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arXiv 2019年

作者： Liu, Chang Du, Zongliang Zhu, Yichao Zhang, Weisheng Zhang, Xiaoyu Guo, Xu State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering Mechanics International Research Center for Computational Mechanics Dalian University of Technology Dalian116023 China Mechanical & Aerospace Engineering University of Missouri ColumbiaMO65211 United States Beijing Institute of Spacecraft System Engineering CAST Beijing China

In the present work, a hybrid MMC-MMV approach is developed for designing additive manufacturing-oriented shell-graded-infill structures. The key idea is to describe the geometry of a shell-graded-infill structure explicitly using some geometry parameters. To this end, a set of morphable voids is adopted to describe the boundary of the coating shell, while a set of morphable components combing with a coordinate perturbation technique are introduced to represent the graded infill distribution. Under such treatment, both the crisp boundary of the coating shell and the graded infill can be optimized simultaneously, with a small number of design variables. Numerical examples demonstrate the effectiveness of the proposed approach. Copyright © 2019, The Authors. All rights reserved.

关键词： Coatings

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Analysis and Modeling of Friction Stir Processing-Based Crack Repairing in 2024 Aluminum Alloy

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Acta Metallurgica Sinica(English Letters) 2017年第3期30卷 228-237页

作者： Jun-Gang Ren Lei Wang Dao-Kui Xu Li-Yang Xie Zhan-Chang Zhang Department of Mechanical Engineering and Automation Northeastern University Department of Electromechanical Engineering Shenyang Aerospace University Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of Sciences

Abstract A friction stir processing-based method was used to repair cracks in the 2024 aluminum alloy plates. The temperature field and plastic material flow pattern were analyzed on the basis of experimental and finite element simulation results. Microstructure and tensile properties of the repaired specimens were studied. The results showed that the entire crack repairing was a solid-phase process and plastic materials tended to flow toward the shoulder center and then resulted in the repairing of cracks. Meanwhile, the coarse grain structures were refined in repaired zone （RZ）, while the grains in thermal-mechanically affected zone and heat-affected zone were elongated and driven to grow up. Meanwhile, large phases are crushed into small particles and dispersed inside the RZ. Finally, the strength of the repaired specimens can be restored dramatically and their ductility can be partially restored. After heat treatment, the tensile properties of the repaired specimens can be further enhanced.

关键词： Friction stir processing Crack repairing Aluminum alloy Microstructure Hardness Tensile properties

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Modeling of Mars Entry Vehicles with an Internal Sole-moving-mass Actuator

Modeling of Mars Entry Vehicles with an Internal Sole-moving...

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IEEE Chinese Guidance, Navigation and Control Conference (CGNCC)

作者： Junlong Yuan Kun Ni Qingzhen Zhang Mei Lin School of Automation Science and Electrical Engineering Beihang University Beijing China System Engineering Second Research Office Beijing Institute of Aerospace Automation Beijing China

ISBN: (数字)9781538611715

ISBN: (纸本)9781538611722

This paper investigates the deployment of an internal sole-moving-mass actuator in Mars entry vehicles. Given the extreme environment of Mars atmosphere, moving mass control has gained plenty of advantages in efficiency, cost and reliability over aerodynamic flap and thruster-based control. First, a model of moving-mass dynamics is derived using Kane's Method based on the proposed moving mass configuration. In such a multi-body system, the interactions between the moving mass and the vehicle are focused on during the modeling procedure. Then, several key parameters of the moving mass configuration are determined through analysis. Finally, the manipulation characteristics are verified to ensure the capability of mission accomplishment. Simulation results indicate the applicability and effectiveness of the proposed sole-moving-mass actuator.

关键词： Mathematical model Atmospheric modeling Mars Aerodynamics Actuators Terrestrial atmosphere Vehicle dynamics

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Correction: Antibody-coated microstructures for selective isolation of immune cells in blood

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Lab on a chip 2022年第4期22卷 848页

作者： Jiyu Li Ya Liu Jifeng Ren Benjamin Zikai Tay Tao Luo Lei Fan Dong Sun Guannan Luo Denvid Lau Raymond H W Lam Department of Biomedical Engineering City University of Hong Kong Hong Kong. rhwlam@cityu.edu.hk. School of Mechanical and Aerospace Engineering Nanyang Technological University Singapore. Centre for Robotics and Automation City University of Hong Kong Hong Kong. Department of Economics and Finance City University of Hong Kong Hong Kong. Department of Architecture and Civil Engineering City University of Hong Kong Hong Kong. Centre for Biosystems Neuroscience and Nanotechnology City University of Hong Kong Hong Kong. City University of Hong Kong Shenzhen Research Institute Shenzhen China.

Correction for 'Antibody-coated microstructures for selective isolation of immune cells in blood' by Jiyu Li , , 2020, , 1072-1082, DOI: 10.1039/D0LC00078G.

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Pedestrian Dead Reckoning system Using Dual IMU to Consider Heel Strike Impact

Pedestrian Dead Reckoning System Using Dual IMU to Consider ...

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International Conference on Control, automation and systems

作者： Hojin Ju Jae Hong Lee Chan Gook Park Automation and Systems Research Institute Seoul National University Seoul Korea Department of Mechanical and Aerospace Engineering Automation and Systems Research Institute Seoul National University Seoul Korea

ISBN: (纸本)9781538670804;9788993215168

In this paper, we propose pedestrian dead-reckoning (PDR) system using shoe and calf mounting inertial measurement units (IMUs) to consider heel strike impact. Generally, PDR system with shoe mounted inertial sensors often uses zero velocity update (ZUPT) for reducing the influence of the bias and white noises in the gyroscope and accelerometer signals. However, heel strike impact causes a large acceleration and angular velocity that cannot be measured by the accelerometer and the gyroscope. Accordingly, the designed extended Kalman filter (EKF) does not correctly reflect the actual environment, because conventional algorithms do not take into consideration the non-measurable acceleration. It is also difficult to compensate for unmeasurable values if the heel strike impact is large. In order to consider heel strike impact, we proposed the PDR system using dual IMU. Calf mounted IMU is less affected by heel strike impact than shoe mounted IMU because of the damping effect by shoe insole. Therefore, the proposed algorithm uses the joint constraint between two sensors considering heel strike impact. The experimental results show improved performance by comparing the proposed algorithm and conventional algorithm.

关键词： Pedestrian dead reckoning Zero velocity update Heel strike impact Joint constraint

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Path Tracking for a Skid-steer Vehicle using Model Predictive Control with On-line Sparse Gaussian Process

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IFAC-PapersOnLine 2017年第1期50卷 5755-5760页

作者： Kim T. Kim W. Choi S. Jin Kim H. Mechanical and Aerospace Engineering Department Automation and Systems Research Institute Seoul National University Seoul South Korea

Skid-steer vehicle can generate a large traction force, which is especially good for navigation on a rough terrain. However, the turning motion is so sensitive to slippage effect that designing a controller is still challenging problem. Also, the motion of the vehicle is affected not only by wheel motion, but also by the road properties and the characteristics of wheel control. With this in mind, we employ a model predictive control (MPC) with an on-line model learning. The velocity model, which represents the relationship between true vehicle velocity and input command, is learned with an on-line sparse Gaussian process (GP). The on-line sparse GP can reduce the computational complexity of GP and also consistently update the model from the driving data. Finally, combining with MPC makes it possible to generate an optimal policy based on the learned model. Experiments are conducted to test the tracking performance of skid-steer robot. The results show the more reliable performance than the method based on a conventional model with parameter adaptation. © 2017

关键词： model predictive control Path tracking skid steer vehicle sparse gaussian process

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Automatic assembly of hydraulic actuators in practice

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AIP Conference Proceedings 2020年第1期2258卷

作者： Wending Li Guanglin Shi Wenyong Dong Weidong Sun Ning Li 1School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China 2Shanghai Aerospace Control Technology Institute Shanghai 201109 China 3Shanghai Servo-system Engineering Research Center Shanghai 201109 China

This study investigates the production status of hydraulic actuators and their automatic assembly in practice. The current difficulties and relevant research are discussed to identify the assembly characteristics of actuator shaft hole parts. Several key technologies of actuator assembly automation technology, including automatic deburring of parts, visual quality identification, and automatic centering assembly, are evaluated to realize informatization and intelligent production. The automatic assembly equipment of a typical shaft hole assembly is developed and implemented in practice. The development trend and future research goals of actuator shaft hole assembly technology are proposed.

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Author Correction: Epitope-directed monoclonal antibody production using a mixed antigen cocktail facilitates antibody characterization and validation

Communications biology

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Communications biology 2021年第1期4卷 531页

作者： Oi Wah Liew Samantha S M Ling Shera Lilyanna Yue Zhou Peipei Wang Jenny P C Chong Yan Xia Ng Angeline E S Lim Eliot R Y Leong Qifeng Lin Teck Kwang Lim Qingsong Lin Enoch M W Ng Tuck Wah Ng A Mark Richards Cardiovascular Research Institute Department of Medicine Yong Loo Lin School of Medicine National University of Singapore National University Health System Singapore Singapore. mdclow@nus.edu.sg. Cardiovascular Research Institute Department of Medicine Yong Loo Lin School of Medicine National University of Singapore National University Health System Singapore Singapore. Department of Biological Sciences National University of Singapore Singapore Singapore. Laboratory for Optics & Applied Mechanics Department of Mechanical & Aerospace Engineering Monash University Clayton VIC Australia. Christchurch Heart Institute University of Otago Christchurch New Zealand.

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Distributed online linear regression

arXiv

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arXiv 2019年

作者： Yuan, Deming Proutiere, Alexandre Shi, Guodong Research School of Engineering Australian National University CanberraACT0200 Australia School of Automation Nanjing University of Science and Technology Nanjing210094 China Department of Automatic Control KTH Royal Institute of Technology Stockholm100-44 Sweden Australian Center for Field Robotics School of Aerospace Mechanical and Mechatronic Engineering University of Sydney SydneyNSW2006 Australia

We study online linear regression problems in a distributed setting, where the data is spread over a network. In each round, each network node proposes a linear predictor, with the objective of fitting the network-wide data. It then updates its predictor for the next round according to the received local feedback and information received from neighboring nodes. The predictions made at a given node are assessed through the notion of regret, defined as the difference between their cumulative networkwide square errors and those of the best off-line network-wide linear predictor. Various scenarios are investigated, depending on the nature of the local feedback (full information or bandit feedback), on the set of available predictors (the decision set), and the way data is generated (by an oblivious or adaptive adversary). We propose simple and natural distributed regression algorithms, involving, at each node and in each round, a local gradient descent step and a communication and averaging step where nodes aim at aligning their predictors to those of their neighbors. We establish regret upper bounds typically in O(T 3/4) when the decision set is unbounded and in O(√T) in case of bounded decision set. Copyright © 2019, The Authors. All rights reserved.

关键词： Gradient methods

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Low Cost MEMS-IMU Based DR/GPS Integrated system in Urban Environment

Low Cost MEMS-IMU Based DR/GPS Integrated System in Urban En...

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International Conference on Control, automation and systems ( ICCAS)

作者： Woo Jung Park Jae Hong Lee Chang Ho Kang Myung Hwan Seo Sang Yeon Park Jong Yun Yeo Jin Woo Song Chan Gook Park Department of Mechanical and Aerospace Engineering Seoul National University Seoul Korea In-Vehicle Solution Team Hyundai MNSOFT Seoul Korea Department of Intelligent Mechatronic Engineering Sejong University Seoul Korea Department of Mechanical Engineering Seoul National University/Automation and System Research Institute Seoul Korea

ISBN: (纸本)9781538670804;9788993215168

In this paper, we propose an MEMS-IMU Based 10 th order DR/GPS integrated system. Existing low cost MEMS based INS/GPS integrated systems are not applicable to autonomous vehicle localization that needs navigation error under 3m. To improve the performance of the MEMS based navigation system, odometer based DR/GPS formulation was proposed. By substituting MEMS accelerometer to odometer, velocity and position errors of navigation solution are reduced. The proposed method is tested for a land vehicle in urban area including GPS outage section. The experimental results show that the proposed method reduced the navigation error in the GPS outage section than MEMS INS/GPS system.

关键词： Global Positioning system Micromechanical devices Accelerometers Mathematical model Sensors Kalman filters

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