The still-untamed SARS-CoV-2 pandemic underlined,again,two important facts that have been known for a long while but conveniently forgotten by humankind.One is that we are profoundly linked to other organisms and natu...The still-untamed SARS-CoV-2 pandemic underlined,again,two important facts that have been known for a long while but conveniently forgotten by humankind.One is that we are profoundly linked to other organisms and nature,and the other is that human-driven distribution chains are global and fast.展开更多
We live in the Age of Extinctions-the call for naming our time＂Anthropocene＂is no more than hubris and escapism from this colossal sin.Although the6thmass extinction has possibly already started（Barnosky et al.,201...We live in the Age of Extinctions-the call for naming our time＂Anthropocene＂is no more than hubris and escapism from this colossal sin.Although the6thmass extinction has possibly already started（Barnosky et al.,2011）,and it may prove the largest so far to be endured by life on Earth,efforts are needed not to turn this into the Age of Loneliness,when humans may find themselves Masters of the Earthbut alone（Wilson,2014）.展开更多
Recently,I attended a conference organised by the European Food Safety Authority in the beautiful and prosperous Italian city of Parma.The overall topic of the conference was risk assessment,and the program included a...Recently,I attended a conference organised by the European Food Safety Authority in the beautiful and prosperous Italian city of Parma.The overall topic of the conference was risk assessment,and the program included a section on aspects of environmental risk assessment.In various areas,including the evalution of the effects of pesticide applications,invasive organisms or genetically modified plants(Arpaia et al.,2014)preparing an environmental risk assessment is an obviously relevant exercise.展开更多
In this paper,we investigate the periodic traveling wave solutions problem for a single population model with advection and distributed delay.By the bifurcation analysis method,we can obtain periodic traveling wave so...In this paper,we investigate the periodic traveling wave solutions problem for a single population model with advection and distributed delay.By the bifurcation analysis method,we can obtain periodic traveling wave solutions for this model under the influence of advection term and distributed delay.The obtained results indicate that weak kernel and strong kernel can both deduce the existence of periodic traveling wave solutions.Finally,we apply the main results in this paper to Logistic model and Nicholson’s blowflies model.展开更多
Based on Gulliver's four voyages in Jonathan Swift's Gulliver's Travels this paper analyzes the author's satirical view of the state of European government and religions,and inquiry into the corruption...Based on Gulliver's four voyages in Jonathan Swift's Gulliver's Travels this paper analyzes the author's satirical view of the state of European government and religions,and inquiry into the corruption of men,and his desire to establish a harmonious and democratic Houyhnhm-like society.展开更多
In solving small- to medium-scale travelling salesman problems （TSPs） of both symmetric and asymmetric types, the traditional ant colony optimization （ACO） algorithm could work well, providing high accuracy and sa...In solving small- to medium-scale travelling salesman problems （TSPs） of both symmetric and asymmetric types, the traditional ant colony optimization （ACO） algorithm could work well, providing high accuracy and satisfactory efficiency. However, when the scale of the TSP increases, ACO, a heuristic algorithm, is greatly challenged with respect to accuracy and efficiency. A novel pheromone-trail updating strategy that moderately reduces the iteration time required in real optimization problem-solving is proposed. In comparison with the traditional strategy of the ACO in several experiments, the proposed strategy shows advantages in performance. Therefore, this strategy of pheromone-trail updating is proposed as a valuable approach that reduces the time-complexity and increases its efficiency with less iteration time in real optimization applications. Moreover, this strategy is especially applicable in solving the moderate large-scale TSPs based on ACO.展开更多
This paper carefully analyses the possibility of that a generalized KdV equa- tion possesses a family of solutions of the finite series form,and thus a kind of its explicit complex exact solutions is cxhibited.These c...This paper carefully analyses the possibility of that a generalized KdV equa- tion possesses a family of solutions of the finite series form,and thus a kind of its explicit complex exact solutions is cxhibited.These complex solutions constitute real exact so- lutions to th e system of complex form of the above generalized KdV equation.展开更多
The vehicle routing problem (VRP) can be described as the problem of designing the optimal delivery or collection routes from one or several depots to a number of geographically scattered customers, subject to load co...The vehicle routing problem (VRP) can be described as the problem of designing the optimal delivery or collection routes from one or several depots to a number of geographically scattered customers, subject to load constraints. The routing decision involves determining which of the demand s will be satisfied by each vehicle and what route each vehicle will follow in s erving its assigned demand in order to minimize total delivery cost. In this pap er, a methodology for the design of VRP by integrating optimization and simulate d annealing (SA) approach is presented hierarchically. To express the problem of vehicle routing, a new mathematical formulation is first conducted. The objecti ve function involves both the delivery cost and the vehicle acquisition cost wit h load constraints. A heuristic is then proposed to solve this problem by using SA procedure in conjunction with any solution procedure of travelling salesman p roblem (TSP). The initial configuration is arranged as one vehicle route ser ving one customer. The SA searching procedure is then developed to combine custo mer to any one of the vehicle routes existed in the system if the capacity and c ost are attractive. An important concept of this proposed heuristic is that it attempts to minimize total number of vehicle required in the system on the b asis of the fixed cost and the variable cost view points. In addition, this appr oach can be easily adapted to accommodate many additional problem complexities.展开更多
The growth of crystals of the high T c oxide superconductors has been hampe red by the complexities of the materials and their phase diagrams.The most common crys tal growth technique adopted for these oxides is the ...The growth of crystals of the high T c oxide superconductors has been hampe red by the complexities of the materials and their phase diagrams.The most common crys tal growth technique adopted for these oxides is the “flux”method,where the st arting materials are solved in a melt,which is usually formed by excess CuO and BaO or a KCl/NaCl mixture.The crystals are produced by slow cooling of the heate d solvent.This method,however,suffers from several disadvantages: (1) the crystals are contaminated with the crucible material, (2) the crystals are difficult to remove from the crucible, (3) the crystals contain flux inclusions.展开更多
In the travel process of urban residents,travelers will take a series of activities such as imitation and exclusion by observing other people’s travel modes,which affects their following trips.This process can be see...In the travel process of urban residents,travelers will take a series of activities such as imitation and exclusion by observing other people’s travel modes,which affects their following trips.This process can be seen as a repeated game between members of the travelers.Based on the analysis of this game and its evolution trend,a multi-dimensional game model of low-carbon travel for residents is established.The two dimensional game strategies include whether to accept the low-carbon concept and whether to choose low-carbon travel.Combined with evolutionary game theory,the low-carbon travel choices of residents in different cities are simulated,and the evolutionary stability strategies are obtained.Finally,the influences of the main parameters of the model on the evolution process and stability strategies are discussed.The results show that travelers would develop towards two trends.Cities with more developed public traffic system have a higher proportion of receiving low-carbon concept and choosing low-carbon travel.Cities with underdeveloped public transport system could increase this proportion by some measures such as encouraging residents to choose slow transport and increasing the propaganda of low-carbon travel,but the positive effects of the measures like propaganda have a limited impact on the proportion.展开更多
Ant colony optimization （ACO） is a new heuristic algo- rithm which has been proven a successful technique and applied to a number of combinatorial optimization problems. The traveling salesman problem （TSP） is amo...Ant colony optimization （ACO） is a new heuristic algo- rithm which has been proven a successful technique and applied to a number of combinatorial optimization problems. The traveling salesman problem （TSP） is among the most important combinato- rial problems. An ACO algorithm based on scout characteristic is proposed for solving the stagnation behavior and premature con- vergence problem of the basic ACO algorithm on TSP. The main idea is to partition artificial ants into two groups： scout ants and common ants. The common ants work according to the search manner of basic ant colony algorithm, but scout ants have some differences from common ants, they calculate each route＇s muta- tion probability of the current optimal solution using path evaluation model and search around the optimal solution according to the mutation probability. Simulation on TSP shows that the improved algorithm has high efficiency and robustness.展开更多
Based on the reliability budget and percentile travel time(PTT) concept, a new travel time index named combined mean travel time(CMTT) under stochastic traffic network was proposed. CMTT here was defined as the convex...Based on the reliability budget and percentile travel time(PTT) concept, a new travel time index named combined mean travel time(CMTT) under stochastic traffic network was proposed. CMTT here was defined as the convex combination of the conditional expectations of PTT-below and PTT-excess travel times. The former was designed as a risk-optimistic travel time index, and the latter was a risk-pessimistic one. Hence, CMTT was able to describe various routing risk-attitudes. The central idea of CMTT was comprehensively illustrated and the difference among the existing travel time indices was analyzed. The Wardropian combined mean traffic equilibrium(CMTE) model was formulated as a variational inequality and solved via an alternating direction algorithm nesting extra-gradient projection process. Some mathematical properties of CMTT and CMTE model were rigorously proved. Finally, a numerical example was performed to characterize the CMTE network. It is founded that that risk-pessimism is of more benefit to a modest(or low) congestion and risk network, however, it changes to be risk-optimism for a high congestion and risk network.展开更多
Traffic flow prediction is an important component for real-time traffic-adaptive signal control in urban arterial networks.By exploring available detector and signal controller information from neighboring intersectio...Traffic flow prediction is an important component for real-time traffic-adaptive signal control in urban arterial networks.By exploring available detector and signal controller information from neighboring intersections,a dynamic data-driven flow prediction model was developed.The model consists of two prediction components based on the signal states(red or green) for each movement at an upstream intersection.The characteristics of each signal state were carefully examined and the corresponding travel time from the upstream intersection to the approach in question at the downstream intersection was predicted.With an online turning proportion estimation method,along with the predicted travel times,the anticipated vehicle arrivals can be forecasted at the downstream intersection.The model performance was tested at a set of two signalized intersections located in the city of Gainesville,Florida,USA,using the CORSIM microscopic simulation package.Analysis results show that the model agrees well with empirical arrival data measured at 10 s intervals within an acceptable range of 10%-20%,and show a normal distribution.It is reasonably believed that the model has potential applicability for use in truly proactive real-time traffic adaptive signal control systems.展开更多
As a major mode choice of commuters for daily travel, bus transit plays an important role in many urban and metropolitan areas. This work proposes a mathematical model to optimize bus service by minimizing total cost ...As a major mode choice of commuters for daily travel, bus transit plays an important role in many urban and metropolitan areas. This work proposes a mathematical model to optimize bus service by minimizing total cost and considering a temporally and directionally variable demand. An integrated bus service, consisting of all-stop and stop-skipping services is proposed and optimized subject to directional frequency conservation, capacity and operable fleet size constraints. Since the research problem is a combinatorial optimization problem, a genetic algorithm is developed to search for the optimal result in a large solution space. The model was successfully implemented on a bus transit route in the City of Chengdu, China, and the optimal solution was proved to be better than the original operation in terms of total cost. The sensitivity of model parameters to some key attributes/variables is analyzed and discussed to explore further the potential of accruing additional benefits or avoiding some of the drawbacks of stop-skipping services.展开更多
In order to evaluate and integrate travel time reliability and capacity reliability of a road network subjected to ice and snowfall conditions,the conceptions of travel time reliability and capacity reliability were d...In order to evaluate and integrate travel time reliability and capacity reliability of a road network subjected to ice and snowfall conditions,the conceptions of travel time reliability and capacity reliability were defined under special conditions.The link travel time model(ice and snowfall based-bureau public road,ISB-BPR) and the path choice decision model(elastic demand user equilibrium,EDUE) were proposed.The integrated reliability was defined and the model was set up.Monte Carlo simulation was used to calculate the model and a numerical example was provided to demonstrate the application of the model and efficiency of the solution algorithm.The results show that the intensity of ice and snowfall,the traffic demand and supply,and the requirements for level of service(LOS) have great influence on the reliability of a road network.For example,the reliability drops from 65% to 5% when the traffic demand increases by 30%.The comprehensive performance index may be used for network planning,design and maintenance.展开更多
Ants of artificial colony are able to generate good solutions to the famous traveling salesman problem (TSP). We propose an artificial ants algorithm for solving the minimum ratio TSP, which is more general than the s...Ants of artificial colony are able to generate good solutions to the famous traveling salesman problem (TSP). We propose an artificial ants algorithm for solving the minimum ratio TSP, which is more general than the standard TSP in combinatorial optimization area. In the minimum ratio TSP, another criterion concerning each edge is added, that is, the traveling salesman can have a benefit if he travels from one city to another. The objective is to minimize the ratio between total costs or distances and total benefits. The idea of this type of optimization is in some sense quite similar to that of traditional cost-benefit analysis in management science. Computational results substantiate the solution quality and efficiency of the algorithm.展开更多
文摘The still-untamed SARS-CoV-2 pandemic underlined,again,two important facts that have been known for a long while but conveniently forgotten by humankind.One is that we are profoundly linked to other organisms and nature,and the other is that human-driven distribution chains are global and fast.
文摘We live in the Age of Extinctions-the call for naming our time＂Anthropocene＂is no more than hubris and escapism from this colossal sin.Although the6thmass extinction has possibly already started（Barnosky et al.,2011）,and it may prove the largest so far to be endured by life on Earth,efforts are needed not to turn this into the Age of Loneliness,when humans may find themselves Masters of the Earthbut alone（Wilson,2014）.
文摘Recently,I attended a conference organised by the European Food Safety Authority in the beautiful and prosperous Italian city of Parma.The overall topic of the conference was risk assessment,and the program included a section on aspects of environmental risk assessment.In various areas,including the evalution of the effects of pesticide applications,invasive organisms or genetically modified plants(Arpaia et al.,2014)preparing an environmental risk assessment is an obviously relevant exercise.
基金Supported by the National Natural Science Foundation of China(12261050)Science and Technology Project of Department of Education of Jiangxi Province(GJJ2201612 and GJJ211027)Natural Science Foundation of Jiangxi Province of China(20212BAB202021)。
文摘In this paper,we investigate the periodic traveling wave solutions problem for a single population model with advection and distributed delay.By the bifurcation analysis method,we can obtain periodic traveling wave solutions for this model under the influence of advection term and distributed delay.The obtained results indicate that weak kernel and strong kernel can both deduce the existence of periodic traveling wave solutions.Finally,we apply the main results in this paper to Logistic model and Nicholson’s blowflies model.
文摘Based on Gulliver's four voyages in Jonathan Swift's Gulliver's Travels this paper analyzes the author's satirical view of the state of European government and religions,and inquiry into the corruption of men,and his desire to establish a harmonious and democratic Houyhnhm-like society.
基金supported by the Fundamental Research Funds for the Central Universities(2015XZD15)the Soft Science Research Project of Guangdong Province(2015A070704015)+1 种基金the Guangdong Province Key Laboratory Open Foundation(2011A06090100101B)the Technology Trading System and Science&Technology Service Network Construction Project of Guangdong Province(2014A040402003)
文摘In solving small- to medium-scale travelling salesman problems （TSPs） of both symmetric and asymmetric types, the traditional ant colony optimization （ACO） algorithm could work well, providing high accuracy and satisfactory efficiency. However, when the scale of the TSP increases, ACO, a heuristic algorithm, is greatly challenged with respect to accuracy and efficiency. A novel pheromone-trail updating strategy that moderately reduces the iteration time required in real optimization problem-solving is proposed. In comparison with the traditional strategy of the ACO in several experiments, the proposed strategy shows advantages in performance. Therefore, this strategy of pheromone-trail updating is proposed as a valuable approach that reduces the time-complexity and increases its efficiency with less iteration time in real optimization applications. Moreover, this strategy is especially applicable in solving the moderate large-scale TSPs based on ACO.
文摘This paper carefully analyses the possibility of that a generalized KdV equa- tion possesses a family of solutions of the finite series form,and thus a kind of its explicit complex exact solutions is cxhibited.These complex solutions constitute real exact so- lutions to th e system of complex form of the above generalized KdV equation.
文摘The vehicle routing problem (VRP) can be described as the problem of designing the optimal delivery or collection routes from one or several depots to a number of geographically scattered customers, subject to load constraints. The routing decision involves determining which of the demand s will be satisfied by each vehicle and what route each vehicle will follow in s erving its assigned demand in order to minimize total delivery cost. In this pap er, a methodology for the design of VRP by integrating optimization and simulate d annealing (SA) approach is presented hierarchically. To express the problem of vehicle routing, a new mathematical formulation is first conducted. The objecti ve function involves both the delivery cost and the vehicle acquisition cost wit h load constraints. A heuristic is then proposed to solve this problem by using SA procedure in conjunction with any solution procedure of travelling salesman p roblem (TSP). The initial configuration is arranged as one vehicle route ser ving one customer. The SA searching procedure is then developed to combine custo mer to any one of the vehicle routes existed in the system if the capacity and c ost are attractive. An important concept of this proposed heuristic is that it attempts to minimize total number of vehicle required in the system on the b asis of the fixed cost and the variable cost view points. In addition, this appr oach can be easily adapted to accommodate many additional problem complexities.
文摘The growth of crystals of the high T c oxide superconductors has been hampe red by the complexities of the materials and their phase diagrams.The most common crys tal growth technique adopted for these oxides is the “flux”method,where the st arting materials are solved in a melt,which is usually formed by excess CuO and BaO or a KCl/NaCl mixture.The crystals are produced by slow cooling of the heate d solvent.This method,however,suffers from several disadvantages: (1) the crystals are contaminated with the crucible material, (2) the crystals are difficult to remove from the crucible, (3) the crystals contain flux inclusions.
基金Project(BK20160512)supported by the Natural Science Foundation of Jiangsu Province,ChinaProject(16YJCZH027)supported by the Humanity and Social Science Youth Foundation of Ministry of Education of ChinaProject(15GLC004)supported by the Social Science Foundation of Jiangsu Province,China
文摘In the travel process of urban residents,travelers will take a series of activities such as imitation and exclusion by observing other people’s travel modes,which affects their following trips.This process can be seen as a repeated game between members of the travelers.Based on the analysis of this game and its evolution trend,a multi-dimensional game model of low-carbon travel for residents is established.The two dimensional game strategies include whether to accept the low-carbon concept and whether to choose low-carbon travel.Combined with evolutionary game theory,the low-carbon travel choices of residents in different cities are simulated,and the evolutionary stability strategies are obtained.Finally,the influences of the main parameters of the model on the evolution process and stability strategies are discussed.The results show that travelers would develop towards two trends.Cities with more developed public traffic system have a higher proportion of receiving low-carbon concept and choosing low-carbon travel.Cities with underdeveloped public transport system could increase this proportion by some measures such as encouraging residents to choose slow transport and increasing the propaganda of low-carbon travel,but the positive effects of the measures like propaganda have a limited impact on the proportion.
基金supported by the National Natural Science Foundation of China(60573159)
文摘Ant colony optimization （ACO） is a new heuristic algo- rithm which has been proven a successful technique and applied to a number of combinatorial optimization problems. The traveling salesman problem （TSP） is among the most important combinato- rial problems. An ACO algorithm based on scout characteristic is proposed for solving the stagnation behavior and premature con- vergence problem of the basic ACO algorithm on TSP. The main idea is to partition artificial ants into two groups： scout ants and common ants. The common ants work according to the search manner of basic ant colony algorithm, but scout ants have some differences from common ants, they calculate each route＇s muta- tion probability of the current optimal solution using path evaluation model and search around the optimal solution according to the mutation probability. Simulation on TSP shows that the improved algorithm has high efficiency and robustness.
基金Project(2012CB725403-5)supported by National Basic Research Program of ChinaProject(71131001-2)supported by National Natural Science Foundation of China+1 种基金Projects(2012JBZ005)supported by Fundamental Research Funds for the Central Universities,ChinaProject(201170)supported by the Foundation for National Excellent Doctoral Dissertation of China
文摘Based on the reliability budget and percentile travel time(PTT) concept, a new travel time index named combined mean travel time(CMTT) under stochastic traffic network was proposed. CMTT here was defined as the convex combination of the conditional expectations of PTT-below and PTT-excess travel times. The former was designed as a risk-optimistic travel time index, and the latter was a risk-pessimistic one. Hence, CMTT was able to describe various routing risk-attitudes. The central idea of CMTT was comprehensively illustrated and the difference among the existing travel time indices was analyzed. The Wardropian combined mean traffic equilibrium(CMTE) model was formulated as a variational inequality and solved via an alternating direction algorithm nesting extra-gradient projection process. Some mathematical properties of CMTT and CMTE model were rigorously proved. Finally, a numerical example was performed to characterize the CMTE network. It is founded that that risk-pessimism is of more benefit to a modest(or low) congestion and risk network, however, it changes to be risk-optimism for a high congestion and risk network.
基金Project(71101109) supported by the National Natural Science Foundation of China
文摘Traffic flow prediction is an important component for real-time traffic-adaptive signal control in urban arterial networks.By exploring available detector and signal controller information from neighboring intersections,a dynamic data-driven flow prediction model was developed.The model consists of two prediction components based on the signal states(red or green) for each movement at an upstream intersection.The characteristics of each signal state were carefully examined and the corresponding travel time from the upstream intersection to the approach in question at the downstream intersection was predicted.With an online turning proportion estimation method,along with the predicted travel times,the anticipated vehicle arrivals can be forecasted at the downstream intersection.The model performance was tested at a set of two signalized intersections located in the city of Gainesville,Florida,USA,using the CORSIM microscopic simulation package.Analysis results show that the model agrees well with empirical arrival data measured at 10 s intervals within an acceptable range of 10%-20%,and show a normal distribution.It is reasonably believed that the model has potential applicability for use in truly proactive real-time traffic adaptive signal control systems.
基金Project(B01B1203)supported by Sichuan Province Key Laboratory of Comprehensive Transportation,ChinaProject(SWJTU09BR141)supported by the Southwest Jiaotong University,China
文摘As a major mode choice of commuters for daily travel, bus transit plays an important role in many urban and metropolitan areas. This work proposes a mathematical model to optimize bus service by minimizing total cost and considering a temporally and directionally variable demand. An integrated bus service, consisting of all-stop and stop-skipping services is proposed and optimized subject to directional frequency conservation, capacity and operable fleet size constraints. Since the research problem is a combinatorial optimization problem, a genetic algorithm is developed to search for the optimal result in a large solution space. The model was successfully implemented on a bus transit route in the City of Chengdu, China, and the optimal solution was proved to be better than the original operation in terms of total cost. The sensitivity of model parameters to some key attributes/variables is analyzed and discussed to explore further the potential of accruing additional benefits or avoiding some of the drawbacks of stop-skipping services.
基金Project(E200940) supported by the Natural Science Foundation of Heilongjiang Province, ChinaProject(2009GC20008020) supported by the Technology Research and Development Program of Shandong Province, China
文摘In order to evaluate and integrate travel time reliability and capacity reliability of a road network subjected to ice and snowfall conditions,the conceptions of travel time reliability and capacity reliability were defined under special conditions.The link travel time model(ice and snowfall based-bureau public road,ISB-BPR) and the path choice decision model(elastic demand user equilibrium,EDUE) were proposed.The integrated reliability was defined and the model was set up.Monte Carlo simulation was used to calculate the model and a numerical example was provided to demonstrate the application of the model and efficiency of the solution algorithm.The results show that the intensity of ice and snowfall,the traffic demand and supply,and the requirements for level of service(LOS) have great influence on the reliability of a road network.For example,the reliability drops from 65% to 5% when the traffic demand increases by 30%.The comprehensive performance index may be used for network planning,design and maintenance.
基金This project was supported by the Shanghai Education Development Foundation (No.2000SG30).
文摘Ants of artificial colony are able to generate good solutions to the famous traveling salesman problem (TSP). We propose an artificial ants algorithm for solving the minimum ratio TSP, which is more general than the standard TSP in combinatorial optimization area. In the minimum ratio TSP, another criterion concerning each edge is added, that is, the traveling salesman can have a benefit if he travels from one city to another. The objective is to minimize the ratio between total costs or distances and total benefits. The idea of this type of optimization is in some sense quite similar to that of traditional cost-benefit analysis in management science. Computational results substantiate the solution quality and efficiency of the algorithm.
