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A 2D electrostatic PIC code for the Mark III Hypercube (open access)

A 2D electrostatic PIC code for the Mark III Hypercube

We have implemented a 2D electrostastic plasma particle in cell (PIC) simulation code on the Caltech/JPL Mark IIIfp Hypercube. The code simulates plasma effects by evolving in time the trajectories of thousands to millions of charged particles subject to their self-consistent fields. Each particle`s position and velocity is advanced in time using a leap frog method for integrating Newton`s equations of motion in electric and magnetic fields. The electric field due to these moving charged particles is calculated on a spatial grid at each time by solving Poisson`s equation in Fourier space. These two tasks represent the largest part of the computation. To obtain efficient operation on a distributed memory parallel computer, we are using the General Concurrent PIC (GCPIC) algorithm previously developed for a 1D parallel PIC code.
Date: December 31, 1990
Creator: Ferraro, R. D.; Liewer, P. C. & Decyk, V. K.
System: The UNT Digital Library
Activated transport in AMTEC electrodes (open access)

Activated transport in AMTEC electrodes

Transport of alkali metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant, reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. Little can be learned about the detailed mass transport process from the ac impedance or current voltage curves of an electrode at one set of operating parameters, because the transport process includes a number of important physical parameters that are not all uniquely determined by one experiment. The temperature dependence of diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and …
Date: July 1, 1992
Creator: Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Underwood, M. L.; O`Connor, D. & Kikkert, S.
System: The UNT Digital Library
Activated transport in AMTEC electrodes (open access)

Activated transport in AMTEC electrodes

Transport of alkali metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant, reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. Little can be learned about the detailed mass transport process from the ac impedance or current voltage curves of an electrode at one set of operating parameters, because the transport process includes a number of important physical parameters that are not all uniquely determined by one experiment. The temperature dependence of diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and …
Date: January 1, 1992
Creator: Williams, R.M.; Jeffries-Nakamura, B.; Ryan, M.A.; Underwood, M.L.; O'Connor, D. & Kikkert, S.
System: The UNT Digital Library
Advances in high temperature components for AMTEC (alkali metal thermal-to-electric converter) (open access)

Advances in high temperature components for AMTEC (alkali metal thermal-to-electric converter)

Long lifetimes are required for AMTEC (or sodium heat engine) components for aerospace and terrestrial applications, and the high heat input temperature as well as the alkali metal liquid and vapor environment places unusual demands on the materials used to construct AMTEC devices. In addition, it is important to maximize device efficiency and power density, while maintaining a long life capability. In addition to the electrode, which must provide both efficient electrode kinetics, transport of the alkali metal, and low electrical resistance, other high temperature components of the cell face equally demanding requirements. The beta{double prime} alumina solid electrolyte (BASE), the seal between the BASE ceramic and its metallic transition to the hot alkali metal (liquid or vapor) source, and metallic components of the device are exposed to hot liquid alkali metal. Modification of AMTEC components may also be useful in optimizing the device for particular operating conditions. In particular, a potassium AMTEC may be expected to operate more efficiently at lower temperatures.
Date: January 1, 1991
Creator: Williams, R.M.; Jeffries-Nakamura, B.; Underwood, M.L.; Ryan, M.A.; O'Connor, D. & Kikkert, S.
System: The UNT Digital Library
Advances in high temperature components for AMTEC (alkali metal thermal-to-electric converter) (open access)

Advances in high temperature components for AMTEC (alkali metal thermal-to-electric converter)

Long lifetimes are required for AMTEC (or sodium heat engine) components for aerospace and terrestrial applications, and the high heat input temperature as well as the alkali metal liquid and vapor environment places unusual demands on the materials used to construct AMTEC devices. In addition, it is important to maximize device efficiency and power density, while maintaining a long life capability. In addition to the electrode, which must provide both efficient electrode kinetics, transport of the alkali metal, and low electrical resistance, other high temperature components of the cell face equally demanding requirements. The beta{double_prime} alumina solid electrolyte (BASE), the seal between the BASE ceramic and its metallic transition to the hot alkali metal (liquid or vapor) source, and metallic components of the device are exposed to hot liquid alkali metal. Modification of AMTEC components may also be useful in optimizing the device for particular operating conditions. In particular, a potassium AMTEC may be expected to operate more efficiently at lower temperatures.
Date: December 31, 1991
Creator: Williams, R. M.; Jeffries-Nakamura, B.; Underwood, M. L.; Ryan, M. A.; O`Connor, D. & Kikkert, S.
System: The UNT Digital Library
[Article: Decathlete, family man, games founder] (open access)

[Article: Decathlete, family man, games founder]

A magazine article about the last days of Dr. Tom Waddell's life from Dick Schaap's view. Dr. Tom Waddell was the founder of the Gay Games, a famous athlete, and was diagnosed with AIDS.
Date: June 1994
Creator: unknown
System: The UNT Digital Library
At the Edge of Eternity's Shadows: Scaling the Fractal Continuum from Lower into Higher Space (open access)

At the Edge of Eternity's Shadows: Scaling the Fractal Continuum from Lower into Higher Space

Article addressing the hyperspatial implications of the fractal-scaling scheme, including several case studies.
Date: Summer 2003
Creator: Greene, F. Gordon
System: The UNT Digital Library
The Choctaws Indians in the Middle of the Nineteenth Century (open access)

The Choctaws Indians in the Middle of the Nineteenth Century

Article is a lecture given by Reverend John Edwards to the student body at the University of California regarding his observations and experiences working as a missionary within Indian Territory.
Date: Autumn 1932
Creator: Edwards, John & Swanton, John R.
System: The Gateway to Oklahoma History
[Clipping: 'Our Daring Young Women': WWII role models guide women pilots] (open access)

[Clipping: 'Our Daring Young Women': WWII role models guide women pilots]

Photocopy of an clipping on the legacy of Women Airforce Service Pilots, their contributions to World War II, and their eventual fight to gain veteran status.
Date: November 1984
Creator: Watson, Liz
System: The Portal to Texas History
The comet Giacobini-Zinner magnetotail: Axial stresses and inferred near-nucleus properties (open access)

The comet Giacobini-Zinner magnetotail: Axial stresses and inferred near-nucleus properties

Utilizing the electron and magnetic field data from the ICE tail traversal of Comet Giacobini-Zinner along with the MHD equations, we have developed a steady state, stress balance model of the cometary magnetotail. With it we infer many important but unmeasured ion properties within the G-Z magnetotail both at ICE and upstream at the average point along each streamline where cometary ions are picked-up. The derived tailward ion flow speed at ICE is quite constant at approx.-20 to -30 km/sec across the entire tail. The flow velocity, ion temperature, density, and ion source rates upstream from the lobes (current sheet) at the average pickup locations are approx.-75 km/sec (approx.-12), approx.4 x 10/sup 6/ K (approx.1 x 10/sup 5/), approx.20 /cm/sup 3/ (approx.400), and approx..15 /cm/sup 3//sec (approx.3.6). Gradients in the plasma properties between these two regions are quire strong. Implications of our inferred plasma properties for the near-nucleus region and for cometary magnetotail formation are examined. 9 refs., 1 fig.
Date: October 1, 1986
Creator: McComas, D. J.; Gosling, J. T.; Bame, S. J.; Slavin, J. A.; Smith, E. J. & Steinberg, J. L.
System: The UNT Digital Library
A Critique of Kellehear's Transcendent Society (open access)

A Critique of Kellehear's Transcendent Society

Article responding to Allen Kellehear's cultural analysis based on nine Mormon near-death experiences (NDEs) did not reflect the diversity of near-death visions from other cultures. It suggests that these Mormon NDEs were neither as utopian as Kellehear assumed nor representative of contemporary NDE reports, and that a more complete analysis would reveal a variety of NDEs and otherworld visions reflecting the experiencers' sociocultural background.
Date: Winter 1991
Creator: Mickel, Howard A.
System: The UNT Digital Library
[The Dallas Morning News, 'Museum director resigns'] (open access)

[The Dallas Morning News, 'Museum director resigns']

An article written by Janet Kutner for The Dallas Morning News that announces the resignation of E. A. Carmean Jr. as director of the Modern Art Museum of Fort Worth. The piece covers the work he did while at the museum.
Date: 199X
Creator: Kutner, Janet
System: The UNT Digital Library
The Death and Posthumous Life of Tom Sawyer: A Case Study of Apparent After-Death Communication (open access)

The Death and Posthumous Life of Tom Sawyer: A Case Study of Apparent After-Death Communication

Article exploring the near-death experience of Tom Sawyer, as well as the question of whether he actually died in April of 2007.
Date: Winter 2008
Creator: Ring, Kenneth
System: The UNT Digital Library
The Death Journey of a Hopi Indian: A Case Study (open access)

The Death Journey of a Hopi Indian: A Case Study

Article presenting the case study of the "death journey" or near-death experience (NDE) of Don Talayesva, a Hopi Indian, whose experience occurred between 1900 and 1910. The article compares and contrasts his experience with 11 accounts of Native American NDEs reported by Jenny Wade, as well as with modern day NDEs.
Date: Summer 2008
Creator: Green, J. Timothy
System: The UNT Digital Library
[Denton Record-Chronicle articles, June 10, 1990] (open access)

[Denton Record-Chronicle articles, June 10, 1990]

A clipping of an article by Susan Shelton for the Denton Record-Chronicle about the new NTIEVA program's reworking of art education in Metroplex schools. Another piece by Shelton that is included covers Dr. Warren Carver's support of the program.
Date: June 10, 1990
Creator: Shelton, Susan
System: The UNT Digital Library
Describing the Light: Attribution Theory as an Explanation of the Near-Death Experience (open access)

Describing the Light: Attribution Theory as an Explanation of the Near-Death Experience

Article exploring near-death experiences and attribution theory, which focuses on how information is used to create causal inferences and answer causal questions. The finding that near-death experiencers (NDErs) rarely describe unknown events, characters, or objects suggests that NDErs make attributions to answer why these experiences occurred. Examining various descriptions of NDEs demonstrates how attribution theory explains individuals' descriptions of their NDEs.
Date: Spring 1995
Creator: Norton, Max C. & Sahlman, James M.
System: The UNT Digital Library
Design considerations for a fiber optic communications network for power systems (open access)

Design considerations for a fiber optic communications network for power systems

The design of a fiber optic communication network for monitoring and control in power systems is discussed. It is shown that by appropriate choice of protocols, a fault-tolerant system can be built that operates in any arbitrary configuration. Since the network is based on fiber optics, it can be made fast enough for substation monitoring and control. In this application, a relatively small number of cables is required to implement a high reliability system. The network can also be used for distribution automation. In this application the network is required to reach all parts of the power system, and the fiber cable itself becomes a significant fraction of the cost of communications. However, since many applications can be supported at once, the cost per function can be reasonable.
Date: August 1, 1993
Creator: Kirkham, H.; Johnston, A. R. & Allen, G. D.
System: The UNT Digital Library
Distressing Near-Death Experiences as Photographic Negatives (open access)

Distressing Near-Death Experiences as Photographic Negatives

Article presenting various interpretative frameworks for painful near-death experiences (NDEs).
Date: Winter 1996
Creator: Ellwood, Gracia Fay
System: The UNT Digital Library
Dual arm master controller concept (open access)

Dual arm master controller concept

The Advanced Servomanipulator (ASM) slave was designed with an anthropomorphic stance, gear/torque tube power drives, and modular construction. These features resulted in increased inertia, friction, and backlash relative to tape-driven manipulators. Studies were performed which addressed the human factors design and performance trade-offs associated with the corresponding master controller best suited for the ASM. The results of these studies, as well as the conceptual design of the dual arm master controller, are presented. 6 references, 3 figures.
Date: January 1, 1984
Creator: Kuban, D.P. & Perkins, G.S.
System: The UNT Digital Library
Dual arm master controller development (open access)

Dual arm master controller development

The advanced servomanipulator (ASM) slave was designed with an anthropomorphic stance, gear/torque tube power drives, and modular construction. These features resulted in increased inertia, friction, and backlash relative to tape-driven manipulators. Studies were performed which addressed the human factors design and performance trade-offs associated with the corresponding master controller best suited for the ASM. The results of these studies, as well as the conceptual design of the dual arm master controller, are presented. This work was performed as part of the Consolidated Fuel Reprocessing Program at the Oak Ridge National Laboratory. 5 refs., 7 figs., 1 tab.
Date: January 1, 1985
Creator: Kuban, D. P. & Perkins, G. S.
System: The UNT Digital Library
Dynamic load balancing in a concurrent plasma PIC code on the JPL/Caltech Mark III hypercube (open access)

Dynamic load balancing in a concurrent plasma PIC code on the JPL/Caltech Mark III hypercube

Dynamic load balancing has been implemented in a concurrent one-dimensional electromagnetic plasma particle-in-cell (PIC) simulation code using a method which adds very little overhead to the parallel code. In PIC codes, the orbits of many interacting plasma electrons and ions are followed as an initial value problem as the particles move in electromagnetic fields calculated self-consistently from the particle motions. The code was implemented using the GCPIC algorithm in which the particles are divided among processors by partitioning the spatial domain of the simulation. The problem is load-balanced by partitioning the spatial domain so that each partition has approximately the same number of particles. During the simulation, the partitions are dynamically recreated as the spatial distribution of the particles changes in order to maintain processor load balance.
Date: December 31, 1990
Creator: Liewer, P. C.; Leaver, E. W.; Decyk, V. K. & Dawson, J. M.
System: The UNT Digital Library
Edward W. Bushyhead and John Rollin Ridge: Cherokee Editors in California (open access)

Edward W. Bushyhead and John Rollin Ridge: Cherokee Editors in California

Article chronicles how Edward W. Bushyhead and John Rollin Ridge established newspapers within California during their search for gold.
Date: Autumn 1936
Creator: Foreman, Carolyn Thomas, 1872-1967
System: The Gateway to Oklahoma History
Efficiency of an AMTEC recirculating test cell, experiments and projections (open access)

Efficiency of an AMTEC recirculating test cell, experiments and projections

The alkali metal thermal to electric converter (AMTEC) is an electrochemical device for the direct conversion of heat to electrical energy with efficiencies potentially near Carnot. The future usefulness of AMTEC for space power conversion depends on the efficiency of the devices. Systems studies have projected from 15% to 35% thermal to electric conversion efficiencies, and one experiment has demonstrated 19% efficiency for a short period of time. Recent experiments in a recirculating test cell (RTC) have demonstrated sustained conversion efficiencies as high as 10.2% early in cell life and 9.7% after maturity. Extensive thermal and electrochemical analysis of the cell during several experiments demonstrated that the efficiency could be improved in two ways. First, the electrode performance could be improved. The electrode for these tests operated at about one third the power density of state of the art electrodes. The low power density was caused by a combination of high series resistance and high mass flow resistance. Reducing these resistances could improve the efficiency to greater than 10%. Second, the cell thermal performance could be improved. Efficiencies greater than 14% could be realized through reducing the radiative thermal loss. Further improvements to the efficiency range predicted by systems studies …
Date: May 1, 1992
Creator: Underwood, M. L.; O`Connor, D.; Williams, R. M.; Jeffries-Nakamura, B. & Ryan, M. A.
System: The UNT Digital Library
Experimental evaluation of a fixed collector employing vee-trough concentrator and vacuum tube receivers (open access)

Experimental evaluation of a fixed collector employing vee-trough concentrator and vacuum tube receivers

A test bed for experimental evaluation of a fixed solar collector which combines an evacuated glass tube solar receiver with a flat plate/black chrome plated copper absorber and an asymmetric veetrough concentrator was designed and constructed. Earlier predictions of thermal performance were compared with test data acquired for a bare vacuum tube receiver; and receiver tubes with Alzak aluminum, aluminized FEP Teflon film laminated sheet metal and second surface ordinary mirror reflectors. Test results and system economics as well as objectives of an ongoing program to obtain long-term performance data are discussed.
Date: January 1, 1977
Creator: Selcuk, M. K.
System: The UNT Digital Library