NPLOT: an Interactive Plotting Program for NASTRAN Finite Element Models

The NPLOT (NASTRAN Plot) is an interactive computer graphics program for plotting undeformed and deformed NASTRAN finite element models. Developed at NASA's Goddard Space Flight Center, the program provides flexible element selection and grid point, ASET and SPC degree of freedom labelling. It is easy to use and provides a combination menu and command driven user interface. NPLOT also provides very fast hidden line and haloed line algorithms. The hidden line algorithm in NPLOT proved to be both very accurate and several times faster than other existing hidden line algorithms. A fast spatial bucket sort and horizon edge computation are used to achieve this high level of performance. The hidden line and the haloed line algorithms are the primary features that make NPLOT different from other plotting programs

Shock absorber Patent

Design and development of double acting shock absorber for spacecraft docking operation

Variable domain transformation for linear PAC analysis of mixed-signal systems

This paper describes a method to perform linear AC analysis on mixed-signal systems which appear strongly nonlinear in the voltage domain but are linear in other variable domains. Common circuits like phase/delay-locked loops and duty-cycle correctors fall into this category, since they are designed to be linear with respect to phases, delays, and duty-cycles of the input and output clocks, respectively. The method uses variable domain translators to change the variables to which the AC perturbation is applied and from which the AC response is measured. By utilizing the efficient periodic AC (PAC) analysis available in commercial RF simulators, the circuit’s linear transfer function in the desired variable domain can be characterized without relying on extensive transient simulations. Furthermore, the variable domain translators enable the circuits to be macromodeled as weakly-nonlinear systems in the chosen domain and then converted to voltage-domain models, instead of being modeled as strongly-nonlinear systems directly

Magnets with stabilized conductors

Method fabricates stabilized composite conductor, for use in construction of magnets, using equal amounts of superconducting and metal materials, thus reducing weight, cost and size

Use of composite rotations to correct systematic errors in NMR quantum computation

We implement an ensemble quantum counting algorithm on three NMR spectrometers with 1H resonance frequencies of 500, 600 and 750 MHz. At higher frequencies, the results deviate markedly from naive theoretical predictions. These systematic errors can be attributed almost entirely to off-resonance effects, which can be substantially corrected for using fully-compensating composite rotation pulse sequences originally developed by Tycko. We also derive an analytic expression for generating such sequences with arbitrary rotation angles.Comment: 8 pages RevTex including 7 PostScript figures (18 subfigures

Cultures within a culture: the role of nationality and religion for environmentally significant behaviour in students living in university accommodation

Reducing global warming cannot be achieved through technological interventions alone; it requires a change in human behaviour. Households are a major contributor to carbon emissions, and thus play an integral part in strategies aiming at a more sustainable living. Behaviour changes in the household can make a significant contribution towards reducing CO2 emissions. However, people vary strongly in their household practices; differences in behaviour account for a substantial amount of variance in heat, electricity, and water consumption (Gill et al., 2010). What causes these differences? In addition to age and education, nationality and religion play a role: They impact on physical aspects of well-being and on environmental attitudes (e.g., Isaacs et al., 2010; Guth et al., 1995). The physical aspect such as perception of warmth is of importance insofar as that comfort practices could influence on environmentally significant behaviour. The Eurobarometer 295 (2008), a study on the attitudes of European citizens towards the environment, also revealed differences in attitudes and behaviour of Europeans towards the environment. Therefore, steps to promote more sustainable living have to be adapted to different cultures. Rising globalization brings about more heterogeneous populations, meaning that there will be increasingly "cultures within a culture." An important question is what happens to cultural differences in environmentally significant behaviour in such a setting. It could be that differences are diluted by a largely shared environment, or that they continue to persist, thanks to being deeply rooted in one’s origin and to the non-shared part of the environment. Our study: The aim of this study was to examine the variation in pro-environmental attitudes, behaviour, and values in members of a community now living in a very similar setting but coming from diverse backgrounds. If personal background accounts for differences in the variables at stake, then this has important implications, e.g. for all national interventions launched to change behaviour. Data was collected through a web-based survey. The survey was sent out to first-year students living in university accommodation at the University of Greenwich. Religion, strength of religion, nationality, years living in the UK, program studied, gender and age were recorded and the impact of these variables on a variety of measures such as pro- environmental attitudes, values, and actual behaviour was assessed. Results are currently being analysed but preliminary data suggest that sub-culture does play a role and thus needs to be considered when developing carbon reduction interventions. The implications of these findings for the University and national policies are discussed

Fast, non-monte-carlo estimation of transient performance variation due to device mismatch

This paper describes an efficient way of simulating the effects of device random mismatch on circuit transient characteristics, such as variations in delay or in frequency. The proposed method models DC random offsets as equivalent AC pseudo-noises and leverages the fast, linear periodically time-varying (LPTV) noise analysis available from RF circuit simulators. Therefore, the method can be considered as an extension to DC match analysis and offers a large speed-up compared to the traditional Monte-Carlo analysis. Although the assumed linear perturbation model is valid only for small variations, it enables easy ways to estimate correlations among variations and identify the most sensitive design parameters to mismatch, all at no additional simulation cost. Three benchmarks measuring the variations in the input offset voltage of a clocked comparator, the delay of a logic path, and the frequency of an oscillator demonstrate the speed improvement of about 100-1000x compared to a 1000-point Monte-Carlo method