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Combined plate motion and density driven flow in the asthenosphere beneath Saudi Arabia: Evidence from shear-wave splitting and seismic anisotropy

Description: A comprehensive study of mantle anisotropy along the Red Sea and across Saudi Arabia was performed by analyzing shear-wave splitting recorded by stations from three different seismic networks: the largest, most widely distributed array of stations examined across Saudi Arabia to date. Stations near the Gulf of Aqaba display fast orientations that are aligned parallel to the Dead Sea Transform Fault, most likely related to the strike-slip motion between Africa and Arabia. However, most of our observations across Saudi Arabia are statistically the same, showing a consistent pattern of north-south oriented fast directions with delay times averaging about 1.4 s. Fossilized anisotropy related to the Proterozoic assembly of the Arabian Shield may contribute to the pattern but is not sufficient to fully explain the observations. We feel that the uniform anisotropic signature across Saudi Arabia is best explained by a combination of plate and density driven flow in the asthenosphere. By combining the northeast oriented flow associated with absolute plate motion with the northwest oriented flow associated with the channelized Afar plume along the Red Sea, we obtain a north-south oriented resultant that matches our splitting observations and supports models of active rifting processes. This explains why the north-south orientation of the fast polarization direction is so pervasive across the vast Arabian Plate.
Date: February 8, 2006
Creator: Hansen, S & Schwartz, S
Partner: UNT Libraries Government Documents Department

Studies of Nucleon Form Factors with 12 GeV CEBAF and SuperBigBite

Description: The elastic electromagnetic form factors are among the most fundamental quantities that describe the ground-state structure of the proton and neutron. Precision data of the form factors over a wide kinematical range provide a powerful test of current theories of hadron structure. A number of experiments aiming to measure the electric and magnetic elastic form factors of the neutron, G{sub E}{sup n} and G{sub M}{sup n}, and proton, G{sub E}{sup p}, at very high momentum transfer, up to the range of Q{sup 2} = 10-14 (GeV/c){sup 2}, are planned to be carried out with the future 11 GeV electron beam of the upgraded CEBAF at Jefferson Lab. These experiments will determine the nucleon form factors with unprecedented precision to Q{sup 2}-values up to three times higher than those of existing data. We review the approved proposals and the conceptual design of a new spectrometer, SuperBigBite, that will be used in these and other future experiments at Jefferson Lab.
Date: April 1, 2012
Creator: Hansen, Jens-Ole
Partner: UNT Libraries Government Documents Department

ADMINISTRATIVE AND ENGINEERING CONTROLS FOR THE OPERATION OF VENTILATION SYSTEMS FOR UNDERGROUND RADIOACTIVE WASTE STORAGE TANKS

Description: Liquid radioactive wastes from the Savannah River Site are stored in large underground carbon steel tanks. The majority of the waste is confined in double shell tanks, which have a primary shell, where the waste is stored, and a secondary shell, which creates an annular region between the two shells, that provides secondary containment and leak detection capabilities should leakage from the primary shell occur. Each of the DST is equipped with a purge ventilation system for the interior of the primary shell and annulus ventilation system for the secondary containment. Administrative flammability controls require continuous ventilation to remove hydrogen gas and other vapors from the waste tanks while preventing the release of radionuclides to the atmosphere. Should a leak from the primary to the annulus occur, the annulus ventilation would also serve this purpose. The functionality of the annulus ventilation is necessary to preserve the structural integrity of the primary shell and the secondary. An administrative corrosion control program is in place to ensure integrity of the tank. Given the critical functions of the purge and annulus ventilation systems, engineering controls are also necessary to ensure that the systems remain robust. The system consists of components that are constructed of metal (e.g., steel, stainless steel, aluminum, copper, etc.) and/or polymeric (polypropylene, polyethylene, silicone, polyurethane, etc.) materials. The performance of these materials in anticipated service environments (e.g., normal waste storage, waste removal, etc.) was evaluated. The most aggressive vapor space environment occurs during chemical cleaning of the residual heels by utilizing oxalic acid. The presence of NO{sub x} and mercury in the vapors generated from the process could potentially accelerate the degradation of aluminum, carbon steel, and copper. Once identified, the most susceptible materials were either replaced and/or plans for discontinuing operations are executed.
Date: November 13, 2013
Creator: Wiersma, B. & Hansen, A.
Partner: UNT Libraries Government Documents Department

rSUGRA: Putting Nonuniversal Gaugino Masses on the (W)MAP

Description: In this talk, we investigate the relic density and direct detection prospects of rSUGRA, a simple paradigm for supersymmetry breaking that allows for nonuniversal gaugino masses. We present updated plots reflecting the latest cosmological measurements from WMAP.
Date: June 17, 2003
Creator: Birkedal-Hansen, Andreas
Partner: UNT Libraries Government Documents Department

Shielding requirements for the transport of nuclear warhead components under decommissioning

Description: The requirements to carry out accurate shielding calculations involved with the safe off-site transportation of packages containing nuclear warhead components, special assemblies and radioactive materials are discussed. The need for (a) detailed information on the geometry and material composition of the packaging and radioactive load, (b) accurate representation of the differential energy spectra (dN/dE) for the neutron and gamma spectra emitted by the radioactive materials enclosed in the packaging, (c) well-tested neutron and photon cross section libraries, (d) and accurate three-dimensional Monte Carlo transport codes are illustrated. A brief discussion of the need for reliable dose measurements is presented.
Date: September 1, 1994
Creator: Hansen, L.F.
Partner: UNT Libraries Government Documents Department

From science to compliance: Geomechanics studies of the Waste Isolation Pilot Plant

Description: Mechanical and hydrological properties of salt provide excellent bases for geological isolation of hazardous materials. Regulatory certification of the Waste Isolation Pilot Plant (WIPP) testifies to the nearly ideal characteristics of bedded salt deposits in southeast New Mexico. The WIPP history includes decades of testing and scientific investigations, which have resulted in a comprehensive understanding of salt's mechanical deformational and hydrological properties over an applicable range of stresses and temperatures. Comprehensive evaluation of salt's favorable characteristics helped demonstrate regulatory compliance and ensure isolation of radioactive waste placed in a salt geological setting.
Date: June 5, 2000
Creator: HANSEN,FRANCIS D.
Partner: UNT Libraries Government Documents Department

{sup 3}He[pol]({rvec e}, e{prime})X and the neutron electromagnetic form factors

Description: Recent data for the spin-dependent A{sub T}, and A{sub TL}, asymmetries in {sup 3}He[pol]({rvec e}, e{prime}) quasielastic scattering are reviewed. The neutron electric and magnetic form factors are extracted from the data using a plane wave impulse approximation (PWIA) model, and the model uncertainties are estimated. The extracted G{sub M}{sup n} is in agreement with the dipole prediction as well as with other recent experiments. No meaningful result for G{sub E}{sup n} is obtained due to large uncertainties and possible final-state interaction effects. At higher Q{sup 2}, the determination of G{sub E}{sup n} in {sup 3}He[pol]({rvec e},e{prime}) does appear feasible based on the plane wave impulse approximation (PWIA) predictions.
Date: December 31, 1995
Creator: Hansen, J.O.
Partner: UNT Libraries Government Documents Department

Key Geomechanics Issues at the Waste Isolation Pilot Plant Geomechanics

Description: Mechanical and hydrological properties of rock salt provide excellent bases for geological isolation of hazardous materials. Regulatory compliance determinations for the Waste Isolation Pilot Plant (WIPP) stand as testament to the widely held conclusion that salt provides excellent isolation properties. The WIPP saga began in the 1950s when the U.S. National Academy of Sciences (NAS) recommended a salt vault as a promising solution to the national problem of nuclear waste disposal. For over 20 years, the Scientific basis for the NAS recommendation has been fortified by Sandia National Laboratories through a series of large scale field tests and laboratory investigations of salt properties. These scientific investigations helped develop a comprehensive understanding of salt's 4 reformational behavior over an applicable range of stresses and temperatures. Sophisticated constitutive modeling, validated through underground testing, provides the computational ability to model long-term behavior of repository configurations. In concert with advancement of the mechanical models, fluid flow measurements showed not only that the evaporite lithology was essentially impermeable but that the WIPP setting was hydrologically inactive. Favorable mechanical properties ensure isolation of materials placed in a salt geological setting. Key areas of the geomechanics investigations leading to the certification of WIPP are in situ experiments, laboratory tests, and shaft seal design.
Date: September 1, 1999
Creator: Hansen, Francis D.
Partner: UNT Libraries Government Documents Department

GOTHIC MODEL OF BWR SECONDARY CONTAINMENT DRAWDOWN ANALYSES

Description: This article introduces a GOTHIC version 7.1 model of the Secondary Containment Reactor Building Post LOCA drawdown analysis for a BWR. GOTHIC is an EPRI sponsored thermal hydraulic code. This analysis is required by the Utility to demonstrate an ability to restore and maintain the Secondary Containment Reactor Building negative pressure condition. The technical and regulatory issues associated with this modeling are presented. The analysis includes the affect of wind, elevation and thermal impacts on pressure conditions. The model includes a multiple volume representation which includes the spent fuel pool. In addition, heat sources and sinks are modeled as one dimensional heat conductors. The leakage into the building is modeled to include both laminar as well as turbulent behavior as established by actual plant test data. The GOTHIC code provides components to model heat exchangers used to provide fuel pool cooling as well as area cooling via air coolers. The results of the evaluation are used to demonstrate the time that the Reactor Building is at a pressure that exceeds external conditions. This time period is established with the GOTHIC model based on the worst case pressure conditions on the building. For this time period the Utility must assume the primary containment leakage goes directly to the environment. Once the building pressure is restored below outside conditions the release to the environment can be credited as a filtered release.
Date: October 6, 2004
Creator: Hansen, P.N.
Partner: UNT Libraries Government Documents Department

A comparison of the shielding performances of the AT-400A, Model FL and Model AL-R8 containers

Description: A comparison of the neutron and photon dose rates at different locations on the outside surface of the Model AL-RB, Model FL and the AT-400A containers for a given pit load has been done in order to understand the shielding characteristics of these containers. The Model AL-R8 is not certified for transport and is only used for storage of pits, while the Model FL is a certified Type B pit transportation container. The AT-400A is being developed as a type B pit storage and transportation container. The W48, W56 and B83 pits were chosen for this study because of their encompassing features with regard to other pits presently being stored. A detailed description of the geometry and materials of these containers and of the neutron and photon emission spectra from the actinide materials present in the pit have been used in the calculations of the total dose rates. The calculations have been done using the three-dimensional, neutron-photon Monte Carlo code MCNP. The results indicate the need for a containment vessel (CV), as is found in the Model FL and AT-400A containers, in order to assure compliance with 10 CFR 71 regulations. The absence of a CV in the AL-R8 container results in total dose rates well above of the 200mr/hr allowed by the regulations for the W56 pit. Similar behavior will be expected for other pits with configuration similar to the W56 in which the main contribution to the dose rate is from the fission photons.
Date: April 28, 1995
Creator: Hansen, L.F.
Partner: UNT Libraries Government Documents Department

Performance and Modeling of Amorphous Silicon Photovoltaics for Building-Integrated Applications (Preprint prepared for Solar 99)

Description: Amorphous silicon photovoltaic (PV) modules offer several advantages for building-integrated applications. The material can be deposited on glass or flexible substrates, which allows for products like roofing shingles and integrated PV/building glass. The material also has a uniform surface, which is ideal for many architectural applications. Amorphous silicon modules perform well in warm weather and have a small temperature coefficient for power. Depending on the building load, this may be beneficial when compared to crystalline systems. At the National Renewable Energy Laboratory, we are monitoring the performance of a triple-junction a-Si system. The system consists of 72 roofing shingles mounted directly to simulated roofing structures. This paper examines the performance of the building-integrated amorphous silicon PV system and applicability for covering residential loads. A simple model of system performance is also developed and is presented.
Date: June 7, 1998
Creator: Kroposki, B. & Hansen, R.
Partner: UNT Libraries Government Documents Department

SUSY dark matter and non-universal gaugino masses

Description: In this talk the authors investigate the dark matter prospects for supersymmetric models with non-universal gaugino masses. They motivate the use of non-universal gaugino masses from several directions, including problems, with the current favorite scenario, the cMSSM. They then display new corridors of parameter space that allow an acceptable dark matter relic density once gaugino mass universality is relaxed. They finish with a specific string-derived model that allows this universality relaxation and then use the dark matter constraint to make specific statements about the hidden sector of the model.
Date: April 15, 2002
Creator: Birkedal-Hansen, Andreas
Partner: UNT Libraries Government Documents Department

Streamlining the process: A strategy for making NEPA work better and cost less

Description: When the National Environmental Policy Act (NEPA) was enacted in 1969, neither Congress nor the Federal Agencies affected anticipated that implementation of the NEPA process would result in the intolerable delays, inefficiencies, duplication of effort, commitments of excessive financial and personnel resources, and bureaucratic gridlock that have become institutionalized. The 1975 Council on Environmental Quality (CEQ) regulations, which were intended to make the NEPA process more efficient and more useful to decision makers and the public, have either been largely ignored or unintentionally subverted. Agency policy mandates, like those of former Secretary of Energy Hazel R. O`Leary, to ``make NEPA work better and cost less`` have, so far, been disappointingly ineffectual. Federal Agencies have reached the point where almost every constituent of the NEPA process must be subjected to crisis management. This paper focuses on a ten-point strategy for streamlining the NEPA process in order to achieve the Act`s objectives while easing the considerable burden on agencies, the public, and the judicial system. How the ten points are timed and implemented is critical to any successful streamlining.
Date: May 1, 1998
Creator: Hansen, R.P.; Hansen, J.D. & Wolff, T.A.
Partner: UNT Libraries Government Documents Department

Object-Oriented Analysis Code for Hall A Vertical Drift Chambers

Description: The high-resolution spectrometers in Jefferson Lab's Hall A use vertical drift chambers to determine charged particle tracks. The current analysis code for the vertical drift chambers is difficult to maintain and modify, which has prompted the development of an object-oriented version, which will be easier to maintain and more able to adapt to changes in the detector configuration. However, the object-oriented approach involves using a slightly different algorithm than ESPACE, which could lead to different results. In this project, a preliminary version of an object-oriented analysis program for the vertical drift chambers is created and its results are compared to the existing software to determine the impacts of the differences in the reconstruction algorithms. In addition, the algorithms themselves are compared, and minor differences in track reconstruction techniques are reported.
Date: January 1, 2002
Creator: Robbins, J. & Hansen, J.O.
Partner: UNT Libraries Government Documents Department

Comparison of Two Wire Chamber Track Reconstruction Algorithms Used in Hall A at Jefferson Lab

Description: The Hall A collaboration at Jefferson Lab is currently in the process of redesigning and rewriting its physics analysis software in C++, using the ROOT libraries developed at CERN, to replace the Fortran-based ESPACE analyzer. In this paper, we carry out a detailed comparison of the wire chamber tracking results of both software packages. To this end, reconstruction of target quantities from detected tracks through the Vertical Drift Chambers (VDCs) in both spectrometer arms has been recently added to the C++ analyzer, to bring it to the same level as ESPACE. A study of the differences in the outputs of both analysis programs shows that while the output of the C++ analyzer is suitable for calibrations and studies that do not require high resolution, there are still many subtle differences that need to be resolved before it is ready for a productionquality release. The problems are most likely due to different cluster matching and track fitting algorithms used by both programs for tracks through the VDCs, as well as certain corrections missing from the C++ code. These problems and some possible solutions are discussed.
Date: January 1, 2003
Creator: Dobbs, S. & Hansen, J.O.
Partner: UNT Libraries Government Documents Department

Advances in NLTE Modeling for Integrated Simulations

Description: The last few years have seen significant progress in constructing the atomic models required for non-local thermodynamic equilibrium (NLTE) simulations. Along with this has come an increased understanding of the requirements for accurately modeling the ionization balance, energy content and radiative properties of different elements for a wide range of densities and temperatures. Much of this progress is the result of a series of workshops dedicated to comparing the results from different codes and computational approaches applied to a series of test problems. The results of these workshops emphasized the importance of atomic model completeness, especially in doubly excited states and autoionization transitions, to calculating ionization balance, and the importance of accurate, detailed atomic data to producing reliable spectra. We describe a simple screened-hydrogenic model that calculates NLTE ionization balance with surprising accuracy, at a low enough computational cost for routine use in radiation-hydrodynamics codes. The model incorporates term splitting, {Delta}n = 0 transitions, and approximate UTA widths for spectral calculations, with results comparable to those of much more detailed codes. Simulations done with this model have been increasingly successful at matching experimental data for laser-driven systems and hohlraums. Accurate and efficient atomic models are just one requirement for integrated NLTE simulations. Coupling the atomic kinetics to hydrodynamics and radiation transport constrains both discretizations and algorithms to retain energy conservation, accuracy and stability. In particular, the strong coupling between radiation and populations can require either very short timesteps or significantly modified radiation transport algorithms to account for NLTE material response. Considerations such as these continue to provide challenges for NLTE simulations.
Date: July 8, 2009
Creator: Scott, H A & Hansen, S B
Partner: UNT Libraries Government Documents Department

Mechanical excavator performance in Yucca Mountain tuffs

Description: A research effort of four phases is in progress at the Colorado School of Mines. The overall program will evaluate the cutability of welded tuff and other lithologies likely to be excavated at Yucca Mountain in the site characterization process. Several mechanical systems are considered with emphasis given to the tunnel boring machine. The research comprises laboratory testing, linear drag bit and disc cutter tests and potentially large-scale laboratory demonstrations to support potential use of a tunnel boring machine in welded tuff. Preliminary estimates of mechanical excavator performance in Yucca Mountain tuff are presented here. As phases of the research project are completed, well quantified estimates will be made of performance of mechanical excavators in the Yucca Mountain tuffs. 3 refs., 2 tabs.
Date: January 1, 1991
Creator: Ozdemir, L. & Hansen, F.D.
Partner: UNT Libraries Government Documents Department

Black carbon emissions in the United Kingdom during the past four decades: An empirical analysis

Description: We use data from a unique 40-year record of 150 urban and rural stations in the ''Black Smoke and SO2 Network'' in Great Britain to infer information about sources of atmospheric black carbon (BC). The data show a rapid decline of ambient atmospheric BC between 1962 and the early 1990s that exceeds the decline in official estimates of BC emissions based only on amount of fuel use and mostly fixed emission factors. This provides empirical confirmation of the existence and large impact of a time-dependent ''technology factor'' that must multiply the rate of fossil fuel use. Current ambient BC amounts in Great Britain comparable to those in western and central Europe, with diesel engines being the principal present source. From comparison of BC and SO2 data we infer that current BC emission inventories understate true emissions in the U.K. by about a factor of two. The results imply that there is the potential for improved technology to achieve large reduction of global ambient BC. There is a need for comparable monitoring of BC in other countries.
Date: April 22, 2004
Creator: Novakov, T. & Hansen, J.E.
Partner: UNT Libraries Government Documents Department

Advanced Controls and Communications for Demand Response andEnergy Efficiency in Commercial Buildings

Description: Commercial buildings account for a large portion of summer peak demand. Research results show that there is significant potential to reduce peak demand in commercial buildings through advanced control technologies and strategies. However, a better understanding of commercial building's contribution to peak demand and the use of energy management and control systems is required to develop this demand response resource to its full potential. This paper discusses recent research results and new opportunities for advanced building control systems to provide demand response (DR) to improve electricity markets and reduce electric grid problems. The main focus of this paper is the role of new and existing control systems for HVAC and lighting in commercial buildings. A demand-side management framework from building operations perspective with three main features: daily energy efficiency, daily peak load management and event driven, dynamic demand response is presented. A general description of DR, its benefits, and nationwide potential in commercial buildings is outlined. Case studies involving energy management and control systems and DR savings opportunities are presented. The paper also describes results from three years of research in California to automate DR in buildings. Case study results and research on advanced buildings systems in New York are also presented.
Date: January 17, 2006
Creator: Kiliccote, Sila; Piette, Mary Ann & Hansen, David
Partner: UNT Libraries Government Documents Department

An Automatic Lithium Drifting Apparatus for Silicon and Germanium Detectors

Description: Drifting a thick lithium-drifted counter (silicon and germanium) is a time-consuming operation that frequently results in a poor device, owing to inadequate knowledge of progress of the drifting operation. The drifting apparatus described here automatically controls the temperature of the detector that is being drifted to maintain the leakage current at a preselected value. While drifting proceeds, a continuous measurement is made of the distance of the lithium-drifted region from the opposite face of the wafer. When the drifted region reaches 30 mil or less from the back of the wafer a meter indicates the thickness of the undrifted region and, when this thickness falls below a preselected value, the temperature of the detector is automatically reduced to room temperature. The need for constant supervision of the drifting operation is thereby eliminated, and reliance on theoretical drift-rate calculations to predict the drift-through time is avoided. The technique has been applied to the manufacture of lithium-drifted silicon detectors with excellent results. The application of the technique to lithium-drifted germanium {gamma} detectors is also discussed briefly.
Date: February 8, 1964
Creator: Goulding, Fred S. & Hansen, W. L.
Partner: UNT Libraries Government Documents Department

Introducing an Absolute Cavity Pyrgeometer for Improving the Atmospheric Longwave Irradiance Measurement (Presentation)

Description: Advancing climate change research requires accurate and traceable measurement of the atmospheric longwave irradiance. Current measurement capabilities are limited to an estimated uncertainty of larger than +/- 4 W/m2 using the interim World Infrared Standard Group (WISG). WISG is traceable to the Systeme international d'unites (SI) through blackbody calibrations. An Absolute Cavity Pyrgeometer (ACP) is being developed to measure absolute outdoor longwave irradiance with traceability to SI using the temperature scale (ITS-90) and the sky as the reference source, instead of a blackbody. The ACP was designed by NREL and optically characterized by the National Institute of Standards and Technology (NIST). Under clear-sky and stable conditions, the responsivity of the ACP is determined by lowering the temperature of the cavity and calculating the rate of change of the thermopile output voltage versus the changing net irradiance. The absolute atmospheric longwave irradiance is then calculated with an uncertainty of +/- 3.96 W/m2 with traceability to SI. The measured irradiance by the ACP was compared with the irradiance measured by two pyrgeometers calibrated by the World Radiation Center with traceability to the WISG. A total of 408 readings was collected over three different clear nights. The calculated irradiance measured by the ACP was 1.5 W/m2 lower than that measured by the two pyrgeometers that are traceable to WISG. Further development and characterization of the ACP might contribute to the effort of improving the uncertainty and traceability of WISG to SI.
Date: August 1, 2012
Creator: Reda, I.; Hansen, L. & Zeng, J.
Partner: UNT Libraries Government Documents Department

ADC and TDC implemented using FPGA

Description: Several tests of FPGA devices programmed as analog waveform digitizers are discussed. The ADC uses the ramping-comparing scheme. A multi-channel ADC can be implemented with only a few resistors and capacitors as external components. A periodic logic levels are shaped by passive RC network to generate exponential ramps. The FPGA differential input buffers are used as comparators to compare the ramps with the input signals. The times at which these ramps cross the input signals are digitized by time-to-digital-converters (TDCs) implemented within the FPGA. The TDC portion of the logic alone has potentially a broad range of HEP/nuclear science applications. A 96-channel TDC card using FPGAs as TDCs being designed for the Fermilab MIPP electronics upgrade project is discussed. A deserializer circuit based on multisampling circuit used in the TDC, the 'Digital Phase Follower' (DPF) is also documented.
Date: November 1, 2007
Creator: Wu, Jinyuan; Hansen, Sten; Shi, Zonghan & /Fermilab
Partner: UNT Libraries Government Documents Department

MOOSE: A PARALLEL COMPUTATIONAL FRAMEWORK FOR COUPLED SYSTEMS OF NONLINEAR EQUATIONS.

Description: Systems of coupled, nonlinear partial di?erential equations often arise in sim- ulation of nuclear processes. MOOSE: Multiphysics Ob ject Oriented Simulation Environment, a parallel computational framework targeted at solving these systems is presented. As opposed to traditional data / ?ow oriented com- putational frameworks, MOOSE is instead founded on mathematics based on Jacobian-free Newton Krylov (JFNK). Utilizing the mathematical structure present in JFNK, physics are modularized into “Kernels” allowing for rapid production of new simulation tools. In addition, systems are solved fully cou- pled and fully implicit employing physics based preconditioning allowing for a large amount of ?exibility even with large variance in time scales. Background on the mathematics, an inspection of the structure of MOOSE and several rep- resentative solutions from applications built on the framework are presented.
Date: May 1, 2009
Creator: Hansen, G.; Newman, C. & Gaston, D.
Partner: UNT Libraries Government Documents Department