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Direct arylation polycondensation is regarded as an efficient synthetic method for conjugated polymers. This methodology is difficult to apply to dichloroaryl monomers because of the low reactivity of the C–Cl bonds compared to that of the C–Br bonds in dibromoaryl monomers, which have been widely used in direct arylation polycondensation. In this research, direct arylation polycondensation of dichloroaryl monomers was achieved by the use of a Pd/Cu binary catalytic system. Optimisation of the molar ratio of the Pd and Cu catalyst resulted in the formation of high-molecular-weight polymers in good yields. Structural defects of the polymer at the terminal unit were minimised by logical choice of the monomer ratio on the basis of the reaction mechanism. The obtained polymer with relatively low structural defects showed a higher quantum efficiency of photoluminescence and electroluminescence than that of the polymer with irregular terminal structures.

Degradation of multi-component system exists widely in the field of engineering. And the degradation failure of multi-component system is due to the overall degradation of the system to a certain extent, or the degradation of component. In this paper, we focus on the reliability model of multi-component degradation system, which failure caused by degradation of component failure, was simplified and applied to the optimization model of maintenance policy. For each component of the degraded system, pure degradation and degradation increment can cause irreversible damage to it. The continuous degradation process was considered to be linear. And the degradation increment caused by the shock was considered to be cumulative. The shock was random, so that subject to Poisson distribution. The reliability model of the multi-component degradation system under the cumulative Poisson shock is complex and not easy to be applied to the maintenance model optimization model of the multi-component system. From that, this paper simplified the reliability model of multi-component degradation system under the cumulative Poisson shock. And the simplified reliability function was used as the constraint to improve the optimization model of multi-objective maintenance policy based on the reliability theory so as to facilitate its application in engineering. The feasibility of the simplified reliability model and the correctness of the improved multi-objective maintenance policy was verified by case. The influence of the change of the reliability constraint value on the whole maintenance policy was analyzed.

This paper studies the degradation process of mechanical systems which are composed of multiple sub-systems which have been subjected to continuous wear and random shocks. We have developed a new mathematical model of series systems and established the function curve of each sub-system's degradation over time to evaluate the system's lifetime. Previous research mainly focused on simple non-repairable systems with multiple sub-systems which suffered from independent degradation processes, and held the view that systems can normally work only when the total degradation of each sub-system is less than the threshold level. This new model extends previous research by considering both a non-repairable system and a repairable system subject to multiple degradation processes, and these two types of systems will also fail when the degradation of the overall system is greater than the threshold level. The model is demonstrated on a specific example by means of Monte-Carlo simulation.

The choice of maintenance strategy is a common problem in reliability engineering, and proper maintenance strategies can improve the efficiency of maintenance and save maintenance cost to some extent. There are many papers on the selection and optimization of maintenance strategies. Most of them considered the problem from the system level, and ignored the difference between different components. In fact, the maintenance process of each component is different in many aspects, such as maintenance time and cost. Therefore, it is necessary to analyze the maintenance strategy from the perspective of components. In this paper, the multi-objective optimization model of maintenance cost rate and system availability is established under the constraint of system reliability by mathematical modeling. At the end of this paper, the practicability of the model will be verified by means of numerical analysis.