Modeling And Simulation Of Individual Activity Decision-making Under The Condition Of Uncertain Activity Duration

In the study of traffic behavior,the traditional behavior model analysis method is lacking in the time and space relations between travel and travel,interpersonal relationship and the relationship between activities and travel,and has gradually been replaced by the analysis of time and geography.Time geography studies the travelers and related activities in a unified space and time environment,and puts forward the concept of space-time accessibility,which provides a new perspective for the research methods of traffic behavior.According to the time and space accessibility theory,the individual forms the individual activity pattern by sorting daily activities into the time windows in their own and ordering the activities according to the priority of the activities.However,the current model generation models are usually given priority to the commuter activities such as work and school as fixed activity classes,while other classes are flexible after the fixed activity arrangement,and the other hypothesis is implied in the process of handling the time information of the fixed activity.The time information of the fixed activity in the schedule is exactly the same,that is,the possibility of the readjustment of the fixed activity plan,such as the uncertainty of the duration of the fixed activity,which leads to the change of the activity time of the follow-up flexibility,and the default fixed activity is done strictly according to the plan.In real life,there are obvious deficiencies in this hypothesis,which makes the model have some limitations in practical application,that is,it can not predict how the individual changes the activity plan when the environment changes to the environment.Secondly,according to the setting of the activity priority,the completion of the elastic activity depends on the execution of the fixed activity,but in making a specific flexibility decision,the execution time of the fixed activity will affect the completion time of the later elastic activity,that is,the later elastic activity.Decision making is closely related to the execution of the previous fixed activity.And the time,space and activity subjects,as the basic decision-making elements of activity,are also the key measure variables of temporal and spatial accessibility.Therefore,the decision of flexible activities is the result of the relevance of the elements of activities,and the decision-making process is a process of interaction among different elements.The high flexibility activity of elastic activity in the three dimensions of time,space and active body determines the decision selection set of elastic activity.The individual must adjust the activity decision to eliminate the change of the choice set of the activity constraint caused by the change of the external conditions.The newly generated activity model is the individual time,space and active owner.The result of a rebalancing between the bodies.Therefore,the paper considers the change in the time information of the fixed activities in the decision-making process,and takes the space-time prism formed by any two temporary adjacent fixed activities in the individual activity plan as the basic decision unit,and pays attention to the influence of the duration uncertainty on the individual activity trip decision,from the time and space.With the basic elements of three activities decision making,the time geography theory is used to study the decision-making process of individual activity pattern,so as to achieve the goal of explaining the travel behavior from the individual activity pattern.The main research work is as follows:First,based on the space-time Accessibility Theory,considering the uncertainty of the duration of fixed activity,the influence of factor relevance on individual behavior is studied.Starting with the basic three elements of the activity decision,this paper analyzes the mechanism between the spatiotemporal accessibility,the factor relevance and the activity pattern,and proposes to consider the inaccuracy of the duration of the activity.The theoretical framework of individual activity decision process and adjustment is determined.Second,by extending the traditional space-time prism,the paper introduces the uncertainty factors caused by the external conditions into the study of the space-time prism.The penalty function is introduced to quantify the effect of the inconsistent implementation of the fixed activity and the plan disagreement,and the space-time window formed by the two adjacent fixed activities is the basic decision making list.On the basis of place relevance,activity time relevance and subjective relevance,a accessibility measure model,which considers space-time constraints,place attraction,activity relevance and individual attributes,is proposed to measure the accessibility of individual completion activities under the uncertainty of the end time of fixed activities.Then,based on objective function of achieves k maximum accessibility,and constructs a decision model of activity pattern adjustment.Third,to verify the applicability of the proposed model in daily life through scene simulation,and to evaluate the impact of individual space-time accessibility changes on their activity travel mode under the influence of external influence.This paper takes the individual from the core family as an example,and takes the maximum utility as the objective function under the specific time and space constraints,and combines the scene simulation under different constraints,and uses the designed genetic algorithm to solve the problem.The simulation results show that,when the changes in the environment are considered,the activity decision of individual is adjustable in time,space and activity participants,and the activity is transferable.It verifies the theory proposed by the paper and the reasonableness of the constructed model,and also verifies the proposed rules of activity adjustment.