To investigate the vibration response of the comprehensive transportation hub structure under multiple-source excitations,an on-site vibration measurement was carried out at Wuhan Railway Station in China.The characte...To investigate the vibration response of the comprehensive transportation hub structure under multiple-source excitations,an on-site vibration measurement was carried out at Wuhan Railway Station in China.The characteristics of each floor vibration were obtained through the time domain and frequency domain analyses.Based on the vibration characteristic under multiple-source excitations,the proposed attenuation model was derived.In addition,a vibration comfort evaluation on the Wuhan Railway Station was conducted.The results show that the effect of the number of vibration sources on horizontal acceleration is more significant than that regarding vertical acceleration.When the structure is under the effects two vibration sources with different frequencies,a high-frequency vibration can amplify a low-frequency vibration.The derived attenuation model can precisely predict the vibration attenuation and reduce the subsequent vibration test workload.Based on the annoyance rate model result,the annoyance rate of Wuhan Railway Station is high,which is harmful to the staff of the station.展开更多
The metabolic evolution model of transportation demand for comprehensive transportation systems is put forward on the basis of a metabolic theory of ecology. In the model, the growth rates or changing rates of transpo...The metabolic evolution model of transportation demand for comprehensive transportation systems is put forward on the basis of a metabolic theory of ecology. In the model, the growth rates or changing rates of transportation volumes for the various transportation modes of a city are determined not only by the GDP per capita which reflects the size of the city itself, but also by the relationship of competition and cooperation among transportation modes. The results of empirical analysis for Chinese cities show that the allometric growth exponent in the equation for the variation rate of passenger demand volume on rail is greater than the predicted value of 1/4 in metabolic ecology, whereas the allometric growth relationship is not so evident in the equation for the variation rate of passenger demand volume on road. The changing rate of road transportation is thus mainly affected by the relationship of competition and cooperation among transportation modes for Chinese cities.展开更多
In recent years,research investigations have focused on the substantial freshwater storage in the Beaufort Gyre(BG)region due to climate change.Despite active mesoscale eddies in the area,a notable gap in understandin...In recent years,research investigations have focused on the substantial freshwater storage in the Beaufort Gyre(BG)region due to climate change.Despite active mesoscale eddies in the area,a notable gap in understanding the three-dimensional structure and induced transport has been observed.This study concentrates on the Canada Basin in the western Arctic Ocean,specifically examining a subsurface anticyclonic eddy(SAE)sampled by a Mooring A in the BG region.Hybrid Coordinate Ocean Model(HYCOM)analysis data reveal its lifecycle from February 15 to March 15,2017,marked by initiation,development,maturity,decay,and termination stages.This work extends the finding of SAE passing through Mooring A by examining its overall effects,spatiotemporal variations,and swirl transport.SAE generation through baroclinic instability,which contributes to the westward tilt of the vertical axis,is also confirmed in this study.Swirl transport induced by SAE is predominantly eastward and downward due to its trajectory and background flow.SAE temporarily weakens stratification and extends the subsurface depth but demonstrates transient effects.Moreover,SAE transports upper-layer freshwater,Pacific Winter Water,and Atlantic Water downward,emphasizing its potential influence on freshwater redistribution in the Canadian Basin.This research provides valuable insights into mesoscale eddy dynamics,revealing their role in modulating the upper water mass in the BG region.展开更多
The Changjiang River (Yangtze) is one of the fastest growth areas of container transportation in China. Rail, road and water transportation have competed against each other for container transportation in the Chang-ji...The Changjiang River (Yangtze) is one of the fastest growth areas of container transportation in China. Rail, road and water transportation have competed against each other for container transportation in the Chang-jiang River main line and its delta area. It is of significance to assess these different transportation modes scientifically in order to organize container transportation efficiently in this area and make decision for integral plan and construction of transportation system in this area. This paper outlines application of fuzzy comprehensive evaluation to appraise different modes of typical direction of containers. Twelve assessment indexes were decided. Membership functions were formulated. Evaluation results indicated that road transportation was optimal mode in the Changjiang River delta area, however water transportation was the primary way in the Changjiang River main line.展开更多
It is urgent and important to explore the dynamic evolution in comprehensive transportation green efficiency(CTGE)in the context of green development.We constructed a social development index that reflects the social ...It is urgent and important to explore the dynamic evolution in comprehensive transportation green efficiency(CTGE)in the context of green development.We constructed a social development index that reflects the social benefits of transportation services,and incorporated it into the comprehensive transportation efficiency evaluation framework as an expected output.Based on the panel data of 30 regions in China from 2003-2018,the CTGE in China was measured using the slacks-based measure-data envelopment analysis(SBM-DEA)model.Further,the dynamic evolution trends of CTGE were determined using the spatial Markov model and exploratory spatio-temporal data analysis(ESTDA)technique from a spatio-temporal perspective.The results showed that the CTGE shows a U-shaped change trend but with an overall low level and significant regional differences.The state transition of CTGE has a strong spatial dependence,and there exists the phenomenon of“club convergence”.Neighbourhood background has a significant impact on the CTGE transition types,and the spatial spillover effect is pronounced.The CTGE has an obvious positive correlation and spatial agglomeration characteristics.The geometric characteristics of the LISA time path show that the evolution process of local spatial structure and local spatial dependence of China’s CTGE is stable,but the integration of spatial evolution is weak.The spatio-temporal transition results of LISA indicate that the CTGE has obvious transfer inertness and has certain path-dependence and spatial locking characteristics,which will become the major difficulty in improving the CTGE.展开更多
Launching the evaluation research of green transportation can grasp the green transportation implementation accurately and diagnose the existing problems. From the perspective of green transportation, this research ch...Launching the evaluation research of green transportation can grasp the green transportation implementation accurately and diagnose the existing problems. From the perspective of green transportation, this research chose Dongguan “motorcycle ban” policy as the research object, and constructed secondary evaluation index system in transportation and environmental harmony, transportation and future harmony, transportation and society harmony, transportation and resource harmony, four dimensions. Then it used fuzzy comprehensive evaluation model to do the evaluation and found that the policy’s positive effect on the Dongguan green transportation development was average. Finally, based on the evaluation results, measures and advices were proposed.展开更多
Changes in the water cycle on the Tibetan Plateau(TP)have a significant impact on local agricultural production and livelihoods and its downstream regions.Against the background of widely reported warming and wetting,...Changes in the water cycle on the Tibetan Plateau(TP)have a significant impact on local agricultural production and livelihoods and its downstream regions.Against the background of widely reported warming and wetting,the hydrological cycle has accelerated and the likelihood of extreme weather events and natural disasters occurring(i.e.,snowstorms,floods,landslides,mudslides,and ice avalanches)has also intensified,especially in the highelevation mountainous regions.Thus,an accurate estimation of the intensity and variation of each component of the water cycle is an urgent scientific question for the assessment of plateau environmental changes.Following the transformation and movement of water between the atmosphere,biosphere and hydrosphere,the authors highlight the urgent need to strengthen the three-dimensional comprehensive observation system(including the eddy covariance system;planetary boundary layer tower;profile measurements of temperature,humidity,and wind by microwave radiometers,wind profiler,and radiosonde system;and cloud and precipitation radars)in the TP region and propose a practical implementation plan.The construction of such a three-dimensional observation system is expected to promote the study of environmental changes and natural hazards prevention.展开更多
The essential for microseismic monitoring is fast and accurate calculation of seismic wave source location. The precision of most traditional microseismic monitoring processes of mines, using TDOA location method in t...The essential for microseismic monitoring is fast and accurate calculation of seismic wave source location. The precision of most traditional microseismic monitoring processes of mines, using TDOA location method in two-dimensional space to position the microseismic events, as well as the accuracy of positioning microseismic events, may be reduced by the two-dimensional model and simple method, and ill-conditioned equations produced by TDOA location method will increase the positioning error. This article, based on inversion theory, studies the mathematical model of TDOA location method, polariza- tion analysis location method, and comprehensive difference location method of adding angle factor in the traditional TDOA location method. The feasibility of three methods is verified by numerical simulation and analysis of the positioning error of them. The results show that the comprehensive location method of adding angle difference has strong positioning stability and high positioning accuracy, and it may reduce the impact effectively about ill-conditioned equations to positioning results. Comprehensive location method with the data of actual measure may get better positioning results.展开更多
The comprehensive transportation project involves with many different transportation methods, such as railway, highway, waterway, airline, and pipeline, which have their special characteristics. To evaluate the transp...The comprehensive transportation project involves with many different transportation methods, such as railway, highway, waterway, airline, and pipeline, which have their special characteristics. To evaluate the transporta- tion project with different transportation methods under the same system, the integrated evaluation method should be built up on the basis of a common index system. This paper suggests a feasible integrated evaluation method including index system establishing, indices transacting, the index weight distributing, and weighted value integrating.展开更多
The target of integrated construction of comprehensive transportation hub is to integrate the traffic resources,achieve butt joint of pan-regional transportation mode,and finally realize the"seamless connection&q...The target of integrated construction of comprehensive transportation hub is to integrate the traffic resources,achieve butt joint of pan-regional transportation mode,and finally realize the"seamless connection"of the goods and"zero transfer"of the passenger traffic.Relying on the particularity of the geographical location and the convenience of the Yangtze River channel,Luzhou puts forth effort to build a comprehensive transport hub in Southern Sichuan and has made great efforts in traffic infrastructure construction.However,there are still some problems.Combining practice of Luzhou,using the advanced experience of foreign and domestic cities for reference,the paper pointed out that for the sake of constructing a comprehensive transportation hub,we need to build the traffic integration on the basis of the efficiency.Besides,the paper proposed the strategies for construction.展开更多
The target of integrated construction of comprehensive transportation hub is to integrate the traffi c resources, achieve butt jointof pan-regional transportation mode, and fi nally realize the “seamless connection”...The target of integrated construction of comprehensive transportation hub is to integrate the traffi c resources, achieve butt jointof pan-regional transportation mode, and fi nally realize the “seamless connection”of the goods and “zero transfer” of the passenger traffi c.Relying on the particularity of the geographical location and the convenience of the Yangtze River channel, Luzhou puts forth effort to build acomprehensive transport hub in Southern Sichuan and has made great efforts in traffi c infrastructure construction. However, there are still someproblems. Combining practice of Luzhou, using the advanced experience of foreign and domestic cities for reference, the paper pointed out thatfor the sake of constructing a comprehensive transportation hub, we need to build the traffi c integration on the basis of the effi ciency. Besides, thepaper proposed the strategies for construction.展开更多
Comprehensive transportation evaluation objects using multi-objective decision method is a process of choosing the best one from a few objects through calculating, analyzing, and comparing the index system. The result...Comprehensive transportation evaluation objects using multi-objective decision method is a process of choosing the best one from a few objects through calculating, analyzing, and comparing the index system. The result may be different because of the difference of the index weight and index value. Therefore, sensitivity analysis should be one of the necessary parts of the decision-making. It is desired to give the index with higher sensitivity and its varying scope to control the index strictly during the execution process. This paper derives transfer index weight, which changes the rank evaluation order of the projects. Meanwhile, a simple, effective and practical method based on sensitivity district and sensitivity matrix is proposed for the sensitivity analysis of decision-making. As an example, the index sensitivity in decision-making of some provinces comprehensive transportation objects, and their influence on the final decision are discussed.展开更多
Trunk roads play an important role in undertaking high-grade roads and connecting Qixia County, township and rural roads in road traffic. At present, it has been transformed from the decline of construction bonus to a...Trunk roads play an important role in undertaking high-grade roads and connecting Qixia County, township and rural roads in road traffic. At present, it has been transformed from the decline of construction bonus to a new era of increased maintenance. As the manager and maintainer of road traffic, how to do a good job in the comprehensive and three-dimensional maintenance of the road itself and the surrounding environment, so as to achieve the real meaning of "Chang'an, Shu'Mei",It is one of the important issues that highway managers and maintainers should consider as highway high-quality development. This paper shares the management experience in recent years for peer reference only.展开更多
The Chengdu-Chongqing twin city economic circle has become a national strategy.As the westwards gateway of Chongqing central city,the High-tech Zone should further strengthen its traffic integration and interconnectiv...The Chengdu-Chongqing twin city economic circle has become a national strategy.As the westwards gateway of Chongqing central city,the High-tech Zone should further strengthen its traffic integration and interconnectivity with the Chengdu-Chongqing main Corridor.Combining the design concept and functional positioning of Jinfeng Hub,the research should be carried out from the aspects of hub scale control,three-dimensional spatial layout,rail transit connection,road collection and distribution system construction,and integrated development with the city.It is expected to provide a good reference for the planning and design of modern integrated transportation hub.展开更多
A three-dimensional transportation model for suspended solids (SS) in Zhujiang (Pearl) River estuary, South China, was developed by coupling with a three-dimensional hydrodynamic model. The model was validated using h...A three-dimensional transportation model for suspended solids (SS) in Zhujiang (Pearl) River estuary, South China, was developed by coupling with a three-dimensional hydrodynamic model. The model was validated using hourly measured data of sediment contents during 25–26, July 1999. The results showed that modeled contents matched well with measured ones and that the modeled top layer distribution agreed with the remotely sensed image of suspended solids in summer. The modeled results showed clearly the layers of sus- pended solids in depth, with larger sediment contents in lower layers though in the interface between salt water and freshwater the lowest contents appeared in middle layer. In overall, the suspended solids inflow from 8 rivers, transport southwestward, and carried by strong coastal flow in Zhujiang River estuary. Contours of sediment contents in the estuary spread further to the open sea during ebb tide rather than flood tide which reflects that the suspended solids in the estuary are land sourced.展开更多
The calculation of flow and sediment transport is one of the most important tasks in river engineering. The task is particularly difficult because a number of complex physical phenomena should be accounted for more re...The calculation of flow and sediment transport is one of the most important tasks in river engineering. The task is particularly difficult because a number of complex physical phenomena should be accounted for more realistically in a model with a predictive power. Three-dimensional calculations of river flow and suspended sediment transport are performed in this paper with application in the Three Gorges Reservoir in the Yangtze River. A period of 76 years after the dam is built is simulated and the results are compared with laboratory measurements obtained by Tsinghua University whereby the model is verified and calibrated. Generally speaking, the calculated results agree well with the experiments, demonstrating that the present model can be used for flow and sediment transport prediction in rivers.展开更多
As mass transport mechanisms,the spreading and mixing(dilution) processes of miscible contaminated compounds are fundamental to understanding reactive transport behaviors and transverse dispersion.In this study,the sp...As mass transport mechanisms,the spreading and mixing(dilution) processes of miscible contaminated compounds are fundamental to understanding reactive transport behaviors and transverse dispersion.In this study,the spreading and dilution processes of a miscible contaminated compound in a three-dimensional self-affine rough fracture were simulated with the coupled lattice Boltzmann method(LBM).Moment analysis and the Shannon entropy(dilution index) were employed to analyze the spreading and mixing processes,respectively.The corresponding results showed that the spreading process was anisotropic due to the heterogeneous aperture distribution.A compound was transported faster in a large aperture region than in a small aperture region due to the occurrence of preferential flow.Both the spreading and mixing processes were highly dependent on the fluid flow velocity and molecular diffusion.The calculated results of the dilution index showed that increasing the fluid flow velocity and molecular diffusion coefficient led to a higher increasing rate of the dilution index.展开更多
An optimization model for the regional comprehensive freight hub location problem was built up from the viewpoint of the minimum cost of freight system. The construction method for regional comprehensive intermodal fr...An optimization model for the regional comprehensive freight hub location problem was built up from the viewpoint of the minimum cost of freight system. The construction method for regional comprehensive intermodal freight network was put forward, and three constraints of the reasonable and feasible path of the intermodal transport, i. e. , reasonable sequence, reasonable freight distance, and reasonable conversion times, were proposed according to the general concepts of the intermodal freight. Then the method for solving the model was given based on the super network and genetic algorithm. Finally, the model and the solution were verified by case study.展开更多
Stereoscopic particle image velocimetry technology was employed to investigate the planar three-dimensional velocity field and the process of proppant entry into branch fractures in a fracture configuration of“vertic...Stereoscopic particle image velocimetry technology was employed to investigate the planar three-dimensional velocity field and the process of proppant entry into branch fractures in a fracture configuration of“vertical main fracture-vertical branch fracture”intersecting at a 90°angle.This study analyzed the effects of pumping rate,fracturing fluid viscosity,proppant particle size,and fracture width on the transport behavior of proppant into branch fractures.Based on the deflection behavior of proppant,the main fractures can be divided into five regions:pre-entry transition,pre-entry stabilization,deflection entry at the fracture mouth,rear absorption entry,and movement away from the fracture mouth.Proppant primarily deflects into the branch fracture at the fracture mouth,with a small portion drawn in from the rear of the intersection.Increasing the pumping rate,reducing the proppant particle size,and widening the branch fracture are conducive to promoting proppant deflection into the branch.With increasing fracturing fluid viscosity,the ability of proppant to enter the branch fracture first improves and then declines,indicating that excessively high viscosity is unfavorable for proppant entry into the branch.During field operations,a high pumping rate and micro-to small-sized proppant can be used in the early stage to ensure effective placement in the branch fractures,followed by medium-to large-sized proppant to ensure adequate placement in the main fracture and enhance the overall conductivity of the fracture network.展开更多
基金Science Fund for Distinguished Young Scholars of Hubei Province under Grant No.2023AFA103National Natural Science Foundation of China under Grant No.52078395+1 种基金Open Projects Foundation of State Key Laboratory for Health and Safety of Bridge Structures under Grant No.BHSKL19-07-GFYoung Top-Notch Talent Cultivation Program of Hubei Province。
文摘To investigate the vibration response of the comprehensive transportation hub structure under multiple-source excitations,an on-site vibration measurement was carried out at Wuhan Railway Station in China.The characteristics of each floor vibration were obtained through the time domain and frequency domain analyses.Based on the vibration characteristic under multiple-source excitations,the proposed attenuation model was derived.In addition,a vibration comfort evaluation on the Wuhan Railway Station was conducted.The results show that the effect of the number of vibration sources on horizontal acceleration is more significant than that regarding vertical acceleration.When the structure is under the effects two vibration sources with different frequencies,a high-frequency vibration can amplify a low-frequency vibration.The derived attenuation model can precisely predict the vibration attenuation and reduce the subsequent vibration test workload.Based on the annoyance rate model result,the annoyance rate of Wuhan Railway Station is high,which is harmful to the staff of the station.
基金The Ph.D.Programs Foundation of Ministry of Education of China(No.20060286005)China Postdoctoral Science Foundation(No.20070411018)
文摘The metabolic evolution model of transportation demand for comprehensive transportation systems is put forward on the basis of a metabolic theory of ecology. In the model, the growth rates or changing rates of transportation volumes for the various transportation modes of a city are determined not only by the GDP per capita which reflects the size of the city itself, but also by the relationship of competition and cooperation among transportation modes. The results of empirical analysis for Chinese cities show that the allometric growth exponent in the equation for the variation rate of passenger demand volume on rail is greater than the predicted value of 1/4 in metabolic ecology, whereas the allometric growth relationship is not so evident in the equation for the variation rate of passenger demand volume on road. The changing rate of road transportation is thus mainly affected by the relationship of competition and cooperation among transportation modes for Chinese cities.
基金support of the Fundamental Research Funds for the Central Universities(No.E2ET0411X2).
文摘In recent years,research investigations have focused on the substantial freshwater storage in the Beaufort Gyre(BG)region due to climate change.Despite active mesoscale eddies in the area,a notable gap in understanding the three-dimensional structure and induced transport has been observed.This study concentrates on the Canada Basin in the western Arctic Ocean,specifically examining a subsurface anticyclonic eddy(SAE)sampled by a Mooring A in the BG region.Hybrid Coordinate Ocean Model(HYCOM)analysis data reveal its lifecycle from February 15 to March 15,2017,marked by initiation,development,maturity,decay,and termination stages.This work extends the finding of SAE passing through Mooring A by examining its overall effects,spatiotemporal variations,and swirl transport.SAE generation through baroclinic instability,which contributes to the westward tilt of the vertical axis,is also confirmed in this study.Swirl transport induced by SAE is predominantly eastward and downward due to its trajectory and background flow.SAE temporarily weakens stratification and extends the subsurface depth but demonstrates transient effects.Moreover,SAE transports upper-layer freshwater,Pacific Winter Water,and Atlantic Water downward,emphasizing its potential influence on freshwater redistribution in the Canadian Basin.This research provides valuable insights into mesoscale eddy dynamics,revealing their role in modulating the upper water mass in the BG region.
文摘The Changjiang River (Yangtze) is one of the fastest growth areas of container transportation in China. Rail, road and water transportation have competed against each other for container transportation in the Chang-jiang River main line and its delta area. It is of significance to assess these different transportation modes scientifically in order to organize container transportation efficiently in this area and make decision for integral plan and construction of transportation system in this area. This paper outlines application of fuzzy comprehensive evaluation to appraise different modes of typical direction of containers. Twelve assessment indexes were decided. Membership functions were formulated. Evaluation results indicated that road transportation was optimal mode in the Changjiang River delta area, however water transportation was the primary way in the Changjiang River main line.
基金National Key Research and Development Program of China(2019YFB1600400)National Natural Science Foundation of China(72174035)+2 种基金National Natural Science Foundation of China(71774018)Liaoning Revitalization Talents Program(XLYC2008030)Liaoning Provincial Natural Science Foundation Shipping Joint Foundation Program(2020-HYLH-20)。
文摘It is urgent and important to explore the dynamic evolution in comprehensive transportation green efficiency(CTGE)in the context of green development.We constructed a social development index that reflects the social benefits of transportation services,and incorporated it into the comprehensive transportation efficiency evaluation framework as an expected output.Based on the panel data of 30 regions in China from 2003-2018,the CTGE in China was measured using the slacks-based measure-data envelopment analysis(SBM-DEA)model.Further,the dynamic evolution trends of CTGE were determined using the spatial Markov model and exploratory spatio-temporal data analysis(ESTDA)technique from a spatio-temporal perspective.The results showed that the CTGE shows a U-shaped change trend but with an overall low level and significant regional differences.The state transition of CTGE has a strong spatial dependence,and there exists the phenomenon of“club convergence”.Neighbourhood background has a significant impact on the CTGE transition types,and the spatial spillover effect is pronounced.The CTGE has an obvious positive correlation and spatial agglomeration characteristics.The geometric characteristics of the LISA time path show that the evolution process of local spatial structure and local spatial dependence of China’s CTGE is stable,but the integration of spatial evolution is weak.The spatio-temporal transition results of LISA indicate that the CTGE has obvious transfer inertness and has certain path-dependence and spatial locking characteristics,which will become the major difficulty in improving the CTGE.
文摘Launching the evaluation research of green transportation can grasp the green transportation implementation accurately and diagnose the existing problems. From the perspective of green transportation, this research chose Dongguan “motorcycle ban” policy as the research object, and constructed secondary evaluation index system in transportation and environmental harmony, transportation and future harmony, transportation and society harmony, transportation and resource harmony, four dimensions. Then it used fuzzy comprehensive evaluation model to do the evaluation and found that the policy’s positive effect on the Dongguan green transportation development was average. Finally, based on the evaluation results, measures and advices were proposed.
基金This research was jointly funded by the Second Tibetan Plateau Scientific Expedition and Research Program(Grant Nos.2019QZKK0103 and 2019QZKK0105)the National Natural Science Foundation of China(Grant Nos.91837208 and 42075085).
文摘Changes in the water cycle on the Tibetan Plateau(TP)have a significant impact on local agricultural production and livelihoods and its downstream regions.Against the background of widely reported warming and wetting,the hydrological cycle has accelerated and the likelihood of extreme weather events and natural disasters occurring(i.e.,snowstorms,floods,landslides,mudslides,and ice avalanches)has also intensified,especially in the highelevation mountainous regions.Thus,an accurate estimation of the intensity and variation of each component of the water cycle is an urgent scientific question for the assessment of plateau environmental changes.Following the transformation and movement of water between the atmosphere,biosphere and hydrosphere,the authors highlight the urgent need to strengthen the three-dimensional comprehensive observation system(including the eddy covariance system;planetary boundary layer tower;profile measurements of temperature,humidity,and wind by microwave radiometers,wind profiler,and radiosonde system;and cloud and precipitation radars)in the TP region and propose a practical implementation plan.The construction of such a three-dimensional observation system is expected to promote the study of environmental changes and natural hazards prevention.
文摘The essential for microseismic monitoring is fast and accurate calculation of seismic wave source location. The precision of most traditional microseismic monitoring processes of mines, using TDOA location method in two-dimensional space to position the microseismic events, as well as the accuracy of positioning microseismic events, may be reduced by the two-dimensional model and simple method, and ill-conditioned equations produced by TDOA location method will increase the positioning error. This article, based on inversion theory, studies the mathematical model of TDOA location method, polariza- tion analysis location method, and comprehensive difference location method of adding angle factor in the traditional TDOA location method. The feasibility of three methods is verified by numerical simulation and analysis of the positioning error of them. The results show that the comprehensive location method of adding angle difference has strong positioning stability and high positioning accuracy, and it may reduce the impact effectively about ill-conditioned equations to positioning results. Comprehensive location method with the data of actual measure may get better positioning results.
文摘The comprehensive transportation project involves with many different transportation methods, such as railway, highway, waterway, airline, and pipeline, which have their special characteristics. To evaluate the transporta- tion project with different transportation methods under the same system, the integrated evaluation method should be built up on the basis of a common index system. This paper suggests a feasible integrated evaluation method including index system establishing, indices transacting, the index weight distributing, and weighted value integrating.
文摘The target of integrated construction of comprehensive transportation hub is to integrate the traffic resources,achieve butt joint of pan-regional transportation mode,and finally realize the"seamless connection"of the goods and"zero transfer"of the passenger traffic.Relying on the particularity of the geographical location and the convenience of the Yangtze River channel,Luzhou puts forth effort to build a comprehensive transport hub in Southern Sichuan and has made great efforts in traffic infrastructure construction.However,there are still some problems.Combining practice of Luzhou,using the advanced experience of foreign and domestic cities for reference,the paper pointed out that for the sake of constructing a comprehensive transportation hub,we need to build the traffic integration on the basis of the efficiency.Besides,the paper proposed the strategies for construction.
文摘The target of integrated construction of comprehensive transportation hub is to integrate the traffi c resources, achieve butt jointof pan-regional transportation mode, and fi nally realize the “seamless connection”of the goods and “zero transfer” of the passenger traffi c.Relying on the particularity of the geographical location and the convenience of the Yangtze River channel, Luzhou puts forth effort to build acomprehensive transport hub in Southern Sichuan and has made great efforts in traffi c infrastructure construction. However, there are still someproblems. Combining practice of Luzhou, using the advanced experience of foreign and domestic cities for reference, the paper pointed out thatfor the sake of constructing a comprehensive transportation hub, we need to build the traffi c integration on the basis of the effi ciency. Besides, thepaper proposed the strategies for construction.
文摘Comprehensive transportation evaluation objects using multi-objective decision method is a process of choosing the best one from a few objects through calculating, analyzing, and comparing the index system. The result may be different because of the difference of the index weight and index value. Therefore, sensitivity analysis should be one of the necessary parts of the decision-making. It is desired to give the index with higher sensitivity and its varying scope to control the index strictly during the execution process. This paper derives transfer index weight, which changes the rank evaluation order of the projects. Meanwhile, a simple, effective and practical method based on sensitivity district and sensitivity matrix is proposed for the sensitivity analysis of decision-making. As an example, the index sensitivity in decision-making of some provinces comprehensive transportation objects, and their influence on the final decision are discussed.
文摘Trunk roads play an important role in undertaking high-grade roads and connecting Qixia County, township and rural roads in road traffic. At present, it has been transformed from the decline of construction bonus to a new era of increased maintenance. As the manager and maintainer of road traffic, how to do a good job in the comprehensive and three-dimensional maintenance of the road itself and the surrounding environment, so as to achieve the real meaning of "Chang'an, Shu'Mei",It is one of the important issues that highway managers and maintainers should consider as highway high-quality development. This paper shares the management experience in recent years for peer reference only.
基金The 2024 Chongqing Municipal Education Commission Science and Technology Research Project,“Research on the Planning and Design of Modern Comprehensive Transportation Hubs under the Background of the Construction of the Chengdu-Chongqing Twin-City Economic Circle:A Case Study of Jinfeng Hub in Chongqing High-tech Zone”(Project No.:KJQN202405604).
文摘The Chengdu-Chongqing twin city economic circle has become a national strategy.As the westwards gateway of Chongqing central city,the High-tech Zone should further strengthen its traffic integration and interconnectivity with the Chengdu-Chongqing main Corridor.Combining the design concept and functional positioning of Jinfeng Hub,the research should be carried out from the aspects of hub scale control,three-dimensional spatial layout,rail transit connection,road collection and distribution system construction,and integrated development with the city.It is expected to provide a good reference for the planning and design of modern integrated transportation hub.
基金This research was funded by The National Science Fund for Distin-guished Young Scholars (Estuarine and Coastal Studies 40225014) and The National Hi-Tech Research Fund (818-09-01-04).
文摘A three-dimensional transportation model for suspended solids (SS) in Zhujiang (Pearl) River estuary, South China, was developed by coupling with a three-dimensional hydrodynamic model. The model was validated using hourly measured data of sediment contents during 25–26, July 1999. The results showed that modeled contents matched well with measured ones and that the modeled top layer distribution agreed with the remotely sensed image of suspended solids in summer. The modeled results showed clearly the layers of sus- pended solids in depth, with larger sediment contents in lower layers though in the interface between salt water and freshwater the lowest contents appeared in middle layer. In overall, the suspended solids inflow from 8 rivers, transport southwestward, and carried by strong coastal flow in Zhujiang River estuary. Contours of sediment contents in the estuary spread further to the open sea during ebb tide rather than flood tide which reflects that the suspended solids in the estuary are land sourced.
基金The project supported by the National Natural Science Foundation of China (50009004)
文摘The calculation of flow and sediment transport is one of the most important tasks in river engineering. The task is particularly difficult because a number of complex physical phenomena should be accounted for more realistically in a model with a predictive power. Three-dimensional calculations of river flow and suspended sediment transport are performed in this paper with application in the Three Gorges Reservoir in the Yangtze River. A period of 76 years after the dam is built is simulated and the results are compared with laboratory measurements obtained by Tsinghua University whereby the model is verified and calibrated. Generally speaking, the calculated results agree well with the experiments, demonstrating that the present model can be used for flow and sediment transport prediction in rivers.
基金supported by the National Natural Science Foundation of China(Grant No.41602239)the Natural Science Foundation of Jiangsu Province(Grant No.BK20160861)+2 种基金the Fundamental Research Funds for the Central Universities(Grant No.2016B05514)the International Postdoctoral Exchange Fellowship Program from the Office of China Postdoctoral Council(Grant No.20150048)the"333 Project"of Jiangsu Province(Grant No.BRA2015305)
文摘As mass transport mechanisms,the spreading and mixing(dilution) processes of miscible contaminated compounds are fundamental to understanding reactive transport behaviors and transverse dispersion.In this study,the spreading and dilution processes of a miscible contaminated compound in a three-dimensional self-affine rough fracture were simulated with the coupled lattice Boltzmann method(LBM).Moment analysis and the Shannon entropy(dilution index) were employed to analyze the spreading and mixing processes,respectively.The corresponding results showed that the spreading process was anisotropic due to the heterogeneous aperture distribution.A compound was transported faster in a large aperture region than in a small aperture region due to the occurrence of preferential flow.Both the spreading and mixing processes were highly dependent on the fluid flow velocity and molecular diffusion.The calculated results of the dilution index showed that increasing the fluid flow velocity and molecular diffusion coefficient led to a higher increasing rate of the dilution index.
基金The National Natural Science Foundation of China (No.50708020)Provincial Natural Science Fund of Jiangsu (BK2007566)
文摘An optimization model for the regional comprehensive freight hub location problem was built up from the viewpoint of the minimum cost of freight system. The construction method for regional comprehensive intermodal freight network was put forward, and three constraints of the reasonable and feasible path of the intermodal transport, i. e. , reasonable sequence, reasonable freight distance, and reasonable conversion times, were proposed according to the general concepts of the intermodal freight. Then the method for solving the model was given based on the super network and genetic algorithm. Finally, the model and the solution were verified by case study.
基金Supported by Joint Funds of the National Natural Science Foundation of China(U23B6004).
文摘Stereoscopic particle image velocimetry technology was employed to investigate the planar three-dimensional velocity field and the process of proppant entry into branch fractures in a fracture configuration of“vertical main fracture-vertical branch fracture”intersecting at a 90°angle.This study analyzed the effects of pumping rate,fracturing fluid viscosity,proppant particle size,and fracture width on the transport behavior of proppant into branch fractures.Based on the deflection behavior of proppant,the main fractures can be divided into five regions:pre-entry transition,pre-entry stabilization,deflection entry at the fracture mouth,rear absorption entry,and movement away from the fracture mouth.Proppant primarily deflects into the branch fracture at the fracture mouth,with a small portion drawn in from the rear of the intersection.Increasing the pumping rate,reducing the proppant particle size,and widening the branch fracture are conducive to promoting proppant deflection into the branch.With increasing fracturing fluid viscosity,the ability of proppant to enter the branch fracture first improves and then declines,indicating that excessively high viscosity is unfavorable for proppant entry into the branch.During field operations,a high pumping rate and micro-to small-sized proppant can be used in the early stage to ensure effective placement in the branch fractures,followed by medium-to large-sized proppant to ensure adequate placement in the main fracture and enhance the overall conductivity of the fracture network.
