基于空间插值的浙江省城市流时空演变特征研究          下载免费PDF全文

魏国恩  贺清云  朱翔  欧阳晓 《干旱区地理》2019,42(1):215--222

为了探寻发达省份内城市间相互作用的时空特征，该文以浙江省为样本单元，选取2005、2010年和2015年3个时间截面，采用反距离权重法和空间插值手段，从城市流强度视角展开了实证分析。结果表明：（1） 城市间的联系在不断加强，期间城市流强度值随时间的推移而整体得到提升，空间上由初始的“中心点”通过发展扩散向“中心域”转变，中心城市的辐射带动作用开始发挥成效。（2）结构上呈现出相对稳定的北高南低的分布格局，以杭州市为龙头，宁波为副核心，温州、绍兴、舟山为重要节点的多中心城市网络结构雏形初步形成。（3） 城市流强度的空间分异特征分析明显，但分异程度有了些许的改善，侧面说明空间上由初始的“中心点”通过发展扩散向“中心域”转变的基本观点。最后就浙江省如何加强省内城市间“流”的规模性、区域协调性和可持续性展开了讨论。  相似文献   

2003-2016年北极净初级生产力时空变化     

李海丽  柯长青  朱庆辉  舒苏 《海洋学报(英文版)》2019,38(8):111-121

The area of Arctic sea ice has dramatically decreased, and the length of the open water season has increased;these patterns have been observed by satellite remote sensing since the 1970 s. In this paper, we calculate the net primary productivity(NPP, calculated by carbon) from 2003 to 2016 based on sea ice concentration products,chlorophyll a(Chl a) concentration, photosynthetically active radiation(PAR), sea surface temperature(SST), and sunshine duration data. We then analyse the spatiotemporal changes in the Chl a concentration and NPP and further investigate the relations among NPP, the open water area, and the length of the open water season. The results indicate that(1) the Chl a concentration increased by 0.025 mg/m~3 per year;(2) the NPP increased by 4.29 mg/(m~2·d) per year, reaching a maximum of 525.74 mg/(m~2·d) in 2016; and(3) the Arctic open water area increased by 57.23×10~3 km~2/a, with a growth rate of 1.53 d/a for the length of the open water season. The annual NPP was significantly positively related to the open water area, the length of the open water season and the SST.The daily NPP was also found to have a lag correlation with the open water area, with a lag time of two months.With global warming, NPP has maintained an increasing trend, with the most significant increase occurring in the Kara Sea. In summary, this study provides a macroscopic understanding of the distribution of phytoplankton in the Arctic, which is valuable information for the evaluation and management of marine ecological environments.  相似文献   

四川米易海塔地区混合岩型铀矿流体包裹体特征     

郭锐  陈友良  刘凯鹏  郑玉文  胡漾 《矿物学报》2020,40(2):137-148

混合岩型铀矿是康滇地轴上最有希望取得找矿突破的铀矿类型,海塔地区的铀矿化即是该类型铀矿的典型代表。本文针对区内的长英质脉矿石、富晶质铀矿石英脉矿石和含矿热液石英脉中的石英流体包裹体进行了研究。结果表明,海塔地区混合岩型铀矿的成矿作用可分为2个阶段:早期混合岩化热液成矿阶段为高温、中低盐度流体,流体包裹体均一温度集中在380~540℃,盐度变化范围为16.15%~23.18%NaCl eqv,是区内铀成矿的主要阶段;晚期热液叠加改造成矿阶段为中低温、低盐度流体,流体包裹体均一温度集中在140~220℃,盐度变化范围为5.56%~23.18%NaCleqv,是区内富铀矿的形成阶段。流体包裹体的气相成分测试表明,长英质脉矿石石英包裹体中以CH4、CO2为主,其次为H2O和N2;而富晶质铀矿石英脉及含矿热液石英脉石英包裹体中以H2为主,部分含有CO2、CH4、H2O。氢、氧同位素研究表明,早期混合岩化成矿阶段的成矿流体可能为岩浆水与变质水的混合,而晚期热液叠加改造成矿阶段成矿流体中可能有大气降水的加入。  相似文献   

水平低周往复位移下单桩-土相互作用试验研究     

黄福云  陈汉伦  董锐  单玉麟 《岩土力学》2020,41(5):1625-1634

整体式桥台无伸缩缝桥梁（以下简称整体桥）桩基应设计为柔性桩，以保证较好的抗水平变形能力。但是，我国相关规范中判别柔性桩的算法主要应用于单向水平受荷桩，可否沿用至整体桥桩基还有待验证。为此，根据一种特殊设计的桩身变形测量方法，对3根埋深不同的混凝土模型桩进行了低周水平往复位移下的拟静力试验，研究单桩-土体系的抗震性能和相互作用机制。研究表明，水平往复位移下混凝土桩在埋深为3D～6D（D为桩径）范围内开裂；桩的埋深越大，桩身挠曲程度越大、变形特征点位置也越深、桩-土体系的抗弯刚度也越大、水平极限承载力也越高、抗震性能也越强。研究还表明，桩-土体系进入弹塑性阶段后，柔性桩的水平工作性状将逐渐向刚性桩退化。另外，在判别整体桥桩基的水平工作性状时，我国相关规范中的规定偏不安全。实际工程中，建议以Broms方法进行参考计算。  相似文献   

The galaxy luminosity function in the LAMOST Complete Spectroscopic Survey of Pointing Area at the Southern Galactic Cap     

Pin-Song Zhao  Hong Wu  Cong Kevin Xu  Ming Yang  Fan Yang  Yi-Nan Zhu  Man I Lam  Jun-Jie Jin  Hai-Long Yuan  Hao-Tong Zhang  Shi-Yin Shen  Jian-Rong Shi  A-Li Luo  Xue-Bing Wu  Yong-Heng Zhao  Yi-Peng Jing 《天文和天体物理学研究(英文版)》2019,(8)

We present optical luminosity functions(LFs) of galaxies in the~(0.1) g,~(0.1) r,~(0.1) i bands, calculated using data in~40 deg~2 sky area of the LAMOST Complete Spectroscopic Survey of Pointing Area(LaCoSSPAr) in the Southern Galactic Cap. Redshifts for galaxies brighter than r = 18.1 were obtained mainly with LAMOST. In each band, LFs derived using both parametric and non-parametric maximum likelihood methods agree well with each other. In the0.1 r band, our fitting parameters of the Schechter function are φ_*=(1.65 ± 0.36) × 10~(-2) h~3 Mpc~(-3), M_*=-20.69 ± 0.06 mag and α =-1.12 ± 0.08,which agree with previous studies. Separate LFs are also derived for emission line galaxies and absorption line galaxies. The LFs of absorption line galaxies show a dip at~(0.1) r ~18.5 and can be fitted well by a double-Gaussian function, suggesting a bimodality in passive galaxies.  相似文献   

利用双视角消除太阳矢量磁场观测中的180◦不确定性          下载免费PDF全文

周茹芸  汪毓明  宿英娜  毕少兰  刘睿  季海生 《天文学报》2021,62(4):41

随着"环日轨道器"(Solar Orbiter, SO)的在轨运行,太阳磁场观测进入了双视角遥测的时代.对利用太阳磁场的双视角观测改正矢量磁图中存在的横场(垂直于视线方向的磁场分量) 180°不确定性进行了模拟,首先模拟了对解析解得到磁图的双视角观测,然后利用"日震学和磁学成像仪"(Helioseismic and Magnetic Imager, HMI)在不同时间观测到的一个老化黑子的磁图模拟了双视角观测.发现要改正一个磁图中横场方向的180°不确定性,在观测上只需要另外一个平行于视线方向的磁场即纵向磁场观测的协助.利用HMI的磁场观测模拟,估算显示30°的张角能够改正50 Gs磁场中的180°不确定性.更大的张角虽然更有利于更弱磁场的改正,但是考虑到投影效应的不利影响, 30°左右的张角应该是未来空间设备进行多视角观测太阳磁场的最佳张角.  相似文献   

Quantifying suitable dynamic water levels in marsh wetlands based on hydrodynamic modelling     

Peng Hu  Zefan Yang  Qiande Zhu  Weize Wang  Qin Yang 《水文研究》2021,35(2):e14054

The water level of marsh wetlands is a dominant force controlling the wetland ecosystem function, especially for aquatic habitat. For different species, water level requirements vary in time and space, and therefore ensuring suitable water levels in different periods is crucial for the maintenance of biodiversity in marsh wetlands. Based on hydrodynamic modelling and habitat suitability assessment, we determined suitable dynamic water levels considering aquatic habitat service at different periods in marsh wetlands. The two-dimensional hydrodynamic model was used to simulate the temporal and spatial variation of water level. The habitat suitability for target species at various water levels was evaluated to obtain the fitting curves between Weighted Usable Area (WUA) and water levels. And then suitable water levels throughout the year were proposed according to the fitting curves. Using the Zhalong Wetland (located in northeastern China) as a case study, we confirmed that the proposed MIKE 21 model can successfully be used to simulate the water level process in the wetland. Suitable water levels were identified as being from 143.9–144.2 m for April to May, 144.1–144.3 m for June to September, and 144.3–144.4 m for October to November (before the freezing season). Furthermore, proposed water diversion schemes have been identified which can effectively sustain the proposed dynamic water levels. This study is expected to provide appropriate guidance for the determination of environmental flows and water management strategies in marsh wetlands.  相似文献   

文莱-沙巴盆地深水褶皱冲断带构造变形特征及成因机制          下载免费PDF全文

唐武  赵志刚  张功成  谢晓军  刘世翔  王一博  宋双  王龙  孙瑞  郭佳 《地球物理学报》2018,61(10):4281-4295

为揭示活动陆缘深水褶皱冲断带的特征及成因，本文利用地震和区域地质资料的综合分析，系统阐述了文莱—沙巴盆地深水褶皱冲断带的构造变形特征，并结合盆地演化动力学特点，探讨其构造变形机制及其对深水区油气成藏的影响.研究结果表明，文莱—沙巴盆地深水褶皱冲断带具有"垂向分期、平面分段"的特点，垂向上，以中中新统底界面为界可划分为下部（始新世-早中新世）和上部（中中新世-现今）两套逆冲褶皱冲断体系，其中下部逆冲褶皱冲断带的形成与古南海的俯冲作用密切相关，上部逆冲褶皱冲断带是中中新世以来三角洲前缘重力滑动与苏禄海扩张造成的区域挤压应力远程效应共同作用的结果，且苏禄海扩张造成的远程挤压效应主控平面上南北段褶皱冲断带变形的差异性，导致北段褶皱变形强度大于南段，具有背斜褶皱数量多、褶皱间距离短、逆冲断层倾角陡的特点，南段反之；且晚上新世以来北段深水区地层缩短量大于陆架区伸展量，两者之差为2~6 km，而南段两者相当，仅受三角洲前缘重力滑动影响.整个褶皱冲断带发育断弯、断展、断滑褶皱等3种断层相关褶皱以及叠瓦扇和冲起构造2种逆冲构造组合，是多期NW向挤压应力作用下形成的大型逆冲推覆构造，以前展式向盆地扩展.此外，由于中中新世以来逆冲断层的持续活动，研究区深水褶皱冲断带发育众多构造圈闭，油气成藏条件优越，且南段优于北段，靠近陆坡的近端优于远端，可作为勘探部署重点.  相似文献   

Degradation of Atenolol with Electrochemical Oxidation at Mixed Metal Oxide Electrodes Assisted by UV Photolysis          下载免费PDF全文

Shumin Zhu  Bingzhi Dong  Shiqing Zhou 《洁净——土壤、空气、水》2018,46(4)

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Study of the flood control scheduling scheme for the Three Gorges Reservoir in a catastrophic flood          下载免费PDF全文

Shanghong Zhang  Zhu Jing  Wenda Li  Yujun Yi  Yong Zhao 《水文研究》2018,32(11):1625-1634

The Three Gorges Project is the world's largest water conservancy project. According to the design standards for the 1,000‐year flood, flood diversion areas in the Jingjiang reach of the Yangtze River must be utilized to ensure the safety of the Jingjiang area and the city of Wuhan. However, once these areas are used, the economic and life loss in these areas may be very great. Therefore, it is vital to reduce this loss by developing a scheme that reduces the use of the flood diversion areas through flood regulation by the Three Gorges Reservoir (TGR), under the premise of ensuring the safety of the Three Gorges Dam. For a 1,000‐year flood on the basis of a highly destructive flood in 1954, this paper evaluates scheduling schemes in which flood diversion areas are or are not used. The schemes are simulated based on 2.5‐m resolution reservoir topography and an optimized model of dynamic capacity flood regulation. The simulation results show the following. (a) In accord with the normal flood‐control regulation discharge, the maximum water level above the dam should be not more than 175 m, which ensures the safety of the dam and reservoir area. However, it is necessary to utilize the flood diversion areas within the Jingjiang area, and flood discharge can reach 2.81 billion m³. (b) In the case of relying on the TGR to impound floodwaters independently rather than using the flood diversion areas, the maximum water level above the dam reaches 177.35 m, which is less than the flood check level of 180.4 m to ensure the safety of the Three Gorges Dam. The average increase of the TGR water level in the Chongqing area is not more than 0.11 m, which indicates no significant effect on the upstream reservoir area. Comparing the various scheduling schemes, when the flood diversion areas are not used, it is believed that the TGR can execute safe flood control for a 1,000‐year flood, thereby greatly reducing flood damage.  相似文献