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Publicações

1999

Coherence properties of multimode incoherent spatial solitons in noninstantaneous Kerr media

Autores
Carvalho, MI; Coskun, TH; Christodoulides, DN; Mitchell, M; Segev, M;

Publicação
PHYSICAL REVIEW E

Abstract
We investigate the coherence characteristics of multimode incoherent spatial solitons in noninstantaneous Kerr-like nonlinear media. Other properties of these incoherent solitons are also discussed as a function of their modal composition. [S1063-651X(99)04001-5].

1999

A virtual machine for a process calculus

Autores
Lopes, L; Silva, F; Vasconcelos, VT;

Publicação
PRINCIPLES AND PRACTICE OF DECLARATIVE PROGRAMMING, PROCEEDINGS

Abstract
Despite extensive theoretical work on process-calculi, virtual machine specifications and implementations of actual computational models are still scarce. This paper presents a virtual machine for a strongly typed, polymorphic, concurrent, object-oriented programming language based on the TyCO process calculus. The system runs byte-code files, assembled from an intermediate assembly language representation, which is in turn generated by a compiler. Code optimizations are provided by the compiler coupled with a type-inference system. The design and implementation of the virtual machine focuses on performance, compactness, and architecture independence with a view to mobile computing. The assembly code emphasizes readability and efficient byte code generation. The byte code has a simple layout and is a compromise between size and performance. We present some performance results and compare them to other languages such as Pict, Oz, and JoCaml.

1999

Or-Parallelism within Tabling

Autores
Rocha, R; Silva, F; Costa, VS;

Publicação
PRACTICAL ASPECTS OF DECLARATIVE LANGUAGES

Abstract
One important advantage of logic programming is that it allows the implicit exploitation of parallelism. Towards this goal, we suggest that or-parallelism can be efficiently exploited in tabling systems and propose two alternative approaches, Or-Parallelism within Tabling (OPT) and Tabling within Or-Parallelism (TOP). We concentrate on the fundamental concepts of an environment copying based model to implement the OPT approach and introduce the data structures and algorithms necessary to extend the YapOr Or-Parallel system, in order to obtain a parallel tabling system.

1999

DAOS - Scalable And-Or parallelism

Autores
Castro, LF; Costa, VS; Geyer, CFR; Silva, F; Vargas, PK; Correia, ME;

Publicação
EURO-PAR'99: PARALLEL PROCESSING

Abstract
This paper presents DAOS, a model for exploitation of Andand Or-parallelism in logic programs. DAOS assumes a physically distributed memory environment and a logically shared address space. Exploiting both major forms of implicit parallelism should serve a broadest range of applications. Besides, a model that uses a distributed memory environment provides scalability and can be implemented over a computer network. However, distributed implementations of logic programs have to deal with communication overhead and inherent complexity of distributed memory managent. DAOS overcomes those problems through the use of a distributed shared memory layer to provide single-writer, multiple-readers sharing for the main execution stacks combined with explicit message passing for work distribution and management.

1999

<title>Surveillance of fiber optic and electric power cables using fiber Bragg grating sensors</title>

Autores
Araujo, FM; Teixeira, M; Ferreira, LAA; Dias, IM; Quintela, A; Castro, JL;

Publicação
Fiber Optic and Laser Sensors and Applications; Including Distributed and Multiplexed Fiber Optic Sensors VII

Abstract

1999

Surveillance of fiber optic cables and electric power cables using fiber Bragg grating sensors

Autores
Araujo, FM; Teixeira, M; Ferreira, LA; Dias, I; Quintela, A; Castro, JL;

Publicação
FIBER OPTIC AND LASER SENSORS AND APPLICATIONS: INCLUDING DISTRIBUTED AND MULTIPLEXED FIBER OPTIC SENSORS VII

Abstract
We report on the integration of optical fiber containing Bragg gratings in the structure of both optical and power cables. It is shown that fiber Bragg gratings provide an efficient method to monitor quasi-distributed mechanical strength along optical cables. This technology is also applied to the monitoring of temperature in power cables for transmission/distribution infrastructures. We show that there are no losses introduced during the cabling process, and the temperature sensitivity of the fiber Bragg grating was found to be only slightly affected by the extrusion process. Results are presented for cable operation in real environment.

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