Ecuaciones diferenciales como modelos en clase de física y de matemáticas

Este artículo trata de la enseñanza y el aprendizaje de la modelación matemática en los cursos de física y de matemáticas. En el 2002, un nuevo currículo para el bachillerato en Francia acentuó el papel de las matemáticas como una herramienta para modelar en otras ciencias. Una descripción del proceso de modelación es presentada, así como el análisis de los manuales comúnmente usados en estos cursos. Este análisis revela el proceso de transposición del "proceso de modelación" practicado por los expertos y el proceso que es adaptado finalmente a la escuela. La implementación de una situación experimental con tareas no habituales permite la identificación de la influencia de las praxeologías en los procesos de los estudiantes. La vinculación de algunas dificultades presentes al abordar la situación con la transposición del proceso de modelación también es discutida en este artículo.

La enseñanza de la modelación en clase de física y de matemáticas

La introducción de nuevos planes de estudio en Francia (2002), muestra la importancia que tiene actualmente la enseñanza y aprendizaje de la modelación, principalmente en disciplinas científicas como Matemáticas y Física. En los programas oficiales y libros del último año de preparatoria se observa la introducción de la noción de ecuación diferencial como objeto de estudio pero también como herramienta para modelar diversas situaciones físicas. En esta investigación, estableceremos un modelo del proceso de modelación que constituya una referencia para posteriormente caracterizarlo, desde un punto de vista antropológico, en dos instituciones diferentes: la clase de matemáticas y la clase de física.

La significación física de la integral a partir de la modelación de fenómenos

Una pregunta que me plantean con mucha frecuencia los estudiantes es ¿qué significado tiene la integral?; con este trabajo pretendemos incursionar en la problemática referida a la formación de la significación física de la integral, para lograrlo partimos de la idea de que esa significación tiene que ver por un lado con las concepciones matemáticas “heredadas” por los profesores a sus alumnos y por otro con los procesos de matematización de fenómenos en diversos contextos. Hemos realizado un primer acercamiento exploratorio para recoger evidencias, que nos permita elaborar una secuencia basada en prácticas de modelación de fenómenos. Reportamos como es construida la significación física de la integral en el discurso. Un resultado consecuente, es una aproximación a la concepción de práctica social.

Logaritmos, física y algo más

Con la popularización de las calculadoras electrónicas el cálculo logarítmico en sí mismo fue perdiendo espacio y en forma gradual se fue abandonando su enseñanza. Pero el tema “logaritmos” sigue presente en los “programas”. Es muy difícil lograr un aprendizaje sustancial y por lo tanto duradero si en el momento de abordar el tema nuestros alumnos no le encuentran significado. Así que procuramos dárselo. Para ello, aspiramos a un desarrollo conceptual muy distante del puro entrenamiento algebraico al que se fue limitando la práctica de la enseñanza de este tema.

Upgrading automation for nuclear fuel in-core management: from the symbolic generation of configurations to the neural adaptation of heuristics

FUELCON is an expert system in nuclear engineering. Its task is optimized refueling-design, which is crucial to keep down operation costs at a plant. FUELCON proposes sets of alternative configurations of fuel-allocation; the fuel is positioned in a grid representing the core of a reactor. The practitioner of in-core fuel management uses FUELCON to generate a reasonably good configuration for the situation at hand. The domain expert, on the other hand, resorts to the system to test heuristics and discover new ones, for the task described above. Expert use involves a manual phase of revising the ruleset, based on performance during previous iterations in the same session. This paper is concerned with a new phase: the design of a neural component to carry out the revision automatically. Such an automated revision considers previous performance of the system and uses it for adaptation and learning better rules. The neural component is based on a particular schema for a symbolic to recurrent-analogue bridge, called NIPPL, and on the reinforcement learning of neural networks for the adaptation.

A novel neural/symbolic hybrid approach to heuristically optimized fuel allocation and automated revision of heuristics in nuclear engineering

FUELCON is an expert system for optimized refueling design in nuclear engineering. This task is crucial for keeping down operating costs at a plant without compromising safety. FUELCON proposes sets of alternative configurations of allocation of fuel assemblies that are each positioned in the planar grid of a horizontal section of a reactor core. Results are simulated, and an expert user can also use FUELCON to revise rulesets and improve on his or her heuristics. The successful completion of FUELCON led this research team into undertaking a panoply of sequel projects, of which we provide a meta-architectural comparative formal discussion. In this paper, we demonstrate a novel adaptive technique that learns the optimal allocation heuristic for the various cores. The algorithm is a hybrid of a fine-grained neural network and symbolic computation components. This hybrid architecture is sensitive enough to learn the particular characteristics of the ‘in-core fuel management problem’ at hand, and is powerful enough to use this information fully to automatically revise heuristics, thus improving upon those provided by a human expert.

Intelligent technologies for nuclear power systems: heuristic and neural tools

The consecutive, partly overlapping emergence of expert systems and then neural computation methods among intelligent technologies, is reflected in the evolving scene of their application to nuclear engineering. This paper provides a bird's eye view of the state of the application in the domain, along with a review of a particular task, the one perhaps economically more important: refueling design in nuclear power reactors.

Refueling in nuclear engineering: the FUELCON project

Over a time span of almost a decade, the FUELCON project in nuclear engineering has led to a fully functional expert system and spawned sequel projects. Its task is in-core fuel management, also called `refueling', i.e., good fuel-allocation for reloading the core of a given nuclear reactor, for a given operation cycle. The task is crucial for keeping down operation costs at nuclear power plants. Fuel comes in different types and is positioned in a grid representing the core of a reactor. The tool is useful for practitioners but also helps the expert in the domain to test his or her rules of thumb and to discover new ones.

Measuring distributions of jump rates in disordered metal–hydrogen systems by nuclear magnetic relaxation

Monte Carlo calculations of the nuclear magnetic relaxation rate in a disordered metal–hydrogen system having a distribution of jump rates are reported. The calculations deal specifically with the spin-locked rotating-frame relaxation time T1ρ. The results demonstrate that the temperature variation of the rate is only weakly dependent on the distribution and it is therefore unlikely that the jump rate distribution can be extracted from relaxation measurements in which temperature is the main variable. It is shown that the alternative of measuring the relaxation rate over a wide range of spin-locking field strengths at a constant temperature can lead to an evaluation of the distribution.

Rotating-frame nuclear magnetic relaxation of spins diffusing on a disordered lattice: a Monte Carlo model

The rotating-frame nuclear magnetic relaxation rate of spins diffusing on a disordered lattice has been calculated by Monte Carlo methods. The disorder includes not only variation in the distances between neighbouring spin sites but also variation in the hopping rate associated with each site. The presence of the disorder, particularly the hopping rate disorder, causes changes in the time-dependent spin correlation functions which translate into asymmetry in the characteristic peak in the temperature dependence of the dipolar relaxation rate. The results may be used to deduce the average hopping rate from the relaxation but the effect is not sufficiently marked to enable the distribution of the hopping rates to be evaluated. The distribution, which is a measure of the degree of disorder, is the more interesting feature and it has been possible to show from the calculation that measurements of the relaxation rate as a function of the strength of the radiofrequency spin-locking magnetic field can lead to an evaluation of its width. Some experimental data on an amorphous metal - hydrogen alloy are reported which demonstrate the feasibility of this novel approach to rotating-frame relaxation in disordered materials.

International perspectives on energy policy and the role of nuclear power

In this book, expert energy economists assess the energy policy of thirty-one countries and the role of nuclear power. For many years the shock of Chernobyl took nuclear power off the agenda in most countries. Intense public relations activities by the industry, increasing evidence of climate change and failures to effectively reduce greenhouse gas emissions, have brought nuclear power issues back to the forefront of policy discussion in the nuclear renaissance countries. But some countries are just not prepared to go in that direction and, indeed, are still divesting themselves of their nuclear legacy, the nuclear phase-out countries. And how are nuclear issues being approached in the industrializing countries? An in-depth country-by-country analysis is presented within this framework. Out of such an analysis emerge thematic discussions on, among others, strategy in energy policy; nuclear plant safety, the impacts of nuclear accidents; the adequacy of nuclear power expertise. [Source: publisher's product description].

The world nuclear industry status report 2009: with particular emphasis on economic issues

A detailed review of the status of the world nuclear industry with particular emphasis on economic aspects.

The financial crisis and nuclear power

An assessment of the impact of the financial crisis on the prospects for new nuclear power plant orders worldwide.