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弹道中段非旋转对称目标动态雷达散射截面仿真
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作者 张平定 孙佳佳 张鸣鸣 《科学技术与工程》 北大核心 2014年第8期23-27,35,共6页
为计算弹道中段非旋转对称目标的动态RCS,根据高频近似方法和局部场原理,分别用几何绕射理论和物理光学法对目标主体及其尾翼的RCS计算公式进行推导;然后根据中段弹道目标的运动学特性,求得其实时视角值;并根据物理光学法提出了一种判... 为计算弹道中段非旋转对称目标的动态RCS,根据高频近似方法和局部场原理,分别用几何绕射理论和物理光学法对目标主体及其尾翼的RCS计算公式进行推导;然后根据中段弹道目标的运动学特性,求得其实时视角值;并根据物理光学法提出了一种判断尾翼遮挡的方法,最终求得其动态RCS值。通过与暗室测量数据的对比,证明了所提方法的有效性。 展开更多
关键词 进动 弹道中段 雷达散射截面 非旋转对称
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He-N_2转动非弹性碰撞的理论研究
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作者 谢代前 卞新峰 唐敖庆 《高等学校化学学报》 SCIE EI CAS CSCD 北大核心 1991年第1期98-100,共3页
用CC方法计算了在BTT势能面上碰撞能为27.3 meV下He-N_2转动非弹性碰撞截面.研究表明,总的微分碰撞截面与Faubel等的实验结果相似,而态-态微分碰撞截面与实验结果符合欠佳,这与Bowers等的预言一致,
关键词 非弹性碰撞 He-N2体系 碰撞截面
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Stereodynamics of O(^3P)+H2 at Scattering Energies of 0.5, 0.75, and 1.0 eV 被引量:2
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作者 Victor Wei-keh Wu 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2010年第2期149-154,I0001,共7页
Quasiclassical trajectory calculation of the title reaction O(^3P)+H2→OH+H at three different scattering energies of 0.5, 0.75, and 1.0 eV on the lowest electronic potential energy surface 1^3A" has been done. D... Quasiclassical trajectory calculation of the title reaction O(^3P)+H2→OH+H at three different scattering energies of 0.5, 0.75, and 1.0 eV on the lowest electronic potential energy surface 1^3A" has been done. Distribution P(θr) of polar angles between the relative velocityk of the reactant and rotational angular momentum vector j' of the product, distribution P(φr) of the azimuthal as well as dihedral angles correlating k-k'-j', 3-dimensional distri-bution, and polarization-dependent differential cross sections (PDDCSs)dependent upon the scattering angle of the product molecule OH between the relative velocity k of the reactant and k' of the product at different scattering energies of 0.5, 0.75, and 1.0 eV are presented and discussed. 展开更多
关键词 Quasiclassical trajectory calculation Stereodynamics Alignment rotational angular momentum Polarization-dependent differential cross section O+H2 reaction
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Evaluation of Productive and Reproductive Performance of Cattle in Major Dairy Production Area of Chitwan and Nawalparasi Districts
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作者 Uddhav Paneru Mohan Sharma +1 位作者 Mana Raj Kolachhapati Bhola Shanker Shrestha 《Journal of Agricultural Science and Technology(A)》 2016年第1期69-75,共7页
A study was conducted to determine the productive and reproductive performance of dairy cattle reared in major milk production area of Chitwan and Nawalparasi districts of Nepal, as well as determining the existing br... A study was conducted to determine the productive and reproductive performance of dairy cattle reared in major milk production area of Chitwan and Nawalparasi districts of Nepal, as well as determining the existing breeding scenario of cattle farming followed by the farmers. Five years (2008-2012) of data of 728 animals send to data management section of Animal Breeding Division under Dairy Cattle Improvement Program (DCIP) were reviewed and analyzed. Similarly, monthly data recording of 380 animals taken from May 2012 to April 2013 were used to find out information on reproductive performance. Average milk yield, fat percentage and protein percentage of cattle were observed 2,841 ± 84.9 kg, 4.43% ± 0.66% and 3.33% ± 0.17%, respectively, and the effect of genotype on these traits were found significant (P 〈 0.001, P 〈 0.001 and P 〈 0.01, respectively). Similarly, calving interval, post-partum estrus, post-partum conception, age at maturity and age at first calving were observed 422.8 ± 7.71, 108.9 ± 6.13, 149.93 ± 27.04, 498.5 ±16.32 and 816.0 ±17.41 d, respectively. Age at maturity and age at first calving was significantly affected by genotype (P 〈 0.01 and P 〈 0.05, respectively). In addition, average number of insemination per conception was observed 1.38 in survey household. Breeding system of cattle followed by the farmers were found satisfactory in the survey household, but needs gradual improvement. It was observed that offspring of cross between Jersey and Holstein performed better in terms of productive and reproductive performance in farmer managed condition of Nepal. Therefore, rotational crossing of Jersey and Holstein for maintaining blood level between 50% and 75% of either breed is the best choice for farmers. 展开更多
关键词 Calving interval post-partum estrus rotational crossing blood level.
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