Space shuttle pogo studies

Topics covered include: (1) pogo suppression for main propulsion subsystem operation; (2) application of quarter-scale low pressure oxidizer turbopump transfer functions; (3) pogo stability during orbital maneuvering subsystem operation; and (4) errors in frequency response measurements

Active Suppression of Pogo on the Space Shuttle

The use of active pogo suppressors on the space shuttle was qualitatively investigated. Suppressor design concepts and the effectiveness of these designs in maintaining the stability of the shuttle vehicle were the primary concerns. Suppressor design concepts were developed by means of a series of parametric stability analyses. These two designs together with two designs provided by NASA were evaluated in detail for control effectiveness, performance relative to a passive suppression device, sensitivity of performance to feedback error, suppressor volume flow requirements, and suppressor development requirements. An active device at the high pressure oxidizer pump inlet was shown to provide a simple and effective design that is insensitive to error in the feedback signal. The sizing of an active suppressor was demonstrated to be dependent upon knowledge of the dynamic characteristics of the system

Analysis of pogo on the space shuttle: Accumulator design guidelines and planar multiengine model development

The design guidelines were generated to support the selection of the baseline accumulator configuration for the space shuttle. They were based upon the elimination of the instabilities that had been predicted for the shuttle system (in the absence of accumulators) using the single-engine model. The multiengine pitch plane stability model was subsequently developed to enable a more refined analysis of the pogo problem. The results obtained with this refined model, in the absence of accumulators, indicated a generally stable system. However, it was found that reasonable adjustment of the axial motion of the feedline aft support on the external tank could induce instability of the system. This instability was eliminated by the addition of high-pressure oxidizer turbopump inlet accumulators to the system. The results obtained with the refined model did not suggest a need to alter the design guidelines that had been obtained previously. The analyses with the multiengine model also treated the question of the use of a phase margin in the system stability requirements

Cost analysis for the development and operation of a mobile wireless research facility

MBA Professional ReportThe Nemesis program's primary objective is to provide a mobile wireless research facility for Federal agencies and other authorized agencies. The report provides estimates of the Nemesis program's original cost, replication cost, scheduled costing for operational requirements, and budgeting guidelines. The report provides future funding request justification for both labor and equipment lifecycle costs. The report also provides the program funding agencies a more precise cost benefit analysis, to project future operating costs, and to provide standardized budget guidelines. The estimate of the original cost includes equipment acquisitions, software and reference material acquisition, inventory validation, billed labor, estimated non-billed labor, estimated nonbilled infrastructure support, billed training and certification, estimated project management, and estimated administrative support. The estimate of the original cost does not include legal support and Governmental administrative requirements. The replicating cost is determined from the original cost with discovery costs removed. The discovery cost includes initial research/evaluation of alternate methods of system implementation, reduced expertise in labor due to documented replicating procedures, and an improved training process for operators. The costing schedule is based on the projected program-operating tempo. The budgeting guidelines provide the budget format, target parameters for inventory, and capital reinvestment to offset depreciation expenses.Approved for public release; distribution is unlimited.Lieutenant, United States Navyhttp://archive.org/details/costnalysisforde10945994

Public health and economic costs of investigating a suspected outbreak of Legionnaires' disease.

This paper provides one of the first assessments of the burden of both the public health investigation and the economic costs associated with an apparent outbreak of Legionnaires' disease (LD) in South East London. In addition to epidemiological, microbiological and environmental investigations, we collected data on the staff time and resources committed by the 11 main organizations responsible for managing the outbreak. Of the overall estimated costs of 455,856 pounds, only 14% (64,264 pounds) was spent on investigation and control of the outbreak compared with 86% (391,592 pounds) spent on the hospital treatment of the patients. The time and money spent on public health services in this investigation appear to represent good value for money considering the potential costs of a major outbreak, including the high case-fatality rate in LD generally and the high health-care costs. Further research is needed to determine optimum strategies for the cost-effective use of health system resources in investigations of LD. Whether the threshold for investigation of cases should be based on observed incidence rates or the cost-effectiveness of investigations, or both, should be debated further

Grey zone simulations of the morning convective boundary layer development

Numerical simulations of two cases of morning boundary layer development are conducted to investigate the impact of grid resolution on mean profiles and turbulent kinetic energy (TKE) partitioning from the large eddy simulation (LES) to the mesoscale limit. Idealized LES, using the 3-D Smagorinsky scheme, is shown to be capable of reproducing the boundary layer evolution when compared against measurements. However, increasing grid spacing results in the damping of resolved TKE and the production of superadiabatic temperature profiles in the boundary layer. Turbulence initiation is significantly delayed, exhibiting an abrupt onset at intermediate resolutions. Two approaches, the bounding of vertical diffusion coefficient and the blending of the 3-D Smagorinsky with a nonlocal 1D scheme, are used to model subgrid diffusion at grey zone resolutions. Simulations are compared against the coarse-grained fields from the validated LES results for each case. Both methods exhibit particular strengths and weaknesses, indicating the compromise that needs to be made currently in high-resolution numerical weather prediction. The blending scheme is able to reproduce the adiabatic profiles although turbulence is underestimated in favor of the parametrized heat flux, and the spin-up of TKE remains delayed. In contrast, the bounding approach gives an evolution of TKE that follows the coarse-grained LES very well, relying on the resolved motions for the nonlocal heat flux. However, bounding gives unrealistic static instability in the early morning temperature profiles (similar to the 3-D Smagorinsky scheme) because model dynamics are unable to resolve TKE when the boundary layer is too shallow compared to the grid spacing.This work has been funded by the Natural Environment Research Council (NERC) GREYBLS (Modelling Grey Zone Boundary Layers) project (grant NE/K011456/1). We acknowledge the use of the MONSooN system, a collaborative facility supplied under the Joint Weather and Climate Research Programme, which is a strategic partnership between the Met Office and the Natural Environment Research Council

Exploring the development of team identification.

The article discusses a study investigating the development of identification with sports teams, with particular focus given to the application of social identity theory and the psychological continuum model (PCM). The development of internal meaning attached to the team and external actions such as searching for team-related information and promoting the team to others is examined, and the influence of media on attitude formation is commented on. A review of previous literature on the topic is also provided

The Janus face of diversity in Australian sport

In this essay, Janus is used as a metaphor for examining the nature of cultural diversity in Australian sport. It does so by firstly presenting a historical context for sport in Australia and the relative lack of cultural diversity found in sport. Within a country dominated by the running codes of football and cricket, the position of soccer in Australia was somewhat unique as it became a bastion for many non-Anglo migrant groups. However, in the 1980s and 1990s soccer's lack of organizational success at the state and national level was negatively ascribed to the tensions between the ethnically affiliated clubs, the same clubs that were ironically the stalwarts driving the growing popularity of the sport. We examine the initiatives used to restructure the game in Australia to make football more appealing to mainstream (i.e. non-ethnically aligned) spectators. The contemporary situation is explored through secondary documentation and the results of a survey of 3,056 spectators undertaken during the first season of the new A-League are presented. The essay concludes with a discussion about the relative success of the restructure in terms of changing the face of Australian soccer. © 2009 Taylor & Francis