Naval Postgraduate School

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 & Boundary layer. 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.

QuikSCAT Satellite Comparisons with Nearshore Buoy Wind Data off the U.S. West Coast

Abstract: To determine the accuracy of nearshore winds from the QuikSCAT satellite, winds from three satellite datasets (scientifically processed swath, gridded near-real-time, and gridded science datasets) were compared to those from 12 nearshore and 3 offshore U.S. West Coast buoys. Satellite observations from August 1999 to December 2000 that were within 25 km and 30 min of each buoy were used. Comparisons showed that satellite–buoy wind differences near shore were larger than those offshore. Editing the satellite data by discarding observations recorded in rain and those recorded in light winds improved the accuracy of all three datasets. After removing rain-flagged data and wind speeds less than 3 m s−1, root-mean-squared differences (satellite minus buoy) for swath data, the best of the three datasets, were 1.4 m s−1 and 37° based on 5741 nearshore comparisons. By removing winds less than 6 m s−1, these differences were reduced to 1.3 m s−1 and 26°. At the three offshore buoys, the root-mean-squared ...

Concepts, Theory, and Techniques PRINCIPLES OF MULTIOBJECTIVE OPTIMIZATION*

Abstract: This paper attempts to isolate and analyze the principal ideas of multiobjective optimization. We do this without casting aspersions on single-objective optimization or championing any one multiobjective technique. We examine each fundamental idea for strengths and weaknesses and subject two—efficiency and utility—to extended consideration. Some general recommendations are made in light of this analysis. Besides the simple advice to retain single-objective optimization as a possible approach, we suggest that three broad classes of multiobjective techniques are very promising in terms of reliably, and believably, achieving a most preferred solution. These are: (1) partial generation of the efficient set, a rubric we use to unify a wide spectrum of both interactive and analytic methods; (2) explicit utility maximization, a much-overlooked approach combining multiattribute decision theory and mathematical programming; and (3) interactive implicit utility maximization, the popular class of methods introduced by Geoffrion, Dyer, and Feinberg [24] and extended significantly by others.

Rip spacing and persistence on an embayed beach

Abstract: [1] Four years of daily time exposure images from an embayed beach were examined to study the spacing, persistence, and location preferences of rips in a natural rip channel system. A total of 5271 rip channels was observed on 782 days. Occurrence statistics showed no evidence of the preferred location pattern associated with standing edge waves trapped in an embayed beach. The histogram of rip spacing, the primary diagnostic observable for most models, was well modeled by a lognormal distribution (mean spacing of 178 m). However, spacings were highly longshore variable (time mean of the standard deviation/longshore mean of rip spacing was 39%), so they are of questionable merit as a diagnostic variable. Storm-driven resets to the longshore uniform condition required by most models occurred only four times per year on average, making rip generation models relevant to only a small fraction of the system behavior. Rip spacings after the 15 observed reset events were uncorrelated with bar crest distance. The lifetime of the 324 individual rip channel trajectories averaged 45.6 days. Rips were equally mobile in both longshore directions, but the coefficient of variation of rip migration rates was large, even for high migration rates. The mean migration rate was well correlated to a proxy for the longshore current (R2 of 0.78). Thus there is no significant evidence that the formation, spacing, and migration of rip channels on this beach can be explained by currently existing simple models. Moreover, the alongshore uniform initial conditions assumed by these models are rare on Palm Beach, making the models generally inapplicable.