A two-dimensional（2-D） incompressible plane jet is investigated using the lattice Boltzmann method（LBM） for low Reynolds numbers of 42 and 65 based on the jet-exit-width and the maximum jet-exit-velocity. The resu...A two-dimensional（2-D） incompressible plane jet is investigated using the lattice Boltzmann method（LBM） for low Reynolds numbers of 42 and 65 based on the jet-exit-width and the maximum jet-exit-velocity. The results show that the mean centerline velocity decays as x-1/3 and the jet spreads as x2/3 in the self-similar region, which are consistent with the theoretical predictions and the experimental data. The time histories and PSD analyses of the instantaneous centerline velocities indicate the periodic behavior and the interaction between periodic components of velocities should not be neglected in the far field region, although it is invisible in the near field region.展开更多
In order to suppress the speckle appearing in synthesis aperture radar (SAR) images, a novel speckle reduction method based on wavelet domain hidden Markov tree (HMT) was proposed. First, the image was logarithmic tra...In order to suppress the speckle appearing in synthesis aperture radar (SAR) images, a novel speckle reduction method based on wavelet domain hidden Markov tree (HMT) was proposed. First, the image was logarithmic transformed to change the statistical property of the speckles. Then an HMT was constructed in the correspondent wavelet domain. Based on this model, the image signal was restored by maximum likelihood estimation and speckle noise was suppressed. Simulating SAR images had shown that the performance of the filter is satisfactory for both speckle smoothing and edges presentation, and for generating visually natural images as well.展开更多
Adult male rats were treated orally with monomer T_4(Tripchlorolide) isolated from Tripterygium wilfordii, at the dose of 50μg/kg/day,6 days/week for6 weeks.Ultrathin section and freeze etching replica of seminifero...Adult male rats were treated orally with monomer T_4(Tripchlorolide) isolated from Tripterygium wilfordii, at the dose of 50μg/kg/day,6 days/week for6 weeks.Ultrathin section and freeze etching replica of seminiferous tubules and epididymal spermatozoa were examined with elec-tron microscope. The results showed that the spemiogenesis was inhibited T_4 in seminiferous tu-bules. However,the damage and disruption of the spermatozoa were more serious in the epididymis.Damage of the structure and function ot microtubule and microfilament may be the chief reason for sperm damage. Sperm membrane was also very sensitive to the treatiment of monomer T_4.展开更多
The combat survivability is an essential factor to be considered in the development of recent military aircraft. Radar stealth and onboard electronic attack are two major techniques for the reduction of aircraft susce...The combat survivability is an essential factor to be considered in the development of recent military aircraft. Radar stealth and onboard electronic attack are two major techniques for the reduction of aircraft susceptibility. A tactical scenario for a strike mission is presented. The effect of aircraft radar cross section on the detection probability of a threat radar, as well as that of onboard jammer, are investigated. The guidance errors of radar guided surface to air missile and anti aircraft artillery, which are disturbed by radar cross section reduction or jammer radiated power and both of them are determined. The probability of aircraft kill given a single shot is calculated and finally the sortie survivability of an attack aircraft in a supposed hostile thread environment worked out. It is demonstrated that the survivability of a combat aircraft will be greatly enhanced by the combined radar stealth and onboard electronic attack, and the evaluation metho dology is effective and applicable.展开更多
鉴于预期全世界因域名抢注(据报道,自2001年1月1日至2002年2月20日,约有8000多个域名被注册)而产生的争议将不断增多,中国国际经济贸易仲裁委员会和香港国际仲裁中心于2002年2月27日联合成立了亚洲域名争议解决中心。该中心已被 The Int...鉴于预期全世界因域名抢注(据报道,自2001年1月1日至2002年2月20日,约有8000多个域名被注册)而产生的争议将不断增多,中国国际经济贸易仲裁委员会和香港国际仲裁中心于2002年2月27日联合成立了亚洲域名争议解决中心。该中心已被 The InternetCorporation for Assigned Names and Numbers(ICANN)指定为全球仅有的四家域名争议解决服务提供机构之一,负责处理互联网络域名注册及使用而产生的争议。在当天举行的新同发布会上。展开更多
[Objective] The paper is to analyze physical quantities and radar parameter of hail shooting and heavy convective rainfall weather. [Method] Using radar data of Jinan station during 2002 and 2008, combined with soundi...[Objective] The paper is to analyze physical quantities and radar parameter of hail shooting and heavy convective rainfall weather. [Method] Using radar data of Jinan station during 2002 and 2008, combined with sounding data, the physical quantities and radar parameter of hail shooting and heavy convective rainfall weather are compared and analyzed. [Result] The smaller Sl is conducive to the generation of hail weather. When K〉 35 ~C, the probability for occurrence of heavy rainfall weather is significantly increased; when K〈20 ^（3, the probability for occurrence of heavy rainfall weather is significantly decreased. When CAPE value is greater than 1 500 J/KG, the probability for occurrence of hail weather is significantly decreased, while the probability for occurrence of heavy rainfall weather is significantly in- creased. The possibility for occurrence of hail monomer is small when the wind shear is less than 5 m/s; and it is large while wind shear is greater than 20 m/s. The radar forecasting indexes of hail monomer is as follows： VIL value reaches 35 kg/m2 （May）, 43 kg/m2 （June and July）, the monomer height is greater than 9 km, the maximum reflectivity factor is larger than 60 dBz, strong center height reaches 3.3 km （May）, 4.3 km （June） and 5.5 km （July）; VlL value of heavy rainfall monomer generally is below 25 kg/m2. [Conclusion] The paper provides basis form prediction of hail and heavy rainfall.展开更多
基金Supported by the National Nature Science Foundation of China(10472046)the Scientific Innova-tion Research of College Graduate in Jiangsu Province(CX08B-035Z)the Innovation and Excellence Foundation of Doctoral Dissertation of Nanjing University of Aeronautics and Astronautics(BCXJ08-01)~~
文摘A two-dimensional（2-D） incompressible plane jet is investigated using the lattice Boltzmann method（LBM） for low Reynolds numbers of 42 and 65 based on the jet-exit-width and the maximum jet-exit-velocity. The results show that the mean centerline velocity decays as x-1/3 and the jet spreads as x2/3 in the self-similar region, which are consistent with the theoretical predictions and the experimental data. The time histories and PSD analyses of the instantaneous centerline velocities indicate the periodic behavior and the interaction between periodic components of velocities should not be neglected in the far field region, although it is invisible in the near field region.
文摘In order to suppress the speckle appearing in synthesis aperture radar (SAR) images, a novel speckle reduction method based on wavelet domain hidden Markov tree (HMT) was proposed. First, the image was logarithmic transformed to change the statistical property of the speckles. Then an HMT was constructed in the correspondent wavelet domain. Based on this model, the image signal was restored by maximum likelihood estimation and speckle noise was suppressed. Simulating SAR images had shown that the performance of the filter is satisfactory for both speckle smoothing and edges presentation, and for generating visually natural images as well.
文摘Adult male rats were treated orally with monomer T_4(Tripchlorolide) isolated from Tripterygium wilfordii, at the dose of 50μg/kg/day,6 days/week for6 weeks.Ultrathin section and freeze etching replica of seminiferous tubules and epididymal spermatozoa were examined with elec-tron microscope. The results showed that the spemiogenesis was inhibited T_4 in seminiferous tu-bules. However,the damage and disruption of the spermatozoa were more serious in the epididymis.Damage of the structure and function ot microtubule and microfilament may be the chief reason for sperm damage. Sperm membrane was also very sensitive to the treatiment of monomer T_4.
文摘The combat survivability is an essential factor to be considered in the development of recent military aircraft. Radar stealth and onboard electronic attack are two major techniques for the reduction of aircraft susceptibility. A tactical scenario for a strike mission is presented. The effect of aircraft radar cross section on the detection probability of a threat radar, as well as that of onboard jammer, are investigated. The guidance errors of radar guided surface to air missile and anti aircraft artillery, which are disturbed by radar cross section reduction or jammer radiated power and both of them are determined. The probability of aircraft kill given a single shot is calculated and finally the sortie survivability of an attack aircraft in a supposed hostile thread environment worked out. It is demonstrated that the survivability of a combat aircraft will be greatly enhanced by the combined radar stealth and onboard electronic attack, and the evaluation metho dology is effective and applicable.
文摘鉴于预期全世界因域名抢注(据报道,自2001年1月1日至2002年2月20日,约有8000多个域名被注册)而产生的争议将不断增多,中国国际经济贸易仲裁委员会和香港国际仲裁中心于2002年2月27日联合成立了亚洲域名争议解决中心。该中心已被 The InternetCorporation for Assigned Names and Numbers(ICANN)指定为全球仅有的四家域名争议解决服务提供机构之一,负责处理互联网络域名注册及使用而产生的争议。在当天举行的新同发布会上。
基金Supported by Science and Technology Development Project of Shandong Science and Technology Hall(2010GSF10805)National Natural Science Foundation of China(41140036)~~
文摘[Objective] The paper is to analyze physical quantities and radar parameter of hail shooting and heavy convective rainfall weather. [Method] Using radar data of Jinan station during 2002 and 2008, combined with sounding data, the physical quantities and radar parameter of hail shooting and heavy convective rainfall weather are compared and analyzed. [Result] The smaller Sl is conducive to the generation of hail weather. When K〉 35 ~C, the probability for occurrence of heavy rainfall weather is significantly increased; when K〈20 ^（3, the probability for occurrence of heavy rainfall weather is significantly decreased. When CAPE value is greater than 1 500 J/KG, the probability for occurrence of hail weather is significantly decreased, while the probability for occurrence of heavy rainfall weather is significantly in- creased. The possibility for occurrence of hail monomer is small when the wind shear is less than 5 m/s; and it is large while wind shear is greater than 20 m/s. The radar forecasting indexes of hail monomer is as follows： VIL value reaches 35 kg/m2 （May）, 43 kg/m2 （June and July）, the monomer height is greater than 9 km, the maximum reflectivity factor is larger than 60 dBz, strong center height reaches 3.3 km （May）, 4.3 km （June） and 5.5 km （July）; VlL value of heavy rainfall monomer generally is below 25 kg/m2. [Conclusion] The paper provides basis form prediction of hail and heavy rainfall.
