基于无线Mesh网络技术的应急通信技术应用   总被引：2，自引：0，他引：2  

付荣国  肖飞 《地震学刊》2014,(6):778-783

强烈地震发生后,灾区现场通信网络设施往往遭到破坏,因此快速建立有效且覆盖面大的应急通信网络,及时传递灾情信息,对现场组织救灾及指挥调度等救援工作具有重大意义。无线网络具有组网简单快速、成本低等技术特点,适合作为现场应急通信的网络平台。本文提出了一种基于无线Mesh网络技术的地震现场应急通信方法,在灾区现场迅速组建无线局域网,从而实现信息传递和共享,整个系统组网快捷、健壮性好,并且通过卫星通信技术可以将各局域网组成灾区广域网并进一步接入互联网,该方法能满足地震现场应急通信信息传输的基本要求。  相似文献   

桂江流域土壤侵蚀估算及其时空特征分析   总被引：2，自引：1，他引：1  

陈萍  Lian Yanqing  蒋忠诚  覃小群 《中国岩溶》2014,33(4):473-482

桂江流域的水土流失现状研究对珠江三角洲的水生态安全有重要的现实意义。采用修正的通用土壤流失方程（RUSLE）估算了桂江流域的土壤侵蚀模数与年侵蚀总量,分析流域内土壤侵蚀的时空分布特征,探讨了影响该区域土壤侵蚀强度的自然与人文因素。结果表明,桂江流域51.8%的地表都在发生不同程度的土壤侵蚀。从全流域平均土壤侵蚀强度来看,属于中度侵蚀。从土壤侵蚀面积来看,约85%的地表处于微度、轻度与中度侵蚀。4-6月的全流域平均土壤侵蚀强度最大,侵蚀总量也是最大的。流域的土壤侵蚀主要发生在高程在30~600m的低山丘陵-高地地貌区内的林地与耕地中。流域内岩溶区的土壤侵蚀强度随着石漠化程度从无到中度逐渐增加,轻、中度石漠化区的土壤侵蚀强度达到强度侵蚀等级。   相似文献   

自动计算热带气旋位置和范围的方法研究     

LIU  Yong-lu SHAO  Li-min LANG  Feng-wang 《海洋通报(英文版)》2013,(2):37-45

本文以卫星云图的热带气旋云系为研究对象,基于Canny边缘检测、contour轮廓提取等方法,研究了通过图像的形状特征和范围大小对热带气旋云系进行自动识别,得到了较好的效果。这种方法有助于提高热带气旋云系识别的自动化程度,实现热带气旋的自动跟踪,从而为热带气旋的预报提供了便利。  相似文献   

MT有限元模拟中截断边界的影响     

汤井田  薛帅 《吉林大学学报(地球科学版)》2013,43(1):267-274

利用有限元方法进行大地电磁正演数值模拟时,由于是在有限网格区域上的数值计算,模拟计算时的网格边界为截断边界,而有限元数值模拟时的大地电磁场边界条件需要在足够远处才能够满足,所以截断边界的存在可能会使大地电磁正演模拟的边界条件无法满足,致使对计算结果和计算精度产生影响。利用有限元二维正演程序,在网格边界处加载一维情况下的大地电磁场,然后固定研究区域的网格剖分,并对一维地电模型和二维地电模型在改变有限元网格边界大小的情况下进行计算。在对一维模型进行模拟计算时,截断边界对边界条件没有影响,边界条件自然满足。而对二维模型进行模拟计算时,截断边界的存在对计算结果有较大影响。利用趋肤深度作为有限元网格边界变化的量度,通过改变网格边界大小,对不同的二维地电模型进行计算比较,总结出适合大地电磁有限元正演模拟的参考网格边界。  相似文献   

Evapotranspiration Estimation Based on MODIS Products and Surface Energy Balance Algorithms for Land （SEBAL） Model in Sanjiang Plain, Northeast China   总被引：1，自引：1，他引：0  

DU Jia  SONG Kaishan  WANG Zongming  ZHANG Bai  LIU Dianwei 《中国地理科学(英文版)》2013,23(1):73-91

In this study,the Surface Energy Balance Algorithms for Land(SEBAL) model and Moderate Resolution Imaging Spectroradiometer(MODIS) products from Terra satellite were combined with meteorological data to estimate evapotranspiration(ET) over the Sanjiang Plain,Northeast China.Land cover/land use was classified by using a recursive partitioning and regression tree with MODIS Normalized Difference Vegetation Index(NDVI) time series data,which were reconstructed based on the Savitzky-Golay filtering approach.The MODIS product Quality Assessment Science Data Sets(QA-SDS) was analyzed and all scenes with valid data covering more than 75% of the Sanjiang Plain were selected for the SEBAL modeling.This provided 12 overpasses during 184-day growing season from May 1st to October 31st,2006.Daily ET estimated by the SEBAL model was misestimaed at the range of-11.29% to 27.57% compared with that measured by Eddy Covariance system(10.52% on average).The validation results show that seasonal ET from the SEBAL model is comparable to that from ground observation within 8.86% of deviation.Our results reveal that the time series daily ET of different land cover/use increases from vegetation on-going until June or July and then decreases as vegetation senesced.Seasonal ET is lower in dry farmland(average(Ave):491 mm) and paddy field(Ave:522 mm) and increases in wetlands to more than 586 mm.As expected,higher seasonal ET values are observed for the Xingkai Lake in the southeastern part of the Sanjiang Plain(Ave:823 mm),broadleaf forest(Ave:666 mm) and mixed wood(Ave:622 mm) in the southern/western Sanjiang Plain.The ET estimation with SEBAL using MODIS products can provide decision support for operational water management issues.  相似文献   

Storage and density of soil organic carbon in urban topsoil of hilly cities: A case study of Chongqing Municipality of China   总被引：1，自引：1，他引：0  

LIU Yong  WANG Cheng  YUE Wenze  HU Yanyan 《中国地理科学(英文版)》2013,23(1):26-34

Rapid urbanization results in the conversion of natural soil to urban soil,and consequently,the storage and density of the soil carbon pools change.Taking Chongqing Municipality of China as a study case,this investigation attempts to better understand soil carbon pools in hilly cities.First,the vegetated areas in the study area were derived from QuickBird images.Then,topsoil data from 220 soil samples(0-20 cm) in the vegetated areas were collected and their soil organic carbon(SOC) densities were analyzed.Using the Kriging interpolation method,the spatial pattern of SOC was estimated.The results show that the SOC density exhibited high spatial variability in the urban topsoil of Chongqing.First,the SOC density in topsoil decreased according to slope in the order 2°-6° < 25°-90° < 0°-2° < 6°-15° < 15°-25°.Second,the newly developed areas during 2001-2010 had a lower SOC density than the areas built before 1988.Third,urban parks and gardens had a higher SOC density in topsoil,residential green land followed,and scattered street green land ranked last.For hilly cities,the variability of terrain affects the distribution of SOC.The Kriging results indicate that Kriging method combining slope with SOC density produced a high level of accuracy.The Kriging results show that the SOC density to the north of the Jialing River was higher than the south.The vegetated areas were estimated to amount to 73.5 km2 across the study area with an SOC storage of 0.192 Tg and an average density of 2.61 kg/m2.  相似文献   

Spatial pattern and regional types of rural settlements in Xuzhou City, Jiangsu Province, China   总被引：4，自引：1，他引：3  

MA Xiaodong  QIU Fangdao  LI Quanlin  SHAN Yongbin  CAO Yong 《中国地理科学(英文版)》2013,23(4):482-491

This paper principally focuses on the morphological differences,spatial pattern and regional types of rural settlements in Xuzhou City of Jiangsu Province in China.Using satellite images of Xuzhou City taken in 2007 and 2008 and models of exploratory spatial data analysis(ESDA) and spatial metrics,the paper conducts a quantitative analysis of the morphological pattern of rural settlements,and finds significant characteristics.First,rural settlements in Xuzhou City are significantly agglomerated in terms of their spatial distribution;meanwhile,there is significant variation in the geographical density distribution.Second,the scale of rural settlements in Xuzhou City is larger than the average in Jiangsu Province,and the histogram of the scale data is more even and more like a gamma distribution.There are a significant high-value cluster in the scale distribution,and local negative correlation between the scale and density distribution of rural settlements in Xuzhou City.Third,the morphology of rural settlements in Xuzhou City shows relative regularity with good connection and integrity,but the spatial variation of the morphology is anisotropic.Finally,according to the characteristics of density,scale,and form of rural settlements,the rural settlements of Xuzhou City are divided into three types:A high-density and point-scattered type,a low-density and cluster-like type and a mass-like and sparse type.The research findings could be used as the scientific foundation for rural planning and community rebuilding,particularly in less-developed areas.  相似文献   

Residents′Activity-travel Behavior Variation by Communities in Beijing,China   总被引：3，自引：1，他引：2  

ZHAO Ying  CHAI Yanwei 《中国地理科学(英文版)》2013,23(4):492-505

China’s transition from a planned economy to a market economy has resulted in many changes in its urban structure and society and provided an opportunity for a quasi-longitudinal case study on the relationship between the built environment and activity-travel behavior.This paper draws upon data from an activity diary survey conducted in Beijing in 2007.The survey sample comprised 652 residents living in Danwei(work unit),commodity housing,and affordable housing neighborhoods.On the basis of the three-dimensional geo-visualization analysis of the space-time path and statistical multivariate regression models of daily travel and leisure time,it was found that both residential spatial factors and socio-demographics influence residents’ daily behaviors.The findings show that Danwei residents have less daily travel time than those who live in commodity housing,but people living in affordable housing endure the longest travel time.Daily leisure time is associated more with individual attributes.We argue that although China’s transition is currently gradual,the Danwei system may continue to play significant roles in daily life,and it might provide a valuable model for neighborhood spatial planning.  相似文献   

Genetic diversity and population structure of Eleutheronema rhadinum in the East and South China Seas revealed in mitochondrial COI sequences   总被引：1，自引：0，他引：1  

孙鑫序  徐冬冬  楼宝  张涛  辛俭  郭垚示  马世磊 《中国海洋湖沼学报》2013,31(6):1276-1283

Eleutheronema rhadinum is a potential commercial fisheries species and is subject to intense exploitation in China. Knowledge on the population structure of E. rhadinum in Chinese coastal waters, which is important for sustainable exploitation and proper resource management, is lacking. In the present study, the genetic diversity and population structure of E. rhadinum were evaluated using a 564-base pair fragment of the mitochondrial cytochrome c oxidase subunit I （COl） gene. A total of 76 specimens were collected from three localities around the East （Qidong and Zhoushan） and South China Seas （Zhuhai）. Among these individuals, nine polymorphic sites were detected and 1 l distinct haplotypes were defined. High levels ofhaplotype diversity （h=0.759i0.035） and low levels of nucleotide diversity （re=0.001 98i0.003 26） were observed in these populations, Hierarchical analysis of molecular variance （AMOVA） indicated that 96.72% of the genetic variation occurred within the populations, whereas 3.28% occurred among populations. No significant genealogical branches or clusters were recognized on the neighbor-joining tree. Intra-group variation among populations was significant （~0~t=0.032 85, P〈0.01）. These results suggest that E. rhadinum populations in the East and South China Seas have developed divergent genetic structures. Tests of neutral evolution and mismatch distribution suggest that E. rhadinum may have experienced a population expansion. The present study provides basic information for the conservation and sustainable exploitation of this species.  相似文献   

Remote forcing of Indian Ocean warming on Northwest Pacific during E1 Nino decaying years： a FOAM model approach     

胡海波  洪晓媛  张媛  杨修群  刘伟  卢华国  杨建玲 《中国海洋湖沼学报》2013,(6):1363-1371

This paper attempts to analyze in detail the remote influence of the Indian Ocean Basin warming on the Northwest Pacific （NWP） during the year of decaying E1 Nifio. Observation data and the Fast Ocean- Atmosphere coupled Model 1.5 were used to investigate the triggering conditions under which the remote influence is formed between the positive sea surface temperature （SST） anomaly in the North Indian Ocean and the Anomalous Northwest Pacific anticyclone （ANWPA）. Our research show that it is only when there is a contributory background wind field over the Indian Ocean, i,e., when the Indian Summer Monsoon （ISM） reaches its peak, that the warmer SST anomaly in the North Indian Ocean incites significant easterly wind anomalies in the lower atmosphere of the Indo-West tropical Pacific. This then produces the remote influence on the ANWPA. Therefore, the SST anomaly in the North Indian Ocean might interfere with the prediction of the East Asia Summer Monsoon in the year of decaying E1 Nifio. Both the sustaining effect of local negative SST anomalies in the NWP, and the remote effect of positive SST anomalies in the North Indian Ocean on the ANWPA, should be considered in further research.  相似文献