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Improving the forming performance of incrementally formed sheet parts with customized heat treatment strategies

Advances in Manufacturing 2023年第2期11卷 264-279页

作者： Hao yuan Yan-Le Li yuan-Yu Liu gang-Lin Zhao Fang-Yi Li Key Laboratory of High Efficiency and Clean Mechanical Manufacture Ministry of EducationSchool of Mechanical EngineeringShandong UniversityJinan250061People's Republic of China National Demonstration Center for Experimental Mechanical Engineering Education Shandong UniversityJinan250061People's Republic of China

Although incremental sheet forming(ISF)is an efficient way to manufacture customized parts,the forming performance and geometric accuracy of formed parts need to be improved to meet industrial *** feasible solution for these problems is to adopt proper heat treatment strategies for the sheet material both before and during the forming *** this paper,the effects of heat treatment before forming and heat-assisted forming on the formability and performance of formed parts were experimentally ***,TA1 sheets were heat-treated at different temperatures before forming,and then the sheets were incrementally formed into the target shape with variable angles at different *** heat treatment,the strength of sheets was decreased due to the occurrence of recrystallization and the growth of ***,the surface quality of formed parts was also improved with pre-heat treatment before *** the heat-assisted forming process,the sheet was softened and the deformation resistance was reduced with the increase of ***,the axial forming force was decreased obviously and the formability of the sheet was increased ***,by adopting both heat treatment and heat-assisted forming,it was found that the forming force could be further reduced and the formability of the sheet and surface quality could be further *** for geometric accuracy,heat treatment has a good effect on improving it,while heat-assisted forming has adverse *** findings provide an effective heat treatment strategy for improving the geometric accuracy and surface quality of the incrementally formed parts with lower forming force.

关键词： Incremental sheet forming(ISF) Heat-assisted forming Heat treatment Forming force Formability

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Numerical Simulation of Random Wave Overtopping of Rubble Mound Breakwater with Armor Units

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China Ocean Engineering 2021年第2期35卷 176-185页

作者： LI Jing-yuan ZHANG qing-he LU Yong-jun State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research InstituteNanjing 210029China

Based on the open source code OpenFOAM,a three-dimensional model is presented for simulation of the interaction between waves and rubble mound breakwater with armor *** armor units with their real geometries are depicted through computational *** volume-averaged RANS equation and the seepage equation containing nonlinear term are used to describe the percolation in the core and underlayer of the *** independence analysis are carried out,the horizontal and vertical grid size are recommended to take as one-fifteenth of the mean nominal diameter D_(50) of the armor units and one-fifteenth of the wave height *** wave overtopping of rubble mound breakwater with armor units is simulated through the proposed *** results show good agreement between the simulated and measured overtopping discharge rates for different types of armor *** developed numerical model can be used to evaluate the random wave overtopping in design of rubble mound breakwater with artificial armor blocs.

关键词： random wave armor units seepage equation overtopping discharges grid independence

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Dependence of 1.54 μm Photoluminescence on Excess-Si Degrees of Er-Doped Si-Rich SiO_(2) Films Deposited by Magnetron Sputtering

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Chinese Physics Letters 2001年第7期18卷 986-988页

作者： RAN Guang-Zhao CHEN yuan MA Zhen-Chang ZONG Wan-Hua XIE Li-qing GUO Chun-gang QIN Guo-gang Department of Physics Peking UniversityBeijing 100871 National Key Laboratory for ASIC Hebei Semiconductor Research InstituteShijiazhuang 050051 Key Laboratory in University for Radiation Beam Technology and Materials Modification Beijing Normal UniversityBeijing 100875 International Center for Materials Physics Chinese Academy of SciencesShenyang 110015

Room-temperature 1.54-μm photoluminescence(PL)is observed from Er-doped Si-rich SiO_(2)(SiO_(2):Si:Er)films deposited by using the magnetron sputtering *** determine the optimum Si content in the SiO_(2):Si:Er films,the percentage area of the Si target in the composite SiO_(2)-Si-Er target was changed from 0,to 10%,20%and 30%.The percentage area of the Er target was fixed at 1%.It is found that the optimum annealing temperatures for Er3+luminescence intensities are 900°C for the SiO_(2):Er film and 900,800,and 700°C for the SiO_(2):Si:Er films containing 10%,20%and 30%excess-Si(percentage areas of Si target),*** SiO_(2):Si:Er film containing 20%excess-Si and annealed at 800°C has the intensest PL.

关键词： technique. optimum film

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Numerical simulation on directional solidification and heat treatment processes of turbine blades

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China Foundry 2024年第5期21卷 476-490页

作者： Ye-yuan Hu Ju-huai Ma qing-yan Xu School of Materials Science and Engineering Tsinghua UniversityKey Laboratory for Advanced Materials Processing TechnologyMinistry of EducationBeijing 100084China

Study on turbine blades is crucial due to their critical role in ensuring the efficient and reliable operation of aircraft ***-based single crystal superalloys are extensively used in the hot manufacturing of turbine blades due to their exceptional high-temperature mechanical *** hot manufacturing of single crystal blades involves directional solidification and heat *** manufacturing of these blades is time-consuming,capital-intensive,and often insufficient to meet industrial *** simulation techniques have gained widespread acceptance in blade manufacturing research due to their low energy consumption,high efficiency,and rapid turnaround *** article introduces the modeling and simulation of hot manufacturing in single crystal *** discussion outlines the prevalent mathematical models employed in numerical simulations related to blade hot *** encapsulates the advancements in research concerning macro to micro-level numerical simulation techniques for directional solidification and heat treatment ***,potential future trajectories for the numerical simulation of single crystal blade hot manufacturing are also discussed.

关键词： single crystal blades Ni-based superalloy directional solidification heat treatment numerical simulation

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A multi-stage regulation strategy of space manipulators with a free-swinging joint failure

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Chinese Journal of Aeronautics 2021年第5期34卷 573-584页

作者： gang CHEN Yingzhuo FU qingxuan JIA Bonan yuan Dan LIU School of Automation Beijing University of Posts and TelecommunicationsBeijing 100876China

To ensure tasks can be completed after a free-swinging joint failure occurs,a multi-stage regulation strategy of space manipulators is *** all terms of the dynamics equation,an evaluation model of the regulation ability(EMRA)of active joints over the fault joint is established based on the fuzzy *** then a multi-stage regulation strategy based on the EMRA is designed to regulate the fault *** strategy divides the regulation process into several stages,and select a certain active joint to regulative the fault joint in every *** this multi-stage regulation strategy,the fault joint can be regulated to the desired angle without huge torque on regulative *** simulation is carried out with a 7-DOF space manipulator,verifying the correctness and effectiveness of the multi-stage regulation *** strategy has three advantages:Coriolis and centrifugal terms are both considered for the first time in selecting the regulative joint,making the selection result more in line with the actual regulation process;The influence of the model uncertainty is eliminated in establishing the EMRA,making the evaluation of regulative ability more precise;The fault joint is successfully regulated to the desired angle without huge torque on regulative joints.

关键词： Free-swinging joint failure Fuzzy entropy Multi-stage regulation strategy Regulation ability Space manipulator

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The atlas of ferroicity in two-dimensional MGeX_(3) family:Room-temperature ferromagnetic half metals and unexpected ferroelectricity and ferroelasticity

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Nano Research 2021年第12期14卷 4732-4739页

作者： Kuan-Rong Hao Xing-Yu Ma Hou-Yi Lyu Zhen-gang Zhu qing-Bo Yan gang Su School of Physical Sciences University of Chinese Academy of SciencesBeijing100049China School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijing100049China Center of Materials Science and Optoelectronics Engineering College of Materials Science and Optoelectronic TechnologyUniversity of Chinese Academy of SciencesBeijing100049China Kavli Institute for Theoretical Sciences and CAS Center of Excellence in Topological Quantum ComputationUniversity of Chinese Academy of SciencesBeijing100190China

Two-dimensional(2D)ferromagnetic and ferroelectric materials attract unprecedented attention due to the spontaneous-symmetry-breaking induced novel properties and multifarious potential *** we systematically investigate a large family(148)of 2D MGeX3(M=metal elements,X=O/S/Se/Te)by means of the high-throughput first-principles calculations,and focus on their possible ferroic properties including ferromagnetism,ferroelectricity,and *** discover eight stable 2D ferromagnets including five semiconductors and three half-metals,212D antiferromagnets,and 11 stable 2D ferroelectric semiconductors including two multiferroic ***,MnGeSe3 and MnGeTe3 are predicted to be room-temperature 2D ferromagnetic half metals with Tc of 490 and 308 K,*** is probably for the first time that ferroelectricity is uncovered in 2D MGeX3 family,which derives from the spontaneous symmetry breaking induced by unexpected displacements of Ge-Ge atomic pairs,and we also reveal that the electric polarizations are in proportion to the ratio of electronegativity of X and M atoms,and IVB group metal elements are highly favored for 2D *** tunnel junction and water-splitting photocatalyst based on 2D ferroic MGeX3 are proposed as examples of wide potential *** atlas of ferroicity in 2D MGeX3 materials will spur great interest in experimental studies and would lead to diverse applications.

关键词： two-dimensional materials ferroicity ferroelectricity ferroelasticity ferromagnetic half metal

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Observation-Driven Multiple UAV Coordinated Standoff Target Tracking Based on Model Predictive Control

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Tsinghua Science and Technology 2022年第6期27卷 948-963页

作者： Shun Sun Yu Liu Shaojun Guo gang Li Xiaohu yuan Department of Control Science and Technology Naval Aviation UniversityYantai 264001China Department of Electronic Engineering Tsinghua UniversityBeijing 100084China National Institute of Defense Technology Innovation Academy of Military Sciences PLABeijing 100091China Department of Automation Tsinghua UniversityBeijing 100084China

An observation-driven method for coordinated standoff target tracking based on Model Predictive Control(MPC)is proposed to improve observation of multiple Unmanned Aerial Vehicles(UAVs)while approaching or loitering over a *** acquiring a fusion estimate of the target state,each UAV locally measures the observation capability of the entire UAV system with the Fisher Information Matrix(FIM)determinant in the decentralized *** facilitate observation optimization,only the FIM determinant is adopted to derive the performance function and control constraints for coordinated standoff ***,a modified iterative scheme is introduced to improve the iterative efficiency,and a consistent circular direction control is established to maintain long-term observation performance when the UAV approaches its *** experiments with simulated and real trajectories validate that the proposed method can improve observation of the UAV system for target tracking and adaptively optimize UAV trajectories according to sensor performance and UAV-target geometry.

关键词： coordinated tracking standoff tracking observation-driven Model Predictive Control(MPC) multiple UAVs Fisher Information Matrix(FIM)

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Persulfate promoted tandem radical cyclization of ortho-cyanoarylacrylamides with oxamic acids for construction of carbamoyl quinoline-2,4-diones under metal-free conditions

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Chinese Chemical Letters 2021年第11期32卷 3632-3635页

作者： qing-qing Han yuan-yuan Sun Shao-Hui Yang Jing-Cheng Song Zu-Li Wang College of Chemistry and Pharmaceutical Sciences Qingdao Agricultural UniversityQingdao 266109China

An efficient and practical methods for the synthesis of carbamoyl quinoline-2,4-diones via the reaction of ortho-cyanoarylacrylamides with oxamic acids was *** cyclic reaction could be performed efficiently under meta... 详细信息

关键词： Ortho-cyanoarylacrylamides Oxamic acids Quinoline-2.4-diones Meta I-free Persulfates

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Assessing frost hardiness of Pinus bungeana shoots and needles by electrical impedance spectroscopy with and without freezing tests

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Journal of Plant Ecology 2010年第4期3卷 285-293页

作者： gang Zhang Ya-qing Li Sheng-hao Dong College of Horticulture Agricultural University of HebeiBaodingPR China071001

Aims Nursery and forest operations require that frost hardiness results be produced faster than can be provided by controlled freezing *** is a great challenge to develop a rapid method for predicting frost hardiness that might not necessitate controlled freezing *** aim of this study was to examine the assessment of the frost hardiness of shoots and needles of Pinus bungeana by electrical impedance spectroscopy(EIS)with and without controlled exposure to *** The frost hardiness of current-year shoots and needles of *** in an 8-year-old provenance field trial was measured at Shisanlin Nursery in Beijing,China,from September 2006 to January 2007 by means of EIS and conventional electrolyte leakage(EL).In the same plants,but without controlled freezing test,were monitored the EIS parameters in current-year shoots and *** Findings The results showed that(i)after controlled freezing tests,the frost hardiness estimated by EIS parameters(extracellular resistance,re,and membrane time constant,sm)was significantly correlated with the frost hardiness assessed by EL method(r=0.95)and(ii)for the samples not exposed to controlled freezing treatment,the relaxation time s1 for shoots and b for needles had greater correlations with the frost hardiness estimated by EL after controlled freezing tests relative to the other parameters(r=0.90 for shoots and r=0.84 for needles,respectively).The parameters re of shoots and needles and sm of needles might be applied for measuring frost hardiness of samples after exposed to controlled freezing *** frost hardiness results can be obtained within 48 *** parameters s1 of shoots and b of needles could be used for estimating the frost hardiness of samples without using a controlled freezing *** frost hardiness results can be obtained within 24 h.

关键词： cold hardiness electrical impedance spectroscopy electrolyte leakage Pinus bungeana

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Erosion and Corrosion of Mild Steel and Stainless Steel in Sodium Carbonate/Bicarbonate Solution Bearing Alumina Particle

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Journal of Iron and Steel Research International 2004年第4期11卷 52-55页

作者： yuan qing-long LIANG Hong-da Taiyuan University of Technology

With a rotating cylinder electrode apparatus,the polarization behaviors of the mild steel and the stainless steel 0Cr18Ni9 in NaHCO3(0.5M)+Na2CO3(0.5M)solution with and without erodent particles were investigated and *** results show that the rotation speed of cylinder hardly affects the polarization behavior of sample in solution without particles but exerts a great influence on that with *** rotation speed,the free corrosion potential shifts to positive direction and the oxygen limiting current density *** the mild steel and stainless steel 0Cr18Ni9 experience a significant increase of the mass loss by increasing erosion,and erosive wear was dominated by severe *** insufficient mechanical strength of both materials leads to a low resistance to particle *** peripheral velocities of the rotating cylinder enhances the corrosion rate of the mild *** stainless steel 0Cr18Ni9,due to a high erosive wear,also suffers from similar erosion-corrosion damage,despite that its corrosion resistance is much higher than that of the mild steel.

关键词： steel erosion corrosion polarization behavior rotation speed

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