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491,873 Matching Results

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Best Match Title Creator Date Created (Newest) Date Created (Oldest) Date Added (Newest) Date Added (Oldest)
Controlled-source magnetotellurics: source effects (open access)

Controlled-source magnetotellurics: source effects

In this paper we evaluate the CSMT impedance in the wavenumber domain, and compare the result with the full EM impedance obtained from the exact solution over the layered earth. Preliminary results show that we can find a pair of wavenumbers that reproduces the full EM impedance over the frequency range affected by source effects. This observation suggests that it is now possible to obtain the electrical resistivity using the low-frequency EM impedance data that can be represented by a pair of wavenumbers, thereby greatly simplifying the computational requirements. The process will involve a non-linear inversion of near-source impedance data for a pair of wavenumbers and a layered-earth resistivity structure.
Date: April 1, 1999
Creator: Smith, T. & Lee, K. H.
Object Type: Report
System: The UNT Digital Library
Large-scale cryopumping for controlled fusion (open access)

Large-scale cryopumping for controlled fusion

Vacuum pumping by freezing out or otherwise immobilizing the pumped gas is an old concept. In several plasma physics experiments for controlled fusion research, cryopumping has been used to provide clean, ultrahigh vacua. Present day fusion research devices, which rely almost universally upon neutral beams for heating, are high gas throughput systems, the pumping of which is best accomplished by cryopumping in the high mass-flow, moderate-to-high vacuum regime. Cryopumping systems have been developed for neutral beam injection systems on several fusion experiments (HVTS, TFTR) and are being developed for the overall pumping of a large, high-throughput mirror containment experiment (MFTF). In operation, these large cryopumps will require periodic defrosting, some schemes for which are discussed, along with other operational considerations. The development of cryopumps for fusion reactors is begun with the TFTR and MFTF systems. Likely paths for necessary further development for power-producing reactors are also discussed.
Date: July 25, 1977
Creator: Pittenger, L. C.
Object Type: Article
System: The UNT Digital Library
An investigation of a passively controlled haptic interface (open access)

An investigation of a passively controlled haptic interface

Haptic interfaces enhance cooperation between humans and robotic manipulators by providing force and tactile feedback to the human user during the execution of arbitrary tasks. The use of active actuators in haptic displays presents a certain amount of risk since they are capable of providing unacceptable levels of energy to the systems upon which they operate. An alternative to providing numerous safeguards is to remove the sources of risk altogether. This research investigates the feasibility of trajectory control using passive devices, that is, devices that cannot add energy to the system. Passive actuators are capable only of removing energy from the system or transferring energy within the system. It is proposed that the utility of passive devices is greatly enhanced by the use of redundant actuators. In a passive system, once motion is provided to the system, presumably by a human user, passive devices may be able to modify this motion to achieve a desired resultant trajectory. A mechanically passive, 2-Degree-of-Freedom (D.O.F.) manipulator has been designed and built. It is equipped with four passive actuators: two electromagnetic brakes and two electromagnetic clutches. This paper gives a review of the literature on passive and robotics and describes the experimental test bed …
Date: March 1, 1997
Creator: Davis, J. T. & Book, W. J.
Object Type: Article
System: The UNT Digital Library
Controlled Hydrogen Fleet and Infrastructure Analysis

Controlled Hydrogen Fleet and Infrastructure Analysis

This presentation summarizes controlled hydrogen fleet & infrastructure analysis undertaken for the DOE Fuel Cell Technologies Program.
Date: June 10, 2010
Creator: Wipke, K.; Sprik, S.; Kurtz, J. & Ramsden, T.
Object Type: Presentation
System: The UNT Digital Library
Microprocessor-controlled scanning densitometer system (open access)

Microprocessor-controlled scanning densitometer system

An Automated Scanning Densitometer System has been developed by uniting a microprocessor with a low energy x-ray densitometer system. The microprocessor controls the detector movement, provides self-calibration, compensates raw readings to provide time-linear output, controls both data storage and the host computer interface, and provides measurement output in engineering units for immediate reading. The densitometer, when used in a scanning mode, is a precision reference instrument that provides chordal average density measurements over the cross section of a pipe under steady-state flow conditions. Results have shown an improvement over the original densitometer in reliability and repeatability of the system, an a factor-of-five improvement in accuracy.
Date: April 1, 1980
Creator: Shurtliff, R.W.
Object Type: Report
System: The UNT Digital Library
Controlled Hydrogen Fleet and Infrastructure Analysis

Controlled Hydrogen Fleet and Infrastructure Analysis

This presentation summarizes controlled hydrogen fleet and infrastructure analysis.
Date: May 1, 2011
Creator: Wipke, K.; Sprik, S.; Kurtz, J.; Ramsden, T.; Ainscough, C. & Saur, G.
Object Type: Presentation
System: The UNT Digital Library
Controlled Hydrogen Fleet and Infrastructure Analysis

Controlled Hydrogen Fleet and Infrastructure Analysis

This is a presentation about the Fuel Cell Electric Vehicle Learning Demo, a 7-year project and the largest single FCEV and infrastructure demonstration in the world to date. Information such as its approach, technical accomplishments and progress; collaborations and future work are discussed.
Date: May 1, 2012
Creator: Wipke, K.; Sprik, S.; Kurtz, J.; Ramsden, T.; Ainscough, C. & Saur, G.
Object Type: Presentation
System: The UNT Digital Library
Controlled Hydrogen Fleet and Infrastructure Analysis

Controlled Hydrogen Fleet and Infrastructure Analysis

None
Date: May 1, 2006
Creator: Wipke, K.
Object Type: Presentation
System: The UNT Digital Library
Controlled Hydrogen Fleet and Infrastructure Analysis

Controlled Hydrogen Fleet and Infrastructure Analysis

This presentation by Keith Wipke at the 2007 DOE Hydrogen Program Annual Merit Review Meeting provides information about NREL's Controlled Hydrogen Fleet and Infrastructure Analysis Project.
Date: May 17, 2007
Creator: Wipke, K.
Object Type: Presentation
System: The UNT Digital Library
Controlled Hydrogen Fleet and Infrastructure Analysis

Controlled Hydrogen Fleet and Infrastructure Analysis

This presentation by Keith Wipke at the 2008 DOE Hydrogen Program Annual Merit Review Meeting provides information about NREL's Controlled Hydrogen Fleet and Infrastructure Analysis Project.
Date: June 10, 2008
Creator: Wipke, K.; Sprik, S. & Kurtz, J.
Object Type: Presentation
System: The UNT Digital Library
Surface effects in controlled thermonuclear fusion (open access)

Surface effects in controlled thermonuclear fusion

During the operation of large size plasma facilities and future controlled thermonuclear fusion reactors the surfaces of such major components as container walls, beam limiters, diverter walls and beam-dump walls of the injector region will be exposed to particle and photon bombardment from primary plasma radiations and from secondary radiations. Such radiations can cause, for example, physical and chemical sputtering, blistering, particle- and photon- impact induced desorption, secondary electron and x-ray emission, backscattering, nuclear reactions, photo-decomposition of surface compounds, photocatalysis, and vaporization. Such effects in turn can (a) seriously damage and erode the bombarded surface and (b) release major quantities of impurities which will contaminate the plasma. The effects of some of the major surface phenomena on the operation of plasma facilities and future fusion reactors are discussed. (auth)
Date: August 1, 1975
Creator: Kaminsky, M.
Object Type: Article
System: The UNT Digital Library
Sensor-Based Demand Controlled Ventilation (open access)

Sensor-Based Demand Controlled Ventilation

In most buildings, occupancy and indoor pollutant emission rates vary with time. With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation (i.e., rate of outside air supply) also varies with time to compensate for the changes in pollutant generation. In other words, SBDCV involves the application of sensing, feedback and control to modulate ventilation. Compared to ventilation without feedback, SBDCV offers two potential advantages: (1) better control of indoor pollutant concentrations; and (2) lower energy use and peak energy demand. SBDCV has the potential to improve indoor air quality by increasing the rate of ventilation when indoor pollutant generation rates are high and occupants are present. SBDCV can also save energy by decreasing the rate of ventilation when indoor pollutant generation rates are low or occupants are absent. After providing background information on indoor air quality and ventilation, this report provides a relatively comprehensive discussion of SBDCV. Topics covered in the report include basic principles of SBDCV, sensor technologies, technologies for controlling air flow rates, case studies of SBDCV, application of SBDCV to laboratory buildings, and research needs. SBDCV appears to be an increasingly attractive technology option. Based on the review of literature and theoretical considerations, the application of SBDCV …
Date: July 1997
Creator: De Almeida, Anibal T. & Fisk, William J.
Object Type: Report
System: The UNT Digital Library
Atomic data for controlled fusion research (open access)

Atomic data for controlled fusion research

Presented is an evaluated graphical and tabular compilation of atomic and molecular cross sections of interest to controlled thermonuclear research. The cross sections are tabulated and graphed as a function of energy for collision processes involving heavy particles, electrons, and photons with atoms and ions. Also included are sections on data for particle penetration through macroscopic matter, particle transport properties, particle interactions with surfaces, and pertinent charged particle nuclear cross sections and reaction rates. In most cases estimates have been made of the data accuracy.
Date: February 1, 1977
Creator: Barnett, C. F.; Ray, J. A.; Ricci, E.; Wilker, M. I.; McDaniel, E. W.; Thomas, E. W. et al.
Object Type: Report
System: The UNT Digital Library
Supplemental Insert Sheets for Engineering Materials List. (open access)

Supplemental Insert Sheets for Engineering Materials List.

None
Date: January 1, 1968
Creator: Kelly, R.C. (ed.)
Object Type: Report
System: The UNT Digital Library
The List (open access)

The List

The List is a collection of short stories focusing on the inability to adapt, or learn from self-destructive patterns, and the bizarre ways people reach out for one another when they don't know what else to do.
Date: December 2009
Creator: O'Brien, Tanner Chase
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Controlled Vocabularies in the Digital Age: Are They Still Relevant? (open access)

Controlled Vocabularies in the Digital Age: Are They Still Relevant?

Keyword searching and controlled vocabularies such as Library of Congress subject headings (LCSH) proved to work well together in automated technologies and the two systems have been considered complimentary. When the Internet burst onto the information landscape, users embraced the simplicity of keyword searching of this resource while researchers and scholars seemed unable to agree on how best to make use of controlled vocabularies in this huge database. This research looked at a controlled vocabulary, LCSH, in the context of keyword searching of a full text database. The Internet and probably its most used search engine, Google, seemed to have set a standard that users have embraced: a keyword-searchable single search box on an uncluttered web page. Libraries have even introduced federated single search boxes to their web pages, another testimony to the influence of Google. UNT's Thesis and Dissertation digital database was used to compile quantitative data with the results input into an EXCEL spreadsheet. Both Library of Congress subject headings (LCSH) and author-assigned keywords were analyzed within selected dissertations and both systems were compared. When the LCSH terms from the dissertations were quantified, the results showed that from a total of 788 words contained in the 207 LCSH …
Date: August 2017
Creator: Baker, William
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Controlled Hydrogen Fleet & Infrastructure Analysis

Controlled Hydrogen Fleet & Infrastructure Analysis

A PowerPoint presentation given as part of the 2005 Hydrogen Program Review, May 24, 2005, in Washington, D.C.
Date: May 1, 2005
Creator: Wipke, K.
Object Type: Presentation
System: The UNT Digital Library
Controlled Hydrogen Fleet and Infrastructure Demonstration Project (open access)

Controlled Hydrogen Fleet and Infrastructure Demonstration Project

This program was undertaken in response to the US Department of Energy Solicitation DE-PS30-03GO93010, resulting in this Cooperative Agreement with the Ford Motor Company and BP to demonstrate and evaluate hydrogen fuel cell vehicles and required fueling infrastructure. Ford initially placed 18 hydrogen fuel cell vehicles (FCV) in three geographic regions of the US (Sacramento, CA; Orlando, FL; and southeast Michigan). Subsequently, 8 advanced technology vehicles were developed and evaluated by the Ford engineering team in Michigan. BP is Ford's principal partner and co-applicant on this project and provided the hydrogen infrastructure to support the fuel cell vehicles. BP ultimately provided three new fueling stations. The Ford-BP program consists of two overlapping phases. The deliverables of this project, combined with those of other industry consortia, are to be used to provide critical input to hydrogen economy commercialization decisions by 2015. The program's goal is to support industry efforts of the US President's Hydrogen Fuel Initiative in developing a path to a hydrogen economy. This program was designed to seek complete systems solutions to address hydrogen infrastructure and vehicle development, and possible synergies between hydrogen fuel electricity generation and transportation applications. This project, in support of that national goal, was designed …
Date: March 31, 2010
Creator: Staley, Dr. Scott
Object Type: Report
System: The UNT Digital Library
Microprocessor-controlled, programmable ramp voltage generator (open access)

Microprocessor-controlled, programmable ramp voltage generator

A special-purpose voltage generator has been developed for driving the quadrupole mass filter of a residual gas analyzer. The generator is microprocessor-controlled with desired ramping parameters programmed by setting front-panel digital thumb switches. The start voltage, stop voltage, and time of each excursion are selectable. A maximum of five start-stop levels may be pre-selected for each program. The ramp voltage is 0 to 10 volts with sweep times from 0.1 to 999.99 seconds.
Date: November 1, 1978
Creator: Hopwood, J.
Object Type: Report
System: The UNT Digital Library
Remotely controlled large container disposal methodology (open access)

Remotely controlled large container disposal methodology

Remotely Handled Large Containers (RHLC), also called drag-off boxes, have been used at the Hanford Site since the 1940s to dispose of large pieces of radioactively contaminated equipment. These containers are typically large steel-reinforced concrete boxes, which weigh as much as 40 tons. Because large quantities of high-dose waste can produce radiation levels as high as 200 mrem/hour at 200 ft, the containers are remotely handled (either lifted off the railcar by crane or dragged off with a cable). Many of the existing containers do not meet existing structural and safety design criteria and some of the transportation requirements. The drag-off method of pulling the box off the railcar using a cable and a tractor is also not considered a safe operation, especially in view of past mishaps.
Date: September 1, 1994
Creator: Amir, S. J.
Object Type: Report
System: The UNT Digital Library
Computer-controlled data communications test center (open access)

Computer-controlled data communications test center

This paper describes the software developed for a computer-based test center used in testing and diagnosing a large network of terminal and remote processor communications links. The software runs in time-base-scheduled and on-demand interactive modes. It includes a control program, several measurement tasks, Datatrieve-11 databases, and various graphical display programs, all running under RSX11M, V4.0, on a PDP-11/70.
Date: January 1, 1982
Creator: Horning, R. R.; Creel, L. R. & Doll, M. A.
Object Type: Article
System: The UNT Digital Library
Optimally Controlled Flexible Fuel Powertrain System (open access)

Optimally Controlled Flexible Fuel Powertrain System

The primary objective of this project was to develop a true Flex Fuel Vehicle capable of running on any blend of ethanol from 0 to 85% with reduced penalty in usable vehicle range. A research and development program, targeting 10% improvement in fuel economy using a direct injection (DI) turbocharged spark ignition engine was conducted. In this project a gasoline-optimized high-technology engine was considered and the hardware and configuration modifications were defined for the engine, fueling system, and air path. Combined with a novel engine control strategy, control software, and calibration this resulted in a highly efficient and clean FFV concept. It was also intended to develop robust detection schemes of the ethanol content in the fuel integrated with adaptive control algorithms for optimized turbocharged direct injection engine combustion. The approach relies heavily on software-based adaptation and optimization striving for minimal modifications to the gasoline-optimized engine hardware system. Our ultimate objective was to develop a compact control methodology that takes advantage of any ethanol-based fuel mixture and not compromise the engine performance under gasoline operation.
Date: December 31, 2010
Creator: Yilmaz, Hakan; Christie, Mark & Stefanopoulou, Anna
Object Type: Report
System: The UNT Digital Library
CARBON DIOXIDE MITIGATION THROUGH CONTROLLED PHOTOSYNTHESIS (open access)

CARBON DIOXIDE MITIGATION THROUGH CONTROLLED PHOTOSYNTHESIS

This research was undertaken to meet the need for a robust portfolio of carbon management options to ensure continued use of coal in electrical power generation. In response to this need, the Ohio Coal Research Center at Ohio University developed a novel technique to control the emissions of CO{sub 2} from fossil-fired power plants by growing organisms capable of converting CO{sub 2} to complex sugars through the process of photosynthesis. Once harvested, the organisms could be used in the production of fertilizer, as a biomass fuel, or fermented to produce alcohols. In this work, a mesophilic organism, Nostoc 86-3, was examined with respect to the use of thermophilic algae to recycle CO{sub 2} from scrubbed stack gases. The organisms were grown on stationary surfaces to facilitate algal stability and promote light distribution. The testing done throughout the year examined properties of CO{sub 2} concentration, temperature, light intensity, and light duration on process viability and the growth of the Nostoc. The results indicate that the Nostoc species is suitable only in a temperature range below 125 F, which may be practical given flue gas cooling. Further, results indicate that high lighting levels are not suitable for this organism, as bleaching occurs …
Date: October 1, 2000
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Automated controlled-potential coulometer for plutonium determination (open access)

Automated controlled-potential coulometer for plutonium determination

The automated controlled-potential coulometer for the determination of plutonium described in this report is the second in a series of automated instruments designed to determine plutonium and uranium contents in nuclear fuel cycle materials. The measurement precision of the instrument is 0.1% relative standard deviation at the 5-mg plutonium level. A highly selective method of analysis was developed, involving reduction of plutonium to Pu(III) in a 5.5 M hydrochloric acid-0.015 M sulfamic acid electrolyte; oxidation of diverse ions, but not Pu(III); addition of phosphate complexant to reduce the Pu(III)-Pu(IV) potential; and oxidation of Pu(III) to Pu(IV) as the measurement step. Construction details of the mechanical and electrical systems of the instrument and control-system software are described, along with instrument preoperational adjustments and tests and sample analysis operations.
Date: May 1, 1981
Creator: Hollen, R. M. & Jackson, D. D.
Object Type: Report
System: The UNT Digital Library