Search

Climate change is an important issue for cities today and in the future. At present, China has a large population and complex climate conditions, and cities are also vulnerable to the adverse effects of climate change (Tian, Environ Sustain Dev 6: 153-155 2020). Three-dimensional greening can not only improve the green space system of a city but also have a far-reaching impact on the ecology, image, and economic benefits of a city. Therefore, the study of urban three-dimensional greening is an effective means to deal with climate change strategies. By exploring the influence of traditional greening and three-dimensional greening on Local Climate in Beilin District of Xi'an, Shaanxi Province, the mechanism of three-dimensional greening on urban ecological environment was discussed, and the ecological theory, urban three-dimensional greening theory, and urban local climate zone (LCZ) were referred to. Based on the methods of national climate monitoring, ENVI-met simulation, and field independent measurement, this paper selected a research sample site in the east section of Jianshe Road, Beilin District, Xi'an City, Shaanxi Province, China, and applied ENVI-met software to simulate the thermal stress relationship among building exterior surfaces, plants, and air in the street; quantified the overall ecology of the area; and used measuring instruments. The influence of different types of greening in the base on the site temperature, humidity, CO2 (carbon dioxide) concentration, wind speed, and other climate factors data was, respectively, measured and analyzed. The grid analysis was used to compare the traditional greening and three-dimensional greening, then the numerical differences of each impact factor were sorted out, and the effect of three-dimensional greening on the improvement of urban ecological environment was discussed by analyzing the climate factors with greater impact. The results show that (1) three-dimensional greening plus traditional greening is the most beneficial mode; (2) in the same environment, according to the parameter of 1.5 m from the ground in the model environment, it can be seen that the temperature of the space treated with three-dimensional greening of buildings is reduced by 3.5–3.6 ℃ compared with the control group, the relative humidity is different by 7–8%, the CO2 concentration is reduced by about 5%, and the spatial wind speed is relatively small. (3) When the urban green coverage rate is more than 40%, the improvement of temperature is more obvious, if it reaches 50%, the cool phenomenon in summer can be fundamentally changed. From the perspective of human perception, the PMV index increased by 0.27 on average. This paper discusses and analyzes the three-dimensional greening of urban streets in Beilin District, Xi'an City, Shaanxi Province, China, and studies its influence on urban ecology to different degrees. The conclusions are as follows: Different types of greening have different degrees of influence on urban climate. Meanwhile, the experimental results of this paper show that in cities like Xi'an, Shaanxi Province, China, where summer is hot, adding three-dimensional greening to traditional street greening can significantly improve the environmental microclimate, which is an effective means to cope with climate change, improve the site environment, and stabilize the urban ecosystem. [ABSTRACT FROM AUTHOR]

China's foreign capital R&D network has become a core component of the high-quality development of the national innovation ecosystem. Narrowing the spatial difference in the foreign R&D network is considered an essential strategy to improve China's holistic innovation capability. Previous studies only examined the internal factors of the system while mostly ignoring the quantitative analysis of the spatial differences diffusion. Based on the dissipative structure theory, the current paper demonstrates the construction of positive and negative entropy indexes of foreign capital R&D networks in China. Rested on a survey dataset of 340 foreign R&D institutions in 21 Chinese provinces from 2016 to 2017, this paper analyzes the spatial differences and driving factors of the innovation development of foreign capital R&D networks across the country using the Brusselator model. The results show that China's entire deviation degree of foreign capital R&D networks is small. Still, there are significant spatial differences in the deviation between the entropy value and the ideal status of dissipative structure in foreign R&D networks, with the minor deviation-value areas located in the eastern regions. In addition, the central and western regions where the late-mover layout of the foreign R&D network deviates are far from the ideal status. Among them, the western (i.e., Xi'an and Chengdu) foreign R&D network is significantly better than the central innovation performance. It is found that policy traction of talent advantage and intellectual property rights protection positively impact the negative entropy flow of foreign R&D networks in China, which becomes an influential driving force for the future system equilibrium. The paper concludes with several policy implications to guide China's innovation and ecological optimization of foreign capital R&D networks. [ABSTRACT FROM AUTHOR]

Although the PM2.5 concept was put forward in 1997, it came into Chinese people's sight in 2011, and became a household name in 2013 in China. Previous studies did not involve this indicator, so we need to re-examine and compare the effects of objective air quality data and subjective perception on Life satisfaction (LS). The data were collected from Xi'an, a megacity of Northwest China. Particles smaller than 2.5 μm in diameter (PM2.5), nitrogen dioxide (NO2), sulfur dioxide (SO2), and Air quality index (AQI) acquired from air quality stations were used to calculate pollutant concentrations near the vicinity of subjects' home by Geographical information system (GIS) software. In this paper, the ordinal logistic regression models are used to explain ratings of LS in terms of the objective air pollution data, social and economic variables. The results indicate that the objective air pollution data has significant and negative effects on LS of the surveyed respondents. However, when the subjective perception of air pollution is considered in the regression models, it shows that the subjective perception of air pollution has a significant negative impact on LS, while the effects of PM2.5, NO2, SO2, and AQI on the LS become insignificant. Furthermore, the research significances and policy suggestions are discussed in this paper. [ABSTRACT FROM AUTHOR]

Urban rainstorm and waterlogging occurred more frequently in recent years, causing huge economic losses and serious social harms. Accurate rainstorm and waterlogging simulation is of significant value for disaster prevention and mitigation. This paper proposed a numerical model for urban rainstorm and waterlogging based on the Storm Water Management Model (SWMM) and Geographic Information System (GIS), and the model was applied in Lianhu district of Xi'an city of China. Furthermore, the effects of rainfall characteristics, pipe network implementation level and urbanization level on waterlogging were explored from the perspectives of spatial distribution of waterlogging points, drainage capacity of pipe network and surface runoff generation and confluence. The results show that: (1) with the increase of rainfall recurrence period, the peak of total water accumulating volume, the average decline rate of water accumulating volume and the number of waterlogging nodes increase; (2) optimizing the pipe diameter can shorten the average overload time of the pipe network from the entire pipe network, but for a single pipe, optimizing the pipe diameter may lead to overloading of unoptimized downstream pipeline; (3) the lower the imperviousness, the less the number of waterlogging nodes and average time of water accumulating, and (4) the west, northwest and southwest areas are relatively affected by the imperviousness, only improving the underlying surface conditions has limited influence on waterlogging in the study area. This study can provide reference for urban waterlogging prevention and reduction and pipe network reconstruction. [ABSTRACT FROM AUTHOR]

Local climate zones (LCZs) are an effective nexus linking internal urban structures to the local climate and have been widely used to study urban thermal environment. However, few studies considered how much the temperature changed due to LCZs transformation and their synergy. This paper quantified the change of urban land surface temperature (LST) in LCZs transformation process by combining the land use transfer matrix with zonal statistics method during 2000–2019 in the Xi'an metropolitan. The results show that, firstly, both LCZs and LST had significant spatiotemporal variations and synchrony. The period when the most LCZs were converted was also the LST rose the fastest, and the spatial growth of the LST coincided with the spatial expansion of the built type LCZs. Secondly, the LST difference between land cover type LCZs and built type LCZs gradually widened. And LST rose more in both built type LCZs transferred in and out. Finally, the Xi'an-Xianyang profile showed that the maximum temperature difference between the peaks and valleys of the LST increased by 4.39°C, indicating that localized high temperature phenomena and fluctuations in the urban thermal environment became more pronounced from 2000 to 2019. [ABSTRACT FROM AUTHOR]

The hyporheic zone (HZ) is an active biogeochemical region where groundwater and surface water mix and a potential reservoir for antibiotic resistance genes (ARGs). In this paper, the relative abundance and spatial distribution of ARGs in the HZ media were investigated, taking into consideration both the five speciation of six metals and the local characteristics. The samples of surface water, groundwater, and sediment were collected from Zaohe–Weihe Rivers of Xi'an City, which is a representative city with characteristics of the northwest region of China. Of 271 ARGs associated with 9 antibiotics, 228 ARGs were detected, with a total detection rate of 84%. Sulfonamide and aminoglycoside ARGs were the dominant types of ARGs. The top 6 ARGs and mobile genetic elements (MGEs) in terms of abundance were tnpA-04, cepA, sul1, aadA2-03, sul2 and intI1. The results of principal component analysis (PCA) showed that the distribution characteristics of ARGs were not associated with the sampling sites but with the environmental medias. Similarity in the water phases and significant differences in the water and sediment phases were found. The redundancy analysis (RDA) identified the key factors controlling ARG pollution, including dissolved oxygen (DO) in surface water, total nitrogen (TN) in groundwater, and total organic carbon (TOC) in sediment. In terms of the speciation of heavy metals, we further revealed the promotion effect between ARGs and heavy metals, especially the residual fraction of Ni. In terms of horizontal transfer mechanism, ARGs were significantly correlated with tnpA-03 in water phase and tnpA-04 in sediment. In the three media, intI1 and ARGs all show a significant correlation. These findings showed that hyporheic zone exerted a bottleneck effect on the distribution and transfer of ARGs. [ABSTRACT FROM AUTHOR]

A woman's crown made of fine gilt bronze with refined glass inlay work was excavated from a Sui-Tang tomb called Kunlun M2 in Xi'an, Shaanxi Province, China. Very few female crowns and crown ornaments have been excavated in China thus far, and there has been a lack of systematic research into the technologies used to manufacture them. Importantly, this paper uses the M2 crown to investigate its surface inlays and overall shape, then conducts a comparative analysis of women's crown ornaments of the same type, providing a reference for study of the crown. Non-invasive and micro-destructive analysis including optical microscopy (OM), optical coherence tomography (OCT), micro X-ray fluorescence imagery (XRF), and Raman spectroscopy were applied. These identified the crown's inlays as potash-lime glass, composed mainly of the raw materials: vein quartz or quartzite with potassium nitrate as flux. The inlays were sintered before embedding into gilt copper wire filigree. In comparison to the composition proportions in other ancient potash-lime glass, there is no specific percentage of the raw materials in Chinese potash-lime glass, where the ingredients were likely determined by the experience of the craftsman. Compared with existing research on other crowns and their inlays, this study speculates that the crown dates from the Sui dynasty (581–618) or early Tang dynasty (618–649), was made locally by Chinese craftsmen and belonged to the wife of a high official. [ABSTRACT FROM AUTHOR]

The subterranean termite Reticulitermes aculabialis was firstly described from the soldier caste in 1977 and diagnose from the imago has been difficult due to the lack of description of alate. In this paper, a detailed description of alate for R. aculabialis is presented, including additional data to soldiers. The data are chiefly based on the external morphology of R. aculabialis imago, which has never been described before. All the samples of alates and soldiers were collected in Xi'an, Shaanxi province, China. All of the essential specific characteristics are illustrated for identification purposes. [ABSTRACT FROM AUTHOR]

This study investigated the differences between Chinese female and male university students regarding the relationship between conscientiousness, interpersonal relationships, and social loafing. By analyzing these relationships, this study interpreted how personality, mediators, and gender differences affect social loafing. In total, 827 Chinese university students were recruited from three universities in Xi'an, Shaanxi, China. Students completed an online questionnaire, which included a conscientiousness scale, an interpersonal relationship scale, and a social loafing scale. Structural equation modeling was performed to test the validity of the measurement scales, mediating effects, and group differences. The findings revealed that the relationship between conscientiousness, interpersonal relationships, and social loafing differed between female and male Chinese university students. Interpersonal relationships served as a partial mediator in the relationship between conscientiousness and social loafing among female students. Interpersonal relationships did not play a mediating role in the relationship between conscientiousness and social loafing among male students. We suggest that university administrators should promote cooperation among Chinese university students. [ABSTRACT FROM AUTHOR]

Urban soil organic carbon (SOC) plays an important role in urban ecosystem services. Rapid urbanization and anthropogenic disturbances have created complex and dynamic land-use patterns and heterogeneous urban landscapes, however, the impact of these patterns on the spatial distribution of soil organic carbon density (DSOC) remains unclear. This study investigated SOC using a spatial sampling method from 213 sites in Xi'an City Ring Expressway, China. The results showed that the DSOC ranged from 1.79 to 4.93 kg m−2, with a mean of 3.31 kg m−2, and the value of Dsoc was decreased from city center toward suburb with a significant spatial heterogeneity. The DSOC varied with land-use types, being higher in parks, transportation, commercial, and public lands than in industrial, agricultural, parking, and construction lands. The Dsoc was positively related to population density, normalized difference impervious surface index, road density, and landscape shape index, while negatively to aggregation index and patch richness density. Overall, the urbanization of Xi'an City has strongly affected the soil C stocks, and the capacity of urban soils to store C was sustainable. These findings lays a scientific foundation for future soil carbon management in urban development. [ABSTRACT FROM AUTHOR]

Under the background of global climate change and rapid development of urbanization, urban extreme occurs more frequently. In consideration of the existing problems in the emergency management decision-making of urban rainstorm and flood disasters in China, this study put forward the decision-making method of urban rainstorm and flood disaster emergency management based on similar cases analysis method. Based on the evolution process of urban waterlogging disaster, the problem attribute system of urban rainstorm and flood disasters was established. The case-based reasoning (CBR) method was used to calculate the global similarity to determine the best historical case. The case-based decision theory (CBDT) method was used to calculate the comprehensive utility value of alternative cases to determine the optimal alternative cases. The empirical analysis was took in Xi'an city, one of the national center cities of China. Results show that the CBR method was used to obtain the highest similarity of historical case P3, which is 0.481. The CBDT method was used to calculate the high similarity of historical cases P3 and P4 to form the similar case set, with the similarity of 0.820 and 0.851, respectively. Combined with the event development, the comprehensive utility values were calculated. When the decision-maker pays the same attention to the emergency effect and response cost, the comprehensive utility value of P3 and P4 is 0.922 and 0.900, respectively, and P3 is the best reference scheme. By comparison, the latter is more suitable. The results can provide scientific basis for emergency management of urban rainstorm and flood disasters. [ABSTRACT FROM AUTHOR]

The PM2.5-bounded elements were measured in outdoor and indoor from two urban middle schools in Xi'an. The PM2.5 mass was from 42.4 to 283.7 µg/m3 with bounded element from 3.4 to 41.7 µg/m3. Both the particle mass and the bounded elements displayed higher levels compared with previous studies in school environments. The most abundant elements were Ca, K, Fe, S, Zn and Cl both indoor and outdoor in two schools, which accounted for about 90% of the total elements. Strong correlations between indoor and outdoor were obtained along with relative effect from students' and teachers' activities on the indoor distributions between workdays and weekends. There had different indoor/outdoor (I/O) distributions for the two schools. It revealed the main outdoor sources for elements in JT and predominance of indoor sources in HT. The principal component analysis investigated main sources of elements in this study were coal combustion, geogenic dust and industrial emission, even though there displayed differences in the two school classrooms. The health risk assessment showed that the cancer risk for Ni and Pb was below the safe value while As and Cr might pose acceptable potential threat to both students' and teachers' health. The total non-cancer risks of accumulative multi-metals in JT exhibited to be higher than 1, indicating that there existed the potential non-carcinogenic health risks of exposure metals. [ABSTRACT FROM AUTHOR]

Pocket parks, the green infrastructures with small sizes and flexible layouts, are suitable for thermal environment improvement in the urban built-up block with limited green space. To quantify the relationship between pocket parks and the thermal environment in western China, two parks in the built-up block of Xi'an were selected. By field measurement, the cooling effect could be extended 100 m from the park boundary, connecting two parks. Furthermore, the road and greening within the block demonstrate significant influence on the cooling diffusion by regression analysis. Based on ENVI-met simulation, the ratio of the tree and the grass, the layout of the tree and the grass, and the layout of the paving were analyzed at different proportions of greening and paving of the park. Finally, a combination of the daytime physiological equivalent temperature (PET) and nighttime air temperature (AT) was proposed to choose the optimum layouts: the trees concentrated in the center and the pavement with more roads. Results can provide insights for designing pocket parks based on the thermal environment improvement. [ABSTRACT FROM AUTHOR]

Flood control initiated Chinese civilization. Chinese civilization has a long history, and Chinese ancestors invented "aquatic engineering technology" for flood control and water management, including the Fascine body, as early as two thousand years ago. The Fascine body is a structure used to protect the bank and prevent breaching of an ancient Chinese flood control project. Excavation of the Shahe ancient bridge ruins in Xi'an City, Shaanxi Province, China led to discovery of a Fascine body structure. Through 14C dating, fibre, slice observations, infrared spectroscopy, X-ray diffraction, thermogravimetric analyses and SEM energy spectrum analyses of the fascine material, microbes in the structure and the surrounding soil were identified, the dominant microbial community was analyzed, and microbial diseases were controlled in a targeted manner. Research on the fascine bank ruins identified the width and length boundaries of the Shahe ancient bridge, determined the exact age of the Shahe ancient bridge, provided important materials for research on ancient bridges, river embankments and other ruins, and provided important clues for the traffic and layout around Chang'an during the Qin and Han Dynasties of Chinese history. [ABSTRACT FROM AUTHOR]

Complex geological conditions and/or inappropriate shield tunnel boring machine (TBM) operation can significantly degrade both the excavation and safety of tunnel construction. In recent years, the excavation behaviour of shield TBMs has been a popular topic in the literature given the large volume of data automatically collected by modern shields. These datasets provide an excellent opportunity to apply advanced data analysis techniques to improve predictions of shield tunnelling excavation behaviour. In this study, a framework to develop machine learning (ML)-based regression models for predicting the behaviour of an earth pressure balance (EPB) shield machine using tunnelling parameters is proposed. The feasibility of four ML algorithms, namely Linear Regression (LR), Decision Tree Regression (DTR), Support Vector Regression (SVR), and Gradient Boosting Regression (GBR), to predict EPB shield excavation behaviour is explored through their application to a recent tunnelling case history in sandy soils. The results show that the misestimates were primarily attributed to a reduction of screw conveyor rotational speed (SCRS), induced by a lower injection volume, the artificial manipulation of penetration rate (PR), the local variations of total jacking load, and the use of 'breakout' cutterwheel torque (CT). The GBR model provided the best performance, while LR often performs the worst due to its inability to handle highly nonlinear relationships. DTR prevented the overfitting problem by using a lower max depth parameter towards sacrificing its accuracy. The performance of SVR was seriously affected by loss functions. The proposed optimisation scheme that prevents the over-smoothing problem during the STL decomposition elevates further the prediction accuracy. [ABSTRACT FROM AUTHOR]

For mainland China, the primary obstacle in conditional spectrum (CS) based ground motion selection work is that the corresponding seismic hazard disaggregation results were not released for the China national standard GB 18306–2015 "Seismic Ground Motion Parameter Zonation Map", which refers to the fifth-generation seismic hazard map. Therefore, this study firstly constructed a probabilistic seismic hazard map for mainland China using the three level seismicity source models as applied to produce the fifth-generation seismic hazard map. The derived peak ground acceleration (PGA) values in our seismic hazard map were basically consistent with the PGA range bins in fifth-generation seismic hazard map for most of the 34 principal cities considered. Then, a three-dimensional disaggregation scheme was performed for PGA and 5%-damped spectral acceleration (Sa) corresponding to mean return periods of 475 and 2475 years. The results clearly identified the potential source areas and corresponding fault zones that dominate the hazard of the target cities regarding different intensity measures. Based on the magnitude-longitude-latitude disaggregation results of three example cities: Xichang, Kunming, and Xi'an, approximate and exact CS were established with/without considering multiple casual earthquakes and possible strike directions of the potential source areas. The mean exact CS lies between the results of approximate CS using long and short axis GMMs. The conditional standard deviation of exact CS is approximately 1.1–1.5 times larger than the approximate CS for the periods away from the conditional period. For three example cities, hazard consistency of the spectral accelerations of the ground motion realizations were validated for matching exact CS and approximate CS. The results suggested that the geometric mean approximate CS without inflation of standard deviation is a practical choice when the target exceedance rate was not too low. Moreover, for the 34 studied cities, we tabulated the uniform hazard curve and disaggregation results for PGA and Sa values (0.2, 0.3, 0.5, 0.7, 1.0, 1.5, and 2.0 s) at mean return period of 475 and 2475 years (https://github.com/JIKUN1990/China-Seismic-Hazard-Deaggregation-34cities). [ABSTRACT FROM AUTHOR]

This study investigated the construct of paired associate learning (PAL) and its associations with Chinese word writing in kindergarten children. A total of 188 Chinese children (95 boys, mean age = 5.65 years; SD =.34) from [Xi'an], Mainland China in the third year of kindergarten participated in this study. Children were assessed on measures of PAL with four mapping conditions (i.e., visual-verbal, verbal-verbal, visual-visual, and verbal-visual), executive functioning (EF) of working memory and inhibitory control, visual-motor integration (VMI), phonological awareness, orthographic knowledge, Chinese word reading and Chinese word writing. Results of path anlyses showed that EF skills uniquely predicted the performance of PAL (except verbal-visual PAL) and VMI was a significant correlate of visual-visual and verbal-visual PAL only. Verbal-visual PAL made a marginal significant contribution to Chinese word writing over and above the effects of age, IQ, phonological awareness, VMI, and Chinese word reading. Furthermore, verbal-verbal PAL showed significant indirect effects on Chinese word writing via word reading. These findings underscore the importance of EF and VMI in explaining the performance of different types of PAL and the different mechanisms of PAL in contribution to Chinese word writing in kindergarten children. [ABSTRACT FROM AUTHOR]

Considering the potential ecological and human health risks of potentially toxic elements (PTEs) in topsoil, it is crucial to determine their concentrations and identify their sources. To improve our understanding of PTE accumulation in peripheral areas of cities, soil samples from different parts of Huyi District, Xi'an city were collected, and the concentrations of As, Pb, V, Cr, Cu, Mn, Co, and Zn were determined through X-ray fluorescence spectrometry. The single pollution index value was used to evaluate the PTE contamination levels. The single pollution index values of V, Cr, Mn, Co, Cu, Zn, As, and Pb were 1.00, 1.78, 0.99, 0.93, 1.45, 1.98, 0.72, and 2.06, respectively. The concentrations of Cr, Cu, Pb, and Zn were significantly higher than the corresponding background values. Compared with those in the downtown area, the single pollution index values of Cr and Zn in the study area were slightly higher. The results of the correlation analysis, cluster analysis, and factor analysis demonstrated that natural sources, traffic emission sources, and comprehensive sources were the primary sources of soil PTEs in the study area. Source apportionment based on the absolute principal component score-multiple linear regression (APCS-MLR) receptor model was performed, and the contribution rates of the PTE sources were determined. The contribution rates of natural sources to V, Mn, Co, and As in the topsoil in Huyi District were 68.16%, 74.16%, 63.54%, and 77.25%, respectively. The contribution rates of traffic emission sources to Pb, Zn, and Cu were 53.48%, 60.93%, and 33.82%, respectively. Comprehensive sources were the main contributors to Cr accumulation, at a rate of 45.60%. Therefore, the emissions of PTEs such as Cu, Pb, Zn, and Cr from certain human activities, such as vehicular activities, industrial production, and agricultural production, should be reduced. [ABSTRACT FROM AUTHOR]