915 resultados para Second Order Parabolic Heat Equation


Relevância:

100.00% 100.00%

Publicador:

Resumo:

The present study investigated the relationship between psychometric intelligence and temporal resolution power (TRP) as simultaneously assessed by auditory and visual psychophysical timing tasks. In addition, three different theoretical models of the functional relationship between TRP and psychometric intelligence as assessed by means of the Adaptive Matrices Test (AMT) were developed. To test the validity of these models, structural equation modeling was applied. Empirical data supported a hierarchical model that assumed auditory and visual modality-specific temporal processing at a first level and amodal temporal processing at a second level. This second-order latent variable was substantially correlated with psychometric intelligence. Therefore, the relationship between psychometric intelligence and psychophysical timing performance can be explained best by a hierarchical model of temporal information processing.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Surface tension induced convection in a liquid bridge held between two parallel, coaxial, solid disks is considered. The surface tension gradient is produced by a small temperature gradient parallel Co the undisturbed surface. The study is performed by using a mathematical regular perturbation approach based on a small parameter, e, which measures the deviation of the imposed temperature field from its mean value. The first order velocity field is given by a Stokes-type problem (viscous terms are dominant) with relatively simple boundary conditions. The first order temperature field is that imposed from the end disks on a liquid bridge immersed in a non-conductive fluid. Radiative effects are supposed to be negligible. The second order temperature field, which accounts for convective effects, is split into three components, one due to the bulk motion, and the other two to the distortion of the free surface. The relative importance of these components in terms of the heat transfer to or from the end disks is assessed

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Fission product yields are fundamental parameters for several nuclear engineering calculations and in particular for burn-up/activation problems. The impact of their uncertainties was widely studied in the past and valuations were released, although still incomplete. Recently, the nuclear community expressed the need for full fission yield covariance matrices to produce inventory calculation results that take into account the complete uncertainty data. In this work, we studied and applied a Bayesian/generalised least-squares method for covariance generation, and compared the generated uncertainties to the original data stored in the JEFF-3.1.2 library. Then, we focused on the effect of fission yield covariance information on fission pulse decay heat results for thermal fission of 235U. Calculations were carried out using different codes (ACAB and ALEPH-2) after introducing the new covariance values. Results were compared with those obtained with the uncertainty data currently provided by the library. The uncertainty quantification was performed with the Monte Carlo sampling technique. Indeed, correlations between fission yields strongly affect the statistics of decay heat. Introduction Nowadays, any engineering calculation performed in the nuclear field should be accompanied by an uncertainty analysis. In such an analysis, different sources of uncertainties are taken into account. Works such as those performed under the UAM project (Ivanov, et al., 2013) treat nuclear data as a source of uncertainty, in particular cross-section data for which uncertainties given in the form of covariance matrices are already provided in the major nuclear data libraries. Meanwhile, fission yield uncertainties were often neglected or treated shallowly, because their effects were considered of second order compared to cross-sections (Garcia-Herranz, et al., 2010). However, the Working Party on International Nuclear Data Evaluation Co-operation (WPEC)

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The bankability of CPV projects is an important issue to pave the way toward a swift and sustained growth in this technology. The bankability of a PV plant is generally addressed through the modeling of its energy yield under a b aseline loss scenario, followed by an on-site measurement campaign aimed at verifying its energetic behavior. The main difference between PV and CPV resides in the proper CPV modules, in particular in the inclusion of optical lements and III-V multijunction cells that are much more sensitive to spectral variations than xSi cells, while the rest of the system behaves in a way that possesses many common points with xSi technology. The modeling of the DC power output of a CPV system thus requires several impo rtant second order parameters to be considered, mainly related to optics, spectral direct solar radiation, wind speed, tracker accuracy and heat dissipation of cells.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

La ecuación en derivadas parciales de advección difusión con reacción química es la base de los modelos de dispersión de contaminantes en la atmósfera, y los diferentes métodos numéricos empleados para su resolución han sido objeto de amplios estudios a lo largo de su desarrollo. En esta Tesis se presenta la implementación de un nuevo método conservativo para la resolución de la parte advectiva de la ecuación en derivadas parciales que modela la dispersión de contaminantes dentro del modelo mesoescalar de transporte químico CHIMERE. Este método está basado en una técnica de volúmenes finitos junto con una interpolación racional. La ventaja de este método es la conservación exacta de la masa transportada debido al empleo de la ley de conservación de masas. Para ello emplea una formulación de flujo basado en el cálculo de la integral ponderada dentro de cada celda definida para la discretización del espacio en el método de volúmenes finitos. Los resultados numéricos obtenidos en las simulaciones realizadas (implementando el modelo conservativo para la advección en el modelo CHIMERE) se han comparado con los datos observados de concentración de contaminantes registrados en la red de estaciones de seguimiento y medición distribuidas por la Península Ibérica. Los datos estadísticos de medición del error, la media normalizada y la media absoluta normalizada del error, presentan valores que están dentro de los rangos propuestos por la EPA para considerar el modelo preciso. Además, se introduce un nuevo método para resolver la parte advectivadifusiva de la ecuación en derivadas parciales que modeliza la dispersión de contaminantes en la atmósfera. Se ha empleado un método de diferencias finitas de alto orden para resolver la parte difusiva de la ecuación de transporte de contaminantes junto con el método racional conservativo para la parte advectiva en una y dos dimensiones. Los resultados obtenidos de la aplicación del método a diferentes situaciones incluyendo casos académicos y reales han sido comparados con la solución analítica de la ecuación de advección-difusión, demostrando que el nuevo método proporciona un resultado preciso para aproximar la solución. Por último, se ha desarrollado un modelo completo que contempla los fenómenos advectivo y difusivo con reacción química, usando los métodos anteriores junto con una técnica de diferenciación regresiva (BDF2). Esta técnica consiste en un método implícito multipaso de diferenciación regresiva de segundo orden, que nos permite resolver los problemas rígidos típicos de la química atmosférica, modelizados a través de sistemas de ecuaciones diferenciales ordinarias. Este método hace uso de la técnica iterativa Gauss- Seidel para obtener la solución de la parte implícita de la fórmula BDF2. El empleo de la técnica de Gauss-Seidel en lugar de otras técnicas comúnmente empleadas, como la iteración por el método de Newton, nos proporciona rapidez de cálculo y bajo consumo de memoria, ideal para obtener modelos operativos para la resolución de la cinética química atmosférica. ABSTRACT Extensive research has been performed to solve the atmospheric chemicaladvection- diffusion equation and different numerical methods have been proposed. This Thesis presents the implementation of an exactly conservative method for the advection equation in the European scale Eulerian chemistry transport model CHIMERE based on a rational interpolation and a finite volume algorithm. The advantage of the method is that the cell-integrated average is predicted via a flux formulation, thus the mass is exactly conserved. Numerical results are compared with a set of observation registered at some monitoring sites in Spain. The mean normalized bias and the mean normalized absolute error present values that are inside the range to consider an accurate model performance. In addition, it has been introduced a new method to solve the advectiondiffusion equation. It is based on a high-order accurate finite difference method to solve de diffusion equation together with a rational interpolation and a finite volume to solve the advection equation in one dimension and two dimensions. Numerical results obtained from solving several problems include academic and real atmospheric problems have been compared with the analytical solution of the advection-diffusion equation, showing that the new method give an efficient algorithm for solving such problems. Finally, a complete model has been developed to solve the atmospheric chemical-advection-diffusion equation, adding the conservative method for the advection equation, the high-order finite difference method for the diffusion equation and a second-order backward differentiation formula (BDF2) to solve the atmospheric chemical kinetics. The BDF2 is an implicit, second order multistep backward differentiation formula used to solve the stiff systems of ordinary differential equations (ODEs) from atmospheric chemistry. The Gauss-Seidel iteration is used for approximately solving the implicitly defined BDF solution, giving a faster tool than the more commonly used iterative modified Newton technique. This method implies low start-up costs and a low memory demand due to the use of Gauss-Seidel iteration.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

En el campo de la fusión nuclear y desarrollándose en paralelo a ITER (International Thermonuclear Experimental Reactor), el proyecto IFMIF (International Fusion Material Irradiation Facility) se enmarca dentro de las actividades complementarias encaminadas a solucionar las barreras tecnológicas que aún plantea la fusión. En concreto IFMIF es una instalación de irradiación cuya misión es caracterizar materiales resistentes a condiciones extremas como las esperadas en los futuros reactores de fusión como DEMO (DEMOnstration power plant). Consiste de dos aceleradores de deuterones que proporcionan un haz de 125 mA y 40 MeV cada uno, que al colisionar con un blanco de litio producen un flujo neutrónico intenso (1017 neutrones/s) con un espectro similar al de los neutrones de fusión [1], [2]. Dicho flujo neutrónico es empleado para irradiar los diferentes materiales candidatos a ser empleados en reactores de fusión, y las muestras son posteriormente examinadas en la llamada instalación de post-irradiación. Como primer paso en tan ambicioso proyecto, una fase de validación y diseño llamada IFMIFEVEDA (Engineering Validation and Engineering Design Activities) se encuentra actualmente en desarrollo. Una de las actividades contempladas en esta fase es la construcción y operación de una acelarador prototipo llamado LIPAc (Linear IFMIF Prototype Accelerator). Se trata de un acelerador de deuterones de alta intensidad idéntico a la parte de baja energía de los aceleradores de IFMIF. Los componentes del LIPAc, que será instalado en Japón, son suministrados por diferentes países europeos. El acelerador proporcionará un haz continuo de deuterones de 9 MeV con una potencia de 1.125 MW que tras ser caracterizado con diversos instrumentos deberá pararse de forma segura. Para ello se requiere un sistema denominado bloque de parada (Beam Dump en inglés) que absorba la energía del haz y la transfiera a un sumidero de calor. España tiene el compromiso de suministrar este componente y CIEMAT (Centro de Investigaciones Energéticas Medioambientales y Tecnológicas) es responsable de dicha tarea. La pieza central del bloque de parada, donde se para el haz de iones, es un cono de cobre con un ángulo de 3.5o, 2.5 m de longitud y 5 mm de espesor. Dicha pieza está refrigerada por agua que fluye en su superficie externa por el canal que se forma entre el cono de cobre y otra pieza concéntrica con éste. Este es el marco en que se desarrolla la presente tesis, cuyo objeto es el diseño del sistema de refrigeración del bloque de parada del LIPAc. El diseño se ha realizado utilizando un modelo simplificado unidimensional. Se han obtenido los parámetros del agua (presión, caudal, pérdida de carga) y la geometría requerida en el canal de refrigeración (anchura, rugosidad) para garantizar la correcta refrigeración del bloque de parada. Se ha comprobado que el diseño permite variaciones del haz respecto a la situación nominal siendo el flujo crítico calorífico al menos 2 veces superior al nominal. Se han realizado asimismo simulaciones fluidodinámicas 3D con ANSYS-CFX en aquellas zonas del canal de refrigeración que lo requieren. El bloque de parada se activará como consecuencia de la interacción del haz de partículas lo que impide cualquier cambio o reparación una vez comenzada la operación del acelerador. Por ello el diseño ha de ser muy robusto y todas las hipótesis utilizadas en la realización de éste deben ser cuidadosamente comprobadas. Gran parte del esfuerzo de la tesis se centra en la estimación del coeficiente de transferencia de calor que es determinante en los resultados obtenidos, y que se emplea además como condición de contorno en los cálculos mecánicos. Para ello por un lado se han buscado correlaciones cuyo rango de aplicabilidad sea adecuado para las condiciones del bloque de parada (canal anular, diferencias de temperatura agua-pared de decenas de grados). En un segundo paso se han comparado los coeficientes de película obtenidos a partir de la correlación seleccionada (Petukhov-Gnielinski) con los que se deducen de simulaciones fluidodinámicas, obteniendo resultados satisfactorios. Por último se ha realizado una validación experimental utilizando un prototipo y un circuito hidráulico que proporciona un flujo de agua con los parámetros requeridos en el bloque de parada. Tras varios intentos y mejoras en el experimento se han obtenido los coeficientes de película para distintos caudales y potencias de calentamiento. Teniendo en cuenta la incertidumbre de las medidas, los valores experimentales concuerdan razonablemente bien (en el rango de 15%) con los deducidos de las correlaciones. Por motivos radiológicos es necesario controlar la calidad del agua de refrigeración y minimizar la corrosión del cobre. Tras un estudio bibliográfico se identificaron los parámetros del agua más adecuados (conductividad, pH y concentración de oxígeno disuelto). Como parte de la tesis se ha realizado asimismo un estudio de la corrosión del circuito de refrigeración del bloque de parada con el doble fin de determinar si puede poner en riesgo la integridad del componente, y de obtener una estimación de la velocidad de corrosión para dimensionar el sistema de purificación del agua. Se ha utilizado el código TRACT (TRansport and ACTivation code) adaptándalo al caso del bloque de parada, para lo cual se trabajó con el responsable (Panos Karditsas) del código en Culham (UKAEA). Los resultados confirman que la corrosión del cobre en las condiciones seleccionadas no supone un problema. La Tesis se encuentra estructurada de la siguiente manera: En el primer capítulo se realiza una introducción de los proyectos IFMIF y LIPAc dentro de los cuales se enmarca esta Tesis. Además se describe el bloque de parada, siendo el diseño del sistema de rerigeración de éste el principal objetivo de la Tesis. En el segundo y tercer capítulo se realiza un resumen de la base teórica así como de las diferentes herramientas empleadas en el diseño del sistema de refrigeración. El capítulo cuarto presenta los resultados del relativos al sistema de refrigeración. Tanto los obtenidos del estudio unidimensional, como los obtenidos de las simulaciones fluidodinámicas 3D mediante el empleo del código ANSYS-CFX. En el quinto capítulo se presentan los resultados referentes al análisis de corrosión del circuito de refrigeración del bloque de parada. El capítulo seis se centra en la descripción del montaje experimental para la obtención de los valores de pérdida de carga y coeficiente de transferencia del calor. Asimismo se presentan los resultados obtenidos en dichos experimentos. Finalmente encontramos un capítulo de apéndices en el que se describen una serie de experimentos llevados a cabo como pasos intermedios en la obtención del resultado experimental del coeficiente de película. También se presenta el código informático empleado para el análisis unidimensional del sistema de refrigeración del bloque de parada llamado CHICA (Cooling and Heating Interaction and Corrosion Analysis). ABSTRACT In the nuclear fusion field running in parallel to ITER (International Thermonuclear Experimental Reactor) as one of the complementary activities headed towards solving the technological barriers, IFMIF (International Fusion Material Irradiation Facility) project aims to provide an irradiation facility to qualify advanced materials resistant to extreme conditions like the ones expected in future fusion reactors like DEMO (DEMOnstration Power Plant). IFMIF consists of two constant wave deuteron accelerators delivering a 125 mA and 40 MeV beam each that will collide on a lithium target producing an intense neutron fluence (1017 neutrons/s) with a similar spectra to that of fusion neutrons [1], [2]. This neutron flux is employed to irradiate the different material candidates to be employed in the future fusion reactors, and the samples examined after irradiation at the so called post-irradiative facilities. As a first step in such an ambitious project, an engineering validation and engineering design activity phase called IFMIF-EVEDA (Engineering Validation and Engineering Design Activities) is presently going on. One of the activities consists on the construction and operation of an accelerator prototype named LIPAc (Linear IFMIF Prototype Accelerator). It is a high intensity deuteron accelerator identical to the low energy part of the IFMIF accelerators. The LIPAc components, which will be installed in Japan, are delivered by different european countries. The accelerator supplies a 9 MeV constant wave beam of deuterons with a power of 1.125 MW, which after being characterized by different instruments has to be stopped safely. For such task a beam dump to absorb the beam energy and take it to a heat sink is needed. Spain has the compromise of delivering such device and CIEMAT (Centro de Investigaciones Energéticas Medioambientales y Tecnológicas) is responsible for such task. The central piece of the beam dump, where the ion beam is stopped, is a copper cone with an angle of 3.5o, 2.5 m long and 5 mm width. This part is cooled by water flowing on its external surface through the channel formed between the copper cone and a concentric piece with the latter. The thesis is developed in this realm, and its objective is designing the LIPAc beam dump cooling system. The design has been performed employing a simplified one dimensional model. The water parameters (pressure, flow, pressure loss) and the required annular channel geometry (width, rugoisty) have been obtained guaranteeing the correct cooling of the beam dump. It has been checked that the cooling design allows variations of the the beam with respect to the nominal position, being the CHF (Critical Heat Flux) at least twice times higher than the nominal deposited heat flux. 3D fluid dynamic simulations employing ANSYS-CFX code in the beam dump cooling channel sections which require a more thorough study have also been performed. The beam dump will activateasaconsequenceofthe deuteron beam interaction, making impossible any change or maintenance task once the accelerator operation has started. Hence the design has to be very robust and all the hypotheses employed in the design mustbecarefully checked. Most of the work in the thesis is concentrated in estimating the heat transfer coefficient which is decisive in the obtained results, and is also employed as boundary condition in the mechanical analysis. For such task, correlations which applicability range is the adequate for the beam dump conditions (annular channel, water-surface temperature differences of tens of degrees) have been compiled. In a second step the heat transfer coefficients obtained from the selected correlation (Petukhov- Gnielinski) have been compared with the ones deduced from the 3D fluid dynamic simulations, obtaining satisfactory results. Finally an experimental validation has been performed employing a prototype and a hydraulic circuit that supplies a flow with the requested parameters in the beam dump. After several tries and improvements in the experiment, the heat transfer coefficients for different flows and heating powers have been obtained. Considering the uncertainty in the measurements the experimental values agree reasonably well (in the order of 15%) with the ones obtained from the correlations. Due to radiological reasons the quality of the cooling water must be controlled, hence minimizing the copper corrosion. After performing a bibligraphic study the most adequate water parameters were identified (conductivity, pH and dissolved oxygen concentration). As part of this thesis a corrosion study of the beam dump cooling circuit has been performed with the double aim of determining if corrosion can pose a risk for the copper beam dump , and obtaining an estimation of the corrosion velocitytodimension the water purification system. TRACT code(TRansport and ACTivation) has been employed for such study adapting the code for the beam dump case. For such study a collaboration with the code responsible (Panos Karditsas) at Culham (UKAEA) was established. The work developed in this thesis has supposed the publication of three articles in JCR journals (”Journal of Nuclear Materials” y ”Fusion Engineering and Design”), as well as presentations in more than four conferences and relevant meetings.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

La presente investigación tiene como objetivo el desarrollo de una metodología que favorezca la innovación en las empresas a través de la actividad directiva, analizando a su vez, su influencia a nivel macro, en los sistemas de innovación, en las políticas de innovación y en el capital intelectual y a nivel micro, en la innovación, en el desempeño y en el clima organizacional. Se estima importante realizar un estudio sobre este tema debido a que la innovación se considera un pilar crítico para el desarrollo social a través de la competitividad de las empresas, así como, una fuente importante de ventaja competitiva. Existe abundante literatura sobre la influencia de la innovación en la gestión empresarial y el papel que el liderazgo desempeña en términos generales. Sin embargo, la literatura presenta diversos estilos de liderazgo sin mostrar una línea consistente de interrelación entre ellos, por lo que finalmente no existe una relación sólida entre el liderazgo, la gestión empresarial y la innovación. Este hecho se debe, como se muestra en la tesis, a que la literatura analiza las organizaciones y el liderazgo desde una perspectiva sociológica u organizacional, y otra desde la perspectiva psicológica sin aportar una línea de articulación entre ambas. Es decir, la literatura analiza el comportamiento organizacional pero no su causa. A lo largo de la tesis se van desarrollando diferentes líneas de trabajo que se convierten en aportaciones empíricas y académicas. Así, una de las aportaciones de la tesis es la sustitución de la figura del líder como persona, por la de un directivo con una doble función; por un lado, la función de liderazgo cuyo objetivo es generar cambio y por el otro, la función de gestionar el día a día o desempeño. Sustituir la figura del líder por una doble funcionalidad directiva facilita la comprensión del concepto liderazgo, lo que permite a su vez, establecer estrategias para su desarrollo, haciendo una realidad el que el liderazgo puede ser aprendido. Este resultado constituye la primera aportación de la tesis. Así mismo, a través de un exhaustivo análisis de la literatura, se desarrolla una propuesta de liderazgo integrado de acuerdo con el modelo Stuart-Kotze, el cual se describe también ampliamente. Encontrar un modelo único de liderazgo supone la piedra angular para el desarrollo de la metodología. Esta propuesta de liderazgo integrado da lugar a la segunda aportación de la tesis. Del mismo modo, se realiza un estudio en profundidad de la perspectiva psicológica de las organizaciones desarrollando el constructo Miedo al Error (ME) que resulta ser un rasgo de la personalidad existente en todos los seres humanos y que presenta una influencia negativa tanto en el desempeño, como en la innovación empresarial. Este resultado permite identificar cuales son las verdaderas barreras para el ejercicio del liderazgo, señalando que la disminución del ME debe ser considerada como una competencia de la Inteligencia Emocional a ser desarrollada por los directivos. Este resultado constituye la tercera aportación de la tesis. Una vez desarrollado el modelo de gestión empresarial expuesto, se procede a su validación, analizando la relación entre los constructos que definen el modelo de gestión: el desempeño, la innovación y el ME. Para identificar las influencias o relaciones de causalidad que subyacen entre los constructos, se utilizó la técnica del modelo de ecuaciones estructurales (SEM). La población objeto de estudio estuvo constituida por 350 profesionales con responsabilidad directiva, procedentes de empresas del sector servicios repartidas por toda la geografía española. Como fuente primaria de recolección de información se utilizó el cuestionario desarrollado por Stuart-Kotze M-CPI (Momentum Continuous Performance Improvement). En primer lugar se procedió a evaluar las propiedades psicométricas del modelo de medida, llevándose a cabo un análisis factorial exploratorio (AFE) y un análisis factorial confirmatorio (AFC) de segundo orden. Los resultados obtenidos ponen de manifiesto que el constructo desempeño (D) viene determinado por dos dimensiones, (DOP), desempeño orientado hacia la planificación y (DORT), desempeño orientado hacia la realización de la tarea. Es decir, la muestra de directivos no percibe que la planificación en el día a día y la realización de la tarea estén articuladas. Posteriormente se procede a realizar el contraste del modelo a través del método de ecuaciones estructurales. Los resultados muestran que la relación de influencia de la dimensión DOP no es significativa, por lo que el constructo D queda representado únicamente por la dimensión DORT. Los resultados de la investigación proporcionan conclusiones e hipótesis para futuras investigaciones. Si bien la muestra de directivos realiza un plan estratégico, éste no se tiene en cuenta en el día a día. Este hecho podría explicar el alto grado de administración por crisis tan frecuente en la empresa española. A su vez, el ME presenta una influencia negativa en la innovación, lo que concuerda con la literatura. Al respecto, considerar el ME como un rasgo de la personalidad, presente tanto en directivos como en colaboradores, facilita la comprensión de las barreras de la organización hacia la comunicación abierta a la vez, que una dirección de trabajo para la mejora de la capacidad innovadora de la organización. Por último, los resultados establecen la existencia de una relación causal entre el desempeño diario y la innovación. Con respecto a este segundo resultado y analizando los comportamientos que identifican el constructo D surgen también varias conclusiones e hipótesis para futuras investigaciones. Los resultados ponen de manifiesto que la muestra de directivos genera iniciativas de cambio con la finalidad de que el trabajo diario salga adelante según los estándares de calidad definidos. Sin embargo, estas iniciativas sólo proceden de los directivos, sin participación alguna de los colaboradores, los cuales son sólo responsables de la implementación produciéndose la consiguiente desmotivación y pérdida de oportunidades. Esta conclusión pone de manifiesto que la innovación de las empresas de la muestra sucede para garantizar la eficiencia de los procesos existentes, pero en ningún caso surge de la iniciativa de buscar una mejor eficacia empresarial. Este hecho plantea un origen doble de la innovación en los procesos. La innovación proactiva que buscaría la mejora de la eficacia de la organización y una innovación de carácter reactiva que buscaría la salvaguarda de la eficiencia. Quizás sea esta la causa del gap existente entre la innovación en España y la innovación de los países que ocupan los primeros puestos en el ranking de producción de innovación lo que constituye un importante punto de partida para una investigación futura. ABSTRACT This research aims to develop a methodology that supports innovation in companies through the managers’ activity, analysing in turn its influence at the macro level: innovation systems, innovation policies and Intellectual capital and at the micro level: innovation itself, performance and organizational climate. It is considered important to conduct a study on this subject due to the fact that innovation is considered a critical pillar for the development and future of the enterprise and an important source of competitive advantage. There is abundant literature about the influence of innovation in business management and the role that leadership plays in general terms. However, the literature presents various styles of leadership without showing a consistent relationship among them, so finally there is not a strong relationship among leadership, business management and innovation. As shown in the thesis, this is due to the fact that the literature analyses organizations and leadership from a sociological or organizational perspective and from a psychological perspective, without providing a hinge line between the two. That is, the existing literature discusses organizational behaviour but not its cause. Throughout the thesis, different lines of work that become empirical and academic contributions have been developed. Thus, one of the contributions of the thesis is replacing the figure of the leader as a person, by a manager with a dual function. Firstly, we have the leadership role which aims to generate change and, on the other hand, the function to manage the day-to-day task or performance. Replacing the figure of the leader by a dual managerial functionality facilitates the understanding of the leadership concept, allowing in turn, to establish development strategies and making true that leadership can be learned. This outcome is the first contribution of the thesis. Likewise, through a comprehensive literature review, an integrated leadership proposal is developed, according to the Kotze model, which is also described widely. Finding a specific leadership model represents the cornerstone for the development of the methodology. This integrated leadership proposal leads to the second contribution of the thesis. Similarly, an in-depth study was conducted about the psychological perspective of the organizations disclosing the construct Fear of Failure. This construct is a personality trait that exists in all human beings and has a negative influence on both performance and business innovation. This outcome allows identifying which are the real barriers to the exercise of leadership, noting that the decrease in fear of failure must be considered as an Emotional Intelligence competence to be developed by managers. This outcome represents the third contribution of the thesis. Once a business management model has been developed, we proceed to its validation by analysing the relationship among the model constructs: management, innovation and fear of failure. To identify the influence or causal relationships underlying the constructs, a structural equation model (SEM) technique was used. The study population consisted of 350 professionals with managerial responsibility, from companies in the services sector scattered throughout the Spanish geography. As a primary source for gathering information a questionnaire developed by Kotze M-CPI (Continuous Performance Improvement Momentum) was used. First we proceeded to evaluate the psychometric properties of the measurement model, carrying out an exploratory factorial analysis (EFA) and a confirmatory factorial analysis (CFA) of second order. The results show that the performance construct D is determined by two-dimensions (DOP: performance oriented to planning) and (DORT: aiming at the realization of the task). That is, the sample of managers does not perceive that planning and the daily task are articulated. Then, we proceeded to make the contrast of the model through a structural equation model SEM. The results show that the influence of the DOP dimension is not significant, so that only the DORT dimension finally represents the construct D. The research outcomes provide conclusions and hypotheses for future research. Although the managers in the sample develop a strategic plan, it seems that managers do not take it into account in their daily tasks. This could explain the high degree of crisis management so prevalent in the Spanish companies. In turn, the fear of failure has a negative influence on innovation, consistent with the literature. In this regard, the fear of failure is considered as a personality trait, present in both managers and employees, which enables the understanding of organizational barriers to open communication and provides a direction to improve the organization’s innovative capacity as well. Finally, the results establish a causal relationship between daily performance and innovation. Regarding this second outcome and analysing the behaviours that identify the construct D, several conclusions and hypotheses for future research arise as well. The results show that the managers in the sample show initiatives of change in order to make everyday work go ahead, according to defined quality standards. However, these initiatives only come from managers without any participation of coworkers, which are only responsible for the implementation, and this produces discouragement and loss of opportunities. This finding shows that the innovation by the companies in the sample happens to guarantee the efficiency of existing processes, but do not arise from an initiative that seeks better business efficacy. This raises two sources of innovation in processes. The first source would be a proactive innovation that would seek improved organizational efficacy. The second one is a reactive innovation that would seek to safeguard efficiency. Perhaps this is the cause of the existing gap between the innovation activity in Spain and the innovation activity in those countries that occupy the top positions in the ranking of innovation outcomes. The Spanish companies seek process efficiency and the top innovators business efficacy. This is an important starting point for future research.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

In this work the thermal analysis of a small satellite orbiting around the Earth has been approached by direct integration of the heat balance equations of a two-node reduced model, obtaining a linearized second order ODE problem, similar in form to the classical case of the forced vibration of a damped system. As the thermal loads (solar radiation, albedo, etc.) are harmonic, the problem is solved by means of Fourier analysis methods. Research on that field can be directly applied to the analysis of thermal problems and the results obtained are satisfactory. Working on the frequency domain streamlines the analysis, simplifies the study and facilitates the experimental testing. The transfer functions are obtained for the two-node case but the study can be extended to an n-node model.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A first-order Lagrangian L ∇ variationally equivalent to the second-order Einstein- Hilbert Lagrangian is introduced. Such a Lagrangian depends on a symmetric linear connection, but the dependence is covariant under diffeomorphisms. The variational problem defined by L ∇ is proved to be regular and its Hamiltonian formulation is studied, including its covariant Hamiltonian attached to ∇ .

Relevância:

100.00% 100.00%

Publicador:

Resumo:

It is presented a mathematical model of the oculomotor plant, based on experimental data in cats. The system that generates, from the neuronal processes at the motoneuron, the control signals to the eye muscles that moves the eye. In contrast with previous models, that base the eye movement related motoneuron behavior on a first order linear differential equation, non-linear effects are described: A dependency on the eye angular position of the model parameters.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Graphs of second harmonic generation coefficients and electro-optic coefficients (measured by ellipsometry, attenuated total reflection, and two-slit interference modulation) as a function of chromophore number density (chromophore loading) are experimentally observed to exhibit maxima for polymers containing chromophores characterized by large dipole moments and polarizabilities. Modified London theory is used to demonstrated that this behavior can be attributed to the competition of chromophore-applied electric field and chromophore–chromophore electrostatic interactions. The comparison of theoretical and experimental data explains why the promise of exceptional macroscopic second-order optical nonlinearity predicted for organic materials has not been realized and suggests routes for circumventing current limitations to large optical nonlinearity. The results also suggest extensions of measurement and theoretical methods to achieve an improved understanding of intermolecular interactions in condensed phase materials including materials prepared by sequential synthesis and block copolymer methods.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We present the first detailed numerical study in three dimensions of a first-order phase transition that remains first order in the presence of quenched disorder (specifically, the ferromagnetic-paramagnetic transition of the site-diluted four states Potts model). A tricritical point, which lies surprisingly near the pure-system limit and is studied by means of finite-size scaling, separates the first-order and second-order parts of the critical line. This investigation has been made possible by a new definition of the disorder average that avoids the diverging-variance probability distributions that plague the standard approach. Entropy, rather than free energy, is the basic object in this approach that exploits a recently introduced microcanonical Monte Carlo method.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We present a detailed numerical study on the effects of adding quenched impurities to a three dimensional system which in the pure case undergoes a strong first order phase transition (specifically, the ferromagnetic/paramagnetic transition of the site-diluted four states Potts model). We can state that the transition remains first-order in the presence of quenched disorder (a small amount of it) but it turns out to be second order as more impurities are added. A tricritical point, which is studied by means of Finite-Size Scaling, separates the first-order and second-order parts of the critical line. The results were made possible by a new definition of the disorder average that avoids the diverging-variance probability distributions that arise using the standard methodology. We also made use of a recently proposed microcanonical Monte Carlo method in which entropy, instead of free energy, is the basic quantity.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

In this work we prensent an analysis of non-slanted reflection gratings by using exact solution of the second order differential equation derived from Maxwell equations, in terms of Mathieu functions. The results obtained by using this method will be compared to those obtained by using the well known Kogelnik's Coupled Wave Theory which predicts with great accuracy the response of the efficieny of the zero and first order for volume phase gratings, for both reflection and transmission gratings.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Equations for the intramolecular surfaces of the 3JHH coupling constants in ethane, ethylene, and acetylene are formulated, and the corresponding coefficients are estimated from calculations at the DFT/B3LYP level. The chosen variables are changes in bond lengths, in the torsion angle φ between the coupled protons Ha and Hb, in bond angles, and in dihedral angles. The 3JHH surface of ethane is formulated as an extended Karplus equation with the coefficients of a truncated Fourier series on the torsion angle φ expanded as second-order Taylor series in the chosen variables taking into account the invariance of 3JHH under reflections and rotations of nuclear coordinates. Partial vibrational contributions from linear and square terms corresponding to changes in the geometry of the Ha − Ca − Cb − Hb fragment are important while those from cross terms are small with a few exceptions. The 3JHH surface of ethane is useful to predict contributions to 3JHH from changes in local geometry of derivatives but vibrational contributions are predicted less satisfactorily. The predicted values at the B3LYP/BS2 level of the 3JHH couplings (vibrational contributions at 300 K) from equilibrium geometries are 9.79 (−0.17) for acetylene, and 17.08 (1.93) and 10.73(0.93) for the trans and cis couplings of ethylene.