Aplicação de modelos de equações estruturais no estudo da eficácia de Sistemas de Gestão de Desempenho

Para fazer face às exigências da sociedade, as organizações têm a necessidade de desenvolver esforços de modo a aumentar a sua performance, através de práticas de gestão estratégica de recursos humanos. Nesta dissertação iremos aprofundar o estudo do modelo proposto por Marr (2009) para explicar a Cultura Orientada para o Desempenho e demonstrar os efeitos que a cultura tem nos Sistemas de Gestão de Desempenho, utilizando os Modelos de Equações Estruturais, através da análise de respostas obtidas sobre 325 colaboradores de empresas portuguesas do sector público e privado. Desta análise resultou a confirmação das quatro dimensões latentes de Cultura Organizacional propostas pelo autor, através da Análise Factorial Confirmatória, revelando também a sua importância e contributos diferenciados no Sistema de Gestão de Desempenho de uma organização. De um modo geral, verificou-se que as dimensões da Cultura contribuem de forma positiva para o aumento da eficácia de um Sistema de Gestão de Desempenho, alinhado com o modelo conceptual proposto e enfatizando a importância de se estudar as dimensões de Cultura e de Sistemas de Gestão de Desempenho de forma simultânea.

Modelagem do desempenho ambiental dos projetos de exploração e produção aplicando equações estruturais

A legislação ambiental e os principais agentes que se relacionam com a empresa se constituem em fatores exógenos que não podem ser negligenciados ao formular-se e avaliar-se a política ambiental corporativa. As influências exógenas e seus efeitos sobre a gestão ambiental e o gerenciamento de projetos de exploração e produção (E&P) e, por essa via, sobre o desempenho ambiental, foram objetos de estudo desta tese. Embora o desempenho ambiental seja um assunto relevante, a pesquisa sobre esse tema ainda é escassa. Tal carência desponta ainda mais acentuada quando se aborda o desempenho ambiental de projetos na indústria de petróleo e gás. O principal objetivo deste estudo foi avaliar a relação entre a legislação ambiental vigente, as ações de órgãos reguladores, fornecedores, empresas terceirizadas e comunidades locais e o desempenho ambiental dos projetos de E&P na indústria de petróleo e gás e, também, analisar os efeitos do sistema de gestão ambiental e o gerenciamento dos projetos sobre tal desempenho. Na fase abdutiva, foi conduzido um estudo de caso com abordagem qualitativa em uma grande empresa brasileira do setor de petróleo e gás, na fase dedutiva, foi realizada uma pesquisa survey explanatória de corte transversal com abordagem quantitativa, incluindo 113 projetos de E&P de cinco unidades executoras da empresa. Foi formulado um modelo conceitual, com cinco construtos e sete hipóteses de pesquisa, representativo dos efeitos de fatores externos sobre o desempenho ambiental dos projetos de E&P. Os dados foram tratados aplicando a Análise Fatorial Exploratória e a Modelagem de Equações Estruturais com aplicação dos softwares IBM® SPSS® Statistics 20.0 e IBM® SPSS® Amos 18.0. O modelo de equações estruturais foi reespecificado e estimado utilizando o método de Máxima Verossimilhança e o procedimento bootstrap com 2000 reamostragens, até alcançar adequados valores dos índices de ajustamento. O modelo mostrou boa aderência às evidências empíricas, representando uma teoria explicativa dos fatores que influenciam o desempenho ambiental dos projetos de E&P na empresa estudada. As estatísticas descritivas apontaram adequado desempenho dos projetos de E&P com relação aos efluentes descartados, volume de água reutilizada, redução de resíduos e práticas de reciclagem. Identificou-se que projetos de maior porte alcançam melhor desempenho ambiental em relação aos de menor tamanho. Não foram achadas diferenças significativas entre os desempenhos de projetos executados por unidades operacionais distintas. Os resultados da modelagem indicaram que nem a legislação ambiental, nem os agentes externos exercem influência significativa sobre a sistemática da gestão dos projetos de E&P. Os agentes externos atuam sobre a gestão ambiental da empresa exercitando capacidades colaborativas, obstrutivas e propositivas. A legislação ambiental é percebida como entrave ao desenvolvimento dos projetos ao longo de seu ciclo de vida, principalmente, pelas deficiências dos órgãos ambientais. Identificou-se que o sistema de gestão ambiental influencia diretamente o Programa de Desenvolvimento e Execução de Projetos de E&P, que, por sua vez, provoca efeitos diretos e indiretos sobre o desempenho ambiental. Finalmente, comprovou-se que o Sistema de Gestão Ambiental da empresa é determinante para o desempenho ambiental dos projetos de E&P, tanto pelos seus efeitos diretos, como pelos indiretos, estes últimos mediados pela sistemática de gestão dos projetos de E&P

Equações de predição para estimar o valor de energia metabolizável do milho para frangos de corte.

2016

Equações de predição para estimar o valor de energia metabolizável do milho para suínos.

2016

The harmonic torsional oscillations of a thin disk submerged in a fluid with a surfactant surface layer

A formulation in terms of a Fredholm integral equation of the first kind is given for the axisymmetric problem of a disk oscillating harmonically in a viscous fluid whose surface is contaminated with a surfactant film. The equation of the first kind is converted to a pair of coupled integral equations of the second kind, which are solved numerically. The resistive torque on the disk is evaluated and surface velocity profiles are computed for varying values of the ratio of the coefficient of surface shear viscosity to the coefficient of viscosity of the substrate fluid, and the depth of the disk below the surface.

Axisymmetric deformation of a short magneto-strictive current-carrying cylinder

The title-problem has been reduced to that of solving a Fredholm integral equation of the second kind. One end of the cylinder is assumed to be fixed, while the cylinder is deformed by an axial current. The vertical displacement on the upper flat end of the cylinder has been determined from an iterative solution of the Fredholm equation valid for large values of the length. The radial displacement of the curved boundary has also been determined at the middle of the cylinder, by using the iterative solution.

On the design of quadratic weirs

This paper considers the problem of the design of the quadratic weir notch, which finds application in the proportionate method of flow measurement in a by-pass, such that the discharge through it is proportional to the square root of the head measured above a certain datum. The weir notch consists of a bottom in the form of a rectangular weir of width 2W and depth a over which a designed curve is fitted. A theorem concerning the flow through compound weirs called the “slope discharge continuity theorem” is discussed and proved. Using this, the problem is reduced to the determination of an exact solution to Volterra's integral equation in Abel's form. It is shown that in the case of a quadratic weir notch, the discharge is proportional to the square root of the head measured above a datum Image a above the crest of the weir. Further, it is observed that the function defining the shape of the weir is rapidly convergent and its value almost approximates to zero at distances of 3a and above from the crest of the weir. This interesting and significant behaviour of the function incidentally provides a very good approximate solution to a particular Fredholm integral equation of the first kind, transforming the notch into a device called a “proportional-orifice”. A new concept of a “notch-orifice” capable of passing a discharge proportional to the square root of the head (above a particular datum) while acting both as a notch, and as an orifice, is given. A typical experiment with one such notch-orifice, having A = 4 in., and W = 6 in., shows a remarkable agreement with the theory and is found to have a constant coefficient of discharge of 0.61 in the ranges of both notch and orifice.

Properties of Toeplitz operators on analytic function spaces : from function symbols to distributions

Toeplitz operators are among the most important classes of concrete operators with applications to several branches of pure and applied mathematics. This doctoral thesis deals with Toeplitz operators on analytic Bergman, Bloch and Fock spaces. Usually, a Toeplitz operator is a composition of multiplication by a function and a suitable projection. The present work deals with generalizing the notion to the case where the function is replaced by a distributional symbol. Fredholm theory for Toeplitz operators with matrix-valued symbols is also considered. The subject of this thesis belongs to the areas of complex analysis, functional analysis and operator theory. This work contains five research articles. The articles one, three and four deal with finding suitable distributional classes in Bergman, Fock and Bloch spaces, respectively. In each case the symbol class to be considered turns out to be a certain weighted Sobolev-type space of distributions. The Bergman space setting is the most straightforward. When dealing with Fock spaces, some difficulties arise due to unboundedness of the complex plane and the properties of the Gaussian measure in the definition. In the Bloch-type spaces an additional logarithmic weight must be introduced. Sufficient conditions for boundedness and compactness are derived. The article two contains a portion showing that under additional assumptions, the condition for Bergman spaces is also necessary. The fifth article deals with Fredholm theory for Toeplitz operators having matrix-valued symbols. The essential spectra and index theorems are obtained with the help of Hardy space factorization and the Berezin transform, for instance. The article two also has a part dealing with matrix-valued symbols in a non-reflexive Bergman space, in which case a condition on the oscillation of the symbol (a logarithmic VMO-condition) must be added.

Faster computation of the Karhunen-Loeve expansion using its domain independence property

The goal of this work is to reduce the cost of computing the coefficients in the Karhunen-Loeve (KL) expansion. The KL expansion serves as a useful and efficient tool for discretizing second-order stochastic processes with known covariance function. Its applications in engineering mechanics include discretizing random field models for elastic moduli, fluid properties, and structural response. The main computational cost of finding the coefficients of this expansion arises from numerically solving an integral eigenvalue problem with the covariance function as the integration kernel. Mathematically this is a homogeneous Fredholm equation of second type. One widely used method for solving this integral eigenvalue problem is to use finite element (FE) bases for discretizing the eigenfunctions, followed by a Galerkin projection. This method is computationally expensive. In the current work it is first shown that the shape of the physical domain in a random field does not affect the realizations of the field estimated using KL expansion, although the individual KL terms are affected. Based on this domain independence property, a numerical integration based scheme accompanied by a modification of the domain, is proposed. In addition to presenting mathematical arguments to establish the domain independence, numerical studies are also conducted to demonstrate and test the proposed method. Numerically it is demonstrated that compared to the Galerkin method the computational speed gain in the proposed method is of three to four orders of magnitude for a two dimensional example, and of one to two orders of magnitude for a three dimensional example, while retaining the same level of accuracy. It is also shown that for separable covariance kernels a further cost reduction of three to four orders of magnitude can be achieved. Both normal and lognormal fields are considered in the numerical studies. (c) 2014 Elsevier B.V. All rights reserved.

An alternative approach to study nonlinear inviscid flow over arbitrary bottom topography

This paper deals with a new approach to study the nonlinear inviscid flow over arbitrary bottom topography. The problem is formulated as a nonlinear boundary value problem which is reduced to a Dirichlet problem using certain transformations. The Dirichlet problem is solved by applying Plemelj-Sokhotski formulae and it is noticed that the solution of the Dirichlet problem depends on the solution of a coupled Fredholm integral equation of the second kind. These integral equations are solved numerically by using a modified method. The free-surface profile which is unknown at the outset is determined. Different kinds of bottom topographies are considered here to study the influence of bottom topography on the free-surface profile. The effects of the Froude number and the arbitrary bottom topography on the free-surface profile are demonstrated in graphical forms for the subcritical flow. Further, the nonlinear results are validated with the results available in the literature and compared with the results obtained by using linear theory. (C) 2015 Elsevier Inc. All rights reserved.

Torsional impact of transversely isotropic solid with functionally graded shear moduli and a penny-shaped crack

The torsional impact response of a penny-shaped crack in an unbounded transversely isotropic solid is considered. The shear moduli are assumed to be functionally graded such that the mathematics is tractable. Laplace transform and Hankel transform are used to reduce the problem to solving a Fredholm integral equation. The crack tip stress fields are obtained. Investigated are the influence of material nonhomogeneity and orthotropy on the dynamic stress intensity factor. The peak value of the dynamic stress intensity factor can be suppressed by increasing the shear moduli's gradient and/or increasing the shear modulus in a direction perpendicular to the crack surface.

A contact crack problem in an infinite plate

The problem of an infinite plate with crack of length 2a loaded by the remote tensile stress P and a pair of concentrated forces Q is discussed. The value of the force Q for the initial contact of crack face is investigated and the contact length elevated, while the Q force increases. The problem is solved assuming that the stress intensity factor vanishes at the end point of the contact portion. By the Fredholm integral equation for the multiple cracks, the reduction of stress intensity factor due to Q is found. (C) 1999 Elsevier Science Ltd. All rights reserved.

不稳定腔的本征值与本征函数

本文证明了不稳定谐振腔的本征值与本征函数的存在性,并证明了不稳定腔的本征值与本征函数组成可数的无穷序列;同时,指出了文献[1]所提出的ε近似本征值与δ近似本征函数的概念并不能真实反映实际不稳定谐振腔的损失与场分布,并指出了有限镜面不稳定谐振腔是具有选模特性的.