利用无人机桥梁病害检测机器视觉系统,可获取大量桥梁混凝土表面病害数据。针对桥梁病害尺寸细长特点,引入实例分割YOLOv7_Seg(You Only Look Once V7_segmentation)网络,并对网络进行轻量级可变形卷积改进,拓宽小目标缺陷的感受野,有...利用无人机桥梁病害检测机器视觉系统,可获取大量桥梁混凝土表面病害数据。针对桥梁病害尺寸细长特点,引入实例分割YOLOv7_Seg(You Only Look Once V7_segmentation)网络,并对网络进行轻量级可变形卷积改进,拓宽小目标缺陷的感受野,有效增强小尺度缺陷特征,实现露筋、破损、蜂窝麻面、裂缝4种桥梁病害的分割与识别;以跨江大桥为例,利用无人机采集病害数据,并使用训练好的模型进行实例分割。结果表明,所提出的系统和方法具有较高识别准确性及广阔应用前景。展开更多
针对Aster导弹在PIF(pilotage inertial enforce)-PAF(puissance an frein)控制中的动力学问题,分析了侧向推力对导弹法向力、俯仰力矩、控制力的影响,建立了PIF-PAF控制导弹的纵向运动模型,采用小扰动线性化方法得到了PIF-PAF控制导弹...针对Aster导弹在PIF(pilotage inertial enforce)-PAF(puissance an frein)控制中的动力学问题,分析了侧向推力对导弹法向力、俯仰力矩、控制力的影响,建立了PIF-PAF控制导弹的纵向运动模型,采用小扰动线性化方法得到了PIF-PAF控制导弹的纵向扰动运动模型以及短周期运动模型。探讨了PIF-PAF控制提升过载响应时间的原理。解释了Aster导弹采用大面积弹翼、大面积舵面并将弹翼前缘后掠角设计为零的原因。展开更多
Two-dimensional （2D） materials have become a hot study topic in recent years due to their outstanding electronic, optical, and thermal properties. The unique band structures of strong in-plane chemical bonds and wea...Two-dimensional （2D） materials have become a hot study topic in recent years due to their outstanding electronic, optical, and thermal properties. The unique band structures of strong in-plane chemical bonds and weak out-of-plane van der Waals （vdW） interactions make 2D materials promising for nanodevices and various other applications. Raman spectroscopy is a powerful and non-destructive characterization tool to study the properties of 2D materials. In this work, we review the research on the characterization of 2D materials with Raman spectroscopy. In addition, we discuss the application of the Raman spectroscopy technique to semiconductors, superconductivity, photoelectricity, and thermoelectricity.展开更多
This paper studies the magnetic hysteresis and refrigeration capacity of Ni-Mn-Ga alloys in detail during heating and cooling isothermal magnetisation processes. The Ni-Mn-Ga alloys show larger magnetic hysteresis whe...This paper studies the magnetic hysteresis and refrigeration capacity of Ni-Mn-Ga alloys in detail during heating and cooling isothermal magnetisation processes. The Ni-Mn-Ga alloys show larger magnetic hysteresis when they trans-form from austenite to martensite, but smaller magnetic hysteresis when they transform from martensite to austenite. This behaviour is independent of either the pure Ni-Mn-Ga alloys or the alloys doped with other elements. Because of the existence of the magnetic hysteresis, the relation between the magnetic entropy change and refrigeration capacity is not simply linear. For practical consideration, magnetocaloric effect of Ni-Mn-Ga alloys should be investigated both on cooling and heating processes.展开更多
文摘利用无人机桥梁病害检测机器视觉系统,可获取大量桥梁混凝土表面病害数据。针对桥梁病害尺寸细长特点,引入实例分割YOLOv7_Seg(You Only Look Once V7_segmentation)网络,并对网络进行轻量级可变形卷积改进,拓宽小目标缺陷的感受野,有效增强小尺度缺陷特征,实现露筋、破损、蜂窝麻面、裂缝4种桥梁病害的分割与识别;以跨江大桥为例,利用无人机采集病害数据,并使用训练好的模型进行实例分割。结果表明,所提出的系统和方法具有较高识别准确性及广阔应用前景。
文摘针对Aster导弹在PIF(pilotage inertial enforce)-PAF(puissance an frein)控制中的动力学问题,分析了侧向推力对导弹法向力、俯仰力矩、控制力的影响,建立了PIF-PAF控制导弹的纵向运动模型,采用小扰动线性化方法得到了PIF-PAF控制导弹的纵向扰动运动模型以及短周期运动模型。探讨了PIF-PAF控制提升过载响应时间的原理。解释了Aster导弹采用大面积弹翼、大面积舵面并将弹翼前缘后掠角设计为零的原因。
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504111,61574060,and 61574056)the Projects of Science and Technology Commission of Shanghai Municipality of China(Grant Nos.15JC1401800 and 14DZ2260800)+2 种基金the Program for Professor of Special Appointment(Eastern Scholar)Shanghai Rising-Star Program,China(Grant No.17QA1401400)the Fundamental Research Funds for the Central Universities of China
文摘Two-dimensional （2D） materials have become a hot study topic in recent years due to their outstanding electronic, optical, and thermal properties. The unique band structures of strong in-plane chemical bonds and weak out-of-plane van der Waals （vdW） interactions make 2D materials promising for nanodevices and various other applications. Raman spectroscopy is a powerful and non-destructive characterization tool to study the properties of 2D materials. In this work, we review the research on the characterization of 2D materials with Raman spectroscopy. In addition, we discuss the application of the Raman spectroscopy technique to semiconductors, superconductivity, photoelectricity, and thermoelectricity.
基金supported by the National Basic Research Program of China (Grant No.2006CB601101)the National High Technology Research and Development Program of China (Grant No.2007AA03Z440)the National Natural Science Foundation of China(Grant No.50731007)
文摘This paper studies the magnetic hysteresis and refrigeration capacity of Ni-Mn-Ga alloys in detail during heating and cooling isothermal magnetisation processes. The Ni-Mn-Ga alloys show larger magnetic hysteresis when they trans-form from austenite to martensite, but smaller magnetic hysteresis when they transform from martensite to austenite. This behaviour is independent of either the pure Ni-Mn-Ga alloys or the alloys doped with other elements. Because of the existence of the magnetic hysteresis, the relation between the magnetic entropy change and refrigeration capacity is not simply linear. For practical consideration, magnetocaloric effect of Ni-Mn-Ga alloys should be investigated both on cooling and heating processes.
