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ELASTIC-PLASTIC DYNAMIC RESPONSE OF A CANTILEVER BEAM SUBJECTED TO OBLIQUE IMPACT AT ITS TIP

Acta Mechanica Solida Sinica 2005年第4期18卷 316-325页

作者： xi Feng liu Feng Shandong Institute of Architecture and Engineering Jinan 250101 China

By employing large deformation governing equations expressed in the form of finite difference, the dynamic responses of an elastic, perfectly plastic cantilever subjected to an oblique impact at its tip was numerically studied. Through analyzing the instantaneous distribution of the yield function （φ = ｜M/Mo｜＋（N/No）^2）, bending moment and axial force during the early stage of the response, the elastic-plastic deformation mechanism and the influence of axial component of an oblique impact on the dynamic response of a cantilever beam were discussed. The present analysis shows that the deformation mechanism of an elastic-plastic cantilever subjected to an oblique impact consists of four phases, i.e. ‘the expanding compressed plastic region＇ mode; the ‘generalized traveling plastic hinge＇ and ‘shrinking plastic region＇ mixed mode; the ‘stationary plastic hinge＇ mode and ‘elastic vibration＇ mode. Compared with the two-phase deformation mode obtained by using the rigid, perfectly plastic approach, the mode of shrinking plastic region that occurred instantly after the oblique impact and the mode of stationary hinge were both confirmed. The primary features of the deformation mechanism are captured by both analysis methods. It has also been found that the beam＇s deformation is mainly controlled by the axial component of the oblique impact in the early phase of the dynamic response, the deformation mechanism is obviously different from the case of a transverse impact. With further development of the response, the axial component attenuates rapidly and gives negligible contribution to the yielding of the beam cross-section. At the same time, the bending moments along the cantilever develop gradually and dominate the beam＇s deformation. The numerical results indicate that the mass, impact speed and oblique angle are the important factors that influence the elastic-plastic dynamic response of a cantilever beam.

关键词： oblique impact elastoplasticity large deformation dynamic response cantilever

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Cyclic Group Action of Composite Order on Indefinite 4-manifolds

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Communications in Mathematical Research 2011年第3期27卷 200-206页

作者： LI hong-xiA liu xi-MIN Department of Applied Mathematics Shanghai Maritime University Shanghai 201306 Department of Mathematics South China University of Technology Guangzhou 510641

In this paper, we study the possibilities for several kinds of topological, locally linear cyclic group actions of non-prime order on some closed, simply connected 4-manifolds with indefinite intersection form. Especi... 详细信息

关键词： periodic map 4-manifold indefinite permutation representation

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ZIF-derived holey electrode with enhanced mass transfer and N-rich catalytic sites for high-power and long-life vanadium flow batteries

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Journal of Energy Chemistry 2022年第9期31卷 545-553,I0015页

作者： Yongbin liu Lihong Yu xin liu Le liu Jingyu xi Institute of Materials Research Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055GuangdongChina School of Materials&Environmental Engineering Shenzhen PolytechnicShenzhen 518055GuangdongChina

Electrode materials with good redox kinetics,excellent mass transfer characteristics and ultra-high stability play a crucial role in reducing the life-cycle cost and prolonging the maintenance-free time of the vanadium flow batteries(VFB).Herein,a nitrogen-doped porous graphite felt electrode(N-PGF)is proposed by growing ZIF-67 nanoparticles on carbon fibers and then calcinating and acid *** multi-scale structure of“carbon fiber gap(electrolyte flow),micro/nano pore(active species diffusion)and Nitrogen active center(reaction site)”in N-PGF electrode effectively increases the catalytic sites and promotes mass transfer *** electrode design makes the battery show excellent rate performance and ultra-high cycling *** peak power density of the battery reaches 1006 mW cm^(-2).During 1000 cycles at 150 mA cm^(-2),the average discharge capacity and average discharge energy of N-PGF increase substantially by 11.6%and 23.4%compared with the benchmark thermal activated graphite felt,*** excitingly,after ultra-long term(5000 cycles)operation at an ultra-high current density(300 mA cm^(-2)),N-PGF exhibits an unprecedented energy efficiency retention(99.79%)and electrochemical performance stability.

关键词： Vanadium flow battery Multi-scale pore electrode Graphite felt Nitrogen-doping Cycling stability

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Novel mutations in LRRC23 cause asthenozoospermia in a nonconsanguineous family

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Asian Journal of Andrology 2024年第5期26卷 484-489页

作者： Song-xi Tang Si-Yu liu hong xiao xin Zhang Zhuang xiao Shan Zhou Yi-Lang Ding Peng Yang Qiang Chen Hai-Lin Huang xi Chen xi Lin Hui-Liang Zhou Ming-xi liu Department of Andrology and Sexual Medicine First Affiliated Hospital of Fujian Medical UniversityFuzhou 350005China State Key Laboratory of Reproductive Medicine and Offspring Health The Affiliated Taizhou People’s Hospital of Nanjing Medical UniversityTaizhou School of Clinical MedicineNanjing Medical UniversityNanjing 211166China State Key Laboratory of Reproductive Medicine and Offspring Health Department of Histology and EmbryologySchool of Basic Medical SciencesNanjing Medical UniversityNanjing 211166China Public Technology Service Center Fujian Medical University Fuzhou 350108China

The cause of asthenozoospermia(AZS)is not well understood because of its complexity and *** some gene mutations have been identified as contributing factors,they are only responsible for a small number of *** spokes(RSs)are critical for adenosine triphosphate-driven flagellar beating and axoneme stability,which is essential for flagellum *** this study,we found novel compound heterozygous mutations in leucine-rich repeat-containing protein 23(LRRC23;c.1018C>T:p.Q340X and c.881_897 Del:p.R295Gfs*32)in a proband from a nonconsanguineous family with AZS and male ***-Quik staining and scanning electron microscopy revealed no abnormal sperm *** blotting and immunofluorescence staining showed that these mutations suppressed LRRC23 expression in sperm ***,transmission electron microscopy showed the absence of RS3 in sperm flagella,which disrupts stability of the radial spoke complex and impairs *** in vitro fertilization and embryo transfer,the proband’s spouse achieved successful pregnancy and delivered a healthy *** conclusion,our study indicates that two novel mutations in LRRC23 are associated with AZS,but successful fertility outcomes can be achieved by in vitro fertilization-embryo transfer techniques.

关键词： asthenozoospermia LRRC23 male infertility whole exome sequencing

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Application of the Binary Bell Polynomials Method to the Dissipative(2+1)-Dimensional AKNS Equation

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Chinese Physics Letters 2012年第12期29卷 1-4页

作者： liu Na liu xi-Qiang Business School Shandong University of Political Science and LawJinan 250014 School of Mathematical Sciences Liaocheng UniversityLiaocheng 252059

Based on the binary Bell polynomials,the bilinear representation,bilinear B?cklund transformation and the Lax pair for the dissipative(2+1)-dimensional Ablowitz-Kaup-Newell-Segur(AKNS)equation are ***,the infinite con... 详细信息

关键词： bilinear AKNS infinite

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Fe/S oxidation-coupled arsenic speciation transformation mediated by AMD enrichment culture under different pH conditions

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Journal of Environmental Sciences 2024年第3期137卷 681-700页

作者： Yu-hang Zhou Wei-xi Huang Zhen-yuan Nie hong-chang liu Yue liu Can Wang Jin-lan xia Wen-sheng Shu Key Lab of Biometallurgy of Ministry of Education of China School of Minerals Processing and BioengineeringCentral South UniversityChangsha 410083China School of Life Sciences South China Normal UniversityGuangzhou 510631China

Arsenic(As)speciation transformation in acid mine drainage(AMD)is comprehensively affected by biological and abiotic factors,such as microbially mediated Fe/S redox reactions and changes in environmental conditions(pH and oxidation-reduction potential).However,their combined impacts on arsenic speciation transformation remain poorly ***,we explored arsenic transformation and immobilization during pyrite dissolution mediated by AMD enrichment culture under different acidic pH *** results for incubation and mineralogical transformation of solid residues show that in the presence of AMD enrichment culture,pH 2.0,2.5,and 3.0 are more conducive to the formation of jarosites and ferric arsenate,which could immobilize high quantities of dissolved arsenic by adsorption and *** pH conditions significantly affect the initial adsorption of microbial cells to the minerals and the evolution of microbial community structure,further infuencing the biodissolution of pyrite and the release and oxidation process of Fe/*** results of Fe/S/As speciation transformation of the solid residues show that the transformation of Fe,S,and As in solution is mainly regulated by pH and potential values,which imposed significantly different effects on the formation of secondary minerals and thus arsenic oxidation and *** above results indicated that arsenic transformation is closely related to the Fe/S oxidation associated with pyrite bio-oxidation,and this correlation is critically regulated by the pH conditions of the system.

关键词： Acid mine drainage(AMD) pH conditions Fe/S/As speciation transformation Microbial community structure

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Population suppression of Bemisia tabaci （Hemiptera： Aleyrodidae） using yellow sticky traps and Eretmocerus nr. rajasthanicus （Hymenoptera： Aphelinidae） on tomato plants in greenhouses

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Insect Science 2008年第3期15卷 263-270页

作者： xi-Shu Gu Wen-Jun Bu Wei-hong Xu Yi-Chuan Bai Bai-Ming liu Tong-xian liu Coflege of Life Science Nankai University Tianjin China Institute of Plant Protection Tianjin Academy of Agricultural Science Tianjin China Department of Entomology Texas AgriLife Research Texas A&M University System Weslaco Texas 78596 USA

We conducted three experiments for management of Bemisia tabaci （Gennadius） biotype＇ B＇ on tomatoes under greenhouse conditions：（i） vertically placing yellow sticky cards either parallel or perpendicular to tomato rows at a rate of 1 per 3-m row; （ii） releasing Eretmocerus sp. nr. rajasthanicus once at 30 adults/m2 in the high whitefly density greenhouses （〉 10 adults/plant）, or twice at 15 adults/m2 at a 5-day interval in the low whitefly density greenhouses （〈 10 adults/plant）; and （iii） using combinations of yellow sticky cards that were placed vertically parallel to tomato rows and parasitoids released once at 30/m2 in high whitefly density greenhouses or twice at 15/m2 at a 5-day interval in low whitefly density greenhouses. Our data show that yellow sticky cards trapped B. tabaci adults and significantly reduced whitefly populations on tomato. The yellow sticky cards that were placed parallel to tomato rows caught significantly more whitefly adults than those placed perpendicular to tomato rows on every sampling date. In the treatment where parasitoids were released once at 30/m2 in high whitefly density greenhouses, the number of live whitefly nymphs were reduced from 4.6/leaf to 2.9/leaf in 40 days as compared with those on untreated plants on which live whitefly nymphs increased from 4.4/leaf to 8.9/leaf. In the treatment where parasitoids were released twice at 15/m2 in low whitefly density greenhouses, the numbers of live nymphs ofB. tabaci on tomato leaves were reduced from 2.1/leaf to 1.7/leaf in 20 days as compared with those on untreated plants on which numbers of live nymphs ofB. tabaci increased from 2.2/leaf to 4.5/leaf. In the treatment of yellow sticky cards and parasitoid release once at 30/m2 in high whitefly density greenhouses, the numbers of live nymphs of B. tabaci on tomato leaves were reduced from 7.2/leaf to 1.9/leaf, and in the treatment of yellow sticky cards and parasitoid release twice at 15/m2 at a 5-day interval at low whitefly de

关键词： greenhouses parasitoids physical control sweetpotato whitefly yellowsticky cards

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D0_(22) precipitates strengthened W-Ta-Fe-Ni refractory high-entropy alloy

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Journal of Materials Science & Technology 2024年第10期177卷 85-95页

作者： Tong Li Jin-xi Chen Tian-Wei liu Yan Chen Jun-Hua Luan Zeng-Bao Jiao Chain-Tsuan liu Lan-hong Dai State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 101408China Inter-University 3D Atom Probe Tomography Unit Department of Materials Science and EngineeringCity University of Hong KongHong KongChina Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHong KongChina

Refractory high-entropy alloys have recently emerged as promising candidates for high-temperature structural ***,their performance is compromised by the trade-off required between strength and ***,a novel W30Ta5(FeNi)65 refractory high-entropy alloy with an outstanding combination of strength and plasticity at both room and elevated temperatures is designed,based on the multi-phase transitions design *** alloy comprises a body-centered cubic dendrite phase,a topologically close-packed μ rhombohedral phase,and a high-density coherent nano-precipitate γ"phase with the D0_(22)structure(Ni3Ta type)embedded in a continuous face-centered cubic *** to pre-cipitation strengthening of D0_(22),the yield stress of the alloy is determined as high as 1450 MPa,which is a significant improvement(~100%)in comparison with the D0_(22)-free alloy,without a loss of *** alloy exhibits an excellent high-temperature strength,with the yield strengths of 1300 MPa at 600 ℃ and 320 MPa at 1000 ℃.Detailed microstructural characterization using transmission electron mi-croscopy,high-angle annular dark-field imaging,and three-dimensional atom probe tomography analyses indicated that this superior strength-plasticity combination stems from the synergy of a multiple-phase *** results provide a new insight into the design of RHEAs and other advanced alloys.

关键词： Refractory high entropy alloy Multi-phase structure D0_(22)superlattice Precipitation strengthening

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Ultrahigh Performance Triboelectric Nanogenerator Enabled by Charge Transmission in Interfacial Lubrication and Potential Decentralization Design

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Research 2022年第4期2022卷 519-529页

作者： Wencong He Wenlin liu Shaoke Fu Huiyuan Wu Chuncai Shan Zhao Wang Yi xi Xue Wang Hengyu Guo hong liu Chenguo Hu School of Physics State Key Laboratory of Power Transmission Equipment and System Security and New TechnologyChongqing UniversityChongqing 400044China State Key Laboratory of Crystal Materials Shandong UniversityJinan 250100China

Triboelectric nanogenerator (TENG) is a promising strategy for harvesting low frequency mechanical energy. However, the bottlenecks of limited electric output by air/dielectric breakdown and poor durability by material abrasion seriously restrict its further improvement. Herein, we propose a liquid lubrication promoted sliding mode TENG to address both issues. Liquid lubrication greatly reduces interface material abrasion, and its high breakdown strength and charge transmission effect further enhance device charge density. Besides, the potential decentralization design by the voltage balance bar effectively suppresses the dielectric breakdown. In this way, the average power density up to 87.26 W·m^(-2)·Hz^(-1), energy conversion efficiency of 48%, and retention output of 90% after 500,000 operation cycles are achieved, which is the highest average power density and durability currently. Finally, a cell phone is charged to turn on by a palm-sized TENG device at 2 Hz within 25 s. This work has a significance for the commercialization of TENG-based self-powered systems.

关键词： durability dielectric generator

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The Switching Fractional Order Chaotic System and Its Application to Image Encryption

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IEEE/CAA Journal of Automatica Sinica 2017年第2期4卷 381-388页

作者： Jialin Hou Rui xi Ping liu Tianliang liu Shandong Key Laboratory of Gardening Machinery and Equipment College of Mechanical and Electrical EngineeringAgricultural University of Shandong School of Computer Science and Technology Dalian University of Technology Department of Mechanical and Electronic Engineering Taishan Vocational and Technical College

Many studies on fractional order chaotic systems and secure communications have been carried out, however, switching fractional order chaotic system and its application to image encryption have not been explored yet. In this paper, a new switching fractional order chaotic system is proposed, containing fractional order Chen system and the other two fractional order chaotic systems. Chaotic attractors and dynamical analysis including Lyapunov exponent, bifurcation diagram, fractal dimension, dissipation, stability and symmetry are shown firstly. After that, some circuit simulations through Multisim are presented. By controlling switch k U+2082 and k U+2083, switching among the three fractional order chaotic subsystems can be realized. Finally, we apply the switching fractional order chaotic system to image encryption using exclusive or U+0028 XOR U+0029 encryption algorithm. The encryption scheme could increase randomness and improve speed of encryption. © 2017 Chinese Association of Automation.

关键词： Circuit simulation Cryptography Fractal dimension Image processing Lyapunov methods Switching

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