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Dissertations / Theses on the topic 'Energetický materiál'
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1
Slovák, Jiří. "Implementace algoritmu pro měření parametrů energetických materiálů v obvodu FPGA." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220352.
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In the text of the master´s thesis, it is at first briefly referred about Energetic Material Measurement topic in general. Emphasis is placed especially at the description of the Velocity of Detonation and short analysis of selected measurement method. The most significant part of the paper is dedicated to the design and description of the system that was created in ISE Design Suite environment using VHDL language. The development was performed with respect to oncoming integration into the board with FPGA and A/D converters. The operation of detection algorithm which was created based on the MATLAB model was verified in the final part of the thesis by simulation of processing of real optical probe signals.
2
Křištof, Adam. "Energetické materiály na bázi nitramidů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-216660.
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Homolytic dissociation of the N-NO2 bond represents primary fission process of energetic materials under the influence of heat, impact, vibration and electric spark. The fission of nitramide bonds is characterized by homolytic bond dissociation energy BDE(RCON-NO2) or disproportionation bond energy DISP(RCON-NO2), which is expressed by an isodesmic reaction RCON-NO2 + SCON-H › RCON-H + SCON NO2, where SCON NO2 is a standard nitramide (1-nitropiperidin-2-on, NPO). This kind of virtual chemical calculation cancels the effect of electron correlation, accompanying the theoretical calculations of free radicals. In this thesis, the homolytic dissociation bond energy BDE(RCON-NO2) and disproportionation bond energy DISP(RCON-NO2) were evaluated for 13 cyclic nitramides using the DFT B3LYP/6-311+G(d,p) method and at the same time the total charges of corresponding nitro groups Q(NO2) were calculated by DFT B3LYP/6-31G(d,p) method. The evaluated BDE and DISP energies were correlated with detonation parameters as squares of detonation velocities and detonation heats. The resulting relationships allow a more detailed description of dependence between the molecular structure of evaluated nitramides and their explosive properties.
3
Bartošková, Monika. "Termochemické vlastnosti vysokodusíkatých energetických materiálů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2015. http://www.nusl.cz/ntk/nusl-234452.
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The main goal of the presented thesis is a theoretical study of heat of formation for high-nitrogen energetic materials. A modification of the classical approach to the isodesmic reactions is realized with the intent that molecules on both sides of the corresponding equation have not only the same number of atoms but also approximately the same size and skeletal similarity. This approach is designated as a method "Alternative Isodesmic Reaction (AIR method)". At its base, using the DFT B3LYP / cc-pVTZ and B3PW91 / cc-pVTZ, for the high nitrogen heterocycles, which are selected from the group of triazoles, triazines, tetrazines, the enthalpy of formation values the gaseous phase f H°(298,g), were obtained whose values are close to the published f H°(298,g). Their application in the calculation of the relevant characteristics of these heterocycles detonation gave real values.
4
Piercey, Davin Glenn. "Advanced energetic materials." Diss., lmu, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-153895.
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Miró, Sabaté Carlos Hector. "Azole-based energetic materials." Diss., lmu, 2008. http://nbn-resolving.de/urn:nbn:de:bvb:19-99477.
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Welch, Jan. "Low sensitivity energetic materials." Diss., kostenfrei, 2008. http://edoc.ub.uni-muenchen.de/8495/.
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Boddy, Rachael Louise. "Damage in energetic materials." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708696.
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Sehnal, Dominik. "Nízkocyklová životnost v podmínkách jaderné energetiky." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-399581.
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Fatique life extension of nuclear powerplants lies in the search for project reserves. This work deals with the evaluation of low-cycle fatigue of nuclear installations of the VVER type and the assessment of the influence of the computational model level. Fatigue tests of austenitic steel using optical method of digital image correlation for which the evaluation procedure is designed and used is performed. Selected model of plasticity with kimenatic (Chaboche) and combinated hardening (Chaboche, Voce) are calibrated from the obtained data. Subsequently, the durability of the test specimen is determined by computational modeling for different material models. From the comparison of the results of fatigue tests with the calculation, the material models suitable for the description of fatigue life and their validity are determined.
9
Schlosser, Radek. "Studium katalytické aktivity keramických perovskitových materiálů pro energetické aplikace." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229408.
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In this diploma thesis the preparation of ceramic catalytic materials was studied. They were studied by means of catalytic activity on powder samples and in a form of membrane as well. At first were multicomponent perovskite materials with the help of “glycine-nitride synthesis” synthesized. Two types of perovskite systems were prepared. First system was on the basis of nickelates LaNiO3 and the second one on the basis of cobaltites SmCoO3. Both of them were doped with aluminium and calcium. Ceramic powders were catalytic tested during reformed reaction. A part of powders was pressed with hydraulic biaxial press. Then the membranes were calcinated, sintered and polished. The membranes were tested to specify the catalytic activity. At first they were in hydrogen atmosphere reduced and afterwards came through the partial oxidation. The appearance of coke fibers on the surface was discussed.
10
Saraf, Sanjeev R. "Molecular characterization of energetic materials." Texas A&M University, 2003. http://hdl.handle.net/1969.1/331.
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Assessing hazards due to energetic or reactive chemicals is a challenging and complicated task and has received considerable attention from industry and regulatory bodies. Thermal analysis techniques, such as Differential Scanning Calorimeter (DSC), are commonly employed to evaluate reactivity hazards. A simple classification based on energy of reaction (-H), a thermodynamic parameter, and onset temperature (To), a kinetic parameter, is proposed with the aim of recognizing more hazardous compositions. The utility of other DSC parameters in predicting explosive properties is discussed.
Calorimetric measurements to determine reactivity can be resource consuming, so computational methods to predict reactivity hazards present an attractive option. Molecular modeling techniques were employed to gain information at the molecular scale to predict calorimetric data. Molecular descriptors, calculated at density functional level of theory, were correlated with DSC data for mono nitro compounds applying Quantitative Structure Property Relationships (QSPR) and yielded reasonable predictions. Such correlations can be incorporated into a software program for apriori prediction of potential reactivity hazards. Estimations of potential hazards can greatly help to focus attention on more hazardous substances, such as hydroxylamine (HA), which was involved in two major industrial incidents in the past four years. A detailed discussion of HA investigation is presented.
11
Millar, David Iain Archibald. "Energetic materials at extreme conditions." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/8213.
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In order to effectively model the behaviour of energetic materials under operational conditions it is essential to obtain detailed structural information for these compounds at elevated temperature and/or pressures. The structural characterisation of the high explosives RDX and CL-20 and a series of inorganic azides [Mn+(N3)n] at extreme conditions is described herein. In addition to the characterisation of a highly metastable β -form of RDX (1,3,5- trinitrohexahydro-1,3,5-triazine) at atmospheric pressure, the structure solution of a high-pressure/ high-temperature polymorph is described. This form, obtained above 4.3 GPa and 450 K, has been shown to be distinct from the β -form and has therefore been denoted - RDX. Furthermore, ε -RDX is sufficiently metastable to allow its recovery to ambient pressure at 150 K; it only transforms to the α -form upon warming to 230 K. Finally, the ambient-temperature compression of RDX has been investigated to a maximum pressure of 23.0 GPa, using methanol:ethanol (4:1) as the pressure-transmitting medium; no phase transition was observed under these conditions, other than the α → γ transition at 3.9 GPa. The structure of a high-pressure polymorph of CL-20 (2,4,6,8,10,12- hexanitrohexaazaisowurtzitane) has also been determined by a combination of powder and single-crystal X-ray diffraction. Compression of γ -CL-20 to above 0.7 GPa using Fluorinert (FC-77) as the pressure-transmitting medium results in a phase transition to the ζ -form, which has been found to display structural similarities with both theγ γ - and ε -forms. The high-pressure behaviour of CL-20, however, depends markedly on the starting polymorph and the pressure-transmitting medium selected. Compression of γ -CL-20 in MeOH:EtOH (4:1) results in the formation of a 2:1 CL-20:MeOH solvate at 0.5 GPa. This solvate is stable upon compression to P > 5.0 GPa. It may also be recovered to ambient pressure at 293 K. Meanwhile, no phase transition is observed during the compression of ε -CL-20 to a maximum pressure of 7.2 GPa. Finally, a series of inorganic azides [NaN3, CsN3, TlN3, NH4N3, AgN3 and Pb(N3)2] has been characterised under a range of pressure and temperature conditions. Of the six compounds studied, all displayed at least one polymorphic transition – 5 new forms have been structurally characterised in this work and evidence of another 5 is presented. The combined effect of pressure and temperature results in sodium azide adopting a tetragonal structure common to larger alkali metal azides. Caesium azide has been shown to undergo three phase transitions during compression to 6.0 GPa – the structure of the first high-pressure form is reported. A variable temperature X-ray powder diffraction study of TlN3 has allowed the structural characterisation of the low-temperature TlN3-IV (at 230 K) as well as providing evidence for a phase transition to a high-temperature form above 550 K. The high-pressure form III (obtained above 0.76 GPa) has also been determined by neutron powder diffraction. Silver, ammonium and lead(II) azides have all been shown to undergo a phase transition at high pressures. Compression of silver azide (P > 0.80 GPa) removes an orthorhombic distortion observed at atmospheric pressure, resulting in the tetragonal structure adopted by CsN3 and TlN3 under ambient conditions. Moreover, NH4N3 and Pb(N3)2 have been found to undergo phase transitions at 2.6 GPa, although their high-pressure structures have still to be determined.
12
Diodati, Giulia. "Realizzazione e caratterizzazione di materiali polimerici elettroattivi per lo sviluppo di un sistema di pavimentazione a recupero energetico." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Il presente lavoro di tesi è stato svolto presso il Dipartimento di Ingegneria dell’Energia Elettrica e dell’Informazione “Guglielmo Marconi” della Facoltà di Ingegneria dell’Università di Bologna, nel Laboratorio di Innovazione Tecnologica.
Le attività svolte si sono focalizzate sulla realizzazione e caratterizzazione di materiali polimerici elettroattivi al fine di sviluppare un prototipo di pavimentazione a recupero energetico, cioè in grado di generare energia elettrica in seguito alla sollecitazione meccanica del passo umano. Questa tecnologia è un idea innovativa e rientra nella più ampia materia dell’Energy Harvesting, cioè lo studio di soluzione alternative in grado di sfruttare fonti di energia che altrimenti andrebbero dissipate, come appunto il calpestio umano.
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Kleinbauer, Jan. "Energetická bezpečnost EU." Master's thesis, Vysoká škola ekonomická v Praze, 2011. http://www.nusl.cz/ntk/nusl-149864.
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Shortening supply of strategic raw materials (mostly oil and gas) and increasing demand for these energy raw materials in fast-growing Asian economies caused EU to put energy security among its top interests. The key goal of this thesis is to propose possibilities to increase energy security of the EU so that Europe has continuous and stable energy supplies both from its own sources and from import. I will analyze the current state of EU energy security in the first part of the thesis. I will focus on using EU's own resources and assess the benefits and drawbacks of using renewable energy sources compared to traditional sources. Then I will analyze dependency of EU on energy import and describe particularities and risks of current suppliers. The second part of the thesis will be focused on increasing energy security of the EU. Could the common energetic policy strengthen the energy security? I will also focus on possibilities of supplier and energy sources diversification. Last but not least, I will examine the topic of energetic savings and its impact on energy security.
14
Chiarotti, Nicola. "Determinazione sperimentale delle perdite di carico di efflussi forzati di aria in schiume metalliche di elevata porosità." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17854/.
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Le schiume metalliche, grazie alle loro peculiari proprietà di alta porosità e alto rapporto superficie su volume, possiedono, ad oggi, diverse applicazioni industriali. La caratterizzazione di questi materiali porosi è di importanza critica per l’adattamento di questi materiali alle esigenze applicative desiderate. Per modificarne il campo d’applicazione, è fondamentale conoscere i parametri descrittivi delle schiume metalliche, e per realizzare ciò è necessario conoscerne e quantificarne il comportamento fluidodinamico, con particolare riferimento alle perdite di carico. In questo studio è stata posta maggiore attenzione su un certo tipo di schiume metalliche, caratterizzate da un’elevata porosità e di spessore variabile
I risultati ottenuti, mostrano che il gradiente lineare di perdita di carico cala all’aumentare dello spessore, divenendo costante dopo un certo limite, definibile spessore critico, per effetto della diminuzione del contributo degli effetti di entrata ed uscita del fluido dalle schiume metalliche, che contribuiscono all’incremento delle perdite di carico. All’aumentare dello spessore, con particolare riferimento a spessori maggiori dello spessore critico, si è anche notata una minore dispersione dei risultati sperimentali, fino all’inclusione entro le barre d’incertezza dei dati sperimentali. Una seconda parte dello studio ha esplorato le inconsistenze derivanti dall’utilizzo di alcuni parametri fluidodinamici, quali k ed f, per la caratterizzazione delle schiume metalliche, da cui scaturisce una notevole variabilità fra i risultati sperimentali osservabili nella letteratura scientifica disponibile. La conclusione alla quale si è addivenuti è che l’appartenenza ad uno specifico regime di moto del fluido, ben al di fuori del regime ottimale per l’estrapolazione del parametro di permeabilità k, ricade sui valori estrapolati, manifestandosi in forma di un’enorme dispersione dei risultati.
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Urbinati, Sofia. "Analisi Energetica in un'azienda di fabbricazione di articoli in materie plastiche." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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Questo lavoro di tesi nasce dal periodo di tirocinio effettuato presso la società di consulenza energetica Energika S.r.l. e dallo specifico caso studio di una delle aziende in consulenza presso la società. Lo stabilimento, che si occupa principalmente di stampaggio di materie plastiche, ha richiesto lo svolgimento di una Diagnosi Energetica per assolvere i compiti dell’obbligatorietà derivanti dal Decreto Legislativo n°102 del 4 luglio 2014. Lo stabilimento risulta infatti tra i soggetti obbligati a causa dell’incidenza degli assorbimenti.
Nel corso dell’elaborato vengono analizzate inizialmente le principali direttive europee inerenti al concetto di efficienza energetica, in particolare la direttiva 2012/27/EU ed il suo recepimento nella legislazione italiana. Successivamente, dopo aver introdotto i principali processi di lavorazione delle materie plastiche, e gli indicatori di prestazione caratteristici di questo settore individuando dei valori di benchmark viene riportato lo stato dell’arte delle migliori pratiche di efficienza energetica disponibili in letteratura.
Il corpo del lavoro è costituito dall'analisi di uno specifico caso studio per cui sono stati raccolti dati di consumo e di produzione con dettaglio mensile. Per lo specifico caso studio è stato prima descritto il processo produttivo, la situazione dell’azienda al momento del sopralluogo, e poi è stata effettuata un’accurata analisi degli indicatori di prestazione energetica, ricavando il consumo specifico di energia generale e dove possibile il consumo specifico di energia per attività principale, espressi in kWh/kg.
Sono infine stati valutati alcuni interventi di efficientamento energetico.
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Strejček, Josef. "Studium syntézy a struktury keramických perovskitových materiálů pro energetické aplikace." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229301.
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Method, so called “glycin- nitrate process”, combined with high temperature solid state reaction, of preparation multi- component ceramic perovskite materials was studied. Two types of perovskite systems were prepared by this method. Firs one, based on LaNiO3 doped by calcium and aluminium and second one, based on SmFeO3 doped by calcium and nickel or cobalt. This method made possible preparation of one phase perovskite or perovskites with few percent of nickel in form of oxide. In systems containing both nickel and calcium another phases rich in calcium and nickel appeared.
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Szlaur, Vít. "Analýza procesů obrábění kovových materiálů se zaměřením na energetické aspekty." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230098.
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A general analysis of machining problems, analysis of cutting forces for turning, milling, drilling. Evaluation of experimentally measured values of surface structure and theoretical values of cutting forces in turning cylindrical parts. Economical processes for the comparable results of the final state of the surface.
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Conroy, Michael W. "First-principles studies of energetic materials." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002276.
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Davidson, Alistair J. "High-pressure studies of energetic materials." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/16976.
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Although high pressure has been used extensively to study a range of materials that include metals, minerals, and ices, a class of material that has received rather less attention is energetic materials (explosives, propellants). The work presented has used high-pressure techniques to investigate polymorphism in energetic materials. Novel-high pressure phases of RDX (cyclotrimethylenetrinitramine or cyclonite) and ammonium perchlorate are reported, which have both been structurally characterised using single-crystal X-ray and powder neutron diffraction. Of particular importance has been the successful determination of the structure of the elusive high-pressure –form of RDX. Equations of state for both polymorphs of both compounds have been determined. High-pressure measurements of HMX (cyclotetramethylenetetranitramine or octogen) revealed no phase transitions up to 8.46 GPa. An equation of state up to this pressure has been determined. Crystallisation of HMX from DMSO at 0.1 GPa gives a 1:2 HMX-DMSO solvate which has been structurally characterised by single-crystal X-ray diffraction. The high-pressure behaviour of TATP (triacetone triperoxide) has been explored. Hydroxylammonium perchlorate has been investigated using high-temperature single-crystal X-ray diffraction and powder neutron diffraction, and a high-temperature phase has been fully structurally characterised for the first time. High-pressure studies of hydroxylammonium perchlorate indicate the presence of two new polymorphs. High-pressure measurements have been conducted on ammonium nitrate up to 7.85 GPa, showing no phase transitions. An equation of state has been determined over this pressure range. Studies have also been undertaken on the simple molecular compound thiourea dioxide. Two new high-pressure phases have been identified and structurally characterised using both single-crystal X-ray and powder neutron diffraction.
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Melin, Pontus. "Atomistic Modeling of Amorphous Energetic Materials." Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-359778.
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A majority of research within the field of energetic materials have been centered around the stable crystalline phase, whilst there has been less about the amorphous phase and the implications of these types of material. In this study, Molecular Dynamics simulations with the General Amber Force Field (GAFF) is used to predict fundamental properties of the nitramine explosives HMX and CL-20 in the amorphous phase. Amorphous structures are obtained by compressing a molecular gas to 4 GPa followed by relaxation and equilibration. The simulations indicate that the amorphous phases of HMX and CL-20 have lower densities than the corresponding crystal phases, 12.7% and 7.3% respectively. Both HMX and CL-20 was found to compress more easily when subject to external pressure, the difference was most significant for HMX.As a second part of this study an amorphous composition of CL-20/HMX/Polyvinylacetate(PVAc) (50/45/5 -wt%) was studied. This was obtained by compressing a molecular gas to varying pressures followed by relaxation and equilibration. Results indicate that the simulated density around 1.64 [g/cm3 ] fall close to experimental observations of 1.7 [g/cm3 ]. The density was observed to not vary significantly for pressures higher than 0.4 [GP a] in accordance to experimental data.
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Goveas, Stephen George. "The laser ignition of energetic materials." Thesis, University of Cambridge, 1997. https://www.repository.cam.ac.uk/handle/1810/272508.
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Harding, Philip H. "The energetics of adhesion in composite materials /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/9819.
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Göbel, Michael. "Energetic Materials Containing The Trinitromethyl Pseudohalide Functionality." Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-124207.
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Stierstorfer, Jörg. "Advanced Energetic Materials Based on 5-Aminotetrazole." Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-129940.
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Conroy, Michael W. "Density Functional Theory Studies of Energetic Materials." Scholar Commons, 2009. http://scholarcommons.usf.edu/etd/3691.
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First-principles calculations employing density functional theory (DFT) were
performed on the energetic materials PETN, HMX, RDX, nitromethane, and a recently
discovered material, nitrate ester 1 (NEST-1). The aims of the study were to accurately
predict the isothermal equation of state for each material, improve the description of these
molecular crystals in DFT by introducing a correction for dispersion interactions, and
perform uniaxial compressions to investigate physical properties that might contribute to
anisotropic sensitivity.
For each system, hydrostatic-compression simulations were performed. Important
properties calculated from the simulations such as the equilibrium structure, isothermal
equation of state, and bulk moduli were compared with available experimental data to
assess the agreement of the calculation method. The largest contribution to the error was
believed to be caused by a poor description of van der Waals (vdW) interactions within
the DFT formalism.
An empirical van der Waals correction to DFT was added to VASP to increase
agreement with experiment. The average agreement of the calculated unit-cell volumes
for six energetic crystals improved from approximately 9% to 2%, and the isothermal
EOS showed improvement for PETN, HMX, RDX, and nitromethane. A comparison was
made between DFT results with and without the vdW correction to identify possible
advantages and limitations.
Uniaxial compressions perpendicular to seven low-index crystallographic planes
were performed on PETN, HMX, RDX, nitromethane, and NEST-1. The principal
stresses, shear stresses, and band gaps for each direction were compared with available
experimental information on shock-induced sensitivity to determine possible correlations
between physical properties and sensitivity. The results for PETN, the only system for
which the anisotropic sensitivity has been thoroughly investigated by experiment,
indicated a possible correlation between maximum shear stress and sensitivity. The
uniaxial compressions that corresponded to the greatest maximum shear stresses in HMX,
RDX, solid nitromethane, and NEST-1 were identified and predicted as directions with
possibly greater sensitivity. Experimental data is anticipated for comparison with the
predictions.
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Ward, Daniel W. "Tailoring the physical properties of energetic materials." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/29531.
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Energetic materials are a class of material that have large amounts of chemical energy stored within their molecular structure. This energy is released upon decomposition, generally in the form of rapidly expanding, hot gases. They are therefore used for a wide range of applications such as; mining, military, and space exploration, and there is therefore a strong desire to improve the overall performance and safety of such materials. On account of reduced sensitivity to initiation by shock and impact, 2,4-dinitroanisole (DNAN) is a potential replacement for 2,4,6-trinitrotoluene (TNT) in melt-cast formulations for military applications. However, up to 15 % irreversible growth of DNAN has been previously observed upon thermal cycling and is a key reason why DNAN has not yet been universally accepted as a replacement for TNT. DNAN exhibits a complex system of polymorphism. One particular transition from DNAN-II to DNAN-III, which occurs at 266 K, has been observed in these studies to cause 8 - 10 % growth of DNAN-II pellets when temperature cycled for 30 cycles between 256 K and 276 K. What was even more concerning was the appearance of cracking of DNAN pellets after being temperature cycled. Doping the crystal structure of DNAN-II with related molecules, such as 2,4-dinitrotoluene or 2,4-dinitroaniline, was investigated in order to probe how steric and electronic factors affect the transition. The addition of varying amounts of 2,4-dinitroaniline suppressed this transition to varying extents and ultimately as low as 150 K with 10 mol% 2,4-dinitroaniline, and potentially eliminated entirely. This doped material has been designated as phase-stabilised DNAN (PS-DNAN). Temperature cycling of PS-DNAN was conducted over the same 256-276 K range, and this material showed no evidence of irreversible growth compared to undoped DNAN pellets, on account of suppression of the II-III transition. The production of PS-DNAN is therefore a possible route to avoiding problematic irreversible growth in DNAN formulations. Melt-casting of DNAN in a sealed environment consistently results in the metastable form-II, which has proven to be stable for in excess of 32 weeks. However, exposure to seeds of form-I, either via deliberate or accidental seeding, rapidly converted the material to the thermodynamically more stable form-I. This transition was accelerated by increasing temperature which rapidly converted pellets of DNAN-II to DNAN-I. When DNAN-I pellets were temperature cycled, they did not undergo a transition to form-III, and as a result did not illustrate irreversible growth. This presents another approach to avoiding problematic growth in DNAN-based materials. Whilst being one of the most widely used oxidisers in propellant formulations, ammonium perchlorate (AP) has several issues; the formation of porous ammonium perchlorate (PAP) can seriously affect the sensitivity of propellants, the hygroscopicity of AP makes handling and manufacture of formulations difficult, and spherical AP exhibits poor binding properties to the polymer binders used in propellant formulations. Several different approaches were taken to combat these issues. Co-crystallisation of AP was attempted in order to produce new AP co-crystals with reduced reactivity towards the formation of PAP. A theoretical based approach using COSMOtherm was used for rapid screening and selection of potential co-formers to be used in lab-based co-crystallisation trials. Co-crystallisation was attempted using multiple stoichiometries and multiple solvents by solvent evaporation, cooling crystallisation, and Resonant Acoustic Mixing methods. Unfortunately no new co-crystals were obtained, presumably on account of the ionic nature of AP which makes co-crystallisation difficult. The mass of untreated AP increased by 0.027% in a humid environment (90% RH) due to the uptake of water, which resulted in significant caking and hence hindering the processability of AP. In an attempt to counteract the hygroscopicity and improve the processability of AP, particles of AP were coated in graphene nanoplatelets using the technique of Resonant Acoustic Mixing. Low mixing energy (G-force) (30 G) resulted in poor coating of AP, but the flowability of this mixure after exposure to moisture was significantly enhanced, most probably as a result of graphene acting as an effective lubricant. Higher mixing energy (90-100 G) was required to break up agglomerates of graphene nanoplatelets and resulted in AP particles efficiently coated with graphene (APGR). Differential scanning calorimetry showed that the energy released upon decomposition of APGR was greater than pure AP, or AP mixed with graphene, due to the intimacy of the AP particle surface and the graphene coating.
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Landerville, Aaron Christopher. "First-Principles Atomistic Simulations of Energetic Materials." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5056.
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This dissertation is concerned with the understanding of physico-chemical properties of energetic materials (EMs). Recently, a substantial amount of work has been directed towards calculations of equations of state and structural changes upon compression of existing EMs, as well as elucidating the underlying chemistry of initiation in detonating EMs. This work contributes to this effort by 1) predicting equations of state and thermo-physical properties of EMs, 2) predicting new phases of novel EMs, and 3) examining the initial stages of chemistry that result in detonation in EMs. The motivation for the first thrust, is to provide thermodynamic properties as input parameters for mesoscale modeling. Such properties are urgently sought for a wide range of temperatures and pressures, and are often difficult or even impossible to obtain from experiment. However, thermo-physical properties are obtained by calculating structural properties and vibration spectra using density function theory and employing the quasi-harmonic approximation. The second thrust is directed towards the prediction and investigation of novel polymorphs of known azide compounds to identify precursor materials for synthesis of polymeric nitrogen EMs. Structural searches are used to identify new polymorphs, while theoretical Raman spectra for these polymorphs are calculated to aid experimentalists in identifying the appearance of these azide compounds under high pressure. The final thrust is concerned with elucidating the initial chemical events that lead to detonation through hypervelocity collision simulations using first-principles molecular dynamics. The chemical mechanisms of initiation are determined from the atomic trajectory data, while heats of reaction are calculated to quantify energy trends of chemical transformations.
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Aydelotte, Brady Barrus. "Fragmentation and reaction of structural energetic materials." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50253.
Full textAbstract:
Structural energetic materials (SEM) are a class of multicomponent materials which may react under various conditions to release energy. Fragmentation and impact induced reaction are not well characterized phenomena in SEMs. The structural energetic systems under consideration here combine aluminum with one or more of the following: nickel, tantalum, tungsten, and/or zirconium. These metal+Al systems were formulated with powders and consolidated using explosive compaction or the gas dynamic cold spray process.
Fragment size distributions of the indicated metal+Al systems were explored; mean fragment sizes were found to be smaller than those from homogeneous ductile metals at comparable strain rates, posing a reduced risk to innocent bystanders if used in munitions. Extensive interface failure was observed which suggested that the interface density of these systems was an important parameter in their fragmentation. Existing fragmentation models for ductile materials did not adequately capture the fragmentation behavior of the structural energetic materials in question. A correction was suggested to modify an existing fragmentation model to expand its applicability to structural energetic materials. Fragment data demonstrated that the structural energetic materials in question provided a significant mass of combustible fragments. The potential combustion enthalpy of these fragments was shown to be significant.
Impact experiments were utilized to study impact induced reaction in the indicated metal+Al SEM systems. Mesoscale parametric simulations of these experiments indicated that the topology of the microstructure constituents, particularly the stronger phase(s), played a significant role in regulating impact induced reactions. Materials in which the hard phase was topologically connected were more likely to react at a lower impact velocity due to plastic deformation induced temperature increases. When a compliant matrix surrounded stronger, simply connected particles, the compliant matrix accommodated nearly all of the deformation, which limited plastic deformation induced temperature increases in the stronger particles and reduced reactivity. Decreased difference between the strength of the constituents in the material also increased reactivity. The results presented here demonstrate that the fragmentation and reaction of metal+Al structural energetic materials are influenced by composition, microstructure topology, interface density, and constituent mechanical properties.
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Hlavsa, Tomáš. "Tvorba konceptu energeticky soběstačných obytných budov." Doctoral thesis, Vysoké učení technické v Brně. Fakulta architektury, 2018. http://www.nusl.cz/ntk/nusl-355648.
Full textAbstract:
Creating the concept of buildings is the primary task of architects, designers in the field of architecture and engineering. Although the basic requirements remain the same across time , possibilities of their solution are constantly evolving and changing. In addition, with the increasing globalization, in context of the housing and the architecture is expected new requirements go beyond the horizons of the interests of bouth investor and designer. Global view of each project and the evaluation of its traces left in our environment and society, although is much discussed but rarely taken into account or even just considered. In this context, we are witnessing the development of new trends of the concepts of buildings, consisting in the use of natural materials, in reducing the environmental burden of a surroundings, in reducing energy demands, or even in an effort to achieve energy independence thus trends, whose common denominator is sustainable construction, hence sustainable development in general. Feasibility of the creation of the concept of energy self-sufficient building doesn´t consist only in the precise solution of the assigned task from the perspective of the designer or investor, but also in finding such a solution which, even with using new trends and principles, will not go against the initial idea itself. The present instrument processed and presented in this dissertation has the ambition to move global view of the project into the perspective of a particular individual design process and in small way contribute to the creation of better projects from the perspective of sustainable development The term of energy self-sufficient buildings are not clearly defined. To work with them it was necessary to determine their basic definition that describes their diverse conceptual variations and allows precisely define the solution area. To correctly select the optimal solution in terms of sustainable development is necessary the assessment and mutual comparison since the beginning. As a basic tool for this assessment was used and partially modified SBTool, which is built on three basic pillars of sustainable development - SOCIAL - ENVIRONMENTAL - ECONOMIC. SBTool tries to determine the degree of left traces of the approach from the perspectives of these three aspects and evaluate the effectiveness of the selected solution. This tool allow to compare the different concepts for the same project among themselves, their parts but also various projects among each other. All of course with regard to the development of various aspects in the time.
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Mocová, Pavla. "Optimalizace návrhu energetické renovace školských budov." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-390264.
Full textAbstract:
The dissertation thesis is focused on a methodology of optimal design energy renovation of school buildings. The thesis is focused on the analysis of selected school buildings during the last 100 years of construction in the first phase. At this phase, are found some important information, especially in terms of the energy performance of the building envelope and results of this parts. Last but not least, CO2 emissions were detected. In the next part of this work, one selected school is assessed in terms of the quality of the environment, due to the evaluation of microbial microclimate on building structures, CO2 concentration and daylight. CO2 concentration and classroom daylight is addressed both for the original and for the new state. Another point of this thesis is the appreciation of the size of the classrooms in the schools both in terms of typological principles and in terms of the average size of classrooms. The daylight assessment is performed on these selected sizes, which is a part of the "PaMo I" design tool. In the next phase of the dissertation was created the design tool "PaMo I". This tool solves the evaluation of the renovation of school buildings from the point of view of the thermal engineering in connection with the influence of the daylight illumination on the classrooms of the school buildings by the thickness of the insulation system and the replacement of the windows. Part of the design tool is also the financial quantification of the investment, the payback period and the impact on the environment of the individual variants. The choice of variant options has been used when making a design tool user decision. The result of this work is a design tool which will help in deciding and finding the optimal alternative to the energy renovation of a school building in connection with daylighting inside classrooms.
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Narayanan, Vindhya. "Non-equilibrium Thermomechanics of Multifunctional Energetic Structural Materials." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7570.
Full textAbstract:
Shock waves create a unique environment of high pressure, high temperature and high strain-rates. It has been observed that chemical reactions that occur in this regime are exothermic and can lead to the synthesis of new materials that are not possible under other conditions. The exothermic reaction is used in the development of binary energetic materials. These materials are of significant interest to the energetic materials community because of its capability of releasing high heat content during a chemical reaction and the relative insensitivity of these types of energetic materials. Synthesis of these energetic materials, at nano grain sizes with structural reinforcements, provides an opportunity to develop a dual functional material with both strength and energetic characteristics.
Shock-induced chemical reactions pose challenges in experiment and instrumentation. This thesis is addressed to the theoretical development of constitutive models of shock-induced chemical reactions in energetic composites, formulated in the framework of non-equilibrium thermodynamics and mixture theories, in a continuum scale. Transition state-based chemical reaction models are introduced and incorporated with the conservation equations that can be used to calculate and simulate the shock-induced reaction process. The energy that should be supplied to reach the transition state has been theoretically modeled by considering both the pore collapse mechanism and the plastic flow with increasing yield stress behind the shock wave. A non-equilibrium thermodynamics framework and the associated evolution equations are introduced to account for time delays that are observed in the experiments of shock-induced or assisted chemical reactions. An appropriate representation of the particle size effects is introduced by modifying the initial energy state of the reactants. Numerical results are presented for shock-induced reactions of mixtures of Al, Fe2O3 and Ni, Al with epoxy as the binder.
The theoretical model, in the continuum scale, requires parameters that should be experimentally determined. The experimental characterization has many challenges in measurement and development of nano instrumentation. An alternate approach to determine these parameters is through ab-initio calculations. Thus, this thesis has initiated ab-initio molecular dynamics studies of shock-induced chemical reactions. Specifically, the case of thermal initiation of chemical reactions in aluminum and nickel is considered.
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Reding, Derek James. "Shock induced chemical reactions in energetic structural materials." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28174.
Full textAbstract:
Thesis (M. S.)--Aerospace Engineering, Georgia Institute of Technology, 2009.Committee Chair: Hanagud, Sathya; Committee Member: Kardomateas, George; Committee Member: McDowell, David; Committee Member: Ruzzene, Massimo; Committee Member: Thadhani, Naresh.
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Tang, Shuang Ph D. Massachusetts Institute of Technology. "Materials Physics for Thermoelectric and Related Energetic Applications." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98735.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 118-122).
Thermoelectrics study the direct inter-conversion between heat flow and electrical power, which has a wide range of applications including power generation and refrigeration. The performance of thermoelectricity generation and the refrigeration is characterized by a dimensionless number called the Figure-of-Merit (ZT), defined as ZT = [sigma]-S 2T / [kappa], where a is the electrical conductivity, K is the thermal conductivity, S is the Seebeck coefficient, and T is the absolute temperature. Before 1993, the upper-limit of ZT was barely 1. After the efforts of more than twenty years, the upper-limit of ZT has been pushed up to ~2. However, for the thermoelectric technology to be commercially attractive, the value of ZT and the cost of production have to be further improved. Most of the ZT enhancing strategies that have been proposed since 1993 involve the changing and the controlling of the dimension of materials systems, the scattering mechanism(s) of carriers, the shape of the electronic band structure and the density of states, and the magnitude of the band gap. As further research is carried out, it is found that these strategies do not always work to enhance ZT. Even for a working materials system, the improvement margin of increasing ZT can be small. The balancing between [sigma] and S 2 / [kappa] has significantly limited the improvement margin for our ZT enhancing goal. Therefore, we have two problems to explore: (1) how can we deal with the strong correlation between [sigma] and S2 / [kappa] , when trying to enhance ZT, and (2) how can we make the above mentioned strategies more convergent as we change the dimension of materials systems, the scattering mechanism(s) of carriers, the shape of electronic band structure, and the magnitude of the band gap? This thesis aims to explore the solutions to these two major problems at the research frontier of thermoelectric ZT enhancement. The first problem is discussed by providing a new framework of pseudo-ZTs, where the electronic contribution (zte) and the lattice contribution (ztL) to the overall ZT can be treated in a relatively separate manner. The second problem is discussed under this new framework of pseudo-ZTs, through four subsections: (i) scattering and system dimension; (ii) band structure; (iii) density of states; (iv) band gap. The one-to-one correspondence relation between the carrier scattering mechanism(s) and the maximum Seebeck coefficient is further studied. A new tool for scattering mechanism(s) inference and for the Seebeck coefficient enhancement is provided. For the band structure and the band gap part, advanced band engineering methods are provided to study nanostructured narrow-gap materials, the Dirac cone materials, and the anisotropic materials, which are historically found to be good thermoelectric materials. To further demonstrate the newly developed theories, this thesis has also illustrated the application of these models in some specific materials systems, including the graphene system, the transition metal dichalcogenides monolayer materials systems, the Bi1 -xSbx alloys system, the In1.xGaxN alloys system, and the (BiiySby) 2(S1_xTex)3 alloys system.
by Shuang Tang.
Ph. D.
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Jiba, Zetu. "Coating processes towards selective laser sintering of energetic material composites." Diss., University of Pretoria, 2019. http://hdl.handle.net/2263/79246.
Full textAbstract:
This research aims to contribute to the safe methodology for additive manufacturing (AM) of
energetic materials. Coating formulation processes were investigated to find a suitable method
that may enable selective laser sintering (SLS) as the safe method for fabrication of high
explosive (HE) compositions. For safety and convenience reasons, the concept demonstration
was conducted using inert explosive simulants with properties quasi-similar to the real HE.
Coating processes for simulant RDX-based microparticles by means of PCL and 3,4,5-
trimethoxybenzaldehyde (as TNT simulant) are reported. These processes were evaluated for
uniformity of coating the HE inert simulant particles with binder materials to facilitate the SLS
as the adequate binding and fabrication method. The critical constraints being the coating
effectiveness required, spherical particle morphology, micron size range (>20 μm) and a good
powder deposition and flow, and performance under SLS to make the method applicable for
HEs.
Of the coating processes investigated, suspension system and single emulsion methods gave
required particle near spherical morphology, size and uniform coating. The suspension process
appears to be suitable for the SLS of HE mocks and potential formulation methods for active
HE composites. The density was estimated to be comparable with the current HE compositions
and plastic bonded explosives (PBXs) such as C4 and PE4, produced from traditional methods. The formulation method developed and the understanding of the science behind the processes
paves the way toward safe SLS of the active HE compositions and may open avenues for further
research and development of munitions of the future.Dissertation (MSc)--University of Pretoria, 2019.
Chemical Technology
MSc
Unrestricted
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Kaleta, Radoslav. "Výpočetní model a analýza energeticky úsporných budov." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2019. http://www.nusl.cz/ntk/nusl-403117.
Full textAbstract:
The thesis deals with the analysis of the properties of the external and internal environment of the buildings, the possibilities of heating and cooling. The emphasis is mainly on the energy intensity and the impact of weather conditions on the building temperature during the year. The model created by UPPAAL SMC describes the behavior of heating and cooling during the year and identifies the energy demand of the given building. The building model itself can be partially modified using the built-in user interface.
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Patel, Nitin R. "Intermediate Strain Rate Behavior of Two Structural Energetic Materials." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4865.
Full textAbstract:
A new class of materials, known as multi-functional energetic structural materials (MESMs), has been developed. These materials possess both strength and energetic functionalities, serving as candidates for many exciting applications. One of such applications is ballistic missiles, where these materials serve as part of structural casing as well as explosive payload.
In this study, the dynamic compressive behavior of two types of MESMs in the intermediate strain rate regime is investigated. The first type is a thermite mixture of Al and Fe₂O₃ particles suspended in an epoxy matrix. The second type is a shock compacted mixture of Ni and Al powders. Compression experiments on a split-Hopkinson pressure bar (SHPB) apparatus are carried out at strain rates on the order of 103 s-1. In addition, a novel method for investigating the dynamic hardness of the Al + Fe₂O₃ + Epoxy materials is developed. In this method, high-speed digital photography is used to obtain time-resolved measurements of the indentation diameter throughout the indentation process.
Experiments show that the shock compacted Ni-Al material exhibits a rather ductile behavior and the deformation of the Al + Fe₂O₃ + Epoxy mixtures is dominated by the polymer phase and significantly modulated by the powder phases. The pure epoxy is ductile with elastic-plastic hardening, softening, and perfectly plastic stages of deformation. The Al and Fe₂O₃ particles in Al + Fe₂O₃ + Epoxy mixtures act as reinforcements for the polymer matrix, impeding the deformation of the polymer chains, alleviating the strain softening of the glassy polymer matrix at lower levels of powder contents (21.6 - 29.2% by volume), and imparting the attributes of strain hardening to the mixtures at higher levels of powder contents (21.6 - 49.1% by volume). Both the dynamic and quasi-static hardness values of the Al + Fe₂O₃ + Epoxy mixtures increase with powder content, consistent with the trend seen in the stress-strain curves.
To quantify the constitutive behavior of the 100% epoxy and the Al + Fe₂O₃ + Epoxy materials, the experimentally obtained stress-strain curves are fitted to the Hasan-Boyce model. This model uses a distribution of activation energies to characterize the energy barrier for the initiation of localized shear transformations of long chain polymeric molecules. The results show that an increase in powder content increases the activation energy, decreases the number of transformation sites, causes redistribution of applied strain energy, and enhances the storage of inelastic work. These effects lead to enhanced strength and strain hardening rate at higher levels of powder content.
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Dippold, Alexander. "Nitrogen-rich energetic materials based on 1,2,4-triazole derivatives." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-161426.
Full text
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Szabo, Tamas. "Energy transfer at gas-liquid interface towards energetic materials /." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4797.
Full textAbstract:
Thesis (Ph. D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on February 29, 2008) Vita. Includes bibliographical references.
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Hunter, Steven. "High-pressure computational and experimental studies of energetic materials." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8084.
Full textAbstract:
On account of the high temperatures and pressures experienced by energetic materials during deflagration and detonation, it is important to know not only the physical properties of these materials at ambient temperatures and pressures, but also to understand how their structure and properties are affected by extreme conditions. Combined computational and experimental investigations of the effects of high pressures on the structure and properties of several energetic materials are described herein. A comparison of the performances of different pseudopotentials and density functional theory (DFT) dispersion correction schemes in calculating crystal geometries and vibrational frequencies of crystalline ammonium perchlorate at high pressure is described. The results highlight the fact that care must be taken when choosing pseudopotentials for high-pressure studies. A comprehensive comparison of calculated vibrational modes (including symmetry) with experiment has been performed, with the frequencies of all internal modes predicted to lie within 5% of experimental values. This study established that no significant improvements in the calculation of crystal geometries of ammonium perchlorate are obtained by employing DFT-D corrections. The enthalpy of fusion (ΔHfus) of the highly metastable β-form of RDX (cyclotrimethylenetrinitramine) was determined to be 12.63 ± 0.28 kJ mol-1. DFT-D calculations of the lattice energies of the α- and β-forms of RDX are described. Furthermore, the response of the lattice parameters and unit-cell volumes to pressure for the α-, γ- and ε-forms of RDX calculated using DFT-D are in very good agreement with experimental data. Phonon calculations provide good agreement with vibrational frequencies obtained from Raman spectroscopy, and a predicted inelastic neutron scattering (INS) spectrum of α-RDX shows excellent agreement with experimental INS data recorded as part of this study. The results of the high-pressure phonon calculations have been used to show that the heat capacities of the α-, γ- and ε- forms of RDX are only weakly affected by pressure. DFT-D calculations have been utilised to describe accurately the structure and properties of both β-HMX (Cyclotetramethylenetetranitramine) and α-FOX-7 (1,1-Diamino-2,2-dinitroethylene) as a function of pressure. This work presents data for the experimental hydrostatic compression of both deuterated β-HMX and α-FOX-7 performed using neutron powder diffraction at the ISIS Neutron and Muon facility, in addition to experimental determinations of the INS spectra of both β-HMX and α-FOX-7. The DFT-D hydrostatic compression studies for both materials reproduce the experimental compression trends. Furthermore, the calculated vibrational properties as a function of pressure were in very good agreement with available experimental data. The results of the phonon calculations were then used to predict the effect of pressure on the heat capacities of β-HMX and α-FOX-7. These predictions suggest a very weak pressure dependence of heat capacities (approximately -1 J K-1 mol-1 GPa-1) for these materials. This work demonstrates that the DFT-D model performs extremely well over a range of conditions, and is able to describe accurately intramolecular and intermolecular interactions, and thus the structure and properties of organic molecular nitramine crystals. The computational model was therefore used to predict the high-pressure hydrostatic compression behaviour of a related nitramine, CL-20 (2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane), the results of which highlighted possible discrepancies in the experimental high-pressure X-ray diffraction data recorded for ε-CL-20. This prompted a high-pressure neutron powder diffraction study, which showed good agreement with the computational results, thereby highlighting radiation damage in the X-ray experiments.
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Lock, C. M. "Stable isotope profiling of energetic materials and their precursors." Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517100.
Full text
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Wagstaff, Douglas C. "The stability of novel energetic materials and associated propellants." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/4642.
Full textAbstract:
A study into the degradation of crystalline Hydrazinium Nitroformate (HNF) in isolation has been carried out alongside studies into HNF / polyNIMMO propellant degradation. The contribution of gas / solid autocatalysis in the degradation of the crystalline phase has been determined to be very low. Studies via GC-MS analysis do suggest that the presence (and eventual release) of the crystal impurity, isopropyl alcohol, is a more significant contributor to the eventual autocatalytic breakdown of the crystal matrix. Investigations into the chemical compatibility of HNF with nitrosated and nitrated derivatives of 2NDPA and pNMA indicated that the reaction of HNF is most rapid with N-NO-2NDPA. This reaction between HNF and N-NO-2NDPA is proposed to be the principal route to rapid propellant degradation in 2NDPA stabilised propellant systems. Analysis of a range of polyNIMMO / HNF propellants has allowed development of a hypothesis for this family of propellant compositions over a range of temperatures. The data has indicated that the degradation of polyNIMMO / HNF propellants is a complex process involving a number of interrelated and interdependent reactions. It appears that a significantly different reaction scheme dominates at 80°C compared to either 60°C or 40°C. The incorporation of a 1% anhydrous sodium sulphite + 1% pNMA mixed stabiliser system has shown promise for use in propellant formulations up to temperature of 80°C. Some level of success in stabilisation has also been achieved using very high levels of pNMA within the propellant formulation.
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Collins, Adam Leigh. "Environmentally responsible energetic materials for use in training ammunition." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610529.
Full text
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Rai, Nirmal Kumar. "Numerical framework for mesoscale simulation of heterogeneous energetic materials." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/2001.
Full textAbstract:
Heterogeneous energetic materials such as plastic bonded explosives (PBX), pressed explosives etc have very detailed and non-uniform microstructure. The heterogeneities are usually present in the form of binder, voids, microcracks etc. Shock interaction with these heterogeneities leads to local heated regions known as hot spots. It is widely accepted that these hot spots are predominantly the cause of triggering reaction and eventually ignition in these energetic materials. There are various physical mechanisms operating at mesoscale through which hot spot can be created such as void collapse, inter-granular friction in energetic crystals, shock heating of HMX crystals and binder etc. Hence, microstructural heterogeneities can play a vital role for shock initiation in heterogeneous explosives. In the current work, a general framework is established for performing mesoscale simulations on heterogeneous energetic materials. The numerical framework is based on a massively parallel Cartesian grid based Eulerian solver. Narrow band level set approach is used for sharp tracking of the material interfaces. The interfacial conditions are applied using modified ghost fluid method. The use of level set method for interface tracking provides an inherent advantage of using level set based image segmentation algorithm(active contouring) for the representation of explosives microstructure. The image processing approach allows to perform simulation on real geometries than the idealized shapes. The image processing framework is incorporated in the Eulerian solver. The energetic material considered in the current work is HMX. The chemical decomposition of HMX is modeled using Henson Smilowitz chemical kinetic law. Shock analysis is performed on two different samples of HMX based pressed explosives. Also, both two dimensional and three dimensional shock analysis on mock sugar geometry are performed. The effect of shock strength and relative positioning of voids on ignition threshold of porous HMX is studied. The current work is focused towards the development of a computational framework which can replicate the experimental way of studying the shock initiation behavior of energetic materials i.e. using flyer plate simulations.
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Wagstaff, D. C. "The Stability of novel energetic materials and associated propellants." Thesis, Department of Environmental and Ordnance Systems, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/4642.
Full textAbstract:
A study into the degradation of crystalline Hydrazinium Nitroformate (HNF) in isolation has been
carried out alongside studies into HNF / polyNIMMO propellant degradation. The contribution of
gas / solid autocatalysis in the degradation of the crystalline phase has been determined to be very
low. Studies via GC-MS analysis do suggest that the presence (and eventual release) of the
crystal impurity, isopropyl alcohol, is a more significant contributor to the eventual autocatalytic
breakdown of the crystal matrix. Investigations into the chemical compatibility of HNF with
nitrosated and nitrated derivatives of 2NDPA and pNMA indicated that the reaction of HNF is
most rapid with N-NO-2NDPA. This reaction between HNF and N-NO-2NDPA is proposed to be
the principal route to rapid propellant degradation in 2NDPA stabilised propellant systems.
Analysis of a range of polyNIMMO / HNF propellants has allowed development of a hypothesis
for this family of propellant compositions over a range of temperatures. The data has indicated
that the degradation of polyNIMMO / HNF propellants is a complex process involving a number
of interrelated and interdependent reactions. It appears that a significantly different reaction
scheme dominates at 80°C compared to either 60°C or 40°C.
The incorporation of a 1% anhydrous sodium sulphite + 1% pNMA mixed stabiliser system has
shown promise for use in propellant formulations up to temperature of 80°C. Some level of
success in stabilisation has also been achieved using very high levels of pNMA within the
propellant formulation.
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Sklenářová, Lenka. "Možnosti aplikace systémů s akumulací tepla v jaderné energetice." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230557.
Full textAbstract:
This dissertation covers the application of heat accumulation systems in nuclear power engineering, namely in nuclear power plants. It is mainly a case of passive emergency systems, whose task is to accumulate the heat produced in the reactor’s active zone and in spent fuel pools during DBA (design-basis accidents) or beyond DBA. A particular example of heat accumulation is steam condensation after LOCA (loss of coolant accident). The primary circuit steam leakage increases containment pressure and has to be decreased by the steam condensation. This thesis deals with a theoretical substitute for ice condensers, which are used as a passive safety measure in some nuclear power plants. The substitute involves a choice of an alternative material, whose melting temperature (for heat accumulation) is closer to nuclear power plant operating temperatures. The other part of the dissertation discusses heat accumulation in spent fuel pools in case of all cooling systems failure.
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Liu, Yen-Shan. "Development of an advanced nanocalorimetry system for rapid material characterizations." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4834.
Full textAbstract:
The development of a versatile system capable of providing rapid, portable, and
inexpensive detection of explosives and energetic compounds is needed critically to offer
an enhanced level of protection against current and future threats to homeland security, as
well as to satisfy a wide range of applications in the fields of forensic analysis, emergency
response, and industrial hazards analysis. The hand-held nanocalorimeter will serve as a
first-of-its-kind screening tools for explosive and energetic compounds directly in the
settings where they are needed with high efficiency, reduced cost, and simplicity with ease
of use. Unlike current explosives detectors, this system is based on calorimetric
techniques that are inherently capable of providing direct measurements of energy release
potential and therefore do not depend on prior knowledge of familiar compounds.
The microfabricated calorimetry instrument consists of (i) a thermal control
module incorporating arrays of microfabricated heaters and temperature sensors, as well
as any necessary electronic interconnections, and (ii) a sample encapsulation module
incorporating etched enclosures designed to accommodate either solid or liquid samples. Initial work has led to successful fabrication of a chip capable of sampling nano-sized
solid or liquid compounds. Control algorithms incorporating the DSC principle have also
been written using LabVIEW. Device performance of the original and redesigned chips
were tested by studying the thermal transitions associated with the boiling points of
acetone and pentane. With the redesigned chip, the heat loss issue was reduced: the
measured input heat was reduced from 32 times of the required energy to 5 times of the
required energy. Future work will focus on modifying the chip design and control
algorithm to improve accuracy and sensitivity, developing a trace analysis software to link
it to a database of explosive information, and adapting different fabrication procedures for
high temperature operation and large scale production.
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Kaplan, Václav. "Výpočtové hodnocení konstrukčních staviv z hlediska energetické náročnosti budovy." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-401470.
Full textAbstract:
This thesis deals with the computational comparison of the energy performance of buildings of various construction materials. The work aims at assessing the building as a thermal system. The theoretical part describes the methods for calculating the energy performance of buildings. The experimental part of the work focuses on quantifying the heat consumption of specific buildings in terms of thermal stability and it is later compared with the results calculated in accordance with the applicable technical standards.
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Lair, Shalayna Lee. "Energetic comparison of double-walled carbon nanotube systems." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2007. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Žák, Tomáš. "Využití hybridní technologie Laser-TIG pro svařování rozdílných materiálů používáných v energetice." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400985.
Full textAbstract:
Thesis is focused on analyzing the influence of preheating process parameters using electric arc from TIG torch during laser welding on weld properties of stainless steel and carbon steel with higher strength. In this thesis experiment was done in which metal sheets 3 mm thick from X12Cr13 and S355 steels were welded. Welding was done first with using only laser, then laser with TIG preheating and lastly laser with preheated material by induction heater. When TIG preheating was used than set welding current was changed on the power source. The welds were subsequently evaluated based on macrostructure, microstructure and Vickers hardness test.
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Sundaram, Dilip Srinivas. "Multi-scale modeling of thermochemical behavior of nano-energetic materials." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50225.
Full textAbstract:
Conventional energetic materials which are based on monomolecular compounds such as trinitrotoluene (TNT) have relatively low volumetric energy density. The energy density can be significantly enhanced by the addition of metal particulates. Among all metals, aluminum is popular because of its high oxidation enthalpy, low cost, and relative safety. Micron-sized aluminum particles, which have relatively high ignition temperatures and burning times, have been most commonly employed. Ignition of micron-sized aluminum particles is typically achieved only upon melting of the oxide shell at 2350 K, thereby resulting in fairly high ignition delay. Novel approaches to reduce the ignition temperatures and burning times and enhance the energy content of the particle are necessary.
Recently, there has been an enormous interest in nano-materials due to their unique physicochemical properties such as lower melting and ignition temperatures and shorter burning times. Favorably, tremendous developments in the synthesis technology of nano-materials have also been made in the recent past. Several metal-based energetic materials with nano-sized particles such as nano-thermites, nano-fluids, and metalized solid propellants are being actively studied. The “green” reactive mixture of nano-aluminum particles and water/ice mixture (ALICE) is being explored for various applications such as space and underwater propulsion, hydrogen generation, and fuel-cell technology. Strand burning experiments indicate that the burning rates of nano-aluminum and water mixtures surpass those of common energetic materials such as ammonium dinitramide (ADN), hydrazinium nitroformate (HNF), and cyclotetramethylene tetranitramine (HMX). Sufficient understanding of key physicochemical phenomena is, however, not present. Furthermore, the most critical parameters that dictate the burning rate have not been identified. A multi-zone theoretical framework is established to predict the burning properties and flame structure by solving conservation equations in each zone and enforcing the mass and energy continuities at the interfacial boundaries. An analytical expression for the burning rate is derived and physicochemical parameters that dictate the flame behavior are identified. An attempt is made to elucidate the rate-controlling combustion mechanism. The effect of bi-modal particle size distribution on the burning rate and flame structure are investigated. The results are compared with the experimental data and favorable agreement is achieved.
The ignition and combustion characteristics of micron-sized aluminum particles can also be enhanced by replacing the inert alumina layer with favorable metallic coatings such as nickel. Experiments indicate that nickel-coated aluminum particles ignite at temperatures significantly lower than the melting point of the oxide film, 2350 K due to the presence of inter-metallic reactions. Nickel coating is also attractive for nano-sized aluminum particles due to its ability to maximize the active aluminum content. Understanding the thermo-chemical behavior of nickel-aluminum core-shell structured particles is of key importance to both propulsion and material synthesis applications. The current understanding is, however, far from complete. In the present study, molecular dynamics simulations are performed to investigate the melting behavior, diffusion characteristics, and inter-metallic reactions in nickel-coated nano-aluminum particles. Particular emphasis is on the effects of core size and shell thickness on all important phenomena. The properties of nickel-coated aluminum particles and aluminum-coated nickel particles are also compared.
Considerable uncertainties pertaining to the ignition characteristics of nano-aluminum particles exist. Aluminum particles can spontaneously burn at room temperature, a phenomenon known as pyrophoricity. This is a major safety issue during particle synthesis, handling, and storage. The critical particle size below which nascent particles are pyrophoric is not well known. Energy balance analysis with accurate evaluation of material properties (including size dependent properties) is performed to estimate the critical particle size for nascent particles. The effect of oxide layer thickness on pyrophoricity of aluminum particles is studied. The ignition delay and ignition temperature of passivated aluminum particles are also calculated. Specific focus is placed on the effect of particle size. An attempt is made to explain the weak dependence of the ignition delay on particle size at nano-scales.