共查询到19条相似文献,搜索用时 125 毫秒
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地球系统科学数据是支撑地球系统科学和全球变化创新研究的重要基础,也是社会经济发展决策的科学依据。长期以来,我国缺乏可真正运行的地球系统科学数据共享平台,造成了数据资源的重复投资和浪费,严重影响了我国地学创新研究水平,减缓了地学大国向地学强国迈进的步伐。由于地球系统科学数据具有分散、海量、多源、异构和时空特征明显等特点,其共享尤其复杂和困难,已经成为地学研究领域重要的国际前沿。项目通过地球科学、计算机科学技术、天文学等领域的40多个单位400多名学者10多年的协同研究,突破了分散科学数据持续共享的机制,攻克了分散、多源、异构地球系统科学数据的集成方法、标准规范和关键技术,建成并运行我国地球系统科学数据共享国家平台,提供了持续的数据共享服务。 相似文献
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地球系统科学数据共享网是国家科技基础条件平台中以整合共享分散科学数据为重点的项目。作为国家“科学数据共享工程”前批9个试点之一,该项目于2003年启动,2005年纳入国家科技基础条件平台进入建设阶段,2009年通过国家科技单位评估和验收,开始进入运行服务阶段。通过6年多的研究与实践,地球系统科学数据共享网(以下简称“共享网”)为我国科技创新、国家宏观战略决策和社会经济发展提供了大量的数据服务,引领和推动了我国的科学数据共享,提升了我国科学数据共享在国际上的地位。 相似文献
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科学数据共享平台之数据联盟模式初探 总被引:2,自引:0,他引:2
数据资源建设是科学数据共享平台建设的重要内容之一,也是其难点之一。本文比较了我国科学数据共享平台资源建设的三种主要模式,指出数据交换模式更适合于当前目标定位,即建设开放共享的科学数据共享平台;进一步提出了科学数据联盟模式,由此构建的科学数据共享平台可灵活地解决数据资源建设和整合问题,从而提高数据的利用率,提升服务质量;并提出了当前构建科学数据联盟模式的科学数据共享平台的两点建议;最后以地球系统科学数据共享网的建设为例进行了实例说明。本研究将为我国科学数据共享平台建设提供参考。 相似文献
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科学数据的共享管理—创建共享新秩序 总被引:10,自引:0,他引:10
鉴于科学数据共享已经成为我们的共识,那么如何顺利实现科学数据的共享管理,如何创建共享新秩序,实现科学数据的最大价值,就需要我们认真思考,并提出解决办法。 综观科学数据管理的历史,经历了漫长的手抄和印刷时代,在此期间,所产生科学数据的量相对不大,人们对科学数据的管理主要是进行立卷和归档 相似文献
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实现科学数据共享的基石语言——XML的理论与应用 总被引:5,自引:0,他引:5
本文介绍了逐渐成为新世纪网络“国际语言”的XML;阐述了其在标记语言设计、数据交换与整合、内容管理、Web服务、语义网等应用领域中的核心地位;分析了其在学科标记语言设计、元数据技术系统、通用科学数据描述与发布、互操作能力、元数据目录服务、精确数据服务与个性化功能服务、数据网格等科学数据共享管理诸方面的基石作用,指出了XML对于科学数据共享技术平台构架建设的重要意义;最后展望了基于XML的科学数据共享实施策略。 相似文献
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从科研主体间际关系的视角阐释科学数据共享价值的内涵,依据主体尺度和主体关系质态论述科学数据共享价值的属性,剖析科学数据共享价值表征。由于科学数据共享本身无法直接满足主体目的,需要主体通过数据共享关系建构和挖掘数据资源才能实现相应的目的,主要体现的是手段性价值,本文从主体身份认同寻求、信任关系建立、共享管理自为秩序生成、学术资本积累、嵌入行为建构等方面来阐释科学数据共享价值的多维表征。 相似文献
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科学数据共享标准体系框架 总被引:12,自引:0,他引:12
一、科学数据共享的内涵 科学数据共享,旨在通过应用现代信息技术手段,从国家宏观层次上营造一种科学数据共享氛围,使政府部门、科技教育工作者和社会公众可以广泛、有效、便捷地获取所需要的科学数据,对科学数据进行有序管理,实现科学数据拥有者为政府部门和广 相似文献
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W. J. Krzanowski 《Journal of Classification》1994,11(2):195-207
A low-dimensional representation of multivariate data is often sought when the individuals belong to a set ofa-priori groups and the objective is to highlight between-group variation relative to that within groups. If all the data are continuous then this objective can be achieved by means of canonical variate analysis, but no corresponding technique exists when the data are categorical or mixed continuous and categorical. On the other hand, if there is noa-priori grouping of the individuals, then ordination of any form of data can be achieved by use of metric scaling (principal coordinate analysis). In this paper we consider a simple extension of the latter approach to incorporate grouped data, and discuss to what extent this method can be viewed as a generalization of canonical variate analysis. Some illustrative examples are also provided. 相似文献
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科学数据的作用日益得到学术界的重视,其开放与共享是推动科技创新的重要举措,我国在科学数据共享领域已经有了近10年的实践经验,构建了一批领域科学数据共享平台。然而,对这些平台数据资源的组织、规模、类型、开放程度等客观情况的分析比较少。鉴于掌握数据资源的现状有着十分重要的意义,本文以国家人口与健康科学数据共享平台这一医药卫生领域的国家级平台为研究对象,从其网站上获取公开的已共享数据资源信息,以第三方的视角对平台数据资源现状进行深度挖掘和分析研究。对整体把握我国特定领域的科学数据资源情况提供思路,指导平台的进一步建设和发展。 相似文献
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公益性科技名词数据是一种重要的科技数据资源,也是一种重要的公共资源,应当被全社会平等共享。通过分析公益性科技名词数据的性质和特点,探讨公益性科技名词数据共享的原则和方法,希望以此建立科技名词数据共享的体制机制,促进科技创新发展。 相似文献
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Spectral analysis of phylogenetic data 总被引:12,自引:0,他引:12
The spectral analysis of sequence and distance data is a new approach to phylogenetic analysis. For two-state character sequences,
the character values at a given site split the set of taxa into two subsets, a bipartition of the taxa set. The vector which
counts the relative numbers of each of these bipartitions over all sites is called a sequence spectrum. Applying a transformation
called a Hadamard conjugation, the sequence spectrum is transformed to the conjugate spectrum. This conjugation corrects for
unobserved changes in the data, independently from the choice of phylogenetic tree. For any given phylogenetic tree with edge
weights (probabilities of state change), we define a corresponding tree spectrum. The selection of a weighted phylogenetic
tree from the given sequence data is made by matching the conjugate spectrum with a tree spectrum. We develop an optimality
selection procedure using a least squares best fit, to find the phylogenetic tree whose tree spectrum most closely matches
the conjugate spectrum. An inferred sequence spectrum can be derived from the selected tree spectrum using the inverse Hadamard
conjugation to allow a comparison with the original sequence spectrum.
A possible adaptation for the analysis of four-state character sequences with unequal frequencies is considered. A corresponding
spectral analysis for distance data is also introduced. These analyses are illustrated with biological examples for both distance
and sequence data. Spectral analysis using the Fast Hadamard transform allows optimal trees to be found for at least 20 taxa
and perhaps for up to 30 taxa.
The development presented here is self contained, although some mathematical proofs available elsewhere have been omitted.
The analysis of sequence data is based on methods reported earlier, but the terminology and the application to distance data
are new. 相似文献
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The mixture method of clustering applied to three-way data 总被引:3,自引:3,他引:0
Clustering or classifying individuals into groups such that there is relative homogeneity within the groups and heterogeneity between the groups is a problem which has been considered for many years. Most available clustering techniques are applicable only to a two-way data set, where one of the modes is to be partitioned into groups on the basis of the other mode. Suppose, however, that the data set is three-way. Then what is needed is a multivariate technique which will cluster one of the modes on the basis of both of the other modes simultaneously. It is shown that by appropriate specification of the underlying model, the mixture maximum likelihood approach to clustering can be applied in the context of a three-way table. It is illustrated using a soybean data set which consists of multiattribute measurements on a number of genotypes each grown in several environments. Although the problem is set in the framework of clustering genotypes, the technique is applicable to other types of three-way data sets. 相似文献
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W.J. Krzanowski 《Journal of Classification》1998,15(1):81-92
A new set of derived variables is proposed for exhibiting grouped multivariate data in a small number of dimensions, in such
a way as to highlight `extremeness' of one or more groups relative to the rest of the data. Such display can provide a useful
exploratory tool in multivariate ranking and selection problems.
We explore four possible measures of `extremeness', and suggest which one is best for practical application. We show that
the technique can be used to derive either orthogonal or uncorrelated dimensions for any type of input data, and we give an
illustrative example of its use. 相似文献
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A mathematical programming approach to fitting general graphs 总被引:1,自引:1,他引:0
We present an algorithm for fitting general graphs to proximity data. The algorithm utilizes a mathematical programming procedure based on a penalty function approach to impose additivity constraints upon parameters. For a user-specified number of links, the algorithm seeks to provide the connected network that gives the least-squares approximation to the proximity data with the specified number of links, allowing for linear transformations of the data. The network distance is the minimum-path-length metric for connected graphs. As a limiting case, the algorithm provides a tree where each node corresponds to an object, if the number of links is set equal to the number of objects minus one. A Monte Carlo investigation indicates that the resulting networks tend to fall within one percentage point of the least-squares solution in terms of the variance accounted for, but do not always attain this global optimum. The network model is discussed in relation to ordinal network representations (Klauer 1989) and NETSCAL (Hutchinson 1989), and applied to several well-known data sets. 相似文献
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The Kohonen self-organizing map method: An assessment 总被引:1,自引:0,他引:1
The “self-organizing map” method, due to Kohonen, is a well-known neural network method. It is closely related to cluster
analysis (partitioning) and other methods of data analysis. In this article, we explore some of these close relationships.
A number of properties of the technique are discussed. Comparisons with various methods of data analysis (principal components
analysis, k-means clustering, and others) are presented.
This work has been partially supported for M. Hernández-Pajares by the DGCICIT of Spain under grant No. PB90-0478 and by a
CESCA-1993 computer-time grant. Fionn Murtagh is affiliated to the Astrophysics Division, Space Science Department, European
Space Agency. 相似文献