. The combinations of the techniques of AlGaAs/AlGaP ILs and thermal cycle annealing improve the lasing characteristics: an average threshold current density of 1.83 kA/cm2, an average differential quantum efficiency of 52%, an internal quantum efficiency of 83%, an intrinsic mode loss coefficient of 23 cm-1, a differential gain coefficient of 1.9 cm/A, and a transparency current density of 266 A/cm2, which are superior to those of the two-step-grown laser on a Si substrate. The improvements of the lasing characteristics result from the smooth heterointerfaces of the AlGaAs/AlGaP ILs.