雷达资料传输质量的影响因素及应对措施     

赵瑞金  杨海龙 《气象科技》2011,39(1):76-82

介绍了河北省目前新一代天气雷达传输与共享资料的种类及实现方法,并结合近年来河北省雷达资料传输的实际情况对影响雷达数据传输的主要因素进行了分析。指出影响新一代天气雷达资料传输质量的因素来自网络和通信线路、传输软件、雷达设备和人为因素等多个环节,并给出了各种影响因素相应的处理措施,为新一代天气雷达的资料共享、监控和提高雷达资料业务传输质量提供参考。  相似文献   

A study on the effects of the surrounding faults on water loss in the Zoige Wetland, China   总被引：1，自引：1，他引：0  

Mei Li  Rui Xu  Wendian Huang  Hailong Sun  Lin Luo 《山地科学学报》2011,8(4):518-524

The Zoige wetland is the biggest alpine wetland in the world,and an important water resource of the Yellow River.Due to natural and human factors,the Zoige wetland has been seriously degraded.Existing studies on the Zoige wetland mainly focus on the macro features of the wetland,while the influence of the surrounding faults on the Zoige wetland degradation is rarely studied.This study uses terrain data to analyze the cover change and the water loss caused by the Wqie-Seji fault based on the distributed hydrological model.The simulated water loss demonstrates that the Normalized Difference Vegetation Index(NDVI) is the most important factor for inducing water loss.The fault is also a factor that cannot be neglected,which has caused 33% of the wetland water loss.Therefore,it is of importance to study the influence of the fault on the wetland degradation.  相似文献   

An approximate analytical solution for measuring air permeability of asphalt samples partially saturated with water   总被引：1，自引：1，他引：0  

Hailong Li  Yuchen Zhang  Yuqiang Xia 《Environmental Earth Sciences》2011,63(2):283-290

In coastal areas, abnormally high pressure may be caused by the tide-induced water table variation under extensive pavements, particularly during rainfall. To simulate the rainfall infiltration effects on the air permeability of asphalt pavements in coastal area, column-shaped asphalt sample was fixed in the upper part of a steel cylinder with its upper surface saturated with ponding water (depth < 5 mm) and open to the atmosphere. The cylinder’s lower part formed an air chamber. The chamber was pressurized and then the air therein was released naturally through the sample. The pressure variation with time in the chamber was recorded for analysis. Based on the Green–Ampt piston model for the surface water infiltration, an approximate analytical solution was derived to describe the pressure–time relationship in the chamber. A new parameter called the escape pressure was introduced to describe the air pressure needed for the chamber air to break through the capillary pressure induced by the ponding water. The analytical solution gave good estimations of both the escape pressures and the harmonic averages of the permeabilities of the wet and dry parts of 14 samples in the sense that excellent fittings were obtained between the observed and predicted air pressures in the air chamber. The estimated escape pressure ranges from 0.0 to 1.74 kPa. The harmonic average of the permeabilities of the wet and dry parts is 5–94% of the dry sample’s permeability.  相似文献   

中国经济增长与制度变迁的空间面板数据分析     

季民河  武占云  苏海龙  姜磊 《地域研究与开发》2011,30(6):1-5

以North的体制经济学为理论依据,将新古典经济学的Solow增长模型扩展为一个包含制度变量的计量经济学模型,并结合空间面板数据分析方法,使用1997—2005年中国省区的社会经济数据实证检验了经济制度环境对经济增长的影响。研究结果表明:该时期的制度变迁对中国的经济增长具有显著贡献力,证实了North的制度经济学理论假设。此外,空间面板数据的分析方法深入地揭示了省域经济活动之间存在的空间自相关性,即地区之间通过技术扩散、要素转移以及社会文化交流等在地理空间上发生相互影响。  相似文献   

Groundwater Formation Mechanism in Beishan Area, Northwest China—A Potential Site for China’s High-Level Radioactive Waste Repository     

GUO Yonghai  WANG Hailong  DONG Jiannan 《《地质学报》英文版》2013,87(Z1):633-635

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Quantifying bank storage of variably saturated aquifers   总被引：1，自引：0，他引：1  

Li H  Boufadel MC  Weaver JW 《Ground water》2008,46(6):841-850

Numerical simulations were conducted to quantify bank storage in a variably saturated, homogenous, and anisotropic aquifer abutting a stream during rising stream stage. Seepage faces and bank slopes ranging from 1/3 to 100/3 were simulated. The initial conditions were assumed steady-state flow with water draining toward the stream. Then, the stream level rose at a constant rate to the specified elevation of the water table given by the landward boundary condition and stayed there until the system reached a new steady state. This represents a highly simplified version of a real world hydrograph. For the specific examples considered, the following conclusions can be made. The volume of surface water entering the bank increased with the rate of stream level rise, became negligible when the rate of rise was slow, and approached a positive constant when the rate was large. Also, the volume decreased with the dimensionless parameter M (the product of the anisotropy ratio and the square of the domain's aspect ratio). When M was large (>10), bank storage was small because most pore space was initially saturated with ground water due to the presence of a significant seepage face. When M was small, the seepage face became insignificant and capillarity began to play a role. The weaker the capillary effect, the easier for surface water to enter the bank. The effect of the capillary forces on the volume of surface water entering the bank was significant and could not be neglected.  相似文献   

Ecologically based landscape pattern optimization in northwest of Beijing     

YUE Depeng  WANG Jiping  LIU Yongbing  ZHANG Xiaoli  LI Hailong  WANG Jie 《地理学报》2009,19(3):359-372

Supported by the technologies of remote sensing (RS) and geographical information system (GIS), we chose northwest of Beijing as a study area and gave priority to understanding of the spatial-temporal characteristics of landscape pattern change through visually interpreted Landsat TM images of 1989, 1996 and 2005. It is believed that there were a series of landscape ecological problems caused by city expansion: landscape ecological connectivity was low; landscape structure was simplified; the fragmentation of green land patch was more obvious on the plain areas, moreover, spatial distribution of green land was unbalanced. For this reason, this study adopted accumulative cost distance model, combined with ecosystem services and spatial interactions of landscape types, analyzed the spatial difference of the ecological function and the compactness of landscape structure in the study area, and further discussed the landscape pattern optimization proposal. We find that it is essential to protect and establish ecological sources, to establish urban ecological corridors, and to establish ecological nodes at the landscape ecological strategic positions so as to intensify spatial relationships among landscape elements and maintain continuity of landscape ecological process and pattern in the course of city expansion. The methods and final results from this study are expected to be useful for landscape ecological planning in Beijing region.  相似文献   

西安城市扩张及其驱动力分析   总被引：79，自引：6，他引：73  

吴宏安  蒋建军  周杰  张海龙  张丽  艾莉 《地理学报》2005,60(1):143-150

随着人口的增长与经济的发展,尤其我国西部城市在西部大开发的背景下,大中城市的扩张十分明显,深刻地影响城市周边的生态环境。如何快速准确地获取城市扩张信息,并分析其驱动力机制,对于指导城市规划,优化西部生态环境与可持续发展都具有十分重要的意义。作者分别采用了监督分类法和归一化裸露指数 (NDBI) 法提取了西安市的城市边界信息,并对二者进行对比分析,认为监督分类法提取的城市边界信息较为准确。在此基础上通过对相关统计资料的分析,认为西安市城区快速扩张与西部大开发以来西安市固定资产投资额的大幅增加以及经济的快速发展有密切的关系,此外人口的增加、交通等基础设施的发展也是重要的驱动因素。  相似文献   

渤海风驱-潮致Lagrange余流的数值模拟与季相时空变异     

李国胜  王海龙  李柏良 《地理学报(英文版)》2005,15(3):273-285

The spatial distribution and seasonal variation of the tide-induced Lagrangian Residual Circulations (LRC hereafter), wind-driven LRC, and the coupling dynamic characteristics were simulated using ECOM, given the Hellerman and Rosenstein global monthly-mean wind stresses. The results showed that the tide-induced LRC of the harmonic constituent M2 bears an identical pattern in four seasons in the Bohai Sea: the surface one is weak with random directions; however, there exist a southeast current from the Bohai Strait to the Laizhou bay, and a weakly anticlockwise gyre in the south of the Bohai Strait for the bottom layer LRC. The magnitude of bottom layer tide-induced LRC is larger than the surface one, and moreover, it contributes significantly to the whole LRC in the Bohai Sea. Unlike the identical structure of the tide-induced LRC, the wind driven LRC varies seasonally under the prevailing monsoon. It forms a distinct gyre under the summer and winter monsoons in July and January respectively, but it seems weak and non-directional in April and September.  相似文献   

数字南水北调的虚拟技术应用——以中线工程河北段主干线为例     

何玲胡文亮  孙海龙 《地球信息科学学报》2004,6(2):72-76

以中线工程河北段主干线为例,讲述了虚拟技术在南水北调工程中的应用设计,并利用虚拟三维模型在三维景观显示、最佳路线选择、缓冲分析、土方计算、分析表面形态、计算坡度、坡向、长度等方面进行了可行性分析。并指出今后需进一步解决的问题。  相似文献