direction ray目标射线directionn.方向；指导；用法说明；趋势；目标；管理Direction - of - Arrival波达方向（DOA）directional response pattern方向对应图形directional frequency vector方位频率矢量direction of national spirit民族精神导向directionally differentiable方向可导directional penetration depth方向穿透深度directional churning jet pile定向旋喷桩direction and characteristics方向与特色directional distance function方向性距离函数directional duality principle方向对偶原则