Effects of ionizing radiation on selected optical materials: An overview (open access)

Effects of ionizing radiation on selected optical materials: An overview

This report gives an overview of the effects of ionizing radiation on optical materials that may be used in spacecraft sensors. It introduces the relevant phenomena and indicates were more detailed information can be found. The topics covered include radiation induced absorption in ultraviolet transmitting materials, ordinary optical glasses, cerium stabilized optical glasses, and infrared transmitting materials; bleaching and annealing, and radioluminesence.
Date: July 30, 1992
Creator: Wirtenson, G. R. & White, R. H.
Object Type: Report
System: The UNT Digital Library
Adaptive Superplastic Forming Using NIKE2D with ISLAND (open access)

Adaptive Superplastic Forming Using NIKE2D with ISLAND

Superplastic forming has emerged as an important manufacturing process for producing near-net-shape parts. The design of a superplastic forming process is more difficult than conventional manufacturing operations, and is less amenable to trial and error approaches. This paper describes a superplastic forming process design capability incorporating nonlinear finite element analysis. The material constraints to allow superplastic behavior are integrated into an external constraint equation which is solved concurrently with the nonlinear finite element equations. The implementation of this approach using the ISLAND solution control language with the nonlinear finite element code NIKE2D is discussed in detail. Superplastic forming process design problems with one and two control parameters are presented as examples.
Date: July 30, 1992
Creator: Engelmann, Bruce E.; Whirley, Robert G. & Raboin, Peter J.
Object Type: Article
System: The UNT Digital Library
Large spatial, temporal, and algorithmic adaptivity for implicit nonlinear finite element analysis (open access)

Large spatial, temporal, and algorithmic adaptivity for implicit nonlinear finite element analysis

The development of effective solution strategies to solve the global nonlinear equations which arise in implicit finite element analysis has been the subject of much research in recent years. Robust algorithms are needed to handle the complex nonlinearities that arise in many implicit finite element applications such as metalforming process simulation. The authors experience indicates that robustness can best be achieved through adaptive solution strategies. In the course of their research, this adaptivity and flexibility has been refined into a production tool through the development of a solution control language called ISLAND. This paper discusses aspects of adaptive solution strategies including iterative procedures to solve the global equations and remeshing techniques to extend the domain of Lagrangian methods. Examples using the newly developed ISLAND language are presented to illustrate the advantages of embedding temporal, algorithmic, and spatial adaptivity in a modem implicit nonlinear finite element analysis code.
Date: July 30, 1992
Creator: Engelmann, B. E. & Whirley, R. G.
Object Type: Article
System: The UNT Digital Library
Preliminary minimum detectable limit measurements in 208-L drums for selected actinide isotopes in mock-waste matrices (open access)

Preliminary minimum detectable limit measurements in 208-L drums for selected actinide isotopes in mock-waste matrices

Preliminary minimum detectable levels (MDLS) of selected actinide isotopes have been determined in full-scale, 55-gallon drums filled with a range of mock-waste materials from combustibles (0.14 g/CM{sup 3}) to sand (1.7 g/CM{sup 3}). Measurements were recorded from 100 to 10,000 seconds with selected actinide sources located in these drums at an edge position, on the center axis of a drum and midway between these two positions. Measurements were also made with a {sup 166}Ho source to evaluate the attenuation of these mock-matrix materials as a function of energy. By knowing where the source activity is located within a drum, our preliminary results show that a simply collimated 90% HPGE detector can differentiate between TRU (>100 nCi/g) and LLW amounts of {sup 239}Pu in only 100s of measurement time and with sufficient accuracy in both low and medium density, low Z materials. Other actinides measured so far include {sup 235}U, {sup 241}Am, and {sup 244}Cm. These measurements begin to establish the probable MDLs achievable in the nondestructive assays of real waste drums when using active and passive CT. How future measurements may differ from these preliminary measurements is also discussed.
Date: July 30, 1992
Creator: Camp, D. C.; Wang, Tzu-Fang & Martz, H. E.
Object Type: Article
System: The UNT Digital Library
Spectroscopic studies of the 110{degree}C thermal aging of PETN (open access)

Spectroscopic studies of the 110{degree}C thermal aging of PETN

The 110{degrees}C thermal aging parameters, including initial rates of decomposition, of four types of pentaerythritol tetranitrate (PETN) over a period of ten months are presented. Both decomposition products nitric oxide, NO, and nitrogen dioxide, N0{sub 2} were monitored from multiple, hermetically-sealed, in vacuo samples. Nitric oxide appears to be the first nitrogen oxide product evolved. Nitrogen dioxide produced by abrupt thermal aging is more slowly converted to nitric oxide by a 1:1 process. The behavior of samples of RR5K PETN was significantly different from that of other powders studied. Further work is in progress to better define the thermal aging of RR5K PETN.
Date: July 30, 1992
Creator: Dosser, L. R. & Seliskar, C. J.
Object Type: Report
System: The UNT Digital Library
Design of a high activity and selectivity alcohol catalyst (open access)

Design of a high activity and selectivity alcohol catalyst

In methanol dehydration by K-doped Rh-Mo/[gamma]-Al[sub 2]O[sub 3], while higher K levels reduced the dehydration propensity of the surface, at higher levels the potassium oxide layer formed after doping and calcining the surface interferes detrimentally with the Rh-Mo active metallic sites. Silica- and alumina-supported catalysts with 0.5% Rh loading were synthesized and tested for hydrogenation of CO.
Date: July 30, 1992
Creator: Foley, Henry C. & Mills, G. Alex
Object Type: Report
System: The UNT Digital Library
Design of a high activity and selectivity alcohol catalyst. Eighth quarterly report, May 7, 1992--August 7, 1992 (open access)

Design of a high activity and selectivity alcohol catalyst. Eighth quarterly report, May 7, 1992--August 7, 1992

In methanol dehydration by K-doped Rh-Mo/{gamma}-Al{sub 2}O{sub 3}, while higher K levels reduced the dehydration propensity of the surface, at higher levels the potassium oxide layer formed after doping and calcining the surface interferes detrimentally with the Rh-Mo active metallic sites. Silica- and alumina-supported catalysts with 0.5% Rh loading were synthesized and tested for hydrogenation of CO.
Date: July 30, 1992
Creator: Foley, H. C. & Mills, G. A.
Object Type: Report
System: The UNT Digital Library
Commercial Relations with Russia: Prospects for a Common United States-Japanese Policy (open access)

Commercial Relations with Russia: Prospects for a Common United States-Japanese Policy

Discussions in Japan in May 1992 related to potential agreements at the September 1992 Russian-Japanese summit were keyed to the central question, Will the barriers to significant commercial cooperation involving Russia, Japan and the United States in Russian Siberia be removed? [1] From these discussions among key Japanese industrialists, bankers, government officials and academics who influence policy, came a tentative "yes", if four conditions are met. A positive outcome would thus seem more likely than at any previous time. Such an outcome would likely promote profitable trade and investment, creating jobs in U.S. enterprises and serve as a vehicle for mutually beneficial U.S.-Japanese cooperation.
Date: July 30, 1992
Creator: Hardt, John P.
Object Type: Report
System: The UNT Digital Library