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582
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171
Government Accountability Office Reports
80
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23
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897 Matching Results
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Quantifying the value that energy efficiency and renewable energy provide as a hedge against volatile natural gas prices
Advocates of energy efficiency and renewable energy have long argued that such technologies can mitigate fuel price risk within a resource portfolio. Such arguments--made with renewed vigor in the wake of unprecedented natural gas price volatility during the winter of 2000/2001--have mostly been qualitative in nature, however, with few attempts to actually quantify the price stability benefit that these sources provide. In evaluating this benefit, it is important to recognize that alternative price hedging instruments are available--in particular, gas-based financial derivatives (futures and swaps) and physical, fixed-price gas contracts. Whether energy efficiency and renewable energy can provide price stability at lower cost than these alternative means is therefore a key question for resource acquisition planners. In this paper we evaluate the cost of hedging gas price risk through financial hedging instruments. To do this, we compare the price of a 10-year natural gas swap (i.e., what it costs to lock in prices over the next 10 years) to a 10-year natural gas price forecast (i.e., what the market is expecting spot natural gas prices to be over the next 10 years). We find that over the past two years natural gas users have had to pay a premium as high …
Date:
May 15, 2002
Creator:
Bolinger, Mark; Wiser, Ryan; Bachrach, Devra & Golove, William
Object Type:
Article
System:
The UNT Digital Library
Electronic Structure of Germanium Nanocrystal Films Probed with Synchrotron Radiation
The fundamental structure--property relationship of semiconductor quantum dots has been investigated. For deposited germanium nanocrystals strong quantum confinement effects have been determined with synchrotron radiation based x-ray absorption and photoemission techniques. The nanocrystals are condensed out of the gas phase with a narrow size distribution and subsequently deposited in situ onto various substrates. The particles are crystalline in the cubic phase with a structurally disordered surface shell and the resulting film morphology depends strongly on the substrate material and condition. The disordered surface region has an impact on the overall electronic structure of the particles. In a size-dependent study, the conduction and valence band edge of germanium nanocrystals have been measured for the first time and compared to the bulk crystal. The band edges move to higher energies as the particle size is decreased, consistent with quantum confinement theory. To obtain a more accurate analysis of confinement effects in the empty states, a novel analysis method utilizing an effective particle size for the x-ray absorption experiment, which allows a deconvolution of absorption edge broadening effects, has been introduced. Comparison of the present study to earlier studies on silicon reveals that germanium exhibits stronger quantum confinement effects than silicon. Below a …
Date:
May 1, 2002
Creator:
Bostedt, C
Object Type:
Report
System:
The UNT Digital Library
A computer simulation appraisal of non-residential low energy cooling systems in California
An appraisal of the potential performance of different Low Energy Cooling (LEC) systems in nonresidential buildings in California is being conducted using computer simulation. The paper presents results from the first phase of the study, which addressed the systems that can be modeled, with the DOE-2.1E simulation program. The following LEC technologies were simulated as variants of a conventional variable-air-volume system with vapor compression cooling and mixing ventilation in the occupied spaces: Air-side indirect and indirect/direct evaporative pre-cooling. Cool beams. Displacement ventilation. Results are presented for four populous climates, represented by Oakland, Sacramento, Pasadena and San Diego. The greatest energy savings are obtained from a combination of displacement ventilation and air-side indirect/direct evaporative pre-cooling. Cool beam systems have the lowest peak demand but do not reduce energy consumption significantly because the reduction in fan energy is offse t by a reduction in air-side free cooling. Overall, the results indicate significant opportunities for LEC technologies to reduce energy consumption and demand in nonresidential new construction and retrofit.
Date:
May 17, 2002
Creator:
Bourassa, Norman; Haves, Philip & Huang, Joe
Object Type:
Article
System:
The UNT Digital Library
Mechanical relaxation of localized residual stresses associatedwith foreign object damage
Foreign-object damage associated with the ingestion ofdebris into aircraft turbine engines can lead to a marked degradation inthe high-cycle fatigue life of turbine components. This degradation isgenerally considered to be associated with the premature initiation offatigue cracks at or near the damage sites; this is suspected to be dueto, at least in part, the impact-induced residual stress state, which canbe strongly tensile in these locations.
Date:
May 1, 2002
Creator:
Boyce, B. L.; Chen, X.; Peters, J. O.; Hutchinson, J. W. & Ritchie, R. O.
Object Type:
Article
System:
The UNT Digital Library
Fruits and Vegetables: Issues for Congress
This report discusses the Issues for Congress on Fruits and Vegetables.The primary law that exclusively serves the produce industry is the perishable agriculture commodities act in the 1930(PACA).
Date:
May 29, 2002
Creator:
Branaman, Brenda
Object Type:
Report
System:
The UNT Digital Library
The Leading Particle Effect from Heavy-Quark Recombination
The leading particle effect in charm hadroproduction is an enhancement of the cross section for a charmed hadron D in the forward direction of the beam when the beam hadron has a valence parton in common with the D. The large D+/D- asymmetry observed by the E791 experiment is an example of this phenomenon. We show that the heavy-quark recombination mechanism provides an economical explanation for this effect. In particular, the D+/D- asymmetry can be fit reasonably well using a single parameter whose value is consistent with a recent determination from charm photoproduction.
Date:
May 1, 2002
Creator:
Braten, Eric; Jia, Yu & Mehen, Thomas
Object Type:
Article
System:
The UNT Digital Library
Characterization of Microbial Communities from Pristine and Chlorinated-Ethene-Contaminated Landfill Groundwater
Molecular, phospholipid fatty acid analysis (PLFA), and substrate utilization (BIOLOG) techniques were used to assess structural and functional differences between microbial communities from a chlorinated-ethene (CE)-contaminated groundwater at a sanitary landfill. The information will be used to evaluate natural attenuation of the associated CE plume. Two groundwater-monitoring wells were tested.
Date:
May 17, 2002
Creator:
Brigmon, R.L.
Object Type:
Article
System:
The UNT Digital Library
Molecular Dynamics Simulations of Coulomb Explosion
A swift ion creates a track of electronic excitations in the target material. A net repulsion inside the track can cause a ''Coulomb Explosion'', which can lead to damage and sputtering of the material. Here we report results from molecular-dynamics (MD) simulations of Coulomb explosion for a cylindrical track as a function of charge density and neutralization/quenching time, {tau}. Screening by the free electrons is accounted for using a screened Coulomb potential for the interaction among charges. The yield exhibits a prompt component from the track core and a component, which dominates at higher excitation density, from the heated region produced. For the cases studied, the number of atoms ejected per incident ion, i.e. the sputtering yield Y, is quadratic with charge density along the track as suggested by simple models. Y({tau} = 0.2 Debye periods) is nearly 20% of the yield when there is no neutralization ({tau} {yields} {infinity}). The connections between ''Coulomb explosions'', thermal spikes and measurements of electronic sputtering are discussed.
Date:
May 17, 2002
Creator:
Bringa, E M
Object Type:
Article
System:
The UNT Digital Library
Pyrolysis and Combustion of Acetonitrile (CH{sub 3}CN)
Acetonitrile (CH{sub 3}CN) is formed from the thermal decomposition of a variety of cyclic, noncyclic, and polymeric nitrogen-containing compounds such as pyrrole and polyacrylonitrile. The pyrolysis and combustion of acetonitrile have been studied over the past 30 years to gain a more detailed understanding of the complex mechanisms involved in the release of nitrogen-containing compounds such as hydrogen cyanide (HCN) in fires and nitrogen oxides (NOx) in coal combustion. This report reviews the literature on the formation of HCN and NOx from the pyrolysis and combustion of acetonitrile and discusses the possible products found in an acetonitrile fire.
Date:
May 22, 2002
Creator:
Britt, P. F.
Object Type:
Report
System:
The UNT Digital Library
The Neutron Magnetic Form Factor at High Q{sup 2}: Experimental Status, Future Measurements
Recent progress in improving our knowledge of the four nucleon form factors G{sup p}{sub M}, G{sup p}{sub E}, G{sup n}{sub M}, G{sup n}{sub E} at high momentum transfer is stimulating a new wave of theoretical efforts to describe these fundamental quantities. Both model calculations and lattice QCD can predict the elastic form factors; a definitive, stringent test of these efforts is to predict all of them simultaneously. However, the limited range and quality of the data for the neutron magnetic form factor G{sup n}{sub M} presently reduce the discriminating power of such a test. The present status of our knowledge of G{sup n}{sub M} is discussed, and prospects for future improvements are presented.
Date:
May 1, 2002
Creator:
Brooks, Will
Object Type:
Article
System:
The UNT Digital Library
Updated ENDL99 Cross Sections for U(n.y) and U(n,f)
In this note, we describe the first of two updates to the uranium isotopes in Livermore's Evaluated Neutron Data Library, ENDL99. Here, we concentrate on improving the (n, f) and (n, {gamma}) evaluations for a limited set of uranium isotopes. The first improvement consisted of creating an evaluation for {sup 232}U using a combination of fission and capture cross sections from the JENDL-3.2 database and the outgoing particle distributions from the exiting ENDL99 {sup 234}U evaluation. The second improvement consisted of updating existing (n, f) and (n, {gamma}) evaluations for uranium isotopes with A=233-238. These improvements are particularly apparent in the neutron resonance region as ENDL99 often contains gross averages over the resonances. We have propagated these updates into various Livermore application libraries.
Date:
May 7, 2002
Creator:
Brown, D.; Dietrich, F.; Hill, T. & McNabb, D.
Object Type:
Report
System:
The UNT Digital Library
MONITORING POWER PLANT EFFICIENCY USING THE MICROWAVE-EXCITED PHOTOACOUSTIC EFFECT TO MEASURE UNBURNED CARBON
Three test instruments are being evaluated to determine the feasibility of using photo-acoustic technology for measuring unburned carbon in fly ash. The first test instrument is a single microwave frequency system previously constructed to measure photo-acoustic signals in an off-line configuration. This system was assembled and used to begin testing parameters thought to be influential in the resulting photo-acoustic signal output. A standard modulation frequency was chosen based upon signal to noise data gained from experimentation. Sample heterogeneity was tested and found not to be influential. Many other tests were performed during the second quarter. Preliminary results show that compression and photo-acoustic volume have an impact on photo-acoustic signal. Conclusions regarding the data for sample bulk density, temperature, humidity, moisture content, and linearity are pending further review. Conclusions for ambient temperature and humidity are pending further review as well. Simultaneously, a second instrument is to be constructed based in part on lessons learned with the first instrument, and to expand the capabilities of the first instrument. Improvements include a control loop to allow more constant microwave power output and an ability to operate over a range of microwave frequencies. To date, the design of the second instrument has been completed …
Date:
May 13, 2002
Creator:
Brown, Robert C.; Weber, Robert J. & Suby, Andrew A.
Object Type:
Report
System:
The UNT Digital Library
Global Taxation and the United Nations: A Review of Proposals
A discussion of the possibility of the United Nations promoting and planning imposition of international taxation on U.N. member states, including the United States was initiated in response to the March 2002 U.N.-sponsored International Conference on Financing for Development, held in Monterrey, Mexico.
Date:
May 3, 2002
Creator:
Browne, Marjorie Ann
Object Type:
Report
System:
The UNT Digital Library
The Law of the Sea Convention and U.S. Policy
None
Date:
May 28, 2002
Creator:
Browne, Marjorie Ann
Object Type:
Report
System:
The UNT Digital Library
United Nations Peacekeeping: Issues for Congress
None
Date:
May 31, 2002
Creator:
Browne, Marjorie Ann
Object Type:
Report
System:
The UNT Digital Library
Special Operations Forces in Operation Enduring Freedom: Background and Issues for Congress
None
Date:
May 23, 2002
Creator:
Bruner, Edward F.; Bolkcom, Christopher & O'Rourke, Ronald
Object Type:
Report
System:
The UNT Digital Library
Immigration Legislation and Issues in the 107th Congress
This report briefs the Immigration legislation and issues in the 107th Congress.
Date:
May 28, 2002
Creator:
Bruno, Andorra; Wasem, Ruth Ellen; Seghetti, Lisa M.; Siskin, Alison & Ester, Karma
Object Type:
Report
System:
The UNT Digital Library
Science & Technology Review May 2002
None
Date:
May 1, 2002
Creator:
Budil, K S
Object Type:
Report
System:
The UNT Digital Library
Physical Characterization of Solid-Liquid Slurries at High Weight Fractions Using Optical and Ultrasonic Methods
The goal of this proposed work is to directly address the need for rapid on-line characterization of the physical properties of HLW slurries during all phases of the remediation process, from in-tank characterization of sediments to monitoring of the concentration, particle size, and degree of agglomeration and gelation of slurries during transport. This will be done with both optical and ultrasonic methods. There are three tasks: (1) develop optical and acoustic measurements to provide the fundamental science needed for successful device development and implementation, (2) develop theories that describe the interrelationship between wave propagation and the physical properties of the slurry, and (3) solve, in the framework of these theories, the inversion problem and compare them with the experimental measurements to non-intrusively characterize slurries.
Date:
May 28, 2002
Creator:
Burgess, L. W.; Brodsky, A. M.; Panetta, P. D.; Pappas, R. A.; Bond, L. J. & Bamberger, J. A.
Object Type:
Report
System:
The UNT Digital Library
Welfare Reform: An Issue Overview
The House passed a bill (H.R. 3146) on September 24 to extend TAIF, mandatory child care, abstinence education, and transitional Medicaid, on current terms, through March 31, 2004. In the absence of legislation, these programs would expire on September 30. The Senate Finance Committee approved a comprehensive TAIF preauthorization proposal of Chairman Chuck Grassley on September 10. Entitled Personal Responsibility and Individual Development for Everyone (PRIDE), the legislation would extend TANF, mandatory child care, abstinence education, and transitional Medicaid for 5 years, FY2004 through FY2008. It would raise TANF work participation standards, increase weekly work hours, add new countable work activities,
Date:
May 17, 2002
Creator:
Burke, Vee
Object Type:
Report
System:
The UNT Digital Library
Active and passive safety control performance in sub - critical, accelerator - driven nuclear reactors.
Traditional safety performance requirements for nuclear reactors have been developed for critical reactors, whose kinetics characteristics differ significantly from sub-critical, accelerator-driven nuclear reactors. In a critical nuclear reactor, relatively small amounts of reactivity (negative or positive) can produce large changes in the fission rate. In sub-critical reactors, the self-multiplication (k) decreases as the sub-criticality (1-k) increases, and the responsiveness to small reactivity changes decreases. This makes sub-critical nuclear reactors less responsive to positive reactivity insertions than critical reactors. Also, larger negative reactivity insertions are needed in sub-critical reactors to shut down the fission chain if the neutron source remains. This paper presents the results from a computational analysis of the safety performance of sub-critical, accelerator-driven nuclear reactors. Coupled kinetics and thermal-hydraulics models are used to quantify the effectiveness of traditional protection and control system designs in sub-critical reactors. The analyses also quantify the role of inherent, passive reactivity feedback mechanisms in sub-critical reactors. Computational results are used to develop conclusions regarding the most favorable and effective means for reactor control and protection in sub-critical, accelerator-driven nuclear reactors.
Date:
May 24, 2002
Creator:
Cahalan, J. E. & Eriksson, M.
Object Type:
Article
System:
The UNT Digital Library
Non-Linear Dose-Response Relationships in Biology, Toxicology and Medicine - An International Conference
Conference abstract book contains seven sections: Plenary-4 abstracts; Chemical-9 abstracts; Radiation-7 abstracts; Ultra Low Doses and Medicine-6 abstracts; Biomedical-11 abstracts; Risk Assessment-5 abstracts and Poster Sessions-25 abstracts. Each abstract was provided by the author/presenter participating in the conference.
Date:
May 28, 2002
Creator:
Calabrese, Edward J. & Kostecki, Paul T.
Object Type:
Article
System:
The UNT Digital Library
Progress in Heavy Ion Target Capsule and Hohlraum Design
Progress in heavy ion target design over the past few years has focused on relaxing the target requirements for the driver and for target fabrication. We have designed a plastic (CH) ablator capsule that is easier to fabricate and fill than the beryllium ablator we previously used. In addition, 2-d Rayleigh-Taylor instability calculations indicate that this capsule can tolerate ablator surface finishes up to ten times rougher than the NIF specification. We have also explored the trade-off between surface roughness and yield as a method for finding the optimum capsule. We have also designed two new hohlraums: a ''hybrid'' target and a large angle, distributed radiator target. The hybrid target allows a beam spot radius of almost 5 mm while giving gain of 55 from 6.7 MJ of beam energy in integrated Lasnex calculations. To achieve the required symmetry with the large beam spot, internal shields were used in the target to control the P2 and P4 asymmetry. The large-angle, distributed radiator target is a variation on the distributed radiator target that allows large beam entrance angles (up to 24 degrees). Integrated calculations have produced 340 MJ from 6.2 MJ of beam energy in a design that is not quite …
Date:
May 8, 2002
Creator:
Callahan, D. A.; Herrmann, M. C. & Tabak, M.
Object Type:
Article
System:
The UNT Digital Library
Low Wind Speed Technology Development in the U.S. Department of Energy Wind Energy Research Program: Preprint
The United States Department of Energy (DOE) Wind Energy Research Program has begun a new effort to develop wind technology that will allow wind systems to compete in regions of low wind speed. The sites targeted by this effort have annual average wind speeds of 5.8 m/s measured at a 10-meter height. Such sites are abundant in the United States and would increase the land area available for economic development twentyfold. DOE has initiated a three-element approach through a competitive request for proposals. The three elements in the RFP include concept design, component development, and system development. This work will build on previous activities under the WindPACT Program and the Next Generation Turbine Program. The new program is targeting a levelized cost of energy of 3/kWh at low wind speed sites by 2010 and supports the U.S. wind industry's goal of reaching an installed domestic wind capacity of 100 GW by 2020.
Date:
May 1, 2002
Creator:
Calvert, S.; Thresher, R.; Hock, S.; Laxson, A. & Smith, B.
Object Type:
Article
System:
The UNT Digital Library