Due to fewer rainfall, lean soil, serious soil and water loss and the long term negative effect of human activity, the ecological environment in hilly semi arid area is being degraded.
低山丘陵半干旱区气候干旱、土地贫瘠、水土流失严重,加上人类活动的长期负面影响,使得该地区生态环境不断恶化。
Numerical examples show that the negative semi-definite matrix condition of exponential stability and the controller design method are feasible.
数值算例说明指数稳定的半负定矩阵条件和控制器设计方法是可行的。
The X-4's primary importance involved proving a negative, in that a swept-wing semi-tailless design was not suitable for speeds near Mach 1.
的X - 4的主要参与的重要性,证明1负,在这后掠翼半尾巴设计时并没有接近1马赫的速度合适。
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