基于倾角的激光引信定高修正方法

安装激光定距引信的伞降空炸子母弹,降落时受气流影响呈倾斜降落姿态,引起激光引信在同等高度上的光程变长,导致实际空炸高度低于所装定的最佳高度。为修正因弹体倾斜而出现的定高误差,提出一种通过测弹轴倾角来修正子母弹定高高度的方法,文中分析了单、双轴两种定高修正模式。实验结果表明,当弹轴倾角低于50°时,修正值误差不超过8.1%。此方法在修正子母弹空炸高度研究领域中具有一定的可行性。

Determination of fractional energy loss of waves in nearshore waters using an improved high-order Boussinesq-type model

Fractional energy losses of waves due to wave breaking when passing over a submerged bar are studied systematically using a modified numerical code that is based on the high-order Boussinesq-type equations.The model is first tested by the additional experimental data,and the model's capability of simulating the wave transformation over both gentle slope and steep slope is demonstrated.Then,the model's breaking index is replaced and tested.The new breaking index,which is optimized from the several breaking indices,is not sensitive to the spatial grid length and includes the bottom slopes.Numerical tests show that the modified model with the new breaking index is more stable and efficient for the shallow-water wave breaking.Finally,the modified model is used to study the fractional energy losses for the regular waves propagating and breaking over a submerged bar.Our results have revealed that how the nonlinearity and the dispersion of the incident waves as well as the dimensionless bar height(normalized by water depth) dominate the fractional energy losses.It is also found that the bar slope(limited to gentle slopes that less than 1:10) and the dimensionless bar length(normalized by incident wave length) have negligible effects on the fractional energy losses.