The turbulent boundary layer control on NACA 0012 airfoil with Mach number ranging from 0.3 to 0.5 by a spanwise array of dielectric barrier discharge(DBD)plasma actuators by hot-film sensor technology is investigated.Due to temperature change mainly caused through heat produced along with plasma will lead to measurement error of shear stress measured by hot-film sensor,the correction method that takes account of the change measured by another sensor is used and works well.In order to achieve the value of shear stress change,we combine computational fluid dynamics computation with experiment to calibrate the hot-film sensor.To test the stability of the hot-film sensor,seven repeated measurements of shear stress at Ma = 0.3 are conducted and show that confidence interval of hot-film sensor measurement is from-0.18 to 0.18 Pa and the root mean square is 0.11 Pa giving a relative error 0.5%over all Mach numbers in this experiment.The research on the turbulent boundary layer control with DBD plasma actuators demonstrates that the control makes shear stress increase by about 6%over the three Mach numbers,which is thought to be reliable through comparing it with the relative error 0.5%,and the value is hardly affected by burst frequency and excitation voltage. 相似文献
Orthodontic tooth movement is triggered by orthodontic force loading on the periodontal ligament and is
achieved by alveolar bone remodeling, which is regulated by intimate crosstalk between osteoclastogenesis and
osteoblast differentiation. Whether the communication between osteoclasts and osteoblasts is influenced by
orthodontic compression stress requires further clarification. In this study, osteoclasts were differentiated for 10 days.
On day 4 of differentiation, the number of pre-osteoclasts peaked, as determined by the increased expression of
RANK and the number of multinucleated cells. After 24 h of compression stress loading, on day 4, the number of
osteoclasts increased, and the optimal magnitude of stress to promote osteoclastogenesis was determined as 1 g/cm2.
Moreover, the results of RNA-sequencing analysis showed that the miRNA expression profile changed markedly after
compression loading and that many of the altered miRNAs were associated with cell communication functions. A
series of indirect co-culture experiments showed an inhibitory effect of osteoclasts on osteoblast differentiation,
especially after compression. Next, we added osteoclast-derived exosomes to hPDLSCs during osteoblast
differentiation. Exosomes derived from osteoclasts under compression (cEXO) showed a greater inhibitory effect on
osteoblast differentiation, compared to exosomes from osteoclasts without compression (EXO). Therefore, we
analyzed differentially expressed miRNAs associated with bone development functions in exosomes: miR-223-5p and
miR-181a-5p were downregulated, whereas miR-133a-3p, miR-203a-3p, miR-106a-5p, and miR-331-3p were
upregulated; these altered expressions may explain the enhanced inhibitory effect of compression stress. 相似文献
Coal mining can dramatically change hydrogeological conditions and induce serious environmental problems. Fifty groundwater samples were collected from the main aquifers in the Yuaner coal mine (Anhui Province, China). The results show that the main hydrogeochemical processes in the mine include dissolution, precipitation, pyrite oxidation, desulfurization, and cation exchange. The Neogene porous aquifer is affected by groundwater flow conditions; its main hydrogeochemical processes are dissolution of carbonate minerals and gypsum, and cation exchange. The Permian coal measure’s fractured sandstone aquifer was confirmed to be controlled by the region’s geological structure; its main hydrogeochemical processes are desulfurization and cation exchange. The Carboniferous Taiyuan limestone aquifer was determined by both groundwater flow conditions and regional geological structure; its main hydrogeochemical processes are dissolution of carbonate minerals and gypsum, pyrite oxidation, and cation exchange. Additionally, hydrogeochemical inverse modeling of the groundwater flow path confirm the hydrochemistry results and principal component analysis.