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1.
成都日降水量年极大值的渐近分布   总被引:2,自引:0,他引:2  
利用1951-1999年成都日降水量年极大值的记录,通过统计推断,找出了成都日降水量年极大值遵循的渐近分布。讨论了两种分布-皮迩逊Ⅲ型分布、对数正态分布,并比较了它们的拟合效果,最后得出成都日降水量年极大值较好地遵循对数正态分布,并讨论了它们的参数估计方法。  相似文献   

2.
降水量的发生概率是天气预报及旱涝灾害等灾害风险评估的重要组成部分,希望通过对宜宾市季度降水量分布函数的研究,为当地的防灾减灾及农业生产提供一定的科学依据.利用四川省宜宾市1960~2010年51年的降水量数据资料,分别应用正态分布、对数正态分布、伽马分布和皮尔逊-Ⅲ分布函数对该地区的降水分布特征进行研究.在此基础上,利用最小离差平方和准则进行4种分布函数的拟合优度检验.结果表明:4种分布函数均能拟合宜宾季度降水量分布;伽马分布、正态分布、对数正态分布及P-Ⅲ分布分别为宜宾市春、夏、秋、冬各季降水量的最优拟合分布函数.  相似文献   

3.
降水量的发生概率是天气预报及旱涝灾害等灾害风险评估的重要组成部分,希望通过对宜宾市季度降水量分布函数的研究,为当地的防灾减灾及农业生产提供一定的科学依据.利用四川省宜宾市1960~2010年51年的降水量数据资料,分别应用正态分布、对数正态分布、伽马分布和皮尔逊-Ⅲ分布函数对该地区的降水分布特征进行研究.在此基础上,利用最小离差平方和准则进行4种分布函数的拟合优度检验.结果表明:4种分布函数均能拟合宜宾季度降水量分布;伽马分布、正态分布、对数正态分布及P-Ⅲ分布分别为宜宾市春、夏、秋、冬各季降水量的最优拟合分布函数.  相似文献   

4.
利用重庆1951—1996年间地面气温年极大值的记录,分别用韦伯分布、耿贝尔分布、皮尔逊Ⅲ型分布和对数正态分布进行拟合试验,通过统计推断比较,得出重庆地面气温年极大值遵循的渐进分布为韦伯分布和耿贝尔分布。  相似文献   

5.
区域化探中多数元素含量的概率分布服从或接近对数正态分布。在对数正态分布情况下,将标准离差与平均值的对数比值作为变异系数是不科学的。文章提出了类似参数新的计算方法和解释思路。  相似文献   

6.
分析了现行求更新函数解析所存在的不足之处,探讨采用蒙特卡洛模拟法求机器在常用寿命分布情况下的更新函数,并以对数正态分布为例介绍其应用过程。  相似文献   

7.
分析了现行求更新函数解析法所存在的不足之处,探讨采用蒙特卡洛模拟法求机器在常用寿命分布情况下的更新函数,并以对数正态分布为例介绍其应用过程。  相似文献   

8.
元素的地球化学含量异常下限值的确定方法众多,传统的统计学方法是以样品数据呈正态分布或者对数正态分布为假设前提,通过统计学参数对异常进行筛选和评价。已有研究表明,地球化学景观可能是具有低维吸引子的混沌系统,元素的地球化学背景值和异常具有各自独立的幂指数关系,是一种多重分形分布。依据元素的分形分布规律,可运用分形方法来计算元素的异常下限。本文以湖南龙山县地区Hg元素化探数据为基础,使用含量—面积分形方法确定了Hg元素异常下限值,并与传统计算方法所得的结果作了对比,证明了分形方法在计算非正态分布元素的异常下限值方面存在优势,不受元素极值数据的影响,并能有效减少人为干预,在实践工作中具有可行性。  相似文献   

9.
基于GIS确定地球化学异常下限的新方法   总被引:5,自引:0,他引:5  
运用地理信息系统(GIS)空间分析原理,研究了地球化学元素含量与分布面积之间的关系及在异常下限划分中的应用,并以凤凰山矿田为实例,与分形理论做了对比研究,发现利用分形理论对原始数据进行处理得到的异常下限为1000×10-6,利用样品平均值取代特高品位后的分形异常下限为240×10-6,而利用新方法直接对原始数据进行分析的结果为250×10-6。研究表明,新方法并不要求数据服从正态分布或对数正态分布,能从原始数据中直接识别致矿异常,是确定地球化学异常下限的简便方法。  相似文献   

10.
中国大陆若干地震构造带的地震准周期丛集复发行为   总被引:8,自引:3,他引:5  
以青藏高原东南缘和东北缘若干地震构造带的历史地震活动资料为基本数据,通过地震复发间隔的计算,分类和统计检验等,研究了大陆板内地震的复发行为。认为:大陆板内地震既不是简单地准周期重复发生,也不是简单地丛集复发,而可能是一种准周期的丛集复发行为,即地震丛是准周期重复发生的,而在某一地震丛内,地震又是丛集复发的。存在两类地震复发间隔,即地震丛复发间隔和地震丛内的地震复发间隔,它们分别满足对数正态分布和指数分布。在进行大陆板内活动断裂地震危险性定量计算和评估时,不能简单地套用N.B.实进模型中给出的地震复发间隔概率密度函数或累积分布函数,而应该根据当前地震的活动水平,判断当前是属于丛内的活跃期还是丛间的平静期,据此分别选用地震丛内地震复发间隔分布函数或者地震丛复发问题隔分布函数,这样将大大提高活动断裂地震危险性计算和定量评估的水平。最后,简要探讨了大陆板内地震准周期丛集复发行为的可能物理机制。  相似文献   

11.
强降水的GP分布拟合   总被引:1,自引:0,他引:1  
根据极值理论中处于重要地位的GP分布模型,讨论了模型中的形状参数、位置参数及尺度参数的算法,并将其用于拟合呈偏斜状态的月和日降水量资料中强降水部分,得到强降水发生的直观年数。  相似文献   

12.
Fine root is critical to restrain soil erosion and its distribution pattern is of great influence on the restraining effects. This study studied the fine root biomass(Br) distribution of different aged Leucaena leucocephala(5, 10, 15 years) in debris flow source area in Jiangjia Gully by digging downward to the bottom at different distances to stem in three directions on slope. The results showed the Br increased dramatically by 143% from 5 years to 10 years and then rose slowly by 38% from 10 years to 15 years. The Br of 5 years was significantly asymmetric between uphill and alonghill directions, but there was little difference among directions for other ages, and a concentration trend appeared to exist in downhill and alonghill directions. Moreover, fine root(D≤1 mm) was significantly heavier than that of fine root(1mmD≤2 mm), playing a leading role in the vertical distribution of the whole fine root, with a logarithmic or an exponential function. The results presented may shed light on fine root distribution pattern and evaluation of its effect on slope stability in debris flow source area.  相似文献   

13.
Seasonal distribution of bioaerosols in the coastal region of Qingdao   总被引:1,自引:0,他引:1  
Bioaerosols were collected by using a six-stage bioaerosols sampler from September 2007 to August 2008 in the coastal region of Qingdao, China. The terrestrial and marine microbes(including bacteria and fungi) were analyzed in order to understand the distribution features of bioaerosols. The results show that the average monthly concentrations of terrestrial bacteria, marine bacteria, terrestrial fungi and marine fungi are in the ranges of 80–615 CFU m-3, 91–468 CFU m-3, 76–647 CFU m-3 and 231–1959 CFU m-3, respectively. The concentrations of terrestrial bacteria, marine bacteria, terrestrial fungi, marine fungi and total microbes are the highest in each microbial category during fall, high in spring, and the lowest in the summer and winter. The bacterial particles are coarse in spring, autumn and winter. The sizes of fungal particle present the log-normal distribution in all the seasons.  相似文献   

14.
Grain composition plays a vital role in impact pressure of debris flow. Current approaches treat debris flow as uniform fluid and almost ignore its granular effects. A series of flume experiments have been carried out to explore the granular influence on the impact process of debris flow by using a contact surface pressure gauge sensor(Tactilus~?, produced by Sensor Products LLC). It is found that the maximum impact pressure for debris flow of low density fluctuates drastically with a long duration time while the fluctuation for flow of high density is short in time, respectively presenting logarithmic and linear form in longitudinal attenuation. This can be ascribed to the turbulence effect in the former and grain collisions and grainfluid interaction in the latter. The horizontal distribution of the impact pressure can be considered as the equivalent distribution. For engineering purposes, the longitudinal distribution of the pressure can be generalized to a triangular distribution, from which a new impact method considering granular effects is proposed.  相似文献   

15.
By reasearch on geographic distribution, nine genera in bipolar distribution are selected from Permian brachiopods. These taxa originated from middle-high latitude areas in the boreal realm, of which five genera were derived from Late Carboniferous, and other four genera originated from Permian. They were all in bipolar distribution during some different stages in Permian. Specific diversity for each genus was high in the boreal realm, whereas in the Gondwana realm was very low. Perdurability was long in the boreal realm, and short in the Gondwana realm. It was the time when these nine genera came to their maximum diversity that these genera appeared in the Gondwana and formed bipolar distribution; while they also migrated to the low latitude from high latitude. This shows very close relationship between several main cooling events in Permian and the migration of genera from the boreal realm to the Gondwana reahn through the Tethys. Therefore, the cooling events might be the main drive which caused these cold-water-type brachiopods migrated to the Gondwana realm and being bipolar distribution. In this process, the planula tolerance to warm water would be another important factor.  相似文献   

16.
Mechanism on bipolar distribution of Permian brachiopods   总被引:1,自引:1,他引:0  
By reasearch on geographic distribution, nine genera in bipolar distribution are selected from Permian brachiopods. These taxa originated from middle-high latitude areas in the boreal realm, of which five genera were derived from Late Carboniferous, and other four genera originated from Permian. They were all in bipolar distribution during some different stages in Permian. Specific diversity for each genus was high in the boreal realm, whereas in the Gondwana realm was very low. Perdurability was long in the boreal realm, and short in the Gondwana realm. It was the time when these nine genera came to their maximum diversity that these genera appeared in the Gondwana and formed bipolar distribution; while they also migrated to the low latitude from high latitude. This shows very close relationship between several main cooling events in Permian and the migration of genera from the boreal realm to the Gondwana realm through the Tethys. Therefore, the cooling events might be the main drive which caused these cold-water-type brachiopods migrated to the Gondwana realm and being bipolar distribution. In this process, the planula tolerance to warm water would be another important factor.  相似文献   

17.
Modern industry in northeast China started from light industry. From the end of 19th century to 1931 was the phase of initial development of light industry in northeast China. During this period, the development of light industry gave priority to grain processing industry. After occupying northeast China, Japanese vigorously developed heavy industry to meet the needs of munitions and paid more attention to raw materials and semi-finished articles industry for the purpose of the war. Light industry was impeded and developed slowly. After the founding of New China, large-scale economic construction took place in northeast and heavy industry received prior investment and equipment. Northeast region became the first heavy industry base through several five-year plans, the development of light industry made giant strides. The present features of light industry distribution are: difference of light industry distribution, similarity of light industry structure, and imbalance of light industry development. The  相似文献   

18.
THEEVOLUTIONOFSETTLEMENTLOCATIONANDDISTRIBUTIONINURBANRURALINTEGRATIONLiaoRonghua(廖荣华)ChenXiangman(陈湘满)DepartmentofGeography...  相似文献   

19.
The urban-rural integration is an inevitable outcome of regional economic development in a certain stage and is objectively exhibited as the evolution of settlement location and distribution, that is, the turning from spot-distribution to area-distribution of the settlement in developed areas, while in less developed areas, from spet-distribution to linear distribution. The evolution of the settlement location and distribution is an inevitable result of economic development in the urban-rural integration, which is restricted by factors affecting economic development, on the other hand, it is also an important factor affecting and restricting economic development. In the process of the urban-rural integration, modern transportation orientation, modern market orientation, modern industrial orientation and modern population orientation are important motive force, and influence the basic pattern of the settlement location and distribution, which plays a speeding or delaying role in regional economic development.  相似文献   

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