15,081 research outputs found

    The continuously supported rail subjected to an axial force and a moving load

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    Axial compression force effects in welded rails on critical velocity for high speed trai

    A further study of elastic foundation models

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    Response expressions for elastic foundation model

    Users guide: Steady-state aerodynamic-loads program for shuttle TPS tiles

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    A user's guide for the computer program that calculates the steady-state aerodynamic loads on the Shuttle thermal-protection tiles is presented. The main element in the program is the MITAS-II, Martin Marietta Interactive Thermal Analysis System. The MITAS-II is used to calculate the mass flow in a nine-tile model designed to simulate conditions duing a Shuttle flight. The procedures used to execute the program using the MITAS-II software are described. A list of the necessry software and data files along with a brief description of their functions is given. The format of the data file containing the surface pressure data is specified. The interpolation techniques used to calculate the pressure profile over the tile matrix are briefly described. In addition, the output from a sample run is explained. The actual output and the procedure file used to execute the program at NASA Langley Research Center on a CDC CYBER-175 are provided in the appendices

    Experimental aerodynamic heating to simulated shuttle tiles

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    The heat transfer to simulated shuttle thermal protection system tiles was investigated experimentally using a highly instrumented metallic thin wall tile arranged with other metal tiles in a staggered tile array. Cold-wall heating rate data for laminar and turbulent flow were obtained in the Langley 8-foot high temperature tunnel at a nominal Mach number of 7, a nominal total temperature of 3300 R, free-stream unit Reynolds number from 3.4 x 10 to the 5th power to 2.2 x 10 to the 6th power per foot, and free-stream dynamic pressure of 1.8 psia to 9.1 psia. Experimental data are presented to illustrate the effects of flow angularity and gap width on both local peak heating and overall heating loads

    The Effects of Ultraviolet Light on Anthocyanin Accumulation in the Adventitious Roots of Sedum wrightii (Crassulaceae)

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    Several studies have supported the idea that anthocyanin accumulation may be a possible protection mechanism in plants against DNA damage caused by ultraviolet radiation (UV). This study explored the accumulation of anthocyanins in the adventitious root tips of Sedum wrightii using the following treatments: UVA, UVA+low UVB, and UVA+high UVB. Following exposure to UV radiation, samples were analyzed for anthocyanin accumulation using an ethanol extraction procedure. Using ELISA, additional root samples were analyzed for indicators of DNA damage: cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone dimers (6-4 PPs). The anthocyanin concentrations were significantly higher in the UVA + high UVB treatment than the other groups. The ELISA resultsshowed that a difference occurred between the control and the treatments of UVA, UVA+low UVB and UVA+high UVB for CPDs and between the control and the UVB treatments for 6-4 PPs. Anthocyanins accumulated with increased UV exposure. However, additional research is needed to determine the significance of anthocyanins in the adventitious root tips of S. wrightii

    Development of biaxial test fixture includes cryogenic application

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    Test fixture has the capability of producing biaxial stress fields in test specimens to the point of failure. It determines biaxial stress by dividing the applied load by the net cross section. With modification it can evaluate materials, design concepts, and production hardware at cryogenic temperatures

    A novel approach for quality control system using sensor fusion of infrared and visual image processing for laser sealing of food containers

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    This paper presents a new mechatronic approach of using infrared thermography combined with image processing for the quality control of a laser sealing process for food containers. The suggested approach uses an on-line infrared system to assess the heat distribution within the container seal in order to guarantee the integrity of the process. Visual image processing is then used for quality assurance to guarantee optimum sealing. The results described in this paper show examples of the capability of the condition monitoring system to detect faults in the sealing process. The results found indicate that the suggested approach could form an effective quality control and assurance system

    Renormalization by gravity and the Kerr spinning particle

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    On the basis of the Kerr spinning particle, we show that the mass renormalization is perfectly performed by gravity for an arbitrary distribution of source matter. A smooth regularization of the Kerr-Newman solution is considered, leading to a source in the form of a rotating bag filled by a false vacuum. It is shown that gravity controls the phase transition to an AdS or dS false vacuum state inside the bag, providing the mass balance.Comment: 9 pages, 2 figure

    Shades of Grey: Ethical Dilemmas

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    The Use of Robots in Hydrography

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    Robots are increasingly being applied to tasks which are hazardous or which they can carry out more effectively or safely than people. The use of remotely controlled submersibles for conducting precise undersea surveys has been proposed recently in conjunction with oil industry activities. In Canada robot vehicles are currently under development for offshore surveys of areas under permanent ice cover. This paper describes two requirements, the different technology that is involved in each system, and the progress to date on the developments which, in the case of one system, have now advanced to successful field trials
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