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Deposition behavior of multi-particle impact in cold spraying process

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International Journal of Minerals,Metallurgy and Materials 2010年第5期17卷 635-640页

作者： Xiang-lin Zhou Xiang-kun Wu Hui-hua guo Jian-guo wang Ji-shan zhang State Key Laboratory for Advanced Metals and Materials University of Science mad Technology Beijing Beijing 100083 China

In the practical cold-spraying process, a number of particles impact onto a substrate and then form a coating. To study the deformation behavior and multi-particle interactions, single-particle, two-particle, and three-particle impacts were simulated using the ANSYS/LS-DYNA version 970. A copper coating was prepared and scanning electron microscopy （SEM） was employed to analyze the microstructures of the powders and the coating. Numerical results reveal that the critical deposition velocity is 600 m/s for a copper particle/copper substrate. The particles deform more fully due to multi-particle interactions, such as tamping, interlocking, and extrusion effects. The compression ratio increases from 40% to 70% as a result of the tamping effect. This is beneficial for achieving the cold-sprayed coating. The multi-particle morphology and compression ratio in the experiment are consistent with those of simulation results. Based on these results, the coating of high performance can be prepared through selecting appropriate parameters and suitable pre-treatment processes.

关键词： spraying deposition interfaces particle interactions bonding simulation

Bimodal TBCs with low thermal conductivity deposited by a powder-suspension co-spray process

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Journal of Materials Science & Technology 2018年第8期34卷 1293-1304页

作者： Wei-Wei zhang Guang-Rong Li Qiang zhang Guan-Jun Yang guo-wang zhang Hong-Min Mu State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi'an Jiaotong UniversityXi'an 710049China School of Materials Science and Engineering Chang'an UniversityXi'an 710064China Institute of Publication Science Chang'an UniversityXi'an 710064China AECC Beijing Institute of Aeronautical Material Beijing 100095China

Advanced thermal harrier coatings （TBCs） with better thermal barrier performance are required by both advanced gas turbine and air engine. In this work, novel bimodal TBCs with low thermal conductivity were deposited and characterized by a novel co-spray approach with both solid powder and suspension. Experimental and finite element analyses were used to optimize the process parameters to prepare the specific morphology nanostructure features. With a comprehensive understanding on the influence of spraying parameters on the morphology ofnano-particles, homogeneous nano-particle heaps with a large aspect ratio were introduced to conventional layered coatings by plasma co-spraying with suspension and solid powder. Co-sprayed bimodal microstructure composite coatings resulted from both wet suspension droplets and molten particle droplets exhibited low thermal conductivity. The thermal conductivity of the composite coating was 1/5 lower than that of the counterpart coatings by conventional plasma spraying with solid powder. This study sheds light to the structural tailoring towards the advanced TBCs with low thermal conductivity.

关键词： Thermal barrier coatings Aspect ratioBimodal microstructure Thermal conductivity Co-spray process

A Local Tb Theorem for Square Functions and Parabolic Layer Potentials

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Acta Mathematica Sinica,English Series 2024年第8期40卷 1941-1966页

作者： Zhi Dan wang guo Ming zhang School of Physical and Mathematical Sciences Nanjing Tech UniversityNanjing 211816P.R.China Frontiers Science Center for Nonlinear Expectations Ministry of EductionResearch Center for Mathematics and Interdisciplinary SciencesShandong UniversityQingdao266237P.R.China

In this paper,we give a locally parabolic version of Tb theorem for a class of vector-valued operators with off-diagonal decay in L^(2) and certain quasi-orthogonality on a subspace of L^(2),in which the testing functions themselves are also *** an application,we establish the boundedness of layer potentials related to parabolic operators in divergence form,defined in the upper half-space Rn+2+:={(x,t,λ)∈R^(n+1)×(0,∞)},with uniformly complex elliptic,L^(∞),t,λ-independent coefficients,and satisfying the De Giorgi/Nash estimates.

关键词： Local Tb theorems Calderon-Littlewood-Paley family Parabolic layer potentials Carleson measure estimates

An effective strategy of constructing multi-metallic oxides of ZnO/ CoNiO_(2)/CoO/C microflowers for improved supercapacitive performance

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Chinese Journal of Chemical Engineering 2024年第3期67卷 1-8页

作者： Wei guo Yan zhang Xiaxin Lei Shuang wang College of Physics Taiyuan University of TechnologyJinzhong 030600China College of Environmental Science and Engineering Taiyuan University of TechnologyJinzhong 030600China Shanxi Key Laboratory of Gas Energy Efficient and Clean Utilization Taiyuan University of TechnologyTaiyuan 030024China

In this work,a new ZnO/CoNiO_(2)/CoO/C metal oxides composite is prepared by cost-effective hydrothermal method coupled with annealing process under N_(2) ***,the oxidation-defect annealing environment is conducive to both morphology and component of the composite,which flower-like ZnO/CoNiO_(2)/CoO/C is *** from good chemical stability of ZnO,high energy capacity of CoNiO_(2) and CoO and good conductivity of C,the as-prepared sample shows promising electrochemical behavior,including the specific capacity of 1435 C·g^(-1) at 1 A·g^(-1),capacity retention of 87.3%at 20 A·g^(-1),and cycling stability of 90.5%for 3000 cycles at 5 A·g^(-1),***,the prepared ZnO/CoNiO_(2)/CoO/C/NF//AC aqueous hybrid supercapacitors device delivers the best specific energy of 55.9 W·h·kg^(-1) at 850 W·kg^(-1).The results reflect that the as-prepared ZnO/CoNiO_(2)/CoO/C microflowers are considered as high performance electrode materials for supercapacitor,and the strategy mentioned in this paper is benefit to prepare mixed metal oxides composite for energy conversion and storage.

关键词： Composites Electrochemistry Hydrothermal Transition metal oxides Structural control Supercapacitors

Coupled funnel control for supersonic tailless aerial vehicle on penetrating counter air

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Chinese Journal of Aeronautics 2024年第7期37卷 458-481页

作者： Yingyang wang Peng zhang Jilian guo Jianbo HU Equipment Management and Unmanned Aerial Vehicle Engineering School Air Force Engineering UniversityXi’an 710051China Aviation Engineering School Air Force Engineering UniversityXi’an 710038China

Supersonic Tailless Aerial Vehicles(STAVs)will become an essential force in Penetrating Counter Air(PCA),but STAVs do not have the traditional horizontal and vertical tails,making pitch and yaw control *** attack angle and the sideslip angle need to be limited to ensure that the engine inlet and the aerodynamic rudder at the rear of the vehicle can work properly,which is the so-called security *** addition,the tracking error of the aerodynamic angle needs to be limited to achieve effective attitude control or high-accuracy tracking of trajectories,which is the so-called performance *** this end,an attitude control method that meets the needs of PCA has been devised,based on constraint definition,coupled constraints handling,and control law ***,mathematical descriptions of the security constraints,performance constraints,and control constraints are ***,two treatment methods,coupled command filter and coupled funnel control are proposed for the aerodynamic angle coupled constraint ***,based on Nonlinear Dynamic Inverse(NDI)design,the coupled funnel controller is designed and validated by simulation for two typical mission scenarios,high-altitude penetration and low-altitude surprise *** proposed control method not only satisfies the security and performance constraints of STAV attitude control but also is highly robust.

关键词： Supersonic tailless aircraft Penetrating counter air Funnel control Attitude control Control allocation

Role of A-sites in pyrochlore lanthanide ruthenate for electrocatalysis of oxygen evolution reaction

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Journal of Materiomics 2024年第6期10卷 1234-1242页

作者： Hengyu guo Zhengping zhang Feng wang State Key Laboratory of Chemical Resource Engineering Beijing Key Laboratory of Electrochemical Process and Technology for MaterialsBeijing University of Chemical TechnologyBeijing100029China Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical TechnologyBeijing100029China

Developing highly stable and efficient catalysts for oxygen evolution reaction(OER)is extremely important to sustainable energy conversion and storage,but improved efficiency is largely hindered by sluggish reaction *** and bimetal ruthenates have emerged as one of the promising substitutes to replace single-metal ruthenium or iridium oxides,but the fundamental understanding the role of A-site cations is still ***,a family of lanthanides(Ln=all the lanthanides except Pm)are applied to synthesize pyrochlore lanthanide ruthenates(Ln_(2)Ru_(2)O_(7)),and only Ln_(2)Ru_(2)O_(7)(Ln=Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,or Lu)with pure phase can be obtained by the ambient-pressure *** with the perovskite ruthenates(SrRuO_(3))and rutile RuO_(2),the[RuO_(6)]units in these Ln_(2)Ru_(2)O_(7) present the largely distorted configurations and different energy level splitting to prevent the excessive Ru oxidation and dissolution,which leads the primary improvement in the electrocatalytic OER *** the similar crystalline field split states,the charge transfer between[RuO6]units and Ln^(3+)cations also affect catalytic activities,even in the Ln_(2)Ru_(2)O_(7) surface reconstruction during the OER ***,Tb_(2)Ru_(2)O_(7) showed the highest OER performance among all the prepared Ln_(2)Ru_(2)O_(7) with similar morphologies and *** systematic work gives fundamental cognition to rational design of high-performance OER electrocatalysts in proper water electrolysis technologies.

关键词： Pyrochlores Lanthanides Ruthenates Electrocatalysts Oxygen evolution reaction

Three-dimensional structural models,evolution and petroleum geological significances of transtensional faults in the Ziyang area,central Sichuan Basin,SW China

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Petroleum Exploration and Development 2024年第3期51卷 604-620页

作者： TIAN Fanglei guo Tonglou HE Dengfa GU Zhanyu MENG Xianwu wang Renfu wang Ying zhang Weikang LU guo School of Energy Resources China University of Geosciences(Beijing)Beijing 100083China Key Laboratory of Marine Reservoir Evolution and Hydrocarbon Enrichment Mechanism Ministry of EducationBeijing 100083China Sinopec Southwest Oil and Gas Company Chengdu 610031China

With drilling and seismic data of Transtensional(strike-slip)Fault System in the Ziyang area of the central Sichuan Basin,SW China plane-section integrated structural interpretation,3-D fault framework model building,fault throw analyzing,and balanced profile restoration,it is pointed out that the transtensional fault system in the Ziyang 3-D seismic survey consists of the northeast-trending F_(I)19 and F_(I)20 fault zones dominated by extensional deformation,as well as 3 sets of northwest-trending en echelon normal faults experienced dextral shear *** them,the F_(I)19 and F_(I)20 fault zones cut through the Neoproterozoic to Lower Triassic Jialingjiang Formation,presenting a 3-D structure of an“S”-shaped *** before Permian and during the Early Triassic,the F_(I)19 and F_(I)20 fault zones underwent at least two periods of structural ***,the 3 sets of northwest-trending en echelon normal faults are composed of small normal faults arranged in pairs,with opposite dip directions and partially left-stepped *** before Permian,they had formed almost,restricting the eastward growth and propagation of the F_(I)19 fault *** F_(I)19 and F_(I)20 fault zones communicate multiple sets of source rocks and reservoirs from deep to shallow,and the timing of fault activity matches well with oil and gas generation *** there were favorable Cambrian-Triassic sedimentary facies and reservoirs developing on the local anticlinal belts of both sides of the F_(I)19 and F_(I)20 fault zones,the major reservoirs in this area are expected to achieve breakthroughs in oil and gas exploration.

关键词： transtensional(strike-slip)fault three-dimensional structural model structural evolution petroleum geological significance Ziyang area Sichuan Basin

Prescribed Performance Tracking Control of Time-Delay Nonlinear Systems With Output Constraints

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IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1557-1565页

作者： Jin-Xi zhang Kai-Di Xu Qing-guo wang IEEE the State Key Laboratory of Synthetical Automation for Process Industries Northeastern UniversityShenyang 110819China Institute of Artificial Intelligence and Future Networks Beijing Normal UniversityZhuhai 519087 Guangdong Key Laboratory of Artificial Intelligence and Multi-Modal Data Processing Beijing Normal University-Hong Kong Baptist University United International CollegeZhuhai 519087

The problem of prescribed performance tracking control for unknown time-delay nonlinear systems subject to output constraints is dealt with in this paper. In contrast with related works, only the most fundamental requirements, i.e., boundedness and the local Lipschitz condition, are assumed for the allowable time delays. Moreover, we focus on the case where the reference is unknown beforehand, which renders the standard prescribed performance control designs under output constraints infeasible. To conquer these challenges, a novel robust prescribed performance control approach is put forward in this ***, a reverse tuning function is skillfully constructed and automatically generates a performance envelop for the tracking error. In addition, a unified performance analysis framework based on proof by contradiction and the barrier function is established to reveal the inherent robustness of the control system against the time delays. It turns out that the system output tracks the reference with a preassigned settling time and good accuracy,without constraint violations. A comparative simulation on a two-stage chemical reactor is carried out to illustrate the above theoretical findings.

关键词： Nonlinear systems output constraints prescribed performance reference tracking time delays

Evolution of microstructure and texture of AZ80 magnesium alloy under hot torsion with constant decreasing temperature rate

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Journal of Magnesium and Alloys 2024年第4期12卷 1619-1637页

作者： Yongbiao Yang Jinxuan guo Cuiying wang Wenxuan Jiang Zhimin zhang Qiang wang Xing zhang College of Materials Science and Engineering North University of ChinaLane 3Xueyuan RoadTaiyuanShanxi 030051China North Hongyang mechanical and electronic limited company of Henan Province China

Hot torsion tests for AZ80 magnesium alloy were carried out in the temperature range of 380℃-260℃,with a constant decreasing temperature rate of 10℃/s in order to weaken the basal texture and refine the *** results indicated that the average grain sizes were refined forming gradient structure with increasing specimen radial position from center(12.2-5.4μm),and that the initial basal texture intensity of the extruded magnesium alloy was weakened from 46.2 to ***,the extension twins(ETs)could be disintegrated from the twins forming separated twins with smaller ***,ETs with the same twin variant intersecting with each other could be coalesced forming grains with similar orientation,while ETs with different twin variants were separated by twins boundaries contributing to grain ***,in addition to the conventional continuous dynamic recrystallized(CDRX)grains with 30˚orientation rotated around C-axis of the parent grains,CDRXed grains with 30˚rotation around a-axis and random rotation axis were also ***,the CDRX evolution induced twins were also elaborated,exhibiting the complex competition between CDRX and *** torsion deformation with constant decreasing temperatures rate is an effective way of grain refinement and texture modification.

关键词： Texture Microstructure Hot torsion Decreasing temperature AZ80