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Preparation and properties of Ni-coated WC powder and highly impact resistant and corrosion resistant WC-Ni cemented carbides

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Transactions of Nonferrous Metals Society of China 2022年第6期32卷 1935-1947页

作者： Fan-lu MIN Song-bai YU Sheng WANG zhan-hu yao Jacques Guillaume NOUDEM Si-jin LIU Jian-feng zhanG Key Laboratory of Geomechanics and Embankment Engineering Ministry of EducationHohai UniversityNanjing 210098China College of Civil and Transportation Engineering Hohai UniversityNanjing 210098China College of Mechanics and Materials Hohai UniversityNanjing 210098China CCCC Tunnel Engineering Company Limited Beijing 100102China CRISMAT-ENSICAEN(UMR-CNRS 6508) Universitéde Caen-Basse-NormandieCaenF-14050France China Railway 14th Bureau Group Co. Ltd.Jinan 250101China

WC powders were uniformly coated by Ni nanoparticles through a combined chemical co-precipitation and subsequent high temperature hydrogen reduction strategy(abbreviated as CM-WCN),and then were consolidated by vacuum sintering at 1450°C for 1 h to obtain WC−Ni cemented *** microstructure and properties of the as-consolidated CM-WCN were *** average grain size of WC in the consolidated CM-WCN was calculated to be in the range of 3.0−3.8μm and only few pores were observed.A relative density of 99.6%,hardness of HRA 86.5 and bending strength of 1860 MPa were obtained for the CM-WCN−10wt.%Ni,and the highest impact toughness of 6.17 J/cm^(2 )was obtained for the CM-WCN−12wt.%Ni,surpassing those of the hand mixed WC−Ni(HM-WCN)cemented carbides examined in this study and the other similar materials in the ***-WCN cemented carbides possess excellent mechanical properties,due to their highly uniform structure and low porosity that could be ascribed to the intergranular-dominated fracture mode accompanied by a large number of plastic deformation tears of the bonding *** addition,the corrosion resistance of CM-WCN was superior to that of HM-WCN at the Ni content of 6−12 wt.%.

关键词： WC−Ni cemented carbides chemical co-precipitation method high temperature hydrogen reduction strategy Ni content microstructure impact toughness corrosion resistance

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Initial costates derived by near-optimal reference sequence and least-squares method

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Chinese Journal of Aeronautics 2024年第5期37卷 377-391页

作者： Shaozhao LU yao zhanG Quan hu School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China

In this paper,we present a novel initial costates solver for initializing time-optimal trajectory problems in relative motion with continuous low *** proposed solver consists of two primary components:training a Multilayer Perceptron(MLP)for generating reference sequence and Time of Flight(TOF)to the target,and deriving a system of linear algebraic equations for obtaining the initial *** overcome the challenge of generating training samples for the MLP,the backward generation method is proposed to obtain five different training *** training database and sample form are determined by analyzing the input and output correlation using the Pearson correlation *** best-performing MLP is obtained by analyzing the training results with various hyper-parameter combinations.A reference sequence starting from the initial states is obtained by integrating forward with the near-optimal control vector from the output of ***,a system of linear algebraic equations for estimating the initial costates is derived using the reference sequence and the necessary conditions for *** results demonstrate that the proposed initial costates solver improves the convergence ratio and reduce the function calls of the shooting ***,Monte-Carlo simulation illustrates that the initial costates solver is applicable to different initial velocities,demonstrating excellent generalization ability.

关键词： Relative motion Expanding training database Multilayer perceptron Initial costates Least-squares method

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An infinite-dimensional representation of the Ray-Knight theorems

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Science China Mathematics 2024年第1期67卷 149-162页

作者： Elie Aidékon Yueyun hu zhan Shi School of Mathematical Sciences Fudan UniversityShanghai 200433China LAGA UniversitéSorbonne Paris NordVilletaneuse 93430France Institute of Applied Mathematics Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China

The classical Ray-Knight theorems for the Brownian motion determine the law of its local time process either at the first hitting time of a given value a by the local time at the origin,or at the first hitting time of a given position b by the Brownian *** extend these results by describing the local time process jointly for all a and b,by means of the stochastic integral with respect to an appropriate white *** result applies toμ-processes,and has an immediate application:aμ-process is the height process of a Feller continuous-state branching process(CSBP)with immigration(Lambert(2002)),whereas a Feller CSBP with immigration satisfies a stochastic differential equation(SDE)driven by a white noise(Dawson and Li(2012));our result gives an explicit relation between these two descriptions and shows that the SDE in question is a reformulation of Tanaka’s formula.

关键词： Ray-Knight theorem μ-process white noise Tanaka's formula

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Reduced-complexity multiple parameters estimation via toeplitz matrix triple iteration reconstruction with bistatic MIMO radar

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Chinese Journal of Aeronautics 2024年第7期37卷 482-495页

作者： Chenghong zhan Guoping hu Junpeng SHI Fangzheng ZHAO Hao ZHOU Graduate College Air Force Engineering UniversityXi’an 710051China Air and Missile Defense College Air Force Engineering UniversityXi’an 710051China College of Electronic Countermeasure National University of Defense TechnologyHefei 230037China Beijing Aeronautical Technology Research Center Beijing 100076China

In this advanced exploration, we focus on multiple parameters estimation in bistatic Multiple-Input Multiple-Output(MIMO) radar systems, a crucial technique for target localization and imaging. Our research innovatively addresses the joint estimation of the Direction of Departure(DOD), Direction of Arrival(DOA), and Doppler frequency for incoherent targets. We propose a novel approach that significantly reduces computational complexity by utilizing the TemporalSpatial Nested Sampling Model(TSNSM). Our methodology begins with a multi-linear mapping mechanism to efficiently eliminate unnecessary virtual Degrees of Freedom(DOFs) and reorganize the remaining ones. We then employ the Toeplitz matrix triple iteration reconstruction method, surpassing the traditional Temporal-Spatial Smoothing Window(TSSW) approach, to mitigate the single snapshot effect and reduce computational demands. We further refine the highdimensional ESPRIT algorithm for joint estimation of DOD, DOA, and Doppler frequency, eliminating the need for additional parameter pairing. Moreover, we meticulously derive the Cramér-Rao Bound(CRB) for the TSNSM. This signal model allows for a second expansion of DOFs in time and space domains, achieving high precision in target angle and Doppler frequency estimation with low computational complexity. Our adaptable algorithm is validated through simulations and is suitable for sparse array MIMO radars with various structures, ensuring higher precision in parameter estimation with less complexity burden.

关键词： MIMO Radar Multipleparameters estimation Temporal-spatial Nested Sampling Multi-linear mapping mechanism Toeplitz matrix triple iteration reconstruction Reduce computational complexity

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Active Fault Tolerant Nonsingular Terminal Sliding Mode Control for Electromechanical System Based on Support Vector Machine

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 189-203页

作者： Jian hu Zhengyin Yang Jianyong yao School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China

Effective fault diagnosis and fault-tolerant control method for aeronautics electromechanical actuator is concerned in this *** borrowing the advantages of model-driven and data-driven methods,a fault tolerant nonsingular terminal sliding mode control method based on support vector machine(SVM)is proposed.A SVM is designed to estimate the fault by off-line learning from small sample data with solving convex quadratic programming method and is introduced into a high-gain observer,so as to improve the state estimation and fault detection accuracy when the fault *** state estimation value of the observer is used for state reconfiguration.A novel nonsingular terminal sliding mode surface is designed,and Lyapunov theorem is used to derive a parameter adaptation law and a control *** is guaranteed that the proposed controller can achieve asymptotical stability which is superior to many advanced fault-tolerant *** addition,the parameter estimation also can help to diagnose the system faults because the faults can be reflected by the parameters *** comparative simulation and experimental results illustrate the effectiveness and advancement of the proposed controller compared with several other main-stream controllers.

关键词： Aeronautics electromechanical actuator Fault tolerant control Support vector machine State observer Parametric uncertainty

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Rational modulation of electronic structure in PtAuCuNi alloys boosts efficient electrocatalytic ethanol oxidation assisted with energy-saving hydrogen evolution

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Journal of Energy Chemistry 2024年第6期93卷 557-567,I0014页

作者： hu yao Yinan Zheng Xin Yu Songjie hu Baolian Su Xiaohui Guo Key Lab of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education The College of Chemistry and Materials ScienceNorthwest UniversityXi’an 710069ShaanxiChina Department of Inorganic Chemistry University of NamurBruxellesB-5000 NamurBelgium

Compared to conventional electrocatalytic water splitting,electrocatalytic ethanol oxidation reaction(EOR)along with hydrogen production is considered a more energy-efficient ***,we prepared a type of novel quaternary alloy catalyst(PtAuCuNi@NF)that exhibits excellent activity for EOR(0.215 V at 10 mA cm^(-2))and hydrogen evolution reaction(HER)(7 mV at 10 mA cm^(-2)).Experimental results demonstrated that both Cu and Ni modulated the electronic environment around Pt and *** electron-rich active center facilitates the rapid adsorption and dissociation of reactants and intermediates for both EOR and ***,in the ethanol-assisted overall water splitting(E-OWS),a current density of 10 mA cm^(-2)was achieved at 0.28 ***,an advanced acid-base self-powered system(A-Bsps)that can achieve a self-powered voltage of 0.59 V was ***,the self-driven hydrogen production with zero external power supply was realized by integrating A-Bsps with the E-OWS *** interesting results can provide a feasible strategy for designing and developing advanced nanoalloy-based materials for clean energy integration and use in various fields.

关键词： Pt-based alloy Electronic structure Ethanol oxidation Self-powered system Overall water splitting

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Current Loop Disturbance Suppression for Dual Three Phase Permanent Magnet Synchronous Generators Based on Modified Linear Active Disturbance Rejection Control

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Chinese Journal of Electrical Engineering 2024年第1期10卷 101-113页

作者： Dezhi Xu hu yao Yang He Wenxiang Zhao School of Electrical and Information Engineering Jiangsu UniversityZhenjiang 212013China

A modified four-dimensional linear active disturbance rejection control(LADRC)strategy is proposed for a dual three-phase permanent magnet synchronous generator(DTP-PMSG)system to reduce cross-coupling between the d and q axis currents in the d-q subspace and harmonic currents in the x-y *** the d-q subspace,the proposed strategy uses a model-based LADRC to enhance the decoupling effect between the d and q axes and the disturbance rejection ability against parameter *** the x-y subspace,the 5th and 7th harmonic current suppression abilities are improved by using quasi-resonant units parallel to the extended state observer of the traditional *** proposed modified LADRC strategy improved both the steady-state performance and dynamic response of the DTP-PMSG *** experimental results demonstrate that the proposed strategy is both feasible and effective.

关键词： Dual three-phase permanent magnet synchronous generator current loop decoupling control harmonic suppression linear active disturbance rejection control

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Deciphering a Million-Plus RSA Integer with Ultralow Local Field Coefficient h and Coupling Coefficient J of the Ising Model by D-Wave 2000Q

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Tsinghua Science and Technology 2024年第3期29卷 874-882页

作者： Chao Wang Qiaoyun hu Haonan yao Sumin Wang Zhi Pei Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication Shanghai UniversityShanghai 200444China

This work is the first to determine that a real quantum computer(including generalized and specialized)can decipher million-scale RSA relying solely on quantum algorithms,showing the real attack potential of D-Wave *** influence of different column widths on RSA factorization results is studied on the basis of a multiplication table,and the optimal column method is determined by traversal *** traversal experiment of integer factorization within 10000 shows that the local field and coupling coefficients are 75%–93%lower than the research of Shanghai University in 2020 and more than 85%lower than that of Purdue University in *** low Ising model parameters are crucial to reducing the hardware requirements,prompting factoring 1245407 on the D-Wave 2000Q real machine.D-Wave advantage already has more than 5000 qubits and will be expanded to 7000 qubits during 2023–2024,with remarkable improvements in decoherence and *** machine is expected to promote the solution of large-scale combinatorial optimization *** of the contributions of this paper is the discussion of the long-term impact of D-Wave on the development of post-quantum cryptography standards.

关键词： quantum annealing RSA D-Wave 2000Q post-quantum cryptography

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Ground settlement and tunnel response due to twin-curved shield tunnelling in soft ground with small clear distance

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3122-3135页

作者： yao hu Haoran Tang Yinggang Xu huayang Lei Peng Zeng Kai yao Yabo Dong State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu610059China Research Center of Tunneling and Underground Engineering of Ministry of Education Beijing Jiaotong UniversityBeijing100044China College of Environment and Civil Engineering Chengdu University of TechnologyChengdu610059China School of Civil Engineering Tianjin UniversityTianjin300350China School of Qilu Transportation Shandong UniversityJinan250002China Power China Sinohydro Bureau 7 Co. Ltd.Chengdu610213China

Twin curved tunnels are often encountered in shield tunnelling,where significant complexities in densely exploited underground space are *** this study,the ground settlement and tunnel deformation due to twin-curved shield tunnelling in soft ground were investigated using numerical simulation and field *** curvature radii of twin curved tunnels and subsequent effects of tunnel construction were considered to reveal the tunnelling effect on ground surface settlement and tunnel *** results show that the settlement trough yields one offset towards inside of curved shield *** location of settlement trough and maximum settlement were affected by curvature radius but except for the shape and width of settlement *** parallel twin-curved shield tunnelling could increase the offset of existing settlement trough and maximum ***,an empirical prediction of surface settlement trough due to twin-curved shield tunnelling with same tunnel diameters in soft clay was proposed,which was applicable to curvature radius less than 800 ***,a minimum radius of 600 m of curvature tunnel was proposed in terms of allowable convergence deformation of *** result could provide guidance on safety evaluation for twin curved shield tunnelling construction.

关键词： Shield tunnelling Curvature radius Ground settlement Tunnel deformation Numerical simulation

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Predicting stability of integrated circuit test equipment using upper side boundary values of normal distribution

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The Journal of China Universities of Posts and Telecommunications 2024年第2期31卷 85-93页

作者： zhan Wenfa hu Xinyi Zheng Jiangyun Yu Chuxian Cai Xueyuan zhang Lihua School of Electronic Engineering and Intelligent Manufacturing Anqing Normal UniversityAnqing 246133China School of Computer and Information Technology Anqing Normal UniversityAnqing 246133China

In response to the growing complexity and performance of integrated circuit(IC),there is an urgent need to enhance the testing and stability of IC test equipment.A method was proposed to predict equipment stability using the upper side boundary value of normal ***,the K-means clustering algorithm classifies and analyzes sample *** accuracy of this boundary value is compared under two common confidence levels to select the optimal threshold.A range is then defined to categorize unqualified test *** experimental verification,the method achieves the purpose of measuring the stability of qualitative IC equipment through a deterministic threshold value and judging the stability of the equipment by comparing the number of unqualified data with the threshold value,which realizes the goal of long-term operation monitoring and stability analysis of IC test equipment.

关键词： K-means clustering algorithm the upper side boundary of normal distribution threshold integrated circuit(IC)test equipment stability analysis

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