Flow Analysis of Space Shuttle Feed Line 17-inch Disconnect Valve

A steady incompressible three-dimensional viscous flow analysis has been conducted for the Space Shuttle External Tank/Orbiter propellant feed line disconnect flapper valves with upstream elbows. The full Navier-Stokes code, INS3D, is modified to handle interior obstacles. Grids are generated by SVTGD3D code. Two dimensional initial grids in the flow cross section with and without the flappers are improved by elliptic smoothing to provide better orthogonality, clustering and smoothness to the three dimensional grid. The flow solver is tested for stability and convergence in the presence of interior flappers. An under-relaxation scheme has been incorporated to improve the solution stability. Important flow characteristics such as secondary flows, recirculation, vortex and wake regions, and separated flows are observed. Computed values for forces, moments, and pressure drop are in satisfactory agreement with water flow test data covering a maximum tube Reynolds number of 3.5 x 10(exp 6). The results will serve as a guide to improved design and enhanced testing of the disconnect

Density regulation in strictly metric-free swarms

There is now experimental evidence that nearest-neighbour interactions in flocks of birds are metric free, i.e. they have no characteristic interaction length scale. However, models that involve interactions between neighbours that are assigned topologically are naturally invariant under spatial expansion, supporting a continuous reduction in density towards zero, unless additional cohesive interactions are introduced or the density is artificially controlled, e.g. via a finite system size. We propose a solution that involves a metric-free motional bias on those individuals that are topologically identified to be on an edge of the swarm. This model has only two primary control parameters, one controlling the relative strength of stochastic noise to the degree of co-alignment and another controlling the degree of the motional bias for those on the edge, relative to the tendency to co-align. We find a novel power-law scaling of the real-space density with the number of individuals N as well as a familiar order-to-disorder transition

Human Perambulation as a Self Calibrating Biometric

This paper introduces a novel method of single camera gait reconstruction which is independent of the walking direction and of the camera parameters. Recognizing people by gait has unique advantages with respect to other biometric techniques: the identification of the walking subject is completely unobtrusive and the identification can be achieved at distance. Recently much research has been conducted into the recognition of frontoparallel gait. The proposed method relies on the very nature of walking to achieve the independence from walking direction. Three major assumptions have been done: human gait is cyclic; the distances between the bone joints are invariant during the execution of the movement; and the articulated leg motion is approximately planar, since almost all of the perceived motion is contained within a single limb swing plane. The method has been tested on several subjects walking freely along six different directions in a small enclosed area. The results show that recognition can be achieved without calibration and without dependence on view direction. The obtained results are particularly encouraging for future system development and for its application in real surveillance scenarios

Geometry and mechanics of microdomains in growing bacterial colonies

Bacterial colonies are abundant on living and nonliving surfaces and are known to mediate a broad range of processes in ecology, medicine, and industry. Although extensively researched, from single cells to demographic scales, a comprehensive biomechanical picture, highlighting the cell-to-colony dynamics, is still lacking. Here, using molecular dynamics simulations and continuous modeling, we investigate the geometrical and mechanical properties of a bacterial colony growing on a substrate with a free boundary and demonstrate that such an expanding colony self-organizes into a "mosaic" of microdomains consisting of highly aligned cells. The emergence of microdomains is mediated by two competing forces: the steric forces between neighboring cells, which favor cell alignment, and the extensile stresses due to cell growth that tend to reduce the local orientational order and thereby distort the system. This interplay results in an exponential distribution of the domain areas and sets a characteristic length scale proportional to the square root of the ratio between the system orientational stiffness and the magnitude of the extensile active stress. Our theoretical predictions are finally compared with experiments with freely growing E. coli microcolonies, finding quantitative agreement.Comment: 10 pages, 7 figure

BioMEMS Wireless Pressure Sensor

A design and manufacture of a wireless pressure sensor was proposed as a future tool for use in biological monitoring. This device is designed to acquire pressure changes through a change in capacitance. This is accomplished using a large circular parallel plate capacitor separated by a micron of air. The upper and lower plates are connected together via a large planar inductor on the opposite end of the device. The inductor and capacitor in a parallel form a resonant circuit with resonant frequency equal to one over the square root of inductance times capacitance. The resonant frequency can be dependent on both the inductance and capacitance changes. Since the inductance is fixed, the resonant frequency should change with respect to the capacitance. The capacitance will change as the pressure changes and therefore pressure can be measured through frequency. In the process of manufacturing this device, many unforeseen problems arose resulting in structural and design failures. These problems along with their discovered solutions will be addressed

MS

thesisThis endeavor describes the development of a parenteral admixture program in a 175-bed pediatric acute care hospital. It begins with a description of the advantage to the hospital of a parenteral admixture program as compared to conventional floor stock systems. Some examples of other admixture programs are cited along with specific characteristics of programs that could be applicable to any hospital. An outline is presented of the basic steps found in all programs. A detailed description is given illustrating how the program was actually developed in this hospital. This description includes items such as: 1) how space for the additive center was procured; 2) how a prediction of the workload was arrived at; 3) how the equipment for the center was procured; 4) how the pilot study was set up. This is followed by protocol for the admixture program. A discussion of data obtained during the development of this program includes: 1) how the I.V. usage rate of each was obtained; 2) how the amount of capital los due to the floor stock I.V. system was determined; 3) the amount of capital and the square feet of storage space tied up by the floor stock systems; 4) the amount of time save in the hospital by the additive system; and 5) and evaluation of how many personnel in the hospital were required per 100 I.V. solutions used before and after the additive system. The last chapter discusses the effectiveness of the admixture program based on previously established parameters. Some of the conclusions reached are as follows: 1) The program did save the hospitals money through more efficient use of time and equipment. a) Capital tied up in floor stock was greatly reduced. b) The program reduced the number of man-hours required to operate the I.V. therapy function in the hospital. This freed the nurses more from medication problems and gave them more time for bedside care. c) Checks were made to insure accuracy and also more care was taken in following established hospital policies regarding parenteral therapy as a result of the program. d) Solution and medications were all labeled properly and uniformly

Works Covered In Graduate Reading Reasearch Courses: Two Surveys

What studies should be covered in a graduate reading research course? How should the course be structured? These are questions I considered before teaching a reading research course for the first time. An investigation of the literature found little on reading research courses. While some works identified important studies, articles, and books (Froese, 1981; Manzo, 1983; Pearce and Bader, 1980; and Singer, 1985), none specifically addressed reading research courses. Gentile, Kamil, and Blanchard\u27s Reading Research Revisited (1983) identified studies and furnished a structure. The studies covered, however, appeared to be the editors\u27 choices. In an attempt to answer questions about course content and structure, a two part study was conducted. The first part was a survey to identify reading selections for a research course. A follow-up survey attempted to clarify why certain selections had been named

The Role of Projection in the Control of Bird Flocks

Swarming is a conspicuous behavioural trait observed in bird flocks, fish shoals, insect swarms and mammal herds. It is thought to improve collective awareness and offer protection from predators. Many current models involve the hypothesis that information coordinating motion is exchanged between neighbors. We argue that such local interactions alone are insufficient to explain the organization of large flocks of birds and that the mechanism for the exchange of long-ranged information necessary to control their density remains unknown. We show that large flocks self-organize to the maximum density at which a typical individual is still just able to see out of the flock in many directions. Such flocks are marginally opaque - an external observer can also just still see a substantial fraction of sky through the flock. Although seemingly intuitive we show that this need not be the case; flocks could easily be highly diffuse or entirely opaque. The emergence of marginal opacity strongly constrains how individuals interact with each other within large swarms. It also provides a mechanism for global interactions: An individual can respond to the projection of the flock that it sees. This provides for faster information transfer and hence rapid flock dynamics, another advantage over local models. From a behavioural perspective it optimizes the information available to each bird while maintaining the protection of a dense, coherent flock.Comment: PNAS early edition published online at http://www.pnas.org/cgi/doi/10.1073/pnas.140220211

Outcome modelling strategies in epidemiology: traditional methods and basic alternatives.

Controlling for too many potential confounders can lead to or aggravate problems of data sparsity or multicollinearity, particularly when the number of covariates is large in relation to the study size. As a result, methods to reduce the number of modelled covariates are often deployed. We review several traditional modelling strategies, including stepwise regression and the 'change-in-estimate' (CIE) approach to deciding which potential confounders to include in an outcome-regression model for estimating effects of a targeted exposure. We discuss their shortcomings, and then provide some basic alternatives and refinements that do not require special macros or programming. Throughout, we assume the main goal is to derive the most accurate effect estimates obtainable from the data and commercial software. Allowing that most users must stay within standard software packages, this goal can be roughly approximated using basic methods to assess, and thereby minimize, mean squared error (MSE)

Computational fluid dynamics analysis of space shuttle main propulsion feed line 17-inch disconnect valves

A steady incompressible three-dimensional (3-D) viscous flow analysis was conducted for the Space Shuttle Main Propulsion External Tank (ET)/Orbiter (ORB) propellant feed line quick separable 17-inch disconnect flapper valves for liquid oxygen (LO2) and liquid hydrogen (LH2). The main objectives of the analysis were to predict and correlate the hydrodynamic stability of the flappers and pressure drop with available water test data. Computational Fluid Dynamics (CFD) computer codes were procured at no cost from the public domain, and were modified and extended to carry out the disconnect flow analysis. The grid generator codes SVTGD3D and INGRID were obtained. NASA Ames Research Center supplied the flow solution code INS3D, and the color graphics code PLOT3D. A driver routine was developed to automate the grid generation process. Components such as pipes, elbows, and flappers can be generated with simple commands, and flapper angles can be varied easily. The flow solver INS3D code was modified to treat interior flappers, and other interfacing routines were developed, which include a turbulence model, a force/moment routine, a time-step routine, and initial and boundary conditions. In particular, an under-relaxation scheme was implemented to enhance the solution stability. Major physical assumptions and simplifications made in the analysis include the neglect of linkages, slightly reduced flapper diameter, and smooth solid surfaces. A grid size of 54 x 21 x 25 was employed for both the LO2 and LH2 units. Mixing length theory applied to turbulent shear flow in pipes formed the basis for the simple turbulence model. Results of the analysis are presented for LO2 and LH2 disconnects