A power filter for the detection of burst sources of gravitational radiation in interferometric detectors

We present a filter for detecting gravitational wave signals from burst sources. This filter requires only minimal advance knowledge of the expected signal: i.e. the signal's frequency band and time duration. It consists of a threshold on the total power in the data stream in the specified signal band during the specified time. This filter is optimal (in the Neyman-Pearson sense) for signal searches where only this minimal information is available.Comment: 3 pages, RevTeX, GWDAW '99 proceedings contribution, submitted to Int. J. Modern Phys.

Deep space network

Background, current status, and sites of Deep Space Network stations are briefly discussed

Data analysis strategies for the detection of gravitational waves in non-Gaussian noise

In order to analyze data produced by the kilometer-scale gravitational wave detectors that will begin operation early next century, one needs to develop robust statistical tools capable of extracting weak signals from the detector noise. This noise will likely have non-stationary and non-Gaussian components. To facilitate the construction of robust detection techniques, I present a simple two-component noise model that consists of a background of Gaussian noise as well as stochastic noise bursts. The optimal detection statistic obtained for such a noise model incorporates a natural veto which suppresses spurious events that would be caused by the noise bursts. When two detectors are present, I show that the optimal statistic for the non-Gaussian noise model can be approximated by a simple coincidence detection strategy. For simulated detector noise containing noise bursts, I compare the operating characteristics of (i) a locally optimal detection statistic (which has nearly-optimal behavior for small signal amplitudes) for the non-Gaussian noise model, (ii) a standard coincidence-style detection strategy, and (iii) the optimal statistic for Gaussian noise.Comment: 5 pages RevTeX, 4 figure

Development and flight tests of a Kalman filter for navigation during terminal area and landing operations

A Kalman filter for aircraft terminal area and landing navigation was implemented and flight tested in the NASA Ames STOLAND avionics computer onboard a Twin Otter aircraft. This system combines navaid measurements from TACAN, MODILS, air data, radar altimeter sensors along with measurements from strap-down accelerometer and attitude angle sensors. The flight test results demonstrate that the Kalman filter provides improved estimates of the aircraft position and velocity as compared with estimates from the more standard complementary filter. The onboard computer implementation requirements to achieve this improved performance are discussed

Perceived influences on the career choices of children and youth: an exploratory study

Children’s understanding of factors influencing their career choices was examined. Seventy-two children, in grades kindergarten, 4, and 8, responded to questions about their perceptions of career influences. Responses were coded to capture the nature of the influences identified, including the global versus specific and linear versus interacting nature of these influences. Further, influences were coded as existing proximal versus distal to the child. Results indicate that older children identified more career influences that were either specific or categorical and interacted in dynamic ways. No evidence was found for older children offering influences that existed at a systems level of organization.Accepted manuscrip

Optimising the use of Materials for Construction MSMEs: Building a Comprehensive Framework for Decision-Making and Resource Allocation through an Analytic Hierarchy Process

The efficiency, governance, and compliance with environmental ideals in construction is made possible thanks to a decision support system that ensures Materials, Models, and Methods (3Ms) are adaptable and integrated. Recent advances in Information Technology (IT), for instance, facilitate the visualisation of sequences and production stages in construction. Yet, this falls short in giving compatibility among the 3Ms, their suitability and workability, and their financial and legislative viability. To this end, this manuscript rethinks the concept of productivity, and lays the foundation for a new decision support system that is simple, affordable, and portable enough to attract large enterprises and MSMEs. Ideally, an efficient construction project has good flow of workstreams, is least complex, cost minimised but with added value, timely and in symbiosis with natural health provisions of the ecosystem. A mixed methodology based on gathering data from document reviews, semi-structured interviews, and observations of selected construction MSMEs, will allow to carry out longitudinal research and then code, group, link and analyse the collected raw data through the Analytic Hierarchy Process (AHP) Multi Criteria Decision Making technique. This technique is chosen to develop overall priorities for ranking the alternatives, measure, and monetise the impacting factors to draw out the main impediments to achieve good levels of efficiency. The outputs of the AHP analysis feeds into the novel decision support system, the concepts of which are introduced in this contribution

Ionization Structure and the Reverse Shock in E0102-72

The young oxygen-rich supernova remnant E0102-72 in the Small Magellanic Cloud has been observed with the High Energy Transmission Grating Spectrometer of Chandra. The high resolution X-ray spectrum reveals images of the remnant in the light of individual emission lines of oxygen, neon, magnesium and silicon. The peak emission region for hydrogen-like ions lies at larger radial distance from the SNR center than the corresponding helium-like ions, suggesting passage of the ejecta through the "reverse shock". We examine models which test this interpretation, and we discuss the implications.Comment: 4 pages, 6 figures; To appear in "Young Supernova Remnants" (11th Annual Astrophysics Conference in Maryland), S. S. Holt & U. Hwang (eds), AIP, New York (2001