9,803 research outputs found

    Self-charging metering and dispensing device for fluids

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    A self-metering and dispensing device for fluids obtained from a pressurized fluid supply is discussed. Tubing and valving means permit the introduction of fluid into and discharge from a closed cylindrical reservoir. The reservoir contains a slideably disposed piston co-acting with a coil compression spring, with piston travel determining the amount of fluid in the reservoir. Once the determined amount of fluid is introduced into the reservoir, the fluid is discharged by the force of the coil compression spring acting upon the piston

    Admiralty Litigation In Perpetuum: The Continuing Saga of Package Litigation and Third World Delivery Problems

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    Certain admiralty cargo issues are litigated frequently, often in search of a magical test which will preclude all further litigation. Three such issues are package limitations, the burden of proving the condition and quantity of cargo stowed within containers, and the point at which the ocean carrier delivers cargo at discharge and thus completes its duties under the contract of carriage. Despite the frequency with which these issues have been litigated, significant disagreement remains among the circuit courts as to their proper resolution. This article will examine the current state of judicial uncertainty in these areas and the indications given by the courts as the positions most likely to be adopted in the future

    Exchange Rate Pass-through in the 1980s: The Case of U.S. Imports of Manufactures

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    macroeconomics, exchange rate, 1980s, manufactor imports

    Active rendezvous between a low-earth orbit user spacecraft and the Space Transportation System (STS) shuttle

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    Active rendezvous of an unmanned spacecraft with the Space Transportation System (STS) Shuttle is considered. The various operational constraints facing both the maneuvering spacecraft and the Shuttle during such a rendezvous sequence are discussed. Specifically, the actively rendezvousing user spacecraft must arrive in the generic Shuttle control box at a specified time after Shuttle launch. In so doing it must at no point violate Shuttle separation requirements. In addition, the spacecraft must be able to initiate the transfer sequence from any point in its orbit. The four-burn rendezvous sequence incorporating two Hohmann transfers and an intermediate phasing orbit as a low-energy solution satisfying the above requirements are discussed. The general characteristics of the four-burn sequence are discussed, with emphasis placed on phase orbit altitude and delta-velocity requirements. The planning and execution of such a sequence in the operational environment are then considered. Factor crucial in maintaining the safety of both spacecraft, such as spacecraft separation and contingency analysis, are considered in detail

    Implications of a 130 GeV Gamma-Ray Line for Dark Matter

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    Recent reports of a gamma-ray line feature at ~130 GeV in data from the Fermi Gamma-Ray Space Telescope have generated a great deal of interest in models in which dark matter particles annihilate with a sizable cross section to final states including photons. In this article, we take a model-independent approach, and discuss a number of possibilities for dark matter candidates which could potentially generate such a feature. While we identify several scenarios which could lead to such a gamma-ray line, these models are each fairly constrained. In particular, viable models require large couplings (g>1-3), and additional charged particles with masses in the range of approximately ~130-200 GeV. Furthermore, lower energy gamma-ray constraints from the Galactic Center force us to consider scenarios in which the dark matter annihilates in the early universe through velocity-suppressed processes, or to final states which yield relatively few gamma-rays (such as electrons, muons or neutrinos). An exception to these conclusions can be found in models in which the dark matter annihilates to heavy intermediate states which decay to photons to generate a line-like gamma-ray spectrum.Comment: 7 pages, 4 figure

    Rapid Design of Gravity Assist Trajectories

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    Several International Solar Terrestrial Physics (ISTP) missions require the design of complex gravity assisted trajectories in order to investigate the interaction of the solar wind with the Earth's magnetic field. These trajectories present a formidable trajectory design and optimization problem. The philosophy and methodology that enable an analyst to design and analyse such trajectories are discussed. The so called 'floating end point' targeting, which allows the inherently nonlinear multiple body problem to be solved with simple linear techniques, is described. The combination of floating end point targeting with analytic approximations with a Newton method targeter to achieve trajectory design goals quickly, even for the very sensitive double lunar swingby trajectories used by the ISTP missions, is demonstrated. A multiconic orbit integration scheme allows fast and accurate orbit propagation. A prototype software tool, Swingby, built for trajectory design and launch window analysis, is described

    Development of a bedrest muscle stress apparatus

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    In attempting further to define the deleterious effects of spaceflight on the human body, measurement systems and techniques were devised to determine the loss of skeletal muscle strength and tone as a result of spaceflight exposure. In order to determine how the muscle degradation process progresses with time during nonuse, a system for measuring muscle stress during bedrest was developed. The Bedrest Muscle Stress Apparatus is configured to slip snugly over the foot board of a standard hospital bed. Data collected with this device correlated well with pre- and post-bedrest data collected with the original skeletal muscle stress apparatus

    Analytical and experimental study of the dynamics of a single-tube counterflow boiler

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    Experimental and analytical study of dynamics of single tube counterflow boile

    Assessing Causation in Breast Implant Litigation: The Role of Science Panels

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    In two recent cases, federal judges appointed panels of scientific experts to help assess conflicting scientific testimony regarding causation of systemic injuries by silicone gel breast implants. This article will describe the circumstances that gave rise to the appointments, the procedures followed in making the appointments and reporting to the courts, and the reactions of the participants in the proceedings
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