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A Study on Multi-defect Constrained Bendability of Thin-walled Tube NC Bending Under Different Clearance

Chinese Journal of Aeronautics 2011年第1期24卷 102-112页

作者： li heng YANG He State Key Laboratory of Solidification Processing School of Materials Science and Engineering~ Northwestern Polytechnical University Xi'an 710072 China

Thin-walled tube numerical control （NC） bending is a tri-nonlinear physical process with multi-defect and multi-die constraints. The clearance on each contact interface is the major factor to indicate the contact conditions. A three-dimensional-finite element （3D-FE） model is established to consider the realistic dynamic boundary conditions of multiple dies under ABAQUS/Explicit platform. Combined with experiment, numerical study on bending behavior and bendability under different clearance between tube and various dies is conducted in terms of wrinkling, wall thinning and cross section deformation. The results show that （1）with smaller clearance of tube-wiper die and tube-mandrel, the wrinkling can be restrained while the wall thinning It and cross-section deformation Id increase; while excessive small clearance blocks tube materials to flow past tangent point and causes piles up, the onset of wrinkling enhances It and Id. （2）Both It and Id decrease with smaller clearance of tube-pressure die; the wrinkling possibility rises with larger clearance on this interface if the mandrel’s freedom along Y-axis is opened; smaller clearance of tube-bend die prevents wrinkling while increases It, and the clearance on this interface has little effect on Id. （3）A modified Yoshida buckling test （YBT） is used to address the wrinkling mechanisms under normal constraints in tube bending： the smaller clearance may restrain wrinkling efficiently; the smaller wall thickness, the less critical clearance needed; the critical clearance for tube bending 38 mm×1 mm×57 mm （tube outer diameter×wall thickness×centerline bending radius） equals about 20% of initial wall thickness.

关键词： bendability clearance defects thin-walled tube numerical control bending

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Nanowires:Synthesis and Energy/Environmental Applications

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Energy & Environmental Materials 2021年第4期4卷 544-561页

作者： heng li Ying-Jie Zhu State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

As the main inorganic component of human bones and teeth,hydroxyapatite(HAP)materials have been widely investigated for various applications especially in the biomedical ***,HAP nanowires(HAP NWs)have attracted research interest in the energy and environment-related fields owing to their advantages such as excellent biocompatibility and bioactivity,high-thermal stability,surface modification and functionalization,and selfassembly to form nanoscale porous networked *** this review,we first briefly discuss the synthesis of HAP *** we focus on summarizing the foremost advances in energy and environment-related applications of HAP NWs,including the battery,solar energy-assisted water evaporation,light-driven self-propelled device,thermal insulation,fireresistant inorganic paper,water purification,air purification,molecular detection,superhydrophobic surface,and high-strength nanocomposite *** addition,the future research directions on HAP NWs and their energy and environmental applications are *** review aims to provide inspiration and stimulate extensive future studies in the energy and environmental applications of HAP NWs and other inorganic NWs.

关键词： hydroxyapatite nanowire application energy environment

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Vaidya-de Sitter Black Hole with Spin Fields

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Chinese Physics Letters 1998年第8期15卷 553-554页

作者： li Zhong-heng Department of Physics Zhanjiang Normal CollegeZhanjiang 524048

The generalized Teukolsky-type master equation in Vaidya-de Sitter space-time is *** is found that the massive Dirac field of spin state p=1/2 differs greatly from the massive Dirac field of spin state p=-1/2 in radiative *** effect originates from the variance of Dirac vacuum near the event horizon in the nonstatic space-time caused by spin state.

关键词： mechanism. massive horizon

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Quantum Corrections to the Entropy of a Barriola-Vilenkin Black Hole due to Spin Fields

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Chinese Physics Letters 2000年第6期17卷 396-397页

作者： li Zhong-heng Department of Physics Zhanjiang Normal CollegeZhanjiang 524048

The radial parts of the gravitational,electromagnetic,neutrino,and massless scalar fields in Barriola-Vilenkin spacetime are transformed to the form of the Teukolsky-type master *** first quantum corrections to the entropy of the black hole due to the spin fields are calculated by using the brick wall *** is shown that the contribution of any one of the spin fields is quadratically divergent at the event horizon and is proportional to the surface area of the event horizon.

关键词： equation. correction transformed

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Conditional Simulation of Flow in Heterogeneous Porous Media with the Probabilistic Collocation Method

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Communications in Computational Physics 2014年第9期16卷 1010-1030页

作者： heng li Department of Energy and Resources Engineering College of EngineeringPeking UniversityBeijing 100871China.

A stochastic approach to conditional simulation of flow in randomly heterogeneous media is proposed with the combination of the Karhunen-Loeve expansion and the probabilistic collocation method(PCM).The conditional log hydraulic conductivity field is represented with the Karhunen-Loeve expansion,in terms of some deterministic functions and a set of independent Gaussian random *** propagation of uncertainty in the flow simulations is carried out through the PCM,which relies on the efficient polynomial chaos expansion used to represent the flow responses such as the hydraulic *** the PCM,existing flow simulators can be employed for uncertainty quantification of flow in heterogeneous porous media when direct measurements of hydraulic conductivity are taken into *** illustration of several numerical examples of groundwater flow,this study reveals that the proposed approach is able to accurately quantify uncertainty of the flow responses conditioning on hydraulic conductivity data,while the computational efforts are significantly reduced in comparison to the Monte Carlo simulations.

关键词： Conditional simulation probabilistic collocation method Karhunen-Loeve expansion polynomial chaos expansion

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WAVE MAKING COMPUTATION IN TIME DOMAIN FOR MULTI-HULL SHIPS

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Journal of Hydrodynamics 2006年第2期18卷 225-230页

作者： li Guo-an YE heng-kui School of Traffic Science and Engineering Huazhong University of Science and Technology Wuhan 430074China

A method Green function satisfying of three-dimensional time domain linear conditions at free surface and body surface boundary was employed to analyze the wave resistance and wave profile of a displacement multi-hull ship. The wave profile induced by a moving time domain point source was compared with those by a Havelock source, and satisfactory results were obtained. The panel method based on the time domain source distribution on the ship mean wetted hull surface was used to perform the wave making com- putations tbr mono-hull ships, catamaran and trimaran. Reasonable results were also obtained. Using the numerical method the wave profile simulations of multi-hull ships for a given Froude number were conducted.

关键词： time domain Green function ship wave making mono-hull catamaran trimaran

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Insight into deformation allocation in the multi-pass roll forming of a double-walled brazed tube

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Advances in Manufacturing 2023年第4期11卷 567-586页

作者： Meng-Meng liu Yu-li liu heng li State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an710072People’s Republic of China

Deformation allocation is an important factor that affects 720°curling forming from copper-coated steel strips to double-walled brazed tubes(DWBTs).In this study,four schemes of deformation allocation,considering different weights of the total feed distance,are proposed,and a 3D finite element(FE)model of the multi-pass roll forming process for DWBT is developed and verified to investigate the cross-sectional evolution and deformation *** results show the following.(i)In the 720°curling forming process from the steel strip into double-walled tubes,the curvature of the formed circular arc initially increases and then remains stable with roll forming,and the inner and outer tubes of the DWBT are formed in the third and fifth forming *** forming can eliminate the gap between the double walls and improve the overall roundness.(ii)For different deformation allocations,the cross-sectional profiles of the roll-formed parts exhibit a discrepancy,and the deformation amount varies with the roll-forming *** deformation amount in Scheme three is the maximum,and the cross-sectional profile deviates significantly from the ideal shape and fails to form a DWBT,which indicates that the deformation allocation is unsuitable.(iii)The roundness of the outer tube is better than that of the inner ***,the roundness of the inner tube is the key to restricting the forming accuracy of the *** with Schemes one and two,Scheme four with a linear allocation of the total feed distance exhibits the best roundness,and the deformation allocation is reasonable;i.e.,when the contact points between the rollers and steel strip are in a straight line,the roundness of the DWBT is in good agreement with the ideal condition.

关键词： Double-walled brazed tube(DWBT) Multi-pass roll forming Deformation allocation Cross-sectional profile Roundness

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Transmission through Ag/Organic Multilayers Using Continuous and Island Metal Films

引用

Chinese Physics Letters 2011年第6期28卷 295-297页

作者： li heng Zheng Ning School of Electronic and Optical Engineering Nanjing University of Science and TechnologyNanjing 210094 Key Laboratory of Cluster Science(Ministry of Education) Beijing Institute of TechnologyBeijing 100081

We present the results of transmission spectrum measurements of Ag/tetraphenyldiphenyldiamine periodic multilayers,as well as Ag/SiO2 in the visible and near IR spectral *** continuous silver films,these one-dimensional multilayers transmit visible light in controllable bands and stop IR *** island metal films,surface plasmon modes are excited,which exhibits broad absorption features covering the entire visible spectral *** work successfully extends the discussion of metal-dielectric one-dimensional photonic crystals to metal-organic cases and exhibits the linear optical properties of surface plasmon modes at the island metal/organic interface.

关键词： visible silver excited

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Influence of cycle time distribution on coating uniformity of particles in a spray fluidized bed by using CFD-DEM simulations

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Particuology 2023年第5期76卷 151-164页

作者： heng li Daoyin liu Jiliang Ma Xiaoping Chen Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy&EnvironmentSoutheast UniversityNanjing210096China

Cycle Time Distribution(CTD)plays a critical role for determining uniformity of particle coating in spray fluidized ***,the CTD is influenced by both geometrical structure and operating conditions of fluidized *** this study,a spray fluidized bed of coating process is simulated by a comprehensive Computational Fluid Dynamics-Discrete Element Model(CFD-DEM).To achieve different behaviors of CTD,some modifications are designed on a pseudo-2D internally circulating fluidized bed,which traditionally composes of a high-velocity upward bed and low-velocity downward *** modifi-cations include making the air distributor slope and/or laying a baffle in the downward ***,the CTD and evolution of particle size distribution under different bed structures are *** CTD directly influences the coating *** making the particles flowing along a parallel direction in the downward bed through the geometrical modifications,the CTD becomes narrower and the coating uniformity is significantly ***,under the optimized bed structure,the influence of oper-ating conditions on the coating uniformity is *** increasing the fluidization gas velocity and the fluidization gas temperature and reducing the liquid spray rate can improve the coating uniformity.

关键词： Spray fluidized bed Particle coating Cycle time distribution CFD-DEM

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The li lineage of Traditional Chinese Medicine

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Chinese Medicine and Culture 2020年第2期3卷 105-110页

作者： heng li International Education College Shanghai University of Traditional Chinese MedicineShanghaiChina

Chinese medicine cannot be separated from Chinese culture and *** li Ding's path floridly embodies that,and so is worthy not just of admiration,but also of studious *** from still,after well over half a century there,serving as a doctoral supervisor professor at the Shanghai University of Traditional Chinese Medicine(SHUTCM),and being one of the university's founders,he continues to contribute long after having been formally declared“A representative inheritor for China intangible cultural heritage-Acupuncture and Moxibustion.”This is the second article in a three-part series on Professo *** *** first part focuses on“The lineage of Gu Yi Tang,”and that storied our family history we will continue discussing now,with this second installment:"The lineage of Chinese Studies,"which introduces professor li's Chinese cultural *** forthcoming third part:“The lineage of Dao Sheng Tang”will discuss professor li's inheritance of Chinese medicine *** three articles will bring our readers a rich and colorful Chinese scroll painting,which not only focus on acupuncture and general Chinese medicine,but also touch ancient Chinese history,culture,Taoism,and even more.

关键词： Acupuncture and moxibustion Chinese studies intangible cultural heritage li Ding,lineage traditional Chinese medicine

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