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The performance of cylinder liner-piston ring (CLPR) affects the efficiency of marine engine greatly. An experimental study on textured CLPR was conducted to seek insight into the operation reliability of CLPR. Three types of surface texture, groove texture on cylinder liner, dimple texture on piston ring, and co-texture on both sides, were processed. A series of tests were then carried out on an engine tester. Three characterization parameters, contact resistance, worn surface topography on cylinder liner, and cylinder pressure were used to describe the CLPR tribological properties and air tightness. The results showed that the three textures all improved tribological properties. Compared to the non-textured surface, the contact resistance of the three textures increased 30.7%, 71.7% and 98.4% on average. The wear resistance of dimple texture was weaker than that of groove texture. Air tightness was closely related to oil film pressure. At dead centre, the cylinder pressure of the three textures respectively was optimized by 4.6 kPa, 7.8 kPa and 12.3 kPa averagely. The co-texture was shown to combine the advantages of groove texture with the advantages of dimple texture, which provided the surface with improved oil film distribution and more efficient debris trapping, resulting in the optimum tribological properties and air tightness among the three textures.

Asymmetric casings filled with explosive have attracted increasing attention in the defence technology (e.g. innovative warhead design) and improvised explosive devices (IEDs) protection. As a typical asymmetric casing, D-shaped casing has been used in deformable aimable warhead, deployable aimable warhead as well as warhead in hypersonic weapons. To assist the design of asymmetric warhead, this work examined the velocity distribution of fragments from the bottom part of the D-shaped casing with different shell thickness. The fragment velocity distributions of the D-shaped casings with different shell thickness were numerically analyzed based on the SPH method. Numerical and theoretical analysis showed that there are opportunities to do optimization of shell thickness of D-shaped casings to maximum the utilization of the energy released by explosive. The findings herein could serve as a reference for further investigations on the fragment velocity distribution of D-shaped casings and provide a foundation for asymmetric warhead design.

Aiming at the extraordinary dependency on manual experience during the process of sewage treatment, it is required to explore intelligent prediction mechanism for sewage quality. Due to the fact that convolutional neural network (CNN) has some unique advantages for fast prediction, this paper proposes a convolutional neural network-based prediction mechanism for sewage treatment (CPST). It contains two mains parts respectively named learning process and training process. A group of experiments are managed to evaluate the efficiency of the proposed CPST, and the results demonstrate that CPST obtain the lower prediction error compared with baselines.

The digital metering system has certain advantages in comparison with traditional metering systems in principle and performance, but the engineering application time is short. At present, there is a lack of research on the testability of digital metering systems. Reasonable determination of testability index allocation is an important issue to be addressed in the test requirements of digital systems. In this paper, the fuzzy comprehensive evaluation method is used to distribute the test index of smart substation system, which makes it more realistic. It can reflect the whole process of test distribution objectively and truly. Finally, combining with the communication network subsystem of substation, the proposed method is used to verify the testability distribution method, which shows that the method is feasible and effective.