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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Operation of a High-Pressure Uncooled Plasma Torch with Hydrocarbon Feedstocks

Gallimore, Scott D. Jr. 21 August 1998 (has links)
The main scope of this project was to determine if a plasma torch could operate on pure hydrocarbon feedstocks and, if so, to catalogue the torch operational characteristics. The future goal of the project is to design a plasma torch for supersonic combustion applications that operates off of the vehicle main fuel supply to simplify onboard fuel systems. Experiments were conducted with argon, methane, ethylene and propylene. Spectrographic tests and tests designed to catalogue current/voltage characteristics, plasma jet phenomena, arc stability dependencies, electrode erosion rate and torch body temperature were performed. Spectrographic analysis of the plasma jet exhaust confirmed the presence of combustion-enhancing radicals for each hydrocarbon gas tested. Also, it was discovered that simple hydrocarbon gases, such as methane, produced smooth torch operation, while even slightly more complex gases, ethylene and propylene, caused unsteady performance. Plasma jet oscillation was found to be related to the voltage waveform of the power supplies, indicating that plasma jet length and oscillation rate could be controlled by changing the input voltage. The plasma torch for this study was proven to have the capability of operating with pure hydrocarbon feedstocks and producing radicals that are known to reduce combustion reaction rate times. The torch was demonstrated to have potential for use in supersonic combustion applications. / Master of Science
12

Walking Through Apertures: Assessing Judgments Obtained from Multiple Modalities

Favela, Luis H., Jr. 24 June 2014 (has links)
No description available.
13

Scramjet Operability Range Studies of an Integrated Aerodynamic-Ramp-Injector/Plasma-Torch Igniter with Hydrogen and Hydrocarbon Fuels

Bonanos, Aristides Michael 23 September 2005 (has links)
An integrated aerodynamic-ramp-injector/plasma-torch-igniter of original design was tested in a Mâ = 2, unvitiated, heated flow facility arranged as a diverging duct scramjet combustor. The facility operated at a total temperature of 1000 K and total pressure of 330 kPa. Hydrogen (H2), ethylene (C2H4) and methane (CH4) were used as fuels, and a wide range of global equivalence ratios were tested. The main data obtained were wall static pressure measurements, and the presence of combustion was determined based on the pressure rises obtained. Supersonic and dual-mode combustion were achieved with hydrogen and ethylene fuel, whereas very limited heat release was obtained with the methane. Global operability limits were determined to be 0.07 < Ï < 0.31 for hydrogen, and 0.14 < Ï < 0.48 for ethylene. The hydrogen fuel data for the aeroramp/torch system was compared to data from a physical 10 unswept compression ramp injector and similar performance was found with the two arrangements. With hydrogen and ethylene as fuels and the aeroramp/plasma-torch system, the effect of varying the air total temperature was investigated. Supersonic combustion was achieved with temperatures as low as 530K and 680K for the two fuels, respectively. These temperatures are facility/operational limits, not combustion limits. The pressure profiles were analyzed using the Ramjet Propulsion Analysis (RJPA) code. Results indicate that both supersonic and dual-mode ramjet combustion were achieved. Combustion efficiencies varied with Ï from a high of about 75% to a low of about 45% at the highest Ï . With a theoretical diffuser and nozzle assumed for the configuration and engine, thrust was computed for each fuel. Fuel specific impulse was on average 3000 and 1000 seconds for hydrogen and ethylene respectively, and air specific impulse varied from a low of about 9 sec to a high of about 24 sec (for both fuels) for the To = 1000K test condition. The GASP RANS code was used to numerically simulate the injection and mixing process of the fuels. The results of this study were very useful in determining the suitability of the selected plasma torch locations. Further, this tool can be used to determine whether combustion is theoretically possible or not. / Ph. D.
14

Desenvolvimento de produto multiparamétrico para triagem pré-natal de anticorpos IgG contra doenças infecciosas / Development of multiplex assay for prenatal screening of IgG antibodies against infectious diseases

Pires, Joyce Suellen Coêlho 28 March 2016 (has links)
Infecção congênita é aquela transmitida da mãe ao feto antes do nascimento. A transmissão vertical pode ocorrer por via transplacentária ou por contato direto com o patógeno durante o parto. A fonte de infecção é o microrganismo presente no sangue da gestante durante a infecção primária ou crônica. Estima-se que as infecções perinatais representam 2% a 3% de todas anomalias congênitas e as mais comuns são representadas pela sigla TORCH, que inclui Toxoplasmose, Outras (como sífilis e varicela-zoster), Rubeóla, Citomegalovírus e Herpes. A maioria das infecções TORCH causa morbidade materna leve, assintomática, mas tem consequências fetais graves e, em geral, o tratamento da infecção materna não tem impacto sobre o resultado fetal. Por isso, o reconhecimento do contágio materno e o monitoramento fetal são de extrema importância na prevenção de doenças congênitas. O presente projeto visa o desenvolvimento de um produto multiparamétrico utilizando a tecnologia xMAP®, criada pela companhia norte-americana Luminex Corporation, para detecção simultânea de anticorpos da classe IgG anti-Toxoplasmose, anti-Rubéola e anti- Citomegalovírus em amostras de sangue coletado em papel de filtro. O produto, inédito no mercado nacional, tem o objetivo de atender à demanda específica da triagem pré-natal no país. Como objetivos específicos pode-se citar: a melhoria da eficiência dos programas de triagem pré-natal, graças à economia de tempo, amostras e reagentes; a contribuição financeira para o Brasil, uma vez que será produzido nacionalmente, gerando emprego e renda; a possibilidade de ampliar o mercado a partir do desenvolvimento futuro de novos produtos baseados na mesma metodologia. Para tanto, utilizaram-se antígenos específicos acoplados à microesferas de poliestireno e anticorpos de detecção conjugados à estreptavidina-ficoeritrina. Foram analisadas 1499 amostras de gestantes, coletadas em papel de filtro, cedidas e previamente triadas pela APAE-Goiânia, com o objetivo de comparar os resultados obtidos através da análise com o protótipo desenvolvido com aqueles já confirmados pelo laboratório utilizando a tradicional metodologia de ELISA. Os resultados de Concordância e Sensibilidade foram superiores a 78% para todos os parâmetros. Por outro lado, os valores de Especificidade foram mais baixos, principalmente para os parâmetros Rubéola e Citomegalovírus. Importante ressaltar o pequeno número de amostras com resultado negativo para Citomegalovírus e Rubéola disponível, o que refletiu diretamente no cálculo da Especificidade do produto / Congenital infections are transmitted from the mother to the fetus before birth. Vertical transmission can occur via placenta or by direct contact with the pathogen during childbirth. The source of infection is the microorganism present in the pregnant woman\'s blood during primary or chronic infection. It is estimated that perinatal infections are responsible for 2% to 3% of all congenital abnormalities and the most common are represented by the acronym TORCH, including Toxoplasmosis, Others (such as syphilis and varicella-zoster), Rubella, Cytomegalovirus (CMV) and Herpes. Most infections TORCH causes mild maternal morbidity, asymptomatic, but has serious fetal consequences fetal and, generally, maternal infection treatment has no impact on fetal outcome. Therefore, the recognition of maternal infection and fetal monitoring are extremely important in preventing birth defects. This project aims to develop a product using the multiplex xMAP® technology, created by US company Luminex Corporation, for simultaneous detection of IgG antibodies anti-toxoplasmosis, antirubella and anti-cytomegalovirus in blood samples collected in filter paper. The product, unprecedented in brazilian market, aims to meet the specific demand of prenatal screening in Brazil. The specific objectives are: improving the efficiency of prenatal screening programs, thanks to savings in time, samples and reagents; the financial contribution for Brazil, as it will be produced nationally, generating jobs and income; the possibility of expanding the market from the future development of new products based on the same methodology. For this purpose, were used specific antigens coupled to polystyrene beads and antibodies conjugated to streptavidin-phycoerythrin. Were analyzed 1499 samples of pregnant women, collected on filter paper, pre-screened by APAE-Goiânia, in order to compare the results obtained from the analysis with the prototype developed with those already confirmed by the laboratory using traditional ELISA methodology. The results of Concordance and Sensitivity were higher than 78% for all parameters. In contrast, the Specificity values were lower, especially for Rubella and Cytomegalovirus parameters. Importantly the small number of negative samples negative for Cytomegalovirus and Rubella provided by APAE-Goiânia, which is directly reflected in the product specificity value.
15

Desenvolvimento de produto multiparamétrico para triagem pré-natal de anticorpos IgG contra doenças infecciosas / Development of multiplex assay for prenatal screening of IgG antibodies against infectious diseases

Joyce Suellen Coêlho Pires 28 March 2016 (has links)
Infecção congênita é aquela transmitida da mãe ao feto antes do nascimento. A transmissão vertical pode ocorrer por via transplacentária ou por contato direto com o patógeno durante o parto. A fonte de infecção é o microrganismo presente no sangue da gestante durante a infecção primária ou crônica. Estima-se que as infecções perinatais representam 2% a 3% de todas anomalias congênitas e as mais comuns são representadas pela sigla TORCH, que inclui Toxoplasmose, Outras (como sífilis e varicela-zoster), Rubeóla, Citomegalovírus e Herpes. A maioria das infecções TORCH causa morbidade materna leve, assintomática, mas tem consequências fetais graves e, em geral, o tratamento da infecção materna não tem impacto sobre o resultado fetal. Por isso, o reconhecimento do contágio materno e o monitoramento fetal são de extrema importância na prevenção de doenças congênitas. O presente projeto visa o desenvolvimento de um produto multiparamétrico utilizando a tecnologia xMAP®, criada pela companhia norte-americana Luminex Corporation, para detecção simultânea de anticorpos da classe IgG anti-Toxoplasmose, anti-Rubéola e anti- Citomegalovírus em amostras de sangue coletado em papel de filtro. O produto, inédito no mercado nacional, tem o objetivo de atender à demanda específica da triagem pré-natal no país. Como objetivos específicos pode-se citar: a melhoria da eficiência dos programas de triagem pré-natal, graças à economia de tempo, amostras e reagentes; a contribuição financeira para o Brasil, uma vez que será produzido nacionalmente, gerando emprego e renda; a possibilidade de ampliar o mercado a partir do desenvolvimento futuro de novos produtos baseados na mesma metodologia. Para tanto, utilizaram-se antígenos específicos acoplados à microesferas de poliestireno e anticorpos de detecção conjugados à estreptavidina-ficoeritrina. Foram analisadas 1499 amostras de gestantes, coletadas em papel de filtro, cedidas e previamente triadas pela APAE-Goiânia, com o objetivo de comparar os resultados obtidos através da análise com o protótipo desenvolvido com aqueles já confirmados pelo laboratório utilizando a tradicional metodologia de ELISA. Os resultados de Concordância e Sensibilidade foram superiores a 78% para todos os parâmetros. Por outro lado, os valores de Especificidade foram mais baixos, principalmente para os parâmetros Rubéola e Citomegalovírus. Importante ressaltar o pequeno número de amostras com resultado negativo para Citomegalovírus e Rubéola disponível, o que refletiu diretamente no cálculo da Especificidade do produto / Congenital infections are transmitted from the mother to the fetus before birth. Vertical transmission can occur via placenta or by direct contact with the pathogen during childbirth. The source of infection is the microorganism present in the pregnant woman\'s blood during primary or chronic infection. It is estimated that perinatal infections are responsible for 2% to 3% of all congenital abnormalities and the most common are represented by the acronym TORCH, including Toxoplasmosis, Others (such as syphilis and varicella-zoster), Rubella, Cytomegalovirus (CMV) and Herpes. Most infections TORCH causes mild maternal morbidity, asymptomatic, but has serious fetal consequences fetal and, generally, maternal infection treatment has no impact on fetal outcome. Therefore, the recognition of maternal infection and fetal monitoring are extremely important in preventing birth defects. This project aims to develop a product using the multiplex xMAP® technology, created by US company Luminex Corporation, for simultaneous detection of IgG antibodies anti-toxoplasmosis, antirubella and anti-cytomegalovirus in blood samples collected in filter paper. The product, unprecedented in brazilian market, aims to meet the specific demand of prenatal screening in Brazil. The specific objectives are: improving the efficiency of prenatal screening programs, thanks to savings in time, samples and reagents; the financial contribution for Brazil, as it will be produced nationally, generating jobs and income; the possibility of expanding the market from the future development of new products based on the same methodology. For this purpose, were used specific antigens coupled to polystyrene beads and antibodies conjugated to streptavidin-phycoerythrin. Were analyzed 1499 samples of pregnant women, collected on filter paper, pre-screened by APAE-Goiânia, in order to compare the results obtained from the analysis with the prototype developed with those already confirmed by the laboratory using traditional ELISA methodology. The results of Concordance and Sensitivity were higher than 78% for all parameters. In contrast, the Specificity values were lower, especially for Rubella and Cytomegalovirus parameters. Importantly the small number of negative samples negative for Cytomegalovirus and Rubella provided by APAE-Goiânia, which is directly reflected in the product specificity value.
16

Venereal Disease and American Policy in a Foreign War Zone: 39th Infantry Regiment in Sidi-Bel-Abbes, Algeria. May of 1943.

Gibbs, Thomas J 18 December 2015 (has links)
Second Lieutenant Charles Scheffel, B Company Platoon Leader, 39th Infantry Regiment, 9th Infantry Division modified existing methods of venereal disease control in Algeria, North Africa during Operation Torch after being ordered to reduce the venereal disease rate by his regimental commander, Colonel William Ritter. Tasked with defeating the Germans first, Scheffel learned other enemies lurked as well, and he instituted an illegal policy to solve the problem as fast and as effectively as possible. Official United States policy on the eve of World War Two prohibited the establishment and operation of a brothel. Scheffel operated this brothel as the United States Army occupied Arab lands for the first time in its history and improved the combat effectiveness of his regiment.
17

Thermal analysis of energy beam using de-laval nozzle in plasma figuring process

Yu, Nan January 2016 (has links)
In 2012, plasma figuring was proven to be an alternative solution for the fabrication of large scale ultra-precise optical surfaces. Indeed, plasma figuring was successfully demonstrated on a metre class glass surface. The process was exceptionally rapid but residual errors were observed. This thesis addresses this issue by proposing an enhanced tool that provides a highly collimated plasma jet. The enhanced tool is characterized by a targeted material removal footprint in the range 1 to 5 mm FWHM. The energy beam is provided by an Inductively Coupled Plasma (ICP) torch equipped with a De-Laval nozzle. This thesis focuses on characterization and optimisation of the bespoke plasma torch and its plasma jet. Two research investigations were carried out using both numerical and experimental approaches. A novel CFD model was created to analyse and understand the behaviour of high temperature gas in the De-Laval nozzle. The numerical approach, that was based on appropriate profiles of temperature and velocity applied to the nozzle inlet, led to a significant reduction of computational resources. This model enabled to investigate the aerodynamic phenomena observed from the nozzle inlet up to the processed surface. Design rules and the effect of changing nozzle parameters were identified. Sensitivity analysis highlighted that the throat diameter is the most critical parameter. A challenging power dissipation analysis of the plasma torch was carried out. Temperature and flow rate in key components of the torch were measured. Experimental results enabled to calculate the power dissipation values for RF power up to 800 W and for the entire series of designed nozzles. This work enabled to scientifically understand the power dissipation mechanism in the bespoke ICP torches. In addition, by comparing the intensity of the power dissipation values, one nozzle was clearly identified as being more capable to provide a highly efficient plasma jet.
18

Desenvolvimento de uma tocha de plasma híbrida para o processamento de materiais

Lermen, Richard Thomas January 2011 (has links)
O principal objetivo deste trabalho foi apresentar o projeto, o desenvolvimento, a caracterização e a aplicação de um novo dispositivo híbrido gerador de plasma. Este dispositivo consiste em uma tocha de plasma híbrida, a qual é caracterizada pela formação simultânea de dois arcos plasmas, em apenas um dispositivo, que geram um jato de plasma com elevada densidade de energia. Esta tocha é proveniente da união de dois processos geradores de plasma: Plasma Não-Transferido e Propulsor Magnetoplasmadinâmico. A tocha de plasma híbrida desenvolvida no Laboratório de Soldagem & Técnicas Conexas foi submetida aos seguintes testes: testes iniciais de funcionamento para verificar possíveis problemas de projeto e limites de operação da tocha; testes experimentais para caracterização da tocha de plasma híbrida, os quais consistiram em determinar as curvas características de tensão e corrente, o comprimento do jato de plasma, a distribuição de temperatura do jato de plasma expulso para fora da câmara, e a força propulsora resultante do jato de plasma; e testes de aplicação da tocha de plasma híbrida em processos de fabricação, tais como soldagem, corte e endurecimento superficial. Com base nos resultados obtidos para os testes de funcionamento do dispositivo, alguns problemas de isolamento elétrico e térmico foram encontrados e resolvidos. Quanto aos resultados dos testes de caracterização, os parâmetros de funcionamento da tocha de plasma híbrida apresentaram influência significativa sobre as curvas características de tensão e corrente, os comprimentos do jato de plasma, as forças propulsoras resultantes e as distribuições de temperatura. Os resultados obtidos nos testes de aplicação do dispositivo em processos de fabricação foram satisfatórios, isto é, foi possível realizar soldagens, cortes e endurecimento superficial com a tocha de plasma híbrida. Contudo, um novo dispositivo gerador de plasma foi desenvolvido para aplicações em processos de fabricação, porém novos estudos devem ser realizados para encontrar melhores parâmetros e assim conseguir soldagem, corte e endurecimento superficial com excelentes qualidades. / The main objective of this work was to present the project, development, characterization and application to a new hybrid plasma generator device. This device consists of a hybrid plasma torch that is characterized by the simultaneous formation of two plasma arcs in only one device, generating a plasma jet with high energy density. This torch arises from the union of two different plasma processes: Plasma Non-transferred and Magnetoplasmadynamic Thruster. The hybrid plasma torch developed in the Welding & Related Techniques Laboratory was submitted to the following trials: trials of operation to identify possible design problems and operations torch limits; trials to characterization of hybrid plasma torch that determined the characteristics curves of voltage and current, the length, the temperature distribution, and the thruster of the plasma jet; and application trials of hybrid plasma torch in manufacturing process, such as welding, cutting and hardening surface. Based at initial operation trials results with the device, some electrical and thermal insulation problems were found and solved. Concerning the results of the characterization trials, the hybrid plasma torch parameters had a significant influence over the voltage and current curves, the lengths of the plasma jet, the resultant thrusters and the temperature distributions. The results obtained in manufacturing process application trials were satisfactory, i.e. was possible to carry out welding, cutting and hardening surface with the hybrid plasma torch. However, a new plasma generated device was developed for application in manufacturing processes, but further studies should be performed to find the best parameters to acquire excellent qualities of welding, cutting and hardening surface.
19

A Study on the Application of Regional Innovative Systems of the Southeast Asia to the Practice in Greater Kaohsiung Area

Hung, Po-Yu 11 July 2011 (has links)
Economic growth has virtually dropped to depression era levels in recent years as the domestic economy was and is still being impacted by severe competition in the international market. With the competition in the markets of most industries, how can we deal with the different stressful challenges to gain a dominant position in regard to competitiveness? There are numerous factors preventing many domestic traditional industries from being transformed, such as: the lack of innovative technical knowledge and competence, the limited necessary funds for manpower and equipment, the restriction of our government¡¦s subsidy clauses, etc. Accordingly, industry holders still keep and run their existing traditional industries, thereby raising obstacles to the promotion of the regional innovative system. The key point to solve the problem is to raise the knowledge technology level for the regional industry clusters. How can our government¡¦s policy help to assist the related industries to form the clusters and practice regional balanced development? The goal is to raise innovation in the necessary technologies; only then can an enterprise¡¦s business be sustained. According to the above, industry clusters constitute an important key to promote industrial development. The regional innovative system emphasizes the reactions and flow among organizations, including government, academia, research organizations, intermediaries, the financial market, the information network, etc. The thriving growth in the domestic economy relies much on the strengthening of innovation policies regarding urban areas. This research will discuss Chinese, Japanese and Korean governments¡¦ achievements in regard to the policies concerning regional innovations and management. The aims of the discussion include the following: 1. Investigating these 3 governments¡¦ successful cases of their innovation policies and strategies of industry clusters, in order to offer the greater Kaohsiung area a reference for practicing an innovative system; 2. Applying the results of the successful cases as suggestions for domestic traditional industries; and 3. Through integrated comparisons and analysis, substantial suggestions and measures for future development are proposed for the interaction between industry and academia, the enforcement of the administrative management regulations of the central and regional governments, the clustering strategies, etc. In addition, new energy, new materials and high technology industries are advised as a direction for the overall industrial development in the greater Kaohsiung area. Finally, the issues of industrial pollution of the environment, increasing the employment opportunities, and the cross-region and cross-nation innovative interactions are also explored.
20

Diffusion In Porous Solids : Void Disorder, Orientation And Rotation, Reaction And Separation, And Levitation Effect

Anil Kumar, A V 12 1900 (has links)
Diffusion in bulk has been well studied and our understanding may be said to be adequate if not complete. Similarly, surface diffusion has been investigated by a number of workers and a fair understanding of it has emerged. When guest particles are confined within the micropores of solids such as zeolites, the resulting phase is neither bulk nor an adsorbed phase but something in between. Properties of such a phase have not been understood sufficiently. Such phase found within these porous solids display rich variety in their property. In part, such a variety arises from the large number of factors that determine their properties. Present thesis attempts to study the relationship of some of these factors, viz., the pore size and the disorder in the pore sizes, the sorbate sizes, the role of orienta-tional motion, the inhomogeneities in temperature etc. to diffusion of the guest molecules in porous solids. Chapter 1 gives a brief overview of the literature and the present understanding in the field of diffusion of spherical atoms and small molecules in microporous materials with special attention to zeolites.,The discussion is focussed on the experimental, theoretical and computer simulation results reported in the last few years. In chapter 2 an analytic expression is derived for the diffusion coefficient of a sorbate in a crystalline porous solid with bottlenecks. This is done by assuming a situation of quasiequi-Hbrium and by applying some elementary results of kinetic theory of gases. The diffusion coefficients obtained from the analytic expression is found to agree well with the molecular dynamics results. Further, it is found to reproduce the diffusion anomaly and its temperature dependence for different zeolites such as Y, A and p. The present calculations provide a strong theoretical support for the levitation effect obtained so far purely from molecular dynamics calculations. The computational effort involved in evaluating the derived expression is at least an order of magnitude less as compared to the molecular dynamics simulations. Levitation effect is found to exist in crystalline porous solids, irrespective of the geometry and topology of the void network of the host - the zeolite. Does levitation effect exist in non-crystalline porous solids where a distribution of pore sizes is seen instead of a single size? Chapter 3 attempts to answer this question via detailed molecular dynamics simulations on zeolite Y whose perfectly crystalline pore structure has been modified by introducing disorder. A normal distribution characterized by its width <TQ of 12-ring window diameters has been generated. Investigation of motion of spherical sorbates within such a disordered host suggests that levitation effect persists although the intensity of the anomalous peak is reduced compared to crystalline faujasite. Further, there is a breakdown of the linear relationship between the self-diffusivity D and 1 /^ where a99 is the sorbate diameter in the disordered host. Comparison of similarity between the effect of temperature and that of disorder are discussed. Chapter 4 investigates the role of orientation on diffusion of methane in zeolite NaCaA during intercage and intracage migration. In this work, diffusion of a five site model of methane within porous zeolite A has been investigated by molecular dynamics simulation. Methane exhibits interesting orientational preference during its passage through the 8-membered window, the rate determining step for overall diffusion: (2+2) (or scissor) orientation is preferred to (1+3) (or inverted umbrella) orientation. This suggests strong translational-orientational coupling. This is supported by ab initio mixed basis calculations thereby suggesting that the results are not a consequence of the classical potential employed. Partial freezing of certain rotational degrees of freedom is observed during the passage of methane through the 8-ring window. Intracage motion of methane shows that methane performs a rolling motion rather than a sliding motion within the supercage. In Chapter 5, diffusion of methane and neopentane through the pores of zeolite NaY has been investigated by means of molecular dynamics simulation. Intercage motion consisting of diffusion through 12-ring window of zeolite NaY is seen to occur with strong orientational preference for (2+2) orientation in the case of neopentane but not methane. Comparison of the result with methane diffusion through the 8-ring window of zeolite NaCaA reported in chapter 4 suggests that such a preferential orientation is a typical characteristic of systems whose levitation parameter is close to unity. Temperature dependence of translational-orientational coupling during the passage through the bottleneck has been obtained. As seen earlier, partial freezing of certain rotational degrees of freedom also exists. Little or no freezing is observed around the molecular axis of symmetry parallel to the vector, ft, perpendicular to the window plane since it does the orientation of the molecule with respect to fi. Analysis of intracage motion suggests existence of rolling motion in preference to sliding motion both in methane and neopentane. It is suggested that globular molecules show a predominance of rolling motion in comparison to anisotropic molecules such as benzene. Chapter 6 reports results from molecular dynamics(MD) simulations and its comparison to the quasi-elastic neutron scattering (QENS) measurements of the diffusion of propane, NaY zeolite, at different temperatures and at a relatively high loading. The contributions to S(Q, cu) from ballistic and diffusive motions are analysed. The self-diffusivity D has been calculated from mean squared displacement (MSD) as well as from the dynamic structure factor (S(Q,cu)) computed from the MD simulation. Both the values are consistent with each other. Also, they are in reasonable agreement with the experimental QENS results. The MD results indicate a fixed jump length diffusion process, whereas, the QENS data fits well to a jump diffusion model with a Gaussian distribution of jump lengths. Diffusion is often accompanied by a reaction or sorption which in turn can induce temperature inhomogeneities. In chapter 7 Monte Carlo simulations of Lennard-Jones atoms in zeolite NaCaA are reported for the presence of a hot zone presumed to be created by a reaction. Our simulations show that the presence of localized hot regions can alter both the kinetic and transport properties such as diffusion. An enhancement in diffusion coefficient is seen in the presence of a local hot spot. Further, the enhancement of the diffusion constant is greater for systems with larger barrier height, a surprising result that may be of considerable significance to many chemical and biological processes. We find an unanticipated coupling between reaction and diffusion due to the presence of hot or cold zone in addition to that which normally exists between them via concentration. Chapter 8 explores the possibility of exploiting a judicial combination of levitation effect and blow-torch effect for the separation of mixtures. In this study, Monte Carlo simulations have been carried out for three different binary mixtures in zeolite NaCaA with hot spot placed just before the position of the window along one direction. The binary mixture consisting of two types of particles both of which are from the linear regime does not separate well while the separation achieved of the mixture with one component from the linear regime and another from the anomalous regime is excellent. The separation factors obtained in the case of the latter mixture is more than an order of magnitude larger than that of the conventional separation methods. In the case of Ne-Ar mixture in NaCaA also, where Ne is in the linear regime and Ar is in the anomalous regime, the separation attained is excellent. These results suggest that a combination of levitation and blow-torch effects can be used to obtain extraordinary separation. Here the levitation effect specifies the sign and the magnitude of the energy barrier. The blow-torch drives the component in positive or negative direction depending on the energy barrier of the guest species. An appendix describes an additional but unrelated work carried out: a Monte Carlo study of the orthorhombic(fJ), monoclinic(ct) and liquid phases of toluene in the isobaric isothermal ensemble employing variable shape simulation cell. The structure has been characterized in terms of the radial distribution functions and orientational correlation functions. The transition from the orthorhombic low temperature (3-phase to the high temperature monoclinic cc-phase has been successfully simulated. The transition is first order and lies between 140 and 145K in agreement with experiment. The reverse transition from the a-to the (3-phase does not take place in agreement with experiment. The liquid phase density and the heat of vapourization are in good agreement with the experimental values.

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