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Effects of the Reversely Rotating Assisted Shoulder on Microstructures During the Reverse Dual-rotation Friction Stir Welding

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journal of Materials Science & Technology 2015年第4期31卷 375-383页

作者： j.q.li H.j.liu State Key Laboratory of Advanced Welding and joining Harbin Institute of Technology Capital Aerospace Machinery Company

The reverse dual-rotation friction stir welding(RDR-FSW) has the capability to adjust the heat generation because of the separately designed tool shoulder and tool *** welding torque exerted on the workpiece by the reversely rotating shoulder is opposite to that exerted by the rotating tool pin,so the total welding torque is reduced,which is beneficial to reducing the clamping requirement of *** the present paper,a RDR-FSW joint was welded in a condition similar to the optimal welding condition of conventional FSW,and microstructures in various zones were investigated by comparison,aiming to highlight effects of the reversely rotating assisted *** to the heat conduction of the middle cylinder and the bottom end cover on which the assisted shoulder was machined,the thermal effect of RDR-FSW was smaller than that of the conventional ***,the effect of assisted shoulder on the plastic flow or deformation of material or was constrained in a thin layer near the weld top surface,and thus the flow of material especially along the thickness direction was clearly decreased in the *** the heat-affected zone(HAZ),the precipitate coarsening was the main evolution and was completed through the dissolution of small precipitates and the continuous growth of large *** contrast,the dissolution degree of precipitates increased significantly in the thermomechanically affected zone(TMAZ),and a small amount of original meta-stable precipitates transformed to block-shaped stable *** evolutions in the shoulder affected zone(SAZ)and the weld nugget zone were similar,*** majority of original meta-stable precipitates dissolved into the matrix and the remainder transformed to stable precipitates,though the dissolution degree was greater in the *** with the conventional FSW joint,the coarsening degrees of precipitates in the HAZ and TMAZ of RDR-FSW joint were much smaller,as well as the dissolution degrees of p

关键词： Friction stir welding Reverse dual-rotation fricti

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Microstructural features of Ti-6Al-4V manufactured via high power laser directed energy deposition under low-cycle fatigue

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journal of Materials Science & Technology 2021年第24期83卷 18-33页

作者： Y.M.Ren X.lin H.O.Yang H.Tan j.Chen Z.Y.jian j.q.li W.D.Huang School of Materials and Chemical Engineering Xi’an Technological UniversityXi’an710021China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China

Laser additive manufacturing(LAM)technique has unique advantages in producing geometrically complex metallic ***,the poor low-cycle fatigue property(LCF)of LAM parts restricts its widely ***,the microstructural features of a Ti-6 Al-4 V alloy manufactured via high power laser directed energy deposition subjected to low-cycle fatigue loading were *** fatigue loading,the microstructure of the as-deposited parts was found to exhibit a non-homogeneous distribution of columnar prior-βgrains(200-4000μm)at various scanning velocities(300-1500 mm/min)and relatively coarseα-laths(1.0-4.5μm).Under cyclic loading,fatigue microcracks typically initiated within the alignedαphases in the preferred orientation(45°to the loading direction)at the surface of the fatigue *** Ti-6 Al-4 V exhibited a single straight dislocation character at low strain amplitudes(litudes(>1.1%).In addition,dislocation substructure features,such as dislocation walls,stacking faults,and dislocation networks,were also *** findings may provide opportunities to understand the fatigue failure mechanism of additive manufactured titanium parts.

关键词： Laser additive manufacturing Directed energy deposition Titanium alloy Low-cycle fatigue Microstructure

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The Three-Dimensional TWT Multi-Signal Nonlinear Beam-Wave Interaction

The Three-Dimensional TWT Multi-Signal Nonlinear Beam-Wave I...

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2002 3rd International Conference on Microwave and Millimeter Wave Technology

作者： j.q.li Y.L.Mo Y.Zhang Institute of High Energy Electronics University of Electronic Science and Technology of China

＜正＞Based upon the model of Rowe’s transmission -line equivalent circuit,using the maximal common submultiple fundamental frequency,a 3-dimensional（3D） multi-signal nonlinear model of beam-wave interaction in a helix traveling-wave tube （TWT） has been *** 3D model describes 2D RF fields,3D ac space-charge fields and 3D ac electron *** model has been implemented in the HTWT3D code,which can calculate any number of simultaneous signals,including input signals and their intermodulation *** from the HTWT3D code are shown to compare with measurements of output powers *** power.

关键词： Radio frequency Power generation Transmission lines Equivalent circuits Electron beams Power system modeling Communication systems Artificial satellites Space charge Optical modulation

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Wetting Behaviours of a Single Droplet on Biomimetic Micro Structured Surfaces

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journal of Bionic Engineering 2010年第2期7卷 191-198页

作者： Y.q.Zu~1,Y.Y.Yan~1,j.q.li~2,Z.W.Han~2 1.Faculty of Engineering,University of Nottingham,Nottingham NG7 2RD,UK 2.Key Laboratory of Bionic Engineering (Ministry of Education,China),jilin University,Changchun 130022,P.R.China Faculty of Engineering University of Nottingham Nottingham UK Key Laboratory of Bionic Engineering (Ministry of Education China) Jilin University Changchun P. R. China

Natural surfaces with super hydrophobic properties often have micro or hierarchical *** this paper, the wettingbehaviours of a single droplet on biomimetic micro structured surfaces with different roughness parameters are *** model is proposed to study wetting *** results of theoretical analysis are compared with those of experimentindicating that the proposed model can effectively predict the wetting ***, a numerical simulationbased on the meso scale Lattice Boltzmann Method （LBM） is performed to study dynamic contact angles, contact lines, andlocal velocity fields for the case that a droplet displays on the micro structured surface.A spherical water droplet with r= 15 μmfalls down to a biomimetic square-post patterned surface under the force of gravity with an initial velocity of 0.01 m·sand aninitial vertical distance of 20 μm from droplet centre to the top of *** spite of a higher initial velocity, the droplet can stillstay in a Cassie state; moreover, it reaches an equilibrium state at t≈17.5 ms, when contact angle is 153.16° which is slightlylower than the prediction of Cassie-Baxter’s equation which gives θ=154.40°.

关键词： biomimetic wetting behaviours roughness surfaces contact angle wetting transition

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(Bx,Cu1-x)Sr2YCu2O7,A NEW LAYERED CUPRATE WITH BORON-OXYGEN GROUPS

(Bx,Cu1-x)Sr2YCu2O7,A NEW LAYERED CUPRATE WITH BORON-OXYGEN ...

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Sixteenth Congress of the International Union of Crystallography

作者： W.j.Zhu Y.Z.Huang j.q.li Z.X.Zhao National Laboratory for Superconductivity Institute of PhysicsAcademia Sinica

New layered cuprates(B,CuSrYCuO have been synthesized with various boron *** crystal structures resemble that of YBaCuO,but contain boron-oxygen groups connecting (CuO) sheets beside Y layers.(B,Cu) forms solid solution with an approximate range of x = *** compound of idealized composition(B,Cu)SrYCuO crystallizes in the orthorhombic structure with cell parameters a=0.383,b=0.381 and c=1.096nm. There is a strong incommensurate modulation in the(100) plane

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Convexification of Hybrid AC-DC Optimal Power Flow with line-Commutated Converters

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CSEE journal of Power and Energy Systems 2024年第2期10卷 617-628页

作者： Hongyuan liang Zhigang li j.H.Zheng q.H.Wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China

line-commutated converter (LCC)-based high-voltage DC (HVDC) systems have been integrated with bulk AC power grids for interregional transmission of renewable power. The nonlinear LCC model brings additional nonconvexity to optimal power flow (OPF) of hybrid AC-DC power grids. A convexification method for the LCC station model could address such nonconvexity but has rarely been discussed. We devise an equivalent reformulation for classical LCC station models that facilitates second-order cone convex relaxation for the OPF of LCC-based AC-DC power grids. We also propose sufficient conditions for exactness of convex relaxation with its proof. Equivalence of the proposed LCC station models and properties, exactness, and effectiveness of convex relaxation are verified using four numerical simulations. Simulation results demonstrate a globally optimal solution of the original OPF can be efficiently obtained from relaxed model.

关键词： AC-DC power system convex relaxation linecommutated converter optimal power flow second-order cone programming

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Observability Analysis of Integrated Electricity and Heating Systems with Thermal quasi-dynamics in Pipelines

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CSEE journal of Power and Energy Systems 2024年第3期10卷 1145-1158页

作者： Zhigang li Wenjian Zheng junbo Zhao j.H.Zheng q.H.Wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China Fuzhou Changle District Power Supply Company of State Grid Fujian Electric Power Co. Ltd.Fuzhou 350000China Department of Electrical and Computer Engineering University of ConnecticutStorrsCT 06269USA CSEE IEEE

Observability analysis(OA)is vital to obtaining the available input measurements of state estimation(SE)in an integrated electricity and heating system(IEHS).Considering the thermal quasi-dynamics in pipelines,the measurement equations in heating systems are dependent on the estimated results,leading to an interdependency between OA and *** OA methods require measurement equations be known exactly before SE is performed,and they are not applicable to *** bridge this gap,a scenario-based OA scheme for IEHSs is devised that yields reliable analysis results for a predefined set of time-delay scenarios to cope with this *** its core procedure,the observable state identification and observability restoration are formulated in terms of integer linear *** tests are conducted to demonstrate the validity and superiority of the proposed formulation.

关键词： Integrated electricity and heating system measurement observability analysis state estimation thermal quasi-dynamics

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Hybrid heuristics based on harmony search to minimize total flow time in no-wait flow shop

Hybrid heuristics based on harmony search to minimize total ...

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2010 Chinese Control and Decision Conference

作者： K.Z.Gao~1,H.li~1,q.K.Pan~1,j.q.li~1,j.j.liang~2 1 College of Computer Science,liaocheng University,liaocheng,252059,PR China 2 School.Electrical Engineering,Zhengzhou University

＜正＞This paper proposes an effective harmony search（HS） based heuristics method for the no-wait flow-shop scheduling *** purpose of this paper is to minimize the total flow ***,the basic HS optimization mechanism,FSSP is presented and the total flow time is calculated by a novel method. Secondly,a largest-order-value rule is used to transform harmony in harmony memory from real vectors to job sequence so that the harmony search can be applied for *** rule of new harmony is expatiated and high effective algorithm parameters are set for optimization ***,HS and Insert-and interchange-based neighbor search,is proposed to solve the *** last,simulations and comparisons demonstrate the efficiency,effectiveness and robustness of harmony search algorithm for no-wait FSSP.

关键词： Harmony search total flow time no-wait flow shop

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A Hybrid Signal Processing Method Combining Mathematical Morphology and Walsh Theory for Power quality Disturbance Detection and Classification

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CSEE journal of Power and Energy Systems 2024年第2期10卷 584-592页

作者： Zhi Ding Tianyao ji Mengshi li q.H.Wu School of Electric Power Engineering South China University of Technology(SCUT)Guangzhou 510641China

In this paper, a novel signal processing method combining mathematical morphology (MM) and Walsh theory is proposed, which uses Walsh functions to control the structuring element (SE) and MM operators. Based on the Walsh-MM method, a scheme for power quality disturbances detection and classification is developed, which involves three steps: denoising, feature extraction and morphological clustering. First, various evolution rules of Walsh function are used to generate groups of SEs for the multiscale Walsh-ordered morphological operation, so the original signal can be denoised. Next, the fundamental wave of the denoised signal is suppressed by Hadamard matrix;thus, disturbances can be extracted. Finally, the Walsh power spectrum of the waveform extracted in the previous step is calculated, and the parameters of which are taken by morphological clustering to classify the disturbances. Simulation results reveal the proposed scheme can effectively detect and classify disturbances, and the Walsh-MM method is less affected by noise and only involves simple calculation, which has a potential to be implemented in hardware and more suitable for real-time application.

关键词： Hadamard matrix mathematical morphology morphological clustering power quality disturbance Walsh theory

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Structural and magnetic properties of DyCo4-xFexGa compounds

Structural and magnetic properties of DyCo4-xFexGa compounds

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第十届全国X射线衍射学术大会暨国际衍射数据中心（ICDD）研讨会

作者： W.H.Zhang,j.q.li~1,Y.j.Yu,F.S.liu,W.q.Ao College of Materials Science and Engineering,Shenzhen University and Shenzhen Key Laboratory of Special Functional Materials,Shenzhen 518060,P.R.China

The interesting magnetic performances of the intermetallic compounds formed by alloying rare earth and 3d transition metals are due to the combination of the complementary characteristics of 3d-itinerant and 4f-localized *** investigations of the structural and magnetic properties for DyCoM(M=Al,Ga)[4,5],DyCoCu[6]and DyYCo compounds have been *** results indicate that the substitutions of non-magnetic atoms,Al,Ga and Cu for

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