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学者姓名：王民
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摘要 ：
With the development of space technology, the large scale space deployable antennas gradually become one of the key research themes of research. The basic requirements for large scale satellite antennas are the characteristics of light in weight and high in profile accuracy. The low-frequency and large-amplitude vibration of the large scale antennas is easily excited when working in an environment with zero gravity. In order to suppress the vibration of large scale deployable satellite antenna, a new type of damping mechanism with resetting capability is presented to improve the ability of vibration energy consumption and ensure the dynamic characteristics of the radial rib structure containing the presented profile accuracy of the antenna. The rod making up the deployment mechanism of the antennas is divided into two parts which connected by using the shape memory alloy (SMA) wires through guiding mechanism. Meanwhile, a metal rubber is fixed and pressed between two parts of the rod by SMA wires. The ability of the friction energy dissipation of the metal rubber is utilized to suppress the axial vibration of the rods. The super elasticity of the SMA wires is used to provide the restoring force for ensuring the dimensional stability of the rod. In this paper, the design principle of the axial self-resetting damping structure is introduced in detail. And, the dynamic characteristics of the radial rib structure containing the presented damping mechanism are investigated by using the software ANSYS. The simulation results show that the vibration amplitude of the radial rib of antennas has been reduced significantly. © Published under licence by IOP Publishing Ltd.
关键词 ：
Scales (weighing instruments) Scales (weighing instruments) Energy utilization Energy utilization Rubber Rubber Energy dissipation Energy dissipation Satellite antennas Satellite antennas Dynamics Dynamics Vibration control Vibration control Satellites Satellites Wire Wire Damping Damping Shape-memory alloy Shape-memory alloy
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| GB/T 7714 | Wang, Min , Liu, Jiaxing , Liu, Qinda et al. Research on Damping Mechanism with Resetting Capability for Axial Vibration Control of Satellite Antenna [C] . 2021 . |
| MLA | Wang, Min et al. "Research on Damping Mechanism with Resetting Capability for Axial Vibration Control of Satellite Antenna" . (2021) . |
| APA | Wang, Min , Liu, Jiaxing , Liu, Qinda , Zhao, Tingting , Zhang, Yunfei . Research on Damping Mechanism with Resetting Capability for Axial Vibration Control of Satellite Antenna . (2021) . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
在滚珠丝杠副运动过程中,滚珠与滚道之间的摩擦和磨损导致滚珠丝杠副精度衰退,降低其精度保持性.针对高速滚珠丝杠副螺旋线滚道接触区域的非对称性,采用传统的赫兹接触理论对丝杠和螺母滚道接触几何形状和关系的计算存在较大误差,提出了一种基于最小余能原理对高速滚珠丝杠副滚珠与滚道之间的法向接触应力进行分析计算的方法.首先,基于Frenet-Serret坐标转换公式建立滚珠丝杠副坐标系,对滚珠与滚道接触点处的接触情况进行几何描述,并通过2维插值算法重新进行网格划分以便于后续的接触力学分析;对滚珠与滚道之间的接触区域和控制方程进行离散化分析,提高数值计算的精确性;为了解决接触问题计算求解过程复杂、收敛速度缓慢,通过运用变分原理将接触问题转成极值问题,采用共扼梯度法进行循环迭代来实现快速收敛求解,提高接触数值解法的计算效率,求解出滚珠与滚道之间的接触应力分布;由于接触表面变形的计算相当于求影响系数矩阵与法向压应力之间的卷积,2维卷积运算和对应的2维快速傅里叶变换被用于求解接触问题的数值解.在数值求解中,主要的计算量集中在弹性变形的计算上,使用2维快速傅里叶变换(FFT)技术方便快速地计算接触区域弹性变形.将最小余能原理与赫兹接触理论分别用于求解光滑的球与平面之间的弹性接触应力分布,将两种计算方法得出的结果进行对比,计算数值重合度很好,验证了基于最小余能原理求解接触应力分布的正确性;基于最小余能原理分析螺旋升角对滚珠与滚道接触点处的接触面积和弹性变形的影响,并将该方法所得结果与赫兹接触理论计算结果进行对比分析,发现赫兹接触解与最小余能非赫兹接触精确解相比,随着滚珠丝杠副滚道螺旋升角的增大,丝杠与滚珠接触点A处的误差始终大于螺母与滚珠接触点B处的误差,丝杠滚道与滚珠接触点A处非赫兹解接触应力峰值逐渐变小,螺母滚道与滚珠接触点B处非赫兹解接触应力峰值逐渐增大,且接触点A处应力峰值始终大于接触点B处峰值,计算所得滚珠与滚道接触区域的面积和长短轴有所不同.最小余能原理非赫兹接触计算方法可以准确计算滚珠和滚道接触区域应力分布,并且可以全面和准确的计算滚道磨损带的宽度和深度.研究结果表明,采用最小余能非赫兹接触解可以有效提高滚珠丝杠副接触应力分布计算精度,保证滚珠丝杠副的精度保持性.
关键词 ：
共轭梯度法 共轭梯度法 接触应力 接触应力 最小余能原理 最小余能原理 滚珠丝杠副 滚珠丝杠副 赫兹接触 赫兹接触
引用：
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| GB/T 7714 | 王民 , 孙铁伟 , 董朝阳 et al. 高速滚珠丝杠副非赫兹接触应力计算 [J]. | 工程科学与技术 , 2021 , 53 (2) : 178-186 . |
| MLA | 王民 et al. "高速滚珠丝杠副非赫兹接触应力计算" . | 工程科学与技术 53 . 2 (2021) : 178-186 . |
| APA | 王民 , 孙铁伟 , 董朝阳 , 孔德顺 , 高相胜 . 高速滚珠丝杠副非赫兹接触应力计算 . | 工程科学与技术 , 2021 , 53 (2) , 178-186 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Considering the complexity geometry and thin wall feature, the semiconical shell workpiece will induce complicated and intense vibration in the milling process leading to poor surface quality and large machining deformation. In order to suppress the vibration, this paper focused on the semiconical shell workpiece and proposed a multiple distribution tuned mass damper (MDTMD) vibration control technique by attaching a series of optimized tuned mass dampers (TMD) to each optimal position of workpiece. The vibration characteristics and modal shapes of workpiece were obtained with the use of spectro-geometric-Ritz method (SGM) and the dynamic model of workpiece with MDTMD was established. A novel design of TMD was proposed. The optimal parameters and positions of each TMD were determined simultaneously using numerical optimization algorithm based on the modal summation method. Theoretical studies and experiment results shown that the proposed MDTMD method can remarkably improve the dynamic stiffness of the workpiece. The performance of vibration suppression is further verified in the impact tests and milling experiments.
关键词 ：
Milling vibration control Milling vibration control Multiple distribution tuned mass damper Multiple distribution tuned mass damper Semiconical shell workpiece Semiconical shell workpiece Spectro-geometric-Ritz method Spectro-geometric-Ritz method
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| GB/T 7714 | Qin, Peng , Liu, Yunan , Wang, Min et al. Milling vibration control of semiconical shell workpiece with multiple distribution tuned mass dampers [J]. | INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY , 2021 , 115 (7-8) : 2175-2190 . |
| MLA | Qin, Peng et al. "Milling vibration control of semiconical shell workpiece with multiple distribution tuned mass dampers" . | INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 115 . 7-8 (2021) : 2175-2190 . |
| APA | Qin, Peng , Liu, Yunan , Wang, Min , Zhang, Yanlin . Milling vibration control of semiconical shell workpiece with multiple distribution tuned mass dampers . | INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY , 2021 , 115 (7-8) , 2175-2190 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
高速滚珠丝杠副非赫兹接触应力计算
关键词 ：
接触应力 接触应力 最小余能原理 最小余能原理 赫兹接触 赫兹接触 共轭梯度法 共轭梯度法 滚珠丝杠副 滚珠丝杠副
引用：
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| GB/T 7714 | 王民 , 孙铁伟 , 董朝阳 et al. 高速滚珠丝杠副非赫兹接触应力计算 [J]. | 王民 , 2021 , 53 (2) : 178-186 . |
| MLA | 王民 et al. "高速滚珠丝杠副非赫兹接触应力计算" . | 王民 53 . 2 (2021) : 178-186 . |
| APA | 王民 , 孙铁伟 , 董朝阳 , 孔德顺 , 高相胜 , 工程科学与技术 . 高速滚珠丝杠副非赫兹接触应力计算 . | 王民 , 2021 , 53 (2) , 178-186 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
It is well-known that second-order optimizer can accelerate the training of deep neural networks, however, the huge computation cost of second-order optimization makes it impractical to apply in real practice. In order to reduce the cost, many methods have been proposed to approximate a second-order matrix. Inspired by KFAC, we propose a novel Trace-based Hardware-driven layer-ORiented Natural Gradient Descent Computation method, called THOR, to make the second-order optimization applicable in the real application models. Specifically, we gradually increase the update interval and use the matrix trace to determine which blocks of Fisher Information Matrix (FIM) need to be updated. Moreover, by resorting the power of hardware, we have designed a hardware-driven approximation method for computing FIM to achieve better performance. To demonstrate the effectiveness of THOR, we have conducted extensive experiments. The results show that training ResNet-50 on ImageNet with THOR only takes 66.7 minutes to achieve a top-1 accuracy of 75.9 % under an 8 Ascend 910 environment with MindSpore, a new deep learning computing framework. Moreover, with more computational resources, THOR can only takes 2.7 minutes to 75.9 % with 256 Ascend 910.
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| GB/T 7714 | Chen, Mengyun , Gao, Kaixin , Liu, Xiaolei et al. THOR, Trace-Based Hardware-Driven Layer-Oriented Natural Gradient Descent Computation [C] . 2021 : 7046-7054 . |
| MLA | Chen, Mengyun et al. "THOR, Trace-Based Hardware-Driven Layer-Oriented Natural Gradient Descent Computation" . (2021) : 7046-7054 . |
| APA | Chen, Mengyun , Gao, Kaixin , Liu, Xiaolei , Wang, Zidong , Ni, Ningxi , Zhang, Qian et al. THOR, Trace-Based Hardware-Driven Layer-Oriented Natural Gradient Descent Computation . (2021) : 7046-7054 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
This paper investigates the equivalent viscoelastic behavior of granite after different high-temperature treatments under stress waves. The equivalent viscoelastic behavior of granite after different high-temperature treatments under dynamic conditions was investigated by the pendulum impact test, while its quasi-static behavior was investigated by the uniaxial compression test. The attenuation coefficient, wave number, storage modulus and loss modulus of granite after high-temperature treatments were determined based on the pendulum impact test. A modified three-element model was proposed to describe the relationship between the equivalent viscoelastic behavior of granite and temperature. The proposed model was validated by comparing the storage modulus and loss modulus predicted by the proposed model and those based on the pendulum impact test. The results show that the attenuation coefficient and wave number increase as temperature increases. While the storage modulus and loss modulus decrease as the temperature increases. The proposed model could describe the storage modulus and loss modulus of granite after high-temperature treatment with acceptable accuracy.
关键词 ：
Equivalent viscoelastic model Equivalent viscoelastic model Granite Granite High temperature High temperature Stress wave propagation Stress wave propagation Viscoelastic behavior Viscoelastic behavior
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| GB/T 7714 | Fan, L. F. , Yang, Q. H. , Wang, M. et al. Equivalent Viscoelastic Behavior of High-Temperature Granite Under Seismic Wave [J]. | ROCK MECHANICS AND ROCK ENGINEERING , 2021 . |
| MLA | Fan, L. F. et al. "Equivalent Viscoelastic Behavior of High-Temperature Granite Under Seismic Wave" . | ROCK MECHANICS AND ROCK ENGINEERING (2021) . |
| APA | Fan, L. F. , Yang, Q. H. , Wang, M. , Du, X. L. . Equivalent Viscoelastic Behavior of High-Temperature Granite Under Seismic Wave . | ROCK MECHANICS AND ROCK ENGINEERING , 2021 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
When the stress wave propagates through rock mass with different wave impedances on two sides. It shows different reflection tendencies compared with the traditional study of wave propagation. A characteristic line method combined with the displacement discontinuity model was proposed to study the wave reflection through such rock mass. The effects of incident frequency, joint stiffness and wave impedance ratio on the reflection coefficient were discussed. The results show that the reflection coefficient increases as the wave impedance ratio increases. The traditional study of wave reflection can be regarded as a special case of the present study when the wave impedance ratio equals 1.0. Moreover, the difference of reflection coefficients decreases as the incident frequency increases, while increases as the joint stiffness and wave impedance ratio increase when the wave impedance ratio is larger than 1.0. When the wave impedance ratio is smaller than 1.0, the difference of reflection coefficients increases firstly and then decreases with the increase of incident frequency and joint stiffness, while decreases as the wave impedance ratio increases. For the cases of large incident frequency or small joint stiffness, the effects of wave impedance ratio can be neglected for the approximated prediction of wave reflection.
关键词 ：
> > amplitude attenuation amplitude attenuation jointed rock mass jointed rock mass reflection coefficient<break reflection coefficient<break wave impedance ratio wave impedance ratio Wave reflection Wave reflection
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| GB/T 7714 | Wang, L. J. , Wu, C. Q. , Fan, L. F. et al. Investigation of wave reflection at the joint with different wave impedances on two sides [J]. | WAVES IN RANDOM AND COMPLEX MEDIA , 2021 . |
| MLA | Wang, L. J. et al. "Investigation of wave reflection at the joint with different wave impedances on two sides" . | WAVES IN RANDOM AND COMPLEX MEDIA (2021) . |
| APA | Wang, L. J. , Wu, C. Q. , Fan, L. F. , Wang, M. . Investigation of wave reflection at the joint with different wave impedances on two sides . | WAVES IN RANDOM AND COMPLEX MEDIA , 2021 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
This paper presents an investigation of wave propagation through granite after different high-temperature treatments by using a pendulum impact setup. Propagation coefficients (attenuation coefficient and wave number) were successfully introduced to describe the attenuation of longitudinal waves through granite after high-temperature treatment. The attenuation rate of the longitudinal wave through the granite after different high-temperature treatments was obtained. In addition, the effects of temperature, amplitude and wavelength of longitudinal waves on the propagation coefficient and attenuation rate were discussed. The experimental results show that the propagation coefficient and the attenuation rate increase with increasing temperature. The attenuation rate decreases with increasing wavelength, while the propagation coefficient is not influenced by the wavelength. Meanwhile, the propagation coefficient and the attenuation rate are not influenced by the amplitude of the longitudinal wave.
关键词 ：
Attenuation rate Attenuation rate High-temperature treatment High-temperature treatment Pendulum impact setup Pendulum impact setup Propagation coefficient Propagation coefficient Wave propagation Wave propagation
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| GB/T 7714 | Fan, L. F. , Yang, K. C. , Wang, M. et al. Experimental study on wave propagation through granite after high-temperature treatment [J]. | INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES , 2021 , 148 . |
| MLA | Fan, L. F. et al. "Experimental study on wave propagation through granite after high-temperature treatment" . | INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES 148 (2021) . |
| APA | Fan, L. F. , Yang, K. C. , Wang, M. , Wang, L. J. , Wu, Z. J. . Experimental study on wave propagation through granite after high-temperature treatment . | INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES , 2021 , 148 . |
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摘要 ：
Mild cognitive impairment (MCI) detection using magnetic resonance image (MRI), plays a crucial role in the treatment of dementia disease at an early stage. Deep learning architecture produces impressive results in such research. Algorithms require a large number of annotated datasets for training the model. In this study, we overcome this issue by using layer-wise transfer learning as well as tissue segmentation of brain images to diagnose the early stage of Alzheimer's disease (AD). In layer-wise transfer learning, we used the VGG architecture family with pre-trained weights. The proposed model segregates between normal control (NC), the early mild cognitive impairment (EMCI), the late mild cognitive impairment (LMCI), and the AD. In this paper, 85 NC patients, 70 EMCI, 70 LMCI, and 75 AD patients access form the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Tissue segmentation was applied on each subject to extract the gray matter (GM) tissue. In order to check the validity, the proposed method is tested on preprocessing data and achieved the highest rates of the classification accuracy on AD vs NC is 98.73%, also distinguish between EMCI vs LMCI patients testing accuracy 83.72%, whereas remaining classes accuracy is more than 80%. Finally, we provide a comparative analysis with other studies which shows that the proposed model outperformed the state-of-the-art models in terms of testing accuracy.
关键词 ：
Alzheimer’s disease Alzheimer’s disease Early diagnosis Early diagnosis Image classification Image classification Transfer learning Transfer learning
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| GB/T 7714 | Mehmood Atif , Yang Shuyuan , Feng Zhixi et al. A Transfer Learning Approach for Early Diagnosis of Alzheimer's Disease on MRI Images. [J]. | Neuroscience , 2021 , 460 : 43-52 . |
| MLA | Mehmood Atif et al. "A Transfer Learning Approach for Early Diagnosis of Alzheimer's Disease on MRI Images." . | Neuroscience 460 (2021) : 43-52 . |
| APA | Mehmood Atif , Yang Shuyuan , Feng Zhixi , Wang Min , Ahmad Al Smadi , Khan Rizwan et al. A Transfer Learning Approach for Early Diagnosis of Alzheimer's Disease on MRI Images. . | Neuroscience , 2021 , 460 , 43-52 . |
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摘要 ：
The overall dynamic mechanical behavior of a double-scale discontinuous rock mass with a nonlinear deformational macrojoint was investigated. A method of combining the split three characteristic lines with the piecewise linear displacement discontinuity model (DDM) was proposed. The method was applied to investigate the transmission coefficient of P-wave propagation normally through a double-scale discontinuous rock mass with a nonlinear deformational macrojoint. The results were verified by comparison with the results of P-wave propagation normally through a double-scale discontinuous rock mass with a linear deformational macrojoint. The results showed that for a small amplitude stress wave, the nonlinear deformational macrojoint can be simplified as a linear deformational form to study the stress wave propagation, whereas for a large amplitude stress wave, the effects of the nonlinear deformational behavior of the macrojoint must be considered. The difference of the effects of nonlinear and linear deformational macrojoints on large amplitude stress wave propagation can be overlooked in the low-frequency or high-frequency regions. In addition, when the incident stress wave amplitude and initial macrojoint stiffness are sufficiently large, the effects of the nonlinear deformational macrojoint on stress wave propagation can be overlooked, and the effects of microdefects must be considered. The influence degree of microdefects on the stress wave propagation increases with the increase of incident stress wave frequency. © 2020, Springer-Verlag GmbH Austria, part of Springer Nature.
关键词 ：
Piecewise linear techniques Piecewise linear techniques Rock mechanics Rock mechanics Rocks Rocks Seismic waves Seismic waves Wave propagation Wave propagation
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| GB/T 7714 | Fan, L.F. , Wang, M. , Wu, Z.J. . Effect of Nonlinear Deformational Macrojoint on Stress Wave Propagation Through a Double-Scale Discontinuous Rock Mass [J]. | Rock Mechanics and Rock Engineering , 2021 , 54 (3) : 1077-1090 . |
| MLA | Fan, L.F. et al. "Effect of Nonlinear Deformational Macrojoint on Stress Wave Propagation Through a Double-Scale Discontinuous Rock Mass" . | Rock Mechanics and Rock Engineering 54 . 3 (2021) : 1077-1090 . |
| APA | Fan, L.F. , Wang, M. , Wu, Z.J. . Effect of Nonlinear Deformational Macrojoint on Stress Wave Propagation Through a Double-Scale Discontinuous Rock Mass . | Rock Mechanics and Rock Engineering , 2021 , 54 (3) , 1077-1090 . |
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