1997
Authors
Quintas, A; Leitao, P;
Publication
RE-ENGINEERING FOR SUSTAINABLE INDUSTRIAL PRODUCTION
Abstract
Nowadays, with the globalization of the markets, the companies must to implement new manufacturing technologies and concepts for the improvement of manufacturing systems productivity. The integration is one of the keys to solve the problems in manufacturing systems. The arrangement of the resources in cells and the implementation of control systems allows the improvement of productivity, flexibility, quality and the reduction of production costs. This paper describes a Cell Controller architecture solution, implemented at the flexible manufacturing cell integrated into the demonstration pilot of an ESPRIT Program Project; special attention to the control structure and the system communication is taken. The last part of the paper focuses the costs involved in this solution and presents the alternative platforms and technologies to implement the Cell Controller.
1997
Authors
Fidalgo, JN; Matos, MA; Ponce De Leao, MT;
Publication
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Abstract
Electrical distribution utilities have been dealing with the problem of estimation of distribution network load diagrams, either for operation studies or in forecasting models for planning purposes. Load curve assessment is essential for an efficient management of electric distribution systems. However, the only information available for most of the loads (namely LV loads) is related to monthly energy consumption. The general procedure uses measurements in consumers to construct inference engines that predict load curves using commercial information. This paper presents a new approach for this problem, based on Kohonen maps and Artificial Neural Networks (ANN) to estimate load diagrams for the Portuguese distribution utilities. A method for estimating error bars is also proposed in order to provide a high order information about the performance of load curve estimation process. Performance attained is discussed as well as the method to achieve confidence intervals of the main predicted diagrams. © Springer-Verlag Berlin Heidelberg 1997.
1997
Authors
Araujo, RE; Leite, AV; Freitas, DS;
Publication
ISIE '97 - PROCEEDINGS OF THE IEEE INTERNATIONAL SYMPOSIUM ON INDUSTRIAL ELECTRONICS, VOLS 1-3
Abstract
This paper describes the newly developed Vector Control Signal Processing (VCSP) blockset for use with Matlab(R) and Simulink(R). The originality of this blockset consists on the extension of Simulink for design, simulation and prototyping of signal processing algorithms in motion control systems. This blockset is the first know collection of Simulink blocks to bridge the gap between digital algorithm development and subsequent implementation in motion control systems. The VCSP blockset together with Real-Time Workshop uses the inherent visual programming techniques of Simulink and a number of pre-built blocks to reach the above goals. Due to its open and flexible nature this approach is also very useful as a tool for teaching. This paper is focused on modelling and simulation of motion control systems, in particular employing rotating AC machines and vector control methods. The basic of blockset functions and some examples of modelling techniques for simple drive and complex drive structures are presented, Simulations results are also presented and discussed.
1997
Authors
Diniz, P; Rinard, M;
Publication
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Abstract
Atomic operations are a key primitive in parallel computing systems. The standard implementation mechanism for atomic operations uses mutual exclusion locks. In an object-based programming system the natural granularity is to give each object its own lock. Each operation can then make its execution atomic by acquiring and releasing the lock for the object that it accesses. But this fine lock granularity may have high synchronization overhead. To achieve good performance it may be necessary to reduce the overhead by coarsening the granularity at which the computation locks objects. In this paper we describe a static analysis technique — lock coarsening — designed to automatically increase the lock granularity in object-based programs with atomic operations. We have implemented this technique in the context of a parallelizing compiler for irregular, object-based programs. Experiments show these algorithms to be effective in reducing the lock overhead to negligible levels. © Springer-Verlag Berlin Heidelberg 1997.
1997
Authors
Diniz, P; Rinard, M;
Publication
SIGPLAN Notices (ACM Special Interest Group on Programming Languages)
Abstract
This paper presents dynamic feedback, a technique that enables computations to adapt dynamically to different execution environments. A compiler that uses dynamic feedback produces several different versions of the same source code; each version uses a different optimization policy. The generated code alternately performs sampling phases and production phases. Each sampling phase measures the overhead of each version in the current environment. Each production phase uses the version with the least overhead in the previous sampling phase. The computation periodically resamples to adjust dynamically to changes in the environment. We have implemented dynamic feedback in the context of a parallelizing compiler for object-based programs. The generated code uses dynamic feedback to automatically choose the best synchronization optimization policy. Our experimental results show hat the synchronization optimization policy has a significant impact on the overall performance of the computation, that the best policy varies from program to program, that the compiler is unable to statically choose the best policy, and that dynamic feedback enables the generated code to exhibit performance that is comparable to that of code that has been manually tuned to use the best policy. We have also performed a theoretical analysis which proves, under certain assumptions, a guaranteed optimality bound for dynamic feedback relative to a hypothetical (and unrealizable) optimal algorithm that uses the best policy at every point during the execution.
1997
Authors
Ferreira, LA; Santos, JL; Farahi, F;
Publication
IEEE PHOTONICS TECHNOLOGY LETTERS
Abstract
A pseudoheterodyne, open-loop demodulation technique? for detecting wavelength shifts in wavelength encoded fiber Bragg grating sensors is presented, The scheme uses a processing Bragg grating that is identical to one used as a sensor, When the processing fiber grating is stretched periodically, the system of two gratings produces a carrier at this frequency with its phase modulated by the measurand signal applied to the sensing grating, The demodulation technique is intrinsically immune to fluctuation of optical power in the system and is independent of the source spectral profile characteristics. A resolution of approximate to 1 mu epsilon/root Hz for static axial strain was achieved.
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