SPATIAL-TEMPORAL CHANGES AND TRENDS OF AGEING IN CHINA     

WANG Wu-yi ZHANG Li LI Hai-rong LI Ri-bang YANG Lin-sheng LIAO Yong-feng 《中国地理科学(英文版)》2005,15(3):200-205

This study focuses on the development stages of ageing and its regional differences in China based on examination of official statistics and documents. The development of ageing in China has experienced three major stages. Firstly, in the 1950s, low coefficient of elderly population （over 65 years） paced up to primary adult type. Secondly, there was a deeply drop of the elderly population because of natural disaster and political factors in the 1960s. Thirdly, from the 1970s to the end of 20th century, the constant increasing of elderly coefficient made China close to elderly society. With statistic data of population, Logistic model is used to simulate the future development of ageing, and two characteristics of development of ageing are presented. Firstly, as for ageing from 2005 to 2050, the elderly coefficient will grow up significantly from 8.48% to 16.30%. Secondly, after 2025, the increasing rate of elderly coefficient will slow down gradually. The regional differences of elderly population in China can be summarized as follows： 1） the eastern China possesses higher elderly coefficient and huger elder population than the western China; 2） about 47.4% of municipalities and provinces in the eastern China become elderly especially Shanghai, Zhejiang Province, Jiangsu Province, Beijing, Tianjin and Shandong Province; 3） ageing intensity is higher in rural area than urban area but getting close each other, and there are more elderly people in rural area than in urban area. Therefore, these will arose aged care problems, and it becomes important issue to establish the social security system in rural areas as soon as possible for elderly people.  相似文献   

Urban Spatial Restructuring in Transitional Economy —— Changing Land Use Pattern in Shanghai   总被引：2，自引：1，他引：1  

XU Jiangang LIAO Banggu SHEN Qing ZHANG Feng MEI Anxin 《中国地理科学(英文版)》2007,17(1):19-27

For almost three decades, China has been undergoing significant transition from a planned economy to a market economy. Fast-paced economic growth and urbanization, interacting with market-oriented reforms in land re- sources allocation, have caused profound spatial restructuring of Chinese cities. This paper examines urban expansion and land use reconfiguration in Shanghai’s central city from 1979 to 2002, with a special focus on the effect of the adoption of the land-leasing system in 1988. The empirical research, which employs GIS-based spatial analysis tech- niques to explore land use data for multiple years, indicates fundamental changes in the spatial characteristics of urban development in Shanghai after this important land policy reform.  相似文献   

异步时序设计亚稳态的消除方法     

丁炜  廖成旺  邓涛  谭耀银 《大地测量与地球动力学》2007,27(Z1):103-105

提出一种基于异步比较法产生空满标志位，并利用锁存器实现标志位与时钟同步的FIFO，同时还给出了相应的Verilog HDL代码。该方法能提高时钟频率,节约版图面积。  相似文献   

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廖成旺  邓涛  丁炜  谭耀银  陈亮 《大地测量与地球动力学》2007,27(1):91-95

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QUANTITATIVE ANALYSIS AND FRACTAL MODELING ON THE MOSAIC STRUCTURE OF LANDSCAPE IN THE CENTRAL AREA OF SHANGHAI METROPOLIS     

XUJian-hua AINan-shan CHENYong MEIAn-xin LIAOHong-juan 《中国地理科学(英文版)》2003,13(3):199-206

The mosaic structure of landscape of the central area of Shanghai Metropolis is studied by quantitative methods of landscape ecology based on Remote Sensing (RS) and Geographic Information System (GIS) in this pa-per. Firstly, landscapes are classified into eight categories: residential quarter, industrial quarter, road, other urban landscape, farmland, village and small town, on-building area, river and other water bodies (such as lake, etc.). Sec-ondly, a GIS is designed and set up based on the remote sensing data and field investigation, and a digital map of landscape mosaic is made. Then the indexes of diversity, dominance, fragmentation and isolation, and fractal dimen-sion of each type of landscape in different periods are calculated by using spatial analysis method of GIS. With refer-ence to the calculated results, a series of relative issues are discussed.  相似文献   

An equal area conversion model for rasterization of vector polygons     

Zhou  ChengHu  Ou  Yang  Yang  Liao  Qin  Biao 《中国科学:地球科学(英文版)》2007,50(1):169-175

Vector-raster conversion is one of the classic research topics in the field of Geographical Information Systems (GIS). The algorithms commonly used in GIS are devoted to maintaining the vector polygons’ shape characteristics, but neglect the gain and loss of a polygon’s area, which is another important attribute. This paper proposes an equal-area conversion model based on an area compensation optimization principle. According to the topological relationship among polygons and boundary grids, a neighborhood compensation principle was adopted to assign the attributes of boundary grids and a global optimization algorithm was developed to minimize area distortion in the whole data set. Two experiments were designed and the results indicated that this algorithm not only guaranteed the area error is as small as possible, but also has the advantage as being adaptive to polygon shape and spatial structure.

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Paleoenvironmental Characteristics of Paleogene Lacustrine Source Rocks in the Western Bozhong Sag, Bohai Bay Basin, China: Evidence from Biomarkers, Major and Trace Elements     

WANG Xiang  LIU Guangdi  SONG Zezhang  SUN Mingliang  WANG Xiaolin  WANG Feilong  CHEN Rongtao  GENG Mingyang  LI Yishu 《《地质学报》英文版》2024,98(1):220-240

The organic matter (OM) enrichment mechanisms and depositional environment characteristics of lacustrine source rocks in the western Bozhong Sag, Bohai Bay Basin in Northeast China remain controversial. To address these issues, based on Rock-Eval pyrolysis, kerogen macerals, H/C and O/C ratios, GC-MS, major and trace elements, the Dongying Formation Member (Mbr) 3 (E3d3), the Shahejie Formation mbrs 1 and 2 (E2s1+2), and the Shahejie Mbr 3 (E2s3) source rocks in the western Bozhong Sag were studied. The above methods were used to reveal their geochemical properties, OM origins and depositional environments, all of which indicate that E2s1+2 and E2s3 are excellent source rocks, and that E3d3 is of the second good quality. E3d3 source rocks were formed under a warm and humid climate, mainly belong to fluvial/delta facies, the E3d3 sediments formed under weakly oxidizing and freshwater conditions. Comparatively, the depositional environments of E2s1+2 source rocks were arid and cold climate, representing saline or freshwater lacustrine facies, and the sediments of E2s1+2 belong to anoxic or suboxic settings with large evaporation and salinity. During the period of E2s3, the climate became warm and humid, indicating the freshwater lacustrine facies, and E2s3 was characterized by freshwater and abundant algae. Moreover, compared with other intervals, the OM origin of E3d3 source rocks has noticeable terrestrial input. The OM origin of the E2s1+2 and E2s3 are mainly plankton and bacteria. Tectonic subsidence and climate change have affected the changes of the depositional environment in the western Bozhong Sag, thus controlling the distribution of the source rocks, the geochemical characteristics in the three intervals of lacustrine source rocks have distinct differences. Overall, these factors are effective to evaluate the paleoenvironmental characteristics of source rocks by biomarkers, major and trace elements. The established models may have positive implications for research of lacustrine source rocks in offshore areas with few drillings.  相似文献   

Symplectic integrator for general near-integrable Hamiltonian system     

Xinhao Liao 《Celestial Mechanics and Dynamical Astronomy》1996,66(3):243-253

In this paper, following the idea of constructing the mixed symplectic integrator (MSI) for a separable Hamiltonian system, we give a low order mixed symplectic integrator for an inseparable, but nearly integrable, Hamiltonian system, Although the difference schemes of the integrators are implicit, they not only have a small truncation error but, due to near integrability, also a faster convergence rate of iterative solution than ordinary implicit integrators, Moreover, these second order integrators are time-reversible.  相似文献   

ON THE VERTICAL DISCRETIZATION OF ATMOSPHERIC MODELS—PART I:EXISTING PROBLEMS,DATA PROCESSING AND CHOICE OF VERTICAL COORDINATE AND BASIS FUNCTIONS          下载免费PDF全文

廖洞贤  朱艳秋 《Acta Meteorologica Sinica》1997,(2)

Discussions are carried out on the vertical discretization of current atmospheric models.It ispointed out that there exist problems in the integration of the hydrostatic equation and thecomputation of vertical advection,vertical diffusion and so on.Then some possible ways forsolving or alleviating them are suggested.Finally,the choice of vertical coordinate and basisfunctions is discussed.  相似文献   

阻尼正弦项叠加形式估计参数的Cramer-Rao下界     

廖成旺  王建华 《大地测量与地球动力学》2002,22(3):122-126

对于阻尼正弦项叠加形式的参数估计问题，详细推导了关于部分参数的Cramer-Rao下界的精确形式，并具体计算了一阶情况下的表达式。由于阻尼项的存在，此类参数估计问题是做不到渐近一致的。参数的估计精度与阻尼项有关，阻尼项越接近于零，参数估计可能越好。  相似文献