2,756 research outputs found
The Space Shuttle Booster
An analysis and status report of Space Shuttle booster configuration design features is presented. In comparing stowed, fixed straight, and delta wing basic configurations; the delta wing approach with a canard has been selected. Wing planform shape and cross-section is strongly influenced by air breathing engine installation requirements rather than purely aerodynamic performance optimization
Space Shuttle Booster Configuration Features
Some of the major Space Shuttle configuration design features are considered. The scope of the discussion is limited to the booster stage of a two-stage, parallel mounted concept. The body shape is considered including cross sectional shape, fineness, and nose shape. The factors affecting wing and tail concept and sizing are discussed. The interrelationship between the critical vehicle balance requirements and the forward location of the airbreathing engines is considered. Finally, the booster and orbiter launch arrangement and its influence on performance and ground operations is reviewed. A summary of the trends in booster configuration design is presented
Determination of Traffic Parameters for the Prediction, Projection, and Computation of EWL’s
One of the first published methods for the structural design of highway pavements was called the Massachusetts Rule and was presented in the eighth annual report of the Massachusetts Highway Commission in 1901 (1). The essence of this procedure was a rather intuitive assumption concerning the distribution of vertical pressures beneath a loaded area. For design purposes, this required the selection of a design load which, since failure was assumed to be catastrophic and not cumulative, could be taken as the largest load that could reasonably be anticipated during the design life of the pavement. The prediction of such a design load was in itself a rather formidable task
The conservation significance of the biota of barrow island, western australia
Offshore islands are often important in conservation because of the presence of locally endemic species and for acting as refuges for native wildlife from the impacts of invasive species and inappropriate development. Barrow Island, a small, semi-arid island off the Pilbara coast of northwestern Australia, has maintained the integrity of its terrestrial and aquatic biota despite sporadic incursions by invasive species and the operation of commercial oil extraction and liquified natural gas processing for over 50 years. We collate information from a wide range of sources to provide a framework to inform the ongoing management of the terrestrial and aquatic fauna and flora species that have conservation significance on the island. These include endemic flora and fauna; species listed as threatened by state, national and international authorities; species that are rare or extinct in other parts of their original range; species of biogeographic significance; and migratory birds and marine fauna of national and international significance. In addition, Barrow Island has been of value in acting as a source area for translocations of vulnerable and endangered mammal species that have been eradicated in other parts of their range. The many species with conservation significance and their use in successful translocation programs demonstrates the island’s national and international importance for conservation. In addition, Barrow Island provides exemplary opportunities for research on effective co-management of development and conservation, on mitigation and prevention of the invasion and impacts of exotic species, and on the influence of historical biogeographic processes on the distributions and evolution of biota. © Royal Society of Western Australia 2019
Underwater acoustics research at the Woods Hole Oceanographic Institution, 1930-1960
Author Posting. © Acoustical Society of America, 2016. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Proceedings of Meetings on Acoustics 23 (2016): 070013, doi:10.1121/2.0000214.The Woods Hole Oceanographic Institution (WHOI) was founded in 1930, and throughout its
history has had a strong involvement in research into the science and applications of sound in the
ocean. In terms of a brief history, three eras stand out: (1) pre-WWII, (2) WWII, and (3) the
postwar years. This manuscript will focus on the history of the most influential and colorful, individuals
and stories that arose during the war years. Provided are personal reminiscences, technical report details,
and photos illustrating the achievements, and importance, in underwater sound research at WHOI during
that time.This work was supported by
ONR Grant N00014-14-1-0040/N00014-16-1-2361
PSPACE-Completeness of Reversible Deterministic Systems
We prove PSPACE-completeness of several reversible, fully deterministic
systems. At the core, we develop a framework for such proofs (building on a
result of Tsukiji and Hagiwara and a framework for motion planning through
gadgets), showing that any system that can implement three basic gadgets is
PSPACE-complete. We then apply this framework to four different systems,
showing its versatility. First, we prove that Deterministic Constraint Logic is
PSPACE-complete, fixing an error in a previous argument from 2008. Second, we
give a new PSPACE-hardness proof for the reversible `billiard ball' model of
Fredkin and Toffoli from 40 years ago, newly establishing hardness when only
two balls move at once. Third, we prove PSPACE-completeness of zero-player
motion planning with any reversible deterministic interacting -tunnel gadget
and a `rotate clockwise' gadget (a zero-player analog of branching hallways).
Fourth, we give simpler proofs that zero-player motion planning is
PSPACE-complete with just a single gadget, the 3-spinner. These results should
in turn make it even easier to prove PSPACE-hardness of other reversible
deterministic systems.Comment: 20 pages, 15 figure
WE3F-13 Pulse Power Enhancement using Mode Locked Arrays of Automatic Level Control Oscillators
Abstract-A millimeter wave pulse generation system using mode locked arrays of coupled automatic level control oscillators is analyzed. Previous analyses have shown that 90 degrees of coupling phase maximizes the entrainment region size, however this paper shows that pulse power can be significantly enhanced by choosing 0 degrees of coupling phase. A comparison of the entrainment size and phase sensitivity shows that for large arrays peak power enhancement can be utilized without a significant reduction in overall system robustness
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