Empirical Analysis of City Contact in Zhujiang （Pearl） River Delta,China     

TONG De  LIU Tao  LI Guicai  YU Lei 《中国地理科学(英文版)》2014,24(3):384-392

In traditional urban geography, city contact research is a classic study element in city research. In general, researchers use the traditional gravity model to characterize the contacts that exist between two cities. The traditional gravity model assumes ideal condi- tions, but these preconditions and their results often do not exist in realistic conditions. Thus, we used a modified gravity model to char- acterize the city contacts within a specific region. This model considers factors such as intercity complementarities, government inter- vention, and the diversity of the transportation infrastructure which is characterized as the transportation distance instead of the tradi- tional Euclidean distance. We applied this model to an empirical study of city contact in the Zhujiang （Pearl） River Delta （PRD） of China. The regression results indicated that the modified gravity model could measure city contact more accurately and comprehen- sively than the traditional gravity model, i.e., it yielded a higher adjusted R2 value （0.379） than the traditional gravity model result （0.259）. Our study also suggests that, in addition to urban-regional and metropolitan development, the complementarities of the basic functions of cities at the administrative and market levels, as well as the corporeal and immaterial levels, play very significant roles in the characterization of city contact. Given the complexity of city contact, it will be necessary to consider more relevant influential fac- tors in the modified gravity model to characterize the features of city contact in the future.  相似文献   

Phylogenomic analysis of transcriptomic sequences of mitochondria and chloroplasts for marine red algae (Rhodophyta) in China   总被引：1，自引：1，他引：0  

JIA Shangang  WANG Xumin  QIAN Hao  LI Tianyong  SUN Jing  WANG Liang  YU Jun  LI Xingang  YIN Jinlong  LIU Tao  WU Shuangxiu 《海洋学报(英文版)》2014,33(2):86-93

The chloroplast and mitochondrion of red algae （Phylum Rhodophyta） may have originated from different endosymbiosis. In this study, we carried out phylogenomic analysis to distinguish their evolutionary lin-eages by using red algal RNA-seq datasets of the 1 000 Plants （1KP） Project and publicly available complete genomes of mitochondria and chloroplasts of Rhodophyta. We have found that red algae were divided into three clades of orders, Florideophyceae, Bangiophyceae and Cyanidiophyceae. Taxonomy resolution for Class Florideophyceae showed that Order Gigartinales was close to Order Halymeniales, while Order Graci-lariales was in a clade of Order Ceramials. We confirmed Prionitis divaricata （Family Halymeniaceae） was closely related to the clade of Order Gracilariales, rather than to genus Grateloupia of Order Halymeniales as reported before. Furthermore, we found both mitochondrial and chloroplastic genes in Rhodophyta under negative selection （Ka/Ks〈1）, suggesting that red algae, as one primitive group of eukaryotic algae, might share joint evolutionary history with these two organelles for a long time, although we identified some dif-ferences in their phylogenetic trees. Our analysis provided the basic phylogenetic relationships of red algae, and demonstrated their potential ability to study endosymbiotic events.  相似文献   

直驱式波浪能转换系统的研究和性能优化     

CHEN Zhongxian  YU Haitao  HU Minqiang 《海洋学报(英文版)》2014,33(9):178-183

A direct-drive wave energy conversion system based on a three-phase permanent magnet tubular linear generator （PMTLG） and a heaving buoy is proposed to convert wave energy into electrical energy. Sufficient experimental methods are adopted to compare the computer simulations, the validity of which is verified by the experiment results from a wave tank laboratory. In the experiment, the motion curves of heaving buoy are with small fluctuations, mainly caused by the PMTLG＇s detent force. For the reduction of these small fluctuations and a maximum operational efficiency of the direct-drive wave energy conversion system, the PMTLG＇s detent force minimization technique and the heaving buoy optimization will be discussed. It is discovered that the operational efficiency of the direct-drive wave energy conversion system increases dramatically after optimization. The experiment and optimization results will provide useful reference for the future research on ocean wave energy conversion system.  相似文献   

Distribution and sources of heavy metals in the sediment of Xiangshan Bay   总被引：2，自引：0，他引：2  

SUN Weiping  YU Jianjun  XU Xiaoqun  ZHANG Weiyan  LIU Ruijuan  PAN Jianming 《海洋学报(英文版)》2014,33(4):101-107

Heavy metals in the surface sediments and sediment core from the Xiangshan Bay, a mariculture base on the coast of the East China Sea, were determined by inductively coupled plasma mass spectrometry(ICP–MS) in order to evaluate their levels and sources. The results showed that the levels of Cu, Pb, Zn, and Cr in the sediments of the bay have been generally influenced by anthropogenic inputs since the founding of the People's Republic of China. In particular, Cu and Zn were polluted to some extent, as evidenced by high enrichment factors. Organic matter, grain size, wastewater discharge, and low energy hydrodynamic environment played dominant roles in the heavy metal enrichment in the sediments. The ratio of terrigenous source to marine biogenic deposit of trace metals in the sediments was calculated, revealing that terrigenous inputs were the main source of Cu, Pb, and Zn, while biological pellets contributed much more to the enrichment of Cr and Cd. Considering the influence of biological sources on the enrichment of Cd and Cr, and the fact that the sediment has been polluted by Cu and Zn, the development of mariculture and discharge of wastewater into the Bay should be restricted.  相似文献   

Transcriptome characterization of Ishige okamurae (Phaeophyceae) shows strong environmental acclimation     

QU Jieqiong  WANG Xumin  CHI Shan  WU Shuangxiu  SUN Jing  LIU Cui  CHEN Shengping  YU Jun  LIU Tao 《海洋学报(英文版)》2014,33(2):20-26

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Transcriptome-wide evolutionary analysis on essential brown algae (Phaeophyceae) in China   总被引：1，自引：1，他引：0  

SUN Jing  WANG Liang  WU Shuangxiu  WANG Xumin  XIAO Jingf  CHI Shan  LIU Cui  REN Lufeng  ZHAO Yuhui  LIU Tao  YU Jun 《海洋学报(英文版)》2014,33(2):13-19

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Variability of Atlantic Meridional Overturning Circulation in FGOALS-g2简   总被引：3，自引：0，他引：3  

HUANG Wenyu  WANG Bin  LI Lijuan  DONG Li  LIN Pengfei  YU Yongqiang  ZHOU Tianjun  LIU Li  XU Shiming  XIA Kun  PU Ye  WANG Lu  LIU Mimi  SHEN Si  HU Ning  WANG Yong  SUN Wenqi  DONG Fang 《大气科学进展》2014,31(1):95-109

The variability of Atlantic Meridional Overturning Circulation （AMOC） in the pre-industrial control experiment of the Flexible Global Ocean-Atmosphere-Land System model, Grid-point Version 2 （FGOALS-g2） was investigated using the model outputs with the most stable state in a 512-yr time window from the total 1500-yr period of the experiment. The period of AMOC in FGOALS-g2 is double peaked at 20 and 32 years according to the power spectrum, and 22 years according to an auto-correlation analysis, which shows very obvious decadal variability. Like many other coupled climate models, the decadal variability of AMOC in FGOALS-g2 is closely related to the convection that occurs in the Labrador Sea region. Deep convection in the Labrador Sea in FGOALS-g2 leads the AMOC maximum by 3-4 years. The contributions of thermal and haline effects to the variability of the convection in three different regions [the Labrador, Irminger and Greenland-Iceland- Norwegian （GIN） Seas] were analyzed for FGOALS-g2. The variability of convection in the Labrador and Irminger Seas is thermally dominant, while that in the colder GIN Seas can be mainly attributed to salinity changes due to the lower thermal expansion. By comparing the simulation results from FGOALS-g2 and 11 other models, it was found that AMOC variability can be attributed to salinity changes for longer periods （longer than 35 years） and to temperature changes for shorter periods.  相似文献   

Progress in Studies of the Precipitation Diurnal Variation over Contiguous China          下载免费PDF全文

YU Rucong  LI Jian  CHEN Haoming  YUAN Weihua 《Acta Meteorologica Sinica》2014,28(5):877-902

This paper summarizes the recent progress in studies of the diurnal variation of precipitation over con- tiguous China. The main results are as follows. （1） The rainfall diurnal variation over contiguous China presents distinct regional features. In summer, precipitation peaks in the late afternoon over the south- ern inland China and northeastern China, while it peaks around midnight over southwestern China. In the upper and middle reaches of Yangtze River valley, precipitation occurs mostly in the early morning. Summer precipitation over the central eastern China （most regions of the Tibetan Plateau） has two diurnal peaks, i.e., one in the early morning （midnight） and the other in the late afternoon. （2） The rainfall diurnal variation experiences obvious seasonal and sub-seasonal evolutions. In cold seasons, the regional contrast of rainfall diurnal peaks decreases, with an early morning maximum over most of the southern China. Over the central eastern China, diurnal monsoon rainfall shows sub-seasonal variations with the movement of summer monsoon systems. The rainfall peak mainly occurs in the early morning （late afternoon） during the active （break） monsoon period. （3） Cloud properties and occurrence time of rainfall diurnal peaks are different for long- and short-duration rainfall events. Long-duration rainfall events are dominated by strat- iform precipitation, with the maximum surface rain rate and the highest profile occurring in the late night to early morning, while short-duration rainfall events are more related to convective precipitation, with the maximum surface rain rate and the highest profile occurring between the late afternoon and early night. （4） The rainfall diurnal variation is influenced by multi-scale mountain-valley and land-sea breezes as well as large-scale atmospheric circulation, and involves complicated formation and evolution of cloud and rainfall systems. The diurnal cycle of winds in the lower troposphere also contributes to the regional differences  相似文献   

Mean Structure of Tropical Cyclones Making Landfall in Mainland China   总被引：2，自引：0，他引：2       下载免费PDF全文

BAI Lin  YU Hui  XU Yinglong  WANG Yuan 《Acta Meteorologica Sinica》2014,28(3):407-419

The mean kinematic and thermodynamic structures of tropical cyclones （TCs） making landfall in main-land China are examined by using sounding data from 1998 to 2009. It is found that TC landfall is usually accompanied with a decrease in low-level wind speed, an expansion of the radius of strong wind, weakening of the upper-level warm core, and drying of the mid-tropospheric air. On average, the warm core of the TCs dissipates 24 h after landfall. The height of the maximum low-level wind and the base of the stable layer both increase with the increased distance to the TC center;however, the former is always higher than the latter. In particular, an asymmetric structure of the TC after landfall is found. The kinematic and thermodynamic structures across various areas of TC circulation diff er, especially over the left-front and right-rear quadrants （relative to the direction of TC motion）. In the left-front quadrant, strong winds locate at a smaller radius, the upper-level temperature is warmer with the warm core extending into a deep layer, while the wet air occupies a shallow layer. In the right-rear quadrant, strong wind and wet air dwell in an area that is broader and deeper, and the warmest air is situated farther away from the TC center.  相似文献   

Structural Controls on Baolun Gold Mineralization in Hainan Province,South China     

WU Chuanjun  CAI Jianxin  XU Deru  SHAN Qiang  HOU Maozhou  YU Liangliang  HU Guocheng 《地质学报》2014,88(Z2):1683-1684

Please refer to the attachment(s) for more details.  相似文献