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[Objective] The paper aimed to conduct quantitative calculation and localization research on ecosystem services in Chengdu, to understand the strength, spatial differentiation and impact mechanism of ecosystem services, and to provide policy ideas for the evaluation and supply of ecosystem services in rapidly urbanizing regions. [Method] Based on the gradient space theory, a spatial gradient ring and a spatial gradient transect in Chengdu were established to evaluate the value of ecosystem services, spatial differences and coordination were studied by the evaluation model of ecosystem service value, and coordination degree model in 1990, 2000, 2010 and 2020. [Result] (i) During the study period, the value of ecosystem services in Chengdu decreased by 4.737 billion yuan. (ii) The overall ecosystem service value in Chengdu showed a degrading trend, and the ‘center-periphery’ spatial circle structure radiating from the center to the periphery was obvious, mainly expanding in the southeast (ES) direction, and the northwest (WN) direction was the most stable. (iii) Chengdu has an obvious trend of expanding from the center to the two wings in the north-south direction (S) In the east-west direction (H）, the ecosystem service value gradually declined in the central urban area, rapidly declined in some areas adjacent to the city, and the ecological function areas in the outer suburbs were relatively stable. (iv) From 1990 to 2020, the comprehensive coordination degree (P) on the gradient spatial transect in Chengdu decreased by 2.43. [Conclusion] (i)The value of ecosystem services and comprehensive coordination degree in Chengdu have obvious spatial and temporal differences and significant influence from the expansion of construction land. (ii）The spatial change direction and location of ecosystem services are consistent with the characteristics of urban expansion. (iii) The overall trend of comprehensive coordination (P) is downward. The construction of spatial ecosystem services has an increasingly significant impact on comprehensive coordination (P). [ABSTRACT FROM AUTHOR]

For the location-routing problem of medical waste treatment centers, this paper proposed a multi-objective optimization model considering the public risk. Firstly, from the perspective of the government, the public and the processing center contractor, this paper established the mathematical model which simultaneously considered the operation cost, public risk and transportation cost.Secondly, according to the characteristics of the constructed model, this paper designed an improved multi-objective salp swarm algorithm to solve the problem. Finally, taking the planning projects of the medical waste treatment center in Chengdu, Sichuan province as an example, this paper verified the feasibility of the model and the effectiveness of the algorithm through the method of comparative analysis. [ABSTRACT FROM AUTHOR]

Traffic flow prediction is an important and challenging task in building smart city. Accurate forecasting requires consideration of spatio-temporal characteristics consisting of multiple influences such as holiday, similar node, and weather. In order to accurately capture the spatio-temporal characteristics of road network intersections, this paper proposed a prediction model based on graph convolutional neural network, temporal algorithm Prophet and Pearson correlation coefficient to achieve accurate prediction of intersection traffic considering spatial structure, similar nodes, holidays and other influencing factors. Firstly, it introduced pearson correlation coefficient to reduce the influence of similar nodes to improve the temporal algorithm for capturing temporal features. Secondly, it used the graph convolution neural network to capture spatial features; Finally, it determined the fusion weights of the graph convolutional network and the temporal algorithm by linear regression to obtain the results of spatio-temporal fusion prediction. This paper finally extracted the intersection traffic data based on the analysis of Chengdu taxi trajectory data and conducted traffic prediction experiments. The results show that the accuracy of the model proposed in this paper is better than that of most existing baseline methods, compared with the T-GCN, ASTGCN, and AGCRN models, the MAE is reduced by 1.623, 0.724, 0.161, respectively, and the accuracy is improved by 0. 144, 0. 068, and 0. 021, respectively, which verifies the effectiveness of the model in traffic intersection flow prediction. [ABSTRACT FROM AUTHOR]

The strategic value of farmland usufruct abandonment is becoming more and more prominent, which makes the practice of exploring farmland usufruct abandonment come into being. It is not only the government’s guidance but also the farmers participation and decision-making that are needed to invigorate the farmland usufruct. In order to investigate the factors that affect the decision of the farmer’s farmland usufruct abandonment, we obtain 607 questionnaire survey and interview data of rural households in 33 villages in Zhengzhou and Zhoukou of Henan Province in April ,2018.This paper uses Logistic regression model to explore influence mechanisms of influencing factors on the individual and family characteristics of farmers, resource endowment, ability of abandoning the farmland usufruct, risk estimation of abandoning the farmland usufruct, and cognitive level, which influence the willingness of farmers to abandon the farmland usufruct from different sample areas (taking total sample as a whole, typical rural and urban-rural interface). The possible endogenous problems are also discussed. At the same time, in order to examine the applicability of the farmland usufruct abandonment in various places, This paper systematically analyzes the intention and mode selection orientation of farmers in the study area under the four simulated scenarios of “Pingluo mode”, “Liangping mode”, “Neijiang mode” and “Chengdu mode”. The results show that: 1) The intention of the farmer's farmland usufruct abandonment is markedly influenced by the farmer’s own situation, resource endowment, ability to abandon the farmland usufruct, risk expectation, and cognitive level. Variables like respondents’ gender, skill status, village cadre experience, land transfer status, distance between the nearest county, perennial place of residence, urban settlement plan, income source differentiation, whether has pension insurance or not ,land importance perception and legal cognition are significantly affecting the willingness of rural households to abandon farmland usufruct. Variables such as the level of education, the total number of families, the degree of expected risk, and the willingness to plant land have a significant negative impact on the willingness of farmers to abandon farmland usufruct. Farmers with better family conditions, poor resource endowment, high ability to abandon farmland usufruct, low expected risk, high level of cognition have a strong willingness to abandon farmland usufruct which may be the main groups of farmland usufruct abandonment. 2) Under the unbalanced development of the region, the factors affecting the withdrawal of the farmland usufruct of rural households in typical rural and urban-rural areas are not the same. 3) After using the CMP method to control possible endogenous problems, the influence of variable risk level estimation on the willingness of farmers to abandon farmland usufruct is still significant. However, the absolute value of the coefficient has decreased. This shows that if the endogenous problems are not considered, the impact of risk level estimation on the willingness of farmers to abandon farmland usufruct may be overestimated. 4) Farmers in the research area have higher acceptance of farmland usufruct abandonment mode of Neijiang and Liangping, and lower acceptance of the mode in Pingluo and Chengdu. Farmers are most concerned about compensation, matching social security and forms of abandonment. Based on the research conclusions, the paper proposes policy recommendations for optimizing the system of farmland usufruct abandonment from multiple angles. [ABSTRACT FROM AUTHOR]

[ Objective) This paper aimed to the quantification of the detailed ranges and dynamics of the environmental factors of the light, temperature, air and moisture in morel cultivation. ( Methods ] Environmental factors in greenhouses for Morchella importuna cultivation were collected in Chengdu plain area using Internet of Things (IoT) technologies. Illumination intensity, air temperature, air relative humidity, oxygen percentage in the air, carbon dioxide concentration in the air, soil temperature and soil water content were recorded every ten mi nutes, in greenhouses with different layers of sunshade-net. Fluctuation models in 24-hour cycle were established for the environmental fac tors at different stages. [ Results] The sunlight in the greenhouses showed a dynamic that indirectly regulated the fluctuating features of the ox Oxygen percentage, relative humidity and temperature in the air, while the average illumination intensity in the greenhouse with the highest mo rel yield were about 2500 - 3500 ks at the noon of sunny days. Sunshade-net effectively prevented over-heating during daytime and over-chill ing during night., diminishing the occurrence of extreme values of air temperature and soil temperature, whereas the cumulative temperatures of the air and the soil, as well as the cumulative values of the relative humidity. oxygen percentage and carbon dioxide concentration in the air, and the soil water content, showed no significant difference between the regimes of different sunshade net layers. The effects of the sunshade-net layers were attenus ting the fluctuations of the environmental factors, The air tem perature was either higher than or similar to the soil temperature during the fruiting stage. (Conclusion) Field conditions ideal for morel cultivation were summarized from the analytical results of the environmental factors, for the reference of field management of morel cul tivation in plain area of southwestern China, which further provided some inspirations for the engineers hoping to develop factory-mode tech nologies of morel production. [ABSTRACT FROM AUTHOR]

Leisure tourism will be the future trend of tourism consumption, and leisure tourism resources are the carrier and foundation for the development of leisure tourism industry. Based on the POI data of Chengdu's leisure tourism resources, this paper aimed to analyze the spatial pattern and its influencing factors of leisure tourism resources in the city. We explored and analyzed the spatial distribution of leisure tourism resources using methods including Nearest Neighbor Hierarchical Clustering Analysis, Ripley's K function and Geographic Detector. The results show that: (1) The distribution pattern of Chengdu's leisure tourism resources is featured by central agglomeration and peripheral dispersion. The recreational, cultural, special and natural leisure tourism resources show the layout characteristics based on traditional business districts, cultural centers, green parks and natural attractions respectively. (2) There are different types of leisure tourism resources in terms of spatial scale. The largest spatial scale presents recreational and entertainment features, followed by special and cultural features, and the smallest one exhibits natural features. (3) Distance from the city center, tourist density, street vitality, resident density, resource endowment, road density, etc. are important factors influencing the spatial distribution of leisure tourism resources in the study area. (4) Among the influencing factors, the distance from the city center and the density of tourists and residents are the dominant factors; resource endowment and street vitality are the driving factors; road density, distance from main road and regional economic level are the predisposing factors; government behaviors and major events are the adjustment factors, and all these four factors form the spatial distribution pattern of leisure tourism resources in Chengdu. [ABSTRACT FROM AUTHOR]

[Objective] This paper aimed to investigate the variation characteristics of soil nutrients of cultivated land at different elevation in the transition zone between plain and mountain of Chengdu. [Method] Pengzhou city as the study area was chosen, 1142 topsoil samples at different elevation were collected, and the nutrient data were analyzed with traditional statistics, correlation analysis, variance analysis, semi-variogram model optimization and Co-kriging interpolation. [Result] The correlation relationship between available potassium(AK), soil organic matter(SOM) and elevation were overwhelmingly positive, and the correlation relationship between alkali-hyclrolyzable nitrogen(AN), available phosphorus(AP) and elevation were overwhelmingly negative. The content of AN and AP decreased with elevation increasing and then obviously rebounded at the area above 913 m, the content of AK and SOM increased with elevation. The area with relatively low content of AN, AP and SOM was mainly concentrated in the zone of the most transitional elevation. [Conclusion] The result of this study could be helpful for the improvement of the productivity of cultivated land, soil utilization and protection in the transition zone between plain and mountain of Chengdu, which was of great significance for promoting the sustainable utilization of the resource of cultivated land and ensuring southwest China’s grain security. [ABSTRACT FROM AUTHOR]

[Objective] Eucalyptus globulus, E.grandis and E.robusta are green plants widely cultivated in Chengdu, and this paper aimed to exploit the utilization potential of Eucalyptus resources. [Method] The essential oils from three Eucalyptus species leaves were extracted by using the modified steam-distillation extraction method, and the chemical components were determined by gas chromatography-mass spectrometry（GC-MS）. The effects of the essential oils on proliferation of human hepatoma cells（SMMC-7721） in vitro was studied by 3-（4, 5-dimethyl-2-thiazolyl）-2, 5-diphenyl-2-H-tetrazolium bromide（MTT） assay. [Result] The oil yields of globulus, E.grandis and E.robusta were 3.67 %, 1.21 % and 0.43 %, respectively. The essential oil of E.globulus, E.grandis and E.robusta contains 34, 34 and 31 components. A total of 17 components, such as α-pinene, camphene, limonene, eucalyptol, fenchol, campholenal, borneol, carvone, alloaromadendrene, caryophyllene and o-cymene, were common components of three essential oils. The two main components were α-pinene and eucalyptol in the essential oil of E.globulus, E.grandis and E.robusta, the relative contents of α-pinene were 17.18 %, 17.89%and 41.91%, respectively;The relative contents of eucalyptol were 59.55 %, 50.49 % and 7.68 %, respectively. Three Eucalyptus essential oil significantly inhibited proliferation of human hepatoma SMMC-7721 cells and human normal liver L02 cells.SMMC-7721 cells were more inhibited than L02 by the essential oil of E.robusta, E.grandis and E.Globulus, with half maximal inhibitory concentration(IC50) values of 4.66, 7.36 and 13.53 μg·mL-1 after 24 hours treatments, respectively. The essential oil from E.robusta had a best inhibiting effect on SMMC-7721 cells. [Conclusion] These results indicated that the chemical components and contents of essential oils from different species of Eucalyptus in the same area were different, and the essential oils of Eucalyptus had the potential to be used as antitumor drugs. [ABSTRACT FROM AUTHOR]

Based on the remote sensing monitoring results of the monthly scale drought in Sichuan Province from July to August 2000-2015(Lu et al.(2017)), the multi-scale characteristics of drought are studied in such a complex topographical area in this paper. The multi-dimensional analysis of the monthly average drought conditions and its evolution trend are carried out based on two-dimensional wavelet analysis in different topographic and geomorphological areas. The wavelet square difference (WSD) is taken as an index, the larger the wavelet square difference is, the richer the structural information is in the study area at that scale, and the greater the intensity of drought effect is. Through the research, it is found that: 1) The WSD of average annual situation of drought conditions is reaching its maximum in the vertical direction (North-South direction), the second in the horizontal direction (West-East direction), and the smallest in the diagonal direction (Northwest-Southeast direction), reflecting the significant spatial differentiation of the drought along the vertical direction of the region. The dominant factor that leads to this phenomenon is the significant vertical gradient of the vegetations. 2) The number and scope of the dominant scales for the annual average drought conditions in different are different. There are 5 dominant scales in the Eastern Sichuan basin, and the scale of 5 040.75 km2 is the most topographic areas in the macro scales. The severe drought and extraordinarily drought grades are dominated by the meso scale at 187.34, 560.08 km2, which is mainly reflected in Chengdu Plain. For the plateau and basin transition zone, there are 3 dominant scales. The macro scale of 2 194.5 km2 is mainly characterized by moderate drought and has a significant vertical differentiation. The meso scales of 160.51 and 418 km2 correspond to severe or extraordinarily droughts, which are mainly reflected in the city and built-up area. For the western Sichuan plateau, there are 2 dominant scales. The macro scale of 9 487.5 km2 is prominently represented in the diagonal direction as the drought-free area where the evergreen coniferous forest and the mixed forest are interlaced in the central part of Ganzi Tibetan Autonomous Prefecture. The meso scale of 637.82 km2 is prominent in the horizontal and vertical directions in area where grassland and mixed forest distributed along in the northwestern of the Tibetan and Qiang Autonomous Prefecture. 3) The number of dominant scales and the prominent scale characteristics of the drought and evolution trend are inconsistent in 3 major topographical and morphological areas. For the Eastern Sichuan Basin, there are 4 spatial scales in the drought aggravation trend area, and the mesoscale scale is dominant, while the drought mitigation trend area is dominated by the macro scale of 5 023.02 km2. For the plateau and basin transition areas, there are mainly 3 scales in drought-increasing trend areas. The dominant scale is also the meso scale, while the mitigation trend area is more prominent with 3 meso scales. There are 4 dominant scales in the drought-increasing trend area of the western Sichuan Plateau, which is dominated by the macro scale. While the drought mitigation trend area is dominated by the meso scale. 4) Although the dominant scales in the evolution trend of drought in different geomorphological areas are different, they have strong consistency in the causes of these scale characteristics, that is, the dominant scale areas of drought aggravation trend show a kind of vegetation decline, while the area of drought mitigation is presented as the increasing trend of precipitation. [ABSTRACT FROM AUTHOR]

To ensure the safety of the urban transit network so as to improve the operation efficiency of the entire traffic network, this paper took the transit network of Chengdu city for instance, it analyzed the invulnerability under random and deliberate attacks based on revealing the network topology. The simulation results show that the node number removed from the network affects the invulnerability little in both random attacks and deliberate attacks on the basis of node degree. At the same time, it finds that the less node number removed from the network, the worse invulnerability the network shows in deliberate attacks based on not only node betweeness but node efficiency. Furthermore, the impacts of deliberate attacks based on node betweeness on the network invulnerability are more remarkable than those based on node degree and efficiency. [ABSTRACT FROM AUTHOR]

To study the impact on house value of distance to stations of west extension line of metro line 2 in Chengdu within 800 meters radius area, this paper surveyed residential real estate data along the urban rail transit stations within 800 meters radius area, selected appropriate characteristics variables, and constructed semi-logarithmic equations and logarithmic equations based on hedonic price model, and then built overall equation and distance interval equation by a single distance variable and distance interval variables, and verified the impact on house value of distance to stations of west extension line of metro line 2 in Chengdu. Result shows that, within 800 meters to the metro stations, house values experience an overall downward trend with the increase of distance to the metro stations, the significance of the impact is high. But based on the different distance intervals, house values have seen a trend of "low in the two ends, high in the middle, declining in the overall". And the degree of impact on house value of distance variables, compare to other major variables (distance to the CBD, developer brand, etc.), is relatively low. [ABSTRACT FROM AUTHOR]