In this study,a detailed analysis of the combustion behaviors of the lithium iron phosphate(LFP)and lithium manganese oxide(LMO)batteries used in electric bicycles was conducted.This research included quantitative mea...In this study,a detailed analysis of the combustion behaviors of the lithium iron phosphate(LFP)and lithium manganese oxide(LMO)batteries used in electric bicycles was conducted.This research included quantitative measurements of the combustion duration,flame height,combustion temperature,heat release rate,and total heat release.The results indicated that LMO batteries exhibited higher combustion temperatures of 600–700°C,flame heights of 70–75 cm,a significantly higher heat release rate of40.1 k W(12 Ah),and a total heat release of 1.04 MJ(12 Ah)compared to LFP batteries with the same capacity.Based on these experimental results,a normalized total heat release(NORTHR)parameter was proposed,demonstrating good universality for batteries with different capacities.Utilizing this parameter,quantitative calculations and optimization of the extinguishing agent dosage were conducted for fires involving these two types of batteries,and the method was validated by extinguishing fires for these two types of battery packs with water-based extinguishing fluids.展开更多
Wearing helmetswhile riding electric bicycles can significantly reduce head injuries resulting fromtraffic accidents.To effectively monitor compliance,the utilization of target detection algorithms through traffic cam...Wearing helmetswhile riding electric bicycles can significantly reduce head injuries resulting fromtraffic accidents.To effectively monitor compliance,the utilization of target detection algorithms through traffic cameras plays a vital role in identifying helmet usage by electric bicycle riders and recognizing license plates on electric bicycles.However,manual enforcement by traffic police is time-consuming and labor-intensive.Traditional methods face challenges in accurately identifying small targets such as helmets and license plates using deep learning techniques.This paper proposes an enhanced model for detecting helmets and license plates on electric bicycles,addressing these challenges.The proposedmodel improves uponYOLOv8n by deepening the network structure,incorporating weighted connections,and introducing lightweight convolutional modules.These modifications aim to enhance the precision of small target recognition while reducing the model’s parameters,making it suitable for deployment on low-performance devices in real traffic scenarios.Experimental results demonstrate that the model achieves an mAP@0.5 of 91.8%,showing an 11.5%improvement over the baselinemodel,with a 16.2%reduction in parameters.Additionally,themodel achieves a frames per second(FPS)rate of 58,meeting the accuracy and speed requirements for detection in actual traffic scenarios.展开更多
Bicycle sharing system has emerged as a new mode of transportation in many big cities over the past decade.Since the large number of bicycle stations distribute widely in the city,it is difficult to identify their uni...Bicycle sharing system has emerged as a new mode of transportation in many big cities over the past decade.Since the large number of bicycle stations distribute widely in the city,it is difficult to identify their unique attributes and characteristics directly.Oriented to the real bicycle hire dataset in Hangzhou,China,the clustering analysis for the bicycle stations based on the temporal flow data was carried out firstly.Then,based on the spatial distribution and temporal attributes of calculated clusters,visual diagram and map were used to vividly analyze the bicycle hire behavior related to station category and study the travel rules of citizens.The experimental results demonstrate the relation between human mobility,the time of day,day of week and the station location.展开更多
In order to improve the public transit’s accessibility and promote service quality of the public transit,it is necessary to alleviate the“last⁃mile”problem.The combination of the public transit and bicycle⁃sharing ...In order to improve the public transit’s accessibility and promote service quality of the public transit,it is necessary to alleviate the“last⁃mile”problem.The combination of the public transit and bicycle⁃sharing system is competitive compared with the private car.In 2016,the dockless bicycle⁃sharing system has been undergoing tremendous development.Because the dockless bicycle⁃sharing system is different from previous bicycle⁃sharing systems,components of service quality of the dockless bicycle⁃sharing system differ.However,there are few articles about the service quality of the dockless bicycle⁃sharing system.This paper examined the evaluation of service quality of the dockless bicycle⁃sharing system along with a measurement of users’satisfaction.A questionnaire about service quality was designed,which includes 15 factors.Through the analysis of travelers’evaluation of factors of the dockless bicycle⁃sharing system with Rasch Model,these original ordinal data(Likert data)was transformed to the interval data:the person parameter(ability)and the item parameter(difficulty).Through the analysis of interviewees’abilities,it was found that only education and monthly consumption have significant influence on interviewees’evaluation of service quality of the dockless bicycle⁃sharing system,while there is no significant influence of gender,weekly use of dockless shared⁃bicycle,private car ownership,or monthly income on the evaluation.Furthermore,it was found that users were dissatisfied with cycling under the adverse weather,disturbance from pedestrians and cars,continuity of the bicycle lane,complaint channel,and staff service the most.展开更多
Public bicycle service has experienced 15 years of development in Chinese cities,and China's Mainland is the world's largest public bicycle market.Choosing to use public bicycles is becoming more and more a da...Public bicycle service has experienced 15 years of development in Chinese cities,and China's Mainland is the world's largest public bicycle market.Choosing to use public bicycles is becoming more and more a daily habit of residents.Broadly speaking,public bicycles in Chinese cities include both public bikes with service stations and shared bicycles without service stations.Based on historical review and years of accumulated data,this paper reviews the development of general public bicycles in Chinese cities in the past 15 years.And the role of general public bicycles in China’s urban transportation system is analyzed.Finally,from the perspective of urban construction and management,some suggestions for the future development of public bicycles are put forward.展开更多
Objectives: The primary objective was to characterize the range of Knowledge, Attitude, and Practice (KAP) of Helmet use in children amongst parents to prevent head injuries and death. Methods: This is a cross-section...Objectives: The primary objective was to characterize the range of Knowledge, Attitude, and Practice (KAP) of Helmet use in children amongst parents to prevent head injuries and death. Methods: This is a cross-sectional study, done by online survey using a snowball sampling technique, the number of included responses were 386 parents (Male and female) living in Riyadh Aged 21 - 60 years old or above. Results: The study showed that there is a difference in Parents’ belief in the importance of helmet use while riding a Bicycle vs Motorcycle/Quad bike and that was affected by parents’ education level, almost all the people who answered the survey (76.7%) agree that it is important for their children to wear a helmet when riding both a Bicycle and a Motorcycle or Quadbike with a cumulative percentage of (93.8%). And almost all agreed on multiple approaches to help increase helmet use be it by forcing rental shops to give out helmets, forcing sellers to recommend the use of helmets, increasing awareness campaigns, and imposing fines for not wearing helmets. Conclusions: This study is the first to explore Family helmet use while riding Bicycles and Motorcycles/Quad bikes. Although Parent’s belief in the importance of helmet use for their children was high, it is clear that the level of practice is low. With that the risk of head injuries might be high, our findings suggest that safety interventions for increasing pediatric helmet use are needed to increase helmet use and reduce the risk of head injury and hospitalization.展开更多
Mobile information and communication technologies(MICTs) have fully penetrated everyday life in smart societies;this has greatly compressed time, space, and distance, and consequently, reshaped residents’ travel beha...Mobile information and communication technologies(MICTs) have fully penetrated everyday life in smart societies;this has greatly compressed time, space, and distance, and consequently, reshaped residents’ travel behaviour patterns. As a new mode of shared mobility, the sharing bicycle offers a variety of options for the daily travel of urban residents. Extant studies have mainly examined the travel characteristics and influencing factors of public bicycles with piles, while the travel patterns for sharing bicycles and their driving mechanisms have been largely ignored. Using one week’s travel data for Mobike, this study investigated the spatial and temporal distribution patterns of sharing bicycle travel behaviours in the central urban area of Guangzhou, China;furthermore, it identified the influences of built environment density factors on sharing bicycle travel behaviours based on the geographically weighted regression method. Obvious morning and evening peaks were observed in the sharing bicycle travel patterns for both weekdays and weekends. The old urban area, which had a high degree of mixed function, dense road networks, and cycling-friendly built environments, was the main travel area that attracted sharing bicycles on both weekdays and weekends. Furthermore, factors including the point of interest(POI) for the density of public transport stations, the functional mixing degree, and the density of residential POIs significantly affected residents’ travel behaviours. These findings could enrich discourse regarding shared mobility with a Chinese case characterised by rapidly developing MICTs and also provide references to local authorities for improving slow traffic environments.展开更多
With the development of technology and the change of market demands,the trend in middle and high grade bicycle manufacturing is developed toward small-volume,multi-species,and customer-oriented production.Therefore,hu...With the development of technology and the change of market demands,the trend in middle and high grade bicycle manufacturing is developed toward small-volume,multi-species,and customer-oriented production.Therefore,human element should be fully considered in design so that the bicycle has the best cycling performance for the specific rider.Currently,customized design is difficult to achieve since feature parameters of the rider are not included in the design.The design of bicycle frame is the most important in bicycle design.The relative positions among the saddle,handlebar and central axis are defined as the bicycle three-pivot,they are the main parameters in bicycle frame design.In conventional bicycle design,frame parameters are merely relevant to bicycle types.On the basis of the principles of biomechanics and ergonomics knowledge,this paper presents a design method for bicycle three-pivot considering feature parameters of the rider by dynamic simulation.Firstly,a dynamic model of rider-bicycle system is built for a special rider,and a serial of simulation experiments is designed by uniform test method.Then,a mathematical model is built between the three-pivot position and the square of lower limb muscle stress by using simulation and regression analysis of the rider-bicycle system.The optimal three-pivot position parameters are obtained by setting the minimal of the square of the lower limb muscle stress as the objective.Therefore,the optimal parameters are gained for the specific rider.Finally,various results are gained for different riders based on the same design process.The function between feature parameters of the rider and the optimum three-pivot position parameters is built by regression.Bicycle design considering biomechanics can be divided into three main steps:calculating the three-pivot position,designing the geometrical structure of the bicycle frame and analyzing frame strength,and selecting appropriate parts and assembling the bicycle.Bicycle design considering biomechanics changes the conventional bicycle design and realizes customized design by considering human element in the design process.展开更多
A collision model, an automobile model and a multi-rigid-body model in PC-crash are analyzed. By simulating a side collision accident between a car and an electric bicycle (EB), a method that reproduces the car-electr...A collision model, an automobile model and a multi-rigid-body model in PC-crash are analyzed. By simulating a side collision accident between a car and an electric bicycle (EB), a method that reproduces the car-electric bicycle side collision accident based on PC-crash is presented according to some important information such as the final position, the contacting location between the cyclist and the car. A result is obtained by comparing with the reproduced result, the deformation of accident vehicle and the surveillance video. The rollover direction and fells-over sliding direction after the collision and the contacting location and wrap motion of cyclist and electric bicycle are fitting in with the real situation better compared with the reconstruction result in PC-crash. Then the responsive-surface method and MONTEKARLO method are used in MATLAB to analyze the uncertainty of the vehicle speed in reproduced scene results. And the range of values of the pre-collision speed is obtained which makes the reproduced result more objective and convincible that could provide the basis of the accident assessment.展开更多
The non-smooth dynamic model of an unmanned bicycle is established to study the contact-separate and stick-slip non-smooth phenomena between wheels and the ground.According to the Carvallo-Whipple configuration,the un...The non-smooth dynamic model of an unmanned bicycle is established to study the contact-separate and stick-slip non-smooth phenomena between wheels and the ground.According to the Carvallo-Whipple configuration,the unmanned bicycle is reduced to four rigid bodies,namely,rear wheel,rear frame,front fork,and front wheel,which are connected by perfect revolute joints.The interaction between each wheel and the ground is simplified as the normal contact force and the friction force at the contact point,and these forces are described by the Hunt-Crossley contact force model and the Lu Gre friction force model,respectively.According to the characteristics of flat and curved pavements,calculation methods for contact forces and their generalized forces are presented.The dynamics of the system is modeled by the Lagrange equations of the first kind,a numerical solution algorithm of the dynamic equations is presented,and the Baumgarte stabilization method is used to restrict the drift of the constraints.The correctness of the dynamic model and the numerical algorithm is verified in comparison with the previous studies.The feasibility of the proposed model is demonstrated by simulations under different motion states.展开更多
Vehicle–bicycle conflict incurs a higher risk of traffic accidents,particularly as it frequently takes place at intersections.Mastering the traffic characteristics of vehicle–bicycle conflict and optimizing the desi...Vehicle–bicycle conflict incurs a higher risk of traffic accidents,particularly as it frequently takes place at intersections.Mastering the traffic characteristics of vehicle–bicycle conflict and optimizing the design of intersections can effectively reduce such conflict.In this paper,the conflict between right-turning motor vehicles and straight-riding bicycles was taken as the research object,and T-Analyst video recognition technology was used to obtain data on riding(driving)behavior and vehicle–bicycle conflict at seven intersections in Changsha,China.Herein,eight typical traffic characteristics of vehicle–bicycle conflict are summarized,the causes of vehicle–bicycle conflict are analyzed using 18 factors in three dimensions,the internal relationship between intersection design factors and traffic conflicts is explored,and the guiding of design optimization based on the width of bicycle lanes and the soft separation between vehicles and bicycles is discussed.The results showed that colored paved bicycle lanes were better,performing better at a width of 2.5 m compared to 1.5 m.However,the colored pavement was not suitable for the entire road and had to be set at the position,at which the trajectories of a bicycle and motor vehicle overlapped.Thus,a 2.5-m-wide bicycle lane provides good safety.However,there are still defects in the existing safety indicators,so it is necessary to develop new indicators to reflect real vehicle–bicycle conflict situations more comprehensively.展开更多
Sustainable and practical personal mobility solutions for campus environments have traditionally revolved around the use of bicycles, or provision of pedestrian facilities. However many campus environments also experi...Sustainable and practical personal mobility solutions for campus environments have traditionally revolved around the use of bicycles, or provision of pedestrian facilities. However many campus environments also experience traffic congestion, parking difficulties and pollution from fossil-fuelled vehicles. It appears that pedal power alone has not been sufficient to supplant the use of petrol and diesel vehicles to date, and therefore it is opportune to investigate both the reasons behind the continual use of environmentally unfriendly transport, and consider potential solutions. This paper presents the results from a year-long study into electric bicycle effectiveness for a large tropical campus, identifying barriers to bicycle use that can be overcome through the availability of public use electric bicycles.展开更多
Background: Cycling as a means of transport contributes to public health in terms of increasing the physical activity behaviour and reducing air pollution. In comparison to walking, cycling-spe cific environmental cha...Background: Cycling as a means of transport contributes to public health in terms of increasing the physical activity behaviour and reducing air pollution. In comparison to walking, cycling-spe cific environmental characteristics have been less investigated. The aim of this study was to develop, based on geographic information systems (GIS) data, a bikeability index for a mid-sized European city, to examine the predictive validity of the index and to visualize the bicycle-friendliness of the city by creating a bikeability map. Methods: Using GIS data, we assessed the environmental characteristics of 278 bicycle trips in the city of Graz, Austria. Characteristics which differed significantly between the actually taken and shortest possible routes were used to form an additive bikeability index and the bikeability map for 100 m × 100 m cells. The relationship between the cycling behaviour and the bikeability index around the home environment was examined to assess the predictive validity of the index. Results: Three environmental components (cycling infrastructure, bicycle pathways and green areas) were positively related, and two components (main roads, and topography) were negatively related to the actually used route. These components formed the bikeability index, which was positively correlated with cycling behaviour (OR: 1.08, 95% CI 1.01 - 1.17). The final outcome is a high-resolution coloured map indicating the degree of bicycle-friendliness in the city of Graz. Conclusion: Mapping based on the bikeability index helps to visualize the bicycle-friendliness of an urban area. Therefore, it should be a useful tool for the planning as well as for the evaluation of the transport environments in cities.展开更多
Background: Physical fitness tests are widely used to assess endurance,sprint ability,coordination and/or strength.The objective of the present study was to analyze the degree to which the results of the Bundeswehr Ba...Background: Physical fitness tests are widely used to assess endurance,sprint ability,coordination and/or strength.The objective of the present study was to analyze the degree to which the results of the Bundeswehr Basis Fitness Test(BFT)–a physical fitness test comprising a sprint test(11×10-m shuttle test),a flexed-arm hang test and a 1000-m run–are consistent with the output measured during a bicycle ergometer test.The number of false-positive and falsenegative results with regard to the assessment of physical fitness were also examined.Methods: As part of a retrospective study,health assessments from 323 reenlistment examinations were evaluated regarding the output measured during a bicycle ergometer test and compared with the BFT results of the candidates.Results: Overall,a good correlation was shown between the bicycle ergometer test results and the results achieved in the BFT disciplines.All three disciplines of the BFT showed a highly significant correlation with the relative output achieved during the bicycle ergometer test(P<0.001),and also,the overall BFT score was highly significantly correlated(P<0.001).The overall rate of false-positive and false-negative results was 4.0%.Conclusion: The BFT results measured in the three physical fitness test items were highly correlated with the output measured during the bicycle ergometer tests.The rate of false-positive and false-negative results was low.The test items thus represent an appropriate measurement instrument because the test items require few equipment and less time.Additionally,a large number of subjects can be assessed.We suggest that it would be more useful to assess the physical fitness of this special group exclusively on the basis of the BFT instead of using the bicycle ergometer test.展开更多
Smart growth policies advocate for economically viable,environmentally conscientious,and socially equitable solutions for urban development.These policies were developed largely in response to issues rooted in the aut...Smart growth policies advocate for economically viable,environmentally conscientious,and socially equitable solutions for urban development.These policies were developed largely in response to issues rooted in the automobile-oriented culture:air pollution,high greenhouse gas emissions,traffic congestion,and sedentary lifestyles.In urban settings,a good transportation alternative is cycling,since it is able to serve the travel needs of nearly half of city dwellers' daily trips.Many European and Canadian cities have successfully increased cycling rates by creating safer bicycle environments and restricting or discouraging automobile use.To evaluate the potential effects of the above measures on American urban areas,this paper examines case studies of cycle tracks and bicycle boulevards implemented in American cities,and how these facility improvements have changed how safe cyclists feel on the road and overall bicycle usage.Results show the two methods are indeed effective in increasing bicycle usage rates.Ultimately,increasing cycling rates needs policies to discourage people from driving,the greatest mode share in nearly all urban areas.Parking policy has major impacts on people's decision to use the automobile.Currently,parking is oversupplied and underpriced in many cities,making it irresistible for people to drive.Decreasing the number of parking spaces available and increasing their price will increase pressure on drivers to drive less,especially for short trips,and to bike instead.It is important for planners and policy makers to realize that solutions from both directions,making biking more enjoyable and making parking,and hence driving,less affordable,should be used in tandem.The complementary nature of the two approaches makes it so the effect of the combination is greater than the sum of the two.展开更多
To investigate bicyclists' behavior at unsignalized intersections with mixed traffic flow, a bicycle capacity model of borrowed-priority merge was developed by the addition-conflict-flow procedure. Based on the actua...To investigate bicyclists' behavior at unsignalized intersections with mixed traffic flow, a bicycle capacity model of borrowed-priority merge was developed by the addition-conflict-flow procedure. Based on the actual traffic situation, the concept of borrowed priority, in which the majorroad bicycles borrow the priority of major-road cars to enter the intersections when consecutive headway for major-steam cars is lower than the critical gap for minor-road cars, was addressed. Bicycle capacity at a typical unsignalized intersection is derived by the addition-conflict-flow procedure. The proposes model was validated by the empirical investigation. Numerical results show that bicycle capacity at an intersection is the function of major-road and minor-road car streams. Bicycle capacity increases with increasing major-road cars but decreases with increasing minorroad cars.展开更多
The types of urban-rural recreational greenways were summarized,based on bicycle tourism and their planning methodology was explored.Taking the urban and rural areas of Harbin City as the research objects,the current ...The types of urban-rural recreational greenways were summarized,based on bicycle tourism and their planning methodology was explored.Taking the urban and rural areas of Harbin City as the research objects,the current situation of urban-rural recreational greenway environment and tourism resources was investigated and the evaluation system of bicycle tourism resources was established and tourism resources were evaluated according to the AHP-fuzzy comprehensive evaluation method to select suitable resources for bicycle tourism.Through the ArcGIS software,the currently available resources(rivers,wetlands,transportations and urban-layout)and suitable bicycle tourism resources were superimposed,and the spatial pattern planning and classification planning of urban-rural recreational greenway based on bicycle tourism were carried out.To the end,insights for the development of urbanrural recreational greenway in the future were provided.展开更多
The aim was to study the suitability of the heart rate variability (HRV) spectral parameters for evaluations of bicycle ergometry results in coronary heart disease (CHD) patients. Methods. Our study included 243 male ...The aim was to study the suitability of the heart rate variability (HRV) spectral parameters for evaluations of bicycle ergometry results in coronary heart disease (CHD) patients. Methods. Our study included 243 male CHD patients aged 49±8 years. The coronary atherosclerosis was assessed by coronary angiography. The results of bicycle ergometry, Doppler echocardio-graphy and HRV spectral analysis were also analyzed. The duration of each stage of bicycle ergometry was 3 min, the initial load value was 25 W. Dynamic load continued until the patient had reached 75% of heart rate from his maximal age level. The maximal level of load achieved (i.e. load tolerance) was taken into consideration. We calculated sensitivity (Se), specificity (Sp), likelihood ratios of positive (LR+) and negative (LR-) bicycle ergometry results. Results. All patients had similar clinical characteristics. LR+ become maximal under the moderate load tolerance. LR- are maximal in the CHD patients with high load tolerance. Thus, the excessiveness of false-negative results of bicycle ergometry is in CHD patients with high load tolerance. Reliability of results of bicycle ergometry increased under using assessments of low-frequency (LF) range power of HRV spectrum. Conclusions. Thus,the using of LF range power of HRV spectrum increases reliability of bicycle ergometry (or other load tests) results in CHD patients.展开更多
This paper evaluates different factors and parameters contributing to likelihood of bicycle crash injury severity levels. Multinomial Logit (MNL) model was used to analyze impact of different roadway features, traffic...This paper evaluates different factors and parameters contributing to likelihood of bicycle crash injury severity levels. Multinomial Logit (MNL) model was used to analyze impact of different roadway features, traffic characteristics and environmental conditions associated with bicycle crash injury severities. The multinomial model was used due to its flexibility in quantifying the effect of the independent variables for each injury severity categories. Model results showed that, severity of bicycle crashes increases with increase in vehicles per lane, number of lanes, bicyclist alcohol or drug use, routes with 35-45 mph posted speed limits, riding along curved or sloped road sections, when bicyclists approach or cross a signalized intersection, and at driveways. In addition, routes with a high percentage of trucks, roadway sections with curb and gutter, cloudy or foggy weather and obstructed vision were found to have high probability of severe injury. Segments with wider lanes, wide median and wide shoulders were found to have low likelihood of severe bicycle injury severities. Limited lighting locations was found to be associated with incapacitating injury and fatal crashes, indicating that insufficient visibility can potentially lead to severe crashes. Other findings are also presented in the paper.展开更多
基金supported by the New Energy Vehicle Power Battery Life Cycle Testing and Verification Public Service Platform Project[2022-235-224]the Beijing Science and Technology Planning Project[Z221100005222004]+1 种基金the Key Technologies Research and Development Program[2021YFB2012504]the Beijing Goldenbridge Project[ZZ2023002]。
文摘In this study,a detailed analysis of the combustion behaviors of the lithium iron phosphate(LFP)and lithium manganese oxide(LMO)batteries used in electric bicycles was conducted.This research included quantitative measurements of the combustion duration,flame height,combustion temperature,heat release rate,and total heat release.The results indicated that LMO batteries exhibited higher combustion temperatures of 600–700°C,flame heights of 70–75 cm,a significantly higher heat release rate of40.1 k W(12 Ah),and a total heat release of 1.04 MJ(12 Ah)compared to LFP batteries with the same capacity.Based on these experimental results,a normalized total heat release(NORTHR)parameter was proposed,demonstrating good universality for batteries with different capacities.Utilizing this parameter,quantitative calculations and optimization of the extinguishing agent dosage were conducted for fires involving these two types of batteries,and the method was validated by extinguishing fires for these two types of battery packs with water-based extinguishing fluids.
基金supported by the Ningxia Key Research and Development Program(Talent Introduction Special Project)Project(2022YCZX0013)North Minzu University 2022 School-Level Scientific Research Platform“Digital Agriculture Enabling Ningxia Rural Revitalization Innovation Team”(2022PT_S10)+1 种基金Yinchuan City University-Enterprise Joint Innovation Project(2022XQZD009)Ningxia Key Research and Development Program(Key Project)Project(2023BDE02001).
文摘Wearing helmetswhile riding electric bicycles can significantly reduce head injuries resulting fromtraffic accidents.To effectively monitor compliance,the utilization of target detection algorithms through traffic cameras plays a vital role in identifying helmet usage by electric bicycle riders and recognizing license plates on electric bicycles.However,manual enforcement by traffic police is time-consuming and labor-intensive.Traditional methods face challenges in accurately identifying small targets such as helmets and license plates using deep learning techniques.This paper proposes an enhanced model for detecting helmets and license plates on electric bicycles,addressing these challenges.The proposedmodel improves uponYOLOv8n by deepening the network structure,incorporating weighted connections,and introducing lightweight convolutional modules.These modifications aim to enhance the precision of small target recognition while reducing the model’s parameters,making it suitable for deployment on low-performance devices in real traffic scenarios.Experimental results demonstrate that the model achieves an mAP@0.5 of 91.8%,showing an 11.5%improvement over the baselinemodel,with a 16.2%reduction in parameters.Additionally,themodel achieves a frames per second(FPS)rate of 58,meeting the accuracy and speed requirements for detection in actual traffic scenarios.
基金the Public Projects of Zhejiang Province,China(Nos.2016C33110,2015C33067)National Natural Science Foundations of China(Nos.61602141,61473108,61402141)
文摘Bicycle sharing system has emerged as a new mode of transportation in many big cities over the past decade.Since the large number of bicycle stations distribute widely in the city,it is difficult to identify their unique attributes and characteristics directly.Oriented to the real bicycle hire dataset in Hangzhou,China,the clustering analysis for the bicycle stations based on the temporal flow data was carried out firstly.Then,based on the spatial distribution and temporal attributes of calculated clusters,visual diagram and map were used to vividly analyze the bicycle hire behavior related to station category and study the travel rules of citizens.The experimental results demonstrate the relation between human mobility,the time of day,day of week and the station location.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51578247)
文摘In order to improve the public transit’s accessibility and promote service quality of the public transit,it is necessary to alleviate the“last⁃mile”problem.The combination of the public transit and bicycle⁃sharing system is competitive compared with the private car.In 2016,the dockless bicycle⁃sharing system has been undergoing tremendous development.Because the dockless bicycle⁃sharing system is different from previous bicycle⁃sharing systems,components of service quality of the dockless bicycle⁃sharing system differ.However,there are few articles about the service quality of the dockless bicycle⁃sharing system.This paper examined the evaluation of service quality of the dockless bicycle⁃sharing system along with a measurement of users’satisfaction.A questionnaire about service quality was designed,which includes 15 factors.Through the analysis of travelers’evaluation of factors of the dockless bicycle⁃sharing system with Rasch Model,these original ordinal data(Likert data)was transformed to the interval data:the person parameter(ability)and the item parameter(difficulty).Through the analysis of interviewees’abilities,it was found that only education and monthly consumption have significant influence on interviewees’evaluation of service quality of the dockless bicycle⁃sharing system,while there is no significant influence of gender,weekly use of dockless shared⁃bicycle,private car ownership,or monthly income on the evaluation.Furthermore,it was found that users were dissatisfied with cycling under the adverse weather,disturbance from pedestrians and cars,continuity of the bicycle lane,complaint channel,and staff service the most.
基金This work was supported by the Natural Science Foundation of China(51608473)Shanghai philosophy and social science planning project(No.2017ECK004)+1 种基金2017 Zhejiang Provincial Department of Education General Research Project(Natural Science)(Y201738361)USST Innovation and Entrepreneurship Training Program(XJ2019132).
文摘Public bicycle service has experienced 15 years of development in Chinese cities,and China's Mainland is the world's largest public bicycle market.Choosing to use public bicycles is becoming more and more a daily habit of residents.Broadly speaking,public bicycles in Chinese cities include both public bikes with service stations and shared bicycles without service stations.Based on historical review and years of accumulated data,this paper reviews the development of general public bicycles in Chinese cities in the past 15 years.And the role of general public bicycles in China’s urban transportation system is analyzed.Finally,from the perspective of urban construction and management,some suggestions for the future development of public bicycles are put forward.
文摘Objectives: The primary objective was to characterize the range of Knowledge, Attitude, and Practice (KAP) of Helmet use in children amongst parents to prevent head injuries and death. Methods: This is a cross-sectional study, done by online survey using a snowball sampling technique, the number of included responses were 386 parents (Male and female) living in Riyadh Aged 21 - 60 years old or above. Results: The study showed that there is a difference in Parents’ belief in the importance of helmet use while riding a Bicycle vs Motorcycle/Quad bike and that was affected by parents’ education level, almost all the people who answered the survey (76.7%) agree that it is important for their children to wear a helmet when riding both a Bicycle and a Motorcycle or Quadbike with a cumulative percentage of (93.8%). And almost all agreed on multiple approaches to help increase helmet use be it by forcing rental shops to give out helmets, forcing sellers to recommend the use of helmets, increasing awareness campaigns, and imposing fines for not wearing helmets. Conclusions: This study is the first to explore Family helmet use while riding Bicycles and Motorcycles/Quad bikes. Although Parent’s belief in the importance of helmet use for their children was high, it is clear that the level of practice is low. With that the risk of head injuries might be high, our findings suggest that safety interventions for increasing pediatric helmet use are needed to increase helmet use and reduce the risk of head injury and hospitalization.
基金Under the auspices of National Natural Science Foundation of China(No.41801150,41571146,41801144)Natural Science Foundation of Guangdong Province(No.2018A030310392)+2 种基金Guangdong Planning Project of Philosophy and Social Science(No.GD17YGL01)Science and Technology Program of Guangzhou(No.201906010033)GDAS’(Guangdong Academy of Sciences)Project of Science and Technology Development(No.2020GDASYL-20200104007)。
文摘Mobile information and communication technologies(MICTs) have fully penetrated everyday life in smart societies;this has greatly compressed time, space, and distance, and consequently, reshaped residents’ travel behaviour patterns. As a new mode of shared mobility, the sharing bicycle offers a variety of options for the daily travel of urban residents. Extant studies have mainly examined the travel characteristics and influencing factors of public bicycles with piles, while the travel patterns for sharing bicycles and their driving mechanisms have been largely ignored. Using one week’s travel data for Mobike, this study investigated the spatial and temporal distribution patterns of sharing bicycle travel behaviours in the central urban area of Guangzhou, China;furthermore, it identified the influences of built environment density factors on sharing bicycle travel behaviours based on the geographically weighted regression method. Obvious morning and evening peaks were observed in the sharing bicycle travel patterns for both weekdays and weekends. The old urban area, which had a high degree of mixed function, dense road networks, and cycling-friendly built environments, was the main travel area that attracted sharing bicycles on both weekdays and weekends. Furthermore, factors including the point of interest(POI) for the density of public transport stations, the functional mixing degree, and the density of residential POIs significantly affected residents’ travel behaviours. These findings could enrich discourse regarding shared mobility with a Chinese case characterised by rapidly developing MICTs and also provide references to local authorities for improving slow traffic environments.
基金supported by Tianjin Municipal Special Fund Project for Technology Innovation of China(Grant No.10FDZDGX00500),and Tianjin Municipal Key Laboratory of Advanced Manufacturing Technology and Equipment of Tianjin University of China
文摘With the development of technology and the change of market demands,the trend in middle and high grade bicycle manufacturing is developed toward small-volume,multi-species,and customer-oriented production.Therefore,human element should be fully considered in design so that the bicycle has the best cycling performance for the specific rider.Currently,customized design is difficult to achieve since feature parameters of the rider are not included in the design.The design of bicycle frame is the most important in bicycle design.The relative positions among the saddle,handlebar and central axis are defined as the bicycle three-pivot,they are the main parameters in bicycle frame design.In conventional bicycle design,frame parameters are merely relevant to bicycle types.On the basis of the principles of biomechanics and ergonomics knowledge,this paper presents a design method for bicycle three-pivot considering feature parameters of the rider by dynamic simulation.Firstly,a dynamic model of rider-bicycle system is built for a special rider,and a serial of simulation experiments is designed by uniform test method.Then,a mathematical model is built between the three-pivot position and the square of lower limb muscle stress by using simulation and regression analysis of the rider-bicycle system.The optimal three-pivot position parameters are obtained by setting the minimal of the square of the lower limb muscle stress as the objective.Therefore,the optimal parameters are gained for the specific rider.Finally,various results are gained for different riders based on the same design process.The function between feature parameters of the rider and the optimum three-pivot position parameters is built by regression.Bicycle design considering biomechanics can be divided into three main steps:calculating the three-pivot position,designing the geometrical structure of the bicycle frame and analyzing frame strength,and selecting appropriate parts and assembling the bicycle.Bicycle design considering biomechanics changes the conventional bicycle design and realizes customized design by considering human element in the design process.
文摘A collision model, an automobile model and a multi-rigid-body model in PC-crash are analyzed. By simulating a side collision accident between a car and an electric bicycle (EB), a method that reproduces the car-electric bicycle side collision accident based on PC-crash is presented according to some important information such as the final position, the contacting location between the cyclist and the car. A result is obtained by comparing with the reproduced result, the deformation of accident vehicle and the surveillance video. The rollover direction and fells-over sliding direction after the collision and the contacting location and wrap motion of cyclist and electric bicycle are fitting in with the real situation better compared with the reconstruction result in PC-crash. Then the responsive-surface method and MONTEKARLO method are used in MATLAB to analyze the uncertainty of the vehicle speed in reproduced scene results. And the range of values of the pre-collision speed is obtained which makes the reproduced result more objective and convincible that could provide the basis of the accident assessment.
基金Project supported by the National Natural Science Foundation of China(Nos.11772021 and 62073183)。
文摘The non-smooth dynamic model of an unmanned bicycle is established to study the contact-separate and stick-slip non-smooth phenomena between wheels and the ground.According to the Carvallo-Whipple configuration,the unmanned bicycle is reduced to four rigid bodies,namely,rear wheel,rear frame,front fork,and front wheel,which are connected by perfect revolute joints.The interaction between each wheel and the ground is simplified as the normal contact force and the friction force at the contact point,and these forces are described by the Hunt-Crossley contact force model and the Lu Gre friction force model,respectively.According to the characteristics of flat and curved pavements,calculation methods for contact forces and their generalized forces are presented.The dynamics of the system is modeled by the Lagrange equations of the first kind,a numerical solution algorithm of the dynamic equations is presented,and the Baumgarte stabilization method is used to restrict the drift of the constraints.The correctness of the dynamic model and the numerical algorithm is verified in comparison with the previous studies.The feasibility of the proposed model is demonstrated by simulations under different motion states.
基金This work was supported in part by the Ministry of Education of the People’s Republic of China Project of Humanities and Social Sciences under Grant No.19YJCZH208,author X.X,http://www.moe.gov.cn/in part by the Philosophy and Social Science Foundation Project of Hunan Province under Grant No.15YBA406,author X.X,http://www.hnsk.gov.cn/+3 种基金in part by the Social Science Evaluation Committee Project of Hunan Province under Grant No.XSP18YBZ125,author X.X,http://www.hnsk.gov.cn/in part by the Social Sciences Federation Think Tank Project of Hunan Province under Grant No.ZK2019025,author X.X,http://www.hnsk.gov.cn/in part by the Education Bureau Research Foundation Project of Hunan Province under Grant No.20A531,author X.X,http://jyt.hunan.gov.cn/in part by the Science and Technology Project of Changsha City,under Grant No.kq2004092,author X.X,http://kjj.changsha.gov.cn/.
文摘Vehicle–bicycle conflict incurs a higher risk of traffic accidents,particularly as it frequently takes place at intersections.Mastering the traffic characteristics of vehicle–bicycle conflict and optimizing the design of intersections can effectively reduce such conflict.In this paper,the conflict between right-turning motor vehicles and straight-riding bicycles was taken as the research object,and T-Analyst video recognition technology was used to obtain data on riding(driving)behavior and vehicle–bicycle conflict at seven intersections in Changsha,China.Herein,eight typical traffic characteristics of vehicle–bicycle conflict are summarized,the causes of vehicle–bicycle conflict are analyzed using 18 factors in three dimensions,the internal relationship between intersection design factors and traffic conflicts is explored,and the guiding of design optimization based on the width of bicycle lanes and the soft separation between vehicles and bicycles is discussed.The results showed that colored paved bicycle lanes were better,performing better at a width of 2.5 m compared to 1.5 m.However,the colored pavement was not suitable for the entire road and had to be set at the position,at which the trajectories of a bicycle and motor vehicle overlapped.Thus,a 2.5-m-wide bicycle lane provides good safety.However,there are still defects in the existing safety indicators,so it is necessary to develop new indicators to reflect real vehicle–bicycle conflict situations more comprehensively.
文摘Sustainable and practical personal mobility solutions for campus environments have traditionally revolved around the use of bicycles, or provision of pedestrian facilities. However many campus environments also experience traffic congestion, parking difficulties and pollution from fossil-fuelled vehicles. It appears that pedal power alone has not been sufficient to supplant the use of petrol and diesel vehicles to date, and therefore it is opportune to investigate both the reasons behind the continual use of environmentally unfriendly transport, and consider potential solutions. This paper presents the results from a year-long study into electric bicycle effectiveness for a large tropical campus, identifying barriers to bicycle use that can be overcome through the availability of public use electric bicycles.
文摘Background: Cycling as a means of transport contributes to public health in terms of increasing the physical activity behaviour and reducing air pollution. In comparison to walking, cycling-spe cific environmental characteristics have been less investigated. The aim of this study was to develop, based on geographic information systems (GIS) data, a bikeability index for a mid-sized European city, to examine the predictive validity of the index and to visualize the bicycle-friendliness of the city by creating a bikeability map. Methods: Using GIS data, we assessed the environmental characteristics of 278 bicycle trips in the city of Graz, Austria. Characteristics which differed significantly between the actually taken and shortest possible routes were used to form an additive bikeability index and the bikeability map for 100 m × 100 m cells. The relationship between the cycling behaviour and the bikeability index around the home environment was examined to assess the predictive validity of the index. Results: Three environmental components (cycling infrastructure, bicycle pathways and green areas) were positively related, and two components (main roads, and topography) were negatively related to the actually used route. These components formed the bikeability index, which was positively correlated with cycling behaviour (OR: 1.08, 95% CI 1.01 - 1.17). The final outcome is a high-resolution coloured map indicating the degree of bicycle-friendliness in the city of Graz. Conclusion: Mapping based on the bikeability index helps to visualize the bicycle-friendliness of an urban area. Therefore, it should be a useful tool for the planning as well as for the evaluation of the transport environments in cities.
文摘Background: Physical fitness tests are widely used to assess endurance,sprint ability,coordination and/or strength.The objective of the present study was to analyze the degree to which the results of the Bundeswehr Basis Fitness Test(BFT)–a physical fitness test comprising a sprint test(11×10-m shuttle test),a flexed-arm hang test and a 1000-m run–are consistent with the output measured during a bicycle ergometer test.The number of false-positive and falsenegative results with regard to the assessment of physical fitness were also examined.Methods: As part of a retrospective study,health assessments from 323 reenlistment examinations were evaluated regarding the output measured during a bicycle ergometer test and compared with the BFT results of the candidates.Results: Overall,a good correlation was shown between the bicycle ergometer test results and the results achieved in the BFT disciplines.All three disciplines of the BFT showed a highly significant correlation with the relative output achieved during the bicycle ergometer test(P<0.001),and also,the overall BFT score was highly significantly correlated(P<0.001).The overall rate of false-positive and false-negative results was 4.0%.Conclusion: The BFT results measured in the three physical fitness test items were highly correlated with the output measured during the bicycle ergometer tests.The rate of false-positive and false-negative results was low.The test items thus represent an appropriate measurement instrument because the test items require few equipment and less time.Additionally,a large number of subjects can be assessed.We suggest that it would be more useful to assess the physical fitness of this special group exclusively on the basis of the BFT instead of using the bicycle ergometer test.
文摘Smart growth policies advocate for economically viable,environmentally conscientious,and socially equitable solutions for urban development.These policies were developed largely in response to issues rooted in the automobile-oriented culture:air pollution,high greenhouse gas emissions,traffic congestion,and sedentary lifestyles.In urban settings,a good transportation alternative is cycling,since it is able to serve the travel needs of nearly half of city dwellers' daily trips.Many European and Canadian cities have successfully increased cycling rates by creating safer bicycle environments and restricting or discouraging automobile use.To evaluate the potential effects of the above measures on American urban areas,this paper examines case studies of cycle tracks and bicycle boulevards implemented in American cities,and how these facility improvements have changed how safe cyclists feel on the road and overall bicycle usage.Results show the two methods are indeed effective in increasing bicycle usage rates.Ultimately,increasing cycling rates needs policies to discourage people from driving,the greatest mode share in nearly all urban areas.Parking policy has major impacts on people's decision to use the automobile.Currently,parking is oversupplied and underpriced in many cities,making it irresistible for people to drive.Decreasing the number of parking spaces available and increasing their price will increase pressure on drivers to drive less,especially for short trips,and to bike instead.It is important for planners and policy makers to realize that solutions from both directions,making biking more enjoyable and making parking,and hence driving,less affordable,should be used in tandem.The complementary nature of the two approaches makes it so the effect of the combination is greater than the sum of the two.
基金Supported by the National Basic Research Program of China (2012CB725400)the National Natural Science Foundation of China(70901005+2 种基金7107101671131001)Fundamental Research Funds for the Central Universities(2011JBM055)
文摘To investigate bicyclists' behavior at unsignalized intersections with mixed traffic flow, a bicycle capacity model of borrowed-priority merge was developed by the addition-conflict-flow procedure. Based on the actual traffic situation, the concept of borrowed priority, in which the majorroad bicycles borrow the priority of major-road cars to enter the intersections when consecutive headway for major-steam cars is lower than the critical gap for minor-road cars, was addressed. Bicycle capacity at a typical unsignalized intersection is derived by the addition-conflict-flow procedure. The proposes model was validated by the empirical investigation. Numerical results show that bicycle capacity at an intersection is the function of major-road and minor-road car streams. Bicycle capacity increases with increasing major-road cars but decreases with increasing minorroad cars.
基金Supported by Heilongjiang Natural Science Funding Project"Ecological Evaluation of Planning and Designing of Water Landscape for Farmland in Cold Field"(E2015022)。
文摘The types of urban-rural recreational greenways were summarized,based on bicycle tourism and their planning methodology was explored.Taking the urban and rural areas of Harbin City as the research objects,the current situation of urban-rural recreational greenway environment and tourism resources was investigated and the evaluation system of bicycle tourism resources was established and tourism resources were evaluated according to the AHP-fuzzy comprehensive evaluation method to select suitable resources for bicycle tourism.Through the ArcGIS software,the currently available resources(rivers,wetlands,transportations and urban-layout)and suitable bicycle tourism resources were superimposed,and the spatial pattern planning and classification planning of urban-rural recreational greenway based on bicycle tourism were carried out.To the end,insights for the development of urbanrural recreational greenway in the future were provided.
文摘The aim was to study the suitability of the heart rate variability (HRV) spectral parameters for evaluations of bicycle ergometry results in coronary heart disease (CHD) patients. Methods. Our study included 243 male CHD patients aged 49±8 years. The coronary atherosclerosis was assessed by coronary angiography. The results of bicycle ergometry, Doppler echocardio-graphy and HRV spectral analysis were also analyzed. The duration of each stage of bicycle ergometry was 3 min, the initial load value was 25 W. Dynamic load continued until the patient had reached 75% of heart rate from his maximal age level. The maximal level of load achieved (i.e. load tolerance) was taken into consideration. We calculated sensitivity (Se), specificity (Sp), likelihood ratios of positive (LR+) and negative (LR-) bicycle ergometry results. Results. All patients had similar clinical characteristics. LR+ become maximal under the moderate load tolerance. LR- are maximal in the CHD patients with high load tolerance. Thus, the excessiveness of false-negative results of bicycle ergometry is in CHD patients with high load tolerance. Reliability of results of bicycle ergometry increased under using assessments of low-frequency (LF) range power of HRV spectrum. Conclusions. Thus,the using of LF range power of HRV spectrum increases reliability of bicycle ergometry (or other load tests) results in CHD patients.
文摘This paper evaluates different factors and parameters contributing to likelihood of bicycle crash injury severity levels. Multinomial Logit (MNL) model was used to analyze impact of different roadway features, traffic characteristics and environmental conditions associated with bicycle crash injury severities. The multinomial model was used due to its flexibility in quantifying the effect of the independent variables for each injury severity categories. Model results showed that, severity of bicycle crashes increases with increase in vehicles per lane, number of lanes, bicyclist alcohol or drug use, routes with 35-45 mph posted speed limits, riding along curved or sloped road sections, when bicyclists approach or cross a signalized intersection, and at driveways. In addition, routes with a high percentage of trucks, roadway sections with curb and gutter, cloudy or foggy weather and obstructed vision were found to have high probability of severe injury. Segments with wider lanes, wide median and wide shoulders were found to have low likelihood of severe bicycle injury severities. Limited lighting locations was found to be associated with incapacitating injury and fatal crashes, indicating that insufficient visibility can potentially lead to severe crashes. Other findings are also presented in the paper.