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1.
采用1961—2016年春季(3—5月)内蒙古逐月降水资料,应用统计相关分析、REOF,对比分析等方法分析研究了内蒙古地区春季降水类型的气候特征以及海洋和大气环流特征。可以发现,内蒙古春季降水具有明显的地域性特征,分为4个类型:全区偏少型,全区偏多型,中西部偏多、东部偏少型,东部偏多、中西部偏少型。研究结果说明,春季降水的大气环流形势受ENSO事件影响。AO的正、负位相对内蒙古不同地区造成不同影响,正位相时有利于中西部降水偏多,负位相时有利于东部偏多。西伯利亚高压偏强,东亚大槽偏弱、偏西,冬季青藏高原积雪偏多,西太平洋副热带高压偏强、偏西,降水落区处在低压槽后,冷空气较为活跃,配合暖湿水汽输送条件,冷暖气流在内蒙古地区交汇便形成多雨区;反之亦然。研究结果对预报员预测思路具有预测指导意义。  相似文献   
2.
This study compares how humans and neural networks classify climate types. Human subjects were asked to classify climates from monthly temperature and precipitation patterns. To model their learning process, the same data were used to produce input vectors that trained a pattern associator neural network. Both human subjects and the neural network classified climates accurately after 10 rounds of supervised learning. The neural network successfully modeled the rate of human learning and the ability to learn specific climate categories. Moreover, the neural network weights used to classify climates correspond to distinct visual characteristics in temperature and precipitation. These results suggest that neural networks can model the formation of visual categories.  相似文献   
3.
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【Addresses】1

The tree root distribution pattern and biomass of seventeen year old trees of Grewia optiva, Morus alba, Celtis australis, Bauhinia variegata and Robinia pseudoacacia were studied by excavation method. B. variegata roots penetrated to a maximum depth of 4.78 m, whereas, M. alba roots were found down to 1.48 m depth. Lateral spread was minimum in B. variegata (1.10 m)and maximum inR. pseudoacacia (7.33 m). Maximum root biomass of 6.30 kg was found in R. pseudoacacia and minimum (2.43 kg) was found in M. alba. For four species viz.,G. optiva, M. alba, C. australis andR. pseudoacacia, 68%-87% root biomass occurred within top 0-30 cm soil depth, but forB. variegata this was only45%. The soil binding factor was maximum in G. optiva and minimum in B. variegata. Soil physico-chemical properties also showed wide variation. The study suggests thatB. variegata with a deep root system is the most suitable species for plantation under agroforestry systems. R. pseudoacacia and G. optiva with deep root systems, more lateral spread and high soil binding factor are suitable for plantation on degraded lands for soil conservation.  相似文献   
4.
Simulation of quick runoff components such as surface runoff and associated soil erosion requires temporal high‐resolution rainfall intensities. However, these data are often not available because such measurements are costly and time consuming. Current rainfall disaggregation methods have shortcomings, especially in generating the distribution of storm events. The objectives of this study were to improve point rainfall disaggregation using a new magnitude category rainfall disaggregation approach. The procedure is introduced using a coupled disaggregation approach (Hyetos and cascade) for multisite rainfall disaggregation. The new procedure was tested with ten long‐term precipitation data sets of central Germany using summer and winter precipitation to determine seasonal variability. Results showed that dividing the rainfall amount into four daily rainfall magnitude categories (1–10, 11–25, 26–50, >50 mm) improves the simulation of high rainfall intensity (convective rainfall). The Hyetos model category approach (HyetosCat) with seasonal variation performs representative to observed hourly rainfall compared with without categories on each month. The mean absolute percentage accuracy of standard deviation for hourly rainfall is 89.7% in winter and 95.6% in summer. The proposed magnitude category method applied with the coupled HyetosCat–cascade approach reproduces successfully the statistical behaviour of local 10‐min rainfall intensities in terms of intermittency as well as variability. The root mean square error performance statistics for disaggregated 10‐min rainfall depth ranges from 0.20 to 2.38 mm for summer and from 0.12 to 2.82 mm for the winter season in all categories. The coupled stochastic approach preserves the statistical self‐similarity and intermittency at each magnitude category with a relatively low computational burden. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
5.
北京环城游憩带旅游地类型与空间结构特征   总被引:73,自引:9,他引:73  
苏平  党宁  吴必虎 《地理研究》2004,23(3):403-410
本文针对我国城市居民以城市周边为目的地近距离旅游日益增长的现象 ,以北京市行政区域内除东城、西城、崇文、宣武四个城区以外 14个区县中的 2 35处旅游地作为研究样本 ,按照地复合分类法根据旅游地的资源属性和旅游活动的性质将旅游地分为 9种类型 ,根据北京市情况可归并为 4类 ;运用空间结构、计量地理学理论以及地理信息系统、电话调查等技术手段 ,将四类 2 35处旅游地的大量数据分别进行了城市中心距离、回转半径法、空间分布曲线、空间离散指数等旅游计量地理研究 ,从而得出北京环城游憩带旅游地的空间结构特征  相似文献   
6.
Ron J. Smith 《Geoforum》2011,42(3):316-328
This paper highlights the importance of analysis of the microgeographies of occupation, and the spatially-differentiated means that the Israeli Occupation Forces use to maintain the occupation and create spaces of graduated incarceration for Palestinians. Using the examples of the hinterlands of Qalqiliyah and the old city of Al-Khalil (Hebron) in the occupied West Bank, this paper exposes the microgeographical differentiation the occupation mobilizes in its attempt to enact a panoptic sovereignty over the population, in the process of dispossession. This study challenges geopolitical formations of the state as primary actor, and focuses instead on narratives of Palestinians describing their own experiences of occupation by a hostile state. By relying on popular media, semi-structured interviews, and participant observation, this paper seeks to incorporate a Palestinian vision of life under occupation to challenge traditional geopolitical visions of the Palestinian Israeli conflict, in effect creating a subaltern geopolitical narrative.  相似文献   
7.
泸沽湖以其独特的摩梭风情和秀丽的山水风光被列为国家级风景名胜区、省级旅游区和省级自然保护区。通过对泸沽湖自然保护区风景园林植物种类资源的调查研究。发现共有141种。分属于39科,80属,并依据风景园林植物的特性、观赏目的、生态习性、栽培方式等。将保护区的园林植物划归为林木类、花木类、果木类、观叶类、遮荫类、蔓木类六大功能类型,为当地因地制宜实施生态保护和园林景点建设提供了科学依据和参考。最后。就野生园林资源的开发、保护、引种、发展和综合利用提出了几点建议。  相似文献   
8.
This article describes Professor David Mark’s considerable contributions over the last 11 years to research in Ethnophysiography, the study of terms used for landscape features in different languages, and toponyms (place-names). His preceding research is briefly discussed to provide a summary of the foundation from which ethnophysiography emerged. This article describes the key stages of development of this new field, including David Mark’s collaborations with Andrew Turk, David Stea, and others. It briefly summarizes the key theories used and the two ethnophysiography case studies undertaken thus far. This article provides an overview of how this collaborative transdisciplinary area of research has developed. It highlights the importance of David Mark’s scholarship in this process and indicates some of the impacts of the research.  相似文献   
9.
高等本科地理信息系统专业课程体系分类研究   总被引:2,自引:0,他引:2  
从适应人才培养需要的角度,揭示了现行不同类型的地理信息系统专业课程体系存在的问题。根据课程理论的有关研究成果、地理信息系统学科特征和本科地理信息系统专业的培养目标,提出了本科地理信息系统专业课程的分类体系。  相似文献   
10.
ABSTRACT

Ten years after their publication, the Eurocodes, including Eurocode 7 for Geotechnical design, are being revised taking into account experiences with their use and developments in design concepts and practices since their publication to produce a second generation of the Eurocodes. The objectives for this second generation of Eurocode 7 are to improve its ease of use, harmonise its structure with the other Eurocodes, reduce the number of nationally determined parameters, include measures for robustness and include sections on topics not covered in the current Eurocode 7, such as numerical methods, reinforced soil and ground improvement. The evolution of Eurocode 7 aims to hone its safety and risk assessment aspects by developing the concept of Geotechnical Categories, expanding the supervision, monitoring and maintenance requirements, and explicitly allowing for reliability differentiation.  相似文献   
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