Optimization of the Structural Parameters of a Plastic Centrifugal Pump in the Framework of a Flow Field Analysis

In order to determine the optimal structural parameters of a plastic centrifugal pump in the framework of an orthogonal-experiment approach,a numerical study of the related flow field has been performed using CFX.The thickness S,outlet angleβ2,inlet angleβ1,wrap angle,and inlet diameter D1 of the splitter blades have been considered as the variable factors,using the shaft power and efficiency of the pump as evaluation indices.Through a parametric analysis,the relative importance of the influence of each structural parameter on each evaluation index has been obtained,leading to the following combinations:β119°,β235°,S 2 mm,wrap angle 154°,and D185 mm(corresponding to the maximum efficiency of 75.48%);β119°,β220°,S 6 mm,wrap angle 158°,and D181 mm(corresponding to the minimum shaft power of 75.48%).Moreover,the grey correlation method has been applied to re-optimize the shaft power and efficiency of the pump,leading to the following optimal combination:β119°,β215°,S 4 mm,D181 mm,and wrap angle 152°(corresponding to the maximum efficiency of 71.81%and minimum shaft power of 2.187 kW).

Improved Design of a Hydraulically Expanded Overhead Cylinder for an Automotive Torsion Beam

The design of hydro-bulge molds,able to provide hollow parts with special-shaped cross-sections,is still a pretty complicated task(especially for what concerns the design of the related hydraulic system and its“synchronization”).In the present work,this task is addressed through the introduction of a new type of overhead cylinder hydraulic synchronization system,able to correct automatically any deviation from the optimal process.Using the AMESim software,the displacement synchronization curve of the piston rods of the two cylinders is obtained and it is verified that the system is able to implement an automatic deviation correction function by adjusting the bidirectional servo valve.A mathematical model for the synchronization system is presented,and the transfer function of the closed-loop control system is determined accordingly.The results show that the system response is generated at about 0.1∼0.2 s with the system reaching an equilibrium state at about 0.2 s.

Associations of sleeping patterns and isotemporal substitution of other behavior with the prevalence of CKD in Chinese adults

Studies have found a U-shaped relationship between sleep duration and chronic kidney disease(CKD)risk,but limited research evaluated the association of reallocating excessive sleep to other behavior with CKD.We included 104538 participants from the nationwide cohort of the Risk Evaluation of Cancers in Chinese Diabetic Individuals:A Longitudinal Study,with self-reported time of daily-life behavior.Using isotemporal substitution models,we found that substituting 1 h of sleeping with sitting,walking,or moderate-to-vigorous physical activity was associated with a lower CKD prevalence.Leisure-time physical activity displacement was associated with a greater prevalence reduction than occupational physical activity in working population.In stratified analysis,a lower CKD prevalence related to substitution toward physical activity was found in long sleepers.More pronounced correlations were observed in long sleepers with diabetes than in those with prediabetes,and they benefited from other behavior substitutions toward a more active way.The U-shaped association between sleep duration and CKD prevalence implied the potential effects of insufficient and excessive sleep on the kidneys,in which the pernicious link with oversleep could be reversed by time reallocation to physical activity.The divergence in the predicted effect on CKD following time reallocation to behavior of different domains and intensities and in subpopulations with diverse metabolic statuses underlined the importance of optimizing sleeping patterns and adjusting integral behavioral composition.