一种安全的LEACH路由算法

在研究低功耗自适应集簇分层型路由协议的基础上,从路由安全的攻防角度入手,分析现有各种路由攻击手段的原理、特点及危害,提出一种基于身份认证的密钥协商安全防范密钥管理对策,同时利用秘密共享技术防范关键点攻击,为无线传感器网络安全路由的设计与实现提供一个可行的方案。     

基于排列图的优化广播报文算法

文章就一种特殊的图——排列图的广播算法展开讨论。首先,给出了关于排列图的一些定义。根据排列图的定义,可以知道排列图的结构具有层次性。从这一点出发,作者得出一个把排列图分成一些子图,在子图中分别广播报文的递归算法。之后,作者考虑时间复杂度和报文复杂度,得出递归算法的两点改进。最后,给出了最后的广播算法。     

一种排样图像轮廓线生成方法

针对传统基于聚合的多边形拟合法对皮革图像边缘毛刺敏感和对所围面积无法控制的问题,提出了一种排样图像的轮廓线生成方法。该方法通过将距离误差由绝对值改为带符号值,并对非利用面积误差施加约束,使获得的排样轮廓线既抑制了毛刺的干扰,又是真实轮廓线的最大内接多边形,皮料面积得到了充分利用。实例计算和应用结果表明了本文方法的有效性和科学合理性,且对其他工业排样问题也具有一定的参考价值。     

River basin water resources management in China: a legal and institutional assessment

China's rivers face major challenges arising from social and economic development, particularly associated with pollution and over-abstraction. Although these issues vary significantly across the country, China has adopted a national, unified approach to manage water resources in a river basin context. This paper assesses the legal and institutional arrangements for river basin management in terms of decentralization and centralization. It considers the appropriate roles for the different levels of government, including providing for participation and integration across these levels. It proposes strengthening institutional development and capacity building in the future.     

Flow characteristics of the two tandem wavy cylinders and drag reduction phenomenon

This paper presents an extensive numerical study of 3-D laminar flow around two wavy cylinders in the tandem arrangement for spacing ratios (L/Dm ) ranging from 1.5 to 5.5 at a low Reynolds number of 1...     

吉沙水电站施工总布置设计

吉沙水电站为长引水式电站,主要由混凝土闸坝、水道系统和地面厂房等组成,根据枢纽布置特点及施工支洞布置方案,结合工程实际情况,并考虑其他因素,施工总布置采用集中与分散相结合的布置方式。经过施工实践检验,设计规划的施工总布置方案满足工程建设的需要。     

分布器结构对气固鼓泡流化床内气相分布影响的数值模拟

根据双流体模型,利用计算流体力学软件Fluent 6.3,在布风板开孔率Φ=3.86%时,对6种布孔方式不同的流化床中气相的分布特性进行了数值模拟,得到了各布孔条件下气相分布规律。结果显示,均匀布孔流化床内产生大量的气泡,气泡分布不均且存在大片流化率很低的区域。在各不均匀布孔流化床中,大小孔间隔排布布风板流化床(E型布风板流化床)内产生的气泡相对较小且分散性较好,气相速度矢量分布较分散均一,流化效果最好。与均匀布孔流化床相比,E型布风板的流化床轴向气相压力脉动更小,径向等压线分布更平缓,表现出轴向和径向气相分布更均匀,对鼓泡流化床的优化设计最有参考价值。     

冷却孔复合角和排列方式综合作用对平板气膜冷却效果的影响

研究复合角和排列方式综合作用对平板气膜冷却效果的影响。采用数值模拟的方法,保持射流圆孔尺寸、间距及倾斜角不变,分别对四种孔阵的平板气膜冷却进行了流动和传热的分析。利用Realizable k-ε湍流模型,标准壁面函数边界处理和SIMPLE算法,分析速度、涡量、冷却效率,对比冷却孔复合角和排列方式综合作用对平板气膜冷却效果的影响。结果显示:复合角和叉排同时存在时可改善平板展向上的冷却效果,而在平板流向上对冷却效果的影响不明显。结合吹风比得出较优的孔排方式。     

舰船总布置方案的直觉模糊多属性群决策模型

在舰船总布置方案决策问题中,为了得到总体一致的结论,往往需要专家经过反复的协商和妥协来实现,从有利于舰船作战使用的角度,提出了总布置方案评价的指标体系.为了克服决策过程中需要通过来自不同专业领域的专家反复协商来使专家决策信息达到可接受的一致性不仅耗时且可操作性差的问题,引入了基于自适应一致性算法的直觉模糊多属性群决策模型对设计方案进行优选评价.算法在参考群决策信息的基础上,对专家决策信息进行反复修正,使专家之间的决策信息达到可接受的一致性.算法较好地模拟了专家之间真实的谈判和妥协的决策过程,不需要专家对决策矩阵进行反复的修正,提高了决策的效率,为复杂工业设计方案决策提供了参考.     

Payments for watershed services: Directing incentives for improving lake basin governance

This study introduces the emerging integrated ecosystem management approach known as Payments for Watershed Services (PWS) as utilized for lake and reservoir basin governance. PWS is built on the central concept of providing economic incentives to watershed stakeholders to assist in management efforts. It channels conservation payments from downstream payers to finance conservation activities conducted by upstream payees. The upstream conservation activities are expected to enhance ecosystem functions, thereby improving water‐related ecosystem services desired by downstream stakeholders. Information on 163 PWS projects in 34 developing countries through the year 2008 was collected and analysed, including their common goals, processes, outcomes, scientific assumptions and socioeconomic rationales. This study recognized one unique PWS characteristic, namely the role of intermediary organizations (i.e. brokers) in integrating the economic incentives of upstream payees and downstream payers in order to facilitate their transactions by means of contracts. Although 75% of the reviewed PWS projects have focused on rivers, and only 10% have considered lakes and reservoirs, the similarity of the intermediary functions performed by lake management organizations and PWS intermediary organizations suggests a greater potential for the future application of PWS designs in lake basins. Drawing on components in the field of New Institutional Economics to interpret the intermediary function within the PWS framework, a three‐part PWS design with 15 steps is proposed in this study for lake basin governance, with a Costa Rican PWS scheme serving as an illustration. This study seeks to communicate the scientific and socioeconomic frontiers for developing locally suitable and integrated watershed governance structures to lake management organizations and other watershed stakeholder groups.