Herramientas, argumentos y procesos en prácticas de simulación

Este reporte es parte de una investigación en curso que estudia prácticas de simulación y las herramientas que se construyen para su ejercicio, esta se desarrolla en el marco de la socioepistemología. La simulación se entiende como prácticas recurrentes de diferentes comunidades con la intencionalidad de describir fenómenos a partir de sus modelos. En este trabajo solo abordamos la simulación de fenómenos considerando modelos lineales, para ello analizamos dos puesta en escena de un diseño de aprendizaje con estudiantes de nivel medio superior y de posgrado. Reportamos las herramientas, procesos y argumentos de los actores al simular.

Simulación de problemas probabilísticos

La simulación computacional de problemas de probabilidad permite obtener sus soluciones a través de la frecuencia relativa del número de éxitos obtenidos en los n experimentos realizados. La ley de los grandes números respalda una buena aproximación de la probabilidad teórica de un evento a través de la repetición sucesiva de experimentos. A continuación se presentan una serie de problemas probabilísticos con una posible simulación realizada en los paquetes Fathom y Excel. La solución teórica de estos problemas requiere conocimientos básicos de probabilidad, por lo que las simulaciones realizadas buscan dar una propuesta de solución a estos problemas sin tener que acudir al formalismo matemático.

Simulación en Excel: buscando la probabilidad de un evento

El presente trabajo tiene como objetivo que el lector obtenga una mejor comprensión del concepto de probabilidad y una interpretación correcta a la Ley de los Grandes Números. Las actividades planteadas adoptan el enfoque frecuencial de la definición de probabilidad, en donde a través de la simulación de algunos experimentos aleatorios utilizando Excel y desde una perspectiva Brousseauneana, se aproximan las probabilidades teóricas de algunos eventos.

Investigation into a modular rule-based testing method for testing business rules in scheduling applications

Rule testing in transport scheduling is a complex and potentially costly business problem. This paper proposes an automated method for the rule-based testing of business rules using the extensible Markup Language for rule representation and transportation. A compiled approach to rule execution is also proposed for performance-critical scheduling systems.

Safety issues with the South African Pebble Bed Modular Reactor: when were the issues apparent? A briefing paper

This is a briefing report on when the safety issues identified in a July 2008 report by Jülich should have become apparent In July 2008, the German Jülich nuclear research centre published a report entitled ‘A safety re-evaluation of the AVR pebble bed reactor operation and its consequences for future HTR concepts.’ It concluded: ‘pebble bed HTRs require additional safety related R&D effort and updating of safety analyses before construction.’

Learning soft computing control strategies in a modular neural network architecture

Modelling and control of nonlinear dynamical systems is a challenging problem since the dynamics of such systems change over their parameter space. Conventional methodologies for designing nonlinear control laws, such as gain scheduling, are effective because the designer partitions the overall complex control into a number of simpler sub-tasks. This paper describes a new genetic algorithm based method for the design of a modular neural network (MNN) control architecture that learns such partitions of an overall complex control task. Here a chromosome represents both the structure and parameters of an individual neural network in the MNN controller and a hierarchical fuzzy approach is used to select the chromosomes required to accomplish a given control task. This new strategy is applied to the end-point tracking of a single-link flexible manipulator modelled from experimental data. Results show that the MNN controller is simple to design and produces superior performance compared to a single neural network (SNN) controller which is theoretically capable of achieving the desired trajectory. (C) 2003 Elsevier Ltd. All rights reserved.

A modular approach to luminescent dinuclear ruthenium(II) and rhenium(I) complexes

A series of dinuclear (bipyridine)tricarbonylrhenium(I) and tris(bipyridine)ruthenium(II) complexes have been isolated and characterised, bridged by a flexible diamido ethylene glycol chain. A new stepwise synthetic pathway has been investigated to heterometallic complexes, with the rhenium(I) complexes exhibiting an unusual configuration and inequivalence of the metal centres potentially arising from a surprising hydrogen-bonding interaction between an Re–CO group and an amide proton in low-polarity solvents. This interaction appears to be broken by competing hydrogen-bonding species such as dihydrogen phosphate. This effect was not observed in the corresponding ruthenium(II) complexes, which showed very little interaction with anions. The photophysical characterisation shows that the inclusion of two ester/amide groups to the rhenium centre effectively quenches the fluorescence at room temperature. The ruthenium(II) complexes have considerably stronger fluorescence than the rhenium species, and are less affected by theinclusion of ester and amide groups to the 2,2'-bipyridine chelating group.

High-performance IQ modulator-based phase conjugator for modular retrodirective antenna array implementation

In this paper, we verify a new phase conjugating architecture suitable for deployment as (lie core building block in retrodirective antenna arrays, which can be scaled to any number of elements in a modular way without impacting on complexity. Our solution is based on a modified in-phase and quadrature modulator architecture, which completely resolves four major shortcomings of the conventional mixer-based approach currently used for the synthesis of phase conjugated energy derived from a sampled incoming wavefront. 1) The architecture presented removes the need for a local oscillator running at twice the RF signal frequency to be conjugated. 2) It maintains a constant transmit power even if receive power goes as low as -120 dBm. 3) All unwanted re-transmit signal products are suppressed by at least 40 dB. 4) The issue of poor RF-IF leakage prevalent in mixer-based phase-conjugation solutions is completely mitigated. The circuit has also been shown to have high conjugation accuracy (better than +/-1 degrees at -60-dBm input). Near theoretically perfect experimental monostatic and bistatic results are presented for a ten-element retrodirective array constructed using the new phase conjugation architecture.