Vibration Control of High-speed Cannonball Transport Mechanism Driven by Impact

A method is presented to control the vibration of high-speed cannonball transport mechanism due to the reduction of its weight, which adhere a nonlinear Zn-27Al-1Cu damping alloy layer and a constraint layer partly to the part of mechanism driven by impact. Based on the equivalent viscous damping theory and using curve fitting to describe the rule of the dissipation factor of damping alloy changing with stress, the nonlinear constitutive relation of Zn-27Al-1Cu damping alloy is given. The nonlinear spring damping contact model is adopted to describe the contact force of the clearance joint.Based on the nonlinear finite element contact theory, the outer impact contact force between the mechanism and its working environment is analyzed, and a coupled dynamic model of structural impact and mechanism motion with clearance joint is put forward. A dynamic model is established for the cannonball transport mechanism partly adhering Zn-27Al-1Cu damping alloy layer and constraint layer under complex impact conditions. At last, the feasibility of the method presented is proved by numerical simulation.

青藏铁路可调式通风管路基的数值仿真分析(英文)

Finite Element Method has been used to operate the numerical analysis and comparison between the traditional ventilated embankment and the adjustable ventilated embankment adopted in Qinghai-Tibet Railway construction. The numerical results show that: 1) The adjustable ventilated embankments can prevent the thermal entry from air into ducts during summer from thawing the permafrost beneath the embankments; 2) The cooling effects of the adjustable ventilated embankments on permafrost is much better than the traditional ventilated embankments although two kinds of embankments can generate the thawing bulbs at the beginning of finishing construction; 3) The drop of the mean temperature of permafrost under the adjustable ventilated embankments keeps faster than that of the mean temperature of permafrost under the traditional ventilated embankments. It is clear that the adjustable ventilated embankments can keep the embankment more stable than the traditional ventilated embankments.

青藏铁路通风路基边界条件研究(英文)

In permafrost regions, many methods about active cooling embankment are put forward, one of these representations is ventilated embankment, its cooling effect is the result of the air convection in the duct, and this leads to reducing the annual average ground temperature. The present work in this article is to determine the boundary conditions of the ventilated embankment and natural ground in numerical work. There are several effects which influence boundary conditions, they are: radiation, evaporation, phase change, convection and embankment material etc. Radiation and convection are the main effects in those. We mainly consider sun radiation in this article. The added-surface effect in ventilated embankment lowers its temperature, so the temperature on the wall of the ventilated embankment is different from the temperature in atmosphere. There are two methods in determining the surface temperature, experimental method and experiential method. Detailed research is discussed in the article.

GCR-Net:3D Graph convolution-based residual network for robust reconstruction in cerenkov luminescence tomography

Cerenkov Luminescence Tomography(CLT)is a novel and potential imaging modality which can display the three-dimensional distribution of radioactive probes.However,due to severe ill-posed inverse problem,obtaining accurate reconstruction results is still a challenge for traditional model-based methods.The recently emerged deep learning-based methods can directly learn the mapping relation between the surface photon intensity and the distribution of the radioactive source,which effectively improves the performance of CLT reconstruction.However,the previously proposed deep learning-based methods cannot work well when the order of input is disarranged.In this paper,a novel 3D graph convolution-based residual network,GCR-Net,is proposed,which can obtain a robust and accurate reconstruction result from the photon intensity of the surface.Additionally,it is proved that the network is insensitive to the order of input.The performance of this method was evaluated with numerical simulations and in vivo experiments.The results demonstrated that compared with the existing methods,the proposed method can achieve efficient and accurate reconstruction in localization and shape recovery by utilizing threedimensional information.