Dynamic Distribution Adaptation Based Transfer Network for Cross Domain Bearing Fault Diagnosis

In machinery fault diagnosis,labeled data are always difficult or even impossible to obtain.Transfer learning can leverage related fault diagnosis knowledge from fully labeled source domain to enhance the fault diagnosis performance in sparsely labeled or unlabeled target domain,which has been widely used for cross domain fault diagnosis.However,existing methods focus on either marginal distribution adaptation(MDA)or conditional distribution adaptation(CDA).In practice,marginal and conditional distributions discrepancies both have significant but different influences on the domain divergence.In this paper,a dynamic distribution adaptation based transfer network(DDATN)is proposed for cross domain bearing fault diagnosis.DDATN utilizes the proposed instance-weighted dynamic maximum mean discrepancy(IDMMD)for dynamic distribution adaptation(DDA),which can dynamically estimate the influences of marginal and conditional distribution and adapt target domain with source domain.The experimental evaluation on cross domain bearing fault diagnosis demonstrates that DDATN can outperformance the state-of-the-art cross domain fault diagnosis methods.

Experimental study on the effect of flexible joints of a deep-buried tunnel across an active fault under high in-situ stress conditions

During dislocation,a tunnel crossing the active fault will be damaged to varying degrees due to its permanent stratum displacement.Most previous studies did not consider the influence of the tunnel’s deep burial and the high in-situ stress,so the results were not entirely practical.In this paper,the necessity of solving the anti-dislocation problem of deep-buried tunnels is systemically discussed.Through the model test of tunnels across active faults,the differences in failures between deep-buried tunnels and shallow-buried tunnels were compared,and the dislocation test of deep-buried segmental tunnels was carried out to analyze the external stress change,lining strain,and failure mode of tunnels.The results are as follows.(1)The overall deformation of deep-buried and shallow-buried tunnels is both Sshaped.The failure mode of deep-buried tunnels is primarily characterized by shear and tensile failure,resulting in significant compressive deformation and a larger damaged area.In contrast,shallow-buried tunnels mainly experience shear failure,with the tunnel being sheared apart at the fault crossing,leading to more severe damage.(2)After the segmental structure design of the deep-buried tunnel,the‘‘S”deformation pattern is transformed into a‘‘ladder”pattern,and the strain of the tunnel and the peak stress of the external rock mass are reduced;therefore,damages are significantly mitigated.(3)Through the analysis of the distribution of cracks in the tunnel lining,it is found that the tunnel without a segmental structure design has suffered from penetrating failure and that cracks affect the entire lining.The cracks in a flexible segmental tunnel affect about 66.6%of the entire length of the tunnel,and cracks in a tunnel with a short segmental tunnel only affect about 33.3%of the entire length of the tunnel.Therefore,a deep-buried tunnel with a short segmental tunnel can yield a better anti-dislocation effect.(4)By comparing the shallow-buried segmental tunnel in previous studies,it is concluded that the shallow-buried segmental tunnel will also suffer from deformation outside the fault zone,while the damages to the deep-buried segmental tunnel are concentrated in the fault zone,so the anti-dislocation protection measures of the deep-buried tunnel shall be provided mainly in the fault zone.The results of the above study can provide theoretical reference and technical support for the design and reinforcement measures of the tunnel crossing active fault under high in-situ stress conditions.

Centrifuge modeling of PGD response of buried pipe

A new centrifuge based method for determining the response of continuous buried pipe to PGD is presented. The physical characteristics of the RPI's 100 g-ton geotechnical centrifuge and the current lifeline experiment split-box are described: The split-box contains the model pipeline and surrounding soil and is manufactured such that half can be offset, in flight, simulating PGD. In addition, governing similitude relations which allow one to determine the physical characteristics, (diameter, wall thickness and material modulus of elasticity) of the model pipeline are presented. Finally, recorded strains induced in two buried pipes with prototype diameters of 0.63 m and 0.95 m (24 and 36 inch) subject to 0.6 and 2.0 meters (2 and 6 feet) of full scale fault offsets and presented and compared to corresponding FE results.

Analysis of Fixed Site Leveling Abnormality at Hutubi Seismic Station

On the basis of the comparison data of Stage II of the tunnel site leveling project at Hutubi seismic station and the observation data of Stage IV of the site cross fault leveling project at Hutubi and the level observation data from the cross fault survey lines in Dafeng from 1987 to 2012,this paper analyses the variation rates of the tunnel site leveling observation results and the difference of annual change rates of the cross fault level observations at Hongshan seismic station in Hutubi. This paper concludes the reliability of the Ni004 optical level used by the station and puts forward a proposal based on the analysis. This paper also explores the cross fault leveling research on the ground deformation in the region concerned on the basis of the historical observation of the cross fault level at Dafeng and the comparison results of the tunnel site leveling observation in Hutubi.