2,065 research outputs found

    The Long-term Illinois River fish population monitoring program, Annual Report

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    Report issued on: March 2003Annual ReportINHS Technical Report prepared for Illinois Department of Natural Resource

    The noise environment of a school classroom due to the operation of utility helicopters

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    Noise measurements under controlled conditions have been made inside and outside of a school building during flyover operations of four different helicopters. The helicopters were operated at a condition considered typical for a police patrol mission. Flyovers were made at an altitude of 500 ft and an airspeed of 45 miles per hour. During these operations acoustic measurements were made inside and outside of the school building with the windows closed and then open. The outside noise measurements during helicopter flyovers indicate that the outside db(A) levels were approximately the same for all test helicopters. For the windows closed case, significant reductions for the inside measured db(A) values were noted for all overflights. These reductions were approximately 20 db(A); similar reductions were noted in other subjective measuring units. The measured internal db(A) levels with the windows open exceeded published classroom noise criteria values; however, for the windows-closed case they are in general agreement with the criteria values

    A history of Bahamian education

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    The Bahamas were annexed by the Crown in 1629 but, for a century, there was no progressive settlement, Early in the eighteenth century the island s were abandoned to the nefarious activities of pirates. Government reverted t o the Crown in 1718 and ordered development began. Education of the children of the colonists was begun in 1734 by the Society for the Propagation of the Gospel but State aid was given as early as 1746. Little progress was made for a century but the advent of loyalists from the American Colonies in 1784 had a beneficial influence. With the need f o r educating the liberated slaves a Board of Education was appointed in 1836. There ensued a denominational struggle for control which was resolved by removing the schools from the control of all the churches. At the same time an Inspector was appointed but progress was hindered by lack of teachers and money and by the geographical nature of the colony. Blockade-running during the American Civil war made more money available and a series of inspectors and teachers was appointed from England. Slow but steady progress was effected, the " British Schools" being adopted as a model, Compulsory attendance became universal in 1886 but the number of schools remained totally in sufficient until 1920. Income from boot-legging during American prohibition resulted in rapid expansion both in the number of primary schools and in the provision of secondary education for negroes. The last twenty years have witnessed improvement in teachers' qualifications and the provision of scholarships for higher education. The out islands are far behind Nassau in educational facilities which are uncoordinated in the colony as a whole. Introductory chapters furnish a background of general history and of conditions in the colony at present. Final chapter applies the lessons of history to educational policy for the future

    Results of the flight noise measurement program using a standard and modified SH-3A helicopter

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    A field noise measurement program has been conducted using both a standard SH-3A helicopter and an SH-3A helicopter modified to reduce external noise levels. Modifications included reducing rotor speed, increasing the number of rotor blades, modifying the blade-tip shapes, and acoustically treating the engine air intakes and exhaust. The purpose of this study was to document the noise characteristics recorded on the ground of each helicopter during flyby, hover, landing, and take-off operations. Based on an analysis of the measured results, the average of the overhead, overall, ontrack noise levels was approximately 4 db lower for the modified helicopter than for the standard helicopter. The improved in-flight noise characteristics, and associated small footprint areas and time durations, were judged to be mainly due to tail-rotor noise reductions. The noise reductions were obtained at the expense of required power increases at airspeeds greater than 70 knots for the modified helicopter

    Hidden gauge structure and derivation of microcanonical ensemble theory of bosons from quantum principles

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    Microcanonical ensemble theory of bosons is derived from quantum mechanics by making use of a hidden gauge structure. The relative phase interaction associated with this gauge structure, described by the Pegg-Barnett formalism, is shown to lead to perfect decoherence in the thermodynamics limit and the principle of equal a priori probability, simultaneously.Comment: 10 page

    Flyover noise characteristics of a tilt-wing V/STOL aircraft (XC-142A)

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    A field noise measurement investigation was conducted during the flight testing of an XC-142A tilt-wing V/STOL aircraft to define its external noise characteristics. Measured time histories of overall sound pressure level show that noise levels are higher at lower airspeeds and decrease with increased speed up to approximately 160 knots. The primary noise sources were the four high-speed, main propellers. Flyover-noise time histories calculated by existing techniques for propeller noise prediction are in reasonable agreement with the experimental data

    Schwinger, Pegg and Barnett and a relationship between angular and Cartesian quantum descriptions

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    From a development of an original idea due to Schwinger, it is shown that it is possible to recover, from the quantum description of a degree of freedom characterized by a finite number of states (\QTR{it}{i.e}., without classical counterpart) the usual canonical variables of position/momentum \QTR{it}{and} angle/angular momentum, relating, maybe surprisingly, the first as a limit of the later.Comment: 7 pages, revised version, to appear on J. Phys. A: Math and Ge
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