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Beyond 60G SSB-FBMC signals transmission for Fiber-THz integrated system using simplified parallel Kramers-Kronig receiver

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Optics & Laser technology 2025年 191卷

作者： Long Zhang Jianjun Yu Xiongwei Yang Jianyu Long Chengzhen Bian Jingtao Ge Min Zhu Jiao Zhang Kaihui Wang Wen Zhou Purple Mountain Laboratories Southeast University Nanjing 211111 China State Key Laboratory of ASIC and System Key Laboratory for Information Science of Electromagnetic Waves (MoE) and the School of Information Science and Technology Fudan University Shanghai 200433 China Purple Mountain Laboratories Nanjing 211111 China

Simplifying coherent detection technology is a potential solution to save the cost of receivers in ultra-high data rate photon-assisted terahertz (THz) communication systems. A key issue when using an envelope detector to simplify the system is that the generation of signal-signal beat interference (SSBI) reduces the signal-to-noise ratio. The Kramers-Kronig (KK) receiver can effectively eliminate SSBI. In this paper, we propose and demonstrate a simplified parallel KK (SP-KK) receiver. The key idea is to use the Taylor expansion approximation instead of the nonlinear operation that significantly broadens the spectrum, and to use a multiplier-free finite impulse response (FIR) filter to approximate the Hilbert transform (HT). We evaluate the performance of the proposed SP-KK receiver in a single-channel 63.1 Gb/s transmission at 0.1 THz over 10-km wired and 3-m wireless links by using the envelope detection for 16-QAM filter bank multicarrier (FBMC) signals. The experimental results show that the proposed SP-KK receiver exhibits similar performance to the conventional HT-based KK (HT-KK) receiver.

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Diagonal-symmetrical and Midline-symmetrical Unit Cells with Same Porosity for Bone Implant: Mechanical Properties Evaluation

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Journal of Bionic Engineering 2019年第3期16卷 468-479页

作者： Jian Li Diansheng Chen Yingying Zhang Yan Yao Zhongjun Mo Lizhen Wang Yubo Fan Robotic Institute Beihang University Beijing 100191 China Beijing Key Laboratory of Rehabilitation Technical Aids for Old-Age and Disability and Key Laboratory of Rehabilitation Aids Technology and System of the Ministry of Civil Affairs National Research Center for Rehabilitation Technical Aids Beijing 100176 China Beijing Advanced Innovation Center for Biomedical Engineering Beihang University Beijing 100191 China Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education School of Biological Science and Medical Engineering Beihang University Beijing 100191 China

In this study, mechanical properties of bionic porous structures with diagonal-symmetrical and midline-symmetrical unit cells were studied when the porosities were same. Three typical unit cells (Diamond (DO), Rhombic Dodecahedron (RD), and Octet Truss (OT)) were selected, in which DO has diagonal-symmetrical shape, while RD and OT share midline-symmetrical structure. Based on the same porosity, corresponding models were designed, and Ti6Al4V samples were manufactured by electron beam melting. Then, using Mechanical Properties Testing (MPT) and Finite Element Analysis (FEA) methodologies, mechanical properties and transmissions of different porous structures were evaluated. Besides, composition and details before and after printing were analyzed with Energy Dispersive Spectrometer (EDS), X-ray diffraction (XRD) and Scanning Electron Microscope (SEM). MPT results showed that midline-symmetrical shape would have superior compressive performance than diagonal-symmetrical shape, but opposite trend for the torsion performance, which were in line with FEA prediction. Furthermore, effective modulus of DO, RD and OT were 2.59 GPa, 4.89 GPa, and 1.77 GPa, approximating the mechanical properties of human bones. Additionally, manufacturing defects and discrepancies between FEA and MPT were found. This study would provide great helps for unit cell selection and initial mechanical properties matching for optimum bone implants.

关键词： bionic design porous implant mechanical properties unit cell additive manufacturing 3D printing

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Research on obstacle detection and path planning based on visual navigation for mobile robot

Research on obstacle detection and path planning based on vi...

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作者： Yixiao Zheng Bixi Yan Chao Ma Xinyu Wang Haoyang Xue School of Instrument Science and Optoelectronic Engineering Beijing Information Science and Technology University Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Applications Beijing Institute of Spacecraft System Engineering

Both obstacle and path planning are of significance for autonomous visual navigation of a mobile robot which is able to realize free movement and obstacle *** this paper,a scheme of obstacle detection which is based on binocular vision to identify obstacles is constructed and it is combined with improved A* algorithm for obstacle avoidance motion for mobile robot ***,a binocular vision system to detect the robot's perception of the environment is used and the visual information is *** a Gaussian filter is used to reduce the noise in the image,and the grayscale image is obtained through the binocular vision *** gray scale map is matched with SAD(Sum of Absolute Differences) in order to obtain the disparity image with ***,the location information of the obstacle is extracted through the environmental depth information contained in the disparity image,and the improved A* algorithm is used as the path planning algorithm in this paper,which can modify the path of the planning ***,the detection experiment of the robot visual obstacle avoidance system was established and the optimal path was *** examples show that,the obstacle avoidance system can complete the task of obstacle detection and give a better path for the mobile robot.

关键词： image filter Research on obstacle detection and path planning based on visual navigation for mobile robot

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Effect of SiO2 Nanoparticle's Size and Doping Concentration on AC Breakdown Behavior of Insulating Oil-based Nanofluids

Effect of SiO2 Nanoparticle's Size and Doping Concentration ...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Muhammad Fasehullah Feipeng Wang Sidra Jamil Jingliang Huang Inzamam Ul Haq Qiuhuang Han State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing China Laboratory of Luminescence Analysis and Molecular Sensing Ministry of Education School of Materials and Energy Southwest University Chongqing PR China

Insulating oil based nanofluids can effectively enhance the dielectric strength of insulating oil for their application in transformers. This work is performed to enhance the dielectric strength of synthetic ester (Midel 7131) and Mineral oil (Karamay #25) by using insulative SiO2 nanoparticles of two sizes (15nm & 50 nm) with four concentrations of 0.05 g/L, 0.2 g/L, 0.3 g/L, and 0.4 g/L. The AC breakdown voltages of SE-based nanofluids increase with increasing the doping concentration. Moreover, SiO2 (15nm) exhibits better dielectric strength due to the accumulation of charges at the liquid-solid interface. However, the AC breakdown voltage of mineral oil (MO) based nanofluids of both nanoparticle sizes first increases to a certain extent and then decreases with further increasing the doping concentration. This might be due to the small average distance of nanoparticles at higher doping concentrations. Furthermore, the AC breakdown voltage and increment percentage compared to pure oil at 1%, 10%, and 50% breakdown probabilities for SE and MO-based nanofluids were studied from Weibull probability distribution curves. Consequently, the variation in the breakdown voltage of nanofluids depends upon nanoparticles' size, doping concentration, and nature of nanoparticles (NPs).

关键词： Nanoparticles Silicon compounds Oils Doping Oil insulation Nanofluidics Probability distribution

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Locomotion Stability Analysis of Lower Extremity Augmentation Device

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Journal of Bionic Engineering 2019年第1期16卷 99-114页

作者： Likun Wang Chaofeng Chen Wei Dong Zhijiang Du Yi Shen Guangyu Zhao State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China School of Astronautics Harbin Institute of TechnologyHarbin 150001China Weapon Equipment Research Institute China Ordnance Industries GroupBeijing 102202China

Stability is of great significance in the theoretical framework of biped ***-time control and walking patterns planning are on the premise that the robot works in the stable *** this paper,we address the crucial issue of the locomotion stability based on the modified Poincare return map and the hybrid *** akin to the traditional stability criteria,i.e.,the Zero Moment Point(ZMP)and the Center of Mass(CoM),the modified Poincare return map is more appropriate for both dynamic walking arid non-periodic ***,a novel high-level reinforcement learning methodology,so-called active PI2 CMA-ES,is proposed in this paper to plan the exoskeleton *** proposed learning methodology demonstrates that the locomotion of the exoskeleton is asymptotically stable according to the modified Poincare return map ***,the proposed learning methodology is tested by the Lower Extremity Augmentation Device(LEAD)and its effectiveness is verified by the experiments.

关键词： biped locomotion dynamic walking Dynamic Movement Primitives (DMP),stability exoskeleton bioinspiration

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An Application of Variable Switching Frequency PWM on SiC-Based Paralleled Inverters for Motor Drive

An Application of Variable Switching Frequency PWM on SiC-Ba...

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International Conference on Power Electronics and Motion Control (IPEMC)

作者： Xuan Zhao Dong Jiang Qiao Li Yingtao Ma Yang Liu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China State Key Laboratory for Traction and Control System of EMU and Locomotive Beijing China

ISBN: (数字)9781728153018

ISBN: (纸本)9781728153025

SiC power devices applied in motor drives have brought the advantages of higher efficiency and power density, but with the problem of more serious electromagnetic interference (EMI). Using advanced topologies can help to mitigate EMI, including the paralleled inverters. In this paper, the variable switching frequency PWM (VSFPWM) for paralleled inverters based on predicted circulating current is used to make better use of the coupled inductor's saturation limit, which is determined by the high frequency circulating current peak. Under the high-frequency operating conditions of the SiC inverter, the VSFPWM strategy will allow the switching frequency to change in a wide range, and the switching losses and EMI will be well improved relative to the constant switching frequency PWM (CSFPWM), while the circulating current peak is controlled within the limit. Moreover, the higher normal frequency (f s N), the larger EMI attenuation after VSF operation. Experimental results are provided to verify the proposed method.

关键词： Motor drives Silicon carbide Switching frequency Electromagnetic interference Switching loss Pulse width modulation Inverters

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Effects of Microstructure and Temperature on Short Fatigue Crack Propagation Behaviour of Powder Metallurgy Superalloy Fgh4098 in Vacuum

SSRN

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SSRN 2022年

作者： Zhang, L.C. Jiang, Rong Wang, Y.C. Zhang, L. Liu, J.T. Zhang, Y.W. Song, Y.D. Key Laboratory of Aero-engine Thermal Environment and Structure Ministry of Industry and Information Technology College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing210016 China Jiangsu Province Key Laboratory of Aerospace Power System College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing210016 China High Temperature Material Institute Central Iron and Steel Research Institute Beijing100081 China State Key Laboratory of Mechanics and Control Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing210016 China

Short fatigue crack propagation (SFCP) behaviour of a powder metallurgy (PM) superalloy (i.e. FGH4098) for aeroengine turbine disc application was investigated at room temperature and 650°C in vacuum (10-3 pa) by in-situ fatigue test. The SFCP mechanism was analyzed by the microstructural characterization and assessment of the SFCP rate. The results show that the SFCP resistance of fine grained (FG) FGH4098 is slightly better than that of course grained (CG) FGH4098 at room temperature due to the hindering effects of grain boundary, and close to that of CG FGH4098 at 650°C. The temperature exerts more evident influence on SFCP behaviour of FG FGH4098 due to the grain boundary oxidation compared with that of CG FGH4098. In the scenario which grain boundary oxidation is absent or insignificant, SFCP shows transgranular feature and is closely related to slip bands linked to the slip systems with high Schmid factor and/or geometric compatibility factor. Grain boundary oxidation still occurs in both FG and CG FGH4098 alloy and mainly forms Cr oxides at 650°C, which results in intergranular or mixed-inter-transgranular SFCP and promotes SFCP to some extent for FG FGH4098 alloy. © 2022, The Authors. All rights reserved.

关键词： Fatigue crack propagation

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Error-free approximation of explicit linear MPC through lattice piecewise affine expression

arXiv

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arXiv 2021年

作者： Xu, Jun Lou, Yunjiang De Schutter, Bart Xiong, Zhenhua School of Mechanical Engineering and Automation Harbin Institute of Technology Shenzhen China Key Laboratory of System Control and Information Processing Ministry of Education Shanghai China Delft Center for Systems and Control Delft University of Technology Netherlands State Key Laboratory of Mechanical Systems and Vibration Shanghai Jiao Tong University Shanghai China

In this paper, the disjunctive and conjunctive lattice piecewise affine (PWA) approximations of explicit linear model predictive control (MPC) are proposed. The training data are generated uniformly in the domain of interest, consisting of the state samples and corresponding affine control laws, based on which the lattice PWA approximations are constructed. Re-sampling of data is also proposed to guarantee that the lattice PWA approximations are identical to the explicit MPC control law in the unique order (UO) regions containing the sample points as interior points. Additionally, if all the distinct affine functions have been sampled, the disjunctive lattice PWA approximation constitutes a lower bound while the conjunctive lattice PWA approximation formulates an upper bound of the original optimal control law. The equivalence of the two lattice PWA approximations then guarantees that the approximations are error-free in the domain of interest, which is tested through a statistical guarantee. The complexity of the entire procedure is analyzed, which is polynomial with respect to the number of samples. The performance of the proposed approximation strategy is tested through two simulation examples, and the results show that with a moderate number of sample points, we can construct lattice PWA approximations that are equivalent to the optimal control law of the explicit linear MPC. © 2021, CC0.

关键词： Model predictive control

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Robust Multi-agent Communication Based on Decentralization-Oriented Adversarial Training

arXiv

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arXiv 2025年

作者： Ma, Xuyan Wang, Yawen Wang, Junjie Xie, Xiaofei Wu, Boyu Li, Shoubin Xu, Fanjiang Wang, Qing State Key Laboratory of Intelligent Game Beijing China Science and Technology on Integrated Information System Laboratory Institute of Software Chinese Academy of Sciences Beijing China University of Chinese Academy of Sciences Beijing China Singapore Management University Singapore

In typical multi-agent reinforcement learning (MARL) problems, communication is important for agents to share information and make the right decisions. However, due to the complexity of training multi-agent communication, existing methods often fall into the dilemma of local optimization, which leads to the concentration of communication in a limited number of channels and presents an unbalanced structure. Such unbalanced communication policy are vulnerable to abnormal conditions, where the damage of critical communication channels can trigger the crash of the entire system. Inspired by decentralization theory in sociology, we propose DMAC, which enhances the robustness of multiagent communication policies by retraining them into decentralized patterns. Specifically, we train an adversary DMAC Adv which can dynamically identify and mask the critical communication channels, and then apply the adversarial samples generated by DMAC Adv to the adversarial learning of the communication policy to force the policy in exploring other potential communication schemes and transition to a decentralized structure. As a training method to improve robustness, DMAC can be fused with any learnable communication policy algorithm. The experimental results in two communication policies and four multi-agent tasks demonstrate that DMAC achieves higher improvement on robustness and performance of communication policy compared with two state-of-the-art and commonly-used baselines. Also, the results demonstrate that DMAC can achieve decentralized communication structure with acceptable communication cost. Copyright © 2025, The Authors. All rights reserved.

关键词： Adversarial machine learning

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Research on the detection method of 500kV composite insulator's decay-like fracture

Research on the detection method of 500kV composite insulato...

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22nd International Symposium on High Voltage Engineering (ISH 2021)

作者： G. Pang Z. Zhang M. Lu C. Gao X. Jiang State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing People's Republic of China State Grid Henan Electric Power Research Institute State Grid Zhengzhou People's Republic of China

Composite insulators play an essential role in insulation and load-bearing in transmission lines, and their operating status directly affects the safety and stability of the power grid. This paper uses an insulator of decay-like fracture to measure the temperature and discharge under different conditions by visual inspection, ultraviolet detection, infrared detection, and electric field detection. Detailed morphology of the insulator of decay-like fracture is obtained. The results show that the deterioration of the sheath is considerably related to the surface contamination or leakage current. It is an effective method to determine the deterioration of composite insulators when the temperature and temperature rise of composite insulators are abnormal (for example, T>50°C, ΔT>30°C). Under DC conditions, the temperature rise and discharge are much lower than those of AC, indicating that the temperature rise of the insulator is mainly generated by dielectric loss heating caused by the polarization effect of the insulating dielectric under the impact of the alternating electric field. The measurement results are significantly affected by the test conditions. It isn't easy to judge whether composite insulators are fractured or not by using electric field distribution and UV measurement on site.

关键词： composite insulators dielectric losses discharges (electric) electric fields fracture infrared detectors inspection leakage currents polarisation power grids power transmission lines surface contamination ultraviolet detectors

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