针对深度残差网络无法在噪声环境下精确诊断的问题,提出了一种基于直接快速迭代滤波(direct fast iterative filtering,DFIF)和自适应深度残差网络(adaptive deep residual network,AResNet)的方法,并将其应用于噪声环境下旋转机械的故...针对深度残差网络无法在噪声环境下精确诊断的问题,提出了一种基于直接快速迭代滤波(direct fast iterative filtering,DFIF)和自适应深度残差网络(adaptive deep residual network,AResNet)的方法,并将其应用于噪声环境下旋转机械的故障诊断中。首先,在采集的振动信号中增加不同强度的噪声,再经DFIF分解得到若干个本征模态函数(intrinsic mode function,IMF)分量,选取综合评价指标值最小的IMF分量作为输入样本;其次,提出了自适应残差单元(adaptive residual building unit,ARBU),ARBU通过计算各个通道的最优系数,自适应地放大故障敏感特征和抑制无关特征,能够更好地替代传统的残差单元;最后,基于ARBU构造AResNet,输入样本经过AResNet得到故障诊断结果。将所提方法应用于噪声背景下旋转机械的故障诊断中,在两个不同数据集中进行了验证。研究结果表明,与现有方法相比,所提方法具有更高的噪声鲁棒性、稳定性和更优的计算效率,且能够更好地解决旋转机械在噪声背景下故障特征难以有效挖掘的问题。展开更多
In order to detecting and tracking along the weld seam with rotating arc sensor in underwater welding,the highpressure water environment rotating arc welding hardware platform is established and welding experiments us...In order to detecting and tracking along the weld seam with rotating arc sensor in underwater welding,the highpressure water environment rotating arc welding hardware platform is established and welding experiments using rotating arc sensor is done. Different radius of rotating arc sensor is used. And the corresponding welding current and voltage is obtained,which is compared with the results of rotating arc sensor short-circuit process simulation model under high-pressure water environment established in this article. The results show that under high-pressure water environment,rotating arc radius should be optimized,otherwise the short-circuit-arcing cycle will transit to a short-circuit-arcing-abruption cycle,making the welding quality poor. At last the critical radius between the short-circuit-arcing cycle and short-circuit-arcing-abruption cycle under high-pressure water environment is obtained.展开更多
In this problem,simultaneous effects of Joule and viscous dissipation in three-dimensional flow of nanoliquid have been addressed in slip flow regime under time dependent rotational oscillations.Silver nanoparticles a...In this problem,simultaneous effects of Joule and viscous dissipation in three-dimensional flow of nanoliquid have been addressed in slip flow regime under time dependent rotational oscillations.Silver nanoparticles are submerged in the base fluid(water)due to their chemical and biological features.To increment the novelty,effects of cubic autocatalysis chemical reactions and radiative heat transfer have been incorporated in the related boundary layer equations.Dimensionless partial differential system is solved by employing the proposed implicit finite difference approach.Convergence conditions and stability criteria are obtained to ensure the convergence and accuracy of solutions.A comparative analysis is proposed for no-slip nanofluid flow(NSNF)and slip nanofluid flow(SNF).Variations in skin-friction coefficients,Sherwood and Nusselt numbers against physical parameters are tabulated.It is investigated that velocity slip and temperature jump significantly control drag forces and rate of heat transfer.展开更多
To improve the durability of underwater rotating products,the corrosion characteristics in harsh marine environment were evaluated through various electrochemical experiments on the Al2O3-3TiO2 and CoNiCrAlY coating l...To improve the durability of underwater rotating products,the corrosion characteristics in harsh marine environment were evaluated through various electrochemical experiments on the Al2O3-3TiO2 and CoNiCrAlY coating layers by atmospheric pressure plasma spray coating process.By evaluating the corrosion resistance of these materials,their applicability to environmentally friendly power generation equipment such as blades of tidal current turbines was examined.According to the Tafel analysis for micro-areas including the coating layer,the coating/metal interlayer and the base metal,the Al2O3-3TiO2 coating layer and the CoNiCrAlY coating layer show markedly lower corrosion current density than the base metal.The corrosion current density of the CoNiCrAlY coating layer (9.75316×10-8A/cm2) is about 1.6 times more than that of the Al2O3-3TiO2 coating layer (6.13139×10-8A/cm2).展开更多
文摘针对深度残差网络无法在噪声环境下精确诊断的问题,提出了一种基于直接快速迭代滤波(direct fast iterative filtering,DFIF)和自适应深度残差网络(adaptive deep residual network,AResNet)的方法,并将其应用于噪声环境下旋转机械的故障诊断中。首先,在采集的振动信号中增加不同强度的噪声,再经DFIF分解得到若干个本征模态函数(intrinsic mode function,IMF)分量,选取综合评价指标值最小的IMF分量作为输入样本;其次,提出了自适应残差单元(adaptive residual building unit,ARBU),ARBU通过计算各个通道的最优系数,自适应地放大故障敏感特征和抑制无关特征,能够更好地替代传统的残差单元;最后,基于ARBU构造AResNet,输入样本经过AResNet得到故障诊断结果。将所提方法应用于噪声背景下旋转机械的故障诊断中,在两个不同数据集中进行了验证。研究结果表明,与现有方法相比,所提方法具有更高的噪声鲁棒性、稳定性和更优的计算效率,且能够更好地解决旋转机械在噪声背景下故障特征难以有效挖掘的问题。
基金supported by the National Natural Science Foundation of China(Grant No.51665016)founded by the China Scholarship Council(Grant No.201508360113)
文摘In order to detecting and tracking along the weld seam with rotating arc sensor in underwater welding,the highpressure water environment rotating arc welding hardware platform is established and welding experiments using rotating arc sensor is done. Different radius of rotating arc sensor is used. And the corresponding welding current and voltage is obtained,which is compared with the results of rotating arc sensor short-circuit process simulation model under high-pressure water environment established in this article. The results show that under high-pressure water environment,rotating arc radius should be optimized,otherwise the short-circuit-arcing cycle will transit to a short-circuit-arcing-abruption cycle,making the welding quality poor. At last the critical radius between the short-circuit-arcing cycle and short-circuit-arcing-abruption cycle under high-pressure water environment is obtained.
文摘In this problem,simultaneous effects of Joule and viscous dissipation in three-dimensional flow of nanoliquid have been addressed in slip flow regime under time dependent rotational oscillations.Silver nanoparticles are submerged in the base fluid(water)due to their chemical and biological features.To increment the novelty,effects of cubic autocatalysis chemical reactions and radiative heat transfer have been incorporated in the related boundary layer equations.Dimensionless partial differential system is solved by employing the proposed implicit finite difference approach.Convergence conditions and stability criteria are obtained to ensure the convergence and accuracy of solutions.A comparative analysis is proposed for no-slip nanofluid flow(NSNF)and slip nanofluid flow(SNF).Variations in skin-friction coefficients,Sherwood and Nusselt numbers against physical parameters are tabulated.It is investigated that velocity slip and temperature jump significantly control drag forces and rate of heat transfer.
基金Project supported by the Ministry of Education,Science Technology(MEST)Korea Industrial Technology Foundation(KOTEF)through the Human Resource Training Project for Regional Innovation
文摘To improve the durability of underwater rotating products,the corrosion characteristics in harsh marine environment were evaluated through various electrochemical experiments on the Al2O3-3TiO2 and CoNiCrAlY coating layers by atmospheric pressure plasma spray coating process.By evaluating the corrosion resistance of these materials,their applicability to environmentally friendly power generation equipment such as blades of tidal current turbines was examined.According to the Tafel analysis for micro-areas including the coating layer,the coating/metal interlayer and the base metal,the Al2O3-3TiO2 coating layer and the CoNiCrAlY coating layer show markedly lower corrosion current density than the base metal.The corrosion current density of the CoNiCrAlY coating layer (9.75316×10-8A/cm2) is about 1.6 times more than that of the Al2O3-3TiO2 coating layer (6.13139×10-8A/cm2).
