The investigation on the aerodynamic characteristics of the high-attitude long-endurance (HALE) Diamond Joined-Wing configuration unmanned aerial vehicle ( UAV) was carried out by the theoretical analysis method and n...The investigation on the aerodynamic characteristics of the high-attitude long-endurance (HALE) Diamond Joined-Wing configuration unmanned aerial vehicle ( UAV) was carried out by the theoretical analysis method and numerical simulation. Research indicates that as the wing of the UAV is composed of the front wing and the after wing, the after wing has the ability to transmit the front wing's boundary layer to the after wing root which can inhibit the front wing's flow separation. Although the front wing was affected by the retardation of the after wing, the aerodynamic performance of the front wing was better than that of alone front wing in most cases. The after wing was also affected by the wake and downwash of the front wing, and its aerodynamic performance was greatly decreased. The characteristic curve of the pitching moment of the UAV had nonlinear characteristics. The flow field structure of the after wing changed by the front wing wake direct sweep and flow separation at the after wing root were the main reasons that non-linear ′rise′phenomenon occurred in two segments ( α = 0° and α = 8° ) of the characteristic curve of pitching moment. Moreover, coupling of the flow separation characteristic of the front wing and the after wing resulted in the pitching moment ′pitchup′ phenomenon. The lateral-directional static stability of the flat layout was weak. The HALE Diamond Joined-Wing configuration UAV ' s aerodynamic performance can be improved and the problems in engineering applications can be effectively alleviated by adjusting the overall layout parameters.展开更多
On the basis of photogravitational theory,the influence of solar photogravitation on the motion of comet Hale-Bopp is discussed.It is shown that for plasma tail of comet Hale-Bopp there is only one collinear point L_(...On the basis of photogravitational theory,the influence of solar photogravitation on the motion of comet Hale-Bopp is discussed.It is shown that for plasma tail of comet Hale-Bopp there is only one collinear point L_(3) and for a few of dust tail there can be two coplanar points L_(6),L_(7) and three collinear points L_(21),L_(22),L_(3).The regions in which the coplanar points exist and the dust grain of comet Hale-Bopp can move are also obtained.展开更多
The wavelet transform is applied to studying the near nuclear region of Comet Hale Bopp. The transform suppresses the coma background to enhance visibility of coma features such as jets and shells from which apparent ...The wavelet transform is applied to studying the near nuclear region of Comet Hale Bopp. The transform suppresses the coma background to enhance visibility of coma features such as jets and shells from which apparent expansion speed is measured. Furthermore, two cometary bursts of this comet were found on April 22 and Sept. 10 11. 1996. The latter one coincides with a strong increase in the luminosity in X rays almost at the same time. During the outburst, two globular ejecta were found, and their expanding speeds were about 100m/s. In addition, the projected rotation period is derived.展开更多
Objective The investigate the effect of polypeptide isolated from Chlamys Farreri (PCF) on Hela cells damaged by ultraviolet(UV). Methods The suspension of Hela epithelia cells (5 × 10^8/mL ) cultured for 24 ...Objective The investigate the effect of polypeptide isolated from Chlamys Farreri (PCF) on Hela cells damaged by ultraviolet(UV). Methods The suspension of Hela epithelia cells (5 × 10^8/mL ) cultured for 24 hours were prepared and 1 mL of it was put into each hole of 24-hole plates. Some Hela cells were randomly divided into six groups: control group (C), modal group(M), 5 g/L PCF group, 10 g/L PCF group, 20 g/L PC Fgroup and 10 g/L Vitamin-C (Vc) group. After incubation with RPMI-1640, PCF, Vitamin C, respectively, for 10minutes, the cells were exposed to UVA ( irradiation intensity: 3650 μ/cm^2 ), with the exception of the mice in C group. Some other Hela cells were divided into another six groups, they were treated almost the same as above, but irradiated by UVB ( irradiation intensity: 7.15 ×10^-5 J/cm^2). The intracellular free calcium (Ca^2+ ), apoptosis and cell death rate were measured by flow cytometry (FCM). Enzyme activities and malondialdehyde (MDA) were determined by biochemical assays. Results The apoptosis and cell death rate were decreased and the contents of intracellular Ca^2+ and activities of succinate dehydrogenase (SDH) as well as the activities of GSH-px, SOD,CAT increased and the MDA decreased by the action of PCF. Conclusion It is suggested that PCF could protect the cells from the damage caused by UVA and UVB by enhancing the activities of antioxidant enzymes.展开更多
Objective To observe the spatial and temporal distribution of collagen in fetal and adult rats wounds. Methods The organization of collagen deposition in fetal and adult rats skin wounds were observed by using van Gie...Objective To observe the spatial and temporal distribution of collagen in fetal and adult rats wounds. Methods The organization of collagen deposition in fetal and adult rats skin wounds were observed by using van Gieson stain. The methods of immunohistochemistry and in situ hybridization were applied to examine collagen type Ⅰ and Ⅲ peptide and mRNA localization at serial time point during wound healing. Results Collagen type Ⅰ and Ⅲ were present in wounds of both fetal and adult rats, but the timing and pattern of collagen deposition varied. In the fetus, collagen wes detected by 48h postwounding (PW), but uns not present in the adult wounds until 5d PW. N in situ hybridization, signals in the area of the fetal wound were clearly greater and with increased number of cells as compered to that in the adjacent unwounded tissue. Adult rat wounds had evidence in increased signals of procollagen type Ⅰ and Ⅲ production by wound fibroblasts on day 5. Collagen deposited and wes arranged in reticular pattern as that of the nounal in fetal wounds. While in the adult wound, collagen deposited in the fashion of course bundles. bundles Conclusion Fetal rat wounds appeared to produce collagen mainly by an increased number offibroblasts in the area of the wound. In contrast, adult rat wounds underwent fibroblast migration and induction of procollagen mRNA synthesis. Our results Suggest that the deposition of collagen type Ⅰ and Ⅲ is regulated by their gene expression. Chllagen type Ⅲ plays an important role in the arrangement of collagen depoition.展开更多
基金Sponsored by the Civil Aircraft Project(Grant No.MIE-2015-F-009)the Shaanxi Province Science and Technology Project(Grant No.2015KTCQ01-78)
文摘The investigation on the aerodynamic characteristics of the high-attitude long-endurance (HALE) Diamond Joined-Wing configuration unmanned aerial vehicle ( UAV) was carried out by the theoretical analysis method and numerical simulation. Research indicates that as the wing of the UAV is composed of the front wing and the after wing, the after wing has the ability to transmit the front wing's boundary layer to the after wing root which can inhibit the front wing's flow separation. Although the front wing was affected by the retardation of the after wing, the aerodynamic performance of the front wing was better than that of alone front wing in most cases. The after wing was also affected by the wake and downwash of the front wing, and its aerodynamic performance was greatly decreased. The characteristic curve of the pitching moment of the UAV had nonlinear characteristics. The flow field structure of the after wing changed by the front wing wake direct sweep and flow separation at the after wing root were the main reasons that non-linear ′rise′phenomenon occurred in two segments ( α = 0° and α = 8° ) of the characteristic curve of pitching moment. Moreover, coupling of the flow separation characteristic of the front wing and the after wing resulted in the pitching moment ′pitchup′ phenomenon. The lateral-directional static stability of the flat layout was weak. The HALE Diamond Joined-Wing configuration UAV ' s aerodynamic performance can be improved and the problems in engineering applications can be effectively alleviated by adjusting the overall layout parameters.
基金Supported by the National Natural Science Foundation of China under Grant No.19633010Jiangsu Natural Science Foundation。
文摘On the basis of photogravitational theory,the influence of solar photogravitation on the motion of comet Hale-Bopp is discussed.It is shown that for plasma tail of comet Hale-Bopp there is only one collinear point L_(3) and for a few of dust tail there can be two coplanar points L_(6),L_(7) and three collinear points L_(21),L_(22),L_(3).The regions in which the coplanar points exist and the dust grain of comet Hale-Bopp can move are also obtained.
文摘The wavelet transform is applied to studying the near nuclear region of Comet Hale Bopp. The transform suppresses the coma background to enhance visibility of coma features such as jets and shells from which apparent expansion speed is measured. Furthermore, two cometary bursts of this comet were found on April 22 and Sept. 10 11. 1996. The latter one coincides with a strong increase in the luminosity in X rays almost at the same time. During the outburst, two globular ejecta were found, and their expanding speeds were about 100m/s. In addition, the projected rotation period is derived.
文摘Objective The investigate the effect of polypeptide isolated from Chlamys Farreri (PCF) on Hela cells damaged by ultraviolet(UV). Methods The suspension of Hela epithelia cells (5 × 10^8/mL ) cultured for 24 hours were prepared and 1 mL of it was put into each hole of 24-hole plates. Some Hela cells were randomly divided into six groups: control group (C), modal group(M), 5 g/L PCF group, 10 g/L PCF group, 20 g/L PC Fgroup and 10 g/L Vitamin-C (Vc) group. After incubation with RPMI-1640, PCF, Vitamin C, respectively, for 10minutes, the cells were exposed to UVA ( irradiation intensity: 3650 μ/cm^2 ), with the exception of the mice in C group. Some other Hela cells were divided into another six groups, they were treated almost the same as above, but irradiated by UVB ( irradiation intensity: 7.15 ×10^-5 J/cm^2). The intracellular free calcium (Ca^2+ ), apoptosis and cell death rate were measured by flow cytometry (FCM). Enzyme activities and malondialdehyde (MDA) were determined by biochemical assays. Results The apoptosis and cell death rate were decreased and the contents of intracellular Ca^2+ and activities of succinate dehydrogenase (SDH) as well as the activities of GSH-px, SOD,CAT increased and the MDA decreased by the action of PCF. Conclusion It is suggested that PCF could protect the cells from the damage caused by UVA and UVB by enhancing the activities of antioxidant enzymes.
文摘Objective To observe the spatial and temporal distribution of collagen in fetal and adult rats wounds. Methods The organization of collagen deposition in fetal and adult rats skin wounds were observed by using van Gieson stain. The methods of immunohistochemistry and in situ hybridization were applied to examine collagen type Ⅰ and Ⅲ peptide and mRNA localization at serial time point during wound healing. Results Collagen type Ⅰ and Ⅲ were present in wounds of both fetal and adult rats, but the timing and pattern of collagen deposition varied. In the fetus, collagen wes detected by 48h postwounding (PW), but uns not present in the adult wounds until 5d PW. N in situ hybridization, signals in the area of the fetal wound were clearly greater and with increased number of cells as compered to that in the adjacent unwounded tissue. Adult rat wounds had evidence in increased signals of procollagen type Ⅰ and Ⅲ production by wound fibroblasts on day 5. Collagen deposited and wes arranged in reticular pattern as that of the nounal in fetal wounds. While in the adult wound, collagen deposited in the fashion of course bundles. bundles Conclusion Fetal rat wounds appeared to produce collagen mainly by an increased number offibroblasts in the area of the wound. In contrast, adult rat wounds underwent fibroblast migration and induction of procollagen mRNA synthesis. Our results Suggest that the deposition of collagen type Ⅰ and Ⅲ is regulated by their gene expression. Chllagen type Ⅲ plays an important role in the arrangement of collagen depoition.
