Directed Transmission Method, A Fully Asynchronous approach to Solve Sparse Linear Systems in Parallel

In this paper, we propose a new distributed algorithm, called Directed Transmission Method (DTM). DTM is a fully asynchronous and continuous-time iterative algorithm to solve SPD sparse linear system. As an architecture-aware algorithm, DTM could be freely running on all kinds of heterogeneous parallel computer. We proved that DTM is convergent by making use of the final-value theorem of Laplacian Transformation. Numerical experiments show that DTM is stable and efficient.Comment: v1: poster presented in SPAA'08; v2: full paper; v3: rename EVS to GNBT; v4: reuse EVS. More info, see my web page at http://weifei00.googlepages.co

Cycle-accurate evaluation of reconfigurable photonic networks-on-chip

There is little doubt that the most important limiting factors of the performance of next-generation Chip Multiprocessors (CMPs) will be the power efficiency and the available communication speed between cores. Photonic Networks-on-Chip (NoCs) have been suggested as a viable route to relieve the off- and on-chip interconnection bottleneck. Low-loss integrated optical waveguides can transport very high-speed data signals over longer distances as compared to on-chip electrical signaling. In addition, with the development of silicon microrings, photonic switches can be integrated to route signals in a data-transparent way. Although several photonic NoC proposals exist, their use is often limited to the communication of large data messages due to a relatively long set-up time of the photonic channels. In this work, we evaluate a reconfigurable photonic NoC in which the topology is adapted automatically (on a microsecond scale) to the evolving traffic situation by use of silicon microrings. To evaluate this system's performance, the proposed architecture has been implemented in a detailed full-system cycle-accurate simulator which is capable of generating realistic workloads and traffic patterns. In addition, a model was developed to estimate the power consumption of the full interconnection network which was compared with other photonic and electrical NoC solutions. We find that our proposed network architecture significantly lowers the average memory access latency (35% reduction) while only generating a modest increase in power consumption (20%), compared to a conventional concentrated mesh electrical signaling approach. When comparing our solution to high-speed circuit-switched photonic NoCs, long photonic channel set-up times can be tolerated which makes our approach directly applicable to current shared-memory CMPs

DSL-based triple-play services

This research examines the triple play service based on the ADSL technology. The voice over IP will be checked and combined with the internet data by two monitoring programs in order to examine the performance that this service offers and then will be compared with the usual method of internet connection.This research examines the triple play service based on the ADSL technology. The voice over IP will be checked and combined with the internet data by two monitoring programs in order to examine the performance that this service offers and then will be compared with the usual method of internet connection.

Diakoptic assessment of power system voltage variations and applications in weak grids introduced by wind energy – The Nigerian power system in perspective

The electrical power system is a large interconnected system made up of electrical components to generate, transport and utilize electrical power. The size and complexity of the power system have increased significantly in recent years due to the introduction of wind energy and other renewable energy sources. Hence there is an urgent need to search for new or improved analytical tools for the system performance evaluation and assessment. Load flow analysis is the most important method of assessing the steady-state behaviour of all the components of the power network. The common approach in load flow analysis is to study the network as one-piece and this can take a long time for a very large system. An alternative solution is to reduce the size of the network by tearing apart a large system into small subnetworks, thus a cluster of computers can be supplemented to speed-up the process. Then the system can be solved as separate entities after which their solutions are connected together by mathematical modelling in order to obtain the solution of the original system as if it was solved as one-piece. This method in its original conception is known as diakoptics which, though was conceived for power systems analysis, is now widely viewed as a mathematical method rather than a power systems analysis tool.The work presented in this thesis proposes two novel diakoptic tools for the power system analysis; i.e. the branch voltage multiplier technique (BVMT) and slack bus voltage updating diakoptics (SVUD). Various research works so far have shown that the key factor is in the process of obtaining the fundamental equations of diakoptics and the final equation of solution. The BVMT is a variant of the original diakoptic algorithm mainly by the process of obtaining the diakoptic equations of solution which can reduce the number of solution steps and simplify the method considerably. The resultant algorithm is easier to apply and also more effective in load flow analysis by current injection methods where the relationship is linear. The common practice in present load flow analyses is by power injection which yields nonlinear equations. The BVMT technique has been extended by applying various transformations which make it suitable for nonlinear solutions. This yields the SVUD load flow method that incorporates the classical Gauss-Seidel method. The analysis tools produced have been validated by applying to sample systems including IEEE benchmark systems. In one-piece load flow analysis, the usual practice is to choose one slack bus whose voltage remains unchanged throughout the iterative process. In diakoptic analysis, the systems to be analysed are more than one after tearing, so the subnetworks without the original slack bus will require temporary slack buses during the load flow analysis. During iteration, the voltages of these temporary slack buses would also remain unchanged; the SVUD method ensures that their voltages vary to reflect the state they would have been in one-piece solutions. This is achieved by updating the voltages during iteration using given and computed parameters which, in this case, are the complex powers. This has resulted in the improvement of the convergence characteristics of the traditional Gauss-Seidel method. For example, in the analysis of the IEEE 30-bus network, the number of iterations in one-piece Gauss-Seidel solution was 202 while with the SVUD, the numbers of iterations were 17 when cut into two subnetworks, and 13 when cut into three subnetworks. The SVUD also removes some common problems associated with temporary slack buses. This is demonstrated in the analysis of the 14-bus system using the one-piece Gauss-Seidel, SVUD and diakoptics with the temporary slack bus voltage remaining unchanged during iteration. The one-piece method converged after 106 iterations and the SVUD converged after 5 iterations. The diakoptic analysis with constant temporary slack-bus voltage converged after 146 iterations and erroneous results were obtained.The SVUD analysis of the Nigeria 330kV power transmission network without wind power electricity shows a voltage profile with some violations at a number of buses. The analysis with wind power electricity shows voltage rises, especially at buses close to the point of common coupling. This is a generally accepted effect of electricity from wind on an existing power system. In the Nigeria case, the conventional generation capacity is far below what is required and so the voltage profile is seen to improve because the wind farm constitutes an extra generating capacity. For example, at rated wind power, the voltage magnitudes show rises of 0.12% at bus 31 and 0.15% at bus 32. Increase of wind power to 4.1018 pu shows rises of 3.9% at bus 31 and 4.5% at bus 32

Center for Space Microelectronics Technology

The 1990 technical report of the Jet Propulsion Laboratory Center for Space Microelectronics Technology summarizes the technical accomplishments, publications, presentations, and patents of the center during 1990. The report lists 130 publications, 226 presentations, and 87 new technology reports and patents

Characterization of an Integrated Circuit with Respect to Electrostatic Discharge-Induced Soft Failures

This research proposal presents a methodology whereby an integrated circuit (IC) can be characterized with respect to soft-failures induced by Electrostatic Discharge (ESD)-like events. This methodology uses an exclusively black-box approach to determine the response of an IC in a system-level environment, thereby allowing it to be implemented without intimate knowledge of the DUT IC. Results from this methodology can be referenced during system design to raise awareness of specific vulnerabilities of the core system ICs. During work on this methodology, several sub topics have been explored and developed in the field of system-level ESD. Sections 2 and 3 introduce two topics which were developed to facilitate the generation and expression of IC pin models. Papers 1 and 2 introduce injection methods for characterizing complete systems on an interface-by-interface basis and form the foundation for the following works. Papers 2 and 3 mirror Papers 1 and 2 but instead shift focus away from the system as a whole and outline methods for characterizing the integrated circuits directly. Finally, Section 4 outlines a model method which can be used to describe the failures found in Paper 4 in circuit simulation, rounding out the work. Additional measurements which were unable to be included in Paper 4 are included in Appendices A, B, and C --Abstract, page iv