Argonne's Laboratory Computing Resource Center : 2006 Annual Report. (open access)

Argonne's Laboratory Computing Resource Center : 2006 Annual Report.

Argonne National Laboratory founded the Laboratory Computing Resource Center (LCRC) in the spring of 2002 to help meet pressing program needs for computational modeling, simulation, and analysis. The guiding mission is to provide critical computing resources that accelerate the development of high-performance computing expertise, applications, and computations to meet the Laboratory's challenging science and engineering missions. In September 2002 the LCRC deployed a 350-node computing cluster from Linux NetworX to address Laboratory needs for mid-range supercomputing. This cluster, named 'Jazz', achieved over a teraflop of computing power (10{sup 12} floating-point calculations per second) on standard tests, making it the Laboratory's first terascale computing system and one of the 50 fastest computers in the world at the time. Jazz was made available to early users in November 2002 while the system was undergoing development and configuration. In April 2003, Jazz was officially made available for production operation. Since then, the Jazz user community has grown steadily. By the end of fiscal year 2006, there were 76 active projects on Jazz involving over 380 scientists and engineers. These projects represent a wide cross-section of Laboratory expertise, including work in biosciences, chemistry, climate, computer science, engineering applications, environmental science, geoscience, information science, materials …
Date: May 31, 2007
Creator: Bair, R. B.; Kaushik, D. K.; Riley, K. R.; Valdes, J. V.; Drugan, C. D. & Pieper, G. P.
Object Type: Report
System: The UNT Digital Library
A Customizable Fuzzy Expert System for Regional and Local Play Analysis (open access)

A Customizable Fuzzy Expert System for Regional and Local Play Analysis

None
Date: May 31, 2007
Creator: Balch, Robert S. & Broadhead, Ronald F.
Object Type: Report
System: The UNT Digital Library
Military Base Closures and Realignment: Status of the 2005 Implementation Plan (open access)

Military Base Closures and Realignment: Status of the 2005 Implementation Plan

This report answers frequently asked questions regarding the the implementation for the 2005 Base Realignment and Closure (BRAC) plans, called “Business Plans”, describe the implementing actions, their timing, cost, and other related issues.
Date: May 31, 2007
Creator: Blackwell, Kristine E.
Object Type: Report
System: The UNT Digital Library
A Generalized Eigensolver based on Smoothed Aggregation (GES-SA) for Initializing Smoothed Aggregation Multigrid (SA) (open access)

A Generalized Eigensolver based on Smoothed Aggregation (GES-SA) for Initializing Smoothed Aggregation Multigrid (SA)

Consider the linear system Ax = b, where A is a large, sparse, real, symmetric, and positive definite matrix and b is a known vector. Solving this system for unknown vector x using a smoothed aggregation multigrid (SA) algorithm requires a characterization of the algebraically smooth error, meaning error that is poorly attenuated by the algorithm's relaxation process. For relaxation processes that are typically used in practice, algebraically smooth error corresponds to the near-nullspace of A. Therefore, having a good approximation to a minimal eigenvector is useful to characterize the algebraically smooth error when forming a linear SA solver. This paper discusses the details of a generalized eigensolver based on smoothed aggregation (GES-SA) that is designed to produce an approximation to a minimal eigenvector of A. GES-SA might be very useful as a standalone eigensolver for applications that desire an approximate minimal eigenvector, but the primary aim here is for GES-SA to produce an initial algebraically smooth component that may be used to either create a black-box SA solver or initiate the adaptive SA ({alpha}SA) process.
Date: May 31, 2007
Creator: Brezina, M; Manteuffel, T; McCormick, S; Ruge, J; Sanders, G & Vassilevski, P S
Object Type: Article
System: The UNT Digital Library
Seismic velocity estimation from time migration (open access)

Seismic velocity estimation from time migration

This is concerned with imaging and wave propagation in nonhomogeneous media, and includes a collection of computational techniques, such as level set methods with material transport, Dijkstra-like Hamilton-Jacobi solvers for first arrival Eikonal equations and techniques for data smoothing. The theoretical components include aspects of seismic ray theory, and the results rely on careful comparison with experiment and incorporation as input into large production-style geophysical processing codes. Producing an accurate image of the Earth's interior is a challenging aspect of oil recovery and earthquake analysis. The ultimate computational goal, which is to accurately produce a detailed interior map of the Earth's makeup on the basis of external soundings and measurements, is currently out of reach for several reasons. First, although vast amounts of data have been obtained in some regions, this has not been done uniformly, and the data contain noise and artifacts. Simply sifting through the data is a massive computational job. Second, the fundamental inverse problem, namely to deduce the local sound speeds of the earth that give rise to measured reacted signals, is exceedingly difficult: shadow zones and complex structures can make for ill-posed problems, and require vast computational resources. Nonetheless, seismic imaging is a crucial part …
Date: May 31, 2007
Creator: Cameron, Maria Kourkina
Object Type: Thesis or Dissertation
System: The UNT Digital Library
ITER Shape Controller and Transport Simulations (open access)

ITER Shape Controller and Transport Simulations

We currently use the CORSICA integrated modeling code for scenario studies for both the DIII-D and ITER experiments. In these simulations, free- or fixed-boundary equilibria are simultaneously converged with thermal evolution determined from transport models providing temperature and current density profiles. Using a combination of fixed boundary evolution followed by free-boundary calculation to determine the separatrix and coil currents. In the free-boundary calculation, we use the state-space controller representation with transport simulations to provide feedback modeling of shape, vertical stability and profile control. In addition to a tightly coupled calculation with simulator and controller imbedded inside CORSICA, we also use a remote procedure call interface to couple the CORSICA non-linear plasma simulations to the controller environments developed within the Mathworks Matlab/Simulink environment. We present transport simulations using full shape and vertical stability control with evolution of the temperature profiles to provide simulations of the ITER controller and plasma response.
Date: May 31, 2007
Creator: Casper, T A; Meyer, W H; Pearlstein, L D & Portone, A
Object Type: Article
System: The UNT Digital Library
The Amending Process in the House of Representatives (open access)

The Amending Process in the House of Representatives

This report consists of the amending process in the house of representatives.
Date: May 31, 2007
Creator: Davis, Christopher M.
Object Type: Report
System: The UNT Digital Library
Production of Endohedral Fullerenes by Ion Implantation (open access)

Production of Endohedral Fullerenes by Ion Implantation

The empty interior cavity of fullerenes has long been touted for containment of radionuclides during in vivo transport, during radioimmunotherapy (RIT) and radioimaging for example. As the chemistry required to open a hole in fullerene is complex and exceedingly unlikely to occur in vivo, and conformational stability of the fullerene cage is absolute, atoms trapped within fullerenes can only be released during extremely energetic events. Encapsulating radionuclides in fullerenes could therefore potentially eliminate undesired toxicity resulting from leakage and catabolism of radionuclides administered with other techniques. At the start of this project however, methods for production of transition metal and p-electron metal endohedral fullerenes were completely unknown, and only one method for production of endohedral radiofullerenes was known. They therefore investigated three different methods for the production of therapeutically useful endohedral metallofullerenes: (1) implantation of ions using the high intensity ion beam at the Oak Ridge National Laboratory (ORNL) Surface Modification and Characterization Research Center (SMAC) and fullerenes as the target; (2) implantation of ions using the recoil energy following alpha decay; and (3) implantation of ions using the recoil energy following neutron capture, using ORNL's High Flux Isotope Reactor (HFIR) as a thermal neutron source. While they were unable …
Date: May 31, 2007
Creator: Diener, Michael D.; Alford, J. Michael & Mirzadeh, Saed
Object Type: Report
System: The UNT Digital Library
Electrokinetic Hydrogen Generation from Liquid WaterMicrojets (open access)

Electrokinetic Hydrogen Generation from Liquid WaterMicrojets

We describe a method for generating molecular hydrogen directly from the charge separation effected via rapid flow of liquid water through a metal orifice, wherein the input energy is the hydrostatic pressure times the volume flow rate. Both electrokinetic currents and hydrogen production rates are shown to follow simple equations derived from the overlap of the fluid velocity gradient and the anisotropic charge distribution resulting from selective adsorption of hydroxide ions to the nozzle surface. Pressure-driven fluid flow shears away the charge balancing hydronium ions from the diffuse double layer and carries them out of the aperture. Downstream neutralization of the excess protons at a grounded target electrode produces gaseous hydrogen molecules. The hydrogen production efficiency is currently very low (ca. 10-6) for a single cylindrical jet, but can be improved with design changes.
Date: May 31, 2007
Creator: Duffin, Andrew M. & Saykally, Richard J.
Object Type: Article
System: The UNT Digital Library
Optimal Real-time Dispatch for Integrated Energy Systems (open access)

Optimal Real-time Dispatch for Integrated Energy Systems

This report describes the development and application of a dispatch optimization algorithm for integrated energy systems (IES) comprised of on-site cogeneration of heat and electricity, energy storage devices, and demand response opportunities. This work is intended to aid commercial and industrial sites in making use of modern computing power and optimization algorithms to make informed, near-optimal decisions under significant uncertainty and complex objective functions. The optimization algorithm uses a finite set of randomly generated future scenarios to approximate the true, stochastic future; constraints are included that prevent solutions to this approximate problem from deviating from solutions to the actual problem. The algorithm is then expressed as a mixed integer linear program, to which a powerful commercial solver is applied. A case study of United States Postal Service Processing and Distribution Centers (P&DC) in four cities and under three different electricity tariff structures is conducted to (1) determine the added value of optimal control to a cogeneration system over current, heuristic control strategies; (2) determine the value of limited electric load curtailment opportunities, with and without cogeneration; and (3) determine the trade-off between least-cost and least-carbon operations of a cogeneration system. Key results for the P&DC sites studied include (1) in …
Date: May 31, 2007
Creator: Firestone, Ryan Michael
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Ultra-Deepwater and Unconventional Natural Gas and Other Petroleum Resources (open access)

Ultra-Deepwater and Unconventional Natural Gas and Other Petroleum Resources

RPSEA is currently in its first year of performance under contract DE-AC26-07NT42677, Ultra-Deepwater and Unconventional Natural Gas and Other Petroleum Resources Program Administration. Significant progress has been made in establishing the program administration policies, procedures, and strategic foundation for future research awards. RPSEA has concluded an industry-wide collaborative effort to identify focus areas for research awards under this program. This effort is summarized in the RPSEA Draft Annual Plan, which is currently under review by committees established by the Secretary of Energy.
Date: May 31, 2007
Creator: Fray, Russell E.
Object Type: Report
System: The UNT Digital Library
Modeling Efforts to Aid in the Prediction of Process Enrichment Levels with the Intent of Identifying Potential Material Diversion (open access)

Modeling Efforts to Aid in the Prediction of Process Enrichment Levels with the Intent of Identifying Potential Material Diversion

As part of an ongoing effort at Lawrence Livermore National Laboratory (LLNL) to enhance analytical models that simulate enrichment and conversion facilities, efforts are underway to develop routines to estimate the total gamma-ray flux and that of specific lines around process piping containing UF{sub 6}. The intent of the simulation modeling effort is to aid in the identification of possible areas where material diversion could occur, as input to an overall safeguards strategy. The operation of an enrichment facility for the production of low enriched uranium (LEU) presents certain proliferation concerns, including both the possibility of diversion of LEU and the potential for producing material enriched to higher-than-declared, weapons-usable levels. Safeguards applied by the International Atomic Energy Agency (IAEA) are designed to provide assurance against diversion or misuse. Among the measures being considered for use is the measurement of radiation fields at various locations in the cascade hall. Our prior efforts in this area have focused on developing a model to predict neutron fields and how they would change during diversion of misuse. The neutron models indicated that while neutron detection useful in monitoring feed and product containers, it was not useful for monitoring process lines. Our current effort is …
Date: May 31, 2007
Creator: Guenther, C F; Elayat, H A; O?Connell, W J & Lambert, H E
Object Type: Article
System: The UNT Digital Library
Development of a Hydrogasification Process for Co-Production of Substitute Natural Gas (SNG) and Electric Power from Western Coals-Phase I (open access)

Development of a Hydrogasification Process for Co-Production of Substitute Natural Gas (SNG) and Electric Power from Western Coals-Phase I

The Advanced Hydrogasification Process (AHP)--conversion of coal to methane--is being developed through NETL with a DOE Grant and has successfully completed its first phase of development. The results so far are encouraging and have led to commitment by DOE/NETL to begin a second phase--bench scale reactor vessel testing, expanded engineering analysis and economic perspective review. During the next decade new means of generating electricity, and other forms of energy, will be introduced. The members of the AHP Team envision a need for expanded sources of natural gas or substitutes for natural gas, to fuel power generating plants. The initial work the team has completed on a process to use hydrogen to convert coal to methane (pipeline ready gas) shows promising potential. The Team has intentionally slanted its efforts toward the needs of US electric utilities, particularly on fuels that can be used near urban centers where the greatest need for new electric generation is found. The process, as it has evolved, would produce methane from coal by adding hydrogen. The process appears to be efficient using western coals for conversion to a highly sought after fuel with significantly reduced CO{sub 2} emissions. Utilities have a natural interest in the preservation …
Date: May 31, 2007
Creator: Hobbs, Raymond
Object Type: Report
System: The UNT Digital Library
Report on Toyota/Prius Motor Torque Capability, Torque Property, No-Load Back EMF, and Mechanical Losses, Revised May 2007 (open access)

Report on Toyota/Prius Motor Torque Capability, Torque Property, No-Load Back EMF, and Mechanical Losses, Revised May 2007

In today's hybrid vehicle market, the Toyota/Prius drive system is currently considered the leader in electrical, mechanical, and manufacturing innovations. It is significant that in today's marketplace, Toyota is able to manufacture and sell the vehicle for a profit. This project's objective is to test the torque capability of the 2004 Prius motor and to analyze the torque properties relating to the rotor structure. The tested values of no-load back electromotive force (emf) and mechanical losses are also presented.
Date: May 31, 2007
Creator: Hsu, J.S.; Ayers, C.W.; Coomer, C.L.; Wiles, R.H.; Burress, T.A.; Campbell, S.L. et al.
Object Type: Report
System: The UNT Digital Library
Foreign Direct Investment: Current Issues (open access)

Foreign Direct Investment: Current Issues

This report presents an overview of current issues related to foreign direct investment in the economy and the development of U.S policy toward inward and outward direct investment. It also assesses the role of foreign direct investment in the economy and the costs and benefits of direct investment.
Date: May 31, 2007
Creator: Jackson, James
Object Type: Report
System: The UNT Digital Library
Facilitating Oil Industry Access to Federal Lands through Interagency Data Sharing (open access)

Facilitating Oil Industry Access to Federal Lands through Interagency Data Sharing

Much of the environmental and technical data useful to the oil and gas industry and regulatory agencies is now contained in disparate state and federal databases. Delays in coordinating permit approvals between federal and state agencies translate into increased operational costs and stresses for the oil and gas industry. Making federal lease stipulation and area restriction data available on state agency Web sites will streamline a potential lessors review of available leases, encourage more active bidding on unleased federal lands, and give third-party operators independent access to data who otherwise may not have access to lease restrictions and other environmental data. As a requirement of the Energy Policy Conservation Act (EPCA), the Bureau of Land Management (BLM) is in the process of inventorying oil and natural gas resources beneath onshore federal lands and the extent and nature of any stipulation, restrictions, or impediments to the development of these resources. The EPCA Phase 1 Inventory resulted in a collection of GIS coverage files organized according to numerous lease stipulation reference codes. Meanwhile, state agencies also collect millions of data elements concerning oil and gas operations. Much of the oil and gas data nationwide is catalogued in the Ground Water Protection Council's …
Date: May 31, 2007
Creator: Jehn, Paul & Grunewald, Ben
Object Type: Report
System: The UNT Digital Library
Enhancement of Biogenic Coalbed Methane Production and Back Injection of Coalbed Methane Co-Produced Water (open access)

Enhancement of Biogenic Coalbed Methane Production and Back Injection of Coalbed Methane Co-Produced Water

Biogenic methane is a common constituent in deep subsurface environments such as coalbeds and oil shale beds. Coalbed methane (CBM) makes significant contributions to world natural gas industry and CBM production continues to increase. With increasing CBM production, the production of CBM co-produced water increases, which is an environmental concern. This study investigated the feasibility in re-using CBM co-produced water and other high sodic/saline water to enhance biogenic methane production from coal and other unconventional sources, such as oil shale. Microcosms were established with the selected carbon sources which included coal, oil shale, lignite, peat, and diesel-contaminated soil. Each microcosm contained either CBM coproduced water or groundwater with various enhancement and inhibitor combinations. Results indicated that the addition of nutrients and nutrients with additional carbon can enhance biogenic methane production from coal and oil shale. Methane production from oil shale was much greater than that from coal, which is possibly due to the greater amount of available Dissolved Organic Carbon (DOC) from oil shale. Inconclusive results were observed from the other sources since the incubation period was too low. WRI is continuing studies with biogenic methane production from oil shale.
Date: May 31, 2007
Creator: Jin, Song
Object Type: Text
System: The UNT Digital Library
Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems (open access)

Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems

Advanced electric power generation systems use a coal gasifier to convert coal to a gas rich in fuels such as H{sub 2} and CO. The gas stream contains impurities such as H{sub 2}S and HCl, which attack metal components of the coal gas train, causing plant downtime and increasing the cost of power generation. Corrosion-resistant coatings would improve plant availability and decrease maintenance costs, thus allowing the environmentally superior integrated-gasification-combined-cycle (IGCC) plants to be more competitive with standard power-generation technologies. Heat-exchangers, particle filters, turbines, and other components in the IGCC system must withstand the highly sulfiding conditions of the high-temperature coal gas over an extended period of time. The performance of components degrades significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low cost alloy will improve is resistance to such sulfidation attack and decrease capital and operating costs. The alloys used in the gasifier service include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive nickel-cobalt alloys. The Fe- and Ni-based high-temperature alloys are susceptible to sulfidation attack unless they are fortified with high levels of Cr, Al, and Si. To impart corrosion resistance, these elements need not be in the …
Date: May 31, 2007
Creator: Krishnan, Gopala N.; Malhotra, Ripudaman; Perez, Jordi; Hornbostel, Marc; Lau, Kai-Hung & Sanjurjo, Angel
Object Type: Report
System: The UNT Digital Library
Simulation of Aluminum Combustion and PETN Afterburning in a Confined Explosion (open access)

Simulation of Aluminum Combustion and PETN Afterburning in a Confined Explosion

None
Date: May 31, 2007
Creator: Kuhl, A L; Bell, J B; Beckner, V E & Khasainov, B
Object Type: Article
System: The UNT Digital Library
OPEN AIR DEMOLITION OF FACILITIES HIGHLY CONTAMINATED WITH PLUTONIUM (open access)

OPEN AIR DEMOLITION OF FACILITIES HIGHLY CONTAMINATED WITH PLUTONIUM

The demolition of highly contaminated plutonium buildings usually is a long and expensive process that involves decontaminating the building to near free- release standards and then using conventional methods to remove the structure. It doesn't, however, have to be that way. Fluor has torn down buildings highly contaminated with plutonium without excessive decontamination. By removing the select source term and fixing the remaining contamination on the walls, ceilings, floors, and equipment surfaces; open-air demolition is not only feasible, but it can be done cheaper, better (safer), and faster. Open-air demolition techniques were used to demolish two highly contaminated buildings to slab-on-grade. These facilities on the Department of Energy's Hanford Site were located in, or very near, compounds of operating nuclear facilities that housed hundreds of people working on a daily basis. To keep the facilities operating and the personnel safe, the projects had to be creative in demolishing the structures. Several key techniques were used to control contamination and keep it within the confines of the demolition area: spraying fixatives before demolition; applying fixative and misting with a fine spray of water as the buildings were being taken down; and demolishing the buildings in a controlled and methodical manner. In …
Date: May 31, 2007
Creator: LLOYD, E.R.
Object Type: Article
System: The UNT Digital Library
Summary of operations and performance of the Murdock site restoration project in June 2005-December 2006. (open access)

Summary of operations and performance of the Murdock site restoration project in June 2005-December 2006.

This document summarizes the performance of the groundwater and surface water restoration systems installed by the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) at the former CCC/USDA grain storage facility in Murdock, Nebraska, during the initial period of systems operation, from June 2005 through December 2006. In the Murdock project, several innovative technologies are being used to remove carbon tetrachloride contamination from a shallow aquifer underlying the town, as well as from water naturally discharged to the surface at the headwaters of a small creek (a tributary to Pawnee Creek) north of the town (Figure 1.1). The restoration activities at Murdock are being conducted by the CCC/USDA as a non-time-critical removal action under the regulatory authority and supervision of the U.S. Environmental Protection Agency (EPA), Region VII. Argonne National Laboratory assisted the CCC/USDA by providing technical oversight for the restoration effort and facilities during this review period. Included in this report are the results of all sampling and monitoring activities performed in accord with the EPA-approved Monitoring Plan for this site (Argonne 2006), as well as additional investigative activities conducted during the review period. This document presents overviews of the treatment facilities (Section 2) and site operations …
Date: May 31, 2007
Creator: LaFreniere, L. M.
Object Type: Report
System: The UNT Digital Library
LISSAT Analysis of a Generic Centrifuge Enrichment Plant (open access)

LISSAT Analysis of a Generic Centrifuge Enrichment Plant

The U.S. Department of Energy (DOE) is interested in developing tools and methods for use in designing and evaluating safeguards systems for current and future plants in the nuclear power fuel cycle. The DOE is engaging several DOE National Laboratories in efforts applied to safeguards for chemical conversion plants and gaseous centrifuge enrichment plants. As part of the development, Lawrence Livermore National Laboratory has developed an integrated safeguards system analysis tool (LISSAT). This tool provides modeling and analysis of facility and safeguards operations, generation of diversion paths, and evaluation of safeguards system effectiveness. The constituent elements of diversion scenarios, including material extraction and concealment measures, are structured using directed graphs (digraphs) and fault trees. Statistical analysis evaluates the effectiveness of measurement verification plans and randomly timed inspections. Time domain simulations analyze significant scenarios, especially those involving alternate time ordering of events or issues of timeliness. Such simulations can provide additional information to the fault tree analysis and can help identify the range of normal operations and, by extension, identify additional plant operational signatures of diversions. LISSAT analyses can be used to compare the diversion-detection probabilities for individual safeguards technologies and to inform overall strategy implementations for present and future plants. …
Date: May 31, 2007
Creator: Lambert, H; Elayat, H A; O?Connell, W J; Szytel, L & Dreicer, M
Object Type: Article
System: The UNT Digital Library
SASSE MODELING OF A URANIUM MOLYBDENUM SEPARATION FLOWSHEET (open access)

SASSE MODELING OF A URANIUM MOLYBDENUM SEPARATION FLOWSHEET

H-Canyon Engineering (HCE) is evaluating the feasibility of processing material from the Super Kukla Prompt Burst Reactor, which operated at the Nevada Test Site from 1964 to 1978. This material is comprised of 90 wt % uranium (U) (at approximately 20% 235U enrichment) alloyed with 10 wt % molybdenum (Mo). The objective is to dissolve the material in nitric acid (HNO{sub 3}) in the H-Canyon dissolvers and then to process the dissolved material through H-Canyon First and Second Cycle solvent extraction. The U product from Second Cycle will be sent to the highly enriched uranium (HEU) blend down program. In the blend down program, enriched U from the 1EU product stream will be blended with natural U at a ratio of 1 part enriched U per 3.5 parts natural U to meet a reactor fuel specification of 4.95% 235U before being shipped for use by the Tennessee Valley Authority (TVA) in its nuclear plants. The TVA specification calls for <200 mg Mo/g U (200 ppm). Since natural U has about 10 mg Mo/g U, the required purity of the 1EU product prior to blending is about 800 mg Mo/g U, allowing for uncertainties. HCE requested that the Savannah River National …
Date: May 31, 2007
Creator: Laurinat, J
Object Type: Report
System: The UNT Digital Library
Material-based Stratification (open access)

Material-based Stratification

A simple probability model was applied to detection sampling in a room or space in which different surface materials are present. The model assesses the overall detection capability when the sampling and analytical methods have different performance properties for the different materials. The results suggest that some common sampling strategies may not be ideal. In particular: (1) In a single room or area that includes different surface types with different detection properties, do not use a single sampling grid with a common spacing throughout. (2) If it is known or strongly suspected that one material has better detection properties than the other, place all samples on that material. (3) When it is completely unknown which material has the better detection properties, allocate the samples equally between them.
Date: May 31, 2007
Creator: MacQueen, D H
Object Type: Report
System: The UNT Digital Library