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Abstract: Air, Thermal and Water Management for PEM Fuel Cell Systems (open access)

Abstract: Air, Thermal and Water Management for PEM Fuel Cell Systems

PEM fuel cells are excellent candidates for transportation applications due to their high efficiencies. PEM fuel cell Balance of Plant (BOP) components, such as air, thermal, and water management sub-systems, can have a significant effect on the overall system performance, but have traditionally not been addressed in research and development efforts. Recognizing this, the U.S. Department of Energy and Honeywell International Inc. are funding an effort that emphasizes the integration and optimization of air, thermal and water management sub-systems. This effort is one of the major elements to assist the fuel cell system developers and original equipment manufacturers to achieve the goal of an affordable and efficient power system for transportation applications. Past work consisted of: (1) Analysis, design, and fabrication of a motor driven turbocompressor. (2) A systematic trade study to select the most promising water and thermal management systems from five different concepts (absorbent wheel humidifier, gas to gas membrane humidifier, porous metal foam humidifier, cathode recycle compressor, and water injection pump.) This presentation will discuss progress made in the research and development of air, water and thermal management sub-systems for PEM fuel cell systems in transportation applications. More specifically, the presentation will discuss: (1) Progress of the …
Date: October 1, 2008
Creator: Mirza, Mark K. Gee Zia
System: The UNT Digital Library
Geothermal Electricity Technologies Evaluation Model DOE Tool for Assessing Impact of Research on Cost of Power (open access)

Geothermal Electricity Technologies Evaluation Model DOE Tool for Assessing Impact of Research on Cost of Power

The U.S. Department of Energy (DOE) has developed a spreadsheet model to provide insight as to how its research activities can impact of cost of producing power from geothermal energy. This model is referred to as GETEM, which stands for “Geothermal Electricity Technologies Evaluation Model”. Based on user input, the model develops estimates of costs associated with exploration, well field development, and power plant construction that are used along with estimated operating costs to provide a predicted power generation cost. The model allows the user to evaluate how reductions in cost, or increases in performance or productivity will impact the predicted power generation cost. This feature provides a means of determining how specific technology improvements can impact generation costs, and as such assists DOE in both prioritizing research areas and identifying where research is needed.
Date: January 1, 2008
Creator: Mines, Greg
System: The UNT Digital Library
The Advanced Test Reactor Irradiation Capabilities Available as a National Scientific User Facility (open access)

The Advanced Test Reactor Irradiation Capabilities Available as a National Scientific User Facility

The Advanced Test Reactor (ATR) is one of the world’s premiere test reactors for performing long term, high flux, and/or large volume irradiation test programs. The ATR is a very versatile facility with a wide variety of experimental test capabilities for providing the environment needed in an irradiation experiment. These capabilities include simple capsule experiments, instrumented and/or temperature-controlled experiments, and pressurized water loop experiment facilities. Monitoring systems have also been utilized to monitor different parameters such as fission gases for fuel experiments, to measure specimen performance during irradiation. ATR’s control system provides a stable axial flux profile throughout each reactor operating cycle, and allows the thermal and fast neutron fluxes to be controlled separately in different sections of the core. The ATR irradiation positions vary in diameter from 16 mm to 127 mm over an active core height of 1.2 m. This paper discusses the different irradiation capabilities with examples of different experiments and the cost/benefit issues related to each capability. The recent designation of ATR as a national scientific user facility will make the ATR much more accessible at very low to no cost for research by universities and possibly commercial entities.
Date: September 1, 2008
Creator: Grover, S. Blaine
System: The UNT Digital Library
B physics at CDF (open access)

B physics at CDF

We present the latest measurements on production, spectroscopy, lifetimes and branching fractions for b-mesons, b-baryons and quarkonia. We also discuss recent results on B{sub s}{sup 0} mixing as well as on CP violation for the B{sub s}{sup 0} meson and for b-baryons. These results were obtained by analyzing data collected by the CDF II detector at Fermilab.
Date: September 1, 2008
Creator: Papadimitriou, Vaia
System: The UNT Digital Library
Lattice QCD workflows (open access)

Lattice QCD workflows

This paper discusses the application of existing workflow management systems to a real world science application (LQCD). Typical workflows and execution environment used in production are described. Requirements for the LQCD production system are discussed. The workflow management systems Askalon and Swift were tested by implementing the LQCD workflows and evaluated against the requirements. We report our findings and future work.
Date: December 1, 2008
Creator: Piccoli, Luciano; Kowalkowski, James B.; Simone, James N.; Sun, Xian-He; Jin, Hui; Holmgren, Donald J. et al.
System: The UNT Digital Library
Renewable Hydrogen: Integration, Validation, and Demonstration (open access)

Renewable Hydrogen: Integration, Validation, and Demonstration

This paper is about producing hydrogen through the electrolysis of water and using the hydrogen in a fuel cell or internal combustion engine generator to produce electricity during times of peak demand, or as a transportation fuel.
Date: July 1, 2008
Creator: Harrison, K. W. & Martin, G. D.
System: The UNT Digital Library
Modeling Microbunching from Shot Noise Using Vlasov Solvers (open access)

Modeling Microbunching from Shot Noise Using Vlasov Solvers

Unlike macroparticle simulations, which are sensitive to unphysical statistical fluctuations when the number of macroparticles is smaller than the bunch population, direct methods for solving the Vlasov equation are free from sampling noise and are ideally suited for studying microbunching instabilities evolving from shot noise. We review a 2D (longitudinal dynamics) Vlasov solver we have recently developed to study the microbunching instability in the beam delivery systems for x-ray FELs and present an application to FERMI{at}Elettra. We discuss, in particular, the impact of the spreader design on microbunching.
Date: May 1, 2008
Creator: Venturini, Marco; Venturini, Marco & Zholents, Alexander
System: The UNT Digital Library
Measurement of the ratio of the p anti-p ---> W+c-jet cross section to the inclusive p anti-p ---> W+jets cross section (open access)

Measurement of the ratio of the p anti-p ---> W+c-jet cross section to the inclusive p anti-p ---> W+jets cross section

None
Date: March 1, 2008
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System: The UNT Digital Library
Improved Measurement of CP Observables in B- to D0_CP K- Decays (open access)

Improved Measurement of CP Observables in B- to D0_CP K- Decays

We present a study of the decay B{sup -} {yields} D{sub (CP)}{sup 0}K{sup -} and its charge conjugate, where D{sub (CP)}{sup 0} is reconstructed in both a non-CP flavor eigenstate and in CP (CP-even and CP-odd) eigenstates, based on a sample of 382 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II e{sup +}e{sup -} storage ring. We measure the direct CP asymmetries A{sub CP{+-}} and the ratios of the branching fractions R{sub CP{+-}}: A{sub CP+} = 0.27 {+-} 0.09(stat) {+-} 0.04(syst), A{sub CP-} = -0.09 {+-} 0.09(stat) {+-} 0.02(syst), R{sub CP+} = 1.06 {+-} 0.10(stat) {+-} 0.05(syst), R{sub CP-} = 1.03 {+-} 0.10(stat) {+-} 0.05(syst). These results will help to better constrain the gamma phase parameter of the Cabibbo-Kobayashi-Maskawa quark mixing matrix.
Date: July 1, 2008
Creator: Aubert, Bernard; Bona, Marcella; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E. et al.
System: The UNT Digital Library
Si Memory Chip as a Sensitive Neutron Detector (open access)

Si Memory Chip as a Sensitive Neutron Detector

A novel neutron detector is based on semiconductor technology. A boron-containing film is an integral part of the semiconductor device and is in physical contact with the charge-storage medium (CSM). The CSM is a proprietary cell design known as MirrorBit{trademark}, which is different from conventional memory designs such as SRAM or DRAM. The design doubles the resolution and sensitivity in the array. This enables a highly effective detection of the secondary particles, {sup 7}Li and {sup 4}He, produced due to neutron capture by {sup 10}B in the device. Other approaches using semiconductor materials for neutron detection have employed single-diode detectors that require off-system preamplifiers to filter and condition the signal. There are several advantages to this non-volatile detector, one being that it requires no power for detection and retains the signal until reset. Further, this detector, a semiconductor chip, can be seamlessly integrated into other systems. Finally, the semiconductor manufacturing process on which the detector is based will allow for a high-volume and low-cost alternative to current detectors. MirrorBit{trademark} chips were exposed to neutron flux and the signals recorded. Detailed results from this experiment will be described in this presentation.
Date: March 1, 2008
Creator: Quam, William
System: The UNT Digital Library
The NuMI proton beam at Fermilab successes and challenges (open access)

The NuMI proton beam at Fermilab successes and challenges

The NuMI beam at Fermilab has delivered over 5 x 10{sup 20} 120 GeV protons to the neutrino production target since the start for MINOS [1] neutrino oscillation experiment operation in 2005. We report on proton beam commissioning and operation status, including successes and challenges with this beam.
Date: November 1, 2008
Creator: Childress, S.
System: The UNT Digital Library
Measurement of the Single Top Quark Production Cross Section at CDF (open access)

Measurement of the Single Top Quark Production Cross Section at CDF

We report a measurement of the single top quark production cross section in 2.2 fb{sup -1} of p{bar p} collision data collected by the Collider Detector at Fermilab at {radical}s = 1.96 TeV. Candidate events are classified as signal-like by three parallel analyses which use likelihood, matrix element, and neural network discriminants. These results are combined in order to improve the sensitivity. We observe a signal consistent with the standard model prediction, but inconsistent with the background only model by 3.7 standard deviations with a median expected sensitivity of 4.9 standard deviations. We measure a cross section of 2.2{sub -0.6}{sup +0.7}(stat+sys) pb, extract the CKM matrix element value |V{sub tb}| = 0.88{sub -0.12}{sup +0.13}(stat + sys) {+-} 0.07(theory), and set the limit |V{sub tb}| > 0.66 at the 95% C.L.
Date: September 1, 2008
Creator: Aaltonen, T.; Adelman, J.; Akimoto, T.; Albrow, Michael G.; Alvarez Gonzalez, B.; Amerio, S. et al.
System: The UNT Digital Library
Measurement of b-jet Shapes in Inclusive Jet Production in p anti-p Collisions at s**(1/2) = 1.96-TeV (open access)

Measurement of b-jet Shapes in Inclusive Jet Production in p anti-p Collisions at s**(1/2) = 1.96-TeV

We present a measurement of the shapes of b-jets using 300 pb{sup -1} of data obtained with the upgraded Collider Detector at Fermilab (CDF II) in p{bar p} collisions at center of mass energy {radical}s = 1.96 TeV. This measurement covers a wide transverse momentum range, from 52 to 300 GeV/c. Samples of heavy-flavor enhanced jets together with inclusive jets are used to extract the average shapes of b-jets. The b-jets are expected to be broader than inclusive jets. Moreover, b-jets containing a single b-quark are expected to be narrower than those containing a b{bar b} pair from gluon splitting. The measured b-jet shapes are found to be significantly broader than expected from the pythia and HERWIG Monte Carlo simulations. This effect may arise from an underestimation of the fraction of b-jets originating from gluon splitting in these simulations.
Date: June 1, 2008
Creator: Aaltonen, T.
System: The UNT Digital Library
Heating, Ventilating, and Air-Conditioning: Recent Advances in Diagnostics and Controls to Improve Air-Handling System Performance (open access)

Heating, Ventilating, and Air-Conditioning: Recent Advances in Diagnostics and Controls to Improve Air-Handling System Performance

The performance of air-handling systems in buildings needs to be improved. Many of the deficiencies result from myths and lore and a lack of understanding about the non-linear physical principles embedded in the associated technologies. By incorporating these principles, a few important efforts related to diagnostics and controls have already begun to solve some of the problems. This paper illustrates three novel solutions: one rapidly assesses duct leakage, the second configures ad hoc duct-static-pressure reset strategies, and the third identifies useful intermittent ventilation strategies. By highlighting these efforts, this paper seeks to stimulate new research and technology developments that could further improve air-handling systems.
Date: February 1, 2008
Creator: Wray, Craig; Wray, Craig P.; Sherman, Max H.; Walker, I. S.; Dickerhoff, D. J. & Federspiel, C. C.
System: The UNT Digital Library
Direct-Write Contacts: Metallization and Contact Formation; Preprint (open access)

Direct-Write Contacts: Metallization and Contact Formation; Preprint

Using direct-write approaches in photovoltaics for metallization and contact formation can significantly reduce the cost per watt of producing photovoltaic devices. Inks have been developed for various materials, such as Ag, Cu, Ni and Al, which can be used to inkjet print metallizations for various kinds of photovoltaic devices. Use of these inks results in metallization with resistivities close to those of bulk materials. By means of inkjet printing a metallization grid can be printed with better resolution, i.e. smaller lines, than screen-printing. Also inks have been developed to deposit transparent conductive oxide films by means of ultrasonic spraying.
Date: May 1, 2008
Creator: van Hest, M. F. A. M.; Curtis, C. J.; Miedaner, A.; Pasquarelli, R. M.; Kaydonova, T.; Hersh, P. et al.
System: The UNT Digital Library
Direct-Write Contacts: Metallization and Contact Formation (Poster) (open access)

Direct-Write Contacts: Metallization and Contact Formation (Poster)

None
Date: May 1, 2008
Creator: van Hest, M.; Curtis, C.; Miedaner, A.; Pasquarelli, R.; Kaydanova, T.; Hersh, P. et al.
System: The UNT Digital Library
Wireless Indoor Location Estimation Based on Neural Network RSS Signature Recognition (LENSR) (open access)

Wireless Indoor Location Estimation Based on Neural Network RSS Signature Recognition (LENSR)

Location Based Services (LBS), context aware applications, and people and object tracking depend on the ability to locate mobile devices, also known as localization, in the wireless landscape. Localization enables a diverse set of applications that include, but are not limited to, vehicle guidance in an industrial environment, security monitoring, self-guided tours, personalized communications services, resource tracking, mobile commerce services, guiding emergency workers during fire emergencies, habitat monitoring, environmental surveillance, and receiving alerts. This paper presents a new neural network approach (LENSR) based on a competitive topological Counter Propagation Network (CPN) with k-nearest neighborhood vector mapping, for indoor location estimation based on received signal strength. The advantage of this approach is both speed and accuracy. The tested accuracy of the algorithm was 90.6% within 1 meter and 96.4% within 1.5 meters. Several approaches for location estimation using WLAN technology were reviewed for comparison of results.
Date: June 1, 2008
Creator: Derr, Kurt & Manic, Milos
System: The UNT Digital Library
Estimating Loss-of-Coolant Accident Frequencies for the Standardized Plant Analysis Risk Models (open access)

Estimating Loss-of-Coolant Accident Frequencies for the Standardized Plant Analysis Risk Models

The U.S. Nuclear Regulatory Commission maintains a set of risk models covering the U.S. commercial nuclear power plants. These standardized plant analysis risk (SPAR) models include several loss-of-coolant accident (LOCA) initiating events such as small (SLOCA), medium (MLOCA), and large (LLOCA). All of these events involve a loss of coolant inventory from the reactor coolant system. In order to maintain a level of consistency across these models, initiating event frequencies generally are based on plant-type average performance, where the plant types are boiling water reactors and pressurized water reactors. For certain risk analyses, these plant-type initiating event frequencies may be replaced by plant-specific estimates. Frequencies for SPAR LOCA initiating events previously were based on results presented in NUREG/CR-5750, but the newest models use results documented in NUREG/CR-6928. The estimates in NUREG/CR-6928 are based on historical data from the initiating events database for pressurized water reactor SLOCA or an interpretation of results presented in the draft version of NUREG-1829. The information in NUREG-1829 can be used several ways, resulting in different estimates for the various LOCA frequencies. Various ways NUREG-1829 information can be used to estimate LOCA frequencies were investigated and this paper presents two methods for the SPAR model standard …
Date: September 1, 2008
Creator: Eide, S. A.; Rasmuson, D. M. & Atwood, C. L.
System: The UNT Digital Library
Investigation of Junction Properties in CdS/CdTe Solar Cells and Their Correlation to Device Properties: Preprint (open access)

Investigation of Junction Properties in CdS/CdTe Solar Cells and Their Correlation to Device Properties: Preprint

Secondary-ion mass spectrometry analysis of the CdS/CdTe interface shows that S diffusion in CdTe increases with substrate temperature and CdCl2 heat treatment. There is also an accumulation of Cl at the interface for CdCl2-treated samples. Modulated photo-reflectance studies shows that devices with CdCl2 heat treatment and open-circuit voltage (Voc) of 835 mV have a distinct high electric-field region in the layer with bandgap of 1.45 eV. Electron-beam induced current measurements reveal a one-sided junction for high Voc devices. The nature of the junction changes with processing. For heterojunction devices, the depletion region includes the highly defective CdS/CdTe interface, which would increase the recombination current and consequently the dark current, leading to lower Voc. In the case of CdCl2-treated cells, the n+-p junction and its high electric-field results in the junction between structurally compatible CdTe and the Te-rich CdSTe alloy, and thus, in higher Voc.
Date: May 1, 2008
Creator: Dhere, R. G.; Zhang, Y.; Romero, M. J.; Asher, S. E.; Young, M.; To, B. et al.
System: The UNT Digital Library
The Anti-B ---> D* l anti-nu form factor at zero recoil from three-flavor lattice QCD: A Model independent determination of |V(cb)| (open access)

The Anti-B ---> D* l anti-nu form factor at zero recoil from three-flavor lattice QCD: A Model independent determination of |V(cb)|

None
Date: August 1, 2008
Creator: Bernard, C.; DeTar, C.; Di Pierro, M.; El-Khadra, A. X.; Evans, R. T.; Freeland, E. D. et al.
System: The UNT Digital Library
Observation of transverse space charge effects in a multi-beamlet electron bunch produced in a photo-emission electron source (open access)

Observation of transverse space charge effects in a multi-beamlet electron bunch produced in a photo-emission electron source

A 'multiple beamlet' experiment aimed at investigating the transverse space charge effect was recently conducted at the Argonne Wakefield Accelerator. The experiment generated a symmetric pattern of 5 beamlets on the photocathode of the RF gun with the drive laser. We explored the evolution of the thereby produced 5 MeV, space-charge dominated electron beamlets in the 2m drift following the RF photocathode gun for various external focusing. Two important effects were observed and benchmarked using the particle-in-cell beam dynamics code IMPACT-T. In this paper, we present our experimental observation and their benchmarking with Impact-T.
Date: September 1, 2008
Creator: Rihaoui, M.; /Northern Illinois U. /NICADD, DeKalb; Gai, W.; /Argonne; Piot, P.; /Northern Illinois U. /NICADD, DeKalb /FERMILAB et al.
System: The UNT Digital Library
Recent Lifetime and Mixing Measurements at the Tevatron (open access)

Recent Lifetime and Mixing Measurements at the Tevatron

None
Date: June 1, 2008
Creator: Liu, Chunlei & U., /Pittsburgh
System: The UNT Digital Library
SYSTEM ANALYSIS OF NUCLEAR-ASSISTED SYNGAS PRODUCTION FROM COAL (open access)

SYSTEM ANALYSIS OF NUCLEAR-ASSISTED SYNGAS PRODUCTION FROM COAL

A system analysis has been performed to assess the efficiency and carbon utilization of a nuclear-assisted coal gasification process. The nuclear reactor is a high-temperature helium-cooled reactor that is used primarily to provide power for hydrogen production via high-temperature electrolysis. The supplemental hydrogen is mixed with the outlet stream from an oxygen-blown coal gasifier to produce a hydrogen-rich gas mixture, allowing most of the carbon dioxide to be converted into carbon monoxide, with enough excess hydrogen to produce a syngas product stream with a hydrogen/carbon monoxide molar ratio of about 2:1. Oxygen for the gasifier is also provided by the high-temperature electrolysis process. Results of the analysis predict 90.5% carbon utilization with a syngas production efficiency (defined as the ratio of the heating value of the produced syngas to the sum of the heating value of the coal plus the high-temperature reactor heat input) of 66.1% at a gasifier temperature of 1866 K for the high-moisture-content lignite coal considered. Usage of lower moisture coals such as bituminous can yield carbon utilization approaching 100% and 70% syngas production efficiency.
Date: September 1, 2008
Creator: Harvego, E. A.; McKellar, M. G. & O'Brien, J. E.
System: The UNT Digital Library
Approximate analytical solutions for continuously focused beamsand single-species plasmas in thermal equilibrium (open access)

Approximate analytical solutions for continuously focused beamsand single-species plasmas in thermal equilibrium

None
Date: December 1, 2008
Creator: Startsev, Edward A. & Lund, Steven M.
System: The UNT Digital Library