无线传感器网络中抗共谋的自愈组密钥分配方案

针对现有基于双向Hash链技术的自愈组密钥分配方案不能抵抗撤销节点和新加入节点的共谋攻击问题,并进一步提高现有方案的性能,提出了一种适用于无线传感器网络的有效的抗共谋攻击的自愈组密钥分配方案。方案对传统的双向Hash链进行了结构性改造,在有撤销节点的会话中,用随机值替换前向密钥,使得已被撤销节点无法和新加入节点共谋获取它们未被授权的会话密钥,消除了共谋攻击对网络构成的安全威胁,更适用于俘获节点攻击高发的网络环境。方案还考虑了在实际网络环境中,并不是在每一个会话都有节点被撤销这一个实际情况,减少了通信开销和能量消耗。安全性和性能分析与仿真结果表明,方案在保证更好安全性的同时,降低了通信开销。     

基于双启发动态规划的预分解窑控制器设计

针对水泥预分解窑熟料煅烧过程多变量、多扰动、非线性,难以建立精确的数学模型,实际生产中对工人的生产经验依赖性较强等问题,提出采用误差反向传播(BP)神经网络建立烧成系统数学模型,设计预分解窑双启发动态规划(DHP)控制器。DHP评价网络输出代价函数J关于状态量的偏导数,获得最优或者次优的控制信号,然后由动作网络输出控制信号,使系统得到期望的控制轨迹。仿真结果表明控制器响应时间较快,各参量超调量均不大,有助于实际系统的稳定运行。     

基于FPGA的CCD相机的图像采集

介绍在特定环境下CCD相机图像数据的采集背景下的一种基于FPGA的高速图像数据采集板卡设计方法,详细讨论了其系统结构和核心部分的内部功能模块,并给出了其核心：PCI IPcore的具体仿真结果。同时探讨了此板卡和外部的接口实现问题。     

基于FPGA的CCD相机的图像采集

介绍在特定环境下CCD相机图像数据的采集背景下的一种基于FPGA的高速图像数据采集板卡设计方法,详细讨论了其系统结构和核心部分的内部功能模块,并给出了其核心:PCI IPcore的具体仿真结果。同时探讨了此板卡和外部的接口实现问题。     

Using online pickup site inclusion policies to manage demand in retail/E-tail organizations

A major development in online retailing is the significant increase in the number of traditional “offline” retailers extending their brands online. Many of these retail/e-tail firms are attempting to leverage channel synergies by allowing customers to purchase products over the internet and then pick their orders up at one of the firm's local stores. This paper proposes that the firm presents only a subset of its stores to online customers as available pickup locations, rather than simply listing all local stores with inventory. By doing so, the firm can protect stores with critically low inventory levels and thereby reduce backorder costs. Specifically, we develop and evaluate a dynamic pickup site inclusion policy that incorporates real-time information to specify which of the firm's e-fulfillment locations should be presented at online checkout. Computational results indicate that managing in-store demand via such policies can decrease total cost (holding, backorder, and lost or redirected pickup sale costs) by as much as 18% over allowing customers to pick online orders up from any site with available inventory. The percentage of pickup sales and customers' sensitivity to travel are critical in determining the magnitude of the benefit.     

Enhanced energetic reasoning-based lower bounds for the resource constrained project scheduling problem

We present new and effective lower bounds for the resource constrained project scheduling problem. This problem is widely known to be notoriously difficult to solve due to the lack of lower bounds that are both tight and fast. In this paper, we propose several new lower bounds that are based on the concept of energetic reasoning. A major contribution of this work is to investigate several enhanced new feasibility tests that prove useful for deriving new lower bounds that consistently outperform the classical energetic reasoning-based lower bound. In particular, we present the results of a comprehensive computational study, carried out on 1560 benchmark instances, that provides strong evidence that a deceptively simple dual feasible function-based lower bound is highly competitive with a state-of-the-art lower bound while being extremely fast. Furthermore, we found that an effective shaving procedure enables to derive an excellent lower bound that often outperforms the best bound from the literature while being significantly simpler.     

Single sourcing versus dual sourcing under conditions of learning

This paper considers a buyer who has to decide whether to select a single or two sources of supply for a homogeneous product. The production processes of the suppliers are subject to learning effects, which reduce the production costs and increase the production capacities of the suppliers. This, in turn, enables the suppliers to reduce the sales price, which results in lower acquisition costs at the buyer. As the supplier selection decision influences the individual production quantity of a supplier, the learning effect has to be considered when deciding how many and which suppliers to select. Since the effect of learning on the supplier selection problem has not been investigated in the literature, this paper addresses this limitation and derives models for continuous learning and when learning plateaus. Numerical results indicate that the supplier selection decision can comprehensively influence the learning process for the suppliers and therewith the total costs of the system under study. The results also show that it is not necessarily optimal solely to select the supplier with the highest learning rate.     

Enhancing displacement of lead-zirconate-titanate (PZT) thin-film membrane microactuators via a dual electrode design

A common design of piezoelectric microactuators adopts a membrane structure that consists of a base silicon diaphragm, a layer of bottom electrode, a layer of piezoelectric thin film, and a layer of top electrode. In particular, the piezoelectric thin film is often made of lead-zirconate-titanate (PZT) for its high piezoelectric constants. When driven electrically, the PZT thin film extends or contracts flexing the membrane and generating an out-of-plane displacement. Many manufacturing defects, however, could significantly reduce the designed actuator displacement. Examples include residual stresses, warping, non-uniform etching of the silicon diaphragm, and misalignment between the top electrode and the silicon diaphragm. The purpose of this paper is to develop a dual top-electrode design to enhance the actuator displacement. In this design, the top electrode consists of two disconnected (thus independent) electrode areas, while a continuous bottom electrode serves as the ground. The two top electrodes are located in two regions with opposite curvature when the diaphragm deflects. When the two top electrodes are driven in an out-of-phase manner, the actuator displacement is enhanced. Finite element analyses and experimental measurements both confirm the feasibility of this design. When manufacturing defects are present, experimental results indicate that the actuator displacement can be optimized by adjusting the phase difference between the dual top electrodes.     

大学生生活方式二重性研究——基于网络二重属性的影响

网络自然属性与社会属性既相互联系又相互区别;大学生生活方式自然属性与社会属性也相互联系并相互区别;网络二重性对大学生生活方式二重性产生直接的影响。网络的自然属性重塑大学生的社会结构,二重地改变着大学生生活的时空结构。网络的社会属性削弱大学生现实社会关系的不平等性;改变大学生生活的社交范围,并为其提供更新的社交方式;二重地影响着大学生的思想与心理。     

企业园区网规划及部署研究与应用

本文介绍了企业级网络的规划思路和部署概况,对其中的关键技术进行了探讨和研究。重点介绍了企业网的拓扑构成,内网中虚拟局域网的划分和应用,MSTP与VRRP协议支持的双核心架构的应用,无线局域网漫游、网络的安全防护等关键技术。