A Natural nEighbours Method (NEM) based on the FRAEIJS de VEUBEKE (FdV) variational principle is developed in the domain of 2D infinitesimal transformations. This method is firstly applied to linear elastic problems and then is extended to materially nonlinear problems and problems of linear elastic fracture mechanics (LEFM). In all these developments, thanks to the FdV variational principle, the displacement field, the stress field, the strain field and the support reaction field are discretized independently. In the spirit of the NEM, nodes are distributed in the domain and on its contour and the corresponding Voronoi cells are constructed. In linear elastic problems the following discretization hypotheses are used: 1. The assumed displacements are interpolated between the nodes with Laplace functions. 2. The assumed support reactions are constant over each edge of Voronoi cells on which displacements are imposed. 3. The assumed stresses are constant over each Voronoi cell. 4. The assumed strains are constant over each Voronoi cell. The degrees of freedom linked with the assumed stresses and strains can be eliminated at the level of the Voronoi cells so that the final equation system only involves the nodal displacements and the assumed support reactions. The support reactions can be further eliminated from the equation system if the imposed support conditions only involve constant imposed displacements (in particular displacements imposed to zero) on a part of the solid contour, finally leading to a system of equations of the same size as in a classical displacement-based method. For the extension to materially non linear problems, similar hypotheses are used. In particular, the velocities are interpolated by Laplace functions and the strain rates are assumed to be constant in each Voronoi cell. The final equations system only involves the nodal velocities. It can be solved step by step by time integration and Newton-Raphson iterations at the level of the different time steps. In the extension of this method for LEFM, a node is located on each crack tip. In the Voronoi cells containing the crack tip, the stress and the strain discretization includes not only a constant term but also additional terms corresponding to the solutions of LEFM for modes 1 and 2. In this approach, the stress intensity coefficients are obtained as primary variables of the solution. The final equations system only involves the nodal displacements and the stress intensity coefficients. Finally, an eXtended Natural nEighbours Method (XNEM) is proposed in which the crack is represented by a line that does not conform to the nodes or the edges of the cells. Based on the hypotheses used in linear elastic domain, the discretization of the displacement field is enriched with Heaviside functions allowing a displacement discontinuity at the level of the crack. In the cells containing a crack tip, the stress and strain fields are also enriched with additional terms corresponding to the solutions of LEFM for modes 1 and 2. The stress intensity coefficients are also obtained as primary variables of the solution. A set of applications are performed to evaluate these developments. The following conclusions can be drawn for all cases (linear elastic, nonlinear, fracture mechanics). In the absence of body forces, the numerical calculation of integrals over the area of the domain is avoided: only integrations on the edges of the Voronoi cells are required, for which classical Gauss numerical integration with 2 integration points is sufficient to pass the patch test. The derivatives of the nodal shape functions are not required in the resulting formulation. The patch test can be successfully passed. Problems involving nearly incompressible materials can be solved without incompressibility locking in all cases. The numerical applications show that the solutions provided by the present approach converge to the exact solutions and compare favourably with the classical finite element method. / Une méthode des éléments naturels (NEM) basée sur le principe variationnel de FRAEIJS de VEUBEKE (FdV) est développée dans le domaine des transformations infinitésimales 2D. Cette méthode est dabord appliquée aux problèmes élastiques linéaires puis est étendue aux problèmes matériellement non linéaires ainsi quà ceux de la mécanique de la rupture élastique linéaire (LEFM). Dans tous ces développements, grâce au principe variationnel de FdV, les champs de déplacements, contraintes, réformations et réactions dappui sont discrétisés de façon indépendante. Dans lesprit de la NEM, des noeuds sont distribués dans le domaine et sur son contour et les cellules de Voronoi associées sont construites. En domaine élastique linéaire, les hypothèses de discrétisation sont les suivantes : 1. Les déplacements sont interpolés entre les noeuds par des fonctions de Laplace. 2. Les réactions dappui sont supposées constantes sur chaque côté des polygones de Voronoi le long desquels des déplacements sont imposés. 3. Les contraintes sont supposées constantes sur chaque cellule de Voronoi. 4. Les déformations sont supposées constantes sur chaque cellule de Voronoi. Les degrés de liberté associés aux hypothèses sur les contraintes et les déformations peuvent être éliminées au niveau des cellules de Voronoi de sorte que le système déquations final nimplique que les déplacement nodaux et les réactions dappui supposées. Ces dernières peuvent également être éliminées de ce système déquations si les conditions dappui nimposent que des déplacements constants (en particulier égaux à zéro) sur une partie du contour du domaine étudié, ce qui conduit à un système déquations de même taille que dans une approche basée sur la discrétisation des seuls déplacements. Pour lextension aux problèmes matériellement non linéaires, des hypothèses similaires sont utilisées. En particulier, les vitesses sont interpolées par des fonctions de Laplace et déformations sont supposées constantes sur chaque cellule de Voronoi. Le système déquations final nimplique que les vitesses nodales. Il peut être résolu pas à pas par intégration temporelle et itérations de Newton-Raphson à chaque pas de temps. Pour lextension de cette méthode aux problèmes de LEFM, un noeud est localisé à chaque pointe de fissure. Dans les cellules de Voronoi correspondantes, la discrétisation des contraintes et des déformations contient non seulement un terme constant mais aussi des termes additionnels correspondant aux solutions de la LEFM pour les modes 1 et 2. Avec cette approche, les coefficients dintensité de contraintes constituent des variables primaires de la solution. Le système déquations final ne contient que les déplacements nodaux et les coefficients dintensité de contraintes. Finalement, une méthode des éléments naturels étendue (XNEM) est proposée dans laquelle la fissure est représentée par une ligne indépendante des noeuds ou des côtés des cellules de Voronoi. La discrétisation utilisée en domaine élastique linéaire est enrichie par des fonctions de Heaviside qui autorisent une discontinuité des déplacements au niveau de la fissure. Dans les cellules contenant une pointe de fissure, les contraintes et les déformations sont aussi enrichies par des termes additionnels correspondant aux solutions de la LEFM pour les modes 1 et 2. Ici aussi, les coefficients dintensité de contraintes constituent des variables primaires de la solution. Une série dapplications numériques sont réalisées afin dévaluer ces développements. Les conclusions suivantes peuvent être tirées. Elles sappliquent à tous les cas (élastique linéaire, non linéaire, mécanique de la rupture) : En labsence de force volumique, le calcul numérique dintégrales sur laire du domaine est évité : seules sont nécessaires des intégrales numériques sur les côtés des cellules de Voronoi. Lutilisation de 2 points de Gauss suffit pour passer le patch test. Les dérivées des fonctions dinterpolation nodales ne sont pas nécessaires dans cette formulation. La formulation passe le patch test. Les problèmes impliquant des matériaux quasi incompressibles sont résolus sans verrouillage. Les applications numériques montrent que les solutions fournies par lapproche développée convergent vers les solutions exactes et se comparent favorablement avec celles de la méthode des éléments finis.

This study set-out to examine how university-industry linkage (UIL) is managed in government universities of Ethiopia to contribute to the economic development of the country. Basic questions related to the level of management of UIL, areas of linkage, benefits obtained so far from this partnership, challenges to the proper management of UIL, and the existing opportunities for promoting UIL were raised. In addition to this, strategies for strengthening UIL were also dealt with. In relation to this, the study was framed with the system theory viewpoints and human capital theory viewing universities as a system linked to its external environment like industries. As a model, interactive/balanced type of Triple Helix model was used as it integrates the activities of the government, universities and the industries. Moreover, this study reviewed global perspectives on UIL and an overview of the study context with greater emphasis on higher education reforms and proclamations. Philosophically, this study followed pragmatism research paradigm using mixed research approach. It also employed concurrent/parallel/convergent design in which both quantitative and qualitative data were collected simultaneously, interpreted separately and combined at the time of discussion for better understanding of the problem. Equal importance for both data sets was given. Data were gathered from 99 college deans and department heads, 200 instructors and 316 prospective graduates. In addition to this, 23 interviewees from UILOs, industries, MoE, and MoST took part in this study. Moreover, two focus group discussions were also conducted with the university alumni and data were gathered through survey questionnaires, semi-structured interview, FGD question guides and document reviews. The study result indicated that both quantitative and qualitative data support one another. It was found out that UIL was at its infant stage of development in government universities of Ethiopia with limited areas, dominated by students’ internship. Ethiopian government universities have a link with the industries in areas of some limited joint research projects, consultancies and capacity building. Consequently, universities benefitted by attaching their students with the industries and students got practical exposure to the real world of work. Industries also benefitted from the training provided to them, consultancies and joint research projects. On the other hand, UIL in government universities of Ethiopia was challenged by institutional bottlenecks, policy-practice gaps, contextual variation and information gaps, finance and awareness related caveats, work overload, and facility related hurdles. Moreover, lack of trust and commitment between U & I, lack of commitment and support from the leadership of both universities and industries, and the reluctance of the local industries to work with the universities remained a big rift to UIL. This study also sheds light on the expansion of universities and industries in different parts of the country as the opportunities to be tapped to promote UIL. Further, the attention of the government by designing different policies, strategies, directives and conferences was taken as the opportunity. As a major contribution, this study came up with the model that was designed to improve the practice of management of UIL in government universities of Ethiopia. To overcome the above challenges and to make use of existing opportunities, it was recommended that improving leadership and management related challenges through joint planning, organising, staffing and decision-making. Moreover, it was highly laudable to make a paradigm shift in the roles of universities from teaching dominated to research and innovation universities. Finally, bridging policy-practice gaps, increase networking, arranging various sensitising and advertising programmes and creating a further avenue for more research were commented. / Educational Leadership and Management / D. Ed. (Education Management)