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Full-Text Articles in Engineering

Activation Of Precipitated Iron Fischer-Tropsch Catalysts, Mehul D. Shroff Dec 1995

Activation Of Precipitated Iron Fischer-Tropsch Catalysts, Mehul D. Shroff

Chemical and Biological Engineering ETDs

The Fischer-Tropsch Synthesis (FTS) is an important step in the manufacture of synthetic fuels from coal. The use of iron catalysts for FTS, though desirable from the standpoint of process economy, is hampered by problems relating to catalyst attrition and carbon buildup. In addition, from a research perspective, there has been a long-standing controversy in the literature with regard to the nature of the active phase.

The effect of activation and reaction treatments on the resulting phase transformations in a commercial, precipitated and spray-dried, Fe2O3 - CuO - K2O Fischer-Tropsch catalyst have been studied. Different catalyst batches ...


Construction And Characterization Of An Extended Helicon Plasma Source, Russell Ford Jewett Jr. Sep 1995

Construction And Characterization Of An Extended Helicon Plasma Source, Russell Ford Jewett Jr.

Electrical and Computer Engineering ETDs

A new helicon source has been developed for plasma processing applications. The source is a modification of the traditional cylindrical helicon source design to rectangular geometry. In order to accomplish this, the antenna used for launching helicon waves is stretched in the direction perpendicular to the static magnetic field lines. This source was coupled to a long rectangular slab chamber which is used for the actual material processing. A static magnetic field of -200 Gauss peak strength, pointing out from the source into the diffusion region, was applied to facilitate helicon wave propagation. 13.56 MHz rf power was used ...


Numerical Study Of Granular Soil Behavior Using Random Arrays Of Elastic Ellipsoids, Xiaoshan Lin May 1995

Numerical Study Of Granular Soil Behavior Using Random Arrays Of Elastic Ellipsoids, Xiaoshan Lin

Civil Engineering ETDs

For the purpose of improving computer simulation of granular materials in the framework of the Discrete Element Method (DEM), 2-D and 3-D discrete element models using random arrays of elastic ellipsoids have been developed.


Thermalhydraulics Analysis Of The Unit-Cell Nuclear Light Bulb Rocket Engine, Vojislav Banjac May 1995

Thermalhydraulics Analysis Of The Unit-Cell Nuclear Light Bulb Rocket Engine, Vojislav Banjac

Nuclear Engineering ETDs

This dissertation presents a detailed thermalhydraulics analysis of the unit-cell derivative of the Nuclear Light Bulb (NLB) rocket engine. The NLB engine is a gas core nuclear rocket first proposed in the 1960's by the then-United Aircraft Research Laboratories (UARL); its unit-cell derivative consists of a low-temperature moderator/reflector as well as segmented propellant channels, both proposed with the intent of increasing the keff of the system.

The results of this work can be grouped into two major areas: (1) thermal and neutronics analysis of the engine, and (2) investigation of the feasibility of the engine over a ...


Effects Of Varying Coupling Impedance, Finite Length, And Asynchronous Harmonics On High Power Bwo Performance, Larald Dean Moreland Apr 1995

Effects Of Varying Coupling Impedance, Finite Length, And Asynchronous Harmonics On High Power Bwo Performance, Larald Dean Moreland

Electrical and Computer Engineering ETDs

A systematic study of high power backward wave oscillators (BWOs) was performed using the Sinus-6 repetitively-pulsed relativistic electron beam accelerator. Peak output power of up to 550 MW was measured in a frequency range of 9.2 to 9.8 GHz with pulse lengths up to 10 ns. The experimental results were compared with numerical simulations using TWOQUICK, a 2.5 D, relativistic, fully electromagnetic, particle-in-cell (PIC) code. It was observed that a significant increase in microwave efficiency can be obtained by using a BWO with a spatially varying coupling impedance instead of the traditional uniform distribution. Based on experiments ...