9,711 research outputs found

    A superfluid helium system for an LST IR experiment

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    The results are presented of a study program directed toward evaluating the problems associated with cooling an LST instrument to 2 K for a year by using superfluid helium as the cooling means. The results include the parametric analysis of systems using helium only, and systems using helium plus a shield cryogen. A baseline system, using helium only is described. The baseline system is sized for an instrument heat leak of 50 mw. It contains 71 Kg of superfluid helium and has a total, filled weight of 217 Kg. A brief assessment of the technical problems associated with a long life, spaceborne superfluid helium storage system is also made. It is concluded that a one year life, superfluid helium cooling system is feasible, pending experimental verification of a suitable low g vent system

    A survey of mass analyzers

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    With the increasing applications of mass spectrometry technology to diverse services areas, a need has developed for a consolidated survey of the essential characteristics and features of the various instruments and techniques. This report is one approach to satisfying this need. Information has been collected and consolidated into a format which includes for each approach: (1) a general technique description, (2) instrument features information, and (3) a summary of pertinent advantages and disadvantages. With this information, the potential mass spectrometer user should be able to more efficiently select the most appropriate instrument

    Aerodynamic performance of a 1.20-pressure ratio fan stage designed for low noise

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    The aerodynamic design and the overall blade element performance of a 51 centimeter diameter fan stage is presented. The stage was designed to minimize the noise generated by rotor stator interactions. The design pressure ratio was 1.20 at a flow of 30.6 kilograms per second and a rotor blade tip speed of 228.6 meters per second. At design speed the rotor peak efficiency was 0.935. The peak efficiency of the stage, however, was 0.824. The radial distribution of rotor performance parameters at peak efficiency and design speed indicated excellent agreement with design values

    Performance of a transonic fan stage designed for a low meridional velocity ratio

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    The aerodynamic performance and design parameters of a transonic fan stage are presented. The fan stage was designed for a meridional velocity ratio of 0.8 across the tip of the stage, a pressure ratio of 1.57, a flow of 29.5 kilograms per second, and a tip speed of 426 meters per second. Radial surveys were obtained over the stable operating range from 50 to 100 percent of design speed. The measured, peak efficiency (0.81) of the stage occurred at a pressure ratio of 1.58 and a flow of 28.7 kilograms per second

    Aerodynamic performance of 0.4066-scale model of JT8D refan stage with S-duct inlet

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    A scale model of the JT8D refan stage was tested with a scale model of the S-duct inlet design for the refanned Boeing 727 center engine. Detailed survey data of pressures, temperatures, and flow angles were obtained over a range of flows at speeds from 70 to 97 percent of design speed. Two S-duct configurations were tested; one with a bellmouth inlet and the other with a flight lip inlet. The results indicated that the overall performance was essentially unaffected by the distortion generated by the S-duct inlet. The stall weight flow increased by less than 0.5 kg/sec (approximately 1.5% of design flow) with the S-duct inlet compared with that obtained with uniform flow. The detailed measurements indicated that the inlet guide vane (IGV) significantly reduced circumferential variations. For example, the flow angles ahead of the IGV were positive in the right half of the inlet and negative in the left half. Behind the IGV, the flow angles tended to be more uniform circumferentially

    Effect of casing treatment on performance of an inlet stage for a transonic multistage compressor

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    An inlet stage of a transonic compressor was tested with three rotor tip casing treatment configurations: blade angle slots, circumferential grooves, and axial skewed slots. Significant increases in both rotor and stage total pressure ratio, total temperature ratio, efficiency, flow range, and very large improvements in stall margin were obtained with all three casing treatment configurations. The greatest improvement in performance was achieved with axial skewed slots

    Performance of a low-pressure fan stage with reverse flow

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    The reverse flow aerodynamic performance of a 51-centimeter-diameter fan stage is presented. The stage was tested with the variable pitch rotor blades set through feather at -75 deg, -80 deg, and -85 deg from design setting angle. Of the three tested the stage with the rotor blades set at -75 deg exhibited the highest pressure ratio and highest flow. For all three configurations, there was little or no flow in the inner third of the exit passage due to the rotor blade being almost perpendicular to the axial direction in the hub region

    ERISA: A Co-Fiduciary Has No Right to Contribution and Indemnity

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    Because retirement plans involve large amounts of money, large numbers of people, and fiduciaries with conflicts of interests, Congress designed ERISA to differ from traditional trust law to meet these specific needs and important policy concerns. Before ERISA, fiduciaries and employers often manipulated lack of oversight and conflict of interests to the detriment of the beneficiaries. ERISA raised the standards owed by fiduciaries and established a policing system that required professional fiduciaries to monitor non-professional fiduciaries, thereby forcing non-professional fiduciaries to leave the field or seek expert advice. These provisions created co-fiduciary liability by imputing the liability of the co-fiduciary to an innocent fiduciary and in general creating an atmosphere of transparency and security. Congress considered the possibility of contribution and indemnity in two limited applications. First, exculpation provisions under ERISA generally banned indemnity except in limited circumstances. Second, insurance provisions allowed a type of contribution, if the plan paid the premiums. The Supreme Court has remained true to the Congressional scheme and denied court implied contribution and indemnity. Parties to private pension plans have the power to specify the plan terms as set forth in ERISA and may allocate liabilities amongst themselves. If they choose not to change the terms, then the intent and purpose of ERISA should control the interpretation of the plan and the fiduciaries responsibilities of the plan

    Preliminary S-193 RADSCAT oceanographic data for Skylab 2

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    There are no author-identified significant results in this report
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