Abstract
In this paper it is presented a combined on-line hybrid transient stability formulation with a parallel processing state estimator. The transient stability assessment uses a time domain integration scheme to compute the initial system trajectory and the equal area criteria to obtain the transient stability margins and the critical clearing times. The state estimator that provides the pre-fault operating conditions uses a parallel processing approach. In this technique the power system is split into K areas, and each subsystem is supervised by a local control centre. The measurements in each area are collected in the individual local control centre that has at least one computer system for data acquisition, data processing and computation. The computer programs developed by the authors were applied to a multimachine power network. The results obtained with the proposed formulation were compared with the solutions produced by other methods. Finally, some conclusions that provide a valuable contribution to the understanding of the multimachine power system preventive control are pointed out.

Abstract
Fieldbus communication networks aim to interconnect sensors, actuators and controllers within distributed computer-controlled systems. Therefore, they constitute the foundation upon which real-time applications are to be implemented. A specific class of fieldbus communication networks is based on a simplified version of token-passing protcols, where each station may transfer, at most, one Single Message per Token Visit (SMTV). In this paper, we establish an analogy between non pre-emptive task scheduling in single processors and scheduling of messages on SMTV token-passing networks. Moreover, we clearly show that concepts such as blocking and interference in non pre-emptive task scheduling have their counterpart in the scheduling of messages on SMTV token-passing networks. Based on this task/message scheduling analogy, we provide pre-run-time schedulability conditions for supporting real-time messages with SMTV token-passing networks. We provide both utilisation-based and response time tests to perform the pre-run-time schedulability analysis of real-time RM/DM and EDF priority assignment schemes.

Abstract
Parallel logic programming (PLP) systems are sophisticated examples of symbolic computing systems. PLP systems address problems such as allocating dynamic memory, scheduling irregular computations, and managing different types of implicit parallelism. Most PLP systems have been developed for bus-based architectures. However, the complexity of PLP systems and the large amount of data they process raise the question of whether logic programming systems can still achieve good performance on modern scalable architectures, such as distributed shared-memory (DSM) systems. In this work we use execution-driven simulation of a cache-coherent DSM architecture to investigate the performance of Andorra-I, a state-of-the-art PLP system, on a modern multiprocessor. The results of this simulation show that Andorra-I exhibits reasonable running time performance, but it does not scale well. Our detailed analysis of cache misses and their sources expose several opportunities for improvements in Andorra-I. Based on this analysis, we modify Andorra-I using a set of simple techniques that led to significantly better running time and scalability. These results suggest that Andorra-I can and should perform well on modern multiprocessors. Furthermore, as Andorra-I shares its main data structures with several PLP systems, we conclude that the methodology and techniques used in our work can greatly benefit these other PLP systems. © 2000 Academic Press.

Abstract
This paper presents a novel algorithm for temporal partitioning of graphs representing a behavioral description. The algorithm is based on an extension of the traditional static-list scheduling that tailors it to resolve both scheduling and temporal partitioning. The nodes to be mapped into a partition are selected based on a statically computed cost model. The cost for each node integrates communication effects, the critical path length, and the possibility of the critical path to hide the delay of parallel nodes. In order to alleviate the runtime there is no dynamic update of the costs. A comparison of the algorithm to other schedulers and with close-to-optimum results obtained with a simulated annealing approach is shown. The presented algorithm has been implemented and the results show that it is robust, effective, and efficient, and when compared to other methods finds very good results in small amounts of CPU time.

Abstract
The concept of time refraction is introduced to describe the effects of a sudden change of the optical properties of a dielectric medium. This can be seen as the most elementary process associated with photon acceleration and frequency upshifting. The quantum theory of such a process shows that the initial wave splits into time-transmitted and time-reflected waves propagating in opposite directions after the occurrence of a time discontinuity of the refractive index. The time refraction laws, analogous to the well known Fresnel formulas and Snell's law, are also derived. It is shown that, in quantum terms, time refraction is equivalent to a squeezing transformation.

Abstract