The dockless bike-sharing system has rapidly expanded worldwide and has been widely used as an intermodal transport to connect with public transportation.However,higher flexibility may cause an imbalance between suppl...The dockless bike-sharing system has rapidly expanded worldwide and has been widely used as an intermodal transport to connect with public transportation.However,higher flexibility may cause an imbalance between supply and demand during daily operation,especially around the metro stations.A stable and efficient rebalancing model requires spatio-temporal usage patterns as fundamental inputs.Therefore,understanding the spatio-temporal patterns and correlates is important for optimizing and rescheduling bike-sharing systems.This study proposed a dynamic time warping distance-based two-dimensional clustering method to quantify spatio-temporal patterns of dockless shared bikes in Wuhan and further applied the multiclass explainable boosting machine to explore the main related factors of these patterns.The results found six patterns on weekdays and four patterns on weekends.Three patterns show the imbalance of arrival and departure flow in the morning and evening peak hours,while these phenomena become less intensive on weekends.Road density,living service facility density and residential density are the top influencing factors on both weekdays and weekends,which means that the comprehensive impact of built-up environment attraction,facility suitability and riding demand leads to the different usage patterns.The nonlinear influence universally exists,and the probability of a certain pattern varies in different value ranges of variables.When the densities of living facilities and roads are moderate and the relationship between job and housing is relatively balanced,it can effectively promote the balanced usage of dockless shared bikes while maintaining high riding flow.The spatio-temporal patterns can identify the associated problems such as imbalance or lack of users,which could be mitigated by corresponding solutions.The relative importance and nonlinear effects help planners prioritize strategies and identify effective ranges on different patterns to promote the usage and efficiency of the bike-sharing system.展开更多
If you have been in Beijing for any length of time, you will have come to realize that there are several modes of transportation available to commuters, all ofthem relatively in expensive, especially
As time goes by,shared bikes have become an essential element in people's life.However,due to the limited number and uneven distribution of shared bikes,it has brought some troubles to people's daily travel.In...As time goes by,shared bikes have become an essential element in people's life.However,due to the limited number and uneven distribution of shared bikes,it has brought some troubles to people's daily travel.In this paper,we establish an empty vehicle scheduling model with normal distribution and study the empty vehicle scheduling problem of shared bikes.This paper establishes a model based on real life,assumes different scheduling schemes,and compares different assumptions,so as to get better empty vehicle scheduling schemes.In this way,shared bikes will be more conducive to People's Daily travel and bring more convenience to people.展开更多
Existing research models can neither indicate the availability of shared bikes nor detect unusable ones owing to a lack of information on bike maintenance and failure.To improve awareness regarding the availability of...Existing research models can neither indicate the availability of shared bikes nor detect unusable ones owing to a lack of information on bike maintenance and failure.To improve awareness regarding the availability of shared bikes,we propose an innovative approach for detecting unusable shared bikes based on reinforcement learning and the PageRank algorithm.The proposed method identifies unusable shared bikes depending on the local travel data and provides a ranking of the shared bikes according to their availability levels.Given a sliding time window,the value function for the reinforcement learning model was determined by considering the cumulative number of unavailable shared bikes,the proportion of rental cancelations at the same stations,and the mean time between the cancelations.Reinforcement learning was then used to identify shared bikes with the worst availability.An availability ranking for the shared bikes below the reward threshold was performed using the PageRank algorithm.The proposed detection approach was applied to a trip dataset of a real-world bike-sharing system to illustrate the modeling process and its effectiveness.The detection results of unusable shared bikes in the absence of failure and feedback data can provide essential information to support the maintenance management decisions regarding shared bikes.展开更多
The e-commerce industry has experienced significant growth in the past decade,particu-larly post-COVID.To accommodate such growth,the parcel delivery sector has also grown rapidly.However,there is a lack of study that...The e-commerce industry has experienced significant growth in the past decade,particu-larly post-COVID.To accommodate such growth,the parcel delivery sector has also grown rapidly.However,there is a lack of study that properly evaluates its social and environ-mental impacts at a large scale.A model is proposed to analyze such impacts.A parcel gen-eration process is presented to convert public data into parcel volumes and stops.A continuous approximation model is fitted to estimate the length of parcel service tours.A case study is conducted using New York City(NYC)data.The parcel generation is shown to be a valid fit.The continuous approximation model parameters have R2 values of 98%or higher.The model output is validated against UPS truck trips.Application of the model to 2021 suggests residential parcel deliveries contributed to 0.05%of total daily vehicle-kilometer-traveled(VKT)in NYC corresponding to 14.4 metric tons of carbon equivalent(MTCE)emissions per day.COVID-19 contributed to an increase in parcel deliveries that led to up to 1064.3 MTCE of annual greenhouse gas(GHG)emissions in NYC(which could power 532 standard US households for a year).The existing bike lane infrastructure can support the substitution of 17%of parcel deliveries by cargo bikes,which would reduce VKT by 11%.Adding 3 km of bike lanes to connect Amazon facilities can expand their cargo bike substitution benefit from a VKT reduction of 5%up to 30%.If 28 km of additional bike lanes are made,parcel delivery substitution citywide could increase from 17%to 34%via cargo bike and save an additional 2.3 MTCE per day.Cargo bike priorities can be set to reduce GHG emissions for lower-income neighborhoods including Harlem,Sunset Park,and Bushwick.展开更多
Shijiazhuang,the capital of Hebei,is a reallyhappy city.It is often called the city of well-beingin China.The city has a nice living environment.Thereare lots of beautiful parks where people can walk,exercise,or just ...Shijiazhuang,the capital of Hebei,is a reallyhappy city.It is often called the city of well-beingin China.The city has a nice living environment.Thereare lots of beautiful parks where people can walk,exercise,or just relax on weekends.The air isgetting cleaner,and the streets are cleaner,too.Transportation in Shijiazhuang is very convenient.Subways,buses,and shared bikes can take youeverywhere.Shijiazhuang also has a rich culture.展开更多
当前美国国家标准与技术研究院(National Institute of Standards and Technology,NIST)对后量子密码(Post-Quantum Cryptography,PQC)标准化方案的评估已进入第四轮,位翻转密钥封装(Bit Flipping Key Encapsulation,BIKE)协议是目前被...当前美国国家标准与技术研究院(National Institute of Standards and Technology,NIST)对后量子密码(Post-Quantum Cryptography,PQC)标准化方案的评估已进入第四轮,位翻转密钥封装(Bit Flipping Key Encapsulation,BIKE)协议是目前被评估的四个候选方案之一.在BIKE的密钥生成算法中,多项式乘法作为众多密码系统中特别耗时的操作之一,耗费了大量的时间和面积资源.针对此问题,本文设计了一种基于Karatsuba算法(Karatsuba Algorithm,KA)的无交叠多项式乘法器,可高效实现万级比特位宽的多项式乘法,具有低时延、高性能和面积小的特点.同时,本文将该优化乘法器应用于BIKE密钥生成算法中,并基于现场可编程门阵列(Field Programmable Gate Array,FPGA)对其进行硬件架构实现,改进了原有的紧凑多项式乘法和多项式求逆算法.本文提出的乘法器通过采用不同的操作数位宽,可适应对面积和延时的不同需求.与BIKE原本的设计相比,改进的设计使密钥生成模块的延时减小了36.54%,面积延迟积(Area Delay Production,ADP)减小了10.4%.展开更多
On the morning of 23 December 2024,the Panda Pack and Bike Donation Ceremony in Cambodia under the Action Plan on Silk Road People-to-People Connectivity was held at Balaing Khang Lech Primary School in Kampong Thom P...On the morning of 23 December 2024,the Panda Pack and Bike Donation Ceremony in Cambodia under the Action Plan on Silk Road People-to-People Connectivity was held at Balaing Khang Lech Primary School in Kampong Thom Province.Over 150 participants including Kemreat Viseth,Deputy Director of the Council of Ministers of Cambodia and President of Civil Society Alliance Forum(CSAF),Nhek Ban Kheng,Deputy Governor of Kampong Thom Province.展开更多
Among the four candidate algorithms in the fourth round of NIST standardization,the BIKE(Bit Flipping Key Encapsulation)scheme has a small key size and high efficiency,showing good prospects for application.However,th...Among the four candidate algorithms in the fourth round of NIST standardization,the BIKE(Bit Flipping Key Encapsulation)scheme has a small key size and high efficiency,showing good prospects for application.However,the BIKE scheme based on QC-MDPC(Quasi Cyclic Medium Density Parity Check)codes still faces challenges such as the GJS attack and weak key attacks targeting the decoding failure rate(DFR).This paper analyzes the BGF decoding algorithm of the BIKE scheme,revealing two deep factors that lead to DFR,and proposes a weak key optimization attack method for the BGF decoding algorithm based on these two factors.The proposed method constructs a new weak key set,and experiment results eventually indicate that,considering BIKE’s parameter set targeting 128-bit security,the average decryption failure rate is lowerly bounded by.This result not only highlights a significant vulnerability in the BIKE scheme but also provides valuable insights for future improvements in its design.By addressing these weaknesses,the robustness of QC-MDPC code-based cryptographic systems can be enhanced,paving the way for more secure post-quantum cryptographic solutions.展开更多
As the economy and technology keep growing,the mode of shared bikes gains popularity under these circumstances.At the current period,university students become fond of using shared bikes,which changes body health and ...As the economy and technology keep growing,the mode of shared bikes gains popularity under these circumstances.At the current period,university students become fond of using shared bikes,which changes body health and life style of university students.When this mode combines the characteristics and functions of shared bikes,it has a great impact on the awareness and motivation of work-out of university students.Supported by Internet technology,shared bikes meet the need of people that they can use them at any time,which is new and innovative to the university students.This article provides university students with shared bike service in campus by analyzing the influence of“Internet+shared bike”on health and sports of university students.It will promote the effective application of shared bikes.展开更多
Mobility is among the urban issues that most affect the population’s quality of life.The complexity inherent to mobility requires the development and application of methods and tools that enable a better understandin...Mobility is among the urban issues that most affect the population’s quality of life.The complexity inherent to mobility requires the development and application of methods and tools that enable a better understanding of their interrelationships.In this sense,the use of indicators is important for the analysis of current mobility conditions,as well as allowing the monitoring of the impact of public policies and the evolution of certain phenomena and actions.Thus,the objective is to study the cycling modal in urban mobility in the city of Vitória,Espírito Santo,during the period of the new coronavirus pandemic,through the application of two indicators:the cycling network increase and the traffic accident reduction.It is considered that the demand for the use of public transport and motor vehicles has decreased due to social isolation.The methodology includes a literature review on the studied subject;urban mobility indicators selection;data collection from public agencies;and analysis of the results.The results reveal that indicators are required to support the proposition of public policies,targeting of actions,identification of areas in need of investments and mainly can reflect the pandemic influence on urban mobility.展开更多
In order to study the spatiotemporal characteristics of the dockless bike sharing system(BSS)around urban rail transit stations,new normalized calculation methods are proposed to explore the temporal and spatial usage...In order to study the spatiotemporal characteristics of the dockless bike sharing system(BSS)around urban rail transit stations,new normalized calculation methods are proposed to explore the temporal and spatial usage patterns of the dockless BSS around rail transit stations by using 5-weekday dockless bike sharing trip data in Nanjing,China.First,the rail transit station area(RTSA)is defined by extracting shared bike trips with trip ends falling into the area.Then,the temporal and spatial decomposition methods are developed and two criterions are calculated,namely,normalized dynamic variation of bikes(NDVB)and normalized spatial distribution of trips(NSDT).Furthermore,the temporal and spatial usage patterns are clustered and the corresponding geographical distributions of shared bikes are determined.The results show that four temporal usage patterns and two spatial patterns of dockless BSS are finally identified.Area type(urban center and suburb)has a great influence on temporal usage patterns.Spatial usage patterns are irregular and affected by limited directions,adjacent rail transit stations and street networks.The findings can help form a better understanding of dockless shared bike users behavior around rail transit stations,which will contribute to improving the service and efficiency of both rail transit and BSS.展开更多
As children mature, bike products for children in the market develop at the same time, and the conditions are frequently updated. Certain problems occur when using a bike, such as cycle overlapping, repeating function...As children mature, bike products for children in the market develop at the same time, and the conditions are frequently updated. Certain problems occur when using a bike, such as cycle overlapping, repeating function, and short life cycle, which go against the principles of energy conservation and the environmental protection intensive design concept. In this paper, a rational multi-function method of design through functional superposition, transformation, and technical implementation is proposed. An organic combination of frog-style scooter and children’s tricycle is developed using the multi-function method. From the ergonomic perspective, the paper elaborates on the body size of children aged 5 to 12 and effectively extracts data for a multi-function children’s bike, which can be used for gliding and riding. By inverting the body, parts can be interchanged between the handles and the pedals of the bike. Finally, the paper provides a detailed analysis of the components and structural design, body material, and processing technology of the bike. The study of Industrial Product Innovation Design provides an effective design method to solve the bicycle problems, extends the function problems, improves the product market situation, and enhances the energy saving feature while implementing intensive product development effectively at the same time.展开更多
This paper investigates the dynamic design methodology of mountain bikes with rear suspension. Firstly, a multi-rigid body dynamic model of rider and mountain bike coupled system is constructed. The rider model includ...This paper investigates the dynamic design methodology of mountain bikes with rear suspension. Firstly, a multi-rigid body dynamic model of rider and mountain bike coupled system is constructed. The rider model includes 19 skeletons, 18 joints and 118 main muscles. Secondly, to validate the feasibility of the model, an experiment test is designed to reflect the real cycling status. Finally, aiming at enhancing the performance of the rider vibration comfort, the scale parameters of rear suspension are optimized with computer simulation and uniform design. The mathematical model in the vibration performance and the design variables is constructed with regression analysis. The result shows that when the length of side link is 90 mm, the length of connected rod is 336.115 1 mm and the included angle between absorber and side link is 60°, the mountain bike has better vibration comfort. This study and relevant conclusions are of practical importance to the design of the mountain bike＇s rear suspension system.展开更多
Life-cycle assessment (LCA) is environmental evaluation of products, materials, and processes over their life cycle. Truncation uncertainty and corresponding uncertainty are main problems occurred in process life cycl...Life-cycle assessment (LCA) is environmental evaluation of products, materials, and processes over their life cycle. Truncation uncertainty and corresponding uncertainty are main problems occurred in process life cycle assessment (PLCA) modeling and economic input-output life cycle assessment (EIOLCA) modeling. Through combination of these two modelings in different life cycle stage and use of an uncertainty reduction strategy, a hybrid life cycle assessment modeling method was proposed in this study. Case studies were presented on gasoline-powered motorbikes (M-bike) and electricity-powered electric bike (E-bike). Web-based software was developed to analyze process environmental impacts. Results show that the largest part of life cycle energy (LCE) is consumed at use stage. Less energy is consumed in life cycle of E-bike than that of M-bike. GWP (Global Warming Potential), CO (Carbon Monoxide), PM10 (particulate matter) emission of M-bike are higher than that of E-bike, especially at use stage, AP (acidification Potential) emission of E-bike is higher than that of M-bike. Comprehensively, E-bike is energy efficient and less emitting, and better choice for urban private transportation.展开更多
Research on design of bicycles is concentrated on mechanism and auto appearance design, however few on matches between the bike and the rider. Since unreasonable human-bike relationship leads to both riders＇ worn-out...Research on design of bicycles is concentrated on mechanism and auto appearance design, however few on matches between the bike and the rider. Since unreasonable human-bike relationship leads to both riders＇ worn-out joints and muscle injuries, the design of bicycles should focus on the matching. In order to find the best position of human-bike system, simulation experiments on riding comfort under different riding postures are done with the lifemode software employed to facilitate the cycling process as well as to obtain the best position and the size function of it. With BP neural network and GA, analyzing simulation data, conducting regression analysis of parameters on different heights and bike frames, the equation of best position of human-bike system is gained at last. In addition, after selecting testers, customized bikes based on testers＇ height dimensions are produced according to the size function. By analyzing and comparing the experimental data that are collected from testers when riding common bicycles and customized bicycles, it is concluded that customized bicycles are four times even six times as comfortable as common ones. The equation of best position of human-bike system is applied to improve bikes＇ function, and the new direction on future design of bicycle frame parameters is presented.展开更多
基金supported by the National Key Research and Development Program of China[grant number 2017YFB0503601]。
文摘The dockless bike-sharing system has rapidly expanded worldwide and has been widely used as an intermodal transport to connect with public transportation.However,higher flexibility may cause an imbalance between supply and demand during daily operation,especially around the metro stations.A stable and efficient rebalancing model requires spatio-temporal usage patterns as fundamental inputs.Therefore,understanding the spatio-temporal patterns and correlates is important for optimizing and rescheduling bike-sharing systems.This study proposed a dynamic time warping distance-based two-dimensional clustering method to quantify spatio-temporal patterns of dockless shared bikes in Wuhan and further applied the multiclass explainable boosting machine to explore the main related factors of these patterns.The results found six patterns on weekdays and four patterns on weekends.Three patterns show the imbalance of arrival and departure flow in the morning and evening peak hours,while these phenomena become less intensive on weekends.Road density,living service facility density and residential density are the top influencing factors on both weekdays and weekends,which means that the comprehensive impact of built-up environment attraction,facility suitability and riding demand leads to the different usage patterns.The nonlinear influence universally exists,and the probability of a certain pattern varies in different value ranges of variables.When the densities of living facilities and roads are moderate and the relationship between job and housing is relatively balanced,it can effectively promote the balanced usage of dockless shared bikes while maintaining high riding flow.The spatio-temporal patterns can identify the associated problems such as imbalance or lack of users,which could be mitigated by corresponding solutions.The relative importance and nonlinear effects help planners prioritize strategies and identify effective ranges on different patterns to promote the usage and efficiency of the bike-sharing system.
文摘If you have been in Beijing for any length of time, you will have come to realize that there are several modes of transportation available to commuters, all ofthem relatively in expensive, especially
文摘As time goes by,shared bikes have become an essential element in people's life.However,due to the limited number and uneven distribution of shared bikes,it has brought some troubles to people's daily travel.In this paper,we establish an empty vehicle scheduling model with normal distribution and study the empty vehicle scheduling problem of shared bikes.This paper establishes a model based on real life,assumes different scheduling schemes,and compares different assumptions,so as to get better empty vehicle scheduling schemes.In this way,shared bikes will be more conducive to People's Daily travel and bring more convenience to people.
基金supported by the National Natural Science Foundation of China(G.Nos.71961025 and 71910107002)Natural Science Foundation of the Inner Mongolia Autonomous Region(G.No.2019MS07020)Young Talents of Science and Technology in the Universities of the Inner Mongolia Autonomous Region(G.No.NJYT-20-B08).
文摘Existing research models can neither indicate the availability of shared bikes nor detect unusable ones owing to a lack of information on bike maintenance and failure.To improve awareness regarding the availability of shared bikes,we propose an innovative approach for detecting unusable shared bikes based on reinforcement learning and the PageRank algorithm.The proposed method identifies unusable shared bikes depending on the local travel data and provides a ranking of the shared bikes according to their availability levels.Given a sliding time window,the value function for the reinforcement learning model was determined by considering the cumulative number of unavailable shared bikes,the proportion of rental cancelations at the same stations,and the mean time between the cancelations.Reinforcement learning was then used to identify shared bikes with the worst availability.An availability ranking for the shared bikes below the reward threshold was performed using the PageRank algorithm.The proposed detection approach was applied to a trip dataset of a real-world bike-sharing system to illustrate the modeling process and its effectiveness.The detection results of unusable shared bikes in the absence of failure and feedback data can provide essential information to support the maintenance management decisions regarding shared bikes.
基金support from C2SMART University Transportation Center(USDOT#69A3551747124).
文摘The e-commerce industry has experienced significant growth in the past decade,particu-larly post-COVID.To accommodate such growth,the parcel delivery sector has also grown rapidly.However,there is a lack of study that properly evaluates its social and environ-mental impacts at a large scale.A model is proposed to analyze such impacts.A parcel gen-eration process is presented to convert public data into parcel volumes and stops.A continuous approximation model is fitted to estimate the length of parcel service tours.A case study is conducted using New York City(NYC)data.The parcel generation is shown to be a valid fit.The continuous approximation model parameters have R2 values of 98%or higher.The model output is validated against UPS truck trips.Application of the model to 2021 suggests residential parcel deliveries contributed to 0.05%of total daily vehicle-kilometer-traveled(VKT)in NYC corresponding to 14.4 metric tons of carbon equivalent(MTCE)emissions per day.COVID-19 contributed to an increase in parcel deliveries that led to up to 1064.3 MTCE of annual greenhouse gas(GHG)emissions in NYC(which could power 532 standard US households for a year).The existing bike lane infrastructure can support the substitution of 17%of parcel deliveries by cargo bikes,which would reduce VKT by 11%.Adding 3 km of bike lanes to connect Amazon facilities can expand their cargo bike substitution benefit from a VKT reduction of 5%up to 30%.If 28 km of additional bike lanes are made,parcel delivery substitution citywide could increase from 17%to 34%via cargo bike and save an additional 2.3 MTCE per day.Cargo bike priorities can be set to reduce GHG emissions for lower-income neighborhoods including Harlem,Sunset Park,and Bushwick.
文摘Shijiazhuang,the capital of Hebei,is a reallyhappy city.It is often called the city of well-beingin China.The city has a nice living environment.Thereare lots of beautiful parks where people can walk,exercise,or just relax on weekends.The air isgetting cleaner,and the streets are cleaner,too.Transportation in Shijiazhuang is very convenient.Subways,buses,and shared bikes can take youeverywhere.Shijiazhuang also has a rich culture.
文摘On the morning of 23 December 2024,the Panda Pack and Bike Donation Ceremony in Cambodia under the Action Plan on Silk Road People-to-People Connectivity was held at Balaing Khang Lech Primary School in Kampong Thom Province.Over 150 participants including Kemreat Viseth,Deputy Director of the Council of Ministers of Cambodia and President of Civil Society Alliance Forum(CSAF),Nhek Ban Kheng,Deputy Governor of Kampong Thom Province.
基金funded by Beijing Institute of Electronic Science and Technology Postgraduate Excellence Demonstration Course Project(20230002Z0452).
文摘Among the four candidate algorithms in the fourth round of NIST standardization,the BIKE(Bit Flipping Key Encapsulation)scheme has a small key size and high efficiency,showing good prospects for application.However,the BIKE scheme based on QC-MDPC(Quasi Cyclic Medium Density Parity Check)codes still faces challenges such as the GJS attack and weak key attacks targeting the decoding failure rate(DFR).This paper analyzes the BGF decoding algorithm of the BIKE scheme,revealing two deep factors that lead to DFR,and proposes a weak key optimization attack method for the BGF decoding algorithm based on these two factors.The proposed method constructs a new weak key set,and experiment results eventually indicate that,considering BIKE’s parameter set targeting 128-bit security,the average decryption failure rate is lowerly bounded by.This result not only highlights a significant vulnerability in the BIKE scheme but also provides valuable insights for future improvements in its design.By addressing these weaknesses,the robustness of QC-MDPC code-based cryptographic systems can be enhanced,paving the way for more secure post-quantum cryptographic solutions.
文摘As the economy and technology keep growing,the mode of shared bikes gains popularity under these circumstances.At the current period,university students become fond of using shared bikes,which changes body health and life style of university students.When this mode combines the characteristics and functions of shared bikes,it has a great impact on the awareness and motivation of work-out of university students.Supported by Internet technology,shared bikes meet the need of people that they can use them at any time,which is new and innovative to the university students.This article provides university students with shared bike service in campus by analyzing the influence of“Internet+shared bike”on health and sports of university students.It will promote the effective application of shared bikes.
文摘Mobility is among the urban issues that most affect the population’s quality of life.The complexity inherent to mobility requires the development and application of methods and tools that enable a better understanding of their interrelationships.In this sense,the use of indicators is important for the analysis of current mobility conditions,as well as allowing the monitoring of the impact of public policies and the evolution of certain phenomena and actions.Thus,the objective is to study the cycling modal in urban mobility in the city of Vitória,Espírito Santo,during the period of the new coronavirus pandemic,through the application of two indicators:the cycling network increase and the traffic accident reduction.It is considered that the demand for the use of public transport and motor vehicles has decreased due to social isolation.The methodology includes a literature review on the studied subject;urban mobility indicators selection;data collection from public agencies;and analysis of the results.The results reveal that indicators are required to support the proposition of public policies,targeting of actions,identification of areas in need of investments and mainly can reflect the pandemic influence on urban mobility.
基金The National Key R&D Program of China(No.2018YFB1600900)the Project of International Cooperation and Exchange of the National Natural Science Foundation of China(No.51561135003)the Key Project of National Natural Science Foundation of China(No.51338003)
文摘In order to study the spatiotemporal characteristics of the dockless bike sharing system(BSS)around urban rail transit stations,new normalized calculation methods are proposed to explore the temporal and spatial usage patterns of the dockless BSS around rail transit stations by using 5-weekday dockless bike sharing trip data in Nanjing,China.First,the rail transit station area(RTSA)is defined by extracting shared bike trips with trip ends falling into the area.Then,the temporal and spatial decomposition methods are developed and two criterions are calculated,namely,normalized dynamic variation of bikes(NDVB)and normalized spatial distribution of trips(NSDT).Furthermore,the temporal and spatial usage patterns are clustered and the corresponding geographical distributions of shared bikes are determined.The results show that four temporal usage patterns and two spatial patterns of dockless BSS are finally identified.Area type(urban center and suburb)has a great influence on temporal usage patterns.Spatial usage patterns are irregular and affected by limited directions,adjacent rail transit stations and street networks.The findings can help form a better understanding of dockless shared bike users behavior around rail transit stations,which will contribute to improving the service and efficiency of both rail transit and BSS.
基金supported by Social Science Fund for Young Scholar of Ministry of Education of China(Grant No. 12YJC760092)Changzhou Key Digital Manufacturing Technology Laboratory Foundation of China(Grant No. CM2007301)
文摘As children mature, bike products for children in the market develop at the same time, and the conditions are frequently updated. Certain problems occur when using a bike, such as cycle overlapping, repeating function, and short life cycle, which go against the principles of energy conservation and the environmental protection intensive design concept. In this paper, a rational multi-function method of design through functional superposition, transformation, and technical implementation is proposed. An organic combination of frog-style scooter and children’s tricycle is developed using the multi-function method. From the ergonomic perspective, the paper elaborates on the body size of children aged 5 to 12 and effectively extracts data for a multi-function children’s bike, which can be used for gliding and riding. By inverting the body, parts can be interchanged between the handles and the pedals of the bike. Finally, the paper provides a detailed analysis of the components and structural design, body material, and processing technology of the bike. The study of Industrial Product Innovation Design provides an effective design method to solve the bicycle problems, extends the function problems, improves the product market situation, and enhances the energy saving feature while implementing intensive product development effectively at the same time.
基金supported by Tianjin Municipal Science and Technology Development Project of China (Grant No. 043186211)Tianjin Municipal Key Laboratory of Advanced Manufacturing Technology and Equipment of Tianjin University of China
文摘This paper investigates the dynamic design methodology of mountain bikes with rear suspension. Firstly, a multi-rigid body dynamic model of rider and mountain bike coupled system is constructed. The rider model includes 19 skeletons, 18 joints and 118 main muscles. Secondly, to validate the feasibility of the model, an experiment test is designed to reflect the real cycling status. Finally, aiming at enhancing the performance of the rider vibration comfort, the scale parameters of rear suspension are optimized with computer simulation and uniform design. The mathematical model in the vibration performance and the design variables is constructed with regression analysis. The result shows that when the length of side link is 90 mm, the length of connected rod is 336.115 1 mm and the included angle between absorber and side link is 60°, the mountain bike has better vibration comfort. This study and relevant conclusions are of practical importance to the design of the mountain bike＇s rear suspension system.
文摘Life-cycle assessment (LCA) is environmental evaluation of products, materials, and processes over their life cycle. Truncation uncertainty and corresponding uncertainty are main problems occurred in process life cycle assessment (PLCA) modeling and economic input-output life cycle assessment (EIOLCA) modeling. Through combination of these two modelings in different life cycle stage and use of an uncertainty reduction strategy, a hybrid life cycle assessment modeling method was proposed in this study. Case studies were presented on gasoline-powered motorbikes (M-bike) and electricity-powered electric bike (E-bike). Web-based software was developed to analyze process environmental impacts. Results show that the largest part of life cycle energy (LCE) is consumed at use stage. Less energy is consumed in life cycle of E-bike than that of M-bike. GWP (Global Warming Potential), CO (Carbon Monoxide), PM10 (particulate matter) emission of M-bike are higher than that of E-bike, especially at use stage, AP (acidification Potential) emission of E-bike is higher than that of M-bike. Comprehensively, E-bike is energy efficient and less emitting, and better choice for urban private transportation.
基金Supported by Special Found Project for Technology Innovation of Tianjin(Grant No.10FDZDGX00500)Tianjin Wu Qing Special Fund of Science and Technology,China
文摘Research on design of bicycles is concentrated on mechanism and auto appearance design, however few on matches between the bike and the rider. Since unreasonable human-bike relationship leads to both riders＇ worn-out joints and muscle injuries, the design of bicycles should focus on the matching. In order to find the best position of human-bike system, simulation experiments on riding comfort under different riding postures are done with the lifemode software employed to facilitate the cycling process as well as to obtain the best position and the size function of it. With BP neural network and GA, analyzing simulation data, conducting regression analysis of parameters on different heights and bike frames, the equation of best position of human-bike system is gained at last. In addition, after selecting testers, customized bikes based on testers＇ height dimensions are produced according to the size function. By analyzing and comparing the experimental data that are collected from testers when riding common bicycles and customized bicycles, it is concluded that customized bicycles are four times even six times as comfortable as common ones. The equation of best position of human-bike system is applied to improve bikes＇ function, and the new direction on future design of bicycle frame parameters is presented.
