Modeling And Optimization Research On The Cold Chain Distribution Process Based On Stochastic Petri Net

The growing demand for cold-chain food puts forward to higher requirements to cold chain logistics in our country. Since the cold chain food is more sensitive to time and temperature, delivering on-time and keeping food fresh are both important. Cold chain logistics develops slowly in our country. At the same time, unreasonable, nonstandard or low-efficient link exists in the process of cold chain distribution process, which poses threat to food safety and may cause unnecessary waste. So this paper focus on the research of cold chain logistics distribution process to boost the efficiency.This paper analyzed logistics distribution process of cold chain by modeling in which introduced stochastic Petri net with time parameter, based on which the process optimization was given. Firstly, we introduced the research background of the cold chain logistics distribution process and its theoretical and practical significance was interpreted. The research status of cold chain logistics, delivery process and method of Petri net was reviewed. And the research method and technology route which would be used in this dissertation were discussed. Then we introduced the basic theories related to this paper, including the concept and characteristics of cold chain logistics, cold chain logistics process, modeling methods used for process, stochastic Petri net concepts, and its basic properties and analysis method. We analyzed the cold chain logistics distribution process in detail, and thus lay the sound foundation for the subsequent stochastic Petri net modeling. Then we introduced stochastic Petri net process elements, the logical relationship and modeling steps, which is modeled on this. Finally, combined with the certain case, the model of cold chain logistics distribution process with stochastic Petri net was built. Through the structural analysis, we gave verification to the model’s boundedness, liveness and reachability, and further to prove the validity of the model. Then we used the Markov chain to analyze the performance of the model in order to find out the low efficient distribution process and propose optimized scheme based on the performance analysis. Through remodeling and comparative analysis, we could find that on one hand the average delay time in distribution process was shorten, on the other hand the ratio of cargo sorting process, delivery and transfer process in the total distribution process declined. Through this we can see that the efficiency of cold chain logistics distribution is improved, and also proves that the optimization scheme and stochastic Petri net method for cold chain logistics distribution process modeling, analysis and optimization is feasible.