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41.
ABSTRACT. The excessive and unsustainable exploitation of our marine resources has led to the promotion of marine reserves as a fisheries management tool. Marine reserves, areas in which fishing is restricted or prohibited, can offer opportunities for the recovery of exploited stock and fishery enhancement. In this paper we examine the contribution of fully protected tropical marine reserves to fishery enhancement by modeling marine reserve‐fishery linkages. The consequences of reserve establishment on the long‐run equilibrium fish biomass and fishery catch levels are evaluated. In contrast to earlier models this study highlights the roles of both adult (and juvenile) fish migration and larval dispersal between the reserve and fishing grounds by employing a spawner‐recruit model. Uniform larval dispersal, uniform larval retention and complete larval retention combined with zero, moderate and high fish migration scenarios are analyzed in turn. The numerical simulations are based on Mombasa Marine National Park, Kenya, a fully protected coral reef marine reserve comprising approximately 30% of former fishing grounds. Simulation results suggest that the establishment of a fully protected marine reserve will always lead to an increase in total fish biomass. If the fishery is moderately to heavily exploited, total fishery catch will be greater with the reserve in all scenarios of fish and larval movement. If the fishery faces low levels of exploitation, catches can be optimized without a reserve but with controlled fishing effort. With high fish migration from the reserve, catches are optimized with the reserve. The optimal area of the marine reserve depends on the exploitation rate in the neighboring fishing grounds. For example, if exploitation is maintained at 40%, the ‘optimal’ reserve size would be 10%. If the rate increases to 50%, then the reserve needs to be 30% of the management area in order to maximize catches. However, even in lower exploitation fisheries (below 40%), a small reserve (up to 20%) provides significantly higher gains in fish biomass than losses in catch. Marine reserves are a valuable fisheries management tool. To achieve maximum fishery benefits they should be complemented by fishing effort controls.  相似文献   
42.
Relying on reliability growth testing to improve system designis neither usually effective nor efficient. Instead it is importantto design in reliability. This requires models to estimate reliabilitygrowth in the design that can be used to assess whether goalreliability will be achieved within the target timescale forthe design process. Many models have been developed for analysisof reliability growth on test, but there has been much lessattention given to reliability growth in design. This paperdescribes and compares two models: one motivated by the practicalengineering process; the other by extending the reasoning ofstatistical reliability growth modelling. Both models are referencedin the recently revised edition of international standard IEC61164. However, there has been no reported evaluation of theirproperties. Therefore, this paper explores the commonalitiesand differences between these models through an assessment oftheir logic and their application to an industrial example.Recommendations are given for the use of reliability growthmodels to aid management of the design process and to informproduct development.  相似文献   
43.
Statistical Inference with Fractional Brownian Motion   总被引:3,自引:1,他引:2  
We give a test between two complex hypothesis; namely we test whether a fractional Brownian motion (fBm) has a linear trend against a certain non-linear trend. We study some related questions, like goodness-of-fit test and volatility estimation in these models.  相似文献   
44.
数据通信网综合网管的设计分析   总被引:3,自引:0,他引:3  
结合TMN电信管理网的体系结构.对数据通信网综合网管的结构和功能进行了分析。  相似文献   
45.
As a result of the increased switching complexity of many communications satellites, often transponders are available with a variety of configuration options offering flexibility in power, bandwidth, and coverage. Many of these configurations share resources that prevent them from being simultaneously active, making it a challenge to understand and manage the satellite capacity inventory. In this paper we define the logical channel configuration (LCC) as an unambiguous unit of the inventory and present a novel method of modelling the interdependencies between these LCCs using linear algebra. In particular, a projector matrix is defined which can be used to update the activation state of all LCCs when the state of one or more of these is changed. As a result, a number of valid LCC scenarios can be easily generated and evaluated for optimal use of the satellite resources. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
46.
3-D MCM封装技术及其应用   总被引:1,自引:0,他引:1  
介绍了超大规模集成电路(VLSI)用的3-D MCM封装技术的最新发展,重点介绍了3-D MCM封装垂直互连工艺,分析了3-D MCM封装技术的硅效率、复杂程度、热处理、互连密度、系统功率与速度等问题,并对3-D MCM封装的应用作了简要说明。  相似文献   
47.
介绍了基于西门子楼宇自控系统的空调计费系统的软硬件设计和具体实现.该系统的特点是借助西门子S600系统强大的数据处理和控制能力,采用时间记录和能量测量相结合的方法进行计费,具有实时监测和定时输出报表功能.该系统计量准确、计费合理、安全可靠、性价比高,满足了现代物业管理的需要.  相似文献   
48.
TCP/IP网络的动态模型描述   总被引:2,自引:0,他引:2  
拥塞现象成为TCP/IP网络发展面临的一个重要问题。因此,拥塞控制对TCP/IP网络的鲁棒性和稳定性具有重要作用。目前,网络拥塞控制策略主要包括两类:端到端的控制机制,如TCP拥塞控制算法;网络内部的主动队列管理(AQM)策略。但由于缺乏对网络系统动态特性的了解,这些拥塞控制策略大都基于专家经验,并没有建立完整的理论分析框架。为此,本文从数据流的角度出发,通过建立网络基本单元状态方程模型来实现IP网络系统的数学解析模型,然后用混杂系统来描述TCP带有拥塞控制策略的数据传输过程,建立了TCP/IP网络的动态模型,为网络系统中动态性能的分析、拥塞控制策略的设计奠定了基础。实验结果表明,该数学模型与NS仿真实验的结果相一致。  相似文献   
49.
带有回报计划的动态客户关系管理模型及实验应用分析   总被引:1,自引:0,他引:1  
在客户最大化效用及公司最大化CLV的动态环境下。对所提的带有回报计划的动态客户关系管理模型用于某超市的客户数据库中,发现模型的结果对这类客户是适用的。并给出了不同的客户状态空间对应的有效营销组合策略。结果表明:合适的回报计划可以促进客户的购买、提高公司的利润及缓解价格竞争。回报极限应该比客户的平均购买水平偏高,回报率应该与回报极限的改变方向一致。计划的时间范围应定在一年左右比较合适。对于累积购买水平较高的客户一般不邮寄商品信息。在回报计划的初期与末期不用打折。中期对那些购买次数很少的客户可以实行相应的降价策略。  相似文献   
50.
管理中的Nash平衡与Braess悖论现象   总被引:3,自引:0,他引:3  
本给出了交通规划、经济贸易以及其它管理中的一些Nash平衡和Braess悖论实例,分析了Nash平衡和Braess悖论现象及其本质特征,指出它们在管理工作中具有普遗性和潜在应用性。  相似文献   
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