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Energetic materials at extreme conditionsMillar, David Iain Archibald January 2011 (has links)
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.
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Estudo comparativo de exames clínico-laboratoriais no diagnóstico de carência energética prolongada em garrotes / Comparative study of clinical laboratory assays for the diagnosis of prolonged energetic deficit in steersSucupira, Maria Claudia Araripe 14 February 2003 (has links)
Para comparar indicadores no diagnostico laboratorial da carência energética e avaliar sua influencia no quadro clínico, 12 garrotes foram aleatoriamente distribuídos em três grupos iguais e receberam , por 140 dias, as seguintes dietas: (G1) adequada, para ganho de peso de 900g/dia (13% de PB e 17,7 Mcal/d de ED); (G2) 80% dos requerimentos de mantença (7% de PB e 5,8 Mcal/d de ED); e (G3) 60% desses requerimentos (5% de PB e 4,7 Mcal/d de ED). Dois animais do G3 sucumbiram ao término do experimento. A carência provocou menor consumo de alimentos, diminui9ao do escore de condição corporal, sem alterar o peso vivo. Embora o volume ruminal tenha sido semelhante entre todos os grupos, as taxa de passagem e de renovação de líquidos foram menores nos grupos carentes. O déficit energético reduziu a produção ruminal de ácidos graxos voláteis totais e de suas frações, o tempo de redução de azul de metileno no suco ruminal foi maior, enquanto que os índices de excreção urinaria de alantoína e de ácido úrico foram menores nos grupos carentes. Os melhores indicadores do status energético foram a glicemia e os teores de β-hidroxibutirato plasmáticos, que reduziram durante a carência: os AGLs não foram eficientes devido a alta variabilidade dos resultados. Não foram detectados corpos cetônicos na urina. O hematócrito e os teores séricos de ureia, albumina, globulinas e creatinina não se mostraram úteis no diagnóstico, porem o índice de excreção urinaria de ureia se reduziu, indicando maior conservação de nitrogênio pelo organismo carente. O déficit energético provocou diminui980 nos batimentos cardíacos, atingindo em quadros avançados 30 bat/min; na frequência respiratória; nos movimentos e tonicidade ruminal. Quanto menor foi a glicemia menores foram os batimentos cardíacos (r= 0,55), a frequência respiratória (r = 0,49) e a tonicidade ruminal (r= 0,81). A temperatura retal permaneceu dentro dos valores de normalidade, mas hipotermia foi detectada precedendo a morte. Levando-se em conta a facilidade, praticidade e custo dos exames, sugere-se o diagnóstico de carência requisitando analise de glicose, β-hidroxibutirato plasmáticos, tempo de redução do azul de metileno no suco ruminal e índice de excreção urinária de ácido úrico. / In order to compare laboratory diagnosis indicators of energetic deficit and evaluate their influence in the clinical picture, 12 steers were randomly distributed in 3 groups of 4 animals, which received the following diets for 140 days : (G1) adequate diet for weight gain of 900g/day (CP: 13% and DE: 17,7 Mcal/d); (G2) 80% of the maintenance requirements (CP: 7% and DE: 5,8 Mcal/d); (G3) 60% of the same requirements (CP: 5% and DE: 4,7 Mcal/d). Two animals from G3 died by the end of the experiment. The nutritional deficit led to lower feed intake and a decrease in the body condition score; without changing body weight. Although the rumen volume was similar in all three groups, the rates of liquid passage and ruminal turnover were lower in G2 and G3. The energetic deficit led to a reduced rumen production of total and fractions of volatile fatty acids. The time of blue methylene reduction in the rumen juice was longer, whereas the index of urinary excretion of allantoin and uric acid was lower in G2 and G3. The best indicators of the energetic status were glycemia and the plasma level of β-hydroxybutirate, which were both reduced during the deficit energetic. NEFA levels were not effective, due to the high variability of the results. Ketone bodies were not detected in the urine. Hematocrit and serum levels of urea, albumin, globulin and creatinin were not useful for malnutrition diagnosis, but the index of urinary excretion of urea was decreased, indicating that malnourished bodies were keeping Nitrogen. The energetic deficit caused a gradual decrease in cardiac rates , falling to 30 beats/min in advanced deficit of energy. Reduced respiratory frequency and rumen tonus was also altered in this condition. Low glycemia was related to decreased heart beat frequency (r=0.55), to respiratory frequency (r=0.49) and to rumen tonus (r=0.81). The rectal temperature remained within normal values; however hypothermia was detected preceding death. Taking into account costs and friendly usage of assays, we suggest the analysis of glucose, plasma β-hydroxybutirate, time of reduction of methylene blue in the rumen juice, and index of urinary excretion of uric acid for the diagnosis of energetic deficit.
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"Simulação semi-empírica da resposta termoluminescente sob diferentes geometrias de filtro" / SEMI-EMPIRICAL SIMULATION OF THERMOLUMINESCENT RESPONSE UNDER DIFFERENT FILTER GEOMETRIESShammas, Gabriel Issa Jabra 21 December 2006 (has links)
Muitos materiais termoluminescentes têm sido desenvolvidos e utilizados para a monitoração individual externa de fótons, mas nenhum tem todas as características desejadas sozinho. Estas características incluem robustez, alta sensibilidade, independência de resposta quanto à energia do fóton, larga faixa de detecção de energia, boa reprodutibilidade, evanescência pequena e curva de emissão termoluminescente simples, com picos abaixo de 150oC. O dosímetro de sulfato de cálcio dopado com disprósio CaSO4:Dy) tem sido usado por muitos laboratórios, principalmente no Brasil e na Índia. Outro fósforo interessante é o fluoreto de cálcio (CaF2). As vantagens destes fósforos começam a ser mais requisitadas e suas desvantagens mais aparentes, no mercado globalizado mais e mais competitivo. Estes fósforos são utilizados em monitoração de área e ambiental devido à sua maior sensibilidade do que outros fósforos, como o LiF:Mg. A sua maior desvantagem é a forte dependência energética da resposta, que deve ser corrigida para suas aplicações em campo, onde o fóton é desconhecido a priori. Um modo interessante de fazer esta correção numa incidência ortogonal da radiação no fósforo é a interposição de um filtro plano vazado entre o feixe e o fósforo. Com o objetivo de reduzir a dependência energética sob incidência em qualquer ângulo, reduzindo a incerteza de medição da dose em campo também, este trabalho apresenta um estudo de simulação em geometrias de filtro esféricas. Foram simuladas irradiações de fótons com raios gama do cobalto 60, com raios-X de 33, 48 e 118 keV, em vários ângulos de incidência de zero a noventa graus. Estas simulações computacionais semi-empíricas, utilizando diferenças finitas em três dimensões, foram feitas em coordenadas esféricas. Os resultados indicaram as melhores espessuras e larguras para a otimização da correção da dependência energética. / Many thermoluminescent materials has been developed and used for photon personal dosimetry but no one has all desired characteristics alone. These characteristics include robustness, high sensitivity, energy photon independence, large range of photon energy detection, good reproductibility, small fading and simple glow curve with peaks above 150oC. Calcium Sulfate Dysprosium doped (CaSO4:Dy) phosphor Thermoluminescent Dosimeter (TLD) has been used by many laboratories, mainly in Brazil and India. Another interesting phosphor is Calcium Fluoride (CaF2). These phosphor advantages begin to be more required and its disadvantages have became more apparent, in a global market more and more competitive. These phosphors are used in environmental and area monitoring, once they present more sensibility than other phosphors, like LiF:Mg. Theirs mainly disadvantage is a strong energetic dependence response, which must be corrected for theirs application in the field, where photon radiation is unknown a priori. An interesting way do make this correction in orthogonal incidence of the radiation on the phosphor is to interject a plane leaked filter between the beam and the phosphor. In order to reduce the energetic dependence on any incidence angle, reducing the field dose measurement uncertainty too, this work presents a simulation study on spherical filter geometries. It was simulated photon irradiations with Gamma rays of 60Co and x-rays of 33; 48 and 118 keV, on many incidence angles from zero to ninety degrees. These semi-empirical computational simulations using finite differences in three dimensions were done in spherical coordinates. The results pointed out the best filter thicknesses and widths, in order to optimize the correction on energetic dependence.
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"Simulação semi-empírica da resposta termoluminescente sob diferentes geometrias de filtro" / SEMI-EMPIRICAL SIMULATION OF THERMOLUMINESCENT RESPONSE UNDER DIFFERENT FILTER GEOMETRIESGabriel Issa Jabra Shammas 21 December 2006 (has links)
Muitos materiais termoluminescentes têm sido desenvolvidos e utilizados para a monitoração individual externa de fótons, mas nenhum tem todas as características desejadas sozinho. Estas características incluem robustez, alta sensibilidade, independência de resposta quanto à energia do fóton, larga faixa de detecção de energia, boa reprodutibilidade, evanescência pequena e curva de emissão termoluminescente simples, com picos abaixo de 150oC. O dosímetro de sulfato de cálcio dopado com disprósio CaSO4:Dy) tem sido usado por muitos laboratórios, principalmente no Brasil e na Índia. Outro fósforo interessante é o fluoreto de cálcio (CaF2). As vantagens destes fósforos começam a ser mais requisitadas e suas desvantagens mais aparentes, no mercado globalizado mais e mais competitivo. Estes fósforos são utilizados em monitoração de área e ambiental devido à sua maior sensibilidade do que outros fósforos, como o LiF:Mg. A sua maior desvantagem é a forte dependência energética da resposta, que deve ser corrigida para suas aplicações em campo, onde o fóton é desconhecido a priori. Um modo interessante de fazer esta correção numa incidência ortogonal da radiação no fósforo é a interposição de um filtro plano vazado entre o feixe e o fósforo. Com o objetivo de reduzir a dependência energética sob incidência em qualquer ângulo, reduzindo a incerteza de medição da dose em campo também, este trabalho apresenta um estudo de simulação em geometrias de filtro esféricas. Foram simuladas irradiações de fótons com raios gama do cobalto 60, com raios-X de 33, 48 e 118 keV, em vários ângulos de incidência de zero a noventa graus. Estas simulações computacionais semi-empíricas, utilizando diferenças finitas em três dimensões, foram feitas em coordenadas esféricas. Os resultados indicaram as melhores espessuras e larguras para a otimização da correção da dependência energética. / Many thermoluminescent materials has been developed and used for photon personal dosimetry but no one has all desired characteristics alone. These characteristics include robustness, high sensitivity, energy photon independence, large range of photon energy detection, good reproductibility, small fading and simple glow curve with peaks above 150oC. Calcium Sulfate Dysprosium doped (CaSO4:Dy) phosphor Thermoluminescent Dosimeter (TLD) has been used by many laboratories, mainly in Brazil and India. Another interesting phosphor is Calcium Fluoride (CaF2). These phosphor advantages begin to be more required and its disadvantages have became more apparent, in a global market more and more competitive. These phosphors are used in environmental and area monitoring, once they present more sensibility than other phosphors, like LiF:Mg. Theirs mainly disadvantage is a strong energetic dependence response, which must be corrected for theirs application in the field, where photon radiation is unknown a priori. An interesting way do make this correction in orthogonal incidence of the radiation on the phosphor is to interject a plane leaked filter between the beam and the phosphor. In order to reduce the energetic dependence on any incidence angle, reducing the field dose measurement uncertainty too, this work presents a simulation study on spherical filter geometries. It was simulated photon irradiations with Gamma rays of 60Co and x-rays of 33; 48 and 118 keV, on many incidence angles from zero to ninety degrees. These semi-empirical computational simulations using finite differences in three dimensions were done in spherical coordinates. The results pointed out the best filter thicknesses and widths, in order to optimize the correction on energetic dependence.
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Impacto da altura de aerogeradores sobre a velocidade do vento, energia, efeito de esteira e intensidade de turbulência : estudos de caso em três projetos eólicos localizados no BrasilPereira, Maurício Vieira da Rocha January 2016 (has links)
O setor eólico está em processo de consolidação no Brasil desde o início dos anos 2000, e oportunidades de pesquisas e desenvolvimento estão presentes em todas as etapas do processo. Este trabalho apresenta uma relação entre os parâmetros de velocidade do vento, energia, efeito de esteira e intensidade de turbulência com diferentes alturas de turbinas existentes no mercado brasileiro, em três regiões distintas, Triunfo/PE, São João do Cariri/PB e São Martinho da Serra/RS. A finalidade do trabalho é auxiliar os desenvolvedores e os investidores de parques eólicos na tomada de decisão sobre as alturas de aerogeradores a serem consideradas em seus projetos eólicos, antecipando a avaliação criteriosa do recurso eólico local. Para tal, primeiramente são citadas referências de trabalhos similares disponíveis na literatura bem como é realizada a fundamentação teórica do estudo com as principais equações e modelos utilizados na área. A metodologia do cálculo é teórica e aplicada às ferramentas computacionais do WAsP para a modelagem do vento e do WindFarmer para avaliar a produção de energia elétrica, com adaptações específicas para cada projeto. Procedimentos estatísticos são efetuados a fim de se garantir que as análises contenham o menor nível possível de incerteza na identificação do recurso eólico de cada região. Os resultados do trabalho são apresentados comparativamente entre os sete modelos de aerogerador testados e também entre as três áreas estudadas. O comportamento das turbinas é consideravelmente diferente em todas as opções estudadas. Os modelos de aerogerador A e D são os que apresentam o maior ganho energético percentual com o incremento da altura da turbina com valores médios de 0,42% e 0,44% a cada metro. Já os modelos C e D apresentam as melhorias mais consideráveis em termos de redução de intensidade de turbulência e diminuição de perdas por efeito de esteira, conforme se aumenta a altura das turbinas. As áreas apresentam, também, recursos eólicos distintos entre elas. O projeto eólico de Triunfo é o que apresenta a maior geração de energia dentre os estudados, sendo 24,2% maior que em São Martinho da Serra e 45,0% maior que em São João do Cariri. Verifica-se, também, que caso a velocidade média do vento de longo prazo fosse dobrada em Triunfo, a energia líquida teria um acréscimo de 88%. Já em São Martinho da Serra este valor chegaria em 170% e em São João do Cariri em 220%. / The wind energy sector has been under consolidation in Brazil since the early 2000s. Opportunities for researches and developments are present at all stages of the process. This paper presents a link among wind speed, energy, wake effect and turbulence intensity parameters and the height of existing wind turbine models in Brazil, considering three distinct regions as Triunfo/PE, São João do Cariri/PB and São Martinho da Serra/RS. This paper also aims to support developers and investors in the decision making process in the wind turbines height that should be considered in its wind farms. To this end, the references of similar studies as well as the theoretical basis for the study, including the main equations and models, are presented. The calculation methodology is theoretical and it has been applied to the computational tools WAsP (wind modeling) and WindFarmer (evaluate the energy production), considering specific adaptations for each project. Statistical procedures are performed in order to ensure that the analyses contain the lowest possible level of uncertainty in the characterization of the wind resources in each region. The results are presented comparatively among the seven tested turbine models and also among the three studied areas. The turbine models behavior is considerably different for all options. The wind turbine models A and D are those with the highest percentage energy increase with increasing the turbine height. Their average values are 0.42% and 0.44% per meter height. The models C and D present the most considerable improvements in terms of turbulence intensity and wake effect reductions with increasing the turbine height. The different locations also present distinguished wind resources among them. Triunfo wind farm is the one with the highest energy generation, 24.2% higher than in São Martinho da Serra and 45.0% higher than in São João do Cariri. It is also noted that if the long term mean wind speed was doubled in the project locations, the energy would have an increase of 88% in Triunfo, 170% in São Martinho da Serra and 220% in São João do Cariri.
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EXPLORING THE INKJET PRINTING OF FUNCTIONAL MATERIALS AND THEIR USE IN ENERGETIC SYSTEMS AND SENSING APPLICATIONSAllison K Murray (7845965) 12 November 2019 (has links)
<div>With an eye towards applications such as the selective sensing of volatile organic compounds (VOCs) or micro-scale thrust generation, inkjet printing was explored as a means to selectively deposit functional materials. The work detailed herein explores a series of fundamental steps to gain expertise related to the piezoelectric inkjet printing of functional materials. The successful printing of nanothermite was demonstrated with two unique printing techniques. Furthermore, the integration of this material with an ignition mechanism was shown to create a fully printed igniter energetic system. These advancements support future work related to the printing of other energetic materials necessary to create tunable reactive systems. This knowledge was then translated into the development of resonant mass sensing devices that are selectively functionalized using inkjet printing. This approach to functionalization allowed for the precise deposition of receptive chemistries on devices resulting in selective, highly-sensitive devices that successfully detected biomarkers secreted after traumatic brain injuries and harmful VOCs. This work implemented oscillator-based sensors to achieve a low-cost, low-power sensor platform with redundant elements. Furthermore, the predictive capabilities of these devices were explored using least squares and linear regression modeling.</div>
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Improving the Effectiveness of Laying Hens for Use in Value-Added Egg Production.Nain, Sandeep 06 1900 (has links)
A series of experiments were conducted to explore factors affecting transfer of value-added ingredients from the diet to table eggs, with the goal of contributing to improvements in the enrichment process.
Flaxseed-based ω-3 PUFA enrichment did not reduce lutein enrichment. The combine enrichment of lutein and ω-3 PUFA had decresed lipid oxidation potential. Also, when fed a ω-3 PUFA diet, birds scored as energetic Efficient had longer and wider villi, resulting in greater absorptive surface area/villi than Non-efficient hens. However, histomorphological differences did not affect transfer of ω-3 PUFA from diet to egg. Finally, birds fed graded levels of ω-3 PUFA to characterize change in lipid profile of egg and blood plasma in time reached a plateau in total ω-3 PUFA/egg in 5.9 to 6.6d, with High birds reaching the target of 300 mg/egg in 5d. Egg enrichment can be modulated by changes to the hen diet. / Animal Science
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Spatially Heterogeneous Prey Patterns may be Necessary for Predator Survival: a Model and a Review of the Aquatic LiteratureCinquemani, Fabio Giuseppe 19 July 2012 (has links)
The Allen Paradox is the observation that, in aquatic communities, there is insufficient prey production to support predator growth. An assessment of the literature reveals that this paradox remains apparent in one of every four studies. Here, a novel explanation for this paradox is proposed: predators that feed in a spatially-heterogeneous-prey environment (SHPE) may experience a greater net energy gain than in a corresponding uniform-prey environment (UPE), meaning that predators may require less food than has been traditionally perceived. A model was
developed to simulate a predator’s energy gain while feeding in a SHPE rather than a UPE. According to the simulation, a greater net energy gain in a SHPE than a UPE
is possible, but only under certain conditions. Since prey can be utilized more efficiently in a SHPE, a given amount of prey production can supply more predator growth, which can have positive implications in fish stocking.
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Spatially Heterogeneous Prey Patterns may be Necessary for Predator Survival: a Model and a Review of the Aquatic LiteratureCinquemani, Fabio Giuseppe 19 July 2012 (has links)
The Allen Paradox is the observation that, in aquatic communities, there is insufficient prey production to support predator growth. An assessment of the literature reveals that this paradox remains apparent in one of every four studies. Here, a novel explanation for this paradox is proposed: predators that feed in a spatially-heterogeneous-prey environment (SHPE) may experience a greater net energy gain than in a corresponding uniform-prey environment (UPE), meaning that predators may require less food than has been traditionally perceived. A model was
developed to simulate a predator’s energy gain while feeding in a SHPE rather than a UPE. According to the simulation, a greater net energy gain in a SHPE than a UPE
is possible, but only under certain conditions. Since prey can be utilized more efficiently in a SHPE, a given amount of prey production can supply more predator growth, which can have positive implications in fish stocking.
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Design and Operation of Membrane Microcalorimeters for Thermal Screening of Highly Energetic MaterialsCarreto Vazquez, Victor 1976- 14 March 2013 (has links)
Following several terrorist attacks that have occurred during this decade,
there is an urgent need to develop new technologies for the detection of highly
energetic materials that can represent an explosive hazard. In an effort to
contribute to the development of these new technologies, this work presents the
design aspects of a chip-scale calorimeter that can be used to detect an
explosive material by calorimetric methods. The aim of this work is to apply what
has been done in the area of chip-scale calorimetry to the screening of highly
energetic materials. The prototypes presented here were designed using
computer assisted design and finite element analysis tools. The design
parameters were set to satisfy the requirements of a sensor that can be
integrated into a portable system (handheld) for field applications. The design
approach consisted of developing a sensor with thick silicon membranes that
can hold micro-size samples and that can operate at high temperatures, while
keeping the cost of the sensor low. Contrary to other high resolution systems based on thin-film membranes, our prototypes exhibit a contribution from
addenda that is comparable to that from the sample, and hence they have lower
sensitivity. However, using thick membranes offers the advantage of producing
sensors strong enough for this application and that have significantly lower cost.
Once the prototypes were designed, the fabrication was performed using
standard microfabrication techniques. Finally, the operation of our prototypes
was demonstrated by conducting thermal analysis of different liquid and solid
samples.
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