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Search Results: 1 - 10 of 34413 matches for " Chunfa Zhou "
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Habitat Association and Conservation Implications of Endangered Francois’ Langur (Trachypithecus francoisi)
Yajie Zeng, Jiliang Xu, Yong Wang, Chunfa Zhou
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0075661
Abstract: Francois’ langur (Trachypithecus francoisi) is an endangered primate and endemic to the limestone forests of the tropical and subtropical zone of northern Vietnam and South-west China with a population of about 2,000 individuals. Conservation efforts are hampered by limited knowledge of habitat preference in its main distribution area. We surveyed the distribution of Francois’ langur and modeled the relationship between the probability of use and habitat features in Mayanghe National Nature Reserve, Guizhou, China. The main objectives of this study were to provide quantitative information on habitat preference, estimating the availability of suitable habitat, and providing management guidelines for the effective conservation of this species. By comparing 92 used locations with habitat available in the reserve, we found that Francois’ langur was mainly distributed along valleys and proportionally, used bamboo forests and mixed conifer-broadleaf forests more than their availability, whereas they tended to avoid shrubby areas and coniferous forests. The langur tended to occur at sites with lower elevation, steeper slope, higher tree canopy density, and a close distance to roads and water. The habitat occupancy probability was best modeled by vegetation type, vegetation coverage, elevation, slope degree, distances to nearest water, paved road, and farmland edge. The suitable habitat in this reserve concentrated in valleys and accounted for about 25% of the total reserve area. Our results showed that Francois’ langur was not only restricted at the landscapes level at the regions with karst topography, limestone cliffs, and caves, but it also showed habitat preference at the local scale. Therefore, the protection and restoration of the langur preferred habitats such as mixed conifer-broadleaf forests are important and urgent for the conservation of this declining species.
Influence of potential cavity resources on secondary cavity-nesters and breeding bird community composition

Daqing Zhou,Chunfa Zhou,Wenhong Deng,

生物多样性 , 2009,
Abstract: To explore how density of potential cavity resources (including cavities and artificial nest boxes) affects the composition and distribution of secondary cavity-nesting guilds, as well as the community structure of breeding birds, we studied plots with different densities of nest cavities in Dagang Forestry Farm, Jilin Province, China from November 2007 to July 2008. Based on the density of cavity resources, the nine sample sites were divided into three treatments, i.e., NBP (nest-box plots with less cavities and high-density nest boxes), LDP (low-density cavities plots without nest boxes) and HDP (high-density cavities plots without nest boxes). We then surveyed avian communities and noted the use of cavities and artificial nest boxes. All the treatments contained four primary cavity excavators, and three species were the same. Four secondary cavity nesters were widespread in the three treatments, including the great tit {Parus major), marsh tit (P. palustris), yellow-rumped flycatcher (Ficedula zanthopygia) and eurasian nuthatch (Sitta europaea). Total densities of secondary cavity nesters in NBP and HDP were higher than that of LDP. Densities of great tits and yellow-rumped flycatchers were higher in NBP and HDP than in LDP, because they were major users of nest boxes. There were no significant differences in the densities of marsh tits and eurasian nuthatches among treatments. A significant positive correlation was detected between the density of primary cavity excavators and cavity density, and also between the density of secondary cavity nesters and potential cavity resources. Bird species diversity indices were lower in LDP than in NBP and HDP. Nest-box addition could potentially regulate the composition of avian communities by increasing bird species diversity indices. We observed no differences in evenness, species richness indices or probability of interspecific encounter (PIE) among treatments, and Serensen similarity indices differed little among treatments. There were no obvious differences in structure of breeding bird guilds between HDP and LDP. Nine species were found in all the three treatments, and their densities were not affected by the temporary increase in secondary cavity nesters. We hypothesize that density of primary cavity excavators determines the density of cavities in forests, which may change distributional patterns of secondary cavity-nester guilds, and therefore affect the structure of breeding avian communities.
Finite Element Simulation of Thermal Field in Double Wire Welding  [PDF]
Xiuzhi Yang, Chunjie Yang, Chunfa Dong, Xinhua Xiao, Wenlin Hua, Xiangjie Wang
Journal of Materials Science and Chemical Engineering (MSCE) , 2016, DOI: 10.4236/msce.2016.412002
In this paper, the thermal field of double wire welding is simulated by using ANSYS software. Simulation results were shown that the total heat input (E) is the most significant parameters to change the value of t8/5; By the mean of rationally controlling the proportion of the front arc heat input (E1) in the total heat input (E) and appropriately selecting double wire spacing (L), It is effective means to get the double wire welding thermal cycle. By the way of simulation, it is possible to manage the thermal input in the double welding wires and to control the temperature field and cooling rate that are fundamental for the final joint quality, it is great importance guidance to optimize the double wire welding process parameters.
Model selection for quantitative trait loci mapping in a full-sib family
Tong, Chunfa;Zhang, Bo;Li, Huogen;Shi, Jisen;
Genetics and Molecular Biology , 2012, DOI: 10.1590/S1415-47572012005000044
Abstract: statistical methods for mapping quantitative trait loci (qtls) in full-sib forest trees, in which the number of alleles and linkage phase can vary from locus to locus, are still not well established. previous studies assumed that the qtl segregation pattern was fixed throughout the genome in a full-sib family, despite the fact that this pattern can vary among regions of the genome. in this paper, we propose a method for selecting the appropriate model for qtl mapping based on the segregation of different types of markers and qtls in a full-sib family. the qtl segregation patterns were classified into three types: test cross (1:1 segregation), f2 cross (1:2:1 segregation) and full cross (1:1:1:1 segregation). akaike's information criterion (aic), the bayesian information criterion (bic) and the laplace-empirical criterion (lec) were used to select the most likely qtl segregation pattern. simulations were used to evaluate the power of these criteria and the precision of parameter estimates. a windows-based software was developed to run the selected qtl mapping method. a real example is presented to illustrate qtl mapping in forest trees based on an integrated linkage map with various segregation markers. the implications of this method for accurate qtl mapping in outbred species are discussed.
EM Algorithm for Mapping Quantitative Trait Loci in Multivalent Tetraploids
Jiahan Li,Kiranmoy Das,Guifang Fu,Chunfa Tong,Yao Li,Christian Tobias,Rongling Wu
International Journal of Plant Genomics , 2010, DOI: 10.1155/2010/216547
Abstract: Multivalent tetraploids that include many plant species, such as potato, sugarcane, and rose, are of paramount importance to agricultural production and biological research. Quantitative trait locus (QTL) mapping in multivalent tetraploids is challenged by their unique cytogenetic properties, such as double reduction. We develop a statistical method for mapping multivalent tetraploid QTLs by considering these cytogenetic properties. This method is built in the mixture model-based framework and implemented with the EM algorithm. The method allows the simultaneous estimation of QTL positions, QTL effects, the chromosomal pairing factor, and the degree of double reduction as well as the assessment of the estimation precision of these parameters. We used simulated data to examine the statistical properties of the method and validate its utilization. The new method and its software will provide a useful tool for QTL mapping in multivalent tetraploids that undergo double reduction. 1. Introduction Genetic analysis in polyploids has received considerable interest in recent years because of the biological and economic importance [1–3]. Genetic linkage maps constructed from molecular markers have been published for several major polyploids [4–10]. Statistical models for linkage analysis and map construction that consider unique biological properties of polyploids have been developed [11–14]. For bivalent polyploids, Wu et al. [15, 16] incorporated the so-called chromosomal pairing preference [17] into the linkage analysis framework, to increase the biological relevance of linkage mapping models. There have been several statistical models developed to map quantitative trait loci (QTLs) in bivalent polyploids [18, 19]. There is also a group of polyploids, called multivalent polyploids, in which chromosomes pair among more than two homologous copies at meiosis, rather than only two copies as like in bivalent polyploids. The origin of multivalent polyploids is mostly from the duplication of similar genomes and, for this reason, they are called autopolyploids [20, 21]. The consequence of multivalent pairing in autopolyploids is the occurrence of double reduction, that is, two sister chromatids of a chromosome sort into the same gamete [22]. Fisher [23] proposed a conceptual model for characterizing the individual probabilities of 11 different modes of gamete formation for a quadrivalent polyploid in terms of the recombination fraction between two different loci and their double reductions. Wu et al. [24] used Fisher's model to derive the EM algorithm for the
Multiallelic epistatic model for an out-bred cross and mapping algorithm of interactive quantitative trait loci
Chunfa Tong, Bo Zhang, Zhong Wang, Meng Xu, Xiaoming Pang, Jingna Si, Minren Huang, Rongling Wu
BMC Plant Biology , 2011, DOI: 10.1186/1471-2229-11-148
Abstract: Here we have formulated a general framework to model and define the epistasis between multiallelic QTLs. Based on this framework, we have derived a statistical algorithm for the estimation and test of multiallelic epistasis between different QTLs in a full-sib family of outcrossing species. We used this algorithm to genomewide scan for the distribution of mul-tiallelic epistasis for a rooting ability trait in an outbred cross derived from two heterozygous poplar trees. The results from simulation studies indicate that the positions and effects of multiallelic QTLs can well be estimated with a modest sample and heritability.The model and algorithm developed provide a useful tool for better characterizing the genetic control of complex traits in a heterozygous family derived from outcrossing species, such as forest trees, and thus fill a gap that occurs in genetic mapping of this group of important but underrepresented species.Approaches for quantitative trait locus (QTL) mapping were developed originally for experimental crosses, such as the backcross, double haploid, RILs or F2, derived from inbred lines [1-3]. Because of the homozygosity of inbred lines, the Mendelian (co)segregation of all markers each with two alternative alleles in such crosses can be observed directly. In practice, there is also a group of species of great economical and environmental importance - out-crossing species, such as forest trees, in which traditional QTL mapping approaches cannot be appropriately used. For these species, it is difficult or impossible to generate inbred lines due to long generation intervals and high heterozygosity [4], although experimental hybrids have been commercially used in practical breeding programs.For a given outbred line, some markers may be heterozygous, whereas others may be homozygous over the genome. All markers may, or may not, have the same allele system between any two outbred lines used for a cross. Also, for a pair of heterozygous loci, their allel
The fluid inclusion geochemistry and mineragenetic type of the Wangfeng gold deposit, Xinjiang, China

ZHANG Li,LIU ChunFa,WU Guang,

岩石学报 , 2009,
Abstract: 西天山东缘的望峰金矿床受胜利达坂韧性剪切带的控制,成矿过程包括早、中、晚3个阶段,自然金和矿石矿物主要形成于中阶段。岩相学、显微测温及单个包裹体成分激光拉曼光谱研究表明,望峰金矿床石英中的流体包裹体有CO2-H2O型、纯CO2型、NaCl-H2O溶液型和含子晶多相等4种类型。早阶段石英中原生包裹体主要是CO2-H2O型,其盐度1.62%~8.03% NaCl eqv.,流体密度0.73~0.89g/cm3,均一温度为250~390℃,气相成分为CO2。中阶段石英中的原生包裹体包括了所有4种类型,其CO2-H2O型和NaCl-H2O溶液型包裹体的均一温度分别为210~340℃和230~300℃,显示了流体沸腾现象的存在。CO2-H2O型包裹体的盐度0.83%~9.59% NaCl eqv.,密度0.77~0.95g/cm3,气相成分为CO2±CH4±N2。晚阶段石英只发育水溶液包裹体,具有较低的盐度(0.35%~3.87% NaCl eqv.)和均一温度(120~214℃)。根据CO2-H2O型包裹体估算早、中阶段流体包裹体捕获压力分别为110~300PMa和90~250MPa,成矿深度为9~11km。总体而言,望峰金矿床由低盐度、低密度、富CO2的变质流体系统形成,流体减压沸腾导致矿质沉淀,属于中深带的造山型金矿系统。
Frontiers and Challenges of Sciences and Technologies in Modern Railway Engineering

翟婉明, 赵春发
ZHAI Wanming
, ZHAO Chunfa

- , 2016, DOI: 10.3969/j.issn.0258-2724.2016.02.001
Abstract: 围绕现代轨道交通的四大重点领域高速铁路、重载铁路、城市轨道交通和磁悬浮交通,介绍了当前国内外最新发展动态,特别是我国轨道交通发展现状及其在国际上所处的地位与水平.结合轨道交通工程学科发展趋势与应用需求,分析了轨道交通工程建设与运营过程中涉及系统安全性、运营可靠性和环境适应性等方面的主要技术瓶颈,指出了高速铁路、重载铁路、城市轨道交通和磁悬浮交通领域当前值得关注的前沿科学问题和技术挑战,为今后深入开展轨道交通科学技术研究(特别是针对处于快速发展期的中国轨道交通科技研究)提供有益参考.
: The article reviews the most recent developments in China and abroad in four key fields of modern railway engineering high-speed railway, heavy-haul railway, urban rail transit and maglev transport, with particular emphasis on the status and position of Chinese railways in the world. Focusing on the safety, reliability and environmental suitability of railway transportation system, key frontier problems and challenges of sciences and technologies in the domains of high-speed railway, heavy-haul railway, urban rail transit and maglev transport are pointed out, respectively, which provides valuable references for future researches, and is especially helpful for the rapid development of Chinese high-speed railways and urban rail transits
Numerical Analysis of Static Crushed Behavior of Railway Ballast

张徐, 赵春发, 翟婉明
, ZHAO Chunfa, ZHAI Wanming

- , 2015,
Abstract: 摘要: 为揭示碎石道砟静态受压力学行为与破碎机理,用激光扫描仪获得道砟的真实几何形态,采用球形单元构建了道砟的离散元模型;通过定义单元间接触与黏结行为,模拟了30~60 mm粒径道砟的静态压碎过程,分析了压碎过程中载荷-位移响应以及内部力链和黏结断裂的分布与演化.结果表明:道砟静态压碎特征强度的离散性大且服从Weibull分布,这与已有试验结果一致;初始加载时,尖锐棱角和表面不平整导致道砟表面接触点应力集中与局部压碎,引起道砟翻转及接触状态变化,内部力链分布随之变化,载荷出现短暂回落;道砟稳定弹性变形阶段,部分单元间的接触力随载荷增大逐渐超过黏接强度,出现黏结断裂和局部微裂纹;当黏结断裂数量急剧增加到一定规模时,内部裂纹快速扩展,道砟最终劈裂破碎.
Abstract: In order to reveal the static compressive behavior and breakage mechanism of railway ballast, the discrete element method was applied to simulate its crushed behavior under statically loading between two flat platens. A laser scanner was used to obtain the three dimensional morphology of a ballast. Discrete element models for the ballast with a realistic shape were constructed using hexagonal close packed agglomerates. Contact and bond behaviors between particles were defined in these models. History of load-displacement, distribution evolution of force chain and broken bonds in the ballast during the crush process were analyzed. The numerical results show that the characteristic strength of railway ballast follows a Weibull distribution, being consistent with the existing experimental results. Stress concentration at ballast surface and local crush due to sharp corner and surface irregularity induce the initial rotation of ballast and the change of its contact state, resulting in variation of force chain distribution in the ballast and a short drop of load. During the stable elastic response phase, contact forces between some parts of elements gradually increase with the enlargement of load and then exceed the bond strength, thus broken bonds exist in the ballast. When the number of broken bonds dramatically increases and reaches a certain scale, the ballast is crushed due to the rapid propagation of internal micro cracks
Openingclosing tectonics: Exploration of a new idea on global tectonics.

YANG Weiran
,JIANG Chunfa,ZHANG Kang,GUO Tieying

- , 2016, DOI: 10.13745/j.esf.2016.06.005
Abstract: 20世纪60—70年代,是我国大地构造研究领域学术思想最为活跃的时期,1979年全国第二届构造地质学术会上,出现八大学派的领军人物同台亮相阐明各自观点的壮观场面。尔后多旋回学说的领军人黄汲清及其继承人之一姜春发、断块构造学说的领军人张文佑及其继承人之一张抗、区域大地构造学说的领军人马杏垣及其继承人之一杨巍然几乎同时分别提出多旋回手风琴式开合、断块开合和“开”“合”构造观点。三大学派殊途同归携手创建了具有中国特色的开合构造理论,开合构造理论是研究开合运动及其形成的地质体的结构构造特征和规律的学科。本文是对开合构造研究的新一轮成果的总结。(1)开合运动的基本属性为:开合运动是一切地质体运动的基本形式;它揭示了各种地质运动之间的内在联系和本质特征;开与合是地球动力学中一对主要矛盾,二者相互依存、相互对立、相互转换,转换点(区)时空的定位具有重要的理论和实践意义。(2)地学开合律为开合运动规律的总结:它包括开合运动规模上的级次性和层次性;时间上的旋回性、空间上的互补性、演化上的方向性,并总结出由简至繁和从点开始、到线、再到面的开合迁移演化模式。(3)开合构造研究中几个重要概念:开合标志是指能确定开合属性的各种地质现象,它是研究开合构造的基础资料;开合建造及建造序列是研究开合过程中物质的组合特征,它们反映了该物质组合形成时的构造环境及开合构造演化的阶段;开合构造类型是根据开合标志的综合,总结出不同级次和层次的开合运动的组合规律,它反映了大陆大洋开合演化的不同阶段,目前已总结出8种开合构造类型;开合构造单位是开合构造综合特征和开合构造类型空间分布规律的总结,提出了以大陆一级构造单位为开合构造集群的新概念,它强调集群内各地质体具成生联系和它们围绕核心陆块从点(块)到线(带)再到面(体)的演化规律;笔者将亚洲中部划分了4个开合构造集群。(4)在开合运动和旋转运动长期共同作用下,形成了地球的层圈结构和各种地质构造。其中开合运动是主导的,旋转运动则是调整开合运动达到相对稳定的动态平衡状态,称之为开合旋构造体系;动态平衡体系一度或局部被破坏,并经调整达到新平衡的过程称构造运动,诸如导致地史中出现重大地质事件的晋宁运动、加里东运动、海西运动、燕山运动等。旋转运动调整开合运动达到平衡是通过地球旋转速度短暂的细微变化和地球层圈间旋转速度短暂细微的差异而实现的。(5)构造运动是开合旋动态平衡体系一度或局部被破坏,并经调整达到新平衡这一过程的真实记录。构造运动的主要动因是地球的热能和重力能:地核是不断向上提供热能的热能库;重力在核幔边界形成开合构造转换地带,成为以热能为主的综合能量形成和聚集的基地。在一定条件下,富含综合能量的物质,上升至地幔和地壳不同层位与围岩化合或混合成不同特点的熔融热流体,它们是导致各种地质事件的产生和各种地质构造形成的直接原因。(6)活动论和固定论长期争论不休,其焦点是地壳运动是水平运动还是垂直运动为主。通过时空分析,地壳不可能分出是以水平还是垂直运动为主。实际上垂直运动和水平运动共同存在于开合构造体系之中,是开合运动中两种形式——水平开合与垂直开合。因此,垂直运动与水平运动之争无实际意义。
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