[en] This paper describes our experience in converting the ASPEN program for use on our CRAY computers at the Los Alamos National Laboratory. The CRAY computer is two-to-five times faster than a CDC-7600 for scalar operations, is equipped with up to two million words of high-speed storage, and has vector processing capability. Thus, the CRAY is a natural candidate for programs that are the size and complexity of ASPEN. Our approach to converting ASPEN and the conversion problems are discussed, including our plans for optimizing the program. Comparisons of run times for test problems between the CRAY and IBM 370 computer versions are presented

[en] Fortran applications programs can be executed on multiprocessor computers in either a unitasking (traditional) or multitasking form. The later allows a single job to use more than one processor simultaneously, with a consequent reduction in elapsed time and, perhaps, the cost of the calculation. An introduction to programming in this environment is presented. The concept of synchronization and data sharing using EVENTS and LOCKS are illustrated with examples. The strategy of strong synchronization and the use of synchronization templates are proposed. We emphasize that incorrect multitasking programs can produce irreducible results, which makes debugging more difficult

No abstract available

[en] FORTRAN applications programs can be executed on multiprocessor computers in either a unitasking (traditional) or multitasking form. The latter allows a single job to use more than one processor simultaneously, with a consequent reduction in wall-clock time and, perhaps, the cost of the calculation. An introduction to programming in this environment is presented. The concepts of synchronization and data sharing using EVENTS and LOCKS are illustrated with examples. The strategy of strong synchronization and the use of synchronization templates are proposed. We emphasize that incorrect multitasking programs can produce irreproducible results, which makes debugging more difficult

[en] In this note, we present the results obtained with the CEA Benchmark on a CRAY Y-MP/832. The performances of the new machine are better than those of a Cray X-MP, specially regarding parallel computation

[en] How much speedup can we expect for large scientific parallel programs running on supercomputers. For insight into this problem we extend the parallel processing environment currently existing on the Cray X-MP (a shared memory multiprocessor with at most four processors) to a simulated N-processor environment, where N greater than or equal to 1. Several large scientific parallel programs from Los Alamos National Laboratory were run in this simulated environment, and speedups were predicted. A speedup of 14.4 on 16 processors was measured for one of the three most used codes at the Laboratory

[en] The letter discusses the possible radiation damages on semiconductor equipments included in the implemented cardial peacemakers or other personal portable microprocessor controlled devices of patients undergoing radiation therapyy

[en] The meteorological HIRLAM model system was developed by all the Nordic Countries and the Netherlands in cooperation. Since Autumn 1990 HIRLAM has been operational in Denmark and verification results for the two months December 1990 and January 1991 are presented. Verification against observations at synop- and radiosonde stations shows that for MSL-pressure and winds in 850-hPa and 500 hPa the biases are generally small. 10-meter winds have a positive bias of 1-2 m/s. The biases as well as MAE and RMSE are generally smaller or of equal size as those of the U.K. Limited Area Model, except for the 10-meter wind for which UK-LAM is slightly better. Further inspection of two individual stations, Copenhagen and Paris, shows very high correlation, r>0.9, between observed and prognostic MSL-pressure and wind-direction in 10-meter and 850-hpa. For windspeed in 10-meter and 850-hPa the correlation was fairly high, r>0.8

[en] In this short note we describe some of the problems we have encountered on implementing the R-matrix codes of Berrington et al. on the CRAY-1. In particular we consider the calculation of R-matrix angular integrals which as currently implemented are not vectorizable. Since this section of the code is sandwiched between highly vectorizable packages a bottleneck occurs. An alternative algorithm to circumvent this impasse is suggested. (orig.)

[en] Cray supercomputer hardware and software are discussed. Applications that are being used on Cray computers are briefly described. A detailed discussion of using supercomputers for better than real-time simulations of nuclear plant transients is given. It is shown that supercomputers have the capability of calculating most transients that could occur in a nuclear power plant in better than real time