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Table of Content

    20 July 2019, Volume 55 Issue 4
    Obtaining Driving Torques of Space Manipulators Based on Ground Planar Experimental Data of the Manipulator with Air-bearing Support: Modeling and Experimental Verification
    ZHANG Lei, CUI Zhiwu, CHEN Tao, YAO Hongxiang, ZHAO Zhen
    2019, 55(4):  597-602.  DOI: 10.13209/j.0479-8023.2019.006
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    In order to extract the true dynamics of a manipulator in space from the experimental data on ground, gap functions of the joints’ driving torques are deduced by Lagrangian equations between two manipulators with and without air-bearing support. The real driving torques can be predicted by the ground data minus the gap function. Verifying experiments are designed and carried out by a small manipulator with rigid arms.
    Adaptive Functional Network with Thermal Robustness
    LIU Ming, WANG Hongli
    2019, 55(4):  603-608.  DOI: 10.13209/j.0479-8023.2019.038
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    Through the enumeration of the three-node gene regulatory network, the random sampling of the parameter space and the dynamics simulation, the adaptive gene transcriptional regulation networks with thermal robustness (namely temperature compensation) are found. The structural analysis of the thermally robust adaptive networks shows that there are three basic structures that can achieve adaptive dynamics with thermal robustness, and the complex adaptive networks with thermal robustness uses these three networks as the core skeletons. In order to investigate the sensitivity of the adaptability of the three-node adaptive network to the changes of various parameters in the network dynamics, the authors calculate the corresponding control coefficients of each parameter. The clustering analysis of the control coefficients shows that the mechanism of the three-node functional network to achieve thermal robustness is temperature isolation, that is, although all rate parameters in the network are temperature dependent, only the generation and degradation rates of the output nodes deviate significantly from zero and have opposite signs. Most thermal robustness is achieved by the antagonistic balance adjustment of the output nodes. 
    Time Marker and Quantitative Measurement of Budding Yeast Cell Cycle
    ZHANG Zhiwen, LI Fangting
    2019, 55(4):  609-614.  DOI: 10.13209/j.0479-8023.2019.050
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    The budding yeast strains containing the CDC10-mCherry and SPC42-mCherry were constructed as a reporter system for different phases in the yeast cell cycle process. According to the generation and disappearance of bud neck (CDC10-mCherry) and the duplication and separation of spindle polar body (SPC42-mCherry), the durations of G1 phase, S phase, Early M phase and Late M phase in the yeast cell cycle can be quantitatively
    measured. Based on the reporter system, CLB5 (S-phase cyclin)-GFP and CLB2 (M-phase cyclin)-GFP strains were constructed and single-cell observations were performed to verify the stability and accuracy of the reporter system. The reporter system can be used as a background strain to study the time length of different phase in the yeast cell cycle.
    PM2.5 Forecast of Beijing Based on Ensemble Empirical Mode Decomposition and BP Neural Network
    REN Xiaochen, ZOU Silin, TANG Xian, WEI Jun
    2019, 55(4):  615-625.  DOI: 10.13209/j.0479-8023.2019.041
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    A hybrid model with ensemble empirical mode decomposition (EEMD) and BP (Back-Propagation) neural network for next-day forecasting of PM2.5 concentration in Beijing is developed. The results show that the forecast accuracy of the hybrid model is higher than single BP model. The main error comes from the highest frequency component. The input variables of the hybrid model need to contain information about the output variables. The level of pollutant concentration in the early stage has great influence on the prediction result of the models.
    Analysis of Precipitation Characteristics and Its Causes in Central Yunnan City
    HE Ping, LI Jinxiao, FU Yongmei, LIU Shuhua
    2019, 55(4):  626-634.  DOI: 10.13209/j.0479-8023.2019.040
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    Basing on the nearly 50-year precipitation data of 4 major city (Kunming, Qujing, Yuxi, Chuxiong) in urban agglomeration of central Yunnan, this paper analyzes the variation of precipitation in annual, seasonal, and monthly time scale by using methods including the statistical analysis, the wavelet analysis, accumulative leveling method, and the grey relational analysis. The result shows that the average precipitation in past 50 years is 928.1 mm. The trend of precipitation is declining, and a mutation appears in 2009. Besides, precipitation has a dry and wet season in these region, and the wet season is between May and October but the dry season is between November and April of next year, There are more precipitation in the rainy season and less precipitation in dry season. The maximum of precipitation (184.0 mm) appears in July, but the minimum of precipitation (13.8 mm) appears in December. According to the wavelet analysis, the change of annual precipitation is about 22 years, the summer precipitation has a 19-day increase-decrease cycle with more precipitation and smaller variation, and the winter precipitation has a 20-day increase-decrease cycle with less precipitation and larger variation. The grey relational analysis show that the temperature and the specific humidity are dominant natural factors, and the population and the city size are dominant human factors. Besides, the natural factors play greater role than the artificial factors.
    Seafloor Deformation Monitoring Based on Tiltmeters for Natural Gas Hydrate Production
    ZHANG Xin, ZHANG Hongliang, ZHOU Lei, HE Tao, LIANG Qianyong, DONG Yifei, HE Chuan
    2019, 55(4):  635-642.  DOI: 10.13209/j.0479-8023.2019.054
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    We present and establish a seafloor deformation model for gas hydrate exploitation in the sea area based on Okada’s linear elasticity theory. The seafloor deformation field is simulated by using high precision tiltmeters, and the model parameters are inverted by simulated annealing method. The results show that the accurate information of dip, azimuth and volume of hydrate dissociated zone can be obtained by tiltmeters. The test results at different noise levels show that the model parameter inversion method has good anti-noise performance. In addition, the feasibility of tiltmeter monitoring in practical application is analyzed according to the hydrate exploitation test in Shenhu area of South China Sea in 2017, and the results show that the type of decline in production has advantages in seabed stability.
    Research of Crustal Stress Simulation Using Finite Element Analysis Based on Corner Point Grid
    LIU Yuyang, LIU Shiqi, PAN Mao, LEI Zhengdong
    2019, 55(4):  643-653.  DOI: 10.13209/j.0479-8023.2019.020
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    The development of stress finite element analysis approach based on 3D corner-point grid can establish accurate crustal stress field. Firstly, corner-point grid is employed to establish the detailed structure and attribute model of reservoir. Secondly, grid conversion algorithm is applied to convert corner-point grid to corresponding finite-element grid. Then, finite element analysis is used to get attribute model based on finite-element grid which reflects the distribution of crustal stress. Lastly, grid conversion algorithm is operated to reverse the attribute model to another format which is based on corner-point grid for subsequent analysis. Thus, the procedure continuity and data consistency has been proved by this approach. Furthermore, real data collected from oilfield X and Y are employed to simulate stress distribution and the validity and accuracy of the proposed approach can be verified by comparison between simulation results and real data.
    Sedimentary Characteristics and Tectonic Segmentation of the Passive Continental Margin of the South Atlantic Ocean
    PAN Xiangru, LI Jianghai, TAO Chongzhi, ZHANG Yu, YANG Menglian
    2019, 55(4):  654-662.  DOI: 10.13209/j.0479-8023.2019.049
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    Seven major sediment centers were recognized based on the Total Sediment Thickness of the World’s Oceans and Marginal Seas (NCEI, NOAA), integrated with the research on the passive margin basins, oceanic plateaus, main transform faults. It could be revealed that the western and the northern parts of the South Atlantic Ocean have much thicker sedimentary than the eastern and the southern parts. The nature of sedimentary and tectonic of the passive continental margin and passive continental margin basins were discussed in four segments of South Atlantic Ocean Margin: equatorial segment, central segment, southern segment and Falkland segment. The Equatorial segment was controlled by large transform faults, where the Triassic salt layer developed. The Aptian salt layer was found in the Central segment, which was the key area of oil and gas exploration. Volcanism deeply influenced the Southern segment with the Seaward Dipping Reflectors.
    Zircon U-Pb-Hf of the Altered Basic Volcanics in Jinzhouying Formation, Lüliang Mountains and Their Significance in Geological Evolution
    CAO Shutai, LI Qiugen, LIU Shuwen, WANG Zongqi, SUN Di, LIU Zhengfu, WANG Xiaoyu
    2019, 55(4):  663-674.  DOI: 10.13209/j.0479-8023.2019.048
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    Lüliang Group, as one of the lithostratigraphic units in the Lüliang Mountains, is composed of the original Lüliangshan Group and the low-grade metamorphic part of the original Chashang Group. This study chooses the altered volcanics belonging to the later Group in Lüliang Group to perform zircon U-Pb dating and Hf isotopic analysis in attempt to determine its formation time. The zircon U-Pb results show two groups of ages: one is the younger with concordant age of 1813±6 Ma (n=7) and the other is the older with 207Pb/206Pb weighted mean age of 2516±31 Ma (n=2). The former is likely to be interpreted as the crystallization age of the volcanic rock, whereas the latter is considered as the captured zircons. Magmatic zircons from the volcanic rock have εHf(t) values of -10.8--2.3, with TDM1 of 2308-2655 Ma, whereas captured zircons have εHf(t) values of +10.0-+13.1. The Hf isotopic signatures of ~2.5 Ga ages signify that their εHf(t) value is higher than the DMM line. U-Pb isotopic and Hf isotopic were analyzed in different domains of zircon, so the obtained Hf isotopic compositions are geologically meaningless mixtures. By contrast, the Hf isotopic signatures of ~1.8 Ga ages signify that their derivation from enriched mantle or depleted mantle contaminated by the crust. These results, together with previous data from the literatures, indicate that ~1.81 Ga magmatic event in the Lüliang area occurred at the post-orogenic setting.
    A Plane Sweep Based Arc Splitting and Polygon Auto-Construction Algorithm
    LIU Yuefeng, SUN Ying, ZHANG Kai, CHEN Yue
    2019, 55(4):  675-682.  DOI: 10.13209/j.0479-8023.2019.037
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    Aiming at the deficiency of traditional polygon auto-construction algorithm in automation and time efficiency, which leads to the insufficiency of commercial GIS softwares’ data processing and spatial-temporal analysis ability, an arc splitting and polygon auto-construction algorithm based on plane sweep idea is proposed. Our algorithm contains three features as follows. First, it is a complete process from intersection testing until polygon construction. Next, it takes full advantage of useful information during intersection testing to realize arc splitting and polygon auto-construction at the cost of little algorithm complexity and computing resources. Finally, it avoids the calculation of nested relation and handles degenerate cases of bridge and dangling edge. The result of experiments proves the proposed algorithm improves efficiency significantly in comparison with traditional algorithms.
    Correlation Study of Low-Altitude Turbulence in Civil Aircraft with Geographical Environmental Factor
    LIU Yuefeng, ZHANG Kai, CHEN Yue, SUN Ying
    2019, 55(4):  683-691.  DOI: 10.13209/j.0479-8023.2019.036
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    Based on the flight quality monitoring big data, statistics were made on the frequency of low-altitude airplane turbulence in various airport areas. Besides, using topographic and meteorological data, we analyzed the correlation between low-altitude airplane turbulence and environmental factors. The results indicate a significant correlation between the low-altitude airplane turbulence and relief amplitude, wind speed, and diurnal temperature range. Also, the spatial difference of the effect intensity of these environmental factors is revealed via geographically weighted regression (GWR) model. The effect intensity of relief amplitude and wind speed increase from northeast to southwest, while the effect intensity of diurnal temperature range increases from southeast to northwest then to northeast. The adjusted R2 of the model is 0.512, which means that the model is very effective. Based on the GWR model, we estimated the risk of low-altitude airplane turbulence on the national scale, and obtained the classification map of the risk. The research results have reference value for airport location and flight safety management.
    River Extraction from High-Resolution Satellite Images Combining Deep Learning and Multiple Chessboard Segmentation
    FANG Haiquan, JIANG Yunzhong, YE Yuntao, CAO Yin
    2019, 55(4):  692-698.  DOI: 10.13209/j.0479-8023.2019.045
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    Using existing methods to extract rivers, especially the small river from remote sensing images, is liable to be interrupted. The combination of deep learning and multiple chessboard segmentation is applied to river extraction from high resolution remote sensing images. Three GF-2 satellite remote sensing images in mountain area, plain and city are used for experiment. The results show that compared with the existing methods, extracted river by proposed method is more continuous. The small rivers accounts for two pixel widths can also be extracted in GF-2 satellite remote sensing images.
    Experimental Study on Ecological Restoration of Degraded Mangroves
    SHEN Xiaoxue, JIANG Lide, TAO Jiawei, YU Lingyun, NIU Zhiyuan, CHEN Zhiteng, LI Ruili
    2019, 55(4):  699-708.  DOI: 10.13209/j.0479-8023.2019.046
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    Taking Kandelia obovata forest as the research object, through periodical replenishment experiment, the improvement of physicochemical properties of the sediments and the plant physiological indicators were used to ascertain the repair effect of water supplemnet on K. obovata. The main results were as follows. 1) The water content, pH, salinity, total nitrogen and organic matter content of sediments in the hydration group were higher than those in the control group, indicating that water supplement improved the nutrient conditions and salinity of the sediment. 2) Water supplementation significantly increased net photosynthetic rate, water use efficiency, and chlorophyll a content (P<0.05), while decreased intercellular CO2 concentration, indicating that water replenishment effectively improved the photosynthesis status and promoted the absorption and transformation of light energy for K. obovata. 3) The maximum fluorescence efficiency (Fv/Fm) of the photosystem II (PS II) in the control group was significantly lower than 0.8 (common threshold), indicating that the degraded K. obovata forest was in the photoinhibitory state, while Fv/Fm was significantly increased after water supplementation (P<0.01), approaching 0.8, indicating a significant improvement in plant health status. 4) Water supplementation improved the photochemical efficiency of the PS II reaction center of K. obovate and significantly improved the imbalance of the excitation energy distribution between the two-optical systems. Moreover, water supplementation also effectively reduced the heat dissipation of the antenna pigments and made the distribution of light energy tend to be efficient, thus increasing the foliar photochemical utilization efficiency. In summary, periodic replenishment is an effective method for the rehabilitation of land-based degraded mangroves.
    Study on the Effect of Two Red-Tide Algae on Mercury Biocondensation and Methylation
    TAO Huchun, YANG Sai, DING Lingyun, ZHANG Lijuan, HE Ningning, ZHANG Yaoyu
    2019, 55(4):  709-716.  DOI: 10.13209/j.0479-8023.2019.047
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    The effect of two red-tide algae of Alexandrium tamarens and Scrippsiella trochoidea on mercury (Hg) adsorption and methylation were investigated. The inhibitory effect of two algae on biomethylation of Geobacter Sulfurreducens (G. sulfurreducens) PCA were demonstrated. The growth of Scrippsiella trochoidea was inhibited under exposure to high concentration of HgCl2 (≥25 μg/L), but less affecting Alexandrium tamarens. Significant adsorption of Hg2+ was observed onto algal cells, whilst negligible amount of methylmercury (MeHg) was produced by two algae directly. FTIR spectra revealed that hydroxyl, carboxyl and amino groups were major binding sites for Hg2+ adsorption. In Hg-algae-bacteria tests, at initial HgCl2 concentration of 10 μg/L, a maximum mercury methylation efficiency of (6.38±0.4)% was obtained by pure G. sulfurreducens PCA culture as a control, but the efficiency reduced to (1.04±0.44)% with G. sulfurreducens PCA and Alexandrium tamarens coexisting, and a much lower efficiency of (0.76±0.05)% was detected with G. sulfurreducens PCA and Scrippsiella trochoidea coexisting. These results suggested that two red-tide algae inhibited mercury biomethylation of G. sulfurreducens PCA.
    Characteristics of Humic Substances in KBD-Affected Region of Changdu, Tibet Based on PARAFAC of Fluorescence
    JIANG Yong, GAO Dingxue, MAO Xuewen, YUAN Hao, HU Mingming, ZHANG Min, GUO Yongzhao, YI Malan, WU Jiang, XU Nan
    2019, 55(4):  717-726.  DOI: 10.13209/j.0479-8023.2019.031
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    Humic substances (HS) in Kaschin-Beck disease (KBD) affected regions were analyzed based on parallel factor analysis (PARAFAC) of fluorescence. Total organic carbon content of HS did not show significant difference between endemic and disease-free areas. Five fluorescence components were identified with PARAFAC, i.e. component 1 (oxidized quinone-like), component 2 (tryptophan-like), component 3 (terrestrial humic-like), component 4 (reduced quione-like) and component 5 (tyrosine-like). Component 1 (p<0.10), component 4 (p<0.05) of aquatic fulvic acid (FA) and component 4 (p<0.10) of aquatic humic acid (HA) in endemic areas showed higher content than disease-free areas. Lager differences of the quinone redox system in aquatic HS between endemic and disease-free areas exhibited in reduced quinone state than that in oxidized quinone state, and in FA than that in HA. HA showed higher content of reduced quinone than FA, but smaller differences between endemic and disease-free areas for its weaker influence on KBD due to extremely low carbon content in drinking water. Sediment HS showed mutual transformation with aquatic HS and higher content of reduced quinone, but no significant differences between endemic and disease-free areas. Intensive understanding on the differences of different fractions of HS and different state of quinone between endemic and disease-free areas can help guiding water improvement project in endemic areas.
    Carbon Emissions by Chinese Economy in 1992–2012: An Assessment Based on EIO-LCA Model
    XU Hongzhou, JI Junping
    2019, 55(4):  727-737.  DOI: 10.13209/j.0479-8023.2019.042
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    This paper constructs a non-competition input-output table, calculates the carbon emission data in China from 1992 to 2012, and analyzes the structural characteristics of its emissions using the EIO-LCA method. The results show that, in general, China’s carbon emission shows a fast rising trend. From the view of department structure, in 1992–2012, the main reason for the growth of carbon emissions in China was the large increase in investment activities, exports and the consumption of urban residents. Investment activities accounted for 55.83% of the total increment of the final demand, and the embodied emissions were mainly in the sector 28 (Construction). Exports accounted for 24.38% of the total final demand. The embodied emissions were mainly concentrated in the manufacturing industry. In general, China’s exports contain higher carbon emissions. The consumption of urban residents accounted for 14.99% of the total increment of the final demand. The embodied emissions were mainly concentrated in sector 25 (Production and distribution of electric power and heat power). In 1992–2012, the growth rate of sector 28, 17 (Manufacture of general and special purpose machinery) and 35 (Other services) was the most obvious, and the three accounted for 60.45% of the total increment. In addition, the carbon emissions of sector 22 (Other manufacturing), 2 (Mining and washing of coal), 5 (Mining and processing of nonmetal ores), 3 (Extraction of petroleum and natural gas) and 8 (Manufacture of textiles) maintained a downward trend.
    Factors Affecting Driving and Car-Purchasing Intentions of the Public in Face of Air Pollution
    WANG Ruoyu, QIN Chuanshen, XU Jianhua
    2019, 55(4):  738-746.  DOI: 10.13209/j.0479-8023.2019.044
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    Drawing upon understanding on “social dilemma”, this study uses online survey data obtained from Beijing residents to explore possible factors affecting the reduction of car-driving and car-purchasing intentions of the public in face of air pollution. Results illustrate that different factors influence individual’s intention to reduce his car-purchasing or car-driving behavior. Individual intention to purchase his first car is most likely affected by the sense of behavior control. However, for those already purchasing his own car, intention to reduce driving is more likely to be affected by individual norms in regard of air pollution. The results suggest that when the public perceive a relatively high cost from environmental behavior, it is difficult for them to make changes even if they have a high sense of behavior control.
    Study on the Change of River Connectivity in Qingshui River Basin from 1980 to 2015
    WANG Kun, XU Chao, WANG Wenjie, WU Xiuqin
    2019, 55(4):  747-754.  DOI: 10.13209/j.0479-8023.2019.043
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    In order to reveal the changing rules of regional water system connectivity under the development of urbanization, this paper takes Qingshui River, a tributary of the Yongding River, as an object, integrates remote sensing imagery, statistical data, and land use data, uses the comprehensive evaluation system for river connectivity, combining the longitudinal connectivity of rivers based on the cumulative effects of barriers and the lateral connectivity of rivers based on the effects of catchment fragmentation, and systematically studies the connectivity changes of water systems in the Qingshui River Basin from 1980 to 2015. The results of the study indicate that based on expert knowledge and combined with the actual situation of the Qingshui River, the barriers of the Qingshui River can be divided into four types: reservoirs, sluice gates, diffuse bridges, and river accumulations. During the study period, the number of barriers continues to increase. In 2000, the number of barriers increases by 10.4% in comparison with 1980 and increases by 23.9% in 2015. From 1980 to 2015, the longitudinal connectivity of the Qingshui River Basin as a whole shows an upward trend. The proportion of the watershed with poor vertical connectivity gradually decreases from 40% in 1980 to 14% in 2015. The areas with increased vertical connectivity are mainly concentrated in the eastern and central parts of the basin, and the connectivity in the southwestern part of the catchment area deteriorates. The overall change in river lateral connectivity is not significant, with the western part of the basin decreasing and the eastern part having improved. From 1980 to 2015, the comprehensive connectivity of the Qingshui River Basin shows an overall upward trend. The proportion of catchments with poor comprehensive connectivity is from 26% in 1980, 17% in 2000 and 17% in 2015, respectively. The areas with increased connectivity are mainly concentrated in the east of the basin, while the connectivity in some areas in the southwest of the basin is always poor. The study reveals the law of connectivity changes in the basin during the urbanization process in Beijing, Tianjin and Hebei, and can provide a scientific reference for regional flood prevention and disaster reduction and river ecological rehabilitation.
    Analysis of Fractal Characteristics of Low Carbon Economic Connectivity in Jing-Jin-Ji Urban Agglomeration
    ZHANG Xuehua, XU Wenbo, ZHANG Baoan, HU Yuying
    2019, 55(4):  755-763.  DOI: 10.13209/j.0479-8023.2019.052
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    Fractal theory and method is applied to analyze the characteristics of low carbon economy connectivity of Jing-Jin-Ji urban agglomeration. Firstly, a “full carbon emission” accounting model is established to calculate the resource consumption and pollution emissions of a single city in Jing-Jin-Ji urban agglomeration in the process of social and economic development. Secondly, the low carbon economic connectivity gravity model and the fractal dimension measurement model are set up to calculate and evaluate the low carbon economic connectivity which centered on Beijing and Tianjin in 2006–2016. There are three main factors in the connectivity gravity model: the population support, GDP output and the road bear of every unit CO2 emission. Furthermore, in order to compare and analyze the difference between the single-point radiation source and the double-point source radiation, the superposition effect of the “Jing-Jin” twin-city radiation is calculated according the principle of source superposition. Thirdly, in order to find out the law of the influence of the spatial distribution of single-point radiation connection intensity on the fractal dimension of the source superposition, the representative years are selected to carry out spatial analysis of low carbon economic connectivity based on the tool of ArcGIS. Finally, Xiong’an New Area is treated as the the third radiation center point to calculate and analyze the three-point source radiation superposition. The fractal dimension calculation and analysis results show that in 2006—2016, the low carbon economic connectivity of the Jing-Jin-Ji urban agglomeration have an inverted U-shaped distribution and the peak appears in 2012, which reflect that Beijing and Tianjin had the best combination of low-carbon economy radiation in the urban agglomeration in 2012. The differences of the fractal dimension of low-carbon economic connectivity are very large between Beijing as the central radiation source and Tianjin as the central radiation source in 2007 and 2014, and the inversion of the fractal dimension appears after the dual source superposition, that is the fractal dimension after superposition is lower than the one with higher radiation capacity in a single source, which means that the twin-city linkage is in low effect. The spatial analysis results of low carbon economic connectivity based on ArcGIS show that in 2012, the results of the “Jing-Jin” twin-city radiation low-carbon economic connectivity source superposition shows a reasonable spatial distribution—gradient order and distinct layers, which is the main reason for the peak value of fractal dimension. When Xiong’an New Area is added as the third central radiation source, the fractal dimension of the low carbon economic connectivity of the Jing-Jin-Ji urban agglomeration can be significantly improved.
    A Study on the Characteristics of Hydrological and Meteorological Droughts in the Lower Nu River
    CHEN Wenhua, XU Juan, LI Shuangcheng
    2019, 55(4):  764-772.  DOI: 10.13209/j.0479-8023.2019.034
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    Taken Mengboluo River, the major tributary in the lower reaches of Nu River as a case, the standard precipitation index (SPI), the standardized precipitation evapotranspiration index (SPEI) and the runoff drought index (SDI) were employed to analyse the change processes of meteorological and hydrological drought based on the monthly precipitation and temperature data of the surrounding meteorological stations from 1966 to 2013, and the monthly runoff of the outlet of the river. The drought indexes value in three reference periods (12 months, 6 months and 3 months) were calculated for each indexes, and the correlation between meteorological and hydrological drought in the basin were also analysed. The results show that there were increasing drought trend, especially, that represented by SPEI-6M and SPEI-3M since 2000s; the drought occurred with multi-scale periodic characteristics. After the mid-90s, the large-scale 25–30 years periodicity gradually moved down to the 10–15 years periodicity. After 2000s, the runoff drought has changed into a weakened drought period over 25 years; but on the mesoscale periodicity with 10–15 years, it is in a transition period from drought to semi humid. Runoff drought is closely related to meteorological drought. Meteorological drought index SPEI-6M could be used to predict annual runoff drought
    Current Applications and Future Potentials of Ecosystem Service Tradeoff Research
    WANG Zhifang, PENG Yaoyao, XU Chuanyu
    2019, 55(4):  773-781.  DOI: 10.13209/j.0479-8023.2019.053
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    Ecosystem service has become a hotspot of research and application since the concept has been put forward, particularly on the tradeoff research, which provides a scientific process for rational decision-making among multiple stakeholders based upon a thorough understanding of relationships among varied ecosystem services. Focusing on practical applications, this paper attempts to sum up specific application and practical values of ecosystem service tradeoff research based upon a detailed review of different investigation approaches and methods. The tradeoffs among ecosystem services can be summed up in four categories: mathematical supply tradeoffs, supply-demand tradeoffs, stakeholder tradeoffs and time/space tradeoffs. The quantitative method used involves objective and subjective measures. The four tradeoff types have been applied to different processes of planning/management practices, including goal setting, core area delineation, ecological compensation and public participation. On the basis of the review, this paper proposes a framework for planning application of ecosystem service tradeoffs while highlighting those existing limitations and providing recommendations for future work including data sharing, method simplification, process crossing, fine scale and the integration of quantitative and qualitative methods to further facilitate the implementation of ecosystem service tradeoff research in practice. 
    Ecological Problems and Protection Countermeasures of Mangrove Wetland in Guangdong-Hong Kong-Macao Greater Bay Area
    YU Lingyun, LIN Shenhui, JIAO Xueyao, SHEN Xiaoxue, LI Ruili
    2019, 55(4):  782-790.  DOI: 10.13209/j.0479-8023.2019.051
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    This paper summarized the experience of the technical, policy and regulatory of the San Francisco Bay Area, New York Bay Area, Tokyo Bay Area and other typical bay areas, induced the ecological environment problems and wetland ecosystem health assessment of the typical mangrove communities in the Guangdong-Hong Kong-Macao Greater Bay Area, and summarized the situation of various pollutants in mangrove wetlands in the Greater Bay Area. Combining the actual situation and future development of the Greater Bay Area, some suggestions for the protection of mangrove wetlands in Greater Bay Area are proposed: 1) mangrove recovery and reconstruction; 2) handling the contradiction between urban construction and ecological protection; 3) strengthening management, publicity and popular science education; 4) further scientific research and protection scientifically; 5) establishing more mangrove wetland nature reserves and strengthening the joint cooperation of the Guangdong-Hong Kong-Macao Greater Bay Area.