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A data-driven rolling optimization method for trajectory tracking error prediction of CNC machine tools

Science China Technological Sciences 2025年第1期 274-289页

作者： Yinxin GUAN Jixiang YANG shizhong tan Han DING School of Mechanical Science and Engineering State Key Laboratory of Intelligent Manufacturing Equipment and TechnologyHuazhong University of Science and Technology

The dynamic performance of the feed-drive system in CNC machine tools directly influences the accuracy of machined parts. To enhance the motion control performance of CNC machine tools, a high-precision model of the feed-drive system is critical. However, current modeling methods for feed-drive systems seldom consider time-varying factors such as loads, wear, and lubrication. As a result, the model accuracy degrades when the system characteristics are affected by these time-varying factors. In this paper, a rolling optimization method with partial weights frozen is developed to realize quick iterative learning of a data-driven model for a feed drive system with time-varying characteristics using a small amount of ***, the long short-term memory fully connected(LSTM-FC) network is built and divided into feature extraction and output fitting parts based on their functions. Then, a weight freezing-based rolling optimization method is applied. The weights in the feature extraction part are frozen, which preserves the learned common knowledge and patterns by solidifying the way that high-dimensional features are extracted from the input. By adjusting the weights in the output fitting part, the extracted highdimensional features are remapped to the new data distribution changed by time-varying factors. Finally, the performance of the developed rolling optimization method is confirmed by experiments. The results show that the proposed rolling optimization method reduces the maximum prediction errors by 49.5% and the total training time by 96.3% compared with existing methods,which demonstrates that the proposed method can restore model accuracy when the system characteristics change due to timevarying factors, and significantly accelerate the optimization process by rolling optimization.

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A data-driven rolling optimization method for trajectory tracking error prediction of CNC machine tools

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Science China Technological Sciences 2024年

The dynamic performance of the feed-drive system in CNC machine tools directly influences the accuracy of machined parts. To enhance the motion control performance of CNC machine tools, a high-precision model of the feed-drive system is critical. However, current modeling methods for feed-drive systems seldom consider time-varying factors such as loads, wear, and lubrication. As a result, the model accuracy degrades when the system characteristics are affected by these time-varying factors. In this paper, a rolling optimization method with partial weights frozen is developed to realize quick iterative learning of a data-driven model for a feed drive system with time-varying characteristics using a small amount of ***, the long short-term memory fully connected (LSTM-FC) network is built and divided into feature extraction and output fitting parts based on their functions. Then, a weight freezing-based rolling optimization method is applied. The weights in the feature extraction part are frozen, which preserves the learned common knowledge and patterns by solidifying the way that high-dimensional features are extracted from the input. By adjusting the weights in the output fitting part, the extracted highdimensional features are remapped to the new data distribution changed by time-varying factors. Finally, the performance of the developed rolling optimization method is confirmed by experiments. The results show that the proposed rolling optimization method reduces the maximum prediction errors by 49.5%and the total training time by 96.3%compared with existing methods,which demonstrates that the proposed method can restore model accuracy when the system characteristics change due to timevarying factors, and significantly accelerate the optimization process by rolling optimization.

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On the Undeveloped Capitalism of the Developing Countries

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World Economy & China 1994年第1期2卷 18-22页

作者： $$$$( the Institute for West Asia and Africa of CASS.)tan shizhong

ＯｎｔｈｅＵｎｄｅｖｅｌｏｐｅｄＣａｐｉｔａｌｉｓｍｏｆｔｈｅＤｅｖｅｌｏｐｉｎｇＣｏｕｎｔｒｉｅｓ￥（ＴｈｅａｕｔｈｏｒｉｓａｒｅｓｅａｒｃｈｆｅｌｌｏｗｏｆｔｈｅＩｎｓｔｉｔｕｔｅｆｏｒＷｅｓｔＡｓｉａａｎｄＡｆ... 详细信息

ＯｎｔｈｅＵｎｄｅｖｅｌｏｐｅｄＣａｐｉｔａｌｉｓｍｏｆｔｈｅＤｅｖｅｌｏｐｉｎｇＣｏｕｎｔｒｉｅｓ￥（ＴｈｅａｕｔｈｏｒｉｓａｒｅｓｅａｒｃｈｆｅｌｌｏｗｏｆｔｈｅＩｎｓｔｉｔｕｔｅｆｏｒＷｅｓｔＡｓｉａａｎｄＡｆｒｉｃａｏｆＣＡＳＳ．）ＴａｎＳｈ...

关键词： On the Undeveloped Capitalism of the Developing Countries

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DRAM:A DRL-based resource allocation scheme for MAR in MEC

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Digital Communications and Networks 2023年第3期9卷 723-733页

作者： Tongyu Song Xuebin tan Jing Ren Wenyu Hu Sheng Wang shizhong Xu Xiong Wang Gang Sun Hongfang Yu School of Information and Communication Engineering University of Electronic Science and Technology of ChinaChengduPR China

Mobile Edge Computing(MEC)and 5G technology allow clients to access computing resources at the network frontier,which paves the way for applying Mobile Augmented Reality(MAR)*** the MEC paradigm,MAR clients can offload complex tasks to the MEC server and enhance the human perception of the world by merging the received virtual information with the real ***,the resource allocation problem arises as a critical challenge in circumstances where several MAR clients compete for limited resources at the network *** this paper,we aim to design an online resource allocation scheme on the MEC server that takes both high quality of experience and good fairness performance for MAR clients into *** first formulate this problem as a Markov decision process and tackle the challenge of applying the deep reinforcement learning ***,we propose DRAM,a Deep reinforcement learning-based Resource allocation scheme for mobile Augmented reality service in *** also propose a self-adaptive algorithm on the MAR client that is derived based on the analysis of the MAR service to tackle client adaptation *** simulation results demonstrated that DRAM can provide high quality of experience and simultaneously achieve good fairness performance by coordinating with clients’adaptation algorithms.

关键词： Mobile edge computing Mobile augmented reality Deep reinforcement learning Resource allocation

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Kernel selection with spectral perturbation stability of kernel matrix

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Science China(Information Sciences) 2014年第11期57卷 47-56页

作者： LIU Yong LIAO shizhong School of Computer Science and Technology Tianjin University

Kernel selection is one of the key issues both in recent research and application of kernel *** is usually done by minimizing either an estimate of generalization error or some other related performance measure. Use of notions of stability to estimate the generalization error has attracted much attention in recent years. Unfortunately, the existing notions of stability, proposed to derive the theoretical generalization error bounds, are difficult to be used for kernel selection in practice. It is well known that the kernel matrix contains most of the information needed by kernel methods, and the eigenvalues play an important role in the kernel matrix. Therefore, we aim at introducing a new notion of stability, called the spectral perturbation stability,to study the kernel selection problem. This proposed stability quantifies the spectral perturbation of the kernel matrix with respect to the changes in the training set. We establish the connection between the spectral perturbation stability and the generalization error. By minimizing the derived generalization error bound, we propose a new kernel selection criterion that can guarantee good generalization properties. In our criterion,the perturbation of the eigenvalues of the kernel matrix is efficiently computed by solving the derivative of a newly defined generalized kernel matrix. Both theoretical analysis and experimental results demonstrate that our criterion is sound and effective.

关键词： kernel methods kernel selection stability spectral perturbation stability generalization error bound

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Three kinds of extraneous factors in Dixon resultants

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Science China Mathematics 2009年第1期52卷 160-172页

作者： ZHAO shizhong FU HongGuang Shanghai Key Laboratory of Trustworthy Computing East China Normal UniversityShanghai 200062China School of Computer Science and Engineering University of Electronic Science and Technology of ChinaChengdu 610054China Chengdu Institute of Computer Applications Chinese Academy of SciencesChengdu 610041China

Dixon resultant is a basic elimination method which has been used widely in the high technology fields of automatic control, robotics, etc. But how to remove extraneous factors in Dixon resultants has been a very difficult problem. In this paper, we discover some extraneous factors by expressing the Dixon resultant in a linear combination of original polynomial system. Furthermore, it has been proved that the factors mentioned above include three parts which come from Dixon derived polynomials, Dixon matrix and the resulting resultant expression by substituting Dixon derived polynomials respectively.

关键词： Dixon resultant Dixon matrix extraneous factors 00A06 13A50 13P99 68W30

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First-principles study on the mechanical and thermodynamic properties of MoNbTaTiW

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International Journal of Minerals,Metallurgy and Materials 2020年第10期27卷 1398-1404页

作者： Uttam Bhandari Congyan Zhang Shengmin Guo shizhong Yang Department of Computer Science Southern University and Agricultural&Mechanical CollegeBaton RougeLouisiana 70813USA Department of Mechanical and Industrial Engineering Louisiana State UniversityBaton RougeLouisiana 70803USA

Refractory high-entropy alloys(RHEAs)are emerging as new materials for high temperature structural applications because of their stable mechanical and thermal properties at temperatures higher than 2273 *** this study,the mechanical properties of MoNbTaTiW RHEA are examined by applying calculations based on first-principles density functional theory(DFT)and using a large unit cell with 100 randomized *** phase calculation of MoNbTaTiW with CALPHAD method shows the existence of a stable body-centered cubic structure at a high temperature and a hexagonal closely packed phase at a low *** predicted phase,shear modulus,Young’s modulus,Poisson’s ratio,and hardness values are consistent with available experimental *** linear thermal expansion coefficient,vibrational entropy,and vibrational heat capacity of MoNbTaTiW RHEA are investigated in accordance with Debye-Grüneisen *** results may provide a basis for future research related to the application of RHEAs.

关键词： high-entropy alloy MoNbTaTiW mechanical properties thermodynamic properties density functional theory

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Establishment and verification of a model for the movement of pulverized sweet sorghum stalks in a rotary drum bioreactor by discrete element method

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Particuology 2020年第4期18卷 53-63页

作者： Xiangwen Guan Zhixing Zhou Jihong Li shizhong Li Institute of New Energy Technology Tsinghua UniversityBeijing 100084China Beijing Engineering Research Center for Biofuels Institute of New Energy TechnologyTsinghua UniversityBeijing 100084China

The mixing of raw materials in a rotary drum bioreactor is important for advanced solid-state fermentation ***,the shape,size,and other properties of pulverized sweet sorghum stalk particles are more complicated than those of the spherical *** this study,a soft rod-shaped discrete particle model was established and verified to simulate the mixing behavior of sweet sorghum stalk particles in a rotary drum *** were inspired by the particle shape and established a rod-shaped particle model by investigating the influence of the shape(length-diameter ratio)and size(diameter)on the particle packing(stack height and bed porosity).We used orthogonal simulations and extremum difference analysis to determine the main factors,optimum level,and groups of other *** on calibrated parameters,twelve sets of simulations of radial mixing in the drum were performed,and the results were compared with experiments conducted under identical operating *** average relative error between the simulation and the experiment was 10.95%,which indicates that they agreed well and that the simulation could predict the mixing process well.

关键词： Sweet sorghum particles Radial mixing Discrete element method Rotary drum bioreactor Parameter determination

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Removal of Pollutants of Landfill Leachate by Recirculation

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Journal of Wuhan University of Technology(Materials Science) 2008年第2期23卷 281-284页

作者： LI Ye WANG Lina ZHENG shizhong School of Resources and Environmental Engineering Wuhan University of Technology Wuhan 430070 China The Landfill of Hongmiaoling in Fuzhou City

SAfter leached from municipal solid waste landfill was treated by recirculation, the concentration of pollutants decreases greatly, and the moisture content of the solid waste in landfill site was increased and waste stabilization rate was accelerated. Compared with traditional treatment methods, this method offers more important practical values, including short investment, enhanced treatment efficiency and facilitated operation and management. The experimental results indicated that a 99.9% removal of ammonia nitrogen and an 80.5% removal of COD were obtained, when hydraulic power surface load is 15.92 L/m^2·d, and organic surface load is 25.54 g/m^2·d.

关键词： heteropolyoxometalates molybdotungstosilicic acid cetyltrimethylammonium bromide IR spectral and thermal study

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Living and enantiomer-selective polymerization of allene initiated by Ni complex containing chiral phosphine

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Chinese Chemical Letters 2019年第1期30卷 153-156页

作者： Hai Zhu shizhong Luo Zongquan Wu College of Chemistry and Materials Science The Key Laboratory of Functional Molecular Solids Ministry of Education Anhui Laboratory of Molecular-Based Materials Center for Nano Science and Technology Anhui Normal University Department of Polymer Science and Engineering School of Chemistry and Chemical Engineering Hefei University of Technology and Anhui Key Laboratory of Advanced Catalytic Materials and Reaction Engineering

A new allylnickel(II) complex([S(R)]-N-[(1 S)-2-(diphenylphosphino)-1-phenylethyl]-2-methyl-2-propanesulfinamide)(2,2,2-trifluoroacetato-k O)(p-allyl)nickel(2) was designed and prepared by using chiral phosphine. 2 was revealed to efficiently initiate the polymerization of L-and D-N-(1-(dodecylamino)-1-oxopropan-2-yl)-4-(propa-1,2-dien-1-yloxy)-benzamide(L-1 and D-1) in a living/controlled chain growth manner. Polymerization kinetics of L-1 and D-1 indicated that L-1 preferentially polymerized over the antipode D-1 by a factor of 1.9. In block copolymerization of rac-1 using the poly-L-150 as the macroinitiator, the polymerization proceeded in enantiomer-selective manner. It was found that enantiomeric excess(ee) value of the recovered monomer increased with the monomer conversion and finally reached to the maximum of 34%. These results suggest this chiral phosphine complex exhibits enantiomer-selectivity for the polymerization of chiral allene derivative monomer.

关键词： Chiral allene Helical polymer Chiral phosphine ligand Allylnickel(Ⅱ)complex catalyst Enantiomer-selective polymerization

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