期刊文献+
共找到1,257篇文章
< 1 2 63 >
每页显示 20 50 100
Graph Similarity Join with K-Hop Tree Indexing
1
作者 Yue Wang Hongzhi Wang +1 位作者 Chen Ye Hong Gao 《国际计算机前沿大会会议论文集》 2015年第1期13-14,共2页
Graph similarity join has become imperative for integrating noisy and inconsistent data from multiple data sources. The edit distance is commonly used to measure the similarity between graphs. To accelerate the simila... Graph similarity join has become imperative for integrating noisy and inconsistent data from multiple data sources. The edit distance is commonly used to measure the similarity between graphs. To accelerate the similarity join based on graph edit distance, in the paper, we make use of a preprocessing strategy to remove the mismatching graph pairs with significant differences. Then a novel method of building indexes for each graph is proposed by grouping the nodes which can be reached in k hops for each key node with structure conservation, which is the k-hop-tree based indexing method. Experiments on real and synthetic graph databases also confirm that our method can achieve good join quality in graph similarity join. Besides, the join process can be finished in polynomial time. 展开更多
关键词 GRAPH similarity JOIN EDIT distance constraint k-hop tree based INDEXING structure conservation boundary filtering
下载PDF
SERVICE COMMUNITY CONSTRUCTION METHOD OF INTERNET OF THINGS BASED ON SEMANTIC SIMILARITY 被引量:1
2
作者 Wang Yang Zhang Linjing +2 位作者 Huang Yakun Zhao Baohua Zhao Chuanxin 《Journal of Electronics(China)》 2013年第1期49-56,共8页
Internet of Things (IoT) as an important and ubiquitous service paradigm is one of the most important issues in IoT applications to provide terminal users with effective and efficient services based on service communi... Internet of Things (IoT) as an important and ubiquitous service paradigm is one of the most important issues in IoT applications to provide terminal users with effective and efficient services based on service community. This paper presents a semantic-based similarity algorithm to build the IoT service community. Firstly, the algorithm reflects that the nodes of IoT contain a wealth of semantic information and makes them to build into the concept tree. Then tap the similarity of the semantic information based on the concept tree. Finally, we achieve the optimization of the service community through greedy algorithm and control the size of the service community by adjusting the threshold. Simulation results show the effectiveness and feasibility of this algorithm. 展开更多
关键词 Internet of Things (IoT) Service community Semantic similarity Concept tree
下载PDF
基于FP-tree和MapReduce的集合相似度自连接算法 被引量:1
3
作者 冯禹洪 吴坤汉 +4 位作者 黄志鸿 冯洋洲 陈欢欢 白鉴聪 明仲 《计算机研究与发展》 EI CSCD 北大核心 2023年第12期2890-2906,共17页
利用集合相似度自连接算法找出一个集合集中所有相似度大于给定阈值的集合对有着广泛的应用.基于过滤-验证框架和并行分布式计算框架MapReduce的集合相似度连接是近年来的研究热点.但现有算法在阈值低时产生较大规模的候选集,导致性能... 利用集合相似度自连接算法找出一个集合集中所有相似度大于给定阈值的集合对有着广泛的应用.基于过滤-验证框架和并行分布式计算框架MapReduce的集合相似度连接是近年来的研究热点.但现有算法在阈值低时产生较大规模的候选集,导致性能不理想.针对这一问题,提出采用频繁模式树FP-tree及其派生结构FP-tree*将数据压缩在内存中计算集合相似度自连接以减小候选集规模.首先设计并讨论基于现有FP-tree*的集合相似度连接计算及其优缺点,提出遍历效率更高的线性频繁模式树结构模型TELP-tree及基于它的算法TELP-SJ(TELP-tree self join),其包括分别面向构建树和遍历树的2阶段过滤算法,这些算法可以减小树规模和减少树遍历.然后,设计基于MapReduce的并行分布式算法FastTELP-SJ.最后,基于4组真实应用数据集进行3组性能比较实验.实验结果表明FastTELP-SJ算法面向高维大规模集合相似度自连接计算时,包括执行时间、内存占用率、磁盘使用量和可扩展性的运行效率最好. 展开更多
关键词 相似度连接 FP树 MAPREDUCE框架 Jaccard函数 集合
下载PDF
Effect of Indole 3-Butyric Acid and Media Type on Adventitious Root Formation in Sheanut Tree (<i>Vitellaria paradoxa</i>C. F. Gaertn.) Stem Cuttings 被引量:4
4
作者 Daniel Brain Akakpo Naalamle Amissah +1 位作者 Julius Yeboah Essie Blay 《American Journal of Plant Sciences》 2014年第3期313-318,共6页
Shea nuts play an important role in food security for rural folks within sub-Sahara Africa, serving as the main source of income for many people living in Northern Ghana. Unfortunately, the full economic potential of ... Shea nuts play an important role in food security for rural folks within sub-Sahara Africa, serving as the main source of income for many people living in Northern Ghana. Unfortunately, the full economic potential of the Sheanut tree has not been fully realized due to the difficulty involved in its domestication. This difficulty in vegetatively propagating sheanut trees has greatly hindered its cultivation and the realization of its true economic potential. Two experiments were conducted to investigate the effects of rooting media and varying indole 3-butyric acid (IBA) concentrations on adventitious root formation in cuttings taken from coppiced sheanut trees. Results indicated that 3000 ppm produced significantly (p 0.05) better rooting (57.5%) than 5000 ppm (30%), 7000 ppm (45.0%) and the control (7.5%). Although the levels of soluble sugars (SS) and total free phenols (TFP) in the cutting were significantly (p 0.05) higher at the end of the experiment (after IBA treatment) compared to the start (prior to IBA treatment), the SS and TFP trends observed did not clearly explain the rooting differences found between the IBA levels investigated. Callus formation was significantly (p 0.05) higher (35.0%) in the control (no IBA). Generally, callus formation decreased with increasing IBA concentration. In the rooting media experiment, rooting was significantly (p 0.05) higher in the rice husk medium (35.0%) compared to that in the palm fiber (18.3%), saw dust (14.1%) and top soil (16.7%) media. 展开更多
关键词 Coppiced INDOLE 3-Butyric Acid Sheanut tree cuttings Rooting Medium
下载PDF
A Simple Method to Derive Minimal Cut Sets for a Non-coherent Fault Tree 被引量:2
5
作者 Takehisa Kohda 《International Journal of Automation and computing》 EI 2006年第2期151-156,共6页
Minimal cut sets (or prime implicants: minimal combinations of basic event conditions leading to system failure) are important information for reliability/safety analysis and design. To obtain minimal cut sets for ... Minimal cut sets (or prime implicants: minimal combinations of basic event conditions leading to system failure) are important information for reliability/safety analysis and design. To obtain minimal cut sets for general non-coherent fault trees, including negative basic events or multi-valued basic events, a special procedure such as the consensus rule must be applied to the results obtained by logical operations for coherent fault trees, which will require more steps and time. This paper proposes a simple method for a non-coherent fault tree, whose top event is represented as an AND combination of monotonic sub-trees. A "monotonic" sub-tree means that it does not have both positive and negative representations for each basic event. It is proven that minimal cut sets can be obtained by a conventional method for coherent fault trees. An illustrative example of a simple event tree analysis shows the detail and characteristics of the proposed method. 展开更多
关键词 Non-coherent fault trees monotonic sub-trees minimal cut sets.
下载PDF
STUDY ON MODULAR FAULT TREE ANALYSIS TECHNIQUE WITH CUT SETS MATRIX METHOD
6
作者 Chen, Jinshui Zhang, Li +1 位作者 Cai, Huiming Zhang, Chengpu 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 1998年第2期2-9,共8页
A new fault tree analysis (FTA) computation method is put forth by using modularization technique in FTA with cut sets matrix, and can reduce NP (Nondeterministic polynomial) difficulty effectively. This software can ... A new fault tree analysis (FTA) computation method is put forth by using modularization technique in FTA with cut sets matrix, and can reduce NP (Nondeterministic polynomial) difficulty effectively. This software can run in IBM PC and DOS 3.0 and up. The method provides theoretical basis and computation tool for application of FTA technique in the common engineering system 展开更多
关键词 cut set matrix MODULARIZATION Fault tree analysis
全文增补中
Model test of the cutting properties of a shearer drum 被引量:12
7
作者 LIU Song-yong DU Chang-long CUI Xin-xia CHENG Xue 《Mining Science and Technology》 EI CAS 2009年第1期74-78,共5页
According to similarity theory, we carried out a dimensional analysis of the shearer drum correlation parameters and built similarity criteria. Based on these, similarity models of shearer drums were developed. Simult... According to similarity theory, we carried out a dimensional analysis of the shearer drum correlation parameters and built similarity criteria. Based on these, similarity models of shearer drums were developed. Simultaneously, based on an estab- lished cutting testbed of the coal and rock, cutting tests of different pick arrangements of the drum models were carried out, where the compressive strength of the analogous cutting material was 2.48 MPa and the drum rotary speed 67.5 r/min. The variance, the mean values, maxima and mean maxima of the torque load were analyzed for different type drum models. Moreover, the relation-ships between the type of pick arrangements and the cutting lump coal percentage were studied. The results indicate that the load fluctuation of the sequence drum is larger than that of the punnett square drum in the cutting process and the lump coal percentage and economic benefits of the sequence drum are inferior to the punnett square drum. We conclude that the punnett square drum is superior to the sequence drum. 展开更多
关键词 similarity theory dimensional analysis similarity criteria cutting test lump coal percentage
下载PDF
融合注意力机制和Child-Sum Tree-LSTM的二进制代码相似性检测
8
作者 李涛 王金双 《网络安全与数据治理》 2023年第11期8-14,34,共8页
抽象语法树是一种代码的树型表示,它保留了代码中定义良好的语句组件、语句的显式顺序和执行逻辑。包含丰富语义信息的抽象语法树可以在二进制分析时通过反编译生成,并且已经作为代码特征应用于二进制代码相似度检测。抽象语法树中不同... 抽象语法树是一种代码的树型表示,它保留了代码中定义良好的语句组件、语句的显式顺序和执行逻辑。包含丰富语义信息的抽象语法树可以在二进制分析时通过反编译生成,并且已经作为代码特征应用于二进制代码相似度检测。抽象语法树中不同类别的节点承载着不同的语义信息,对整棵树的语义具有不同的贡献程度。然而现有的二进制代码相似度检测方法所用神经网络无法对抽象语法树节点进行重要性区分,影响了模型的训练效果。针对该问题,提出了一种融合注意力机制和Child-Sum Tree-LSTM神经网络的跨指令集、跨代码混淆二进制代码相似性检测方法。首先使用二进制分析工具IDA Pro对二进制代码反编译提取架构无关的抽象语法树特征,并利用随机采样构造训练样本对。然后使用抽象语法树训练样本对训练融合注意力机制和Child-Sum Tree-LSTM的神经网络模型。在公开数据集BINKIT上的实验表明,所提方法的AUC和Accuracy指标分别为94.1%、66.2%,优于Child-Sum Tree-LSTM算法。 展开更多
关键词 二进制代码 相似性检测 注意力机制 Child-Sum tree-LSTM
下载PDF
Part-level 3-D object classification with improved interpretation tree
9
作者 邢薇薇 刘渭滨 袁保宗 《Journal of Southeast University(English Edition)》 EI CAS 2007年第2期221-225,共5页
For classifying unknown 3-D objects into a set of predetermined object classes, a part-level object classification method based on the improved interpretation tree is presented. The part-level representation is implem... For classifying unknown 3-D objects into a set of predetermined object classes, a part-level object classification method based on the improved interpretation tree is presented. The part-level representation is implemented, which enables a more compact shape description of 3-D objects. The proposed classification method consists of two key processing stages: the improved constrained search on an interpretation tree and the following shape similarity measure computation. By the classification method, both whole match and partial match with shape similarity ranks are achieved; especially, focus match can be accomplished, where different key parts may be labeled and all the matched models containing corresponding key parts may be obtained. A series of experiments show the effectiveness of the presented 3-D object classification method. 展开更多
关键词 3-D object classification shape match similarity measure interpretation tree
下载PDF
科研反哺教学在林木育种学教学中的探索与实践
10
作者 任亚超 张军 +1 位作者 王进茂 杨敏生 《安徽农业科学》 CAS 2024年第10期278-282,共5页
林木育种学是高等农林院校林学专业的一门骨干课程,是以遗传进化理论为指导,研究林木优良品种选育、繁殖原理和技术的学科。其最高目标是选育林木优良品种,为林业生产提供最基本、最优质、最高效的生产资料,是林业的命脉和促进林业产业... 林木育种学是高等农林院校林学专业的一门骨干课程,是以遗传进化理论为指导,研究林木优良品种选育、繁殖原理和技术的学科。其最高目标是选育林木优良品种,为林业生产提供最基本、最优质、最高效的生产资料,是林业的命脉和促进林业产业发展的原动力,在生态文明和美丽中国建设中发挥着越来越重要的作用。为了使学生更容易理解和掌握林木育种学的理论知识,深化科教融合,推进创新型人才培养,完善协同育人机制,在林木育种学授课过程中,通过将理论知识与生产实践相联系,将科技前沿贯穿于课堂教学,并以科研平台辅助实验教学的方式进行教学改革,不仅丰富了教学内容,激发了学生的学习热情,加深了对理论知识的理解,而且还利于学生良好科研素养的培养及创新能力的提高。 展开更多
关键词 林木育种学 科研反哺教学 教学改革 科研基地 科技前沿
下载PDF
掺氢天然气管道故障树分析及建模软件开发
11
作者 赵爽 杜凤 +1 位作者 孙东旭 吴明 《工业安全与环保》 2024年第3期1-5,共5页
针对掺氢天然气管道可能存在的风险与隐患,分析国内外各类管道失效数据,建立了掺氢天然气管道故障树,共包含10个子树和148个底事件,在掺氢管道失效库基础上采用C#程序设计语言开发了掺氢天然气管道故障树建模软件;应用建模软件对已建立... 针对掺氢天然气管道可能存在的风险与隐患,分析国内外各类管道失效数据,建立了掺氢天然气管道故障树,共包含10个子树和148个底事件,在掺氢管道失效库基础上采用C#程序设计语言开发了掺氢天然气管道故障树建模软件;应用建模软件对已建立的掺氢天然气管道故障树进行分析。软件计算通过行列法求解出最小割集共189个,其中一阶最小割集106个,二阶最小割集83个;采用双循环法得到148个底事件结构重要度。分析得出防腐措施是否正常工作以及自然灾害是影响掺氢天然气管道安全运行的重要因素。 展开更多
关键词 掺氢天然气 管道失效 故障树 软件开发 最小割集 结构重要度
下载PDF
蹬空开采条件下雨汪煤矿的110工法相似模拟研究
12
作者 陶志刚 熊弋文 +2 位作者 李勇 刘安堃 林伟军 《煤炭技术》 CAS 2024年第11期39-44,共6页
以雨汪煤矿1010201工作面为研究背景,开展蹬空开采110工法相似模拟试验研究,利用应变监测系统和MatchID散斑非接触测量系统,从应力场和位移场2个方向监测不同阶段上覆岩体和巷道围岩的变形特征,探究上覆岩体裂隙带运动规律。研究结果表... 以雨汪煤矿1010201工作面为研究背景,开展蹬空开采110工法相似模拟试验研究,利用应变监测系统和MatchID散斑非接触测量系统,从应力场和位移场2个方向监测不同阶段上覆岩体和巷道围岩的变形特征,探究上覆岩体裂隙带运动规律。研究结果表明,推进40 cm时,非切缝侧直接顶出现部分垮落;推进80 cm时,直接顶完全垮落;推进100 cm时,基本顶大面积垮落,工作面被完全填充,上覆岩体变形趋于稳定。垂直位移监测云图表明,顶板最大垂直位移为34 mm,底板最大垂直位移为16 mm。说明切顶卸压技术和NPR锚索支护补偿力学理论对超载条件下的蹬空开采仍然具有良好的适用性,通过垮落岩体的碎胀效应对工作面充填支撑,使得基本顶范围内岩体和巷道围岩变形得到了良好的控制,一定程度地减小了地表沉降,并且沿空留巷效果显著,为实际工程施工提供了科学依据和理论指导。 展开更多
关键词 切顶卸压 相似模拟 裂隙带 NPR锚索 沿空留巷
下载PDF
基于ANSYS的果树嫁接机结构优化分析
13
作者 晏芳 《农机化研究》 北大核心 2024年第9期153-156,共4页
通过对果树嫁接机的基本工作原理和结构形式进行分析,构建了果树苗木的力学特性,进行了果树嫁接机切刀优化设计。利用ANSYS对果树嫁接机切刀进行有限元分析,根据静力分析结果进行切刀寿命仿真,获取果树切刀应力集中位置和切刀结构脆弱... 通过对果树嫁接机的基本工作原理和结构形式进行分析,构建了果树苗木的力学特性,进行了果树嫁接机切刀优化设计。利用ANSYS对果树嫁接机切刀进行有限元分析,根据静力分析结果进行切刀寿命仿真,获取果树切刀应力集中位置和切刀结构脆弱点。分别采用两种不同材料对果树嫁接机切刀进行有限元分析,通过应力云图和寿命曲线对果树切刀进行优化设计,最终采用Cr12MoV制作果树切刀,提高了果树嫁接机的使用寿命。 展开更多
关键词 果树嫁接机 结构优化 ANSYS 切削刀具
下载PDF
A Dimensional Reduction Approach Based on Essential Constraints in Linear Programming
14
作者 Eirini I. Nikolopoulou George S. Androulakis 《American Journal of Operations Research》 2024年第1期1-31,共31页
This paper presents a new dimension reduction strategy for medium and large-scale linear programming problems. The proposed method uses a subset of the original constraints and combines two algorithms: the weighted av... This paper presents a new dimension reduction strategy for medium and large-scale linear programming problems. The proposed method uses a subset of the original constraints and combines two algorithms: the weighted average and the cosine simplex algorithm. The first approach identifies binding constraints by using the weighted average of each constraint, whereas the second algorithm is based on the cosine similarity between the vector of the objective function and the constraints. These two approaches are complementary, and when used together, they locate the essential subset of initial constraints required for solving medium and large-scale linear programming problems. After reducing the dimension of the linear programming problem using the subset of the essential constraints, the solution method can be chosen from any suitable method for linear programming. The proposed approach was applied to a set of well-known benchmarks as well as more than 2000 random medium and large-scale linear programming problems. The results are promising, indicating that the new approach contributes to the reduction of both the size of the problems and the total number of iterations required. A tree-based classification model also confirmed the need for combining the two approaches. A detailed numerical example, the general numerical results, and the statistical analysis for the decision tree procedure are presented. 展开更多
关键词 Linear Programming Binding Constraints Dimension Reduction Cosine similarity Decision Analysis Decision trees
下载PDF
基于故障树反演的复合材料成形生产线故障诊断
15
作者 王玉山 贾思敏 +2 位作者 宋照爱 翟华 韩江 《锻压装备与制造技术》 2024年第2期12-17,共6页
复合材料成形装备生产线因其复杂性和高度集成性,故障的产生可能涉及多个环节和因素,因此需要一种系统性的方法来准确地分析和定位故障源。本文梳理了复合材料产品制造过程中可能出现的故障类型和影响因素,构建了一个全面的复合材料成... 复合材料成形装备生产线因其复杂性和高度集成性,故障的产生可能涉及多个环节和因素,因此需要一种系统性的方法来准确地分析和定位故障源。本文梳理了复合材料产品制造过程中可能出现的故障类型和影响因素,构建了一个全面的复合材料成形装备产线故障树,借助故障树反演技术,将实际故障事件映射到故障树上,通过逆向推导,得出可能导致这些故障事件的基本故障事件,该方法在提高生产质量、降低故障风险方面具有重要意义,为复合材料制造领域的技术改进和创新提供了有力支持。 展开更多
关键词 复合材料 成形装备 故障树 最小割集 故障诊断
下载PDF
船用堆全船断电事故的故障树分析研究 被引量:2
16
作者 宋龙飞 陈玉清 朱康 《舰船电子工程》 2024年第4期136-142,共7页
船用堆供电系统的可靠性对核动力装置的安全性有重要影响。参考某典型船用堆供电系统设计,提出了船用堆供电系统故障树建模基本原则,以全船断电事故为顶事件建立故障树,确定了系统的邻接矩阵,并基于此设计了一种故障树辅助生成及最小割... 船用堆供电系统的可靠性对核动力装置的安全性有重要影响。参考某典型船用堆供电系统设计,提出了船用堆供电系统故障树建模基本原则,以全船断电事故为顶事件建立故障树,确定了系统的邻接矩阵,并基于此设计了一种故障树辅助生成及最小割集求解程序。通过定性和定量分析得出全船断电事故的发生概率及各电源设备的重要度,并提出相应的改善措施,为船用堆供电系统的设计、使用和维护保养提供技术支撑。 展开更多
关键词 船用堆 全船断电 故障树 最小割集
下载PDF
基于直觉模糊相似关系的三支决策模型
17
作者 吕明明 薛占熬 +2 位作者 杨梦丽 辛现伟 孙林 《数据采集与处理》 CSCD 北大核心 2024年第3期617-633,共17页
针对一些直觉模糊相似关系使直觉模糊集中对象间的相似度过于集中或者相异度过高,导致不合理的分类结果的问题,以及在构造直觉模糊相似关系时,对象间的相似度和相异度容易受到不重要属性条件信息影响的问题,本文在直觉模糊集和可能性理... 针对一些直觉模糊相似关系使直觉模糊集中对象间的相似度过于集中或者相异度过高,导致不合理的分类结果的问题,以及在构造直觉模糊相似关系时,对象间的相似度和相异度容易受到不重要属性条件信息影响的问题,本文在直觉模糊集和可能性理论基础上,提出一种基于直觉模糊相似关系的三支决策模型。首先,给出可能性测度和必要性测度的定义,结合Hausdorff度量,构造一种距离公式,并证明其性质,定义了直觉模糊集中对象间的相似度和相异度,构造了新的直觉模糊相似关系;然后定义了直觉模糊相似关系下的(λ_(1),λ_(2))-截集及其直觉模糊(λ_(1),λ_(2))-截集下的相似类,并进一步求出目标集的正域、负域和边界域;最后通过UCI数据集和实例验证了该模型的合理性和有效性。 展开更多
关键词 直觉模糊相似关系 可能性理论 三支决策 截集 相似度 相异度
下载PDF
Efficient graph similarity join for information integration on graphs 被引量:4
18
作者 Yue WANG Hongzhi WANG +1 位作者 Jianzhong LI Hong GAO 《Frontiers of Computer Science》 SCIE EI CSCD 2016年第2期317-329,共13页
Graphs have been widely used for complex data representation in many real applications, such as social network, bioinformatics, and computer vision. Therefore, graph similarity join has become imperative for integrati... Graphs have been widely used for complex data representation in many real applications, such as social network, bioinformatics, and computer vision. Therefore, graph similarity join has become imperative for integrating noisy and inconsistent data from multiple data sources. The edit distance is commonly used to measure the similarity between graphs. The graph similarity join problem studied in this paper is based on graph edit distance constraints. To accelerate the similarity join based on graph edit distance, in the paper, we make use of a preprocessing strategy to remove the mismatching graph pairs with significant differences. Then a novel method of building indexes for each graph is proposed by grouping the nodes which can be reached in k hops for each key node with structure conservation, which is the k-hop tree based indexing method. As for each candidate pair, we propose a similarity computation algorithm with boundary filtering, which can be applied with good efficiency and effectiveness. Experiments on real and synthetic graph databases also confirm that our method can achieve good join quality in graph similarity join. Besides, the join process can be finished in polynomial time. 展开更多
关键词 graph similarity join edit distance constraint khop tree based indexing structure conservation boundary filtering
原文传递
基于抚育整枝目标的毛白杨枝条冲击切割性能适应性分析
19
作者 吕坤 班以琛 +2 位作者 坝仕宏 刘洋 文剑 《北京林业大学学报》 CAS CSCD 北大核心 2024年第4期158-166,共9页
【目的】为了提高毛白杨枝条冲击切割效率并改善切割效果,通过研究枝条内部因素对切割性能的影响,对毛白杨枝条的冲击切割性能进行适应性分析。【方法】以我国华北地区林场广泛种植的速生林品种毛白杨的枝条为研究对象,使用自制的枝条... 【目的】为了提高毛白杨枝条冲击切割效率并改善切割效果,通过研究枝条内部因素对切割性能的影响,对毛白杨枝条的冲击切割性能进行适应性分析。【方法】以我国华北地区林场广泛种植的速生林品种毛白杨的枝条为研究对象,使用自制的枝条切割平台进行枝条切割试验。在单因素试验的基础上采用Box-Benhnken中心组合试验方法,通过试验和理论研究枝条直径、含水率和分枝角度3个内部因素对峰值切割力和断裂效果的影响规律。【结果】(1)建立了毛白杨枝条冲击切割性能的切割机理模型;(2)通过对模型进行优化分析,得到最优参数组合为枝条直径14.7 mm、含水率14.0%、分枝角度90°,该组合下的峰值切割力为370.48 N,断裂效果评分为4.6分,峰值切割力和断裂效果分数的预测值与实测值的相对偏差均小于5%;(3)峰值切割力与枝条直径呈线性增长关系,随枝条含水率的增大呈先增大后减小的趋势,随着分枝角度的增大而小幅增大。【结论】选择树龄为7年时进行修枝作业,作业的季节选择秋冬季,可以获得较优的修枝质量,该研究可为速生林修枝装备的研发与林木抚育方式的优化结合提供数据支撑。 展开更多
关键词 机械化 抚育整枝 冲击切割 毛白杨枝条 切割适应性 切割质量参数
下载PDF
环割时间和弧度对盛果期油茶树体营养分配及结实的影响
20
作者 廖志鹏 邹中华 +5 位作者 胡冬南 谢双岭 王毓曼 廖康平 刘阳 游璐 《江西农业大学学报》 CAS CSCD 北大核心 2024年第5期1244-1255,共12页
【目的】为探明环割时间和弧度对盛果期油茶养分分配及结实的影响,阐明树体养分与果实生长之间的关系。【方法】于11月份盛花期和次年3月份春梢萌发前对7年生油茶分别进行180°、360°环割处理,环割口愈合前(5月份)、愈合后(7... 【目的】为探明环割时间和弧度对盛果期油茶养分分配及结实的影响,阐明树体养分与果实生长之间的关系。【方法】于11月份盛花期和次年3月份春梢萌发前对7年生油茶分别进行180°、360°环割处理,环割口愈合前(5月份)、愈合后(7月份、8月份、10月份)分别调查测定各器官氮磷钾养分、可溶性糖、可溶性蛋白、可溶性淀粉含量及单株果实数量、单果质量、产量,并进行分析。【结果】(1)不同条件下环割均提高了环割伤口愈合前根系无机养分以及果实膨大期叶片磷、钾、有机营养含量;同时降低了叶片氮及果实成熟期叶片可溶性糖、可溶性淀粉含量。(2)环割弧度相比环割时间,对油茶叶、根营养物质含量的影响更为显著。(3)春梢萌发前360°环割减少了油茶初期落果,提高了坐果率,增加了单株挂果数和单株鲜果产量,但其果实更小更轻。(4)油茶落果与叶、根营养间相关性不显著,但果实产量与部分叶、根营养间存在有明显的协同与拮抗关系。(5)适宜的环割处理通过增加油茶根系全钾、叶片全磷、叶片可溶性糖含量并降低根系可溶性淀粉含量显著提高坐果率及单株产量。【结论】油茶春梢萌发前360°环割有利于叶片对果实膨大期可溶性糖、果实快速生长期可溶性蛋白以及根系氮、磷、钾养分的积累,可促进挂果,减少落果,对油茶的促产效果最好。 展开更多
关键词 油茶 环割 树体养分 产量
下载PDF
上一页 1 2 63 下一页 到第
使用帮助 返回顶部