Authors:KENT R. DAVEY; HOWARD E. JORDAN, RIGOBERTO J. RODRIGUEZ, ROBERT E. HEBNER Pages: 31 - 39 Abstract: The deleterious effect of full bridge rectifiers on the output of an AC generator deserves attention from the Naval community. The harmonics observed at the stator of the generator not only introduce hysteresis and eddy current losses, but voltage spikes that impact the life of the generator. The two primary factors compromising life are localized heating due to harmonics and voltage spikes that cause insulation failure through partial discharge. Induced eddy currents are proportional to frequency squared. PubDate: 2012-03-16T15:13:01.490771-05: DOI: 10.1111/j.1559-3584.2011.00193.x
Authors:PATRICIA HAMBURGER; DAVID MISKIMENS, SCOTT TRUVER Pages: 41 - 50 Abstract: Until recently, the Navy's approach to designing, engineering, and acquiring complex weapon systems did not routinely or completely include the human “warrior” as an integral part of the system. Rather, the Navy viewed systems as combinations of hardware and software. The results were often less‐than‐optimal capability and high life‐cycle cost—and, sometimes, even mission failure. Given the high rate of technological change and the need to rein in cost in the face of increasingly constrained budgets, the Navy and the other services have increasingly embraced the need to consider human‐performance capabilities and limitations up front and on an equal footing with hardware and software—as integral elements in both new‐acquisition and technology‐refresh programs. The US Submarine Force has championed human systems integration (HSI). HSI is a specialized engineering discipline that takes human limitations and capabilities fully into account to influence system design and engineering early in the research, development, and acquisition process, thereby helping to ensure the highest overall performance at the lowest total ownership cost. Implementation of HSI has involved new partnerships with unlikely partners such as the audio equipment company Bose, game‐makers, the visual‐reality industry, physiologists, and psychologists. Nowhere has this been more apparent than in the Virginia (SSN‐774)‐Class Nuclear Attack Submarine Program. PubDate: 2012-03-16T15:13:01.490771-05: DOI: 10.1111/j.1559-3584.2009.00198.x
Authors:MARK A. CAMPBELL; JOHN KREMPASKY, MICHAEL BOSWORTH Pages: 51 - 66 Abstract: This paper will examine the Global Fleet Station (GFS) concept, first proposed in the Naval Operations Concept 2006 and implemented since then through a variety of US Navy (USN) and US Coast Guard (USCG) humanitarian assistance and foreign military training cruises. First, we will explore GFS missions, and the capability and materiel requirements that are derived from them. Next, relying on lessons learned from recent USN and USCG GFS and GFS‐type cruises, and preliminary analysis of 20 US and foreign vessels potentially suitable for GFS missions, this paper will argue that to effectively implement GFS in a persistent, distributed, and affordable manner, greater attention must be given to ships specially built or modified for the mission, complemented by dual‐use legacy ships used as necessary in augmentation roles. It is important to recognize that emerging GFS requirements differ greatly from requirements for ships built for major combat operations, but that the resulting cost savings actually make this a cost‐effective and operationally effective trade‐off for the USN. PubDate: 2012-03-16T15:13:01.490771-05: DOI: 10.1111/j.1559-3584.2009.00228.x
Authors:RANDY MARTENS; MARK REMPEL Pages: 67 - 80 Abstract: Defense organizations within many nations (e.g., United States and Canada), use capability‐based planning (CBP) to guide their force development processes. A key element of the CBP process is testing current and proposed capabilities against force planning scenarios, particularly for asset evaluation. This analysis involves a wide range of capabilities, and thus is a multicriteria problem. Comparison of alternatives using multiple criteria is challenging, and often is assisted by aggregation techniques. Set in a naval context, this paper presents three high‐level capability aggregation techniques: the vector method, star plot method, and wedge method. Each method aggregates naval task group capabilities, with respect to a scenario, into three quantifiable measures: effectiveness, unmatched, and unused. As with numerous techniques, the effectiveness gauges the ability of a task group to meet a set of scenario requirements. The unmatched and unused measures yield insight into capability gaps, which is an important aspect of CBP. The unmatched metric measures scenario requirements that are not provided by a task group and the unused metric measures task group capabilities that are not required by a scenario. An application of the methods is presented, including a discussion of their strengths and weaknesses. Based on this work, it is concluded that the vector method is the best of the three presented. PubDate: 2012-03-16T15:13:01.490771-05:
Authors:ROBERT LATORRE; JULIO ARANA Pages: 81 - 89 Abstract: Amphibious vehicles and other blunt‐shaped floating vehicles encounter the problem of a large bow wave forming at high speeds. This wave formation is accompanied by higher resistance and at a critical speed results in bow submergence or swamping. A 1/4 scale model of a tracked amphibious vehicle was tested at speeds corresponding to 3–7 km/h full scale to investigate the phenomena. The experiment showed that at speeds of 5–6 km/h, there is a significant increase in the trim by the bow. The vehicle's “breakwater” plate was able to break up this wave and avoid swamping. Comparative tests with the vehicle fitted with the wave cancellation bow plate showed that this bow plate reduced the bow wave formation and achieved a 10% reduction in the towing resistance. The wave cancellation bow plate can reduce the vehicle's power and extend its amphibious operating range or increase its amphibious speed. PubDate: 2012-03-16T15:13:01.490771-05:
Authors:CHARLES GALLAGHER Pages: 91 - 98 Abstract: In 1989, Ingalls Shipbuilding contracted to design and construct three Sa'ar V Class corvettes for the Government of Israel. The available funding was considerably less than would have been needed to design and build equivalent ships for the US Navy. As a result, the Israeli Navy (IN) and Ingalls Shipbuilding, working closely together, implemented significant innovative systems engineering and design practices and the ships were delivered within the budget. Some of the key innovative design and engineering methods used during that program are described in this paper. PubDate: 2012-03-16T15:13:01.490771-05:
Authors:RICHARD C. MILLAR; DAVID H. OLWELL Pages: 99 - 107 Abstract: An earlier nonparametric statistical study of GE F414 engine removals from operational F/A‐18 aircraft in US Navy service provided insights into the lifetime patterns of engine removals for various causes. Inspection of the estimated hazard function for engine removals for foreign object damage (FOD) suggested that a parametric analysis using Erlang distributions might be fruitful, bolstered by a hypothesized relevance to the maintenance procedures governing engine removals for this cause, and their outcomes. The objective was both a better model to forecast engine removals and to provide insight into the number of FOD incidents it took to drive an engine removal. Gamma and Erlang distributions did better fit the removals data and provide a tool for predicting engine removals, aircraft availability impact, and the resultant maintenance workload. A parametric model using a cascade of Erlang functions was developed to simulate the combined FOD/line maintenance process, which provides insight into the outcomes expected under reasonable simplifying assumptions. This model predicts that the key research issue, the probability that a typical FOD event prompts a removal, cannot be estimated from engine removals data alone. Field data must be collected to gain understanding of the underlying frequency of FOD and the utility of the present inspection criteria. PubDate: 2012-03-16T15:13:01.490771-05: DOI: 10.1111/j.1559-3584.2011.00337.x
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