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According to the requirement of projectile long-travel and heavy-load automatic loading, a chain rammer with compact structure and forced ramming is designed. Based on virtual prototype technology, the virtual prototype model of the chain rammer is built. Adding driving according to the driving motor output characteristic, the dynamics simulation of the work process of rammer is carried out and the stability of chain drive ramming is analyzed. The results of simulation show that the projectile is stable in the forced ramming travel, the projectile at the end of the ramming can overcome the heavy load and accurately pushed into the chamber at a certain speed, the values can meet the requirements of automatic loading, and it is proved that the design is rationality.

In this study, numerical investigations of the tip clearance flow characteristics of a pumpjet propulsor based on Computational Fluid Dynamics (CFD) method have been presented. The Zwart-Gerber-Belamri (Z-G-B) cavitation model based on Reynolds Averaged Navier–Stokes (RANS) method is employed. The structured gird is applied. The formation and development of the tip clearance flows has been investigated and presented. The structure of the tip leakage vortex has been shown. The radial distributions of different velocity components with different Span along the axial direction have been carried out to present the influence of the tip clearance flow on the main flow. In addition, the influences of the tip clearance size on the pumpjet propulsor performance, including the impact on the velocity flow fields and the cavitation characteristic, have been presented. Keywords: Pumpjet propulsor, Numerical investigation, Tip clearance characteristic, Tip leakage vortex, Tip clearance size

Blockchain -- a distributed and public database of transactions -- has become a platform for decentralized applications. Despite its increasing popularity, blockchain technology faces a scalability problem: the throughput does not scale with the increasing network size. Thus, in this paper, we propose a scalable blockchain protocol to solve the scalability problem. The proposed method was designed based on a proof of stake (PoS) consensus protocol and a sharding protocol. Instead of transactions being processed by the whole network, the sharding protocol is employed to divide unconfirmed transactions into transaction shards and to divide the network into network shards. The network shards process the transaction shards in parallel to produce middle blocks. Middle blocks are then combined into a final BLOCK in a timestamp recorded on the blockchain. Experiments were performed in a simulation network consisting of 100 Amazon EC2 instances. The latency of the proposed method was approximately 27 s and the maximum throughput achieved was 36 transactions per second for a network containing 100 nodes. The results of the experiments indicate that the throughput of the proposed protocol increases with the network size. This confirms the scalability of the proposed protocol. [ABSTRACT FROM AUTHOR]