35 Matching Results

Search Results

Results: 1 - 24 next
open access

Adaptive Remote-Sensing Techniques Implementing Swarms of Mobile Agents

Description: In many situations, stand-off remote-sensing and hazard-interdiction techniques over realistic operational areas are often impractical "and difficult to characterize. An alternative approach is to implement an adap- tively deployable array of sensitive agent-specific devices. Our group has been studying the collective be- havior of an autonomous, multi-agent system applied to chedbio detection and related emerging threat applications, The current physics-based models we are using coordinate a s… more
Date: November 25, 1998
Creator: Asher, R. B.; Cameron, S. M.; Loubriel, G. M.; Robinett, R. D.; Stantz, K. M.; Trahan, M. W. et al.
Partner: UNT Libraries Government Documents Department
open access

Design and construction of a pipeline for transfer of radioactive sodium at Argonne National Laboratory-West.

Description: Experimental Breeder Reactor-II (EBR-II), an experimental sodium cooled fast breeder reactor located at Argonne National Laboratory-West (ANL-W), was shut down in 1994, and has since been defueled in preparation for final plant closure. Approximately 100,000 gallons of liquid sodium is contained in the primary and secondary cooling systems of the EBR-II plant. The liquid sodium must be drained from the reactor systems during closure of the plant to place the reactor plant in an industrially and… more
Date: February 25, 1998
Creator: Baily, C. E.
Partner: UNT Libraries Government Documents Department
open access

Recent advances in fabrication of high-T{sub c} superconductors for electric power applications.

Description: The U.S. Department of Energy (DOE) supports an applied superconductivity program entitled ''Superconductivity Program for Electric Power Systems.'' Activities within this program contribute to development of the high-temperature superconductor (HTS) technology needed for industry to proceed with the commercial development of electric power applications such as motors, generators, transformers, transmission cables, and current limiters. Research is conducted in three categories: wire developmen… more
Date: March 25, 1998
Creator: Balachandran, U.
Partner: UNT Libraries Government Documents Department
open access

Atomistic simulations for multiscale modeling in bcc metal

Description: Quantum-based atomistic simulations are being used to study fundamental deformation and defect properties relevant to the multiscale modeling of plasticity in bcc metals at both ambient and extreme conditions. Ab initio electronic-structure calculations on the elastic and ideal-strength properties of Ta and Mo help constrain and validate many-body interatomic potentials used to study grain boundaries and dislocations. The predicted C(capital Sigma)5 (310)[100] grain boundary structure for Mo ha… more
Date: September 25, 1998
Creator: Belak, J.; Moriarty, J.A.; Soderlind, P.; Xu, W.; Yang, L.H. & Zhu
Partner: UNT Libraries Government Documents Department
open access

Impact of mental representational systems on design interface.

Description: The purpose of the studies conducted at Argonne National Laboratory is to understand the impact mental representational systems have in identifying how user comfort parameters influence how information is to best be presented. By understanding how each individual perceives information based on the three representational systems (visual, auditory and kinesthetic modalities), it has been found that a different approach must be taken in the design of interfaces resulting in an outcome that is much… more
Date: February 25, 1998
Creator: Brown-VanHoozer, S. A.
Partner: UNT Libraries Government Documents Department
open access

Towards a Standard for Highly Secure SCADA Systems

Description: The critical energy inkstructures include gas, OL and electric power. These Mrastructures are complex and interdependent nmvorks that are vital to the national secwiy and social well being of our nation. Many electric power systems depend upon gas and oil, while fossil energy delive~ systems depend upon elecnic power. The control mechanisms for these Mrastructures are often referred to as SCADA (Supmivry CkmdandDaU Ac@itz&z) systems. SCADA systems provide remote monitoring and centralized contr… more
Date: September 25, 1998
Creator: Carlson, R.
Partner: UNT Libraries Government Documents Department
open access

Current profile modeling to extend the duration of high performance advanced Tokamak modes in DIII-D

Description: We use a model for negative central shear (NCS) heat transport which has a parametric dependence on the plasma conditions with a transport barrier dependence on the minimum of the safety factor profile, 4, qualitatively consistant with experimental observations. Our intention is not to do a detailed investigation of transport models but rather to provide a reasonable model of heat conductivity to be able to simulate effects of electron cyclotron heating (ECH) and current drive (ECCD) on confine… more
Date: June 25, 1998
Creator: Casper, T. A.
Partner: UNT Libraries Government Documents Department
open access

Collaboratory for support of scientific research

Description: Collaboration is an increasingly important aspect of magnetic fusion energy research. With the increased size and cost of experiments needed to approach reactor conditions, the numbers being constructed has become limited. In order to satisfy the desire for many groups to conduct research on these facilities, we have come to rely more heavily on collaborations. Fortunately, at the same time, development of high performance computers and fast and reliable wide area networks has provided technolo… more
Date: June 25, 1998
Creator: Casper, T. A.; Meyer, W. H. & Moller, J. M.
Partner: UNT Libraries Government Documents Department
open access

Molybdenum disilicide composites produced by plasma spraying

Description: The intermetallic compound, molybdenum disilicide (MoSi{sub 2}) is being considered for high temperature structural applications because of its high melting point and superior oxidation resistance at elevated temperatures. The lack of high temperature strength, creep resistance and low temperature ductility has hindered its progress for structural applications. Plasma spraying of coatings and structural components of MoSi{sub 2}-based composites offers an exciting processing alternative to conv… more
Date: May 25, 1998
Creator: Castro, R. G.; Hollis, K. J.; Kung, H. H. & Bartlett, A. H.
Partner: UNT Libraries Government Documents Department
open access

A numerical investigation of the scale-up effects on flow, heat transfer, and kinetics processes of FCC units.

Description: Fluid Catalytic Cracking (FCC) technology is the most important process used by the refinery industry to convert crude oil to valuable lighter products such as gasoline. Process development is generally very time consuming especially when a small pilot unit is being scaled-up to a large commercial unit because of the lack of information to aide in the design of scaled-up units. Such information can now be obtained by analysis based on the pilot scale measurements and computer simulation that in… more
Date: August 25, 1998
Creator: Chang, S. L.
Partner: UNT Libraries Government Documents Department
open access

A numerical study of short residence time FCC riser flows with a new flow/kinetics modeling technique.

Description: Fluid Catalytic Cracking (FCC) technology is the most important process used by the refinery industry to convert crude oil to valuable lighter products such as gasoline. New and modified processes are constantly developed by refinery companies to improve their global competitiveness and meet more stringent environmental regulations. Short residence time FCC riser reactor is one of the advanced processes that the refining industry is actively pursuing because it can improve the yield selectivity… more
Date: August 25, 1998
Creator: Chang, S. L.
Partner: UNT Libraries Government Documents Department
open access

Rigorous method for compensation selection and alignment of microlithographic optical systems

Description: The assembly of an optical system requires the correction of aberrations in the entire imaging field by making selected rigid-body motions of the optical elements. We present a rigorous method for determining which adjustment motions, called compensators, to use for alignment. These compensators are found by employing techniques from linear algebra that choose the most independent vectors from a set which are interdependent. The method finds the smallest number of compensators to correct for mi… more
Date: March 25, 1998
Creator: Chapman, H.N. & Sweeney, D.W.
Partner: UNT Libraries Government Documents Department
open access

High charge short electron bunches for wakefield accelerator structures development.

Description: The Argonne Wakefield Accelerator group develops accelerating structures based on dielectric loaded waveguides. We use high charge short electron bunches to excite wakefields in dielectric loaded structures, and a second (low charge) beam to probe the wakefields left behind by the drive beam. We report measurements of beam parameters and also initial results of the dielectric loaded accelerating structures. We have studied acceleration of the probe beam in these structures and we have also made… more
Date: September 25, 1998
Creator: Conde, M. E.
Partner: UNT Libraries Government Documents Department
open access

Resonant excitation of plasma wakefields using multiple electron bunches.

Description: We plan to resonantly excite plasma wakefields using a train of electron bunches separated by an-integer number of plasma wavelengths. The multiple electron bunches are generated by a photocathode based RF gun by splitting the laser beam into temporally separated pulses. The amplitude of the wakefields generated by the sequence of bunches is expected to be higher than that generated if all charge had been in only one bunch, because this single bunch would be considerably longer than the individ… more
Date: September 25, 1998
Creator: Conde, M. E.
Partner: UNT Libraries Government Documents Department
open access

Laser system for a subpicosecond electron linac.

Description: At the Argonne Chemistry Division efforts are underway to develop a sub-picosecond electron beam pulse radiolysis facility for chemical studies. The target output of the accelerator is to generate electron pulses that can be adjusted from 3nC in .6ps to 100nC in 45ps. In conjunction with development of the accelerator a state-of-the-art ultrafast laser system is under construction that will drive the linac's photocathode and provide probe pulses that are tunable from the UV to IR spectral regio… more
Date: September 25, 1998
Creator: Crowell, R. A.
Partner: UNT Libraries Government Documents Department
open access

Fatigue and fracture of fiber composites under combined interlaminar stresses

Description: As part of efforts to develop a three-dimensional failure model for composites, a study of failure and fatigue due to combined interlaminar stresses was conducted. The combined stresses were generated using a hollow cylindrical specimen, which was subjected to normal compression and torsion. For both glass and carbon fiber composites, normal compression resulted in a significant enhancement in the interlaminar shear stress and strain at failure. Under moderate compression levels, the failure mo… more
Date: June 25, 1998
Creator: DeTeresa, S J; Freeman, D C & Groves, S E
Partner: UNT Libraries Government Documents Department
open access

PNC in hydrogen. different prospects using heliumlike ions.

Description: The motivation for parity experiments in simple atomic systems is that the atomic physics is known precisely so they directly test the weak interactions. We review the status of the parity experiments that have been done in atomic hydrogen and suggest some possibilities for experiments in helium like ions.
Date: September 25, 1998
Creator: Dunford, R. W.
Partner: UNT Libraries Government Documents Department
open access

Perforation of HY-100 steel plates with 4340 R{sub c} 38 and T-250 maraging steel rod projectiles

Description: The authors conducted perforation experiments with 4340 Rc 38 and T-250 maraging steel, long rod projectiles and HY-100 steel target plates at striking velocities between 80 and 370 m/s. Flat-end rod projectiles with lengths of 89 and 282 mm were machined to nominally 30-mm-diameter so they could be launched from a 30-mm-powder gun without sabots. The target plates were rigidly clamped at a 305-mm-diameter and had nominal thicknesses of 5.3 and 10.5 mm. Four sets of experiments were conducted t… more
Date: May 25, 1998
Creator: Forrestal, M.J. & Hanchak, S.J.
Partner: UNT Libraries Government Documents Department
open access

High-spin states in {sup 71}As, {sup 72}Se, and {sup 72}Br.

Description: The {sup 16}O + {sup 58}Ni reaction was used to study yrast and non-yrast excitations in {sup 71}As, {sup 72}Se, and {sup 72}Br. High-spin yrast and negative-parity non-yrast bands were observed in {sup 72}Se. The F{sub 7/2} proton extruder orbital was identified in {sup 71}As. The odd-even staggering in the {pi}g{sub 9/2}{nu}g{sub 9/2} decoupled band in {sup 72}Br is compared with similar structures in heavier Br isotopes.
Date: August 25, 1998
Creator: Fotiades, N.
Partner: UNT Libraries Government Documents Department
open access

Assessment of Cracks in Stress Concentration Regions with Localized Plastic Zones

Description: Marty brittle fracture evaluation procedures include plasticity corrections to elastically computed stress intensity factors. These corrections, which are based on the existence of a plastic zone in the vicinity of the crack tip, can overestimate the plasticity effect for a crack embedded in a stress concentration region in which the elastically computed stress exceeds the yield strength of the material in a localized zone. The interactions between the crack, which acts to relieve the high stre… more
Date: November 25, 1998
Creator: Friedman, E.
Partner: UNT Libraries Government Documents Department
open access

Frequency converter design and manufacturing considerations for the National Ignition Facility

Description: The National Ignition Facility (NIF), being constructed at Lawrence Livermore National Laboratory (LLNL), comprises 192 laser beams, Figure 1. The lasing medium is neodymium in phosphate glass with a fundamental frequency (1{omega}) of 1.053 {micro}m. Sum frequency generation in a pair of conversion crystals (KDP/KD*P) produces 1.8 Mj of the third harmonic light (3{omega} or {lambda}=0.35). On NIF the frequency conversion crystals are part of the Final Optics Assembly (FOA), whose two principal… more
Date: March 25, 1998
Creator: Hibbard, R. L.; English, R. E., Jr.; De Yoreo, J. J. & Montesanti, R. C.
Partner: UNT Libraries Government Documents Department
open access

Microprocessor Implementation of a Time Variant Floating Mean Counting Algorithm

Description: Rate estimation of nuclear pulses emitted from nuclear detectors has been well documented in papers written as early as 1965 to as recently as 1990. It is well known that pulses emitted from a nuclear detector can vary with time and an accurate estimate of the count rate must be based on a sifficient number of pulse counts within a sample period as well as the recent history of pulse counts acquired in previous windows to accurately estimate the current rate. This paper will review the attribut… more
Date: November 25, 1998
Creator: Huffman, R. K.
Partner: UNT Libraries Government Documents Department
open access

Determining Pu-239 content by resonance transmission analysis using a filtered reactor beam.

Description: A novel technique has been developed at Argonne National Laboratory to determine the {sup 239}Pu content in EBR-II blanket elements using resonance transmission analysis (RTA) with a filtered reactor beam. The technique uses cadmium and gadolinium filters along with a {sup 239}Pu fission chamber to isolate the 0.3 eV resonance in {sup 239}Pu. In the energy range from 0.1 to 0.5 eV, the total microscopic cross-section of {sup 239}Pu is significantly larger than the cross-sections of {sup 238}U a… more
Date: November 25, 1998
Creator: Klann, R. T.
Partner: UNT Libraries Government Documents Department
open access

Imprinting artificial magnetic structures.

Description: Recently we created La/Fe multilayers with a helical magnetic structure imprinted from the conditions of growth rather than by the magnetic interactions between layers. Each sublayer was 30{angstrom} thick, and during deposition the sample was rotated in an external field of 3 Oe. a field strong enough to magnetize the Fe layer being deposited but not sufficient to perturb the magnetization of the Fe layers already grown. As a result adjacent Fe layers formed a helical structure with a chiralit… more
Date: September 25, 1998
Creator: Lohstroh, W.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen