Research On Polypropylene Grade Transition Optimization Algorithms And Its Software Implementation

Polypropylene (PP) is a thermoplastic polymer, made by the chemical industry and used in a wide variety of applications, including chemical industry, light industry, household appliances, electronics, building materials etc. Polypropylene has good performance, such as low production cost, high hardness, light weight, and good chemical resistance etc. Companies need transit PP grades frequently to meet the market demand. Therefore, the research of polypropylene grade transition optimization method and the development of polypropylene grade transition optimization software, which are in order to shorten the transition time of grade transition and to reduce the by-product during the grade transition, have an important significance for the industrial development of PP. The main research work and the achievements are listed as follows:1. Based on the inspection of industrial production at home and abroad, as well as polypropylene grade transition on the literature, grade transition model and related factors were outlined, and optimization methods to solve the problem were introduced.2. Adaptive differential evolution (ADE) algorithm was proposed to improve the searching efficiency of simple differential evolution (DE) algorithm. An adaptive mutation operator was introduced to improve the diversity of populations and enhance the algorithm's capability of finding global optimum. A disturbance scaling factor was also introduced in order to keep the population diversity. Typical examples indicated good performance of the new algorithm. Finally, the ADE has been successfully applied to optimal grade transition in polypropylene production process.3. According to grade transition for the non-linear, distributed parameter, strong coupling and mixing of the characteristics, researching variable selection, mutation and crossover operator on the performance of DE algorithm, differential evolution based on distance measurement (DEDM) algorithm was proposed. An adaptive weighted mutation strategy was introduced to make a good tradeoff between the exploration and exploitation. An adaptive scaling factor based on distance measurement was also introduced in order to keep the population diversity. Numerical experiments using a set of 30 test problems indicated the new algorithm is considerably better and more efficient than the DE, DERL and DERB algorithm. Finally, the DEDM has been successfully applied to optimal grade transition in polypropylene production process.4. Using object-oriented software design method, considering software design goals and principles, based on demand analysis, overall structure, software framework and functional model of polypropylene grade transition optimization software were designed. According to data access frequency and flow, database program of optimization software was designed. Grade production simulation module, grade transition optimization module, grade transition control module, and knowledge-based management module were developed.5. Finally, the conclusions were presented, and further research directions were proposed.