Services for activities in group editing 'sage'

The project described in this thesis investigates the needs of a group of people working cooperatively in an OSI environment, and recommends tools and services to meet these needs. The project looks specifically at Services for Activities in Group Editing, and is identified as the `SAGE' project. The project uses case studies to identify user requirements and to determine common functionalities for a variety of group editing activities. A prototype is implemented in an X.400 environment to help refine user requirements, as a source of new ideas and to test the proposed functionalities. The conceptual modelling follows current CCITT proposals, but a new classification of group activities is proposed: Informative, Objective and Supportive application groups. It is proposed that each of these application groups have their own Service Agent. Use of this classification allows the possibility of developing three sets of tools which will cover a wide range of group activities, rather than developing tools for individual activities. Group editing is considered to be in the Supportive application group. A set of additional services and tools to support group editing are proposed in the context of the CCITT draft on group communication, X.gc. The proposed services and tools are mapped onto the X.400 series of recommendations, with the Abstract Service Definition of the operational objects defined, along with their associated component files, by extending the X.420 protocol functionality. It is proposed that each of the Informative, Objective and Supportive application groups should be implemented as a modified X.420 inter-personal messaging system.

Impact of the carrier relaxation paths on two-state operation in quantum dot lasers

We study InGaAs QD laser operating simultaneously at ground (GS) and excited (ES) states under 30ns pulsed-pumping and distinguish three regimes of operation depending on the pump current and the carrier relaxation pathways. An increased current leads to an increase in ES intensity and to a decrease in GS intensity (or saturation) for low pump range, as typical for the cascade-like pathway. Both the GS and ES intensities are steadily increased for high current ranges, which prove the dominance of the direct capture pathway. The relaxation oscillations are not pronounced for these ranges. For the mediate currents, the interplay between the both pathways leads to the damped large amplitude relaxation oscillations with significant deviation of the relaxation oscillation frequency from the initial value during the pulse.