摘要：Autologous bone marrow-derived mesenchymal stem cells(BMSCs)have been shown to promote osteogenesis;however,the effects of allogeneic BMSCs(allo-BMSCs)on bone regeneration remain ***,we explored the bone regeneration promotion effect of allo-BMSCs in 3D-printed autologous bone particle(ABP)***,we concurrently printed scaffolds with polycaprolactone,ABPs,and allo-BMSCs for appropriate support,providing bioactive factors and seed cells to promote *** vitro studies showed that ABP scaffolds promoted allo-BMSC osteogenic *** vivo studies revealed that the implantation of scaffolds loaded with ABPs and allo-BMSCs into canine skull defects for nine months promoted *** experiments suggested that only a small portion of implanted allo-BMSCs survived and differentiated into vascular endothelial cells,chondrocytes,and *** implanted allo-BMSCs released stromal cell-derived factor 1 through paracrine signaling to recruit native BMSCs into the defect,promoting bone *** study contributes to our understanding of allo-BMSCs,providing information relevant to their future application.

摘要：Functional performance variations of products and systems are often used to measure the qualities of products and systems considering the changes in the design parameter values caused by uncertainties.A robust design approach has been developed in this research to minimize the functional performance variations considering the design parameter uncertainties by identifying the boundaries of the functional performance variations through *** this work,a mathematical model is developed to describe the relationships among functional performance,design configurations and parameters,and design parameter uncertainties.A multi-level optimization model is established to identify:(1)The optimal design configuration,(2)the optimal values of design parameters,and(3)the boundaries of functional performance *** analysis considering the impact of parameter uncertainties on functional performance variation boundaries has also been conducted.A case study on the design of a truss system has been *** study results show that the sensitivities of functional performance variation boundaries to the design parameter uncertainties can be reduced significantly using the new robust design approach.

摘要：There is a relatively complex flow state inside the high speed on-off valve,which often produces low pressure area and oil reflux in the high-speed opening and closing process of the spool,causing cavitation and vortex and other *** phenomena will affect the stability of the internal flow field of the plate valve and the flow characteristics of the high speed on-off *** at the problems of small flow rate and instability of internal flow field,a new spool structure was *** flow field models of two-hole and three-hole plate spools with different openings were established,and software ANSYS Workbench was chosen to mesh the *** standard k−εturbulence model was selected for numerical simulation using FLUENT *** pressure distribution and velocity distribution under the same pressure and different opening degree were *** structure and parameters of the optimization model were also *** stability analysis of flow field under different pressure was carried *** results demonstrate that the three-hole spool has a similar flow field change with the two-hole spool,but it does not create a low pressure zone,and the three-hole spool can work stably at 2 MPa or *** method improves the appearance of low pressure area and oil backflow in the process of high speed opening and closing of *** stability of flow field and the flow rate of high speed switch valve are ***,the products designed in this paper are compared with existing hydraulic valve *** results show that the three-hole plate type high speed on-off valve designed in this paper maintains the stability of the internal flow field under the condition of 200 Hz and large opening degree,and realizes the increase of flow rate.

摘要：A kind of surface instability,basin-like depression defect companied by mixed grain structure at the bottom of large-scale valve during electric upsetting process,would significantly influence the microstructures and mechanical properties of *** order to analyze the forming process of the basin-like depression defect,a finite element model for the electric upsetting process of Ni80A superalloy was developed using multi-field and multi-scale coupling analysis ***,a series of parameters loading path schemes for force and current were designed by varying the initial value,peak value and value level,and their effects on basin-like depression and mixed grain structure were simulated and *** is concluded that the changes of heating speed and pressurization speed result in the different flow velocities between the inner and outer layers of billet,thus exerting the basin-like *** results also indicate that these defects can be optimized through the parameter coordination between force and ***,the validity and reliability of the finite element model were verified by physical experiments in electric upsetting process.