To reduce the risk of traffic accidents significantly caused by the speeding behavior of electric bicycles,this study focuses on the Beijing Yizhuang Economic and Tech-nological Development Zone.This work relies on hi...To reduce the risk of traffic accidents significantly caused by the speeding behavior of electric bicycles,this study focuses on the Beijing Yizhuang Economic and Tech-nological Development Zone.This work relies on high-precision shared electric bicycle Global Positioning System trajectory data,integrating a spatiotemporal analysis model and geographic information system(GIS)technol-ogy to explore the spatial and temporal variability law and formation mechanism of speeding behavior.Through data preprocessing,speeding events are identified,and weekday features are extracted.Four periods are identified:morning peak,midday minipeak,evening peak,and nighttime flat peak.Using the GIS platform,global spatial autocorrela-tion and local clustering analysis are conducted to identify the spatial clustering characteristics of speeding behaviors and hotspot areas.The coldspot and hotspot patterns of speeding events and the dynamic trajectories of their evolu-tion are analyzed using spatiotemporal cube technology.The results show that speeding behaviors are strongly corre-lated with the commuting peak in time and spatially concen-trated in the intersections of urban main roads,the periphery of commercial complexes,and industrial parks,with a dif-fusion tendency.The results of this study provide novel in-sights into the research and analysis of the spatial and tempo-ral characteristics of speeding risk behaviors of electric bi-cycles and effective technical support for nonmotorized traf-fic safety management.展开更多
In this paper, an iterative learning control algorithm is proposed for discrete linear time-varying systems to track iterationvarying desired trajectories. A high-order internal model(HOIM) is utilized to describe the...In this paper, an iterative learning control algorithm is proposed for discrete linear time-varying systems to track iterationvarying desired trajectories. A high-order internal model(HOIM) is utilized to describe the variation of desired trajectories in the iteration domain. In the sequel, the HOIM is incorporated into the design of learning gains. The learning convergence in the iteration axis can be guaranteed with rigorous proof. The simulation results with permanent magnet linear motors(PMLM) demonstrate that the proposed HOIM based approach yields good performance and achieves perfect tracking.展开更多
This paper studies a multiple unmanned aerial vehicle(UAV)relaying communication system,where multiple UAV re-lays assist the blocked communication between a group of ground users(GUs)and a base station(BS).Since the ...This paper studies a multiple unmanned aerial vehicle(UAV)relaying communication system,where multiple UAV re-lays assist the blocked communication between a group of ground users(GUs)and a base station(BS).Since the UAVs only have limited-energy in practice,our design aims to maximize the energy efficiency(EE)through jointly designing the communica-tion scheduling,the transmit power allocation,as well as UAV trajectory under the buffer constraint over a given flight period.Actually,the formulated fractional optimization problem is diffi-cult to be solved in general because of non-convexity.To re-solve this difficulty,an efficient iterative algorithm is proposed based on the block coordinate descent(BCD)and successive convex approximation(SCA)techniques,as well as the Dinkel-bach’s algorithm.Specifically,the optimization variables of the formulated problem are divided into three blocks and we alter-nately optimize each block of the variables over iteration.Numeri-cal results verify the convergence of the proposed iterative al-gorithm and show that the proposed designs achieve significant EE gain,which outperform other benchmark schemes.展开更多
Space emergency launching is to send a satellite into space by using a rapid responsive solid rocket in the bounded time to implement the emergency Earth observation mission.The key and difficult points mainly include...Space emergency launching is to send a satellite into space by using a rapid responsive solid rocket in the bounded time to implement the emergency Earth observation mission.The key and difficult points mainly include the business process construction of launching mission planning,validation of the effectiveness of the launching scheme,etc.This paper pro-poses the agile space emergency launching mission planning simulation and verification method,which systematically con-structs the overall technical framework of space emergency launching mission planning with multi-field area,multi-platform and multi-task parallel under the constraint of resource schedul-ing for the first time.It supports flexible reconstruction of mis-sion planning processes such as launching target planning,tra-jectory planning,path planning,action planning and launching time analysis,and can realize on-demand assembly of operation links under different mission scenarios and different plan condi-tions,so as to quickly modify and generate launching schemes.It supports the fast solution of rocket trajectory data and the accurate analysis of multi-point salvo time window recheck and can realize the fast conflict resolution of launching missions in the dimensions of launching position and launching window sequence.It supports lightweight scenario design,modular flexi-ble simulation,based on launching style,launching platform,launching rules,etc.,can realize the independent mapping of mission planning results to two-dimensional and three-dimen-sional visual simulation models,so as to achieve a smooth con-nection between mission planning and simulation.展开更多
This study explores the efficacy of advanced antibiotic compounds against P. aeruginosa, focusing on Antibiotic B, an enhanced derivative of Ceftriaxone. The study measured the intracellular uptake of Antibiotic B and...This study explores the efficacy of advanced antibiotic compounds against P. aeruginosa, focusing on Antibiotic B, an enhanced derivative of Ceftriaxone. The study measured the intracellular uptake of Antibiotic B and introduced a novel adjuvant, Influximax, which augmented its antibacterial activity. Results showed a diminished potential for resistance emergence with Antibiotic B, particularly when used in combination with Influximax. The study suggests that optimizing antibiotic delivery into bacterial cells and leveraging syner-gistic adjuvant combinations can enhance drug resistance combat. .展开更多
To aim at the substitution of the magnitude and direction of water flow movement near bed for those of bed load transport in solid-liquid two-phase one-fluid model,and to simulate the effect of secondary flow on trans...To aim at the substitution of the magnitude and direction of water flow movement near bed for those of bed load transport in solid-liquid two-phase one-fluid model,and to simulate the effect of secondary flow on transverse bed load transport in channel bends and the effect of bed slope on bed load trans-port in a better way,a three-dimensional k-ε-kp solid-liquid two-phase two-fluid model in curvilinear coordinates is solved numerically with a finite-volume method on an adaptive grid for studying wa-ter-sediment movements and bed evolution in a 120°channel bend.Numerical results show that the trajectories of solid-phase deviate from those of liquid-phase in the channel bend,and the deviation increases with the increase of the particle diameters.The calculated bed deformation by the k-ε-kp model is in better agreement with measured bed deformation than those by one-fluid model.It is proved that the k-ε-kp model can simulate the effect of secondary flow on lateral bed load transport with the higher accuracy than the one-fluid model.展开更多
Enabling cellular access for unmanned aerial vehicles(UAVs)is a practically appealing solution to realize their high-quality communications with the ground for ensuring safe and efficient operations.In this paper,we s...Enabling cellular access for unmanned aerial vehicles(UAVs)is a practically appealing solution to realize their high-quality communications with the ground for ensuring safe and efficient operations.In this paper,we study the trajectory design for a cellular-connected UAV that needs to fly from given initial to final locations,while communicating with the ground base stations(GBSs)subject to a minimum signal-to-noise ratio(SNR)requirement along its flight.However,due to various practical considerations such as GBSs’locations and coverage range as well as UAV’s trajectory and mobility constraints,the SNR target may not be met at certain time periods during the flight,each termed as an outage duration.In this paper,we first propose a general outage cost function in terms of outage durations in the flight,which includes the two commonly used metrics,namely total outage duration and maximum outage duration as special cases.Based on it,we formulate a UAV trajectory optimization problem to minimize its mission completion time,subject to a constraint on the maximum tolerable outage cost.To tackle this challenging(non-convex)optimization problem,we first transform it into a tractable form and thereby reveal some useful properties of the optimal trajectory solution.Based on these properties,we further simplify the problem and propose efficient algorithms to check its feasibility and obtain optimal as well as low-complexity suboptimal solutions for it by leveraging graph theory and convex optimization techniques.Numerical results show that our proposed trajectory designs outperform that by the conventional method of dynamic programming,in terms of both performance and complexity.展开更多
基金The National Natural Science Foundation of China(No. 52072012)。
文摘To reduce the risk of traffic accidents significantly caused by the speeding behavior of electric bicycles,this study focuses on the Beijing Yizhuang Economic and Tech-nological Development Zone.This work relies on high-precision shared electric bicycle Global Positioning System trajectory data,integrating a spatiotemporal analysis model and geographic information system(GIS)technol-ogy to explore the spatial and temporal variability law and formation mechanism of speeding behavior.Through data preprocessing,speeding events are identified,and weekday features are extracted.Four periods are identified:morning peak,midday minipeak,evening peak,and nighttime flat peak.Using the GIS platform,global spatial autocorrela-tion and local clustering analysis are conducted to identify the spatial clustering characteristics of speeding behaviors and hotspot areas.The coldspot and hotspot patterns of speeding events and the dynamic trajectories of their evolu-tion are analyzed using spatiotemporal cube technology.The results show that speeding behaviors are strongly corre-lated with the commuting peak in time and spatially concen-trated in the intersections of urban main roads,the periphery of commercial complexes,and industrial parks,with a dif-fusion tendency.The results of this study provide novel in-sights into the research and analysis of the spatial and tempo-ral characteristics of speeding risk behaviors of electric bi-cycles and effective technical support for nonmotorized traf-fic safety management.
基金supported by National Basic Research Program of China(973 Program)(No.2012CB316400)National Natural Science Foundation of China(Nos.61171034 and 61273134)
文摘In this paper, an iterative learning control algorithm is proposed for discrete linear time-varying systems to track iterationvarying desired trajectories. A high-order internal model(HOIM) is utilized to describe the variation of desired trajectories in the iteration domain. In the sequel, the HOIM is incorporated into the design of learning gains. The learning convergence in the iteration axis can be guaranteed with rigorous proof. The simulation results with permanent magnet linear motors(PMLM) demonstrate that the proposed HOIM based approach yields good performance and achieves perfect tracking.
基金supported by the National Natural Science Foundation of China(61671474).
文摘This paper studies a multiple unmanned aerial vehicle(UAV)relaying communication system,where multiple UAV re-lays assist the blocked communication between a group of ground users(GUs)and a base station(BS).Since the UAVs only have limited-energy in practice,our design aims to maximize the energy efficiency(EE)through jointly designing the communica-tion scheduling,the transmit power allocation,as well as UAV trajectory under the buffer constraint over a given flight period.Actually,the formulated fractional optimization problem is diffi-cult to be solved in general because of non-convexity.To re-solve this difficulty,an efficient iterative algorithm is proposed based on the block coordinate descent(BCD)and successive convex approximation(SCA)techniques,as well as the Dinkel-bach’s algorithm.Specifically,the optimization variables of the formulated problem are divided into three blocks and we alter-nately optimize each block of the variables over iteration.Numeri-cal results verify the convergence of the proposed iterative al-gorithm and show that the proposed designs achieve significant EE gain,which outperform other benchmark schemes.
文摘Space emergency launching is to send a satellite into space by using a rapid responsive solid rocket in the bounded time to implement the emergency Earth observation mission.The key and difficult points mainly include the business process construction of launching mission planning,validation of the effectiveness of the launching scheme,etc.This paper pro-poses the agile space emergency launching mission planning simulation and verification method,which systematically con-structs the overall technical framework of space emergency launching mission planning with multi-field area,multi-platform and multi-task parallel under the constraint of resource schedul-ing for the first time.It supports flexible reconstruction of mis-sion planning processes such as launching target planning,tra-jectory planning,path planning,action planning and launching time analysis,and can realize on-demand assembly of operation links under different mission scenarios and different plan condi-tions,so as to quickly modify and generate launching schemes.It supports the fast solution of rocket trajectory data and the accurate analysis of multi-point salvo time window recheck and can realize the fast conflict resolution of launching missions in the dimensions of launching position and launching window sequence.It supports lightweight scenario design,modular flexi-ble simulation,based on launching style,launching platform,launching rules,etc.,can realize the independent mapping of mission planning results to two-dimensional and three-dimen-sional visual simulation models,so as to achieve a smooth con-nection between mission planning and simulation.
文摘This study explores the efficacy of advanced antibiotic compounds against P. aeruginosa, focusing on Antibiotic B, an enhanced derivative of Ceftriaxone. The study measured the intracellular uptake of Antibiotic B and introduced a novel adjuvant, Influximax, which augmented its antibacterial activity. Results showed a diminished potential for resistance emergence with Antibiotic B, particularly when used in combination with Influximax. The study suggests that optimizing antibiotic delivery into bacterial cells and leveraging syner-gistic adjuvant combinations can enhance drug resistance combat. .
基金Supported by the National Natural Science Foundation of China(Grant No.50839001)the National Basic Research Program of China("973")(Grant No.2005CB724202)
文摘To aim at the substitution of the magnitude and direction of water flow movement near bed for those of bed load transport in solid-liquid two-phase one-fluid model,and to simulate the effect of secondary flow on transverse bed load transport in channel bends and the effect of bed slope on bed load trans-port in a better way,a three-dimensional k-ε-kp solid-liquid two-phase two-fluid model in curvilinear coordinates is solved numerically with a finite-volume method on an adaptive grid for studying wa-ter-sediment movements and bed evolution in a 120°channel bend.Numerical results show that the trajectories of solid-phase deviate from those of liquid-phase in the channel bend,and the deviation increases with the increase of the particle diameters.The calculated bed deformation by the k-ε-kp model is in better agreement with measured bed deformation than those by one-fluid model.It is proved that the k-ε-kp model can simulate the effect of secondary flow on lateral bed load transport with the higher accuracy than the one-fluid model.
文摘Enabling cellular access for unmanned aerial vehicles(UAVs)is a practically appealing solution to realize their high-quality communications with the ground for ensuring safe and efficient operations.In this paper,we study the trajectory design for a cellular-connected UAV that needs to fly from given initial to final locations,while communicating with the ground base stations(GBSs)subject to a minimum signal-to-noise ratio(SNR)requirement along its flight.However,due to various practical considerations such as GBSs’locations and coverage range as well as UAV’s trajectory and mobility constraints,the SNR target may not be met at certain time periods during the flight,each termed as an outage duration.In this paper,we first propose a general outage cost function in terms of outage durations in the flight,which includes the two commonly used metrics,namely total outage duration and maximum outage duration as special cases.Based on it,we formulate a UAV trajectory optimization problem to minimize its mission completion time,subject to a constraint on the maximum tolerable outage cost.To tackle this challenging(non-convex)optimization problem,we first transform it into a tractable form and thereby reveal some useful properties of the optimal trajectory solution.Based on these properties,we further simplify the problem and propose efficient algorithms to check its feasibility and obtain optimal as well as low-complexity suboptimal solutions for it by leveraging graph theory and convex optimization techniques.Numerical results show that our proposed trajectory designs outperform that by the conventional method of dynamic programming,in terms of both performance and complexity.
