Estimation procedures to measure and monitor failure rates of components during thermal-vacuum testing

Estimation procedures are described for measuring component failure rates, for comparing the failure rates of two different groups of components, and for formulating confidence intervals for testing hypotheses (based on failure rates) that the two groups perform similarly or differently. Appendix A contains an example of an analysis in which these methods are applied to investigate the characteristics of two groups of spacecraft components. The estimation procedures are adaptable to system level testing and to monitoring failure characteristics in orbit

OSS-1/contamination monitor

A 20-cm high, 18-cm wide, and 30-cm long (8x7x12 inch) box weighing about 7 kg (15 lbs) and consuming about 7 watts of power was carried on the OSS-1 pallet to monitor the mass build-up or accretion of condensible, volatile materials on surfaces in the shuttle bay during all phases of ascent, on-orbit, and descent. Passively thermally controlled, the box holds two witness samples and four actively temperature controlled quartz crystal microbalances (TQCM) whose temperature can vary from -60 C to +80 C. Graphs show the accretion indicated by the TQCM during the launch and early orbital phase. Conditions during tail to the Sun, nose to the Sun, and bay to the Sun attitudes of the shuttle during STS-3 are reflected in temperatures indicated by the OSS-1 thermistor. These temperatures influence outgassing rates of various materials as well as measurements made by the contamination monitor package. The parameters that bear on TQCM measurements data are shown in graphs and discussed

A thermal vacuum test optimization procedure

An analytical model was developed that can be used to establish certain parameters of a thermal vacuum environmental test program based on an optimization of program costs. This model is in the form of a computer program that interacts with a user insofar as the input of certain parameters. The program provides the user a list of pertinent information regarding an optimized test program and graphs of some of the parameters. The model is a first attempt in this area and includes numerous simplifications. The model appears useful as a general guide and provides a way for extrapolating past performance to future missions

Evaluation of Disability Employment Policy Demonstration Programs

[Excerpt] Having characterized the intermediary approach from published literature, as well as impressions of those who are using this approach in their demonstration projects, and reviewed ODEP’s requirements regarding implementation of the intermediary approach, Westat determined that the intermediary approaches required in the SGAs for the State Intermediary and Faith-based Mentoring demonstration programs have much in common with other ODEP demonstration programs. Other ODEP programs require demonstration projects to partner and collaborate with businesses and business organizations, government, transportation systems, and health and other service providers. They also have goals for ensuring quality and impact and promoting policies to sustain effective practices. The difference, however, is that the State Intermediary and Faith-based mentoring SGAs specifically identified the intermediary approach as the strategy to use. The State Intermediary SGA went even further by delineating specific steps as part of the intermediary process (resource mapping and development of a state plan). Our literature review uncovered a wide variety of examples in which the intermediary approach has achieved useful outcomes on behalf of youth with disabilities. However, all literature we found was descriptive and did not address questions on effectiveness or the most appropriate strategies. Therefore, it is not known whether the intermediary approach is the most fruitful approach for achieving systems change, whether there are some intermediary approaches that are better than others, or whether those approaches would be repeatable and adaptable to other environments. Nevertheless, at our three site visits, we were able to uncover a variety of examples of activities that are consistent with intermediary strategic and operational functions identified in the literature and appear to bode well for success in achieving systems change. Further review of Quarterly Reports and findings from site visits also revealed some systems change already taking place in the systems change focus areas of capacity-building, coordination, consumer choice and employer support, and evaluation of new practices. Subsequent site visits in Phase IV of the independent evaluation are likely to uncover additional examples of intermediary processes, outputs, and outcomes, as well as those practices that appear to be most successful in achieving systems change

Role of Intermediaries in ODEP Youth Demonstration Programs

[Excerpt] All Office of Disability Employment Policy (ODEP) demonstration programs use aspects of an intermediary approach to connect organizations and agencies at all levels in meeting educational and employment goals on behalf of people with disabilities. As part of Phase III of the independent evaluation of ODEP demonstration programs, ODEP asked Westat to conduct an in-depth analysis of the role of intermediaries in building sustained capacity and integration of services of the workforce development system to better serve youth with disabilities. The overriding question in the context of this issue analysis is whether, to what extent, and how the intermediary approach is being used in youth demonstration programs and whether it is effective in creating systems change to better serve youth with disabilities. The following questions were addressed: - What characterizes the intermediary approach? - What are ODEP’s requirements with regard to the use of an intermediary approach by demonstration programs? - What are demonstration project sites’ experiences in using an intermediary approach? &#; What can be said to date on the effectiveness of using an intermediary approach, particularly with regard to systems change

Evaluation of waist-to-height ratio to predict 5 year cardiometabolic risk in sub-Saharan African adults

Simple, low-cost central obesity measures may help identify individuals with increased cardiometabolic disease risk, although it is unclear which measures perform best in African adults. We aimed to: 1) cross-sectionally compare the accuracy of existing waist-to-height ratio (WHtR) and waist circumference (WC) thresholds to identify individuals with hypertension, pre-diabetes, or dyslipidaemia; 2) identify optimal WC and WHtR thresholds to detect CVD risk in this African population; and 3) assess which measure best predicts 5-year CVD riskPeer reviewedFinal Accepted Versio

Kinetics of nitric oxide formation and decomposition

Experiments on shock wave structure were conducted in the 12 inch shock tube facility, and it is shown that this work was motivated by the need for improved kinetics for the modeling of NO production in space shuttle flow fields. The experiments on shock structure involved simultaneous observations of pressure and temperature on the wall of the shock tube during reflection of normal shock waves in inert gases

Experimental evaluation of high-thrust, throttleable, monopropellant hydrazine reactors

Throttleable monopropellant hydrazine catalytic reactors of a size applicable to a planetary landing vehicle were designed, fabricated, and tested. An experimental evaluation of two 2670-N reactor designs was conducted. The steady state and dynamic characteristics of the thruster/valve combinations were determined. The results of the testing, including the engine characteristic velocity, smoothness of combustion, insensitivity to heat sterilization, and response during various simulated duty cycles are presented and discussed. No problems of a fundamental nature were encountered as a result of rapid dynamic throttling of these large hydrazine reactors

A Comparison of Quartz Crystal Microbalance Measurements with Mass Spectrometer Determinations

An experimental program was undertaken in which mass accretion rates, as determined by a liquid nitrogen cooled quartz crystal microbalance, were compared with the mass flux rates, as determined by both a cycloidal type and a quadrupole type residual gas analyzer for five simple materials. The data indicate a high degree of correlation between these instruments insofar as the shape of the curves. There are large variations however among the absolute values