Through collaborative efforts at Texas A&M University and Sandia National Laboratories, a crystalline silicotitanate (CST), which shows extremely high selectivity for radioactive cesium removal in highly concentrated sodium solutions, was synthesized. The effect of hydrogen peroxide on a CST under cesium ion exchange conditions has been investigated. The experimental results with hydrogen peroxide showed that the distribution coefficient of cesium decreased and the tetragonal phase, the major component of CST, slowly dissolved at hydrogen peroxide concentrations greater than 1 M. A simple and novel experimental apparatus for a single-layer ion exchange column was developed to generate experimental data for estimation of the intraparticle effective diffusivity. A mathematical model is presented for estimation of effective diffusivities for a single-layer column of CST granules. The intraparticle effective diffusivity for Cs was estimated as a parameter in the analytical solution. By using the least square method, the effective diffusivities of 1.56 ± 0.14 x 10-11 m2/s and 0.68 ± 0.09x 10-11 m2/s, respectively, were obtained. The difference in the two values was due to the different viscosities of the solutions. A good fit of the experimental data was obtained which supports the use of the homogeneous model for this system. A counter-current ion exchange (CCIX) process was designed to treat nuclear waste at the Savannah River Site. A numerical method based on the orthogonal collocation method was used to simulate the concentration profile of cesium in the CCIX loaded with CST granules. To maximize cesium loading onto the CST and minimize the volume of CST, two design cases of a moving bed, where the fresh CST is pulsed into the column at certain periods or at certain concentration of cesium, were investigated. Simulation results showed that cesium removal behavior in the pilot-scale test of CCIX experiment, where the column length is 22 ft and the CST is pulsed 1 ft in every 24 hours, was well predicted by using the values of the effective diffusivities of 1.0 to 6.0 × 10-11 m2/s.

This thesis sets out to examine the proposal that, by using tomography and gas sensing techniques to detect and image gas concentration in fast moving flows, engineers can improve the combustion diagnostics and emissions performance of gas turbines, enabling a better understanding of combustion and design optimisation of greener engines. The key factor is the combination of tomography with Tunable Diode Laser Absorption Spectroscopy (TDLAS) gas sensing technology, implemented simultaneously along many beams, to image the gas concentration distribution in the exhaust plume of a gas turbine, in a plane perpendicular to the plume flow direction. The target gas species is carbon dioxide, CO2, and the absorption feature chosen is at a wavelength of 1997.2 nm. The narrow spectral absorption properties of such small molecules present a considerable challenge for a multi-beam tomographic implementation. Moreover, the design, oriented to harsh and industrial environments, presents key challenges for the design of robust optics and electronics for the collection of reliable data. The development of a 126-beam tomography system required the investigation of recently developed TDLAS techniques and their compatibility with data acquisition (DAQ) system firmware strategies to be implemented by custom DAQ electronics. A novel FPGA-based single channel TDLAS CO2 detection system has been designed and built to demonstrate the feasibility for the replication of 126-channels in the full system. Further proof-of-concept experiments carried out at full scale have produced tomographic images of phantom CO2 distributions that demonstrate the utility of the CST technique.

This diploma thesis is aimed at radar cross section of passenger cars. Basic scattering parameters of simple targets are described. Some numeric methods used for computing radar cross section are discussed. CST Microwave Studio is used for simulation of passenger car with two different solvers. For the results there are plots of radar cross section of a car for 1 GHz, 24.125 GHz and 33 GHz. There is a plot of visualized hotspots.

This thesis deals with RFID tags design. It comprises an overview of the RDIF technology while focusing upon the passive tags in UHF band. The CST Microwave studio software has been used for draft simulations. The resulting tags have been subjected to parameter measuring – the reflection coefficient, the minimum capacity needed to switch on the tag, the maximum reading distance. The influence of the proximity of metal objects and other materials has also been examined.

京都大学 / 0048 / 新制・課程博士 / 博士(生命科学) / 甲第20100号 / 生博第360号 / 新制||生||48(附属図書館) / 33216 / 京都大学大学院生命科学研究科統合生命科学専攻 / (主査)教授 石川 冬木, 教授 上村 匡, 教授 松本 智裕 / 学位規則第4条第1項該当 / Doctor of Philosophy in Life Sciences / Kyoto University / DFAM

Neste trabalho apresenta-se um elemento finito de casca plano que é obtido pela composição de um elemento de placa com um de membrana. O elemento de placa usado, o DKT (Discrete Kirchhoff Theory), pertence à classe dos elementos triangulares com nove graus de liberdade (uma translação e duas rotações por nó), e é obtido pela imposição da hipótese de Kirchhoff nos seus pontos nodais. Para o elemento de membrana, usou-se o elemento CST (Constant Strain Triangle), com seis graus de liberdade (duas translações por nó). O elemento finito resultante DCT, possui dezoito graus de liberdade (três translações e três rotações, sendo uma das rotações fictícia- no plano do elemento). Simples exemplos de placa e chapa no espaço foram analisados para se testar o elemento, e finalmente uma casca cilíndrica uniformemente carregada foi analisada e o resultado obtido comparado com o fornecido por outros autores. Neste estudo, o elemento DKT mostrou-se eficiente na análise de cascas. / This work presents a flat shell finite element composed of plates in bending and in tension finite elements. The bending element used, the DKT (Discrete Kirchhoff Theory) belongs to the class of triangular elements with nine degrees of freedom (the transverse displacement and its derivatives at each node) and it is obtained from the theory of plates with shear force influence with Kirchhoff hypothesis imposed in the nodes of the element. The tension finite element is the well known CST (Constant Strain Triangle) with six degrees of freedom (the displacement u and v at each node). The resulting finite element, called DCT, has 18 degrees of freedom, including an extra and fictitious rotation in the normal direction to the surface of elements. Single plates in bending and in tension described in a tridimensional system of coordinates were analyzed to test the adopted finite elements and finally cylindrical shell uniformly loaded were analyzed and the results compared with those of authors. In the work the DKT element shown to be a reliable finite element to be used in shell analysis.

Neste trabalho apresenta-se um elemento finito de casca plano que é obtido pela composição de um elemento de placa com um de membrana. O elemento de placa usado, o DKT (Discrete Kirchhoff Theory), pertence à classe dos elementos triangulares com nove graus de liberdade (uma translação e duas rotações por nó), e é obtido pela imposição da hipótese de Kirchhoff nos seus pontos nodais. Para o elemento de membrana, usou-se o elemento CST (Constant Strain Triangle), com seis graus de liberdade (duas translações por nó). O elemento finito resultante DCT, possui dezoito graus de liberdade (três translações e três rotações, sendo uma das rotações fictícia- no plano do elemento). Simples exemplos de placa e chapa no espaço foram analisados para se testar o elemento, e finalmente uma casca cilíndrica uniformemente carregada foi analisada e o resultado obtido comparado com o fornecido por outros autores. Neste estudo, o elemento DKT mostrou-se eficiente na análise de cascas. / This work presents a flat shell finite element composed of plates in bending and in tension finite elements. The bending element used, the DKT (Discrete Kirchhoff Theory) belongs to the class of triangular elements with nine degrees of freedom (the transverse displacement and its derivatives at each node) and it is obtained from the theory of plates with shear force influence with Kirchhoff hypothesis imposed in the nodes of the element. The tension finite element is the well known CST (Constant Strain Triangle) with six degrees of freedom (the displacement u and v at each node). The resulting finite element, called DCT, has 18 degrees of freedom, including an extra and fictitious rotation in the normal direction to the surface of elements. Single plates in bending and in tension described in a tridimensional system of coordinates were analyzed to test the adopted finite elements and finally cylindrical shell uniformly loaded were analyzed and the results compared with those of authors. In the work the DKT element shown to be a reliable finite element to be used in shell analysis.

Absolicon Solar Collector AB in Härnösand, Sweden, develops concentrating solar collectors with a parabolic trough. In the solar collector trough, there is thermal loss due to convection. A convection suppressor was made and used as a method to reduce thermal loss due to convection in the trough. The objective of the project was to evaluate the convection suppressor for solar collectors with a parabolic trough and its impact on the performance (thermal loss characteristics) in two different orientations of the trough, horizontal and inclined. The performance of the solar collector was first measured without the convection suppressor; these results were compared to two previous quasi-dynamical tests of the solar collector performance made by two different institutes, Research Institute of Sweden and SPF Institut für Solartechnik (Switzerland). The comparison was made to validate the test results from the tests without the convection suppressor, which matched. Secondly, when the convection suppressor was made and tested in the two different orientations, the results of the performance with and without the convection suppressor was evaluated as well as the convection suppressor itself. The results showed a significant improvement of the solar collector performance in the aspect of reduced thermal loss when the convection suppressor was used, hence higher efficiency. / Absolicon Solar Collector AB I Härnösand, Sverige, utvecklar koncentrerande solfångare med ett paraboliskt tråg. I solfångarens tråg uppstår termiska förluster som en följd av konvektion. En konvektionsreducerare tillverkades och användes som metod för att minska de termiska förlusterna i tråget. Målet med projektet var att testa och utvärdera konvektionsreduceraren för koncentrerande solfångare med ett paraboliskt tråg samt dess inverkan på verkningsgraden i två olika positioner för tråget, horisontell och lutande. För att kunna mäta konvektionsreducerarens inverkan på solfångaren mättes först solfångarens prestanda utan konvektionsreduceraren i de två olika positionerna, detta resultat användes som referens efter validering. Valideringen gjordes genom att resultatet jämfördes sedan med två andra prestandamätningar (quasi-dynamical test) av solfångaren gjorda av två olika institut, Research Institute of Sweden och SPF Institut für Solartechnik (Schweiz). Därefter, när konvektionsreduceraren var tillverkat och testad i de olika positionerna på samma sätt som mätningarna utan konvektionsreducerare, jämfördes resultaten med och utan konvektionsreducerareet samt att en utvärdering gjordes av dess inverkan. Resultatet visade en signifikant förbättring av solfångarens prestanda i form av minskade termiska förluster när konvektionsreduceraren användes och därav ökad verkningsgrad.

Les antennes reconfigurables offrent de multiples fonctions en changeant dynamiquement leurs propriétés telles que la fréquence de fonctionnement, la polarisation, le diagramme de rayonnement ou toute combinaison de ces trois paramètres. Leur agilité et leur diversité créent de nouvelles possibilités d'applications pour les systèmes radio tels que les réseaux locaux, les liaisons par satellite et notamment la radio cognitive. Dans cette thèse, deux antennes reconfigurables en fréquence fonctionnant dans les bandes des standards sans fil actuels ont été proposées. Elles sont basées sur la modification de la géométrie du patch rayonnant. Leurs dimensions ont été optimisées par algorithmes génétiques embarqués et combinés à un logiciel de simulation électromagnétique. La commande de la reconfiguration de ces antennes est réalisée à l'aide d'un microcontrôleur qui pilote l'état des commutateurs (des diodes PIN). De ce fait, un système d'antenne reconfigurable intelligent dédié à la radio cognitive a été développé. / Reconfigurable antennas offer multiple functions by dynamically changing their properties such as operating frequency, polarization, radiation pattern, and a combination of all these factors. Their agility and diversity create a wide range of different and new applications for radio systems such as local networks, satellites, and especially in cognitive radio. In this thesis, two new frequency reconfigurable antennas are proposed. The frequency reconfiguration is obtained by changing the geometry of radiating patch. Their dimensions have been optimized by genetic algorithm embedded in the electromagnetic simulation software. These antennas operate at the frequency band for IEEE 802.11b/g standard with satisfactory radiation characteristics. This thesis also presents a method of controlling the operation of the frequency reconfigurable antenna by a micro-controller. The operation of electronic switches (PIN diodes) are carried out through programs which allows an adaptive operating system like smart antennas and work well in cognitive radio environment.

Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2008. / This study investigates high frequency probes through good metrology and computation software such as CST. A factor that can strongly influence the accuracy of measurements, is common mode (CM) current. Therefore, the main focus of this project was the CM current on the outside of an SMA, flanged, probe used for measuring material properties. In the course of the investigation, a clamp-on CM current probe (CP) was calibrated using a CST model and good measurements. This calibration data indicated that the CP was invasive on the measurement setup and could not deliver the accuracy required for the CM current measurement. In light of this, a second method was implemented where the material probe was placed within a cylindrical shield. A cavity was formed between the probe and the walls of the shield in which the electric fields could be simulated and measured. These field measurements allowed measurements to be conducted in both the time- (TD) and frequency-domain (FD). For the TD measurements, a sampling oscilloscope was used. As the basic principle of a sampling oscilloscope differs from its real-time counterpart, this principle, as well as the systematic errors associated with these devices, was explored. The results of the final measurements indicated that the TD results were within an acceptable range of both the FD results, measured on the VNA, and the results predicted by CST. This study shows that CST can be used to simulate complex measurement setups and deliver reliable results in cases where an accurate measurement cannot be guaranteed.