A visual object-oriented software for lane following on intelligent highway system (IHS) is proposed. According to object-oriented theory, 3 typical user services of self-check, transfer of human driving and automatic...A visual object-oriented software for lane following on intelligent highway system (IHS) is proposed. According to object-oriented theory, 3 typical user services of self-check, transfer of human driving and automatic running and abnormal information input from the sensors are chosen out. In addition, the functions of real-time display, information exchanging interface, determination and operation interweaving in the 3 user services are separated into 5 object-oriented classes. Moreover, the 5 classes are organized in the visual development environment. At last, experimental result proves the validity and reliability of the control application.展开更多
To resolve the path tracking problem of autonomous ground vehicles,an analysis of existing path tracking methods was carried out and an important conclusion was got.The vehicle-road model is crucial for path following...To resolve the path tracking problem of autonomous ground vehicles,an analysis of existing path tracking methods was carried out and an important conclusion was got.The vehicle-road model is crucial for path following.Based on the conclusion,a new vehicle-road model named "ribbon model" was constructed with consideration of road width and vehicle geometry structure.A new vehicle-road evaluation algorithm was proposed based on this model,and a new path tracking controller including a steering controller and a speed controller was designed.The difficulties of preview distance selection and parameters tuning with speed in the pure following controller are avoided in this controller.To verify the performance of the novel method,simulation and real vehicle experiments were carried out.Experimental results show that the path tracking controller can keep the vehicle in the road running as fast as possible,so it can adjust the control strategy,such as safety,amenity,and rapidity criteria autonomously according to the road situation.This is important for the controller to adapt to different kinds of environments,and can improve the performance of autonomous ground vehicles significantly.展开更多
Traffic jam in large signalized road network presents a complex nature.In order to reveal the jam characteristics,two indexes,SVS(speed of virtual signal) and VOS(velocity of spillover),were proposed respectively.SVS ...Traffic jam in large signalized road network presents a complex nature.In order to reveal the jam characteristics,two indexes,SVS(speed of virtual signal) and VOS(velocity of spillover),were proposed respectively.SVS described the propagation of queue within a link while VOS reflected the spillover velocity of vehicle queue.Based on the two indexes,network jam simulation was carried out on a regular signalized road network.The simulation results show that:1) The propagation of traffic congestion on a signalized road network can be classified into two stages:virtual split driven stage and flow rate driven stage.The former stage is characterized by decreasing virtual split while the latter only depends on flow rate; 2) The jam propagation rate and direction are dependent on traffic demand distribution and other network parameters.The direction with higher demand gets more chance to be jammed.Our findings can serve as the basis of the prevention of the formation and propagation of network traffic jam.展开更多
In snow-icy road environment, the survey data indicate that the largest decrease in traffic flow running characters occurs when snow and ice begin to accumulate on the road surface. Saturation flow is decreased by 16%...In snow-icy road environment, the survey data indicate that the largest decrease in traffic flow running characters occurs when snow and ice begin to accumulate on the road surface. Saturation flow is decreased by 16% , speed is decreased by 30% , and start-up lost time is increased by 27%. Based on the signal control theory of HCM and Webster, the character values of traffic flow in different urban road environments were investigated, and the evolvement regularity of signal control parameters such as cycle, split, green time, offset, yellow time and red time in snow-icy road environment was analyzed. The impact factors and the changes in the scope of signal control parameters were achieved. Simulation results and practical application show that the signal control plan of road enviromnent without snow and ice will increase the vehicle delay, stop length and traffic congestion in snow-icy road environment. Thus, the traffic signal control system should address a suitable signal control plan based on different road environments.展开更多
The turning motion of a tracked pipeline-robot implemented by skid steering is a nonholonomic dynamic problem with intrinsic nonlinearity, to which the classical control method is inappropriate and cannot be applied. ...The turning motion of a tracked pipeline-robot implemented by skid steering is a nonholonomic dynamic problem with intrinsic nonlinearity, to which the classical control method is inappropriate and cannot be applied. This paper presents a novel path tracking control method based on hierarchical fuzzy structure. The controller consists of three sub-level low dimensional fuzzy control systems: fuzzy supervisory control, fuzzy steering and fuzzy velocity control. As a result, establishing the bases of rules for the fuzzy control becomes feasible and simplified, and the related controller can be adapted to complicated ground and environment. Using this method, the number of fuzzy controt rules is greatly decreased so that the curse of dimensionality causing the multivariable problem does not occur. Simulation and experimental results validate the effectiveness of the proposed method with satisfied performance on path tracking. Autonomous navigation of the caterpillar-inspired pipeline-robot is also implemented based on the sensor feedbacks.展开更多
Geographic routing has been introduced in mobile ad hoc networks and sensor networks. But its per-formance suffers greatly from mobility-induced location errors that can cause Lost Link (LLNK) and LOOP problems. Thu...Geographic routing has been introduced in mobile ad hoc networks and sensor networks. But its per-formance suffers greatly from mobility-induced location errors that can cause Lost Link (LLNK) and LOOP problems. Thus various mobility prediction algorithms have been proposed to mitigate the errors, but sometimes their prediction errors are substantial. A novel mobility prediction technique that incorpo-rates both mobile positioning information and road topology knowledge was presented. Furthermore, the performance of the scheme was evaluated via simulations, along with two other schemes, namely, Linear Velocity Prediction (LVP) and Weighted Velocity Prediction (WVP) for comparison purpose. The results of simulation under Manhattan mobility model show that the proposed scheme could track the movement of a node well and hence provide noticeable improvement over LVP and MVP.展开更多
Device-to-Device(D2D) communication has been proposed to facilitate cellular network with system capacity(SC) and quality of service(QoS).We consider the design of link assignment(LA),channel allocation(CA)and power c...Device-to-Device(D2D) communication has been proposed to facilitate cellular network with system capacity(SC) and quality of service(QoS).We consider the design of link assignment(LA),channel allocation(CA)and power control(PC) in D2D-aided content delivery scenario for both user fairness(UF)and system throughput(ST) under QoS requirement.Due to the complexity of the problem,we decompose it into two components:CA is formulated from graph perspective to mitigate severe co-channel interference,which turns out to be the Max K-cut problem;LA and PC are jointly optimized to utilize the gain achieved from CA for supreme performance,and specifically,genetic algorithm(GA) is adopted to optimize LA,but when deriving the fitness of each chromosome,PC optimization will be involved.Thanks to numerical results,we elucidate the efficacy of our scheme.展开更多
A method of ascertaining grade length limitation of freeways in mountain terrain is presented. The relationship models between 15 th percentile speeds and grades were built through the surveys and analyses of operatio...A method of ascertaining grade length limitation of freeways in mountain terrain is presented. The relationship models between 15 th percentile speeds and grades were built through the surveys and analyses of operation speeds on 7 typical sections of 3 freeways in mountain terrain. Using 15 thpercentile and 85 th percentile as speed limitations, the methods of determining admitted velocities were put forward according to the grades. Deceleration distances of longitudinal slopeways were analyzed utilizing the theories of vehicle. According to the results of analysis, grade length limitation was loosed. Finally the values of grade length limitation for freeways were put forward. The results could be used as references for freeway design.展开更多
Now the surface settlement induced by shallow buried tunnel to under-traverse highway,mostly adopt the empirical value,3 cm,acquired from Beijing or Shenzhen metro,which is regarded as the controlling standard.But to ...Now the surface settlement induced by shallow buried tunnel to under-traverse highway,mostly adopt the empirical value,3 cm,acquired from Beijing or Shenzhen metro,which is regarded as the controlling standard.But to more project,tunnel under-traverse highway,we must decide the controlling standard flexibly,which should base on the pavement service function and the pavement condition.The thesis,based on the pavement evenness and running comfort ability in the view of completing the pavement service function,supposes the longitudinal pavement settlement cross section as a quadratic parabola,and gets the maximal settlement value in the range of longitudinal pavement influence when the tunnel is under-traverse highway perpendicularly.Then the controlling standard is decided.As Wenxiang Tunnel under-traverse Lianhuo Freeway on Zhengzhou-Xi'an Passenger Dedicated Railway Line for an example,the settlement controlling standard is acquired,and we hope it has an direction and reference value to similar tunnel construction.展开更多
This work proposes a map-based control method to improve a vehicle's lateral stability, and the performance of the proposed method is compared with that of the conventional model-referenced control method. Model-r...This work proposes a map-based control method to improve a vehicle's lateral stability, and the performance of the proposed method is compared with that of the conventional model-referenced control method. Model-referenced control uses the sliding mode method to determine the compensated yaw moment; in contrast, the proposed map-based control uses the compensated yaw moment map acquired by vehicle stability analysis. The vehicle stability region is calculated by a topological method based on the trajectory reversal method. A 2-DOF vehicle model and Pacejka's tire model are used to evaluate the proposed map-based control method. The properties of model-referenced control and map-based control are compared under various road conditions and driving inputs. Model-referenced control uses a control input to satisfy the linear reference model, and it generates unnecessary tire lateral forces that may lead to worse performance than an uncontrolled vehicle with step steering input on a road with a low friction coefficient. However, map-based control determines a compensated yaw moment to maintain the vehicle within the stability region,so the typical responses of vehicle enable to converge rapidly. The simulation results with sine and step steering show that map-based control provides better the tracking responsibility and control performance than model-referenced control.展开更多
With the advantages of long lifetime, high lighting effect and non-pollution, LED lighting has taken a leading role in the lighting sector. LED street and tunnel lights have no unified product interface, so the produc...With the advantages of long lifetime, high lighting effect and non-pollution, LED lighting has taken a leading role in the lighting sector. LED street and tunnel lights have no unified product interface, so the products of different enterprises cannot interchange with each other, restraining the development of the whole industry due to the large-scale production problem. The alliance standard CSA 016-2013 has been approved as a national standard project, paving the way for the orderly development of LED industry. Interpreting the CSA 016 standard, the paper expounds on the technical requirements for interchangeable interface in the optical, mechanical, electrical and thermal aspects.展开更多
The adopted 2-D SSD (stopping sight distance) adequacy investigation in current design practice may lead to design deficiencies due to inaccurate calculation of the available sight distance. Although this concern ha...The adopted 2-D SSD (stopping sight distance) adequacy investigation in current design practice may lead to design deficiencies due to inaccurate calculation of the available sight distance. Although this concern has been identified by many research studies in the past, none of them suggested a comprehensive methodology to simulate from a 3-D perspective concurrently both the cross-section design and the vehicle dynamics in space during emergency braking conditions. The proposed methodology can accurately perform SSD adequacy investigation in any 3-D road environment where the ground, road and roadside elements are inserted by identifying areas of interrupted vision lines between driver and obstacle being less than the required distance necessary to bring the vehicle to a stop condition. The present approach provides flexibility among every road design and/or vehicle dynamic parameter inserted, as well as direct overview regarding design elements that restrict the driver's vision and create SSD inadequacies. As a result, precious guidance is provided to the designer for further alignment improvement but mostly an accurate aid to implement geometric design control criteria with respect to both existing as well as new road sections is delivered. The efficiency of the suggested methodology is demonstrated through a case study.展开更多
As two kinds of management modes of highway tramc control, lane-control, and speed-control produce different effect under different conditions. In this paper, traffic flow cellular automaton models for four-lane highw...As two kinds of management modes of highway tramc control, lane-control, and speed-control produce different effect under different conditions. In this paper, traffic flow cellular automaton models for four-lane highway system with two opposing directions under the above two modes are established considering car and truck mixed running. Through computer numerical simulating, the fundamental diagrams with different parameters are obtained, and after the analysis of density-flux diagrams, the variation discipline of flux with traffic density under different control models is gained. The results indicate that, compared with lane-control, utilization ratio of road can be further improved with speed-control when the truck number increases. The research result is of great significance for reasonable providing theoretical guidance for highway traffic control.展开更多
This paper proposes a circuit structure which can be used for both synchronous and asynchronous pipeline control. It is a self-circulation structure with embedded delay network, and a pipeline can be controlled by thi...This paper proposes a circuit structure which can be used for both synchronous and asynchronous pipeline control. It is a self-circulation structure with embedded delay network, and a pipeline can be controlled by this structure with the interconnection of adjacent stages. This paper first proposes a basic circuit structure, then a linear pipeline is designed with self-circulation structure. The performance of linear pipeline is analyzed, and a 16-bit digital signal processor (DSP) with the structure is designed to prove the validity of the structure. Results show that about 10%-15% power consumption is saved with self-circulation structure compared with synchronous counterpart, while almost the same performance is achieved.展开更多
When a four in-wheel motors drive electric vehicle with a specific wheels mass is running on an uneven road and transient steering occurs in the meantime, the joint action of the large unsprung dynamic load and the ce...When a four in-wheel motors drive electric vehicle with a specific wheels mass is running on an uneven road and transient steering occurs in the meantime, the joint action of the large unsprung dynamic load and the centrifugal force may cause the vehicle to rollover. To avoid the above accident, a rollover prevention control method based on active distribution of the in-wheel motors driving torques is investigated. First, tile rollover evolution process of the four in-wheel motors drive electric vehicle under the described operating condition is analyzed. Next, a multiple degrees of freedom vehicle dynamics model including an uneven road tyre model is established, and the rollover warning threshold is determined according to the load transfer ratio. Then, the hypothesis of the effects of unsprung mass on the vehicle roll stability on a plat road and on an uneven road is verified respectively. Finally, a rollover prevention controller is designed based on the distribution of the four wheels driving torques with sliding mode control, and the control effect is verified by simulations. The conclusion shows that, once the wheels mass does not match road conditions, the large unsprung mass may play a detrimental role on the vehicle roll stability on an uneven road, which is different from the beneficial role of large unsprung mass on the vehicle roll stability on a plat road. With the aforementioned rollover prevention controller, the vehicle rollover, which is caused by the coupling effect between large unsprung dynamic load and suspension potential energy on an uneven road, can be avoided effectively.展开更多
The Chinese road has deep historical roots. Its most striking feature is that it is marked by historical continuity rather than rupture, and the main force behind this continuity is its intrinsic dynamism and vitality...The Chinese road has deep historical roots. Its most striking feature is that it is marked by historical continuity rather than rupture, and the main force behind this continuity is its intrinsic dynamism and vitality. Unlike the paradigm of Eurocentrism or "Discovering History in China," the comparative analytical paradigm discovers China through long-term comparisons with corresponding countries in the same time and space in an effort to find positive elements in the history of the Chinese road and to refute the long prevalent theory of Chinese stagnation. Seen over the course of world history, the impetus for the creation of the world's most brilliant agrarian civilization was endogenous. This impetus was not a momentary "explosive force" but a sustainable institutional drive whose main constituents were the independent farming household, endogenous government capacity and adaptive national governance. In addition to the main theme of "permanent change," Chinese development had a secondary theme of "cyclical change" which cannot be ignored. The roots of Chinese development are buried deep in the genes of this agrarian nation in the form of sticky institutions, bureaucratic inertia, arbitrary power, etc. Historical continuity provided a foundation for China's creative revolution and development in modern times, ultimately laying down a socialist development road with Chinese characteristics, although this remains an unfinished relay process.展开更多
Inferior dislocation of the hip is the rarest type in hip dislocation. Very few cases have been reported in the anglophonic literature, most of which involved the pediatric age group. Surprisingly, we came across a 30...Inferior dislocation of the hip is the rarest type in hip dislocation. Very few cases have been reported in the anglophonic literature, most of which involved the pediatric age group. Surprisingly, we came across a 30- year-old patient with a bilateral inferior hip dislocation. He had sustained a road traffic accident and the attitude of both hip joints was flexion and abduction. The diagnosis was confirmed by radiographs which revealed the long axis of the femur at an angle of 1 l0 (right) degrees and 100 (left)degrees respectively away from the axis. Closed reduction under sedation was successfully performed. Skin traction for a period of 6 weeks was advised and the follow-up revealed an excellent result. We present the details of this case, the first of its kind along with a review of the literature, discussing the various modes and mechanisms of injury inducing inferior dislocation of the hip.展开更多
Hoffa's fracture is an uncommon fracture of the femoral condyle with coronal orientation of the fracture line. The mechanism of injury in pediatric Hoffa's fracture is road traffic accident, sports injury, and trivi...Hoffa's fracture is an uncommon fracture of the femoral condyle with coronal orientation of the fracture line. The mechanism of injury in pediatric Hoffa's fracture is road traffic accident, sports injury, and trivial injury. Clinical examination and proper imaging is important for diagnosis of pediatric Hoffa's fracture because of high chances of missing these injuries which can lead to nonunion and malunion at the fracture site. Open reduction and anatomical reduction of intraarticular fragment is the gold standard treatment of these fractures. We present a rare case of Hoffa's fracture in a 16-year-old girl with asso- ciated ipsilateral fibular fracture.展开更多
文摘A visual object-oriented software for lane following on intelligent highway system (IHS) is proposed. According to object-oriented theory, 3 typical user services of self-check, transfer of human driving and automatic running and abnormal information input from the sensors are chosen out. In addition, the functions of real-time display, information exchanging interface, determination and operation interweaving in the 3 user services are separated into 5 object-oriented classes. Moreover, the 5 classes are organized in the visual development environment. At last, experimental result proves the validity and reliability of the control application.
基金Project(90820302)supported by the National Natural Science Foundation of China
文摘To resolve the path tracking problem of autonomous ground vehicles,an analysis of existing path tracking methods was carried out and an important conclusion was got.The vehicle-road model is crucial for path following.Based on the conclusion,a new vehicle-road model named "ribbon model" was constructed with consideration of road width and vehicle geometry structure.A new vehicle-road evaluation algorithm was proposed based on this model,and a new path tracking controller including a steering controller and a speed controller was designed.The difficulties of preview distance selection and parameters tuning with speed in the pure following controller are avoided in this controller.To verify the performance of the novel method,simulation and real vehicle experiments were carried out.Experimental results show that the path tracking controller can keep the vehicle in the road running as fast as possible,so it can adjust the control strategy,such as safety,amenity,and rapidity criteria autonomously according to the road situation.This is important for the controller to adapt to different kinds of environments,and can improve the performance of autonomous ground vehicles significantly.
基金Project(2012CB725402)supported by the State Key Development Program for Basic Research of ChinaProject(2012MS21175)supported by the National Science Foundation for Post-doctoral Scientists of ChinaProject(Bsh1202056)supported by the Excellent Postdoctoral Science Foundation of Zhejiang Province,China
文摘Traffic jam in large signalized road network presents a complex nature.In order to reveal the jam characteristics,two indexes,SVS(speed of virtual signal) and VOS(velocity of spillover),were proposed respectively.SVS described the propagation of queue within a link while VOS reflected the spillover velocity of vehicle queue.Based on the two indexes,network jam simulation was carried out on a regular signalized road network.The simulation results show that:1) The propagation of traffic congestion on a signalized road network can be classified into two stages:virtual split driven stage and flow rate driven stage.The former stage is characterized by decreasing virtual split while the latter only depends on flow rate; 2) The jam propagation rate and direction are dependent on traffic demand distribution and other network parameters.The direction with higher demand gets more chance to be jammed.Our findings can serve as the basis of the prevention of the formation and propagation of network traffic jam.
基金Sponsored by the National Basic Research and Development Program of China(Grant No.2006CB705505) Research Fund for the Doctoral Program of Higher Education of China(Grant No.200802131012)
文摘In snow-icy road environment, the survey data indicate that the largest decrease in traffic flow running characters occurs when snow and ice begin to accumulate on the road surface. Saturation flow is decreased by 16% , speed is decreased by 30% , and start-up lost time is increased by 27%. Based on the signal control theory of HCM and Webster, the character values of traffic flow in different urban road environments were investigated, and the evolvement regularity of signal control parameters such as cycle, split, green time, offset, yellow time and red time in snow-icy road environment was analyzed. The impact factors and the changes in the scope of signal control parameters were achieved. Simulation results and practical application show that the signal control plan of road enviromnent without snow and ice will increase the vehicle delay, stop length and traffic congestion in snow-icy road environment. Thus, the traffic signal control system should address a suitable signal control plan based on different road environments.
基金Supported by the National Science Foundation of China ( No. 60935001 ) and New Century Excellent Talents in University of Chinese Ministry of Education (NCET-06-0398).
文摘The turning motion of a tracked pipeline-robot implemented by skid steering is a nonholonomic dynamic problem with intrinsic nonlinearity, to which the classical control method is inappropriate and cannot be applied. This paper presents a novel path tracking control method based on hierarchical fuzzy structure. The controller consists of three sub-level low dimensional fuzzy control systems: fuzzy supervisory control, fuzzy steering and fuzzy velocity control. As a result, establishing the bases of rules for the fuzzy control becomes feasible and simplified, and the related controller can be adapted to complicated ground and environment. Using this method, the number of fuzzy controt rules is greatly decreased so that the curse of dimensionality causing the multivariable problem does not occur. Simulation and experimental results validate the effectiveness of the proposed method with satisfied performance on path tracking. Autonomous navigation of the caterpillar-inspired pipeline-robot is also implemented based on the sensor feedbacks.
文摘Geographic routing has been introduced in mobile ad hoc networks and sensor networks. But its per-formance suffers greatly from mobility-induced location errors that can cause Lost Link (LLNK) and LOOP problems. Thus various mobility prediction algorithms have been proposed to mitigate the errors, but sometimes their prediction errors are substantial. A novel mobility prediction technique that incorpo-rates both mobile positioning information and road topology knowledge was presented. Furthermore, the performance of the scheme was evaluated via simulations, along with two other schemes, namely, Linear Velocity Prediction (LVP) and Weighted Velocity Prediction (WVP) for comparison purpose. The results of simulation under Manhattan mobility model show that the proposed scheme could track the movement of a node well and hence provide noticeable improvement over LVP and MVP.
基金supported by the National 863 projects of China(2014AA01A706)
文摘Device-to-Device(D2D) communication has been proposed to facilitate cellular network with system capacity(SC) and quality of service(QoS).We consider the design of link assignment(LA),channel allocation(CA)and power control(PC) in D2D-aided content delivery scenario for both user fairness(UF)and system throughput(ST) under QoS requirement.Due to the complexity of the problem,we decompose it into two components:CA is formulated from graph perspective to mitigate severe co-channel interference,which turns out to be the Max K-cut problem;LA and PC are jointly optimized to utilize the gain achieved from CA for supreme performance,and specifically,genetic algorithm(GA) is adopted to optimize LA,but when deriving the fitness of each chromosome,PC optimization will be involved.Thanks to numerical results,we elucidate the efficacy of our scheme.
基金Sponsored by the Specialized Research Fund for the Doctoral Program of High Education(Grant No.20030213030)
文摘A method of ascertaining grade length limitation of freeways in mountain terrain is presented. The relationship models between 15 th percentile speeds and grades were built through the surveys and analyses of operation speeds on 7 typical sections of 3 freeways in mountain terrain. Using 15 thpercentile and 85 th percentile as speed limitations, the methods of determining admitted velocities were put forward according to the grades. Deceleration distances of longitudinal slopeways were analyzed utilizing the theories of vehicle. According to the results of analysis, grade length limitation was loosed. Finally the values of grade length limitation for freeways were put forward. The results could be used as references for freeway design.
文摘Now the surface settlement induced by shallow buried tunnel to under-traverse highway,mostly adopt the empirical value,3 cm,acquired from Beijing or Shenzhen metro,which is regarded as the controlling standard.But to more project,tunnel under-traverse highway,we must decide the controlling standard flexibly,which should base on the pavement service function and the pavement condition.The thesis,based on the pavement evenness and running comfort ability in the view of completing the pavement service function,supposes the longitudinal pavement settlement cross section as a quadratic parabola,and gets the maximal settlement value in the range of longitudinal pavement influence when the tunnel is under-traverse highway perpendicularly.Then the controlling standard is decided.As Wenxiang Tunnel under-traverse Lianhuo Freeway on Zhengzhou-Xi'an Passenger Dedicated Railway Line for an example,the settlement controlling standard is acquired,and we hope it has an direction and reference value to similar tunnel construction.
基金supported by a grant from Research year of Inje University in 2008(0001200811700)
文摘This work proposes a map-based control method to improve a vehicle's lateral stability, and the performance of the proposed method is compared with that of the conventional model-referenced control method. Model-referenced control uses the sliding mode method to determine the compensated yaw moment; in contrast, the proposed map-based control uses the compensated yaw moment map acquired by vehicle stability analysis. The vehicle stability region is calculated by a topological method based on the trajectory reversal method. A 2-DOF vehicle model and Pacejka's tire model are used to evaluate the proposed map-based control method. The properties of model-referenced control and map-based control are compared under various road conditions and driving inputs. Model-referenced control uses a control input to satisfy the linear reference model, and it generates unnecessary tire lateral forces that may lead to worse performance than an uncontrolled vehicle with step steering input on a road with a low friction coefficient. However, map-based control determines a compensated yaw moment to maintain the vehicle within the stability region,so the typical responses of vehicle enable to converge rapidly. The simulation results with sine and step steering show that map-based control provides better the tracking responsibility and control performance than model-referenced control.
文摘With the advantages of long lifetime, high lighting effect and non-pollution, LED lighting has taken a leading role in the lighting sector. LED street and tunnel lights have no unified product interface, so the products of different enterprises cannot interchange with each other, restraining the development of the whole industry due to the large-scale production problem. The alliance standard CSA 016-2013 has been approved as a national standard project, paving the way for the orderly development of LED industry. Interpreting the CSA 016 standard, the paper expounds on the technical requirements for interchangeable interface in the optical, mechanical, electrical and thermal aspects.
文摘The adopted 2-D SSD (stopping sight distance) adequacy investigation in current design practice may lead to design deficiencies due to inaccurate calculation of the available sight distance. Although this concern has been identified by many research studies in the past, none of them suggested a comprehensive methodology to simulate from a 3-D perspective concurrently both the cross-section design and the vehicle dynamics in space during emergency braking conditions. The proposed methodology can accurately perform SSD adequacy investigation in any 3-D road environment where the ground, road and roadside elements are inserted by identifying areas of interrupted vision lines between driver and obstacle being less than the required distance necessary to bring the vehicle to a stop condition. The present approach provides flexibility among every road design and/or vehicle dynamic parameter inserted, as well as direct overview regarding design elements that restrict the driver's vision and create SSD inadequacies. As a result, precious guidance is provided to the designer for further alignment improvement but mostly an accurate aid to implement geometric design control criteria with respect to both existing as well as new road sections is delivered. The efficiency of the suggested methodology is demonstrated through a case study.
文摘As two kinds of management modes of highway tramc control, lane-control, and speed-control produce different effect under different conditions. In this paper, traffic flow cellular automaton models for four-lane highway system with two opposing directions under the above two modes are established considering car and truck mixed running. Through computer numerical simulating, the fundamental diagrams with different parameters are obtained, and after the analysis of density-flux diagrams, the variation discipline of flux with traffic density under different control models is gained. The results indicate that, compared with lane-control, utilization ratio of road can be further improved with speed-control when the truck number increases. The research result is of great significance for reasonable providing theoretical guidance for highway traffic control.
基金Sponsored by the National High Technology Research and Development Program of China(Grant No.2003AA1Z1350)
文摘This paper proposes a circuit structure which can be used for both synchronous and asynchronous pipeline control. It is a self-circulation structure with embedded delay network, and a pipeline can be controlled by this structure with the interconnection of adjacent stages. This paper first proposes a basic circuit structure, then a linear pipeline is designed with self-circulation structure. The performance of linear pipeline is analyzed, and a 16-bit digital signal processor (DSP) with the structure is designed to prove the validity of the structure. Results show that about 10%-15% power consumption is saved with self-circulation structure compared with synchronous counterpart, while almost the same performance is achieved.
基金supported by the National Natural Science Foundation of China(Grant Nos.51405259&51775478)
文摘When a four in-wheel motors drive electric vehicle with a specific wheels mass is running on an uneven road and transient steering occurs in the meantime, the joint action of the large unsprung dynamic load and the centrifugal force may cause the vehicle to rollover. To avoid the above accident, a rollover prevention control method based on active distribution of the in-wheel motors driving torques is investigated. First, tile rollover evolution process of the four in-wheel motors drive electric vehicle under the described operating condition is analyzed. Next, a multiple degrees of freedom vehicle dynamics model including an uneven road tyre model is established, and the rollover warning threshold is determined according to the load transfer ratio. Then, the hypothesis of the effects of unsprung mass on the vehicle roll stability on a plat road and on an uneven road is verified respectively. Finally, a rollover prevention controller is designed based on the distribution of the four wheels driving torques with sliding mode control, and the control effect is verified by simulations. The conclusion shows that, once the wheels mass does not match road conditions, the large unsprung mass may play a detrimental role on the vehicle roll stability on an uneven road, which is different from the beneficial role of large unsprung mass on the vehicle roll stability on a plat road. With the aforementioned rollover prevention controller, the vehicle rollover, which is caused by the coupling effect between large unsprung dynamic load and suspension potential energy on an uneven road, can be avoided effectively.
文摘The Chinese road has deep historical roots. Its most striking feature is that it is marked by historical continuity rather than rupture, and the main force behind this continuity is its intrinsic dynamism and vitality. Unlike the paradigm of Eurocentrism or "Discovering History in China," the comparative analytical paradigm discovers China through long-term comparisons with corresponding countries in the same time and space in an effort to find positive elements in the history of the Chinese road and to refute the long prevalent theory of Chinese stagnation. Seen over the course of world history, the impetus for the creation of the world's most brilliant agrarian civilization was endogenous. This impetus was not a momentary "explosive force" but a sustainable institutional drive whose main constituents were the independent farming household, endogenous government capacity and adaptive national governance. In addition to the main theme of "permanent change," Chinese development had a secondary theme of "cyclical change" which cannot be ignored. The roots of Chinese development are buried deep in the genes of this agrarian nation in the form of sticky institutions, bureaucratic inertia, arbitrary power, etc. Historical continuity provided a foundation for China's creative revolution and development in modern times, ultimately laying down a socialist development road with Chinese characteristics, although this remains an unfinished relay process.
文摘Inferior dislocation of the hip is the rarest type in hip dislocation. Very few cases have been reported in the anglophonic literature, most of which involved the pediatric age group. Surprisingly, we came across a 30- year-old patient with a bilateral inferior hip dislocation. He had sustained a road traffic accident and the attitude of both hip joints was flexion and abduction. The diagnosis was confirmed by radiographs which revealed the long axis of the femur at an angle of 1 l0 (right) degrees and 100 (left)degrees respectively away from the axis. Closed reduction under sedation was successfully performed. Skin traction for a period of 6 weeks was advised and the follow-up revealed an excellent result. We present the details of this case, the first of its kind along with a review of the literature, discussing the various modes and mechanisms of injury inducing inferior dislocation of the hip.
文摘Hoffa's fracture is an uncommon fracture of the femoral condyle with coronal orientation of the fracture line. The mechanism of injury in pediatric Hoffa's fracture is road traffic accident, sports injury, and trivial injury. Clinical examination and proper imaging is important for diagnosis of pediatric Hoffa's fracture because of high chances of missing these injuries which can lead to nonunion and malunion at the fracture site. Open reduction and anatomical reduction of intraarticular fragment is the gold standard treatment of these fractures. We present a rare case of Hoffa's fracture in a 16-year-old girl with asso- ciated ipsilateral fibular fracture.