两系杂交稻制种基地气候风险评估的研究   总被引：6，自引：1，他引：6       下载免费PDF全文

殷剑敏  魏丽等 《应用气象学报》2001,12(4):469-477

通过对两系杂交稻制种气候风险的数学定义, 根据江西省1:25万地形数据和84个气象台站40年气候资料, 在分析气候要素与海拔高度关系的基础上, 运用地理信息系统的空间分析方法, 对两系杂交稻制种气候风险进行评估, 找出了最佳制种地理区域和季节。对农业生产具有重要的意义, 分析结果在生产实际中得到证实。  相似文献   

江西省两系杂交稻制种基地气候风险区划的研究     

殷敛敏  魏丽等 《南京气象学院学报》2001,24(3):415-422

通过对两系稻制种气候风险的数学定义，根据江西省1：25万地形数据和各气象台站40a气候资料及气候要素与海拔高度的关系，运用地理信息系统的空间分析方法，对两系稻制种基地的气候风险进行了区划，找出了最佳制种地理区域和不同品种最小气候风险下的最佳播种期。  相似文献   

钢管-钢管混凝土复合拱桥动力特性分析   总被引：13，自引：0，他引：13  

孙潮  陈宝春  陈水盛 《地震工程与工程振动》2001,21(2):48-52

福建省福鼎市山前大桥是一座应用钢管－钢管混凝土复合拱桥概念设计成的试验桥，本文以它作为研究对象，进行了动力特性的测试和计算，并讨论了主要结构参数对其动力特性的影响，为此类桥梁的设计提供参考。  相似文献   

PSV-wave propagation in a medium with local heterogeneities: a hybrid formulation and its application   总被引：1，自引：0，他引：1  

Helga Emmerich 《Geophysical Journal International》1992,109(1):54-64

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Petrological Significance of Zoned Plagioclase in Eldjurti Granite and Mafic Microgranular Enclaves,North Caucasus,Russia   总被引：5，自引：0，他引：5  

朱永峰 《中国地球化学学报》1994,13(2):142-155

Plagioclase phenocrysts from mafic enclaves and plagioclase from its host granite possess a pat-tern of complex zonation .A plagioclase phenocryst can generally be divided into three parts:an oscillatory, locally patchy zoned core (An47-19),a ring with dusty, more calcic plagioclase (An64-20) and a normally zoned rim composed of sodic plagioclase (An22-3.3). Major discontinuities in zoning coincide with resorption surfaces that are overgrown by the more calcic plagioclase.The cores of large plagioclase phenocrysts from mafic enclaves and host granite show similar zoning patterns and similar compositions, indicating their crystallization under the same conditions .Steep normal zoning of the rims of plagioclases both from host granite and mafic enclaves illustrates a drastic decrease in An content which is considered to have resulted from the continuous differentiation of hybrid magma and efficient heat loss because of the upward emplacement of the residual magma.Wide rims of plagioclases from the host granite against the discrete rims of plagioclases from mafic enclaves indicate that differentiation and cooling lasted much longer in the host granite than in the mafic enclaves.  相似文献   

烟台、威海南部近岸海域物理自净能力研究——Ⅰ.潮流模型     

郑连远  田晖  郭耀同 《中国海洋大学学报(自然科学版)》1994,(Z1)

采用不规则三角形网格,利用变边界分步杂交法汁算烟台、威海南部近岸海域的潮流分布,指出此海城属于正规半日潮海域,潮波由北向南传播。  相似文献   

Developing a hybrid multi‐model for peak flood forecasting     

Yupa Chidthong  Hitoshi Tanaka  Seree Supharatid 《水文研究》2009,23(12):1725-1738

The present study aims to develop a hybrid multi‐model using the soft computing approach. The model is a combination of a fuzzy logic, artificial neural network (ANN) and genetic algorithm (GA). While neural networks are low‐level computational structures that perform well dealing with raw data, fuzzy logic deal with reasoning on a higher level by using linguistic information acquired from domain experts. However, fuzzy systems lack the ability to learn and cannot adjust themselves to a new environment. Moreover, experts occasionally make mistakes and thus some rules used in a system may be false. A network type structure of the present hybrid model is a multi‐layer feed‐forward network, the main part is a fuzzy system based on the first‐order Sugeno fuzzy model with a fuzzification and a defuzzification processes. The consequent parameters are determined by least square method. The back‐propagation is applied to adjust weights of network. Then, the antecedent parameters of the membership function are updated accordingly by the gradient descent method. The GA was applied to select the fuzzy rule. The hybrid multi‐model was used to forecast the flood level at Chiang Mai (under the big flood 2005) and the Koriyama flood (2003) in Japan. The forecasting results are evaluated using standard global goodness of fit statistic, efficient index (EI), the root mean square error (RMSE) and the peak flood error. Moreover, the results are compared to the results of a neuro‐genetic model (NGO) and ANFIS model using the same input and output variables. It was found that the hybrid multi‐model can be used successfully with an efficiency index (EI) more than 0·95 (for Chiang Mai flood up to 12 h ahead forecasting) and more than 0·90 (for Koriyama flood up to 8 h ahead forecasting). In general, all of three models can predict the water level with satisfactory results. However, the hybrid model gave the best flood peak estimation among the three models. Therefore, the use of fuzzy rule base, which is selected by GA in the hybrid multi‐model helps to improve the accuracy of flood peak. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

改进的遗传算法及其在渗流参数反演中的应用   总被引：11，自引：5，他引：6  

刘杰  王媛 《岩土力学》2003,24(2):237-241

利用水头实测资料,以裂隙组的渗透系数比例因子为待反演的参数向量,在采用基本遗传算法进行参数反演研究的基础上,针对裂隙岩体无压渗流参数反问题计算量过大,目标参数众多以及参数可能变化范围大等特点,提出了一种混合遗传算法求解此类问题,力求克服简单遗传算法在解决此类问题时存在的局部搜索能力弱、易出现早熟收敛及计算量大等缺陷,并通过典型岩坡渗流算例进行验证,同时给出了基本遗传算法、传统单纯形算法的反演成果。计算结果表明,该方法保持了基本遗传算法优点,并有效地提高了算法的运行效率,从而为求解裂隙岩体无压渗流参数反问题等计算量大的系列问题提供了新的途径。  相似文献   

GPS网平差的多元响应-非线性最小二乘模型及其解的最优化混合算法   总被引：1，自引：1，他引：0  

李述山  陶华学 《测绘科学》2004,29(1):20-21

在控制网中,用GPS测量,可以同时测得一个点的基线向量,在具有起算数据时可获得观测点的三维坐标等多个响应变量值,将这些响应变量包含的信息综合起来,可以得到参数的更精确的估计。本文针对GPS测量数据为多元响应数据的特点,建立了一个GPS网平差的多元响应-非线性最小二乘模型,针对该模型,结合拟牛顿法和信赖域算法建立了一个新非线性优化的混合算法,该算法具有全局收敛性和超线性收敛性。  相似文献   

一种新型混合控制技术的振动台模型试验研究   总被引：1，自引：1，他引：0  

孟庆利  张敏政  陈栋 《地震工程与工程振动》2004,24(2):145-149

本文提出了基底隔震和上部结构变刚度／阻尼半主动控制结合的一种新型混合控制型式,并且通过小型电磁振动台模型试验来研究其控制效能,为其今后更进一步理论和实验研究奠定基础。  相似文献