舰载无人直升机反潜任务载荷应用问题研究

任务载荷应用问题是舰载无人直升机作战使用研究的重要内容之一,本文从分析舰载无人直升机的发展现状和反潜任务载荷类型入手,通过引入模糊AHP法,提供了一种对该问题的解决思路,同时通过对设定战术背景下的反潜载荷应用方案进行优选,得出了结论,验证了方法的可行性和有效性.本文的研究方法及结论对实际训练和作战中的舰载无人机反潜载荷应用有重要的参考价值.     

On the convergence of iterative methods for the distribution balancing problem

A general distribution balancing problem, specified by the given outflows and inflows and the factorial form of its solution, is formulated. Solution uniqueness and boundedness is discussed—primarily in graph theoretical terms. An entropy maximisation problem, subject to general linear constraints, is transformed into an unconstrained optimisation problem by application of standard duality theory, and a relevant general convergence theorem for iterative solution methods is given. The optimum solution in a special case is identified with the flow solution. When expressed in flow variables, the dual objective has a unique and bounded optimum solution and is an appropriate unifying concept for measuring the rate of convergence of different solution methods. By regarding the balancing procedure as an iterative optimisation method, a new and simple proof of its convergence is given, together with some asymptotic results, which are also compared with those of Newton's method. It is pointed out that there are two different forms of Newton's method, according to the choice of variables—untransformed or transformed— in the original distribution balancing problem. When Newton's method is applied to the whole system of equations simultaneously, the trajectory of iterates is observed to depend on this variable choice. For the transformed variables it is noticed that the convergence with the balancing procedure is quicker than with Newton's method applied to the outflow- and inflow- equations, alternately. To guarantee global convergence with Newton's method and to increase the rate a supplementary linear search routine is recommended.     

Book review

Recreation: Marine Promise, Proceedings of the National Conference on Marine Recreation Susan H. Andersen, Ed., October 2–4, 1975, Newport Beach, California

Parable Beach: A Primer in Coastal Zone Economics by J. W. Devanney III, G. Ashe, and B. Parkhurst, The MIT Press, 1976, 99 pp.

Marine Recreational Fisheries, Proceedings of the First Annual Marine Recreational Fisheries Symposium Henry Clepper, ed., New Orleans, Louisiana, February 27, 1976.     

ASNE Delaware Valley Chapter Teaches Students Naval Engineering through the Sea Perch Underwater Robotics Program

Sea Perch is an underwater robotics program sponsored by the Office of Naval Research as part of the National Naval Responsibility for Naval Engineering aimed at recruiting the next generation of naval architects and marine engineers. ASNE Delaware Valley (DV) and Naval Surface Warfare Center, Philadelphia, embraced the outreach opportunity as an educational, challenging, and fun way to get kids excited about naval engineering. ASNE-DV has received an overwhelmingly positive feedback from both teachers and students. Teachers have said their students are excited to learn about remotely operated vehicles and cannot wait to work on their Sea Perch robots. During the past 3 years, ASNE-DV has teamed with Drexel University and the school district of Philadelphia to successfully implement a sustainable, local Sea Perch competition program for middle and high school students. ASNE-DV is encouraging expansion of the program to additional areas. This article discusses how the DV Sea Perch program evolved from two schools building the robots in the winter of 2005, to over 40 teams from a diverse range of schools participating in a Sea Perch competition in the spring of 2007.     

ELASTIC – A methodological framework for identifying and selecting sustainable transport indicators

There is significant reliance on sustainable transport indicators for monitoring and reporting progress towards sustainable transport. The selection of appropriate sustainability indicators presents a number of challenges however, not least because of the vast number of potential indicators available. To help address these challenges, this paper presents the Evaluative and Logical Approach to Sustainable Transport Indicator Compilation (ELASTIC) – a framework for identifying and selecting a small subset of sustainable transport indicators. ELASTIC is demonstrated with an application to the English Regions, UK.     

The environmental effects of airline carbon emissions taxation in the US

This study investigates how air traffic emissions taxes may impact carbon emissions in the US. The magnitude of emissions savings in the US domestic airline industry that would result from lower demand for air travel as taxes are levied and air fares increase is estimated. At the same time, the air-automobile substitution effect is considered and it is argued that some air travelers may divert to automobiles, thus increasing automobile carbon emissions. Both the analysis of the aggregate US domestic airline industry and the study of a sample of US domestic route markets indicate that potentially sizeable increases in automobile traffic and related emissions may substantially reduce the environmental benefits of air travel carbon emissions taxes. In some instances, carbon emissions may even increase in short-haul markets. Sensitivity analyses are performed to demonstrate the robustness of these findings.     

Statistical characterization of surfaces of corroded steel plates

The statistical characteristics of corroded steel plate surfaces exposed to marine environments are of interest for assessing longer term structural safety and integrity using probabilistic methods. This requires information about the variability of corrosion loss and pitting over surfaces. The present paper reports on the observed statistical character of the surfaces of 10 large (1.2 m × 0.8 m × 3 mm thick) steel plates exposed in temperate climate marine immersion, tidal and splash zones for 2.5 years. For the analysis the plates were cut into smaller segments that were mechanically scanned to obtain digitised surface topographies. These were then analysed to estimate the correlation structure and the standard deviation of the surface topography. Considerable differences were found for these and for the mean corrosion loss between different exposure zones. For any one segment the surface topography was found to be highly statistically dependent, implying that smaller coupon sizes can provide adequate estimates of corrosion loss. From this it may be inferred that the deepest pits are not statistically independent as commonly assumed in extreme value statistical representations.     

Current operational urban land‐use–transport modelling frameworks: A review

Various alternative frameworks are available for modelling urban land‐use–transport interaction. This paper provides a detailed review of six of these frameworks that have been or are currently being used to develop operational models. The intention is to indicate what is the general nature of the current state of practice and what is now available for practical modelling work in the area. The intention is also to compare the current state of practice with what might be the ideal in various respects. The six frameworks reviewed (ITLUP, MEPLAN, TRANUS, MUSSA, NYMTC‐LUM and UrbanSim) are considered in terms of their representations of physical systems, decision‐makers and processes, along with various more general modelling and implementation issues. None matches the ideal as envisaged here in all respects. However, a wide range of policy considerations can be handled explicitly with what is available, and more recent developments show an encouraging trend towards expansion in the scope of what can be considered. Further strengthening of the behavioural basis and relaxation of some of the more restrictive assumptions would appear to be both appropriate and likely in the future.     

Regional fishery management councils: The federal perspective

Abstract

Under the Magnuson Fishery Conservation and Management Act of 1976, the federal government cooperates with states, the fishing industry, and public constituencies to regulate fisheries. This paper notes changes in U.S. fisheries over the last decade, remarks on the effectiveness of the Act, and makes suggestions for an improved fishery management process.