DYNAMIC RESPONSE OF ROLLER GEAR INDEXING CAM SYSTEM CONSIDERING CLEARANCE AND MOTOR CHARACTERISTIC

The dynamic responses of roller gear indexing cam mechanism are investigated .With applying Lagarange equation and Gear method,motion equations of this mechanism including clearance,motor characteristic,torsion flexibility are developed and solved.The results show that clearance affects primarily the response on turret,and has little effects on the responses on rotary table.At the same time,the velocity fluctuation of motor shaft is not serious for the existence of inertia of reducer,and the high frequency of velocity fluctuation of camshaft is related with the torsion stiffness of shaft and the clearance between pairs.

Correlation of computed tomography findings and lung function in children and adolescents with cystic fibrosis

Background The timely and appropriate monitoring of pulmonary status is of utmost importance for patients with cystic fibrosis(CF).Computed tomography(CT)has been used in clinical and research settings for tracking lung involvement in CF patients.However,as CT delivers a considerable amount of radiation,its sequential use in CF patients remains a concern.The application of CT,therefore,should take into account its potential risks.This review aims to understand whether and to what extent the CT findings correlate with the findings from other monitoring tools in CF lung disease.Data sources PubMed was searched for articles about the correlation of chest CT findings with spirometric indices and with lung clearance index in children and adolescents with CF.The most relevant articles were reviewed and are presented herein.Results Most studies have shown that forced expiratory volume in the first second(FEV,)and other spirometric indices correlate moderately with CT structural lung damage.However,at the individual level,there were patients with FEV,within the normal range and abnormal CT and vice versa.Furthermore,longitudinal studies have indicated that the deterioration of structural lung damage does not occur in parallel with the progression of lung function.Lung clearance index is a better predictor of CT findings.Conclusions In general,the existing studies do not support the use of lung function tests as surrogates of chest CT.