While feeding her ostriches,Wang Xue swiftly responds to fans'questions with a sense of humor through her popular live‑streaming channel.Since Wang,30,an expert in ostrich farming,started live broadcasting on a sh...While feeding her ostriches,Wang Xue swiftly responds to fans'questions with a sense of humor through her popular live‑streaming channel.Since Wang,30,an expert in ostrich farming,started live broadcasting on a short‑video platform with her husband Han Peng,their ostrich farming business has flourished,garnering nearly 3 million fans on the platform.“The highest viewership for one single live broadcast reached over 6 million,”said Wang,adding that riding an ostrich at high speed was an essential part of her broadcasts.Through her videos,Wang brought fans close to the ostriches,providing details of their habits,farming methods and economic value.展开更多
On April 10,2025,the China International Exhibition Center(Shunyi Pavi l ion)became a symphony of roaring engines and dazzling digital light scapes as the 2025 Beijing International Motorcycle Expo kicked off.Under th...On April 10,2025,the China International Exhibition Center(Shunyi Pavi l ion)became a symphony of roaring engines and dazzling digital light scapes as the 2025 Beijing International Motorcycle Expo kicked off.Under the theme of“Promot ing Safe and Civilized Riding Awareness,Advancing the Orderly Development of Motorcycle Culture”,the event attracted over 150 global enterprises and nearly 200 brands.展开更多
1 A few decades ago,it was common to see groups of chil-dren riding bikes down quiet American streets.However,this scene is less likely to be seen today.In the 1990s,an average of 20.5 million children aged 7 to 17 ro...1 A few decades ago,it was common to see groups of chil-dren riding bikes down quiet American streets.However,this scene is less likely to be seen today.In the 1990s,an average of 20.5 million children aged 7 to 17 rode bikes six or more times a year,according to the National Sporting Goods Association.By 2023,this number had dropped to about 10.9 million,with less than 5%of them riding frequently.展开更多
An Italian scholar fulfills his potential in China,by being aligned with the country’s vibrant cultural development.“In August 2014,when I set my feet on the land of China,ride-hailing apps like Didi weren’t popula...An Italian scholar fulfills his potential in China,by being aligned with the country’s vibrant cultural development.“In August 2014,when I set my feet on the land of China,ride-hailing apps like Didi weren’t popular in Nanjing yet,and translation software was rarely seen.I didn’t speak Chinese,so even simple tasks like going out was challenging,”said Andrea L.Baldini,a Changjiang Scholar Distinguished Professor at Peking University’s School of Arts,in an exclusive interview with China Today.展开更多
The cooperative control of ride comfort and handling stability in automobile suspension systems presents a significant challenge in intelligent chassis system design.This complexity arises from the high degrees of fre...The cooperative control of ride comfort and handling stability in automobile suspension systems presents a significant challenge in intelligent chassis system design.This complexity arises from the high degrees of freedom,diverse operating conditions,and inherent trade-offs between performance metrics in full-car suspension systems.In this paper,a novel switching control strategy is proposed to better balance ride comfort and handling stability for a full-car suspension system.The system integrates a ride comfort controller and an anti-rollover controller,guided by a new rollover risk assessment indicator that requires fewer state variables.First,a vehicle suspension simplification model approach is introduced,reducing the fourteen-degree-of-freedom full-car suspension model to three two-degree-of-freedom models:vertical,pitch and roll.Based on these simplified models,vertical,roll,and pitch controllers are designed,simplifying the controller design process for full-car suspension systems.The ride comfort controller is constructed using the modal energy method in conjunction with the simplified model controllers,while the roll controller functions as the anti-rollover controller.The proposed rollover risk assessment indicator serves as the switching criterion between handling stability and ride comfort control.Experimental results demonstrate that the proposed switching control strategy effectively adapts to various road conditions,enabling the semi-active variable damping suspension system to perform multi-modal switching.Compared to a well-tuned passive suspension,vertical,roll,and pitch accelerations are reduced by 14.13%,13.02%and 13.08%,respectively,significantly improving ride comfort.Additionally,the system effectively mitigates rollover risk,achieving reductions in roll angle,roll speed,and roll acceleration by 19.69%,16.40%,and 29.96%,respectively,thereby greatly enhancing vehicle safety.Overall,the proposed switching control strategy achieves a successful balance between ride comfort and handling stability,enhancing overall driving performance.展开更多
Typically,seat or floor acceleration is used to evaluate the ride comfort of a high-speed train.However,the dynamic performance of the human body significantly differs from that of the floor.Therefore,using the car bo...Typically,seat or floor acceleration is used to evaluate the ride comfort of a high-speed train.However,the dynamic performance of the human body significantly differs from that of the floor.Therefore,using the car body floor and seat accelerations to calculate the ride comfort index of a high-speed train may not reflect the true feelings of passengers.In this study,a 3D human-seat-vehicle-track coupling model was established to investigate the ride comfort of highspeed train passengers.The seated human model,which considers the longitudinal,lateral,vertical,pitching,yawing,and rolling motions,comprises the head,upper torso,lower torso,pelvis,thighs,and shanks.The model parameters were determined using multi-axis excitation measurement data based on a genetic algorithm.Subsequently,the applicability of the small-angle assumption and natural modes of the human model is analyzed.Using the coupling system model,the vibration characteristics of the human-seat interaction surface were analyzed.The ride comfort of the high-speed train and human body dynamic performance were analyzed under normal conditions,track geometric irregularities and train meeting conditions.The results showed that the passenger seats in the front and rear rows adjacent to the window had a higher acceleration value than the others.The human backrest and seat pad connection points have higher vibration amplitudes than the car body floor in the human-sensitive frequency range,indicating that using the acceleration values on the floor may underestimate the discomfort of passengers.The ride comfort of high-speed trains diminishes in the presence of track geometric irregularities and when trains pass each other.When the excitation frequency of track geometry irregularities approached the natural frequency of the human-seat-vehicle system,ride comfort in high-speed trains decreased significantly.Moreover,using seat acceleration to evaluate passenger ride comfort overlooks the vibration characteristics of the human body.The transient aerodynamic force generated when the train meets can cause a larger car body roll and lateral motion at 2 Hz,which,in turn,decreases the passenger ride comfort.This study presents a detailed human-seat-vehicle-track coupling system that can reflect a passenger’s dynamic performance under complex operating conditions.展开更多
A kind of construction truck model is built in Adams based on multi-body dynamic theory. The rigid and elastic wheels of tire-soil contact models are proposed based on the Bekker pressure model and the Jonasi shear so...A kind of construction truck model is built in Adams based on multi-body dynamic theory. The rigid and elastic wheels of tire-soil contact models are proposed based on the Bekker pressure model and the Jonasi shear soil model, and they are described in the form of S-function to enhance the calculation efficiency and simulation accuracy. Finally, the interaction of truck and soil is simulated by Adams-Maflab co-simulation to study the influence of soft terrain on the ride comfort of vehicles. The co-simulation results reveal that the terrain properties have a great influence on the ride comfort of vehicles as well as driving speed, road roughness and cargo weight. This co-simulation model is convenient for adding the factor of terrain deformation to the analysis of vehicle ride comfort. It can also be used to optimize suspension system parameters especially for off-road vehicles.展开更多
Massive spatio-temporal big data about human mobility have become increasingly available.Revealing underlying dynamic patterns from these data is essential for understanding people’s behavior and urban deployment.Spa...Massive spatio-temporal big data about human mobility have become increasingly available.Revealing underlying dynamic patterns from these data is essential for understanding people’s behavior and urban deployment.Spatio-temporal autocorrelation analysis is an exploratory approach to recognizing data distribution in space and time.The most widely used spatial autocorrelation measurements,such as Moran’s I and local indicators of spatial association(LISA),only apply to static data,so are powerless to spatio-temporal big data about human mobility.Thus,we proposed a new method by extending Moran’s I to measure the spatial autocorrelation of time series data.Then the method was applied to taxi ride data in Beijing,China to reveal the spatial pattern of collective human mobility.The result shows that there is strong positive spatio-temporal autocorrelation within the 5th Ring Road,weak negative spatio-temporal autocorrelation nearby the Sixth Ring Road,and almost no spatiotemporal autocorrelation between the roads.Local spatial patterns of taxi travel were also recognized.This method is useful for discovering underlying patterns from spatio-temporal big data to understand human mobility.展开更多
A systematic and effective optimization is proposed for the design of a three-dimensional （3-D） vehicle suspension model with eight degrees of freedom （DOF）, including vertical seat motion, vehicle suspension, pit...A systematic and effective optimization is proposed for the design of a three-dimensional （3-D） vehicle suspension model with eight degrees of freedom （DOF）, including vertical seat motion, vehicle suspension, pitching and rolling motions, and vertical wheel motions using the evolutionary game theory. A new design of the passive suspension is aided by game theory to attain the best compromise between ride quality and suspension deflections. Extensive simulations are performed on three type road surface models A, B, C pavement grades based on the guidelines provided by ISO-2631 with the Matlab/Simulink environment. The preliminary results show that, when the passive suspension is optimized via the proposed approach, a substantial improvement in the vertical ride quality is obtained while keeping the suspension deflections within their allowable clearance when the vehicle moves at a constant velocity v=20 m/s, and the comfort performance of a suspension seat can be enhanced by 20%-30%.展开更多
The feasibility of providing the tank a limited anti helicopter ability with gun launched missile is studied. A type of simulation model of gun launched missile against attack helicopters is established. The simula...The feasibility of providing the tank a limited anti helicopter ability with gun launched missile is studied. A type of simulation model of gun launched missile against attack helicopters is established. The simulation and the parameter optimization of missile control system under various circumstances are done. The gun launched missile can directly hit the helicopters in the typical tracks, all the missdistances are less than 1?m and the maximum overload is less than available overload. Gun launched missile is a feasible choice for tanks against attack helicopters.展开更多
The optimum theory and methods were adopted to design the laser beam riding guidance anti tank missile's control system in the short run. Through building the mathematical model of system, selecting a proper meth...The optimum theory and methods were adopted to design the laser beam riding guidance anti tank missile's control system in the short run. Through building the mathematical model of system, selecting a proper method and taking advantage of computer's high speed calculation and logic traits, an optimal controller was designed. Simulation results showed that the designed control system has fair performance and it satisfies the tactical and technical requirements. The results also demonstrate that by the combination of the optimizing methods and the computer the control system could be designed as soon as possible.展开更多
文摘While feeding her ostriches,Wang Xue swiftly responds to fans'questions with a sense of humor through her popular live‑streaming channel.Since Wang,30,an expert in ostrich farming,started live broadcasting on a short‑video platform with her husband Han Peng,their ostrich farming business has flourished,garnering nearly 3 million fans on the platform.“The highest viewership for one single live broadcast reached over 6 million,”said Wang,adding that riding an ostrich at high speed was an essential part of her broadcasts.Through her videos,Wang brought fans close to the ostriches,providing details of their habits,farming methods and economic value.
文摘On April 10,2025,the China International Exhibition Center(Shunyi Pavi l ion)became a symphony of roaring engines and dazzling digital light scapes as the 2025 Beijing International Motorcycle Expo kicked off.Under the theme of“Promot ing Safe and Civilized Riding Awareness,Advancing the Orderly Development of Motorcycle Culture”,the event attracted over 150 global enterprises and nearly 200 brands.
文摘1 A few decades ago,it was common to see groups of chil-dren riding bikes down quiet American streets.However,this scene is less likely to be seen today.In the 1990s,an average of 20.5 million children aged 7 to 17 rode bikes six or more times a year,according to the National Sporting Goods Association.By 2023,this number had dropped to about 10.9 million,with less than 5%of them riding frequently.
文摘An Italian scholar fulfills his potential in China,by being aligned with the country’s vibrant cultural development.“In August 2014,when I set my feet on the land of China,ride-hailing apps like Didi weren’t popular in Nanjing yet,and translation software was rarely seen.I didn’t speak Chinese,so even simple tasks like going out was challenging,”said Andrea L.Baldini,a Changjiang Scholar Distinguished Professor at Peking University’s School of Arts,in an exclusive interview with China Today.
基金Supported by the Australian Research Council’s Discovery Project(Grant No.DP200100149)Taishan Scholars Program of Shandong Province(Grant No.tsqn202211062)Chinses Scholarship Council(Grant No.202006690005).
文摘The cooperative control of ride comfort and handling stability in automobile suspension systems presents a significant challenge in intelligent chassis system design.This complexity arises from the high degrees of freedom,diverse operating conditions,and inherent trade-offs between performance metrics in full-car suspension systems.In this paper,a novel switching control strategy is proposed to better balance ride comfort and handling stability for a full-car suspension system.The system integrates a ride comfort controller and an anti-rollover controller,guided by a new rollover risk assessment indicator that requires fewer state variables.First,a vehicle suspension simplification model approach is introduced,reducing the fourteen-degree-of-freedom full-car suspension model to three two-degree-of-freedom models:vertical,pitch and roll.Based on these simplified models,vertical,roll,and pitch controllers are designed,simplifying the controller design process for full-car suspension systems.The ride comfort controller is constructed using the modal energy method in conjunction with the simplified model controllers,while the roll controller functions as the anti-rollover controller.The proposed rollover risk assessment indicator serves as the switching criterion between handling stability and ride comfort control.Experimental results demonstrate that the proposed switching control strategy effectively adapts to various road conditions,enabling the semi-active variable damping suspension system to perform multi-modal switching.Compared to a well-tuned passive suspension,vertical,roll,and pitch accelerations are reduced by 14.13%,13.02%and 13.08%,respectively,significantly improving ride comfort.Additionally,the system effectively mitigates rollover risk,achieving reductions in roll angle,roll speed,and roll acceleration by 19.69%,16.40%,and 29.96%,respectively,thereby greatly enhancing vehicle safety.Overall,the proposed switching control strategy achieves a successful balance between ride comfort and handling stability,enhancing overall driving performance.
基金Supported by National Natural Science Foundation of China(Grant No.U1934203)Research and Development Project of Science and Technology of China Railway Corporation(Grant No.P2023T002)。
文摘Typically,seat or floor acceleration is used to evaluate the ride comfort of a high-speed train.However,the dynamic performance of the human body significantly differs from that of the floor.Therefore,using the car body floor and seat accelerations to calculate the ride comfort index of a high-speed train may not reflect the true feelings of passengers.In this study,a 3D human-seat-vehicle-track coupling model was established to investigate the ride comfort of highspeed train passengers.The seated human model,which considers the longitudinal,lateral,vertical,pitching,yawing,and rolling motions,comprises the head,upper torso,lower torso,pelvis,thighs,and shanks.The model parameters were determined using multi-axis excitation measurement data based on a genetic algorithm.Subsequently,the applicability of the small-angle assumption and natural modes of the human model is analyzed.Using the coupling system model,the vibration characteristics of the human-seat interaction surface were analyzed.The ride comfort of the high-speed train and human body dynamic performance were analyzed under normal conditions,track geometric irregularities and train meeting conditions.The results showed that the passenger seats in the front and rear rows adjacent to the window had a higher acceleration value than the others.The human backrest and seat pad connection points have higher vibration amplitudes than the car body floor in the human-sensitive frequency range,indicating that using the acceleration values on the floor may underestimate the discomfort of passengers.The ride comfort of high-speed trains diminishes in the presence of track geometric irregularities and when trains pass each other.When the excitation frequency of track geometry irregularities approached the natural frequency of the human-seat-vehicle system,ride comfort in high-speed trains decreased significantly.Moreover,using seat acceleration to evaluate passenger ride comfort overlooks the vibration characteristics of the human body.The transient aerodynamic force generated when the train meets can cause a larger car body roll and lateral motion at 2 Hz,which,in turn,decreases the passenger ride comfort.This study presents a detailed human-seat-vehicle-track coupling system that can reflect a passenger’s dynamic performance under complex operating conditions.
基金The National Natural Science Foundation of China(No.50575040)the Natural Science Foundation of Jiangsu Province(No.BK2007112)
文摘A kind of construction truck model is built in Adams based on multi-body dynamic theory. The rigid and elastic wheels of tire-soil contact models are proposed based on the Bekker pressure model and the Jonasi shear soil model, and they are described in the form of S-function to enhance the calculation efficiency and simulation accuracy. Finally, the interaction of truck and soil is simulated by Adams-Maflab co-simulation to study the influence of soft terrain on the ride comfort of vehicles. The co-simulation results reveal that the terrain properties have a great influence on the ride comfort of vehicles as well as driving speed, road roughness and cargo weight. This co-simulation model is convenient for adding the factor of terrain deformation to the analysis of vehicle ride comfort. It can also be used to optimize suspension system parameters especially for off-road vehicles.
基金This work is funded by the National Natural Science Foundation of China[grant numbers 41830645 and 41625003].
文摘Massive spatio-temporal big data about human mobility have become increasingly available.Revealing underlying dynamic patterns from these data is essential for understanding people’s behavior and urban deployment.Spatio-temporal autocorrelation analysis is an exploratory approach to recognizing data distribution in space and time.The most widely used spatial autocorrelation measurements,such as Moran’s I and local indicators of spatial association(LISA),only apply to static data,so are powerless to spatio-temporal big data about human mobility.Thus,we proposed a new method by extending Moran’s I to measure the spatial autocorrelation of time series data.Then the method was applied to taxi ride data in Beijing,China to reveal the spatial pattern of collective human mobility.The result shows that there is strong positive spatio-temporal autocorrelation within the 5th Ring Road,weak negative spatio-temporal autocorrelation nearby the Sixth Ring Road,and almost no spatiotemporal autocorrelation between the roads.Local spatial patterns of taxi travel were also recognized.This method is useful for discovering underlying patterns from spatio-temporal big data to understand human mobility.
基金Supported by Program for New Century Excellent Talents in University (070003)the Natural Science Foundation of Anhui Province (070414154)~~
文摘A systematic and effective optimization is proposed for the design of a three-dimensional （3-D） vehicle suspension model with eight degrees of freedom （DOF）, including vertical seat motion, vehicle suspension, pitching and rolling motions, and vertical wheel motions using the evolutionary game theory. A new design of the passive suspension is aided by game theory to attain the best compromise between ride quality and suspension deflections. Extensive simulations are performed on three type road surface models A, B, C pavement grades based on the guidelines provided by ISO-2631 with the Matlab/Simulink environment. The preliminary results show that, when the passive suspension is optimized via the proposed approach, a substantial improvement in the vertical ride quality is obtained while keeping the suspension deflections within their allowable clearance when the vehicle moves at a constant velocity v=20 m/s, and the comfort performance of a suspension seat can be enhanced by 20%-30%.
文摘The feasibility of providing the tank a limited anti helicopter ability with gun launched missile is studied. A type of simulation model of gun launched missile against attack helicopters is established. The simulation and the parameter optimization of missile control system under various circumstances are done. The gun launched missile can directly hit the helicopters in the typical tracks, all the missdistances are less than 1?m and the maximum overload is less than available overload. Gun launched missile is a feasible choice for tanks against attack helicopters.
文摘The optimum theory and methods were adopted to design the laser beam riding guidance anti tank missile's control system in the short run. Through building the mathematical model of system, selecting a proper method and taking advantage of computer's high speed calculation and logic traits, an optimal controller was designed. Simulation results showed that the designed control system has fair performance and it satisfies the tactical and technical requirements. The results also demonstrate that by the combination of the optimizing methods and the computer the control system could be designed as soon as possible.
