The evolution of ablative Rayleigh–Taylor instability(ARTI)induced by single-mode stationary and time-varying perturbations in heat flux is studied numerically in two dimensions.Compared with the stationary case,time...The evolution of ablative Rayleigh–Taylor instability(ARTI)induced by single-mode stationary and time-varying perturbations in heat flux is studied numerically in two dimensions.Compared with the stationary case,time-varying heat-flux perturbation mitigates ARTI growth because of the enhanced thermal smoothing induced by the wave-like traveling heat flux.A resonance is found to form when the phase velocity of the heat-flux perturbation matches the average sound speed in the ablation region.In the resonant regime,the coherent density and temperature fluctuations enhance the electron thermal conduction in the ablation region and lead to larger ablation pressure and effective acceleration,which consequently yield higher linear growth rate and saturated bubble velocity.The enhanced effective acceleration offers increased implosion velocity but can also compromise the integrity of inertial confinement fusion shells by causing faster ARTI growth.展开更多
<strong>Objective: </strong>The quantum dots are the useful materials in microelectronics and biomedical research. However its toxicity has to be considered. We studied the effect of cell inhibition with Z...<strong>Objective: </strong>The quantum dots are the useful materials in microelectronics and biomedical research. However its toxicity has to be considered. We studied the effect of cell inhibition with ZnS core quantum dots and CdTe quantum dots modified with Thioglycolic acid or Cysteine functional group (TGA-CdTe, TGA-CdTe/ZnS, Cys-CdTe, Cys-CdTe/ZnS) on Caco-2 cell proliferation. <strong>Methods</strong>: We studied the effect of cell inhibition with ZnS core QDs and CdTe QDs modified with functional group on Caco-2 cell proliferation by MTT assay at 0, 12.5, 25, 50, 100 μg/ml and 6, 24, 48 h. <strong>Result:</strong> Our results showed that all QDs have inhibited cell proliferation and reached maximum 79.21%. The inhibition rate of Cys-modified QDs increased with the increase of concentration and reached maximum 66.72%. The inhibition rate of TGA-modified QDs increased with the increase of time. The ratios of Cys-modified to TGA-modified were less than 1 at all concentrations and three exposure times (P ≤ 0.01). The average ratios of Cys-CdTe/ZnS to Cys-CdTe reached 1.11 only for 48 h (P ≤ 0.05). The ratios of TGA-CdTe/ZnS to TGA-CdTe were closed to 1 at all concentrations and exposure times. <strong>Conclusion:</strong> The regularity of QDs modified with functional group is that inhibition of TGA-modified higher than Cys-modified. Inhibition exhibited dose-dependent for Cys-modified while exhibited time-dependent for TGA-modified. The regularity of CdTe-QDs with ZnS or not is that the inhibition of Cys-CdTe/ZnS was higher than Cys-CdTe while TGA-CdTe/ZnS and TGA-CdTe were consistent.展开更多
<i><span style="font-family:Verdana;">Aconitum kusnezoffii</span></i><span style="font-family:Verdana;"></span><span style="font-family:;" "=&q...<i><span style="font-family:Verdana;">Aconitum kusnezoffii</span></i><span style="font-family:Verdana;"></span><span style="font-family:;" "=""><span style="font-family:Verdana;"> used as an analgesic and anti-inflammatory. It is often used not only in Mongolian medicine but also in traditional Chinese medicine. However, there are few studies on its impact of inflammatory cytokines. This study explored the effects of </span><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">Aconitum kusnezoffii</span></i> <i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"></span></i></span><span style="font-family:Verdana;"> used human colon cancer (Caco-2) cells. Cytotoxicity was assessed by measuring effects on expression of IL-1</span><i><span style="font-family:Verdana;"><span style="white-space:nowrap;">β</span></span></i><span style="font-family:Verdana;">, IL-6, IL-8, and TNF-</span><i><span style="font-family:Verdana;"><span style="white-space:nowrap;">α</span></span></i><span style="font-family:Verdana;"> used enzyme-linked immun</span><span style="font-family:Verdana;">o</span><span style="font-family:;" "=""><span style="font-family:Verdana;">sorbent assay (ELISA). </span><span><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">In vitro</span></i><span style="font-family:Verdana;"></span></i></span></span><span style="font-family:Verdana;"> study demonstrated that incubation of Caco-2 cells with some kinds of</span><i> </i><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">Aconitum kusnezoffii</span></i><span style="font-family:Verdana;"></span></i><span style="font-family:Verdana;"> at some concentrations inhibit secretion of TNF-</span><i><span style="font-family:Verdana;"><span style="white-space:nowrap;">α</span></span></i><span style="font-family:Verdana;"> and FAXIU </span><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">ACONITUM</span></i> <i><span style="font-family:Verdana;">KUSNEZOFFII</span></i><span style="font-family:Verdana;"></span></i><span style="font-family:Verdana;"> could inhibit the secretion of IL-1</span><i><span style="font-family:Verdana;"><span style="white-space:nowrap;">β</span></span></i><span style="font-family:Verdana;">. While IL-6 and IL-8 levels were unaffected after 24 h of treatment with </span><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">Aconitum kusnezoffii</span></i><span style="font-family:Verdana;"><i></i></span><i><span style="font-family:Verdana;">, </span></i></i><span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span><span style="font-family:Verdana;">qujian </span><i><i><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">Aconitum kusnezoffii</span></i><span style="font-family:Verdana;"><i></i></span><i><span style="font-family:Verdana;">, </span></i></i></i></i><span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span><span style="font-family:Verdana;">faxiu </span><i><i><i><i><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">Aconitum kusnezoffii</span></i><span style="font-family:Verdana;"></span></i><span style="font-family:Verdana;">.</span></i></i></i></i>展开更多
Chronic obstructive pulmonary disease </span><span style="font-family:""><span style="font-family:Verdana;">(COPD) is a major chronic respiratory disease worldwide. Inflammat...Chronic obstructive pulmonary disease </span><span style="font-family:""><span style="font-family:Verdana;">(COPD) is a major chronic respiratory disease worldwide. Inflammatory cells reflect the </span><span style="font-family:Verdana;">inflammatory situation both in peripheral blood and induced sputum. </span></span><span style="font-family:""><span style="font-family:Verdana;">Their correlation has not been reported. </span><span style="font-family:Verdana;">The correlation between neutrophils (Neu), eosinophils (Eos), and lymphocyte (Lym) in induced sputum and that in peripheral blood of COPD </span><span style="font-family:Verdana;">patients was evaluated </span><span><span style="font-family:Verdana;">to explore the </span><span style="font-family:Verdana;">consistency of inflammatory cells in peripheral blood and induced sputum. Peripheral blood and induced sputum were collected from 437 </span><span style="font-family:Verdana;">patients with acute exacerbation of COPD</span></span><span style="font-family:Verdana;"> (AECOPD) who were hospitalized in the Department of respiratory and critical care medicine, Inner Mongolia People’s Hospital. </span><span style="font-family:Verdana;">The correlation analysis was performed by Spearman correlation analysis. </span><span style="font-family:Verdana;">The r</span><span style="font-family:Verdana;">atios of Neu, Eos, and Lym in induced sputum were (79.15 ± 22.60)%, (5.23 ± 12.74)%, and (1.69 ± 2.66)%. The ratios of </span><span style="font-family:Verdana;">Neu, Eos, and Lym in </span><span style="font-family:Verdana;">peripheral blood were (63.29 ± 11.44)%, (2.99 ± 3.60)%, and (25.16 ± 10.19)%. The results showed that the ratios of Neu and Eos in induced sputum were significantly correlated with the proportion of </span><span style="font-family:Verdana;">corresponding cells in peripheral blood (P < 0.05). </span><span style="font-family:Verdana;">There was no correlation between the ratio of Lym and Leu in induced sputum and corresponding cells in </span><span style="font-family:Verdana;">peripheral blood (P > 0.05). In patients with AECOPD, the tendency of Neu and Eos in induced sputum was </span><span style="font-family:Verdana;">consistent with the corresponding cells in peripheral blood. Neu and Eos in </span><span style="font-family:Verdana;">induced sputum and peripheral blood reflected the degree of inflammation to guide the individualized medication of patients.展开更多
Spatial instability waves associated with lowfrequency noise radiation at shallow polar angles in the chevron jet are investigated and are compared to the round counterpart. The Reynolds-averaged Navier–Stokes equati...Spatial instability waves associated with lowfrequency noise radiation at shallow polar angles in the chevron jet are investigated and are compared to the round counterpart. The Reynolds-averaged Navier–Stokes equations are solved to obtain the mean flow fields, which serve as the baseflow for linear stability analysis. The chevron jet has more complicated instability waves than the round jet, where three types of instability modes are identified in the vicinity of the nozzle, corresponding to radial shear, azimuthal shear,and their integrated effect of the baseflow, respectively. The most unstable frequency of all chevron modes and round modes in both jets decrease as the axial location moves downstream. Besides, the azimuthal shear effect related modes are more unstable than radial shear effect related modes at low frequencies. Compared to a round jet, a chevron jet reduces the growth rate of the most unstable modes at downstream locations. Moreover, linearized Euler equations are employed to obtain the beam pattern of pressure generated by spatially evolving instability waves at a dominant low frequency St = 0.3, and the acoustic efficiencies of these linear wavepackets are evaluated for both jets. It is found that the acoustic efficiency of linear wavepacket is able to be reduced greatly in the chevron jet, compared to the round jet.展开更多
A large eddy simulation(LES) is performed for two subsonic jets with a Reynolds number of Re = 105,which have different core temperatures, i.e., the cold and hot jet. The far-field overall sound pressure levels(OASPL)...A large eddy simulation(LES) is performed for two subsonic jets with a Reynolds number of Re = 105,which have different core temperatures, i.e., the cold and hot jet. The far-field overall sound pressure levels(OASPL)and noise spectra are well validated against previous experimental results. It is found that the OASPL is raised by heating at shallow angles. The most energetic coherent structures are extracted with specified frequencies using the filter based on the frequency domain variant of the snapshot method of proper orthogonal decomposition(POD). The m = 0, 1 modes have high coherence of near-field pressure for both jets, while the coherence of m = 0 modes is enhanced greatly by heating. Based on the coherent structures, spatial wavepackets are educed and the characteristics of growth, saturation and decay are analyzed and compared between the two jets in detail. The results show that heating would enhance the linear growth rate for high frequency components, and nonlinear growth rates for low frequency components in general, which are responsible for higher OASPL in the hot jet. The far-field sound generated by wavepackets is computed using the Kirchhoff extrapolation,which matches well with that of LES at shallow angles.This indicates that the wavepackets associated with coherent structures are dominant sound sources in forced transitional turbulent jets. Additionally, the present POD method is proven to be a robust tool to extract the salient features of the wavepackets in turbulent flows.展开更多
Supersonic flows past two-dimensional cavities with/without control are investigated by the direct numerical simulation(DNS). For an uncontrolled cavity, as the thickness of the boundary layer declines, transition of ...Supersonic flows past two-dimensional cavities with/without control are investigated by the direct numerical simulation(DNS). For an uncontrolled cavity, as the thickness of the boundary layer declines, transition of the dominant mode from the steady mode to the Rossiter Ⅱ mode and then to the Rossiter Ⅲ mode is observed due to the change of vortex-corner interactions. Meanwhile, a low frequency mode appears. However, the wake mode observed in a subsonic cavity flow is absent in the current simulation.The oscillation frequencies obtained from a global dynamic mode decomposition(DMD)approach are consistent with the local power spectral density(PSD) analysis. The dominant mode transition is clearly shown by the dynamic modes obtained from the DMD. A passive control technique of substituting the cavity trailing edge with a quarter-circle is studied. As the effective cavity length increases, the dominant mode transition from the Rossiter Ⅱ mode to the Rossiter Ⅲ mode occurs. With the control, the pressure oscillations are reduced significantly. The interaction of the shear layer and the recirculation zone is greatly weakened, combined with weaker shear layer instability, responsible for the suppression of pressure oscillations. Moreover, active control using steady subsonic mass injection upstream of a cavity leading edge can stabilize the flow.展开更多
The bifurcations of penetrative Rayleigh-B′enard convection in cylindrical containers are studied by the linear stability analysis(LSA) combined with the direct numerical simulation(DNS) method. The working ?uid is c...The bifurcations of penetrative Rayleigh-B′enard convection in cylindrical containers are studied by the linear stability analysis(LSA) combined with the direct numerical simulation(DNS) method. The working ?uid is cold water near 4?C, where the Prandtl number P r is 11.57, and the aspect ratio(radius/height) of the cylinder ranges from 0.66 to 2. It is found that the critical Rayleigh number increases with the increase in the density inversion parameter θ_m. The relationship between the normalized critical Rayleigh number(Rac(θ_m)/Rac(0)) and θ_m is formulated, which is in good agreement with the stability results within a large range of θ_m. The aspect ratio has a minor effect on Rac(θ_m)/Rac(0). The bifurcation processes based on the axisymmetric solutions are also investigated. The results show that the onset of axisymmetric convection occurs through a trans-critical bifurcation due to the top-bottom symmetry breaking of the present system.Moreover, two kinds of qualitatively different steady axisymmetric solutions are identi?ed.展开更多
Noise is generated in a two-dimensional mixing layer due to the growing of instability waves and vortex pairings. The adjoint-based control methodology has shown to be a robust tool to suppress noise radiation. The mo...Noise is generated in a two-dimensional mixing layer due to the growing of instability waves and vortex pairings. The adjoint-based control methodology has shown to be a robust tool to suppress noise radiation. The mode decomposition algorithms such as the compressible version of proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) are employed to analyze the spatial/spatial-temporal coherent structures for a consecutive data sets of the controlled mixing layer and its uncontrolled counterpart. The analyses of POD indicate that the y-direction body force control mainly modify the most energetic spatial structures, and increase the uniformity of the flow. The analyses of DMD show us prevalent frequencies and corresponding mode structures, and the stability characteristics of each mode can be obtained from DMD-spectrum. The spectral signatures illustrate that a lot of neutral/slightly damping modes emerging in uncontrolled flow within the frequency range (ω < 0.4) are suppressed due to control, relevant spatial-temporal structures are also varied, which is coincident with the change of far-field noise spectra. From the view of mode decomposition, the action of control redistribute the energy for frequency components of ω < 0.4 by weakening nonlinearities and regularizing corresponding dynamic structures in streamwise direction, and thus suppress the noise radiation. Moreover, the PODand DMD-analysis in this study demonstrate that DMD can serve as an important supplement for POD in analyzing a time-resolved physical process.展开更多
The reduced-order model(ROM) for the two-dimensional supersonic cavity flow based on proper orthogonal decomposition(POD) and Galerkin projection is investigated. Presently, popular ROMs in cavity flows are based on a...The reduced-order model(ROM) for the two-dimensional supersonic cavity flow based on proper orthogonal decomposition(POD) and Galerkin projection is investigated. Presently, popular ROMs in cavity flows are based on an isentropic assumption,valid only for flows at low or moderate Mach numbers. A new ROM is constructed involving primitive variables of the fully compressible Navier-Stokes(N-S) equations, which is suitable for flows at high Mach numbers. Compared with the direct numerical simulation(DNS) results, the proposed model predicts flow dynamics(e.g., dominant frequency and amplitude) accurately for supersonic cavity flows, and is robust. The comparison between the present transient flow fields and those of the DNS shows that the proposed ROM can capture self-sustained oscillations of a shear layer. In addition, the present model reduction method can be easily extended to other supersonic flows.展开更多
Stabilities of supersonic jets are examined with different velocities, momentum thicknesses, and core temperatures. Amplification rates of instability waves at inlet are evaluated by linear stability theory(LST). It i...Stabilities of supersonic jets are examined with different velocities, momentum thicknesses, and core temperatures. Amplification rates of instability waves at inlet are evaluated by linear stability theory(LST). It is found that increased velocity and core temperature would increase amplification rates substantially and such influence varies for different azimuthal wavenumbers. The most unstable modes in thin momentum thickness cases usually have higher frequencies and azimuthal wavenumbers. Mode switching is observed for low azimuthal wavenumbers, but it appears merely in high velocity cases. In addition, the results provided by linear parabolized stability equations show that the mean-flow divergence affects the spatial evolution of instability waves greatly. The most amplified instability waves globally are sometimes found to be different from that given by LST.展开更多
Viscous fingering in a modified Hele-Shaw cell is numerically investigated.The cell allows periodic variation of depth in the lateral direction. The wavenumber n of the depth perturbation has great influence on finger...Viscous fingering in a modified Hele-Shaw cell is numerically investigated.The cell allows periodic variation of depth in the lateral direction. The wavenumber n of the depth perturbation has great influence on fingering patterns. For n = 1, the fingering pattern due to the interface instability remains the same as that in the conventional Hele-Shaw cell, while the depth variation causes the steady finger to be a little narrower. For n = 2, four different fingering patterns are captured, similar to the available experimental observations in a modified Hele-Shaw cell containing a centered step-like occlusion. It is found that new fingering patterns appear as n further increases, among which, two patterns with spatial oscillation along both edges of the finger are particularly interesting.One is a symmetric oscillatory finger for n = 3, and the other is an asymmetric one for n = 4. The influence of capillary number on fingering patterns is studied for n = 3 and 4.We find that spatial oscillation of the finger nearly ceases at moderate capillary numbers and occurs again as the capillary number increases further. Meanwhile, the wide finger shifts to the narrow one. It is accompanied by a sudden decrease in the finger width which otherwise decreases continuously as the capillary number increases. The wavenumber and the amplitude of depth perturbation have little effect on the finger width.展开更多
The far-field noise radiated from mixing layers is determined by the near-field flow dynamics which is sensitive to the initial perturbation of instability introduced physically or numerically.This study focuses on th...The far-field noise radiated from mixing layers is determined by the near-field flow dynamics which is sensitive to the initial perturbation of instability introduced physically or numerically.This study focuses on the effects of the phase delay in two initial perturbations,one at the fundamental wave number and the other at its subharmonic both calculated from linear instability analysis,on the sound generation in mixing layers.When different phase delaysφ_1 changing from zero to 2πis applied on the fundamental mode,we observe different vortex merging processes(e.g.vortex pairing or tearing).The strong nonlinear interaction in the merging process generates most of the noise from mixing layers.There shows a pattern in a period of 2πfor the response of far-field sound to the change ofφ_1.Similar effects on the dynamics and acoustics can be achieved by adding different phase delaysφ_2 to the subharmonic mode instead,however,the response repeats in a period of onlyπforφ_2.The effects of the combination of different phase delays to other parameters,including the amplitude and wave number for each perturbations,are also investigated.All the results indicate a critical role of nonlinearity in the sound generation mechanism of mixing layers.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA25050400 and XDA25010200)the National Natural Science Foundation of China(Grant No.12175229 and 12388101)+1 种基金the Frontier Scientific Research Program of the Deep Space Exploration Laboratory(Grant No.2022-QYKYJH-HXYF-019)by the Fundamental Research Funds for the Central Universities.
文摘The evolution of ablative Rayleigh–Taylor instability(ARTI)induced by single-mode stationary and time-varying perturbations in heat flux is studied numerically in two dimensions.Compared with the stationary case,time-varying heat-flux perturbation mitigates ARTI growth because of the enhanced thermal smoothing induced by the wave-like traveling heat flux.A resonance is found to form when the phase velocity of the heat-flux perturbation matches the average sound speed in the ablation region.In the resonant regime,the coherent density and temperature fluctuations enhance the electron thermal conduction in the ablation region and lead to larger ablation pressure and effective acceleration,which consequently yield higher linear growth rate and saturated bubble velocity.The enhanced effective acceleration offers increased implosion velocity but can also compromise the integrity of inertial confinement fusion shells by causing faster ARTI growth.
文摘<strong>Objective: </strong>The quantum dots are the useful materials in microelectronics and biomedical research. However its toxicity has to be considered. We studied the effect of cell inhibition with ZnS core quantum dots and CdTe quantum dots modified with Thioglycolic acid or Cysteine functional group (TGA-CdTe, TGA-CdTe/ZnS, Cys-CdTe, Cys-CdTe/ZnS) on Caco-2 cell proliferation. <strong>Methods</strong>: We studied the effect of cell inhibition with ZnS core QDs and CdTe QDs modified with functional group on Caco-2 cell proliferation by MTT assay at 0, 12.5, 25, 50, 100 μg/ml and 6, 24, 48 h. <strong>Result:</strong> Our results showed that all QDs have inhibited cell proliferation and reached maximum 79.21%. The inhibition rate of Cys-modified QDs increased with the increase of concentration and reached maximum 66.72%. The inhibition rate of TGA-modified QDs increased with the increase of time. The ratios of Cys-modified to TGA-modified were less than 1 at all concentrations and three exposure times (P ≤ 0.01). The average ratios of Cys-CdTe/ZnS to Cys-CdTe reached 1.11 only for 48 h (P ≤ 0.05). The ratios of TGA-CdTe/ZnS to TGA-CdTe were closed to 1 at all concentrations and exposure times. <strong>Conclusion:</strong> The regularity of QDs modified with functional group is that inhibition of TGA-modified higher than Cys-modified. Inhibition exhibited dose-dependent for Cys-modified while exhibited time-dependent for TGA-modified. The regularity of CdTe-QDs with ZnS or not is that the inhibition of Cys-CdTe/ZnS was higher than Cys-CdTe while TGA-CdTe/ZnS and TGA-CdTe were consistent.
文摘<i><span style="font-family:Verdana;">Aconitum kusnezoffii</span></i><span style="font-family:Verdana;"></span><span style="font-family:;" "=""><span style="font-family:Verdana;"> used as an analgesic and anti-inflammatory. It is often used not only in Mongolian medicine but also in traditional Chinese medicine. However, there are few studies on its impact of inflammatory cytokines. This study explored the effects of </span><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">Aconitum kusnezoffii</span></i> <i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"></span></i></span><span style="font-family:Verdana;"> used human colon cancer (Caco-2) cells. Cytotoxicity was assessed by measuring effects on expression of IL-1</span><i><span style="font-family:Verdana;"><span style="white-space:nowrap;">β</span></span></i><span style="font-family:Verdana;">, IL-6, IL-8, and TNF-</span><i><span style="font-family:Verdana;"><span style="white-space:nowrap;">α</span></span></i><span style="font-family:Verdana;"> used enzyme-linked immun</span><span style="font-family:Verdana;">o</span><span style="font-family:;" "=""><span style="font-family:Verdana;">sorbent assay (ELISA). </span><span><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">In vitro</span></i><span style="font-family:Verdana;"></span></i></span></span><span style="font-family:Verdana;"> study demonstrated that incubation of Caco-2 cells with some kinds of</span><i> </i><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">Aconitum kusnezoffii</span></i><span style="font-family:Verdana;"></span></i><span style="font-family:Verdana;"> at some concentrations inhibit secretion of TNF-</span><i><span style="font-family:Verdana;"><span style="white-space:nowrap;">α</span></span></i><span style="font-family:Verdana;"> and FAXIU </span><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">ACONITUM</span></i> <i><span style="font-family:Verdana;">KUSNEZOFFII</span></i><span style="font-family:Verdana;"></span></i><span style="font-family:Verdana;"> could inhibit the secretion of IL-1</span><i><span style="font-family:Verdana;"><span style="white-space:nowrap;">β</span></span></i><span style="font-family:Verdana;">. While IL-6 and IL-8 levels were unaffected after 24 h of treatment with </span><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">Aconitum kusnezoffii</span></i><span style="font-family:Verdana;"><i></i></span><i><span style="font-family:Verdana;">, </span></i></i><span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span><span style="font-family:Verdana;">qujian </span><i><i><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">Aconitum kusnezoffii</span></i><span style="font-family:Verdana;"><i></i></span><i><span style="font-family:Verdana;">, </span></i></i></i></i><span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span><span style="font-family:Verdana;">faxiu </span><i><i><i><i><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">Aconitum kusnezoffii</span></i><span style="font-family:Verdana;"></span></i><span style="font-family:Verdana;">.</span></i></i></i></i>
文摘Chronic obstructive pulmonary disease </span><span style="font-family:""><span style="font-family:Verdana;">(COPD) is a major chronic respiratory disease worldwide. Inflammatory cells reflect the </span><span style="font-family:Verdana;">inflammatory situation both in peripheral blood and induced sputum. </span></span><span style="font-family:""><span style="font-family:Verdana;">Their correlation has not been reported. </span><span style="font-family:Verdana;">The correlation between neutrophils (Neu), eosinophils (Eos), and lymphocyte (Lym) in induced sputum and that in peripheral blood of COPD </span><span style="font-family:Verdana;">patients was evaluated </span><span><span style="font-family:Verdana;">to explore the </span><span style="font-family:Verdana;">consistency of inflammatory cells in peripheral blood and induced sputum. Peripheral blood and induced sputum were collected from 437 </span><span style="font-family:Verdana;">patients with acute exacerbation of COPD</span></span><span style="font-family:Verdana;"> (AECOPD) who were hospitalized in the Department of respiratory and critical care medicine, Inner Mongolia People’s Hospital. </span><span style="font-family:Verdana;">The correlation analysis was performed by Spearman correlation analysis. </span><span style="font-family:Verdana;">The r</span><span style="font-family:Verdana;">atios of Neu, Eos, and Lym in induced sputum were (79.15 ± 22.60)%, (5.23 ± 12.74)%, and (1.69 ± 2.66)%. The ratios of </span><span style="font-family:Verdana;">Neu, Eos, and Lym in </span><span style="font-family:Verdana;">peripheral blood were (63.29 ± 11.44)%, (2.99 ± 3.60)%, and (25.16 ± 10.19)%. The results showed that the ratios of Neu and Eos in induced sputum were significantly correlated with the proportion of </span><span style="font-family:Verdana;">corresponding cells in peripheral blood (P < 0.05). </span><span style="font-family:Verdana;">There was no correlation between the ratio of Lym and Leu in induced sputum and corresponding cells in </span><span style="font-family:Verdana;">peripheral blood (P > 0.05). In patients with AECOPD, the tendency of Neu and Eos in induced sputum was </span><span style="font-family:Verdana;">consistent with the corresponding cells in peripheral blood. Neu and Eos in </span><span style="font-family:Verdana;">induced sputum and peripheral blood reflected the degree of inflammation to guide the individualized medication of patients.
基金supported by the National Natural Science Foundation of China(Grants 11232011,11402262,11572314,and 11621202)the Fundamental Research Funds for the Central Universitiesthe China Postdoctoral Science Foundation(Grant 2017M610823)
文摘Spatial instability waves associated with lowfrequency noise radiation at shallow polar angles in the chevron jet are investigated and are compared to the round counterpart. The Reynolds-averaged Navier–Stokes equations are solved to obtain the mean flow fields, which serve as the baseflow for linear stability analysis. The chevron jet has more complicated instability waves than the round jet, where three types of instability modes are identified in the vicinity of the nozzle, corresponding to radial shear, azimuthal shear,and their integrated effect of the baseflow, respectively. The most unstable frequency of all chevron modes and round modes in both jets decrease as the axial location moves downstream. Besides, the azimuthal shear effect related modes are more unstable than radial shear effect related modes at low frequencies. Compared to a round jet, a chevron jet reduces the growth rate of the most unstable modes at downstream locations. Moreover, linearized Euler equations are employed to obtain the beam pattern of pressure generated by spatially evolving instability waves at a dominant low frequency St = 0.3, and the acoustic efficiencies of these linear wavepackets are evaluated for both jets. It is found that the acoustic efficiency of linear wavepacket is able to be reduced greatly in the chevron jet, compared to the round jet.
基金supported by the National Natural Science Foundation of China (Grants 11232011, 11402262, 11572314, 11621202)the Fundamental Research Funds for the Central Universities
文摘A large eddy simulation(LES) is performed for two subsonic jets with a Reynolds number of Re = 105,which have different core temperatures, i.e., the cold and hot jet. The far-field overall sound pressure levels(OASPL)and noise spectra are well validated against previous experimental results. It is found that the OASPL is raised by heating at shallow angles. The most energetic coherent structures are extracted with specified frequencies using the filter based on the frequency domain variant of the snapshot method of proper orthogonal decomposition(POD). The m = 0, 1 modes have high coherence of near-field pressure for both jets, while the coherence of m = 0 modes is enhanced greatly by heating. Based on the coherent structures, spatial wavepackets are educed and the characteristics of growth, saturation and decay are analyzed and compared between the two jets in detail. The results show that heating would enhance the linear growth rate for high frequency components, and nonlinear growth rates for low frequency components in general, which are responsible for higher OASPL in the hot jet. The far-field sound generated by wavepackets is computed using the Kirchhoff extrapolation,which matches well with that of LES at shallow angles.This indicates that the wavepackets associated with coherent structures are dominant sound sources in forced transitional turbulent jets. Additionally, the present POD method is proven to be a robust tool to extract the salient features of the wavepackets in turbulent flows.
基金supported by the National Natural Science Foundation of China(Nos.11232011 and11402262)the 111 Project of China(No.B07033)+1 种基金the China Postdoctoral Science Foundation(No.2014M561833)the Fundamental Research Funds for the Central Universities
文摘Supersonic flows past two-dimensional cavities with/without control are investigated by the direct numerical simulation(DNS). For an uncontrolled cavity, as the thickness of the boundary layer declines, transition of the dominant mode from the steady mode to the Rossiter Ⅱ mode and then to the Rossiter Ⅲ mode is observed due to the change of vortex-corner interactions. Meanwhile, a low frequency mode appears. However, the wake mode observed in a subsonic cavity flow is absent in the current simulation.The oscillation frequencies obtained from a global dynamic mode decomposition(DMD)approach are consistent with the local power spectral density(PSD) analysis. The dominant mode transition is clearly shown by the dynamic modes obtained from the DMD. A passive control technique of substituting the cavity trailing edge with a quarter-circle is studied. As the effective cavity length increases, the dominant mode transition from the Rossiter Ⅱ mode to the Rossiter Ⅲ mode occurs. With the control, the pressure oscillations are reduced significantly. The interaction of the shear layer and the recirculation zone is greatly weakened, combined with weaker shear layer instability, responsible for the suppression of pressure oscillations. Moreover, active control using steady subsonic mass injection upstream of a cavity leading edge can stabilize the flow.
基金Project supported by the National Natural Science Foundation of China(Nos.11572314,11621202,and 11772323)the Fundamental Research Funds for the Central Universities
文摘The bifurcations of penetrative Rayleigh-B′enard convection in cylindrical containers are studied by the linear stability analysis(LSA) combined with the direct numerical simulation(DNS) method. The working ?uid is cold water near 4?C, where the Prandtl number P r is 11.57, and the aspect ratio(radius/height) of the cylinder ranges from 0.66 to 2. It is found that the critical Rayleigh number increases with the increase in the density inversion parameter θ_m. The relationship between the normalized critical Rayleigh number(Rac(θ_m)/Rac(0)) and θ_m is formulated, which is in good agreement with the stability results within a large range of θ_m. The aspect ratio has a minor effect on Rac(θ_m)/Rac(0). The bifurcation processes based on the axisymmetric solutions are also investigated. The results show that the onset of axisymmetric convection occurs through a trans-critical bifurcation due to the top-bottom symmetry breaking of the present system.Moreover, two kinds of qualitatively different steady axisymmetric solutions are identi?ed.
基金supported by the National Natural Science Foundation of China (11072238, 11232011)111 project (B07033)
文摘Noise is generated in a two-dimensional mixing layer due to the growing of instability waves and vortex pairings. The adjoint-based control methodology has shown to be a robust tool to suppress noise radiation. The mode decomposition algorithms such as the compressible version of proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) are employed to analyze the spatial/spatial-temporal coherent structures for a consecutive data sets of the controlled mixing layer and its uncontrolled counterpart. The analyses of POD indicate that the y-direction body force control mainly modify the most energetic spatial structures, and increase the uniformity of the flow. The analyses of DMD show us prevalent frequencies and corresponding mode structures, and the stability characteristics of each mode can be obtained from DMD-spectrum. The spectral signatures illustrate that a lot of neutral/slightly damping modes emerging in uncontrolled flow within the frequency range (ω < 0.4) are suppressed due to control, relevant spatial-temporal structures are also varied, which is coincident with the change of far-field noise spectra. From the view of mode decomposition, the action of control redistribute the energy for frequency components of ω < 0.4 by weakening nonlinearities and regularizing corresponding dynamic structures in streamwise direction, and thus suppress the noise radiation. Moreover, the PODand DMD-analysis in this study demonstrate that DMD can serve as an important supplement for POD in analyzing a time-resolved physical process.
基金Project supported by the National Natural Science Foundation of China(Nos.11232011,11402262,11572314,and 11621202)
文摘The reduced-order model(ROM) for the two-dimensional supersonic cavity flow based on proper orthogonal decomposition(POD) and Galerkin projection is investigated. Presently, popular ROMs in cavity flows are based on an isentropic assumption,valid only for flows at low or moderate Mach numbers. A new ROM is constructed involving primitive variables of the fully compressible Navier-Stokes(N-S) equations, which is suitable for flows at high Mach numbers. Compared with the direct numerical simulation(DNS) results, the proposed model predicts flow dynamics(e.g., dominant frequency and amplitude) accurately for supersonic cavity flows, and is robust. The comparison between the present transient flow fields and those of the DNS shows that the proposed ROM can capture self-sustained oscillations of a shear layer. In addition, the present model reduction method can be easily extended to other supersonic flows.
基金supported by the National Natural Science Foundation of China(11232011 and 11402262)China Postdoctral Science Foundation Funded Project(2014M561833)111 Project(B07033)
文摘Stabilities of supersonic jets are examined with different velocities, momentum thicknesses, and core temperatures. Amplification rates of instability waves at inlet are evaluated by linear stability theory(LST). It is found that increased velocity and core temperature would increase amplification rates substantially and such influence varies for different azimuthal wavenumbers. The most unstable modes in thin momentum thickness cases usually have higher frequencies and azimuthal wavenumbers. Mode switching is observed for low azimuthal wavenumbers, but it appears merely in high velocity cases. In addition, the results provided by linear parabolized stability equations show that the mean-flow divergence affects the spatial evolution of instability waves greatly. The most amplified instability waves globally are sometimes found to be different from that given by LST.
基金Project supported by the National Natural Science Foundation of China(No.11232011)the 111 Project of China(No.B07033)
文摘Viscous fingering in a modified Hele-Shaw cell is numerically investigated.The cell allows periodic variation of depth in the lateral direction. The wavenumber n of the depth perturbation has great influence on fingering patterns. For n = 1, the fingering pattern due to the interface instability remains the same as that in the conventional Hele-Shaw cell, while the depth variation causes the steady finger to be a little narrower. For n = 2, four different fingering patterns are captured, similar to the available experimental observations in a modified Hele-Shaw cell containing a centered step-like occlusion. It is found that new fingering patterns appear as n further increases, among which, two patterns with spatial oscillation along both edges of the finger are particularly interesting.One is a symmetric oscillatory finger for n = 3, and the other is an asymmetric one for n = 4. The influence of capillary number on fingering patterns is studied for n = 3 and 4.We find that spatial oscillation of the finger nearly ceases at moderate capillary numbers and occurs again as the capillary number increases further. Meanwhile, the wide finger shifts to the narrow one. It is accompanied by a sudden decrease in the finger width which otherwise decreases continuously as the capillary number increases. The wavenumber and the amplitude of depth perturbation have little effect on the finger width.
基金supported by the National Natural Science Foundation of China(11072238)111 Project (B07033)
文摘The far-field noise radiated from mixing layers is determined by the near-field flow dynamics which is sensitive to the initial perturbation of instability introduced physically or numerically.This study focuses on the effects of the phase delay in two initial perturbations,one at the fundamental wave number and the other at its subharmonic both calculated from linear instability analysis,on the sound generation in mixing layers.When different phase delaysφ_1 changing from zero to 2πis applied on the fundamental mode,we observe different vortex merging processes(e.g.vortex pairing or tearing).The strong nonlinear interaction in the merging process generates most of the noise from mixing layers.There shows a pattern in a period of 2πfor the response of far-field sound to the change ofφ_1.Similar effects on the dynamics and acoustics can be achieved by adding different phase delaysφ_2 to the subharmonic mode instead,however,the response repeats in a period of onlyπforφ_2.The effects of the combination of different phase delays to other parameters,including the amplitude and wave number for each perturbations,are also investigated.All the results indicate a critical role of nonlinearity in the sound generation mechanism of mixing layers.
