Study on Wheel and Workpiece Position Error Influence on Surface Shape Accuracy during Ceramic Ball Grinding

The reasons for bringing surface accuracy error in ultra-precision grinding ceramic ball joint were analyzed,and the influences wheel position error and shaft run-out error on the ball joint surface accuracy were discussed.Through establishing three-dimensional grinding model,the mathematical relationship between the position error and surface accuracy was derived,and the distance from any point on spherical surface to the ideal center was calculated when position error existed,and a precise surface shape was got,and theoretical support was provided to improve the surface accuracy during the grinding process.Using self-developed ultraprecision grinding machine to do the ceramic ball grinding experiment,the surface accuracy PV value of ceramic spherical joint is 4.8μm.

Impact of COVID-19 pandemic on radiology education,training,and practice:A narrative review

Radiology education and training is of paramount clinical importance given the prominence of medical imaging utilization in effective clinical practice.The incorporation of basic radiology in the medical curriculum has continued to evolve,focusing on teaching image interpretation skills,the appropriate ordering of radiological investigations,judicious use of ionizing radiation,and providing exposure to interventional radiology.Advancements in radiology have been driven by the digital revolution,which has,in turn,had a positive impact on radiology education and training.Upon the advent of the corona virus disease 2019(COVID-19)pandemic,many training institutions and hospitals adhered to directives which advised rescheduling of non-urgent outpatient appointments.This inevitably impacted the workflow of the radiology department,which resulted in the reduction of clinical in-person case reviews and consultations,as well as in-person teaching sessions.Several medical schools and research centers completely suspended face-to-face academic activity.This led to challenges for medical teachers to complete the radiology syllabus while ensuring that teaching activities continued safely and effectively.As a result,online teaching platforms have virtually replaced didactic face-to-face lectures.Radiology educators also sought other strategies to incorporate interactive teaching sessions while adopting the e-learning approach,as they were cognizant of the limitations that this may have on students’clinical expertise.Migration to online methods to review live cases,journal clubs,simulation-based training,clinical interaction,and radiology examination protocolling are a few examples of successfully addressing the limitations in reduced clinical exposure.In this review paper,we discuss(1)The impact of the COVID-19 pandemic on radiology education,training,and practice;(2)Challenges and strategies involved in delivering online radiology education for undergraduates and postgraduates during the COVID-19 pandemic;and(3)Difference between the implementation of radiology education during the COVID-19 pandemic and pre-COVID-19 era.