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Structural topology optimization subject to overhang angle constraint with overhang length relaxation in additive manufacturing

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Science China(Technological Sciences) 2022年第6期65卷 1213-1231页

作者： ZHANG KaiQing CHENG GengDong wang yu Department of Engineering Mechanics Dalian University of TechnologyDalian 116023China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116023China

This paper studies additive manufacturing(AM) oriented structural topology optimization(TO).The minimum compliance design subject to overhang angle constraint with overhang length relaxation and horizontal minimum length control is *** the overhang length relaxation allows additional flexibility for AM product design,there have been very limited studies on *** paper elucidates that the overhang angle constraint we proposed can identify the lower boundary element that violates the overhang angle *** advantage of this fact,we achieve the overhang length relaxation by specifying that the volume fraction of the elements that violate the overhang angle constraint in each local area of the design domain is less than a specified upper bound.A formula for estimating the maximum allowable overhang length of this method is proposed and *** horizontal minimum length constraint is also employed in this *** controlling the horizontal length size of the structural member,this constraint together with the overhang angle constraint with overhang length relaxation suppresses the hanging *** gradient-based optimization algorithm method of moving asymptotic(MMA) is used to solve the TO *** examples show the effectiveness of this *** is observed that the new constraint alleviates the main issues of traditional overhang angle constraints,i.e.,gray element issue,stress concentration issue,and shattered structure *** with the strict traditional overhang angle constraint,the new formulation reduces structural compliance.

关键词： topology optimization overhang angle constraint overhang length relaxation design for manufacturability additive manufacturing

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An adaptive distributed auction algorithm and its application to multi-AUV task assignment

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Science China(Technological Sciences) 2023年第5期66卷 1235-1244页

作者： wang yu LI HuiPing YAO Yao School of Marine Science and Technology Northwestern Polytechnical UniversityXi’an 710072China Jiangsu Automation Research Institute Lianyungang 222061China

The task assignment of multi-agent system has attracted considerable attention;however,the contradiction between computational complexity and assigning performance remains to be *** this paper,a novel consensus-based adaptive optimization auction(CAOA)algorithm is proposed to greatly reduce the computation load while attaining enhanced system payoff.A new optimization scheme is designed to optimize the critical control parameter in the price update role of auction algorithm which can reduce the searching complexity in obtaining a better bidding *** this new scheme,the CAOA algorithm is *** the developed algorithm is applied to the multi-AUV task assignment problem for underwater detection mission in complex *** simulation and comparison studies verify the effectiveness and advantage of the CAOA algorithm.

关键词： task assignment multi-agent systems consensus-based adaptive optimization auction intelligent algorithm multiple AUVs

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Selective Acceleration in Impulsive Solar Flares

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Chinese Physics Letters 2001年第9期18卷 1291-1293页

作者： wang De-yu Purple Mountain Observatory Chinese Academy of SciencesNanjing 210008 National Astronomical Observatories Chinese Academy of SciencesBeijing 100012

A plasma acceleration mechanism is proposed to explain the dramatic enhancement in the ratio of 3 He/4He, (enhancement factor 102-103) observed in solar 3He-rich flares. Considering that coronal plasma is mainly composed of hydrogen and helium ions, the hydrogen ion-helium ion hybrid waves and quasi-perpendicular waves can be excited by energetic electron beam during the impulsive solarflares. The frequencies of these waves are close to the ^(3)He^(++) ion gyrofrequency, but far from the ^(4)He^(++ ) ion gyrofrequency. Most of these waves are selectively absorbed by 3He ions. These preheated 3He ions can be successively stochastic accelerated by Alfvén turbulence, when their velocities are larger than the local Alfvén velocity. It makes the ratio of 3He/4He dramatically enhanced and the acceleration energy spectrum of 3He ions forms a power-law distribution during the impulsive solar flares.

关键词： acceleration heated turbulence

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A method for the length-pressure hysteresis modeling of pneumatic artificial muscles

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Science China(Technological Sciences) 2020年第5期63卷 829-837页

作者： XIE ShengLong LIU HaiTao &wang yu School of Mechanical and Electrical Engineering China Jiliang UniversityHangzhou 310018China Key Laboratory of Mechanism Theory and Equipment Design Ministry of EducationTianjin UniversityTianjin 300072China

This paper presents a method for the length-pressure hysteresis modeling of pneumatic artificial muscles(PAMs)by using a modified generalized Prandtl-Ishlinskii(GPI)*** from the approaches for establishing the GPI models by replacing the linear envelope functions of operators with hyperbolic tangent and exponential envelop functions,the proposed model is derived by modifying the envelope functions of operators into arc tangent functions,which shows an improvement in the modeling *** effectiveness of the proposed model is verified by the experimental data of a ***,its capacity in capturing the hysteresis relationship between length and pressure is testified by giving different input pressure *** regard to the computational efficiency,the influence of the number of operators on the modeling accuracy is ***,the inversion of the GPI model is *** capability of compensating the hysteresis nonlinearities is confirmed via the simulation and experimental study.

关键词： modified generalized Prandtl-Ishlinskii model pneumatic artificial muscle hysteresis envelope function control

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Preparation and oxidation characteristics of ZrC-ZrB2 composite powders with different proportions

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International Journal of Minerals,Metallurgy and Materials 2022年第3期29卷 521-528页

作者： yu wang Guohua Zhang Kuochih Chou State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

ZrC and ZrB2 are both typical ultra-high temperature ceramics,which can be used in the hyperthermal *** this study,a method for preparing ultrafine ZrC-ZrB2 composite powder was provided,by using the raw materials of nano ZrO2,carbon black,B4C,and metallic *** is worth pointing out that ZrC-ZrB2 composite powder with any proportion of ZrC to ZrB2 could be synthesized by this ***,a mixture of ZrC and C was prepared by carbothermal reduction of *** adjusting the addition amount of B4C,ZrC was boronized by B4C to generate ZrC-ZrB2 composite powder with different *** this method,five composite powders with different molar ratios of ZrC and ZrB2(100ZrC,75ZrC-25ZrB2,50ZrC-50ZrB2,25ZrC-75ZrB2,and 100ZrB2)were *** the temperature of boronization and decarburization process was 1473 K,the particle size of product was only tens of ***,the oxidation charac-teristics of different composite powders were investigated through oxidation *** oxidation resistance of ZrC-ZrB2 composite powder continued to increase as the content of ZrB2 increased.

关键词： borides carbides core-shell structures powders ultra-high temperature ceramic

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Target detection for low angle radar based on multi-frequency order-statistics

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Journal of Systems Engineering and Electronics 2015年第2期26卷 267-273页

作者： yunhe Cao Shenghua wang yu wang Shenghua Zhou National Laboratory of Radar Signal Processing Xidian University

For radar targets flying at low altitude, multiple pathways produce fade or enhancement relative to the level that would be expected in a free-space environment. In this paper, a new detec- tion method based on a wide-ranging multi-frequency radar for low angle targets is proposed. Sequential transmitting multiple pulses with different frequencies are first applied to decorrelate the cohe- rence of the direct and reflected echoes. After receiving all echoes, the multi-frequency samples are arranged in a sort descending ac- cording to the amplitude. Some high amplitude echoes in the same range cell are accumulated to improve the signal-to-noise ratio and the optimal number of high amplitude echoes is analyzed and given by experiments. Finally, simulation results are presented to verify the effectiveness of the method.

关键词： multipath signal detection order statistic multi-frequency low angle

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A 3D nonlinear finite element method for the dynamic analysis of rotating rotor with a transverse crack

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Science China(Technological Sciences) 2017年第2期60卷 219-231页

作者： wang Shuai ZI YanYang wang yu HE ZhengJia State Key Laboratory for Manufacturing and Systems Engineering School of Mechanical Engineering Xi'an Jiaotong University Xi'an 710049 China

A general and efficient method is presented in this paper for studying the effects of unbalance on the breathing mechanism of *** on 3D finite element models combined with a nonlinear contact approach for crack modeling, the method is free from theassumption of weight-dominance and can be used to gain deep insights into the breathing mechanism of crack. In order to greatlyreduce the computational time, a complex free-interface component mode synthesis (CMS) method is employed to reduce theorder of the model. Based on the proposed method, the effects of unbalance on the breathing mechanism of crack are *** results show that the unbalance can lead to significant changes in the breathing of crack, even when the unbalance force is about an order of magnitude smaller than the self-weight. Moreover, the level and orientation of the unbalance have also remarkable effects on the breathing behaviors of crack. Besides, a new universal non-steady breathing phenomenon of crack is firstly found in this paper, which denotes that the breathing speed of a crack is fluctuated over one revolution when there exists residual unbalance in the cracked rotor.

关键词： cracked rotor breathing mechanism of crack unbalance 3D finite element model model order reduction

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Effect of ion-beam assisted deposition on the film stresses of TiO_2 and SiO_2 and stress control

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Acta Mechanica Sinica 2012年第5期28卷 1382-1388页

作者： yu-Qiong Li Hua-Qing wang Wu-yu wang Zhi-Nong yu He-Shan Liu Gang Jin National Microgravity Laboratory(NML) Institute of MechanicsChinese Academy of Sciences School of Optoelectronics Beijing Institute of Technology Optical Thin Film Center Daheng New Epoch Technology Inc. Beijing General Research Institute for Nonferrous Metals Division of Mineral Research and Material Energy

Based on Hartmann-Shack sensor technique, an online thin film stress measuring system was introduced to measure the film stresses of TiO2 and SiO2, and comparison was made between the film stresses prepared respectively by the conventional process and the ion-beam assisted deposition. The effect of ion-beam assisted deposition on the film stresses of TiO2 and SiO2 was investigated in details, and the stress control methodologies using on-line adjustment and film doping were put forward. The results show that the film stress value of TiO2 prepared by ion-beam assisted deposition is 40 MPa lower than that prepared by conventional process, and the stress of TiO2 film changes gradually from tensile stress into compressive stress with increasing ion energy; while the film stress of SiO2 is a tensile stress under ion-beam assisted deposition because of the ion-beam sputtering effect, and the film refractive index decreases with increasing ion energy. A dynamic film stress control can be achieved through in-situ adjustment of the processing parameters based on the online film stress measuring technique, and the intrinsic stress of film can be effectively changed through film doping.

关键词： Film stress Stress controlling Ion-beam as-sisted deposition Hartmann-Shack sensor

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A Note on Commutators with Power Central Values on Lie Ideals

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Acta Mathematica Sinica,English Series 2006年第6期22卷 1715-1720页

作者： yu wang Hong YOU College of Mathematics Jilin Normal University Siping 136000 P. R. China College of Sciences Harbin Institute of Technology Harbin 150001 P. R. China

This note proves that, if R is a prime ring of characteristic 2 with d a derivation of R and L a noncentral Lie ideal of R such that [d（u）,u]^n is central, for all u ∈ L, then R must satisfy s4, the standard identity in 4 variables. The case where R is a semiprime ring is also examined by the authors. The results of the note improve Carini and Filippis＇s results.

关键词： prime ring semiprime ring lie ideal derivation

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Spectral properties and Judd-Ofelt analysis of novel red phosphors Gd_(2)InSbO_(7):Eu^(3+)with high color purity for white LEDs

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Journal of Rare Earths 2021年第11期39卷 1327-1335,I0001页

作者： yu wang Baokui Zhao Bin Deng Shanshan Chen yuanyuan Liu a Guodong wang Ruijin yu College of Chemistry&Pharmacy Northwest A&F UniversityYangling 712100China College of Science Northwest A&F UniversityYangling 712100China College of Chemistry&Biology and Environmental Engineering Xiangnan UniversityChenzhou 423043China Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds Research and Application Chenzhou 423043China

Gd_(2)InSbO_(7):Eu^(3+)red phosphors we re successfully synthesized via high-temperature solid-state reactio *** phase purity,particle size,and luminescence properties of obtained phosphors were measured and analyzed in *** Gd_(2)InSbO_(7)lattice possesses cubic structure with F_(d-3 m)(227)space *** phosphors emit bright red emission at 628 nm under 393 nm excitation,and this phenomenon is attributed to the^(5)D0-^(7)F_(2)*** Judd-Ofelt parameters(Ω_(2),Ω_(4)),transition ratio,and branching ratios(β)of Eu^(3+)-doped Gd_(2)InSbO_(7)phosphor were calculated on the basis of the emission spectra and decay *** optimal content in Gd_(2)InSbO_(7):xEu^(3+)is identified to be 15 mol%.The thermal quenching of Gd_(2)InSbO_(7):Eu^(3+)is found to be over 500 K,and its activation energy is 0.26 *** Commission Internationale de l’Eclairage(CIE)chromaticity coordinates of Gd_(2)InSbO_(7):15%Eu^(3+)are(0.629,0.371),which are close to ideal red chromaticity coordinates(0.670,0.330).The fabricated w-LED exhibits good color rendering index(Ra)(86),correlated color temperature(CCT)(6997 K),and CIE chromaticity coordinates(0.302,0.330).The obtained results demonstrate that Gd_(2)InSbO_(7):Eu^(3+)phosphors have potential applications in white LEDs.

关键词： Luminescence Phosphor Antimonate Gd_(2)InSbO_(7) Rare earths

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