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11,553 Matching Results
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Global Cooling: Increasing World-Wide Urban Albedos to Offset CO2
Modification of urban albedos reduces summertime urban temperatures, resulting in a better urban air quality and building air-conditioning savings. Furthermore, increasing urban albedos has the added benefit of reflecting some of the incoming global solar radiation and countering to some extent the effects of global warming. In many urban areas, pavements and roofs constitute over 60% of urban surfaces (roof 20-25%, pavements about 40%). Using reflective materials, both roof and the pavement albedos can be increased by about 0.25 and 0.10, respectively, resulting in a net albedo increase for urban areas of about 0.1. Many studies have demonstrated building cooling-energy savings in excess of 20% upon raising roof reflectivity from an existing 10-20% to about 60% (a U.S. potential savings in excess of $1 billion (B) per year in net annual energy bills). On a global basis, our preliminary estimate is that increasing the world-wide albedos of urban roofs and paved surfaces will induce a negative radiative forcing on the earth equivalent to removing {approx} 22-40 Gt of CO{sub 2} from the atmosphere. Since, 55% of the emitted CO{sub 2} remains in the atmosphere, removal of 22-40 Gt of CO{sub 2} from the atmosphere is equivalent to reducing global CO{sub …
Date:
January 14, 2008
Creator:
Akbari, Hashem; Menon, Surabi & Rosenfeld, Arthur
Object Type:
Article
System:
The UNT Digital Library
Development of a Novel Catalyst for NO Decomposition
Air pollution arising from the emission of nitrogen oxides as a result of combustion taking place in boilers, furnaces and engines, has increasingly been recognized as a problem. New methods to remove NOx emissions significantly and economically must be developed. The current technology for post-combustion removal of NO is the selective catalytic reduction (SCR) of NO by ammonia or possibly by a hydrocarbon such as methane. The catalytic decomposition of NO to give N2 will be preferable to the SCR process because it will eliminate the costs and operating problems associated with the use of an external reducing species. The most promising decomposition catalysts are transition metal (especially copper)-exchanged zeolites, perovskites, and noble metals supported on metal oxides such as alumina, silica, and ceria. The main shortcoming of the noble metal reducible oxide (NMRO) catalysts is that they are prone to deactivation by oxygen. It has been reported that catalysts containing tin oxide show oxygen adsorption behavior that may involve hydroxyl groups attached to the tin oxide. This is different than that observed with other noble metal-metal oxide combinations, which have the oxygen adsorbing on the noble metal and subsequently spilling over to the metal oxide. This observation leads one …
Date:
March 14, 2007
Creator:
Akyurtlu, Ates & Akyurtlu, Jale F.
Object Type:
Report
System:
The UNT Digital Library
Development Of A Novel Catalyst For No Decomposition
Air pollution arising from the emission of nitrogen oxides as a result of combustion taking place in boilers, furnaces and engines, has increasingly been recognized as a problem. New methods to remove NO{sub x} emissions significantly and economically must be developed. The current technology for post-combustion removal of NO is the selective catalytic reduction (SCR) of NO by ammonia or possibly by a hydrocarbon such as methane. The catalytic decomposition of NO to give N2 will be preferable to the SCR process because it will eliminate the costs and operating problems associated with the use of an external reducing species. The most promising decomposition catalysts are transition metal (especially copper)-exchanged zeolites, perovskites, and noble metals supported on metal oxides such as alumina, silica, and ceria. The main shortcoming of the noble metal reducible oxide (NMRO) catalysts is that they are prone to deactivation by oxygen. It has been reported that catalysts containing tin oxide show oxygen adsorption behavior that may involve hydroxyl groups attached to the tin oxide. This is different than that observed with other noble metal-metal oxide combinations, which have the oxygen adsorbing on the noble metal and subsequently spilling over to the metal oxide. This observation leads …
Date:
September 14, 2006
Creator:
Akyurtlu, Ates & Akyurtlu, Jale F.
Object Type:
Report
System:
The UNT Digital Library
Comparison of Experimental and Model Data for the Evaporation of a Synthetic Topopah Spring Tuff Pore Water, Yucca Mountain, NV
The evaporation of a range of synthetic pore water solutions representative of the potential high-level-nuclear-waste repository at Yucca Mountain, NV is being investigated. The motivation of this work is to understand and predict the range of brine compositions that may contact the waste containers from evaporation of pore waters, because these brines could form corrosive thin films on the containers and impact their long-term integrity. A relatively complex synthetic Topopah Spring Tuff pore water was progressively concentrated by evaporation in a closed vessel, heated to 95 C in a series of sequential experiments. Periodic samples of the evaporating solution were taken to determine the evolving water chemistry. According to chemical divide theory at 25 C and 95 C our starting solution should evolve towards a high pH carbonate brine. Results at 95 C show that this solution evolves towards a complex brine that contains about 99 mol% Na{sup +} for the cations, and 71 mol% Cl{sup -}, 18 mol% {Sigma}CO{sub 2}(aq), 9 mol% SO{sub 4}{sup 2-} for the anions. Initial modeling of the evaporating solution indicates precipitation of aragonite, halite, silica, sulfate and fluoride phases. The experiments have been used to benchmark the use of the EQ3/6 geochemical code in …
Date:
October 14, 2003
Creator:
Alai, M; Sutton, M & Carroll, S
Object Type:
Article
System:
The UNT Digital Library
Oxygen Isotopes in Chondritic Interplanetary Dust: Parent-Bodies and Nebular Oxygen Reservoirs
Planetary objects have preserved various amounts of oxygen issued from isotopically different oxygen reservoirs reflecting their origin and physico-chemical history. An {sup 16}O-rich component is preserved in refractory inclusions (CAIs) whereas meteorites matrices are enriched in an {sup 16}O-poor component. The origin of these components is still unclear. The most recent models are based on isotope selective photodissociation of CO in a {sup 16}O-rich nebula/presolr cloud resulting in a {sup 16}O-poor gas in the outer part of the nebula. However because most meteorite components are thought to be formed in the inner 3AU of the solar nebula, the precise isotopic composition of outer solar system components is yet unknown. In that respect, the oxygen isotopic composition of cometary dust is a key to understand the origin of the solar system. The Stardust mission will bring back to the Earth dust samples from comet Wild2, a short period comet from the Jupiter family. A precise determination of the oxygen isotope composition of Wild2 dust grains is essential to decipher the oxygen reservoirs of the outer solar system. However, Stardust samples may be extremely fragmented upon impact in the collector. In addition, interplanetary dust particles (IDPs) collected in the stratosphere are likely …
Date:
February 14, 2006
Creator:
Aleon, J.; McKeegan, K. D. & Leshin, L.
Object Type:
Article
System:
The UNT Digital Library
Development of a CO2 Sequestration Module by Integrating Mineral Activation and Aqueous Carbonation
Mineral carbonation is a promising concept for permanent CO{sub 2} sequestration due to the vast natural abundance of the raw materials and the permanent storage of CO{sub 2} in solid form as carbonates. The sequestration of CO{sub 2} through the employment of magnesium silicates--olivine and serpentine--is beyond the proof of concept stage. For the work done in this project, serpentine was chosen as the feedstock mineral due to its abundance and availability. Although the reactivity of olivine is greater than that of serpentine, physical and chemical treatments have been shown to increase greatly the reactivity of serpentine. The primary drawback to mineral carbonation is reaction kinetics. To accelerate the carbonation, aqueous processes are preferred, where the minerals are first dissolved in solution. In aqueous carbonation, the key step is the dissolution rate of the mineral, where the mineral dissolution reaction is likely to be surface-controlled. The relatively low reactivity of serpentine has warranted research into physical and chemical treatments that have been shown to greatly increase its reactivity. The use of sulfuric acid as an accelerating medium for the removal of magnesium from serpentine has been investigated. To accelerate the dissolution process, the mineral can be ground to very fine …
Date:
August 14, 2006
Creator:
Alexander, George; Aksoy, Parvana; Andresen, John; Maroto-Valer, Mercedes & Schobert, Harold
Object Type:
Report
System:
The UNT Digital Library
Whales and Sonar: Environmental Exemptions for the Navy's Mid-Frequency Active Sonar Training
This report discusses laws related to the protection of marine mammals when using mid-frequency active sonar including the Marine Mammal Protection Act (MMPA), the Endangered Species Act (ESA), the National Environmental Policy Act (NEPA), and the Coastal Zone Management Act (CZMA). The report discusses each of the laws generally, and then reviews the litigation surrounding the Navy's compliance with these laws in the context of using the sonar for training purposes off California's coast.
Date:
November 14, 2008
Creator:
Alexander, Kristina
Object Type:
Report
System:
The UNT Digital Library
Timpson & Tenaha News (Timpson, Tex.), Vol. 18, No. 32, Ed. 1 Thursday, August 14, 2003
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
August 14, 2003
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 19, No. 40, Ed. 1 Thursday, October 14, 2004
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
October 14, 2004
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 20, No. 14, Ed. 1 Thursday, April 14, 2005
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
April 14, 2005
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 20, No. 26, Ed. 1 Thursday, July 14, 2005
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
July 14, 2005
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 21, No. 37, Ed. 1 Thursday, September 14, 2006
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
September 14, 2006
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 21, No. 50, Ed. 1 Thursday, December 14, 2006
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
December 14, 2006
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 25, No. 23, Ed. 1 Thursday, June 14, 2007
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
June 14, 2007
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 26, No. 7, Ed. 1 Thursday, February 14, 2008
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
February 14, 2008
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 26, No. 33, Ed. 1 Thursday, August 14, 2008
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
August 14, 2008
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 28, No. 18, Ed. 1 Thursday, May 14, 2009
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
May 14, 2009
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Solubility of Budesonide, Hydrocortisone, and Prednisolone in Ethanol + Water Mixtures at 298.2 K
This article discusses the solubility of budesonide, hydrocortisone, and prednisolone in ethanol and water mixtures at 298.2 K.
Date:
September 14, 2009
Creator:
Ali, Hany Saleh Mohamed; Blagden, Nicholas; York, Peter; Soltanpour, Shahla; Acree, William E. (William Eugene) & Jouyban, Abolghasem
Object Type:
Article
System:
The UNT Digital Library
THE SECOND STAGE OF FERMI@ELETTRA: A SEEDED FEL IN THE SOFT X-RAY SPECTRAL RANGE
The second stage of the FERMI FEL, named FEL-2, is based on the principle of high-gain harmonic generation and relies on a double-seeded cascade. Recent developments stimulated a revision of the original setup, which was designed to cover the spectral range between 40 and 10 nm. The numerical simulations we present here show that the nominal (expected) electron-beam performance allows extension of the FEL spectral range down to 4 nm. A significant amount of third harmonic power can be also expected. We also show that the proposed setup is flexible enough for exploiting future developments of new seed sources, e.g., high harmonic generation in gases.
Date:
August 14, 2009
Creator:
Allaria, E.; DeNinno, G. & Fawley, W. M.
Object Type:
Article
System:
The UNT Digital Library
Studies of vibrational properties in Ga stabilized delta-Pu by extended X-ray absorption fine structure
Temperature dependent extended x-ray absorption fine structure (EXAFS) spectra were measured for a 3.3 at. % Ga stabilized Pu alloy over the range T= 20 - 300 K. EXAFS data were acquired at both the Ga K-edge and the Pu L{sub III} edge. Curve-fits were performed to the first shell interactions to obtain pair-distance distribution widths, {sigma}, as a function of temperature. The temperature dependence of {sigma}(T) was accurately modeled using a correlated-Debye model for the lattice vibrational properties, suggesting Debye-like behavior in this material. Using this formalism, we obtain pair-specific correlated-Debye temperatures, {Theta}{sub cD}, of 110.7 {+-} 1.7 K and 202.6 {+-} 3.7 K, for the Pu-Pu and Ga-Pu pairs, respectively. The result for the Pu-{Theta}{sub cD} value compares well with previous vibrational studies on {delta}-Pu. In addition, our results represent the first unambiguous determination of Ga-specific vibrational properties in Pu-Ga alloys, i.e, {Theta}{sub cD} for the Ga-Pu pair. Because the Debye temperature can be related to a measure of the lattice stiffness, these results indicate the Ga-Pu bonds are significantly stronger than the Pu-Pu bonds. This effect has important implications for lattice stabilization mechanisms in these alloys.
Date:
February 14, 2002
Creator:
Allen, P. G.; Henderson, A. L.; Sylwester, E. R.; Turchi, P. E. A.; Shen, T. H.; Gallegos, G. F. et al.
Object Type:
Article
System:
The UNT Digital Library
Water and Energy Savings using Demand Hot Water Recirculating Systems in Residential Homes: A Case Study of Five Homes in Palo Alto, California
This report summarizes a preliminary study aimed at estimating the potential of saving potable water, (and the electrical energy used to heat it), that is presently lost directly to the drain while occupants wait for hot water to arrive at the faucet (point of use). Data were collected from five single-family homes in Palo Alto, California. Despite the small sample size in this study, the results make a compelling case for retrofitting homes with hot water recirculation systems to eliminate unnecessary wastage of water at the point of use. Technical as well as behavioral and attitudinal changes towards water conservation are necessary for a fulfilling and successful conservation effort. This report focuses on the technical issues, but behavioral issues are also noted, which may be factored into future studies involving local and state governments and utility companies.
Date:
November 14, 2002
Creator:
Ally, M.R.
Object Type:
Report
System:
The UNT Digital Library
Handling Pyrophoric Reagents
Pyrophoric reagents are extremely hazardous. Special handling techniques are required to prevent contact with air and the resulting fire. This document provides several methods for working with pyrophoric reagents outside of an inert atmosphere.
Date:
August 14, 2009
Creator:
Alnajjar, Mikhail S. & Haynie, Todd O.
Object Type:
Report
System:
The UNT Digital Library
Criticality Model
The ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2003) presents the methodology for evaluating potential criticality situations in the monitored geologic repository. As stated in the referenced Topical Report, the detailed methodology for performing the disposal criticality analyses will be documented in model reports. Many of the models developed in support of the Topical Report differ from the definition of models as given in the Office of Civilian Radioactive Waste Management procedure AP-SIII.10Q, ''Models'', in that they are procedural, rather than mathematical. These model reports document the detailed methodology necessary to implement the approach presented in the Disposal Criticality Analysis Methodology Topical Report and provide calculations utilizing the methodology. Thus, the governing procedure for this type of report is AP-3.12Q, ''Design Calculations and Analyses''. The ''Criticality Model'' is of this latter type, providing a process evaluating the criticality potential of in-package and external configurations. The purpose of this analysis is to layout the process for calculating the criticality potential for various in-package and external configurations and to calculate lower-bound tolerance limit (LBTL) values and determine range of applicability (ROA) parameters. The LBTL calculations and the ROA determinations are performed using selected benchmark experiments that are applicable to various waste forms …
Date:
September 14, 2004
Creator:
Alsaed, A.
Object Type:
Report
System:
The UNT Digital Library
Oral History Interview with Abelino Alviar, March 14, 2003
The National Museum of the Pacific War presents an interview with Abelino Alviar. Alviar joined the Army in May of 1944. In early 1945, he joined the 778th Anti-aircraft Artillery Automatic Weapons Battalion. They deployed to Le Havre, France, and traveled to Munich, Germany, arriving after the Battle of the Ardennes. Alviar provided guard duty, and served as a gunner on the half-track supporting the 1st Infantry Division as they fought into Germany. He also worked as a translator and helped transport supplies to the front line. He returned home and was discharged in May of 1946.
Date:
March 14, 2003
Creator:
Alviar, Abelino
Object Type:
Sound
System:
The Portal to Texas History