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Approximate ballistics formulas for spherical pellets in free flight 被引量:2
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作者 e.j.allen 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2018年第1期1-11,共11页
The ballistics equations for spherical pellets in free flight are simplified through appropriate scaling of the pellet velocity and pellet distance. Two different drag coefficient curves are averaged to yield a single... The ballistics equations for spherical pellets in free flight are simplified through appropriate scaling of the pellet velocity and pellet distance. Two different drag coefficient curves are averaged to yield a single curve applicable to shot pellets and round balls. The resulting S-shaped drag coefficient curve is approximated by three straight-line segments. The scaled ballistics equations are then solved exactly and simple formulas are found for the velocity and flight time with respect to trajectory distance. The formulas are applicable to spherical shot pellets and round balls of any composition under any atmospheric conditions. The formulas are amenable to quick and easy computation and may also serve as an aid in understanding and comparing black-box ballistics calculators. For shotshell ballistics, an important assumption in the present investigation is that the pellets are moving as single, free spheres and not as a dense cloud or in a shot column, in particular, the pellets are not interacting during flight. Therefore, the formulas are most appropriate for single round balls, for large shot sizes, and for pellets of small shot size fired from open chokes. The formulas are clear and accessible, and can be implemented by military or law enforcement personnel as well as hunters and shooters. This work differs from previous investigations in that accurate ballistics formulas are derived for spherical projectiles of shotguns and muzzleloaders using realistic drag coefficients. 展开更多
关键词 BALLISTICS SPHERE Drag SHOTGUN Muzzleloader Nondimensionalization
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以马铃薯的叶长估算其个体叶面积
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作者 D.M.Firman e.j.allen 李艳英 《河南科技大学学报(农学版)》 1990年第3期34-34,27,共2页
在作物上,个体叶面积的测量在分析作物郁蔽程度方面是很有用处的,因这些测量可确定叶面积系数的空间构成。这个资料可用于叶的生长标准和在个体发育中不同层次、不同郁蔽程度光合势的评定。(参阅Firman和Allen 1988)
关键词 叶面积系数 叶长 测量 生长标准 个体发育 估算 试验组合 光合势 作物 马铃薯
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