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朱石坚 《海军工程大学学报》1994,(2)
本文将桁架式水塔结构等效成单自由度弹簧质量系统,考虑其在风载(包括定常与随机波动两部分)作用下,以桁架中的最大应力及频率耦合等作为约束条件的优化设计问题,导出了设计变量的最优化设计数学模型。 相似文献
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Because of the complexities of tire-road interaction,the wheels of a multi-wheel distributed electric drive vehicle can easily slip under certain working conditions.As wheel slip affects the dynamic per-formance and stability of the vehicle,it is crucial to control it and coordinate the driving force.With this aim,this paper presents a driving force coordination control strategy with road identification for eight-wheeled electric vehicles equipped with an in-wheel motor for each wheel.In the proposed control strategy,the road identification module estimates tire-road forces using an unscented Kalman filter al-gorithm and recognizes the road adhesion coefficient by employing the recursive least-square method.According to road identification,the optimal slip ratio under the current driving condition is obtained,and a controller based on sliding mode control with a conditional integrator uses this value for accel-eration slip regulation.The anti-slip controller obtains the adjusting torque,which is integrated with the driver-command-based feedforward control torque to implement driving force coordination control.The results of hardware-in-loop simulation show that this control strategy can accurately estimate tire-road forces as well as the friction coefficient,and thus,can effectively fulfill the purpose of driving force coordinated control under different driving conditions. 相似文献
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《防务技术》2022,18(9):1589-1601
Infrared (IR) small target detection is one of the key technologies of infrared search and track (IRST) systems. Existing methods have some limitations in detection performance, especially when the target size is irregular or the background is complex. In this paper, we propose a pixel-level local contrast measure (PLLCM), which can subdivide small targets and backgrounds at pixel level simultaneously. With pixel-level segmentation, the difference between the target and the background becomes more obvious, which helps to improve the detection performance. First, we design a multiscale sliding window to quickly extract candidate target pixels. Then, a local window based on random walker (RW) is designed for pixel-level target segmentation. After that, PLLCM incorporating probability weights and scale constraints is proposed to accurately measure local contrast and suppress various types of background interference. Finally, an adaptive threshold operation is applied to separate the target from the PLLCM enhanced map. Experimental results show that the proposed method has a higher detection rate and a lower false alarm rate than the baseline algorithms, while achieving a high speed. 相似文献
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本文讨论基于条件事件代数系统上的条件随机变量的表示问题,并给出了在多个信息源提供的不同类型的条件数据时之统一表示方法,以及利用条件随机变量分布函数性质,对所得数据进行关联等。 相似文献
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给出了随机截几场合下步进应力加速寿命试验(步加试验)的统计方法,并讨论了其估计的方差问题. 相似文献
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