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排序方式: 共有169条查询结果,搜索用时 15 毫秒
1.
农业信息数据挖掘的粗糙集方法研究与实例 总被引:1,自引:0,他引:1
我国是个农业大国,农业数据量极大,手工处理工作量大且不准确.本文研究了将粗糙集理论运用于农业数据挖掘的计算机处理方法,提出了基于粗糙集理论的农业数据挖掘的基本算法和模型,并通过实例对其进行了验证. 相似文献
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Huang Wenzhen Huang Buyu Dong Xun 《保鲜与加工》1993,(1):72-77
Based upon the eigenvalue sensitivity theory of non-self-adjoit system and the component mode synthesis method,a new technique is developed to analyze the eigenvalue sensitivity to variation of parameters of large rotor-bearing system. As an application, the influence of the journal bearing parameters on the stability of a large domestic turbine-generator set is analyzed and discussed. 相似文献
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烟草成分对其品质影响程度的粗糙集判别方法 总被引:8,自引:0,他引:8
运用粗糙集理论研究了烟草主要化学成分 (总糖、还原糖、总氮、烟碱、氧化钾和氯离子 )对烟草品质影响程度的判别方法。对比已有的研究结果 ,表明基于粗糙集理论的计算方法简单 ,结果明了 ,而且还能量化烟草成分对品质的影响程度。 相似文献
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The effects of three set-sizes (12.5, 17.5 and 22.5 mm in diameter) and seven storage temperatures (0, 5, 10, 15, 20, 25 and 30 °C) on bolting, bulbing and seed yield in two onion (Allium cepa L.) cultivars ‘Hygro’ and ‘Delta’ were investigated. The incidence of bolting increased linearly with set-size and curvi-linearly with decreasing storage temperature. Time to inflorescence emergence and floret opening showed a curvi-linear response to storage temperature with the earliest inflorescence emergence and floret opening occurring at 5 °C and the latest at 30 °C for ‘Hygro’ and at 25 °C for ‘Delta’. Seed yield per umbel also showed a curvi-linear response to storage temperature with the lowest seed yield occurring at 30 °C for ‘Hygro’ and at 25 °C for ‘Delta’ and the highest seed yield at 5 °C. For a seed crop, storage of large sets (22.5 mm) of these cultivars at 5 °C for 120 days appeared to be optimum with 5–12% higher seed yield per umbel than that of 90 days storage. Bulb yield showed a curvi-linear response to storage temperature with the highest bulb yield occurring at 25 °C and the lowest at 5 °C. 相似文献
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基于粗集权重的改进可拓评价方法在灌区干旱评价中的应用 总被引:9,自引:2,他引:9
在分析了灌区干旱评价特点和目前评价方法不足的基础上,引入了基于非对称贴近度和粗集理论的改进可拓评价方法,有效避免了灌区干旱评价指标界限的纲性量化导致的遗漏问题和单项指标评价结果的矛盾性、不确定性和不相容性。与传统可拓评价方法相比,在指标权重的确定中采用经验因子协调主客观权重,克服了以往决策者过分依赖专家经验知识确定的不足。在等级评价中采用非对称贴近度原则,代替最大隶属度,有效解决最大隶属度原则的失效问题。计算实例表明,采用基于粗集权重的改进可拓评价方法进行灌区干旱评价是切实可行的。 相似文献
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知识约简的多族蚁群算法 总被引:1,自引:0,他引:1
Rough集理论中知识约简是个NP-hard问题,已有的方法都有不同的局限性。受蚁群算法的启发,通过将条件属性集映射到有向图结构,并采用两族群蚂蚁协作共同完成求解,提出了知识约简的多族蚁群算法。采用多族群蚂蚁协作后,改善了一般蚁群算法收敛速度较慢的问题,提高了求解速度。通过实验验证,它是一种非常有效的方法。 相似文献
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对28个西瓜品种进行抗枯萎病筛选.苗期用特定浓度接种,每隔7d调查其感病情况及植株生长情况.株高、茎粗、叶片数等生长势指标与发病率均呈极显著负相关,相关系数分别为-0.5480、-0.6052、-0.8114.利用聚类分析方法统计,把28个西瓜品种按其抗性表现归类,从而得出抗病水平不同的各组西瓜品种,并筛选出一组抗性水平相当高的品种.为选育高抗西瓜品种以及研究各西瓜品种的抗病性关系提供了一种简捷的科学方法. 相似文献
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Fusarium oxysporum,F. proliferatum and F. redolens associated with basal rot of onion in Finland 下载免费PDF全文
M. Haapalainen S. Latvala E. Kuivainen Y. Qiu M. Segerstedt A. O. Hannukkala 《Plant pathology》2016,65(8):1310-1320
In recent years in Finland, Fusarium infections in onions have increased, both in the field and in storage, and Fusarium species have taken the place of Botrytis as the worst pathogens causing post‐harvest rot of onion. To study Fusarium occurrence, samples were taken from onion sets, harvested onions and also from other plants grown in the onion fields. Isolates of five Fusarium species found in the survey were tested for pathogenicity on onion. Fusarium oxysporum was frequently found in onions and other plants, and, of the isolates tested, 31% caused disease symptoms and 15% caused growth stunting in onion seedlings. Fusarium proliferatum, a species previously not reported in Finland, was also identified. Over 50% of the diseased onion crop samples were infected with F. proliferatum, and all the F. proliferatum isolates tested were pathogenic to onion. Thus, compared to F. oxysporum, F. proliferatum seems to be more aggressive on onion. Also some of the F. redolens isolates were highly virulent, killing onion seedlings. Comparison of the translation elongation factor 1α gene sequences revealed that the majority of the aggressive isolates of F. oxysporum f. sp. cepae group together and are distinct from the other isolates. Incidence and relative proportions of the different Fusarium species differed between the sets and the mature bulbs. More research is required to determine to what extent Fusarium infections spoiling onions originate from infected onion sets rather than the field soil. 相似文献