中国高新技术企业分布影响因素的空间异质性与尺度效应     

肖凡  王姣娥  黄宇金  古恒宇 《地理研究》2022,41(5):1338-1351

影响高新技术企业分布的因素往往具有空间非平稳性,然而既有研究对其关注尚少。基于2017—2019年间认定的215791家高新技术企业数据,运用多尺度地理加权回归模型（MGWR）,刻画了中国高新技术企业的空间分布格局,识别了其影响因素的空间异质性与尺度效应,结果表明：① 2019年中国高新技术企业的空间分布呈现出在以“北上广深”为首位中心,以成渝与区域性中心城市为次位中心的高度集聚特征。② 企业内部因素、城市知识创造水平、技术创新水平、创新环境水平和外部连通水平共同影响了高新技术企业的空间分布。③ 影响高新技术企业分布的因素存在空间异质性,公司年龄、高校学生数量、互联网的影响呈现出“东-西”向空间分异格局,专利申请数、高新区、生活设施的正向影响呈现出“南-北”向空间分异格局,高铁的正向影响呈现出“东南-西北”向空间分异格局,研发费用投入对东北地区影响最大,市场化水平对京津冀和珠三角城市群地区影响最大。④ 影响因素存在尺度效应,靠近创新末端的变量具有更大的作用空间尺度。最后,本研究提出相关的政策建议,以期为高新技术产业的发展提供借鉴与参考。  相似文献   

Patterns of Multiscale Temperature Variability over the Eastern and Central Tibetan Plateau During 1960-2008     

SONG Ci  PEI Tao  ZHOU Chenghu  HE Yawen 《Acta Meteorologica Sinica》2013,27(4):521-540

Climate variability is an important inherent characteristic of climate and it varies on all timescales. Through examination of temperature variability on multiple temporal scales at 63 stations over the eastern and central Tibetan Plateau （TP） during 1960-2008, we find decreasing trends in daily and intraannual temperature, especially in cold seasons （autumn and winter）. These changes are more sensitive than those in the eastern China coastal region at the same latitude and indicate an asymmetric change of temperature, with hourly, daily, and monthly trends in cold periods stronger than those in warm periods during the recent years. The variation of interannual temperature is complex, showing an increasing trend in autumn and winter and decreasing trend in spring and summer, which is similar to those in the northern polar region. The changes of multiscale variability of temperature are mainly related to changes of atmospheric water vapor, cloudiness, anthropogenic aerosols, monsoon-driven climate, and some local factors. To find the influences of local conditions on temperature variability, we analyze the effects of altitude, topography, and urbanization. The results show that elevation is strongly and positively related to diurnal temperature range （DTR） and slightly positively related to interannual temperature variability （IVT）, but intraannual temperature variability shows no clear elevation dependency. Topography and urbanization also play important roles in multiscale temperature variability. Finally, strong relationships are observed between temperature variability on each scale and different extreme indices.  相似文献   

Analysing the influences of ENSO and PDO on water discharge from the Yangtze River into the sea          下载免费PDF全文

Jun Peng  Xiangxin Luo  Feng Liu  Zihao Zhang 《水文研究》2018,32(8):1090-1103

The El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) are two important climate oscillations that affect hydrological processes at global and regional scales. However, few studies have attempted to identify their single and combined influences on water discharge variability at multiple timescales. In this study, we examine temporal variation in water discharge from the Yangtze River into the sea and explore the influence of the ENSO and the PDO on multiscale variations in water discharge over the last century. The results of the wavelet transform analysis of the water discharge series show significant periodic variations at the interannual timescale of 2 to 8 years and the decadal timescale of 15 to 17 years. Water discharge tended to be higher during the La Niña–PDO cold phase and lower during the El Niño–PDO warm phase. The results of the cross wavelet spectrum and wavelet coherence analyses confirm the relationship between the interannual (i.e., 2 to 8 years) and decadal (i.e., 15 to 17 years) periodicities in water discharge with the ENSO and the PDO, respectively. As an important large‐scale climate background, the PDO can modulate the influence of the ENSO on water discharge variability. In general, the warm PDO enhances the influence of El Niño events, and the cold PDO enhances the influence of La Niña events. Our study is helpful in understanding the influencing mechanism of climate change on hydrological processes and provides an important scientific guideline for water resource prediction and management.  相似文献   

Roughness scale dependence of the relationship between tracer longitudinal dispersion and Peclet number in variable‐aperture fractures          下载免费PDF全文

Zhi Dou  Zhifang Zhou  Jinguo Wang  Yong Huang 《水文研究》2018,32(10):1461-1475

The relationship between the longitudinal dispersion (D_L) and Peclet number (Pe) is crucial for predicting and simulating tracer through the variable‐aperture fracture. In this study, the roughness of the self‐affine fracture wall was decomposed into primary roughness (relatively large‐scale waviness) and secondary roughness (relatively small‐scale waviness) by a multiscaled wavelet analysis technique. Based on the complete dispersion mechanism (diffusion, macrodispersion, and Taylor dispersion) in the variable‐aperture fracture, three relationships (second‐order, power‐law, and linear relationships) between the D_L and Pe were investigated at large and small scales, respectively. Our results showed that the primary roughness mostly controlled the Taylor dispersion mechanism, whereas the secondary roughness was a dominant factor for the macrodispersion mechanism. Increasing the Hurst exponent and removing the secondary roughness led to the decreasing range of Pe where macrodispersion mechanism dominated the solute transport. It was found that estimating the D_L from the power‐law relationship based on Taylor dispersion theory resulted in considerable errors, even in the range of Pe where the Taylor dispersion mechanism dominated. The exponent of the power‐law relationship increased as the secondary roughness was removed. Analysing the linear relationship between the D_L and Pe revealed that the longitudinal dispersivity α_L increased linearly. However, this linear increase became weak as the Taylor dispersion mechanism dominated. In the range of Pe where the macrodispersion mechanism dominated, increasing the Hurst exponent caused the increase of α_L and the secondary roughness played a significant role in enhancing the α_L. As the Taylor dispersion mechanism dominated, the α_L was insensitive to the influence of multiscale roughness in variable‐aperture fractures.  相似文献   

Multiscale method for long tunnels subjected to seismic loading     

Hai‐Tao Yu  Yong Yuan  Antonio Bobet 《国际地质力学数值与分析法杂志》2013,37(4):374-398

A multiscale method for the dynamic analysis of underground structures is proposed, which involves the concurrent discretization of the entire domain with both coarse‐scale and fine‐scale finite element meshes. The coarse‐scale mesh is employed to capture seismic response characteristics of the integral system, whereas the fine‐scale mesh describes in detail the dynamic response in positions of potential damage or interest. For both the coarse‐scale and fine‐scale meshes to overlap, a bridging scale term is introduced so that compatibility of dynamic behavior between the coarse‐ and fine‐scale models is enforced. Both material and contact nonlinearities are considered in the multiscale model. As an application, the model is used for large‐scale seismic response of a newly built long‐distance shield tunnel. Results show that this multiscale method does not have spurious wave reflections at the fine/coarse interface and does not need filtering procedures, which is an advantage compared with the displacement coupling method. Stress and deformation response in lining segments and their connecting bolts are investigated and analyzed within the fine‐scale model, and the capacity of critical structural components, such as bolts and joints is evaluated. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Multiscale adaptive estimation of the conductivity field using pump test data     

K. K. Lee  J. H. Cushman 《Stochastic Environmental Research and Risk Assessment (SERRA)》1993,7(4):241-253

An inverse problem is posed in terms of log-conductivities which are decomposed into macroscale deterministic and microscale stochastic components. The macroscale and microscale conductivities conceptualize hierarchical, scale-dependent aquifer parameters. A deterministic parameter estimation scheme divides a flow domain into a limited number of macroscale constant conductivity zones. A stochastic microscale parameter estimation scheme is used to obtain fluctuations about the macroscale averages in terms of geostatistical models. Both the macroscale and the microscale conductivities are estimated via maximum likelihood, adjoint-state methodologies. Monte Carlo-type approaches are used to examine the distribution of macroscale and microscale conductivity estimates.  相似文献   

基于第二代Curvelet变换的面波压制(英文)   总被引：3，自引：2，他引：1  

郑静静  印兴耀  张广智  武国虎  张作胜 《应用地球物理》2010,7(4):325-335

针对面波能量强、频率低、视速度低等特点,本文提出了基于第二代Curvelet变换的多尺度、多方向分解的面波压制方法,充分利用Curvelet变换的多尺度、多方向功能,分离出含有面波的尺度和方向然后利用面波与有效波在Curvelet域基本不重叠的特性,进行信噪分离处理。这种方法在实际叠前地震数据的处理中,能够有效压制面波,同时较好地保护有效反射波,特别是反射波的低频分量。文中提出的基于第二代Curvelet变换的去面波方法是一种较好的保幅去噪方法。  相似文献   

利用航磁数据向下延拓得到海面磁场的方法   总被引：3，自引：2，他引：1  

于波  翟国君  刘雁春  黄谟涛 《测绘学报》2009,38(3):0-201

采用航磁数据向下延拓到海面代替船测数据,可提高磁力测量成果的综合利用率.基于多尺度边缘检测理论,研究改善航磁数据向下延拓到海面精度的方法,提出多尺度边缘约束迭代法,并给出模型和实测数据算例.计算结果表明,当航磁数据中噪声水平较大时,利用多尺度边缘约束迭代法可以提高向下延拓的精度,满足三、四级海洋磁力测量的精度要求.  相似文献   

1960—2017年艾比湖流域实际蒸散量与气象要素的变化特征   总被引：1，自引：1，他引：0  

尼格娜热·阿曼太  丁建丽  葛翔宇  包青岭 《地理学报》2021,76(5):1177-1192

传统估算蒸散发的方法大都基于局地尺度,而在生态水文发生剧烈变化的资料稀缺流域背景下,充分考虑流域下垫面的空间变异性的陆面过程模型为流域长时序、大尺度及连续模拟实际蒸散量提供了新途径。以艾比湖流域为研究区,应用可变下渗能力模型（VIC）模拟1960—2017年艾比湖流域的水文过程,探讨研究区值实际蒸散发量的年、月、日时空变化规律,并运用小波分析方法对5个气象要素及研究区实际蒸散发量的模拟值进行多尺度特征分析,结果表明：① VIC在温泉和博乐的径流纳什效率系数（NSE）分别为0.09和0.23,模拟效果较为满意;VIC实际蒸散量的模拟值与理论计算值,R²达0.80,均方根误差（RMSE）为31.76 mm a^-1,NSE为0.32,模拟效果相对较好;② 时间尺度上,艾比湖流域58 a来年际实际蒸散量呈上升趋势,年均实际蒸散量以1.03 mm a^-1的速率递增;月值和日值蒸散量均呈单峰趋势;且年代际变化中5—7月的实际蒸散量在20世纪90年代和21世纪呈现下降趋势,20世纪70年呈现上升趋势,而其余月份无明显变化;③ 空间分布上,艾比湖流域内实际蒸散发量总体上呈现高海拔及其附近地区蒸散强烈,从春季到夏季,强蒸散区由西北向东南转移,年实际蒸散量空间分布与春夏季分布一致;④ 艾比湖流域实际蒸散发量与各气象要素在时频域中均存在1~4个显著性周期,且在一定尺度的周期上,平均风速、平均温度以及日照时数超前于实际蒸散量变化,而年降水量和相对湿度滞后于实际蒸散量变化,受降水影响实际蒸散发1965年和2003年发生1 a周期的“强—弱”转换,受相对湿度影响实际蒸散量在1965年和2008年发生2~4.5 a周期的“强—弱”转换。  相似文献   

A Perspective on the Evolution of Atmospheric Blocking Theories: From Eddy-Mean flow Interaction to Nonlinear Multiscale Interaction     

Dehai LUO  Binhe LUO  Wenqi ZHANG 《大气科学进展》2023,40(4):553-569

In this paper, we first review the research advancements in blocking dynamics and highlight the merits and drawbacks of the previous theories of atmospheric blocking. Then, the dynamical mechanisms of atmospheric blocking are presented based on a nonlinear multi-scale interaction(NMI) model. Previous studies suggested that the eddy deformation(e.g., eddy straining, wave breaking, and eddy merging) might lead to the formation and maintenance of atmospheric blocking.However, the results were specu...  相似文献