共查询到19条相似文献,搜索用时 46 毫秒
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覃德泽 《中南林业科技大学学报(自然科学版)》2011,31(2)
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。 相似文献
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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。 相似文献
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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. 相似文献
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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。 相似文献
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基于FCM和分水岭算法的无人机影像中林分因子提取 总被引:2,自引:0,他引:2
【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。 相似文献
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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. 相似文献
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公路及其路网对生态环境的影响与对策 总被引:2,自引:0,他引:2
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。
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L. Senni C. Casieri A. Bovino M. C. Gaetani F. De Luca 《Wood Science and Technology》2009,43(1-2):167-180
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. 相似文献
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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. 相似文献
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A design and application of compound multi-functional sensor in wood-based panel processing 总被引:1,自引:0,他引:1
XU Kai-hong ZHOU Ding-guo 《林业研究》2006,17(4):319-322
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 … 相似文献
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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… 相似文献
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