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Articles 1 - 11 of 11

Full-Text Articles in Engineering

Organometallic Chemical Vapor Deposition Of Copper Oxide Thin Films , Yu-Neng Chang Jan 1992

Organometallic Chemical Vapor Deposition Of Copper Oxide Thin Films , Yu-Neng Chang

Retrospective Theses and Dissertations

Copper oxide thin films were prepared by organometallic chemical vapor deposition (OMCVD or MOCVD) technique. This MOCVD process uses copper acetylacetonate (Cu(acac)[subscript]2) as the copper precursor. Spectroscopic (X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and infrared spectroscopy (IR)) and diffraction (X-ray diffraction (XRD)) methods were employed to analyze the chemical composition and oxidation state of copper in these films. According to spectroscopic results, the composition of these MOCVD film primarily depends on the deposition temperature and partial pressures of the reactants. As indicated by XPS and XRD results, Cu[subscript]2O films were prepared at 360 ...


Development Of A Process Simulator Using Object Oriented Programming: Information Modeling And Program Structure , Gadiraju V. Varma Jan 1992

Development Of A Process Simulator Using Object Oriented Programming: Information Modeling And Program Structure , Gadiraju V. Varma

Retrospective Theses and Dissertations

Object Oriented Programming Languages (OOPL) offer the flexibility of language extension to the specific application of interest. The development effort required for process simulators can be greatly reduced if we extend OOPL with process simulator specific objects and use them for simulation. Design of objects is the most important aspect of development in using OOPL. But OOPL do not provide a methodology to aid in object design. The objects to be designed should reflect the nature of the application at hand.;The objective of this work is to develop an object oriented process simulator to illustrate the benefit of using ...


Development Of A Process Simulator Using Object Oriented Programming: Numerical Procedures And Convergence Studies , Kheng Hock Lau Jan 1992

Development Of A Process Simulator Using Object Oriented Programming: Numerical Procedures And Convergence Studies , Kheng Hock Lau

Retrospective Theses and Dissertations

An object oriented process simulation environment was developed using object oriented programming. It consists of a sequential modular simulator, an equation-based simulator, a physical quantity system, a physical property system and a databank. The modified Powell's dogleg method was evaluated and found to be a reliable nonlinear equation solver for both dense and sparse equations. Two approaches of keeping unknowns in the feasible region were evaluated. They performed remarkably well. For the update of the sparse Jacobian matrix, Schubert's update and Bogle's update were both effective. We extended the root solving technique of Topliss and it performed ...


Evaluation Of Solubility And Viscosity Of Refrigerant/Lubricant Solutions , Ufuk Gündüz Jan 1992

Evaluation Of Solubility And Viscosity Of Refrigerant/Lubricant Solutions , Ufuk Gündüz

Retrospective Theses and Dissertations

Convenient representations for the pressure, temperature, composition and viscosity of three refrigerant/lubricant mixtures are studied. Solubility results are obtained from different models for the activity of the mixtures and from application of thermodynamic perturbation theory.;Local composition models have the advantage that an approximate form for the temperature dependence of the activity is provided. This work provides an analysis of the applicability of local composition models based on Wilson's treatment of the Flory-Huggins approximation for the lattice gas model in which site-site interactions are neglected. We have presented a modification of the Wilson's approach in which site-site ...


Solute Clustering In Supersaturated Solutions , Deepak Lumba Jan 1992

Solute Clustering In Supersaturated Solutions , Deepak Lumba

Retrospective Theses and Dissertations

The phenomenon of solute clustering in aqueous solutions of ammonium paramolybdate has been characterized using the following experimental techniques: laser Raman spectroscopy, concentration gradient studies, and multi-angle light scattering. Additionally, light scattering techniques have been developed to investigate the occurrence of solute clustering in concentrated and supersaturated solutions;The results of these experimental techniques indicate that solute clustering occurs in undersaturated, saturated, and supersaturated solutions of ammonium paramolybdate. The age of the solutions does not affect the degree of clustering in these solutions. The size of solute clusters increases with supersaturation and the degree of clustering increases at the saturation ...


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 ...


Low Pressure And Plasma Enhanced Chemical Vapor Deposition Of Molybdenum Oxide Films , Jeffrey Scott Cross Jan 1992

Low Pressure And Plasma Enhanced Chemical Vapor Deposition Of Molybdenum Oxide Films , Jeffrey Scott Cross

Retrospective Theses and Dissertations

Thin films of molybdenum oxides were produced on silicon substrates from Mo(CO)[subscript]6 and O[subscript]2 using both a low pressure and plasma enhanced chemical vapor deposition (LPCVD and PECVD). The substrates were heated using a SiC coated graphite susceptor which was inductively coupled to a 200-450 kHz radio-frequency (RF) generator and using a Macor resistive heater. The process variables investigated were temperature, 250-530°C; pressure, 100-1014 mtorr; Mo(CO)[subscript]6 flow rate, 0.56-6.7 mg/min; O[subscript]2 flow rate, 5-15 sccm; H[subscript]2O flow rate of 0.0-0.53 sccm; and ...


Selective Oxidation Of C4 Hydrocarbons Over (Vo)2p2o7 Catalyst: Nature Of The Redox Mechanism , Satish Narayan Kamat Jan 1992

Selective Oxidation Of C4 Hydrocarbons Over (Vo)2p2o7 Catalyst: Nature Of The Redox Mechanism , Satish Narayan Kamat

Retrospective Theses and Dissertations

For the selective oxidation of n-butane to maleic anhydride, (VO)[subscript]2P[subscript]2O[subscript]7 has been identified as the most active and selective V-P-O phase. However, the presence of various types of oxygen species present in this polyfunctional system has made it difficult to study its redox mechanism in terms of the different oxygen species present. To overcome this problem, we have employed isotopic reactive-site mapping (IR-SM) approach. A three stage solid state procedure was used to synthesize a (VO)[subscript]2P[subscript]2O[subscript]7 catalyst labeled with [superscript]18O. Characterization of this labeled catalyst by infrared ...


The Effect Of Electrochemical Reactions On The Surface Film Composition And Corrosion Resistance Of Aluminum In Acid Solutions , Ching-Feng Lin Jan 1992

The Effect Of Electrochemical Reactions On The Surface Film Composition And Corrosion Resistance Of Aluminum In Acid Solutions , Ching-Feng Lin

Retrospective Theses and Dissertations

Cathodic polarization was found to reduce the hydrogen transport resistance of the surface oxide film on aluminum, at potentials around -1.65V vs. Ag/AgCl/4M KCl in 0.1M HCl solution. Reduction of film resistance was shown to be due to change of film composition as a consequence of cathodic charging. Formation of surface film was also found at potentials where the film resistance was reduced. The film, which was shown to contain appreciable amounts of water, was found to be an ohmic proton conductor with the conductivity at the same order of magnitude as precipitated aluminum hydroxide;The ...


Investigation Of Crystallization And Phase Transitions Of Sol-Gel Derived Ba2ti9o20 And Bati5o11 Thin Films , Hsin-Chun Lu Jan 1992

Investigation Of Crystallization And Phase Transitions Of Sol-Gel Derived Ba2ti9o20 And Bati5o11 Thin Films , Hsin-Chun Lu

Retrospective Theses and Dissertations

A new sol-gel process was developed to produce thin films of Ba[subscript]2Ti[subscript]9O[subscript]20 and BaTi[subscript]5O[subscript]11, and the phenomena of crystallization and phase transition processes of these sol-gel derived thin films during isothermal annealing was studied by the experimental techniques of in situ laser Raman spectroscopy and transmission electron microscopy;Precursor solutions of Ba[subscript]2Ti[subscript]9O[subscript]20 and BaTi[subscript]5O[subscript]11 were produced by first hydrolizing titanium alkoxide and then mixing the resulting titania sol with a barium alkoxide-methanol solution. By using X-ray diffraction and laser Raman ...


The Influence Of Carbon Dioxide On The Catalytic Oxidative Coupling Of Methane Over A-La2o3 And Ii-La2o2co3 , Richard Paul Taylor Jan 1992

The Influence Of Carbon Dioxide On The Catalytic Oxidative Coupling Of Methane Over A-La2o3 And Ii-La2o2co3 , Richard Paul Taylor

Retrospective Theses and Dissertations

Previous work conducted in our laboratory suggested a strong correlation between the presence of oxycarbonate and the ability of lanthanum oxide-based materials to selectively promote the oxidative coupling of methane (OCM). Since A-La[subscript]2O[subscript]3 and II-La[subscript]2O[subscript]2CO[subscript]3 may be prepared from each other by the loss and gain, respectively, of CO[subscript]2 at temperatures ranging from 415 to 970°C (depending on the gas phase environment), the influence of CO[subscript]2 on the OCM process is of great interest;This work found that co-feeding CO[subscript]2 over pure A-La ...