Investigating the effect of entrepreneurial competencies on business performance among early stage entrepreneurs Global Entrepreneurship Monitor (GEM 2010 survey data)

Entrepreneurs of this era need to be more competent and skillful compared to businessmen working in the beginning of this century. A robust body of knowledge has grown around entrepreneurs' need for superior skills and personality characteristics; the ones that enables them to effectively compete and survive. In this study, we analyzed the relationship between entrepreneurial competencies along with social norms and entrepreneurs' business performance. Data of GEM gathered during 2010 was utilized and 125 cases was selected from 59 member countries. Confirmatory factor analysis showed that social image of entrepreneurs is a better measure than national attitude toward entrepreneurship for the construct "entrepreneurial social norms" based on their factor loadings. For the same reason, entrepreneurial skills remained as the measure of entrepreneurial competencies and entrepreneurial personality measure was dropped. And, for the dependent variable "performance", growth and innovation remained as a more powerful measures than export. Finally, the positive effect of entrepreneurial competencies on business performance was supported by the data and results revealed that there is a positive effect between entrepreneurial social norms on entrepreneurs' competencies which conforms the mediating role of entrepreneurial competencies. However, the data did not support the direct effect of entrepreneurial social norms on performance

Simple and Safe Packing Method for High-Grade Liver Injuries

Background: Injury to the liver is a commonly encountered problem in trauma cases and is a frequent cause of morbidity and mortality. Because gauze packing is easy to use and has the potential for rapid hemorrhage control, it is the most commonly used method for patients with severe liver injuries, particularly those with coagulopathy. Objectives: In this study, OpSite sheets were used to make three-layer packs for decreasing the complication associated with removing gauze packing. Patients and Methods: Twenty male patients with grade IV or V liver injuries that required laparotomy were enrolled in the study. Ten patients were treated using conventional packing, while the other 10 were treated using the three-layer pack. In the case group, the liver was mobilized as much as possible. The three-layer pack was then placed at the site of liver damage and extended onto the liver surface, and the other pads were placed on top of this pad. After 72 h, reoperation was performed, the packs were removed, and the packs causing injury were recorded. Additionally, if rebleeding due to the adhesive bands of the pack was observed, the blood was suctioned and bleeding volume was measured. Data were analyzed using the Mann–Whitney test. Results: Patients in the case and control groups were similar in age and admission vital signs. During the second operation, the bleeding volumes measured in the case and control groups were 66 ± 27.01 mL and 152 ± 85.4 mL, respectively. There was some pad-induced damage after the removal of the pad in the control group. Conclusions: Our study has provided a simple and safe packing method for high-grade liver injuries

Higher-order multi-resolution topology optimization using the finite cell method

This article presents a detailed study on the potential and limitations of performing higher-order multi-resolution topology optimization with the finite cell method. To circumvent stiffness overestimation in high-contrast topologies, a length-scale is applied on the solution using filter methods. The relations between stiffness overestimation, the analysis system, and the applied length-scale are examined, while a high-resolution topology is maintained. The computational cost associated with nested topology optimization is reduced significantly compared with the use of first-order finite elements. This reduction is caused by exploiting the decoupling of density and analysis mesh, and by condensing the higher-order modes out of the stiffness matrix

Attitudes politiques de Tunis dans le conflit entre Aragonais et Français en Sicile autour de 1282

International audienceSimulating the deformation of the human anatomy is a central element of Medical Image Computing and Computer Assisted Interventions. Such simulations play a key role in non-rigid registration, augmented reality, and several other applications. Although the Finite Element Method is widely used as a numerical approach in this area, it is often hindered by the need for an optimal meshing of the domain of interest. The derivation of meshes from imaging modalities such as CT or MRI can be cumbersome and time-consuming. In this paper we use the Immersed Boundary Method (IBM) to bridge the gap between these imaging modalities and the fast simulation of soft tissue deformation on complex shapes represented by a surface mesh directly retrieved from binary images. A high resolution surface, that can be obtained from binary images using a marching cubes approach, is embedded into a hexahedral simulation grid. The details of the surface mesh are properly taken into account in the hexahedral mesh by adapting the Mirtich integration method. In addition to not requiring a dedicated meshing approach, our method results in higher accuracy for less degrees of freedom when compared to other element types. Examples on brain deformation demonstrate the potential of our method

Barriers to the C-Suite: The Impact of Perceptions of Gender Bias on Women Leaders’ Senior Leadership Ambitions

The current research examined whether women leaders' senior leadership ambitions are more strongly negatively affected by perceptions of gender bias (i.e., subtle gender bias, inequity, and mistreatment) in the workplace than leaders who are men and whether this association occurs through cynicism towards work. To test this, 347 leaders completed an online survey. It was found that women leaders had similar senior leadership ambitions as men, and contrary to expectations, gender did not affect the relation between gender bias and senior leadership ambitions. However, for both women and men, perceptions of gender bias were related to cynicism towards work, and ultimately, lower senior leadership ambitions. Further, women leaders who worked in male-dominated workplaces reported more issues of subtle gender bias than others. These findings have meaningful implications and suggest that it is likely systemic barriers, and not women's ambitions, that explain the lack of women in the C-suite

Modeling of microstructure evolution in aluminum alloys during hot extrusion

Die Modellierung und Simulation der Mikrostrukturentwicklung von Aluminiumlegierungen in Warmumformverfahren liefern einen Einblick in die Materialeigenschaften des Endproduktes und ermöglichen die Optimierung und Anpassung des Materialverhaltens dieses Endproduktes durch die Steuerung der Mikrostrukturentwicklungen während und nach dem Umformprozess. Für die präzise und stabile Simulation der Mikrostruktur und des Materialverhaltens während Warmumformungsprozessen müssen zahlreiche numerische und strukturelle Aspekte berücksichtigt, sowie ein passendes Materialmodell gewählt werden. Die vorliegende Arbeit beschäftigt sich einerseits mit den numerischen Aspekten der Simulation von Warmumformungsprozessen, andererseits mit der Material- und Mikrostrukturmodellierung solcher Prozesse. Das erste Kapitel gibt einen Überblick über diese Arbeit und ihr verwandte Forschungsgebiete. Hier werden die verschiedenen Aspekte der Modellierung und Simulation des Strangpressprozesses diskutiert. Im Übrigen umfasst dieses Kapitel eine Zusammenstellung der aktuellen Modelle zur Mikrostrukturentwicklung beim Warmumformungsprozess, ebenso wie die neuesten Bemühungen zur Modellierung dieser. Im zweiten Kapitel dieser Doktorarbeit liegt das Augenmerk auf den Aluminiumlegierungen der Serien 6000 (Al-Mg-Si) und 7000 (Al-Zn-Mg). Es wird eine Reihe von Aspekten der Struktursimulation sowie des Strangpressens als thermomechanischen Prozess berücksichtigt. Diese Gesichtspunkte beinhalten den Kontakt, die adaptive Netzverfeinerung, die Wärmeübertragung im Inneren des Walzblocks, den Wärmeaustausch zwischen dem Werkstück und dem Behälter, den Reibungsverlust, die mechanische Energie und die Oberflächenstrahlung. Im dritten Kapitel werden allgemeine Rahmenbedingungen für die Modellierung des Materialverhaltens von Metallen in Umformprozessen dargestellt. Ferner wird, um Simulationsprobleme von Umformprozessen zu überwinden, ein neues Modell zur Neuvernetzung präsentiert. Hier wird die im zweiten Kapitel dargestellte Netzverfeinerung durch die neue Vernetzung der deformierten Geometrie ersetzt. Die Anwendung der Grundstruktur und der entwickelten Simulationstechniken auf zwei Umformprozesse wird präsentiert. Um die numerischen Kosten zu reduzieren und die Ergebnisgenauigkeit zu verbessern, wird die Qualität des Netzes während der Simulation kontrolliert und die Simulation angehalten, falls die Netzqualität einen erlaubten Wert unterschreitet. Die Simulationsergebnisse für die Mikrostrukturentwicklung als Funktion der Prozessbedingungen demonstrieren die Empfindlichkeit der Mikrostrukturentwicklung gegenüber diesen Bedingungen. Ein Vergleich der Simulationsergebnisse für die Mikrostrukturentwicklung mit den jeweiligen experimentellen Werten zeigt gute qualitative Übereinstimmungen. Im vierten Kapitel liegt der Fokus auf dem Vergleich der Ergebnisse aus Experiment und Simulation. Weiterhin wird ein Modell zur Vorhersage und Simulation der Mikrostrukturentwicklung, insbesondere der Kornentwicklung der Aluminiumlegierung EN AW-6082 während Warmumformprozessen kurz beschrieben. Dieses Modell ist ein physikalisch motiviertes phänomenologisches Modell, welches auf vom inneren Zustand abhängigen Variablen basiert. Die Mikrostrukturentwicklung ist ein temperaturabhängiger Prozess und wird mit Hilfe der Finite Elemente Software Abaqus in einem vollständig gekoppelten thermomechanischen Verfahren simuliert. Die Ergebnisse werden mit experimentellen Werten, bestimmt mit Hilfe einer EBSD Messung eines kleinmaßstäbigen Strangpressungsprozesses, der sich für wissenschaftliche Zwecke etabliert hat, abgeglichen und verifiziert. Die Simulationsergebnisse weisen eine zufriedenstellende Übereinstimmung mit den Experimentalergebnissen auf. Im letzten Kapitel werden für das thermoelastische, viskoplastische Verhalten von Aluminiumlegierungen zwei Modelle formuliert und auf den Fall der Strangpressung angewendet. Das erste Modell basiert auf einer gängigen semiempirischen Form der (skalaren) Fließregel der Strangpressgemeinde und vernachlässigt alle Effekte der Mikrostruktur auf das Aushärtungsverhalten. Dies resultiert in einem idealen viskoplastischen Modell. Im zweiten Modell wird eine skalare Fließregel basierend auf der Taylorannahme formuliert, außerdem werden der Einfluss der Subkornstrukturentwicklung auf die freie inelastische Energie sowie die Fließspannung berücksichtigt. Die Vorhersagen dieser beiden Modelle für einfache Benchmarkprobleme aus der Materialprüfung und der Strangpressung werden verglichen.Modeling and simulation of microstructure evolution of aluminum alloys in hot forming processes give an insight into the material properties of the final product and enable us to optimize or customize the material behavior of the final product by controlling the microstructure evolutions during and after forming process. An accurate and robust simulation of microstructure and material behavior during hot large deformation processes requires consideration of several numerical and structural aspects as well as an appropriate material model. The current work deals with the numerical aspects of the simulation of hot forming processes on the one hand, and with the material and microstructure modeling of such processes on the other. The first chapter gives an overview of this work and related researches. Here the different aspects of modeling and simulation of the extrusion processes are discussed. Furthermore a summary of the recent models and efforts for modeling the microstructure evolution in hot forming processes is given in this chapter. In the second chapter of this thesis attention is focused on aluminum alloys of the 6000 series (Al-Mg-Si) and 7000 series (Al-Zn-Mg). Here, a number of aspects of the structural simulation as well as that of extrusion as a thermomechanical process are considered. These aspects include contact and adaptive mesh refinement, heat transfer inside the billet, heat transfer between the workpiece and the container, frictional dissipation, mechanical energy and surface radiation. The third chapter presents a general framework for modeling the material behavior of metals in forming processes. Moreover, to overcome the problems of simulation of large forming processes a new remeshing scheme is presented. Here the mesh refinement applied in the second chapter is replaced by the new remeshing of the deformed geometry. The application of the framework and developed simulation techniques in two forming processes is set out. In the new meshing scheme, in order to reduce the numeric costs and increase the accuracy of the results, the mesh quality is controlled during the simulation and the simulation is stopped when the quality of mesh is less than the allowed value. Simulation results for the microstructure development as a function of process conditions demonstrate the sensitivity of microstructure development to these conditions. Comparison of the simulation results for the microstructure evolution with corresponding experimental results show good qualitative agreement. Chapter four focuses on the comparison of experimental and simulation results as well as a brief description of the applied model for prediction and simulation of the evolution of microstructure, in particular the evolution of grains, during hot forming processes of aluminum alloy EN AW–6082. The model is a physically motivated phenomenological model based on internal state dependent variables. The microstructure evolution is a temperature dependent process and is simulated in a fully-coupled thermomechanical process by help of the Finite Element software Abaqus. The results are compared and verified with experimental results obtained by the EBSD measurement of a small-scale extrusion process established for scientific purposes. The simulation results are in reasonable agreement with the experimental ones. In the final chapter two models are formulated for the thermoelastic, viscoplastic behavior of aluminum alloys and applied to the case of extrusion. The first model is based on a common semi-empirical form of the (scalar) flow rule in the extrusion community and neglects all effects of the microstructure on the hardening behavior. This results in an ideal viscoplasticmodel. The second model formulates a scalar flow rule as based on the Taylor assumption. Furthermore the effect of the subgrain structure development on the inelastic free energy and the flow stress are considered. The predictions of both of these models for simple benchmark problems involving material testing and extrusion are compared

Exact 3D boundary representation in finite element analysis based on Cartesian grids independent of the geometry

This paper proposes a novel Immersed Boundary Method where the embedded domain is exactly described by using its Computer-Aided Design (CAD) boundary representation with Non-Uniform Rational B-Splines (NURBS) or T-splines. The common feature with other immersed methods is that the current approach substantially reduces the burden of mesh generation. In contrast, the exact boundary representation of the embedded domain allows to overcome the major drawback of existing immersed methods that is the inaccurate representation of the physical domain. A novel approach to perform the numerical integration in the region of the cut elements that is internal to the physical domain is presented and its accuracy and performance evaluated using numerical tests. The applicability, performance, and optimal convergence of the proposed methodology is assessed by using numerical examples in three dimensions. It is also shown that the accuracy of the proposed methodology is independent on the CAD technology used to describe the geometry of the embedded domain