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51.
This paper introduces phenomenon of electric erosion of gear and the research condition and evolution of it; puts forward a point of view that a system of electric erosion of gear is a especial tribology system which is in relation to many subjects and in which many phenomena exist and coupling each other , moreover , it is very difficult and complex to study electric erosion of gear by experiment ; have made statistical datas about typical example of electric erosion of gear inland ,at this base ,summarizes characters of electric erosion of gear and the study means of it. 相似文献
52.
文章针对传统评价方法不能很好地解决评价因子与水质等级间复杂的非线性关系,以及主观确定权重等问题,提出基于投影寻踪的改进集对分析模型(RAGAPP-SPA)。利用最佳投影方向作为指标权重,并通过完善Ⅴ级相邻级别联系度为-1的不足,假设存在Ⅵ级的指标值,从而得出联系度,进而对涡北井田地下水质进行了等级评价。结果表明,13个地区评价结果基本与原方法相同,权重符合实际规律。基于投影寻踪的改进型集对分析,能够客观确定权重,改进后的集对分析模型等级划分更细致,对检测数据利用率高,可应用于各种非线性、非正态高维数据评价研究中。 相似文献
53.
P. Skelsey J. G. Elphinstone G. S. Saddler S. J. Wale I. K. Toth 《Plant pathology》2016,65(4):570-576
Potato blackleg, caused by Pectobacterium and Dickeya species, is one of the most significant bacterial diseases affecting potato production globally. Although it is generally accepted to be a seedborne disease, the processes underlying the spread of disease largely remain unknown. Spatial point pattern analysis was applied to blackleg occurrence in seed potato crops in Scotland during the period of 2010–2013 (approximately 8000 blackleg‐affected crops), to assess whether its distribution was random, regular or aggregated, and the spatial scales at which these patterns occurred. Blackleg‐affected crops derived from mother stocks with symptoms were omitted from the analyses in order to examine the statistical evidence for horizontal transmission of blackleg. The pair correlation function was used to test for global spatial autocorrelation, and results indicated significant (P < 0·05) clustering of incidence at a wide range of spatial scales. Strength of clustering (degree of aggregation) among blackleg‐affected crops was notably larger at spatial scales of 25 km or less. A hot‐ and coldspot analysis was performed to test for local spatial autocorrelation, and statistically significant clusters of high and low values of disease were found across the country. These analyses provide the first quantitative evidence of localized and large‐scale spatial clustering of potato blackleg. Understanding the mode(s) of inoculum dispersal will be important for developing new management strategies that minimize host–pathogen contacts in potato and numerous other crops affected by pathogenic Pectobacterium and Dickeya species. 相似文献
54.
基于压力-状态-响应模型与集对分析的土地利用系统健康评价 总被引:2,自引:3,他引:2
土地利用系统健康评价是改善土地利用系统健康状况,促进土地可持续利用的重要基础。针对土地利用系统健康的不确定性,构建了基于PSR模型的评价指标体系。在了解集对分析原理的基础上,利用原创联系度的可展性对其进行改进,建立了基于集对分析法和改进熵值法的土地利用系统健康评价模型,并对中国土地利用系统健康状况进行诊断。结果表明:(1) 1999-2008年中国土地利用系统健康水平不断提高,健康等级经历了"不健康-临界状态"的演变历程,但2008年"临界状态"水平不高;(2)固定资产投资年增长率、人均耕地面积、土地垦殖率、水土流失程度、地均GDP等是土地利用系统健康等级提升的关键制约因素。研究结果表明,基于PSR模型的评价指标体系能更准确地反映土地利用系统健康,各要素之间的关系。集对分析法通过注重信息处理过程中的相对性和模糊性能很好地解决不确定性问题,有效挖掘土地利用系统存在的具体问题,适合用于土地利用系统健康状况的评价。 相似文献
55.
For normal planar closed chain mechanism, it is based on ideal planar constraint condition. The authors took crank leader mechanism as an example, and analyzed influences resulted from uncertain factors, such as manufacturing error. The result shows it belongs to statically indetermination mechanism. After analyzing its over-constraint and eliminating it, in this way, it become statically determination mechanism and can be assembled without obstacle. However, in the process of practical running, the mechanism can give birth to new kinematic constraint, frictional constraint and dynamic constraint etc., so over constraint emerges again. Therefore, it is necessary to analyse its adaptability in total running process. The conclusion shows that design of adaptability mechanism normally eliminate geometry over constraint at first, then it is analyzed that whether there is new over constraints from all kind of external constraints in the process of running. 相似文献
56.
57.
Developing tolerant genotypes is crucial for stabilizing maize productivity under drought stress conditions as it is one of the most important abiotic stresses affecting crop yields. Twenty seven genotypes of maize (Zea mays L.) were evaluated for drought tolerance for three seasons under well watered and water stressed conditions to identify interactions amongst various tolerance traits and grain yield as well as their association with SSR markers. The study revealed considerable genetic diversity and significant variations for genotypes, environment and genotype × environment interactions for all the traits. The ranking of genotypes based on drought susceptibility index for morpho-physiological traits was similar to that based on grain yield and principal component analysis. Analysis of trait – trait and trait – yield associations indicated significant positive correlations amongst the water relations traits of relative water content (RWC), leaf water potential and osmotic potential as well as of RWC with grain yield under water stressed condition. Molecular analysis using 40 SSRs revealed 32 as polymorphic and 62 unique alleles were detected across 27 genotypes. Cluster analysis resulted in categorization of the genotypes into five distinct groups which was similar to that using principal component analysis. Based on overall performance across seasons tolerant and susceptible genotypes were identified for eventual utilization in breeding programs as well as for QTL identification. The marker-trait association analysis revealed significant associations between few SSR markers with water relations as well as yield contributing traits under water stressed conditions. These associations highlight the importance of functional mechanisms of intrinsic tolerance and cumulative traits for drought tolerance in maize. 相似文献
58.
本文首先对法门寺茶器具的两种系统联系的分类学思路进行了反驳,进而提出在文物分类中,不仅仅应该基于文物的特征、材质与功能,同时应当考虑到文物之中体现的社会关系。在法门寺地宫的《衣物帐》中,出现了三类社会关系,人与神之间的"供养"关系,君与臣之间的"恩赐"关系和皇亲与大臣对佛表示恭敬与支持的"施"关系,其中以君臣之间的"恩赐"关系为主,所以法门寺的茶器不是成套的,这与唐朝的佛政关系背景有关。 相似文献
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60.
基于六元联系数的水质综合评价模型 总被引:1,自引:1,他引:1
为了合理地评价河流水质.在集对分析原理的基础上,建立了基于熵权的六元联系数水质评价模型,该模型将联系分童系数作为标记,并根据水质指标与标准限值的联系程度对联系分量赋值.用该模型对小清河9个主要河段的10项水质指标进行分析.结果表明,六元联系数法理论严谨,计算简便,评价结果更能真实反映水质状况.是一种有效的水质综合评价方... 相似文献