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LMAdam:Enhancing Adam via Linear Multistep Discretization 认领 引用
1
作者 Liangming Chen Longbang Wang +1 位作者 Long Jin Jun Wang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2026年第1期161-169,共9页
In this paper,we propose a learning algorithm termed linear multistep adaptive moment(LMAdam) to enhance the adaptive moment(Adam) algorithm for machine learning.Considering Adam as a single-step discretization of its... In this paper,we propose a learning algorithm termed linear multistep adaptive moment(LMAdam) to enhance the adaptive moment(Adam) algorithm for machine learning.Considering Adam as a single-step discretization of its continuous counterpart,we develop the LMAdam algorithm based on a linear multistep discretization scheme.We design a feedforward neural network for learning the coefficients of the multistep terms with ensured consistency and select the coefficients to ensure zero stability of the multistep terms.We experimentally demonstrate the superiority of the LMAdam via extensive experimentation on benchmark datasets for training various deep neural networks in three applications. 展开更多
关键词 Adaptive moment(Adam)algorithm continuous dynamic deep learning multistep discretization
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Discretization and assembly connection technology of cement concrete pavement structure: A review 认领 引用 被引量：5
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作者 Mingjing Fang Longjie Xiang +3 位作者 Yao Wang Shaojie Li Hanhui Wang Hua Xie 《Journal of Road Engineering》 EI CAS 2025年第3期378-393,共16页
Precast concrete pavements(PCPs)represent an innovative solution in the construction industry,addressing the need for rapid,intelligent,and low-carbon pavement technologies that significantly reduce construction time ... Precast concrete pavements(PCPs)represent an innovative solution in the construction industry,addressing the need for rapid,intelligent,and low-carbon pavement technologies that significantly reduce construction time and environmental impact.However,the integration of prefabricated technology in pavement surface and base layers lacks systematic classification and understanding.This paper aims to fill this gap by introducing a detailed analysis of discretization and assembly connection technology for cement concrete pavement(CCP)structures.Through a comprehensive review of domestic and international literature,the study classifies prefabricated pavement technology based on discrete assembly structural layers and presents specific conclusions(i)surface layer discrete units are categorized into bottom plates,top plates,plate-rod separated assemblies,and prestressed connections,with optimal material compositions identified to enhance mechanical properties;(ii)base layer discrete units include block-type,plate-type,and beam-type elements,highlighting their contributions to sustainability by incorporating recycled materials(iii)planar assembly connection types are assessed,ranking them by load transfer efficiency,with specific dimensions provided for optimal performance;and(iv)vertical assembly connections are defined by their leveling and sealing layers,suitable for both new constructions and repairs of existing roads.The insights gained from this review not only clarify the distinctions between various structural layers but also provide practical guidelines for enhancing the design and implementation of PCP.This work contributes to advancing sustainable and resilient road construction practices,making it a significant reference for researchers and practitioners in the field. 展开更多
关键词 Cement concrete pavement Precast concrete pavement Pavement discretization Discrete unit Assembly and connection
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Isogeometric Collocation Method for Random Field Discretization Based on Adaptive Moment Abscissae 认领 引用
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作者 Zhenyu Liu Deshang Peng +3 位作者 Minglong Yang Jin Cheng Chan Qiu Jianrong Tan 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2025年第6期272-286,共15页
The discretization of random fields is the first and most important step in the stochastic analysis of engineering structures with spatially dependent random parameters.The essential step of discretization is solving ... The discretization of random fields is the first and most important step in the stochastic analysis of engineering structures with spatially dependent random parameters.The essential step of discretization is solving the Fredholm integral equation to obtain the eigenvalues and eigenfunctions of the covariance functions of the random fields.The collocation method,which has fewer integral operations,is more efficient in accomplishing the task than the timeconsuming Galerkin method,and it is more suitable for engineering applications with complex geometries and a large number of elements.With the help of isogeometric analysis that preserves accurate geometry in analysis,the isogeometric collocation method can efficiently achieve the results with sufficient accuracy.An adaptive moment abscissa is proposed to calculate the coordinates of the collocation points to further improve the accuracy of the collocation method.The adaptive moment abscissae led to more accurate results than the classical Greville abscissae when using the moment parameter optimized with intelligent algorithms.Numerical and engineering examples illustrate the advantages of the proposed isogeometric collocation method based on the adaptive moment abscissae over existing methods in terms of accuracy and efficiency. 展开更多
关键词 Random Random discretization Isogeometric collocation method Isogeometric Galerkin method Greville abscissae Adaptive moment abscissae
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Thermal damage and permeability evolution in granite subjected to rapid heating and cooling : Experimental and numerical insights 认领 引用 被引量：1
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作者 CHEN Yong-jun YIN Tu-bing +4 位作者 RANJITH P G LI Xi-bing YIN Zhi-qiang SUN Dao-yuan LI Hong-ru 《Journal of Central South University》 SCIE EI CAS CSCD 2026年第3期1203-1241,共39页
As clean energy technologies advance,the engineering challenges caused by rapid thermal fluctuations are expected to become more complex.This study investigates the damage behavior of granite subjected to rapid heatin... As clean energy technologies advance,the engineering challenges caused by rapid thermal fluctuations are expected to become more complex.This study investigates the damage behavior of granite subjected to rapid heating and cooling,focusing on the underlying damage evolution processes.A range of experimental and computational methods,including nuclear magnetic resonance(NMR),synchronous thermal analyzer(STA),and discrete element method(DEM),were used.The results show that as temperature increases,material density,P-wave velocity,and dynamic elastic modulus decline exponentially,while the damage index and linear thermal expansion coefficient increase.Thermal damage primarily results from dehydration,thermal expansion,decarbonation,plasticization,phase changes,cracking,and decomposition.Thermal shock decreases the contribution of micropores to total porosity,while macropores grow above 200℃.The study also improves the Schlumberger-Doll-Research(SDR)and Timur-Coates models,enhancing the accuracy of permeability predictions under different cooling conditions.High temperatures slightly reduce the fractal dimension of the pore structure,which negatively correlates with permeability.As temperature rises,pore coalescence and crack propagation increase,significantly altering permeability.DEM simulations show that cracks are mainly influenced by tensile stresses and thermal expansion and contraction stresses.Higher heating temperatures cause more extensive cracks,while crack contributions decrease during cooling at 600℃.Thermal damage creates additional energy release paths,increasing local thermal resistance and hindering heat transfer.Finally,thermal cycling results in a more directional crack distribution and a notable decrease in contact angles at 600℃,indicating microstructure rearrangement. 展开更多
关键词 granite rapid heating and cooling nuclear magnetic resonance damage evolution pore characteristics discrete element method
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Influence of bedding and prefabricated fissure angles on cement-bonded sand 3 D-printed Brazilian discs:Experimental investigations and PFC modelling 认领 引用 被引量：1
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作者 SUN Yi-qing XIA Shi-fa +3 位作者 HUANG Wei YANG Wei-cai GAN Lei ZHANG Wen-bing 《Journal of Central South University》 SCIE EI CAS CSCD 2026年第3期1371-1386,共16页
Bedding structures significantly influence rock mass deformation and failure,challenging engineering stability.This study aimed to investigate the fracture mechanisms of layered rock masses by examining the effects of... Bedding structures significantly influence rock mass deformation and failure,challenging engineering stability.This study aimed to investigate the fracture mechanisms of layered rock masses by examining the effects of bedding and prefabricated fissure inclination angles on the mechanical behavior of layered Brazilian disc specimens.Layered rock-like Brazilian disc specimens were prepared by combining sand 3 D printing technology with cement slurry as a bonding agent,enabling precise control of bedding features.Uniaxial compression tests,with a loading rate of 0.3 mm/min,coupled with digital image correlation(DIC)technology,were conducted to capture load−displacement curves and crack propagation processes,with two schemes designed to explore varying prefabricated fissure inclination angles(α)and bedding inclination angles(β).Additionally,the discrete element method(DEM)using particle flow code(PFC)with parallel bond(PB)and smooth-joint(SJ)models was employed for numerical simulation,with mesoscopic parameters calibrated against experimental data.The results showed that both α and β significantly affected crack propagation and failure modes:Increasing α led to a gradual increase in peak strength,with cracks initiating from fissure tips and propagating toward loading points;Increasing β caused the failure mode to transition from vertical splitting to bedding-controlled fracture,with peak strength first decreasing,and then increasing.PFC simulations effectively reproduced experimental load−displacement curves and crack morphologies,confirming numerical reliability.This study demonstrates that sand 3 D printing with cement bonding is viable for fabricating layered rock-like specimens,and the combined experimental and numerical results provide insights into layered rock fracture mechanisms,offering references for understanding bedding and prefabricated fissure influences on rock mechanical behavior. 展开更多
关键词 bedded rock masses sand 3 D printing cement slurry bonding Brazilian disc test PFC discrete element simulation
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Coupled FEM-DEM modeling of permeability evolution in rough fractured shale during shearing under varying confining pressures 认领 引用 被引量：2
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作者 Bin Li Qi Li 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2026年第3期1736-1754,共19页
The dynamic evolution of fracture permeability presents a critical scientific challenge in rock masses.Understanding the mechanisms of rock mass permeability evolution is vital for engineering project design and opera... The dynamic evolution of fracture permeability presents a critical scientific challenge in rock masses.Understanding the mechanisms of rock mass permeability evolution is vital for engineering project design and operations.By integrating the discrete element method(DEM)with the finite element method(FEM),a numerical simulation framework for shear seepage in rough fractured shale has been developed to investigate the dynamic mechanisms of permeability evolution under varying confining pressures and during the shearing process.Numerical simulations were conducted on rough fractured samples under effective confining pressures ranging from 5 MPa to 20 MPa to monitor the aperture and permeability evolution of the fracture.The results of the numerical simulation are consistent with the experimental observations,indicating that both the shearing process and confining pressure significantly influence permeability.Moreover,the magnitude of the confining pressure is a crucial factor influencing the trend in permeability changes.Under a confining pressure of 5 MPa,fracture permeability initially increases significantly but decreases post-shearing.In contrast,a continuous decrease in fracture permeability is observed when the confining pressure exceeds 10 MPa.The results of the shear numerical simulation indicate that the confining pressure restricts fracture dilation during shearing,promotes the generation of rock debris,and decreases both the permeability and transmissivity of the fracture.The wear results obtained from numerical simulations are consistent with the experimental patterns and correlate with the joint roughness coefficient(JRC).This study proposed an effective numerical simulation method to reveal the evolution mechanism of fracture flow capacity,taking into account the wear of the fracture surface in shear simulations and the initial stress state of the rock in seepage simulations.This research explains the permeability evolution mechanism of fractured shale from a microscopic perspective,and the proposed numerical simulation method for shear seepage provides a powerful means to uncover the dynamic evolution mechanisms governing fracture permeability. 展开更多
关键词 Discrete element method(DEM) Finite element method(FEM) Fracture Permeability Shear stress Joint roughness coefficient(JRC) Dynamic evolution
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Fixed points as regulatory hubs in discrete memristive neural networks:An analysis of the FitzHugh–Nagumo model 认领 引用
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作者 Shaobo He Jiawei Xiao +1 位作者 Qilai Chen Huihai Wang 《Chinese Physics B》 SCIE EI CAS CSCD 2026年第6期207-226,共20页
This study investigates the dynamics of discrete memristive FitzHugh–Nagumo(FHN)neural networks.We introduce a discrete memristor with hyperbolic tangent nonlinearity and incorporate it into neuron models ranging fro... This study investigates the dynamics of discrete memristive FitzHugh–Nagumo(FHN)neural networks.We introduce a discrete memristor with hyperbolic tangent nonlinearity and incorporate it into neuron models ranging from single neurons and coupled pairs to complex networks with ring and small-world topologies.Stability and bifurcation analyses reveal transitions from periodic to chaotic dynamics.A key contribution is the identification of a constant fixed point that remains invariant across periodic,weakly chaotic,and chaotic regimes.Linear stability analysis of this fixed point provides a fundamental basis for understanding the system's dynamical evolution.The fixed point theory explains how memristive coupling induces diverse synchronization patterns,including stable phase-locking and synchronization–desynchronization transitions,and further accounts for the emergence of chimera states in ring networks as well as their alteration in smallworld networks owing to long-range connections.Field-programmable gate array(FPGA)implementation successfully validates the mathematical models,confirming the feasibility of hardware realization.Overall,this work establishes a theoretical framework linking fixed point properties with firing mechanisms and synchronization dynamics in discrete memristive FHN neural networks,providing insights into potential applications in neuromorphic computing. 展开更多
关键词 discrete memristor discrete neuron complex network chimera state FPGA implementation
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Effects of reflection distance on Richtmyer-Meshkov instability in the reshock process:a discrete Boltzmann study 认领 引用
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作者 Huilin Lai Chuandong Lin +4 位作者 Demei Li Tao Yang Yanbiao Gan Lingyan Lian Aiguo Xu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2026年第4期464-482,共19页
The Richtmyer-Meshkov(RM)instability occurs when a perturbed interface between two fluids undergoes impulsive acceleration due to a shock wave.In this paper,a numerical investigation of the RM instability during the r... The Richtmyer-Meshkov(RM)instability occurs when a perturbed interface between two fluids undergoes impulsive acceleration due to a shock wave.In this paper,a numerical investigation of the RM instability during the reshock process is conducted using the two-component discrete Boltzmann method.The influence of reflection distance on the RM instability,including both hydrodynamic and thermodynamic non-equilibrium effects,is explored in detail.The interaction time between the reflected shock wave and the material interface varies with different reflection distances.Larger reflection distances lead to a longer evolution time of the material interface before reshock,resulting in more complex effects on the interface deformation,the mixing extent of the fluid system,and non-equilibrium behaviors after reshock.Additionally,while the reflection distance has a minimal impact on mixing entropy before the secondary impact,a significant difference emerges after the secondary impact.This suggests that the secondary impact enhances the evolution of the RM instability.Furthermore,non-equilibrium behaviors or quantities exhibit complex dynamics due to the influence of the transmitted shock wave,transverse waves,rarefaction waves,material interfaces,and dissipation/diffusion processes. 展开更多
关键词 Richtmyer-Meshkov instability Discrete Boltzmann method Non-equilibrium effects Compressible flows Reflection distance
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Effects of internal parts on burden distribution and segregation in bell-less top blast furnace 认领 引用
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作者 Wang Zeng Ye-Han Fang +6 位作者 Zuo-Bang Chen De-Sheng Zou Guang-Liang Wang Yun-Peng Si Heng Zhou Tian-Xiang Zhang Ming-Yin Kou 《Journal of Iron and Steel Research International》 SCIE EI CSCD 2026年第4期241-255,共15页
As the key equipment connecting the feeding belt to the top of blast furnace,the structure of the hoppers directly affects the burden distribution in blast furnace throat.Therefore,it is of great significance to explo... As the key equipment connecting the feeding belt to the top of blast furnace,the structure of the hoppers directly affects the burden distribution in blast furnace throat.Therefore,it is of great significance to explore the suitable structure of the hoppers to optimize the burden and gas distribution of the blast furnace and improve the gas utilization rate.A three-dimensional model of a 1:1 bell-less top blast furnace with serial-type hoppers was established based on the discrete element method,which simulates the entire movement process of the burden from the belt to each hopper and then to the throat.The effects of internal components,such as the distributor,guiding cone,and buffer platform,on particle size segregation in the upper hopper,the weighing hopper,and the throat of the blast furnace were investigated.The results indicate that removing the distributor can reduce the burden segregation during the discharge from the weighing hopper.The guiding cone significantly influences the radial particle size distribution within the weighing hopper and its discharge.Eliminating the buffer platform promotes a more uniform burden distribution both in the weighing hopper and the throat of the blast furnace.Among the conditions investigated,removing the distributor and the buffer platform yields the best distribution,with the segregation index improved by 92%compared to the base model,which is recommended for practical operations. 展开更多
关键词 Blast furnace Burden distribution Segregation Internal part Discrete element method
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Mechanical behavior,failure characteristics and energy evolution of layered rock subjected to uniaxial loading 认领 引用
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作者 SHUANG Haiqing LI Lei +3 位作者 XIN Jie ZHOU Bin LIN Haifei MENG Weitao 《Journal of Mountain Science》 SCIE CSCD 2026年第6期2891-2909,共19页
The stability of overlying rock strata is jointly controlled by the advancement rate of coal mining face and rock properties.However,the crossscale mechanical behavior and energy evolution mechanism of two-layered roc... The stability of overlying rock strata is jointly controlled by the advancement rate of coal mining face and rock properties.However,the crossscale mechanical behavior and energy evolution mechanism of two-layered rock under different loading rates remain unclear,and the mesoscopic fracture characteristics and crack evolution law of three-layered rock are yet to be fully elucidated.To address these gaps,uniaxial compression tests were conducted on three types of two-layered rock(siltstone-fine sandstone,siltstone-sandy mudstone,fine sandstone-sandy mudstone) under five loading rates(0.05,0.08,0.10,0.15,0.20 mm/min).Acoustic emission and digital image correlation were coupled with the energy conservation principle to systematically investigate the mechanical properties,failure modes and energy conversion characteristics of the two-layered rock.Furthermore,based on the calibrated meso-parameters of two-layered rock,particle flow code numerical simulations were performed to explore the meso-mechanical properties,crack evolution and failure modes of three-layered rock(siltstone,fine sandstone,sandy mudstone) under typical loading rates(0.05 and 0.20 mm/min).The results showed that the mechanical evolution of twolayered rock could be divided into four typical stages,with synchronized responses from AE and DIC,i.e.,compaction stage(Stage Ⅰ-characterized by loading contact and pore closure),linear elastic stage(Stage Ⅱ-marked by discrete microcrack initiation and elastic energy storage),yield stage(Stage Ⅲ-dominated by extensive crack initiation,propagation,coalescence,partial rock spalling,and dissipative energy release),and residual stage(Stage Ⅳ-governed by post-failure joint surface friction).Specifically,the siltstone-fine sandstone exhibited a particular dual-peak phenomenon.Regarding energy evolution,elastic deformation dominated before reaching peak strength,manifesting as elastic strain energy storage.Post-peak,the rock component with lower compressive strength rapidly degraded,transferring energy to the adjacent component and inducing crack propagation,coalescence,and instability.The micro-crack evolution exhibited four stages,i.e.,initialization,slow propagation,rapid propagation,and stabilization,corresponding to the mechanical behavior of the threelayered rock.Moreover,sandy mudstone was used as an intermediate layer(FSM/MSF),the number of cracks increased by 40%-75%.This study provides a theoretical basis for the stability control of overlying rock strata in mining engineering. 展开更多
关键词 Layered rock Mechanical behavior Crack characteristic Energy evolution Discrete element method
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Constrained RLV guidance via pseudospectral model predictive convex programming and predefined-height sliding mode approach 认领 引用
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作者 Zhe LIU Naigang CUI +1 位作者 Feng ZHANG Jialun PU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2026年第5期466-482,共17页
Online trajectory generation and tracking for the Terminal Area Energy Management(TAEM)phase of a Reusable Launch Vehicle(RLV)is one of the core technologies for achieving a soft landing.The processing of complex non-... Online trajectory generation and tracking for the Terminal Area Energy Management(TAEM)phase of a Reusable Launch Vehicle(RLV)is one of the core technologies for achieving a soft landing.The processing of complex non-convex path constraints significantly reduces the real-time performance of guidance methods.In addition,the terminal full-element state constraints are difficult to satisfy due to the coupling of longitudinal and lateral motion of RLV.To address these issues,a high-precision constrained guidance method for RLV is proposed in this paper.The analytical sensitivity relationships among the terminal states,non-convex path constraints,and control profile are rapidly constructed via multi-interval pseudospectral discretization.The repeated recursive calculation of sensitivity matrix is avoided by linearizing the non-convex constraints at state output points and expanding the sensitivity matrix sequentially,which reduces the time consumption of constraint processing.Furthermore,a model-based prediction-correction process is introduced to eliminate deviation iteratively and constraints are handled using homotopy to improve convergence.Meanwhile,a robust parallel guidance method is presented to overcome numerical instability issues.The guidance commands obtained by trajectory online generation are prioritized executed,while the tracking commands are calculated in parallel to enhance the guidance feasibility.Instead of tracking a fixed reference trajectory,a predefined height-convergent sliding mode surface is designed and tracked online,which can guarantee that the RLV states converge to the desired values at a preset height,even under various uncertainties.Finally,Monte Carlo simulations are conducted to demonstrate the effectiveness and robustness of the proposed method. 展开更多
关键词 Convex optimization Model predictive Parallel guidance Pseudospectral discretization Reusable launch vehicle
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Discrete Polyesters Featuring a Cyclic Pendant Group 认领 引用
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作者 Shuai Wang Qin He +3 位作者 Xi-Tong Chen Dong-Dong Zhou Zhan-Hui Gan Xue-Hui Dong 《Chinese Journal of Polymer Science》 SCIE EI CAS CSCD 2026年第2期416-422,I0012,共7页
In contrast to cyclic polymers with ring-like backbones,side-chain cyclization is another intriguing structural feature that has not been extensively studied.In this study,a library of orthogonally protected monomers ... In contrast to cyclic polymers with ring-like backbones,side-chain cyclization is another intriguing structural feature that has not been extensively studied.In this study,a library of orthogonally protected monomers featuring monocyclic,dicyclic,or tricyclic pendant motifs was designed and prepared based on malic acid derivatives.Polyesters with precise chemical structures and uniform chain lengths were prepared modularly through iterative growth.Meticulous control over the chemical details allows for a close investigation of the topological effects on the polymer properties.Compared to their linear side chain counterparts,the presence of cyclic pendant groups has a significant impact on chain conformation,leading to a reduction in hydrodynamic volume and an enhancement in the glass transition temperature.These results underscore the potential of tailoring polymer properties through rational engineering of side chain topology. 展开更多
关键词 Discrete polymer Iterative growth Side chain topology Cyclic conformation
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Crushing evolution in pebble bed based on a novel method:a crushable DEM study 认领 引用
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作者 Jian Wang Ming‑Zhun Lei +4 位作者 Ming‑Zong Liu Qi‑Gang Wu Zi‑Cong Cai Kai‑Song Wang Hai‑Shun Deng 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2026年第1期212-224,共13页
In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical m... In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical model,and its validity was verified using a simple impact test.A crushable discrete element method(DEM)framework is built based on the previously established theoretical model.The tensile strength,which considers the fractal theory,size effect,and Weibull variation,was assigned to each generated particle.The assigned strength is then used for crush detection by comparing it with its maximum tensile stress.Mass conservation is ensured by inserting a series of sub-particles whose total mass was equal to the quality loss.Based on the crushable DEM framework,a numerical simulation of the crushing behavior of a pebble bed with hollow cylindrical geometry under a uniaxial compression test was performed.The results of this investigation showed that the particle withstands the external load by contact and sliding at the beginning of the compression process,and the results confirmed that crushing can be considered an important method of resisting the increasing external load.A relatively regular particle arrangement aids in resisting the load and reduces the occurrence of particle crushing.However,a limit exists to the promotion of resistance.When the strain increases beyond this limit,the distribution of the crushing position tends to be isotropic over the entire pebble bed.The theoretical model and crushable DEM framework provide a new method for exploring the pebble bed in a fusion reactor,considering particle crushing. 展开更多
关键词 Crushing behavior Granular material Discrete element method Pebble bed Fractal theory
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Paving process of nylon powder considering mesoscopic forces in selective laser sintering 认领 引用
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作者 Xiangwu Xiao Zhenglan Zhang +4 位作者 Shengqiang Jiang Rui Chen Yue Zhang Jinfeng Peng Ruitao Peng 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2026年第1期14-30,共17页
Powder paving is an intermediate process of selective laser sintering(SLS).The dimensional accuracy and mechanical properties of sintered components are directly affected by the quality of the powder paving process,wh... Powder paving is an intermediate process of selective laser sintering(SLS).The dimensional accuracy and mechanical properties of sintered components are directly affected by the quality of the powder paving process,which is closely related to the flow characteristics of the powder and the process parameters of powder paving.This study investigated the simulation and optimization of the nylon powder paving in SLS by combining a discrete-element-method numerical simulation with a process test.A dynamic model was established to describe the flow and paving process of nylon powder at a preheating temperature considering mesoscopic van der Waals and electrostatic forces.The effects of the physical parameters and ambient temperature on the flow characteristics of nylon powder were analyzed,and the intrinsic relationship between the physical parameters of nylon powder,the process parameters of powder paving,and the quality of the powder paving were explored.A multi-objective regression model of the quality of powder paving was established using the response surface methodology,and a genetic algorithm was adopted to optimize the quality of the powder paving.A scientific and intelligent database of the nylon powder paving process in SLS was constructed by matching the process parameters of powder paving and physical parameters of the nylon powder,and the level of the SLS process was improved. 展开更多
关键词 Selective laser sintering Nylon powder Discrete element numerical Spreadability Response surface methodology Multi-objective optimization
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Effects of slurry and rock type on shear properties of grout-filled jointed rock:Experimental and numerical investigation 认领 引用
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作者 Xuewei Liu Jinze Sun +3 位作者 Bin Liu Quansheng Liu Qingcheng Liu Lei Zhu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2026年第6期4702-4722,共21页
This study investigates the influence of slurry type and rock type on the evolution of microscopic failure during the shear process of grout-filled jointed rock(GJR)through direct shear tests and nanoindentation exper... This study investigates the influence of slurry type and rock type on the evolution of microscopic failure during the shear process of grout-filled jointed rock(GJR)through direct shear tests and nanoindentation experiments.The interfacial shear fracture behavior is analyzed,and an interfacial bond strength model is established.Results indicate that the variation trend of shear strength is consistent across all specimen types.Mudstone specimens grouted with a self-developed high-performance composite cement slurry(MH)exhibit the most pronounced reinforcement effect and the smallest interfacial transition zone(ITZ).Additionally,a discrete element method(DEM)model is proposed and validated to investigate the shear performance and progressive failure mechanisms.Numerical simulations confirm that tensile cracks dominate the failure process,with micro-cracks formed before peak stress accounting for 10%to 30%of the total.Furthermore,coordination number distribution and acoustic emission(AE)analyses reveal that the MH specimens display a higher proportion of shear failure modes compared to other specimens.Finally,energy evolution within the GJR specimens during shear loading is examined.Variations in slurry type result in greater dissipative energy losses compared to variations in rock type.The MH specimens demonstrate the highest proportion of damping energy and require greater elastic energy for failure initiation,indicating superior interfacial bonding performance.This work provides a novel perspective for optimizing material selection and enhancing grouting effectiveness in the reinforcement of fractured surrounding rock masses. 展开更多
关键词 Grouting Direct shear test Discrete element method Micro-cracks Mechanical property
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A 32‑channel charge‑sensitive amplifier for delay‑line readout of parallel plate avalanche counter array 认领 引用
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作者 Yue‑Zhao Zhang Peng Ma +8 位作者 Zhuang‑Yu Lin Zhen‑Fei Tan Xing‑Chi Han Chen Liu Shuo Wang Da‑Peng Sun Zhi‑Quan Li En‑Hong Wang Shou‑Yu Wang 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2026年第1期164-179,共16页
A 32-channel charge-sensitive amplifier(CSA)is designed for fast timing in the delay-line readout of a parallel plate avalanche counter(PPAC)array.It is realized on a PCB with operational amplifiers and other discrete... A 32-channel charge-sensitive amplifier(CSA)is designed for fast timing in the delay-line readout of a parallel plate avalanche counter(PPAC)array.It is realized on a PCB with operational amplifiers and other discrete components.Each channel consists of an integrator,a pole-zero cancellation net,and a linear amplification stage,which can be adapted to accommodate either positive or negative input signals.The RMS equivalent input noise charges are 3.3 fC,the conversion gains are approximately±2 mV∕fC,and the intrinsic time resolution reaches 32 ps.In the prototype PPAC application,the CSA performs as well as the commercial FTA820A amplifier,providing a position resolution as good as 0.17 mm,and exhibiting reliable stability during several hours of continuous data acquisition. 展开更多
关键词 Charge-sensitive amplifier Fast timing Parallel plate avalanche counter Delay-line Discrete components
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Design and mechanical characterization of discretely assembled mechanical metamaterials for macroscale applications 认领 引用
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作者 Zhengtao Shu Ying Zhou +2 位作者 Junjian Fu Hao Li Liang Gao 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2026年第2期80-94,共15页
Manufacturing large-scale mechanical metamaterials(MMs) is extremely challenging owing to the limitations of machining technology and equipment.This study proposes a family of discretely assembled MMs to address this ... Manufacturing large-scale mechanical metamaterials(MMs) is extremely challenging owing to the limitations of machining technology and equipment.This study proposes a family of discretely assembled MMs to address this issue.In this work,six types of MM unit cells are divided into several face blocks,which can be mass-produced by traditional low-cost manufacturing processes.The discrete face blocks are then assembled using connectors and fasteners to form a unit cell.These assembled unit cells can be further discretely assembled for modular constructions and reconfigurable MM structure systems.The results show that the discretely assembled MMs exhibit excellent mechanical properties such as high stiffness,compression resistance,and auxetic and chiral behaviors.In addition,two typical application scenarios and an example show that the discrete assembly strategy provides accessibility for the heterogeneous and multi-material assemblies of MMs.The discrete assembly strategy,benefiting from the incremental assembly feature,is proven to be a low-cost and highly repeatable forming process.It provides scalability and functionality that are not achievable with traditional manufacturing techniques.Combined with advanced design methods and automated assembly processes,discretely assembled MMs will be significant in future intelligent structures,soft robotics,and aerospace. 展开更多
关键词 Discrete assembly Mechanical metamaterials Modular and reconfigurable system Mass production Large-scale forming
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Mesoscale Mechanical Discrete Model for Cementitious Composites with Microfibers 认领 引用
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作者 Lei Shen Linfeng Hu +3 位作者 Giovanni Di Luzio Maosen Cao Lei Xu Gianluca Cusatis 《Engineering》 SCIE EI CSCD 2026年第6期159-174,共16页
Microfibers(less than 100 lm in diameter)are commonly employed in structural applications to mini-mize early shrinkage cracking and lower pore pressure during fires.For any application,micro fiber-reinforced concrete(... Microfibers(less than 100 lm in diameter)are commonly employed in structural applications to mini-mize early shrinkage cracking and lower pore pressure during fires.For any application,micro fiber-reinforced concrete(FRC)structural behavior and durability must be estimated using the mechanical constitutive law.Formulating a mechanical constitutive law for FRC presents several difficulties in terms of comprehending the physical principles and employing suitable numerical techniques.A novel model called"lattice discrete particle model for micro-FRC(LDPM-MicroF)"is presented to simulate the fracture behavior of micro-FRC.An equivalent fiber diameter coefficient has been defined to balance modeling accuracy and computational cost so that the LDPM-MicroF model can simulate the mechanical responses of engineered cementitious composites.The unimodal variation in tensile strength caused by the increase in microfiber dose is assessed and quantitatively reproduced by LDPM-MicroF predictions.This phe-nomenon is explained by a combination of mesoscopic mechanisms and the"near-field effect"of the fibers.A small number of microfibers can improve the strength of the matrix and thus slightly the tensile strength.However,when the dosage of microfibers exceeds a certain amount,the tensile strength decreases as the contribution of the fiber bridging force to the strength becomes lower than that of the replaced matrix.This research has provided new insights into the physical comprehension of the mechanical properties of micro-FRC,which has significant implications for the field of study. 展开更多
关键词 Microfiber Fiber reinforced concrete Unimodal tensile strength variation Mesoscopic discrete modeling
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Enhancing fracture uniformity in hydraulic fracturing:A 3D simulation study on natural fracture networks and plugging optimization 认领 引用
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作者 Xingyi Wang Xin Chang +3 位作者 Chunhe Yang Yintong Guo Haijun Mao Xilin Shi 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2026年第7期5505-5523,共19页
The non-uniform propagation of multi-cluster fractures during the hydraulic fracturing of deep shale gas reservoirs is an ongoing challenge.The dynamic interaction between natural fracture networks and in-situ stress ... The non-uniform propagation of multi-cluster fractures during the hydraulic fracturing of deep shale gas reservoirs is an ongoing challenge.The dynamic interaction between natural fracture networks and in-situ stress fieldsstrongly affects fracture propagation,decreasing fracturing efficiency.In this study,a 3D discrete lattice numerical simulation is employed to systematically analyze the dynamic regulatory mechanisms of multi-cluster fracture propagation under the combined effects of natural fracture characteristics,differential in-situ stress,and temporary plugging strategies.The goal is to optimize temporary plugging parameters for balanced fracture extension.The results reveal that increasing the natural fracture density and size reduces the average hydraulic fracture length while markedly mitigating stress shadowing effects.A greater difference in horizontal in-situ stress intensifiesthe interfracture stress,suppresses natural fracture activation and decreases mechanical interference.Ballsealing temporary plugging effectively limits the excessive growth of dominant outer fractures.As the number of plugging balls increases,the fracture length differentiation coefficientdecreases but then increases,with the optimal plugging timing identifiedat 37.5% of the total fracturing duration.Singlestage plugging achieves a better fracture length differentiation coefficientthan two-stage plugging does.Field applications require multi-stage plugging to increase operational tolerance,which requires proportional increases in the number of plugging balls.The established optimization criteria for temporary plugging parameters provide a theoretical basis for increasing the development efficiencyof deep shale gas reservoirs. 展开更多
关键词 Deep shale Hydraulic fracturing Natural fracture Temporary plugging optimization Discrete lattice model
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A High-Fidelity and High-Efficiency Simulator for 6G-Integrated Space-Ground Networks 认领 引用
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作者 Haibo Zhou Xiaoyu Liu +5 位作者 Xin Zhang Xiaohan Qin Mengyang Zhang Yuze Liu Weihua Zhuang Xuemin Shen 《Engineering》 SCIE EI CSCD 2026年第1期62-78,共17页
Mega-constellation networks have recently gained significant research attention because of their potential for providing ubiquitous and high-capacity connectivity in future sixth-generation(6G)wireless communication s... Mega-constellation networks have recently gained significant research attention because of their potential for providing ubiquitous and high-capacity connectivity in future sixth-generation(6G)wireless communication systems.However,the high dynamics of network topology and large scale of a megaconstellation pose new challenges to constellation simulation and performance evaluation.To address these issues,we introduce Ultra Star,a high-fidelity and high-efficiency computer simulator to support the development of 6G wireless communication systems with low-Earth-orbit mega-constellation satellites.The simulator facilitates the design and performance analysis of various algorithms and protocols for network operation and deployment.We propose a systematic,scalable,and comprehensive simulation architecture for the high-fidelity modeling of network configurations and for performing highefficiency simulations of network operations and management capabilities,while providing users with intuitive visualizations.We capture heterogeneous topology characteristics by establishing an environment update algorithm that incorporates real ephemeris data for satellite orbit prediction,sun outages,and link handovers.For a realistic simulation of software and hardware configurations,we develop a Network Simulator 3 based network model to support networking protocol extensions.We propose a message passing interface-based parallel and distributed approach with multiple cores or machines to achieve high simulation efficiency in large and complex network scenarios.Experimental results demonstrate the high fidelity and efficiency of Ultra Star can help pave the way for 6G integrated space-ground networks. 展开更多
关键词 Low-Earth-orbit satellite networks Discrete event simulation architecture Parallel and distributed simulation Performance evaluation
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