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Understanding microstructure-property relationships of HPDC Al-Si alloy based on machine learning and crystal plasticity simulation

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Advances in manufacturing 2024年第3期12卷 497-511页

作者： qiang-qiang Zhai Zhao liu Ping Zhu State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai200240People’s Republic of China National Engineering Research Center of Automotive Power and Intelligent Control Shanghai Jiao Tong UniversityShanghai200240People’s Republic of China School of Design Shanghai Jiao Tong UniversityShanghai200240People’s Republic of China

Al-Si alloys manufactured via high-pressure die casting(HPDC)are suitable for a wide range of ***,the heterogeneous microstructure and unpredictable pore distribution of Al-Si high-pressure die castings result in significant variations in the mechanical properties,thus leading to a complicated microstructure-property relationship that is difficult to ***,a computational framework incorporating machine learning and crystal plasticity method is *** framework aims to provide a systematic and comprehensive understanding of this relationship and enable the rapid prediction of macroscopic mechanical properties based on the ***,we select eight variables that can effectively characterize the microstructural features and then obtain their statistical ***,based on 160 samples obtained via the Latin hypercube sampling method,representative volume elements are constructed,and the crystal plasticity fast Fourier transformation method is executed to obtain the macroscopic mechanical ***,the yield strength,elastic modulus,strength coefficient,and strain-hardening exponent are used to characterize the stress-strain curve,and Gaussian process regression models and microstructural variables are ***,sensitivity and univariate analyses based on these machine-learning models are performed to obtain insights into the microstructure-property relationships of the HPDC Al-Si *** results show that the Gaussian process regression models exhibit high accuracy(R^(2) greater than 0.84),thus confirming the viability of the proposed *** results of sensitivity analysis indicate that the pore size exerts the most significant effect on the mechanical ***,the proposed framework can not only be transferred to other alloys but also be employed for material design.

关键词： High-pressure die casting(HPDC) Machine learning Crystal plasticity Aluminum alloys

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Effect of MgO on Oxidation Process of Fe_3O_4 in Pellets

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Journal of Iron and Steel Research International 2016年第10期23卷 1007-1011页

作者： qiang-jian GAO Yan-song SHEN Xin JIANG Hai-yan ZHENG Feng-man SHEN Chang-sheng liu School of Metallurgy Northeastern University School of Chemical Engineering University of New South Wales

Induration process of oxidized pellets involves the oxidation of Fe3O4 and re-crystallization of *** oxidation process of Fe3O4 is significant for pellets to obtain better ambient ***,the effect of MgO on oxidation process of Fe3O4 was *** unreacted core model was applied to analyze the oxidizing induration process of *** experimental results show that MgO plays a negative role in the oxidation process of *** oxidation rate of Fe3O4 in MgO-fluxed pellets（95.0% Fe3O4 ＋5.0% MgO）is slower than that in standard acid pellets（100% Fe3O4）.The relation between oxidation ratio of Fe3O4 and time was calculated based on the unreacted core model for both MgO-fluxed pellets and standard acid *** to verification experiments,the values calculated by model coincide well with the experimental ***,the unreacted core model could be applied to describe the oxidizing induration process of pellets.

关键词： MgO-fluxed pellet Fe3O4 oxidation unreacted core model

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Modeling and Analytical Solution of Chatter Stability for T-slot Milling

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Chinese Journal of Mechanical Engineering 2010年第1期23卷 88-93页

作者： LI Zhongqun liu qiang School of Mechanical Engineering Hunan University of Technology Zhuzhou 412008 China School of Mechanical Engineering and Automation Beihang University Beijing 100191 China

T-slot milling is one of the most common milling processes in industry. Despite recent advances in machining technology, productivity of T-slot milling is usually limited due to the process limitations such as high cutting forces and stability. If cutting conditions are not selected properly the process may result in the poor surface finish of the workpiece and the potential damage to the machine tool. Currently, the predication of chatter stability and determination of optimal cutting conditions based on the modeling of T-slot milling process is an effective way to improve the material removal rate（MRR） of a T-slot milling operation. Based on the geometrical model of the T-slot cutter, the dynamic cutting force model was presented in which the average directional cutting force coefficients were obtained by means of numerical approach, and leads to an analytical determination of stability lobes diagram（SLD） on the axial depth of cut. A new kind of SLD on the radial depth of cut was also created to satisfy the special requirement of T-slot milling. Thereafter, a dynamic simulation model of T-slot milling was implemented using Matlab software. In order to verify the effectiveness of the approach, the transfer functions of a typical cutting system in a vertical CNC machining center were measured in both feed and normal directions by an instrumented hammer and accelerators. Dynamic simulations were conducted to obtain the predicated SLD under specified cutting conditions with both the proposed model and CutPro~. Meanwhile, a set of cutting trials were conducted to reveal whether the cutting process under specified cutting conditions is stable or not. Both the simulation comparison and experimental verification demonstrated that the satisfactory coincidence between the simulated, the predicted and the experimental results. The chatter-free T-slot milling with higher MRR can be achieved under the cutting conditions determined according to the SLD simulation.

关键词： machining dynamics T-slot milling chatter vibration stability lobes diagram

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Interaction of Cd and citric acid, EDTA in red soil

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Journal of Environmental Sciences 2001年第2期13卷 153-156页

作者： ZHOU Dong mei WANG Shen-qiang CHEN Huai man Laboratory of Material Cycling in Pedosphere Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China

Adsorption and desorption process of cadmium in red soil (Ferrisols) as well as the influence by media' s pH were investigated in detail with and without citric acid and EDTA. Experimental results clearly showed that Cd adsorption in red soil was affected significantly by the coexisted organic chemicals. In the presence of citric acid and EDTA, Cd adsorption in red soil increased with pH in acid media but decreased in high pH one. Further studies placed stress on the adsorbed Cd in red soil which was found to be existed mainly as exchangeable one at pH < 5.5, and desorption rate by 0.10 mol/L NaNO3 gave a peak-shaped curve due to the difference of specifically and nonspecifically adsorbed Cd with pH's change.

关键词： cadmium interaction organic acid red soil

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Global adaptive stabilization for planar nonlinear systems with unknown input powers

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Science China(Information Sciences) 2021年第9期64卷 261-263页

作者： Yongchao man Yungang liu School of Control Science and Engineering Shandong University

Dear editor,Despite the development of extensive strategies [1,2], adaptive control still requires thorough investigations to improve its capability and cover more uncertain systems. This study aims to demonstrate the powerful ability of adaptive control in compensating multiple serious uncertainties, particularly those in input powers,

关键词： Nonlinear systems multiple serious uncertainties unknown input powers adaptive control global stabilization

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A Pincer Cobalt Complex as Catalyst with Dual Hydrogenation Activities for Hydrodeoxygenation of Ketones with H2

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Chinese Journal of Chemistry 2023年第24期41卷 3528-3532页

作者： Bingxue liu qiang liu Center of Basic Molecular Science (CBMS) Department of ChemistryTsinghua UniversityBeijing100084 China

Reductive deoxygenation of ketones using H_(2) is a highly desirable but also challenging transformation in both chemical synthesis,industrial-scale petroleum and biomass feedstock reforming ***,we report a cooperative cobalt/Lewis acid (LA)-catalyzed hydrodeoxygenation of ketones using H_(2) as the *** particular,the newly developed pincer cobalt catalyst possesses dual hydrogenation activities for both ketones and alkenes under the same reaction *** reaction features a broad substrate scope,excellent functional-group compatibility,and potential applicability.

关键词： Cobalt catalyst Lewis acids Homogeneous catalysis Dual hydrogenation activities Hydrodeoxygenation Ketones

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High Accurate Interpolation of NURBS Tool Path for CNC Machine Tools

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Chinese Journal of Mechanical Engineering 2016年第5期29卷 911-920页

作者： liu qiang liu Huan YUAN Songmei School of Mechanical Engineering and Automation Beihang University

Feedrate fluctuation caused by approximation errors of interpolation methods has great effects on machining quality in NURBS interpolation, but few methods can efficiently eliminate or reduce it to a satisfying level without sacrificing the computing efficiency at present. In order to solve this problem, a high accurate interpolation method for NURBS tool path is proposed. The proposed method can efficiently reduce the feedrate fluctuation by forming a quartic equation with respect to the curve parameter increment, which can be efficiently solved by analytic methods in real-time. Theoretically, the proposed method can totally eliminate the feedrate fluctuation for any 2nd degree NURBS curves and can interpolate 3rd degree NURBS curves with minimal feedrate fluctuation. Moreover, a smooth feedrate planning algorithm is also proposed to generate smooth tool motion with considering multiple constraints and scheduling errors by an efficient planning strategy. Experiments are conducted to verify the feasibility and applicability of the proposed method. This research presents a novel NURBS interpolation method with not only high accuracy but also satisfying computing efficiency.

关键词： NURBS interpolation feedrate machine tool CNC

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Non-contact and full-field online monitoring of curing temperature during the in-situ heating process based on deep learning

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Advances in manufacturing 2024年第1期12卷 167-176页

作者： qiang-qiang liu Shu-Ting liu Ying-Guang Li Xu liu Xiao-Zhong Hao College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing210016People’s Republic of China School of Mechanical and Power Engineering Nanjing Tech UniversityNanjing211816People’s Republic of China

Online monitoring of the curing temperature field is essential to improving the quality and efficiency of the manufacturing process of composite *** embedded sensor-based technologies have difficulty monitoring the full temperature field or have to introduce heterogeneous items that could have an undesired impact on the *** this paper,a non-contact,full-field monitoring method based on deep learning that predicts the internal temperature field of composite parts in real time using surface temperature measurements of auxiliary materials is *** the proposed method,an average temperature monitoring accuracy of 97%is achieved in various heating *** addition,this method also demonstrates satisfying feasibility when a stronger thermal barrier covers the *** method was experimentally validated during the self-resistance electric heating process,in which the monitoring accuracy reached 93.1%.This method can potentially be applied to automated manufacturing and process control in the composites industry.

关键词： Online monitoring Curing temperature field Deep learning(DL) In-situ heating

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Flow Field Investigation in a Trapezoidal Duct with Swirl Flow Induced by Impingement Jets

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Chinese Journal of Aeronautics 2011年第1期24卷 8-17页

作者： liu Haiyong qiang Hongfu liu Songling liu Cunliang 201 Section Xi 'an High- Teeh Institute Xi 'an 710025 China School of Power and Energy Northwestern Polytechnieal University Xi 'an 710072 China

An enlarged model of trapezoidal duct near the leading-edge in the blade is built up. The effects of impingement jets, swirl flow, cross flow and effusion flow are considered. Experiments are performed to measure flow fields in this confined passage and exit holes on one of its side walls. Cross flow and effusion flow are induced in the channel by the outflow of side exit hole （SEH） and film cooling hole （FCH）, which are oriented on one end wall and bottom wall of the passage. Detailed flow structures are measured for two impingement angles of 35° and 45° with 6 combinations of outflow ratios. Results show that the small jets impinge the target wall effectively while the large jets contribute to inducing and impelling a strong counter-clockwise vortex in the upper part of the passage. Cross flow plays a dominate role for the flow structures in the passage and exit holes. It deflects jets, enhances swirl and deteriorates side exit conditions. Impingement angle is another significant factor for the flow characteristics. Its effect reveals more evidently with cross flow. Within the present test conditions, the mass flow rates and outflow positions of FCHs have no distinct effect on the main flow structures.

关键词： flow fields leading edge impingement jets swirl flow film cooling cross flow

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Bootstrap Approximation of Wavelet Estimates in a Semiparametric Regression Model

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Acta Mathematica Sinica,English Series 2010年第4期26卷 763-778页

作者： liu Gen XUE qiang liu College of Applied Sciences Beijing University of Technology Beijing 100124 P. R. China School of Statistics Capital University of Economics and Business Beijing 100070 P. R. China

The inference for the parameters in a semiparametric regression model is studied by using the wavelet and the bootstrap methods. The bootstrap statistics are constructed by using Efron＇s resampling technique, and the strong uniform convergence of the bootstrap approximation is proved. Our results can be used to construct the large sample confidence intervals for the parameters of interest. A simulation study is conducted to evaluate the finite-sample performance of the bootstrap method and to compare it with the normal approximation-based method.

关键词： bootstrap approximation confidence interval semiparametric regression model strong uniform convergence wavelet estimate

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