Thesis (Ph. D.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: During the course of the CSIR’s research into the characterisation of explosive sources to devise methods of active intervention against threats, the need has arisen to research a particular means of early identification of the threat, which is the intense light flash during the threat detonation. For this purpose, a low cost rugged fast optical sensor was sought, since the application thereof would imply possible destruction, especially if integrated into an active intervention system later on. Given the average time of about 1ms available for intervention, it is clear that the active intervention system needs to operate within that period, hence the interest in the characteristic light emission of detonations in the pre-millisecond time frame. It was thought that by characterising this emitted light in terms of wavelength (temperature) and amplitude (and maybe other unique phenomena), the size of the threat could be determined and logic decisions derived therefrom. Needless to say, the environment in which the detonation light emission sensor is to operate, is extremely hostile in terms of shock, dust, flying debris, fast rise time of the explosive event, and Electro-magnetic Interference ( EMI) caused by the detonation itself. It must be noted that the light sensor research was driven by the outcome of research tests performed in aid of the development of an active intervention system. During this research the possibility of using commercially available low cost optical detectors at room temperature in combination with cost effective narrow band pass op- tical filters for the relative measurement of the light emission at discrete wavelengths during explosive detonation events were investigated. In 2006, not much applicable lit- erature could be found on this subject, hence the educated “shot-in-the-dark” approach then, which, by a systematic approach of explosive tests and continuous evaluation up to 2011, led to a surprisingly simple and robust low cost optical sensor. The research commenced with a range of optical detector elements selected for their responsivity and bandwidth in the optical spectrum of interest; the optical filtering by means of the recording of the emitted light signal during scaled down explosive tests at the Blast Impact Survivability Research Unit (BISRU) at the University of Cape Town. These tests were followed by full-scale tests at DBEL, and confirmed the findings at BISRU that the light emissions at the longer wavelengths (>2 m) manifest themselves too late for use within the intervention time frame. It was therefore decided to concentrate on the ultra-violet (UV) to near infra-red (NIR) spectrum of the emitted light for further full scale tests, since these discrete spectra showed the most promise for characterisa- tion of the emitted light. During this period a robust sensor housing with detector and filter mounts was designed for protection against blast shock and EMI. During the following years, certain types of optical detectors that were used during previous tests were eliminated according to results obtained, and more discrete narrow band pass filters added in the visible to NIR spectrum. A dedicated fast instrumen- tation amplifier (bandwidth > 1MHz and selectable gain up to 40dB) was developed to amplify weak signals (mainly caused by the heavy load in the detector circuit to improve rise times). However, the emission of light per wavelength in this region was measured to be relatively strong, and actually not as fast as was anticipated. This meant that the load resistor value of the detector element could be increased without affecting the signal negatively (bandwidth sufficient), thus adding to the amplitude of the signal to such a point that amplification in a 10m to 30 meter stand-off scenario was no longer needed. This culminated in an unamplified universal detector element being used with various narrow band pass filters up to 1 m, integrated as a very robust analog sensor at a discrete wavelength, and facilitating the direct comparison of light amplitude/relative intensity of the detonation at discrete spectral points. The sensor was employed in the field at various full scale explosive tests at DBEL, which led to the capture of a vast amount of light emitted data for different types of explosives, at various distances from the detonation, and of varying mass. Analysis of this data showed that the broadband light intensity of the emitted light scales to the explosive mass1/3 (as published by FJ Mostert and M Olivier in the Journal for Applied Physics, October 2011). Further analysis also confirmed the attenuation of the emitted light intensity by the square of the distance. Besides the aforesaid, various other key inputs to a possible active intervention algorithm have been identified. These findings are inputs to the determination of i.a. the detonation threat size, a vital component in the active intervention algorithm. The results of these experiments confirmed that the final low cost analog sensor can measure relative light emission at discrete wavelengths from detonation of explosives in the very early stages of development, and that the sensor has many other applications in the detonics research fields as well. / AFRIKAANSE OPSOMMING: Gedurende die WNNR se navorsing om detonerende bronne te karakteriseer ten einde aktiewe teenmaatreëls daar te stel, het die behoefte na vore gekom om die intense ligflits van ’n detonasie te ondersoek en te karakteriseer. Vir hierdie doel is ’n lae koste ligsensor benodig, synde die uiteindelike aanwending van hierdie ligsensor die vernietiging daarvan sou beteken, aldus die lae koste vereiste. Gegewe die kort tydsduur van die detonasie (’n paar millisekondes), is dit duidelik dat die ligflits karakerisering voor 1ms moet geskied, en daarom moet die ligsensor ook baie vinnig reageer om insette te lewer tot ’n aktiewe teenmaatreëlstelsel. Daar moet op gelet word dat die ligsensor se ontwikkeling uitkomsgedrewe was deur die navorsingstoetse om ’n aktiewe teenmaatreëlstelsel daar te stel. Een van die insette tot so ’n aktiewe teenmaatreëlstelsel is die grootte van die bedreiging: deur die ligflits te karakteriseer met die lae koste ligsensors t.o.v. golflengte, ligamplitude en moontlik ander verskynsels, kan bv. die massa inset verkry word wat nodig is vir die teenmaatreël algoritme. Die omgewing waarin die ligsensor moet funksioneer is baie onvriendelik i.t.v. skok, stof, vlieënde partikels en elektromagnetiese steurings, en sou daarteen beskerm moes word. Gedurende die navoring om so ’n ligsensor te ontwikkel (samelopend met die teen- maatreël navorsing), is kommersiële kamertemperatuur detektors oorweeg en aange- wend, in samewerking met nouband optiese filters. Die doel was om die ligopbrengs per golflengte te karakteriseer m.b.t. die plofstof massa, plofstof tipe en geometrie, en die afstand vanaf die detonasie. Bitter min literatuur oor die ligmeting van detonasies is aanvanklik gevind, aldus is ’n basislyn daargestel en deur sistematiese toetsing, ontleding en verbetering voortgegaan met die navorsing. Dit het gelei tot ’n verrassend eenvoudige en verharde lae koste ligsensor, wat deur meting sleutelinsette kon lewer tot die gesogte aktiewe teenmaatreël algoritme. Kommersiële detektors en nouband optiese filters is uitgesoek na aanleiding van hul prys en prestasie, en waar nodig, is versterking van die seine aangebring. Verskeie toetse met plofstof (op klein en groot skaal) is uitgevoer, waartydens ligmeting by spesifieke golflengtes opgeneem is. Analise van hierdie data het getoon dat die langer golflengtes (>2 m) se verskyning te laat is vir insluiting in die teenmaatreël algoritme, en is dus geleidelik (of sistematies) uitgeskakel. Die klem het geskuif na die detonasie liguitsetting in die UV tot naby infrarooi spektrum, wat nuwe detektors en filters tot gevolg gehad het (uitkoms gebasseerde navorsing). In die proses is ’n instrumentasie versterker ontwerp en gebou, vir buffering en versterking van seine hoër as 1 MHz met ’n selekteerbare aanwins van tot 40dB. Toetse met volskaalse ladings het egter getoon dat die liguitset besonder sterk is in die UV tot naby infrarooi spektrum, en ’n onversterkte ligsensor is aldus op die proef gestel. Hierdie proeflopie het getoon dat die onversterkte ligsensor besonder goed funksioneer op afstande tot en met 30m, en daar is op hierdie model voortgebou. Die verharde onversterkte ligsensor is aangewend in verskeie verdere volskaalse plofstof toetse, en het data gelewer t.o.v. detonasie liguitstraling by spesifieke golflengtes vir tipes plofstof, plofstof massas, plofstof geometrie en afstande vanaf die detonasie. Analise van hierdie data het getoon dat breëband liguitsetting se intensiteit skaal met die plofstof massa1=3 (gepubliseer as ’n artikel deur FJ Mostert en M Olivier in die Journal of Applied Physics’ - Oktober 2011). Verdere analise het verskeie sleutelinsette tot ’n aktiewe teenmaatreël algoritme geïdentifiseer. Die uitkoms van hierdie eksperimentele navorsing het getoon dat die lae koste lig- sensor relatiewe liguitsetting van ’n detonasie by gekose golflengtes vinnig kan meet in die baie vroeë stadia van die detonasie. Buiten dit, het die sensor verskeie ander nuttige aanwending in die detonasie navorsingsveld.

Les explosions de mélanges de gaz inflammables/solides combustibles ne sont pas bien comprises en raison de la complexité des transferts thermiques, des mécanismes de cinétiques et des interactions entre la turbulence /combustion. L'objectif principal de ce travail est d'étudier la sévérité des explosions des nanoparticules de carbone noir/méthane afin de comprendre l'influence de l'insertion des nanoparticules sur les explosions de gaz. Des tests ont été effectués sur ces mélanges dans un tube de propagation de la flamme et dans une sphère d'explosion standard de 20 L. L'influence de la turbulence initiale et de la taille de particule élémentaire du noir de carbone a également été étudiée. Il semble que l'insertion de nanoparticules de noir de carbone augmente d'environ 10% la sévérité de l’explosion pour les mélanges pauvres en méthane. Par conséquent, il semble que les nanoparticules ont un impact sur la sévérité de l'explosion même pour les systèmes à basse turbulence, contrairement aux systèmes impliquant des poudres de taille micrométrique qui nécessitent une dispersion à des niveaux élevés de turbulence. L'augmentation de la vitesse maximale de montée en pression est plus élevée pour des poudres avec un petit diamètre de particule, notamment en raison des phénomènes de fragmentation. En outre, un modèle numérique de propagation de front de flamme associé à un mélange gaz/noir de carbone a été développé pour examiner l'influence du noir de carbone sur la propagation de la flamme. Les résultats du modèle numérique suggèrent que la contribution de la chaleur radiative favorise l'accélération de la flamme. Ces résultats sont en accord avec les résultats expérimentaux de sévérité de l'explosion pour certains mélanges hybrides / Flammable gas/solid hybrid mixture explosions are not well understood because of the interaction of the thermal transfer process, the combustion kinetics mechanisms and the interactions between turbulence and combustion. The main objective on this work is to study the explosion severity and flame burning velocities of carbon black nanoparticles/methane to better understand the influence of added nanopowders in gas explosions. Tests have been performed in a flame propagation tube and in the standard 20 L explosion sphere. The influence of carbon black particles on the explosions severity and in the front flame propagation has been appreciated by comparing the results obtained for pure gas mixtures. It appeared that the carbon black nanoparticles insertion increases around 10% the explosion severity for lean methane mixtures. Therefore, it seems that nanoparticles has an impact on the severity of the explosion even for quiescent systems, contrary to systems involving micro-sized powders that requires a dispersion at high turbulence levels. The increment on the maximum rate of pressure rise is higher for powders with lower elementary particle diameter, which is notably due to the fragmentation phenomena. A flame propagation numerical model associated to a gas/carbon black mixture has been developed to examine the influence of carbon blacks on the flame propagation. The results of the numerical model suggest that the radiative heat contribution promotes the flame acceleration. This result is consistent with the experimental increase on the explosion severity for some hybrid mixtures

Made available in DSpace on 2014-10-09T12:34:53Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:18Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:34:53Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:18Z (GMT). No. of bitstreams: 0 / O presente trabalho tratou do estudo dos riscos apresentados pelos radioisótopos após serem submetidos aos efeitos da detonação de um artefato explosivo. O estudo permitiu a obtenção de dados baseados em pesquisas bibliográficas, documentais, cálculos e softwares, possibilitando análises das consequências resultantes de artefatos explosivos contendo radioisótopos. O objetivo deste trabalho foi a obtenção de conhecimentos quanto à potencialidade destrutiva do explosivo denominado emulsão, composto principalmente por nitrato de amônia, bem como das propriedades do cobalto, iodo e do irídio que farão parte da carga destes explosivos. Supomos que à emulsão fossem acrescentadas as atividades de 1,5.102 TBq de cobalto-60, 3,7.10-3 TBq de iodo-131 e 3,7 TBq de irídio-192 que são suas atividades representativas em radioterapia, medicina nuclear e gamagrafia respectivamente. Avaliamos a progressão da pluma radioativa a partir do epicentro da explosão, possibilitando análises dos valores das doses, da distribuição e do alcance, a partir do epicentro, dos radioisótopos estudados. A simulação da progressão da pluma radioativa foi realizada por cálculos e simulação computacional fazendo uso dos programas Blast/FX Explosive Effects Analysis Software e The HotSpot Health Physics Codes - Version 2.07.2. No trabalho só foram estudadas as doses resultantes da exposição externa considerando que todo material radioativo volatizou. Foi deixado para estudos futuros calcular as doses internas e no pulmão bem como as doses resultantes de estilhaços radioativos produzidos na explosão. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2016-04-18T21:39:49Z (GMT). No. of bitstreams: 3 Rodney Vicente de Souza1.pdf: 1174123 bytes, checksum: 7a62f896de855669fd1482cb7686b0a2 (MD5) Rodney Vicente de Souza2.pdf: 1457076 bytes, checksum: f145ee6c55c0e70f0cfdd3ad7e370967 (MD5) Rodney Vicente de Souza3.pdf: 3052150 bytes, checksum: 5500ea47ec4be6101280762f54f09dd7 (MD5) Previous issue date: 2009-08-03 / The solar phenomena are the main agents of magnetosphere disturbance and geomagnetic storms. During geomagnetic storms, the electrons in the magnetosphere can be accelerated to high speeds. These electrons can cause great damage to electrical equipment on the orbital satellite. For several decades the coronal mass ejections (CMEs) and the solar bursts have been studied but their physical processes are not fully understood. The goal of this work is establishing a possible tool to predict the occurrence of solar events from the behavior 7 GHz signals. The radio data were obtained with high sensitivity (<0.5 sfu) and temporal resolution (10 ms) with the Solar Radio Polarimeter in operation at the Itapetinga Radio Observatory (ROI). The analysis of the radio signal is made for the period of high solar activity on October 2003. The Wavelet Multi-Resolution technique was used to analyses the components of the period of radio signal at 7 GHz. We compare the signal noise amplitude, which also compared with the polarization changes at 7 GHz and the evolution of magnetic configuration of active regions obtained with MDI. The results show increase in the noise amplitude at 7 GHz and the appearance of period components, minutes before the minor burst (class < B), and hours or even day before the larger burst (class C, M, or X). We present in detail the behavior of component S at 7 GHz in association with the activity increasing and the occurrence of great explosions. / Os fenômenos solares são os principais agentes perturbadores da magnetosfera terrestre e podem produzir tempestades geomagnéticas. Durante as tempestades geomagnéticas os elétrons, presentes na magnetosfera, podem ser acelerados até velocidades relativísticas. Estes elétrons causam grandes danos aos equipamentos elétricos nos satélites em órbita. Durante várias décadas as ejeções de massa coronal (EMCs) e as explosões solares têm sido objeto de estudos, mas ainda não se entende totalmente os processos físicos, que os antecede. O objetivo deste trabalho é contribuir para a previsão destes eventos solares, através da análise dos padrões de comportamento do sinal em 7 GHz. Os dados foram obtidos com alta sensibilidade (>0,5 sfu) e resolução temporal (10 ms) com o Rádio Polarímetro Solar em operação no Rádio Observatório do Itapetinga (ROI). A análise do sinal rádio em 7 GHz é feita para o período de grande atividade solar de outubro de 2003. Utilizamos a técnica ondeletas de Multi-Resolução para identificar as componentes de período do sinal. Foi feita a comparação entre as variações na amplitude do ruído do sinal e na potência das componentes de períodos associados a polarização circular em 7 GHz e a evolução da configuração magnética das regiões obtidas do experimento MDI onde ocorreram as grandes explosões. Os resultados mostram aumentos na amplitude do ruído do sinal associados a aumentos pronunciados na potência das componentes de períodos do sinal em diferentes faixas, minutos antes das explosões menores (classificação em raios X < B), horas ou até dia antes das explosões maiores (classificação em raios X C, M ou X). Apresentamos detalhadamente neste trabalho, o padrão de comportamento da componente S em 7 GHz, que antecede as explosões solares.

M.Phil. / Three test and certification bodies in the explosion prevention field currently exist in South Africa. One of these bodies was started in 2003 and faced a significant number of challenges in competition with the two other wellestablished bodies / institutions. This dissertation covers some of the internal and external challenges especially with respect to strategic marketing in a small and specialized industrial market, but also in the global market. The dissertation is based on the basic requirements, analysis and implementation of a marketing strategy and marketing plan, covering both the theoretical aspects and the specific challenges as experienced by the body in the case study. Market research, market segmentation, industry analysis, competitive analysis, aspects of industrial marketing and SWOT Analysis are topics included in the development of the strategic and marketing plan for the business in the case study.

This thesis by articles addresses the role played by Chapman-Jouguet (CJ) deflagrations in deflagration to detonation transition (DDT) events. By definition, CJ deflagrations are flames propagating with a sonic flow in the burned gases, and are theoretically the fastest subsonic combustion waves able to propagate steadily, predicted using conservation of mass, momentum and energy. DDT is difficult to describe, as many complex phenomena and their interaction take place, including flame instabilities, turbulent combustion, and combustion in compressible medium, among others. Recent experiments and numerical simulations however showed that, prior to transition to detonations, deflagrations plateau at the CJ regime before rapid acceleration. In the present thesis, multiple aspects of the last stages of DDT are studied, and are each presented in published articles or articles in preparation. The two articles presented in Chapter 2 focus on experiments performed on the transition of a shock-flame complex to a detonation downstream of a single obstacle, in a stoichiometric propane-oxygen mixture at low pressure, mimicking the common configuration found at the last stages of DDT in experiments and numerical simulations performed in a channel filled with obstacles. The relative large size of the obstacle and the low gas initial pressure permitted to visualize the details of the initiation of the detonation around the obstacle. Transition to detonation was found to occur in a similar fashion for variously shaped obstacles, after flame acceleration due to the interaction with reflected shocks. This acceleration process was found to occur rapidly in the case where the incident flame propagated with a burning rate close to the Chapman-Jouguet value. The third article presented in Chapter 3 describes a model aimed to predict the properties of shocks followed by a CJ deflagration, in experimental configurations where the burned gases can be vented. The formulation is similar to the double discontinuity problem adapted from the work of Chue (1993), extended to cases where the burned gases are not confined by a rear wall anymore, but can be vented through an opening of known dimensions. The properties of the shock / CJ-deflagration complex could then be predicted and compared to flame measurements done prior the initiation of detonations, obtained on a selection of large scale DDT experiments. The good agreement suggests that DDT occurs when deflagrations reach the CJ regime, corroborating with observations done in shock tubes. The article presented in Chapter 4 is aimed to present a consistent method for calculating the structure of flames propagating at arbitrary burning velocities, from the low-Mach case (isobaric) up to the CJ deflagration regime. The method uses a dynamical system approach to calculate the steady wave structure, described by ordinary differential equations. A stability analysis near the burned and unburned gases permitted to develop a numerical shooting technique, which was used to obtain the flame structure and burning rate eigenvalue. Chapter 5 is a numerical study of the deflagration to detonation transition problem in one-dimension. By linearly increasing the burning rate eigenvalue to increase the flame burning velocity, the flame first reached the CJ condition. Subsequent increase in the burning rate leads to the self-organization of the flame into a CJ deflagration - shock complex. This self-organization triggers a pulsating gasdynamic instability leading to the transition of the flame to detonation.

In this work we develop a Blast-Propellant-Facility integrated analysis study, which evaluates, by using two different approaches, the blast-related impact of an explosive accident of the Space Shuttle during the first ten seconds after launch at Kennedy Space Center. The blast-related risk associated with an explosion at this stage is high because of the quantity of energy involved in both multiple and complex processes. To do this, one of our approaches employed BlastFX®, a software system that facilitates the estimation of the level of damage to people and buildings, starting from an explosive device and rendering results through a complete report that illustrates and facilitates the evaluation of consequences. Our other approaches employed the Hopkinson-Cranz Scaled Law for estimating similar features at a more distant distance and by evaluating bigger amounts of TNT equivalent. Specifically, we considered more than 500 m and 45,400 kg, respectively, which are the range and TNT content limits that our version of BlastFX® can cover. Much research has been done to study the explosion phenomena with respect to both solid and liquid propellants and the laws that underlie the blast waves of an explosion. Therefore our methodology is based on the foundation provided by a large set of literature review and the actual capacities of an application like BlastFX®. By using and integrating the lessons from the literature and the capabilities of the software, we have obtained very useful information for evaluating different scenarios that rely on the assumption, which is largely studied, that the blast waves' behavior is affected by the distance. All of this has been focused on the Space Shuttle system, in which propellant mass represents the source of our analysis and the core of this work. Estimating the risks involved in it and providing results based on different scenarios augments the collective knowledge of risks associated with space exploration.

Examination of seismic records during the time interval of the Sago Mine disaster in 2006 revealed a small amplitude signal possibly associated with an event in the mine. Although the epicenter of the signature was located in the vicinity where the explosion occurred, it could not be unequivocally attributed to the explosion. More needs to be understood about the seismicity from mine explosions in order to properly interpret critical seismic information. A seismic monitoring system located at NIOSH's Lake Lynn Experimental Mine has monitored nineteen experimental methane and dust based explosions. The objective of the study was to analyze seismic signatures generated by the methane and dust explosions to begin understanding their characteristics at different distances away from the source. The seismic signatures from these different events were analyzed using standard waveform analysis procedures in order to estimate the moment magnitude and radiated seismic energy. The procedures used to analyze the data were conducted using self-produced programs not available with existing commercial software. The signatures of the explosions were found to be extremely complex due a combination of mine geometry and experimental design, both of which could not be controlled for the purposes of the study. Geophones located approximately 600 m (1970 ft) and over from the source collected limited data because of the attenuation of the seismic waves generated by the methane explosion. A combination of the methods used to characterize the seismic signatures allowed for differentiation between experimental designs and the size of the explosion. The factors having the largest impact on the signatures were the mine geometry, size of the methane explosion, construction of the mine seal and location of the mine seal. A relationship was derived to correlate the radiated seismic energy to the size of the explosion. Recommendations were made, based upon the limitations of this study, on methods for better collection of seismic data in the future. / Ph. D.