Optimal design of gas adsorption refrigerators for cryogenic cooling

The design of gas adsorption refrigerators used for cryogenic cooling in the temperature range of 4K to 120K was examined. The functional relationships among the power requirement for the refrigerator, the system mass, the cycle time and the operating conditions were derived. It was found that the precool temperature, the temperature dependent heat capacities and thermal conductivities, and pressure and temperature variations in the compressors have important impacts on the cooling performance. Optimal designs based on a minimum power criterion were performed for four different gas adsorption refrigerators and a multistage system. It is concluded that the estimates of the power required and the system mass are within manageable limits in various spacecraft environments

COSMIC/NASTRAN Free-field Input

A user's guide to the COSMIC/NASTRAN free field input for the Bulk Data section of the NASTRAN program is proposed. The free field input is designed to be user friendly and the user is not forced out of the computer system due to input errors. It is easy to use, with only a few simple rules to follow. A stand alone version of the COSMIC/NASTRAN free field input is also available. The use of free field input is illustrated by a number of examples

Transitions from AFDC to SSI Prior to Welfare Reform – Policy Brief

The Supplemental Security Income (SSI) and Temporary Assistance for Needy Families (TANF) programs serve overlapping target groups. SSI serves adults and children with disabilities from low-income families, while TANF serves low-income families with children. Consequently, policy changes in one program can affect the other. The target group for Aid to Families with Dependent Children (AFDC), TANF’s predecessor, also overlapped with SSI’s target group. Many have anticipated that the replacement of AFDC with TANF in August 1996 would eventually increase SSI participation as TANF recipients with disabilities sought SSI benefits to avoid TANF work requirements and time limits

Impacts of Expanding Health Care Coverage on the Employment and Earnings of Participants in the SSI Work Incentive Program - Policy Brief

While people with disabilities often say that a loss of public health insurance is a deterrent to work, it is rare to find situations in which they might actually exhibit such a behavioral response to a change in access. Expansions in the income threshold for SSI work incentives program (Sections 1619(a) and (b)) provide an opportunity to observe such a response. Section 1619(b) allows SSI recipients to maintain Medicaid eligibility even if their income is above the level that makes them ineligible for SSI payments. If earnings increase beyond the 1619(b) threshold, however, the person loses their SSI and Medicaid eligibility. Section 1619(b) income thresholds vary significantly across states and over time. Stapleton and Tucker (2000) use the variation in Section 1619(b) income thresholds to examine the employment, earnings and program participation patterns of SSI recipients who have incomes near the threshold level for their state. They find strong evidence that many SSI recipients restrain their earnings to stay below the 1619(b) threshold. It is important to note, however, that the findings only provide evidence on the behavior of a small portion of the population with disabilities (i.e., SSI recipients who work). Nonetheless, this evidence seems to provide strong empirical support for the hypothesis that lack of access to health insurance is an important work disincentive for people with disabilities. They also find that 1619(b) participation varies significantly from month to month. Consequently, cross-sectional estimates on the share of SSI recipients participating in 1619(b) significantly understate the share of SSI recipients who ever participate. These findings are consistent with previous findings that cross-sectional estimates of employment tend to understate multi-period employment patterns for the broader population with disabilities