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Photothermal-controlled sustainable degradation of protective coating modified Mg alloy using near-infrared light

Rare Metals 2021年第9期40卷 2538-2551页

作者： Zhi-Xin Han Xiang-Mei Liu Lei Tan Zhao-Yang Li Yu-Feng Zheng Kelvin Wai-Kwok Yeung Zhen-Duo Cui Yan-Qin Liang Sheng-Li Zhu Shui-Lin Wu Hubei Key Laboratory of Polymer Materials Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional MaterialsSchool of Materials Science&EngineeringHubei UniversityWuhan 430062China The Key Laboratory of Advanced Ceramics and Machining Technology by the Ministry of Education of China School of Materials Science&EngineeringTianjin UniversityTianjin 300072China State Key Laboratory for Turbulence and Complex System Department of Materials Science and EngineeringCollege of EngineeringPeking UniversityBeijing 100871China Department of Orthopaedics and Traumatology Li Ka Shing Faculty of MedicineThe University of Hong KongPokfulam 999077Hong KongChina

Controlling the corrosion rate is critical for practical applications of Mg-based alloys. In this work, we constructed a protective coating of hybrid polycaprolactone(H-PCL)/indocyanine green(ICG) on AZ31 Mg alloy,whose degradation rate was controlled by 808-nm nearinfrared(NIR) light irradiation. The corrosion behaviors of H-PCL/ICG coated Mg alloys were systematically investigated by potentiodynamic polarization tests, electrochemical impedance spectroscopy(EIS) and hydrogen evolution experiments. The results disclosed that the H-PCL/ICG composite coating could effectively protect Mg alloy from corroding without NIR light irradiation. In contrast, under 808-nm NIR light irradiation, the corrosion resistance of this composite coating was decreased significantly, i.e., the corrosion current density(i_(corr))increasedfrom(8.81 ± 1.068) 9 10^(-8) to(1.22 ± 0.545) 9 10^(-6) A·cm^(-2). This is because the component of ICG in the coating was excited to produce heat locally, which triggered the glass transition temperature(T_(g)) of H-PCL in the coating, resulting in the motion of the molecular chain segment. Consequently, the electrolytes penetrated the coating and corroded the Mg substrate. In vitro biological experiment indicated that the synthesized coating exhibited good ***, these findings will provide a new strategy for designing novel photoresponsive coatings to remotely adjust the degradation rate of biodegradable metals for biomedical applications.

关键词： Magnesium Corrosion Coating Photoresponsive Surface modification

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Robust composite control of telescopic wing morphing aircraft with control allocation

Robust composite control of telescopic wing morphing aircraf...

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Chinese Automation Congress (CAC)

作者： Zijian Wang Mingzhe Hou Mingrui Hao Center for Control Theory and Guidance Technology Harbin Institute of Technology Harbin China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing China

ISBN: (纸本)9781665426480

In this paper, the problem of anti-disturbance, anti-saturation and fixed-time control for a class of telescopic wing morphing aircraft is studied. The telescopic wing morphing aircraft treats the variable wingspan as an extra control input to construct the dynamic model of the morphing-aided maneuver. According to the model characteristics, the controller design is divided into two loops: the speed loop and the attitude loop. Through a fixed-time continuous feedback control scheme, fixed time of the tracking reference trajectory is ensured. By combining the integral sliding mode control (ISMC) method with super-twisting control (STC), the uncertainties of aerodynamic coefficients and external disturbances are overcome. In addition, the anti-saturation problem of the aircraft actuator is solved by the initial solution correction method based on Null-space augmented solutions. The simulation result shows that the designed algorithm has great tracking performance, while the robustness and anti-saturation performance are guaranteed.

关键词： Attitude control Atmospheric modeling Heuristic algorithms Aerodynamics Robustness Trajectory Feedback control

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A General Framework for Chinese Domain Knowledge Graph Question Answering Based on TransE 3

A General Framework for Chinese Domain Knowledge Graph Quest...

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2020 3rd International Conference on Computer Information science and Artificial Intelligence, CISAI 2020

作者： Pei, Zhongmin Zhang, Jie Xiong, Wei Li, Li Luo, Zhangkai Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing China Gaojing Network Management and Security Center Beijing China

This paper introduces a general question answering (QA) framework for Chinese domain knowledge graphs to serve various industries. The question is analyzed by shielding invalid characters in this framework, and the TransE calculation of entities and relations is used to search answer, rather than traditional logical queries that rely heavily on predefined rules. In this way, the QA framework can be easily applied to different fields with little manual participation, and reduce the migration cost caused by the lack of scalability of the existing QA systems, which are designed only for specific domains. Then, the proposed framework is operated on the space launch knowledge graph and has achieved HITS@1, HITS@3, HITS@5 scores of 60.60%, 80.87%, 85.61% separately, which is competitive with other restricted domain knowledge graphs. In addition, numerical results on the knowledge graph of the Three Kingdoms and the COVID-19-Character verified the scalability of the QA framework. © Published under licence by IOP Publishing Ltd.

关键词： Knowledge graph

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DRL-based Energy Efficient Resource Allocation for STAR-RIS Assisted Coordinated Multi-cell Networks

DRL-based Energy Efficient Resource Allocation for STAR-RIS ...

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GLOBECOM 2022 - 2022 IEEE Global Communications Conference

作者： Jian Chen Ziye Ma Yixuan Zou Jie Jia Xingwei Wang School of Computer Science and Engineering Northeastern University Shenyang China Ministry of Education Engineering Research Center of Security Technology of Complex Network System China Queen Mary University of London London U.K.

ISBN: (纸本)9781665435413

A novel simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RIS) assisted collabo-rative multi-cell network is proposed. Cell-center and cell-edge users are enhanced by the STAR-RIS's reflection and transmission functions, respectively. We propose an online joint active and passive beamforming framework to maximize this system's long-term energy efficiency (EE) under time-varying channels and users' requirements. We first invoke fractional programming (FP) to optimize the coordinated zero-forcing beamforming among all base stations and to construct an interference-free transmission during each time slot. Then, a parallel deep reinforcement learning (DRL) algorithm is proposed to facilitate the online optimization of the passive beamforming of all STAR-RISs. Finally, the beamforming calculated by the FP algorithm is utilized as a part of the reward function of the DRL. As a result, the size of the action and state space is reduced, and the dynamic joint optimization is realized. Extensive numerical results reveal that: 1) the proposed algorithm induces a low computation complexity compared with conventional DRL algorithms, and 2) the STAR-RIS enhanced system can achieve higher EE than systems without RIS or with conventional reflection/transmission-only RISs.

关键词： Training Array signal processing Heuristic algorithms Reinforcement learning Time-varying channels Energy efficiency Reflection

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Robust Imagined Speech Production from Electrocorticography with Adaptive Frequency Enhancement

Robust Imagined Speech Production from Electrocorticography ...

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International Joint Conference on Neural Networks (IJCNN)

作者： Xu Xu Chong Fu Junxin Chen Gwanggil Jeon David Camacho School of Computer Science and Engineering Northeastern University Shenyang China School of Software Dalian University of Technology Dalian China Key Laboratory of Intelligent Computing in Medical Image Ministry of Education Northeastern University Shenyang China Engineering Research Center of Security Technology of Complex Network System Ministry of Education Shenyang China College of Information Technology Incheon National University Incheon Korea Department of Computer Systems Engineering Universidad Politécnica de Madrid Madrid Spain

ISBN: (数字)9798350359312

ISBN: (纸本)9798350359329

Imagined speech production with electrocorticography (ECoG) plays a crucial role in brain-computer interface system. A challenging issue is the great variation underlying the frequency bands of the ECoG signals’ encode information, which makes current methods difficult to generate imagined speech with stable quality among different persons. To this end, we propose a robust model to generate high-quality imagined speech from ECoG. A frequency enhancement branch is first designed to adaptively modulate the frequency information, whose product is fed into the following multi-scale channel attention module for robust feature extraction and fusion. By incorporating both the mel-spectrum and audio as training constraints, a multi-constraint decoder branch is finally constructed for imagined speech production. The performance of our model is evaluated on a high-quality dateset, i.e, Single Word Production Dutch-iBIDS. It yields Pearson correlation scores that are all above 0.8, and the standard deviationsare are all below 0.2 in different volunteers. Experimental results demonstrate that our model is effective and robust for ECoG based imagined speech production, and has advantages over peer methods.

关键词： Training Adaptation models Frequency modulation Correlation Neuroscience Production Speech enhancement

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Strengthening and Toughening Mechanisms Induced by Metal Ion Cross-Linking in Wet-Drawn Bacterial Cellulose Films

SSRN

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SSRN 2022年

作者： Liu, Xuan Jiang, Yingjie Wei, Xiaoding State Key Laboratory for Turbulence and Complex System Department of Mechanics and Engineering Science College of Engineering Beijing Innovation Center for Engineering Science and Advanced Technology Peking University Beijing100871 China Peking University Nanchang Innovation Institute Nanchang330000 China

Cellulose nanofibril (CNF) has become a renewable and sustainable building block for functional and structural materials. In this study, combining chemical structure analyses, mechanical experiments and first principle calculations, we elaborate on the strengthening and toughening mechanisms for the wet-drawn bacterial cellulose films that contain metal ion crosslinks. Wet-drawing assists the alignment of CNFs, and multivalent metal ion cross-linking further improves the inter-fibril interactions. BC films cross-linked with Na+, Ca2+, Cu2+, Al3+, and Fe3+ all demonstrate improved mechanical strength than the as-received samples. Density functional theory (DFT) calculations reveal that besides the electrostatic forces between the metal ions and the adjacent carboxylate oxygen atoms, Cu2+ and Fe3+ can also form coordination bonds with the adjacent carboxylate oxygen atoms. Among all the five metal ions tried herein, we found that Fe3+ introduces the strongest cross-links between fibers through coordination bonds and electrostatic forces. The BC films cross-linked with Fe3+ exhibit high tensile strength and toughness of 451.51 MPa and 8.19 MJ∙m-3, respectively. The underlying mechanisms discovered herein open new possibilities for the utilization of natural fibers. © 2022, The Authors. All rights reserved.

关键词： Cellulose

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Detection of Colored Noise Correlation Time with Josephson Junctions

SSRN

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SSRN 2023年

作者： Pountougnigni, Oberlin Valex Yamapi, René Filatrella, Giovanni Tchawoua, Clément Laboratory of Mechanics and Materials Department of Physics Faculty of Science University of Yaoundé I Box 812 Yaoundé Cameroon Fundamental Physics Laboratory Physics of Complex System Group Department of Physics Faculty of Science University of Douala Box 24 157 Douala Cameroon INFN - Napoli Salerno Group Department of Science and Technology University of Sannio Via Port’Arsa 11 BeneventoI-82100 Italy

It is shown that the effect of a Gaussian noisy source on the escape times of a Josephson junction depends upon the time duration of the noise correlation. A careful analysis reveals that two effects are preeminent: the increase of the stability (as measured by the average escape time from the metastable state) and the increase of extreme events in the tail of the escape time distribution. The changes occur if the noise correlation exceeds the characteristic time of the Josephson junction. As the superconducting device is very fast, with a characteristic time easily below the nanosecond, the device is responsive even to very short noise correlation. We speculate that it is thus possible toestimate in situ noise correlation with a superconducting Josephson junction through the measurements of the escapes, without a high frequency sampling of the noise. Moreover, the superconducting circuit can be cooled as much as necessary, thus offering the further advantage to be intrinsically very quiet. © 2023, The Authors. All rights reserved.

关键词： Quantum optics

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Incremental Control system Design and Flight Tests of a Micro-Coaxial Rotor UAV

arXiv

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arXiv 2022年

作者： Liu, Zhenchang Zhang, Yufei Chen, Haixin Zhang, Zhiduo Science And Technology On Complex System Control And Intelligent Agent Cooperation Laboratory School Of Aerospace Engineering Beijing100074 China Tsinghua University School Of Aerospace Engineering Beijing100084 China Beijing Institute Of Technology School Of Aerospace Engineering Beijing100081 China

In this paper, the incremental nonlinear dynamic inversion (INDI) method is applied to the control system design of coaxial rotor UAVs. The aerodynamic uncertainty and anti-disturbance problems are solved in the control system design. The designed controller gives the UAV excellent flight performance and control robustness. An incremental gain method (IGM) is proposed for the delay problem of the state derivative. This method has the advantages of less calculation load and simple parameter adjustment, which provides excellent convenience for applying INDI controllers to coaxial rotor UAVs. The principle of IGM is demonstrated by the stability analysis method of the discrete system, and the parameter selection strategy of the IGM is analyzed in detail by simulation. The advantages of the controller design method are verified by comparative flight tests of nonlinear dynamic inversion (NDI) and INDI. The experimental results show that the average trajectory tracking error of INDI is only 58.3% of that of NDI under the same wind speed. When the angular acceleration delay is less than 0.06 s, IGM can easily keep the system stable. In addition, INDI has better robustness under obvious model errors and strong input disturbance. Copyright © 2022, The Authors. All rights reserved.

关键词： Unmanned aerial vehicles (UAV)

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Lightweight Vision Transformer for Small Data Sets

Lightweight Vision Transformer for Small Data Sets

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Youth Academic Annual Conference of Chinese Association of Automation (YAC)

作者： Wenxing Fang Yanxu Su Institutes of Physical Science and Information Technology Anhui University Hefei China School of Artificial Intelligence Anhui University Hefei P. R. China Key Laboratory of Measurement and Control of Complex System of Engineering Ministry of Education Southeast University Nanjing P. R. China

With the rapid development of Transformers in the field of computer vision, models based on Transformers have become highly competitive architectures in the area. Although variants of Transformer models have achieved increasing accuracy on image classification tasks, the size of the training set and the number of parameters required by the models have increased dramatically. When dealing with small datasets, such models face problems such as overfitting and undergeneralization, leading to poor accuracy on the test set. We propose a new lightweight vision transformer (LVT) to address these issues. We reconstructed the backbone network, which learns the relationship between pixels through local window self-attention and global self-attention computation. We also use the attention pooling approach to fuse the token sequences generated by the backbone network more meticulously. We trained on the CIFAR-10 and CIFAR-100 datasets from scratch and compared them with a modern convolutional neural network. The experimental results show that LVT outperforms the modern convolutional neural network in terms of accuracy and efficiency. On the test set of CIFAR-10, we have obtained an accuracy of 96.83%, which indicates that our model can effectively solve the problems facing the training of small datasets and has a wide range of application prospects.

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The design of a displaying system for battlefield situation based on ArcGIS Engine

The design of a displaying system for battlefield situation ...

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Chinese Automation Congress (CAC)

作者： Jiaqi Wang Cheng Xu Hua Ji Science and Technology on Complex System Control and Ietelligent Agent Coopration Laboratory Beijing Beijing Electro-Mechanical Engineering Institute Beijing China

ISBN: (数字)9781665426473

ISBN: (纸本)9781665426480

To facilitate the precise analysis and judgment of battlefield situation for military stuffs inmodern warfare with abundant information, a modularized two-dimension battlefield situation displaysystem is designed based on ArcGIS Engine in this paper. The functions of each module are analyzed, andkey issues of the design are introduced. The real-time dynamic display of moving objects in the battlefield isachieved by reading data from the battlefield.

关键词： Computer languages Automation Real-time systems Software C# languages Engines

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