Electrochromic devices are applied extensively to camouflages, smart windows, heat insulation layers, and automobile rearview mirrors, etc. The amorphous WO3 is a very attractive electrochromic ...material, whereas it suffers from degradation of optical modulation and reversibility on ion exchange owing to those deep trapped ions with irreversible reaction behavior. Herein, we designed and, by using magnetron sputtering, prepared a composite film with TiO2/WO3/TiO2 double heterojunctions, which is capable of eliminating the deep trapped ions by itself under ultraviolet light (UV) assistance. The electrochromic device based on this composite film, after being recovery by short-time UV irradiation, can maintain a high transmission modulation of 94.72% after 7000 cycles of the voltammetry measurement. This feature allows the device to maintain its initial electrochromic performance after prolonged use. Moreover, the double heterojunction structure can reduce colouring time and enormously improve the colouration efficiency (CE) of electrochromic devices. Experimental research shows that when the thickness of the bottom and upper TiO2 layer of the WO3 film was 145.5 nm and 97.0 nm, respectively, the CE of electrochromic devices reached a perfectly high value (479.3 cm2/C), being much higher than that of WO3 devices (69.5 cm2/C). Functions of the TiO2/WO3/TiO2 double heterojunction in electrochromic device were investigated by combining theoretical analysis and experiment validation, and these results provide a general framework for developing and designing superior electrochromic materials and devices.
The role of neuroinflammation in the pathogenesis of Alzheimer's disease (AD) has attracted much attention recently. Regulatory T-cells (Tregs) play an important role in modulating inflammation. We ...aimed to explore the Treg-related immunosuppression status at different stages of AD.
Thirty healthy control (HC) subjects, 26 patients with mild cognitive impairment (MCI), 30 patients with mild probable AD-related dementia, and 28 patients with moderate-to-severe probable AD-related dementia underwent detailed clinical history taking, structural MRI scanning, and neuropsychological assessment. Peripheral blood samples were taken to measure the percentage of CD4
CD25
CD127
Tregs by flow cytometry and the levels of interleukin (IL-10), interleukin (IL-35), and transforming growth factor β (TGF-β) by ELISA.
The percentage of Tregs in the blood of MCI patients was the highest (9.24%); there was a significant difference between patients with MCI and patients with probable AD-related dementia. The level of TGF-β in patients with MCI (47.02 ng/ml) was significantly increased compared with patients with AD-related dementia. There were positive correlations between Treg percentage, IL-35, and Mini-mental state evaluation scores in patients with MCI and probable AD-related dementia.
Patients with MCI have stronger Treg-related immunosuppression status compared with patients with probable AD-related dementia.
The paper investigates the loss of performance due to flow separation in an over-expanded single expansion ramp nozzle (SERN) during the startup and shutdown process. Characterization of the ...performance of SERN in this flight regime is complicated as the high degree of asymmetry in the geometry of SERN results in asymmetric separation patterns. In this investigation, the various separation patterns of SERN have been studied by way of numerical simulations. The characteristics of the over-expanded separation patterns have been detailed, and the effects of the critical parameters, such as the length of the flap, the expansion ramp angle and the Mach number, have been analyzed. The outcome of the simulations indicates that restricted shock separation (RSS) accounts for the largest range of over-expanded pressure ratios. The length of the flap can affect the separation patterns, and RSS on the flap does not occur for a short flap SERN. Moreover, with the ramp angle larger than 27 degrees, RSS on the ramp can be avoided, while an angle smaller than 20 degree can circumvent free shock separation (FSS) as well as RSS on the flap. When the vehicle accelerates from very low speeds, the separation pattern is changed in a complex manner, transitioning from FSS to RSS and then back to FSS.
A trimming method to optimize the configuration of a three-dimensional asymmetric nozzle with shape transition, which aims to obtain good aerodynamic performance and to save weight at the same time, ...is presented in this paper. Then the effects of the entry shape on the performance of the three-dimensional nozzle are investigated. The streamline tracing involved in an axisymmetric flowfield with optimal thrust is employed to obtain the inviscid contour of the three-dimensional nozzle with shape transition, and the reference temperature method is applied to correct the thickness of the boundary layer. The performance of the designed nozzle is obtained by using computational fluid dynamics. The calculated results show that the trimmed nozzle gains increases in the lift and pitching moment by 427.00% and 10.80%, respectively, with only a 0.76% decrease in the axial thrust coefficient, while the weight can be reduced by as much as 37.51%. For the nozzles with elliptical entrances, as the axial ratio ranges from 1.0 to 2.0, the axial thrust coefficient is increased by 5.38%, while the lift is decreased by 67.74%. When considering the nozzles with rectangular entrances, as the aspect ratio ranges 1.0 to 2.0, the axial thrust coefficient is increased by 3.58%, while the lift and pitching moment are decreased by 82.09% and 16.43%, respectively. Most of the axial thrust is produced on the upper-wall and side-walls in all nozzles, and the contribution of the expansion flow along the side-walls on the thrust generation is pronounced in the nozzle with a relatively smaller entry ratio. However, the majority of the lift and pitching moment are generated on the upper-wall and lower-wall. Besides, the viscosity loss and weight can be reduced by applying the elliptical cross-section in the propulsion system.
The performance of a single expansion ramp nozzle (SERN) is poor due to over-expansion at off-design conditions. The present study focuses on improving the SERN performance by secondary injection on ...the cowl and is carried out by using the k−ε RNG turbulence model. The incidence shock wave resulting from the secondary injection impinges on the expansion ramp, resulting in separation and the increase of the pressure distribution along the ramp. The performance of the SERN can be improved significantly, and the augmentation of the thrust coefficient, lift and pitch moment can be as high as 3.16%, 29.43% and 41.67%, respectively, when the nozzle pressure ratio (NPR) is 10. The location of the injection has a considerable effect on the lift and pitching moment, and the direction of the pitch moment can be changed from nose-up to nose-down when the injection is on the tail of the cowl. The effect of the injection on the axial thrust coefficient is much more apparent, if the operation NPR is far from the design point, and however, the results for the lift and pitching moment are opposite. The increases of injection total pressure and injection width have positive impacts on the SERN performance. And if the parameter φ maintains constant, the axial thrust coefficient would increase when the injection total pressure decreases, so low energy flow can also be used as the secondary injection without decreasing the lift and pitching moment. The mass flow rate of the injection can be decreased by applying the higher total temperature flow without reducing the performance of the SERN.
•The SERN performance at off-design conditions can be improved by the secondary injection.•The theoretical analysis that verifies the feasibility of the injection is performed.•The effects of geometric and aerodynamic parameters of the injection are investigated.
In this paper, the mode transition process of an over-under exhaust system for a turbine based combined cycle (TBCC) is investigated experimentally. The method of characteristics (MOC) and truncation ...method are employed to design the single expansion ramp nozzle (SERN) at the cruise condition, and the final configuration of the exhaust system is determined by resolving the turbine nozzle performance. The crank-link mechanisms are applied to convert the rotation modes of the splitter and cowl to the linear motion modes in the experimental model. The flowfield structure and pressure distribution along the symmetric plane are measured in the experiment. Furthermore, the computational fluid dynamics (CFD) approach is also adopted to simulate the flowfield of the exhaust system for comparison. The results denote that although the flowfield is greatly complicated as the interaction of the exhaust system plume with the external freestream, the internal flowfield of the exhaust system is independent of the external flow. The flowfield of the entire exhaust system is occupied by the turbine nozzle flow at the initial condition, while it is dominated by the ramjet nozzle flow at the end of the mode transition. At the afterburner and throttle stages of the turbine, the shear layer deflects toward the turbine nozzle flowfield, and the influence of the ramjet nozzle jet on the turbine nozzle flowfield is increased. The internal flow of the turbine nozzle is not influenced by the ramjet nozzle plume at the afterburner stage, while it is greatly affected by the ramjet nozzle plume at the throttle stage. Instead, the shear layer deflects toward the ramjet nozzle flowfield at the transitional stage, and the effect of the turbine nozzle flow on the ramjet nozzle flowfield is increased. Furthermore, the calculated flowfield structure and pressure distributions agree well with the experimental results, and the numerical method can be capable of capturing the flowfield feature of the exhaust system.
A new method based on maximum thrust theory to design a two-dimensional single expansion ramp nozzle with geometric constraints directly is presented in this paper. To generate the contour of the ...nozzle, the inviscid flowfield is calculated by using the method of characteristics and the reference temperature method is applied to correct the boundary layer thickness. The computational fluid dynamics approach is employed to obtain the aerodynamic performance of the nozzles. The results show that the initial arc radius slightly influences the axial thrust coefficient and that the variations in the length and initial expansion angle of the cowl significantly affect the axial thrust coefficient. The nozzle designed by truncating ideal nozzle is also investigated for comparison to verify the superiority of this new method. The nozzle designed by this proposed method shows increases in the axial thrust coefficient, lift, and pitching moment of 5.5%, 1098.2% and 20.3%, respectively, at the design point. Moreover, the proposed nozzle provided the positive lift with considerable increments in the axial thrust coefficient and in the pitching moment at off-design operations.
The present study focuses on the unsteady mode transition process of an over-under TBCC exhaust system. The method of characteristics is applied to design the over-under TBCC exhaust system according ...to the entrance parameters of the turbine nozzle and ramjet nozzle at the design point. The dynamic mesh is adopted to adjust to the update of the computational domain, and the unsteady numerical method is employed to simulate the dynamic flowfield of the exhaust system during the mode transition process. The results show that the flowfield structure and the performance vary greatly during the mode transition. Owing to the interaction between the turbine exhaust jet and ramjet plume, the flowfiled in the turbine nozzle is affected by the ramjet exhaust jet considerably. The axial thrust of the turbine nozzle decreases, while that of the ramjet nozzle increases gradually during the mode transition, but the total axial thrust of the entire exhaust system varies smoothly. Both the axial thrust coefficient and pitching moment of the exhaust system increase along with the open of the ramjet nozzle, while the result for the lift is contrary. However, the axial thrust coefficient, lift and pitching moment all decrease rapidly with the shutdown of the turbine nozzle, and the decreases in axial thrust coefficient, lift and pitching moment are 1.04%, 67.15% and 80.92%, respectively. Besides, two sudden change of the axial thrust coefficient exist at the beginning and end of the motion of the splitter plate.
•The unsteady mode transition process for an over-under TBCC exhaust system is investigated.•The unsteady flowfield of the exhaust system during the mode transition process is analysis.•The performance variance of the exhaust system during the mode transition process is discussed.
Electrochromic devices are applied extensively to camouflages, smart windows, heat insulation layers, and automobile rearview mirrors, etc. The amorphous WO
is a very attractive electrochromic ...material, whereas it suffers from degradation of optical modulation and reversibility on ion exchange owing to those deep trapped ions with irreversible reaction behavior. Herein, we designed and, by using magnetron sputtering, prepared a composite film with TiO
/WO
/TiO
double heterojunctions, which is capable of eliminating the deep trapped ions by itself under ultraviolet light (UV) assistance. The electrochromic device based on this composite film, after being recovery by short-time UV irradiation, can maintain a high transmission modulation of 94.72% after 7000 cycles of the voltammetry measurement. This feature allows the device to maintain its initial electrochromic performance after prolonged use. Moreover, the double heterojunction structure can reduce colouring time and enormously improve the colouration efficiency (CE) of electrochromic devices. Experimental research shows that when the thickness of the bottom and upper TiO
layer of the WO
film was 145.5 nm and 97.0 nm, respectively, the CE of electrochromic devices reached a perfectly high value (479.3 cm
/C), being much higher than that of WO
devices (69.5 cm
/C). Functions of the TiO
/WO
/TiO
double heterojunction in electrochromic device were investigated by combining theoretical analysis and experiment validation, and these results provide a general framework for developing and designing superior electrochromic materials and devices.
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