Thesis (Ph. D.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains xiv, 215 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 143-147).

Orientador: Reginaldo Guirardello, Demetrio Bastos Netto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-07T08:23:33Z (GMT). No. of bitstreams: 1 MendoncaFilho_LetivanGoncalvesde_D.pdf: 5427915 bytes, checksum: 7869e5fa656a6b2cc31cdebb6074d24c (MD5) Previous issue date: 2006 / Resumo: Este trabalho utiliza o conhecimento científico relativo a explosões e efeitos associados para sugerir distâncias de segurança para proteção de edificações nas proximidades de explosivos e atmosferas inflamáveis, para aplicação nas áreas civil e militar. Através da análise de um inquérito de um acidente ocorrido em 1964 foi possível relacionar as duas metodologias utilizadas para estabelecer as distâncias atuais de segurança para habitações. Verificou-se algumas falhas em um dos trabalhos originais e com a correção proposta foram apresentadas novas equações relacionando massa de explosivo, distância e o custo de reparos para residências. Avaliou-se as distâncias de segurança adotadas no Brasil por meio de diversas correlações estatísticas. Foi realizado um estudo experimental consistindo na montagem e posicionamento de uma carga de explosivo em frente a uma edificação, a uma distancia variável de uma vidraça fixa. Com base neste estudo foram identificados diversos aspectos referentes à fragmentação de vidraças como: Relação entre espessura, impulso e velocidade de fragmentos. Novas distâncias de segurança foram propostas considerando uma diferenciação em relação ao tipo de estabelecimento, uso de taludes e o equivalente TNT da massa de explosivo. Uma alternativa de armazenagem é mostrada baseada no conceito de separação em compartimentos dos materiais explosivos para adequar os valores de distância de segurança praticados com os valores idealizados. No caso de explosões gasosas, tratou-se um caso real envolvendo uma explosão em um navio de transporte de material inflamável. Com base neste estudo foram propostas novas distâncias de segurança para atmosferas explosivas, usando o método multi-energético e o conhecimento da relação entre danos e sobrepressão desenvolvidos / Abstract: This work uses the original military scientific know how on explosions and its effects to suggest safety distances to cases dealing with explosives and inflammable atmospheres. Considering the information contained in an investigation of an accident which took place in 1964 in a production line of gunpowder at the "Fabrica Presidente Vargas",in the city of Piquete, São Paulo, it was possible to relate and review the two main techniques used as the basis of the actual safety distances in inhabited building in USA and Europe. Based on this study it was suggested some corrections at the american technique. With the correction it was possible to suggest two probit equations relating distance, weight of explosives and the repair costs to brick and wood houses. As the American analysis to determinate the safety distances was based on a patrimonial criterion and we were interested in establishing a criterion centered in the human being, severa I statistical correlations were employed to evaluate the effect of explosions on the human being, considering the safety distances of the Brazilian legislation. Due to the relevance of the risks associated with the glass hazards generated in window breakage by . overpressure an experimental study was performed. The experiment consisted in blasting explosive charge close to window so that the initial velocity was measured using a laser system with an electronic chronometer. The overpressure generated by the blast broke the window and threw the fragments against a special kind of foam glued on a wood wall. Some of the fragments were caught by the foam, in such away that it was possible to identify aspects concerning window breakaging relations between fragments thickness and ~nitial velocity .Also the effect of drag on the terminal velocity of fragments. Based on these studies new safety distances were suggested take in account the diversity of the establishments. '.The attenuation effect by the use of barriers and the TNT equivalents of explosives- and propellants were considered also in the new safety distances. The new values were compared with the Brazilian legislation leading to a proposal for storage of explosive materiais dividing them into severa I compartments to be adequate the actual values of the legislation with the suggested one. Considering the case of gas/vapor explosion, we dealt with a real case of explosion. Aspects related to evaporation, dispersion and development of inflammable and explosives atmospheres were considered along with the analysis of sensitivity of stimulus to ignition. A mechanism of the storage vessel rupture was suggested. based on the thermodynamic and kinetics analysis of the combustion system. Having the motivation of the necessity to define safety distances in similar cases it was suggested safety distances using the multi energy method developed by the TNO and the knowledge of the relation between damage and overpressure / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

Las voladuras son una forma de generación de vibraciones comunes en la actividad de construcción de obra civil, extracción de materiales (cantera y minas) y demoliciones. Estas son vibraciones causadas por actividad humana y han cobrando importancia a medida que las fuentes generadoras de tales vibraciones aumentan en cantidad, magnitud y cercanía a zonas pobladas. Unión Andina de Cementos (UNACEM), la cual se encuentra ubicada en el distrito de Atocongo en Villa María del Triunfo, dedicada a la extracción de caliza para la fabricación de cemento, realiza voladuras diarias con este fin. En ese sentido el objetivo de nuestra investigación es evaluar en qué medida los efectos dinámicos producidos por las voladuras, en la explotación minera de la planta de cementos UNACEM, podrían afectar las edificaciones del centro poblado Virgen de Lourdes. El tipo de investigación es cuantitativa y de nivel descriptivo; al no manipular las variables tenemos que su método es no experimental y de diseño explicativo. Los resultados obtenidos debían tener un punto de comparación, por lo que en la NORMA E030 DISEÑO SISMORESISTENTE del 2014 nos sirvió para aplicarla en un caso específico de una vivienda típica de la zona en mención. Se modelo esta vivienda en el software VISUAL FEA y se aplicaron las vibraciones recolectadas por las voladuras con la finalidad de analizar los resultados con la Norma E030 y verificar si las vibraciones eran capaces de afectar estructuralmente a la vivienda modelo. Los datos obtenidos demuestran que las vibraciones producidas por Cementos UNACEM para ese periodo cumplieron con las normas y no afectan estructuralmente a las viviendas del poblado Virgen de Lourdes. The explosions are a common way of generating vibrations in the activity of civil engineering construction, extraction of materials (quarry and mine) and demolitions. These vibrations are caused by human activity and have been gaining importance as generating sources of such vibrations increase in number, size and proximity to populated areas. Union Andina de Cementos (UNACEM) located in Atocongo Villa Maria del Triunfo, for the extraction of limestone for cement, makes daily blasts for this purpose. The objective of our research is to evaluate the extent to which dynamic effects of blasting in the mine UNACEM plant could affect the buildings of the Virgin of Lourdes populated center. The research is quantitative and descriptive level. By not manipulate the variables have their method is not experimental and explanatory design. The results should be a point of comparison, so the TECHNICAL STANDARD OF BUILDING E.030 EARTHQUAKE-RESISTANT DESIGN 2014 helped us to apply in a particular case which was a typical home in the area. This apartment in the FEA model VISUAL software and vibrations collected by blasting in order to analyze the results together with the standard E030 and see if the vibrations were able to structurally affect the model will be applied. The data obtained show that the vibrations produced by UNACEM’S CEMENTS for that period met the standards and not structurally affect the housing of the town Virgen de Lourdes.

No description available.

Explosions of gas and dust continue to be recognized as an extreme danger in underground coal mines and still occur despite significant technological advances. Mining researchers have been attempting to accurately measure and quantify ventilation and gas properties since early mining; however basic monitoring attempts were limited by the available technologies. Recent advancements in monitoring and communication technologies enable comprehensive atmospheric monitoring to become feasible on a mine-wide scale. Atmospheric monitoring systems (AMS) allow operators to monitor conditions underground in real-time. Real-time monitoring enables operators to detect and identify developing high risk areas of the mine, as well as quickly alert mining personnel underground. Real-time monitoring also can determine whether conditions are safe for mining, to operate ventilation systems more efficiently, and to provide an additional layer of monitoring atmospheric conditions underground. AMS utilizes numerous monitoring technologies that will allow underground coal mines to comprehensively monitor gas and ventilation parameters. AMS are utilized worldwide as well as in the United States, and can be modified to cater to specific hazards at different mines. In the United States, AMS are primarily used to monitor belt lines and electrical installations for smoke, CO, and CH₄, and to automatically alarm at set thresholds. The research in this study investigates and analyzed AMS across the world (specifically Australia, Canada, and United States). Two case studies presented in Chapter 5 focus on the utilization and implementation of AMS in two underground coal mines in the United States. These case studies identify challenges regarding installation, data management, and analysis of real-time atmospheric monitoring data. The second case study provides significant evidence that correlates mine ventilation fan outages and changes in barometric pressure to increases in methane from previous works. This research does not attempt to quantify data, but intends to provide engineers knowledge to utilize, design, and implement an AMS. Several incident scenarios are simulated using ventilation computer software, as well as the benefits of monitoring in past disasters are analyzed. This research does not intend to place blame, but intends to increase the understanding of utilizing and implementing AMS in underground coal mines. / Ph. D.

In this investigation a method is suggested for determining the dynamic, elastic response of a thin hemispherical shell subjected to a head-on attack by the initial shock wave of an underwater explosion. The shell which is fastened to the end of a fixed, semi-infinite tube of the same radius is surrounded by a high density fluid similar to water, and the internal cavity of the shell is filled with a low density fluid similar to air. The initial shock wave moves through the high density fluid. In the neighborhood of the obstacle, the shock front propagates in the direction of the axis of the semi-infinite tube and makes initial contact with the obstruction at the tip of the hemisphere at time equal to 0+. The following basic assumptions are used to define the mathematical model for the physical problem. The shock wave is considered to be a plane pressure pulse with exponential decay, the surrounding fluid is treated as if it were an acoustic medium, and the low density fluid is assumed to exert a constant pressure over the interior surface of the shell. The thin, hemispherical shell is regarded as being constructed of an isotropic, homogeneous, Hookean material of constant thickness. This shell experiences only small displacements. Moreover, in this model, the hemispherical shell is attached to a rigid, semi-infinite tube in such a way that the normal and in-plane displacements of the middle surface of the shell and the slope of the middle surface of the shell in the longitudinal direction are all zero at the shell-tube connection. The investigation for the solution to this axisymmetric problem, in which the mathematical formulations on the displacements of the shell and the velocity potential of the fluid are coupled, is begun with the separation of the displacements of the middle surface of the shell into two parts, ( )_M and ( )_B displacements. These are then shown to be analogous to the "membrane" and "pure bending" displacements familiar in the theory of static shells. The governing equations and the determinative conditions for the ( )_M displacements are found to be independent of the ( )_B displacements, while in the ( )_B formulation the ( )_M displacements are found to appear only in the determinative conditions. An approximate solution which is valid for small time and in which Poisson's ratio and the in-plane inertia term are assumed to be zero is obtained for the ( )_M displacements. A complementary solution for the ( )_B displacements which is valid in the neighborhood of the shell-tube connection is determined by using geometric and kinematic approximations in the ( )_B formulation. Approximate solutions for the displacements of the middle surface of the shell are then formulated by combining the ( )_M and ( )_B expressions above with the assumptions (valid only for the stated small time range) that the ( )_B contribution to the in-plane displacement is negligible over the entire shell and that the ( )_B contribution to the normal displacement is negligible except in the region near the shell-tube connection. Numerical results are calculated for a steel shell immersed in sea water and these results are presented in the form of tables and plots. / Ph. D.

Underwater explosions (UNDEX) generate high-energy shock waves that pose significant risks to military personnel during training exercises and combat scenarios. The primary objective of this research is to develop a surrogate modeling framework using engineering materials to investigate the biomechanical response of lung tissue during UNDEX events. A representative lung surrogate was designed to mimic the mechanical behavior of human lungs, utilizing thermoplastic elastomers (TPE) and polyurethane foam to replicate the elastic and porous nature of lung tissue and alveolar sacs. Material characterization tests were conducted to simulate quasi-static deformation through uniaxial tensile tests and dynamic loading conditions using dynamic mechanical analysis (DMA). The viscoelastic response of the surrogate material across a wide range of temperatures and frequencies is presented. A series of UNDEX experimental tests were conducted on the surrogates using the Virginia Tech Shockwave Generator (SWG), with targeted overpressures ranging from 10 to 20 psi. The surrogates were instrumented with sensors to record changes in principal strains and internal pressures. The results were analyzed to evaluate strain and pressure trends, impulse, and potential injury mechanisms. A linear relationship was observed between shockwave impulse, peak pressure, and principal strains, while no significant differences in internal pressure dynamics were observed within the tested blast overpressure ranges. / Master of Science / Underwater explosions create powerful shockwaves that can damage ship structures, affect marine life and harm military personnel during combat scenarios. However, the effects of these shock waves on the human body are not well understood. This study aims to fill that gap by studying representative models that replicate human lungs to help us better understand how they respond in dynamic conditions. Lung models were fabricated from commercially available materials that mimic the soft and elastic nature of the human lungs. The selected materials were extensively tested to understand its behavior under both static and dynamic conditions. Additionally, blast experiments were simulated using a shockwave generator to subject the models to controlled shock waves with pressures ranging from 10 to 20 psi. Pressure and strain sensors were mounted on the models to observe the dynamic changes that occur during exposure to shockwaves. Overall, the use of lung models as an alternative to live tissue is demonstrated and the experimental results were analyzed and discussed by evaluating injury mechanisms.

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Master of Science in Engineering / Regulation 10.24 of the Minerals Act (1991) of the Republic of South Africa is applied for the purpose of preventing the development and propagation of coal-dust explosions in underground coal mines. ( Abbreviation abstract ) / AC2017

Dans cette thèse, une nouvelle loi d'endommagement en traction des roches sous chargement exploisif est établie. Basée sur l'approche micro-mécanique et énergétique, la loi d'évolution d'endommagement dynamique est conçue à l'aide de la méthode mathématique d'homogénéisation basée sur le développement asymptotique, et en tenant compte de l'effet inertiel lors de la propagation de fissure. Les simulations numériques sont présentées en vue d'illustrer la capacité du modèle à décrire les comportements connus comme les effets de taille pour la réponse structurelle, la sensibilité au taux de déformation, la transition fragile-ductile et la dispersion de l'onde.<p><p>La loi est implémentée dans le code aux éléments finis LAGAMINE pour étudier la réponse macroscopique du modèle. Plusieurs cas d'applications en dynamique ont été examinés.\\<p><p>- En 1D, les problèmes de localisation ont été étudiés dans une barre sollicitée en traction dynamique par une rampe de chargement. Selon l'amplitude de chargement, trois réponses ont été identifiées: a) comportement purement élastique pour des faibles charges, b) localisation à l'extrémité encastrée de la barre pour des chargements modérés et c) localisation à la tête de la barre pour des chargements élevés. L'influence de la taille microstrurelle sur la localisation a été examinée. Des simulations numériques de l'essai de traction dynamique par écaillage ont été éffectuées. Des essais expérimentaux de traction dynamique par écaillage ont été réalisés sur la bauxite et ont permis de valider le modèle en comparant l'analyse post mortem de l'éprouvette aux résultats des simulations numériques d'écaillage. Ces essais ont aussi permis de déterminer les caractéristiques mécaniques du matériau, la résistance mécanique en traction dynamique, l'instant de rupture et la vitesse de déformation à rupture.\\<p><p>- En 2D, des simulations numériques sont efféctuées pour reproduire le comportement d'une mine sous charge explosive. Le modèle a été capable de reproduire l'endommagement en traction sous charge explosive. L'influence des paramètres du modèle tels que: l'orientation de fissures, la taille de microstructure et la valeur initial d'endommagement sur la distribution de l'endommagement autour du trou de charge a été étudiée. Enfin, un cas d'application sur les mines de bauxite de Guinée a été étudié, incluant un calcul de l'extension de la zone endommagée ainsi qu'une prédiction numérique du niveau de vibration engendrée suite aux tirs à l'explosif. La prédiction du modèle est globalement en accord avec les résultats de la littérature. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Ce travail porte sur de nouvelles explosions de cycles (orbites périodiques), l'étude de leur structure par l'analyse qualitative, leur mise en évidence par simulation numérique (Auto, Xpp) et la discussion de leur pertinence dans des modèles mathématiques dans les neurosciences. De telles explosions se produisent dans les systèmes dynamiques lents-rapides. La plupart des neurones sont excitables, dès 1940, Hodgkin identifia trois classes fondamentales d'axones excitables distinguées par leurs réponses à un courant injecté d'amplitude variable. A l'aide de la fonction de Lambert, nous étudions la transition entre les types I et II par des explosions de cycle incomplètes, initiées par une bifurcation de Hopf singulière et qui se terminent dans une bifurcation homocline dans des systèmes une variable rapide/une variable lente. Vient ensuite une étude poussée du système de Hindmarsh-Rose. Il s'agit d'un système deux variables rapides/une variable lente qui produit des oscillations en salves (ou bursting). Nous généralisons la notion d'ensembles candidats-limites-périodiques (clp) aux systèmes tridimensionnels, il s'agit des ensembles invariants du système à la limite singulière. A l'aide de ces derniers, nous obtenons une description très fine de la déformation du cycle limite jusqu'à l'addition d'un nouveau spike au burst. Nous finissons par une étude de la minimalité du modèle de F. Clément et J.-P. Françoise. Ce dernier est un système 4D qui modélise l¿activité des neurones à GnRH. Nous étudions un système une variable rapide/deux variables lentes qui reproduit certaines des caractéristiques du modèle 4D, notamment des Mixed-Modes oscillations. / This thesis is focussed on the analysis of novel explosions of limit cycles (periodic orbits). We provide a study of their structure by qualitative analysis, exhibit evidences of their existence by numerical simulations (Auto, Xpp) and propose a discussion of their relevance in mathematical modeling for neurosciences. Such explosions occur in the slow-fast dynamical systems. Most of neurons are excitable, Hodgkin (1940) identified three fundamental classes of excitable axon distinguished by their responses to a current of variable amplitude injected. Using the Lambert function, we study the transition between types I and II by incomplete explosion of cycle. This explosion, produced by a planar vector field with one fast/one slow variable, is initiated by a singular Hopf bifurcation and ends via a homoclinic bifurcation. The next chapter proposed a study of the Hindmarsh-Rose system. This system, composed of one fast/ two slow variables, is well known to produce square wave bursting oscillation. We generalize the notion of candidate-limit-perodic sets (CLP-sets) to three-dimensional systems. A CLP-set is an invariant set of the system in the singular limit. Using these, we get a very acurate description of the limit cycle deformation under the variation of a parameter until the addition of a new spike to burst. Finally, we propose a study fot the minimality of the model introduced by F. Clement and J.-P. Françoise. The latter is a 4D system that models the activity of GnRH neurons. We study a system composed by one fast /two slow variables that reproduces some of the features of the 4D model, including Mixed-Modes oscillations.