Maritime transportation is one of the most important and extensive transportation modes in the world. Maritime transportation is the backbone of contemporary world trade and therefore special attention should be paid ...Maritime transportation is one of the most important and extensive transportation modes in the world. Maritime transportation is the backbone of contemporary world trade and therefore special attention should be paid to all subjects concerning this mode of transportation. It is also necessary to complement maritime transportation by other modes, such as rail and/or truck （road）. This article deals with the problems of maritime transportation and provides the summary of recent developments, trends and statistics mainly on transatlantic maritime routes （Europe to US）. Besides maritime transportation, this thesis also reviews the trends and statistics of rail and truck （road） transportation in US and Europe. The authors considers four Czech biggest cities （points of origin）, five European ports, eight US ports and 10 biggest cities in US （points of destination）. The adapted TCMMSP （transnational collaborative multi-mode shipping problem） is applied to this case study and it seeks to solve the transportation of a set of five shipments with unique O-D （origin-destination） pairs and volume. The end of the thesis summarizes the results and analyses the average costs, optimal set volume, optimal shipment routing and port analysis.展开更多
This paper analyzes the key indicators of the impact assessment the teleworking as practice of performing regular work from home or from a location close to home,on reducing the number of travel and reduced carbon emi...This paper analyzes the key indicators of the impact assessment the teleworking as practice of performing regular work from home or from a location close to home,on reducing the number of travel and reduced carbon emissions transportation activities.Models and methodologies described in the literature are a good basis for a better and more comprehensive and understanding of the positives and negative effects teleworking and real opportunities of its wider application,however there is a lack of systemic analysis.Development of a set of indicators for assessing emission reduction induced by the measures to promote sustainable transport.Due to the complexity of the transport sector,a change in any indicator models have side effects on other indicators(unwanted and multiplier effects)and what is the theme of our research work.展开更多
Limiting environmental pollution from exhaust emissions from internal combustion engines includes many measures,including encouraging biofuel use because biofuel is environmentally friendly and renewable.A mixture of ...Limiting environmental pollution from exhaust emissions from internal combustion engines includes many measures,including encouraging biofuel use because biofuel is environmentally friendly and renewable.A mixture of diesel fuel and vegetable oil is a form of biofuel.However,some properties of the mixed fuel,such as viscosity and density,are higher than those of traditional diesel fuel,affecting the injection and combustion process and reducing power and non-optimal toxic emissions,especially soot emissions.This study uses Kiva-3V software to simulate the combustion process of a diesel-vegetable oil mixture in the combustion chamber of a fishing vessel diesel engine with changes in fuel injection timing.The results show that when increasing the fuel injection timing of a diesel-vegetable oil mixture about 1–2 degrees of crankshaft rotation angle before the top dead center compared to diesel fuel injection timing,the engine power increases,and soot emissions decrease compared to no adjustment.The above simulation research results will help orient the experiments conveniently and reduce costs in the future experimental research process to quantify the fuel system adjustment of fishing vessels’diesel engines when using biofuels,including diesel-vegetable oil mixtures.Thus,the engine’s economic indicators will improve,and emissions that pollute the environment will be limited.展开更多
The emissions from traditional fossil heavy-duty trucks have become a conspicuous issue worldwide.The electrical road system(ERS)can offer a viable solution for achieving zero CO_(2) emissions and has high energy effi...The emissions from traditional fossil heavy-duty trucks have become a conspicuous issue worldwide.The electrical road system(ERS)can offer a viable solution for achieving zero CO_(2) emissions and has high energy efficiency in long-distance road cargo transport.While many kinds of pantograph structures have been developed for the ERS,their corresponding pantograph-catenary dynamic characteristics under different road conditions have not been investigated.This work performs a numerical study on the dynamics of the pantograph-catenary interaction of an ERS considering different pantograph structures.First,a pantograph-catenary-truck-road model is proposed.The reduced catenary model and reduced-plate model transmission method are used to minimize model scale.Three different types of ERS pantograph structures are considered in the model.After validation,the pantograph-catenary dynamics under the influence of truck-road interactions with complex road roughness and different pantographs are studied and compared.The corresponding vibration transmission mechanism is further focused.The results show that the truck-road interaction has a significant effect on the pantograph-catenary interaction,but the pantograph with only one lower and upper armcan isolate the roll vibrationmotion transmission fromthe truck to the collector head,which has the best dynamic performance and is suggested for use in the ERS.展开更多
Unmanned aerial vehicle(UAV)was introduced to take road segment traffic surveillance.Considering the limited UAV maximum flight distance,UAV route planning problem was studied.First,a multi-objective optimization mode...Unmanned aerial vehicle(UAV)was introduced to take road segment traffic surveillance.Considering the limited UAV maximum flight distance,UAV route planning problem was studied.First,a multi-objective optimization model of planning UAV route for road segment surveillance was proposed,which aimed to minimize UAV cruise distance and minimize the number of UAVs used.Then,an evolutionary algorithm based on Pareto optimality technique was proposed to solve multi-objective UAV route planning problem.At last,a UAV flight experiment was conducted to test UAV route planning effect,and a case with three scenarios was studied to analyze the impact of different road segment lengths on UAV route planning.The case results show that the optimized cruise distance and the number of UAVs used decrease by an average of 38.43% and 33.33%,respectively.Additionally,shortening or extending the length of road segments has different impacts on UAV route planning.展开更多
In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been developed.The mechanical and hydraulic simulation models are e...In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been developed.The mechanical and hydraulic simulation models are established using MATLAB Simscape to analyze their kinetics and dynamics in the lifting and holding stages.The simulation findings are compared to the analytical calculation results in the steady state,and both methods show good agreement.In the early lifting stage,Model 1 produces greater force and discharges goods in the container faster than Model 2.Meanwhile,Model 2 reaches a higher force and ejects goods from the container cleaner than its counterpart at the end lifting stage.The established simulation models can consider the effects of dynamic loads due to inertial moments and forces generated during the system operation.It is crucial in studying,designing,and optimizing the structure of hydraulic-mechanical systems.展开更多
We use multifractal detrended fluctuation analysis （MF-DFA） method to investigate the multifractal behavior of the interevent time series in a modified Olami-Feder-Christensen （OFC） earthquake model on assortative...We use multifractal detrended fluctuation analysis （MF-DFA） method to investigate the multifractal behavior of the interevent time series in a modified Olami-Feder-Christensen （OFC） earthquake model on assortative scale-free networks. We determine generalized Hurst exponent and singularity spectrum and find that these fluctuations have multifraetal nature. Comparing the MF-DFA results for the original interevent time series with those for shuffled and surrogate series, we conclude that the origin of multifractality is due to both the broadness of probability density function and long-range correlation.展开更多
Our paper describes the organizing of database,remarks about SNGO(Surlari National Geomagnetic Observatory)and network infrastructure.Based on the geomagnetic data acquired and stored on the database server,we perform...Our paper describes the organizing of database,remarks about SNGO(Surlari National Geomagnetic Observatory)and network infrastructure.Based on the geomagnetic data acquired and stored on the database server,we perform the processing and analysis of geomagnetic parameters through different spectral,statistical and correlation methods.All these parameters are included in the geomagnetic database on server.The web interface for the database meets the different needs of handling the data collected,raw or processed.The server-side programming language used for design is php.This allow us to select different periods for which access to stored data,required for different search filters and different parameters or data from different time periods can be compared.For a more in-depth analysis of the stored data,through JavaScript programming language graphs for different parameters can be drawn.Access to the web interface can be done with or without authentication,depending on the need to ensure the security of certain data collected,stored and processed.The applications are scalable for different devices that will access it:mobile,tablets,laptops or desktops.展开更多
The purpose of this study was to analyze the associated spectrum of geomagnetic field,frequencies intensity and the time of occurrence.We calculated the variation of the correlation coefficients,with mobile windows of...The purpose of this study was to analyze the associated spectrum of geomagnetic field,frequencies intensity and the time of occurrence.We calculated the variation of the correlation coefficients,with mobile windows of various sizes,for the recorded magnetic components at different latitudes and latitudes.The observatories we included in our study are USA(Surlari),HON(Honolulu),SBA(Scott Base),KAK(Kakioka),THY(Tihany),UPS(Uppsala),WNG(Wingst)and Yellowknife(YKC).We used the data of these observatories from International Real-time Magnetic Observatory Network(INTERMAGNET)for the geomagnetic storm from October 28-31,2003.We have used for this purpose a series of filtering algorithms,spectral analysis and wavelet with different mother functions at different levels.In the paper,we show the Fourier and wavelet analysis of geomagnetic data recorded at different observatories regarding geomagnetic storms.Fourier analysis hightlights predominant frequencies of magnetic field components.Wavelet analysis provides information about the frequency ranges of magnetic fields,which contain long time intervals for medium frequency information and short time intervals for highlight frequencies,details of the analyzed signals.Also,the wavelet analysis allows us to decompose geomagnetic signals in different waves.The analyses presented are significant for the studies of the geomagnetic storm.The data for the next days after the storm showed a mitigation of the perturbations and a transition to quiet days of the geomagnetic field.展开更多
In the paper the Czech toll system and its future are presented. E-toll Czech project： Facts and Figures （today） are included and the next steps in the process of developing microwave infrastructure are mentioned. ...In the paper the Czech toll system and its future are presented. E-toll Czech project： Facts and Figures （today） are included and the next steps in the process of developing microwave infrastructure are mentioned. In the event of possible system extension of the roads of the 1st, 2rid and 3rd class （ca 55,000 km）, the satellite technology will be used. The feasibility of such a combination of these two technologies, microwave and satellite, is subject to the compatibility of both systems in terms of the control equipment. For the microwave toll system, economic analyses according to EU directives were prepared for the Czech Ministry of Transport. Special attention is paid to the problems of traffic congestion, noise and damage to the environment, on the basis of the ＂user pays＂ and ＂polluter pays＂ according to the Eurovignette Directive principles. A complete survey of the EU toll system is included in the list of information sources.展开更多
The seismic hazard value is a fundamental quantity for the seismic risk assessment and for the determination of terms of references of seismic design of important facilities as dams, chemical plants, nuclear power pla...The seismic hazard value is a fundamental quantity for the seismic risk assessment and for the determination of terms of references of seismic design of important facilities as dams, chemical plants, nuclear power plants, etc.. In real sites, the seismic hazard value is influenced by both, the earthquake sizes, the impacts of which in a given site may be expected, and the properties of geological structure through which seismic waves spread from earthquake loci to a given site. The seismic risk is predetermined by hazard value, distribution of assets in the given site and asset numbers and vulnerabilities. The paper describes the used procedure of hazard assessment of important sites. The attention is especially paid to the basic steps as the data collection （homogeneity level, uncertainty and vagueness）, the focal region boundaries （their uncertainties and vagueness）, and the maximum expected earthquake size in each focal region that must be taken into account （its uncertainty and vagueness）, because they substantially influence the hazard value. Discussion is also concentrated to the attenuation that Central Europe substantially depends on the azimuth between earthquake focus and the given site. The attenuation differences are shown in seismic scenarios for individual focal regions. They are caused by focal mechanisms in near focal zone and differences in structure properties in distant zone; the boundary between near and distant zone in Central Europe is ca 2.5 h, where h is the focal depth in km. The real results are given for a real locality in Central Europe. It is shown than that great influence on hazard value is caused by great differences in azimuth attenuation curves. It is the reality that the Bohemian Massif is characterised with very low seismic attenuation in comparison with its vicinity. The following real results are presented： geological structure of near site vicinity, earthquake catalogue for Central Europe, focal regions in Central Europe, attenuation curves in Central Europe, typical earthquake isoseismals for individual focal regions, frequency graph, recurrence probability curve, etc.. The approaches used for nuclear facilities were recommended by the IAEA （International Atomic Energy Agency）.展开更多
Utilizing unmanned aerial vehicle (UAV) photography to timely detect and evaluate potential safety hazards (PSHs) around high-speed rail has great potential to complement and reform the existing manual inspections by ...Utilizing unmanned aerial vehicle (UAV) photography to timely detect and evaluate potential safety hazards (PSHs) around high-speed rail has great potential to complement and reform the existing manual inspections by providing better overhead views and mitigating safety issues. However, UAV inspections based on manual interpretation, which heavily rely on the experience, attention, and judgment of human inspectors, still inevitably suffer from subjectivity and inaccuracy. To address this issue, this study proposes a lightweight hybrid learning algorithm named HDTA (hybrid dual tasks architecture) to automatically and efficiently detect the PSHs of UAV imagery. First, this HDTA architecture seamlessly integrates both detection and segmentation branches within a unified framework. This design enables the model to simultaneously perform PSH detection and railroad parsing, thereby providing comprehensive scene understanding. Such joint learning also lays the foundation for PSH assessment tasks. Second, an innovative lightweight backbone based on the shuffle selective state space model (S^(4)M) is incorporated into HDTA. The state space model approach allows for global contextual information extraction while maintaining linear computational complexity. Furthermore, the incorporation of shuffle operation facilitates more efficient information flow across feature dimensions, enhancing both feature representation and fusion capabilities. Finally, extensive experiments conducted on a railroad environment dataset constructed from UAV imagery demonstrate that the proposed method achieves high detection accuracy while maintaining efficiency and practicality.展开更多
A gradient nanostructured layer was fabricated on the surface of TA15(Ti-6Al-2Zr-1Mo-1V)alloy(produced by selective laser melting)using severe shot peening(SSP).This study focuses on the evolution of the microstructur...A gradient nanostructured layer was fabricated on the surface of TA15(Ti-6Al-2Zr-1Mo-1V)alloy(produced by selective laser melting)using severe shot peening(SSP).This study focuses on the evolution of the microstructure and the mechanism of grain refinement in TA15 titanium alloy during SSP treatment.Transmission electron microscopyand Rietveld refinement methods were employed.The residual stress and microhardness variations with depth were also characterized.The results show:(1)At the initial stage of deformation,plastic deformation is primarily accommodated through twinning and dislocation slip.(2)As the strain increases,twinning disappears,and dislocations interact to form tangles.Some dislocations annihilate and rearrange into subgrain boundaries,subdividing the original grains into subgrains.(3)With continued dislocation activity,the subgrain size decreases until nanocrystals are formed through the dynamic rotational recrystallization.SSP introduced compressive residual stress(CRS)in the near-surface layer of the material,with the maximum CRS of approximately−1141 MPa observed in the subsurface layer.It also induced work hardening,increasing the surface hardness to approximately 479 HV.However,the surface roughness increases,leading to a slight deterioration in surface quality.展开更多
For internal combustion engines,engines installed for transport ships,cargo ships,and fishing vessels are mainly diesel engines.The number of engines is increasing due to the development of the maritime and seafood ex...For internal combustion engines,engines installed for transport ships,cargo ships,and fishing vessels are mainly diesel engines.The number of engines is increasing due to the development of the maritime and seafood exploitation sectors.Therefore,the high demand for petroleum fuels increases environmental pollution due to engine emissions.Reducing environmental pollution from the combustion of petroleum fuels has become a concern worldwide,especially for internal combustion engines.The exhaust gases from the engine contain harmful substances such as soot and nitrogen oxides(NO_(x)).Fuels with higher carbon content generate more soot when burned.In contrast,biofuels have low carbon and sulfur content and supply ample oxygen,which helps to reduce soot formation.For these reasons,biofuels are encouraged as alternative fuels to petroleum.Vegetable oil is one of the primary raw materials for biofuel production.This study presents a mixture of diesel and vegetable oil utilized as fuel for fishing vessels’diesel engines.The results of experimental research on a fishing vessel’s 4CHE Yanmar diesel engine when using diesel fuel mixed with coconut oil(B15,15%coconut oil,and 85%diesel)show that increasing B15 fuel injection pressure by about 10–15%compared with diesel fuel injection pressure reduces the engine’s soot emissions and increases power compared to unadjusted.This solution contributes to reducing environmental pollution from engine emissions.展开更多
This study explored how the human cortical folding pattern composed of convex gyri and concave sulci afected single-subject morphological brain networks,which are becoming an important method for studying the human br...This study explored how the human cortical folding pattern composed of convex gyri and concave sulci afected single-subject morphological brain networks,which are becoming an important method for studying the human brain connectome.We found that gyri-gyri networks exhibited higher morphological similarity,lower small-world parameters,and lower long-term test-retest reliability than sulci-sulci networks for cortical thickness-and gyrifcation index-based networks,while opposite patterns were observed for fractal dimension-based networks.Further behavioral association analysis revealed that gyri-gyri networks and connections between gyral and sulcal regions signifcantly explained inter-individual variance in Cognition and Motor domains for fractal dimension-and sulcal depth-based networks.Finally,the clinical application showed that only sulci-sulci networks exhibited morphological similarity reductions in major depressive disorder for cortical thickness-,fractal dimension-,and gyrifcation index-based networks.Taken together,these fndings provide novel insights into the constraint of the cortical folding pattern to the network organization of the human brain.展开更多
As the demand for bike-sharing has been increasing,the oversupply problem of bike-sharing has occurred,which leads to the waste of resources and disturbance of the urban environment.In order to regulate the supply vol...As the demand for bike-sharing has been increasing,the oversupply problem of bike-sharing has occurred,which leads to the waste of resources and disturbance of the urban environment.In order to regulate the supply volume of bike-sharing reasonably,an estimating model was proposed to quantify the urban carrying capacity(UCC)for bike-sharing through the demand data.In this way,the maximum supply volume of bike-sharing that a city can accommodate can be obtained.The UCC on bike-sharing is reflected in the road network carrying capacity(RNCC)and parking facilities’carrying capacity(PFCC).The space-time consumption method and density-based spatial clustering of application with noise(DBSCAN)algorithm were used to explore the RNCC and PFCC for bike-sharing.Combined with the users’demand,the urban load ratio on bike-sharing can be evaluated to judge whether the UCC can meet users’demand,so that the supply volume of bike-sharing and distribution of the related facilities can be adjusted accordingly.The application of the model was carried out by estimating the UCC and load ratio of each traffic analysis zone in Nanjing,China.Compared with the field survey data,the effect of the proposed algorithm was verified.展开更多
Permanent magnet synchronous motors(PMSMs)are typical electromechanical energy-conversion systems,in which the electrical and mechanical subsystems interact and impact each other.However,existing studies have investig...Permanent magnet synchronous motors(PMSMs)are typical electromechanical energy-conversion systems,in which the electrical and mechanical subsystems interact and impact each other.However,existing studies have investigated these two subsystems independently and failed to determine the coupling effect between electrical signals and mechanical vibrations.To address these gaps,a comprehensive electromechanical coupled model is proposed herein.This model integrates the PMSM model based on the winding function and the rotor-bearing dynamics model.The developed model can take into account the variations in inductance and current caused by non-uniform air-gap distribution.The electromechanical dynamic responses of the PMSM under rotor-bearing vibration and rotor eccentricity conditions are systematically analysed using this model.Results demonstrate that the proposed model improved the accuracy of both internal and external excitation representation in PMSMs compared with the conventional models.The dynamic behaviour of the rotor-bearing system is distinctly reflected in the electrical signals,and the variation laws of rotor eccentric distance and eccentric angle on the dynamic characteristics of the PMSM are revealed.The proposed model provides theoretical support for investigating the electromechanical coupled effect in PMSMs and offers an effective approach for state detection and fault diagnosis of motor-driven systems.展开更多
Delay is one of the most crucial factors for both pedestrians and car drivers around pedestrian crossings.Drivers often do not yield to pedestrians,which may result in both delay and impatient pedestrian behaviour.Thi...Delay is one of the most crucial factors for both pedestrians and car drivers around pedestrian crossings.Drivers often do not yield to pedestrians,which may result in both delay and impatient pedestrian behaviour.This tendency may alter after introducing autonomous vehicles as the vehicles will follow the traffic rules in all cases.This study aims to estimate the delay time alteration at a simple zebra crossing using on-site measures and simulation.Roadside video recordings were carried out in Budapest,Hungary,to obtain the crossing decisions of pedestrian groups based on the approaching vehicle distance.We have determined the accepted vehicle distance vales for pedestrian groups that served as input data for microsimulation modelling.The novelty of the study is that the simulation involved autonomous vehicles that hold preset headways from the leading vehicle.The simulation was designed based on the traffic share of autonomous vehicles and the headways they kept.The main findings are that the travel time and stopping time for cars are higher if the modal share of autonomous vehicles is high.For pedestrians,however,we found a slight decrease in both travel times and stopping times.Moreover,we have proposed modifications to the simulation software(Vissim)to handle distancedependent pedestrian decisions and drivers'failure to give priority.The results can be useful for road operators to estimate the road capacity in the era of autonomous vehicles and for software developers to formulate the simulated and real driving mechanism for autonomous vehicles.展开更多
文摘Maritime transportation is one of the most important and extensive transportation modes in the world. Maritime transportation is the backbone of contemporary world trade and therefore special attention should be paid to all subjects concerning this mode of transportation. It is also necessary to complement maritime transportation by other modes, such as rail and/or truck （road）. This article deals with the problems of maritime transportation and provides the summary of recent developments, trends and statistics mainly on transatlantic maritime routes （Europe to US）. Besides maritime transportation, this thesis also reviews the trends and statistics of rail and truck （road） transportation in US and Europe. The authors considers four Czech biggest cities （points of origin）, five European ports, eight US ports and 10 biggest cities in US （points of destination）. The adapted TCMMSP （transnational collaborative multi-mode shipping problem） is applied to this case study and it seeks to solve the transportation of a set of five shipments with unique O-D （origin-destination） pairs and volume. The end of the thesis summarizes the results and analyses the average costs, optimal set volume, optimal shipment routing and port analysis.
文摘This paper analyzes the key indicators of the impact assessment the teleworking as practice of performing regular work from home or from a location close to home,on reducing the number of travel and reduced carbon emissions transportation activities.Models and methodologies described in the literature are a good basis for a better and more comprehensive and understanding of the positives and negative effects teleworking and real opportunities of its wider application,however there is a lack of systemic analysis.Development of a set of indicators for assessing emission reduction induced by the measures to promote sustainable transport.Due to the complexity of the transport sector,a change in any indicator models have side effects on other indicators(unwanted and multiplier effects)and what is the theme of our research work.
文摘Limiting environmental pollution from exhaust emissions from internal combustion engines includes many measures,including encouraging biofuel use because biofuel is environmentally friendly and renewable.A mixture of diesel fuel and vegetable oil is a form of biofuel.However,some properties of the mixed fuel,such as viscosity and density,are higher than those of traditional diesel fuel,affecting the injection and combustion process and reducing power and non-optimal toxic emissions,especially soot emissions.This study uses Kiva-3V software to simulate the combustion process of a diesel-vegetable oil mixture in the combustion chamber of a fishing vessel diesel engine with changes in fuel injection timing.The results show that when increasing the fuel injection timing of a diesel-vegetable oil mixture about 1–2 degrees of crankshaft rotation angle before the top dead center compared to diesel fuel injection timing,the engine power increases,and soot emissions decrease compared to no adjustment.The above simulation research results will help orient the experiments conveniently and reduce costs in the future experimental research process to quantify the fuel system adjustment of fishing vessels’diesel engines when using biofuels,including diesel-vegetable oil mixtures.Thus,the engine’s economic indicators will improve,and emissions that pollute the environment will be limited.
基金supported by the National Natural Science Foundation of China(grant number 12302048,received by author Yan Xu)Yunnan fundamental research projects(grant No.202501AT070321,received by author Yan Xu).
文摘The emissions from traditional fossil heavy-duty trucks have become a conspicuous issue worldwide.The electrical road system(ERS)can offer a viable solution for achieving zero CO_(2) emissions and has high energy efficiency in long-distance road cargo transport.While many kinds of pantograph structures have been developed for the ERS,their corresponding pantograph-catenary dynamic characteristics under different road conditions have not been investigated.This work performs a numerical study on the dynamics of the pantograph-catenary interaction of an ERS considering different pantograph structures.First,a pantograph-catenary-truck-road model is proposed.The reduced catenary model and reduced-plate model transmission method are used to minimize model scale.Three different types of ERS pantograph structures are considered in the model.After validation,the pantograph-catenary dynamics under the influence of truck-road interactions with complex road roughness and different pantographs are studied and compared.The corresponding vibration transmission mechanism is further focused.The results show that the truck-road interaction has a significant effect on the pantograph-catenary interaction,but the pantograph with only one lower and upper armcan isolate the roll vibrationmotion transmission fromthe truck to the collector head,which has the best dynamic performance and is suggested for use in the ERS.
基金Project(2009AA11Z220)supported by National High Technology Research and Development Program of ChinaProjects(61070112,61070116)supported by the National Natural Science Foundation of China+1 种基金Project(2012LLYJTJSJ077)supported by the Ministry of Public Security of ChinaProject(KYQD14003)supported by Tianjin University of Technology and Education,China
文摘Unmanned aerial vehicle(UAV)was introduced to take road segment traffic surveillance.Considering the limited UAV maximum flight distance,UAV route planning problem was studied.First,a multi-objective optimization model of planning UAV route for road segment surveillance was proposed,which aimed to minimize UAV cruise distance and minimize the number of UAVs used.Then,an evolutionary algorithm based on Pareto optimality technique was proposed to solve multi-objective UAV route planning problem.At last,a UAV flight experiment was conducted to test UAV route planning effect,and a case with three scenarios was studied to analyze the impact of different road segment lengths on UAV route planning.The case results show that the optimized cruise distance and the number of UAVs used decrease by an average of 38.43% and 33.33%,respectively.Additionally,shortening or extending the length of road segments has different impacts on UAV route planning.
基金Ho Chi Minh City University of Technology(HCMUT)Vietnam National University Ho Chi Minh City(VNU-HCM)for supporting this study。
文摘In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been developed.The mechanical and hydraulic simulation models are established using MATLAB Simscape to analyze their kinetics and dynamics in the lifting and holding stages.The simulation findings are compared to the analytical calculation results in the steady state,and both methods show good agreement.In the early lifting stage,Model 1 produces greater force and discharges goods in the container faster than Model 2.Meanwhile,Model 2 reaches a higher force and ejects goods from the container cleaner than its counterpart at the end lifting stage.The established simulation models can consider the effects of dynamic loads due to inertial moments and forces generated during the system operation.It is crucial in studying,designing,and optimizing the structure of hydraulic-mechanical systems.
基金Supported by Foundation for Outstanding Young and Middle-aged Scientists in Shandong Province under Grant No.BS2011HZ019State Key Laboratory of Data Analysis and Applications,State Oceanic Administration under Grant No.LDAA-2011-02the Fundamental Research Funds for the Central Universities under Grant No.201113006
文摘We use multifractal detrended fluctuation analysis （MF-DFA） method to investigate the multifractal behavior of the interevent time series in a modified Olami-Feder-Christensen （OFC） earthquake model on assortative scale-free networks. We determine generalized Hurst exponent and singularity spectrum and find that these fluctuations have multifraetal nature. Comparing the MF-DFA results for the original interevent time series with those for shuffled and surrogate series, we conclude that the origin of multifractality is due to both the broadness of probability density function and long-range correlation.
基金the Romanian Ministry of Education and Research for financing the projects:“The realization of 3D geological/geophysical models for the characterization of some areas of economic and scientific interest in Romania”,with Contract No.49N/2019“Institutional capacities and services for research,monitoring and forecasting of risks in extra-atmospheric space”,acronym SAFESPACE,Contract No.16PCCDI/2018,within PNCDIII.
文摘Our paper describes the organizing of database,remarks about SNGO(Surlari National Geomagnetic Observatory)and network infrastructure.Based on the geomagnetic data acquired and stored on the database server,we perform the processing and analysis of geomagnetic parameters through different spectral,statistical and correlation methods.All these parameters are included in the geomagnetic database on server.The web interface for the database meets the different needs of handling the data collected,raw or processed.The server-side programming language used for design is php.This allow us to select different periods for which access to stored data,required for different search filters and different parameters or data from different time periods can be compared.For a more in-depth analysis of the stored data,through JavaScript programming language graphs for different parameters can be drawn.Access to the web interface can be done with or without authentication,depending on the need to ensure the security of certain data collected,stored and processed.The applications are scalable for different devices that will access it:mobile,tablets,laptops or desktops.
文摘The purpose of this study was to analyze the associated spectrum of geomagnetic field,frequencies intensity and the time of occurrence.We calculated the variation of the correlation coefficients,with mobile windows of various sizes,for the recorded magnetic components at different latitudes and latitudes.The observatories we included in our study are USA(Surlari),HON(Honolulu),SBA(Scott Base),KAK(Kakioka),THY(Tihany),UPS(Uppsala),WNG(Wingst)and Yellowknife(YKC).We used the data of these observatories from International Real-time Magnetic Observatory Network(INTERMAGNET)for the geomagnetic storm from October 28-31,2003.We have used for this purpose a series of filtering algorithms,spectral analysis and wavelet with different mother functions at different levels.In the paper,we show the Fourier and wavelet analysis of geomagnetic data recorded at different observatories regarding geomagnetic storms.Fourier analysis hightlights predominant frequencies of magnetic field components.Wavelet analysis provides information about the frequency ranges of magnetic fields,which contain long time intervals for medium frequency information and short time intervals for highlight frequencies,details of the analyzed signals.Also,the wavelet analysis allows us to decompose geomagnetic signals in different waves.The analyses presented are significant for the studies of the geomagnetic storm.The data for the next days after the storm showed a mitigation of the perturbations and a transition to quiet days of the geomagnetic field.
文摘In the paper the Czech toll system and its future are presented. E-toll Czech project： Facts and Figures （today） are included and the next steps in the process of developing microwave infrastructure are mentioned. In the event of possible system extension of the roads of the 1st, 2rid and 3rd class （ca 55,000 km）, the satellite technology will be used. The feasibility of such a combination of these two technologies, microwave and satellite, is subject to the compatibility of both systems in terms of the control equipment. For the microwave toll system, economic analyses according to EU directives were prepared for the Czech Ministry of Transport. Special attention is paid to the problems of traffic congestion, noise and damage to the environment, on the basis of the ＂user pays＂ and ＂polluter pays＂ according to the Eurovignette Directive principles. A complete survey of the EU toll system is included in the list of information sources.
文摘The seismic hazard value is a fundamental quantity for the seismic risk assessment and for the determination of terms of references of seismic design of important facilities as dams, chemical plants, nuclear power plants, etc.. In real sites, the seismic hazard value is influenced by both, the earthquake sizes, the impacts of which in a given site may be expected, and the properties of geological structure through which seismic waves spread from earthquake loci to a given site. The seismic risk is predetermined by hazard value, distribution of assets in the given site and asset numbers and vulnerabilities. The paper describes the used procedure of hazard assessment of important sites. The attention is especially paid to the basic steps as the data collection （homogeneity level, uncertainty and vagueness）, the focal region boundaries （their uncertainties and vagueness）, and the maximum expected earthquake size in each focal region that must be taken into account （its uncertainty and vagueness）, because they substantially influence the hazard value. Discussion is also concentrated to the attenuation that Central Europe substantially depends on the azimuth between earthquake focus and the given site. The attenuation differences are shown in seismic scenarios for individual focal regions. They are caused by focal mechanisms in near focal zone and differences in structure properties in distant zone; the boundary between near and distant zone in Central Europe is ca 2.5 h, where h is the focal depth in km. The real results are given for a real locality in Central Europe. It is shown than that great influence on hazard value is caused by great differences in azimuth attenuation curves. It is the reality that the Bohemian Massif is characterised with very low seismic attenuation in comparison with its vicinity. The following real results are presented： geological structure of near site vicinity, earthquake catalogue for Central Europe, focal regions in Central Europe, attenuation curves in Central Europe, typical earthquake isoseismals for individual focal regions, frequency graph, recurrence probability curve, etc.. The approaches used for nuclear facilities were recommended by the IAEA （International Atomic Energy Agency）.
基金supported in part by the National Natural Science Foundation of China(grantNo.52362048)in part by Yunnan Fundamental Research Projects(grantNo.202301BE070001-042 and grant No.202401AT070409).
文摘Utilizing unmanned aerial vehicle (UAV) photography to timely detect and evaluate potential safety hazards (PSHs) around high-speed rail has great potential to complement and reform the existing manual inspections by providing better overhead views and mitigating safety issues. However, UAV inspections based on manual interpretation, which heavily rely on the experience, attention, and judgment of human inspectors, still inevitably suffer from subjectivity and inaccuracy. To address this issue, this study proposes a lightweight hybrid learning algorithm named HDTA (hybrid dual tasks architecture) to automatically and efficiently detect the PSHs of UAV imagery. First, this HDTA architecture seamlessly integrates both detection and segmentation branches within a unified framework. This design enables the model to simultaneously perform PSH detection and railroad parsing, thereby providing comprehensive scene understanding. Such joint learning also lays the foundation for PSH assessment tasks. Second, an innovative lightweight backbone based on the shuffle selective state space model (S^(4)M) is incorporated into HDTA. The state space model approach allows for global contextual information extraction while maintaining linear computational complexity. Furthermore, the incorporation of shuffle operation facilitates more efficient information flow across feature dimensions, enhancing both feature representation and fusion capabilities. Finally, extensive experiments conducted on a railroad environment dataset constructed from UAV imagery demonstrate that the proposed method achieves high detection accuracy while maintaining efficiency and practicality.
基金financially supported by the National Natural Science Foundation of China(No.12262014).
文摘A gradient nanostructured layer was fabricated on the surface of TA15(Ti-6Al-2Zr-1Mo-1V)alloy(produced by selective laser melting)using severe shot peening(SSP).This study focuses on the evolution of the microstructure and the mechanism of grain refinement in TA15 titanium alloy during SSP treatment.Transmission electron microscopyand Rietveld refinement methods were employed.The residual stress and microhardness variations with depth were also characterized.The results show:(1)At the initial stage of deformation,plastic deformation is primarily accommodated through twinning and dislocation slip.(2)As the strain increases,twinning disappears,and dislocations interact to form tangles.Some dislocations annihilate and rearrange into subgrain boundaries,subdividing the original grains into subgrains.(3)With continued dislocation activity,the subgrain size decreases until nanocrystals are formed through the dynamic rotational recrystallization.SSP introduced compressive residual stress(CRS)in the near-surface layer of the material,with the maximum CRS of approximately−1141 MPa observed in the subsurface layer.It also induced work hardening,increasing the surface hardness to approximately 479 HV.However,the surface roughness increases,leading to a slight deterioration in surface quality.
文摘For internal combustion engines,engines installed for transport ships,cargo ships,and fishing vessels are mainly diesel engines.The number of engines is increasing due to the development of the maritime and seafood exploitation sectors.Therefore,the high demand for petroleum fuels increases environmental pollution due to engine emissions.Reducing environmental pollution from the combustion of petroleum fuels has become a concern worldwide,especially for internal combustion engines.The exhaust gases from the engine contain harmful substances such as soot and nitrogen oxides(NO_(x)).Fuels with higher carbon content generate more soot when burned.In contrast,biofuels have low carbon and sulfur content and supply ample oxygen,which helps to reduce soot formation.For these reasons,biofuels are encouraged as alternative fuels to petroleum.Vegetable oil is one of the primary raw materials for biofuel production.This study presents a mixture of diesel and vegetable oil utilized as fuel for fishing vessels’diesel engines.The results of experimental research on a fishing vessel’s 4CHE Yanmar diesel engine when using diesel fuel mixed with coconut oil(B15,15%coconut oil,and 85%diesel)show that increasing B15 fuel injection pressure by about 10–15%compared with diesel fuel injection pressure reduces the engine’s soot emissions and increases power compared to unadjusted.This solution contributes to reducing environmental pollution from engine emissions.
基金supported by the STI 2030-Major Projects(2021ZD0200500)the National Social Science Foundation of China(20&ZD296)Key Realm R&D Program of Guangdong Province(2019B030335001).
文摘This study explored how the human cortical folding pattern composed of convex gyri and concave sulci afected single-subject morphological brain networks,which are becoming an important method for studying the human brain connectome.We found that gyri-gyri networks exhibited higher morphological similarity,lower small-world parameters,and lower long-term test-retest reliability than sulci-sulci networks for cortical thickness-and gyrifcation index-based networks,while opposite patterns were observed for fractal dimension-based networks.Further behavioral association analysis revealed that gyri-gyri networks and connections between gyral and sulcal regions signifcantly explained inter-individual variance in Cognition and Motor domains for fractal dimension-and sulcal depth-based networks.Finally,the clinical application showed that only sulci-sulci networks exhibited morphological similarity reductions in major depressive disorder for cortical thickness-,fractal dimension-,and gyrifcation index-based networks.Taken together,these fndings provide novel insights into the constraint of the cortical folding pattern to the network organization of the human brain.
基金Project(2018YFE0120100)supported by the National Key R&D Program of ChinaProject(YBPY2040)supported by the Scientific Research Foundation of Graduate School of Southeast University,China。
文摘As the demand for bike-sharing has been increasing,the oversupply problem of bike-sharing has occurred,which leads to the waste of resources and disturbance of the urban environment.In order to regulate the supply volume of bike-sharing reasonably,an estimating model was proposed to quantify the urban carrying capacity(UCC)for bike-sharing through the demand data.In this way,the maximum supply volume of bike-sharing that a city can accommodate can be obtained.The UCC on bike-sharing is reflected in the road network carrying capacity(RNCC)and parking facilities’carrying capacity(PFCC).The space-time consumption method and density-based spatial clustering of application with noise(DBSCAN)algorithm were used to explore the RNCC and PFCC for bike-sharing.Combined with the users’demand,the urban load ratio on bike-sharing can be evaluated to judge whether the UCC can meet users’demand,so that the supply volume of bike-sharing and distribution of the related facilities can be adjusted accordingly.The application of the model was carried out by estimating the UCC and load ratio of each traffic analysis zone in Nanjing,China.Compared with the field survey data,the effect of the proposed algorithm was verified.
基金supported by the National Natural Science Foundation of China(Grant Nos.52275132,52388102)the National Key R&D Program of China(Grant No.2022YFB3402100)the Sichuan Science and Technology Program(Grant No.2024NSFTD0011)。
文摘Permanent magnet synchronous motors(PMSMs)are typical electromechanical energy-conversion systems,in which the electrical and mechanical subsystems interact and impact each other.However,existing studies have investigated these two subsystems independently and failed to determine the coupling effect between electrical signals and mechanical vibrations.To address these gaps,a comprehensive electromechanical coupled model is proposed herein.This model integrates the PMSM model based on the winding function and the rotor-bearing dynamics model.The developed model can take into account the variations in inductance and current caused by non-uniform air-gap distribution.The electromechanical dynamic responses of the PMSM under rotor-bearing vibration and rotor eccentricity conditions are systematically analysed using this model.Results demonstrate that the proposed model improved the accuracy of both internal and external excitation representation in PMSMs compared with the conventional models.The dynamic behaviour of the rotor-bearing system is distinctly reflected in the electrical signals,and the variation laws of rotor eccentric distance and eccentric angle on the dynamic characteristics of the PMSM are revealed.The proposed model provides theoretical support for investigating the electromechanical coupled effect in PMSMs and offers an effective approach for state detection and fault diagnosis of motor-driven systems.
基金the Hungarian Academy of Science for awarding him the Bolyai János Research Scholarship(BO/00393/22)。
文摘Delay is one of the most crucial factors for both pedestrians and car drivers around pedestrian crossings.Drivers often do not yield to pedestrians,which may result in both delay and impatient pedestrian behaviour.This tendency may alter after introducing autonomous vehicles as the vehicles will follow the traffic rules in all cases.This study aims to estimate the delay time alteration at a simple zebra crossing using on-site measures and simulation.Roadside video recordings were carried out in Budapest,Hungary,to obtain the crossing decisions of pedestrian groups based on the approaching vehicle distance.We have determined the accepted vehicle distance vales for pedestrian groups that served as input data for microsimulation modelling.The novelty of the study is that the simulation involved autonomous vehicles that hold preset headways from the leading vehicle.The simulation was designed based on the traffic share of autonomous vehicles and the headways they kept.The main findings are that the travel time and stopping time for cars are higher if the modal share of autonomous vehicles is high.For pedestrians,however,we found a slight decrease in both travel times and stopping times.Moreover,we have proposed modifications to the simulation software(Vissim)to handle distancedependent pedestrian decisions and drivers'failure to give priority.The results can be useful for road operators to estimate the road capacity in the era of autonomous vehicles and for software developers to formulate the simulated and real driving mechanism for autonomous vehicles.
