Positively Verifying Mating of Previously Unverifiable Flight Connectors

Current practice is to uniquely key the connectors, which, when mated, could not be verified by ground tests such as those used in explosive or non-explosive initiators and pyro valves. However, this practice does not assure 100-percent correct mating. This problem could be overcome by the following approach. Errors in mating of interchangeable connectors can result in degraded or failed space mission. Mating of all flight connectors considered not verifiable via ground tests can be verified electrically by the following approach. It requires two additional wires going through the connector of interest, a few resistors, and a voltage source. The test-point voltage V(sub tp) when the connector is not mated will be the same as the input voltage, which gets attenuated by the resistor R(sub 1) when the female (F) and male (M) connectors are mated correctly and properly. The voltage at the test point will be a function of R(sub 1) and R(sub 2). Monitoring of the test point could be done on ground support equipment (GSE) only, or it can be a telemetry point. For implementation on multiple connector pairs, a different value for R(sub 1) or R(sub 2) or both can be selected for each pair of connectors that would result in a unique test point voltage for each connector pair. Each test point voltage is unique, and correct test point voltage is read only when the correct pair is mated correctly together. Thus, this design approach can be used to verify positively the correct mating of the connector pairs. This design approach can be applied to any number of connectors on the flight vehicle

State-space average modelling of converters with parasitics and storage-time modulation

The State-Space Averaging approach to modelling switching converter power stages is used to extend the analytical descriptions of the buck, boost, buck-boost, and Cuk converters to included the effects of all parasitic resistances and transistor storage-time modulation. The analysis reveals for the first time a new and unexpected term in the line to ouput response of the Cuk converter. The new term contains a right half-plane zero produced by the energy transfer capacitance in combination with the duty-ratio-weighted sum of the on-resistances of the transistor and diode plus a non-dissipative ac resistance term due to transistor storage-time modulation. The conventional circuit model of the converter is modified to include the effects of the new term. The improved model permits an eas physical interpretation of the new zero, which has been observed only the in Cuk converter. An extended analysis of storage-time modulation in bipolar transistor switches shows that the ac small-signal performance of a switching converter is highly dependent on the nature of the base drive. It is demonstrated that storage-time modulation in conjunction with a proportional base drive can produce instability in switching converters, even open-loop. The results of these analyses are verified experimentally and their impacts on practical converters are discussed

The Chandrayaan-2 Large Area Soft X-ray Spectrometer (CLASS)

The CLASS experiment on Chandrayaan-2, the second Indian lunar mission, aims tomap the abundance of the major rock forming elements on the lunar surface using the technique of X-ray fluorescence during solar flare events. CLASS is a continuation of the successful C1XS [1] XRF experiment on Chandrayaan-1. CLASS is designed to provide lunar mapping of elemental abundances with a nominal spatial resolution of 25 km (FWHM) from a 200 km polar, circular orbit of Chandrayaan-2

Serum resistin is associated with C-reactive protein and LDL- cholesterol in type 2 diabetes and coronary artery disease in a Saudi population

Aims Resistin is an adipocyte-derived factor implicated in obesity-associated type 2 diabetes (T2DM). This study examines the association between human serum resistin, T2DM and coronary heart disease. Methods One hundred and fourteen Saudi Arabian patients (male: female ratio 46:68; age 51.4 (mean ± SD)11.7 years; median and range: 45.59 (11.7) years and BMI: 27.1 (mean ± SD) 8.1 Kgm2 median and range: 30.3 (6.3) were studied. Serum resistin and C-reactive protein (CRP), a marker of inflammation CRP levels, were measured in all subjects. (35 patients had type 2 diabetes mellitus (T2DM); 22 patients had coronary heart disease (CHD). Results Serum resistin levels were 1.2-fold higher in type 2 diabetes and 1.3-fold higher in CHD than in controls (p = 0.01). In addition, CRP was significantly increased in both T2DM and CHD patients (p = 0.007 and p = 0.002 respectively). The use of regression analysis also determined that serum resistin correlated with CRP levels (p = 0.04, R2 0.045). Conclusion The findings from this study further implicate resistin as a circulating protein associated with T2DM and CHD. In addition this study also demonstrates an association between resistin and CRP, a marker of inflammation in type 2 diabetic patients

Feature Selection of Post-Graduation Income of College Students in the United States

This study investigated the most important attributes of the 6-year post-graduation income of college graduates who used financial aid during their time at college in the United States. The latest data released by the United States Department of Education was used. Specifically, 1,429 cohorts of graduates from three years (2001, 2003, and 2005) were included in the data analysis. Three attribute selection methods, including filter methods, forward selection, and Genetic Algorithm, were applied to the attribute selection from 30 relevant attributes. Five groups of machine learning algorithms were applied to the dataset for classification using the best selected attribute subsets. Based on our findings, we discuss the role of neighborhood professional degree attainment, parental income, SAT scores, and family college education in post-graduation incomes and the implications for social stratification.Comment: 14 pages, 6 tables, 3 figure

Sensorization and intelligent systems in energetic sustainable environments

Sustainability is an important topic of discussion in our world. However, measuring sustainability and assessing behaviors is not always easy. Indeed, and in order to fulfill this goal, in this work it will be proposed a multi-agent based architecture to measure and assess sustainable indicators taken from a given environment. These evaluations will be based on past and present behaviors of the users and the particularities of the setting, leading to the evaluation of workable indicators such as gas emissions, energetic consumption and the users fitting with respect to the milieu. Special attention is given to user interaction and user attributes to calculate sustainable indicators for each type of structure, i.e., the aim of this scheme is to promote sustainability awareness and sustainable actions through the use of sustainable markers calculated in terms of the information gathered from the environment.The research presented is partially supported by a portuguese doctoral grant, SFRH/BD/78713/2011, issued by the Fundação da Ciência e Tecnologia (FCT) in Portugal

First-principles data for solid-solution strengthening of magnesium: From geometry and chemistry to properties

Solid-solution strengthening results from solutes impeding the glide of dislocations. Existing theories of strength rely on solute-dislocation interactions, but do not consider dislocation core structures, which need an accurate treatment of chemical bonding. Here, we focus on strengthening of Mg, the lightest of all structural metals and a promising replacement for heavier steel and aluminum alloys. Elasticity theory, which is commonly used to predict the requisite solute-dislocation interaction energetics, is replaced with quantum-mechanical first-principles calculations to construct a predictive mesoscale model for solute strengthening of Mg. Results for 29 different solutes are displayed in a "strengthening design map" as a function of solute misfits that quantify volumetric strain and slip effects. Our strengthening model is validated with available experimental data for several solutes, including Al and Zn, the two most common solutes in Mg. These new results highlight the ability of quantum-mechanical first-principles calculations to predict complex material properties such as strength.Comment: 9 pages, 7 figures, 2 table