2010年“7·25”云南强降雨物理量特征分析   总被引：1，自引：0，他引：1  

黄文凤  解福燕  杨韬  YANG Tao 《云南地理环境研究》2011,23(3):94-97,102

2010年7月25日,云南省产生了一次大雨、暴雨天气过程,通过对天气影响系统以及动力、热力、水汽条件等物理量特征分析表明,热带低压倒槽引导700 hPa上的辐合切变西移,加上低涡的配合,是此次强降雨过程的关键影响系统,加之高层到低层的负速度中心向左倾斜的趋势与中低层的热带低压倒槽、辐合切变走向一致,低层正涡度并有较强的水汽辐合,高层负涡度,并有较强的水汽辐散,从北部湾至云南省存在较丰富的水汽输送,强降水开始前,k指数在不断增大,垂直上升运动强烈,有较强的不稳定能量堆积,有利于对流活动的发生和发展,极易产生大雨、暴雨天气。  相似文献   

北京城市边缘区典型乡镇发展有序协调度研究     

李世峰  于瑞  来璐  崔莎  董锁成 《地域研究与开发》2011,30(6):70-73

大城市边缘区是人口、用地、经济、社会和生态等发展最无序的区域。基于城市边缘区有序协调发展的机理,综合运用影响程度法、层次分析法和专家评判法等方法,从时间、空间、数量和功能4个维度上评价并分析北京城市边缘区3个典型乡镇(旧宫镇、长陵镇和永清镇)发展的有序协调程度。研究结果表明,旧宫镇的有序协调程度最高,其次是长陵镇,永清镇最低。  相似文献   

中亚地缘政治新格局及其对中国的战略影响     

陆俊元 《世界地理研究》2011,20(2):8-14

中亚作为一个相对独立的地缘政治单元,在区位、文化、社会等方面具有特殊性,在能源和资源方面具有显著的优势,在世界政治和国际关系中具有重要地位。自“9·11”事件所致的阿富汗战争之后,中亚地缘政治重新洗牌,多种国际政治行为体竞相介入中亚,形成复杂的地缘政治关系,中亚地缘政治格局发生新的变化,对中国产生新的和复杂的战略影响。  相似文献   

南京“老字号”餐饮企业地理区位变化及影响因素分析     

陶鸿  赵媛  袁晓燕  陶萍 《世界地理研究》2011,(3):145-154

通过对南京＂老字号＂餐饮企业生存现状的调查,发现南京＂老字号＂餐饮企业不仅数量在减少,而且有从老城区向外搬迁的趋势。探讨其形成原因,主要有城市建设、市场、消费需求与口味变化、法律法规不健全等外部因素,以及企业体制陈旧、产品缺乏创新、品牌意识淡薄、传承方式单一、品牌扩张和宣传力度不够、产品质量下滑、就餐环境和服务质量下降等内部因素。针对＂老字号＂餐饮企业发展参差不齐的状况,提出振兴南京＂老字号＂餐饮企业举措建议,以充分发挥＂老字号＂不可估量的品牌价值、经济价值和文化价值。  相似文献   

Long-term measurements of 36Cl to investigate potential solar influence on the decay rate     

《Astroparticle Physics》2014

Recently, Jenkins et al. [6] reported on fluctuations in the detected decay events of ³⁶Cl which were measured with a Geiger–Müller counter. Experimental data of ³²Si measured by means of an end-window gas-flow proportional counter at the Brookhaven National Laboratory show similar periodicity, albeit a different amplitude. Jenkins et al. interpret the fluctuations as evidence of solar influence on the decay rates of beta-decaying radionuclides.In this work, liquid scintillation counting was used to check for potential variations in the ³⁶Cl decay rates. A custom-built counter with three photomultiplier tubes was used. In contrast to commercial counters, the relevant parameters of our system are well controlled and the discrimination threshold and HV setting can be adjusted and checked. The experimental data were analyzed by means of the triple-to-double coincidence ratio (TDCR) method which is a primary method for activity determination. Thus, our results do not depend on any other standard or reference source.Our data show fluctuations which are by more than one order of magnitude lower than those seen in the experiment using a Geiger–Müller counter. More importantly, no oscillation could be identified. Interestingly, our data overlap in time with those from Jenkins et al. [6]. We do not observe the phase and amplitude as seen by Jenkins and conclude that the fluctuations are not due to solar influence. This also implies that the interpretation by Jenkins et al. is false.  相似文献   

MODELING OF REGIONAL DIFFERENTIATION OF LAND-USE DEGREE IN CHINA   总被引：1，自引：0，他引：1  

庄大方  刘纪远 《中国地理科学(英文版)》1997,7(4):302-309

Thestudyonland--useandland--coverchangesbecomesmoreandmoreimPOrtantinglobalenvironmentchangeresearch.AglobalresearchplannamedLUCCwasfoundedbyIGHPandHIJPin1995andonecoreprojectplanandprojectocr-nmittee(CPPCmePELUCC)wasalsofounded.Aninternationalconferenceonland--useandland--coverchangeswasheldintheNetherlands.Inthisconference,fiveframequestions(IGBP,1996)andthreeresearchfocuses(IGBP,1996)havebeenproPOsed.Studyonland--useandland-coverchangesPOssessesanimPOrtantPOsitioninthefield…  相似文献   

Efficient Method for Computing with Certainty Periodic Orbits on a Surface of Section     

E. A. Perdios  V. S. Kalantonis  M. N. Vrahatis 《Celestial Mechanics and Dynamical Astronomy》2002,84(3):231-244

We present an improved method for locating periodic orbits of a dynamical system of arbitrary dimension. The method first employs the characteristic bisection method (CBM) to roughly locate a periodic orbit, followed by the quadratically convergent Newton method to rapidly refine its position. The method is applied to the physically interesting example of the two degrees of freedom photogravitational problem, and shown to surpass the CBM algorithm and Newton's method alone.  相似文献   

自然系列地图轮廓界线统一协调问题     

詹小龙  廖克 《地理学报》1989,(4)

本文讨论了自然系列地图编制中的一个重要问题——自然界线之间的统一协调。作者通过对自然界线的定性、定量研究，阐述了自然界线及其相互联系的特征。并在此基础上提出了自然系列地图轮廓界线统一协调的主要方法和措施。  相似文献   

诸暨铜岩山矿区剥蚀程度地球化学判别指标之研究     

姚俭  何汉泉 《浙江国土资源》1997,(1)

本文简述了铜岩山矿床地质概况，分析了矿区内蚀变带和主要矿体特征，综合研究本矿区剥蚀程度地球化学判别指标。利用累乘晕比值方法，建立5组累乘元素比值公式，求得各组剥蚀系数，以显示矿区内矿体矿化序列和剥蚀程度。发现本矿区内高温成矿元素分布在矿体上方，中低温成矿元素聚集在矿体下部之矿化反序列现象。  相似文献   

The influence of hydroelectrical development on the flow regime of the karstic river Cetina     

Ognjen Bonacci  Tanja Roje‐Bonacci 《水文研究》2003,17(1):1-15

The Cetina River is a typical karst watercourse in the deep and well‐developed Dinaric karst. The total length of the Cetina River open streamflow from its spring to the mouth is about 105 km. Estimated mean annual rainfall is 1380 mm. The Cetina catchment is built of Triassic, Jurassic, and Cretaceous carbonate strata. The western part of the catchment by the Cetina River is referred to as the ‘direct’ or topographic catchment. It was defined based on surface morphologic forms, by connection between mountain chain peaks. This part of the catchment is almost entirely situated in the Republic of Croatia. The eastern part of the catchment is referred to as the ‘indirect’ catchment, and is mainly situated in Bosnia‐Herzegovina. Water from the ‘indirect’ catchment emerges from the western ‘direct’ catchment in numerous permanent and temporary karst springs. Since 1960, numerous hydrotechnical works have been carried out on the Cetina River and within its catchment. Five hydroelectric power plants (HEPPs), five reservoirs, and three long tunnels and pipelines have been built. Their operation has significantly altered the natural hydrological regime. The Cetina River is divided into two hydrological reaches. In the 65 km upstream, the hydrological regime was redistributed within the year: low flows had increased and high flows had decreased, although the mean annual discharge remained the same. Part of the Cetina watercourse downstream from the Pran?evi?i Reservoir lost the majority of its flow. The mean annual discharges dropped from 100 m³ s^?1 to less than 10 m³ s^?1 because of the Zaku?ac HEPP development. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献