1,659 research outputs found

    Review of \u3ci\u3eBarnum Brown: The Man Who Discovered Tyrannosaurus rex.\u3c/i\u3e By Lowell Dingus and Mark A. Norell.

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    The book itself is well written, and follows Brown\u27s life chronologically from birth to death. Along the way, the narrative delves, sometimes quite deeply, into the people and events, both American and foreign, that would have influenced Brown\u27s life and work at the time. The reams of facts, figures, and dates in the book are meticulously referenced using the extensive archives of the AMNH. Brown was notorious for not keeping field notes, and correspondence to and from the field with his bosses, as well as annual reports, are the sources for most of the details of Brown\u27s life while associated with the Museum. Despite their efforts, the authors lament that aspects of Brown\u27s personal life and personality can really only be glimpsed from the writings of his two wives, his only daughter, and professional colleagues, leaving the man himself still a bit of a mystery

    Review of \u3ci\u3eBarnum Brown: The Man Who Discovered Tyrannosaurus rex.\u3c/i\u3e By Lowell Dingus and Mark A. Norell.

    Get PDF
    The book itself is well written, and follows Brown\u27s life chronologically from birth to death. Along the way, the narrative delves, sometimes quite deeply, into the people and events, both American and foreign, that would have influenced Brown\u27s life and work at the time. The reams of facts, figures, and dates in the book are meticulously referenced using the extensive archives of the AMNH. Brown was notorious for not keeping field notes, and correspondence to and from the field with his bosses, as well as annual reports, are the sources for most of the details of Brown\u27s life while associated with the Museum. Despite their efforts, the authors lament that aspects of Brown\u27s personal life and personality can really only be glimpsed from the writings of his two wives, his only daughter, and professional colleagues, leaving the man himself still a bit of a mystery

    Design and Characterization of Thin Stainless Steel Burst Disks for Increasing Two-Stage Light Gas Launcher Efficiency

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    Laser etched 300 series Stainless Steel Burst Disks (SSBD) ranging between 0.178 mm (0.007-in.) and 0.508mm (0.020-in.) thick were designed for use in a 17-caliber two-stage light gas launcher. First, a disk manufacturing method was selected using a combination of wire electrical discharge machining (EDM) to form the blank disks and laser etching to define the pedaling fracture pattern. Second, a replaceable insert was designed to go between the SSDB and the barrel. This insert reduced the stress concentration between the SSBD and the barrel, providing a place for the petals of the SSDB to open, and protecting the rifling on the inside of the barrel. Thereafter, a design of experiments was implemented to test and characterize the burst characteristics of SSBDs. Extensive hydrostatic burst testing of the SSBDs was performed to complete the design of experiments study with one-hundred and seven burst tests. The experiment simultaneously tested the effects of the following: two SSBD material states (full hard, annealed); five SSBD thicknesses 0.178, 0.254, 0.305, 0.381 mm (0.007, 0.010, 0.012, 0.015, 0.020-in.); two grain directions relative); number of times the laser etch pattern was repeated (varies between 5-200 times); two heat sink configurations (with and without heat sink); and, two barrel configurations (with and without insert). These tests resulted in the quantification of the relationship between SSBD thickness, laser etch parameters, and desired burst pressure. Of the factors investigated only thickness and number of laser etches were needed to develop a mathematical relationship predicting hydrostatic burst pressure of disks using the same barrel configuration. The fracture surfaces of two representative SSBD bursts were then investigated with a scanning electron microscope, one burst hydrostatically in a fixture and another dynamically in the launcher. The fracture analysis verified that both burst conditions resulted in a ductile overload failure indicated by transgranular microvoid coalescence, non-fragmenting rupture and mixed tensile and shear failure modes, regardless of the material states tested. More testing is underway to determine the relationship between SSBD burst pressure and projectile velocity

    A quantum measure of coherence and incompatibility

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    The well-known two-slit interference is understood as a special relation between observable (localization at the slits) and state (being on both slits). Relation between an observable and a quantum state is investigated in the general case. It is assumed that the amount of ceherence equals that of incompatibility between observable and state. On ground of this, an argument is peresented that leads to a natural quantum measure of coherence, called "coherence or incompatibility information". Its properties are studied in detail making use of 'the mixing property of relative entropy' derived in this article. A precise relation between the measure of coherence of an observable and that of its coarsening is obtained and discussed from the intutitive point of view. Convexity of the measure is proved, and thus the fact that it is an information entity is established. A few more detailed properties of coherence information are derived with a view to investigate final-state entanglement in general repeatable measurement, and, more importantly, general bipartite entanglement in follow ups of this study.Comment: 19 GS pages; supercedes quant-ph/030921

    Controlling Buffeting Loads by Rudder and Piezo-Actuation

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    High performance aircraft, especially those with twin vertical tails, encounter unsteady buffet loads when flying at high angles of attack. These stochastic loads result in significant stresses, which may cause fatigue damage leading to restricted capabilities and availability of the aircraft. An international collaborative research activity among Australia, Canada and the United States, conducted under the auspices of The Technical Cooperation Program (TTCP) contributed resources toward a program that coalesced a broad range of technical knowledge and expertise into a single investigation to demonstrate the enhanced performance and capability of the advanced active Buffet Load Alleviation ( ) control system in preparation for a flight test demonstration. The research team investigated the use of active structural control to alleviate the damaging structural response to these loads by applying advanced directional piezoelectric actuators, the aircraft rudder, switch mode amplifiers, and advanced control strategies on an F/A-18 aircraft empennage. Some results of the full-scale investigation are presented herein

    Actively Controlling Buffet-Induced Excitations

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    High performance aircraft, especially those with twin vertical tails, encounter unsteady buffet loads when flying at high angles of attack. These loads result in significant random stresses, which may cause fatigue damage leading to restricted capabilities and availability of the aircraft. An international collaborative research activity among Australia, Canada and the United States, conducted under the auspices of The Technical Cooperation Program (TTCP) contributed resources toward a program that coalesced a broad range of technical knowledge and expertise into a single investigation to demonstrate the enhanced performance and capability of the advanced active BLA control system in preparation for a flight test demonstration. The research team investigated the use of active structural control to alleviate the damaging structural response to these loads by applying advanced directional piezoelectric actuators, the aircraft rudder, switch mode amplifiers, and advanced control strategies on an F/A-18 aircraft empennage. Some results of the full-scale investigation are presented herein

    A high-performance speech neuroprosthesis

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    Speech brain-computer interfaces (BCIs) have the potential to restore rapid communication to people with paralysis by decoding neural activity evoked by attempted speech into tex

    Human Factors Analysis to Improve the Processing of Ares-1 Launch Vehicle

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    This slide presentation reviews the use of Human Factors analysis in improving the ground processing procedures for the Ares-1 launch vehicle. The light vehicle engineering designers for Ares-l launch vehicle had to design the flight vehicle for effective, efficient and safe ground operations in the cramped dimensions in a rocket design. The use of a mockup of the area where the technician would be required to work proved to be a very effective method to promote the collaboration between the Ares-1 designers and the ground operations personnel
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