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Sunken green space is one of the urban rainwater collection facilities, which belongs to Low Impact Development (LID) techniques. It plays a key role in the construction of sponge city, and the amount of runoff collection is usually affected by the area of the sunken green space, the infiltration rate of the soil, and the annual runoff collection rate. To determine the minimum soil infiltration rate of sunken green space considering the annual runoff collection ratio of sponge cities, this paper selects a residential district in Hefei city, China, as the case study. Based on 45 years of precipitation data, the designed rainfall corresponding to annual runoff collection ratios of 75%, 80% and 85% is 21.3 mm, 23.4 mm and 27.5 mm, respectively. The characteristics of rainfall infiltration in sunken green space are analyzed by using the water balance model and runoff yield and conflux model. The results reveal that the soil infiltration rate is 1.16×10−4 cm/s~3.88×10−3 cm/s when the sunken depth is 0.1 m~0.3 m and that the ratio of green space area is 5%~25%. The runoff collection of the reconstructed sunken green space is 2.87 times and 1.98 times that of the nonsunken green space and the nonreconstructed sunken green space, respectively. That is to say, under the comprehensive performance of the sunken depth, sunken green space area, the steady soil infiltration rater of the reconstructed sunken green space cannot be less than the value obtained in this paper. Otherwise, the requirements of annual total runoff reduction ratio of the sponge city cannot be met. Therefore, this study provides references for realizing the ratio of annual runoff collection and sponge city construction in similar urban areas. It can also be applied to optimal selection of sunken green space in some sponge city projects. [ABSTRACT FROM AUTHOR]

The existing prediction methods have complex model application, high requirements for data parameters, and are limited to the prediction of a single observation point. To address this problem, this paper proposes a deep learning-based surface subsidence prediction method. Taking Hefei City of China as the research area, the time-series surface deformation results of this area are obtained by using SBAS-InSAR, and then the SFLA intelligent algorithm and Elman neural network model are combined to predict the surface deformation of key urban areas, and the prediction results are compared and analyzed.The experimental results show that the prediction model proposed in this paper can not only accurately predict a single deformation point, but also predict regional land subsidence, and can be used for auxiliary decision-making of urban spatial planning, early warning of geological hazards and hazard mitigation. [ABSTRACT FROM AUTHOR]

With the development of urban built-up areas, accurately extracting the urban built-up area and spatiotemporal pattern evolution trends could be valuable for understanding urban sprawl and human activities. Considering the coarse spatial resolution of nighttime light (NTL) data and the inaccurate regional boundary reflection on point of interest (POI) data, land surface temperature (LST) data were introduced. A composite index method (LJ–POI–LST) was proposed based on the positive relationship for extracting the boundary and reflecting the spatial-temporal evolution of urban built-up areas involving the NTL, POIs, and LST data from 1993 to 2018 in this paper. This paper yielded the following results: (1) There was a spatial-temporal pattern evolution from north-east to south-west with a primary quadrant orientation of IV, V, and VI in the Hefei urban area from 1993–2018. The medium-speed expansion rate, with an average value of 14.3 km2/a, was much faster than the population growth rate. The elasticity expansion coefficient of urbanization of 1.93 indicated the incongruous growth rate between the urban area and population, leading to an incoordinate and unreasonable development trend in Hefei City. (2) The detailed extraction accuracy for urban and rural junctions, urban forest parks, and other error-prone areas was improved, and the landscape connectivity and fragmentation were optimized according to the LJ–POI–LST composite index based on a high-resolution remote sensing validation image in the internal spatial structure. (3) Compared to the conventional NTL data and the LJ–POI index, the LJ–POI–LST composite index method displayed an extraction accuracy greater than 85%, with a similar statistical and landscape pattern index result. This paper provides a suitable method for the positive relationship among these LST, NTL, and POI data for accurately extracting the boundary and reflecting the spatial-temporal evolution of urban built-up areas by the fusion data. [ABSTRACT FROM AUTHOR]

• A soil-tunnel periodic model with a track slab was proposed based on wave transform. • Train load and its component were mathematically decomposed in the generalised modal space. • Two measures to improve calculation efficiency without loss of accuracy were presented. • Accuracy and efficiency were verified by comparing the results with literature and measurements. The prediction of ground-borne vibrations induced by underground trains in tunnels is advantageous for guiding vibration-mitigation designs. The supporting forces of the fastener acting on the track bed that is induced by the train operation are spatially periodic in the tunnel axis direction. Utilising this feature, this paper proposes a novel periodic tunnel-soil model with a track slab to simulate the propagation of train-induced vibrations. The periodic tunnel-soil model based on wave transformations is briefly introduced, and then the slab beam is solved analytically and combined with the tunnel invert using equivalent springs based on the generalised modal function series. The train load and its single component are mathematically decomposed in a generalised modal space for application to the semi-analytical periodic model. Two measures for further improving the calculation efficiency of the semi-analytical model under the moving train load are presented and discussed in detail. The formulation correctness of this model is ensured by literature verification. Furthermore, an in-situ measurement of the vibration on the tunnel wall and ground surface by the train passage in the Hefei metro is conducted to validate this semi-analytical model. It is demonstrated that the proposed model is accurate and efficient for predicting ground-borne vibrations generated by train loads, thus it has the potential to predict vibration levels at a large number of receiver points around a newly constructed metro line. [ABSTRACT FROM AUTHOR]

This paper proposes a novel aviation CO 2 emissions reduction method by introducing a market-based incentive mechanism. An aviation carbon emissions prediction model is proposed to characterize both the microscopic flight dynamics and the macroscopic air traffic demand trend. Based on emissions prediction, a linear climate response model is applied to evaluate the environmental impact of the aviation carbon emissions. Finally, a market-based framework for aviation CO 2 emissions reduction is established based on a two-phase carbon trading model, which provides a piecewise charge method through emission taxation and cap-and-trade. A case study is carried out to demonstrate the effectiveness of the proposed framework using a real-world dataset from the Hefei Air Traffic Control Zone in China. Three scenarios are defined to describe the possible development speed of sustainable aviation fuel application in the future: not applied, medium-speed development, and high-speed development. The results show that the carbon peak will be reached in 2025 in the high-speed development scenario, when the emission amount and associated environmental impact will be reduced by 23.7% and 22.3%, respectively. Thus, the market-based framework proposed in this paper can effectively reduce aviation CO 2 emissions and mitigate the effects of global warming. • An aviation CO 2 emissions prediction model is proposed considering both microscopic flight dynamics and macroscopic traffic demand. • A more efficient market-based CO 2 emission reduction framework is developed based on a two-phase carbon trading model by means of taxation and cap-and-trade. • Case study shows that the proposed method has a more optimal incentive for CO 2 emission reduction. [ABSTRACT FROM AUTHOR]

To analyze the temporal variation characteristics of PM2.5 concentration and its influencing factors in Hefei, this paper utilizes mixed frequency data of air pollution and socio-economic development from 2013 to 2021, and constructs an adaptive change point detection model and fusion of Lightgbm in Machine Learning Models and LGBNN in multilayer neural networks to examine the change point characteristics and significant factors affecting PM2.5 concentration changes in Hefei. The findings indicate evident periodic oscillation patterns in PM2.5 concentration in Hefei, with a greater number of decreasing variables compared to rising variables in the sequence, and the change points exhibit a distinct "phased" characteristic. Regarding the influencing factors, the feature selection analysis conducted on multiple machine learning models like LGBNN reveals that policy factors exhibit the highest prominence, followed by social economy development, air pollution, and meteorological factors. [ABSTRACT FROM AUTHOR]

Taking the domestic waste reverse logistics network in Hefei as the research object, considering the multi frequency recycling and vehicle sharing scheduling strategy, a reverse logistics network optimization scheme based on the operation cost of the reverse logistics network is proposed. Firstly, a reverse logistics recycling operation cost model is constructed, which includes the construction cost of reverse logistics infrastructure, equipment maintenance cost, the sum of the transportation cost of municipal solid waste and the treatment cost of non-recyclable waste at all levels, and a product maximization revenue model of the recycling center is established. Secondly, according to the characteristics of the model, a k-means spatio-temporal clustering algorithm considering the geographical location of waste transfer stations, recycling frequency and recycling time window is designed, and then an improved GA-PSO hybrid algorithm is proposed. The effectiveness of the model and algorithm is verified by comparing with HGA, GA-TS and HACO algorithms. Finally, according to the actual data of Hefei domestic waste reverse logistics network, the optimization research was carried out, and the recycling frequency and vehicle scheduling of transfer stations in different locations were analyzed. The results show that the model and algorithm proposed in this paper can carry out the optimal selection of recycling cost, resource sharing of recycling vehicles and reasonable vehicle routing optimization scheduling, and the operation cost of reverse logistics network is reduced by 8% compared with the previous one; As the transportation distance is reduced, the transportation cost is greatly reduced, and the treatment efficiency of municipal solid waste is improved. [ABSTRACT FROM AUTHOR]

This paper aims to analyse how to effectively protect and scientifically utilize the natural enemies of Pentatomidae in tea plantations in the peak period. In this paper, the spatial, quantitative and temporal relationships between Pentatomidae and its natural enemies in "Pingyangtezao", "Wuniuzao", "Huangshandayezhong", "Anjibaicha","Longjing 43″ and "Nongkangzao" tea gardens in Hefei, China were comprehensively compared and analyzed with the methods of geostatistical analysis, gray system analysis and temporal ecotone overlap index analysis. According to the size of the closeness index, the top three natural enemies with the largest sum of spatial, quantitative, and temporal closeness indexes in the six tea gardens were Clubiona japonicola (X7, 16.514), Oxyopes sertatus (X5, 16.390) and Xysticus ephippiafus (X2, 16.270). The size of the ratio between the number of Pentatomidae individuals and natural enemies largely determines whether the natural enemies follow Pentatomidae pests closely or not. The better the growth of tea plantations and the richer the diversity of pest species, the more accurately the predation preference of natural enemies can be reflected. In the control of Pentatomidae, specific analysis should be made according to the occurrence characteristics of target pests in different tea plantations and the basic attributes of tea plantations (species, growth, population characteristics of natural enemies and pests, etc.) in order to scientifically utilize its natural enemies. [ABSTRACT FROM AUTHOR]

• Pedestrian spatial violations at unmarked roads were collected by an unmanned aerial vehicle and a camera. • Male pedestrianshave a higher violation lkelihood. Younger pedestrians waited a shorter time before crossing and had fewer observations while crossing. • The illegal crossing probability with companions is higher than that of crossing alone. • Shorter intersections spacing, higher vehicle flow and longer crossing length all reduce the illegal propensity. Pedestrian violations are a major cause of pedestrian accidents. Considering that pedestrians are vulnerable to mortality and severe injury in traffic accidents, it is necessary to conduct a study of the factors influencing the occurrence of unmarked street crossing violations and to improve pedestrian safety in a targeted manner. This paper investigated pedestrian spatial violations on unmarked roadways at six high-traffic locations in Hefei and examined the effects of the road environment, pedestrian crossing behaviour, and pedestrian characteristics on pedestrian spatial violation decisions. Thirty variables with a total of 723 samples were obtained by an unmanned aerial vehicle (UAV) and a camera. The purpose of this study was to gain an understanding of pedestrian spatial crossing violations at unmarked roadways. A random parameter logit model was used to establish a pedestrian crossing decision model for roadway violations. The results indicate that males are more likely to violate than females; the probability of violation with companions is higher than that of crossing alone; when pedestrians cross with other strangers in the same direction, the rate will decrease; and shorter intersection spacing, a higher vehicle flow, and a longer pedestrian crossing length all reduce the illegal crossing propensity. The findings should be indicative to help traffic road construction departments and traffic participants take effective measures to improve road safety. [ABSTRACT FROM AUTHOR]

Driven by the concept of landscaping, this paper analyzed the impact of plant diversity on landscaping function, arrangement methods and community structure by taking plot sampling method as the experimental axis and 3 urban parks in Hefei as the blueprint. Six plots with the size of 20 m x 20 m were selected for investigation. There were 56 species of plants belonging to 50 genera and 42 families in the plots of Zhongshan Road City Park, 48 species of plants belonging to 44 genera and 40 families in the plots of Four Seasons Flower Sea City Park, and 69 species of plants belonging to 57 genera and 45 families in the plots of Xiaoyaojin Park. The survey results show that there are following problems in city parks: lack of plant effectiveness, too homogeneous plant community, disharmony between landscape and environment, poor plant maintenance and lack of attention to ecological maintenance. Based on this, the optimization measures are put forward: increasing evergreen plants to avoid no scenery in autumn, developing plants with excellent landscape effects and a variety of colorful plants, paying attention to the shaping of spatial structure and landscape pattern, regularly taking care of plants and their surrounding environment. It is expected to provide some reference for the construction and development of Hefei city parks, ensure the healthy and stable development of city parks, and provide ideas and methods for the improvement of plant landscaping in city parks. [ABSTRACT FROM AUTHOR]

With the increasing aging and the accelerating urbanization of China, the layout of urban medical facilities should be adjusted to meet the needs of the elderly population. This paper takes Hefei, China, as the research object. A questionnaire survey was conducted on the elderly who went to different levels of medical facilities for daily medical treatment, and 2,271 valid questionnaires were collected. The survey found that an accessibility factor of medical facilities is a common concern for the elderly who go to facilities of different levels, which indicates that it is reasonable to optimize the layout of medical facilities at all levels from the perspective of accessibility. Results revealed that the elderly in Hefei considered living within 10 km from a tertiary hospital (referred to as a Grade A facility in this paper) was most ideal. Meanwhile, a primary or secondary hospital (a Grade B facility) was most accessible within 6 km, and within 1.5 km was the optimum accessibility distance for a community health service center (a Grade C facility). This study considered the aforementioned medical service radii suitable for the elderly. From this, the study evaluated the accessible service range of different levels of medical facilities suitable for the elderly through the network analysis in ArcGIS. Then, the scarce areas of medical services in the city could be determined. Through location–allocation models, it was found that to realize the ideal medical distance for the elderly, 2 additional facilities were needed for Grade A, 1 for Grade B, and 61 for Grade C. The results could provide references for subsequent urban medical construction and aging development in China. [ABSTRACT FROM AUTHOR]

The aim of this paper is to clarify the difference of spatial closeness between natural enemies and Frankliniella intonsa, and to provide a scientific basis for rational protection and utilization of natural enemies. This paper applied the block‐sample square difference analysis method, Gray correlation degree method, the aggregation intensity index method and ρ index method to study the difference in the closeness of the spatial relationship between F. intonsa and natural enemies when the number of F. intonsa and their natural enemies was the highest and the minimum area occupied by F. intonsa individuals and colonies in five tea plantations in Hefei, Anhui province in 2021 and four tea plantations in 2020. The results were as follows: 1) Tetragnatha squamataKarsch, Xysticus ephippiafus, Erigonidium graminicolum and Theridion Octomaculatum were the top four natural enemies closely related to F. intonsa in 2021. The top three natural enemies closely related to F. intonsa in 2020 were Tetragnatha squamata Karsch, Xysticus ephippiafus and Theridion Octomaculatum. Two years ago, Tetragnatha squamata Karsch and Xysticus ephippiafus were the same. 2) Cluster size did not change the distribution patterns of natural enemies and F. intonsa. 3) The aggregation of F. intonsa was caused by their own causes or some environmental factors, and the aggregation of natural enemies was caused by environmental factors. 4) In 2021, the minimum area occupied by individuals and groups of F. intonsa in tea gardens was 2m2, and in 2020, it was 8 m2. [ABSTRACT FROM AUTHOR]

For the demand of rapid monitoring of pollution gas disorganized emissions in industrial parks, this paper studies the solar fast tracker system of vehicle-mounted SOF-FTIR (Solar Occultation Flux Fourier Transform Infrared Spectroscopy) system, where the spectrometer directly measures the broadband absorption spectrum of solar radiation light. A fast portable solar tracking system based on PSD (position sensitive detector) is designed, the mathematical model of solar spot position on the PSD surface source is established, and the optimal optical design parameters are simulated using the model. The dead-zone integral separation PID (Proportion Integration Differentiation) control algorithm is used to track the trajectory of the solar, and the light spot position model is used to nonlinearly compensate the output of PID control so that the PID controller has the same control precision and response speed in different error areas. Experimental analysis of the solar tracking performance of the vehicle-mounted SOF-FTIR under static and dynamic conditions, as well as the spectral effects on the measurements under static vehicle, constant speed, and turning driving conditions. The remote sensing application experiment of vehicle-mounted SOF-FTIR pollution gas emission flux was carried out in a tire factory in Hefei City, Anhui Province. A vehicle-mounted SOF-FTIR system realized the qualitative and quantitative analysis of the pollution gas at the boundary of the tire plant and calculated the flux of each component pollution gas. The emission flux of pollution gas was highly consistent with the actual pollution distribution of the tire plant. The results show that the positioning accuracy of PSD in the vehicle tracking experiment can also meet SOF-FTIR requirements for solar tracking. The remote sensing system will be useful in the field of atmospheric environment monitoring, and the mobile monitoring of regional pollutant gases based on solar infrared spectroscopy has application value. [ABSTRACT FROM AUTHOR]

Ground surface ozone (O3) is an emerging concern in China due to its complex formation process. In August 2020, field measurements of O3, NOx, and volatile organic compounds (VOCs) were carried out in Hefei's western suburbs. The pollution features of VOCs and O3 formation were thoroughly analyzed. The total VOC concentration was 42.26 ppb, with the dominant contributor being oxygenated VOCs (OVOCs). Seven emission sources were recognized using the positive matrix factorization (PMF) model, including aged air masses, combustion sources, fuel evaporation, industrial emissions, vehicular emission, solvent utilization, and biogenic emission. Ozone generation mainly occurred under an NOx-limited regime based on the zero-dimensional box model analysis. According to the scenario analysis, the 13% cut in O3 might be achieved by the 10% and 30% reduction in NOx and VOCs, respectively. The O3 budget analysis demonstrates its high ozone production rate during the pollution period. The influence of regional transport cannot be ignored for high O3 pollution. This paper provides scientific evidence for O3 production and the strategies of reducing O3 by controlling its precursors. [ABSTRACT FROM AUTHOR]

In view of the various constraints faced by cultural tourism industry in the process of integrated development, fifteen risk factors affecting the integration of the cultural tourism industry are analyzed from five dimensions. Taking the cultural tourism industry in Hefei as the research object, this paper analyzes the centrality and cause degree of each risk factor with the DEMATEL method. Combined with the ISM method, it analyzes the structure of risk factors for the integration of Hefei's cultural tourism industry, then sorts it into the deep factors, intermediate factors and convergence factors. The results show that the centrality of market integration risk is the highest; technology convergence risk and organizational convergence risk are the two key underlying risks; product fusion risk is a conductive risk; insufficient market adhesion is the main risk outcome factor, and it is also a direct reflection of the cultural tourism industry integration risk. According to the analysis results, relevant suggestions were put forward to promote the further integration and development of cultural tourism industry in Hefei. [ABSTRACT FROM AUTHOR]

X-band weather radar can provide high spatial and temporal resolution data, which is essential to precipitation observation and prediction of mesoscale and microscale weather. However, X-band weather radar is susceptible to precipitation attenuation. This paper presents an X-band attenuation correction method based on the light gradient machine (LightGBM) algorithm (the XACL method), then compares it with the ZH correction method and the ZH-KDP comprehensive correction method. The XACL method was validated using observations from two radars in July 2021, the X-band dual-polarization weather radar at the Shouxian National Climatology Observatory of China (SNCOC), and the S-band dual-polarization weather radar at Hefei. During the rainfall cases on July 2021, the results of the attenuation correction were used for precipitation estimation and verified with the rainfall data from 1204 automatic ground-based meteorological network stations in Anhui Province, China. We found that the XACL method produced a significant correction effect and reduced the anomalous correction phenomenon of the comparison methods. The results show that the average error in precipitation estimation by the XACL method was reduced by 39.88% over 1204 meteorological stations, which is better than the effect of the other two correction methods. Thus, the XACL method proved good local adaptability and provided a new X-band attenuation correction scheme. [ABSTRACT FROM AUTHOR]

In the dynamic ensemble selection algorithm, the region of competence of the test sample was composed of fixed samples, which would affect the classifier selection. Therefore, the paper proposed the DES-DCR-CIER algorithm based on dynamic region of competence strategy. Firstly, this algorithm used the heterogeneous classifier to generate the base classifier pool to deal with the problem that the difference between the homogeneous ensemble classifiers was little and the number of heterogeneous ensemble classifiers was small. Next, it applied three steps including the mutual K nearest neighbor with adaptive distance algorithm, approaching the distance center of the sample set and removing the class edge samples to determine the dynamic region of competence of the test sample and it used overall complementarity index to select a set of classifiers. Finally, the classifiers were synthesized by the ER rule to get integration. Experiments on the diagnosis data of breast mass from 8 sonographers in a tertiary hospital in Hefei, Anhui Province and American Wisconsin Breast Cancer Diagnostic data set showed that the diagnostic model based on the DES-DCR-CIER algorithm had better accuracy. [ABSTRACT FROM AUTHOR]

Accurately forecasting the demand of urban online car-hailing is of great significance to improving operation efficiency, reducing traffic congestion and energy consumption. This paper takes 265-day order data from the Hefei urban online car-hailing platform from 2019 to 2021 as an example, and divides each day into 48 time units (30 min per unit) to form a data set. Taking the minimum average absolute error as the optimization objective, the historical data sets are classified, and the values of the state vector T and the parameter K of the K-nearest neighbor model are optimized, which solves the problem of prediction error caused by fixed values of T or K in traditional model. The conclusion shows that the forecasting accuracy of the K-nearest neighbor model can reach 93.62%, which is much higher than the exponential smoothing model (81.65%), KNN1 model (84.02%) and is similar to LSTM model (91.04%), meaning that it can adapt to the urban online car-hailing system and be valuable in terms of its potential application. [ABSTRACT FROM AUTHOR]

Due to the complications in the measurement of fine particulate matter (PM2.5), this paper proposes a method using lidar for assessing PM2.5. By calculating the aerosol optical depth (AOD) for MODIS, CALIPSO, and ground-based lidar, the corrected PM2.5 was predicted. The results showed that AOD and PM2.5 had a linear relationship. The linear correlation coefficient between ground-based lidar AOD and PM2.5 was 0.81, and the root-mean-square error (RMSE) and mean deviation (MD) were 24.43 and 18.41, respectively. The linear correlation coefficient between CALIPSO AOD and PM2.5 was 0.8, and its RMSE and MD were 42.91 and 33.25, respectively. The linear correlation between AOD and PM2.5 for VIIRS was approximately 0.7. This paper provides more possibilities for lidar observation and prediction of the environment. [ABSTRACT FROM AUTHOR]

As an essential parameter to represent vehicle following characteristics, distance headway (DHW) plays an essential role in microtraffic flow simulation, traffic control, and traffic safety alarm. However, due to the randomness, nonlinearity, and correlation of DHW data, constructing DHW prediction models is difficult. Moreover, few studies have considered the time correlation between the historical DHW and the target DHW. To solve the above problems, a DHW prediction model is proposed in this paper by integrating entropy-based grey relation analysis (EB-GRA) and temporal convolutional network (TCN), named as EB-GRA-TCN model. In the model, the EB-GRA is adopted to calculate the correlation between the target DHW and historical DHW sequences, and the DHW data with high correlation are dynamically selected as the optimal input of the DHW prediction model. Then, the TCN algorithm is used to train the DHW prediction model. The TCN architecture integrates the advantages of recurrent neural network (RNN) and convolutional neural network (CNN), which could fully use the previous DHW information. In the experiment, the DHW data from Hefei Expressway are utilized for training the EB-GRA-TCN model. The prediction results showed that the average root mean square error (RMSE) and mean absolute error (MAE) of the proposed model were 0.115 and 0.090, respectively, in the 5, 10, and 15 predicted steps. Compared with the autoregressive integrated moving average (ARIMA), TCN, RNN, and long short-term memory (LSTM) models, the EB-GRA-TCN model achieved the best prediction accuracy. The results indicated that the EB-GRA-TCN model obtained good predictive performance and could provide support for road traffic control and traffic safety warming. [ABSTRACT FROM AUTHOR]

Bioaerosols are usually defined as aerosols arising from biological systems such as bacteria, fungi, and viruses. They play an important role in atmospheric physical and chemical processes including ice nucleation and cloud condensation. As such, their dispersion affects not only public health but also regional climate. Lidar is an effective technique for aerosol detection and pollution monitoring. It is also used to profile the vertical distribution of wind vectors. In this paper, a coherent Doppler wind lidar (CDWL) is deployed for aerosol and wind detection in Hefei, China, from 11 to 20 March in 2020. A wideband integrated bioaerosol sensor (WIBS) is used to monitor variations in local fluorescent bioaerosols. Three aerosol transport events are captured. The WIBS data show that, during these transport events, several types of fluorescent aerosol particles exhibit abnormal increases in their concentration, number fractions to total particles, and number fractions to whole fluorescent aerosols. These increases are attributed to external fluorescent bioaerosols instead of local bioaerosols. Based on the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) backward trajectory model and the characteristics of external aerosols in WIBS, their possible sources, transport paths, and components are discussed. The results prove the influence of external aerosol transport on local high particulate matter (PM) pollution and fluorescent aerosol particle composition. The combination of WIBS and CDWL expands the aerosol monitoring parameters and provides a potential method for real-time monitoring of fluorescent biological aerosol transport events. In addition, it also helps to understand the relationships between atmospheric phenomena at high altitudes like virga and the variation of surface bioaerosol. It contributes to the further understanding of long-range bioaerosol transport, the roles of bioaerosols in atmospheric processes, and in aerosol–cloud–precipitation interactions. [ABSTRACT FROM AUTHOR]

Urban transportation is a significant contributor to energy consumption and environmental degradation, while solar electric bikes (SE-bikes) represent a viable solution for alleviating both problems. In this paper, the charging and discharging properties of the SE-bike are investigated. An SE-bike is constructed for short and long term experiments. Experimental results indicate that the SE-bike can increase endurance by 20.5 km on a sunny day, and can meet daily cycling needs of 10 km without charging in both summer and autumn in Hefei. To assess the annual performance of the SE-bike, a theoretical model is developed, which includes the effects of environmental factors, vehicle shapes, daily electricity usage, etc. Simulation results reveal that the SE-bike only needs to be charged 5 times per year to meet daily demands in Hefei, which is a relative reduction of 93.0 % compared to 71 times per year for the regular bike without solar power supply. [ABSTRACT FROM AUTHOR]

Traditional flat PV heat pumps has low irradiation density, large PV area, and the PV evaporators are always fixed, causing large area occupation and lots of irradiation missing, which limit the application and system efficiency. To solve the problems, a novel concentrated PV-air dual-source heat pump system (CPV-DSHP) was proposed in the previous paper, but the annual performance and economic comparison with flat PV-DSHP (FPV-DSHP) are still blank, which are extremely concerning to researchers. Besides, the paper also fills related content about the impact of irradiation composition on the system performance and economics, as well as the irradiation comparison on tracking CPV and fixed FPV surface. From the calculation of the validated model, it's found that the CPV-DSHP system could capture 6098 MJ and 2213 MJ more solar energy, and produce 282.21 kWh and 100.16 kWh more electricity in Garze and Hefei in a year. The annual concentration efficiency is 82.73 % in Garze where direct irradiation accounts for 68.89 %, which is only 73.15 % in Hefei with 39.84 %.The COP PVT is annually lifted by 0.40 in Garze. Although the two systems could both get payback in 5∼6 years, the CPV-DSHP only shows economic advantages in places with good direct irradiation conditions like Garze. • A novel concentrated PV-air dual-source heat pump system (CPV-DSHP) is presented. • The annual performance and economic comparison in different cities are supplemented. • The CPV-DSHP could produce 282.21 kWh more electricity in Garze in a year. • The annual concentration efficiency is 82.73 % in Garze with better direct irradiation. • Payback time is 5∼6 years but CPV-DSHP only shows economic advantage in Garze. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate the impact of e-government usage on citizen engagement during the COVID-19 crisis in China, in relation to the mediating role of how citizens perceive the government. A model was also proposed to explain the relationship between e-government usage during the COVID-19 crisis and the mediating role that different perceptions of government play in influencing citizens level of engagement. Design/methodology/approach: The research model was tested empirically through a survey conducted online with 866 research participants, comprising of Chinese citizens from three large cities, which include Hefei, Shanghai and Nanjing. Findings: The results in structural equation modeling showed that e-government usage has a significant positive influence on citizens' perception about trust in government, government transparency and government reputation but not significant influence on citizens' engagements. However, an indirect relationship was found out in the mediation analysis. There was also a significant relationship between the different perceptions of government. Mediation analysis showed that all the different perceptions of government mediate the relationship between e-government usage and citizens' engagements during the COVID-19 crisis. The single mediation pathways were found to be most effective mediators, identifying citizens' perception about trust in government to be the most effective mediator. Originality/value: This study filled the gap in literature by examining how e-government usage by Chinese citizens during the COVID-19 crisis helped influence their attitude and behavior. Specifically, this study is one of the first to integrate citizens' usage of e-government and citizens' engagement through the different citizens' perceptions of government such as trust in government, transparency of government and government reputation in a non-liberal country. [ABSTRACT FROM AUTHOR]

In urban traffic systems, alleviating traffic congestion originated from left-turn/U-turn lanes at highly demanded intersections plays an important role in enhancing the traffic efficiency. For a typical intersection, the layout with double left-turn (DLT) lanes is a relatively common geometric feature. However, the effect of DLT scheme on the performance of the entire traffic system is not clear. This paper compares the performance of urban traffic system with different lane function schemes with extended cellular automaton (CA) model considering the car-following, lane-changing, intersection-traversing and route-choice behavior of vehicles. Using the flow-density relation, three macroscopic parameters (average trip completion rate, average traffic flow and average velocity) are examined to evaluate the system performance. With the wide application of DLT scheme, the vehicles can be distributed more evenly among the lanes. As a result, the traffic flow and the trip completion rate will be higher, especially at high density. Case studies of realistic Hefei city network and Sioux Falls networks are also carried out. The results show that the performance of traffic network will be better if more intersections adopt the DLT scheme. [ABSTRACT FROM AUTHOR]

Spatial Markov chain can effectively explore the spatial evolution trend of housing price under the influence of lag factor. This paper uses spatial autocorrelation and spatial Markov to study 353 second-hand houses in Hefei. The results show that (1) the housing price of Hefei urban area presents a situation of "two points and one side," the high housing price is concentrated in the south and southwest of the urban area, and the price level gradually weakens from south to north, and the housing development shows a north-south differentiation. (2) There is a significant spatial autocorrelation between second-hand housing prices in Hefei. The "high-high" residential price clusters are mainly distributed in Shushan District and Binhu New Area, while the "low-low" residential price clusters are mostly in Yaohai district and its surrounding areas. The number of "low-high" agglomeration and "high-low" agglomeration is small, and the degree of change is not big. (3) Under the influence of different neighborhood environments, the housing prices in urban Area of Hefei show club convergence overall. At the same time, under the short-term influence of the policy, the housing prices of low level and middle and low level are promoted in the same neighborhood environment, while the housing prices of high level and middle and high level are negatively affected. [ABSTRACT FROM AUTHOR]

Driven by the single function and poor thermal performance of traditional building windows, a novel CdTe multi-layer ventilated window integrated with a middle PCM layer is proposed in this paper. Comparative study is conducted between this novel system and another CdTe ventilated window without the PCM layer. Mathematical model of the system is established and validated. Comparison case study is performed under two groups of typical winter and summer days in Hefei. Parameter analyses are conducted and annual performance comparisons are investigated under the typical meteorological year of Hefei. Main results are: (1) Electrical performance of the PV window system was enhanced and indoor thermal comfort was improved due to the utilization of PCM; (2) T a m b and G s o l a r are respectively the most influential weather factors on thermal and electrical performance. Properly decreasing the channel height and increasing the PCM thickness can improve the comprehensive performance; (3) Annual E p v of the two window systems are 171.16 kWh and 169.55 kWh. Building with the novel window system could achieve a better indoor thermal comfort for the whole year. Annual indoor air-conditioning load is reduced by 1246.87 kWh and the energy-saving potential of this newly proposed CdTe PV ventilated window system is proved. [ABSTRACT FROM AUTHOR]

Administrative division adjustments, such as agglomerations, upgrading, and revocation, introduce a series of uncertain impacts on the social and economic development in administrative regions. Previous studies have focused more on the economic effects of administrative division adjustments, but in this paper, we also consider the environmental effects of such adjustments. In 2011, with the approval of the State Council, the prefecture-level Chaohu city was officially revoked, resulting in a county-level Chaohu city. One district and four counties under the jurisdiction of the original Chaohu city were placed under the jurisdiction of Hefei, Wuhu, and Ma'anshan. This adjustment made Chaohu Lake an inner lake of Hefei city. The administrative division adjustment of Chaohu Lake, China, is used as a quasi-natural experiment to explore the influence of such an adjustment on pollution control. The synthetic control method (SCM) is used in this study to evaluate the effect of the administrative division adjustment on the water quality indicators of Chaohu Lake. The following conclusions are drawn. First, after the administrative division adjustment, some water quality indicators, such as ammonia nitrogen, improved; however, other major pollution indicators, such as chemical oxygen demand (COD) and dissolved oxygen (DO), worsened to varying degrees. Second, the results reveal that improper development ideas, excessive industrial expansion, and the shift in economic growth and environmental goals were problems after the adjustment. Returning to the original intention of the administrative division adjustment, rationalizing the Chaohu Lake management system and designing a sound and feasible accountability mechanism are fundamental measures for reducing pollution. [ABSTRACT FROM AUTHOR]

Emergency fire service (EFS) systems provide rescue operations for emergencies and accidents. If properly designed, they can decrease property loss and mortality. This paper proposes a distributionally robust model (DRM) for optimizing the location of fire stations, the number of fire trucks, and demand assignment for long term planning in an EFS system. This is achieved by minimizing the worst-case expected total cost, including fire station construction cost, purchase cost for fire trucks, transportation cost, and penalty cost for not providing adequate service. The ambiguity in demands and travel durations distributions are captured through moment information and mean absolute deviation. A cutting plane method is used to solve the problem. Due to fact that it is computationally intensive for larger problems, two approximate methods are introduced; one that uses linear decision rules (LDRs), and another that adopts three-point approximations of the distributions. The results show that the heuristic method is especially useful for solving large instances of DRM. Extensive numerical experiments are conducted to analyze the model's performance with respect to different parameters. Finally, data obtained from Hefei (China) demonstrates the practical applicability and value of the model in designing an EFS system in a large metropolitan setting. [ABSTRACT FROM AUTHOR]

In this paper, a CdTe photovoltaic double-skin ventilated window integrated with vacuum glazing (VPV-DSV) is proposed. The mathematical model of VPV-DSV was developed and validated through tests in Hefei, China. Annual energy performance and the economic analysis of the VPV-DSV was evaluated and compared with the other two PV-DSVs and an insulating glazed window (IG) under climate conditions of five selected cities, including Changchun, Hefei, Kunming, Shenzhen, and Shijiazhuang. Moreover, effects of window design factors, including the window-to-wall ratio, PV coverage, and pillar spacing of the VG, were explored. Results indicated that: (1) the VPV-DSV produced the best energy saving results and the least energy consumption. (2) NECs of the VPV-DSV in the five cities above was 955.05 kW•h, 464.31 kW•h, 110.66 kW•h, 53.71 kW•h, and 443.14 kW•h, respectively. (3) Due to high cost of the VG, the VPV-DSV only had the best economic performance in Shenzhen and the NPV was 3931.47 CNY. (4) The WWR and PV coverage had obvious impacts on the overall performance of the VPV-DSV, while the pillar spacing only had a more significant impact on the air conditioning energy consumption. [ABSTRACT FROM AUTHOR]

• A continuous division method is developed for the dynamic boundary of single congested region. • A congested area range estimation method is applied to determine the boundary change trend. • A three-dimensional MFD surface model is proposed considering the scope of the sub-region. • A sliding mode control method is integrated for the perimeter flow of dynamic changing congested sub-region. • The proposed control method can improve the efficiency of road network compared to PI and PIDB. The urban traffic system is a complex dynamic system, and its state changes with the real-time traffic demand; correspondingly, the range of congested areas also continuously transforms spatiotemporally. Affected by the traffic congestion range, the dynamics of a road network and the macroscopic control model that describes the road network also change. The existing sub-region division methods divide sub-regions based on cluster algorithms, and their results cannot be directly used to establish a dynamic congested area model with varying ranges or to implement perimeter control because they fail to consider the continuity of congested area transfer. To achieve control of the dynamic entrance boundary of a continuously changing congested range, this paper carries out three related analyses. First, depending on the section data of the kernel congested area, a continuous division method for generating sub-regions is proposed on the basis of similarity theory to determine the dynamic boundary of the congested area. Then, after the boundary intersections of bottlenecks are categorized as output, input, or passing types, a congested area range estimation model is established using the density wave transfer speed to estimate the boundary range change trend caused by the influence of traffic congestion diffusion or dissipation. A three-dimensional macroscopic fundamental diagram (MFD) surface model with an independent section length, traffic flow density, and road network trip completion rate of the congested area is then established according to the changes in the congested area. On the basis of the three-dimensional MFD surface model, a sliding mode control with dynamic boundary (SMCDB) method is proposed to determine the entrance of the congested area. With a regional road network in Hefei taken as an example, numerical experiments are carried out, and the simulation results are compared with those of PI control with and without boundary changes, showing that the SMCDB method can track congested boundaries and adjust boundary flows according to the traffic state, protect the centre network from over-saturation, effectively improve the trip completion flow, and decrease the network travel delay. [ABSTRACT FROM AUTHOR]

In this paper, a horizontal and vertical double-slits interferometer using visible light are designed to measure the transverse beam size of Hefei Light Source II (HLS-II). For the given initial structural parameters of the two interferometers, a series of numerical simulations and analyses are carried out by using the Synchrotron Radiation Workshop (SRW) code. Furthermore, the core parameters of the double-slits components in the interferometers are optimized. In the end, the visibilities of the horizontal and vertical interferometer we designed are 0.345 and 0.548 respectively, which are in the range of 0.2–0.6. And simulation results meet the requirement of theoretical relative measurement error of less than 10%. [ABSTRACT FROM AUTHOR]

• Revealing the causal relationship between sub-central city and green innovation. • GTFP and GPG are used to measure green innovation. • The sub-center policy can promote green innovation (GTFP and GPG). • Results are of great significance to regional integration policy planning. The green innovation level of sub-center cities in regional integration must be addressed in promoting high-quality economic development. Therefore, governments and policymakers should pay attention to its positive effects. In the Yangtze River Delta integration context, this paper uses Hefei as an example sub-center city to assess its green innovation in two indicators, green total factor productivity (GTFP) and the number of green patent grants (GPG). The first step is to measure GTFP using the SBM-ML model. The second step is to evaluate the policy effects of sub-center city experiences on green innovation using Synthetic Control Methods. The empirical findings of this study indicate that sub-centers play an essential role in promoting green innovation even if they are located outside the core area of an urban agglomeration. Additionally, the placebo trial confirmed the reliability and significance of the results. This paper proposes some policy recommendations to realize global green innovation based on these findings. [ABSTRACT FROM AUTHOR]

Bioaerosols, usually defined as aerosols derived from biological systems, including bacteria, fungi, and viruses, play an important role in atmospheric physical and chemical processes, such as ice nucleation and cloud condensation. Thus their transport affects regional climate change and public health. Lidar is an effective technique for aerosol detection and pollution monitoring as well as profiling the vertical distribution of wind vectors. In this paper, a coherent Doppler wind lidar (CDWL) was deployed for wind and aerosol detection in Hefei, China, from 11 March to 20 March in 2020. A wideband integrated bioaerosol sensor (WIBS) was deployed to monitor the local fluorescent bioaerosol variation. During the observation, three aerosol transport event was captured. The WIBS data show that some types of fluorescent aerosol particles exhibit abnormal increases in concentration and fraction to total particles or whole fluorescent aerosols during the transport events. We attribute these increases to the transported external fluorescent bioaerosols instead of local bioaerosols. Based on the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) backward trajectory model and the characteristics of external aerosols in WIBS, their possible sources, transport paths, and components are given. This work proves the influence of external aerosol transport on local high particulate matter (PM) pollution and fluorescent aerosol particle composition and gives a possible method for real-time monitoring of fluorescent biological aerosol transport events. It contributes to the further understanding of bioaerosol transport. [ABSTRACT FROM AUTHOR]

Assessing seismic risk is an essential element of urban risk management and urban spatial security work. In response to the issues posed by the complexity and openness of urban systems, the nonlinearity of driving factors, and sudden changes in geological processes that affect urban seismic research, this paper is based on a variety of intelligent algorithms to develop a hybrid intelligent model that integrates probability and vulnerability to evaluate and quantify the difference in the urban spatial units distribution of earthquake risk. We applied this model to Hefei, one of the few superlarge provincial capital cities on the "Tancheng-Lujiang" fault zone, one of the four major earthquake zones in China, which suffers frequent earthquakes. Our method combined the genetic algorithm (GA), particle swarm optimization (PSO), and backpropagation neural network methods (BP) to automatically calculate rules from inputted data on known seismic events and predict the probability of seismic events in unknown areas. Then, based on the analytic hierarchy process (AHP), spatial appraisal and valuation of environment and ecosystems method (SAVEE), and EMYCIN model, an urban seismic vulnerability was evaluated from the four perspectives of buildings, risk of secondary disasters, socioeconomic conditions, and urban emergency response capabilities. In the next step, the overall urban seismic risk was obtained by standardizing and superimposing seismic probability and vulnerability. Using the hybrid intelligent model, earthquake probability, seismic vulnerability, and overall seismic risk were obtained for Hefei, and the spatial characteristics of its overall seismic risk were examined. This study concludes that areas with very high, high, low, and very low earthquake risk in Hefei account for 8.10%, 31.90%, 40.94%, and 19.06% of its total area, respectively. Areas with very high earthquake risk are concentrated in the old city, the government affairs district, Science City, and Xinzhan District. This study concludes that government authorities of Hefei should target earthquake safety measures consisting of basic earthquake mitigation measures and pre- and postearthquake emergency measures. In the face of regional disasters such as earthquakes, coordinating and governing should be strengthened between cities and regions. [ABSTRACT FROM AUTHOR]

Most road crashes are caused by human factors. Risky behaviors and lack of driving skills are two human factors that contribute to crashes. Considering the existing evidence, risky driving behaviors and driving skills have been regarded as potential decisive factors explaining and preventing crashes. Nighttime accidents are relatively frequent and serious compared with daytime accidents. Therefore, it is important to focus on driving behaviors and skills to reduce traffic accidents and enhance safe driving in low illumination conditions. In this paper, we examined the relation between drivers' risk perception and propensity for risky driving behavior and conducted a comparative analysis of the associations between risk perception, propensity for risky driving behavior, and other factors in the presence and absence of streetlights. Participants in Hefei city, China, were asked to complete a demographic questionnaire, the Driver Behavior Questionnaire (DBQ), and the Driver Skill Inventory (DSI). Multiple linear regression analyses identified some predictors of driver behavior. The results indicated that both the DBQ and DSI are valuable instruments in traffic safety analysis in low illumination conditions and indicated that errors, lapses, and risk perception were significantly different between with and without streetlight conditions. Pearson's correlation test found that elderly and experienced drivers had a lower likelihood of risky driving behaviors when driving in low illumination conditions, and crash involvement was positively related to risky driving behaviors. Regarding the relationship between study variables and driving skills, the research suggested that age, driving experience, and annual distance were positively associated with driving skills, while myopia, penalty points, and driving self-assessment were negatively related to driving skills. Furthermore, the differences across age groups in errors, lapses, violations, and risk perception in the presence of streetlights were remarkable, and the driving performance of drivers aged 45–55 years was superior to that of drivers in other age groups. Finally, multiple linear regression analyses showed that education background and crash involvement had a positive influence on error, whereas risk perception had a negative effect on errors; crash involvement had a positive influence, while risk perception had a negative effect on lapse; driving experience and crash involvement had a positive influence on violation; and age had a negative influence on it. [ABSTRACT FROM AUTHOR]

Through an overview of the construction and development process of the pomegranate specialized garden in Hefei Botanical Garden, the collection and application status of the pomegranate varieties in the specialized garden w'ere introduced, and the significance of the construction of the pomegranate specialized garden and the related problems that exist and need to be solved urgently were analyzed. This paper put forward suggestions and solutions for the better application of pomegranate varieties in Hefei, laying a foundation for the later research on pomegranate. [ABSTRACT FROM AUTHOR]

Urbanization in Central and Western China has attracted increasing attention in the advent of new-type urbanization in China and the age of 'Global Urbanism'. Although land urbanization is at the epicenter of Chinese urbanization, its process and driving forces in counties beyond the Eastern coastal areas are less known. This paper therefore seeks to investigate the spatial expansion and driving forces of land urbanization in Feixi county, a relatively advanced county neighboring Hefei city proper in Anhui province in Central China. Based on the land-use change survey data, remote sensing interpretation data, and statistical yearbook data of Feixi county from 2002 to 2016, it is revealed that the overall scale of urban land in Feixi county increased remarkably, though with obvious temporal and geographical variants. The year 2009 appears to be the cutting line between quantity-based land urbanization and quality-based land urbanization. Land urbanization rate is sensitive to both geographical distance and traffic accessibility to Hefei city proper. Driving forces of land urbanization in Feixi county are summarized as: (1) central city expansion, (2) government-led industrial park construction, and (3) large industrial projects along traffic corridors. A better understanding of urbanization in Feixi county cannot be fulfilled without taking into account the wider spatial process in Hefei city and the Yangtze River Delta city-region. [ABSTRACT FROM AUTHOR]

Information on the vertical distribution of air pollutants is essential for understanding their spatiotemporal evolution underlying urban atmospheric environment. This paper presents the SO 2 profiles based on ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements from March 2018 to February 2019 in Hefei, East China. SO 2 decrease rapidly with increasing heights in the warm season, while lifted layers were observed in the cold season, indicating accumulation or long-range transport of SO 2 in different seasons might occur at different heights. The diurnal variations of SO 2 were roughly consistent for all four seasons, exhibiting the minimum at noon and higher values in the morning and late afternoon. Lifted layers of SO 2 were observed in the morning for fall and winter, implying the accumulation or transport of SO 2 in the morning mainly occurred at the top of the boundary layer. The bivariate polar plots showed that weighted SO 2 concentrations in the lower altitude were weakly dependent on wind, but in the middle and upper altitudes, higher weighted SO 2 concentrations were observed under conditions of middle-high wind speed. Concentration weighted trajectory (CWT) analysis suggested that potential sources of SO 2 in spring and summer were local and transported mainly occurred in the lower altitude from southern and eastern areas; while in fall and winter, SO 2 concentrations were deeply affected by long-range transport from northwestern and northern polluted regions in the middle and upper altitudes. Our findings provide new insight into the impacts of regional transport at different heights in the boundary layer on SO 2 pollution. [Display omitted] [ABSTRACT FROM AUTHOR]

With the consideration of the uneven traffic volume distribution at intersections on urban arterials, this paper aims to minimize the overall passenger delay (buses and private vehicles) at intersections and identify the applicable conditions of the proposed method with field data. The overlapping phase-based signal control logic and the bus priority control algorithm under two-way signal coordination on arterial roads are proposed. The vehicular capacities and occupancies for buses and passenger cars are considered in the evaluation of the method performance. A field test was carried out at two major intersections on an arterial road in Hefei, China. With the test data, the proposed method is examined and the possible influencing factors are analyzed for identifying the corresponding applicable conditions. The analysis result shows that the application of the overlapping phase helps to provide a relatively flexible signal control for the varying traffic demands at intersections. Compared to the conventional phase, it isof more practical significance to consider overlapping phase and apply bussignal priority control under two-way signal coordination according to the condition of uneven traffic volumedistribution at intersections on urban arterials. The proposed method can effectively decrease the total passenger delay at the intersections on urban arterials under certain applicable conditions. The possible factors influencing the method applicability are identified as well. It is verified that bus signal priority control under the two-way signal coordination, based on overlapping phases, is more conducive to improving traffic efficiency on urban arterials. Regarding the influencing factors and the applicability of the proposed method, the results show that not all situations are conducive to decreasing passenger delay at intersections. The proposed method should be applied under certain applicable conditions and principles in order to efficiently and effectively improve the traffic efficiency on arterial roads. [ABSTRACT FROM AUTHOR]

In the traditional PV/T system, there is a certain contradiction in the collection process of heat and electric energy. This paper describes a spectral splitting PV/T system, which effectively alleviates the negative effects of high temperature on monocrystalline silicon cells, and separates the soalr radiation so as to improve the utilization efficiency of full spectrum energy. Then, through the all-day experimental study, the results show that the maximum temperature of the spectral splitting medium can reach 38.21 °C, the maximum thermal and electrical efficiency were 38.7 % and 11.77 %, respectively. The output power of the PV cell is more affected by solar radiation, and the filling factor is more affected by the temperature of the battery. In addition, the mathematical model is established and verified. The results show that the optimal nanofluid concentration of the system is 1*107 μg/m3 and 5*106 μg/m3 in Xining and Hefei, respectively. When applied in Beijing area, the optimal nanofluid concentration is 1*106 μg/m3 in summer and 1*107 μg/m3 in winter. Finally, we calculated the annual electric energy and heat output in the three regions using the best nanofluids, namely 126.6 MJ/m2 and 1186.68 MJ/m2 in Xining, 154.44 MJ/m2 and 948.96 MJ/m2 in Hefei, 164.46 MJ/m2 and 1062.43 MJ/m2 in Beijing. • Experimental and numerical investigation on spectral splitting PV/T system under natural conditions. • Excellent thermal and electrical performance, loss coefficient of heat energy. • The applicability of spectrally selective nanofluids in the system were evaluated. • Optimal nanofluid concentration for different regions based on annual performance analysis. [ABSTRACT FROM AUTHOR]

Hefei, the capital city of Anhui Province, is located in China's central region. A city with over 2200 years of history, Hefei was still a middle-sized city at the end of 1970s. Over the past decade, however, the city had experienced a dramatic spatial expansion and economic growth. This paper discusses Hefei's history of development, its achievement in socioeconomic and spatial development, and its challenges with regard to future development. Urban researchers have largely ignored cities in China's central region; as such, this paper will serve to enrich the international literature in this field and enable readers to better understand the urbanization and industrialization efforts of a typical emerging city in inland China. [ABSTRACT FROM AUTHOR]

In the era of the Internet and big data, data permeate the entire process of multiple criteria decision making (MCDM). Therefore, generation of rational solutions from current observations and historical data has become an important and interesting issue. To address this issue, this paper proposes a data-driven MCDM framework in the context of the evidential reasoning approach. Three challenges in the framework are met, including the transformation of observations into assessments, the learning of parameters and their constraints from historical data, and the generation of a data-driven solution. The proposed framework is then used to model the diagnosis of thyroid cancer and generate data-driven diagnostic results. The three challenges in the application are met to aid radiologists in improving the diagnostic accuracy of thyroid cancers. To examine whether the application of the proposed data-driven MCDM framework to the diagnosis of thyroid cancer can help improve diagnostic accuracy, we conduct a case study by using the examination reports of three radiologists from July 2015 to October 2017 in the ultrasonic department of a tertiary hospital located in Hefei, Anhui Province, China. [ABSTRACT FROM AUTHOR]

This case study uses a long short-term memory (LSTM)–based model to predict short-term urban water demands for the Hefei City of China. The performance of the LSTM-based model is compared with the autoregressive integrated moving average (ARIMA) model, the support vector regression (SVR) model, and the random forests (RF) model based on data with time resolutions ranging from 15 min to 24 h. Additionally, this paper investigates the performance of the LSTM-based model in predicting multiple successive data points. Results show that the LSTM-based model can offer predictions with improved accuracy than the other models when dealing with data with high time resolutions, data points with abrupt changes, and data with a relatively high uncertainty level. It is also observed that the LSTM-based model exhibits the best performance in predicting multiple successive water demands with high time resolutions. In addition, the inclusion of external parameters (e.g., temperature) cannot enhance the performance of the LSTM-based model, but it can improve ARIMAX's prediction ability (ARIMAX is the ARIMA with variables). These observations provide additional and improved evaluations regarding the LSTM-based models used for short-term urban water demand forecasting, thereby enabling their wider adoption in practical applications. [ABSTRACT FROM AUTHOR]

The concept of solar-air dual source heat pump has been proposed to overcome the limitations of single source heat pump system. In this paper, a comparative investigation is presented among three types of solar-air dual source heat pump with different heat source configurations: solar-air series source heat pump (SA-SHP), solar-air parallel source heat pump (SA-PHP) and air-solar series source heat pump (AS-SHP). The impact of environmental parameters has been discussed, and the optimal working condition for each system has been identified. The results indicate that SA-SHP is suitable for working under the environment with low solar irradiation, AS-SHP shows the best performance under the condition with low ambient temperature and high solar irradiation, and SA-PHP can achieve the optimal state at high ambient temperature or high solar irradiation. The dynamic performance of SA-SHP, SA-PHP and AS-SHP in the daytime has been compared. The dynamic behavior of each system is significantly different. The COP of SA-PHP is the highest ranging from 4.50 to 4.58, followed by AS-SHP ranging from 4.39 to 4.50, and the COP of SA-SHP is the lowest ranging from 4.33 to 4.41. Moreover, the annual performance and economic feasibility for each system in different climatic regions are evaluated. • Dual source heat pump with different heat source configurations is compared. • Optimal working condition for each system is identified. • The role of air source evaporator and solar evaporator in each system is discussed. • The annual and economic performance is evaluated in different climatic regions. • The annual average COPs of each system in Hefei, Beijing and Xining are above 3.0 [ABSTRACT FROM AUTHOR]

This paper aims to examine the characteristics of steady burning of inclined polymethyl methacrylate (PMMA) slabs under different ambient pressures. A sequence of experiments concerning steady burning intensity and combustion efficiency of the sample were conducted under both normal pressure (Hefei: altitude 30 m, 100 kPa) and reduced pressure (Lhasa: altitude 3650 m, 64 kPa). An in situ calorimeter based on oxygen consumption method was employed to measure the heat release rate of materials. A semi-theoretical model based on convective heat feedback from the flame was proposed and fitted well with laminar-dominated flame over the inclined PMMA surface. The critical maximum side length of sample for laminar-dominated flame in Hefei is lower than Lhasa. The trend of combustion efficiency with increasing inclination angle shows a great difference under different pressure environments. [ABSTRACT FROM AUTHOR]

Analyzing the GPS coordinate time series plays an important role in the crustal deformation monitoring and surface mass variation interpretations. In this paper, we present the results of detailed studies concerning the analysis of the long-term GPS coordinate time series. We show what the characteristics of all stations is monitored and how to keep track of the variations for both horizontal and vertical components by using Lomb-Scargle periodogram method and Maximum Likelihood Estimation method. For the Hefei area, the horizontal components exhibit obvious linear trend, while the vertical components display significant seasonal fluctuations which can be approximated by a function of an annual and a semi-annual signal. Under the optimal noise models, there is a consistent southeast trend, with an average of 35.21 mm/yr in the direction of E20.91°S, in the horizontal components under the ITRF2014. The relative velocities between different stations are with variations of 0.5~1.5 mm/yr, and the southern stations indicate bigger relative velocities than the northern stations. The mean vertical velocity is 1.31 mm/yr, revealing an overall uplift for this area. Moreover, the vertical displacements from the surface loading models (SLMs) are computed to interpret the seasonal GPS vertical crustal deformations. There are good consistencies between the GPS and SLMs data. The solutions of the two different types of data are closely to each other, and the mean correlation coefficient is 0.55 between the GPS and SLMs displacement time series, demonstrating that the seasonal variations might originate from the same geophysical process. Our analysis can provide useful reference for comprehensive analysis of the regional GPS coordinate time series. [ABSTRACT FROM AUTHOR]

The lithospheric "de‐rooting" of the Sulu‐Dabie Orogen (SDO) is an important tectonic mechanism for post‐orogenic tectono‐magmatism, which influenced the sedimentation, evolution, and development of oil–gas accumulation in the Hefei Basin (HB). Combined with seismic, geological, and sedimentary data of the HB and the SDO, this paper studies the coupling of the HB and the SDO since the Late Mesozoic. While the North China Block (NCB) indented south‐eastwards under the Greater South China Block (GSCB) since the Mesozoic, the SDO underwent three intense tectonic stages, i.e., subduction, exhumation, and uplift. The upwelling of deep mantle material causes the exhumation of the ultrahigh‐pressure metamorphic (UHPM) rocks to the upper crust or surface, forming the UHPM. Influenced by the indentation of the NCB, the "de‐rooting" of the SDO lithosphere, caused the delamination and thinning of the lithosphere, accompanied by the continuous flexural subsidence in the HB. The basin underwent at least four stages of tectonic evolution, involving sequentially: the flexural basin, the foreland basin, the strike‐slip‐related basin, and the faulted graben development periods. The tectonic evolution of the HB was closely coupled with the SDO orogeny. The "de‐rooting" of the SDO lithosphere resulted in a strong uplift and erosion of the orogen, providing abundant source of material for the HB and causing the successively northwards migration of basin depocenters at its early stage. Finally, influenced by the subduction retreat of the (Palaeo‐) Pacific Plate and the strike‐slip movement of the Tanlu Fault, the depocenters migrated to the east. [ABSTRACT FROM AUTHOR]

In order to quantitatively analyze the relationship between the phreatic evaporation and water surface evaporation of different soil textures in bare soil area, soils with different texture and sand samples were taken from the test site in Hefei University of Technology. After pretreatment such as drying and particles sieving, 4 types of homogeneous test materials were selected including coarse sand, fine sand, loam and sand soil. Then, a self-made phreatic evaporation measurement device was made with diameters of 60 and 25 mm and a height of 42 mm. It can easily solve the problem of automatic water replenishment during the evaporation process, so that the groundwater depth can always be 0. Based on the self-designed device, a total of 5 groups of comparative test schemes were constructed, including coarse sand, fine sand, loam, sandy soil and water in bare soil area. Under the same environmental conditions, daily phreatic evaporation of the 4 different soil textures and water surface evaporation were observed for a total of 127 days from December 24, 2018 to April 29, 2019. By analyzing the relationship between phreatic evaporation and water surface evaporation for soils with different textures, linear mathematical equations were established. The results revealed that the change trend of phreatic evaporation and water surface evaporation was basically the same during the experiment. The high air temperature would lead to larger soil evaporation. However, the phreatic evaporation of the 4 different soil textures was not equal to the water surface evaporation, and the difference between them was more significant as the air temperature was increased. The determination coefficients between phreatic evaporation value of different soil textures and the water surface evaporation were all greater than 0.97. Especially for fine sand, the correlation coefficient reached 0.99, which indicated that there was a significant correlation between phreatic evaporation and water surface evaporation (P<0.05). And the conversion coefficients were achieved between them according to the linear mathematical equations. Generally, in soil bare areas with similar climatic conditions in Hefei, the conversion coefficient of coarse sand was 0.94, and the coefficients of fine sand, loam and sand are 1.04, 1.14 and 1.19, respectively. The phreatic evaporation value of coarse sand was less than the evaporation of water surface. The phreatic evaporation values of fine sand, loam and sand were greater than water evaporation. Under bare soil conditions, this conversion coefficient was only related to soil texture. In addition, the loam and sandy soil evaporation in the Wudaogou test site of Anhui Province, China was selected to verify the rationality of the conversion coefficient obtained above. The results showed that when the groundwater depth was 0.4 m, the relative error of the loam evaporation calculated by the substitution method and the phreatic evaporation coefficient method were -10.30% and 2.25%, respectively. Moreover, the sand evaporation calculated by the substitution method was 5.11 mm smaller than the measured value with a relative error of -17.79%, while the sand evaporation calculated using the phreatic evaporation coefficient method was only less than the measured value of 0.56 mm, and the relative error was reduced to -1.94%. Therefore, when calculating the phreatic evaporation at different groundwater depths, directly replacing phreatic evaporation with water surface evaporation would inevitably cause larger relative errors. However, the relative error of the calculation result obtained from the phreatic evaporation coefficient method was smaller, and the calculated value was much closer to the measured value. The coefficient method proposed in this paper would significantly improve the reliability and accuracy of the calculation results of phreatic evaporation. [ABSTRACT FROM AUTHOR]