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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Experiments with the REMUS AUV

Phaneuf, Matthew D. 06 1900 (has links)
Approved for public release; distribution is unlimited / This thesis centers around actual field operations and post-mission analysis of data acquired using a REMUS AUV operated by the Naval Postgraduate School Center for Autonomous Underwater Vehicle Research. It was one of many platforms that were utilized for data collection during AOSN II, (Autonomous Oceanographic Sampling Network II), an ONR sponsored exercise for dynamic oceanographic data taking and model based analysis using adaptive sampling. The vehicle's ability to collect oceanographic data consisting of conductivity, temperature, and salinity during this experiment is assessed and problem areas investigated. Of particular interest are the temperature and salinity profiles measured fromlong transect runs of 18 Km. length into the southern parts of Monterey Bay. Experimentation with the REMUS as a mine detection asset was also performed. The design and development of the mine hunting experiment is discussed as well as its results and their analysis. Of particular interest in this portion of the work is the issue relating to repeatability and precision of contact localization, obtained from vehicle position and sidescan sonar measurements. / Lieutenant, United States Navy
152

The sandbox strategy : the why and how of federal law enforcement integration

Mandoli, Gregory R. 09 1900 (has links)
CHDS State/Local / This thesis examines the interoperability of federal law enforcement's Big Six investigative agencies, to include the Federal Bureau of Investigation, Immigration and Customs Enforcement, Drug Enforcement Administration, Alcohol Tobacco Firearms and Explosives, Internal Revenue Service-CID, and the United States Secret Service-Investigations. The main issue is whether, in the post-9/11 environment of transnational and terrorist criminal threats, the current administrative and jurisdictional configuration of the Big Six within three executive epartments with overlapping duties marginalizes the nation's investigative work-product. This discussion includes the establishment of metrics used to gauge the functionality of the Big Six and, thus, to determine whether Negative Characteristics are present that materially affect the "total" mission. Ultimately, the conclusion is drawn that the integration of the Big Six into a single agency, namely the FBI, would better serve the nation's federal investigative law enforcement needs. This leads into the next area of discussion, which is how to integrate the Big Six. Associated with both these topics is an analysis of what the federal investigative mission means and whether it should include a domestic intelligence product. / Special Agent, Department of Homeland Security, ICE
153

Développement de capteurs chimiques d'explosifs basés sur la détection par fluorescence / Development of explosives chemichal sensors based on a fluorescent detection

Caron, Thomas 14 December 2010 (has links)
Face à  la menace croissante du terrorisme, il est essentiel de mettre en place des mesures de précaution et des moyens de surveillance permettant d'assurer la sécurité dans les lieux publics. Dans ce cadre, le CEA Le Ripault développe des systèmes de détection portatifs et autonomes dédiés à la détection d'explosifs en phase gazeuse. Cette thèse s'inscrit dans ce projet. L'objectif de cette étude est de concevoir et d'étudier les propriétés de matériaux sensibles fluorescents dédiés à la détection de composés nitroaromatiques tel que le TNT. Ainsi, les propriétés de mise en forme et de détection de différents matériaux, sensibles aux composés nitroaromatiques, ont été étudiées. Après identification du matériau le plus efficace pour cette application, nous avons étudié sa stabilité et nous avons cherché à comprendre le mécanisme de détection associé à ce matériau fluorescent. Les performances du détecteur de composés nitroaromatiques, intégrant ce matériau, ont ensuite été évaluées. / In order to overcome the growing threat of terrorism, it is essential to put into operation preventive measures and means of monitoring to ensure security in public areas. In this context, the CEA Le Ripault develops portable and self-contained detection systems dedicated to the detection of explosives in the gas phase. This PhD work is part of this project. The objective of this study is to design and to assess the properties of fluorescent sensitive materials dedicated to the detection of nitroaromatic compounds such as TNT. Consequently, the ease of deposition, thin films properties and detection performances of several sensitive materials have been considered. After identification of the most effective material for this application, we studied its stability and we searched to understand the detection mechanism associated with this fluorescent material. Then, the performances of the device which incorporate this sensitive material have been evaluated for the detection of nitroaromatic compounds.
154

Examination of the use of exact versus approximate phase weights on the performance of a synthetic aperture sonar system

Boland, Matthew R. 03 1900
Approved for public release; distribution in unlimited. / Synthetic aperture sonar beamforming and signal processing relies on properly steering and focusing the aperture beam pattern in order to co-phase all the received signals. Due to the effects of motion in the synthetic aperture sonar problem, the propagation path between the transmitter, discrete point scatterer, and the receiver is time varying. Traditionally, simple approximations are used to determine these propagation ranges and angles of incidence and scatter. Methods to determine these ranges and angles exactly may significantly improve array gain and, therefore, target detection. This thesis investigates improvements to SAS signal processing algorithms using exact methods for the calculation of the time-varying ranges between transmitter and discrete point scatter, and between discrete point scatter and receiver, and the phase angle of the scattered acoustic signal incident upon the receiver. Using computer simulations, exact range and angle calculations were performed for different scenarios and compared to ranges and angles determined using standard approximations. The exact ranges were then used to determine incident phase, and were again compared to the approximate methods. Comparison of the exact and approximate methods was based on range estimation error and percentage error. Improvements in synthetic aperture array gain using exact phase weights based on exact, time-varying range solutions are proposed. / http://hdl.handle.net/10945/1142 / Lieutenant, United States Navy
155

Heat Generation Mechanisms in Energetic Composite Materials Under Ultrasonic Excitation

Zane A Roberts (6998114) 15 August 2019 (has links)
<p>Thermal dissipation of mechanical energy from periodic loading in energetic materials (EMs) leads to the creation of areas of intense, localized heating, called hot spots. The impact and shock conditions for the hot spot initiation of solid explosives have been extensively explored, but little work has focused on high-frequency contact loading. In order to design formulations to address unintentional initiation by mitigating heating in polymer-bonded explosives (PBXs) and other heterogeneous EMs, the mechanisms of heat generation which lead to the thermal initiation of energetic composites under ultrasonic excitation were explored. Heat generation mechanisms which may lead to unintentional initiation were identified through the diagnostic techniques of second harmonic generation (SHG) of δ-HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocine) crystals; X-ray phase contrast imaging (PCI) performed at the Argonne National Laboratory Advanced Photon Source; infrared (IR) thermography; and optical microscopy. This work concludes with high-speed mesoscale observations of dense layers of PETN (pentaerythritol tetraniterate), CL-20 (hexanitrohexaazaisowurtzitane), RDX (1,3,5-trinitro-1,3,5-triazine), and HMX which were damaged or driven to decomposition under acoustic insult using the non-intrusive imaging technique of shadowgraphy to detect hot spots within the transparent binder. Recommendations are formed which address binder adhesion, energetic material properties, and particle morphology on the vibration sensitivity of a PBX formulation. </p>
156

Spectroscopie de plasma induit par laser appliquée à la détection de résidus d'explosifs

Mothe, Emilien 15 December 2011 (has links)
La menace d’attaques terroristes reste omniprésente dans de nombreux lieux à forte fréquentation. Une technique capable de détecter les substances explosives est donc nécessaire pour traiter au mieux cette menace. Initié par le Ministère de la Défense et la Direction générale de l’Armement, le projet REI ExploLIBS a pour but d’étudier le potentiel de la spectroscopie de plasma induit par laser à détecter les résidus d’explosifs. Des études expérimentales et théoriques sont menées par Bertin Technologies en collaboration avec le laboratoire LP3 – UMR 6182. L’ablation de polymères sous différentes atmosphères a permis de caractériser l’évolution spatio-temporelle de l’émission des molécules CN et C2. Le rayon d’émission, la température et la décroissance de l’intensité sont reliés au processus de formation des molécules. L’analyse complémentaire par le calcul de la composition du plasma en équilibre thermodynamique local permet de mettre en évidence la présence de molécules en fortes concentrations dans le plasma difficiles à visualiser en spectroscopie optique. Ces études ont abouti au développement d’une sonde portable dédiée à la détection des explosifs. Le taux de détection est évalué à plus de 90% et le taux de faux positif inférieur à 5%. La limite actuelle de sensibilité est estimée à 55 µg.cm-2. / The threat of terrorist attacks remains omnipresent in many high traffic sites. A technique capable of detecting explosives is needed to best address this threat. Initiated by the Ministère de la Défense and the Direction Générale de l’Armement, the project REI ExploLIBS aims to explore the potential of laser-induced breakdown spectroscopy to detect explosive residue. Experimental and theoretical studies are carried out by Bertin Technologies in collaboration with the LP3 laboratory – UMR 6182. The ablation of polymers under different atmospheres permits to characterize the spatial and temporal evolution of the emission of the CN and the C2 molecules. The radius of emission, the temperature and the decrease of the intensity are related to the formation process of the molecules. The additional analysis by the calculation of the composition of the plasma in local thermodynamic equilibrium reveals the presence of molecules in high concentrations in the plasma that are difficult to visualise in optical spectroscopy. These studies led to the development of a portable sensor dedicated to the detection of explosives. The detection rate is estimated at over 90% and the false positive rate below 5%. The current sensitivity limit is estimated at 55 µg.cm-2.
157

Improvement of mining efficiencies at Thamazimbi iron ore mine

Rodger, Sean James 14 November 2006 (has links)
Student Number : 9506626A - MSc (Eng) research report - School of Mining - Faculty of Engineering and the Built Environment / Significant research has been carried out over the years into what effect blast designs and techniques have on the final product in the mining process. There are numerous parameters that can be altered to deliver downstream benefits – the key is to determine which changes are appropriate for the rock body in question. A project is currently underway at Thabazimbi Iron Ore Mine (Northern Province, South Africa) to improve the operational efficiency through attention to the blasting operation. Previous research suggests changing fragmentation will have an effect on mining efficiency, but no definitive model has been developed directly linking the two. Using data collected during the project, the author developed a sensitivity analysis tool, which defines the effect of changing fragmentation on overall mine efficiency. This prediction model was based partly on theory and partly on empirical information gathered from mine databases and personnel. Over the course of this project, this model was validated through the practical implementation of the theory behind its development. This involved decreasing powder factors through increasing the drilling pattern, thus changing the resulting fragmentation of the muckpile. Subsequently, downstream effects on mining efficiency were monitored and these results were recorded in the model. The proven model was then used to identify areas of opportunity for improvement. In this report two areas are discussed, firstly, the implementation of a doped emulsion replacing ANFO across the mine, and secondly the introduction of electronic detonators. The second option would require further test work to develop confidence in the assumptions made in the model, concerning the effect of timing accuracy on fragmentation. This research report covers the background to the project, an explanation of the model and the final results obtained.
158

Studies of nanoparticle reinforced polymer coatings for trace gas detection

Unknown Date (has links)
With the goal of improving chemical detection methods for buried improvised explosive devices (IED’s), the intention of this study is to show that functionalized nano-particles improve the sensing properties of a polymer applied to gas sensors. The approach was reinforcing the polymer, Nafion, with acid-functionalized carbon nanotubes (CNT’s). Ammonia was chosen as the analyte for its similarity to IED byproducts without the dangers of toxicity or explosion. Two sensor platforms were investigated: Quartz crystal microbalances (QCM’s) and microcantilevers (MC’s). Preliminary evaluation of treated QCM’s, via frequency analyzer, showed improvements in sensitivity and fast reversal of adsorption; and suggested increased stability. Tests with coated MC’s also supported the findings of QCM tests. Amplitude response of MC’s was on average 4 times greater when the Nafion coating contained CNT’s. Quantitative QCM testing with gas-flow meters showed that with CNT inclusion: the average number of moles adsorbed increased by 35% (>1.2 times frequency response); sensitivity improved by 0.63 Hz/ppt on average; although the detection threshold decreased marginally; but reusability was much better after extended exposures to concentrated ammonia. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2013.
159

Amélioration des explosifs par ajustement de leur balance en oxygène lors de la cristalisation par Evaporation Flash de Spray / Explosives enhancement by oxygen balance tuning throughout spray flash evaporation crystallization process

Berthe, Jean-Edouard 13 December 2018 (has links)
Dans la littérature, que ce soit pour un explosif secondaire ou un matériau composite, une balance en oxygène (BO) proche de 0% est assimilée à de bonnes performances énergétiques (vitesse de détonation, chaleur de décomposition, etc…). L’objectif majeur de cette thèse est d’améliorer les performances énergétiques d’explosifs secondaires courants (RDX, HMX, CL-20) par l’ajout d’un oxydant (DNA) afin d’obtenir un matériau composite avec une BO de -1%. Le mélange intime de ces deux composés est permis par un procédé d’évaporation flash de spray, utilisé habituellement pour réduire la taille de particules des explosifs. Les matériaux composites ont été cristallisés dans les trois cas avec succès, avec la présence d’explosif submicrométrique et de DNA nanostructuré. Un tel résultat a été permis grâce à une meilleure compréhension du procédé, et en conséquence l’ajustement des conditions expérimentales. L’étude de la réactivité de ces matériaux composites montre dans certains cas une désensibilisation, une diminution de la distance de la déflagration à la détonation, ou encore une augmentation de la vitesse de détonation, comparée aux explosifs correspondants. / In literature, for secondary explosive or composite material, an oxygen balance (OB) close to 0% is often linked to good energetic performances (detonation velocity, heat of decomposition, etc.). The main objective of this thesis is to enhance energetic performances of current secondary explosives (RDX, HMX, CL-20) by adding oxidizer (ADN) to obtain a composite material with an OB of -1%. The spray flash evaporation process, usually used for particle size reduction of explosives, enables to obtain an intimate mixture of these two compounds. Composite materials were successfully crystallized in three cases, resulting of submicrometric explosives and nanostructured ADN particles. These results were obtained thanks to a preliminary study for better process understanding and the optimization of experimental conditions. Reactivity studies show some desensitization, shorter distance from deflagration to detonation, and/or higher detonation velocity, compared to corresponding explosives.
160

Ion Mobility Spectrometry: Optimization of Parameters in Collision Cross Sections and Trace Detection of Explosives

Tianyang Wu (5931161) 17 January 2019 (has links)
Ion mobility spectrometry is a powerful technique for the study related to molecule. The work of tow major applications are introduced in this paper. The first application is the optimization of parameters in CCS. The accurate calculation of the collision cross section for multiple molecules is a long-time interested topic in the research for substances detection in micro scale. No reliable analytical approach to calculate the collision cross section has been established to date. Different approaches rely on different mechanism will provide different results in significant extent. This work introduce a method for the determination of parameters in the Lennard Jones potential. Experimental data combined with numerical computation was the fundamental strategy during the optimization of the parameters. In the experiment, electrospray is used as the ion source of IMS while a nebulizer was utilized to electrify the aromatic compounds. New parameters show no less accuracy and equal efficiency while can explain the physical meaning of the collision more clearly. The second application is the trace detection of explosives with very low concentration. The detection of explosives is an important topic in security, while the detection will be difficult due to the low vapor pressure of explosives. In this work, two types of devices are designed for the trace detection of explosives at an extremely low concentration. TNT is selected as the explosives in the experiment. The experiment succeed to reach a sensitivity of 1 part per quintillion, and even find out a linear relationship between the logarithm of TNT concentration and TNT vapor pressure.

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