褐环乳牛肝菌对马尾松幼苗根系构型的影响     

翟帅帅  丁贵杰  王艺  罗晓蔓  李敏 《福建林学院学报》2015,(3)

为探索外生菌根对植物幼苗根系构型的影响,选用褐环乳牛肝菌Sl12、Sl13接种马尾松幼苗,采用根系图像扫描分析等方法,研究了苗高、地径、根系生物量和根系构型等指标变化。结果表明：接种Sl12、Sl13与CK相比,苗高、地径和根系生物量分别极显著增加了28．9％、20．17％、63．98％和42．8％、37．82％、134．41％;根系总长度、表面积、体积和根尖数目、根冠比显著增加,比根长减少;拓扑指数差异不显著,分形维数极显著增长;2种褐环乳牛肝菌均显著促进了苗木生物量和根系生长,尤以Sl13促生效果更佳。说明褐环乳牛肝菌扩展了根系分布范围,但未改变马尾松幼苗根系分支策略。  相似文献   

基于分形维数和HHT的蚜虫刺吸电位波形机器识别     

吴莉莉  贾树恒  邢玉清  卢少华  潘建斌  闫凤鸣 《农业工程学报》2018,34(24):175-183

昆虫刺吸电位(electricalpenetrationgraph,EPG)技术在研究刺吸式昆虫取食行为、昆虫与植物的关系、昆虫传毒机制、作物抗虫机制等方面得到了广泛的应用,然而EPG信号的识别和分析一直是靠人工进行,亟需波形自动识别系统以提高分析效率。刺吸式昆虫取食植物时,产生的EPG波形跟昆虫和植物的种类有关,不同类别的刺吸式昆虫EPG波形差别很大,即使是同种类型的EPG波形其幅值和频率间也会有差异,这给EPG波形的机器识别带来了困难。该文以蚜虫的EPG信号为研究对象,对np波、pd波、E1波、E2波、G波、C波和F波的特征提取和分类识别进行了研究,提出了一种基于分形维数、希尔伯特-黄变换(hilbert-huang transform,HHT)和决策树的EPG波形识别方法。首先对EPG仪器采集得到的信号进行去噪预处理,分别提取分形维数和HHT共10维特征,组成不同维数的特征向量进入决策树分类器进行对比试验。试验结果表明,可采用分形盒维数、Hurst指数、前2层的谱质心和加权频率融合的6维特征向量获得较高的识别率。在EPG波形的机器识别中采用6维特征向量输入的决策树进行分类,通过对4组不同样本进行测试,得到了92.14%、89.29%、95%和89.29%的识别率,平均识别率为91.43%。研究结果表明该文提出的基于分形维数和HHT的特征提取方法以及构建的决策树分类器具有一定的可行性,可为研发EPG信号自动识别分析系统提供理论参考。  相似文献   

配电GIS图形转换系统的研究     

许童羽  蔡楠 《农业机械化与电气化》2009,(1):52-56

配电网地理图自动生成电气接线网是配电GIS图形转换的主要问题,要求生成的电气接线图与地理图信息完全一致,同时还要科学、美观。采用优化的节点提取拓扑分析方法分析配电地理图中网络拓扑结构。在常见处理方法的基础上提出一种快捷有效的算法．可根据配电网地理图中的地理信息自动生成电气接线图。  相似文献   

Root Architecture Plasticity of Citrus Rootstocks in Response to Nitrate Availability     

A. Sorgonà  M. R. Abenavoli  P. G. Gringeri  A. Lupini  G. Cacco 《Journal of plant nutrition》2013,36(11):1921-1932

Under nutrient heterogeneous soil conditions, the ability of plants to compete for resource acquisition was closely related to the plasticity of root architecture, intended as a change of topology and geometry.

Root architecture variations in response to different nitrate supplies of co-generic citrus rootstocks, ‘Rough Lemon’ (Citrus jambhiri Lush), ‘Sweet Orange’ (Citrus sinensis (L) Osbeck), ‘Cleopatra Mandarin’ (Citrus reshni Hort ex Tan.), and ‘Sour Orange’ (Citrus aurantium L.) are reported here. Root architecture was gauged by an image-specific analysis system (WinRHIZO).

Based on the topological index, root topology of citrus rootstocks varied in response to nitrate treatments. In terms of root geometry, external-external and, to a lesser degree, internal-internal links of all rootstocks changed in response to nitrate supply. Among the rootstocks, ‘Cleopatra Mandarin’, both in terms of root topology (high TI) and root geometry (high length of exterior and interior link), could be considered less competitive owing to resource acquisition compared to the other rootstocks.  相似文献   

组合式三相逆变器同步控制方法     

郑志曜  孙钦斐  王江波  杨仁刚 《农业工程学报》2015,31(5):146-151

为实现组合式三相逆变器输出电压的同步控制,该文以三台单相储能逆变器Y/△连接为例,对其离网模式及离并网预同步过程时的同步控制方法进行研究。该文在离网模式下采用基于CAN(controller area network)总线通信的基准时间同步与相位调整同步的主从同步控制方法;在此基础上,针对离并网预同步过程,该文提出了一种基于改进的二阶广义积分锁相环的频率调整同步控制方法,引入了逻辑判断控制器,实现了三相逆变器电压输出相位差时刻满足120°,保证了离网模式及离并网预同步过程时输出电压的同步,为离并网无冲击切换打下基础。最后,实际试验验证了该方法的可靠性和实用性。  相似文献   

Effects of environmental factors on growth and mortality of Parashorea macrophylla (Dipterocarpaceae) planted on slopes and valleys in a degraded tropical secondary forest in Sarawak,Malaysia     

Daisuke Hattori  Tanaka Kenzo  Nozomi Yamauchi  Kazuo Okamura Irino  Joseph Jawa Kendawang  Ikuo Ninomiya 《Soil Science and Plant Nutrition》2013,59(2):218-228

Enrichment planting with climax trees such as dipterocarps is required to rehabilitate degraded tropical forests in Southeast Asia, because these forests have been damaged by various anthropogenic activities. Severely degraded tropical secondary forests are the most important targets for enrichment planting in the region, because secondary forest trees potentially provide moderate conditions for planted seedlings by preventing strong sunlight and high temperatures. In an enrichment planting site located in Sarawak, Malaysia, we explored how variation in secondary forest structure (biomass and stand density) and soil (nutrient and water) conditions influenced the mortality and growth rates of planted dipterocarp seedlings (Parashorea macrophylla, Wyatt-Sm. ex P.S. Ashton) over the period from 2000–2007. Experimental plots were set up on different topographical features (slopes and valleys). Using the data collected, we demonstrated the ways in which environmental factors, such as soil nitrogen content, relate to climax tree seedling growth and mortality in degraded tropical secondary forests dominated by the genera Macaranga, Ficus, and Glochidion. Stand density and total aboveground biomass of secondary forest trees were significantly lower in the valley plots than on the slopes, whereas soil total nitrogen and water contents were significantly higher in valley plots. Over seven years, the total biomass of trees increased, whereas the density of secondary forest trees decreased in all plots. Nutrient stocks (nitrogen, phosphorus, potassium, calcium, and magnesium) in the soil (0–5?cm) also decreased over seven years in all plots. Height, diameter, and mortality of planted seedlings were higher in the valley plots than on slopes. Multiple stepwise regression demonstrated significant positive effects of total soil nitrogen and water content on the relative growth rate of seedlings over seven years. There were no significant relationships between seedling mortality and any of the environmental factors measured, including soil conditions. We conclude that (1) seedling growth was enhanced by soil total nitrogen rather than by available phosphorus or potassium, and (2) planted seedlings grew faster and died more often in the valley plots than on the slopes.  相似文献   

窑窖滴灌系统输水管路的优化布置     

冒建华  姚春梅  雷廷武 《农业工程学报》2003,19(4):70-73

窑窖集雨滴灌成为解决我国干旱半干旱地区水资源短缺的途径之一。该文分析了窑窖分散式水源特点：水量较小，零星分布，管道设计困难，系统管理繁杂。以在农作物缺水关键期进行灌溉为出发点，根据水窖和地块分散的特点，通过对水窖输水线路优化设计，降低灌溉的管理和工程造价，设计最佳滴灌输水路线，达到水源联合调度的目的，并与传统设计方法和图论优化设计法进行了比较。所提出的设计方法适合解决各种地形条件下分布水源的输水路线布置问题。  相似文献   

柑橘衰退病毒株对两种橘蚜不同翅型取食行为的影响     

赵如娜  何应琴  鲁卓越  陈文龙  杨毓银  王雪峰  周常勇 《山地农业生物学报》2017,(4):13-20

为明确感染柑橘衰退病毒(Citrus tristeza virus,CTV)的柑橘对不同翅型橘蚜取食行为的影响,通过刺探电位图谱技术(electrical penetration graph,EPG)对褐色橘蚜和棉蚜在感染CTV植株上的取食行为进行持续记录,与健康植株进行比较分析。结果表明,褐色橘蚜无翅型在感病植株的参数均与有翅型无显著差异;棉蚜无翅型在感病植株上的非刺探波(no penetration,np波)和路径波(C波)的总持续时间、电势落差(potential drops,pd波)的次数均显著小于有翅型,C波和刺探的次数均极显著小于棉蚜有翅型。褐色橘蚜无翅型在感病植株上的pd波的次数和韧皮部分泌唾液波(E1波)的平均持续时间显著小于棉蚜无翅型;褐色橘蚜有翅型在感病植株上的C波的次数和总持续时间、刺探的次数、pd波的次数和总持续时间均极显著小于棉蚜有翅型,韧皮部被动吸食波(E2波)的总持续时间和平均持续时间均极显著大于棉蚜有翅型。褐色橘蚜无翅型在感病植株上的刺探和pd波的次数均显著高于健康植株,但总刺探时间相反,np波、C波和非韧皮部阶段的总持续时间极显著高于健康植株,E2波的总持续时间极显著短于健康植株。表明柑橘感病状态对无翅型和有翅型的影响是相似的;柑橘感染CTV对褐色橘蚜无翅型的取食行为影响明显,且偏好健康植株,从而促进病毒的传播。  相似文献   

基于梅尔谱图和改进ResNet34模型的鸭蛋裂纹识别算法     

康俊琪  肖德琴  刘又夫  孔馨月  殷建军 《华中农业大学学报》2023,42(3):115-122

针对鸭蛋裂纹人工检测受主观性影响造成精度波动大等问题,利用ResNet34网络模型,提出1种基于梅尔谱图的鸭蛋裂纹识别算法。首先利用敲蛋装置收集敲蛋声音数据,再将音频转化成梅尔谱图,构建梅尔谱图数据集,然后搭建ResNet34模型,引入迁移学习机制训练模型,再通过Adam优化算法更新梯度,增加注意力机制模块并将卷积结构替换为深度可分离卷积以对网络模型进行改进,并调整参数进行优化,最后利用模型对鸭蛋裂纹进行识别。结果显示：改进的ResNet34DP＿CA网络模型检测的平均准确率为92.4%,对比原始ResNet34网络模型,平均准确率提高5.5个百分点,参数量减少32%;对比其他网络模型VGG16、MobileNetv2和EfficientNet,平均准确率分别提高10.9、13.7、16.3个百分点,识别时间为21.5 ms。结果表明,所提出的基于梅尔谱图和改进ResNet34模型的鸭蛋裂纹识别算法,能够有效地对鸭蛋裂纹进行检测识别。  相似文献   

基于加权Voronoi图的乡镇行政边界调整研究——以山东省商河县为例     

陈淑兴 《安徽农业科学》2008,36(20)

以GIS为技术手段,通过综合应用基于GIS的Voronoi图分析方法和多层面复合等空间分析方法,得出了合理的商河县乡镇行政区划调整理论方案。  相似文献