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A Tree-valued Markov Process Associated with an Admissible Family of Branching Mechanisms
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作者 Hong Wei BI Hui HE 《数学学报:英文版》 SCIE CSCD 2019年第1期135-160,共26页
Let E■R be an interval. By studying an admissible family of branching mechanisms{ψt,t ∈E} introduced in Li [Ann. Probab., 42, 41-79(2014)], we construct a decreasing Levy-CRT-valued process {Tt, t ∈ E} by pruning ... Let E■R be an interval. By studying an admissible family of branching mechanisms{ψt,t ∈E} introduced in Li [Ann. Probab., 42, 41-79(2014)], we construct a decreasing Levy-CRT-valued process {Tt, t ∈ E} by pruning Lévy trees accordingly such that for each t ∈E, Tt is a ψt-Lévy tree. We also obtain an analogous process {Tt*,t ∈E} by pruning a critical Levy tree conditioned to be infinite. Under a regular condition on the admissible family of branching mechanisms, we show that the law of {Tt,t ∈E} at the ascension time A := inf{t ∈E;Tt is finite} can be represented by{Tt*,t∈E}.The results generalize those studied in Abraham and Delmas [Ann. Probab., 40, 1167-1211(2012)]. 展开更多
关键词 PRUNING ADMISSIBLE FAMILY branching PROCESS random TREE Levy TREE tree-valued PROCESS ascension PROCESS
直径为5的一类树的能量排序 预览
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作者 贾亚荣 火博丰 +1 位作者 尹君 杜轻松 《青海师范大学学报:自然科学版》 2019年第2期7-13,共7页
一个图的能量定义为这个图邻接矩阵特征值的绝对值之和.本文研究了直径为5的一类树的能量排序.在直径为5的树中分别给定它的两个中心点的度为s+1,t+1.固定悬挂点总数,对于和树的同一个中心点相邻的任意两个点,要求与它们分别相邻的悬挂... 一个图的能量定义为这个图邻接矩阵特征值的绝对值之和.本文研究了直径为5的一类树的能量排序.在直径为5的树中分别给定它的两个中心点的度为s+1,t+1.固定悬挂点总数,对于和树的同一个中心点相邻的任意两个点,要求与它们分别相邻的悬挂点个数之差不超过1,这样得到的树记为Tn(p,s1,s;q,t1,t).本文讨论了这一类树的能量与其中参数变化的关系.这一结果有助于解决直径为5的树的极大能量问题. 展开更多
关键词 直径 结构 树的中心 极大能量
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What is a tree in the Mediterranean Basin hotspot? A critical analysis 预览
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作者 Frédéric Médail Anne-Christine Monnet +11 位作者 Daniel Pavon Toni Nikolic Panayotis Dimopoulos Gianluigi Bacchetta Juan Arroyo Zoltán Barina Marwan Cheikh Albassatneh Gianniantonio Domina Bruno Fady Vlado Matevski Stephen Mifsud Agathe Leriche 《森林生态系统:英文版》 CSCD 2019年第2期159-177,共19页
Background: Tree species represent 20% of the vascular plant species worldwide and they play a crucial role in the global functioning of the biosphere. The Mediterranean Basin is one of the 36 world biodiversity hotsp... Background: Tree species represent 20% of the vascular plant species worldwide and they play a crucial role in the global functioning of the biosphere. The Mediterranean Basin is one of the 36 world biodiversity hotspots, and it is estimated that forests covered 82% of the landscape before the first human impacts, thousands of years ago. However, the spatial distribution of the Mediterranean biodiversity is still imperfectly known, and a focus on tree species constitutes a key issue for understanding forest functioning and develop conservation strategies. Methods: We provide the first comprehensive checklist of all native tree taxa (species and subspecies) present in the Mediterranean-European region (from Portugal to Cyprus). We identified some cases of woody species difficult to categorize as trees that we further called "cryptic trees". We collected the occurrences of tree taxa by"administrative regions", i.e. country or large island, and by biogeographical provinces. We studied the species-area relationship, and evaluated the conservation issues for threatened taxa following IUCN criteria. Results: We identified 245 tree taxa that included 210 species and 35 subspecies, belonging to 33 families and 64 genera. It included 46 endemic tree taxa (30 species and 16 subspecies), mainly distributed within a single biogeographical unit. The countries with the highest tree richness are Greece (146 taxa), Italy (133), Albania (122), Spain (155), Macedonia (116), and Croatia (110). The species-area relationship clearly discriminated the richest central-eastern (Balkans) and northern (Alpine and Cevenno-Pyrenean) biogeographical provinces, against the five western provinces in the Iberian Peninsula. We identified 44 unrecognized "cryptic trees", representing 21% of the total trees. Among the 245 taxa identified, 19 are considered to be threatened (15 CR+EN+VU) or near threatened (4 NT) by IUCN. Conclusions: The Mediterranean-European region includes an unsuspectedly high number of tree taxa, almost 200 tree taxa more tha 展开更多
关键词 Plant BIOGEOGRAPHY Mediterranean REGION THREATENED trees TREE definition TREE DISTRIBUTIONS
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Competition-density effect of tree organs in Acacia auriculiformis stands 预览
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作者 Huifang Feng Li Xue 《林业研究:英文版》 CAS CSCD 2019年第3期891-898,共8页
The competition-density (C-D) effects for mean mass for tree, stem, branch and leaf were analyzed in Acacia auriculiformis stands. Mean tree mass-density and mean organ mass-density were well explained by the C-D equa... The competition-density (C-D) effects for mean mass for tree, stem, branch and leaf were analyzed in Acacia auriculiformis stands. Mean tree mass-density and mean organ mass-density were well explained by the C-D equation of tree and the C-D equation of tree organ, respectively. An equation describing the relationship between mean leaf area u and density was formulated that fit the u-data well. The relationship between mean tree mass w and the ratio of each organ to mean tree mass (wo/ w) was examined. With increasing w, the stem mass ratio wS/w increased, whereas the branch mass ratio wB/w and the leaf mass ratio wL/w decreased. The yield difference between the lowest-density stand and the high-density stand became greater with stand growth. However, the yield of the mid-density stand was slightly lower than the yield of the high-density stand during the experimental period. To produce the most desirable combination of demanding individual-tree size and relative high stem yield, the mid-density is recommended as proper planting density for future management of A. auriculiformis stands. 展开更多
关键词 ACACIA auriculiformis C-D effect Leaf area Ratio of ORGAN MASS to TREE MASS TREE ORGAN Stand yield
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星型树和双星树的谱半径的界
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作者 张友 李沐春 《西南大学学报:自然科学版》 CAS CSCD 北大核心 2019年第6期84-89,共6页
针对星型树和双星树,通过删除割点、割边的图运算方法,利用特征多项式根与系数的关系先给出了谱半径的上界,然后由已知的结论推出广义星型树图谱半径的界,最后从改变最大度和第二大度出发,通过剖分广义星型树的内部路以及外部路,得到谱... 针对星型树和双星树,通过删除割点、割边的图运算方法,利用特征多项式根与系数的关系先给出了谱半径的上界,然后由已知的结论推出广义星型树图谱半径的界,最后从改变最大度和第二大度出发,通过剖分广义星型树的内部路以及外部路,得到谱半径的变化不超过1. 展开更多
关键词 谱半径 上界
Discovering unusual structures from exception using big data and machine learning techniques
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作者 Jianshu Jie Zongxiang Hu +9 位作者 Guoyu Qian Mouyi Weng Shunning Li Shucheng Li Mingyu Hu Dong Chen Weiji Xiao Jiaxin Zheng Lin-Wang Wang Feng Pan 《科学通报:英文版》 SCIE EI CSCD 2019年第9期612-616,共5页
Recently, machine learning(ML) has become a widely used technique in materials science study. Most work focuses on predicting the rule and overall trend by building a machine learning model. However,new insights are o... Recently, machine learning(ML) has become a widely used technique in materials science study. Most work focuses on predicting the rule and overall trend by building a machine learning model. However,new insights are often learnt from exceptions against the overall trend. In this work, we demonstrate that how unusual structures are discovered from exceptions when machine learning is used to get the relationship between atomic and electronic structures based on big data from high-throughput calculation database. For example, after training an ML model for the relationship between atomic and electronic structures of crystals, we find AgO2 F, an unusual structure with both Ag3+and O22à, from structures whose band gap deviates much from the prediction made by our model. A further investigation on this structure might shed light into the research on anionic redox in transition metal oxides of Li-ion batteries. 展开更多
关键词 Machine learning GRADIENT BOOSTING decision tree Band gap UNUSUAL STRUCTURES
A Comparative Study on the Two Chinese Versions of The Apple Tree by John Galsworthy 预览
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作者 JIAO Jing 《文学与艺术研究:英文版》 2019年第5期473-478,共6页
The author establishes parallel corpus of The Apple Tree by John Galsworthy and two translated Chinese versions by Huang Zixiang and Dong Hengxun.Wordsmith and ICTCLAS are applied to make a quantitative study on the l... The author establishes parallel corpus of The Apple Tree by John Galsworthy and two translated Chinese versions by Huang Zixiang and Dong Hengxun.Wordsmith and ICTCLAS are applied to make a quantitative study on the linguistic features of the source and the target language.A comparative study is made on the translation skills and styles of the two Chinese versions.Translation samples are analyzed and appreciated.It is concluded that the form and the literal meaning of the source language is retained more in Huang’s version while the implied meaning is conveyed more in Dong’s version,with more standard,fluent,and natural Chinese and more flexible sentence structures.The socio-cultural contexts of the two translators are also considered in analyzing their styles and translation choices. 展开更多
关键词 CORPUS The Apple TREE COMPARATIVE study WORDSMITH ICTCLAS
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Strong link between large tropical volcanic eruptions and severe droughts prior to monsoon in the central Himalayas revealed by tree-ring records
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作者 Eryuan Liang Binod Dawadi +4 位作者 Neil Pederson Shilong Piao Haifeng Zhu Shalik Ram Sigdel Deliang Chen 《科学通报:英文版》 SCIE EI CSCD 2019年第14期1018-1023,共6页
Large tropical volcanic eruptions can cause short-term global cooling. However, little is known whether large tropical volcanic eruptions, like the one in Tambora/Indonesia in 1815, cause regional hydroclimatic anomal... Large tropical volcanic eruptions can cause short-term global cooling. However, little is known whether large tropical volcanic eruptions, like the one in Tambora/Indonesia in 1815, cause regional hydroclimatic anomalies. Using a tree-ring network of precisely dated Himalayan birch in the central Himalayas, we reconstructed variations in the regional pre-monsoon precipitation back to 1650 CE. A superposed epoch analysis indicates that the pre-monsoon regional droughts are associated with large tropical volcanic eruptions, appearing to have a strong influence on hydroclimatic conditions in the central Himalayas. In fact, the most severe drought since 1650 CE occurred after the Tambora eruption. These results suggest that dry conditions prior to monsoon in the central Himalayas were associated with explosive tropical volcanism. Prolonged La Ni?a events also correspond with persistent pre-monsoon droughts in the central Himalayas. Our results provide evidence that large tropical volcanic eruptions most likely induced severe droughts prior to monsoon in the central Himalayas. 展开更多
关键词 Tree ring Drought TROPICAL VOLCANIC ERUPTIONS CENTRAL HIMALAYAS
Effect of exogenous GA3 on flowering quality,endogenous hormones,and hormone-and flowering-associated gene expression in forcingcultured tree peony(Paeonia suffruticosa) 预览
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作者 GUAN Yan-ren XUE Jing-qi +3 位作者 XUE Yu-qian YANG Ruo-wen WANG Shun-li ZHANG Xiu-xin 《农业科学学报:英文版》 SCIE CAS CSCD 2019年第6期1295-1311,共17页
Gibberellins(GAs)promote flowering in the forcing-cultured tree peony(Paeonia suffruticosa),however,the mechanism of regulating flowering is not fully understood.In this study,exogenous GA3 was applied to five-year-ol... Gibberellins(GAs)promote flowering in the forcing-cultured tree peony(Paeonia suffruticosa),however,the mechanism of regulating flowering is not fully understood.In this study,exogenous GA3 was applied to five-year-old Luoyang Hong plants to explore responses in terms of endogenous hormones,flowering quality,and the hormone-and flowering-associated gene expression.Exogenous GA3 application significantly promoted flower bud development and new branch growth,as well as improved flowering quality.Exogenous GA3 application also stimulated the synthesis of endogenous GA3 and indole-3-acetic acid(IAA)but reduced abscisic acid(ABA)levels.To further elucidate the regulatory mechanism,eight genes for GA biosynthesis and signaling,including PsCPS,PsKS,PsGA3ox,PsGA2ox,PsGID1b,PsGID1c,PsDELLA,and PsGID2 were cloned for the first time,and sequence analysis was also performed.The results suggested that all the cloned genes have conserved structure as each homologous gene reported in the other species.Phylogenetic trees constructed by the each cloned gene showed that the phylogenetic evolutionary relationship of P.suffruticosa was closely related to Vitis vinifera.The expression patterns of the above genes,and genes for ABA and IAA biosynthetic and signaling,and the flowering time were also investigated.Most of the above genes showed higher expression in the control buds than those in the GA3 treated buds at six developmental stages,whereas the expression levels of PsSOC1 and PsSPL9 were up-regulated by GA3 treatment.The results also showed that the GA-biosynthetic and signaling pathways are conserved in tree peony,and the PsCPS,PsGA3ox,PsGA2ox,PsGID1,PsDELLA,and PsGID2 genes are necessary for feedback regulation of GAs.Furthermore,hormone changes promoted PsSOC1 and PsSPL9 expression,and repressed PsSVP expression,which contributed to the improvement flowering quality in tree peony of forcing culture. 展开更多
关键词 tree PEONY FORCING culture HORMONES gibberellic acid GA BIOSYNTHESIS and signaling FLOWERING QUALITY
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Genetic Structure of the Red-spotted Tokay Gecko, Gekko gecko(Linnaeus, 1758)(Squamata: Gekkonidae) from Mainland Southeast Asia
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作者 Weerachai SAIJUNTHA Sutthira SEDLAK +7 位作者 Takeshi AGATSUMA Kamonwan JONGSOMCHAI Warayutt PILAP Watee KONGBUNTAD Wittaya TAWONG Warong SUKSAVATE Trevor N.PETNEY Chairat TANTRAWATPAN 《亚洲两栖爬行动物研究:英文版》 SCIE CSCD 2019年第2期69-78,共10页
This study was performed to explore the genetic diversity and genetic structure of red-spotted tokay geckos(Gekko gecko) from 23 different geographical areas in Thailand, Lao PDR and Cambodia. The mitochondrial tRNAGl... This study was performed to explore the genetic diversity and genetic structure of red-spotted tokay geckos(Gekko gecko) from 23 different geographical areas in Thailand, Lao PDR and Cambodia. The mitochondrial tRNAGln/tRNA-Met/partial NADH dehydrogenase subunit 2 from 166 specimens was amplified and sequenced. A total of 54 different haplotypes were found. Highly significant genetic differences occurred between populations from different localities. The haplotype network revealed six major haplogroups(G1 to G6) belonging to different clades(clade A–E). Clade D and clade E were newly observed in this study. Haplogroup G4(clade D) was a sympatric population with haplogroup G1(clade B). The populations from northern Thailand were divided into two distinct haplogroups separated by mountain range. Genetic structure and genetic differentiation of the tokay in Southeast Asia was related to the geographical region sampled, spatial distance and natural barriers. Our results indicate that red-spotted tokay geckos from mainland Southeast Asia are cryptically diverse. Morphological comparisons, in addition to an intensive genetic investigation covering the whole species range, are needed to clarify the systematic and population structure of this species group. 展开更多
关键词 Genetic diversity Gene flow Natural barrier PHYLOGENETIC tree HAPLOTYPE network
Optimization Model Research on Major Underlying Factors in the Subhealth Condition Evaluation in 1 City and 7 Provinces in China
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作者 Hong-Mei Ni Yu-Min He Xu-Ming Yang 《世界中医药杂志:英文版》 2019年第2期88-94,共7页
Background:The study aimed to analyze major underlying factors of the subhealth condition evaluation and find the optimization model.Methods:Selected 524 cases of health state and 453 cases of subhealth state from the... Background:The study aimed to analyze major underlying factors of the subhealth condition evaluation and find the optimization model.Methods:Selected 524 cases of health state and 453 cases of subhealth state from the research objects.A genetic algorithm was applied to discover the optimization model.The decision tree algorithm was used to find the main performance in the areas of physical,psychological,and social adaptation in the two populations which were the health state and the subhealth state.Conclusions:To establish the optimization model,the author would set up a curve-fitting equation between reduction of health self-assessment score(S-G1)and white blood cell(WBC)value in routine blood,so as to establish the relationship between S-G1 and WBC and found the approximate minimum solution of each equation.Besides,the author would analyze the differences between two populations in WBC examination to seize the difference.Revealed the differences of two populations in the areas of physical,psychological,and social adaptation by data mining and got the result that WBC of"the health state population"was higher than that of"the sub-health state population"in the index changes of WBC.The problem in social adaptation area of the subhealth state population was more serious in degree than the health state population;the reason was complex.If WBC of the health state population was near or below 5.5079,the object may be in the state of subhealth.However,if WBC was near or below 4.35,it is possible to enter the"morbid state." 展开更多
关键词 CURVE fitting decision tree genetic algorithm health state subhealth state white cell COUNT value
Fault-tolerant precise data access on distributed log-structured merge-tree
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作者 Tao ZHU Huiqi HU +2 位作者 Weining QIAN Huan ZHOU Aoying ZHOU 《中国计算机科学前沿:英文版》 SCIE EI CSCD 2019年第4期760-777,共18页
Log-structured merge tree has been adopted by many distributed storage systems. It decomposes a large database into multiple parts: an in?writing part and several read-only ones. Records are firstly written into a mem... Log-structured merge tree has been adopted by many distributed storage systems. It decomposes a large database into multiple parts: an in?writing part and several read-only ones. Records are firstly written into a memoryoptimized structure and then compacted into in-disk struc? tures periodically. It achieves high write throughput. However, it brings side effect that read requests have to go through multiple structures to find the required record. In a distributed database system, different parts of the LSM-tree are stored in distributed fashion. To this end, a server in the query layer has to issues multiple network communications to pull data items from the underlying storage layer. Coming to its rescue, this work proposes a precise data access strategy which includes: an efficient structure with low maintaining overhead designed to test whether a record exists in the in?writing part of the LSM-tree;a lease-based synchronization strategy proposed to maintain consistent copies of the structure on remote query servers. We further prove the technique is capable of working robustly when the LSM-Tree is re?organizing multiple structures in the backend. It is also fault-tolerant, which is able to recover the structures used in data access after node failures happen. Experiments using the YCSB benchmark show that the solution has 6x throughput improvement over existing methods. 展开更多
关键词 DISTRIBUTED data storage log-structured MERGE TREE linearizability fault tolerance
给定度序列的AZI指数值最小的树 预览
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作者 甘露 周耀鹏 《湖北师范大学学报:自然科学版》 2019年第2期28-31,共4页
增强型的萨格勒布指数(简称AZI)是被B.Furtula等人提出的一类拓扑指数.该指数已被证实在辛烷和正庚烷的热形成研究中是一个有价值的预测性指数.本文将研究在给定度序列的条件下,AZI指数值最小的树的特点,并给出一个算法构造出此树.
关键词 AZI指数 度序列
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树状能量网络故障检测
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作者 杨文 赵千川 《系统科学与数学》 CSCD 北大核心 2019年第2期278-285,共8页
研究具有树形拓扑的能量网络故障检测问题,基于能量分层平衡关系,给出传感器故障和设备故障的检测条件.与已有研究相比,文章得到的结果优点在于可以同时分析传感器故障和设备故障.文章给出的条件仅利用了系统每个节点的相关范围的局部信... 研究具有树形拓扑的能量网络故障检测问题,基于能量分层平衡关系,给出传感器故障和设备故障的检测条件.与已有研究相比,文章得到的结果优点在于可以同时分析传感器故障和设备故障.文章给出的条件仅利用了系统每个节点的相关范围的局部信息,可用于在大规模网络化系统中实施并发的分布式故障检测. 展开更多
关键词 能量网络 故障检测
Research on Data Privacy Protection Algorithm with Homomorphism Mechanism Based on Redundant Slice Technology in Wireless Sensor Networks 预览
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作者 Peng Li Chao Xu +2 位作者 He Xu Lu Dong Ruchuan Wang 《中国通信:英文版》 SCIE CSCD 2019年第5期158-170,共13页
Wireless transmission method in wireless sensor networks has put forward higher requirements for private protection technology. According to the packet loss problem of private protection algorithm based on slice techn... Wireless transmission method in wireless sensor networks has put forward higher requirements for private protection technology. According to the packet loss problem of private protection algorithm based on slice technology, this paper proposes the data private protection algorithm with redundancy mechanism, which ensures privacy by privacy homomorphism mechanism and guarantees redundancy by carrying hidden data. Moreover,it selects the routing tree generated by CTP(Collection Tree Protocol) as routing path for data transmission. By dividing at the source node, it adds the hidden information and also the privacy homomorphism. At the same time,the information feedback tree is established between the destination node and the source node. In addition, the destination node immediately sends the packet loss information and the encryption key via the information feedback tree to the source node. As a result,it improves the reliability and privacy of data transmission and ensures the data redundancy. 展开更多
关键词 wireless sensor network PRIVACY PROTECTION SLICE TECHNOLOGY PRIVACY HOMOMORPHISM collection tree protocol
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多层中继网络上的分布式LT码 预览
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作者 张艳 陈建华 唐猛 《电子与信息学报》 EI CSCD 北大核心 2019年第7期1548-1554,共7页
目前对分布式LT码(DLT)的研究仅限于信源数量较少、且只有1层中继的情况,该文提出一种能够部署在多层中继网络上的分布式LT码,即多层分布式LT码(MLDLT)。该码将信源进行分组,将中继进行分层,通过分层后的中继群,可以将多达几十个乃至上... 目前对分布式LT码(DLT)的研究仅限于信源数量较少、且只有1层中继的情况,该文提出一种能够部署在多层中继网络上的分布式LT码,即多层分布式LT码(MLDLT)。该码将信源进行分组,将中继进行分层,通过分层后的中继群,可以将多达几十个乃至上百个信源连接到同一个接收端,从而实现众多信源通过多层中继对同一个接收终端的分布式LT码通信。通过对MLDLT码进行与或树分析,得出其中继度分布的线性优化方程。分别在无损和有损链路上计算该码的渐进性能并进行数值仿真,结果证明MLDLT码在无损和有损链路上的错误平台都比较低。MLDLT码非常适合于信源数量较多的多层中继网络。 展开更多
关键词 分布式LT码 度分布 与或树 渐进性能
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Complementary parametric probit regression and nonparametric classification tree modeling approaches to analyze factors affecting severity of work zone weather-related crashes 预览
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作者 Ali Ghasemzadeh Mohamed M. Ahmed 《现代交通学报:英文版》 2019年第2期129-140,共12页
Identifying risk factors for road traffic injuries can be considered one of the main priorities of transportation agencies. More than 12,000 fatal work zone crashes were reported between 2000 and 2013. Despite recent ... Identifying risk factors for road traffic injuries can be considered one of the main priorities of transportation agencies. More than 12,000 fatal work zone crashes were reported between 2000 and 2013. Despite recent efforts to improve work zone safety, the frequency and severity of work zone crashes are still a big concern for transportation agencies. Although many studies have been conducted on different work zone safety-related issues, there is a lack of studies that investigate the effect of adverse weather conditions on work zone crash severity. This paper utilizes probit–classification tree, a relatively recent and promising combination of machine learning technique and conventional parametric model, to identify factors affecting work zone crash severity in adverse weather conditions using 8 years of work zone weatherrelated crashes (2006–2013) in Washington State. The key strength of this technique lies in its capability to alleviate the shortcomings of both parametric and nonparametric models. The results showed that both presence of traffic control device and lighting conditions are significant interacting variables in the developed complementary crash severity model for work zone weather-related crashes. Therefore, transportation agencies and contractors need to invest more in lighting equipment and better traffic control strategies at work zones, specifically during adverse weather conditions. 展开更多
关键词 ADVERSE WEATHER Work zone Safety CRASH characteristics PROBIT model Decision tree
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Simulated Reflectance of Apple Trees in Canopy Level Based on the PROSAIL Model and HJ-1A-HSI Data 预览
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作者 Xiaoyan Guo Xicun Zhu +5 位作者 Jingling Xiong Ruiyang Yu Xueyuan Bai Yuanmao Jiang Dongsheng Gao Guijun Yang 《遥感科学:中英文版》 2019年第1期18-26,共9页
Using the PROSAIL radiation transfer model and HJ-1A-HSI data to simulate the canopy reflectivity of apple trees, this study lays the foundation for the inversion of canopy parameters. Taking Qixia City of Yantai City... Using the PROSAIL radiation transfer model and HJ-1A-HSI data to simulate the canopy reflectivity of apple trees, this study lays the foundation for the inversion of canopy parameters. Taking Qixia City of Yantai City, Shandong Province as the research area, the apple tree was taken as the research object, and the hyperspectral reflectance, LAI and sample GPS of apple canopy were measured in the field. The parameters required for the PROSAIL model were obtained by experimental methods. The model simulates the reflectivity;the HSI image data is preprocessed, and the canopy reflectivity is extracted by GPS coordinates. The PROSAIL model and the HSI image simulated reflectance were fitted to the measured apple canopy reflectivity. The decisive factor (R2) of the simulated reflectance and the measured reflectance of the PROSAIL model was 0.9944, and the relative error (RE%)was 0.1845. The HSI data simulated reflectance and measured reflectance. The coefficient of determination is 0.9714 and the relative error is 0.6202. Both have achieved good fitting effects and can be used for inversion studies of apple canopy parameters. 展开更多
关键词 APPLE TREE PROSAIL Model HJ-1A-HSI CANOPY REFLECTIVITY
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Inversion of Canopy Nitrogen Content in Apple Orchard Based on GF-1 Satellite Image 预览
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作者 Shujing Cao Xicun Zhu +5 位作者 Jingling Xiong Ruiyang Yu Xueyuan Bai uanmao Jiang Dongsheng Gao Guijun Yang 《遥感科学:中英文版》 2019年第1期27-38,共12页
The apple orchard in Qixia City, Yantai City, Shandong Province was used as the research area. The nitrogen content inversion of apple canopy was studied by using the satellite remote sensing images of GF-1. On the ba... The apple orchard in Qixia City, Yantai City, Shandong Province was used as the research area. The nitrogen content inversion of apple canopy was studied by using the satellite remote sensing images of GF-1. On the basis of GF-1 satellite multispectral image preprocessing, vegetation index was extracted by band math. The nitrogen sensitive vegetation index of apple canopy was selected by correlation analysis of nitrogen content in apple canopy. The best inversion model for the nitrogen content of apple canopy was selected by establishing the regression model of univariate and multivariate factors. The nitrogen content of the canopy of apple orchard in the study area was inverted in space. The results showed that the 6 vegetation indices of RVI, NDVI, EVI, VARI, NPCI and NRI were better correlated with nitrogen content in the vegetation index based on GF-1 satellite multispectral imaging. The best inversion model of nitrogen content in apple canopy layer is the multivariate stepwise regression (MSR) model: Nc = 35.74– 41.978^*NPCI-10.78^*NDVI. The R^2 and RMSE of the model was 0.69 and 1.07. The spatial inversion of nitrogen content in apple orchard canopy was obtained. This study provided theoretical basis and technical support for large-area rapid monitoring of regional fruit tree nutrients. 展开更多
关键词 GF-1 NITROGEN Content INVERSION APPLE TREE CANOPY
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树图的外围维纳指标的下界 预览
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作者 雷思宇 李冠村 《闽南师范大学学报:自然科学版》 2019年第2期14-18,共5页
设G=(V,E)为简单连通图.对v∈V(G),顶点v的离心率ε(v)=max{d(u,v)│u∈V(G)}, d(u,v)为图G中顶点u,v间的距离.图G的直径为d(G)=max{ε(v)│v∈V(G)}.外围顶点集P(G)指图G中满足ε(v)=d(G)的所有v=V(G).图G的外围维纳指标为PW(G)=∑({u... 设G=(V,E)为简单连通图.对v∈V(G),顶点v的离心率ε(v)=max{d(u,v)│u∈V(G)}, d(u,v)为图G中顶点u,v间的距离.图G的直径为d(G)=max{ε(v)│v∈V(G)}.外围顶点集P(G)指图G中满足ε(v)=d(G)的所有v=V(G).图G的外围维纳指标为PW(G)=∑({u,v}∈P(G))d(u,v).首先讨论了当树图T的外围顶点个数确定时,它的第二下界;然后讨论了当树图T的顶点数目确定时,其对应的PW(T)的最小值,及达到其最小值的极图. 展开更多
关键词 外围维纳指标 下界
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