Minimizing queueing delays in computer networks

Ph.DDOCTOR OF PHILOSOPH

Minimum queuing delay: An adaptive algorithm for scheduling in a dynamic job shop

IECON Proceedings (Industrial Electronics Conference)2962-967IEPR

Versorgungsforschung auf dem Gebiet der Geriatrie und geriatrischen Rehabilitation aus nationaler und internationaler Sicht

In this paper, we propose a generalised minimum queuing delay (GMQD) service discipline for high speed networks, mainly asynchronous transfer mode (ATM) networks. This proposed scheme is similar to service disciplines based on fair queuing, but instead of using only a single service rate for each session for its entire connection lifetime, multiple service rates are used. The service rate of any session at any point in time is computed efficiently based on the number of bits backlogged in the queues of the session and another imaginary reference session at that point in time. The main advantage of this scheme is that the queuing delays suffered by all the sessions connected to a single output node are minimised, leading to a smaller delay variation. In addition, this smaller delay variation also implies a smaller variance in the maximum queue length, thereby, reducing the possibility of buffer overflow. Keywords: ATM, scheduling, multi-rate service disciplines I. INTRODUCTION Asynch..

Adaptive range composite differential evolution for fast optimal reactive power dispatch

This paper proposes a novel adaptive range composite differential evolution (ARCoDE) algorithm to efficiently and accurately solve optimal reactive power dispatch (ORPD) problem. Because of a novel adaptive range strategy for control parameters, the proposed ARCoDE possesses superior exploration and exploitation capabilities that can efficiently handle the ORPD problem involving complicated constraints and discrete and continuous variables. This has been demonstrated in case studies using the IEEE optimal power flow testbeds considering complex wind and demand scenarios. The superior performance of ARCoDE has been further validated through comparisons with several award-winning algorithms in 2014 IEEE Competition on “Application of Modern Heuristic Optimization Algorithms for Solving Optimal Power Flow Problems”, given limited iterations of in evolutionary optimization process.Energy Market Authority (EMA)Published versionThis work was supported in part by the National Key Research and Development Program of China under Grant 2019YFB1505400, and inpart by the Energy Market Authority and National Science Foundation Singapore under Grant NRF2017EWT-EP003-038

Reliability importance of renewable energy sources to overall generating systems

Over the years, probabilistic nature of renewable energy sources (RES) and its influence on power system adequacy have been well studied. However, rather less attention has been paid to the impact of RES unit itself’s and its power conversion system’s (PCS’) reliability, as well as their various connection topologies. This paper devises a comprehensive sensitivity study on how each of these elements can affect overall generating system reliability. given the plethora of RES configurations and components, it is of import to identify the most vulnerable element in RES. In this work, component importance is extended, for the first time, to generating capacity adequacy assessment (HLI). Measurement index is the centerpiece in reliability importance. New indices have to be introduced to facilitate the study. While the physical meaning of previously developed indices is lost, in this study indices are proposed based on traditional importance measures, of which the physical meaning are strictly retained and consistent with the definitions. With the proposed assessment technique, components in various RES configuration can be ranked according to their reliability importance. It is found in the numerical study that different importance measures (such as risk-achievement based measures and risk-reduction based measures) can result in different rankings. Studies on contributing factors of the reliability importance are also performed. As more and more RES gaining foothold in generating systems, the proposed technique assist to achieve targeted reliability level of the system, by easily identifying and prioritizing reliability improvement tasks among various units/components in the increasing complex system.Energy Market Authority (EMA)National Research Foundation (NRF)Published versionThis work was supported in part by the Energy Market Authority and National Research Foundation Singapore underGrant NRF2017EWT-EP003-038, and in part by the National Key Research and Development Program of China underGrant 2019YFB1505400

Achieving proportional delay differentiation efficiently

10.1109/ICON.2002.1033306IEEE International Conference on Networks, ICON169-17