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Mesoscopic modelling of UHPCC material under dynamic tensile loadings

Defence Technology（防务技术） 2023年第5期23卷 75-91页

作者： xiang-zhen kong Shang-bin Yang Tao Zhang Qin Fang Heng-bo xiang Rui-wen Li Engineering Research Centre for Safety and Protection of Explosion&Impact of Ministry of Education Southeast UniversityJiangsu Nanjing211189China State Key Laboratory of Disaster Prevention&Mitigation of Explosion&Impact Army Engineering University of PLAJiangsu Nanjing210007China Research Institute for National Defense Engineering of Academy of Military Science PLALuoyang471023China School of Civil Engineering and Architecture Xi'an University of TechnologyXi'an710048China

This paper presents a new 3D mesoscopic model of ultra-high performance cement-based composite(UHPCC)to investigate its dynamic tensile *** this model,the UHPCC is regarded as a two-phase material composed of cementitious matrix and randomly distributed *** model is established using the commercial software LS-DYNA and involves generating the randomly distributed fiber elements with considerations of diameter,length,orientation and volume fraction,and then fully constraining them with the *** particular,to capture the slipping effect between fibers and matrix that has a strong influence on the dynamic tensile behavior,the fibers are modelled by a fictitious material represented by the load-slip *** strain-rate effect of slipping force neglected in most of previous studies is considered by calibrating constitutive parameters of the fictitious material under different strain-rates based on the single fiber pullout ***,the 3D mesoscopic model is validated against three sets of tension-dominated experiments covered a wide range of loading *** predictions demonstrate that strain-rate effect of slipping force must be considered,and the neglect of it may lead to a great underestimation of the dynamic tensile strength of UHPCC material and would unavoidably underestimate the blast resistance of UHPCC components.

关键词： UHPCC Dynamic tensile behavior Mesoscopic model Strain-rate effect Impact and blast loadings

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Ultralight pyrolytic carbon foam reinforced with amorphous carbon nanotubes for broadband electromagnetic absorption

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International Journal of Minerals,Metallurgy and Materials 2023年第3期30卷 570-580页

作者： Luo kong Sihan Luo Shuyu Zhang Guiqin Zhang Yi liang School of Materials Science and Engineering Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic MaterialsShaanxi University of Science and TechnologyXi’an 710021China

For electromagnetic wave-absorbing materials,maximizing absorption at a specific frequency has been constantly achieved,but enhancing the absorption properties in the entire band remains a *** this work,a 3D porous pyrolytic carbon(PyC)foam matrix was synthesized by a template *** carbon nanotubes(CNTs)were then in-situ grown on the matrix surface to obtain ultralight CNTs/Py C *** in-situ grown amorphous CNTs were distributed uniformly and controlled by the catalytic growth time and can enhance the interface polarization and conduction loss of *** the electromagnetic wave enters the internal holes,the electromagnetic energy can be completely attenuated under the combined action of polarization,conductivity loss,and multiple *** ultralight CNTs/Py C foam had a density of 22.0 mg·cm^(-3)and a reflection coefficient lower than-13.3 d B in the whole X-band(8.2-12.4 GHz),which is better than the conventional standard of effective absorption bandwidth(≤-10 dB).The results provide ideas for researching ultralight and strong electromagnetic wave absorbing materials in the X-band.

关键词： ultralight carbon foam amorphous carbon nanotubes broadband electromagnetic absorption

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In-situ observation of asymmetrical deformation around inclusion in a heterogeneous additively manufactured 316L stainless steel

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Journal of Materials Science & Technology 2021年第30期89卷 133-140页

作者： Decheng kong Chaofang Dong Xiaoqing Ni Zhang liang Xiaogang Li Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing100083China Department of Materials Science and Engineering Massachusetts Institute of TechnologyCambridgeMA02139USA Shanghai Engineering Research Center of 3D Printing Materials Shanghai Research Institute of MaterialsShanghai200437China

Oxide inclusions widely exist in additively manufactured components due to the native oxide layer on the powder surface,together with gas impurities during the printing *** in-situ tensile tests combined with electron backscatter diffraction(EBSD)and electron channeling contrast imaging(ECCI)techniques,we propose an asymmetrical cracking mechanism around the oxide inclusions in a selective laser melted 316L stainless *** heterogeneous sub-micro cellular structures lead to different twinning tendencies around the inclusions due to the size-related critical twinning stresses,and the deformation-induced nano-twin clusters can resist the cracking propagation,therefore resulting in the asymmetrical cracking behaviors around the inclusions.

关键词： Selective laser melting 316L stainless steel Oxide inclusion Asymmetrical crack Cellular structure

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Study on Cutting Force,Cutting Temperature and Machining Residual Stress in Precision Turning of Pure Iron with Different Grain Sizes

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Chinese Journal of Mechanical Engineering 2020年第4期33卷 159-167页

作者： Yinfei Yang Lu Jin Jinpeng Zhu Jinxing kong liang Li College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Pure iron is one of the difficult-to-machine materials due to its large chip deformation,adhesion,work-hardening,and built-up edges formation during *** leads to a large workpiece deformation and challenge to meet the required technical ***,under varying the grain size of pure iron,the influence of cutting speed,feed,and depth of cut on the cutting force,heat generation,and machining residual stresses were explored in the turning process to improve the machinability without compromising the mechanical properties of the *** experimental findings have depicted that the influence of grain size on cutting force in the precision turning process is not ***,the cutting temperature and residual stress of machining fine-grain iron were much smaller than the coarse grain at all levels of cutting parameters.

关键词： Pure iron Grain size Cutting parameter Cutting force Cutting temperature Residual stress

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Immunomodulation and osteointegration of infected implants by ion-riched and hierarchical porous TiO_(2)matrix

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Nano Research 2023年第2期16卷 2905-2914页

作者： Yang Xue Lan Zhang Fuwei Liu liang kong Yong Han State-key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Military Stomatology&National Clinical Research Center for Oral Diseases&Shaanxi Clinical Research Center for Oral Diseases Department of Oral and Maxillofacial SurgerySchool of StomatologyThe Fourth Military Medical UniversityXi’an 710032China

Infection is a main cause of implant *** microenvironment cell experiencing after antimicrobial therapy of infected implants is very crucial for immunomodulation and subsequent *** on the superiority of photothermal therapy in anti-infection,a matrix of nanograined TiO_(2)with(Si/P)-dual ions and hierarchical nano/microporous topography is developed on Ti implant by micro-arc *** shows good photothermal properties due to the lattice distortion induced by ion doping and can kill bacteria with near-infrared(NIR)light irradiation *** to the combined action of porous topography and release of Si/P ions,the TiO_(2)matrix achieves M1-to-M_(2)phenotype switch of macrophages timely at different simulating infection stage and accelerates recruitment,proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells(BMSCs)in *** vivo,the TiO_(2)matrix also shows desired antibacterial performance after photothermal therapy and exhibits outstanding immunomodulatory ability and new bone formation *** study provides a promising TiO_(2)matrix applied in clinic for settling implant infection by NIR light irradiation and promoting bone regeneration through osteoimmunomodulation.

关键词： photothermal antibacterial immunomodulation osteointegration

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Reactions of Laser Ablation-magnesium Plasma with Methanol Clusters

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Chemical Research in Chinese Universities 2006年第5期22卷 621-625页

作者： ZHANG Shu-dong kong xiang-he ZHU xiang-jun WANG Yan JIANG Su-rong College of Physics and Engineering Qufu Normal University Qufu 273165 P. R. China

The laser ablation-molecular beam（LA-MB） method is useful for studying the reactions of metal ions with molecular clusters. Reactions of magnesium plasma with methanol clusters were studied by using this method. A specially designed reaction cell was used as a fast flow reactor operated under thermal conditions, and the reaction products were measured with a time-of-flight（TOF） mass spectrometer. Surprisingly, several series of cluster ions with complex sizes and intensity distributions were obtained when the laser ablating was applied to different parts of the molecular beam. In the front part of the molecular beam, strong Mg^＋（CH3OH）n（ n = 0-5） and weak H^＋（CH3OH）n（ n = 0-5 ） cluster ions were observed with relatively small cluster sizes ; in the middle part of the molecular beam, the main cluster ions were H^＋（ CH3OH）n （ n = 6-17 ） and H^＋（ H2O） 2 （ CH3OH）n（ n = 6-17 ） with a relatively large cluster size and a weak intensity; in the back part of the molecular beam, two new series of cluster ions, MgO^＋（ H2O）（ CH3 OH）n（ n = 6-10 ） and MgOCH3^＋（ CH3OH）n（ n = 6-10）, were obtained and accompanied by weak H^＋（CH3OH）n（n = 4-7） and H^＋（ H2O）2 （CH3OH）n（ n = 3-6）. The formation mechanisms and speed characteristics of the cluster ions are discussed in this article.

关键词： Laser ablation-molecular beam Mg plasma Methanol cluster Ion-molecular cluster reaction Formation mechanism

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Delay-dependent Non-fragile H_∞ Control for Linear Systems with Interval Time-varying Delay

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International Journal of Automation and computing 2015年第1期12卷 109-116页

作者： Jun-Jun Hui He-Xin Zhang xiang-Yu kong The Xi'an Research Institute of High Technology

This paper considers the problem of delay-dependent non-fragile H∞control for a class of linear systems with interval time-varying delay. Based on the direct Lyapunov method, an appropriate Lyapunov-Krasovskii functional(LKF) with triple-integral terms and augment terms is introduced. Then, by using the integral inequalities and convex combination technique, an improved H∞performance analysis criterion and non-fragile H∞controller are formulated in terms of linear matrix inequalities(LMIs), which can be easily solved by using standard numerical packages. At last, two numerical examples are provided to demonstrate the effectiveness of the obtained results.

关键词： Lyapunov-Krasovskii functional(LKF) non-fragile H∞control linear matrix inequality(LMI) interval time-varying delay

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Tumor-suppressor effects of chemical functional groups in an in vitro co-culture system

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Frontiers of Materials Science 2014年第2期8卷 136-141页

作者： Su-Ju xu Fu-Zhai CUI xiang-Dong kong Institute of Biomaterials and Marine Biological Resources College of Life Sciences Zhejiang Sci-Tech University Hangzhou 310018 China Institute of Regenerative Medicine and Biomimetic Materials School of Materials Science and Engineering Tsinghua University Beijing 100084 China

Liver normal cells and cancer cells co-cultured on surfaces modified by different chemical functional groups, including mercapto （-SH）, hydroxyl （-OH） and methyl （-CHz） groups. The results showed that different cells exhibited changes in response to different surfaces. Normal cells on -SH surface exhibited the smallest contact area with mostly rounded morphology, which led to the death of cancer cells, while cancer cells could not grow on -CH3 groups, which also died. In the co-culture system, the -CH3 group exhibited its unique effect that could trigger the death of cancer cells and had no effects on normal cells. Our findings provide useful information on strategies for the design of efficient and safe regenerative medicine materials.

关键词： tumor suppressor chemical functional group co-culture system regen-erative medicine material

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Kinetic Behavior of Exchange-Driven Growth with Catalyzed-Birth Processes

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Communications in Theoretical Physics 2006年第6X期46卷 1113-1120页

作者： WANG Hai-Feng LIN Zhen-Quan kong xiang-Mu Department of Physics Wenzhou University Wenzhou 325027 China Department of Physics Qufu Normal University Qufu 273165 China

Two catalyzed-birth models of n-species （n ≥ 2） aggregates with exchange-driven growth processes are proposed and compared. In the first one, the exchange reaction occurs between any two aggregates Ak^m and Af^m of the same species with the rate kernels Km（k,j）= Kmkj （m = 1, 2,... ,n, n ≥ 2）, and aggregates of A^n species catalyze a monomer-birth of A^l species （l = 1, 2 , n - 1） with the catalysis rate kernel Jl（k,j） -Jlkj^v. The kinetic behaviors are investigated by means of the mean-field theory. We find that the evolution behavior of aggregate-size distribution ak^l（t） of A^l species depends crucially on the value of the catalysis rate parameter v：（i） ak^l（t） obeys the conventional scaling law in the case of v ≤ 0, （ii） ak^l（t） satisfies a modified scaling form in the case of v 〉 0. In the second model, the mechanism of monomer-birth of An-species catalyzed by A^l species is added on the basis of the first model, that is, the aggregates of A^l and A^n species catalyze each other to cause monomer-birth. The kinetic behaviors of A^l and A^n species are found to fall into two categories for the different v：（i） growth obeying conventional scaling form with v ≤ 0, （ii） gelling at finite time with v 〉 0.

关键词： behavior exchange-driven growth catalyzed-birth scaling law rate equations

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Exergy analysis of operation process of district heating systems

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Journal of Central South University 2017年第7期24卷 1663-1670页

作者： JIE Peng-fei kong xiang-fei LI Jing School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China School of Energy and Environmental Engineering Hebei University of TechnologyTianjin 300401China China Environmental Resources Technology Co. LtdBeijing 100012China

The nature of the exergy consumption of district heating(DH) systems can not be explained clearly using the first law of *** analysis method was used.A case study based on a DH system in Inner Mongolia,China,was carried *** impact of operating parameters and design parameters on the energy quality of circulating water and exergy losses of DH systems during heat distribution was *** show that the energy quality of circulating water and exergy losses of DH systems during heat distribution could be reduced by decreasing the indoor temperature or increasing radiator *** with other factors,the outdoor temperature and indoor temperature have a greater impact on the energy quality of circulating water,exergy losses of circulating water,and total exergy losses during heat *** the outdoor temperature varied by 10.00%,the average variation rates of such parameters were 85.12%,90.02%,and 64.60%,*** the outdoor temperature was 273.00 K and indoor temperature varied by 50.00%,the average variation rates of such parameters were 83.88%,99.34% and 32.87%,*** can be observed that the energy quality and exergy losses of DH systems can be reduced in the operation process.

关键词： energy quality coefficient exergy loss rate design parameters operating parameters energy conservation measures

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