Survivable routing and wavelength assignment algorithm for multiple link failures in wavelength-routed all-optical WDM networks

In this paper, we have investigated the problem of enhancing multiple-fault restorability in the path protected wavelength-routed all-optical WDM networks. The system architecture considered is circuit-switched with dynamic arrival of session requests. We have proposed a mechanism, which is used to combat multiple link failures. A survivable routing and wavelength assignment algorithm has been proposed which is very efficient for the networks having multiple failures. This algorithm deals with the optical networks with multiple faults and is effective for the varying load applied to nodes. This algorithm works well for the load applied to the nodes varying from low to high.     

EVE-OPT: a hybrid algorithm for the capacitated vehicle routing problem

This paper presents EVE-OPT, a Hybrid Algorithm based on Genetic Algorithms and Taboo Search for solving the Capacitated Vehicle Routing Problem. Several hybrid algorithms have been proposed in recent years for solving this problem. Despite good results, they usually make use of highly problem-dependent neighbourhoods and complex genetic operators. This makes their application to real instances difficult, as a number of additional constraints need to be considered. The algorithm described here hybridizes two very simple heuristics and introduces a new genetic operator, the Chain Mutation, as well as a new mutation scheme. We also apply a procedure, the k-chain-moves, able to increase the neighbourhood size, thereby improving the quality of the solution with negligible computational effort. Despite its simplicity, EVE-OPT is able to achieve the same results as very complex state-of-the art algorithms.     

An ILP based hierarchical global routing approach for VLSI ASIC design

The use of integrated circuits in high-performance computing, telecommunications, and consumer electronics has been growing at a very fast pace. The level of integration as measured by the number of logic gates in a chip has been steadily rising due to the rapid progress in processing and interconnect technology. The interconnect delay in VLSI circuits has become a critical determiner of circuit performance. As a result, circuit layout is starting to play a more important role in today’s chip designs. Global routing is one of the key sub-problems of circuit layout which involves finding an approximate path for the wires connecting the elements of the circuit without violating resource constraints. In this paper, several integer programming (ILP) based global routing models are fully investigated and explored. The resulting ILP problem is relaxed and solved as a linear programming (LP) problem followed by a rounding heuristic to obtain an integer solution. Experimental results obtained show that the proposed combined WVEM (wirelength, via, edge capacity) model can optimize several global routing objectives simultaneously and effectively. In addition, several hierarchical methods are combined with the proposed flat ILP based global router to reduce the CPU time by about 66% on average for edge capacity model (ECM).     

Metaheuristics for vehicle routing problems with three-dimensional loading constraints

This paper addresses an important combination of three-dimensional loading and vehicle routing, known as the Three-Dimensional Loading Capacitated Vehicle Routing Problem. The problem calls for the combined optimization of the loading of freight into vehicles and the routing of vehicles along a road network, with the aim of serving customers with minimum traveling cost. Despite its clear practical relevance in freight distribution, the literature on this problem is very limited. This is because of its high combinatorial complexity.     

Exact results for the order picking time distribution under return routing

This paper derives exact expressions for the Laplace-Stieltjes transform of the order picking time in single- and 2-block warehouses. We consider manual warehouses that deploy return routing and assume that order sizes follow a Poisson distribution. The results in this paper apply to a wide range of storage policies, including but not restricted to class-based and random storage. Furthermore, we compare the performance of the storage policies and warehouse lay-outs by using numerical inversion of the Laplace-Stieltjes transforms.     

能量收集传感器网络中改进的能耗管理方案研究

能量收集传感器平台为网络协议的设计开辟了新的领域。为了支持网络的运行,能耗率不得高于能量收集率,否则,传感器节点会最终耗尽它们的能量。与资源处于静态的传统网络资源分配问题相比,充电速率的时间可变性带来了新的挑战。在本文中,我们首先研究了一种基于高效对偶分解和次梯度策略的算法QuickFix,计算出数据采样率和路由。然而,再次充电发生波动时的时标可能会快于传统方法的收敛时间,进而导致电池断电和溢出,这会造成采样丢失和能量收集机会丢失。为了解决这一动态问题,我们提出一种本地算法SnapIt,通过对采集率进行调节以维持电池电量在目标水平上。基于TOSSIM模拟器的性能评估表明,QuickFix和SnapIt联合起来可以跟踪网络瞬时最优效用,同时维持电池电量处于目标水平。与基于余压的IFRC相比,本文方法使总体数据速率平均提升42%,同时显著提升了网络效用。     

一种链式无线路由协议的液压支架压力监测系统设计

本文研究并设计了一种基于无线传感器网络的液压支架压力信息采集节点,并以此为基础搭建了监测系统平台。首先对无线网络拓扑结构分析,以提高网络整体生命周期为目的,设计了一种链式结构的简单无线路由协议。在此基础上,以CC2530为主处理器完成压力采集节点软、硬件设计。最后,给出了系统采集到的液压支架工作阻力数据。测试结果表明,系统能够实现液压支架压力实时监测功能,满足应用需求。     

移动Ad Hoc中基于位置辅助的链路稳定性预测算法

在移动Ad Hoc网络中,随着拓扑的动态变化,路由会发生断裂。传统的稳定路由协议通常定性地考虑链路的质量,并未对链路的稳定性进行有效预测。为了适应网络拓扑的变化,建立稳定性较高的路由,提出了基于位置信息辅助的链路稳定性预测算法,并在AODV协议上进行实现,得到了基于位置辅助的按需距离矢量路由协议,即PB-AODV。在路由发现过程中,协议在节点的稳定区内选择稳定度较高的路由进行数据传送;而在路由维护阶段,PB-AODV采取链路中断预测机制,对即将中断的链路进行通告,在路由中断之前进行路由修复,建立起备份路由。实验表明：具有稳定预测算法的PB-AODV协议在综合性能上优于其他两种性能优良的路由协议,提升了网络的性能。     

Autonomous localization based energy saving mechanism in indoor MANETs using ACO

The biggest challenge in MANETs is to find most efficient routing due to the changing topology and energy constrained battery operated computing devices. It has been found that Ant Colony Optimization (ACO) is a special kind of optimization technique having characterization of Swarm Intelligence (SI) which is highly suitable for finding the adaptive routing for such a type of volatile network. The proposed ACO routing algorithm uses position information and energy parameters as a routing metric to improve the performance and lifetime of network. Typical routing protocols have fixed transmission power irrespective of the distance between the nodes. Considering limiting factors, like small size, limited computational power and energy source, the proposed solution excludes use of GPS for identifying the distance between nodes for indoor MANETs. The distance between nodes can be determined by using Received Signal Strength Indicator (RSSI) measurements. Thus, an intelligent ACO routing algorithm with location information and energy metric is developed to adaptively adjust the transmission power and distribute the load to avoid critical nodes. Proposed Autonomous Localization based Eligible Energetic Path_with_Ant Colony Optimization (ALEEP_with_ACO) algorithm ensures that nodes in the network are not drained out of the energy beyond their threshold, as the load is shared with other nodes, when the energy of a node in the shortest path has reached its threshold. Hence, the total energy expenditure is reduced, thus prolonging the lifetime of network devices and the network. We simulated our proposal and compared it with the classical approach of AODV and other biological routing approaches. The results achieved show that ALEEP_with_ACO presents the best Packet Delivery Ratio (PDR), throughput and less packet drop specially under high mobility scenarios.