Application of 3D X-ray CT data sets to finite element analysis (open access)

Application of 3D X-ray CT data sets to finite element analysis

Finite Element Modeling (FEM) is becoming more important as industry drives toward concurrent engineering. A fundamental hindrance to fully exploiting the power of FEM is the human effort required to acquire complex part geometry, particularly as-built geometry, as a FEM mesh. Many Quantitative Non Destructive Evaluation (QNDE) techniques that produce three-dimensional (3D) data sets provide a substantial reduction in the effort required to apply FEM to as-built parts. This paper describes progress at LLNL on the application of 3D X-ray computed tomography (CT) data sets to more rapidly produce high-quality FEM meshes of complex, as-built geometries. Issues related to the volume segmentation of the 3D CT data as well as the use of this segmented data to tailor generic hexahedral FEM meshes to part specific geometries are discussed. The application of these techniques to FEM analysis in the medical field is reported here.
Date: August 31, 1995
Creator: Bossart, P. L.; Martz, H. E.; Brand, H. R. & Hollerbach, K.
Object Type: Article
System: The UNT Digital Library
Characterization of static- and fatigue-loaded carbon composites by X-ray CT (open access)

Characterization of static- and fatigue-loaded carbon composites by X-ray CT

The development and improvement of advanced materials is strictly connected to the understanding of the properties and behavior of such materials as a function of both their macro and micro-structures. The application of X-ray computed tomography (CT) to these materials allows for a better understanding of the materials properties and behavior on either macro or micro-structure scales. The authors applied CT to study a set of aerospace grade carbon fiber/thermoplastic matrix composites. Samples of APC-2 (PEEK/AS4) were subjected to either static or high-stress fatigue loading in tension. Both notched (central circular hole) and unnotched specimens were examined. They are investigating a high-temperature thermoplastic polyimide composite sample by acquiring CT data sets before, during (at set intervals), and after full-reversal (tension-compression), low-stress fatigue loading at the upper use temperature. The CT scanner employed and the results obtained in the analysis of 3D CT data sets to study the defects and other features within the different composites are presented in this report.
Date: August 31, 1995
Creator: Savona, V.; Martz, H. E.; Brand, H. R.; Groves, S. E. & DeTeresa, S. J.
Object Type: Report
System: The UNT Digital Library
Coal-fired high performance power generating system. Final report (open access)

Coal-fired high performance power generating system. Final report

As a result of the investigations carried out during Phase 1 of the Engineering Development of Coal-Fired High-Performance Power Generation Systems (Combustion 2000), the UTRC-led Combustion 2000 Team is recommending the development of an advanced high performance power generation system (HIPPS) whose high efficiency and minimal pollutant emissions will enable the US to use its abundant coal resources to satisfy current and future demand for electric power. The high efficiency of the power plant, which is the key to minimizing the environmental impact of coal, can only be achieved using a modern gas turbine system. Minimization of emissions can be achieved by combustor design, and advanced air pollution control devices. The commercial plant design described herein is a combined cycle using either a frame-type gas turbine or an intercooled aeroderivative with clean air as the working fluid. The air is heated by a coal-fired high temperature advanced furnace (HITAF). The best performance from the cycle is achieved by using a modern aeroderivative gas turbine, such as the intercooled FT4000. A simplified schematic is shown. In the UTRC HIPPS, the conversion efficiency for the heavy frame gas turbine version will be 47.4% (HHV) compared to the approximately 35% that is achieved …
Date: August 31, 1995
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Future land use plan (open access)

Future land use plan

The US Department of Energy`s (DOE) changing mission, coupled with the need to apply appropriate cleanup standards for current and future environmental restoration, prompted the need for a process to determine preferred Future Land Uses for DOE-owned sites. DOE began the ``Future Land Use`` initiative in 1994 to ensure that its cleanup efforts reflect the surrounding communities` interests in future land use. This plan presents the results of a study of stakeholder-preferred future land uses for the Brookhaven National Laboratory (BNL), located in central Long Island, New York. The plan gives the Laboratory`s view of its future development over the next 20 years, as well as land uses preferred by the community were BNL ever to cease operations as a national laboratory (the post-BNL scenario). The plan provides an overview of the physical features of the site including its history, topography, geology/hydrogeology, biological inventory, floodplains, wetlands, climate, and atmosphere. Utility systems and current environmental operations are described including waste management, waste water treatment, hazardous waste management, refuse disposal and ground water management. To complement the physical descriptions of the site, demographics are discussed, including overviews of the surrounding areas, laboratory population, and economic and non-economic impacts.
Date: August 31, 1995
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Multiphase Flow Modeling - Validation and Application CRADA MC94-019, Final Report (open access)

Multiphase Flow Modeling - Validation and Application CRADA MC94-019, Final Report

For the development and validation of multiphase flow modeling capability, a cooperative research and development agreement (CRADA) is in effect between Morgantown Energy Technology Center (METC) and Fluent Inc. To validate the Fluent multiphase model, several simulations were conducted at METC and the results were compared with the results of MFIX, a multiphase flow code developed at METC, and with experimental data. The results of these validation studies will be presented. In addition, the application of multiphase flow modeling will be illustrated by presenting the results of simulations of a filter back- flushing and a fluidized bed coal gasifier. These simulations were conducted only with MFIX, since certain features needed in these simulations will be available only in the next release of Fluent.
Date: August 31, 1995
Creator: Syamlal, Madhava & Nicoletti, Philip A.
Object Type: Report
System: The UNT Digital Library
Petroleum marketing monthly, September 1995 with data for June 1995 (open access)

Petroleum marketing monthly, September 1995 with data for June 1995

The Petroleum Marketing Monthly (PMM) provides information and statistical data on a variety of crude oils and refined petroleum products. The publication presents statistics on crude oil costs and refined petroleum products sales for use by industry, government, private sector analysts, educational institutions, and consumers. Data on crude oil include the domestic first purchase price, the fob and landed cost of imported crude oil, and the refiners` acquisition cost of crude oil. Refined petroleum product sales data include motor gasoline, distillates, residuals, aviation fuels, kerosene, and propane. The Petroleum Marketing Division, Office of Oil and Gas, Energy Information Administration ensures the accuracy, quality, and confidentiality of the published data in the Petroleum Marketing Monthly.
Date: August 31, 1995
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Preliminary report: NIF laser bundle review (open access)

Preliminary report: NIF laser bundle review

As requested in the guidance memo {sup 1}, this committe determined whether there are compelling reasons to recommend a change from the NIF CDR baseline laser. The baseline bundle design based on a tradeoff between cost and technical risk, which is replicated four times to create the required 192 beams. The baseline amplifier design uses bottom loading 1{times}4 slab and flashlamp cassettes for amplifier maintenance and large vacuum enclosures (2.5m high {times} 7m wide in cross-section for each of the two spatial filters in each of the four bundles. The laser beams are arranged in two laser bays configured in a u-shape around the target area. The entire bundle review effort was performed in a very short time (six weeks) and with limited resources (15 personnel part-time). This should be compared to the effort that produced the CDR design (12 months, 50 to 100 personnel). This committee considered three alternate bundle configurations (2{times}2, 4{times}2, and 4{times}4 bundles), and evaluated each bundle against the baseline design using the seven requested issues in the guidance memo: Cost; schedule; performance risk; maintainability/operability; hardware failure cost exposure; activation; and design flexibility. The issues were reviewed to identify differences between each alternate bundle configuration and …
Date: August 31, 1995
Creator: Tietbohl, G.L.; Larson, D.W. & Erlandson, A.C.
Object Type: Report
System: The UNT Digital Library
Radionuclide separations using pillared layered materials. Final report (open access)

Radionuclide separations using pillared layered materials. Final report

The objective of this project is to prepare an all inorganic strontium specific sorbent or ion exchanger for the removal of highly alkaline nuclear waste solutions. A series of clays and layered titanates were pillared and calcined to convert their essentially two dimensional structure to three dimensional porous structures with high surface areas. The pillaring agents were alumina, zirconia, chromia and silica based. The pillared clays, particularly those containing Zr pillars, achieved moderate (Kd as high at 13,700 ml/g with V:m = 28) selectivities for Sr{sup 2+}. In contrast, the silica pillared titanates showed exceptional affinities for Sr{sup 2+} with Kd values in excess of 100,000 ml/g in 5M NaNO{sup 3} + 1M NaOH. These latter results suggest a more detailed study of the pillared titanates in the presence of simulants closely resembling real waste solutions.
Date: August 31, 1995
Creator: Clearfield, A.
Object Type: Report
System: The UNT Digital Library
Silicon bonding techniques for X-ray optics: A summary of R&D work carried out by the Experimental Facilities Division Optics Group (XFD-OP) through July 1995 (open access)

Silicon bonding techniques for X-ray optics: A summary of R&D work carried out by the Experimental Facilities Division Optics Group (XFD-OP) through July 1995

Some of the most efficient heat-exchanger designs for direct-cooled optics consist of two or more pieces of silicon single crystal bonded to each other and attached to a coolant manifold. Therefore, achieving successful silicon-to-silicon and silicon-to-metal bonds has become one of the goals of the high heat load (HHL) optics program. A viable bond for a cooled silicon optic has to satisfy the following requirements: strain free; compatible with the coolant used; radiation resistant; coefficient of thermal expansion of the bonding agent must be close to that of silicon. The techniques that have been pursued by XFD-OP members are: Si-Si direct bonding; Si-Si die attach paste bonding; Si-Si and Si-metal epoxy bonding; Si-Si and Si-metal glass frit bonding; and Si-metal gold-based solder. A description of each of these techniques and their performance are described in this report.
Date: August 31, 1995
Creator: Fernandez, P.B.
Object Type: Report
System: The UNT Digital Library
Surfactant loss control in chemical flooding: Spectroscopic and calorimetric study of adsorption and precipitation on reservoir minerals. Quarterly progress report, April 1, 1995--June 30, 1995 (open access)

Surfactant loss control in chemical flooding: Spectroscopic and calorimetric study of adsorption and precipitation on reservoir minerals. Quarterly progress report, April 1, 1995--June 30, 1995

Previously, adsorption and desorption behaviors of tetradecyl trimethyl ammonium chloride (TTAC) and pentadecylethoxylated nonyl phenol (NP-15) mixtures have been reported. It was observed that there was either synergistic or competitive adsorption between these two surfactants depending on the mixture ratios and the concentrations studied and that their adsorption/desorption behaviors were also rather complex. To better elucidate the mechanisms involved in these adsorption and desorption processes it is important to the understand the exact nature of the physico-chemical interactions between various components in mixtures and, how this in turn, controls the performance of the surfactant systems. Recently we have adapted the ultrafiltration technique to determine monomer concentrations in surfactant mixtures and to study the aggregation phenomenon between TTAC and NP-15. During the current report period, monomer concentrations of TTAC and NP-15 were measured for different mixing ratios at a constant ionic strength of 0.03 M NaCl and after adsorption for 4:1 TTAC:NP-15 mixture system. Possible behaviors of mixed micellization processes in solution are proposed and the relationship between monomer concentration and adsorption density is discussed.
Date: August 31, 1995
Creator: Somasundaran, P.
Object Type: Report
System: The UNT Digital Library
Development of a membrane-based process for the treatment of oily waste waters. Annual report, March 4, 1993--March 5, 1995 (open access)

Development of a membrane-based process for the treatment of oily waste waters. Annual report, March 4, 1993--March 5, 1995

The goal of this program was to develop an economical oily-water treatment system based on reverse-osmosis (RO) membrane technology. The RO system would be used to: (1) reduce oil-production costs by reducing the volume of waste water for which disposal is required; (2) form the basis of a generic waste-water treatment system that can easily be integrated into oil-field operations, especially at production facilities that are small or in remote locations: and (3) produce water clean enough to meet current and anticipated environmental regulations. The specific focus of this program was to develop a hollow-fiber membrane module capable of treating oily waste waters. Typically, the organics in oily waste water swell or dissolve the materials used in conventional polymeric membranes and modules. Our goal was to develop hollow-fiber membranes and modules that were more solvent-resistant than conventional membrane modules. We successfully achieved this goal. During the course of this program. we developed thin-film-composite (TFC) membranes, which consisted of a solvent-resistant selective coating placed on a solvent-resistant hollow-fiber support. These TFC membranes were used in low-cost, hollow-fiber modules, which were made using solvent-resistant components. The modules were tube-side-feed modules, in which the oily waste water travels down the inside (lumen) of …
Date: August 30, 1995
Creator: McCray, S.B.
Object Type: Report
System: The UNT Digital Library
Engineering development of advanced coal-fired low-emission boiler systems. Technical progress report No. 11, April 1995--June 1995 (open access)

Engineering development of advanced coal-fired low-emission boiler systems. Technical progress report No. 11, April 1995--June 1995

The Pittsburgh Energy Technology Center of the U.S. Department of Energy (DOE) has contracted with Combustion Engineering, Inc. (ABB CE) to perform work on the {open_quotes}Engineering Development of Advanced Coal-Fired Low-Emission Boiler Systems{close_quotes} Project and has authorized ABB CE to complete Phase I on a cost-reimbursable basis and Phases II and III on a cost-share basis. The overall objective of the Project is the expedited commercialization of advanced coal-fired low-emission boiler systems. The specified primary objectives are: (1) NO{sub x} emissions not greater than one-third NSPS. (2) SO{sub x} emissions not greater than one-third NSPS. (3) Particulate emissions not greater than one-half NSPS. The specific secondary objectives are: (1) Improved ash disposability and reduced waste generation. (2) Reduced air toxics emissions. (3) Increased generating efficiency. The final deliverables are a design data base that will allow future coal-fired power plants to meet the stated objectives and a preliminary design of a Commercial Generation Unit. The work in Phase I covered a 24-month period and included system analysis, RD&T Plan formulation, component definition, and preliminary Commercial Generating Unit (CGU) design. Phase II will cover a 15-month period and will include preliminary Proof-of-Concept Test Facility (POCTF) design and subsystem testing. Phase III …
Date: August 30, 1995
Creator: unknown
Object Type: Report
System: The UNT Digital Library
The evolution and explosion of massive Stars II: Explosive hydrodynamics and nucleosynthesis (open access)

The evolution and explosion of massive Stars II: Explosive hydrodynamics and nucleosynthesis

The nucleosynthetic yield of isotopes lighter than A = 66 (zinc) is determined for a grid of stellar masses and metallicities including stars of 11, 12, 13, 15, 18, 19, 20, 22, 25, 30, 35, and 40 M{sub {circle_dot}} and metallicities Z = 0, 10{sup {minus}4}, 0.01, 0.1, and 1 times solar (a slightly reduced mass grid is employed for non-solar metallicities). Altogether 78 different model supernova explosions are calculated. In each case nucleosynthesis has already been determined for 200 isotopes in each of 600 to 1200 zones of the presupernova star, including the effects of time dependent convection. Here each star is exploded using a piston to give a specified final kinetic energy at infinity (typically 1.2 {times} 10{sup 51} erg), and the explosive modifications to the nucleosynthesis, including the effects of neutrino irradiation, determined. A single value of the critical {sup 12}C({sub {alpha},{gamma}}){sup 16}O reaction rate corresponding to S(300 keV) = 170 keV barns is used in all calculations. The synthesis of each isotope is discussed along with its sensitivity to model parameters. In each case, the final mass of the collapsed remnant is also determined and often found not to correspond to the location of the piston …
Date: August 30, 1995
Creator: Woosley, S. E. & Weaver, T. A.
Object Type: Report
System: The UNT Digital Library
Risk communication: Uncertainties and the numbers game (open access)

Risk communication: Uncertainties and the numbers game

The science of risk assessment seeks to characterize the potential risk in situations that may pose hazards to human health or the environment. However, the conclusions reached by the scientists and engineers are not an end in themselves - they are passed on to the involved companies, government agencies, legislators, and the public. All interested parties must then decide what to do with the information. Risk communication is a type of technical communication that involves some unique challenges. This paper first defines the relationships between risk assessment, risk management, and risk communication and then explores two issues in risk communication: addressing uncertainty and putting risk number into perspective.
Date: August 30, 1995
Creator: Ortigara, M.
Object Type: Article
System: The UNT Digital Library
Development and testing of a high efficiency advanced coal combustor, Phase III industrial boiler retrofit. Quarterly technical progress report No. 15, April 1, 1995--June 30, 1995 (open access)

Development and testing of a high efficiency advanced coal combustor, Phase III industrial boiler retrofit. Quarterly technical progress report No. 15, April 1, 1995--June 30, 1995

The objective of this project is to retrofit a burner capable of firing microfine coal to a standard gas/oil designed industrial boiler to assess the technical and economic viability of displacing premium fuels with microfine coal. This report documents the technical aspects of this project during the fifteenth quarter (April `95 through June `95) of the program. The overall program has consisted of five major tasks: (1.0) A review of current state-of-the-art coal firing system components. (2.0) Design and experimental testing of a prototype HEACC (High Efficiency Advanced Coal Combustor) burner. (3.0) Installation and testing of a prototype HEACC system in a commercial retrofit application. (4.0) Economics evaluation of the HEACC concept for retrofit applications. (5.0) Long term demonstration under commercial user demand conditions. Task 1 through Task 4 were previously completed. Based on all the results obtained to date the ABB/Penn State team and DOE/PETC have decided to conduct a 1000 hr demonstration test (Task 5). Importantly, a decision was made to employ a new burner for the demonstration. The new burner is based on the concept called {open_quotes}Radially Stratified Flame Core (RSFC){close_quotes}, developed by MIT and licensed by ABB. Work under Task 5 of this program was started …
Date: August 29, 1995
Creator: Scaroni, A. W.; Miller, B. G. & McGowan, J. G.
Object Type: Report
System: The UNT Digital Library
High-resolution imaging of hypervelocity metal jets using advanced high-speed photographic techniques (open access)

High-resolution imaging of hypervelocity metal jets using advanced high-speed photographic techniques

It is now possible to obtain high resolution sequential photographs of the initial formation and evolution of hypervelocity metal jets formed by shaped charge devices fired in air. Researchers have been frustrated by the high velocity of the jet material and the luminous sheath of hot gases cloaking the jet that made detailed observation of the jet body extremely difficult. The camera system that provides the photographs is a large format multi-frame electro-optic camera, referred to as an IC camera (IC stands for image converter), that utilizes electro-optic shuttering, monochromatic pulsed laser illumination and bandpass filtering to provide sequential pictures (in 3D if desired) with minimal degradation due to luminous air shocks or motion blur. The large format (75mm image plane), short exposure (15 ns minimum), ruby laser illumination and bandpass filtering (monochromatic illumination while excluding extraneous light) produces clear, sharp, images of the detailed surface structure of a metal shaped charge jet during early jet formation, elongation of the jet body, jet tip evolution and subsequent particulation (breakup) of the jet body. By utilizing the new camera system in conjunction with the more traditional rotating mirror high speed cameras, pulsed radiography, and electrical sensors, a maximum amount of, often …
Date: August 29, 1995
Creator: Shaw, L.L. & Muelder, S.A.
Object Type: Report
System: The UNT Digital Library
Surface Water Transport for the F/H Area Seepage Basins Groundwater Program (open access)

Surface Water Transport for the F/H Area Seepage Basins Groundwater Program

The contribution of the F- and H-Area Seepage Basins (FHSBs) tritium releases to the tritium concentration in the Savannah River are presented in this report. WASP5 was used to simulate surface water transport for tritium releases from the FHSBs. The WASP5 model was qualified with the 1993 tritium measurements at US Highway 301. The tritium concentrations in Fourmile Branch and the Savannah River were calculated for tritium releases from FHSBs. The calculated tritium concentrations above normal environmental background in the Savannah River, resulting from FHSBs releases, drop from 1.25 pCi/ml (<10% of EPA Drinking Water Guide) in 1995 to 0.0056 pCi/ml in 2045.
Date: August 29, 1995
Creator: Chen, Kuo-Fu
Object Type: Report
System: The UNT Digital Library
Coherent Bremsstrahlung at Relativistic Heavy Ion Colliders (open access)

Coherent Bremsstrahlung at Relativistic Heavy Ion Colliders

This report talks about Coherent Bremsstrahlung at Relativistic Heavy Ion Colliders
Date: August 28, 1995
Creator: Serbo, V. G.
Object Type: Report
System: The UNT Digital Library
D0 Silicon Upgrade: Upgrade Piping Loads on Cleanroom Roof (open access)

D0 Silicon Upgrade: Upgrade Piping Loads on Cleanroom Roof

The proposed piping layout for the DO upgrade will run along the south wall of DAB. The cryogenic service pipe runs above the upper and lower cleanroom roofs and will need to be supported by the roofs beams. Calculations were done to determine the stresses in the I-beams created by the existing and additional loads due to the upgrade. Refer to drawing no. 3823.115-ME-317283 for drawings of the piping layout. Figure 1 shows the 'plan view' portion of this drawing. The weight of the individual lines were calculated in figure 2 assuming a pipe density of O.28 lbm/in{sup 3} for stainless steel (0.12% C) and a fluid density (assuming LN2 at 1 atm) of 0.03 lbm/in{sup 3}. The weights of the corrugated steel flooring, assembly hall feed cans, support beams, and roof hatch were also included in the analysis. These loads are calculated on pgs. 5-6. A floor load of 50 lbf/ft{sup 2} was also added in order to maintain the existing floor load limit in addition to the added piping loads. Measurements of the dimensions of the I-beams determined that the nominal sizes of the beams were W8 x 21 for the lower roof and W14 x 26 for …
Date: August 28, 1995
Creator: Sakla, Steve
Object Type: Report
System: The UNT Digital Library
Report on follow-up inspection of the double funding of security for special nuclear material at the Richland Operations Office (open access)

Report on follow-up inspection of the double funding of security for special nuclear material at the Richland Operations Office

In a June 3, 1993, Office of Inspections Letter Report, the Office of Inspector General notified the Department`s Acting Chief Financial Officer that the Department had requested and received $60 million, double the funds needed, for the safeguard and security of special nuclear material at the Department`s Richland Operations Office in Fiscal Year 1993. In response to the Letter Report, in a June 28, 1993, memorandum, the Acting Chief Financial Officer advised the Office of Inspector General that the extra $30 million received by the Office of Environmental Management would either be: (1) applied to unanticipated requirements in Fiscal Year 1993; (2) applied to the anticipated Congressional reduction to the Department`s Fiscal Year 1994 budget request; or (3) used as an offset to the Fiscal Year 1995 budget request. The purpose of this follow-up inspection was to review the circumstances surrounding the Fiscal Year 1993 double funding for the security of special nuclear material at Richland. The principal objectives of this inspection were to: (1) identify contributing factors to the double funding and corrective actions needed to prevent the double funding from reoccurring; and (2) review Departmental Managers` response to the double funding issue.
Date: August 28, 1995
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Testing EQ3/6 and GEMBOCHS using fluid-mineral equilibria in the wairakei geothermal system (open access)

Testing EQ3/6 and GEMBOCHS using fluid-mineral equilibria in the wairakei geothermal system

The ability of the EQ3 and EQ6 geochemical modeling codes and the GEMBOCHS thermodynamic data bases to simulate geochemical changes in the post-emplacement environment at the potential Yucca Mountain, Nevada repository is being tested using observed mineral-fluid relations in the Taupo Volcanic Zone of New Zealand. In this report, comparisons between observed equilibria and simulations of field relations in the Wairakei geothermal system are used to test the codes and data bases in high temperature systems. Analysis of trends in water and gas chemistries and well discharge characteristics with time were used to identify a set of representative water and gas analyses from zones producing at about 250{degrees}C. The most common vein minerals at this temperature are: wairakite, adularia, epidote, quartz, albite, chlorite, calcite, prehnite, and pyrite. Calculations were carried out using version 7.2a R134 of EQ3 and version 7.2a R130 of EQ6 and the SUPCRT and COM subsets of the R24 version of GEMBOCHS. Thermodynamic data bases using different data for Al aqueous species were sued to identify the data set which produced the best matches between observed and calculated equilibria. The simulations described in this paper suggest that EQ6 can be used to identify facies of minerals that …
Date: August 28, 1995
Creator: Bruton, C. J.
Object Type: Report
System: The UNT Digital Library
A theoretical comparison of evolutionary algorithms and simulated annealing (open access)

A theoretical comparison of evolutionary algorithms and simulated annealing

This paper theoretically compares the performance of simulated annealing and evolutionary algorithms. Our main result is that under mild conditions a wide variety of evolutionary algorithms can be shown to have greater performance than simulated annealing after a sufficiently large number of function evaluations. This class of EAs includes variants of evolutionary strategie and evolutionary programming, the canonical genetic algorithm, as well as a variety of genetic algorithms that have been applied to combinatorial optimization problems. The proof of this result is based on a performance analysis of a very general class of stochastic optimization algorithms, which has implications for the performance of a variety of other optimization algorithm.
Date: August 28, 1995
Creator: Hart, W.E.
Object Type: Article
System: The UNT Digital Library
Chemical kinetic modelling of hydrocarbon ignition (open access)

Chemical kinetic modelling of hydrocarbon ignition

Chemical kinetic modeling of hydrocarbon ignition is discussed with reference to a range of experimental configurations, including shock tubes, detonations, pulse combustors, static reactors, stirred reactors and internal combustion engines. Important conditions of temperature, pressure or other factors are examined to determine the main chemical reaction sequences responsible for chain branching and ignition, and kinetic factors which can alter the rate of ignition are identified. Hydrocarbon ignition usually involves complex interactions between physical and chemical factors, and it therefore is a suitable and often productive subject for computer simulations. In most of the studies to be discussed below, the focus of the attention is placed on the chemical features of the system. The other physical parts of each application are generally included in the form of initial or boundary conditions to the chemical kinetic parts of the problem, as appropriate for each type of application being addressed.
Date: August 25, 1995
Creator: Westbrook, C.K.; Pitz, W.J.; Curran, H.J.; Gaffuri, P. & Marinov, N.M.
Object Type: Article
System: The UNT Digital Library
International petroleum statistics report, August 1995 (open access)

International petroleum statistics report, August 1995

The International Petroleum Statistics Report presents data on international oil production, demand, imports, exports, and stocks. The report has four sections. Section 1 contains time series data on world oil production, and on oil demand and stocks in the Organization for Economic Cooperation and Development (OECD). This section contains annual data beginning in 1985, and monthly data for the most recent two years. Section 2 presents an oil supply/demand balance for the world. This balance is presented in quarterly intervals for the most recent two years. Section 3 presents data on oil imports by OECD countries. This section contains annual data for the most recent year, quarterly data for the most recent two quarters, and monthly data for the most recent twelve months. Section 4 presents annual time series data on world oil production and oil stocks, demand, and trade in OECD countries. World oil production and OECD demand data are for the years 1970 through 1994; OECD stocks from 1973 through 1994; and OECD trade from 1984 through 1994.
Date: August 25, 1995
Creator: unknown
Object Type: Report
System: The UNT Digital Library