Institution
Naval Postgraduate School
Education•Monterey, California, United States•
About: Naval Postgraduate School is a education organization based out in Monterey, California, United States. It is known for research contribution in the topics: Tropical cyclone & Nonlinear system. The organization has 5246 authors who have published 11614 publications receiving 298300 citations. The organization is also known as: NPS & U.S. Naval Postgraduate School.
Papers published on a yearly basis
Papers
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24 Jul 2005TL;DR: A water-resistant amphibious prototype design, based on the biologically-inspired Whegstrade platform, has been completed in this article, which allows the robot to navigate on rough terrain and underwater, and accomplish tasks with little or no low-level control.
Abstract: The capability of autonomous and semi-autonomous platforms to function in the shallow water surf zone is critical for a wide range of military and civilian operations. Of particular importance is the ability to transition between locomotion modes in aquatic and terrestrial settings. The study of animal locomotion mechanisms can provide specific inspiration to address these demands. In this work, we summarize on-going efforts to create an autonomous, highly mobile amphibious robot. A water-resistant amphibious prototype design, based on the biologically-inspired Whegstrade platform, has been completed. Through extensive field-testing, mechanisms have been isolated to improve the implementation of the Whegstrade concept and make it more suited for amphibious operation. Specific design improvements include wheel-leg propellers enabling swimming locomotion, an active, compliant, water resistant, non-backdrivable body joint, and improved feet for advanced mobility. These design innovations allow Whegstrade to navigate on rough terrain and underwater, and accomplish tasks with little or no low-level control, thus greatly simplifying autonomous control system implementation. Complementary work is underway for autonomous control. We believe these results can lay the foundation for the development of a generation of amphibious robots with an unprecedented versatility and mobility
140 citations
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TL;DR: The wind-sea part of the wave spectrum conforms to established growth curves for significant wave height and peak period, except at inner-shelf stations where a large along-shore windsea component was observed.
Abstract: Wind-sea generation was observed during two experiments off the coast of North Carolina. One event with offshore winds of 9–11 m s−1 directed 20° from shore normal was observed with eight directional stations recording simultaneously and spanning a fetch from 4 to 83 km. An opposing swell of 1-m height and 10-s period was also present. The wind-sea part of the wave spectrum conforms to established growth curves for significant wave height and peak period, except at inner-shelf stations where a large alongshore wind-sea component was observed. At these short fetches, the mean wave direction θm was observed to change abruptly across the wind-sea spectral peak, from alongshore at lower frequencies to downwind at higher frequencies. Waves from another event with offshore winds of 6–14 m s−1 directed 20°–30° from shore normal were observed with two instrument arrays. A significant amount of low-frequency wave energy was observed to propagate alongshore from the region where the wind was strongest. The...
139 citations
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TL;DR: An adaptive system which varies the sampling frequency by measuring a system parameter is made here and it is shown that a sampler followed by a zero-order hold whose sampling period is controlled by the absolute value of the first derivative of the error signal will be a more "efficient" sampler than a fixed-frequency sampler.
Abstract: Sampled-data control systems generally have fixed sampling frequencies which must be set high enough to give satisfactory performance for all anticipated conditions. A study is made here of an adaptive system which varies the sampling frequency by measuring a system parameter. It is shown that a sampler followed by a zero-order hold whose sampling period is controlled by the absolute value of the first derivative of the error signal will be a more "efficient" sampler than a fixed-frequency sampler. That is, over a given time interval, fewer samples are needed with the variable-frequency system than with a fixed-frequency system while maintaining essentially the same response characteristics. Analog computer studies of simple Type I and Type II sampled-data servo systems with error sampling and unity feedback verified the method. Standard analog computer components were used to set up a simulated servo system, a rate detector, absolute-value detector, a voltage-controlled oscillator, and a sampler and zero-order hold. The system described reduced the number of samples required for response to a step input to about three-quarters that required in a fixed-sampling-frequency system. Over a long period of time savings in the number of samples required can be expected to be between 25 and 50 per cent. In many applications the savings produced by reducing the over-all number of samples required may outweigh the added complexity of the adaptive-sampling-frequency system.
139 citations
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TL;DR: Very large subaqueous sand dunes were discovered on the upper continental slope of the northern South China Sea as discussed by the authors, where they were observed along a single 40 km long transect southeast of 21.93°N, 117.53°E in water depths of 160 to 600m.
139 citations
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TL;DR: The implementation of a hierarchical data structure on the world modeled by NPSNET utilizing quadtrees is explored, which requires the use of hierarchical data structures to provide high fidelity in real-time.
139 citations
Authors
Showing all 5313 results
Name | H-index | Papers | Citations |
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Mingwei Chen | 108 | 536 | 51351 |
O. C. Zienkiewicz | 107 | 455 | 71204 |
Richard P. Bagozzi | 104 | 347 | 103667 |
Denise M. Rousseau | 84 | 218 | 50176 |
John Walsh | 81 | 756 | 25364 |
Ming C. Lin | 76 | 370 | 23466 |
Steven J. Ghan | 75 | 207 | 25650 |
Hui Zhang | 75 | 200 | 27206 |
Clare E. Collins | 71 | 560 | 21443 |
Christopher W. Fairall | 71 | 293 | 19756 |
Michael T. Montgomery | 68 | 258 | 14231 |
Tim Li | 67 | 383 | 16370 |
Thomas M. Antonsen | 65 | 888 | 17583 |
Nadia Magnenat-Thalmann | 65 | 521 | 14850 |
Johnny C. L. Chan | 61 | 261 | 14886 |