Dynamic information architecture system (DIAS) : multiple model simulation management. (open access)

Dynamic information architecture system (DIAS) : multiple model simulation management.

Dynamic Information Architecture System (DIAS) is a flexible, extensible, object-based framework for developing and maintaining complex multidisciplinary simulations of a wide variety of application contexts. The modeling domain of a specific DIAS-based simulation is determined by (1) software Entity (domain-specific) objects that represent the real-world entities that comprise the problem space (atmosphere, watershed, human), and (2) simulation models and other data processing applications that express the dynamic behaviors of the domain entities. In DIAS, models communicate only with Entity objects, never with each other. Each Entity object has a number of Parameter and Aspect (of behavior) objects associated with it. The Parameter objects contain the state properties of the Entity object. The Aspect objects represent the behaviors of the Entity object and how it interacts with other objects. DIAS extends the ''Object'' paradigm by abstraction of the object's dynamic behaviors, separating the ''WHAT'' from the ''HOW.'' DIAS object class definitions contain an abstract description of the various aspects of the object's behavior (the WHAT), but no implementation details (the HOW). Separate DIAS models/applications carry the implementation of object behaviors (the HOW). Any model deemed appropriate, including existing legacy-type models written in other languages, can drive entity object behavior. The DIAS …
Date: May 13, 2002
Creator: Simunich, K. L.; Sydelko, P.; Dolph, J. & Christiansen, J.
Object Type: Article
System: The UNT Digital Library
Source Release Modeling for the Idaho National Engineering and Environmental Laboratory's Subsurface Disposal Area (open access)

Source Release Modeling for the Idaho National Engineering and Environmental Laboratory's Subsurface Disposal Area

A source release model was developed to determine the release of contaminants into the shallow subsurface, as part of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) evaluation at the Idaho National Engineering and Environmental Laboratory's (INEEL) Subsurface Disposal Area (SDA). The output of the source release model is used as input to the subsurface transport and biotic uptake models. The model allowed separating the waste into areas that match the actual disposal units. This allows quantitative evaluation of the relative contribution to the total risk and allows evaluation of selective remediation of the disposal units within the SDA.
Date: May 13, 2002
Creator: Becker, B.H.
Object Type: Article
System: The UNT Digital Library
MONITORING POWER PLANT EFFICIENCY USING THE MICROWAVE-EXCITED PHOTOACOUSTIC EFFECT TO MEASURE UNBURNED CARBON (open access)

MONITORING POWER PLANT EFFICIENCY USING THE MICROWAVE-EXCITED PHOTOACOUSTIC EFFECT TO MEASURE UNBURNED CARBON

Three test instruments are being evaluated to determine the feasibility of using photo-acoustic technology for measuring unburned carbon in fly ash. The first test instrument is a single microwave frequency system previously constructed to measure photo-acoustic signals in an off-line configuration. This system was assembled and used to begin testing parameters thought to be influential in the resulting photo-acoustic signal output. A standard modulation frequency was chosen based upon signal to noise data gained from experimentation. Sample heterogeneity was tested and found not to be influential. Many other tests were performed during the second quarter. Preliminary results show that compression and photo-acoustic volume have an impact on photo-acoustic signal. Conclusions regarding the data for sample bulk density, temperature, humidity, moisture content, and linearity are pending further review. Conclusions for ambient temperature and humidity are pending further review as well. Simultaneously, a second instrument is to be constructed based in part on lessons learned with the first instrument, and to expand the capabilities of the first instrument. Improvements include a control loop to allow more constant microwave power output and an ability to operate over a range of microwave frequencies. To date, the design of the second instrument has been completed …
Date: May 13, 2002
Creator: Brown, Robert C.; Weber, Robert J. & Suby, Andrew A.
Object Type: Report
System: The UNT Digital Library
Defect Structure and Evolution in Silicon Carbide Irradiated to 1 dpa-SiC at 1100 C (open access)

Defect Structure and Evolution in Silicon Carbide Irradiated to 1 dpa-SiC at 1100 C

Transmission electron microscopy (TEM), swelling measurements, isochronal annealing, and thermal diffusivity testing were used to characterize the effects of radiation damage in SiC. Together, these techniques provided a comprehensive set of tools for observing and characterizing the structure and evolution of radiation-induced defects in SiC as a function of irradiation temperature and dose. In this study, two types of dense, crystalline, monolithic SiC were subjected to irradiation doses up to 1 dpa-SiC at a temperature of 1100 C, as well as post-irradiation annealing up to 1500 C. The microscopic defect structures observed by TEM were correlated to changes in the macroscopic dimensions, thermal diffusivity and thermal conductivity. The results demonstrated the value of using ultrapure {beta}SiC as an effective reference material to characterize the nature of expected radiation damage in other, more complex, SiC-based materials such as SiC/SiC composites.
Date: May 13, 2002
Creator: Senor, D. J.; Youngblood, G. E.; Greenwood, L. R.; Archer, D. V.; Alexander, D. L.; Chen, M. C. et al.
Object Type: Report
System: The UNT Digital Library
Characteristics of aqueous colloids generated by corrosion of metallic uranium fuel. (open access)

Characteristics of aqueous colloids generated by corrosion of metallic uranium fuel.

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Date: May 13, 2002
Creator: Fortner, J. A.; Mertz, C. J. & Seifert, S.
Object Type: Article
System: The UNT Digital Library
Greybull Sandstone Petroleum Potential on the Crow Indian Reservation, South-Central Montana (open access)

Greybull Sandstone Petroleum Potential on the Crow Indian Reservation, South-Central Montana

The focus of this project was to explore for stratigraphic traps that may be present in valley-fill sandstone at the top of the Lower Cretaceous Kootenai Formation. This sandstone interval, generally known as the Greybull Sandstone, has been identified along the western edge of the reservation and is a known oil and gas reservoir in the surrounding region. The Greybull Sandstone was chosen as the focus of this research because it is an excellent, well-documented, productive reservoir in adjacent areas, such as Elk Basin; Mosser Dome field, a few miles northwest of the reservation; and several other oil and gas fields in the northern portion of the Bighorn Basin.
Date: May 13, 2002
Creator: Lopez, David A.
Object Type: Report
System: The UNT Digital Library
Residual stress measurement in YBCO thin films. (open access)

Residual stress measurement in YBCO thin films.

Residual stress in YBCO films on Ag and Hastelloy C substrates was determined by using 3-D optical interferometry and laser scanning to measure the change in curvature radius before and after film deposition. The residual stress was obtained by appropriate analysis of curvature measurements. Consistent with residual thermal stress calculations based on the thermal expansion coefficient mismatch between the substrates and YBCO film, the measured residual stress in the YBCO film on Hastelloy C substrate was tensile, while it was compressive on the Ag substrate. The stress values measured by the two techniques were generally in good agreement, suggesting that optical interferometry and laser scanning have promise for measuring residual stresses in thin films.
Date: May 13, 2002
Creator: Cheon, J. H. & Singh, J. P.
Object Type: Article
System: The UNT Digital Library
Using Decision Analysis in Evaluation and Prioritization of Technologies for Long Term Stewardship (open access)

Using Decision Analysis in Evaluation and Prioritization of Technologies for Long Term Stewardship

The purpose of this paper is to describe a systematic approach to assess and prioritize technology concepts and systems for future research and development (R and D) funding. This paper discusses the analysis and rationale used in developing an evaluation process to assist those engaged in prioritizing technologies. This paper will explain the developed evaluation process, discuss the methodology, and summarize the rationale underlying the process.
Date: May 13, 2002
Creator: Nadeau, J. L.; Byers, J.; Harbour, J. L.; Hill, S.; Nickelson, R. A.; Richardson, J. G. et al.
Object Type: Article
System: The UNT Digital Library
Effects of an External Perturbation on a Cylindrical Spheromak (open access)

Effects of an External Perturbation on a Cylindrical Spheromak

In experiments like the spheromak, it becomes interesting to investigate the quality o f the magnetic flux surfaces in the device. One method of doing so is to impose an external perturbation. If the magnetic field without perturbation is tangled and no flux surfaces exist, then the perturbation will have little effect. However, if the field has well defined flux surfaces, the field should react strongly to a perturbation. Magnetic islands should form and potentially cause a degradation of the plasma This paper will assume the second case of good behavior and closed surfaces and will attempt to describe the effects of an external perturbation. Geometry-wise, we begin with the infinite cylinder approximation to a toroidally confined plasma. In the unperturbed state of this cylinder there are a toroidal field (axial field in the cylindrical geometry), a poloidal field and no radial field.
Date: May 13, 2002
Creator: Terry, M R
Object Type: Report
System: The UNT Digital Library
RESONANT X-RAY SCATTERING AS A PROBE OF ORBITAL AND CHARGE ORDERING. (open access)

RESONANT X-RAY SCATTERING AS A PROBE OF ORBITAL AND CHARGE ORDERING.

Resonant x-ray scattering is a powerful experimental technique for probing orbital and charge ordering. It involves tuning the incident photon energy to an absorption edge of the relevant ion and observing scattering at previously ''forbidden'' Bragg peaks, and it allows high-resolution, quantitative studies of orbital and charge order--even from small samples. Further, resonant x-ray scattering from orbitally ordered systems exhibits polarization- and azimuthal-dependent properties that provide additional information about the details of the orbital order that is difficult, or impossible, to obtain with any other technique. In the manganites, the sensitivity to charge and orbital ordering is enhanced when the incident photon energy is tuned near the Mn K absorption edge (6.539 keV), which is the lowest energy at which a 1s electron can be excited into an unoccupied state. In this process, the core electron is promoted to an intermediate excited state, which decays with the emission of a photon. The sensitivity to charge ordering is believed to be due to the small difference in K absorption edges of the Mn{sup 3+} and Mn{sup 4+} sites. For orbital ordering, the sensitivity arises from a splitting--or difference in the weight of the density of states [239]--of the orbitals occupied by …
Date: May 13, 2002
Creator: Nelson, C. S.; Hill, J. P. & Gibbs, D.
Object Type: Book
System: The UNT Digital Library