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Chemical engineering

Retrospective Theses and Dissertations

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Full-Text Articles in Engineering

Synthesis And Characterization Of Stimuli Responsive Block Copolymers, Self-Assembly Behavior And Applications , Michael Duane Determan Jan 2006

Synthesis And Characterization Of Stimuli Responsive Block Copolymers, Self-Assembly Behavior And Applications , Michael Duane Determan

Retrospective Theses and Dissertations

Water-soluble stimuli responsive block copolymers are a rapidly emerging class of materials with great potential in biomedical and technological applications. In this work a novel class of pentablock copolymers are synthesized via atom transfer radical polymerization techniques and their stimuli-responsive self-assembly properties are characterized. Aqueous solutions of these materials are observed to form micelles and hydrogels in response to changes in both temperature and pH. Cryogenic transmission electron microscopy (cryo-TEM) and small angle neutron and X-ray scattering (SANS and SAXS) techniques are used to investigate the nanoscale structures formed by these pentablock copolymers in solution. The gel structure and mechanical ...


Continuous-Time Block-Oriented Nonlinear Modeling With Complex Input Noise Structure , Dongmei Zhai Jan 2005

Continuous-Time Block-Oriented Nonlinear Modeling With Complex Input Noise Structure , Dongmei Zhai

Retrospective Theses and Dissertations

The continuous-time closed-form algorithms to sinusoidal input changes are proposed and presented for single-input, single-output (SISO) Hammerstein and Wiener systems with the first-order, second-order, and second-order plus lead dynamics. By simulation on theoretical Hammerstein and Wiener systems, the predicted responses agree exactly with the true process values. They depend on only the most recent input change. The algorithms to SISO Hammerstein and Wiener systems can be conveniently extended to the multiple-input, multiple-output (MIMO) systems as shown by the two-input, two-output examples and demonstrated by the simulated seven-input, five-output continuous stirred tank reactor (CSTR). The predictions and the simulated theoretical responses ...


Synthesis And Characterization Of Nanostructured Aluminas , Weihua Deng Jan 2005

Synthesis And Characterization Of Nanostructured Aluminas , Weihua Deng

Retrospective Theses and Dissertations

In the work, mesoporous aluminas were produced by nonionic supramolecular templating and characterized to determine the stability of their physical structure during extended calcination at elevated temperatures. The effect of synthesis temperature on the physical structure of these materials and the resulting thermal evolution from synthesized aluminum hydroxide to transitional alumina was studied using thermogravimetric analysis. A high resolution multiple quantum magic angle spinning NMR spectroscopy method was used to determine quantitatively the evolution of the aluminum coordination during the thermal processing. The mesoporous alumina exhibited high stability upon prolonged heating, which is essential for their future applications in catalytic ...


Combinatorial Synthesis And Screening Of Fuel Cell Catalysts , Shrisudersan Jayaraman Jan 2004

Combinatorial Synthesis And Screening Of Fuel Cell Catalysts , Shrisudersan Jayaraman

Retrospective Theses and Dissertations

Polymer electrolyte membrane fuel cells (PEMFCs) are compact power sources that can operate with high efficiencies and low emission of environmentally harmful gases. One of the major barriers impeding the development of PEMFCs as a competitive energy source is the inability of existing anode catalysts to oxidize fuels other than hydrogen at sufficient levels due to catalyst deactivation by carbon monoxide (CO) and other partial oxidation products. The focus of this research is the development and application of combinatorial strategies to construct and interrogate electrooxidation (anode) catalysts pertaining to PEMFCs to discover catalysts with enhanced performance in catalyst deactivating environments ...


Theoretical And Experimental Explorations In Atomic Force Microscopy , Anil Gannepalli Jan 2004

Theoretical And Experimental Explorations In Atomic Force Microscopy , Anil Gannepalli

Retrospective Theses and Dissertations

Nanotechnology is the capability to build by controlling the arrangement of individual atoms and molecules. Such a technology would be founded on the ability to control, manipulate and investigate matter at the atomic scale. The invention of atomic force microscope (AFM) and the advances in micro-cantilever based scanning probe technology have significantly enhanced the experimental capability to probe and modify matter at the nanoscale. However, it is still severely limited in achieving the necessary bandwidth, sensitivity and resolution. To further the advances in this field an in-depth understanding of the nature and effects of the tip-sample interactions is imperative. A ...


Hybrid Finite-Volume/Transported Pdf Method For The Simulation Of Turbulent Reactive Flows , Venkatramanan Raman Jan 2003

Hybrid Finite-Volume/Transported Pdf Method For The Simulation Of Turbulent Reactive Flows , Venkatramanan Raman

Retrospective Theses and Dissertations

A novel computational scheme is formulated for simulating turbulent reactive flows in complex geometries with detailed chemical kinetics. A Probability Density Function (PDF) based method that handles the scalar transport equation is coupled with an existing Finite Volume (FV) Reynolds-Averaged Navier-Stokes (RANS) flow solver. The PDF formulation leads to closed chemical source terms and facilitates the use of detailed chemical mechanisms without approximations. The particle-based PDF scheme is modified to handle complex geometries and grid structures. Grid-independent particle evolution schemes that scale linearly with the problem size are implemented in the Monte-Carlo PDF solver. A novel algorithm, in situ adaptive ...


Interdiffusion Phenomena At Partially Miscible Polymer Interfaces , Erin Lynne Jablonski Jan 2002

Interdiffusion Phenomena At Partially Miscible Polymer Interfaces , Erin Lynne Jablonski

Retrospective Theses and Dissertations

This research is focused on understanding the effect of miscibility on interdiffusion phenomena in bilayers of polystyrene (PS) and the statistically random copolymer, poly (styrene-r-4-bromostyrene) (PBS). Miscibility in such systems can be quantified by N*chi, where N* is an effective degree of polymerization and chi the Flory-Huggins interaction parameter. In the PS/PBS system, miscibility decreases as N *chi increases. The extent of interdiffusion at a bilayer interface is ultimately determined by the miscibility of the system. A description of the effect of miscibility on interdiffusion phenomena, interfacial width, phase behavior, and fracture energy and a relationship between these ...


Investigation Of The Peroxovanadate Sol-Gel Process And Characterization Of The Gels , Craig Joseph Fontenot Jan 2001

Investigation Of The Peroxovanadate Sol-Gel Process And Characterization Of The Gels , Craig Joseph Fontenot

Retrospective Theses and Dissertations

Vanadium oxide gels derived from aqueous solution of V2O 5 and H2O2 have been investigated using in situ 51V NMR and laser Raman spectroscopic techniques. On the basis of this characterization, a pathway for peroxovanadate decomposition has been proposed, including the presence of two peroxovanadate dieters. New Raman bands and assignments for these species are reported. Experimental 51V NMR evidence suggested the VO2+ species was directly involved in the formation of the gel. The vanadia xerogels were studied using 51V and 17O MAS NMR, 17 O 3QMAS NMR, TGA, DSC, XRD, SEM and laser Raman spectroscopy. Based primarily on the ...


Study Of Transport And Dissolution Of A Nonaqueous Phase Liquid In Porous Media: Effects Of Low-Frequency Pulsations And Surfactants , Mirrya Mosier Fontenot Jan 2001

Study Of Transport And Dissolution Of A Nonaqueous Phase Liquid In Porous Media: Effects Of Low-Frequency Pulsations And Surfactants , Mirrya Mosier Fontenot

Retrospective Theses and Dissertations

The transport and dissolution of residual non aqueous phase liquids (NAPLs) trapped in water saturated porous media is a problem pertinent to both environmental and petrochemical industries. In this work we have quantitatively examined the complete dissolution of residual entrapped NAPL at the pore-scale in three dimensions using refractive index matching techniques along with planar laser induced fluorescence. The results yielded pore-scale information regarding ganglia volume, surface area, and position over time at various Capillary numbers. We found that with increasing Capillary numbers, the time for total dissolution decreased. In addition, it appears that large ganglia exhibit fractal area to ...


Development And Scale-Up Of Particle Agglomeration Processes For Coal Beneficiation , Meiyu Shen Jan 1999

Development And Scale-Up Of Particle Agglomeration Processes For Coal Beneficiation , Meiyu Shen

Retrospective Theses and Dissertations

The development of two modified agglomeration processes for coal beneficiation is presented separately in Parts I and II of this dissertation. Part I is based on research which was conducted to study the mechanism and characteristics of a gas-promoted oil agglomeration process. Part II is based on research which was carried out to develop a newer and more innovative method for agglomerating coal particles with microscopic gas bubbles in aqueous suspensions;In Part I, the development of a gas-promoted oil agglomeration process for cleaning coal was carried out with scale model mixing systems in which aqueous suspensions of ultrafine coal ...


Metal Cluster Hydrodesulfurization Catalysts Based On Ternary Molybdenum Sulfides , Robert Kirk Thompson Jan 1999

Metal Cluster Hydrodesulfurization Catalysts Based On Ternary Molybdenum Sulfides , Robert Kirk Thompson

Retrospective Theses and Dissertations

Catalysts based on metal sulfide cluster compounds such as Chevrel phases (MxMo6S8) have been shown to possess high activity and selectivity for hydroprocessing reactions. Previous methods of preparing crystalline Chevrel phases have involved high temperature, solid-state synthetic routes which produce low surface area materials (0.1--1.0m2/gm). In our recent research, lower temperature syntheses via solution precursors have been explored as routes to these materials. The discovery of a new class of compounds, M2x/n n+(Mo6S8)Sx (n = 1--3) has resulted. These new reduced ternary molybdenum sulfides have been shown to have both high activity and selectivity in ...


Development Of An Empirical Model Of Human Sweating And A Semi-Empirical Model Of Human Thermoregulation , Jennifer Jane Walker Jan 1999

Development Of An Empirical Model Of Human Sweating And A Semi-Empirical Model Of Human Thermoregulation , Jennifer Jane Walker

Retrospective Theses and Dissertations

The physiology of the human thermoregulatory response to changes in environment and work load has been studied from the perspective of both the physiologist and the engineer. Both fields have brought certain skills and tools to the effort. An effort to bring together the understanding gained from these two perspectives has been lacking. In this work a model for the sweat response and a model for the thermoregulatory response to changes in room temperature were developed. These models were developed using the modeling tools of engineering and the knowledge contained in past experimental data;An empirical model of the sweat ...


Triphase Catalysis: Mass Transfer And Kinetic Studies , Holger Jürgen Glatzer Jan 1999

Triphase Catalysis: Mass Transfer And Kinetic Studies , Holger Jürgen Glatzer

Retrospective Theses and Dissertations

The importance of phase transfer catalysis (PTC) in the production of high value chemicals has grown immensely over the past few years. PTC may be a suitable method to synthesize a product whenever each reactant is miscible in a different phase. By addition of a PT catalyst, which functions as a ferrying agent between the phases, significant rate enhancements can be achieved;The PT catalyst (e.g. a quaternary ammonium salt) is usually used in soluble form. Alternatively, it can be bound to a solid support. The latter technique is called triphase catalysis (TPC). It has operational advantages over conventional ...


A Knowledge-Based Approach For Data Reconciliation Of Process Networks , Maria Victoria Balagat Bascuñana Jan 1999

A Knowledge-Based Approach For Data Reconciliation Of Process Networks , Maria Victoria Balagat Bascuñana

Retrospective Theses and Dissertations

Because the area of gross error detection and data reconciliation has received a significant amount of attention in the past two decades, the problem is fairly well-defined but the solutions have yet to be perfected. Also, despite the proliferation of new methods that offer particular strengths and the potential economic value of this data analysis step, it has not been as widely performed in chemical manufacturing plants because of the difficulties, both mathematical and instrumental, that plant operators encounter. Hence, the focus of this dissertation is the simplification of the gross error detection and data reconciliation problems at hand using ...


Process Analysis And Yield Enhancement For The Production Of Beta-Hydroxy-Beta-Methyl-Butyrate (Hmb) , George Barac Jan 1998

Process Analysis And Yield Enhancement For The Production Of Beta-Hydroxy-Beta-Methyl-Butyrate (Hmb) , George Barac

Retrospective Theses and Dissertations

The purpose of this work was to develop an optimum chemical process philosophy for the manufacture of [beta]-hydroxy-[beta]-methyl-butyrate (HMB), using existing synthesis and purification schemes as a starting point. Process analysis and improvement were performed as a means to increase overall efficiency and to address environmental concerns;A protein breakdown suppresser, HMB is used as a nutritional supplement or as a feed additive. The current process which employs reaction of diacetone alcohol and sodium hypochlorite, separation of the product by batch extraction, and crystallization, displays very low efficiency and has to deal with waste disposal issues. Currently ...


A Kinetic Study On The Adsorption And Reaction Of Hydrogen Over Silica-Supported Ruthenium And Silver-Ruthenium Catalysts During The Hydrogenation Of Carbon Monoxide , David Paul Vanderwiel Jan 1998

A Kinetic Study On The Adsorption And Reaction Of Hydrogen Over Silica-Supported Ruthenium And Silver-Ruthenium Catalysts During The Hydrogenation Of Carbon Monoxide , David Paul Vanderwiel

Retrospective Theses and Dissertations

An interesting phenomenon in bimetallic catalysis is the synergistic effect between two metals during CO hydrogenation. For example, addition of Ag to Ru catalysts results in a dramatic decrease in the specific activity of the catalyst, even though Ag alone does not appreciably adsorb H2 or CO. A series of Ag-Ru/SiO2 catalysts containing 0, 3, 10, 20 and 30 atomic percent silver was used to examine the kinetics of the adsorption and reaction of H2 on Ru during CO hydrogenation. CO was saturatively adsorbed at room temperature on each catalyst, followed by subsequent reaction with ambient H2 at 460 ...


Sonochemical Reactions: Mass Transfer And Kinetic Studies Of A Solid-Liquid System , Leigh Christine Hagenson Jan 1997

Sonochemical Reactions: Mass Transfer And Kinetic Studies Of A Solid-Liquid System , Leigh Christine Hagenson

Retrospective Theses and Dissertations

Ultrasound has been shown to have desirable effects on both homogeneous and heterogeneous reactions, such as increasing the conversion, enhancing the selectivity, and improving the yield. Enhancements due to ultrasound may be attributed to chemical effects or mechanical effects, or to both simultaneously. The chemical effects of ultrasound are attributed to the implosion of microbubbles, generating free-radicals with a great propensity for reaction. Mechanical effects are caused by shock waves formed during symmetric cavitation, or by microjets formed when the bubble implodes asymmetrically. Research emphasis in this area attempts to discern the mechanisms behind ultrasound's mechanical effects by selecting ...


New Approaches For Identification Of Systematic Measurement Errors In Linear Steady State And Dynamic Processes , Sriram Devanathan Jan 1997

New Approaches For Identification Of Systematic Measurement Errors In Linear Steady State And Dynamic Processes , Sriram Devanathan

Retrospective Theses and Dissertations

In this work three new methods are presented for improved identification of measurement biases in linear and nonlinear pseudo steady state processes. In addition to these methods, a new method is outlined for identification of biases in dynamic processes;The first method makes use of information contained in the relationship between individual measurements and the corresponding nodal balance. The performance of this method is demonstrated on a problem from the literature that has proved difficult for earlier methods. Additionally, this work discusses how the new technique can be used as a visual monitoring tool for identifying biased measured variables;The ...


Turbulent Scalar Transport Using Two-Point Statistical Closure Theory , Robert Charles Sanderson Jan 1995

Turbulent Scalar Transport Using Two-Point Statistical Closure Theory , Robert Charles Sanderson

Retrospective Theses and Dissertations

The turbulent transport of a passive scalar (Corrsin's problem with diffusion) and of an active scalar in stably stratified fluids is studied using linear analysis (rapid distortion theory or RDT), Kraichnan's direct interaction approximation (DIA) and direct numerical simulation (DNS). The results are compared with each other and with laboratory experiments. The numerical results compare favorably with the experiments of Sirivat and Warhaft, Budwig, Tavoularis and Corrsin and Stillinger and Itsweire of van Atta's group. The RDT study reveals that much of the qualitative behavior observed in experiments, such as the tendency for the system to evolve ...


Surface Properites Of Coal And Their Effects On The Selective Oil Agglomeration Process , Xiaoping Qiu Jan 1992

Surface Properites Of Coal And Their Effects On The Selective Oil Agglomeration Process , Xiaoping Qiu

Retrospective Theses and Dissertations

The heat of immersion of coal in water and various organic liquids provides a useful means for characterizing the surface of the material, while the oil-water-coal, three-phase contact angle provides a characterization of the coal surface as well as the interactions among oil, water, and coal. Such characterizations may provide an indication of how well the coal will respond to cleaning by the froth flotation and oil agglomeration methods which are controlled by the surface properties of the material;The heat of immersion of two types of coal in water and in several different organic liquids was determined with a ...


Reduced Molybdenum Oxidation States In Hydrodesulfurization Catalysis By Chevrel Phases , Mark Eugene Ekman Jan 1991

Reduced Molybdenum Oxidation States In Hydrodesulfurization Catalysis By Chevrel Phases , Mark Eugene Ekman

Retrospective Theses and Dissertations

The catalytic activities of reduced (relative to Mo[superscript]4+) molybdenum sulfides, known as Chevrel phases, have been evaluated for thiophene and benzothiophene hydrodesulfurization (HDS) and 1-butene hydrogenation (HYD). These materials have been found to have HDS activities comparable to, or greater than, model unpromoted and cobalt-promoted MoS[subscript]2 catalysts; in contrast, Chevrel phases exhibit low activities for 1-butene HYD;X-ray powder diffraction and laser Raman spectroscopy analysis of the used (10 hours of thiophene reaction) catalysts indicated that the bulk structures were stable under reaction conditions. XPS analysis demonstrated that reduced molybdenum oxidation states were present at the ...


The Kinetics Of The Reverse Deacon Reaction , Arun K. Nanda Jan 1981

The Kinetics Of The Reverse Deacon Reaction , Arun K. Nanda

Retrospective Theses and Dissertations

The reverse Deacon reaction, Cl(,2) + H(,2)O (--->) 2HCl + 1/2 O(,2) is considered one of the most important steps in thermochemical water-splitting processes, for production of hydrogen from water. The purpose of the research undertaken was to investigate the kinetics of the chlorination of water vapor at high temperatures. An eleven-pass glass reactor 4 mm ID and 511 mm long was used. Stimulus-response experiments showed the reactor could be analyzed by plug flow procedures. The rate expression for the reverse Deacon reaction was developed from the experimental data at 879(DEGREES)K. Varying the partial pressures of ...


Moisture Flow Optimization In Porous Media For Land Leaching And For Seedbed Design , Stephen Bruce Affleck Jan 1980

Moisture Flow Optimization In Porous Media For Land Leaching And For Seedbed Design , Stephen Bruce Affleck

Retrospective Theses and Dissertations

Two problems on optimization of fresh water management in porous media soil systems were investigated. The first problem dealt with the use of surface barriers on tile-drained land during leaching operations. The barriers were designed to prevent direct flow to underlying tile drains and make leaching more efficient. The 0.1 m diameter tile drains were imbedded in an impermeable layer 2 m below the ground surface and drain spacings of 4, 8 and 16 m were investigated. Calculations were made for surface barriers that covered 25, 50 and 75 percent of the land for each case of tile spacing ...


Desulfurization Of Coal By Oxidation In Alkaline Solution , Kang-Chun Chuang Jan 1979

Desulfurization Of Coal By Oxidation In Alkaline Solution , Kang-Chun Chuang

Retrospective Theses and Dissertations

No abstract provided.


A Mathematical Model Of The Chemistry Of The Dump Leaching Of Chalcopyrite, Knona Constance Liddell Jan 1979

A Mathematical Model Of The Chemistry Of The Dump Leaching Of Chalcopyrite, Knona Constance Liddell

Retrospective Theses and Dissertations

No abstract provided.


Devolatilization And Desulfurization Of Iowa Coal , Edmund Tao Kang Huang Jan 1977

Devolatilization And Desulfurization Of Iowa Coal , Edmund Tao Kang Huang

Retrospective Theses and Dissertations

No abstract provided.


Bed And Contact Resistances In An Electrically Conducting Fluidized Bed , Tan-Ping Chen Jan 1975

Bed And Contact Resistances In An Electrically Conducting Fluidized Bed , Tan-Ping Chen

Retrospective Theses and Dissertations

No abstract provided.


Simulation And Control Synthesis For A Pulse Column Separation System For Plutonium-Uranium Recovery , Edward Barrett Mccutcheon Jan 1975

Simulation And Control Synthesis For A Pulse Column Separation System For Plutonium-Uranium Recovery , Edward Barrett Mccutcheon

Retrospective Theses and Dissertations

No abstract provided.


Continuous Steam Gasification Of Coal Char In An Electrofluid Reactor , Justin Leo Beeson Jan 1973

Continuous Steam Gasification Of Coal Char In An Electrofluid Reactor , Justin Leo Beeson

Retrospective Theses and Dissertations

No abstract provided.


A Theoretical Investigation Of Heat Transfer To Fluids In Laminar Flow In Tubes , Kermit Layton Holman Jan 1964

A Theoretical Investigation Of Heat Transfer To Fluids In Laminar Flow In Tubes , Kermit Layton Holman

Retrospective Theses and Dissertations

No abstract provided.