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Model heat source using actual distribution of laser power density for simulation of laser processing

Journal of Central South University 2022年第10期29卷 3277-3293页

作者： WANG Gen-wang DING Ye GUAN Yan-chao WANG Yang YANG Li-jun State Key Laboratory of Robotics and Systems Harbin Institute of TechnologyHarbin 150001China School of Mechatronics Engineering Harbin Institute of TechnologyHarbin 150001China

The model of heat source(MHS) which reflects the thermal interaction between materials and laser during processing determines the accuracy of simulation results. To acquire desirable simulations results, although various modifications of heat sources in the aspect of absorption process of laser by materials have been purposed, the distribution of laser power density(DLPD) in MHS is still modeled theoretically. However, in the actual situations of laser processing, the DLPD is definitely different from the ideal models. So, it is indispensable to build MHS using actual DLPD to improve the accuracy of simulation results. Besides, an automatic modeling method will be benefit to simplify the tedious pre-processing of simulations. This paper presents a modeling method and corresponding algorithm to model heat source using measured DLPD. This algorithm automatically processes original data to get modeling parameters and provides a step MHS combining with absorption models. Simulations and experiments of heat transfer in steel plates irradiated by laser prove the mothed and the step MHS. Moreover, the investigations of laser induced thermal-crack propagation in glass highlight the signification of modeling heat source based on actual DLPD and demonstrate the enormous application of this method in the simulation of laser processing.

关键词： heat source laser processing distribution of power density digital images processing heat transfer

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The Performance Of A Novel P300 Brain-Computer Interface Paradigm With Electrical And Vibration Modes 12

The Performance Of A Novel P300 Brain-Computer Interface Par...

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12th International Conference on CYBER technology in Automation, Control, and Intelligent systems, CYBER 2022

作者： Chu, Chenxi Luo, Jingjing Du, Qiang Han, Xiangke Guo, Shijie and Robotics Academy for Engineering and Technology Fudan University Shanghai China Hebei University of Technology The Hebei Key Laboratory of Robot Perception and Human-Robot Interaction Department of the State Key Laboratory of Reliability and Intelligence of Electrical Equipment Tianjin China

ISBN: (数字)9781665472678

ISBN: (纸本)9781665472678

A novel tactile P300 paradigm was proposed for Brain-Computer Interface(BCI), in which only two types of stimuli was used to distinguish different targets. We also adapted an algorithm for intention recognition, which used spatial information to distinguish different stimulation sites, and frequency information to identify attended-target stimuli and disturbances. Our novel paradigm was verified on both vibration and electrical stimuli modes, and achieved an average classification accuracy of 95.21% for vibration stimuli mode and 94.88% for electrical stimuli mode, respectively. Furthermore, we evaluated performances of brain's functional connectivity by the correlation coefficient, and preliminarily explored the similarities and differences between vibration stimuli mode and electrical stimuli mode. © 2022 IEEE.

关键词： Brain computer interface

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Late Paleozoic–Early Mesozoic tectonic evolution of the Zongwulong Shan-Qinghai Nanshan tectonic belt in the northern Qaidam continent， northern Tibet

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Journal of Earth Science 2025年

作者： Yonghui Zhao Chen Wu Jie Li Peter J.Haproff Lin Ding State Key Laboratory of Tibetan Plateau Earth System and Resources Environment (TPESRE)， Institute of Tibetan Plateau Research， Chinese Academy of Sciences University of Chinese Academy of Sciences Chongqing Key Laboratory of Complex Oil and Gas Field Exploration and Development， Chongqing University of Science and Technology Department of Earth and Ocean Sciences， University of North Carolina Wilmington

The Zongwulong Shan-Qinghai Nanshan tectonic belt of the northern Tibet Plateau experienced a protracted tectonic history， including the openings and closures of the Proto- and Paleo-Tethyan Oceans. Although the tectonic belt has been extensively studied， details regarding the tectonic processes involved in its development remain controversial. To better constrain the tectonic processes of this tectonic belt， we conducted detailed field geological mapping， zircon U-Pb geochronology， and whole-rock geochemical and Sr-Nd isotopic analyses. Our results show that intrusive rocks in the tectonic belt crystallized in ca. 292–233 Ma， perhaps in an arc/subduction setting. Geochemical and Sr-Nd isotopic data suggest that early Permian–late Triassic ultramafic-intermediate intrusions were sourced from the enriched mantle， whereas intermediate-acidic rocks were sourced from mixed crust-mantle. We present the tectonic model that involves: (1) Early Devonian–early Permian intracontinental extension occurred in the northern margin of the Qaidam continent (ca. 416 Ma–292 Ma); (2) Early Permian–late Triassic northward subduction of the Paleo-Tethyan Ocean resulted in arc magmatism (ca. 292 Ma–233 Ma); and (3) subsequent late Triassic intracontinental extension (ca. 233 Ma–215 Ma). Our results suggest that the late Paleozoic–early Mesozoic development of the Zongwulong Shan-Qinghai Nanshan was related to the opening， subduction， and slab retreat of the Paleo-Tethyan Ocean， which has key implications for the tectonic evolution of the northern Tibetan Plateau.

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Analytical Impact-Excitation Theory of Er/O/B Codoped Si Light-Emitting Diodes

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Physical Review Letters 2024年第24期132卷 246901-246901页

作者： Xiaoming Wang Jiajing He Ao Wang Kun Zhang Yufei Sheng Weida Hu Chaoyuan Jin Hua Bao Yaping Dan State Key Laboratory of Advanced Optical Communication Systems and Networks University of Michigan–Shanghai Jiao Tong University Joint Institute Aerospace Laser Technology and System Department Global Institute of Future Technology State Key Laboratory of Infrared Physics College of Information Science and Electronic Engineering

Er doped Si light-emitting diodes may find important applications in silicon photonics and optical quantum computing. These diodes exhibit an emission efficiency 2 orders of magnitude higher at reverse bias than forward bias due to impact excitation. However, physics of impact excitation in these devices remains largely unexplored. In this work, we fabricated an Er/O/B codoped Si light-emitting diode which exhibits a strong electroluminescence by the impact excitation of electrons inelastically colliding the Er ions. An analytical impact-excitation theory was established to predict the electroluminescence intensity and internal quantum efficiency which fit well with the experimental data. From the fittings, we find that the excitable Er ions reach a record concentration of 1.8×1019 cm−3 and up to 45% of them is in an excitation state by impact excitation. This work has important implications for developing efficient classical and quantum light sources based on rare earth elements in semiconductors.

关键词： Density of states Electrical conductivity Electrical properties Electroluminescence Ion impact & scattering LEDs

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3D Source Tracking Using a Position-Unknown AOA Sensor with Measurement Drift and UAV Moving Direction Optimization

3D Source Tracking Using a Position-Unknown AOA Sensor with ...

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IEEE International Conference on Real-time Computing and robotics (RCAR)

作者： Rongrong Xu Sheng Xu Kaimin Cao Xianliang Li Jialiang Wang Wujing Cao Guangdong Provincial Key Laboratory of Robotics and Intelligent System Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen China University of Chinese Academy of Sciences Beijing China Robotics Laboratory China Nanhu Academy of Electronics and Information Technology China

ISBN: (数字)9798350372601

ISBN: (纸本)9798350372618

This work solves the angle-of-arrival (AOA) source tracking problem in 3-dimensional (3D) space utilizing a position-unknown unmanned aerial vehicle (UAV). An AOA sensor is carried by a mobile UAV, and the conventional self-positioning module, such as the global positioning system (GPS), is not allowed due to environmental limitations. Thus, to guarantee the feasibility of this source tracking problem, at least two position-known landmarks are required. Firstly, the detailed problem formulation is provided with the consideration of measurement drift caused by sensor-vehicle installation errors. Secondly, all the unknown states are estimated using a proposed extended Kalman filter (EKF). Thirdly, a UAV moving direction optimization algorithm is developed to promote the estimation accuracies of the source, UAV and measurement drift. Finally, simulation examples demonstrate the characteristics of the proposed method.

关键词： Three-dimensional displays Accuracy Measurement uncertainty Estimation Autonomous aerial vehicles Robot sensing systems Velocity measurement

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Generation of polarization-multiplexed terahertz orbital angular momentum combs via all-silicon metasurfaces

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Light(Advanced Manufacturing) 2024年第3期5卷 120-129页

作者： Ming-Zhe Chong Yiwen Zhou Zong-Kun Zhang Jin Zhao Yue-Yi Zhang Chong-Qi Zhang Xiaofei Zang Chao-Hai Du Pu-Kun Liu Ming-Yao Xia School of Electronics Peking UniversityBeijing 100871China Terahertz Technology Innovation Research Institute and Shanghai Key Lab of Modern Optical SystemUniversity of Shanghai for Science and TechnologyNo.516 Jun Gong RoadShanghai 200093China State Key Laboratory of Advanced Optical Communication Systems and Networks School of ElectronicsPeking UniversityBeijing 100871China

Electromagnetic waves carrying orbital angular momentum(OAM),namely OAM beams,are important in various fields including optics,communications,and quantum ***,most current schemes can only generate single or several simple OAM ***-mode OAM beams are rarely *** paper proposes a scheme to design metasurfaces that can generate multiple polarization-multiplexed OAM modes with equal intervals and intensities(i.e.,OAM combs)working in the terahertz(THz)*** a proof of concept,we first design a metasurface to generate a pair of polarization-multiplexed OAM combs with arbitrary mode ***,another metasurface is proposed to realize a pair of polarization-multiplexed OAM combs with arbitrary locations and intervals in the OAM *** results agree well with full-wave simulations,verifying a great performance of OAM combs *** method may provide a new solution to designing high-capacity THz devices used in multi-mode communication systems.

关键词： Metasurfaces Terahertz Orbital angular momentum comb Polarization multiplexing

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A Novel Kinematic Calibration Method Based on the End Acceleration of the Manipulator 3

A Novel Kinematic Calibration Method Based on the End Accele...

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3rd International Conference on robotics and Computer Vision, ICRCV 2021

作者： Zhou, Rui Jin, Hongzhe Wang, Binluan Ge, Mingda Yin, Hong Zhao, Jie Harbin Institute of Technology State Key Laboratory of Robotics and Systems Harbin China

ISBN: (纸本)9781665436281

The kinematic calibration of the manipulator is one of the main methods to improve the absolute positioning accuracy of the end of the manipulator. Due to the disadvantages of the current calibration methods, such as excessively expensive measuring equipment, complex calibration process and numerous calculations, exploring a new calibration method has become a research focus in recent years. This paper proposes a novel kinematic calibration method based on the end acceleration of the manipulator for the first time. This method derives the relationship between the end acceleration of the manipulator and the kinematic parameters by Jacobian matrix. After obtaining the manipulator's joints data and the end acceleration acquired by the inertial measurement unit attached to the end of the manipulator, these data will be brought into the derived relationship, then using the recursive least squares method to obtain the estimated value of parameters of the manipulator. This calibration method has the advantages of low cost, simple operation and the low requirements for the experimental environment. With the improvement of inertial measurement unit technology, the calibration results of this method will become more and more accurate, and its development prospect is extremely broad. © 2021 IEEE.

关键词： Manipulators

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Convolutional neural network based on sparse graph attention mechanism for MRI super-resolution

arXiv

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arXiv 2023年

作者： Hua, Xin Du, Zhijiang Yu, Hongjian Ma, Jixin State Key Laboratory of Robotics Technology and Systems Harbin Institute of Technology Heilongjiang Harbin15000 China

Magnetic resonance imaging (MRI) is a valuable clinical tool for displaying anatomical structures and aiding in accurate diagnosis. Medical image super-resolution (SR) reconstruction using deep learning techniques can enhance lesion analysis and assist doctors in improving diagnostic efficiency and accuracy. However, existing deep learning-based SR methods predominantly rely on convolutional neural networks (CNNs), which inherently limit the expressive capabilities of these models and therefore make it challenging to discover potential relationships between different image features. To overcome this limitation, we propose an A-network that utilizes multiple convolution operator feature extraction modules (MCO) for extracting image features using multiple convolution operators. These extracted features are passed through multiple sets of cross-feature extraction modules (MSC) to highlight key features through inter-channel feature interactions, enabling subsequent feature learning. An attention-based sparse graph neural network module is incorporated to establish relationships between pixel features, learning which adjacent pixels have the greatest impact on determining the features to be filled. To evaluate our model's effectiveness, we conducted experiments using different models on data generated from multiple datasets with different degradation multiples, and the experimental results show that our method is a significant improvement over the current state-of-the-art methods. Copyright © 2023, The Authors. All rights reserved.

关键词： Magnetic resonance imaging

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IMPROVING LATERAL SAFETY DISTANCE-BASED ON FEATURE DETECTION AND PRM FOR UNMANNED VEHICLE PATH PLANNING

IMPROVING LATERAL SAFETY DISTANCE-BASED ON FEATURE DETECTION...

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2022 International Conference on Computer, Artificial Intelligence, and Control Engineering, CAICE 2022

作者： Wang, Boqian Wang, Jianfeng Li, Wenxuan Liu, Yiqun Yang, Na Wang, Quanqing Yao, Xinyue School of Automotive Engineering Harbin Institute of Technology Shandong Weihai264209 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China Weihai Guangtai Airport Equipment Co. Ltd. Weihai264200 China

ISBN: (纸本)9781510655942

Most of the existing path-planning algorithms do not consider lateral safe distance requirements in practical applications. Hence, in this study, a new path point selection algorithm is proposed for path planning. The algorithm first used the Harris and Line Segment Detector(LSD) algorithms to detect and obtain the corner and edge information of obstacles. A vertical line was provided to the edge of the surrounding obstacles along each corner successively. In this process, the narrow impassable area in the map was filtered and removed by setting a safety threshold, and the foot of the vertical coordinates were simultaneously obtained. The corresponding midpoint coordinates were solved by using the corner coordinates and the foot of the corresponding perpendicular coordinates. The midpoint coordinates were used as candidate points to generate path points. These candidate points are screened and relaxed using the Probabilistic Roadmaps(PRM) algorithm to obtain the series of path points required. Finally, the path was planned according to these path points and smoothed using the Quadratic polynomial interpolation method(QPMI). Through simulation experiments, the method proposed in this study can solve a unique path without randomness under given conditions, and the probability of a collision in practical applications was reduced. © 2022 SPIE.

关键词： Motion planning

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Design of LCoS-Based Twin 1×40 Wavelength Selective Switch

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ZTE Communications 2024年第4期22卷 18-28页

作者： WANG Han LIU Maoqi FENG Zhenhua LIU Minghuan MAO Baiwei School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China Wuhan National Laboratory for Optoelectronics Huazhong Univer-sity of Science and TechnologyWuhan 430074China WDM System Department of Wireline Product R&D Institute ZTE CorporationWuhan 430223China State Key Laboratory of Mobile Network and Mobile Multimedia Technology Shenzhen 518055China

Wavelength selective switch(WSS)is the crucial component in the reconfigurable optical add/drop multiplexer(ROADM),which plays a pivotal role in the next-generation all-optical *** present a compact architecture of twin 1×40 liquid crystal on silicon(LCoS)-based WSS,which can be regarded as a 4f system in the wavelength direction and a 2f system in the switching *** is designed with theoretical analysis and simulation *** multiplexing is employed for two sources of twin WSS by polarization con-version before the common optical *** WSS system attains a coupling efficacy exceeding 96%for 90%of the ports through simulation *** 3 dB bandwidth can be achieved by more than 44 GHz at a 50 GHz grid for all 120 channels at all deflection *** work establishes a solid foundation for developing high-performance WSS with larger port counts.

关键词： wavelength selective switch(WSS) liquid crystal on silicon(LCoS) optical structure design insertion loss

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