基于模拟退火的多射频多信道网络的路由算法

提出一种基于模拟退火的优化算法来解决路由问题。模拟退火算法以加权累积期望传输时间为代价函数来寻找最佳路由方式。系统仿真基于802.11无线网络,分别比较使用基于模拟退火的路由算法和最短路由算法情况下的网络吞吐量和丢包率。仿真结果显示,基于模拟退火的路由算法比最短路由算法具有更好的性能。     

一种应用于林业监测的链式分簇无线传感器网络

介绍了无线传感器网络在林业监测应用中的优势,提出了适合于林区监测的、基于链式分簇的无线传感器网络的布设方案,并描述了基于ZigBee网络协议的方案实现。     

一种分布式路由管理器架构

路由管理器是路由器软件体系架构中的核心组件。基于当前分布式路由器硬件体系架构,采用主控与线卡之间的任务共享机制,提出了一种分布式的路由管理器组件的实现架构。该分布式路由管理器架构可有效满足新一代路由器的扩展性、鲁棒性和可用性要求。通过将该分布式路由管理器架构与集中式路由器管理架构进行对比,表明该架构具有较好的扩展性。     

基于自然保护区传感器网络的整合架构设计

然保护区不仅对维护生态平衡、保护生态环境发挥了重要作用,而且也为经济和社会的可持续发展提供了生态安全保障.在我国自然保护区数量和面积得到发展的同时,如何对保护区实施有效的、科学的管理是当前面临的最大问题.     

基于NS2移动自组网路由协议性能评价的仿真实现

为了使用网络仿真软件NS2评价移动自组网的路由协议,编写了用于仿真实现的脚本程序,提出了对仿真结果进行分析的方法.通过实例仿真,得出了移动自组网路由协议AODV(自组网按需路由协议)和DSR(动态源路由)性能参数的比较图.     

利用ANSYS进行参数化有限元网格剖分

以起重机吊臂设计为例 ,介绍了利用ANSYS进行参数化有限元网格剖分的过程 ,本方法可推广应用于其它工程机械的设计。     

一种基于Wi-Fi的井下人员精确定位算法研究

简单分析了基于RFID的人员定位技术、基于到达时间差TDOA的定位技术以及基于接受信号强度RSSI的定位技术。在此基础上针对煤矿井下巷道的特殊环境,提出了一种基于两点定位的井下人员精确定位算法。通过实地模拟实验得出该算法的定位误差基本控制在2~3 m之内。     

气象通信网络中OSPF动态路由技术解析

分析了OSPF动态路由技术的应用前景,并介绍了OSPF动态路由技术在黑龙江省气象通信网络路由器中的配置方法。     

基于JSR168规范网格Portal的设计

网格环境的复杂性，常导致用户难以使用高性能科学计算。因此需要一个基于应用服务的网格Portal来提高软件与网格服务、网格资源的交互。面向教育资源网格Portal的设计把服务的实现和访问分离，为充分利用和有效协调教育资源提供了很好的手段。     

基于FCM和分水岭算法的无人机影像中林分因子提取

【目的】研究高精度小型无人机获取林分调查因子方法,将林分调查因子在低空无人机影像上识别并提取出来,获取树高、冠径等测树因子,建立林分因子测量方法,实现经济、高效、快捷、精准的森林资源调查和监测,及时掌握森林资源及相关林分因子的时空变化特征。【方法】以东北林业大学城市林业示范基地樟子松人工林为研究对象,以多旋翼无人机影像为数据源,基于FCM聚类算法和分水岭分割算法以及形态学运算、阈值分割、图像平滑、灰度化、二值化等一系列数字图像处理技术,提取樟子松人工林林分因子。FCM聚类算法和阈值分割法用于提取树梢标记图像,分水岭分割算法对树梢标记图像进行迭代处理从而获得单木树冠分割图像,根据单木树冠分割结果提取单木特征进而计算各林分因子值。【结果】在林地提取中,根据影像的颜色特征绿度分割成功地将林地部分与非林地部分分离开来,确定单木树冠分割范围。在单木树冠分割中,阈值分割法和FCM聚类算法均可有效将树梢标记从林地图像中提取出来;将基于标记的分水岭分割算法用于单木树冠分割取得较好效果,大多数单木树冠被单独分割出来,但某些区域仍然存在一定的欠分割或过分割问题。在林分因子提取中,提取的林分因子包括林分郁闭度、林地面积、立木株数和平均冠幅,其中林分郁闭度的测量精度为96.67%,林地面积的测量精度为81.23%,立木株数和平均冠幅的测量精度与单木树冠分割中的树梢提取方法(阈值分割法和FCM聚类算法)及分水岭分割中的2个参数(形态学腐蚀的结构元素大小和中值滤波的窗口大小)有关。针对2种树梢提取方法,分别进行参数组合试验,结果显示2种树梢提取方法使用适当参数组合所得各林分因子测量精度均在80%以上,平均测量精度均在90%以上,其中阈值分割法的最高平均测量精度为94.49%,FCM聚类算法的最高平均测量精度为93.17%。【结论】利用无人机拍摄的人工林影像进行森林资源调查,将先进的计算机科学技术和无人机技术应用到林业领域中,可有效提高森林资源调查的效率和精度。本研究提出的林分因子提取方法适用于高郁闭度林分,测量精度满足实际需求。     

基于无线传感网的森林火灾FWI系统分析

林火的高发性和破坏性决定了林火防控的重要性,无线传感器网络技术的兴起和发展为现代林业火灾预警预报的实现提供了机遇。加拿大森林火险气候指数(Fire Weather Index,FWI)系统是以时滞-平衡含水率理论为基础,通过天气条件的变化计算地面可燃物含水率的情况,根据地表到地下不同层次的可燃物含水率划分森林潜在火险等级。笔者分析研究了FWI系统的原理,并以南京市为参照验证了FWI系统的分析结果,希望在基于FWI系统的基础上发展中国的森林火险等级预警系统。     

木工平面镂铣加工CAD/CNC-AP集成技术

本以ＡｕｔｏＣＡＤ Ｒ１４为开发平台,综合运用Ｏｂｊｅｃｔ ＡＲＸ ＳＤＫ,Ｖｉｓｕａｌ Ｃ＾＋＋６．０级ＣＮＣ技术,研究了ＡｕｔｏＣＡＤ Ｒ１４数据结构和将平面镂铣ＣＡＤ图形自动转换成ＣＮＣ加工程序的计算方法,开发出一中适用于ＣＮＣ木工镂铣一类平面轨迹和加工的、集ＣＡＤ／ＣＮＣ ＡＰ于一体的集成技术。该技术可直接将二维ＡｕｔｏＣＡＤ图形快速转成二维ＣＮＣ加工程序,解决了实际二维平面镂铣加工ＣＡ     

A linear programming algorithm and software for forest-level planning problems including factories

Combining stand simulation and forest-level optimization is an efficient way to study harvest scenarios of a forest area. A simulator first generates for each treatment unit a number of treatment schedules. Linear programming (LP) can then be used to study how stand-level schedules can be combined at the forest level with respect to alternative goals and constraints. The special structure of the obtained LP problems can be utilized using the generalized upper-bound technique which takes care of the so-called area constraints. JLP software was based on this technique. Later J software was developed to replace JLP. Now J is developed to deal with factory problems where the transportations costs and capacities of factories are included in the problem definition. The generalized upper-bound technique was modified to handle transportation constraints which tell that each timber unit produced is transported to some of the factories. The number of these constraints is very large. This paper describes the basic features of the algorithm and its implementation in the J software.     

公路及其路网对生态环境的影响与对策

公路及其路网对开放空间及其中的各种自然生态过程产生了十分不利的影响。从沿线环境污染与侵扰、行动障碍与交通伤亡、区域生境碎化等几方面分析了公路生态环境影响,并结合国际上的一些先进经验论述了公路生态环境建设的基本方法框架、生态环境决策与生态工程措施。       

A portable NMR sensor for moisture monitoring of wooden works of art, particularly of paintings on wood

It is proposed the use of a mobile device based on a NMR single-sided sensor for in situ non-invasive determination of the moisture content (MC) of wood items, especially items of Cultural Heritage interest. The MC is obtained through the moisture volume fraction, which is an appropriate quantity for the sensor and corresponds to the fraction of its measurements sensitive volume occupied by water. The device has been used here to track changes in MC of wood specimens caused by changes over time of the environmental relative humidity. The kinetics of water adsorption has been related to results obtained with the gravimetric method. Measurements on an old painting, the Pietà (1516–1517), oil on a poplar wood panel by Sebastiano del Piombo (1485 Venice, 1547 Rome), Civic Museum, Viterbo, Italy, have shown, conclusively, the good sensitivity of the sensor and its capability to behave as a non-invasive and in situ utilizable device. Results of in situ painting measurements show that the NMR sensor can track moisture fluctuations that are outside the sensitivity range and precision of electro-hygrometric approach.     

A comparison of selected acoustic signal analysis techniques to evaluate wood surface roughness produced during routing

This study examines the applicability of several signal analyzing methods applied to audio signals to establish relationships between audio signals generated during machining and the surface roughness produced. One-third octave passband filters were also used to condition audio signals acquired during routing of Japanese beech (Fagus crenata Blume) at different machining conditions. The one-third octave analysis was essential for gaining satisfactory results. Three different analyzing strategies were investigated: the RMS averaging method and the count rate method combined with static and dynamic thresholds. The count rate method at constant threshold could not be applied to the sound intensity signal due to its substantial range in magnitude during machining at different states, although the dynamic threshold strategy can be applied to both the sound intensity and the sound pressure signals, and adjusts flexibly to the variable signal generated. Linear regression of data obtained during each of the analyzing strategies shows that the RMS averaging method is most suitable for analyzing audio signals, as shown by its highest correlation coefficient with surface roughness produced. The results suggest that measurement of sound intensity is a promising method for monitoring surface roughness and determining optimum feed rates.     

A design and application of compound multi-functional sensor in wood-based panel processing

Introduction Multi-functional sensor, a new developmental direction of sensor field, can integrate several sense organs to measure several parameters at one time (Liu 1999). This sensor not only has small size but also has strong functions. Moreover, the …     

BJFG—1型光栅位移传感器位移检测原理

1　概　述BJFG- 1型光栅位移传感器是一种新型部件式金属反射光栅位移传感器。随着现代加工和计量技术的发展 ,对长度和位移测量不仅要求提高精度 ,而且要求能迅速而客观地将长度和位移测量结果以数字信号形式输出 ,以便进行数据处理和程序控制。光栅测量系统不但能以数字显示位移量 ,而且可以按预置指令程序来控制测量或加工过程 ,实现数字控制或伺服跟踪 ,因此 ,极大地提高了产品的质量和劳动生率。2　构成及原理光栅数显测量装置通常由光源、计量光栅、光电接收器、前置放大器、电子细分电路、计数器、显示装置等组成。其中 ,光源、光…