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Table of Content

    20 May 2017, Volume 53 Issue 3
    Orginal Article
    Multi-step Reduced Reaction Mechanism Simulation of Hydrogen Supersonic Combustion Process
    Zhongqiu LAN, Tongtian DENG, Jingliang ZHONG, Zhili SUN
    2017, 53(3):  397-404.  DOI: 10.13209/j.0479-8023.2017.050
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    In order to reduce the combustion experiments and improve the scramjet structure design, the supersonic flow and combustion process of hydrogen and air in the scramjet are simulated with the large-scale simulation software Fluent. Firstly the cooling mixed flow of air and fuel in the scramjet is simulated, then supersonic combustion process is simulated with one-step or multi-step reduced chemical reaction mechanism respectively. The simulation results show that when using one-step global reaction mechanism, the fuel can be ignited easily, and the combustion efficiency is also relatively high, but the temperature obtained is higher. Simulation with the multi-step reduced reaction mechanism is closer to the actual combustion experiments, but the fuel may be ignited harder, the flame may easy to destroy during the simulation, and the time of simulation may relatively longer.

    Tibetan Information Entropy and Input Keyboard Design
    Wanmezhaxi, Nimazhaxi
    2017, 53(3):  405-411.  DOI: 10.13209/j.0479-8023.2016.113
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    Based on research and analysis of the Tibetan spelling grammar, a computer Tibetan fast input keyboard layout is described by formalization, and some rules and method of Tibetan keyboard layout are derived. According to the Tibetan character’s frequency statistics, the rules of Tibetan keyboard layout, Dvorak keyboard keystroke convenient index, in order to facilitate memor and consider the similarity in pronunciation of English and Tibetan alphabet, a non-repeated code Tibetan keyboard layout is designed. Finally, it proves that the design of the keyboard layout proposed above is more scientific than the other input methods through the average number of keystrokes.

    Combining Multiple Models and High-Confidence Dictionary
    for Event Nugget Detection
    Yadong CHEN, Yu HONG, Xiaobin WANG, Xuerong YANG, Jianmin YAO, Qiaoming ZHU
    2017, 53(3):  412-420.  DOI: 10.13209/j.0479-8023.2017.005
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    This paper proposes a method that combines multiple models and high-confidence dictionary for event nugget detection. This method introduces dictionary features into maximum entropy model and conditional random fields model respectively, then combines the results of two models. In addition, the lexical length and the length of the dependency path between the trigger and negation or speculation in event realis recognition are considered to improve the accuracy of event realis detection. Compared to the method based on maximum entropy model, the experiment results show that proposed method can get 6.43% gain of F1 in event nugget recognition and 1.69% gain of F1 in event realis recognition.

    Spatial Differentiation and Its Driving Factors of Agricultural Mechanization Level: A Case Study of Hebei Province
    Linnan TANG, Yanpeng WU, Yu LIU, Xiumei TANG
    2017, 53(3):  421-428.  DOI: 10.13209/j.0479-8023.2017.006
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    This paper made a comprehensive discussion about the spatial differentiation, evolution trend, correlation and driving factors of the regional agricultural mechanization level by using TOPSIS method, trend surface analysis, ESDA and GWR model. The results show that Hebei county’s agricultural mechanization level presents obvious spatial directivity and topographical distribution differences in 2013. The agricultural mechanization level develops better in central southeast plain, followed by the northwest plateau, and hilly region relatively worse. There exists a significant spatial autocorrelation characteristic and regional convergence phenomenon. The southern area of Hebei major in HH type, and northern area major in LL type. GWR shows great superiority in explaining the spatial non-stationary of elements, and reveals both positive and negative correlations between farmland scale and plant structure (expect for terrain), which is different from OLS result that all the factors are positive. In the future the government can consider such measures as enhancing the cultivated land scale and proportion of planting structure in the plateau area, considering other factors in the plain area to promote county’s agricultural mechanization level.

    Research of Customer’s Choice Preference for New Energy Vehicles:Based on the Analysis of a Consumer Survey in Shenzhen
    Yongsheng ZHU, Jisong ZHU, Shengwen YU, Guoyu QIU
    2017, 53(3):  429-435.  DOI: 10.13209/j.0479-8023.2017.007
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    Based on the questionnaires of consumers in Shenzhen, and analysis the data with Nested Logit model, the customer’s choice preference was studied. The result shows that different people have different preference of new energy vehicles: younger people prefer HEV; women and high education group prefer PHEV the elder, low income and low education groups prefer BEV. The results provide a reference for government and enterprise to market segmentation and product improvement, which is essential to improve air quality.

    Relationships between Urban Landscape Pattern and Land Surface Temperature: A Case Study of Shenzhen
    Jing ZOU, Hui ZENG
    2017, 53(3):  436-444.  DOI: 10.13209/j.0479-8023.2017.021
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    Using the Landsat TM imagery and land use data of Shenzhen in Oct. 2009, this paper studied the relationship between land use structure and spatial differentiation of thermal environment, by land surface temperature (LST) retrieval, temperature zoning and overlay mapping. Besides, investigation of plots in three temperature partitions and analysis of landscape metrics were also used to study the relationship between landscape characteristics and LST. The results showed that, 1) there were significant variation in both land use structure and spatial pattern of different temperature partition. The landscape of mid-temperature partition was highly fragmented and patch shape was most complex. In cooling-island partition, heterogeneity of landscape was low and patch shape were relatively simple with an aggregated structure. 2) relationships between spatial pattern and LST also differed among the three partitions. The landscape-level configuration metrics were all significantly negatively correlated to LST in heat-island partition , however, they displayed a positive relationship in cool-island partition. 3) In greenspace and water area, several patch-level landscape metrics displayed an inconsistent relationship among three partitions, suggested there existed a threshold character in cooling effect of ecological land uses. Research on relationship between urban landscape pattern and LST can help us understand the influence of the land use pattern on surface thermal environment, and it also provide support for studies about optimization of landscape pattern to ease heat island effect.

    Comparison of Sulfide Removal and Electricity Generation in Microbial Fuel Cells
    Qing LÜ, Baogang ZHANG, Ye LIU, Huipeng LIU
    2017, 53(3):  445-450.  DOI: 10.13209/j.0479-8023.2016.093
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    Comparison of air-cathode single chamber and double chamber Microbial fuel cells (MFCs) for sulfide-containing wastewater treatment was carried out. It was found that sulfide containing wastewater could be treated based on MFC technology with energy recovery. The maximum open circuit voltage of 897.2 mV and 821.7 mV, maximum power density of 340.0 mW/m 2 and 273.8 mW/m 2 , and the coulombic efficiency (CE) of 5.6% and 10.7% were realized in the single chamber and double chamber MFCs, respectively, with influent sulfide 100 mg/L and glucose 812 mg/L. Single chamber MFCs had higher performance in electricity output, but double chamber ones had a higher CE. After 72 hours operation of the single chamber MFCs, sulfide and TOC removal efficiencies reached 75.4% and 17.8%, respectively. Results indicate the feasibility of sulfide removal in MFCs and the cathode resistance is recognized as the main limiting factor in the reported system.

    Integrated Landscape Pattern Optimization in Arid Region:A Case Study of Middle Reaches of Heihe River
    Jijun MENG, Xiaodong WANG, Zhen ZHOU
    2017, 53(3):  451-461.  DOI: 10.13209/j.0479-8023.2017.022
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    Middle reaches of Heihe river was chosen as the study area, and meanwhile the core ecological source was identified by biodiversity service, landscape connectivity and habitat quality, and the ecological resistance surface was built by recessive ecological resistance, comprehensive ecological resistance, topography data and street data. Based on the Minimum Cumulative Resistance Model, the ecological corridor network and ecological nodes were identified and a landscape function regionalization was proposed, finally the landscape pattern was optimized from point, line and surface three levels. The results are as follows. 1) The patches with better habitat quality accounted for only 13.77% of the total area, are mainly composed of wetland, high and medium covered grassland and cultivated land, concentrated distributed in the big ups and downs mountains in southeast and the both sides of the main stream of Heihe River. 2) The main ecological corridor throughout the study area from southeast to northwest, the core ecological source and the main ecological corridors are connected by the subsidiary ecological corridors, adjacent main corridors (or sources) are connected by branch corridors, which is mainly distributed in the east ecological nodes are mainly distributed in the weak parts of ecological corridors. 3) Based on the frequency and spatial distribution feature of the minimum cumulative resistance, the area is divided into ecological buffer area, ecological connected area, ecological transition area and ecological edge area four functional areas, construction strategies aiming at ecological sources, ecological corridors and ecological nodes are proposed. The results can provide feasible scientific guidance for ecosystem management in middle reaches of Heihe River.

    A Cognitive Study on Public Participation in Environmental Impact Assessment of Beijing Residents
    He HUANG, Kebin HOU, Daqing QIU, Nan LI, Zhijie ZHAO
    2017, 53(3):  462-468.  DOI: 10.13209/j.0479-8023.2017.023
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    The cognition of EIA (environmental impact assessment) public participation among Beijing residents was studied through questionnaire, including their understanding degree, positivity of participation, rationality, and the issue they are concerned about most. The statistical result of 1043 valid questionnaires reveals that, currently, Beijing residents’ cognition on EIA public participation is relatively high, as more than half of them understand EIA public participation to a certain extent, showing their positivity or rationality of participation, but there is still much room for improvement. Some specific proposals are raised from two aspects, comment processing and feedback, so as to improve the effectiveness of EIA public participation in feasibility.

    A Study on Bottled Water Consumption: A Bounds Testing Analysis for Guangdong Province
    Jisong ZHU, Yongsheng ZHU, Shengwen YU, Guoyu QIU
    2017, 53(3):  469-474.  DOI: 10.13209/j.0479-8023.2017.024
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    To study the driving factors underlying the bottled water consumption growth, the bounds testing analysis for Guangdong Province between the bottled water consumption and the GDP indexes, the student number and the number of overnight tourist was performed. The results indicated that there existed a long-run relationship between the bottled water consumption and these factors. The subsequent autoregressive distributed lag (ARDL) and error correction model (ECM) analysis concluded that the income level was positively related with the bottled water consumption in the long run and short run. Moreover, the growth of the selected two particular sectors, the education sector and the tourism sector, was also positively related with the bottled water consumption. Additionally, the tourism had a larger influence on the bottled water consumption than the education sector in the long run, and the education sector exhibited some substitutability of bottled water consumption. Therefore, with the increase of the income level and development of the tourism and education sector, the energy problems and other environmental problems behind the bottled water consumption will not be negligible.

    Typical Village Domain Models of Rural Residential Land Consolidation Based on the External and Internal Characteristics of the Complex System
    Yanbo QU, Guanghui JIANG, Ran SHANG, Yu GAO
    2017, 53(3):  475-486.  DOI: 10.13209/j.0479-8023.2017.026
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    From the viewpoint of system theory, on the basis of defining the connotation and elements and attributes of rural residential land consolidation model, the paper explained the system relationship of kernel components and outside influence factors and their action mechanism. In view of the theory of rural regional function and the science of human settlements and significant regional characteristics, taking Pinggu district of Beijing city as an example, the paper explicated the regional function division and functional orientation, analyzed the influence factors of rural life, production and ecological conditions, and depicted the edge characteristics of rural residential consolidation model. From the perspective of external orientation and internal performance, the paper put forward the kernel elements combination of different rural residential land consolidation model, and summed up five typical models and its main points, which were city comprehensive development and town transferring type, advantage industry driven and the center community integration type, modern agriculture leading and internal intensive type, ecological agriculture cultivation and new site reconstruction type, ecotourism mining and former site transforming type, to provide a favorable reference for regional rural residential land consolidation and beautiful countryside construction.

    Migration Distance of Floating Population and Regional Differences of Its Influence on Urbanization
    Jun DAN, Jie YIN
    2017, 53(3):  487-496.  DOI: 10.13209/j.0479-8023.20175.043
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    Based on the county-level floating population data of 2010 sixth national population census, the regional differences of influence of migration distance of floating population on urbanization are focused and analyzed, with the methods of spatial autocorrelation and geographically weighted regression. The results show that: 1) the average rate of short-distance floating population is the largest, followed by the medium-distance floating population, and the rate of long-distance floating population is the least. The migration distance of floating population varies with districts. The rate of short-distance floating population is larger in the central and northeast of China, with rate of medium-distance floating population larger in the minority nationality regions and border regions of west part of China and rate of long-distance floating population larger in the Yangtze River Delta, Pearl River Delta, Jing-Jin-Ji Area and northwest of China. 2) There is a big difference between influence of short-distance floating, medium-distance floating and long-distance floating on urbanization, and it varies with regions. The rate of short-distance floating population is negative relevant with urbanization, and the highly negative relevant areas are mostly located in the mountainous area and provincial boundary area. The rate of medium-distance floating population is positive relevant with urbanization, and the highly positive relevant areas are mainly located in the border area between China’s second and third terrain ladder as well as the southeast hilly region. The areas that the rate of long-distance floating population is negative relevant with urbanization are mainly located in the minority nationality regions, remote and border regions, and in the rest areas the rate of long-distance floating population is positive relevant with urbanization. 3) The areas with higher rate of short-distance floating population match the areas where the rate of short-distance floating population have a strong influence on urbanization. The high-low clustered areas of the rate of medium-distance floating population form the center-periphery structure with the areas where the rate of medium-distance floating population strongly influences urbanization. The areas with higher rate of long-distance floating population mismatch with the areas where the rate of long-distance floating population highly influences urbanization.

    Treatment of Landfill Leachate Using A/O-Coagulation-BDD:Ⅰ. Parameter Optimization
    Yingchun SHAN, Qingwei WANG, Weiyi PAN, Wanzi SHI, Haimei SUN, Weiling SUN
    2017, 53(3):  497-506.  DOI: 10.13209/j.0479-8023.20175.044
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    Landfill leachate was treated by A/O-coagulation-BDD combined processes, and the operation parameters were optimized. The optimal HRT and sludge recirculation ratio was 10.7 days and 3.5 for A/O treatment process. Reaction pH and optimal dose of ferric chloride coagulation treatment was 5.5 and 0.4 g/L. The current density and A/V ratio (anode area/reaction volum) for best performance of BDD was 60 mA/cm2 and 4 m-1. CODCr concentration in raw leachte and final effluent were 13375 mg/L and 60 mg/L, with the removal efficiency of 99.5%. TOC concentration before and after treatment by combined treatment process were 6893 mg/L and 12 mg/L, with the removal efficiency of 99.8%. Ammonia nitrogen was completely removed by the combined treatment processes from 1889 mg/L to 0 mg/L. The contribution of A/O, coagulation, and BDD was 59.0%, 32.9%, and 7.6% for CODCr removal of total CODCr, was 50.5%, 46.1%, and 13.2% for TOC removal, was 84.3%, 2.5%, and 3.2% for ammonia nitrogen removal, respectively.

    Treatment of Landfill Leachate Using A/O-Coagulation-BDD:Ⅱ. Removal Mechanism of the Organic Matters
    Yingchun SHAN, Conghe WANG, Jingmiao WEI, Haimei SUN, Weiling SUN
    2017, 53(3):  507-517.  DOI: 10.13209/j.0479-8023.2017.045
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    Landfill leachate was treated by A/O-coagulation-BDD combined processes, and the organic matters during treatment processes were characterized by UV spectra, fluorescence excitation-emission matrix, GC-MS, and Fourier transform infrared spectra under optimum operating conditions. Aliphatic organic matters, tryptophan-like matters, and some fulvic acid-like organic matters can be easily removed by A/O treatment while humic acid-like organic matters can not. The removal efficiencies of ryptophan-like matters and fulvic acid-like organic matters were better as HRT increasing from 4.0 d to 10.7 d. As sludge recirculation ratio increasing from 3.0 to 3.5, the removal efficiency of ryptophan-like matters was better while the removal efficiency of fulvic acid-like organic matters was worse. Coagulation mainly removed aliphatic organic matters, proteins, and some humic acid-like organic matters, but can’t easily remove fulvic acid-like organic matters, and there were still some aroma organic matter in the effluent. BDD treatment can effectively remove kinds of refractory organic matters.

    NIMBY-Effect Evaluation Method of Urban Municipal Infrastructures
    Fang YANG, Yi HE, Zhijie ZHAO
    2017, 53(3):  518-524.  DOI: 10.13209/j.0479-8023.2017.025
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    From the cause generated by NIMBY (Not in my back yard) effect, the authors analyze the size, nature and distribution of each infrastructure. Taking the distribution of the population, protection zone and maximum impact range as main parameters, this paper constructs the NIMBY-index method to evaluate regional NIMBY effect. Taking Haidian district in Beijing as example, this paper assesses the NIMBY-effect distribution and uses the GIS technology to achieve the NIMBY spatial distribution. The result shows that the NIMBY-effect spatial varies significantly in Haidian District, and the NIMBY-index is high in the south and low in the north, which has a close relationship with regional development planning, NIMBY facilities distribution and population density. The evaluation method can be used to provide guidance for urban planning, construction, management and layout of environmental protection facilities.

    Accumulation Characteristics of Surface Pollutants in Different Urban Land Use Types in Changzhou
    Yan JIANG, Huapeng QIN, Luanhui XIAO, Kangmao HE, Zhijie ZHAO
    2017, 53(3):  525-534.  DOI: 10.13209/j.0479-8023.2017.058
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    In view of the problem that the non-point source pollutants had different accumulation characteristics on urban complex different underlying surfaces, the research took Changzhou central city as an example, collected 64 samples of surface pollutants on residential, industrial, traffic, commercial and cultural lands, tested the contents of SS, ammonia nitrogen and total and dissolved COD, TP, TN of surface pollutants, analyzed the accumulation characteristics of surface pollutants on different urban lands and the seasonal differences among residential and traffic lands. The results showed that the cumulative intensities of pollutants on roads were generally higher than other lands, especially SS and the total COD, with 59004.5 and 11179.7 mg/m2 respectively. The cumulative intensities of dissolved pollutants on commercial lands were highest. The cumulative intensities of pollutants on cultural, residential and industrial lands were low. The cumulative intensities in October 2014 (autumn) and March 2015 (spring) had significant seasonal differences on roads. Compared with autumn, the average cumulative intensities of SS in spring were reduced by 7.7%, while total TN and dissolved COD, TN, TP and ammonia nitrogen were increased by 3.3%, 49%, 85%, 61% and 200%. The cumulative intensities had no seasonal differences on residential lands. The average ratios of grainy to total COD, TP and TN were 86.5%, 85.1% and 71.1%, which indicated that the main pollutants were adsorbed on the particulate matters, and more urban cleaning helped reduce urban non-point source pollution. The average contents of COD and TN per unit mass of particulate matters on commercial lands were higher than that on the other lands with 532.6 mg/g and 17.5 mg/g, while that on roads were lower than that on the other lands with 212.2 mg/g (COD), 0.86 mg/g (TP) and 2.9 mg/g (TN).

    Responses of Leaf Traits to Nitrogen and Phosphorus Additions across Common Species in an Alpine Grassland on the Qinghai-Tibetan Plateau
    Ying LI, Li LIN, Wenyan ZHU, Zhenhua ZHANG, Jinsheng HE
    2017, 53(3):  535-544.  DOI: 10.13209/j.0479-8023.2017.057
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    To investigate species’ resource competition strategies with traits of the leaf economics spectrum across contrasting environments and to examine the effects of nutrient additions on the ranking of species based on their leaf economics spectrum in an alpine grassland on the Qinghai-Tibetan Plateau, five leaf traits (LDMC: leaf dry matter content, SLA: specific leaf area, LC: leaf carbon concentration, LN: leaf nitrogen concentration and LP: leaf phosphorus concentration) were measured for 10 plant common species in all plots. The results showed that N addition significantly increased LN by 9.4% and P addition significantly increased LP by 81.8%. There were significant interactions between N addition and P addition on SLA and LDMC, which increased SLA by 15.3% and decreased LDMC by 10.1%. In addition, there were species-specific responses of leaf traits across multivariate trait space to nutrient additions. The variation in species responses to NP addition significantly changed the species ranking based on the leaf economics spectrum. These results showed that co-occurring species followed a conservative strategy in the infertile environment and an exploitative strategy in the fertilized ones by increasing SLA and leaf nitrogen and phosphorus concentrations. Different species responses to NP addition caused a new species distribution based on the leaf economics spectrum. These results suggest that, before using leaf traits to predict responses of community structure and ecosystem functioning to nitrogen and phosphorus additions, it is necessary to take the species-specific responses into consideration.

    Distribution Pattern and Its Impact Factors of Thorny Shrubs in Mountains of the Beijing-Tianjin-Hebei Region
    Qiuyi WANG, Weichao GUO, Tao WANG, Qian HAO, Chongyang XU, Xu LIU, Yue HAN, Shuang QIU, Hongyan LIU
    2017, 53(3):  545-554.  DOI: 10.13209/j.0479-8023.2017.061
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    To analyze the distribution pattern of thorny shrubs and its impact factors, 460 sample sites were collected in mountains of the Beijing-Tianjin-Hebei region. Results showed that about 60% of sample sites had thorny shrubs, which were mainly the shrub community dominated by Vitex negundo var. heterophylla. In a small number of sample sites, thorny shrubs even became the dominant species. Twenty-four thorny shrub species were mainly from the families Rhamnaceae, Rosaceae and Leguminosae. The most common three species (Ziziphus jujuba, Rhamnus parvifolia and Caragana rosea) are mainly distributed on the gentle sunny and half-sunny slopes in the hilly area with elevation lower than 600 m a.s.l.. Quantitative analysis also showed that light condition and drought were limiting factors for growth of thorny shrubs (especially Ziziphus jujuba). Affected by climate, topography, and community factors together, thorny shrubs can be distributed under different habitats in mountains of the Beijing-Tianjin-Hebei region.

    Copper Supply Risk Identification and Analysis Study in China
    Lin XU, Jinrong TANG
    2017, 53(3):  555-562.  DOI: 10.13209/j.0479-8023.2017.062
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    The paper focuses on the study of the copper supply risk conception and the process of risk identification and analysis in risk management, based on the risk theory. The authors establish a list of China copper supply risk through risk identification, and build up copper supply risk matrix through risk analysis. Based on the risk matrix, the copper supply risk is at a higher level in 2013. The reason is the importance of copper resources in the economy is higher, thus expanding the copper resources supply risk. In addition, social development and environmental regulation of supplying countries also have a great impact on China’s copper supply, yet the political risk and economic risk is relatively moderate.

    Analysis on Temporal-Spatial Change of Vegetation Coverage in Hulunbuir Steppe (2000‒2014)
    Fei PENG, Wenjie FAN, Xiru XU, Xing LIU
    2017, 53(3):  563-572.  DOI: 10.13209/j.0479-8023.2016.124
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    As the core components of Hulunbuir Steppe, Xinbaerhuyouqi, Xinbaerhuzuoqi, Chenbaerhuqi, and Ewenkezuzizhiqi were selected as the key study area. Pixel decomposition model was introduced to retrieve the fraction of vegetation coverage (FVC) utilizing the MODIS NDVI data set, and the time series of vegetation coverage was reconstructed. Then, the temporal-spatial changes of FVC time series for study region over the 15-year period from 2000 to 2014 were analyzed. Especially, the algorithm of checking abnormal-point was also introduced, combining the same period of meteorological data of this area to investigate the interior driving forces between FVC and meteorological factors. The FVC distribution of 2014 showed that the higher level vegetation coverage mainly distributed in the east of study area; on the contrary, the lower level of that mainly distributed in the west of study area. Especially, the lowest vegetation coverage existed in the southwest of the study area. Further study of FVC changes showed that the vegetation coverage of whole study area decreased in the first 10 years, while that increased slowly in the latter 5 years. Additionally, the abnormal points which occurred in green-up and green-end periods had much more significant correlation with temperature; while the abnormal points which occurred from July to August strongly correlated with precipitation.

    Perfectionism and Procrastination: The Moderating Role of Conscientiousness
    Yubo HOU, Shuiyun GU
    2017, 53(3):  573-578.  DOI: 10.13209/j.0479-8023.2017.046
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    Based on the survey of 250 staffs, this study explored the relationship between self-oriented perfect-ionism and procrastination. It is found that self-oriented perfectionism negatively correlates with procrastination and conscientiousness of Big-five plays a moderating role: For people low in conscientiousness, self-oriented perfectionism would significantly decrease the procrastination, while for people high in conscientiousness, self-oriented perfectionism has no effect on procrastination. The results are of great reference value for further under-standing of procrastination, and its influence factors.

    An Assessment with Lidar on the Applicability of Radiosonde Data in Retrieving the Mixing Height in Tibetan Plateau
    Cungui WANG, Chengcai LI, Qianshan HE, Wangshu TAN, Yiqi CHU, Jian LI
    2017, 53(3):  579-587.  DOI: 10.13209/j.0479-8023.2016.102
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    With micro-pulse lidar (MPL) data, the max mixing height (MMH) in the summer of Naqu is retrieved by gradient method. With radiosonde data (twice daily at 08:00 and 20:00) and max potential temperature of Naqu in the corresponding date, MMH is retrieved by parcel method. The intercomparison between MMHs from the different data shows that the result from 08:00 radiosonde data consists well with MPL results, with correlation coefficient 0.85, root-mean-square error (RMSE) 0.30 km, mean absolute error (MAE) 0.25 km, and the t-test (0.95) passed. But the result from 20:00 radiosonde data has larger deviation from MPL results, with the correlation coefficient 0.84, RMSE 0.67 km, MAE 0.54 km and failed in the t-test. Deviation analysis shows that some factors such as the residual mixing layer in 20:00 soundings, some local weather process before the 20:00 launch time and the temporal-spatial variation of the mixing height induced by the thermal convective bubbles or/and the entrainment process may cause the inconsistency in the results. All above lead to the non-availability of the 20:00 radiosonde data in retrieving the mixing height. The character of the diurnal variation of the potential temperature profile will also affect the accuracy of retrieval result, which would produce a higher height from 08:00 data, and some statistical corrections should be used to improve the result.

    Environmental Behavior of Persistent Organic Pollutants (POPs) in Aquatic Ecosystem
    Qiuyuan FENG, Tong WU, Yi WAN, Xueqin LIU, Yong LIU
    2017, 53(3):  588-596.  DOI: 10.13209/j.0479-8023.2017.020
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    This paper reviewed the environmental behaviors of POPs (persistent organic pollutants) in water column, sediment and living organism in aquatic ecosystem. The main results were presented as below. 1) Meteorological factors and physicochemical properties could determine the transmission of POPs in the interface of air-water and water column-sediment, including wind speed, temperature, productivity, dissolved oxygen (DO), particle size and component of sediment. The degradation, sedimentation, resuspension, adsorption and desorption of POPs would also be affected. 2) The categories, molecular structures, molecular size and lipophicity were closely related with the passive diffusion and degradation of POPs. Under different condition, the dominant influence factors would change. 3) Larger growth and biotransformation rate would cause smaller bioaccumulation, while higher lipid content had the opposite effects. 4) Comparing to male individuals, the female ones always had stronger bioaccumulation of POPs. The body size had different effects on bioaccumulation among various species and POPs. The analysis also found that previous studies were always conducted separately and lack of comprehen-sive investigation of POPs behavior in environmental medium and individuals, and the dynamic changes at different temporal and spatial scales were still not clear. Food web is an improtant transfer path for POPs, and in the future, more efforts should be put to explore and understand the complex behaviors of POPs in aquatic food web, especially the benthic, coupled benthic-pelagic and microbial food web.