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Analysis of Coordinated Steering Performance in Multi-wheel Landing Gears
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作者 gui xiwen ZHANG Ming +2 位作者 SHI Xiazheng HU Tianyang XU Yuhan 《Transactions of Nanjing University of Aeronautics and Astronautics》 2025年第5期659-678,共20页
During aircraft ground steering,the nose landing gear(NLG)tires of large transport aircraft often experience excessive lateral loads,leading to sideslip.This compromises steering safety and accelerates tire wear.To ad... During aircraft ground steering,the nose landing gear(NLG)tires of large transport aircraft often experience excessive lateral loads,leading to sideslip.This compromises steering safety and accelerates tire wear.To address this issue,the rear landing gear is typically designed to steer in coordination with the nose wheels,reducing sideslip and improving maneuverability.This study examines how structural parameters and weight distribution affect the performance of coordinated steering in landing gear design for large transport aircraft.Using the C-5 transport aircraft as a case study,we develop a multi-wheel ground steering dynamics model,incorporating the main landing gear(MLG)deflection.A ground handling dynamics model is also established to evaluate the benefits of coordinated steering for rear MLG during steering.Additionally,the study analyzes the impact of structural parameters such as stiffness and damping on the steering performance of the C-5.It further investigates the effects of weight distribution,including the center-of-gravity(CG)height,the longitudinal CG position,and the mass asymmetry.Results show that when the C-5 employs coordinated steering for rear MLG,the lateral friction coefficients of the NLG tires decrease by 22%,24%,26%,and 27%.The steering radius is reduced by 29.7%,and the NLG steering moment decreases by 19%,significantly enhancing maneuverability.Therefore,in the design of landing gear for large transport aircraft,coordinated MLG steering,along with optimal structural and CG position parameters,should be primary design objectives.These results provide theoretical guidance for the design of multi-wheel landing gear systems in large transport aircraft. 展开更多
关键词 multi-wheel landing gear coordinated steering aircraft ground steering dynamics influence law analysis
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乳腺X线图像纹理分析鉴别乳腺小结节良恶性的价值 被引量:17
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作者 彭文静 徐凯 +3 位作者 刘正立 桂熙雯 张孝庚 路欣 《中国医学影像学杂志》 CSCD 北大核心 2018年第12期890-893,898,共5页
目的探讨乳腺X线图像纹理分析对乳腺小结节良恶性的鉴别诊断价值。资料与方法回顾性分析2015年1月-2016年12月徐州医科大学附属医院收治的219例乳腺疾病患者的X线及临床资料,共计230枚直径<2 cm的乳腺结节,并根据病理结果分为良性组... 目的探讨乳腺X线图像纹理分析对乳腺小结节良恶性的鉴别诊断价值。资料与方法回顾性分析2015年1月-2016年12月徐州医科大学附属医院收治的219例乳腺疾病患者的X线及临床资料,共计230枚直径<2 cm的乳腺结节,并根据病理结果分为良性组和恶性组。使用FireVoxel纹理分析软件勾画感兴趣区并提取纹理参数。分析各纹理参数对小结节良恶性的鉴别效能。结果良性组和恶性组均值、偏度和峰度差异无统计学意义(P>0.05);标准偏差、不均匀度和熵可有效区分良、恶性乳腺小结节,差异有统计学意义(P<0.001),三者诊断恶性肿块的受试者工作特性曲线下面积分别为0.641、0.645和0.681(P<0.001),以熵的鉴别效能最佳。多种纹理参数联合可以提高单一参数的鉴别效能;乳腺X线联合纹理特征可将单一乳腺X线诊断小乳癌的敏感度从75.2%提升至82.2%,准确度从82.6%提升至84.8%,差异均有统计学意义(P<0.05)。结论熵可成为乳腺X线纹理分析鉴别乳腺小结节良恶性的最佳单一纹理指标。乳腺X线联合纹理特征可以提高单一X线诊断小乳癌的敏感度和准确度。 展开更多
关键词 乳腺肿瘤 乳房X线摄影术 诊断 鉴别
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