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基于力学思想的空间聚类有效性评价

从力学的角度来考虑空间聚类问题,并结合地理学基本规律提出了一种基于力学思想的空间聚类有效性评价指标(简称SCV)。实验分析表明,本文提出的评价指标能够更准确、高效地对二维地理空间数据的硬聚类结果进行有效性评价。     

水库控制流域汛期分期的有效聚类分析

受诸多因素影响的水库汛期分期其实质是一个聚类数目未确知的高维时间序列聚类问题,它要求聚类方法具有能处理高维和时序性数据,且能同时回答聚为几类最为合理的能力。鉴于目前常规聚类方法不同时具备这些能力,在模糊C-均值聚类和紧密与分离聚类有效函数的基础上,提出了能够处理高维时序聚类问题的动态模糊C-均值聚类分析方法和相应的时序聚类有效性函数,耦合二者建立了适用于汛期分期的有效模糊聚类分析方法,提出采用实码加速遗传算法优化求解,克服了模糊C-均值聚类方法常规迭代优化求解对初值敏感的困难,并给出了完备的建模步骤和模型的合理性检验。最后,将模型应用于滦河流域潘家口水库汛期分期中,得出了合理的结论。     

冀东平原土壤重金属元素的存在形态及有效性分析

通过对冀东平原根系土中8种重金属元素形态含量的统计与分析,总结出其形态组成特征,初步分析了各重金属元素在土壤中的地球化学行为。笔者运用相关性分析方法,对重金属元素有效态含量与全量及土壤pH、TOC的相关性进行分析,从而得出重金属元素有效态含量的高低不仅受其全量的影响,而且与土壤pH、TOC亦有密切关系,这为表层土壤重金属元素污染程度的科学合理评价提供了理论依据。     

The need for operational reasoning in data‐driven rating curve prediction of suspended sediment

The use of data‐driven modelling techniques to deliver improved suspended sediment rating curves has received considerable interest in recent years. Studies indicate an increased level of performance over traditional approaches when such techniques are adopted. However, closer scrutiny reveals that, unlike their traditional counterparts, data‐driven solutions commonly include lagged sediment data as model inputs, and this seriously limits their operational application. In this paper, we argue the need for a greater degree of operational reasoning underpinning data‐driven rating curve solutions and demonstrate how incorrect conclusions about the performance of a data‐driven modelling technique can be reached when the model solution is based upon operationally invalid input combinations. We exemplify the problem through the re‐analysis and augmentation of a recent and typical published study, which uses gene expression programming to model the rating curve. We compare and contrast the previously published solutions, whose inputs negate their operational application, with a range of newly developed and directly comparable traditional and data‐driven solutions, which do have operational value. Results clearly demonstrate that the performance benefits of the published gene expression programming solutions are dependent on the inclusion of operationally limiting, lagged data inputs. Indeed, when operationally inapplicable input combinations are discounted from the models and the analysis is repeated, gene expression programming fails to perform as well as many simpler, more standard multiple linear regression, piecewise linear regression and neural network counterparts. The potential for overstatement of the benefits of the data‐driven paradigm in rating curve studies is thus highlighted. Copyright © 2011 John Wiley & Sons, Ltd.     

矿物热力学数据的获取

简介矿物热力学数据获取方法发展现状,重点评述量热法和相平衡法的近期发展状况。     

大学英语等级考试的信度与效度测试:英语四、六级与有效交际能力

关于大学英语四、六级,及其英语口语考试,是否具有科学的信度与效度这一问题的论证,引起了诸多争议。运用Carl Popper的反证法,在怀疑并否定其具有科学信度与效度方面,也不乏许多挑战权威的例子。尽管现今反证的理论与例证并不十分系统,但它终将会以科学的信度与效度为目标而日臻完善。     

空间数据模糊聚类的有效性(英文)

The validity measurement of fuzzy clustering is a key problem. If clustering is formed, it needs a kind of machine to verify its validity. To make mining more accountable, comprehensible and with a usable spatial pattern, it is necessary to first detect whether the data set has a clustered structure or not before clustering. This paper discusses a detection method for clustered patterns and a fuzzy clustering algorithm, and studies the validity function of the result produced by fuzzy clustering based on two aspects, which reflect the uncertainty of classification during fuzzy partition and spatial location features of spatial data, and proposes a new validity function of fuzzy clustering for spatial data. The experimental result indicates that the new validity function can accurately measure the validity of the results of fuzzy clustering. Especially, for the result of fuzzy clustering of spatial data, it is robust and its classification result is better when compared to other indices.     

自然灾害风险初议

自然灾害风险的研究与评价是制定减灾对策、土地利用规划、社会发展与经济建设规划及保险展业的基础工作。自然灾害风险是灾害科学的前沿性研究课题。本文对自然灾害风险的特点、分类、形成原因、构成要素、结构层次、分析方法和研究风险的基本步骤进行了初步的讨论,以期在推动我国自然灾害风险研究中起到抛砖引玉的作用。     

南海长棘海星物种有效性探讨

南海长棘海星暴发已严重威胁到该海域珊瑚礁生态系统健康,乃至整个南海生物多样性。针对南海长棘海星拉丁学名混用、中文名不统一的现状,我们采集了中沙群岛济猛暗沙海域长棘海星样品,结合长棘海星此前物种分类和分布的研究结果,对南海长棘海星物种有效性进行探讨。结果表明：所有长棘海星序列明显分为4个类群,各类群间遗传距离范围为0.087 5~0.104 7,达到了种间差异水平。南海长棘海星与长棘海星的太平洋种聚类到一起,实为太阳长棘海星(Acanthaster solaris),与其余3个种存在明显的种间差异。太阳长棘海星中2个支系间的遗传距离为0.005 3,在COⅠ基因层面属于种内差异。南海长棘海星物种有效性的研究结果为后续开展其遗传特征与适应性机制、种群分布与扩散机制、种群暴发机制等内容的研究提供科学依据。