Thesis (M.Eng.)(Chemical)--University of Pretoria, 2004. / Includes summary. Includes bibliographical references.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 75-78). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 75-78). Also available on the Internet.

Two streamline, ordinary differential equation (ODE) models for detonation, the Chan-Kirby model and the straight streamline approach of Watt et al., are extended to a multiphase system of equations. These multiphase equations, with realistic equations of state, are used to better capture the heterogeneities in non-ideal explosives used in mining applications. Streamline ODE multidimensional models are normally obtained by reducing the partial differential equations (PDEs) describing the motion of the material to ODEs by making approximations about some of the physics of the problem. These models are referred to as reduced ODE models in this work and are the primary focus of this research into fast, efficient solutions of non-ideal explosives. In the development of these reduced order forms, some terms in the full equations have been removed for analytical convenience. Although this is not always the result of a formal order of magnitude analysis, this somewhat empirical approach is justified by simulation studies. In particular, by demonstrating that in a variety of benchmark problems, the reduced order ODEs give similar results to those obtained from the much more complex, full order PDE models. Further support is obtained by comparing the reduced order solution with experimental results. Comparisons with multiphase direct numerical simulations and experiments are undertaken to investigate the effect of the approximations and assumptions made in the derivation of the models. Both models produce comparable diameter effect curves for two different non-ideal explosives, EM120D and ANFO, in unconfined conditions. Empirical assumptions in the Chan-Kirby model can be eliminated but investigation shows that the straight streamline multiphase extension is based on better approximations for non-ideal explosives. This latter approach also gives better prediction of the diameter effect curve and detonation driving zone shape. The multiphase straight streamline model is then extended to model confined multiphase detonations, with realistic equations of state for the confining material, and predicts most strong confinement examples well. Future work of extending to curved streamlines and including confinement other than strong or weak is discussed.

abstract: In today's world there is a great need for sensing methods as tools to provide critical information to solve today's problems in security applications. Real time detection of trace chemicals, such as explosives, in a complex environment containing various interferents using a portable device that can be reliably deployed in a field has been a difficult challenge. A hybrid nanosensor based on the electrochemical reduction of trinitrotoluene (TNT) and the interaction of the reduction products with conducting polymer nanojunctions in an ionic liquid was fabricated. The sensor simultaneously measures the electrochemical current from the reduction of TNT and the conductance change of the polymer nanojunction caused from the reduction product. The hybrid detection mechanism, together with the unique selective preconcentration capability of the ionic liquid, provides a selective, fast, and sensitive detection of TNT. The sensor, in its current form, is capable of detecting parts per trillion level TNT in the presence of various interferents within a few minutes. A novel hybrid electrochemical-colorimetric (EC-C) sensing platform was also designed and fabricated to meet these challenges. The hybrid sensor is based on electrochemical reactions of trace explosives, colorimetric detection of the reaction products, and unique properties of the explosives in an ionic liquid (IL). This approach affords not only increased sensitivity but also selectivity as evident from the demonstrated null rate of false positives and low detection limits. Using an inexpensive webcam a detection limit of part per billion in volume (ppbV) has been achieved and demonstrated selective detection of explosives in the presence of common interferences (perfumes, mouth wash, cleaners, petroleum products, etc.). The works presented in this dissertation, were published in the Journal of the American Chemical Society (JACS, 2009) and Nano Letters (2010), won first place in the National Defense Research contest in (2009) and has been granted a patent (WO 2010/030874 A1). In addition, other work related to conductive polymer junctions and their sensing capabilities has been published in Applied Physics Letters (2005) and IEEE sensors journal (2008). / Dissertation/Thesis / Ph.D. Electrical Engineering 2012

Alguns altos explosivos foram caracterizados por espectroscopia Raman e no Infravermelho, e o efeito da temperatura sobre os espectros Raman foi medido in-situ. Foram estudados os produtos comerciais TNT, HMX, RDX e PETN, os quais, com exceção do HMX e RDX, pertencem a classes químicas distintas e também foi investigado o TATP sintetizado no laboratório. As amostras foram inicialmente caracterizadas por FT-IR, FT-IR/ATR e espectroscopia Raman com excitação no visível (632,8 nm) e no NIR (1064 nm) visando determinar se a técnica de amostragem exercia algum efeito, especificamente transições de fase e degradação, sobre os espectros. ATR e FT-Raman forneceram os espectros a partir dos quais foi feita a atribuição de bandas, a qual foi suportada por simulações teóricas (DFT, B3PW91). Cada amostra foi aquecida até uma temperatura abaixo do ponto de fusão, na qual o comportamento do espectro com o aquecimento era reversível. No caso do PETN e TNT esse valor foi bem próximo do ponto de fusão e no caso do HMX e RDX, foi substancialmente inferior. As bandas mais afetadas pela temperatura devem ser aquelas envolvidas nas rotas de relaxação de energia em explosivos. Os resultados obtidos sugerem que o PETN sofra decomposição térmica através da ruptura da ligação C-ONO2, enquanto que no HMX e RDX a ligação N-N deve ser rompida. As mudanças no espectro do TNT indicam que vibrações envolvendo os grupos NO2 e a ligação C-N são as mais sensíveis à temperatura. TATP sublima à temperatura de 70°C e até essa temperatura o espectro não é afetado pelo calor. Provavelmente a energia é utilizada no processo de sublimação. / Selected high explosives were characterized by Raman and Infrared spectroscopies and the effect of temperature was followed in-situ by Raman spectroscopy. TNT, HMX, RDX, PETN (commercial products) and TATP belong to distinct chemical families (except HMX and RDX) and their response to heating was evaluated. The samples were first characterized by FT-IR, FT-IR/ATR and Raman with excitation in the visible (632.8 nm) and in the NIR (1064 nm) aiming at the detection of sampling effects in the obtained spectra, specifically phase transitions and degradation. ATR and FT-Raman were the techniques of choice to provide the spectra for band assignment, which was assisted by theoretical simulations (DFT). Each sample was heated up to a temperature well below its melting point, in order to avoid thermal decomposition. The bands most affected by temperature were taken as the routes for energy relaxation in explosives. The obtained results lead to the conclusion that PETN decomposes through the rupture of the C-ONO2 bond, whereas in HMX and RDX the N-N bond is broken. TNT spectra indicates that the NO2 and C-N vibrations are the most sensitive to temperature and TATP sublimated at 70°C and no bands were affected by temperature. The results are agreement with the literature or theoretical simulations.

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

Nébulex est un appareil permettant de solubiliser les vapeurs d’analytes présents dans l’atmosphère via la formation d’un spray. L’objet de ce travail est de développer un nouveau système de détection in-situ par électrochimie pour le nitrométhane, un constituant de compositions explosives artisanales. Les paramètres ont d’abord été optimisés pour évaluer la limite de détection qui peut être atteinte avec un système simple et robuste. Le mécanisme de réaction a été revisité dans nos conditions spécifiques et comparé à celui décrit dans la littérature. Ensuite, différentes voies de fonctionnalisation d’électrodes ont été explorées afin d’améliorer la répétabilité de la mesure et la sensibilité au nitrométhane. Enfin, le système de détection a été miniaturisé et intégré au prototype Nébulex. Des essais de détection de vapeurs ont pu être menés, conduisant à un temps de détection de l’ordre de la minute pour des teneurs en nitrométhane de quelques ppmv. / Nebulex is a device allowing the solubilization of atmospheric analyte vapors via a spray formation. The aim of this work is to develop a new in-situ electrochemical detection system for the nitromethane, a constituent of home-made explosives. The parameters were first optimized to determine the limit of detection which can be reached with a simple and robust system. The reaction mechanism was revisited in our specific conditions and compared to the one described in the literature. Next, several functionalization ways were explored to enhance the measurement stability and the sensitivity for nitromethane. Finally, the detection system was miniaturized and integrated to the Nebulex prototype. Vapor detection experiments were performed, leading to detection time in the range of a minute for few ppmv of nitromethane content.

M.Comm. / This study establishes an introductory management tool in the form of a computergenerated report card. The report card displays an overview of ~II pertinent key performance areas within an explosives production plant. The key performance areas cater for the planning, organising, staffing, reporting and controlling of explosives within an explosives production facility. The concept of the report card for the explosives production manager, makes use of the balanced scorecard as well as other key performance management tools to encourage management control, open communication and enhance performance drivers. The overall objective of the dissertation is to use certain assumptions that have become current in academic discussions of management control with particular relevance to aligning strategic control in order to establish what constituents may influence the production facilities' effectiveness, safety, efficiency and future focus areas for managers in the explosives production environment. There is nothing new about the basic notion of combining a number of performance measures in a compact description for a business operation. Recent developments have yielded useful approaches for management control within production companies. This research paper takes an avid search into the various communication tools, financial views, production flexibility, performance drivers, experience as well as development aspects that take place on a day-to-day basis within the explosives production facility. The essential indicators that constitute attention from management are outlined and drafted as a management tool that allows for the total comprehensive picture of the explosives production factory to be accurately reported and acted upon. This allows for more precise information upon which easier decision-making can take place.

M.Sc. / At the very roots of this dissertation lies a commercial process with many as yet unexplored characteristics that will be thoroughly examined, using a rich variety of statistical methods and techniques. Broadly speaking, the main objective of this study involves the development of techniques to control the quality of advanced explosives detonators used in commercial mining operations. To accomplish this task, various statistical characteristics of this detonation process are described and examined in order to obtain a holistic understanding of the underlying process. The parameters of the process are introduced and estimates for unknowns are derived. Real-time quality control techniques based on these results are suggested. 1.2. The role of blasting in mining A major part of South Africa's economy is based on the mining of the rich mineral deposits that are to be found in the country. These mining operations are carried out both above ground (open-pit iron ore mines, for example) and below ground (gold, uranium and others). Open-pit mining, in particular, requires significant amounts of commercial blasting to dislodge the high volumes of material that have to be moved and processed. An average blasting block at Iscor's Sishen mine, for example, contains about 250 000 tons of material, although a world record was established in April 1981 when 7, 2 million tons of rock was broken during a single blast. The chemical quality of the final products is partly controlled by supplying the primary crusher at the mine with a suitable mixture of so-called run-of-mine ore. To determine which material from a specific blasting block may be sent to the plant, and to which waste dump the remaining material should be assigned, factors such as beneficiation properties of the raw material and the content of various by-products are considered. Samples are typically taken from alternate blast holes for every metre drilled. Each drill sample is divided into two parts by means of a riffler for a washed and unwashed sample. The washed samples are examined and the rock types noted. Subsequently, all the samples are grouped and analysed chemically and the densities of the different rock types are determined. The results are processed and those for the washed and unwashed samples correlated. The blasting blocks in the pit are demarcated by means of whitewash lines, according to the divisions on the blasting-block plans, and they are marked with signs to guide shovel operators. Primary drilling is performed by means of electrically-driven rotary drills. At the Sishen mine, 310 mm diameter blast holes are drilled in all rock types. The following table depicts typical drilling 2 patterns for various rock types: Rock type Pattern (m) Drill depth (m) Hard iron ore 2 x 8, 3 3, 0 Medium-hard iron ore 1 x 9, 3 2, 7 Quartzite 8,2 x 9,4 2, 5 Flagstone 8,2 x 9,4 5 Calcrete 8,1 x 9,3 0 Primary blasting is done at Sishen with Heavy Anfo, an explosive that is manufactured by mine personnel at the emulsion plant on site. The ingredients for the explosive blends are transported by pump trucks to the blasting blocks, where it is mixed and pumped down the blast holes. Good fragmentation of the blasted material is a prerequisite for high loading rates by the loading equipment. At Sishen and other similar mines, a blasting efficiency of 3, 2 tons of rock per kilogram of explosives used, is considered to be acceptable.