11,958 research outputs found

    Science opportunities from the Topex/Poseidon mission

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    The U.S. National Aeronautics and Space Administration (NASA) and the French Centre National d'Etudes Spatiales (CNES) propose to conduct a Topex/Poseidon Mission for studying the global ocean circulation from space. The mission will use the techniques of satellite altimetry to make precise and accurate measurements of sea level for several years. The measurements will then be used by Principal Investigators (selected by NASA and CNES) and by the wider oceanographic community working closely with large international programs for observing the Earth, on studies leading to an improved understanding of global ocean dynamics and the interaction of the ocean with other processes influencing life on Earth. The major elements of the mission include a satellite carrrying an altimetric system for measuring the height of the satellite above the sea surface; a precision orbit determination system for referring the altimetric measurements to geodetic coordinates; a data analysis and distribution system for processing the satellite data, verifying their accuracy, and making them available to the scientific community; and a principal investigator program for scientific studies based on the satellite observations. This document describes the satellite, its sensors, its orbit, the data analysis system, and plans for verifying and distributing the data. It then discusses the expected accuracy of the satellite's measurements and their usefulness to oceanographic, geophysical, and other scientific studies. Finally, it outlines the relationship of the Topex/Poseidon mission to other large programs, including the World Climate Research Program, the U.S. Navy's Remote Ocean Sensing System satellite program and the European Space Agency's ERS-1 satellite program

    High-quality ion beams by irradiating a nano-structured target with a petawatt laser pulse

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    We present a novel laser based ion acceleration scheme, where a petawatt circularly polarized laser pulse is shot on an ultra-thin (nano-scale) double-layer target. Our scheme allows the production of high-quality light ion beams with both energy and angular dispersion controllable by the target properties. We show that extraction of all electrons from the target by radiation pressure can lead to a very effective two step acceleration process for light ions if the target is designed correctly. Relativistic protons should be obtainable with pulse powers of a few petawatt. Careful analytical modeling yields estimates for characteristic beam parameters and requirements on the laser pulse quality, in excellent agreement with one and two-dimensional Particle-in Cell simulations.Comment: 18 pages, 7 figures, accepted in New. J. Phy

    Superconductivity and short range order in metallic glasses Fex_{x}Ni1−x_{1-x}Zr2_{2}

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    In amorphous superconductors, superconducting and vortex pinning properties are strongly linked to the absence of long range order. Consequently, superconductivity and vortex phases can be studied to probe the underlying microstructure and order of the material. This is done here from resistance and local magnetization measurements in the superconducting state of Fex_{x}Ni1−x_{1-x}Zr2_{2} metallic glasses with 0≤x≤0.60\leq x \leq 0.6. Firstly, we present typical superconducting properties such as the critical temperature and fields and their dependence on Fe content in these alloys. Then, the observations of peculiar clockwise hysteresis loops, wide double-step transitions and large magnetization fluctuations in glasses containing a large amount of Fe are analyzed to reveal a change in short range order with Fe content.Comment: 8 pages, 7 figure

    Spontaneous ignition delay characteristics of hydrocarbon fuel-air mixtures

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    The influence of pressure on the autoignition characteristics of homogeneous mixtures of hydrocarbon fuels in air is examined. Autoignition delay times are measured for propane, ethylene, methane, and acetylene in a continuous flow apparatus featuring a multi-point fuel injector. Results are presented for mixture temperatures from 670K to 1020K, pressures from 1 to 10 atmospheres, equivalence ratios from 0.2 to 0.7, and velocities from 5 to 30 m/s. Delay time is related to pressure, temperature, and fuel concentration by global reaction theory. The results show variations in global activation energy from 25 to 38 kcal/kg-mol, pressure exponents from 0.66 to 1.21, and fuel concentration exponents from 0.19 to 0.75 for the fuels studied. These results are generally in good agreement with previous studies carried out under similar conditions

    European Beech (Fagus Sylvatica) Observations

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    The location of tree #604 is by the walkway to the library, and right across the street from the Salve Regina Mercy Center. I observed this tree from September 24, 2021 until December 9, 2021. This tree is a European Beech (Fagus sylvatica) tree.https://digitalcommons.salve.edu/bio140_arboretum/1034/thumbnail.jp

    iWaste: Analyzing Apple\u27s Sustainable Technology Production

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    Electronic waste is a global issue that has not received the attention it deserves; there is an enormous amount of e-waste from the rapid industrialization of many countries throughout the world. Apple is the largest technology company in the world, with the highest revenue and the largest number of products manufactured. Therefore, it is important to see what they are doing to mitigate their efforts to the electronic waste crisis that is expected to increase in the next seven years. Three policy options are examined in this paper to evaluate and determine how well Apple is following the goals within their 2022 Environmental Progress Report.https://digitalcommons.salve.edu/glo100/1004/thumbnail.jp
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