检索结果-南通市图书馆

Driving force planning in shield tunneling based on Markov decision processes

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2012年第4期55卷 1022-1030页

作者： HU XiangTao HUANG YongAn YIN ZhouPing XIONG YouLun state key laboratory of digital manufacturing equipment&technology Huazhong University of Science&TechnologyWuhan 430074China

In shield tunneling, the control system needs very reliable capability of deviation rectifying in order to ensure that the tunnel trajectory meets the permissible criterion. To this goal, we present an approach that adopts Markov decision process (MDP) theory to plan the driving force with explicit representation of the uncertainty during excavation. The shield attitudes of possi- ble world and driving forces during excavation are scattered as a state set and an action set, respectively. In particular, an evaluation function is proposed with consideration of the stability of driving force and the deviation of shield attitude. Unlike the deterministic approach, the driving forces based on MDP model lead to an uncertain effect and the attitude is known only with an imprecise probability. We consider the case that the transition probability varies in a given domain estimated by field data, and discuss the optimal policy based on the interval arithmetic. The validity of the approach is discussed by comparing the driving force planning with the actual operating data from the field records of Line 9 in Tianjin. It is proved that the MDP model is reasonable enough to predict the driving force for automatic deviation rectifying.

关键词： shield tunneling Markov decision process automatic deviation rectifying interval arithmetic driving force planning

Integration of Electrical Properties and Polarization Loss Modulation on Atomic Fe–N‑RGO for Boosting Electromagnetic Wave Absorption

在线全文

学校读者我要写书评

暂无评论

Nano-Micro Letters 2025年第2期17卷 517-532页

作者： Kaili Zhang Yuefeng Yan Zhen Wang Guansheng Ma Dechang Jia Xiaoxiao Huang Yu Zhou state key laboratory of Precision Welding&Joining of Materials and Structures Harbin Institute of TechnologyHarbin 150001People’s Republic of China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001People’s Republic of China MIIT key laboratory of Advanced Structural‑Functional Integration Materials&Green manufacturing technology Harbin Institute of TechnologyHarbin 150001People’s Republic of China

Developing effective strategies to regulate graphene’s conduction loss and polarization has become a key to expanding its application in the electromagnetic wave absorption(EMWA)*** on the unique energy band structure of graphene,regulating its bandgap and electrical properties by introducing heteroatoms is considered a feasible ***,metal-nitrogen doping reduced graphene oxide(M–N-RGO)was prepared by embedding a series of single metal atoms M–N_(4) sites(M=Mn,Fe,Co,Ni,Cu,Zn,Nb,Cd,and Sn)in RGO using an N-coordination atom-assisted *** composites had adjustable conductivity and polarization to optimize dielectric loss and impedance matching for efficient EMWA *** results showed that the minimum reflection loss(RL_(min))of Fe–N-RGO reaches−74.05 dB(2.0 mm)and the maximum effective absorption bandwidth(EAB_(max))is 7.05 GHz(1.89 mm)even with a low filler loading of only 1 wt%.Combined with X-ray absorption spectra(XAFS),atomic force microscopy,and density functional theory calculation analysis,the Fe–N_(4) can be used as the polarization center to increase dipole polarization,interface polarization and defect-induced polarization due to d-p orbital hybridization and structural ***,electron migration within the Fe further leads to conduction loss,thereby synergistically promoting energy *** study demonstrates the effectiveness of metal-nitrogen doping in regulating the graphene′s dielectric properties,which provides an important basis for further investigation of the loss mechanism.

关键词： Electromagnetic wave absorption Fe-N-RGO Dipole polarization Conduction loss Impedance matching

An improved artificial bee colony algorithm for steelmaking–refining–continuous casting scheduling problem

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2018年第8期26卷 1727-1735页

作者： Kunkun Peng Quanke Pan Biao Zhang state key laboratory of digital manufacturing equipment and technology Huazhong University of Science and Technology

Steelmaking–refining–Continuous Casting(SCC) scheduling is a worldwide problem, which is NP-hard. Effective SCC scheduling algorithms can help to enhance productivity, and thus make significant monetary savings. This paper develops an Improved Artificial Bee Colony(IABC) algorithm for the SCC scheduling. In the proposed IABC, charge permutation is employed to represent the solutions. In the population initialization, several solutions with certain quality are produced by a heuristic while others are generated randomly. Two variable neighborhood search neighborhood operators are devised to generate new high-quality solutions for the employed bee and onlooker bee phases, respectively. Meanwhile, in order to enhance the exploitation ability, a control parameter is introduced to conduct the search of onlooker bee phase. Moreover, to enhance the exploration ability,the new generated solutions are accepted with a control acceptance criterion. In the scout bee phase, the solution corresponding to a scout bee is updated by performing three swap operators and three insert operators with equal probability. Computational comparisons against several recent algorithms and a state-of-the-art SCC scheduling algorithm have demonstrated the strength and superiority of the IABC.

关键词： Artificial bee colony Steelmaking–refining–continuous casting Hybrid flowshop scheduling Variable neighborhood search

Interpolation-based contour error estimation and componentbased contouring control for five-axis CNC machine tools

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2018年第11期61卷 1666-1678页

作者： LI XiangFei ZHAO Huan ZHAO Xin DING Han state key laboratory of digital manufacturing equipment and technology Huazhong University of Science and Technology

High accuracy contour error estimation and direct contour error control are two major approaches to reduce the contour ***, two key factors make them complex for five-axis machine tools: the nonlinear kinematics and the coupling between the tool position and orientation. In this study, by finding the reference point nearest to the current actual position, and interpolating the point with two neighboring reference points and using the distance ratio, a new contour error estimation method for five-axis machine tools is proposed, which guarantees high accuracy while depending on only the reference points. By adding a weighted contour error on the tracking error in the workpiece coordinate system, and specifying a desired second-order error dynamics based on the error variable, an effective contouring control method is proposed, which can alleviate the problem: when the contour error components are introduced into the controller, the contour errors increase instead in some regions of the tracking trajectory. A series of experiments are performed on a tilting-rotary-table(TRT) type five-axis machine tool. The results reveal that the proposed estimation method has high accuracy, and compared with the case without contour error control, the proposed control approach can reduce the contour error along the whole trajectory.

关键词： five-axis contour error contouring control interpolation component-based

Bio-inspired untethered fully soft robots in liquid actuated by induced energy gradients

在线全文

学校读者我要写书评

暂无评论

National Science Review 2019年第5期6卷 970-981页

作者： Liang Xiong Lyu Fen Li Kang Wu Pan Deng Seung Hee Jeong Zhigang Wu Han Ding state key laboratory of digital manufacturing equipment and technology Huazhong University of Science and Technology

Soft robotics with new designs, fabrication technologies and control strategies inspired by nature have been totally changing our view on *** fully exploit their potential in practical applications, untethered designs are preferred in ***, hindered by the limited thermal/mechanical performance of soft materials, it has been always challenging for researchers to implement untethered solutions, which generally involve rigid forms of high energy-density power sources or high energy-density processes.A number of insects in nature, such as rove beetles, can gain a burst of kinetic energy from the induced surface-energy gradient on water to return to their familiar habitats, which is generally known as Marangoni *** by such a behavior, we report the agile untethered mobility of a fully soft robot in liquid based on induced energy gradients and also develop corresponding fabrication and maneuvering *** robot can reach a speed of 5.5 body lengths per second, which is 7-fold more than the best reported, 0.69(body length per second), in the previous work on untethered soft robots in liquid by *** controlling the robots, we demonstrate a soft-robot swarm that can approach a target simultaneously to assure a hit with high *** employing any high energy-density power sources or processes, our robot exhibits many attractive merits, such as quietness, no mechanical wear, no thermal fatigue, invisibility and ease of robot fabrication, which may potentially impact many fields in the future.

关键词： fully soft robot untethered induced energy gradients Marangoni propulsion robot swarm

3D Printing of Tough Hydrogel Scaffolds with Functional Surface Structures for Tissue Regeneration

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nano-Micro Letters 2025年第2期17卷 18-45页

作者： Ke Yao Gaoying Hong Ximin Yuan Weicheng Kong Pengcheng Xia Yuanrong Li Yuewei Chen Nian Liu Jing He Jue Shi Zihe Hu Yanyan Zhou Zhijian Xie Yong He state key laboratory of Fluid Power and Mechatronic Systems School of Mechanical EngineeringZhejiang UniversityHangzhou 310027People’s Republic of China Liangzhu laboratory Zhejiang UniversityHangzhou 310027People’s Republic of China key laboratory of 3D Printing Process and equipment of Zhejiang Province College of Mechanical EngineeringZhejiang UniversityHangzhou 310027People’s Republic of China Stomatology Hospital School of StomatologyZhejiang University School of MedicineHangzhou 310027People’s Republic of China state key laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001People’s Republic of China Institute of digital Medicine Nanjing First HospitalNanjing Medical UniversityNanjing 210006People’s Republic of China

Hydrogel scaffolds have numerous potential applications in the tissue engineering ***,tough hydrogel scaffolds implanted in vivo are seldom reported because it is difficult to balance biocompatibility and high mechanical *** by Chinese ramen,we propose a universal fabricating method(printing-P,training-T,cross-linking-C,PTC&PCT)for tough hydrogel scaffolds to fill this ***,3D printing fabricates a hydrogel scaffold with desired structures(P).Then,the scaffold could have extraordinarily high mechanical properties and functional surface structure by cycle mechanical training with salting-out assistance(T).Finally,the training results are fixed by photo-cross-linking processing(C).The tough gelatin hydrogel scaffolds exhibit excellent tensile strength of 6.66 MPa(622-fold untreated)and have excellent ***,this scaffold possesses functional surface structures from nanometer to micron to millimeter,which can efficiently induce directional cell ***,this strategy can produce bionic human tissue with mechanical properties of 10 kPa-10 MPa by changing the type of salt,and many hydrogels,such as gelatin and silk,could be improved with PTC or PCT *** experiments show that this scaffold can effectively promote the new generation of muscle fibers,blood vessels,and nerves within 4 weeks,prompting the rapid regeneration of large-volume muscle loss injuries.

关键词： 3D printing Tough hydrogel scaffold Functional surface structure Tissue regeneration Biomaterials

Algebraic test of relative form closure grasps with its implementation

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2014年第7期57卷 1401-1410页

作者： XIONG YouLun XIONG Tao WANG YuHui state key laboratory of digital manufacturing equipment and technology Huazhong University of Science and Technology

This paper presents an approach to algebraic detection of relative form closure for a multi-fingered grasp G and gives an attention to the classification of relative form *** or not a grasp G is of relative form closure has been verified by the geometric criterion 0?rintC[G](Xiong Y L,Xiong X *** structure and geometric interpretation of rigid complex fixture *** Trans Autom Sci Eng,2007,4:252–264;Xiong Y *** of point contact restraint and qualitative analysis of robot *** China Ser A-Math,1994,37:629–640).Our aim is at transferring the geometric criterion into an algebraic formulation by a theorem that a grasp G is relative form closure,if,and only if the origin 0 can be represented as a positive convex combination of *** we develop a constructive procedure called ri-simplex algorithm to find a positive convex combination of G when it has relative form *** closure is considered as a special case of relative form closure,when the grasp G can affinely span the whole space,while partly relative form closure is referred to as form closed relative to a subset G1 of G.

关键词： relative form closure algebraic test PCC(positive convex combination) ri-simplex algorithm simplex grasp complex grasp

Deformation Behavior of Zr_(65)Cu_(17.5)Ni_(10)Al_(7.5)in Superplastic Forming with Silicon Mould: Simulation and Application

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of technology(Materials Science) 2014年第2期29卷 250-255页

作者：杨璠 SHI Tielin YU Qiang 廖广兰 state key laboratory of digital manufacturing equipment and technology Huazhong University of Science and Technology

We investigated the deformation behaviors of Zr_65Cu_17.5Ni_10Al_7.5 in superplastic forming in silicon mould via numerical modeling and experiments. The data needed for the constitutive formulation were obtained from compressive tests to establish a material library for finite-element simulation using a DEFORM 3D software. A constant speed forming process of a micro gear was modeled where the loading force, feature size and amount of deformation in the micro gear in silicon mould were analyzed in detail for the optimal requirements of micro gear forming and the protection of silicon mould. Guided by the modeling parameters, an amorphous metal micro gear was successfully obtained by our home-made superplastic forming system with the optimized parameters （temperature of 683 K, top speed of 0.003 mm/s until the load force reaching limiting value at 1960 N, and a gradually decelerating process for holding the force to the end）. Our work gives a good example for optimization of superplastic forming and fabrication of BMGs in microparts.

关键词： bulk metallic glass deformation finite-element simulation superplastic forming silicon mould

Design of a combined magnetic negative stiffness mechanism with high linearity in a wide working region

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2022年第9期65卷 2127-2142页

作者： WU JiuLin CHE JiXing CHEN XueDong JIANG Wei state key laboratory of digital manufacturing equipment and technology Huazhong University of Science and TechnologyWuhan 430074China

Combining magnetic negative stiffness mechanism(NSM) in parallel with positive stiffness has been considered to be an effective approach to realize the quasi-zero stiffness(QZS) characteristic,thus resolving the contradiction between high load capacity and(ultra-) low-frequency vibration isolation ***,the remarkable stiffness nonlinearity of common magnetic NSMs restricts the displacement region with reliable negative stiffness,resulting in considerable nonlinear behavior,poor vibration attenuation performance,and probable instability under large amplitude vibrations.A novel combined negative stiffness mechanism(CNSM) with attractive magnetic NSM(ANSM) and repulsive magnetic NSM(RNSM) in parallel is proposed in this *** stiffness nonlinearities of the ANSM and RNSM in the CNSM are counteracted through the parallel configuration such that the displacement region with reliable linear stiffness of the CNSM is widened by several *** analytical model of the CNSM is established by the magnetic charge model and verified by simulation on ANSYS *** studies are then conducted to investigate the effects of design parameters on the stiffness characteristic,providing guidelines for the optimal design of the ***,the stiffness and nonlinearity of the CNSM are compared with that of a single ANSM and *** and dynamic experiments are finally conducted on the proposed test *** results demonstrated the validity of the established model and the effectiveness of the CNSM in generating high linear stiffness within a wide displacement region and lowering the resonance ***,the proposed CNSM can be applied in(ultra-) low-frequency vibration isolation under large amplitude excitations.

关键词： vibration isolation quasi-zero stiffness combined negative stiffness mechanism high linearity

同方期刊数据库