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Epoxy resin (EP) is a kind of thermosetting resin, and its application is usually limited by poor toughness. In this case, a type of new flexible chain blocking hyperbranched polyester (HBP) was designed and synthesized. The purpose of this study is to enhance the toughness and dielectric properties of EP.

P-toluene sulfonic acid was used as the catalyst, with dimethy propionic acid as the branch unit and pentaerythritol as the core in the experiment. Then, n-hexanoic acid and n-caprylic acid were, respectively, put to gain HBP with a n-hexanoic acid and n-caprylic acid capped structure. The microstructure, mechanical properties, insulation properties and dielectric properties of the composite were characterized for the purpose of finding the appropriate proportion of HBP.

HBP enhanced the toughness of epoxy-cured products by interpenetrating polymer network structure between the flexible chain of HBP and the EP molecular chain. Meanwhile, HBP reduced the ε and tgδ of the epoxy anhydride-cured product by reducing the number of polar groups per unit volume of the EP through free volumes.

Yet EP is a kind of thermosetting resin, which is widely used in coating, aerospace, electronics, polymer composites and military fields, but it is usually limited by poor toughness. In a word, it is an urgent priority to develop new EP with better toughness and mechanical properties.

At present, HBP has been applied as a new kind of toughening strategy and as a modifier for EP. According to the toughening mechanism of HBP modified EP, the free volume of HBP creates a space for the EP molecule to move around when loaded. Moreover, the free volume could cause the dielectric constant of EP to diminish by reducing the content of polarizable groups. Meanwhile, the addition of HBP with flexible chains grafted to the EP could develop an interpenetrating network structure, thus further enhancing the toughness of EP

The purpose of this paper is to investigate the process optimization of a precast concrete component production line by using value stream mapping.

This paper is an empirical focused on of lean production theory and value stream mapping. The data in the case study were collected in real time on-site for each process during the production process of a prefabricated exterior wall.

The results of the current value stream map indicate that the main problems of the current production process are related to equipment, technology and organization. The equipment problems include simple demolding and cleaning tools and the lack of professional transfer channels. The technology problems include the lack of a marking mechanism and pipeline exit mechanism. There is a lack of standard operating procedures and incomplete process convergence. A comparison and analysis of the current value stream and the future value flow indicate that optimizations of the process flow, the production line layout, and the standard operating procedures have shortened the delivery cycle, reduced the number of workers, improved the operator’s operating level and balanced the production line.

The results of this study provide practitioners with a clear understanding of the optimization of the precast concrete component production and represent a method and basis for the process optimization of a factory production line; the approach is suitable for process optimization in other areas.

This research represents an innovative application of lean production theory and value stream mapping in a complex production line of precast concrete components and thereby fills the gap between the theory and practice of the optimization of a precast concrete component production line.

This paper aims to introduce a new type of analysis method to seek the actual working performance of the regulatable dry gas seal, including equilibrium film thickness, stiffness-leakage ratio and so on. Additionally, a parametric optimization of the hydrostatic structure is completed for this kind of seal.

From the point of axial force balance based on gas lubrication theory, a new analysis method, the Gas Film Divided Method, has been introduced. A four-factor and three-level hydrostatic structural parameters test scheme is designed by means of Central Composite Design test and then the hydrostatic structural parameters of regulatable dry gas seal were optimized. Three types of regulatable dry gas seal have been designed and manufactured to verify the theoretical analysis by measuring the equilibrium film thickness and inward leakage.

The results indicate that the numerical values of the Gas Film Divided (GFD) method agree well with the experimental ones. Test proves that the Central Composite Design test could achieve optimized hydrostatic structural parameters of regulatable dry gas seal effectively.

For validating the correctness of the GFD method, an experiment study of the regulatable dry gas seal is being carried out where atmosphere is selected as the lubricant for the sake of safety. Soon after, the author will discuss the application in the new paper.

The introduction of the GFD method proffers important insights to seek the performances of regulatable dry gas seal under the actual working conditions. The detailed optimal values of the hydrostatic structural parameters were given by the theoretical research which may be helpful for the design of regulatable dry gas seal.