Neutron spectrometry using artificial neural networks for a bonner sphere spectrometer with 3He detector

Neutron spectra unfolding and dose equivalent calculation are complicated tasks in radiation protection, are highly dependent of the neutron energy, and a precise knowledge on neutron spectrometry is essential for all dosimetry-related studies as well as many nuclear physics experiments. In previous works have been reported neutron spectrometry and dosimetry results, by using the ANN technology as alternative solution, starting from the count rates of a Bonner spheres system with a LiI(Eu) thermal neutrons detector, 7 polyethylene spheres and the UTA4 response matrix with 31 energy bins. In this work, an ANN was designed and optimized by using the RDANN methodology for the Bonner spheres system used at CIEMAT Spain, which is composed of a He neutron detector, 12 moderator spheres and a response matrix for 72 energy bins. For the ANN design process a neutrons spectra catalogue compiled by the IAEA was used. From this compilation, the neutrons spectra were converted from lethargy to energy spectra. Then, the resulting energy ?uence spectra were re-binned by using the MCNP code to the corresponding energy bins of the He response matrix before mentioned. With the response matrix and the re-binned spectra the counts rate of the Bonner spheres system were calculated and the resulting re-binned neutrons spectra and calculated counts rate were used as the ANN training data set.

Performance of artificial neural networks and genetical evolved artificial neural networks unfolding techniques

With the Bonner spheres spectrometer neutron spectrum is obtained through an unfolding procedure. Monte Carlo methods, Regularization, Parametrization, Least-squares, and Maximum Entropy are some of the techniques utilized for unfolding. In the last decade methods based on Artificial Intelligence Technology have been used. Approaches based on Genetic Algorithms and Artificial Neural Networks have been developed in order to overcome the drawbacks of previous techniques. Nevertheless the advantages of Artificial Neural Networks still it has some drawbacks mainly in the design process of the network, vg the optimum selection of the architectural and learning ANN parameters. In recent years the use of hybrid technologies, combining Artificial Neural Networks and Genetic Algorithms, has been utilized to. In this work, several ANN topologies were trained and tested using Artificial Neural Networks and Genetically Evolved Artificial Neural Networks in the aim to unfold neutron spectra using the count rates of a Bonner sphere spectrometer. Here, a comparative study of both procedures has been carried out.

Grupos estratégicos: su influencia en el desempeño de la industria bancaria venezolana y su relación con la cobertura geográfica

El objetivo de esta investigación fue determinar los grupos estratégicos de la industria bancaria venezolana y su influencia sobre el desempeño en el sector, así como su relación con la cober tura geográfica, durante el primer semestre del año 2008. Los resultados más relevantes fueron los siguientes: 1) Los grupos estratégicos combinan patrones de conductas. 2) Las diferentes estrategias adoptadas por los bancos no se expresaron en una diferenciación en los niveles de resultados económicos y financieros. 3) Los grupos bancarios llevan a cabo una estrategia de cobertura geográfica relacionada con la estrategia financiera.

Modelling Saharan dust transport into the Mediterranean basin with CMAQ

The need for a better quantification of the influence of Saharan dust transport processes on the air quality modelling in the Mediterranean basin led to the formulation of a dust emission module (DEM) integrated into the Air Quality Risk Assessment System for the Iberian Peninsula (SERCA). This paper is focused on the formulation of DEM based on the GOCART aerosol model, along with its integration and execution into the air quality model. It also addresses the testing of the module and its evaluation by contrasting results against satellite products such as MODIS and CALIPSO and ground-level observations of aerosol optical thickness (AOT) and concentration levels of PM10 for different periods in July 2007. DEM was found capable of reproducing the spatial (horizontal and vertical) and temporal profiles of Saharan dust outbreaks into the Mediterranean basin and the Atlantic coast of Africa. Moreover, it was observed that its combination with CMAQ increased the correlation degree between observed and modelled PM10 concentrations at the selected monitoring locations. DEM also enhanced CMAQ capabilities to reproduce observed AOT, although significant underestimations remain. The implementation of CMAQ + DEM succeeded in capturing Saharan dust transport into the Iberian Peninsula, with contributions up to 25 and 14 μg m−3 in 1 h and 24 h average PM10 respectively. The general improvement of total PM10 predictions in Spain are however moderate. The analysis of model performance for the main PM components points out that remaining PM10 underestimation is due to dust local sources missing in the inventories and misrepresentation of organic aerosol processes, which constitutes the main areas for future improvement of CMAQ capabilities to simulate particulate matter within SERCA.

Evaluation of the trading development in the Iberian Energy Derivatives Market

The efficiency of the Iberian Energy Derivatives Market in its first five and a half years is assessed in terms of volume, open interest and price. The continuous market shows steady liquidity growth. Its volume is strongly correlated to that of the Over The Counter (OTC) market, the amount of market makers, the enrolment of financial agents and generation companies belonging to the integrated group of last resort suppliers, and the OTC cleared volume in its clearing house. The hedging efficiency, measured through the ratio between the final open interest and the cleared volume, shows the lowest values for the Spanish base load futures as they are the most liquid contracts. The ex-post forward risk premium has diminished due to the learning curve and the effect of the fixed price retributing the indigenous coal fired generation. This market is quite less developed than the European leaders headquartered in Norway and Germany. Enrolment of more traders, mainly international energy companies, financial agents, energy intensive industries and renewable generation companies is desired. Market monitoring reports by the market operator providing post-trade transparency, OTC data access by the energy regulator, and assessment of the regulatory risk can contribute to efficiency gains.

The role of a firm's absorptive capacity and the technology transfer process in clusters: How effective are technology centres in low-tech clusters?

This paper analyses how the internal resources of small- and medium-sized enterprises determine access (learning processes) to technology centres (TCs) or industrial research institutes (innovation infrastructure) in traditional low-tech clusters. These interactions basically represent traded (market-based) transactions, which constitute important sources of knowledge in clusters. The paper addresses the role of TCs in low-tech clusters, and uses semi-structured interviews with 80 firms in a manufacturing cluster. The results point out that producer–user interactions are the most frequent; thus, the higher the sector knowledge-intensive base, the more likely the utilization of the available research infrastructure becomes. Conversely, the sectors with less knowledge-intensive structures, i.e. less absorptive capacity (AC), present weak linkages to TCs, as they frequently prefer to interact with suppliers, who act as transceivers of knowledge. Therefore, not all the firms in a cluster can fully exploit the available research infrastructure, and their AC moderates this engagement. In addition, the existence of TCs is not sufficient since the active role of a firm's search strategies to undertake interactions and conduct openness to available sources of knowledge is also needed. The study has implications for policymakers and academia.

Optimum adhesive thickness in structural adhesives joints using statistical techniques base on Weibull distribution

The geometrical factors defining an adhesive joint are of great importance as its design greatly conditions the performance of the bonding. One of the most relevant geometrical factors is the thickness of the adhesive as it decisively influences the mechanical properties of the bonding and has a clear economic impact on the manufacturing processes or long runs. The traditional mechanical joints (riveting, welding, etc.) are characterised by a predictable performance, and are very reliable in service conditions. Thus, structural adhesive joints will only be selected in industrial applications demanding mechanical requirements and adverse environmental conditions if the suitable reliability (the same or higher than the mechanical joints) is guaranteed. For this purpose, the objective of this paper is to analyse the influence of the adhesive thickness on the mechanical behaviour of the joint and, by means of a statistical analysis based on Weibull distribution, propose the optimum thickness for the adhesive combining the best mechanical performance and high reliability. This procedure, which is applicable without a great deal of difficulty to other joints and adhesives, provides a general use for a more reliable use of adhesive bondings and, therefore, for a better and wider use in the industrial manufacturing processes.

Degradation in seawater of structural adhesives for hybrid fibre-metal laminated materials

The adhesives used for applications in marine environments are subject to particular chemical conditions, which are mainly characterised by an elevated chlorine ion content and intermittent wetting/drying cycles, among others.These conditions can limit the use of adhesives due to the degradation processes that they experience. In this work, the chemical degradation of two different polymers, polyurethane and vinylester, was studied in natural seawater under immersion for different periods of time.The diffusion coefficients and concentration profiles of water throughout the thickness of the adhesiveswere obtained.Microstructural changes in the polymer due to the action of water were observed by SEM, and the chemical degradation of the polymer was monitored with the Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The degradation of the mechanical properties of the adhesive was determined by creep tests withMixed Cantilever Beam (MCB) specimens at different temperatures. After 180 days of immersion of the specimens, it was concluded that the J-integral value (depending on the strain) implies a loss of stiffness of 51% and a decrease in the failure load of 59% for the adhesive tested.

Approach to integrate product conceptual design information into a computer-aided design system

Commercial computer-aided design systems support the geometric definition of product, but they lack utilities to support initial design stages. Typical tasks such as customer need capture, functional requirement formalization, or design parameter definition are conducted in applications that, for instance, support ?quality function deployment? and ?failure modes and effects analysis? techniques. Such applications are noninteroperable with the computer-aided design systems, leading to discontinuous design information flows. This study addresses this issue and proposes a method to enhance the integration of design information generated in the early design stages into a commercial computer-aided design system. To demonstrate the feasibility of the approach adopted, a prototype application was developed and two case studies were executed.

Numerical simulation of tangling in jet engine turbines

The numerical analysis of certain safety related problems presents serious difficulties, since the large number of components present leads to huge finite elementmodels that can only be solved by using large and expensive computers or by making rough approaches to the problem. Tangling, or clashing, in the turbine of a jet engine airplane is an example of such problems. This is caused by the crash and friction between rotor and stator blades in the turbine after an eventual shaft failure. When facing the study of an event through numerical modelling, the accurate simulation of this problem would require the engineer to model all the rotor and stator blades existing in the turbine stage, using a small element size in all pieces. Given that the number of stator and rotor blades is usually around 200, such simulations would require millions of elements. This work presents a new numerical methodology, specifically developed for the accurate modelling of the tangling problem that, depending on the turbine configuration, is able to reduce the number of nodes up to an order of magnitude without losing accuracy. The methodology, which benefits from the cyclic configuration of turbines, is successfully applied to the numerical analysis of a hypothetical tangling event in a turbine, providing valuable data such as the rotating velocity decrease of the turbine, the braking torque and the damage suffered by the blades. The methodology is somewhat general and can be applied to any problem in which damage caused by the interaction between a rotating and static piece is to be analysed.

A new approach to fuzzy estimation of Takagi-Sugeno model and its applications to optimal control for nonlinear systems

An efficient approach is presented to improve the local and global approximation and modelling capability of Takagi-Sugeno (T-S) fuzzy model. The main aim is obtaining high function approximation accuracy. The main problem is that T-S identification method cannot be applied when the membership functions are overlapped by pairs. This restricts the use of the T-S method because this type of membership function has been widely used during the last two decades in the stability, controller design and are popular in industrial control applications. The approach developed here can be considered as a generalized version of T-S method with optimized performance in approximating nonlinear functions. A simple approach with few computational effort, based on the well known parameters' weighting method is suggested for tuning T-S parameters to improve the choice of the performance index and minimize it. A global fuzzy controller (FC) based Linear Quadratic Regulator (LQR) is proposed in order to show the effectiveness of the estimation method developed here in control applications. Illustrative examples of an inverted pendulum and Van der Pol system are chosen to evaluate the robustness and remarkable performance of the proposed method and the high accuracy obtained in approximating nonlinear and unstable systems locally and globally in comparison with the original T-S model. Simulation results indicate the potential, simplicity and generality of the algorithm.

Significado e importancia de las etapas descriptiva y proyectual en los proyectos de restauración ambiental: término municipal de Mogarraz (Salamanca)

El municipio de Mogarraz (Salamanca), incluido en el Parque Natural de Las Batuecas Sierra de Francia, ha sufrido en los últimos años un intenso proceso emigratorio que ha supuesto un abandono de sus tierras y un envejecimiento poblacional. Al hacerse extensible esta realidad al resto de municipios incluidos dentro de los Espacios Protegidos de Castilla y León, surge el Programa Parques Naturales de Castilla y León (septiembre 2002), dirigido a la conservación y el desarrollo socioeconómico del medio rural. Este proyecto, apoyado en el Programa, pretende mejorar las condiciones de vida de la población de Mogarraz, recuperar la actividad económica y social, y potenciar y conservar los valores ambientales que posee. Para ello, se ha diseñado un esquema metodológico que sirve de guía para la elaboración de este tipo de proyectos de restauración. En él se plantean las etapas lógicas y secuenciales para conseguir los objetivos propuestos. El proyecto incluye: etapa descriptiva, diagnóstico de los problemas ambientales, propuesta de soluciones, y etapa proyectual de las actuaciones prioritarias: restauración del área de descanso del núcleo urbano, y recuperación de un antiguo camino con el fin de convertirlo en senda ecológica. Finaliza con el pliego de condiciones, planos, y presupuesto de las obras.

Automating HAZOP studies using D-higraphs

In this paper, we present the use of D-higraphs to perform HAZOP studies. D-higraphs is a formalism that includes in a single model the functional as well as the structural (ontological) components of any given system. A tool to perform a semi-automatic guided HAZOP study on a process plant is presented. The diagnostic system uses an expert system to predict the behavior modeled using D-higraphs. This work is applied to the study of an industrial case and its results are compared with other similar approaches proposed in previous studies. The analysis shows that the proposed methodology fits its purpose enabling causal reasoning that explains causes and consequences derived from deviations, it also fills some of the gaps and drawbacks existing in previous reported HAZOP assistant tools.

Análisis y Propuesta metodológica para el Diseño y Fabricación de una Cubertería.

Diseño y fabricación de una cubertería adaptada a personas discapacitadas.

Incorporacion de metodologias y herramientas para alcanzar el diseño integrado por ordenador.

La información que soportan los actuales sistemas PLM/CAD está relacionada principalmente con las fases de diseño de forma y de diseño de detalle y la información relacionada con la fase de diseño conceptual se limita mayoritariamente a la documentación de especificación de requerimientos. Los sistemas comerciales CAD están pensados para soportar la definición geométrica de producto, pero carecen de utilidades que les permitan soportar las etapas iniciales del diseño. Las tareas típicas del diseño conceptual tales como: la captura de necesidades del cliente, la formalización de requerimientos funcionales o la definición de parámetros de diseño, son realizadas en aplicaciones no interoperables con los sistemas CAD. Esta situación causa una discontinuidad en el flujo de información de diseño: necesidades del cliente – requerimientos funcionales – parámetros de diseño – características críticas – parámetros geométricos. Para solventar este aspecto y facilitar el reuso del conocimiento, en este trabajo se propone un marco para desarrollar una aplicación basada en el conocimiento (KBA) e integrar las herramientas de diseño: despliegue de la función de calidad (QFD), diseño axiomático, análisis de modos y efectos de fallo (FMEA) y la metodología MOKA. El objetivo de esta propuesta es ayudar en la integración de aspectos del diseño conceptual en el proceso de diseño, así como su flujo de información asociado dentro de un sistema CAD comercial. Esta tesis propone mejorar la integración de la información de diseño generado en las etapas más tempranas del diseño dentro de un sistema CAD. Esta investigación presenta la metodología para realizar el desarrollo, el entorno de una aplicación informática, el modelado de información de la aplicación propuesta y la conducción de resultados de la implementación de dicha aplicación informática. Dos casos de estudio son llevados a cabo para validar la metodología propuesta y para evaluar el desarrollo de una aplicación con una interfaz de programación dentro del sistema CAD comercial, todo ello para soportar el flujo de información. El primer caso de estudio está relacionado con el desarrollo de un KBA para el diseño de un componente del embrague de fricción de un automóvil a combustión. El segundo caso trata sobre el desarrollo de una aplicación KBA para el diseño de un componente estructural del fuselaje posterior de un avión comercial de pasajeros. Los resultados obtenidos muestran como la implementación del marco integrado en el sistema KBA podría beneficiar al diseñador en una forma práctica.