991 research outputs found

    Planning Flood Control Measures by Digital Computer

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    The purpose of this study was to develop adequate guidelines whereby those interested in flood control planning would be able to apply a pair of digital computer programs known as the University of Kentucky Flood Control Planning Programs to ease the computational burden of evaluating specific flood control situations. Program II determines the economically optimum combination of channel improvement, land use restriction, and flood proofing for flood damage abatement. Program III also incorporates reservoir storage into the planning process. The Programs are not intended to provide a finished design but rather to select the optimum combination of flood control measures and residual flooding with regard to both time and space. Application of Computer Programs to flood control planning is guided by presenting first a general description of the application process then a detailed description of the input required and the output produced by the Planning Programs. Input was developed and results interpreted to determine the optimum flood control plan for the upper reaches of the North Fork of the Kentucky River near Hazard, Kentucky

    Economic Analysis of Alternative Flood Control Measures

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    Within the last few years, the growing realization that an effective flood control program must include non-structural measures (land use management and flood proofing) has resulted in Presidential Executive Order 11296 requiring Federal agencies to seek the optimum combination of structural and non-structural measures for flood control. The requirement has created a dilemma. No methodology is available for systematic evaluation of alternative combinations of structural and non-structural measures. Prospective procedures are too time consuming to be feasible under current financial and manpower limitations. The only way out is to perform much of the planning process by digital computer. With this goal, two flood control planning programs have been developed. Each program systematically selects the optimum combination of channel improvement, flood proofing, and land use management by location within the flood plain and by time. The second program adds detention storage to the list of available alternatives. Both programs contain the entire planning process by going all the way from raw data to a selected optimum program of measure use in one run. However, the programs are not intended to produce a finished design. Their use should be followed by a final field check to verify the input data and preparation of the plans and specifications necessary for implementation. The programs have been applied to a series of flood hazard areas in California and Kentucky and indicated an optimum flood control program in a small fraction of the time spent in current planning methods. They free the planning engineer from spending most of his time in routine calculations and allow more time for consideration of qualitative and intangible factors

    Hastings-Levitov aggregation in the small-particle limit

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    We establish some scaling limits for a model of planar aggregation. The model is described by the composition of a sequence of independent and identically distributed random conformal maps, each corresponding to the addition of one particle. We study the limit of small particle size and rapid aggregation. The process of growing clusters converges, in the sense of Caratheodory, to an inflating disc. A more refined analysis reveals, within the cluster, a tree structure of branching fingers, whose radial component increases deterministically with time. The arguments of any finite sample of fingers, tracked inwards, perform coalescing Brownian motions. The arguments of any finite sample of gaps between the fingers, tracked outwards, also perform coalescing Brownian motions. These properties are closely related to the evolution of harmonic measure on the boundary of the cluster, which is shown to converge to the Brownian web

    Utah\u27s 1977 Drought

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    The Utah Drought of 1976-1977 has been characterized as the wettest drought in history. It was produced by the driest winter season of record followed by summer rains which were much wetter than normal in many regions of the state. Stream-flow is highly correlated with winter rather than summer precipitation and therefore the most severe impacts of the drought were related to the record low stream-flow during 1977 plus the ski industry impacts which were directly related to 1976-1977 snowfall. Drought impacts upon several sectors of the economy plus the extensive responses of all levels of government in the form of drought relief programs are described and quantified

    VLBA Imaging of the OH Maser in IIIZw35

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    We present a parsec-scale image of the OH maser in the nucleus of the active galaxy IIIZw35, made using the Very Long Baseline Array at a wavelength of 18 cm. We detected two distinct components, with a projected separation of 50 pc (for D=110 Mpc) and a separation in Doppler velocity of 70 km/s, which contain 50% of the total maser flux. Velocity gradients within these components could indicate rotation of clouds with binding mass densities of ~7000 solar masses per cubic parsec, or total masses of more than 500,000 solar masses. Emission in the 1665-MHz OH line is roughly coincident in position with that in the 1667-MHz line, although the lines peak at different Doppler velocities. We detected no 18 cm continuum emission; our upper limit implies a peak apparent optical depth greater than 3.4, assuming the maser is an unsaturated amplifier of continuum radiation.Comment: 10 pages, 3 figure

    Effects of Heating on Teflon(Registered Trademark) FEP Thermal Control Material from the Hubble Space Telescope

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    Metallized Teflon(Registered Trademark) FEP (fluorinated ethylene propylene) thermal control material on the Hubble Space Telescope (HST) is degrading in the space environment. Teflon(Registered Trademark) FEP thermal control blankets (space-facing FEP) retrieved during the first servicing mission (SM1) were found to be embrittled on solar facing surfaces and contained microscopic cracks. During the second servicing mission (SM2) astronauts noticed that the FEP outer layer of the multi-layer insulation (MLI) covering the telescope was cracked in many locations around the telescope. Large cracks were observed on the light shield, forward shell and equipment bays. A tightly curled piece of cracked FEP from the light shield was retrieved during SM2 and was severely embrittled, as witnessed by ground testing. A Failure Review Board (FRB) was organized to determine the mechanism causing the MLI degradation. Density, x-ray crystallinity and solid state nuclear magnetic resonance (NMR) analyses of FEP retrieved during SM1 were inconsistent with results of FEP retrieved during SM2. Because the retrieved SM2 material curled while in space, it experienced a higher temperature extreme during thermal cycling, estimated at 200 C, than the SM1 material, estimated at 50 C. An investigation on the effects of heating pristine and FEP exposed on HST was therefore conducted. Samples of pristine. SM1, and SM2 FEP were heated to 200 C and evaluated for changes in density and morphology. Elevated temperature exposure was found to have a major impact on the density of the retrieved materials. Characterization of polymer morphology of as-received and heated FEP samples by NMR provided results that were consistent with the density results. These findings have provided insight to the damage mechanisms of FEP in the space environment

    Insights Developed Into the Damage Mechanism of Teflon FEP Thermal Control Material on the Hubble Space Telescope

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    Metalized Teflon FEP (DuPont; fluorinated ethylene propylene) thermal control material on the Hubble Space Telescope (HST) has been found to degrade in the space environment. Teflon FEP thermal control blankets retrieved during the first servicing mission were found to be embrittled on solar-facing surfaces and to contain microscopic cracks (the FEP surface is exposed to the space environment). During the second servicing mission, astronauts noticed that the FEP outer layer of the multilayer insulation blanketing covering the telescope was cracked in many locations. Large cracks were observed on the light shield, forward shell, and equipment bays. A tightly curled piece of cracked FEP from the light shield was retrieved during the second mission. This piece was severely embrittled, as witnessed by ground testing. A Failure Review Board was organized by NASA Goddard Space Flight Center to determine the mechanism causing the multilayer insulation degradation. This board included members of the Electro-Physics Branch of the NASA Glenn Research Center at Lewis Field. Density measurements of the retrieved materials obtained under the review board's investigations indicated that FEP from the first servicing mission was essentially unchanged from pristine FEP but that the second servicing mission FEP had increased in density in comparison to pristine FEP (ref. 1). The results were consistent with crystallinity measurements taken using x-ray diffraction and with results from solid-state nuclear magnetic resonance tests (see the table and ref. 1). Because the second servicing mission FEP was embrittled and its density and crystallinity had increased in comparison to pristine FEP, board researchers expected that the first servicing mission FEP, which was also embrittled, would also have increased in crystallinity and density, but it did not. Because the retrieved second servicing mission material curled while in space, it experienced a higher temperature extreme during thermal cycling (estimated at 200 C) than the first servicing mission material (estimated at 50 C). Therefore, Glenn initiated and conducted an investigation of the effects of heating pristine FEP and FEP that had been exposed on the Hubble Space Telescope. Samples of pristine and first and second servicing mission FEP were heated to 200 C and evaluated for changes in density and morphology. We hoped that the results would help explain why FEP degrades in the Hubble Space Telescope space environment

    Rural Food Pantry Users’ Stigma and Safety Net Food Programs

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    Increasing numbers of individuals in our community have been seeking local food pantry assistance. Previous studies of food pantries found that users show low rates of governmental aid receipt, especially in rural areas. We assessed evidence that suggests that post-recession need has mitigated rural reluctance to pursue government assistance. The inadequacy of government and local food assistance to address the problem of food insecurity in our community is discussed

    Community-based Rehabilitation Training after stroke: Protocol of a pilot randomised controlled trial (ReTrain)

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    Introduction: The Rehabilitation Training (ReTrain) intervention aims to improve functional mobility, adherence to poststroke exercise guidelines and quality of life for people after stroke. A definitive randomised controlled trial (RCT) is required to assess the clinical and cost-effectiveness of ReTrain, which is based on Action for Rehabilitation from Neurological Injury (ARNI). The purpose of this pilot study is to assess the feasibility of such a definitive trial and inform its design. Methods and analysis: A 2-group, assessor-blinded, randomised controlled external pilot trial with parallel mixed-methods process evaluation and economic evaluation. 48 participants discharged from clinical rehabilitation despite residual physical disability will be individually randomised 1:1 to ReTrain (25 sessions) or control (exercise advice booklet). Outcome assessment at baseline, 6 and 9 months include Rivermead Mobility Index; Timed Up and Go Test; modified Patient-Specific Functional Scale; 7-day accelerometry; Stroke Self-efficacy Questionnaire, exercise diary, Fatigue Assessment Scale, exercise beliefs and self-efficacy questionnaires, SF-12, EQ-5D-5L, Stroke Quality of Life, Carer Burden Index and Service Receipt Inventory. Feasibility, acceptability and process outcomes include recruitment and retention rates; with measurement burden and trial experiences being explored in qualitative interviews (20 participants, 3 intervention providers). Analyses include descriptive statistics, with 95% CI where appropriate; qualitative themes; intervention fidelity from videos and session checklists; rehearsal of health economic analysis. Ethics and dissemination: National Health Service (NHS) National Research Ethics Service approval granted in April 2015; recruitment started in June. Preliminary studies suggested low risk of serious adverse events; however (minor) falls, transitory muscle soreness and high levels of postexercise fatigue are expected. Outputs include pilot data to inform whether to proceed to a definitive RCT and support a funding application; finalised Trainer and Intervention Delivery manuals for multicentre replication of ReTrain; presentations at conferences, public involvement events; internationally recognised peer-reviewed journal publications, open access sources and media releases
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