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 & 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.

Measurement issues in performance-based logistics

Abstract: Performance Based Logistics (PBL) is an acquisition reform that is intended to improve weapon systems logistics by reducing cost, improving reliability, and reducing footprint. PBL is an extension of a broad process of rationalizing and, in many cases, outsourcing government services. As with other examples of governmental service outsourcing, measurement issues arise in the gap between governmental objectives and service measurement, and in the contrast between clear profit-centered vendor metrics, and more complex mission-oriented governmental metrics. Beyond this, however, PBL presents new challenges to the relationship between governmental agencies and their service vendors. In many cases, weapons systems logistical support involves levels of operational risk that are more difficult to measure and more difficult to value than other government services. We discuss the implications of operational risk and other measurement issues on PBL implementation.

Enhanced cellular preservation by clay minerals in 1 billion-year-old lakes.

Abstract: Organic-walled microfossils provide the best insights into the composition and evolution of the biosphere through the first 80 percent of Earth history. The mechanism of microfossil preservation affects the quality of biological information retained and informs understanding of early Earth palaeo-environments. We here show that 1 billion-year-old microfossils from the non-marine Torridon Group are remarkably preserved by a combination of clay minerals and phosphate, with clay minerals providing the highest fidelity of preservation. Fe-rich clay mostly occurs in narrow zones in contact with cellular material and is interpreted as an early microbially-mediated phase enclosing and replacing the most labile biological material. K-rich clay occurs within and exterior to cell envelopes, forming where the supply of Fe had been exhausted. Clay minerals inter-finger with calcium phosphate that co-precipitated with the clays in the sub-oxic zone of the lake sediments. This type of preservation was favoured in sulfate-poor environments where Fe-silicate precipitation could outcompete Fe-sulfide formation. This work shows that clay minerals can provide an exceptionally high fidelity of microfossil preservation and extends the known geological range of this fossilization style by almost 500 Ma. It also suggests that the best-preserved microfossils of this time may be found in low-sulfate environments.

Application of the Godunov method and its second-order extension to cascade flow modeling

Abstract: The Godunov method and a new second-order accurate extension of the method are used for the solution of two-dimensional Euler equations. Both numerical schemes are described in detail. Their performances in the subsonic, transonic, and supersonic flow regimes are first tested on the problem of flow in a channel with a circular arc bump. The niethods are then applied to calculate the transonic flow through a supercritical com­ pressor cascade designed by J. Sanzo For this case, the solution with the second-order extension of the Godunov method gives verygood agreement with the design distribution of parameters given by Sanzo

Optimizing Submarine Berthing with a Persistence Incentive

Abstract: Submarine berthing plans reserve mooring locations for inbound U.S. Navy nuclear submarines prior to their port entrance. Once in port, submarines may be shifted to different berthing locations to allow them to better receive services they require or to make way for other shifted vessels. However, submarine berth shifting is expensive, labor inten- sive, and potentially hazardous. This article presents an optimization model for submarine berth planning and demonstrates it with Naval Submarine Base, San Diego. After a berthing plan has been approved and published, changed requests for services, delays, and early arrival of inbound submarines are routine events, requiring frequent revisions. To encourage trust in the planning process, the effect on the solution of revisions in the input is kept small by incorporating a persistence incentive in the optimization model. q 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 301 - 318, 1997. Although the Cold War has ended, United States Navy submarines remain very capable and effective ships of war: A smaller number of submarines operated from fewer submarine bases will continue to play a significant role in national defense. The wise use of time and resources while submarines are in port will improve the state of readiness of a smaller fleet. While in port, a submarine completes preventive and corrective maintenance, replenishes stores, and conducts training and certification tests to maintain high material and personnel readiness. Ideally, a submarine in port should devote its time exclusively to these activities. However, submarines frequently spend time shifting berths. Some shifts are necessary and some are not. Services such as ordnance loading and the use of special maintenance equip- ment require that a submarine be moored at a specific location. During periodic maintenance upkeep, personnel from a submarine tender assist the submarine crew, and berthing near the tender is preferable. During training, inspection, and other periods, it is desirable to berth closer to shore, near squadron offices and training facilities. When conditions permit,