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811 Matching Results

Start Over Decade 2000-2009 Year 2000 Day 26th

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Results: 1 - 24 of 811 next

(open access)

Frequency Doubling Broadband Light in Multiple Crystals

The authors compare frequency doubling of broadband light in a single nonlinear crystal with doubling in five crystals with intercrystal temporal walk off compensation, and with doubling in five crystals adjusted for offset phase matching frequencies. Using a plane-wave, dispersive numerical model of frequency doubling they study the bandwidth of the second harmonic and the conversion efficiency as functions of crystal length and fundamental irradiance. For low irradiance the offset phase matching arrangement has lower efficiency than a single crystal of the same total length but gives a broader second harmonic bandwidth. The walk off compensated arrangement gives both higher conversion efficiency and broader bandwidth than a single crystal. At high irradiance, both multicrystal arrangements improve on the single crystal efficiency while maintaining broad bandwidth.

Date: July 26, 2000

Creator: ALFORD,WILLIAM J. & SMITH,ARLEE V.

Object Type: Article

System: The UNT Digital Library

(open access)

Thermal Decomposition of Radiation-Damaged Polystyrene

The radiation-damaged polystyrene (given the identification name of 'polycube') was fabricated by mixing high-density polystyrene material ("Dylene Fines # 100") with plutonium and uranium oxides. The polycubes were used in the 1960s for criticality studies during processing of spent nuclear fuel. The polycubes have since been stored for almost 40 years at the Hanford Plutonium Finishing Plant (PFP) after failure of two processes to reclaim the plutonium and uranium oxides from the polystyrene matrix. Thermal decomposition products from this highly cross-linked polystyrene matrix were characterized using Gas Chromatograph/Mass Spectroscopy (GC/MS) system coupled to a horizontal furnace. The decomposition studies were performed in air and helium atmospheres at about 773 K. The volatile and semi-volatile organic products for the radiation-damaged polystyrene were different compared to virgin polystyrene. The differences were in the number of organic species generated and their concentrations. In the inert (i.e., helium) atmosphere, the major volatile organic products identified (in order of decreasing concentrations) were styrene, benzene, toluene, ethylbenzene, xylene, nathphalene, propane, .alpha.-methylbenzene, indene and 1,2,3-trimethylbenzene. But in air, the major volatile organic species identified changed slightly. Concentrations of the organic species in the inert atmosphere were significantly higher than those for the air atmosphere processing. Overall, 38 …

Date: September 26, 2000

Creator: Abrefah, John & Klinger, George S.

Object Type: Report

System: The UNT Digital Library

(open access)

EARLY ENTRANCE COPRODUCTION PLANT

The overall objective of this project is the three phase development of an Early Entrance Coproduction Plant (EECP) which produces at least one product from at least two of the following three categories: (1) electric power (or heat), (2) fuels, and (3) chemicals. The objective is to have these products produced by technologies capable of using synthesis gas derived from coal and/or other carbonaceous feedstock. The objective of Phase I is to determine the feasibility and define the concept for the EECP located at a specific site and to develop a Research, Development, and Testing Plan (RD and T) for implementation in Phase II. The objective of Phase II is to implement the RD and T as outlined in the Phase I RD and T Plan to enhance the development and commercial acceptance of coproduction technology that produces high-value products, particularly those that are critical to our domestic fuel and power requirements. The project will resolve critical knowledge and technology gaps on the integration of gasification and downstream processing to coproduce some combination of power, fuels, and chemicals from coal and other feedstocks. The objective of Phase III is to develop an engineering design package and a financing plan for …

Date: October 26, 2000

Creator: Abughazaleh, John S.; Ahmed, Mushtaq; Anand, Ashok; Anderson, John H.; Benham, Charles; Brent, Fred D. et al.

Object Type: Report

System: The UNT Digital Library

(open access)

Mechanical design and analysis of the Fermilab 11 T Nb{sub 3}Sn dipole model

The goal of the Fermilab High Field Magnet (HFM) R and D project is to explore various designs and production technology of a high-field, low-cost Nb{sub 3}Sn accelerator magnet suitable for a future Very Large Hadron Collider (VLHC). The model under fabrication consists of two-layer shell-type coil with 43.5 mm aperture and cold iron yoke. Fermilab concept of magnet design and fabrication technology involves some specific features such as curing of half-coil with ceramic binder/matrix before reaction, and then simultaneous reaction and impregnation of both half-coils to get a coil pipe structure. The coil pipe is mechanically supported by the vertically-split iron yoke locked by two aluminum clamps and a thick stainless steel skin. 2D finite element analysis has been performed to study and optimize the prestress in the coil and in the structural elements at room temperature and at 4.2 K. Model description, material properties and the results of mechanical analysis are reported in this paper.

Date: January 26, 2000

Creator: Ambrosio, G.

Object Type: Article

System: The UNT Digital Library

(open access)

Study of the react and wind technique for a Nb{sub 3}Sn common coil dipole

Fermilab, in collaboration with LBNL, is exploring the use of the react and wind technique for a common coil dipole with a Nb{sub 3}Sn Rutherford cable. An R and D program on conductor design and magnet technology was begun aiming at an 11 T, 2 layer, 30 mm aperture design operating at 4.5 K. The goal is to explore the feasibility of the react and wind technique for flat coils with a minimum bending radius of 90 mm. In order to improve the understanding of the I{sub c} degradation caused by bending after reaction this effect will be studied on both strands and cables. In this paper, the authors present two techniques to measure the critical current degradation due to bending, both in wires and cables, using standard test facilities. Together with the description of the program they show the results of the first measurements on strands and the layout of the cables that are being produced.

Date: January 26, 2000

Creator: Ambrosio, G.

Object Type: Article

System: The UNT Digital Library

(open access)

Staggered grid lagrangian method with local structured adaptive mesh refinement for modeling shock hydrodynamics

A new method for the solution of the unsteady Euler equations has been developed. The method combines staggered grid Lagrangian techniques with structured local adaptive mesh refinement (AMR). This method is a precursor to a more general adaptive arbitrary Lagrangian Eulerian (ALE-AMR) algorithm under development, which will facilitate the solution of problems currently at and beyond the boundary of soluble problems by traditional ALE methods by focusing computational resources where they are required. Many of the core issues involved in the development of the ALE-AMR method hinge upon the integration of AMR with a Lagrange step, which is the focus of the work described here. The novel components of the method are mainly driven by the need to reconcile traditional AMR techniques, which are typically employed on stationary meshes with cell-centered quantities, with the staggered grids and grid motion employed by Lagrangian methods. These new algorithmic components are first developed in one dimension and are then generalized to two dimensions. Solutions of several model problems involving shock hydrodynamics are presented and discussed.

Date: September 26, 2000

Creator: Anderson, R W; Pember, R B & Elliot, N S

Object Type: Article

System: The UNT Digital Library

(open access)

Post-remediation biomonitoring of pesticides and other contaminants in marine waters and sediment near the United Heckathorn Superfund Site, Richmond, California

Marine sediment remediation at the United Heckathorn Superfund Site was completed in April 1997. Water and mussel tissues were sampled in February 1999 from four stations near Lauritzen Canal in Richmond, California, for Year 2 of post-remediation monitoring of marine areas near the United Heckathorn Site. Dieldrin and dichlorodiphenyl trichloroethane (DDT) were analyzed in water samples, tissue samples from resident mussels, and tissue samples from transplanted mussels deployed for 4 months. Concentrations of dieldrin and total DDT in water and total DDT in tissue were compared with Year 1 of post-remediation monitoring, and with preremediation data from the California State Mussel Watch program (tissues) and the Ecological Risk Assessment for the United Heckathorn Superfund Site (tissues and water). Mussel tissues were also analyzed for polychlorinated biphenyls (PCB), which were detected in sediment samples. Chlorinated pesticide concentrations in water samples were similar to preremediation levels and did not meet remediation goals. Mean dieidrin concentrations in water ranged from 0.62 rig/L to 12.5 ng/L and were higher than the remediation goal (0.14 ng/L) at all stations. Mean total DDT concentrations in water ranged from 14.4 ng/L to 62.3 ng/L and exceeded the remediation goal (0.59 ng/L) at all stations. The highest concentrations …

Date: May 26, 2000

Creator: Antrim, LD & Kohn, NP

Object Type: Report

System: The UNT Digital Library

(open access)

Post-Remediation Biomonitoring of Pesticides and Other Contaminants in Marine Waters and Sediment Near the United Heckathorn Superfund Site, Richmond, California

Date: May 26, 2000

Creator: Antrim, Lyle D. & Kohn, Nancy P.

Object Type: Report

System: The UNT Digital Library