An empirical evaluation of techniques for parallel simulation of message passing networks

209 p.[EN]In the field of computer design, simulation is an essential tool to validate and evaluate architectural proposals. Conventional simulation techniques, designed for their use in sequential computers, are too slow if the system to simulate is large or complex. The aim of this work is to search for techniques to accelerate simulations exploiting the parallelism available in current, commercial multicomputers, and to use these techniques to study a model of a message router. This router has been designed to constitute the communication infrastructure of a (hypothetical) massively parallel computer. Three parallel simulation techniques have been considered: synchronous, asynchronous-conservative and asynchronous-optimistic. These algorithms have been implemented in three multicomputers: a transputer-based Supernode, an Intel Paragon and a network of workstations. The influence that factors such as the characteristics of the simulated models, the organization of the simulators and the characteristics of the target multicomputers have in the performance of the simulations has been measured and characterized. It is concluded that optimistic parallel simulation techniques are not suitable for the considered kind of models, although they may provide good performance in other environments. A network of workstations is not the right platform for our experiments, because the communication demands of the parallel simulators surpass the abilities of local area networks—the granularity is too fine. Synchronous and conservative parallel simulation techniques perform very well in the Supernode and in the Paragon, specially if the model to simulate is complex or large—precisely the worst case for traditional, sequential simulators. This way, studies previously considered as unrealizable, due to their exceedingly high computational cost, can be performed in reasonable times. Additionally, the spectrum of possibilities of using multicomputers can be broadened to execute more than numeric applications.[ES]En el ámbito del diseño de computadores, la simulación es una herramienta imprescindible para la validación y evaluación de cualquier propuesta arquitectónica. Las ténicas convencionales de simulación, diseñadas para su utilización en computadores secuenciales, son demasiado lentas si el sistema a simular es grande o complejo. El objetivo de esta tesis es buscar técnicas para acelerar estas simulaciones, aprovechando el paralelismo disponible en multicomputadores comerciales, y usar esas técnicas para el estudio de un modelo de encaminador de mensajes. Este encaminador está diseñado para formar infraestructura de comunicaciones de un hipotético computador masivamente paralelo. En este trabajo se consideran tres técnicas de simulación paralela: síncrona, asíncrona-conservadora y asíncrona-optimista. Estos algoritmos se han implementado en tres multicomputadores: un Supernode basado en Transputers, un Intel Paragon y una red de estaciones de trabajo. Se caracteriza la influencia que tienen en las prestaciones de los simuladores aspectos tales como los parámetros del modelo simulado, la organización del simulador y las características del multicomputador utilizado. Se concluye que las técnicas de simulación paralela optimista no resultan adecuadas para trabajar con el modelo considerado, aunque pueden ofrecer un buen rendimiento en otros entornos. La red de estaciones de trabajo no resulta una plataforma apropiada para estas simulaciones, ya que una red local no reúne condiciones para la ejecución de aplicaciones paralelas de grano fino. Las técnicas de simulación paralela síncrona y conservadora dan muy buenos resultados en el Supernode y en el Paragon, especialmente si el modelo a simular es complejo o grande—precisamente el peor caso para los algoritmos secuenciales. De esta forma, estudios previamente considerados inviables, por ser demasiado costosos computacionalmente, pueden realizarse en tiempos razonables. Además, se amplía el espectro de posibilidades de los multicomputadores, utilizándolos para algo más que aplicaciones numéricas.Este trabajo ha sido parcialmente subvencionado por la Comisión Interministerial de Ciencia y Tecnología, bajo contrato TIC95-037

Quantum phase transitions in odd-A nuclei: The effect of the odd particle from spherical to oblate shapes

Quantum shape-phase transitions in odd-nuclei are investigated within the framework of the interacting boson-fermion model (IBFM). We consider the case of a single-j fermion coupled to an even-even boson core that performs a transition from spherical to oblate shapes varying a control parameter in the boson Hamiltonian. The aim of this work is to see the effect of the coupling of the unpaired fermion on the transition, to understand how the coupled single particle modifies the geometric shape of the system and how each of the odd states behaves when the boson core shifts along the transitional path.Scientific and Technical Research Council of Turkey BIDEB-2224AMinisterio de Economía y Competitividad FIS2011-28738- c02-01, CSD2007-00042Junta de Andalucía FQM160, P11-FQM-763

The Urban Campus of A Coruña: Citizen Demand and Urban Project

[Resumo] La consecución de centros superiores de enseñanza ha sido una constante demanda de la ciudad de A Coruña, conformándose como un proyecto colectivo que se materializó en 1947 con la inauguración de los primeros edificios de la Ciudad Escolar, ubicada en la zona de Riazor y constituida por una serie de espacios libres y edificios de uso docente. Una ambiciosa propuesta urbana de creación de un conjunto universitario elaborada por el arquitecto Antonio Tenreiro, devino en la construcción de cuatro edificios proyectados por él: la Escuela de Magisterio, el Instituto de Enseñanzas Medias, la Escuela de Comercio y la Escuela de Náutica.[Abstract] The city of A Coruña had long been clamoring for the establishment of institutions of higher education. This demand was materialized in 1947 with the opening of the first buildings belonging to the college campus located in the Riazor area, with facilities that included open spaces and buildings to be used exclusively as classrooms. This ambitious urban project for a university complex designed by the architect Antonio Tenreiro resulted in the construction of four buildings: the School of Education, a High School, the Business School and the Naval Academy

Odd-even 147–153Pm isotopes within the neutron-proton interacting boson-fermion model

Low-lying energy states of the 147 -153Pm isotopic chain are studied within the framework of the neutron-proton interacting boson-fermion model (IBFM-2). The spectra of these isotopes show a transition from a particle coupled to a vibrational core to a particle coupled to a deformed one. The calculation reproduces this behavior. In addition, reduced transition probabilities B(E2) and B(M1) and quadrupole and magnetic moments, as well as spectroscopic factors corresponding to stripping and pickup transfer reactions, are calculated. Obtained results compare well with the available experimental data, which reinforces the reliability of the wave functions obtained within the IBFM-2 model.Ministerio de Ciencia e Innovación (España) FIS2009-07277 FIS2008-04189CPAN-Ingenio CSPD-2007-00042Junta de Andalucía FQM160 P07-FQM-0296

The one nucleon transfer operator in the microscopic IBM without NOA

The mapping of the single fermion creation operator (ci†) onto the Interacting Boson-Fermion space (IBFM) is revisited within the Generalized Seniority scheme. In the original work the Number Operator Approximation (NOA) was used. Here the exact evaluation of the relevant terms using exact values for the fermion matrix elements in the Generalized Seniority scheme is worked out. This provides a new, improved, single particle transfer operator to be used in IBFM.Ministerio de Economía y Competitividad FIS2011-28738-c02-01Junta de Andalucía FQM-160 y Project P11-FQM-7632Consolider-Ingenio 2010 Programme CPAN CSD2007-0004

One-particle spectroscopic intensities as a signature of shape phase transition: The γ -unstable case

We investigate the evolution of one-particle spectroscopic intensities as a possible signature of shape phase transitions. The study describes the odd systems in terms of the interacting boson–fermion model. We consider the particular case of an odd j=3/2 particle coupled to an even-even boson core that undergoes a phase transition from spherical U(5) to γ-unstable O(6) situation. At the critical point, our findings are compared with the one-particle spectroscopic intensities that can be obtained within the E(5/4) model proposed by [F. Iachello, Phys. Rev. Lett. 95, 052503 (2005); F. Iachello, in Symmetries and Low-Energy Phase Transitions in Nuclear Structure Physics, edited by G. Lo Bianco (University of Camerino Press, Camerino, Italy, in press)].Ministerio de Educación y Ciencia y FEDER FIS2005-0110

Shape phase transition in odd nuclei in a multi- j model: The UB(6) ⊗ UF(12) case

The phase transition in odd nuclei when the underlying even-even core nuclei experience a transition from spherical to deformed γ-unstable shapes is investigated. The odd particle is assumed to be moving in the three single-particle orbitals j=1/2,3/2, and 5/2. At the critical point in the phase transition, an analytic solution to the corresponding Bohr Hamiltonian, called E(5/12), is worked out. Energy spectra and electromagnetic transitions and moments are presented. The same problem is also attacked in the framework of the interacting boson-fermion model (IBFM). Two different Hamiltonians are used. The first one is constructed ad hoc so as to mimic the situation in the E(5/12) model. The second one leads to the occurrence of the OB(6) ⊗ UF(12) symmetry when the boson part approaches the O(6) condition. The entire transition line is studied with this Hamiltonian and, in particular, the critical point. Both IBFM calculations at the critical point are consistent with the E(5/12) results.Ministerio de Educación y Ciencia (España)FEDER FIS2005-0110

Search for E(5) symmetry in nuclei: The Ru isotopes

We carry out an interacting boson model study of the Ru isotopes using a U(5)-SO(6) transitional Hamiltonian with fixed parameters, where the variation is due only to the change in boson number N. Transitional behavior in 104Ru is compared with recent predictions of an E(5) critical symmetry, including a modified version with an alternative b dependence for the T(E2) operator.Ministerio de Ciencia y Tegnología PB98- 111