General solutions for some classes of interacting two field kinks

In this work we present some classes of models whose the corresponding two coupled first-order nonlinear equations can be put into a linear form, and consequently be solved completely. In these cases the so-called trial orbit method is completely unnecessary. We recall that some physically important models as, for instance, the problem of tiling a plane with a network of defects and polymer properties are in this class of models. (c) 2005 Elsevier B.V. All rights reserved.

Direct Cartesian-Space Solutions of Generalized Bloch Equations in the Rotating Frame

Analytical solutions of the generalized Bloch equations for an arbitrary set of initial values of the x, y, and z magnetization components are given in the rotating frame. The solutions involve the decoupling of the three coupled differential equations such that a third-order differential equation in each magnetization variable is obtained. In contrast to the previously reported solutions given by Torrey, the present attempt paves the way for more direct physical insight into the behavior of each magnetization component. Special cases have been discussed that highlight the utility of the general solutions. Representative trajectories of magnetization components are given, illustrating their behavior with respect to the values of off-resonance and initial conditions. (C) 1995 Academic Press, Inc.

Static equilibrium of horizontal ring prominence

In 1980 the Beijing Observatory had successively observed sevesal rare completely closed ring prominences whose ring plane was approximately parallel to the solar surface with a characteristic life about 1—2 days. In this paper we discuss the static equilibrium of this kind of horizontal ring plasma under the simultaneous actions of magnetic force, gravity and pressure gradients. Assuming ring plasma with axisymmetry and rectangular plasma cross-section and adopting closed magnetic field boundary condition from the basic equations we obtain the exact zero order general solutions for magnetic field (force-free field) and density (pressure). We further obtain an eigen-solution for the zero order magnetic field and density as well as the first order magnetic field, thus giving a kind of the possible distribution of magnetic field and density for the horizontal closed ring prominence. The closed magnetic structure of ring prominence as presented in this paper, has no link with the force lines of the outside corona magnetic field. This is helpful to explain the great temperature difference between prominenee and corona.

Understanding Tariff Deficit and its Challenges

Regulators and market participants have become increasingly concerned about the Spanish electricity tariff deficit due to its size and the difficulties to control its growth. The deficit can be traced to inefficiencies in market organization and solutions should be designed to mitigate those inefficiencies. Tariff deficits have allowed for the transfer of part of the present costs of electricity services to future consumers, but this situation has reached a limit and a deep revision of regulation in this market cannot be postponed. In general, solutions that interfere with market prices and signals are not appropriate.

Soluções cosmológicas e locais para uma eletrodinâmica modificada

The present work investigates some consequences that arise from the use of a modifed lagrangean for the eletromagnetic feld in two diferent contexts: a spatially homogeneous and isotropic universe whose dynamics is driven by a magnetic feld plus a cosmological parameter A, and the problem of a static and charged point mass (charged black hole). In the cosmological case, three diferent general solutions were derived. The first, with a null cosmological parameter A, generalizes a particular solution obtained by Novello et al [gr-qc/9806076]. The second one admits a constant A and the third one allows A to be a time-dependent parameter that sustains a constant magnetic feld. The first two solutions are non-singular and exhibit in ationary periods. The third case studied shows an in ationary dynamics except for a short period of time. As for the problem of a charged point mass, the solutions of the Einstein-Maxwell equations are obtained and compared with the standard Reissner-Nordstrom solution. Contrary to what happens in the cosmological case, the physical singularity is not removed

Variáveis canônicas não singulares e o movimento rotacional de satélites artificiais

Pós-graduação em Física - FEG

Fluxo do grupo de renormalização dos modelos-'alfa' e as álgebras de Lie contínuas

Pós-graduação em Física - IFT

An inverse method to estimate the moving heat source in machining process

The present work propounds an inverse method to estimate the heat sources in the transient two-dimensional heat conduction problem in a rectangular domain with convective bounders. The non homogeneous partial differential equation (PDE) is solved using the Integral Transform Method. The test function for the heat generation term is obtained by the chip geometry and thermomechanical cutting. Then the heat generation term is estimated by the conjugated gradient method (CGM) with adjoint problem for parameter estimation. The experimental trials were organized to perform six different conditions to provide heat sources of different intensities. This method was compared with others in the literature and advantages are discussed. (C) 2012 Elsevier Ltd. All rights reserved.

Some techniques for automated, resource-aware distributed and mobile computing in a multi-paradigm programming system

Distributed parallel execution systems speed up applications by splitting tasks into processes whose execution is assigned to different receiving nodes in a high-bandwidth network. On the distributing side, a fundamental problem is grouping and scheduling such tasks such that each one involves sufñcient computational cost when compared to the task creation and communication costs and other such practical overheads. On the receiving side, an important issue is to have some assurance of the correctness and characteristics of the code received and also of the kind of load the particular task is going to pose, which can be specified by means of certificates. In this paper we present in a tutorial way a number of general solutions to these problems, and illustrate them through their implementation in the Ciao multi-paradigm language and program development environment. This system includes facilities for parallel and distributed execution, an assertion language for specifying complex programs properties (including safety and resource-related properties), and compile-time and run-time tools for performing automated parallelization and resource control, as well as certification of programs with resource consumption assurances and efñcient checking of such certificates.

California pragmatista 1900-1960: proyecto doméstico como expresión y laboratorio del modo de vida

Esta tesis doctoral pretende desgranar una técnica de proyecto que la experiencia californiana ejemplifica y que puede ser descrita en términos pragmatistas. La arquitectura doméstica californiana fue la expresión tangible de una forma de ser y estar californiana pero también universal. El destinatario de esta arquitectura experimental y pragmática fue el individuo, tanto el gran mecenas como el liberal individualista de recursos moderados y aspiraciones infinitas; la gente corriente y, más tarde, la típica familia de clase media, fueron sin embargo el destinatario soñado en muchos ensayos de casa particular, frecuentemente en la casa del propio arquitecto. Arquitectos y clientes compartían el deseo común de un espacio doméstico involucrado en propiciar una vida sana, informal y hedonista, y en comunión con el aire, la naturaleza y el territorio, que satisficiera el espíritu independiente y emprendedor propio de una identidad libre y progresista. Participaron en ese sentido de la esperanza pragmatista de un futuro mejor, mediante la formulación de un modo de vida propio, moldeado por las distintas fuerzas motoras que definían el contexto. La principal de ellas fue la sensación de oportunidad: California se ofrecía como una tabula rasa con un clima paradisíaco; el paraíso soñado para generaciones sucesivas de recién llegados, que en la distancia con tradiciones preestablecidas en sus lugares de origen, encontraron el mayor estímulo para una actitud experimental que tomó el modo de vida como un material de proyecto para la formulación del espacio doméstico. Así, el proyecto doméstico californiano, fue un laboratorio cuyo trabajo mezclaba casos específicos con mitos e ilusiones, muchas veces cuestionadas; pero su interés reside en que puede ser, además de un referente estético y un icono visual, un ejemplo de una forma de proyectar que aborda el proyecto doméstico con talante indagador desde la receptividad al contexto físico, social y cultural; con capacidad para soñar y experimentar llevando los ideales a la práctica de los casos concretos; desde la atención al usuario, aunque sea anónimo; y usando un léxico llano, que devuelve toda la eficacia al vocabulario cotidiano. La experiencia californiana es por tanto, en este trabajo, sólo un ejemplo; un ejemplo paradigmático de una técnica de proyecto que puede ser de interés en otras circunstancias y contextos, y que concibe el espacio doméstico como la expresión, y también el laboratorio, del modo de vida. ABSTRACT This doctoral thesis aims to display a design’s technic that is exemplified by the Californian experience and can be described in pragmatic terms. The Californian domestic architecture was the tangible expression of a life style and way of being that was Californian but also universal. Home’s designed for the everyday experience attended the individual, both the rich sponsors of their own domestic design and the low income liberal individualists in search of an affordable but optimum home. But the dreamed target was ordinary people and the typical middle class family, as they represented the dream of a truly democratic society. Many domestic experiments for them took the form of particular cases, often in the house of the architect, which acted as a laboratory in search of general solutions. Architects and clients shared the common desire of a new domestic space, involved in promoting a healthy, casual and hedonistic lifestyle and in communion with the air, nature and territory, which satisfied the own independent and entrepreneurial spirit of a free and progressive identity. The way of life was therefore a design material, sensitive to the forces that shaped the region and its society through its domestic space. The main one was the feeling of opportunity: California offered itself as a tabula rasa with an exotic climate; the dreamed paradise for successive generations of newcomers who, in the distance with the pre-established traditions of their homelands, found the greatest incentive for an experimental attitude in which lifestyle was seen as project material to formulate the domestic space. Thus, the Californian domestic project can be more than an aesthetic reference and a visual icon; it is also an example of a design’s technic that approaches the domestic project with an inquisitive spirit sustained by these abilities: receptivity to the physical, social and cultural context; capacity to dream and to experiment, carrying ideals into practice; attention to the user, even when it’s anonymous; and use of a common lexicon that returns all the power to the everyday vocabulary. The Californian experience is therefore, in this dissertation, just an example; a paradigmatic example of a project technique that conceives domestic space as an expression, and also as a laboratory, of the way of life.

Getting marketing back in the boardroom:understanding the drivers of marketing's influence within the firm

As many strategically important aspects of marketing are addressed by other functions in the organization, the decreased influence of the marketing department within companies is a topic of growing debate. In this study, the authors investigate this diminished influence and assess its determinants and consequences. They interviewed 25 marketing and finance executives from leading Dutch firms. They also conducted a large-scale Internet-based survey of several hundred marketing, finance, and general managers. Their results show that accountability and the innovativeness of the marketing department are the major drivers of the marketing department’s influence. They also demonstrate that a firm’s short-term orientation is negatively related to the influence of the marketing department. Marketing influence is positively related to market orientation, which is positively related to firm performance. Their results do not support prior findings of a direct positive link between marketing influence and firm performance, which might suggest that there is no need for a strong marketing department. The study suggests that an influential marketing department is relevant primarily when the firm is not market oriented. When firms are market oriented, a less influential marketing department does not lower their performance. Hence, it appears that they can choose to have an influential or noninfluential marketing department without any repercussions for their performance. Marketing activities could move to other functions. The authors suggest that marketing departments should aim to retain their influence. Dispersing marketing decision making among many functions can cause a lack of coordination; customers also lose their advocate within the firm. How can marketing departments regain their influence? The authors suggest two general solutions. First, marketing departments should become more accountable by linking marketing actions and policies with financial results. Marketers should become capable in analytics and finance. Second, they should become more innovative by increasing their share in new product or service concepts. They can do so by using their knowledge of the market and customers to contribute to new product or service development.

Exact series solutions of reactive transport models with general initial conditions

Exact solutions of partial differential equation models describing the transport and decay of single and coupled multispecies problems can provide insight into the fate and transport of solutes in saturated aquifers. Most previous analytical solutions are based on integral transform techniques, meaning that the initial condition is restricted in the sense that the choice of initial condition has an important impact on whether or not the inverse transform can be calculated exactly. In this work we describe and implement a technique that produces exact solutions for single and multispecies reactive transport problems with more general, smooth initial conditions. We achieve this by using a different method to invert a Laplace transform which produces a power series solution. To demonstrate the utility of this technique, we apply it to two example problems with initial conditions that cannot be solved exactly using traditional transform techniques.

Exact solutions and transformation properties of nonlinear partial differential equations from general relativity

Various families of exact solutions to the Einstein and Einstein-Maxwell field equations of General Relativity are treated for situations of sufficient symmetry that only two independent variables arise. The mathematical problem then reduces to consideration of sets of two coupled nonlinear differential equations.

The physical situations in which such equations arise include: a) the external gravitational field of an axisymmetric, uncharged steadily rotating body, b) cylindrical gravitational waves with two degrees of freedom, c) colliding plane gravitational waves, d) the external gravitational and electromagnetic fields of a static, charged axisymmetric body, and e) colliding plane electromagnetic and gravitational waves. Through the introduction of suitable potentials and coordinate transformations, a formalism is presented which treats all these problems simultaneously. These transformations and potentials may be used to generate new solutions to the Einstein-Maxwell equations from solutions to the vacuum Einstein equations, and vice-versa.

The calculus of differential forms is used as a tool for generation of similarity solutions and generalized similarity solutions. It is further used to find the invariance group of the equations; this in turn leads to various finite transformations that give new, physically distinct solutions from old. Some of the above results are then generalized to the case of three independent variables.