Joint Optimization Of Fresh Agri-products On Harvest And Distribution Considering Maturity

Fresh agri-products have the characteristics of seasonality,freshness,perishability and regionality,then how to establish an efficient and complete logistics distribution system have become a hot issue in the field of agricultural management in order to maintain the quality and the taste of fresh agri-products.Therefore,compressing the supply chain of fresh agri-products,enhancing the efficiency of harvest and distribution of fresh agri-products,and ensuring maturity and freshness are key issues that need to be solved in "farm to door" mode.This thesis takes fresh agri-products as the research obj ect.The decision objective is to ensure the freshness and to minimize the total costs.The key research issues are when to harvest and how to obtain the optimal distribution routing.The entry point is the maturity fitting model In accordance with the basic research ideas of "definition problems-recognition problems-solving problems",focusing on the inherent decision-making requirements of integration and time-space research problems,we use the theoretical methods of curve regression analysis,vehicle routing problem with time windows,genetic algorithm and time-space network flow to carry out the model and designed algorithms.In view of the above problems,the main researched works of this thesis are as follows:(1)For the contradiction between high perishability and maturity of fresh agri-products,we use Statistics to study the maturity of fresh agri-products.Firstly,the curve regression is used to predict the time functions of color,firmness,soluble solids and sense respectively.Secondly,the principal component analysis is used to analyze principal component variables.Thirdly,we use Logistic regression analysis to establish the maturity model with time varying.The measured data are applied to verify the accuracy of the model.(2)For the interdependence of the integrated harvest and distribution of fresh agri-products,we analyze the research problem from three aspects:Firstly,the joint optimization problem of harvest and distribution is analyzed and considered from the perspective of system integration.The quadratic quality loss function is introduced in the established mixed integer programming model,and we analyze the complexity of the model.Secondly,combined with the internal characteristics of the constructed model,an improved adaptive genetic algorithm is designed which concludes crossover probability and mutation probability methods.Thirdly,the small-scale cases are designed to verify the accuracy of the model,and the large-scale cases are to verify the validity of the algorithm,which provides a new idea for the modeling problem of joint optimization of fresh agri-products.(3)In view of the time complexity and spatial complexity of fresh agri-products,we analyze the research problem from three aspects:Firstly,with the time-space network flow method,we propose the joint optimization problem of harvest and distribution for fresh agri-products under the coupling of decision variables.The highest customer satisfaction takes as the decision target,then we build up a time-space network flow model that combining harvest and distribution with the maturity of fresh agri-products.Secondly,the differential evolution algorithm is used to solve the established model according to the structural characteristics of the model.Thirdly,the small-scale cases are designed to verify the accuracy of the model,and the large-scale cases is to verify the validity of the algorithm,which provides a new idea for the modeling problem of joint optimization of fresh agri-products.The research work of this thesis solves the problem of joint optimization of harvest and distribution of fresh agri-products,and deals with the problem that the integrated difficult optimization model,which provides an effective theory for harvest and distribution decision of fresh agri-products.Meanwhile,the basic and methodological systems have practical guiding significance and theoretical significance for the preservation of fresh agri-products and the improvement of customer satisfaction.