• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 12
  • 4
  • 3
  • Tagged with
  • 31
  • 9
  • 8
  • 7
  • 6
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 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.
21

Toward particle size reduction by spray flash evaporation : the case of organic energetic crystals and cocrystals / Réduction de la taille des particules par spray flash évaporation : le cas des cristaux et cocristaux organiques énergétiques

Pessina, Florent 05 October 2016 (has links)
La cristallisation en continu de nanoparticules énergétiques est un défi de longue date. Le Spray Flash Evaporation (SFE) est une technique majeure développée et brevetée en interne, pour la production en continu de matériaux énergétiques submicroniques ou nanométriques ; la technologie se base sur la surchauffe d’un solvant pulvérisé dans le vide et s’évaporant de manière flash. Ce présent travail de recherche a pour but de comprendre et contrôler la cristallisation au sein du procédé SFE. Le RDX et le cocristal CL-20:HMX 2:1 sont étudiés. La sursaturation, concernant le SFE, est une fonction du temps et de l’espace liée aux tailles et vitesses de gouttes : elle fut variée par un anti-solvant et par l’amélioration du SFE avec un système double buse. Ensuite, PVP 40K et PEG 400 ont été utilisés afin de contrôler la nucléation et la croissance. Les particules ont pu être ajustées d’une taille de 160 nm à 5 µm, avec des morphologies facettées ou sphériques et avec des sensibilités moindres. / The continuous formation of nanosized energetic material is a long-standing challenge. Spray Flash Evaporation (SFE) is a major technique, internally developed and patented, for continuously producing energetic materials at submicron or nano scale; it relies on the superheating of a solvent sprayed into vacuum and thus flashing. This present research project aims to understand and control the crystallisation occurring in the SFE process. RDX and the cocrystal CL-20:HMX 2:1 was studied overcome the limited in situ characterizations also. The supersaturation is a function of time and space in SFE, linked to the size distribution and velocity of droplets. Supersaturation was raised with an anti-solvent and by the enhancement of the SFE with a dual nozzle system. Then PVP 40K and PEG 400 were successfully used to alter the nucleation and the growth. The particles were subsequently tuned from 160 nm spheres to 5 µm grains and were less sensitive, especially toward electrostatic discharge.
22

<b>Development of a Sustainability-Oriented Decision-Making Framework and Computational Tool for Energetic and Critical Material Evaluations</b>

Anusha Sivakumar (18777499) 06 June 2024 (has links)
<p dir="ltr">The modern world faces many challenges related to sustainability, including the ability to make high-level decisions using a sustainability-oriented framework, a matter of increasing importance to the United States military with respect to energetic materials (EMs). Although a few pieces - process flowsheet optimization, life cycle assessment (LCA) studies, and the use of optimization tools to identify an option - have been studied and utilized, there exists no systematic approach that combines all these pieces to create a framework that allows for holistic decision making. This is especially true with EMs, other key critical materials, and new methods of manufacture. An interconnected framework for LCA-based decision making is developed and a tool based on this framework created for use with novel materials. The interconnected framework and tool are utilized in two case studies related to the manufacture of RDX- a lab-scale, batch-mode configuration and a simplified continuous-mode configuration, to determine the optimal reaction temperature.</p>
23

Plant functional trait and hyperspectral reflectance responses to Comp B exposure: efficacy of plants as landmine detectors

Manley, Paul V, II 01 January 2016 (has links)
At least 110 million landmines have been planted since the 1970s in about 70 nations, many of which remain in place today. Some risk of detection may be mitigated using currently available remote sensing techniques when vegetation is present. My study focused on using plants as phytosensors to detect buried explosives. I exposed three species representing different functional types (Cyperus esculentus (sedge), Ulmus alata (tree), Vitis labrusca (vine)) to 500 mg kg-1 of Composition B (Comp B; 60/40 mixture of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and 2,4,6-trinitrotoluene (TNT)), a commonly used explosive mixture, and measured functional traits and reflectance over a nine-week period. Cyperus esculentus was not a good indicator for the presence of explosive compounds. Comp B treatment woody species, U. alata and V. labrusca, exhibited changes in pigment content, leaf area, specific leaf area, dry leaf biomass, and canopy reflectance. The efficacy of plants as landmine detectors is species and/or functional group dependent.
24

Estudo da compatibilidade de RDX e HMX com polímeros e materiais inertes.

Maria Alice Carvalho Mazzeu 01 July 2010 (has links)
A compatibilidade química de explosivos é estudada para avaliar potenciais riscos quando os mesmos são colocados em contato com outros materiais durante a produção, armazenamento e manuseio. Esta compatibilidade pode ser estudada por vários métodos, tais como DSC (Calorimetria Exploratória Diferencial), TG (Termogravimetria), Estabilidade química a vácuo, microcalorimetria, calorimetria de fluxo de calor, etc. Os métodos de ensaios e a definição de critérios de avaliação são elementos importantes quando um estudo de compatibilidade está sendo realizado. Nesse trabalho, a compatibilidade química de dois importantes explosivos utilizados em armamentos, RDX (ciclotrimetilenotrinitroamina) e HMX (ciclotetrametilenotetranitroamina), foi estudada com polímero fluorado (Viton B) e alumínio em pó (Al 123), usando os métodos DSC, TG e Estabilidade química a vácuo. Os três métodos forneceram informações importantes sobre a compatibilidade química dos materiais, através dos parâmetros térmicos e volume de gás liberado. Observou-se que o HMX apresenta compatibilidade com Viton B e Al, da mesma forma que o RDX apresenta compatibilidade com Viton, porém no estudo de compatibilidade do RDX com Al, com os métodos DSC e TG, nota-se um pico adicional, após o pico de decomposição, o que é um indicativo de incompatibilidade. Os métodos foram comparados em relação aos fatores que podem influenciar o resultado, servindo de base para futuros estudos de compatibilidade química. A conclusão é que, quando se utilizam os métodos DSC e TG, os sistemas HMX - Al, HMX - Viton e RDX - Viton são compatíveis, porém o sistema RDX - Al apresenta um grau de incompatibilidade. Entretanto, todos são compatíveis quando se utiliza o método da estabilidade química a vácuo.
25

Transformation de matériaux énergétiques par oxydation hydrothermale : Etude cinétique globale et simulation du procédé en régime permanent sur des composés modèles

Mateos, David 01 December 2003 (has links) (PDF)
Les procédés d'oxydation hydrothermale en milieu fluide supercritique offrent une alternative innovante à la gestion des matériaux énergétiques en "fin de vie" et des rebus de production. Afin d'évaluer et de promouvoir le développement de cette technologie, deux pilotes d'oxydation hydrothermale ont été mis en place. Le premier fonctionne en mode fermé et utilise un réacteur chemisé titane. Il est dédié aux études de faisabilité sur des produits réels tels que des propergols et les différents éléments qui les composent (liants, charges énergétiques...). Le second quant a lui fonctionne en mode continu et utilise un nouveau concept de réacteur permettant une multi injection d'oxygène le long du réacteur d'oxydation hydrothermal. Il est dédié à la détermination des données nécessaires au dimensionnement des réacteurs industriels. Des molécules modèles telles que l'acide acétique, le méthanol et le phénol ont été étudiés. Une méthode de calcul a été développée et validée afin d'accéder aux grandeurs cinétiques et notamment à l'ordre par rapport à la concentration en oxygène dans la loi de vitesse globale d'oxydation hydrothermale. Sur la base des données cinétiques obtenues, nous avons validé le logiciel de génie des procédés, Prosim Plus, pour simuler le procédé d'oxydation hydrothermale.
26

Molecular Simulations of Adsorption and Diffusion in Metal-Organic Frameworks (MOFs)

Xiong, Ruichang 01 May 2010 (has links)
Metal-organic frameworks (MOFs) are a new class of nanoporous materials that have received great interest since they were first synthesized in the late 1990s. Practical applications of MOFs are continuously being discovered as a better understanding of the properties of materials adsorbed within the nanopores of MOFs emerges. One such potential application is as a component of an explosive-sensing system. Another potential application is for hydrogen storage. This work is focused on tailoring MOFs to adsorb/desorb the explosive, RDX. Classical grand canonical Monte Carlo (GCMC) and molecular dynamic (MD) simulations have been performed to calculate adsorption isotherms and self-diffusivities of RDX in several IRMOFs. Because gathering experimental data on explosive compounds is dangerous, data is limited. Simulation can in part fill the gap of missing information. Through these simulations, many of the key issues associated with MOFs preconcentrating RDX have been resolved. The issues include both theoretical issues associated with the computational generation of properties and practical issues associated with the use of MOFs in explosive-sensing system. Theoretically, we evaluate the method for generating partial charges for MOFs and the impact of this choice on the adsorption isotherm and diffusivity. Practically, we show that the tailoring of an MOF with a polar group like an amine can lead to an adsorbent that (i) concentrates RDX from the bulk by as much as a factor of 3000, (ii) is highly selective for RDX, and (iii) retains sufficient RDX mobility allowing for rapid, real time sensing. Many of the impediments to the effective explosive detection can be framed as shortcomings in the understanding of molecule surface interactions. A fundamental, molecular-level understanding of the interaction between explosives and functionalized MOFs would provide the necessary guidance that allows the next generation of sensors to be developed. This is one of the main driving forces behind this dissertation. Another important achievement in this work is the demonstration of a new direction for tailoring MOFs. A new class of tailored MOFs containing porphyrins has been proposed. These tailored MOFs show greater capability for hydrogen storage, which also demonstrated the great functionalization of MOFs and great potential to serve as preconcentrators. The use of a novel multiscale modeling technique to develop equations of state for inhomogeneous fluids is included as a supplement to this dissertation.
27

BIODEGRADATION OF THE ENERGETIC COMPOUNDS TNT, RDX AND HMX IN FLUIDIZED-BED AND ACTIVATED SLUDGE REACTORS

DAVEL, JAN L. 24 January 2003 (has links)
No description available.
28

Trace amount analysis of common explosives in bodies of water using UHPLC-HRMS Orbitrap

Olsson, Felix January 2024 (has links)
Topical inquiries for the Swedish Defence Research Agency (FOI) include analysis of explosive substances in different sample types. Research into explosives in complex matrixes can provide an analytical support function for forensic investigation i.e. tools for areas such as finding bomb factories, identification and risk analysis of home-made explosives (HME) and improvised explosive devices (IED) as well as preventive measures against maliciously intended use of explosives. Additionally, the research may lay the groundwork for indications of health- and environmental hazards. Utilizing state-of-the-art equipment and years of extensive expertise, FOI is able to carry out these types of research tasks to provide security and sustainability for society. The aim of this thesis project is to establish and validate developed methods for collecting, extracting, separating, and detecting trace amounts of explosives in various bodies of water using a solid-phase extraction (SPE) robot and a high-resolution (HR) mass spectrometer (MS) connected to an ultra-high-performance liquid chromatograph (UHPLC). Particular areas of interest include locations in the Stockholm archipelago where experimental detonations of explosives have taken place. Overall, UHPLC-HRMS analysis provides a powerful tool for analyzing explosives in complex matrixes with unambiguous and reliable measurement data. The compounds of investigation were hexogen (RDX), octogen (HMX), pentyl (PETN), and trotyl (TNT). To summarize, during the course of the thesis, trace amounts of some explosives were detected and quantified in various bodies of water. Furthermore, the applied method for the project was successful in qualitatively and quantitatively analyze the compounds of interest with limit of detection ranging between 0.33–11 μg/L (ppb) in various water sources.
29

Protein Phosphatase 1 Concentrates at the Base of Sensory Hair Cell Stereocilia, Where it May Function in Stereocilia Cytoskeletal Structure

Gomez, Salvador Gustavo 04 December 2019 (has links)
No description available.
30

Détection de matériaux énergétiques dans les eaux naturelles souterraines par spectroscopie de résonance des plasmons de surface portable

Granger, Genevieve 03 1900 (has links)
Au cours des dernières années, les matériaux énergétiques, tels que le 2,4,6-trinitrotoluène (TNT) et le 1,3,5-trinitro perhydro-1,3,5-triazine (RDX), ont été utilisés lors des activités d’entrainement militaire, ayant un impact potentiel sur l’environnement, les bases militaires, la population environnante, la faune et la flore. Sur les champs de tir, les sols à proximité des cibles et autour des positions de tir nécessitent une surveillance particulière, puisqu’il est possible de trouver une importante quantité de résidus d’explosif qui peuvent être transportés vers les eaux de surface et des eaux souterraines avec les précipitations. Toutefois, la procédure actuelle pour détecter des matériaux énergétiques dans l'eau naturelle est complexe, longue, nécessite un personnel hautement spécialisé et augmente le risque de contamination croisée. Par conséquent, il est difficile d'assurer un contrôle rapide et continu des contaminants. En fait, l'objectif des travaux présentés dans ce mémoire est de développer une technique pour identifier et quantifier les explosifs et leurs produits de dégradation dans les eaux naturelles. En outre, ce test doit être in situ, en continu, peu coûteux et rapide. La résonance des plasmons de surface (SPR) a été donc utilisée pour quantifier les matériaux énergétiques. Une matrice de bis-aniline réticulée avec des nanoparticules d’or (AuNPs) est utilisée en tant que polymère à empreinte moléculaire (MIP) sur le film d'or pour capturer sélectivement le composé d’intérêt. L'association de la molécule d’intérêt, tel que le TNT ou RDX, au MIP par interactions π-donneur-accepteur permet la détection d'explosifs suite aux changements d’indice de réfraction sur la sonde. Le couplage entre les plasmons des AuNPs et de la couche d'or peut également augmenter les signaux SPR. Le test optimisé a ensuite été utilisé sur une base militaire canadienne. L'utilisation de cet essai à base de MIP fournit un outil pour l'extraction et la pré-concentration de TNT ou RDX à la surface d’une sonde SPR et permet leur détection en continu de faibles concentrations dans les eaux naturelles. / Over the last few years, energetic materials such as 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) have been used and show a probable environmental impact on military bases, the surrounding population, fauna and flora, caused by military training involving munitions. On shooting ranges, soils near the firing positions and around targets require special monitoring, since the quantities of explosives residues found can be significant, and these compounds can be transported to surface water and groundwater by precipitation. However, the current procedure to detect energetic materials in natural water is complex, long and poorly adapted to. These operations require highly specialized personnel and increase the risk of cross contamination. Therefore, it is difficult to ensure a fast and continuous monitoring of the contaminants. Here, the objective is to develop a technique for identifying and quantifying explosives and their degradation products in natural water. Also, this test has to be in-situ, inexpensive and fast. Surface plasmon resonance (SPR) has been proposed to probe energetic materials. A bis-aniline-cross-linked gold nanoparticles (AuNPs) matrix is used as a molecular imprinted polymer (MIP) on gold film to selectively capture the target compound. The association of the target such as TNT or RDX to the MIP with π-donor-acceptor interactions have allow the detection of explosives by following SPR refractive changes. Plasmon coupling effects between the AuNPs and the gold film could also increase the SPR signals. The optimal sensor was then used on site to detect RDX in underground water of a Canadian military base. The utilisation of MIP based assay will provide a tool for the extraction and pre-concentration of TNT or RDX on the detector’s surface and will allow the detection of lower concentrations in natural water.

Page generated in 0.1402 seconds