Scientific Study in Human Science

تهدف هذه الدراسة إلى إبراز أهمية العلم وهو تلك المعرفة المؤكدة بالتجريب، إذ بفضله نصل إلى الدقة والموضوعية كالتي نلمسها في الفيزياء والبيولوجيا مثلا، دليل ذلك تلك القوانين الكثيرة التي توصل إليها العلماء، هذا النجاح أغرى بقية الباحثين بمحاولة تطبيق المنهج التجريبي في مجالات أخرى غير المادة، ومن ضمن هذه المجالات الظواهر الإنسانية سواء أكانت نفسية، تاريخية، اجتماعية. وتوصلت الدراسة إلى أن أنه من المفيد أن ننظر إلى العلوم الإنسانية والاجتماعية، أن لها أهمية بالغة ومكانة هامة بين العلوم الأخرى لاسيما العلوم الطبيعية، ويمكن أن تؤدي دورها الفعال في بناء المعرفة الإنسانية، وبهذا فهي قادرة وجديرة بأن تنهض بدورها بصفتها علم من العلوم.This study shows the importance of science, which is that knowledge confirmed by experimentation, it is thanks to it that we reach the precision and the objectivity as we see in physics and biology as an example, The evidence is the laws that scientists reached, This success motivates other searchers to try to apply the experimental method in other fields rather than material, among those fields’ human phenomena, whether psychological, historical or social.  The study found that it is beneficial to consider the human and social sciences as having great importance and notable position as other sciences especially the natural sciences, and it can play its effective role in the building of the human knowledge, in this way it is able and worthy to fulfill its role as one of the sciences

Stabilisation des systèmes non linéaire via des modèles flous incertains de type Takagi-Sugeno

L’objectif du travail réalisé dans ce mémoire est d’étudier les méthodes de stabilisation des systèmes non linéaires représentés par des modèles flous incertains de Takagi-Sugeno. L’étude de la stabilisation de ces types de modèles fait appel, dans la grande majorité des cas, à la méthode directe de Lyapunov avec une fonction de type quadratique. Celle-ci permet d’écrire facilement les conditions de stabilité sous forme de contraintes LMI ( Linear Matrix Inequalities). Les techniques utilisées sont des extensions de celles proposées pour les systèmes flous de Takagi-Sugeno sans incertitudes en profitant les méthodes de synthèse des systèmes linéaires incertains. Les deux approches utilisées pour la synthèse de lois de commande sont : La commande PDC ( Parallel Distributed Compensation ), le principe de cette méthode est de construire un régulateur par retour d’état pour chaque modèle local, la loi de commande globale est obtenue par interpolation des lois de commande linéaires locales. Le nombre de ces lois de commande locales est égal au nombre de règles. La deuxième approche proposée est la commande multi-contrôleurs linéaires basée sur l’utilisation d’un contrôleur local à chaque région de l’espace d’état, le signal de commande est obtenu par commutation entre les différents contrôleurs locaux. Cette approche permet l’optimisation du nombre de contrôleurs qui peut être inférieur au nombre de règles

A non homogeneous Riemann Solver for shallow water and two phase flows

In this work we consider a two steps finite volume scheme, recently developed to solve nonhomogeneous systems. The first step of the scheme depends on a diffusion control parameter which we modulate, using the limiters theory. Results on Shallow water equations and two phase flows are presented

Use of Probabilistic Engineering Methods in the Detailed Design and Development Phases of the NASA Ares Launch Vehicle

The United States National Aeronautics and Space Administration (NASA) is in the midst of a space exploration program called Constellation to send crew and cargo to the international Space Station, to the moon, and beyond. As part of the Constellation program, a new launch vehicle, Ares I, is being developed by NASA Marshall Space Flight Center. Designing a launch vehicle with high reliability and increased safety requires a significant effort in understanding design variability and design uncertainty at the various levels of the design (system, element, subsystem, component, etc.) and throughout the various design phases (conceptual, preliminary design, etc.). In a previous paper [1] we discussed a probabilistic functional failure analysis approach intended mainly to support system requirements definition, system design, and element design during the early design phases. This paper provides an overview of the application of probabilistic engineering methods to support the detailed subsystem/component design and development as part of the "Design for Reliability and Safety" approach for the new Ares I Launch Vehicle. Specifically, the paper discusses probabilistic engineering design analysis cases that had major impact on the design and manufacturing of the Space Shuttle hardware. The cases represent important lessons learned from the Space Shuttle Program and clearly demonstrate the significance of probabilistic engineering analysis in better understanding design deficiencies and identifying potential design improvement for Ares I. The paper also discusses the probabilistic functional failure analysis approach applied during the early design phases of Ares I and the forward plans for probabilistic design analysis in the detailed design and development phases

Reliability and Maintainability Engineering - A Major Driver for Safety and Affordability

The United States National Aeronautics and Space Administration (NASA) is in the midst of an effort to design and build a safe and affordable heavy lift vehicle to go to the moon and beyond. To achieve that, NASA is seeking more innovative and efficient approaches to reduce cost while maintaining an acceptable level of safety and mission success. One area that has the potential to contribute significantly to achieving NASA safety and affordability goals is Reliability and Maintainability (R&M) engineering. Inadequate reliability or failure of critical safety items may directly jeopardize the safety of the user(s) and result in a loss of life. Inadequate reliability of equipment may directly jeopardize mission success. Systems designed to be more reliable (fewer failures) and maintainable (fewer resources needed) can lower the total life cycle cost. The Department of Defense (DOD) and industry experience has shown that optimized and adequate levels of R&M are critical for achieving a high level of safety and mission success, and low sustainment cost. Also, lessons learned from the Space Shuttle program clearly demonstrated the importance of R&M engineering in designing and operating safe and affordable launch systems. The Challenger and Columbia accidents are examples of the severe impact of design unreliability and process induced failures on system safety and mission success. These accidents demonstrated the criticality of reliability engineering in understanding component failure mechanisms and integrated system failures across the system elements interfaces. Experience from the shuttle program also shows that insufficient Reliability, Maintainability, and Supportability (RMS) engineering analyses upfront in the design phase can significantly increase the sustainment cost and, thereby, the total life cycle cost. Emphasis on RMS during the design phase is critical for identifying the design features and characteristics needed for time efficient processing, improved operational availability, and optimized maintenance and logistic support infrastructure. This paper discusses the role of R&M in a program acquisition phase and the potential impact of R&M on safety, mission success, operational availability, and affordability. This includes discussion of the R&M elements that need to be addressed and the R&M analyses that need to be performed in order to support a safe and affordable system design. The paper also provides some lessons learned from the Space Shuttle program on the impact of R&M on safety and affordability

The Role of Probabilistic Design Analysis Methods in Safety and Affordability

For the last several years, NASA and its contractors have been working together to build space launch systems to commercialize space. Developing commercial affordable and safe launch systems becomes very important and requires a paradigm shift. This paradigm shift enforces the need for an integrated systems engineering environment where cost, safety, reliability, and performance need to be considered to optimize the launch system design. In such an environment, rule based and deterministic engineering design practices alone may not be sufficient to optimize margins and fault tolerance to reduce cost. As a result, introduction of Probabilistic Design Analysis (PDA) methods to support the current deterministic engineering design practices becomes a necessity to reduce cost without compromising reliability and safety. This paper discusses the importance of PDA methods in NASA's new commercial environment, their applications, and the key role they can play in designing reliable, safe, and affordable launch systems. More specifically, this paper discusses: 1) The involvement of NASA in PDA 2) Why PDA is needed 3) A PDA model structure 4) A PDA example application 5) PDA link to safety and affordability

Schéma SRNHS Analyse et Application d'un schéma aux volumes finis dédié aux systèmes non homogènes

International audienceThis article is devoted to the analysis, and improvement of a finite volume scheme proposed recently for a class of non homogeneous systems. We consider those for which the corressponding Riemann problem admits a selfsimilar solution. Some important examples of such problems are Shallow Water problems with irregular topography and two phase flows. The stability analysis of the considered scheme, in the homogeneous scalar case, leads to a new formulation which has a naturel extension to non homogeneous systems. Comparative numerical experiments for Shallow Water equations with sourec term, and a two phase problem (Ransom faucet) are presented to validate the scheme.Cet article concerne l'analyse et l'application, d'un schéma proposé récemment por une classe de systèmes non homogènes. Nous considérons ceux pour lesquels le problème de Riemann correpondant admet une solution autosimilaire. Deux exemples importants de tels problèmes sont l'écoulement d'eau peu profonde au-dessus d'un fond non plat et les problèmes diphasiques. l'analyse de stabilité du schéma, dans le cas scalaire homogène, amène à une nouvelle écriture qui a une extension naturelle pour le cas non homogène. Des expériences numériques comparatives pour des équations de saint-Venant avec topographie variable, et un problème diphasique (Robinet de Ransom) sont présentés pour évaluer l'efficacité du schéma

Finite volume characteristic flux scheme for transonic flow problems

This work deals with the numerical solution of internal transonic flow problems. Currently we expect 1D and 2D inviscid flow of perfect gas modelled by the Euler equations. We use finite volume characteristic flux scheme, called VFFC scheme, which can be viewed as a generalization of Roe scheme. The dissipation matrix is computed analytically or numerically. We present numerical results for 1D shock tube problem computed by the second order method, where the spatial accuracy is due to linear reconstruction with the minmod limiter and temporal discretization is done using explicit three stage Runge-Kutta method. Further numerical results for 2D transonic flow in GAMM channel have been achieved by the first order method on structured quadrilateral as well as unstructured triangular meshes