Evaluation of Seismic Soil-Structure Interaction (SSI) by Different Approaches

The paper investigates the seismic SSI effects for rigid type structures. Structural response is computed by modal synthesis versus frequency response approach. The main aspects analysed are as follows: a) the seismic SSI effects on structural response; b) shortcomings in the current SSI computational procedure; c) seismic structure –soil-structure interaction (SSSI) effects on structural response of neighbouring heavy buildings. Two case studies are presented: a shearwell multistory building (SMB) on soft clay and a massive reactor building (RB). Seismic response quantities are accelerations, displacements, stresses, floor response spectra (FRS) and spectra amplification functions (SAF)

Development and Characterization of a RIE Process for Anisotropic Trenches in Silicon

Reactive Ion Etching (RIE) is an important process widely used in the fabrication of micro-electro mechanical-systems (MEMS) especially for microfluidic channels. The purpose of this investigation was to develop a process for anisotropic trenches in silicon using the Drytek Quad reactive ion etching system available at the Semiconductor and Microsystems Fabrication Laboratory at Rochester Institute of Technology. The etch profiles were analyzed using Scanning Electron Microscopy (SEM) and the aspect ratio dependent etching (ARDE) effect, and the etch anisotropy were characterized. At the end, this investigation demonstrated highly anisotropic trenches etched in silicon. A baseline process for etching anisotropic trenches in silicon using the Drytek Quad was established

Self-similar sets in convex metric spaces

The purpose of this paper is to present some existence and uniqueness results for self-similar sets in convex complete metric spaces

Interpolation par des fonctions entières

Soit $A$ une algèbre normè unifère commutative complète sur un corps commutatif à valeur absolue non triviale. L'article montre qu'il existe une fonction entière, ayant les coefficients en $A$ qui donne une solution pour un problème d'interpolation infinie en $A$

Vanishing Waves on Closed Intervals and Propagating Short-Range Phenomena

This study presents mathematical aspects of wave equation considered on closed space intervals. It is shown that a solution of this equation can be represented by a certain superposition of traveling waves with null values for the amplitude and for the time derivatives of the resulting wave in the endpoints of this interval. Supplementary aspects connected with the possible existence of initial conditions for a secondorder differential system describing the amplitude of these localized oscillations are also studied, and requirements necessary for establishing a certain propagation direction for the wave (rejecting the possibility of reverse radiation) are also presented. Then it is shown that these aspects can be extended to a set of adjacent closed space intervals, by considering that a certain traveling wave propagating from an endpoint to the other can be defined on each space interval and a specific mathematical law (which can be approximated by a differential equation) describes the amplitude of these localized traveling waves as related to the space coordinates corresponding to the middle point of the interval. Using specific differential equations, it is shown that the existence of such propagating law for the amplitude of localized oscillations can generate periodical patterns and can explain fracture phenomena inside materials as well

Études des interactions aéroservoélastiques pour le mouvement de l'avion de test ATM au complet (longitudinal et latéral) en STARS

Dans cette thèse, le logiciel STARS (Structural Analysis Routines) est utilisé pour effectuer les analyses aéroservoélastiques de l'avion. STARS a été conçu par Dr. Kajal K. Gupta aux laboratoires de Centre de la NASA Dryden Flight Research. Le but de notre thèse est le développement d'un modèle complet d'un avion (longitudinal et latéral) en partant de sa géométrie connue uniquement dans le plan latéral. Le modèle de référence ATM (Aircraft Test Model) a servi de base pour la réalisation du modèle complet d'un avion. C'est un modèle d'éléments finis d'un avion étudié seulement dans son plan latéral et qui contient tous les éléments essentiels pour effectuer une analyse aéroservoélastique toujours dans son plan latéral. Dans une première étape, on va réaliser le modèle complet de l'avion par un ensemble d'éléments finis, donc des noeuds flexibles d'une certaine masse, amortissement et rigidité. Les modes de vibrations du modèle de test de l'avion ATM au sol, donc en l'absence de forces aérodynamiques, sont les modes de flexion et de torsion pour les surfaces portantes, le fuselage et les surfaces de commande. Deuxièmement, l'avion est considéré en vol, sous la présence des forces aérodynamiques non stationnaires généralisées. Par la suite, les coefficients aérodynamiques d'influence sont calculés en fonction de six à dix fréquences réduites et plusieurs nombres de Mach de l'avion par méthode de doublets (DLM). Les vitesses de battement pour l'avion complet ATM en boucle ouverte sont obtenues par les méthodes d'analyse de battement k et pk et ASE (similaire à la méthode LS) en STARS, et une comparaison finale est réalisée. On a trouvé que les vitesses et les fréquences de battement obtenues sur le modèle de l'avion complet (longitudinal et latéral) sont très proches de celles obtenues en STARS sur la moitié du modèle original ATM d'où nous pouvons conclure que notre modèle complet de l'avion est validé. Grâce au travail réalisé dans cette thèse, on pourra, à partir de maintenant, réaliser les calculs des interactions aéroservoélastiques sur l'avion au complet

Measure transformation and efficient quadrature in reduced-dimensional stochastic modeling of coupled problems

Coupled problems with various combinations of multiple physics, scales, and domains are found in numerous areas of science and engineering. A key challenge in the formulation and implementation of corresponding coupled numerical models is to facilitate the communication of information across physics, scale, and domain interfaces, as well as between the iterations of solvers used for response computations. In a probabilistic context, any information that is to be communicated between subproblems or iterations should be characterized by an appropriate probabilistic representation. Although the number of sources of uncertainty can be expected to be large in most coupled problems, our contention is that exchanged probabilistic information often resides in a considerably lower dimensional space than the sources themselves. In this work, we thus use a dimension-reduction technique for obtaining the representation of the exchanged information. The main subject of this work is the investigation of a measure-transformation technique that allows implementations to exploit this dimension reduction to achieve computational gains. The effectiveness of the proposed dimension-reduction and measure-transformation methodology is demonstrated through a multiphysics problem relevant to nuclear engineering

Simulation of the Behavior of 32-Layer Composite Plate for Ballistic Protection

This paper presents experimental results and a failure analysis of a composite for ballistic protection. The stratified plate is manufactured at laboratory scale, after a technology designed by the authors. The plates were tested for level FB2, taking into account the standard SR EN 1522:2004 (Windows, doors, shutters and blinds. Bullet resistance. Requirements and classification) and SR EN 1523:2004 (Windows, doors, shutters and blinds. Bullet resistance. Test method) and the results point out that this plate could face more dangerous threats. In order to evaluate the behavior of the plate under the impact characterizing a higher level of threat, the authors uses a FE model and simulated the system bullet – plate for different impact velocities