Andrew Richard Kennedy

Current fault diagnosis methods for rotor-bearing systems are mostly based on analyzing the vibration signals collected at steady rotating speeds. In those methods, the data collected under one operating condition cannot be accurately used for diagnosis under a different condition. Moreover, in vibration monitoring, installing the necessary sensors will affect the equipment structure and hence the vibration response itself. This article proposes a new method based on two-stage parameter transfer and infrared thermal images for fault diagnosis of rotor-bearing systems under variable rotating speeds. The method of parameter transfer enables the use of data (or parameters) acquired under one operating condition (called the source domain) to be extended for use in a different operating condition (called the target domain). First, scaled exponential linear unit (SELU) and modified stochastic gradient descent (MSGD) are used to construct an enhanced convolutional neural network (ECNN). Second, a stacked convolutional auto-encoder (CAE) trained based on unlabeled source-domain thermal images is employed to initialize a source-domain ECNN. Third, model parameters from the pre-trained source-domain ECNN are transferred to the target-domain ECNN to adapt to the characteristics of the target domain. The collected thermal images for a rotor-bearing system under variable speeds are used to test the transfer diagnosis performance of the proposed method. The experimental results demonstrate the performance improvement and the advantages of the proposed method.

Phosphate glasses (PBG) are ideal materials for regenerative medicine strategies since their composition, degradation rates and ion release profiles can easily be controlled. Strontium has previously been found to simultaneously affect bone resorption and deposition. Therefore, by combining the inherent properties of resorbable PBG and therapeutic activity of strontium, these glasses could be used as a delivery device of therapeutic factors for the treatment of orthopaedic diseases such as osteoporosis. This study shows the cytocompatibility and osteogenic potential of phosphate based glasses where CaO is gradually replaced by SrO in the near invert glass system 40P₂O₅·(16‐x)CaO·20Na₂O·24MgO·xSrO (x= 0, 4, 8, 12 and 16 mol %). Direct seeding of MG63 cells onto glass discs showed no significant difference in cell metabolic activity and DNA amount measurement across the different formulations studied. Cell attachment and spreading was confirmed via SEM imaging at days 3 and 14. Alkaline phosphatase (ALP) activity was similarly maintained across the glass compositions. Follow‐on studies explored the effect of each glass composition in microsphere conformation (size: 63‐125μm) on hMSCs in 3D cultures and analysis of cell metabolic activity and ALP activity showed no significant differences at day14 over the compositional range investigated, in line with the observations from MG63 cell culture studies. ESEM and live cell imaging at day14 of hMSCs seeded on the microspheres showed cell attachment and colonisation of the microsphere surfaces, confirming these formulations as promising candidates for regenerative medicine strategies addressing compromised musculoskeletal/orthopaedic diseases.

Detailed structural characterization and experimental measurement of airflow across open‐celled aluminum foam structures with near‐spherical cells varying in pore sizes and interstices are presented herein. The aluminum foam structures were produced by infiltrating liquid aluminum into convergent gaps created by packed beds of near‐spherical hydrosoft salt beds varying in particle sizes, packing densities, and infiltration pressures. A quantitative assessment of the unit pressure drops developed across these structures show that viscous and inertial terms of these structures were observed to greatly depend on the shape and structural macroscopic parameters of the porous medium. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1355–1364, 2019