作者机构:
[Sheng, Haiquan; Zhou, Lv; Chen, Yukai; Xian, Lingxiao; Ma, Shubian] Guilin Univ Technol, Coll Geomatics & Geoinformat, Guilin 541004, Peoples R China.;[Huang, Changjun] Hunan City Univ, Sch Municipal & Surveying Engn, Yiyang 413000, Peoples R China.;[Yang, Fei] China Univ Min & Technol Beijing, Geosci & Survey Engn Coll, Beijing 100083, Peoples R China.
通讯机构:
[Lv Zhou] C;College of Geomatics and Geoinformation, Guilin University of Technology, Guilin 541004, China
关键词:
InSAR;persistent scatterer;Beijing;plain;Sentinel-1A;time series
摘要:
Abstract: Surface subsidence is a serious threat to human life, buildings and traffic in Beijing. Surface subsidence is closely related to human activities, and human activities in Beijing area showed a decreasing trend during the Corona Virus Disease 2019 (COVID-19). To study surface subsidence in Beijing before and after the COVID-19 outbreak and its causes, a total of 51 Sentinel-1A SAR images covering Beijing from January 2018 to April 2022 were selected to derive subsidence information by Time Series Interferometry Synthetic Aperture Radar (TS-InSAR). The results of surface subsidence in Beijing demonstrate that Changping, Chaoyang, Tongzhou and Daxing Districts exhibited the most serious subsidence phenomenon before the COVID-19 outbreak. The four main subsidence areas form an anti-Beijing Bay that surrounds other important urban areas. The maximum subsidence rate reached −57.0 mm/year. After the COVID-19 outbreak, the main subsidence area was separated into three giant subsidence funnels and several small subsidence funnels. During this period, the maximum subsidence rate was reduced to −43.0 mm/year. Human activity decrease with the COVID-19 outbreak. This study effectively analysed the influence of natural factors on surface subsidence after excluding most of the human factors. The following conclusions are obtained from the analysis: (1) Groundwater level changes, Beijing’s geological structure and infrastructure construction are the main reasons for surface subsidence in Beijing. (2) Seasonal changes in rainfall and temperature indirectly affect groundwater level changes, thereby affecting surface subsidence in the area. (3) The COVID-19 outbreak in early 2020 reduced the payload of Beijing’s transportation facilities. It also slowed down the progress of various infrastructure construction projects in Beijing. These scenarios affected the pressure on the soft land base in Beijing and reduced the surface subsidence trend to some extent. Keywords: InSAR; persistent scatterer; Beijing; plain; Sentinel-1A; time series
期刊:
Frontiers in Environmental Science,2023年11:1270921 ISSN:2296-665X
通讯作者:
Ning, QM
作者机构:
[Ji, Qianfu; Yang, Hua; Zhou, Hui; Song, Qidi; Lai, Nan] Hunan Prov Terr Space Survey & Monitoring Inst, Changsha, Peoples R China.;[Ning, Qimeng; Zeng, Zhiwei; Ning, QM] Hunan City Univ, Coll Architecture & Urban Planning, Yiyang, Peoples R China.
通讯机构:
[Ning, QM ] H;Hunan City Univ, Coll Architecture & Urban Planning, Yiyang, Peoples R China.
关键词:
Urban-water coupling;Water ecological space;Resilience control;digitalization;Dongting Lake area
摘要:
Introduction: The construction of digital governance of national land space depends greatly on the development of a digital model for robust control of water and ecological space. However, how changes to the urban-water coupling relationships affect the resilience control of water ecological space is rarely reported.Methods: The evolution characteristics of urban and water space in the study area from 2000 to 2020 and the correlation between them are analyzed based on the grid analysis using InVEST and Moran'I methods. Based on the theory of human-environment interaction territorial system to provide a theoretical framework to explain the urban and water space. We used digital to construct an resilience control framework in the Dongting Lake area based on the correlation between the urban and water space.Results: The results show that: 1) From 2000 to 2020, the geographical evolution of towns and cities in the research area displayed obvious spatial variation in intensity, indicating a process of expansion and change. The regional and temporal fluctuations of the water conservation function are significant. The mountainous areas in the east, south, and northwest are where the high values of the water conservation function are primarily found. These regions have more vegetation, which increases the water conservation function. 2) According to the results of local binary spatial autocorrelation analysis, it can be seen that from 2000 to 2020, the high-high agglomeration of town space and water-related is mainly distributed in Linxiang City, Yueyang County, Miluo City, Li County, and Yiyang City, and the low-low agglomeration is mainly distributed in Dongting Lake, Datong Lake, and along the Yangtze River. 3) Based on how urban spatial evolution affects water ecological space, we construct a theoretical framework of urban-water coupling and establish a digital model of water ecological space resilience control in the Dongting Lake area from four perspectives: threshold, visualization, dynamics, and intelligence.
摘要:
An accurate estimation of earth pressure on retaining walls is imperative to achieving its design. This paper presents an analytical method framework that considers the effect of plant transpiration relative to the traditional calculation approaches. Specifically, a closed-form solution for one-dimensional steady unsaturated flow considering plant transpiration is incorporated into a representation of effective stress to obtain the changes in matric suction, and effective stress. The representations are used to extend Hooke's law and Rankine's earth pressure theory to determine at-rest, active, and passive earth pressures. Subsequently, the analytical method is used in a series of analysis case studies on the influence of root architecture types, transpiration rates, and soil types on earth pressure, to reveal that it can rapidly obtain the earth pressure. Notably, the effect of plant transpiration on earth pressure is significant. Furthermore, it is found that soil types and transpiration rates have a larger influence than root architecture types. Collectively, the research not only reveals the effect of plant on earth pressure for retaining wall, but also provides a theoretical basis for further exploration of the contribution of plants to the stability of retaining wall.
摘要:
Dopamine (DA) is an important neurotransmitter in human's brain, which has direct connection to diseases like Parkinson's disease, schizophrenia, etc. Therefore, the sensitive and rapid quantitative detection of DA is essential for medical diagnosis and disease prevention. To construct a novel electrochemical sensor for DA detection, nickel-based metal-organic frameworks (Ni-MOF) were synthesized through a hydrothermal method and combined with beta-cyclodextrin. Under optimal experimental conditions, the sensor exhibited a wide linear detection range (0.7-310.2 mu M) and a low detection limit (0.227 mu M). Furthermore, the sensor exhibited satisfactory stability and accuracy in an electrochemical study involving human serum and dopamine hydrochloride injection samples containing DA, and the redox mechanism of the sensor was elucidated. Overall, this study presents a novel electrochemical sensor based on cyclodextrins and MOFs for DA detection.
作者机构:
[Xu, Jun; Li, Xintao; Zheng, Kaihong; Pan, Fusheng; Kang, Yuehua; Zhou, Nan] Guangdong Acad Sci, Inst New Mat, Guangzhou 510650, Peoples R China.;[Zhao, Jun] Hunan City Univ, Sch Mech & Elect Engn, Yiyang 413002, Peoples R China.;[Yang, Hong; Jiang, Bin; Pan, Fusheng] Chongqing Univ, Coll Mat Sci & Engn, Natl Engn Res Ctr Magnesium Alloys, Chongqing 400044, Peoples R China.;[Yang, Hong; Jiang, Bin; Pan, Fusheng] Chongqing Inst Adv Light Met, Chongqing 400030, Peoples R China.;[Liu, Wenjun] Chongqing Univ Technol, Coll Mat Sci & Engn, Chongqing, Peoples R China.
通讯机构:
[Jun Xu] I;[Bin Jiang] N;Institute of New Materials, Guangdong Academy of Sciences, Guangzhou, China<&wdkj&>National Engineering Research Center for Magnesium Alloys, College of Materials Science and Engineering, Chongqing University, Chongqing, China<&wdkj&>Chongqing Institute for Advanced Light Metals, Chongqing, China
摘要:
Mg-3Al-1Zn (AZ31) sheets were produced by transverse gradient extrusion (TGE) process. The flow behavior and dynamic recrystallization during extrusion were systematically analyzed. The microstructures, textures, and mechanical behavior of extruded AZ31 sheet were also analyzed and compared with conventional extruded (CE) sheet. The results showed that fine grain structure and multi-type unique textures were formed in TGE sheet because of the generation of extra flow velocity along transverse direction (TD) and flow velocity gradient along extrusion direction (ED) during extrusion. The basal poles gradually deviated away normal direction (ND) from edge to center of the TGE sheet along TD, and the largest inclination angle at center region reached around 65 degrees. Furthermore, the basal poles inclined from ED to TD 40 degrees-63 degrees, except for the center region of TGE sheet. The TGE sheet presented higher ductility and strain hardening exponent (n-value), but lower yield strength and Lankford value (r-value) in comparison with the CE sheet. Both the basal <a> slip and tensile twins were easy to be activated during deformation, and the largest elongation of 41% and the lowest yield strength of 86.5 MPa were obtained for the ED-center sample in the TGE sheet.
关键词:
parametric analysis;tandem compound piles;bearing capacity;discrete element method;finite difference method
摘要:
The tandem compound piles are a combination of a granular column in the deep section and a concrete pile in the shallow section. This method effectively utilizes the consolidation and densification effects of the granular column, as well as the cementation strength of the concrete material. The granular column acts as a consolidation path, aiding in the densification of the surrounding soil. On the other hand, the concrete pile prevents the bulging deformation that commonly happens in granular columns during field construction. To study the bearing capacity and deformation of the improved foundation with tandem compound piles, a coupled continuum-discrete numerical model was developed in this study. The accuracy of the model was confirmed by comparing its results with experimental measurements. Additionally, a parametric study was conducted, considering three influential factors: (1) cushion thickness and modulus, (2) length, modulus, diameter, and spacing of the tandem compound pile, and (3) soil modulus. The results indicated that reducing the cushion thickness and increasing the cushion modulus allowed the pile to bear more loads. Moreover, increasing the length and modulus of the deep section of the pile reduced deformation and improved the bearing capacity. The pile modulus, however, had a limited effect on enhancing the bearing capacity. It is important to maintain a critical pile spacing of at least twice the pile diameter. Finally, a high modulus of the underlying stratum led to higher vertical and radial stresses in the pile.
摘要:
Sediment is the internal and external source of water environment pollution, so sediment remediation is the premise of water body purification. Sediment microbial fuel cell (SMFC) can remove the organic pollutants in sediment by electroactive microorganisms, compete with methanogens for electrons, and realize resource recycling, methane emission inhibiting and energy recovering. Due to these characteristics, SMFC have attracted wide attention for sediment remediation. In this paper, we comprehensively summarized the recent advances of SMFC in the following areas: (1) The advantages and disadvantages of current applied sediment remediation technologies; (2) The basic principles and influencing factors of SMFC; (3) The application of SMFC for pollutant removal, phosphorus transformation and remote monitoring and power supply; (4) Enhancement strategies for SMFC in sediments remediation such as SMFC coupled with constructed wetland, aquatic plant and iron-based reaction. Finally, we have summarized the drawback of SMFC and discuss the future development directions of applying SMFC for sediment bioremediation.
关键词:
Semiconductors;Nanocomposites;Coaxial CdS@ZnO nanowire array;Photodegradation;Methylene blue
摘要:
Herein, a novel coaxial CdS@ZnO nanowire array catalyst was synthesized by magnetron sputtering and hy-drothermal method. The optimum photocatalytic composite was obtained by controlling the ratio of CdS and ZnO. Take methylene blue (MB) as the model, the CdS@ZnO nanowire array (CdS@ZnO-10) exhibited strong photocatalytic solid activity, and the highest adsorption and photodegradation rate of MB reached 90.38 % in 50 min and 99.13 % in 120 min under simulated sunlight illumination. The mechanism of the heterojunction interface affecting photocatalytic performance was studied. Therefore, the synthesis approach could offer new design and controllable construction of coaxial structure for organic dye pollutant degradation.
摘要:
To maximize improving the tracking wind power output plan and the service life of energy storage systems (ESS), a control strategy is proposed for ESS to track wind power planning output based on model prediction and two-layer fuzzy control. First, based on model predictive control, a model with deviations of grid-connected power from the planned output and the minimum deviation of the remaining capacity of the ESS from the ideal value is established as the target. Then, when the grid-connected power exceeds the allowable deviation band of tracking, the weight coefficients in the objective function are adjusted by introducing the first layer of fuzzy control rules, combining the state of charge (SOC) of the ESS with the dynamic tracking demand of the planned value of wind power. When the grid-connected power is within the tracking allowable deviation band, the second layer of fuzzy control rules is used to correct the charging and discharging power of the ESS to improve its ability to track the future planned deviation while not crossing the limit. By repeatedly correcting the charging and discharging power of the ESS, its safe operation and the multitasking execution of the wind power plan output tracking target are ensured. Finally, taking actual data from a wind farm as an example, tests on a simulation platform of a combined wind-storage power generation system verify the feasibility and superiority of the proposed control strategy.
期刊:
Advances in Civil Engineering,2023年2023 ISSN:1687-8086
通讯作者:
Wang, YK
作者机构:
[Wang, YK; Wang, Yukui; Zhang, Dan] Hunan City Univ, Hunan Engn Res Ctr Dev & Applicat Ceramsite Concre, Yiyang 413099, Peoples R China.;[Yan, Shijun] Hunan City Univ, Coll Mech & Elect Engn, Yiyang 413000, Peoples R China.;[Zhang, Dan] Hunan City Univ, Key Lab Green Bldg & Intelligent Construct Higher, Yiyang 413000, Peoples R China.;[Hu, Zhangqi] Hunan City Univ, Coll Civil Engn, Yiyang 413099, Peoples R China.
通讯机构:
[Wang, YK ] H;Hunan City Univ, Hunan Engn Res Ctr Dev & Applicat Ceramsite Concre, Yiyang 413099, Peoples R China.
关键词:
Introduction;Materials and Methods;Results;Discussion;Conclusion;Abstract;Data Availability;Additional Points;Ethical Approval;Consent;Disclosure;Conflicts of Interests;Authors’ Contributions;Funding Statement;Acknowledgements;Acknowledgments;Supplementary Materials;Reference;Dataset Description;Dataset Files;Abstract;Introduction;Introduction and Materials;Introduction and Methods;Materials;Materials and Methods;Methods;Results;Discussion;Results and Discussion;Discussion and Conclusion;Results and Conclusion;Conclusion;Conclusions;Data Availability;Additional Points;Ethical Approval;Consent;Disclosure;Conflicts of Interest;Authors’ Contributions;Funding Statement;Acknowledgements;Supplementary Materials;References;Appendix;Abbreviations;Preliminaries;Introduction and Preliminaries;Notation;Proof of Theorem;Proofs;Analysis of Results;Examples;Numerical Example;Applications;Numerical Simulation;Model;Model Formulation;Systematic Palaeontology;Nomenclatural Acts;Taxonomic Implications;Experimental;Synthesis;Overview;Characterization;Background;Experimental;Theories;Calculations;Model Verification;Model Implementation;Geographic location;Study Area;Geological setting;Data Collection;Field Testing;Data and Sampling;Dataset;Literature Review;Related Works;Related Work;System Model;Methods and Data;Experimental Results;Results and Analysis;Evaluation;Implementation;Case Presentation;Case Report;Search Terms;Case Description;Case Series;Background;Limitations;Additional Points;Case;Case 1;Case 2 etc.;Concern Details;Retraction Details;Copyright;Related Articles
摘要:
The research group utilized the estimation model of energy consumption capacity for reinforced concrete components without axial force to assess the energy consumption capacity of 92-reinforced concrete components from the PEER database, which were subjected to axial force and bending. The study also examined the impact of design parameters, including longitudinal reinforcement ratio, transverse reinforcement ratio, axial compression ratio, and shear-span ratio, on the estimation results. The research findings revealed that when applying the estimation model of energy consumption capacity for reinforced concrete components without axial force to calculate the energy consumption capacity of reinforced concrete components with axial force, there was a significant deviation rate in the estimation of cumulative energy consumption. The relationship between the deviation rate of cumulative energy consumption and longitudinal reinforcement ratio, axial compression ratio, and shear-span ratio remained unclear. However, a more apparent linear relationship was observed with the transverse reinforcement ratio. By conducting a quantitative analysis of the transverse reinforcement ratio, the researchers proposed an modified estimation model of energy consumption capacity for reinforced concrete components with axial force. Nonetheless, the accuracy of the modified estimation model was found to be high within the range of 0–250,000 kN mm of cumulative energy consumption. For cumulative energy consumption exceeding 250,000 kN mm, further experimental and theoretical research is still required to enhance the reliability of the modified estimation model.
期刊:
Water Supply,2023年23(9):3761–3774. ISSN:1606-9749
通讯作者:
Qian, DY
作者机构:
[Cao, Yanmin] Hunan City Univ, Sch Civil Engn, Yiyang 413000, Hunan, Peoples R China.;[Qian, Dongyue] Tianjin Acad Water Transportat Engn, Minist Transport, Tianjin 300456, Peoples R China.;[Wang, Chongyu] Hunan Water Planning & Design Inst Co Ltd, Changsha 410008, Hunan, Peoples R China.
通讯机构:
[Qian, DY ] T;Tianjin Acad Water Transportat Engn, Minist Transport, Tianjin 300456, Peoples R China.
关键词:
contribution rate;cross city driving force;water quality factor;Xiang River Basin
摘要:
Based on the monthly monitoring data of 16 water quality monitoring stations in the Xiang River Basin from 1990 to 2020, the Mann-Kendall test was used to analyze dissolved oxygen, 5-day biochemical oxygen demand, permanganate index, total phosphorus, ammonia nitrogen, cadmium, arsenic, and hexavalent chromium. The changing trend of nine indicators, including the stepwise regression method, was used to determine the cross city driving force of each water quality index, and the contribution rate (weight) of each driving force was obtained by principal component analysis. The research results show that (1) agriculture in Yongzhou is the main driving force, and its contribution rate is 67.2%; (2) urbanization has a greater impact on the driving process of the water environment in the Xiang River Basin, and its contribution rate is as follows: Changsha (83%) > Hengyang (80.7%) > Pingxiang (63.7%) > Chenzhou (60.9%) > Xiangtan (57.4%) > Zhuzhou (50%) > Loudi (48.5%); (3) the urbanization of Zhuzhou City and Loudi City's urban sewage discharge not only has an impact on the city's water environment, but also drives the water environment in the downstream Xiangtan area. The research results can provide a basis and reference for the study of water environmental governance in the basin.
作者机构:
[Li, Qian; Liu, Mailan; Liu, Honghua; Huang, He; Peng, Han] Hunan Univ Chinese Med, Changsha, Peoples R China.;[Huang, Zhiliang] Hunan City Univ, Yiyang, Peoples R China.;[Wei, Lei] Hunan Inst Sci & Technol, Yueyang, Peoples R China.
通讯机构:
[Liu, ML ] H;Hunan Univ Chinese Med, Changsha, Peoples R China.
摘要:
During mild moxibustion treatment, uncertainties are involved in the operating parameters, such as the moxa-burning temperature, the moxa stick sizes, the stick-to-skin distance, and the skin moisture content. It results in fluctuations in skin surface temperature during mild moxibustion. Existing mild moxibustion treatments almost ignore the uncertainty of operating parameters. The uncertainties lead to excessive skin surface temperature causing intense pain, or over-low temperature reducing efficacy. Therefore, the interval model was employed to measure the uncertainty of the operation parameters in mild moxibustion, and the uncertainty optimization design was performed for the operation parameters. It aimed to provide the maximum thermal penetration of mild moxibustion to enhance efficacy while meeting the surface temperature requirements. The interval uncertainty optimization can fully consider the operating parameter uncertainties to ensure optimal thermal penetration and avoid patient discomfort caused by excessive skin surface temperature. To reduce the computational burden of the optimization solution, a high-precision surrogate model was established through a radial basis neural network (RBNN), and a nonlinear interval model for mild moxibustion treatment was formulated. By introducing the reliability-based possibility degree of interval (RPDI), the interval uncertainty optimization was transformed into a deterministic optimization problem, solved by the genetic algorithm. The results showed that this method could significantly improve the thermal penetration of mild moxibustion while meeting the skin surface temperature requirements, thereby enhancing efficacy.
摘要:
Positron Emission Tomography (PET) holds substantial promise in biomedical research and clinical diagnostics. Nonetheless, PET imaging's constraints, typified by deficient sampling and considerable noise interference, often result in the production of inferior quality reconstructed images. These shortcomings can potentially undermine the clinical utility of the modality. To address this issue, this study introduces a novel image reconstruction algorithm underpinned by Bayesian theory that incorporates the total variation model and the median root prior (MRP) algorithm. The iterative resolution process of the algorithm comprises two stages. Initially, the MRP algorithm is employed for image reconstruction. Subsequently, the total variation model is applied to attenuate noise within the reconstructed image. Simulation outcomes reveal that the proposed algorithm effectively mitigates Poisson noise while preserving critical image details, such as edges. When contrasted with traditional reconstruction algorithms, the proposed approach enhances both the precision and reliability of PET imaging markedly. Thus, the algorithm carries significant potential for clinical application and could substantially improve the quality of PET imaging.
摘要:
Abstract: Scholars often consider the deformation of a foundation pit retaining structure as a significant indicator of its stability. However, the current theoretical prediction formula for pit with pile–anchorretaining structure deformation is not yet perfect. This study utilizes a simplified spatial deformation model of a pile–anchorretaining structure and the principle of minimum potential energy to derive a prediction formula for the retaining structure’s spatial deformation. Afterwards, a numerical simulation model is developed based on actual engineering practices. On-site monitoring data is compared with the results of theoretical calculation formulas and numerical simulation models to validate their applicability. The research findings reveal minimal discrepancies between the theoretical calculation results, numerical simulation outcomes, and on-site monitoring data, indicating a high level of accuracy. Those three results follow consistent rules. The horizontal deformation curve of the crown beam exhibits a ‘V’-shaped distribution, and as the distance from the calculation point to the centerline of the foundation pit decreases, the horizontal deformation of the crown beam increases. The horizontal deformation curve of the pile displays a ‘V’-shaped distribution, and the pile’s horizontal deformation increases as the distance to the centerline of the foundation pit decreases. The research findings indicate that increasing the size and material strength of the crown beam and waist beam has only a limited effect on controlling the retaining structure’s deformation. However, by increasing the size and material strength of the pile, the deformation of the retaining structure can be significantly reduced. Keywords: pile–anchor composite system; spatial deformation; prediction formula; numerical simulation; parameter analysis
摘要:
BACKGROUND: Respiratory mechanics monitoring provides useful information for guiding mechanical ventilation, but many measuring methods are inappropriate for awake patients. This study aimed to evaluate the accuracy of dynamic mechanics estimation using expiratory time constant (RC(exp)) calculation during noninvasivepressure support ventilation (PSV) with air leak in different lung models. METHODS: A Respironics V60 ventilator was connected to an active breathing simulator for modeling five profiles: normal adult, restrictive, mildly and severely obstructive, and mixed obstructive/restrictive. Inspiratory pressure support was adjusted to maintain tidal volumes (V(T)), achieving 5.0, 7.0, and 10.0ml/kg body weight. PEEP was set at 5 cmH(2)O, and the back-up rate was 10bpm. Measurements were conducted at system leaks of 25-28L/min. RC(exp) was estimated from the ratio at 75% exhaled V(T) and flow rate, which was then used to determine respiratory system compliance (C(rs)) and airway resistance (R(aw)). RESULTS: In non-obstructive conditions (R(aw) ≤ 10 cmH(2)O/L/s), the C(rs) was overestimated in the PSV mode. Peak inspiratory and expiratory flow and V(T) increased with PS levels, as calculated C(rs) decreased. In passive breathing, the difference of C(rs) between different V(T) was no significant. Underestimations of inspiratory resistance and expiratory resistance were observed at V(T) of 5.0ml/kg. The difference was minimal at V(T) of 7.0ml/kg. During non-invasive PSV, the estimation of airway resistance with the RC(exp) method was accurately at V(T) of 7.0ml/kg. CONCLUSIONS: The difference between the calculated C(rs) and the preset value was influenced by the volume, status and inspiratory effort in spontaneously breathing.
作者机构:
[Liu, Bin] Hunan Normal Univ, Sch Geog Sci, Changsha 410081, Peoples R China.;[Liu, Bin; Yi, Chun] Hunan City Univ, Coll Architecture & Urban Planning, Yiyang 413000, Peoples R China.;[Liu, Bin; Yi, Chun] Key Lab Digital Urban & Rural Spatial Planning Hun, Yiyang 413000, Peoples R China.;[Lu, Chan] Cent South Univ, Sch Architecture & Art, Changsha 410075, Peoples R China.;[Lu, Chan] Hunan Univ Technol, Sch Urban & Environm, Zhuzhou 412007, Peoples R China.
通讯机构:
[Chan Lu] S;School of Architecture and Art, Central South University, Changsha 410075, China<&wdkj&>School of Urban and Environment, Hunan University of Technology, Zhuzhou 412007, China
关键词:
green and low-carbon;research hotspot;research stage;content system;China;rural area
摘要:
Abstract: Green and low-carbon rural development (GLRD) is becoming an important way to explore sustainable development in rural areas of China. It is significant for the sustainable development of the rural economy and of society to build a rural carbon sink system, advocate low-carbon emissions in rural areas, and promote the development of rural green industries and rural transformation. In this study, the existing knowledge system of GLRD was analyzed using CiteSpace. Keywords related to GLRD and their occurrence frequency were identified using keyword co-occurrence analysis. The knowledge evolution stages of GLRD were explored using citation burst analysis. Thus, the evolution of the research related to GLRD was revealed. The summary of Chinese GLRD-related research literature shows that: (1) according to the CiteSpace analysis, the GLRD research can be divided into three stages: starting, rising, and expanding and deepening; (2) GLRD research has focused on low-carbon development, green development, and then green and low-carbon integrated development, thus forming three major research content systems; (3) GLRD’s research content gradually became rich, as over time, the research focus became increasingly prominent and research integration was gradually strengthened; (4) the GLRD literature still has some limitations, e.g., nonunified measurement standards, insufficient research depth and practical significance, and relatively weak innovative policy research; (5) future research should strengthen the scientific evaluation and prediction of rural green and low-carbon functions. The industrial development pathways and regional characteristic modes of GLRD should be further studied. Innovative GLRD policies should be proposed to provide a theoretical basis and decision-making reference for GLRD and construction. Keywords: green and low-carbon; research hotspot; research stage; content system; China; rural area
摘要:
Abstract: Based on analytical and simulation methods, this paper discusses the path choice behavior of mixed traffic flow with autonomous vehicles, advanced traveler information systems (ATIS) vehicles and ordinary vehicles, aiming to promote the development of autonomous vehicles. Firstly, a bi-level programming model of mixed traffic flow assignments constrained by link capacity is established to minimize travel time. Subsequently, the algorithm based on the incremental allocation method and method of successive averages is proposed to solve the model. Through a numerical example, the road network capacity under different modes is obtained, the impact of market penetration on travel time is analyzed, and the state and characteristics of single equilibrium flow and mixed equilibrium flow are explored. Analysis results show that the road network can be maximized based on saving travel time when all vehicles are autonomous, especially when the autonomous lane is adopted. The travel time can be shortened by increasing the market penetration of autonomous vehicles and ATIS vehicles, while the former is more effective. However, the popularization of autonomous vehicles cannot be realized in the short term; the market penetration of autonomous vehicles and ATIS vehicles can be set to 0.2 and 0.6, respectively, during the introduction period. Keywords: heterogeneous traffic flow; autonomous vehicles; capacity; market penetration; bi-level programming