Drilling, Sampling, and Well-Installation Plan for the IFC Well Field, 300 Area (open access)

Drilling, Sampling, and Well-Installation Plan for the IFC Well Field, 300 Area

The 300 Area was selected as a location for an IFC because it offers excellent opportunities for field research on the influence of mass-transfer processes on uranium in the vadose zone and groundwater. The 300 Area was the location of nuclear fuel fabrication facilities and has more than 100 waste sites. Two of these waste sites, the North and South Process Ponds received large volumes of process waste from 1943 to 1975 and are thought to represent a significant source of the groundwater uranium plume in the 300 Area. Geophysical surveys and other characterization efforts have led to selection of the South Process Pond for the IFC.
Date: May 5, 2008
Creator: Bjornstad, Bruce N. & Horner, Jacob A.
System: The UNT Digital Library
Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs (open access)

Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently hampered by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are …
Date: May 5, 2006
Creator: Paulsson, Bjorn N.P
System: The UNT Digital Library
Supernova Science Center (open access)

Supernova Science Center

The Supernova Science Center (SNSC) was founded in 2001 to carry out theoretical and computational research leading to a better understanding of supernovae and related transients. The SNSC, a four-institutional collaboration, included scientists from LANL, LLNL, the University of Arizona (UA), and the University of California at Santa Cruz (UCSC). Intitially, the SNSC was funded for three years of operation, but in 2004 an opportunity was provided to submit a renewal proposal for two years. That proposal was funded and subsequently, at UCSC, a one year no-cost extension was granted. The total operational time of the SNSC was thus July 15, 2001 - July 15, 2007. This document summarizes the research and findings of the SNSC and provides a cummulative publication list.
Date: May 5, 2008
Creator: Woosley, S. E.
System: The UNT Digital Library
Crack growth rates and metallographic examinations of Alloy 600 and Alloy 82/182 from field components and laboratory materials tested in PWR environments. (open access)

Crack growth rates and metallographic examinations of Alloy 600 and Alloy 82/182 from field components and laboratory materials tested in PWR environments.

In light water reactors, components made of nickel-base alloys are susceptible to environmentally assisted cracking. This report summarizes the crack growth rate results and related metallography for field and laboratory-procured Alloy 600 and its weld alloys tested in pressurized water reactor (PWR) environments. The report also presents crack growth rate (CGR) results for a shielded-metal-arc weld of Alloy 182 in a simulated PWR environment as a function of temperature between 290 C and 350 C. These data were used to determine the activation energy for crack growth in Alloy 182 welds. The tests were performed by measuring the changes in the stress corrosion CGR as the temperatures were varied during the test. The difference in electrochemical potential between the specimen and the Ni/NiO line was maintained constant at each temperature by adjusting the hydrogen overpressure on the water supply tank. The CGR data as a function of temperature yielded activation energies of 252 kJ/mol for a double-J weld and 189 kJ/mol for a deep-groove weld. These values are in good agreement with the data reported in the literature. The data reported here and those in the literature suggest that the average activation energy for Alloy 182 welds is on the …
Date: May 5, 2008
Creator: Alexandreanu, B.; Chopra, O. K. & Shack, W. J.
System: The UNT Digital Library
Emerging Energy-Efficient Technologies for Industry (open access)

Emerging Energy-Efficient Technologies for Industry

U.S. industry consumes approximately 37 percent of thenation's energy to produce 24 percent of the nation's GDP. Increasingly,society is confronted with the challenge of moving toward a cleaner, moresustainable path of production and consumption, while increasing globalcompetitiveness. Technology is essential in achieving these challenges.We report on a recent analysis of emerging energy-efficient technologiesfor industry, focusing on over 50 selected technologies. The technologiesare characterized with respect to energy efficiency, economics andenvironmental performance. This paper provides an overview of theresults, demonstrating that we are not running out of technologies toimprove energy efficiency, economic and environmental performance, andneither will we in the future. The study shows that many of thetechnologies have important non-energy benefits, ranging from reducedenvironmental impact to improved productivity, and reduced capital costscompared to current technologies.
Date: May 5, 2005
Creator: Worrell, Ernst; Martin, Nathan; Price, Lynn; Ruth, Michael; Elliot, Neal; Shipley, Anna et al.
System: The UNT Digital Library
Final Technical Report for “A Heliportable Sonic Drilling Platform for Microhole Drilling and Exploration” (open access)

Final Technical Report for “A Heliportable Sonic Drilling Platform for Microhole Drilling and Exploration”

The Phase I objectives were fully achieved the execution of a program that included the: • Development of a comprehensive model of the sonic drill technology and interaction of the dynamic drilling parameters with the impedance of the earth. • Operation and measurement of the sonic drilling process in the field at full scale. • Comparison of the analytical and experimental results to form an objective and quantified approach to describe the fundamental phenomena and to develop a methodology for automated control of the sonic drilling process. • Conceptual design of a modular sonic drilling system that can be transported to remote sites by helicopter. As a result, the feasibility of a commercially viable sonic drilling technology that can produce microholes up to 1,500 feet in depth, and that is field deployable to remote, environmentally sensitive sites via a helicopter, has been demonstrated.
Date: May 5, 2008
Creator: Lucon, Peter
System: The UNT Digital Library
Biomass Biorefinery for the production of Polymers and Fuels (open access)

Biomass Biorefinery for the production of Polymers and Fuels

The conversion of biomass crops to fuel is receiving considerable attention as a means to reduce our dependence on foreign oil imports and to meet future energy needs. Besides their use for fuel, biomass crops are an attractive vehicle for producing value added products such as biopolymers. Metabolix, Inc. of Cambridge proposes to develop methods for producing biodegradable polymers polyhydroxyalkanoates (PHAs) in green tissue plants as well as utilizating residual plant biomass after polymer extraction for fuel generation to offset the energy required for polymer extraction. The primary plant target is switchgrass, and backup targets are alfalfa and tobacco. The combined polymer and fuel production from the transgenic biomass crops establishes a biorefinery that has the potential to reduce the nation’s dependence on foreign oil imports for both the feedstocks and energy needed for plastic production. Concerns about the widespread use of transgenic crops and the grower’s ability to prevent the contamination of the surrounding environment with foreign genes will be addressed by incorporating and expanding on some of the latest plant biotechnology developed by the project partners of this proposal. This proposal also addresses extraction of PHAs from biomass, modification of PHAs so that they have suitable properties for …
Date: May 5, 2008
Creator: Peoples, Dr. Oliver P.
System: The UNT Digital Library
D0 General Support: The Use of Programmable Logic Controllers (PLCS) at D0 (open access)

D0 General Support: The Use of Programmable Logic Controllers (PLCS) at D0

With the exception of control of heating, ventilation, and air conditioning (HVAC) ventilation fans, and their shutdown in the case of smoke in the ducts, all implementations of Programmable Logic Controllers (PLCs) in Dzero have been made within the fundamental premise that no uncertified PLC apparatus shall be entrusted with the safety of equipment or personnel. Thus although PLCs are used to control and monitor all manner of intricate equipment, simple hardware interlocks and relief devices provide basic protection against component failure, control failure, or inappropriate control operation. Nevertheless, this report includes two observations as follows: (1) It may be prudent to reconfigure the link between the Pyrotronics system and the HVAC system such that the Pyrotronics system provides interlocks to the ventilation fans instead of control inputs to the uncertified HVAC PLCs. Although the Pyrotronics system is certified and maintained to life safety standards, the HVAC system is not. A hardware or software failure of the HVAC system probably should not be allowed to result in the situation where the ventilation fans in a smoke filled duct continue to operate. Dan Markley is investigating this matter. (2) It may also be prudent to examine the network security of those …
Date: May 5, 2000
Creator: Hance, R.
System: The UNT Digital Library
IMPACT OF TIME / TEMPERATURE CURING CONDITIONS AND ALUMINATE CONCENTRATIONS ON SALTSTONE PROPERTIES (open access)

IMPACT OF TIME / TEMPERATURE CURING CONDITIONS AND ALUMINATE CONCENTRATIONS ON SALTSTONE PROPERTIES

This report addresses the impact of (1) the time and temperature curing conditions (profile) and (2) the impact of higher aluminate concentrations in the decontaminated salt solution on Saltstone processing and performance properties. The results demonstrate that performance properties as well as some of the processing properties of Saltstone are highly sensitive to the conditions of time and temperature under which curing occurs. This sensitivity is in turn dependent on the concentration of aluminate in the salt feed solution. In general, the performance properties and indicators (Young's modulus, compressive strength and total porosity) are reduced when curing is initially carried out under high temperature. However, this reduction in performance properties is dependent on the sequence of temperatures (the time/temperature profile) experienced during the curing process. That is, samples that are subjected to a 1, 2, 3 or 4 day curing time at 60 C followed by final curing at 22 C lead to performance properties that are significantly different than the properties of grouts allowed to cure for 1, 2, 3 or 4 days at 22 C followed by a treatment at 60 C. The performance properties of Saltstone cured in the sequence of higher temperature first are generally less …
Date: May 5, 2009
Creator: Harbour, J.; Edwards, T. & Williams, V.
System: The UNT Digital Library
Beta-cell Assembly for the Quad Gas Sampling Detector (open access)

Beta-cell Assembly for the Quad Gas Sampling Detector

The beta-cells used in the beta-gamma detector have taken time to develop and to standardize the assembly of them. In making the assembly routine it is important to have step by step assembly instructions as well as a list of potential problems and their solutions. This document attempts to accomplish these goals.
Date: May 5, 2008
Creator: Cooper, Matthew W.; Bowyer, Ted W.; McIntyre, Justin I.; Hayes, James C.; Heimbigner, Tom R.; Ripplinger, Michael D. et al.
System: The UNT Digital Library
2007 Savannah River Site Annual Illness and Injury Surveillance Report (open access)

2007 Savannah River Site Annual Illness and Injury Surveillance Report

The U.S. Department of Energy’s (DOE) commitment to assuring the health and safety of its workers includes the conduct of epidemiologic surveillance activities that provide an early warning system for health problems among workers. The Illness and Injury Surveillance Program monitors illnesses and health conditions that result in an absence of workdays, occupational injuries and illnesses, and disabilities and deaths among current workers.
Date: May 5, 2009
Creator: United States. Department of Energy. Office of Health, Safety, and Security.
System: The UNT Digital Library
DAiSES: Dynamic Adaptivity in Support of Extreme Scale Department of Energy Project No. ER25622 Prime Contract No. DE-FG02-04ER25622 Final Report for September 15, 2004-September 14, 2008 (open access)

DAiSES: Dynamic Adaptivity in Support of Extreme Scale Department of Energy Project No. ER25622 Prime Contract No. DE-FG02-04ER25622 Final Report for September 15, 2004-September 14, 2008

The DAiSES project [Te04] was focused on enabling conventional operating systems, in particular, those running on extreme scale systems, to dynamically customize system resource management in order to offer applications the best possible environment in which to execute. Such dynamic adaptation allows operating systems to modify the execution environment in response to changes in workload behavior and system state. The main challenges of this project included determination of what operating system (OS) algorithms, policies, and parameters should be adapted, when to adapt them, and how to adapt them. We addressed these challenges by using a combination of static analysis and runtime monitoring and adaptation to identify a priori profitable targets of adaptation and effective heuristics that can be used to dynamically trigger adaptation. Dynamic monitoring and adaptation of the OS was provided by either kernel modifications or the use of KernInst and Kperfmon [Wm04]. Since Linux, an open source OS, was our target OS, patches submitted by kernel developers and researchers often facilitated kernel modifications. KernInst operates on unmodified commodity operating systems, i.e., Solaris and Linux; it is fine-grained, thus, there were few constraints on how the underlying OS can be modified. Dynamically adaptive functionality of operating systems, both in …
Date: May 5, 2009
Creator: Teller, Patricia J.
System: The UNT Digital Library
DEVELOPMENT OF REMOTE HANFORD CONNECTOR GASKET REPLACEMENT TOOLING FOR DWPF (open access)

DEVELOPMENT OF REMOTE HANFORD CONNECTOR GASKET REPLACEMENT TOOLING FOR DWPF

The Defense Waste Processing Facility (DWPF) requested the Savannah River National Laboratory (SRNL) to develop tooling and equipment to remotely replace gaskets in mechanical Hanford connectors to reduce personnel radiation exposure as compared to the current hands-on method. It is also expected that radiation levels will continually increase with future waste streams. The equipment is operated in the Remote Equipment Decontamination Cell (REDC), which is equipped with compressed air, two master-slave manipulators (MSM's) and an electro-mechanical manipulator (EMM) arm for operation of the remote tools. The REDC does not provide access to electrical power, so the equipment must be manually or pneumatically operated. The MSM's have a load limit at full extension of ten pounds, which limited the weight of the installation tool. In order to remotely replace Hanford connector gaskets several operations must be performed remotely, these include: removal of the spent gasket and retaining ring (retaining ring is also called snap ring), loading the new snap ring and gasket into the installation tool and installation of the new gasket into the Hanford connector. SRNL developed and tested tools that successfully perform all of the necessary tasks. Removal of snap rings from horizontal and vertical connectors is performed by …
Date: May 5, 2009
Creator: Krementz, D. & Coughlin, Jeffrey
System: The UNT Digital Library
Attractor Explosions and Catalyzed Vacuum Decay (open access)

Attractor Explosions and Catalyzed Vacuum Decay

We present a mechanism for catalyzed vacuum bubble production obtained by combining moduli stabilization with a generalized attractor phenomenon in which moduli are sourced by compact objects. This leads straightforwardly to a class of examples in which the Hawking decay process for black holes unveils a bubble of a different vacuum from the ambient one, generalizing the new endpoint for Hawking evaporation discovered recently by Horowitz. Catalyzed vacuum bubble production can occur for both charged and uncharged bodies, including Schwarzschild black holes for which massive particles produced in the Hawking process can trigger vacuum decay. We briefly discuss applications of this process to the population and stability of metastable vacua.
Date: May 5, 2006
Creator: Green, Daniel; Silverstein, Eva & Starr, David
System: The UNT Digital Library
Dalitz Plot Analysis of the Decay B+ -> K+K+K- (open access)

Dalitz Plot Analysis of the Decay B+ -> K+K+K-

The authors perform an analysis of the three-body charmless decay B{sup {+-}} {yields} K{sup {+-}}K{sup {+-}}K{sup {-+}} using a sample of 226.0 {+-} 2.5 million B{bar B} pairs collected by the BABAR detector and measure the total branching fraction and Cp asymmetry to be {beta} = (35.2 {+-} 0.9 {+-} 1.6) x 10{sup -6} and A{sub CP} = (-1.7 {+-} 2.6 {+-} 1.5)%. They fit the Dalitz plot distribution using an isobar model and report the measured values of magnitudes and phases of the production coefficients. The decay dynamics is dominated by the K{sup +}K{sup -} S-wave, for which we perform a partial-wave analysis in the region m(K{sup +}K{sup -}) < 2 GeV/c{sup 2}. They find no evidence of CP violation for individual components of the isobar model.
Date: May 5, 2006
Creator: Dvoretskii, Alexei
System: The UNT Digital Library
Search for B Meson Decays to eta' eta' K (open access)

Search for B Meson Decays to eta' eta' K

The authors describe searches for decays of B mesons to the charmless final states {eta}'{eta}'K. The data consist of 228 million B{bar B} pairs produced in e{sup +}e{sup -} annihilation, collected with the BABAR detector at the Stanford Linear Accelerator Center. The 90% confidence level upper limits for the branching fractions are {Beta}(B{sup 0} {yields} {eta}'{eta}'K{sup 0}) < 31 x 10{sup -6} and {Beta}(B{sup +} {yields} {eta}'{eta}'K{sup +}) < 25 x 10{sup -6}.
Date: May 5, 2006
Creator: Aubert, B.
System: The UNT Digital Library
Research on CdZnTe and Other Novel Room Temperature Gamma Ray Spectrometer Materials (open access)

Research on CdZnTe and Other Novel Room Temperature Gamma Ray Spectrometer Materials

Room temperature gamma-ray spectrometers are being developed for a number of years for national security applications where high sensitivity, low operating power and compactness are indispensable. The technology has matured now to the point where large volume (several cubic centimeters) and high energy resolution (approximately 1% at 660 eV) of gamma photons, are becoming available for their incorporation into portable systems for remote sensing of signatures from nuclear materials.
Date: May 5, 2007
Creator: Burger, Arnold; Groza, Michael; Cui, Yunlong; Roy, Utpal N. & Guo, M.
System: The UNT Digital Library
Observational Signatures and Non-Gaussianities ofGeneral Single Field Inflation (open access)

Observational Signatures and Non-Gaussianities ofGeneral Single Field Inflation

We perform a general study of primordial scalar non-Gaussianities in single field inflationary models. We consider models where the inflaton Lagrangian is an arbitrary function of the scalar field and its first derivative, and the sound speed is arbitrary. We find that under reasonable assumptions, the non-Gaussianity is completely determined by 5 parameters. In special limits of the parameter space, one finds distinctive ''shapes'' of the non-Gaussianity. In models with a small sound speed, several of these shapes would become potentially observable in the near future. Different limits of our formulae recover various previously known results.
Date: May 5, 2006
Creator: Chen, Xingang; Huang, Min-xin; Kachru, Shamit & Shiu, Gary
System: The UNT Digital Library
Studies of dynamic properties of shock compressed single crystals by in situ dynamic x-ray diffraction and sample recovery (open access)

Studies of dynamic properties of shock compressed single crystals by in situ dynamic x-ray diffraction and sample recovery

Laser compression provides pressures ranging from a few to hundreds of GPa at pulse durations of the order of nanoseconds or fractions thereof. The short duration ensures a rapid decay of the pulse and quenching of shocked sample in times that are orders of magnitude lower than in conventional explosively driven plate impact experiments. Systematic experiments carried out in specimens well suited for transmission electron microscopy characterization are revealing that laser compression, by virtue of a much more rapid cooling, enables the retention of a deformation structure closer to the one existing during shock. The smaller pulse length decreases the propensity for localization. Copper and copper aluminum (2 and 6 wt% Al) with orientations [001] and [ ] were subjected to high intensity laser pulses with energy levels of 70 to 300 J delivered in a pulse duration of approximately 3 ns. Systematic differences of the defect substructure were observed as a function of pressure and stacking fault energy. The changes in the mechanical properties for each condition were compared using micro- and nano-hardness measurements and correlated well with observations of the defect substructure. Three regimes of plastic deformation were identified and their transitions modeled: dislocation cells, stacking faults, and …
Date: May 5, 2007
Creator: Meyers1, M. A.; Schneider, M. S.; Jarmakani, H.; Kad, B.; Remington2, B. A.; Kalantar, D. H. et al.
System: The UNT Digital Library
Scaling up of Carbon Exchange Dynamics from AmeriFlux Sites to a Super-Region in the Eastern United States (open access)

Scaling up of Carbon Exchange Dynamics from AmeriFlux Sites to a Super-Region in the Eastern United States

The primary objective of this project was to evaluate carbon exchange dynamics across a region of North America between the Great Plains and the East Coast. This region contains about 40 active carbon cycle research (AmeriFlux) sites in a variety of climatic and landuse settings, from upland forest to urban development. The core research involved a scaling strategy that uses measured fluxes of CO{sub 2}, energy, water, and other biophysical and biometric parameters to train and calibrate surface-vegetation-atmosphere models, in conjunction with satellite (MODIS) derived drivers. To achieve matching of measured and modeled fluxes, the ecosystem parameters of the models will be adjusted to the dynamically variable flux-tower footprints following Schmid (1997). High-resolution vegetation index variations around the flux sites have been derived from Landsat data for this purpose. The calibrated models are being used in conjunction with MODIS data, atmospheric re-analysis data, and digital land-cover databases to derive ecosystem exchange fluxes over the study domain.
Date: May 5, 2009
Creator: Schmid, Hans Peter & Wayson, Craig
System: The UNT Digital Library
The Power of a Good Idea: Quantitative Modeling of the Spread of Ideas from Epidemiological Models (open access)

The Power of a Good Idea: Quantitative Modeling of the Spread of Ideas from Epidemiological Models

The population dynamics underlying the diffusion of ideas hold many qualitative similarities to those involved in the spread of infections. In spite of much suggestive evidence this analogy is hardly ever quantified in useful ways. The standard benefit of modeling epidemics is the ability to estimate quantitatively population average parameters, such as interpersonal contact rates, incubation times, duration of infectious periods, etc. In most cases such quantities generalize naturally to the spread of ideas and provide a simple means of quantifying sociological and behavioral patterns. Here we apply several paradigmatic models of epidemics to empirical data on the advent and spread of Feynman diagrams through the theoretical physics communities of the USA, Japan, and the USSR in the period immediately after World War II. This test case has the advantage of having been studied historically in great detail, which allows validation of our results. We estimate the effectiveness of adoption of the idea in the three communities and find values for parameters reflecting both intentional social organization and long lifetimes for the idea. These features are probably general characteristics of the spread of ideas, but not of common epidemics.
Date: May 5, 2005
Creator: Bettencourt, L. M. A.; Cintron-Arias, A.; Kaiser, D. I. & Castillo-Chavez, C.
System: The UNT Digital Library
Improved Processes to Remove Naphthenic Acids (open access)

Improved Processes to Remove Naphthenic Acids

In the second year of this project, we continued our effort to develop low temperature decarboxylation catalysts and investigate the behavior of these catalysts at different reaction conditions. We conducted a large number of dynamic measurements with crude oil and model compounds to obtain the information at different reaction stages, which was scheduled as the Task2 in our work plan. We developed a novel adsorption method to remove naphthenic acid from crude oil using naturally occurring materials such as clays. Our results show promise as an industrial application. The theoretical modeling proposed several possible reaction pathways and predicted the reactivity depending on the catalysts employed. From all of these studies, we obtained more comprehensive understanding about catalytic decarboxylation and oil upgrading based on the naphthenic acid removal concept.
Date: May 5, 2005
Creator: Zhang, Aihua; Ma, Qisheng; Wang, Kangshi; Goddard, William A. & Tang, Yongchun
System: The UNT Digital Library
Application of Reservoir Characterization and Advanced Technology to Improve Recovery and Economics in a Lower Quality Shallow Shelf San Andres Reservoir. Annual Report: August 3, 2000--August 2, 2001 (open access)

Application of Reservoir Characterization and Advanced Technology to Improve Recovery and Economics in a Lower Quality Shallow Shelf San Andres Reservoir. Annual Report: August 3, 2000--August 2, 2001

The OXY-operated Class 2 Project at West Welch is designed to demonstrate how the use of advanced technology can improve the economics of miscible CO{sub 2} injection projects in lower quality Shallow Shelf Carbonate reservoirs. The research and design phase (Budget Period 1) primarily involved advanced reservoir characterization. The current demonstration phase (Budget Period 2) is the implementation of the reservoir management plan for an optimum miscible CO{sub 2} flood design based on the reservoir characterization. Although Budget Period 1 for the Project officially ended 12/31/96, reservoir characterization and simulation work continued during the Budget Period 2. During the seventh annual reporting period (8/3/00-8/2/01) covered by this report, work continued on interpretation of the interwell seismic data to create porosity and permeability profiles which were distributed into the reservoir geostatistically. The initial interwell seismic CO{sub 2} monitor survey was conducted and the acquired data processed and interpretation started. Only limited well work and facility construction were conducted in the project area. The CO{sub 2} injection initiated in October 1997 was continued, although the operator had to modify the operating plan in response to low injection rates, well performance and changes in CO{sub 2} supply. CO{sub 2} injection was focused in …
Date: May 5, 2003
Creator: Beebe, Tom
System: The UNT Digital Library
A proposal for a UPC memory consistency model, v1.0 (open access)

A proposal for a UPC memory consistency model, v1.0

The memory consistency model in a language defines the order in which the results of write operations maybe observed through read operations. The behavior of a UPC program may depend on the timing of accesses to shared variables, so a program defines a set of possible executions, rather than a single execution. The memory consistency model constrains the set of possible executions for a given program; the user may then rely on properties that are true of all of those executions. The memory consistency model is defined in terms of the read and write operations issued by each thread in naive translation of the code, i.e., without any code transformations by the compiler, with each thread issuing operations as defined by the abstract machine defined in ISO C 5.1.2.3. A UPC compiler or run time system may perform various code transformations to improve performance, so long as they are not visible to the programmer - i.e., provided the set of externally-visible behaviors (the input/output dynamics and volatile behavior defined in ISO C 5.1.2.3) from any execution of the transformed program are identical to those of the original program executing on the abstract machine and adhering to the consistency model defined …
Date: May 5, 2004
Creator: Yelick, Katherine; Bonachea, Dan & Wallace, Charles
System: The UNT Digital Library