探讨土地整理中的景观生态规划与设计     

鲁迪  杨剑  魏雅丽  陶文星  张敏 《国土资源导刊(湖南)》2005,2(3):27-29

土地整理是一项实现土地资源可持续利用的战略性基础工程。我国人多地少，耕地资源质量低，近年来由于土地利用不合理等现象，导致耕地数量持续减少：从战略发展的高度来看，这将严重威胁到国家安全和国民经济持续发展，为此国家在实行最严格的耕地保护政策的同时，全面推行土地整理工作以求达到占补平衡，但是我们应该看到土地整理活动是一种综合性的区域开发活动，这种区域开发活动可彻底改变原有生态系统的组成与格局，因此土地整理的景观生态规划设计对生态环境有着直接的影响。  相似文献   

�봨����ǰ�����NmF2�쳣�Ŷ�   总被引：6，自引：1，他引：5  

熊晶  吴云  祝芙英  林剑  周义炎  杨剑 《大地测量与地球动力学》2008,28(6):22-26

????COSMIC????????????????2008??5??12????Ms8.0?????????????4????5?????????F2???????????NmF2????????????з???????????4???????????????F2???????????NmF2??????????仯???????????????γ?????????????????????????????Щ?????п????????????????  相似文献   

����GPS���ߵ����������о���ǰ������쳣   总被引：8，自引：6，他引：2  

杨剑  吴云  周义炎 《大地测量与地球动力学》2008,28(1):16-22

????COSMIC??????????????????????о???2006??11??15????????Ms8.0?????2007??2??25????????Ms5.3??????????????????????????????仯,?????K???(???)?????????????????仯??????????????? ?о????????GPS???????????????????????????????????????????????仯,?????仯???п????????????????  相似文献   

Spatial distribution of dimethylsulfide and dimethylsulfoniopropionate in the Yellow Sea and Bohai Sea during summer   总被引：1，自引：0，他引：1  

杨剑  杨桂朋  张洪海  张升辉 《中国海洋湖沼学报》2015,33(4):1020-1038

Abstrac t The distributions of dimethylsulfide(DMS) and its precursor dimethylsulfoniopropionate(DMSP) in surface water of the Yellow Sea and the Bohai Sea were studied during June 2011. The mean concentrations and ranges of DMS, dissolved DMSP(DMSPd), and particulate DMSP(DMSPp) in surface waters were 6.85(1.60–12.36), 7.25(2.28–19.05) and 61.87(6.28–224.01) nmol/L, respectively. There were strong correlations between DMSPp and chlorophyll a in the Bohai Sea and the North Yellow Sea, respectively, and concentrations of DMS and DMSP were high, with a relatively high proportion of dinoflagellates, in the region of the South Yellow Sea Cold Water Mass. Results show that phytoplankton biomass and species composition were important factors that controlled the distribution of DMS and DMSP. Complex environmental factors, including nutrients, transparency, and terrestrial runoff, might also influence the variability in DMS and DMSP. Biological production and consumption rates of DMS in the Bohai Sea were higher than those in the Yellow Sea. DMS production rates were closely correlated with DMSPd concentrations. DMS and DMSP exhibited obvious diel variations, with high concentrations occurring in the late afternoon(16:00–19:00) and low concentrations occurring during the night, implying that the intensity of solar radiation had a significant influence on these variations. Size distributions of chlorophyll a and DMSPp were also investigated and large nanoplankton(5–20 μm), mainly diatoms, contributed significantly to chlorophyll a and DMSPp at most stations. The average sea-to-air flux of DMS in the study area was estimated to be 11.07 μmol/(m2 ·d) during the summer.  相似文献   

基于ETM数据的北衙地区找矿应用效果     

杨剑  薛廉  张景华 《物探化探计算技术》2015,(1):106-114

遥感技术能以较低的成本快速地提供更多更有效的地质异常信息,提高工作效率,降低风险[1]。在分析云南省北衙金矿远景区区域地质背景和控矿规律的基础上,通过目视解译的方法对该区的区域地质进行了解译,并对该区域进行详细的定量分析以及蚀变异常的光谱反映特征提取。从ETM影像中利用相关方法提取了与矿区有关的羟基、铁染异常信息,解译效果良好,划分了找矿远景区。  相似文献   

论地下水资源的永续利用     

杨剑  易发成 《国土资源与环境》2002,(1):16-18

  相似文献   

汶川8.0级地震强震动特征初步分析   总被引：19，自引：3，他引：16  

于海英  王栋  杨永强  卢大伟  解全才  张明宇  周宝峰  江纹乡  程翔  杨剑 《震灾防御技术》2008,3(4):321-336

本文对国家强震动台网中心收集的2008年5月12日14时28分04秒汶川8．0级地震中获取的420组三分量加速度记录进行了处理和初步分析。在这次地震中布设在龙门山断裂带及其周围地区的50多个台站获得了大于100gal的加速度记录,有46组三分量加速度记录的断层距小于100km,使中国大陆近断层区域所获得的强震动加速度记录的数量成倍增加。本文依据这批数据,对汶川大地震强震动特性进行了初步分析,给出了此次地震断层附近地区的PGA衰减规律,并利用此规律模拟了断层附近的加速度峰值,绘制了PGA分布图、竖向PGA与水平向PGA比值图;给出了汶川地震断层附近的加速度反应谱、上盘效应、竖向效应、速度大脉冲效应等地震动特征,这些特征可作为抗震设计规范修订的依据并供灾区重建时参考。  相似文献   

近场数字强震仪记录误差分析与零线校正方法   总被引：6，自引：0，他引：6  

于海英  江汶乡  解全才  杨永强  程翔  杨剑 《地震工程与工程振动》2009,29(6)

本文对数字强震仪记录进行了误差分析,并对国家强震动台网入网的5种型号数字强震仪系统作了振动台对比试验,分析了该系统加速度记录积分后速度和位移时程零线漂移的原因.本文提出了加速度记录的零线漂移校正方法和校正准则.为了印证零线校正方法的可靠性,对振动台试验中强震仪记录到的加速度两次积分得出位移时程与试验时记录到的绝对位移进行比较,计算位移和振动台绝对位移完全一致;对2008年5.12汶川8.0级大地震和1999年台湾9.21集集7.6级地震现场加速度记录两次积分后得出永久位移与两次大地震的GPS同震位移进行比较.结果表明,该方法对大地震近场仪器墩会发生倾斜或产生永久位移时加速度记录的零线校正有明显效果,可以给出加速度积分后的速度和位移并符合校正准则.本文方法解决了对大地震近场地面运动的研究停留在对峰值加速度和反应谱的研究阶段的困惑,满足了结构抗震对地面永久位移的需求.  相似文献   

LEO GPS接收机仪器偏差估计   总被引：1，自引：0，他引：1       下载免费PDF全文

林剑  吴云  熊晶  祝芙英  杨剑 《地球物理学报》2010,53(5):1034-1038

LEO GPS观测已成为空间电离层研究重要手段之一,通过GPS双频观测值获取的TEC则是电离层探测的一个重要参量,为获取高精度TEC需估计和消除GPS接收机仪器偏差（DCB）.本文旨在探索一种全新的LEO GPS接收机仪器偏差的估计方法：基于电离层球对称的假设,利用CHAMP和COSMIC原始GPS观测数据,采用几何映射函数,通过最小二乘解算出GPS接收机仪器偏差.结果表明：(1)2008年1月份期间,通过上述方法解算的仪器偏差都较稳定,相比COSMIC网上发布结果,标准偏差都在0.6 ns以内;（2）COSMIC（轨道高度大约800 km）仪器偏差估计结果优于CHAMP（轨道高度大约400 km）的结果,原因为：对于不同轨道高度LEO GPS仪器偏差估计,其较高轨道高度的电离层球对称假设影响较小.  相似文献   

春秋季南黄海二甲基硫(DMS)与二甲巯基丙酸(DMSP)的浓度分布研究   总被引：2，自引：0，他引：2  

杨剑  杨桂朋  张洪海  张生辉 《海洋学报(英文版)》2016,35(2):76-87

Temporal distributions of dimethylsulfide(DMS) and dimethylsulfoniopropionate(DMSP) were studied in the southern Yellow Sea(SYS) during April and September 2010. The mean concentrations(range) of DMS, dissolved and particulate DMSP(DMSPd and DMSPp) in the surface waters in spring are 1.69(0.48–4.92), 3.18(0.68–6.75)and 15.81(2.82–52.33) nmol/L, respectively, and those in autumn are 2.80(1.33–5.10), 5.45(2.19–11.30) and 30.63(6.24–137.87) nmol/L. On the whole, the distributions of DMS and DMSP in spring are completely different from those in autumn. In the central part of the SYS, the concentrations of DMS and DMSP in spring are obviously higher than those in autumn, but the opposite situation is found on the south of 34°N, which can be attributed to the differences in nutrients and phytoplankton biomass and composition between spring and autumn. Besides,the seasonal variations of water column stability and the Changjiang diluted water also have significant impact on the distributions of DMS and DMSP in spring and autumn on the south of 34°N. DMS and DMSPp concentrations coincide well with chlorophyll a(Chl a) levels in the spring cruise, suggesting that phytoplankton biomass may play an important role in controlling the distributions of DMS and DMSPp in the study area. Annual DMS emission rates range from 0.015 to 0.033 Tg/a(calculated by S), respectively, using the equations of Liss and Merlivat(1986) and Wanninkhof(1992). This result implies a significant relative contribution of the SYS to the global oceanic DMS fluxes.  相似文献