A New 3D Potential-Density Basis Set

A set of bi-orthogonal potential-density basis functions is introduced to model the density and its associated gravitational field of three dimensional stellar systems. Radial components of our basis functions are weighted integral forms of spherical Bessel functions. We discuss the properties of our basis functions and demonstrate their shapes for the latitudinal Fourier number $l=2$.Comment: 2 pages. To appear in the proceedings of IAU Symposium 245, "Formation and Evolution of Galaxy Bulges," M. Bureau, E. Athanassoula, and B. Barbuy, ed

Dynamic Analysis of Isotropic and Laminated Reinforced Composite Plates Subjected to Flowing Fluid

"RÉSUMÉ": Dans ce travail nous examinons le comportement dynamique d’une structure en composite, symétriquement élastique, et d’une plaque anisotrope soumise à un flux de fluide non-visqueux et incompressible. Pour une modélisation mathématique, une combinaison entre la méthode des éléments finis ainsi que la théorie des plaques minces a été utilisée. Pour définir la propriété des composites, un élément rectangulaire anisotrope a été utilisé. La plaque est composée de N couches qui peuvent être fabriquées de fibres unidirectionnelles avec différentes matrices. Ces fibres pourraient être continues, discontinues ou dans un mode aléatoire. L’inertie, la force de Coriolis et la force centrifugeuse du fluide introduisent une pression dynamique qui est modélisée en utilisant la fonction du potentiel de Bernoulli. La condition d’imperméabilité entre la plaque et le fluide est aussi prise en compte. Les matrices de masse et de rigidité pour chaque élément de la plaque ont été calculées par une intégration analytique exacte. Une corrélation assez proche entre la théorie présentée avec les approches expérimentales et Ansys (logiciel d’éléments finis) a été démontrée.----------"ABSTRACT": In situations of fluid and structure, the dynamic behavior of the structure may vary. Structures can lose their stability due to fluid/solid interaction. Modal analysis and the dynamic behavior of elastically symmetrical laminated composites as well as isotropic plates subjected to an incompressible, inviscid flowing fluid are studied in this work using shell and thin plate theories. The effect of stacking sequence and boundary conditions on the natural frequency and static instability of the model are studied. Shear deformation effect is not taken into account. For mathematical modeling, a combination of a hybrid finite element method and classic laminate thin plate theory are used. The finite element is defined as a rectangular thin laminated composite plate with four nodes. Each node has six degrees of freedom to cover all possible movements. The plate consists of N layers that could be made of unidirectional fibers in different matrices and these fibers could be continuous, discontinuous or random modes but in this study in all the examples, models consist of continuous fibers. Inertia, Coriolis and centrifugal fluid forces introduce a dynamic pressure field which is modeled using a velocity potential function and Bernoulli’s equation. This pressure field is a function of the nodal displacement. The impermeability condition between the plate and the fluid is also taken into account. Mass and stiffness matrices for each element of the plate are calculated by exact analytical integration using MATLAB programming software. Close agreement between the presented theory and other sources such as commercial finite element software (ANSYS) and experimental approaches is demonstrated

The Moderating Effect Of Social Capital In Relation To Entrepreneurial Orientation And Firm Performance

The importance of entrepreneurial orientation (EO), resource-based view (RBV), network types of social capital (SC) and small and medium enterprises (SMEs) have become the main focus in the manufacturing environment. In view of the highly competitive manufacturing environment, the ability and reliability of small and medium enterprises (SMEs) is very important in order to achieve desired SMEs performance namely growthprofitability. In addition to that, literature argues that further research is required in the area of entrepreneurship and firm performance. In order to address this need, the study investigates 1. The relationship between EO and Manufacturing SMEs performance and 2. The moderating effect of intra- and extra-industry network in EO and manufacturing SMEs performance relationship. Quantitative method was done through survey. Instrumentation of data-gathering in quantitative method was done through questionnaires and its validity was measured by content validity. The population of this study was industrial SMEs in Tehran and Hamedan. Proportionate stratified random sampling was employed and out of 351 questionnaires sent out, only 150 questionnaires were returned, yielding a return rate of 25 percent. A model is hypothesized and analyzed by multiple regressions. The result implies that EO positively improved manufacturing SMEs performance

Social Media Etiquette for the Modern Medical Student:A Narrative Review

Most medical students worldwide are using some form of social media platform to supplement their learning via file sharing and to stay up-to-date on medical events. Often, social media may blur the line between socialization and educational use, so it is important to be aware of how one is utilizing social media and how to remain professional. Research has yielded some troublesome themes of misconduct: drunken behaviour, violations of confidentiality and defamation of institutions. Because there is no universal policy to monitor online professionalism, there exists the potential for indiscretions to occur. It has been reported that misdemeanours can affect future residency placements and employment for medical students. Accordingly, studies suggest that educators need to recognize this new era of professionalism and adapt policies and reprimands to meet modern outlets where professionalism may be violated

Performance of minimum quantity cooling (MQC) when turning aluminium alloy 6061-T6 : surface roughness, tool temperature and aerosol emission

Nowadays industries desire to obtain parts with better accuracy (dimensional and form) and surface finish at low cost. These factors (accuracy, cost and productivity) are used to evaluate the performance of machining processes. When material removal rate increases, the higher tool temperature is anticipated and therefore, better cooling is required. To reduce the heat effects on cutting tools and therefore improve the life, an efficient and cost effective application of the cutting fluid is required. Also, to cope with environmental and occupational safety issues, new cooling and lubricating methods such as minimum quantity lubrication (MQL) and minimum quantity cooling (MQC) have been proposed. The use of near dry or minimum quantity cooling lubrication (MQCL) considerably decreases cutting fluid consumption as compared to conventional flood cooling and it increases the machinability when compared with dry machining. The surface roughness, heat generation in cutting tool, generated dust and aerosol emission can be known as machining quality index which are highly influenced by cutting conditions. The presented research work investigates the effects of lubrication mode (dry, wet and MQC) and cutting conditions (feed rate, cutting speed, air and liquid flow rates) on surface roughness, cutting tool temperature, aerosol and dust emission during turning of aluminum alloy 6061-T6. It is found that there are optimum conditions for which MQC machining leads to better surface finish than flood and dry machining; MQC and wet machining produce more aerosols (liquid and solid) as compared to dry machining; and finally, MQC produces less heat as compared to traditional wet machining. However, the MQC machining is preferable due to its less destructive effects on air quality and environmental hazards