Engineering Commons^™

Investigating The Rheological Behavior Of A Simple Yield Stress Fluid Under Shear Flows, Francesco Accetta

Theses

Many soft materials display unique and complex rheological behavior characterized by a transition from a solid-like to a fluid-like state upon the application of a force that exceeds the threshold to flow, known as the yield stress. Yield stress fluids are found in a wide range of commonly encountered materials including microgels, emulsions, and foams, and have been widely studied by rheologists over the last several decades. Carbopol is a popular polymeric microgel system as it displays simple, non-thixotropic rheological behavior and is typically seen as an ideal yield stress fluid. Previous research has demonstrated the reproducible behavior of shear …

Modeling Of Quad-Station Module Cluster Tools Using Petri Nets, Aung Nay

Theses

The semiconductor industry is highly competitive, and with the recent chip shortage, the throughput of wafers has become more important than ever. One of the tools that the industry has deployed is to use of quad-station modules instead of the traditional single-station modules that allow for higher throughput and better wafer consistency by processing multiple wafers at the same time and distributing work. The industry trend is to use multiple transfer chamber robots to stack the quad-station modules in a series, particularly for etch products. In this work, the quad-station cluster tool wafer movement is modeled by using Petri net …

Iii-Nitride Ultraviolet Light-Emitting Diodes: Approaches For The Enhanced Efficiency, Moulik Patel

Theses

III-nitride ultraviolet (UV) light-emitting diodes (LEDs) offer marvelous potential for a wide range of applications, including air/water purification, surface disinfection, biochemical sensing, cancer cell elimination, and many more. III-nitride semiconductor alloys, especially AlGaN and AlInN, have drawn significant attention due to their significant advantages that include environmental-friendly material composition, compact in size, longer lifetime, low power consumption, and tunable optical emission. However, the performance of III-nitride UV LEDs in terms of efficiency and output power is still deficient. The presence of high defects and dislocations due to lattice-mismatched epilayers, polarization induced quantum-confined Stark effect, electron overflow with low hole injection …

Utilizing Gis Technology For Brownfields Redevelopment, Jeffrey J. Duteau

Theses

Typically, when developers, banks and other organizations have an interest in a piece of property they perform an extensive information search to determine if the site is worth purchasing. This search could consist of tax and title information, the location of utilities and major roadways in the area, information on population demographics and environmental contaminant data. An information search of this type could take days, weeks or even months to compile. With a geographic information system (GIS), this search could take a matter of minutes and is displayed in an easy to understand graphic or map form along with a …

Trifluoroiodomethane As An Environmentally Friendly Gas For Water Patterning By Plasma Etching Process, Krit Aryusook

Theses

Trifluoroiodomethane (CF₃I), a non-global warming gas, has been investigated with study as a substitute for typical CFC etchants, such as CF₄ and C₂F₆, used in wafer pattering technology. This investigation was carried out by exposing dielectric films of silicon oxide (SiO₂) and silicon nitride (Si₃N₄) in CF₃I and C₂F₆/O₂ (used as a reference) plasma environments. The etch rate of these films was ascertained as function of applied rf power, etchant gas flow rate, reaction chamber operating pressure, and O_{2 …}

Microporous Silicon Dioxide/Vycor Membranes For Gas Separation, Justin R. Barone

Theses

This study focused on producing membranes for molecular sieving of gases by reducing the pore size of an already existing membrane structure. To do this, SiO₂ was deposited inside the pores of a Vycor tube with initial pore diameter of 4 nm. The film deposition took place by a low pressure chemical vapor deposition (LPCVD) process where diethylsilane (DES) and nitrous oxide (N₂O) were used as precursor gases. A counterflow reactant geometry was used where the precursor gases were flowed on both sides of the porous membrane. This deposition geometry gave higher selectivities and better mechanical stability. …

Synthesis And Characterization Of Silicon Dioxide Thin Films By Low Pressure Chemical Vapor Deposition, Sutham Niyomwas

Theses

Ditertiarybutylsilane ( DTBS ) and oxygen have been used as precursors to produce silicon dioxide films by low pressure chemical vapor deposition. These films were synthesized in the temperature range of 600°C to 800°C at constant pressure, and at different gas flow composition. The films were found to be uniform with a composition that varied with deposition temperature and gas flow ratio. The growth rate was found to follow an Arrhenius behavior with an apparent activation energy of 2.62 kcal/mol. The growth rate was seen to increase with higher distance between wafers and to vary as a function of square …

Synthesis And Characterization Of Silicon Dioxide Thin Films By Low Pressure Chemical Vapor Deposition Using Ditertiarybutylsilane And Oxygen, Sung-Jun Lee

Theses

This study is focused on the synthesis and characterization of silicon dioxide thin films deposited on silicon wafers by Low Pressure Chemical Vapor Deposition (LPCVD), using ditertiarybutylsilane (DTBS) as a precursor and oxygen as the oxidant. The dependence of film growth rate on various process parameters were studied. The growth rate was found to follow an Arrhenius curve with the variation in the temperature with an activation energy of 12.6 kcal/mol. The growth rate was found to be inversely proportional to the temperature in the range 550-750 °C. The refractive index and density were observed to be close to 1.47 …

Fabrication Of Integrated Optic Sensor To Monitor Pollutant Concentration In Effluents, Kiran Chatty

Theses

An attempt has been made to fabricate an integrated optic sensor to monitor pollutant concentration in effluents. Optic fiber has to be coupled to the waveguide in order to send light through the waveguide. In order to facilitate the easy coupling of the fiber to the waveguide, V-grooves were formed in the silicon substrate. In order to achieve this Silicon nitride was deposited to serve as an etch mask. An attempt was made to obtain low stress silicon nitride films.

This work also attempted to synthesize the materials required to fabricate the waveguide. LPCVD processes were developed to produce undoped …

Low Pressure Chemical Vapor Deposition Of Silicon Dioxide And Phosphosilicate Glass Thin Films, Vijayalakshmi Venkatesan

Theses

Silicon dioxide thin films were synthesized on silicon and quartz wafers using Ditertiarybutylsilane(DTBS) and oxygen as precursors. Trimethylphosphite (TMP) was injected to obtain phosphosilicate glass. The films were processed at different temperatures between 700°C and 850°C at a constant pressure, and at different flow ratios of the precursors. The films deposited were uniform, amorphous and the composition of the films varied with deposition temperature and precursor flow ratios. The deposition rate increased with increasing temperature and with increasing TMP flow rate. The stresses were very low tensile in the case of undoped silicon dioxide film and tended towards being less …

Effect Of Lamellar Microstructure On The Permeability Of Polyethylene Films, Yufu Li

Theses

Lamellar microstructures can decrease the permeability to gases and vapors by increasing the diffusive path in plastic films, or the so-called "tortuosity" which depends on the aspect ratio, orientation, and the volume fraction of the dispersed material. In this research, different types and percentages of mica with relatively high aspect ratio are used as oxygen barrier materials in blown films. Both high and low density polyethylenes (HDPE and LDPE), as well as their blends are used as the matrix materials.

A decrease in permeability of both LDPE and HDPE films to oxygen is achieved with increasing volume fraction of the …

Dynamic Mechanical Analysis Of Particulate Dental Composites, Minu Parekh

Theses

Typically, dental composites are used in different configurations and situations. When a cavity forms at the occlusal surface of a posterior tooth, a class I and class II filling is used, depending on the extent and nature of the cavity formed. These fillings have to be designed to resist mechanical abrasion and occlusal stress during chewing, bruxing and other tooth functions. Class IV fillings are also designed to resist biting stress. In these applications composites with high filler loading with filler particles of size >0.6μm are used. These composites are typically known as minifill or midifill composites. When more than …

Plasma Enhanced Chemical Vapor Deposition Of Stress Free Tungsten Films, David Perese

Theses

This study focuses on PECVD to make tungsten film for X-ray absorber for use in X-ray lithography applications. The previous LPCVD study was used for comparison of film properties. A cold wall, single wafer, Spectrum 211 CVD reactor was used for the deposition of tungsten from H2 and WF6. The growth kinetics were determined as a function of temperature, pressure and flow rate ratio. The deposition rate was found to follow an Arrehnius behavior between 300-500°C with an activation energy of 55.7 kJ/mol. The growth rate increased linearly with total pressure and H2 partial pressure. In the H2/WF6 ratio studies …

Characterization Of Low Pressure Chemically Vapor Deposited Boron Nitride Films As Low Dielectric Constant Materials, Manish Narayan

Theses

Boron nitride thin films were synthesized on Si and quartz wafers by low pressure chemical vapor deposition using borane triethylamine complex and ammonia as precursors. The films were processed at 400°C, 475°C and 550°C at a constant pressure of 0.5 Torr and at different precursor flow ratios.

The films deposited were uniform, amorphous and the composition of the films varied with deposition temperature and precursor flow ratios. The thickness of the film increased with increasing flow ratio, but, decreased with increasing temperature. The stresses in the film were either mildly tensile or compressive.

The least dielectric constant for the films …

Synthesis Of Boron Nitride/Vycor Composite Membrane Structures By An Optimized Lpcvd Process, Chenna Ravindranath

Theses

Since the advent of the idea of ultrafiltration, microporous membranes have come through a long way in establishing a niche as an efficient technology for gas separation applications. More and more research is aimed at reducing pore size towards nanolevels, when separation factor is the criterion rather than the permeability. This work is focused at synthesizing and characterizing microporous inorganic membranes for gas separations by molecular sieving. BN was deposited on mesoporous vycor tubes using triethylamine borane complex (TEAB) and ammonia as precursors. Effect of temperature and deposition geometry on permeability of various gases has been studied. Very high selectivities …

Low Pressure Chemical Vapor Deposition Of Tungsten As An Absorber For X-Ray Masks, Hongyu Chen

Theses

Tungsten film is one of promising materials for X-ray absorber in X-ray Lithography technology because of its high X-ray absorption and refractory properties. This study focus on CVD method to make tungsten film for X-ray absorber.

In this work, a cold wall, single wafer, Spectrum 211 CVD reactor was used for the deposition of tungsten from H, and WF6. The growth kinetics were determined as a function of temperature, pressure and flow ratio. The deposition rate of as deposited tungsten films was found to follow an Arrehnius behavior in the range of 300-500°C with an activation energy of 55.7 kJ/mol. …

Aeration And Operation Of An Immobilized Cell Oxidative Bioreactor, James Joseph Woods

Theses

The primary purpose of this work is to help define the optimum window of operations for an immobilized cell oxidative bioreactor. The analytical technique employed requires no outside verification (such as G.C. analysis) and is independent of liquid flow rate. Method of aeration has been determined to be an important parameter for optimizing bioreactor efficiency, and optimization of the quantity of hydrogen peroxide added to provide oxygen during bio-oxidation has been investigated. Ammonium hydroxide as a fixed nitrogen source can be used to restore the vitality of the bioreactor under certain conditions.

The effects of several different methods of providing …

Low Pressure Chemical Vapor Deposition Of Copper Films From Cu(I)(Hfac)(Tmvs), Wei-Shang King

Theses

Recently, copper has been found as a possible substitute for Al alloys because of its low resistivity (1.67 μΩ • cm) and potentially improved resistance to electromigration. Conventional physical vapor deposition (PVD) method do not provide the conformal deposition profile for the high density integrated circuit, therefore, chemical vapor deposition (CVD) has become the most promising method for the resulting conformal profile.

In this work, a cold wall, single wafer, CVD tungsten reactor was used for the deposition of copper with Cu(I)(hfac)(tmvs). Film growth rates were between 100 to 800 A/min depending on processing conditions, and an Arrhenius type activation …

Synthesis Of Silicon Oxide/Vycor Composite Membrane Structures By An Optimized Lpcvd Process, Abhijit Datta

Theses

This study is focused on development of highly selective ceramic membrane structures consisting of silicon dioxide films synthesized by low pressure chemical vapor deposition (LPCVD) on mesoporous Vycor substrates. The ability of easily altering the composition of such films by varying the LPCVD processing parameters affords the opportunity of microengineering the pore structure by reducing the diameters of pre-existing pores in the support. The process parameters investigated include, deposition temperature, total pressure, and flow rate of oxygen. Both the kinetics and select properties of the deposits were examined. The growth rate as a function of temperature was seen to follow …

The Photolithographic Patterning Of Porous Silicon Using Silicon Nitride And Silicon Carbide Films As Masks, Hong Wang

Theses

In this study, a simple photolithographic pattern process for porous silicon is described. The process utilizes silicon nitride or silicon carbide coated on the top of silicon wafer as a masks. Then a test pattern was projected on the sample by illumination during anodic etching in HF:ethanol solution which produced microcracks in regions illuminated during anodization. Creation of these microcracks resulted in formation of porous silicon in the underlying regions. The cracking is related to the stress in the thin film. The films with tensile stress exhibit cracking while compressive stress samples do not. Compared to silicon carbide films, silicon …

Artificial Dielectric Materials : Synthesis And Optical Characterization Of Small Metal Clusters Embedded In Polymeric Matrix, Nazneen Karim Shilpee

Theses

This study is concerned with the fabrication of films made of gold, nickel, and silicon clusters dispersed in a polymeric matrix. The films were fabricated by use of metal or semiconductor sputtering and plasma polymerization of Methyl Methacrylate monomer in a capacitively coupled RF (13.56 MHz) sputtering system. Optical transmittance and optical reflectance were measured as a function of wavelength. The optical absorption of metal or silicon clusters was studied as a function of cluster size. Cluster size and content were determined from Transmission Electron Micrographs (TEM). The absorption band resulting from a plasma resonance in the clusters was found …

Expert System For Preventive Maintenance The Aluminum Extrusion Press And Related Equipment, E-Ping Lin

Theses

ESPM is an Expert System for Preventive Maintenance that provides the framework for application-specific equipment maintenance tools. The expert system for preventive maintenance and diagnosis was developed for the Aluminum Extrusion Press and Related Equipment. The system is built in VP-Expert and is implemented on a personal computer.

The expert system includes many characteristics of an expert system cell because it can be expanded easily by adding new information to its knowledge base or by changing the existing information. The expert system can be connected directly with a PC system through a VP-Expert software package and can interact with C …

Low Temperature Synthesis And Characterization Of Lpcvd Silicon Dioxide Films Using Diethylsilane, Chakravarthy Srinivasa Gorthy

Theses

Diethylsilane (DES) has been used as a precursor to produce silicon dioxide films by low pressure chemical vapor deposition. These films were synthesized in the temperature range of 350 to 475°C thus allowing the use of the material as an intermetal dielectric or as a top layer passivation coating in microelectronic devices. In that process, the growth rate was observed to follow an Arrhenius behavior yielding an activation energy of 10 kcal/mol. The growth rate was also observed to increase with higher pressure and to vary as a function of the square root of the DES flow rate and O …

Synthesis And Study Of Polymers Containing Inorganic Ions, Lateef Aderoju Ibikunle-Sofoluwe

Theses

Cupric and ferrous polyacrylates have been prepared and studied. It was thought that partial reduction of Cu²⁺ or Fe³⁺ or oxidation of Cu⁺ or Fe²⁺ might result in semiconducting behavior but no such effect has been observed. Nevertheless, the results obtained are of considerable interest. Quantitative gravimetric and volumetric studies of cupric polyacrylate precipitation from varying molar ratios of cupric chloride and sodium polyacrylate in aqueous solution have shown that the only product formed is Cu(PA)₂ (Where PA represents an acrylate mer in polyacrylate). The insolubility of the product indicates that much of the Cu …

Scanning Electron Microscopy And X-Ray Energy Dispersive Spectroscopic Analysis Of Selected Sorbent Materials, Elhamy Amin Sedhom

Theses

A previous study⁽¹⁾ showed that a combination of acidic and basic sorbents in a layered system is required to reduce to safe levels the contaminants present in the leachates emanating from industrial landfills. The sorbents used were fly ash, vermiculite, kaolinite, illite, zeolite, apautagite, bentonite, activated carbon and bauxite.

The purpose of this investigation is to study the physical properties, elemental composition and the distribution of the aforementioned solid sorbents. Properties of interest are particle size, shape and distribution and also the chemical composition and the distribution of the elements within the sample particles.

Scanning Electron Microscopy (SEM) and …

High Temperature Resistant Crosslinked Phenol, O-Chlorophenol And Formaldehyde Copolymer Fiber, Suh Joon Han

Theses

Phenolic copolymer fibers which possess clearly distinguishable physical and chemical properties from other synthetic and natural fibers were prepared. Acid catalyzed condensation polymerization of phenol, formaldehyde and o-chiorophenol was carried out by a two-stage polymerization. Initially, phenol-formaldehyde and o-chlorophenol-formaldehyde oligomers were separately prepared by refluxing the corresponding monomers at 100°C under strong agitation. At the second stage, these two oligomers were combined and vacuum-distilled to form a block copolymer which was then melt spinned into fibers and subsequently cured by succinyl chloride in a mineral spirit. Using a flame test and thermogravimetric analysis, it was found that these cured fibers …

Molecular Modeling In Anatoxin And Other Semirigid Agonists, Wen-Chung Shang

Theses

Conformational search and molecular mechanics calculations were combined to investigate the structural flexibility of isoquinolone, the anatoxin series, and the ferruginine series. Ring searching allow all rational conformations to be generated.

Isoquinolone shows conformational similarity to isoarecolone but is much less potent which suggests that the proximity of the methyl group beta to the carbonyl groups affects the bioactivity of isoquinolone. The very active agonist-anatoxin, without a similar conformation as isoarecolone, shared a similar electrostatic potential contour in the vicinity between the two atoms connected to the electro-positive nitrogen and hydrogen bonding site. These phenomena were not found in ferruginine …

Determination Of Aromatic Amines By Diazonium Salt, Hong-Hue Hsu

Theses

There are many analytical methods used in the identification of aniline by the production of various colors upon treatment with certain reagents. In this work a new inexpensive, easy and sensitive methods to quantitate aniline is developed. The change of absorbance is large enough to measure with a difference of only 1 ppm in the aniline concentration.

In this method, the reagent (2,4-dinitrodiazonium sulphate) which reacts with aniline produces a yellow color. Formation of this color (which absorbs at 486 nm) indicates the presence of aniline. The amount of aniline can be determined by measuring the absorbance at 486 nm. …

Agitation Requirements For Complete Dispersion Of Emulsions, Dun-Huang Tsai

Theses

An investigation on the minimum agitation speed required to achieve complete dispersion in liquid-liquid systems has been carried out. A model based on the momentum balance for a droplet and on Kolmogoroff's theory of isotropic turbulence was used for the prediction of the role of the most important variables on the minimum agitation speed. The equation so derived can be expressed in terms of a number of non- dimensional groups (such as Re, Ar, and Su). For geometrically similar systems the equation contains only one adjustable parameter ( to be determined experimentally) in the form of the proportionality constant correlating …

Approaches To The Synthesis Of Dentin Bonding Agents Containing Vinyl And Carbamate Functional Groups, Steven W. Amato

Theses

The synthesis of four new monomers containing vinyl and carbamate functional groups was attempted. The desired products were N-m-methacryloxyphenyl-O-phenyl carbamate, N-p-methacryloxy-O-phenyl carbamate, m-N-phenylcarbamato-2-methacryloxyethoxy benzoate, and p-N-phenylcarbamato-2-methacryloxyethoxy benzoate. The carbamate functional group was derived by the Lewis Acid catalyzed reaction of meta-aminophenol, para-aminophenol, meta-aminobenzoic acid, and para-aminobenzoic acid with diphenyl carbonate. The vinyl function was derived, in the case of the aminophenols, by reaction with methacrylyl chloride, and in the case of the aminobenzoic acids, with 2-hydroxyethyl methacrylate.

Partial products only were prepared, these being the two carbamate functional phenols, the two carbamate functional benzoic acids, the two methacryloxy functional derivatives …