In this study, the influence of opening parameters on the ultimate strength of perforated plates subjected to extreme cyclic loading in the presence of material kinematic hardening and isotro pic hardening was analyze...In this study, the influence of opening parameters on the ultimate strength of perforated plates subjected to extreme cyclic loading in the presence of material kinematic hardening and isotro pic hardening was analyzed. It is found that the ultimate strength of the perforated plates decreases rapidly and stabilizes in the first four cycles. Plates with oblong openings have a greater ultimate strength compared to plates with rectangular openings, while the relative strengthening ratio decreases over the duration of the cycle. The location of the openings is also an important parameter that affects the strength of the structure, as the plates with openings close to the edges in the longitudinal direction have higher strengths, while in the transverse direction the strengths are higher when the openings are close to the center. Among the three opening-strengthening methods compared, the Carling stiffener method maintains a better strengthening effect under cyclic loads for many periods.展开更多
为提高海事监测中高频地波雷达(High Frequency Surface Wave Radar,HFSWR)对运动目标的检测准确率,提出了一种基于频谱细化和小波尺度谱重排时频分析的运动目标检测算法.对HFSWR的接收信号进行频率细化处理以提高后续时频分析的频率分...为提高海事监测中高频地波雷达(High Frequency Surface Wave Radar,HFSWR)对运动目标的检测准确率,提出了一种基于频谱细化和小波尺度谱重排时频分析的运动目标检测算法.对HFSWR的接收信号进行频率细化处理以提高后续时频分析的频率分辨率;然后,进行基于Morlet小波的时频分析以提取目标的时频分布特征,为提高时频分布的集中性和抑制交叉项干扰,对小波尺度谱进行重排;根据得到的时频分布特征实现可疑目标区的精确检测.实验结果表明:该算法能有效检测多普勒频率相差很小的运动目标以及海杂波附近的运动目标,可用于对常规目标检测算法无法判定的可疑目标区域进行精细、准确的目标检测与分析.展开更多
本文采用有限元法与强度稳定综合理论(combined theory of strength and stability,CTSS)公式研究箱型梁的极限强度问题。揭示了有限元计算方法的不稳定性,结合Vasta的始屈弯矩法提出箱型梁结构的极限弯矩简化计算公式。通过两个箱型梁...本文采用有限元法与强度稳定综合理论(combined theory of strength and stability,CTSS)公式研究箱型梁的极限强度问题。揭示了有限元计算方法的不稳定性,结合Vasta的始屈弯矩法提出箱型梁结构的极限弯矩简化计算公式。通过两个箱型梁结构的实例计算表明,该公式的计算结果相对于试验结果的误差在10%以内,且与非线性有限元法相比有着简单、稳定的优势,可以为工程设计提供参考。展开更多
文摘In this study, the influence of opening parameters on the ultimate strength of perforated plates subjected to extreme cyclic loading in the presence of material kinematic hardening and isotro pic hardening was analyzed. It is found that the ultimate strength of the perforated plates decreases rapidly and stabilizes in the first four cycles. Plates with oblong openings have a greater ultimate strength compared to plates with rectangular openings, while the relative strengthening ratio decreases over the duration of the cycle. The location of the openings is also an important parameter that affects the strength of the structure, as the plates with openings close to the edges in the longitudinal direction have higher strengths, while in the transverse direction the strengths are higher when the openings are close to the center. Among the three opening-strengthening methods compared, the Carling stiffener method maintains a better strengthening effect under cyclic loads for many periods.
文摘为提高海事监测中高频地波雷达(High Frequency Surface Wave Radar,HFSWR)对运动目标的检测准确率,提出了一种基于频谱细化和小波尺度谱重排时频分析的运动目标检测算法.对HFSWR的接收信号进行频率细化处理以提高后续时频分析的频率分辨率;然后,进行基于Morlet小波的时频分析以提取目标的时频分布特征,为提高时频分布的集中性和抑制交叉项干扰,对小波尺度谱进行重排;根据得到的时频分布特征实现可疑目标区的精确检测.实验结果表明:该算法能有效检测多普勒频率相差很小的运动目标以及海杂波附近的运动目标,可用于对常规目标检测算法无法判定的可疑目标区域进行精细、准确的目标检测与分析.
文摘本文采用有限元法与强度稳定综合理论(combined theory of strength and stability,CTSS)公式研究箱型梁的极限强度问题。揭示了有限元计算方法的不稳定性,结合Vasta的始屈弯矩法提出箱型梁结构的极限弯矩简化计算公式。通过两个箱型梁结构的实例计算表明,该公式的计算结果相对于试验结果的误差在10%以内,且与非线性有限元法相比有着简单、稳定的优势,可以为工程设计提供参考。
