18,340 research outputs found

    Helium Saturation of Liquid Propellants

    Get PDF
    The research is in three areas which are: (1) techniques were devised for achieving the required levels of helium (He) saturation in liquid propellants (limited to monomethylhydrazine (MMH) and nitrogen tetroxide (NTO)); (2) the values were evaluated for equilibrium solubilities of He in liquid propellants as currently used in the industry; and (3) the He dissolved in liquid propellants were accurately measured. Conclusions drawn from these studies include: (1) Techniques for dissolving He in liquid propellants depending upon the capabilities of the testing facility (Verification of the quantity of gas dissolved is essential); (2) Until greater accuracy is obtained, the equilibrium solubility values of He in MMH and NTO as cited in the Air Force Propellant Handbooks should be accepted as standard (There are still enough uncertainties in the He saturation values to warrant further basic experimental studies); and (3) The manometric measurement of gas volume from a frozen sample of propellant should be the accepted method for gas analysis

    Low noise high performance 50nm T-gate metamorphic HEMT with cut-off frequency f<sub>T</sub> of 440 GHz for millimeterwave imaging receivers applications

    Get PDF
    The 50 nm m-HEMT exhibits extremely high f&lt;sub&gt;T&lt;/sub&gt;, of 440GHz, low F&lt;sub&gt;min&lt;/sub&gt; of 0.7 dB, associated gain of 13 dB at 26 GHz with an exceptionally high Id of 200 mA/mm and gm of 950 ms/mm at low noise biased point

    Does Foreign Direct Investment Promote Development?

    Get PDF
    What is the impact of foreign direct investment (FDI) on development? The answer is important for the lives of millions--if not billions--of workers, families, and communities in the developing world. The answer is crucial for policymakers in developing and developed countries, and in multilateral agencies. This volume gathers together the cutting edge of new research on FDI and host country economic performance and presents the most sophisticated critiques of current and past inquiries. It probes the limits of what can be determined from available evidence and from innovative investigative techniques. In addition, the book presents new results, concludes with an analysis of the implications for contemporary policy debates, and proposeds new avenues for future research.

    50-nm T-gate metamorphic GaAs HEMTs with f<sub>T</sub> of 440 GHz and noise figure of 0.7 dB at 26 GHz

    Get PDF
    GaAs-based transistors with the highest f/sub T/ and lowest noise figure reported to date are presented in this letter. A 50-nm T-gate In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As metamorphic high-electron mobility transistors (mHEMTs) on a GaAs substrate show f/sub T/ of 440 GHz, f/sub max/ of 400 GHz, a minimum noise figure of 0.7 dB and an associated gain of 13 dB at 26 GHz, the latter at a drain current of 185 mA/mm and g/sub m/ of 950 mS/mm. In addition, a noise figure of below 1.2 dB with 10.5 dB or higher associated gain at 26 GHz was demonstrated for drain currents in the range 40 to 470 mA/mm at a drain bias of 0.8 V. These devices are ideal for low noise and medium power applications at millimeter-wave frequencies

    50 nm GaAs mHEMTs and MMICs for ultra-low power distributed sensor network applications

    Get PDF
    We report well-scaled 50 nm GaAs metamorphic HEMTs (mHEMTs) with DC power consumption in the range 1-150 &#924;W/&#924; demonstrating f&lt;sub&gt;T&lt;/sub&gt; of 30-400 GHz. These metrics enable the realisation of ultra-low power (&lt;500 &#924;W) radio transceivers for autonomous distributed sensor network applications

    RadioAstron probes the ultra-fine spatial structure in the H2_2O maser emission in the star forming region W49N

    Full text link
    H2_2O maser emission associated with the massive star formation region W49N were observed with the Space-VLBI mission RadioAstron. The procedure for processing of the maser spectral line data obtained in the RadioAstron observations is described. Ultra-fine spatial structures in the maser emission were detected on space-ground baselines of up to 9.6 Earth diameters. The correlated flux densities of these features range from 0.1% to 0.6% of the total flux density. These low values of correlated flux density are probably due to turbulence either in the maser itself or in the interstellar medium.Comment: Accepted for publication in Advances in Space Researc
    corecore