Hydrogen sulfide is toxic by-product of many petroleum, petrochemical and mineral treatment operations. Due to the increasing stringent environment regulations, toxic H2S must be completely removed from industrial waste gases before venting to the atmosphere. The H2S decomposition reaction is a well known thermodynamically limited reaction. Alumina membrane fixed bed catalytic reactors offer the potential for improved conversions at reduced operating temperature due to product separation and catalyst activity. A theoretical and experimental work dealing with a packed bed membrane reactor is the subject of this thesis. A tubular alumina membrane reactor possessing thermal and corrosion resistance has been developed. A multicomponent permeation study indicated that the fluxes of gases could be quantitatively described as a combination of Knudsen diffusion and viscous flow through the porous alumina membrane. The catalytic decomposition of hydrogen sulfide to hydrogen and sulfur was conducted in membrane reactor incorporating a commercial porous alumina membrane in combination with catalytic function of bimetallic RuMo sulfide catalyst. The obtained results demonstrate the possibility of achieving conversion above the equilibrium conversion. The reaction rate is equal to the intrinsic rate since both internal/external mass transfer and heat transfer resistance are negligible for the size of catalyst particles considered. Results obtained with this system have shown a maximum of 2.3 times the equilibrium conversion at the operating temperature 983K, which was equivalent to the conversion at operating temperature 1200K in a conventional fixed bed reactor. The conversion enhancement was significant for the operation with high sweep to feed molar ratio. The reactor configuration of membrane reactor appeared to have an influence on its performance. Comparative experimental and simulation study showed that the cocurrent mode gave slightly higher conversion over counter-current mode. Mathematical models were developed for the reactor, based on plug flow behavior. Simulation had been performed in order to validate the model against experimental data. Reactor optimization was carried out using the validated model. The simulation results from the non-isothermal model were in reasonable agreement with the experimental data. On the other hand, the isothermal model which neglected heat effects that took place in the reactor, has leaded to over-predicted conversion. This study also illustrated that predictive simulations could be used to explore the effects of recycle operation; the optimization study showed that the alumina membrane reactor permitting retentate recycle, could achieve up to 48.6% conversion, corresponding to 6 folded of the equilibrium conversion. The simulations provide a logical methodology for experimental planning and design. To further elucidate the effect of reactor configuration, operation conditions and permeation parameters on the performance of membrane reactors, a high permselective Pt-composite MR model was developed. Comparison of alumina MR and Pt-composite MR was carried out via computer simulation. Porous membrane reactor with higher permeability but lower Permselectivity can attain comparable conversion as the composite membrane reactor with higher permselectivity but lower permeability. Ptcomposite MR was more superior to alumina MR without recycle. Retentate recycle in alumina MR is shown to outperform the Pt-composite MR. Alumina MR was therefore considered as potential candidate for industrial H2S treatment.

Corrigenda pasted onto back end-paper. / Bibliography: leaves 340-355. / xxvi, 380 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this thesis is to develop a mathematical model for the optimum design of pressure irrigation systems. Section I deals with models in which a fixed layout for the piping systems is considered and the enumeration approach is utilised and Section II considers models in which the piping layout is not fixed and the genetic algorithm is utilised as a relatively new approach to optimisation problems. / Thesis (Ph.D.)--University of Adelaide, Dept. of Civil and Environmental Engineering, 1996

R. Akella, P.R. Kumar. / Bibliography: p. [37] / "January 1985." / "N.S.F. Grant ECS-8304435" "...U.S. ARO...Contract DAAG-29-84-K0005"

Thesis (Diploma (Electrical Engineering))--Cape Technikon, 1983. / The Coastal Engineering and Hydraulics Division of the National Research Institute for Oceanology (NRIO) undertakes research projects so as to be able to supply specialised expertise and consultancy services in coastal engineering with special reference to the needs in South Africa. Physical models of harbours, beaches, etc. are built at NRIO and are used mainly for sediment and breakwater studies. To collect the vast amount of data in the tests done on these models a Model Hall Data Acquisition System, MHDAS, was developed (Holroyd, 1980) to provide a data-logging facility and also to provide the control signals required to co-ordinate model operation and thus permit automatic model testing.

The development of connected and automated vehicle (CAV) technologies motivate modeling efforts and studies to understand CAVs' collective behaviors on public roads. In this thesis, we study CAV traffic flows through macroscopic models under two mathematical frameworks: the nonlocal conservation laws and the mean field games.The nonlocal conservation law models incorporate traffic information in a nonlocal range into each vehicle's driving control. We study one such model with a finite spatial nonlocal range, and demonstrate that proper use of the nonlocal information will offer better traffic stability. We also discuss numerical computation of the model that is robust under the changes of the nonlocal range. The mean field game models consider strategic interactions between CAVs, assuming each vehicle anticipates future traffic conditions and plans its driving control to minimize a predefined driving cost. A systematic approach is developed to derive the model, solve the model, and test the equilibrium solution. We take this approach in several traffic scenarios for CAVs on a single road or on a network, and demonstrate that proper design of the CAV driving cost function can lead to more efficient and stable traffic flows than human traffics. The established results in the thesis will bring more mathematical understandings on the proposed and studied models. The results may also provide insights on how to utilize the vehicle connectivity and automation to improve the overall traffic, and help to the CAV driving algorithm design.

No description available.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 1980 / Vita. / Includes bibliographical references. / by Michael Benjamin Packer. / Ph. D. / Ph. D. Massachusetts Institute of Technology, Department of Mechanical Engineering

No description available.

In product design, tolerances are specified due to the inherent variabilities of manufacturing processes. Tolerance specifications have significant implications on the quality and cost of the product. For proper tolerance specification, tolerance analysis must be performed. Prototyping is the the only method available for the analysis of the product geometric variations. For the automation of the analysis procedure, the part tolerance information must be represented in a format suitable for computer interpretation. Previously proposed tolerance representation schemes have suffered either from inadequate variational coverage or departure from the established ANSI tolerancing standards. Toward this end, a tolerance representation scheme capable of modeling the range of tolerances defined in the ANSI Y14.5 standard in a format suitable for automated tolerance analysis has been proposed. One unique feature of this representation scheme is the use of B-splines for the modeling of form variations. The representation scheme can also take into account the distribution characteristics of the manufacturing processes used to enable statistical tolerance analysis. To provide an accurate characterization of the variational form characteristics of the manufactured part features, the use of process capability templates was introduced. For assembly tolerance analysis, a relative positioning scheme capable of modeling the interaction between mating splines was developed to propagate the individual part variations within the assembly. This enabled the tolerance stackup on the assembly design function(s) to be computed automatically without the need to formulate any tolerance functions. A prototype software, written in the C++ programming language and running from within CATIA, has been developed to demonstrate the integration of the above concepts. / Ph. D.

Reliability and availability measures are well defined for simple systems, but many real systems are not simple. Many systems are designed to perform more than one task. In addition, these systems may be performing at one of many levels. When these factors are not considered, the system availability analysis changes considerably. Many modern systems are designed to perform more than one function. Sols (1992) and Sols and Nachlas (1993) discuss the importance of multifunctional systems and the need to redefine availability to accommodate them. Furthermore, in most traditional reliability theory, components are assumed to be either functioning or failed which oversimplifies many physical situations. Multistate models have been developed in the literature, and conditions for the system structure function have been defined. Multifunctional systems and systems with multistate components have been discussed in the literature individually, however a model for systems with both multifunctional capability and potentially degraded components has not been discussed. By synthesizing the previous work on multistate systems and on multifunctional systems, this research presents a general model for multifunctional, multistate systems. The model is specialized to a general class of multifunctional, multistate systems. Expressions are derived for the element, function, and system availability. The availability for an example system is then computed. / Master of Science