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Vibration Analysis of a Simply Supported Beam Traversed by Uniform Distributed Moving Load

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上海交通大学学报 2004年第z2期38卷 155-160页

作者： Yu YANG Nian-guan TENG Yian-feng TENG School of Civil Engineering and Mechanics Shanghai Jiaotong Univ. Shanghai200030 China School of Civil Engineering and Mechanics Shanghai Jiaotong Univ. Shanghai200030 China School of Civil Engineering and Mechanics Shanghai Jiaotong Univ. Shanghai200030 China

Considering the engineering background of some transportation system like maglev, vertical vibration of the simply supported beam is investigated. The length of the vehicle is assumed to be longer than the beam span. The model of moving distributed load with constant speed is established .The beam can be taken as Euler-Bernoulli beam model and the right side of the control equation is simplified by using a moving status function. Duhamel integral and mode superposition method is used to solve the dynamic behavior of the beam. In this aspect deflection and acceleration are included. The results of different parameters such as the span of beam, velocity of load and ratio vehicle-Beam masses are compared. All results show that the dynamic response of the beam is tied up with these factors: the frequency of the beam, the moving frequency of the load and the ratio of vehicle-beam mass.

关键词： simply supported seam vertical vibration moving load

Effects of Nitric Oxide on the Quality and Pectin Metabolism of Yali Pears During Cold Storage

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Agricultural Sciences in China 2011年第7期10卷 1125-1133页

作者： LIU Li-qin DONG Yu guan Jun-feng College of Life Science Hebei Normal University Shijiazhuang 050016 P.R.China Institute of Genetics and Physiology Hebei Academy of Agricultural and Forestry Sciences Shijiazhuang 050051 P.R.China

The effect of fumigation with 10, 20, and 30 μL L-1 nitric oxide （NO） was investigated to study the effects of NO on the quality of Yali pears during cold storage. The ethylene production, composition of cell walls, and cell-wall-modifying enzyme activities were measured on fruits which were fumigated with NO （20 μL L-1）. The results showed that NO not only reduced the peak value of ethylene production rate, the soluble sugar, soluble solid content, maintained higher firmness, starch, and NO content, but also retarded the degradation of covalent soluble pectin, accumulation of ionic soluble pectin and water soluble pectin. Moreover, NO fumigation decreased the activities of polygalacturonase （PG） and b-galactosidase（b-Gal） and delayed the peak of PG activity of fruits. Therefore, it indicated that NO fumigation could delay the softening and ripening of Yali pears.

关键词： pear nitric oxide cell wall material fruit softening

Effects of 1-Methylcyclopropene on NO Content,NOS Activity,and H_2O_2 Content in Postharvest Suli Pears

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Agricultural Sciences in China 2011年第5期10卷 797-804页

作者： DONG Yu LIU Li-qin guan Jun-feng Institute of Genetics and Physiology Hebei Academy of Agricultural and Forestry Sciences Shijiazhuang 050051 P.R.China College of Life Science Hebei Normal University Shijiazhuang 050016 P.R.China

Studies were conducted over the effects of 1-methylcycolpropene （1-MCP） treatment on postharvest life of Suli pears （Pyrus bretschneideri Rehd.） stored at room and cold temperatures on nitric oxide （NO）,nitric oxide synthase （NOS） activity,and hydrogen dioxide （H2O2）.Results showed that the 1-MCP treatment had little effect on total soluble solids （TSS） at both room and cold temperatures.1-MCP delayed softening of Suli pear fruits,decreased respiratory rate and H2O2 accumulation,and increased NO and NOS activity at room temperature storage,while the effect of cold temperature storage was relatively *** was a significant positive correlation between NOS activity and NO *** is concluded that 1-MCP had effects on endogenous NO content and accumulation of ***,H2O2 acting as a signaling molecule via regulating NO level affects the ripening and senescence of Suli pears.

关键词： pear 1-MCP NO NOS H2O2

Tissue factor with age-related macular degeneration

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International Journal of Ophthalmology(English edition) 2012年第5期5卷 609-613页

作者： guan-feng Wang Xiu-Lan Zou Department of Ophthalmology Guangzhou General Hospital of Guangzhou Military Command Guangzhou 510010 Guangdong Province China Jinan University Guangzhou 510630 Guangdong Province China

Wet age-related macular degeneration which incidence increases year by year is a blinding eye disease, but current clinical methods of treatment on this disease are limited and the outcome is not ideal. Recent studies have found abnormally high expression of tissue factors which are targets for the treatment of wet age-related macular degeneration to achieve a certain effect in the choroidal neovascularization. Related literatures are reviewed as following.

关键词： wet age-related macular degeneration choroidal neovascularzation tissue factor photodynamic therapy immunotherapy

High-current pulsed electron beam modification on microstructure and performance of Cu/CuW diffusion bonding joints

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Rare Metals 2024年第6期43卷 2819-2831页

作者： Na-Na Tian Cong-Lin Zhang Peng Lyu Jin-Tong guan Jie Cai Qing-feng guan Shun Guo School of Materials Science and Engineering Jiangsu UniversityZhenjiang 212013China School of Material Science and Engineering Yancheng Institute of TechnologyYancheng 221051China Engineering Institute of Advanced Manufacturing and Modern Equipment Technology Jiangsu UniversityZhenjiang 212013China

This study investigates the influence of high-current pulsed electron beam(HCPEB)modification on the microstructure and shear strength of Cu/CuW *** solid-state diffusion bonding of modified-Cu(MCu)and modified-CuW(M-CuW)was achieved by HCPEB modification pretreatment at a temperature of 800-900℃and a pressure of 5 MPa for 10-50 *** demonstrate that HCPEB modification facilitates the dissolution of W and Cu,resulting in the formation of a Cu_(0.4)W_(0.6)solid solution and thus enhancing the uniform distribution of ***,HCPEB-induced defects play a beneficial role in promoting the diffusion process by providing fast diffusion paths for *** optimal joints with the maximum shear strength of 213.7 MPa were obtained through bonding M-Cu and M-CuW at 900℃and 5 MPa for 30 min,which attributes to the combined effects of fine-grained strengthening and solid solution ***,the application of HCPEB modification showcases its effectiveness in promoting element diffusion and enhancing the mechanical performance of the joints.

关键词： HCPEB Element diffusion Shear strength Crystal defects Surface modification

Enhanced mechanical properties of 6082 aluminum alloy via SiC addition combined with squeeze casting

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Journal of Materials Science & Technology 2021年第29期88卷 119-131页

作者： Wenming Jiang Junwen Zhu guangyu Li feng guan Yang Yu Zitian Fan State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China State Key Laboratory of High Performance Complex Manufacturing Central South University410083 ChangshaChina

In order to improve mechanical properties of 6082 aluminum alloy,the SiC_(p)/Al 6082 composites were prepared by the addition of the micron-sized SiC_(p)articles combined with the squeeze *** effects of the SiC_(p)content and squeeze casting on the microstructure and mechanical properties of the 6082 aluminum alloy were investigated by SEM,EDS,TEM,tensile testing and hardness testing analysis *** results exhibited that the SiC_(p)content and squeeze casting had a significant impact on the microstructure and mechanical properties of the 6082 aluminum *** addition of the SiC_(p)refined the grain size of the 6082 aluminum alloy while caused the increase of the porosity with increasing the SiC_(p)content,especially in the permanent mold casting *** to the permanent mold casting,the squeeze casting obviously reduced pore defects,refined grain size and made the SiC_(p)distribute evenly as well as bond tightly with the Al *** tensile strength,yield strength,elongation,elastic modulus and hardness of the 6082 aluminum alloy obtained with the SiC_(p)and squeeze casting were remarkably improved,and the optimal mechanical properties were obtained with a 2 wt.%SiC_(p),and they increased 10.73%,72.7%,193.9%,23.5%and 25.2%,respectively,compared to those of the6082 aluminum alloy obtained without SiC_(p)and squeeze *** fracture surface of the SiC_(p)/Al 6082 composites obtained with the squeeze casting was dense and exhibited a ductile fracture mode.

关键词： 6082 aluminum alloy SiC_(p) Aluminum matrix composites Squeeze casting Microstructure Mechanical properties

Preparation of Material Surface Structure Similarto Hydrophobic Structure of Lotus Leaf

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Journal of Wuhan University of Technology(Materials Science) 2008年第4期23卷 513-517页

作者： CAO feng guan Zisheng LI Dongxu College of Material Science and Engineering Nanjing University of Technology Nanjing 210009 China

Nano/micro replication, a technique widely applied in the microelectronics field, was introduced to prepare the hydrophobic bionics microstructure on material surface. Poly（vinyl alcohol）（PVA） and polystyrene （PS） moulds of the mastoid microstructure on lotus leaf surface were prepared respectively by the nano/micro replication technology. And poly（dimethylsiloxane）（PDMS） replicas with the mastoid-like microstructure were prepared from these two kinds of polymer moulds. Scanning electronic microscope （SEM） was employed to investigate the morphology and microstructures on moulds and replicas. Both the static and dynamic contact angles between water droplet and PDMS replicas＇ surface were also measured. As a result, similar microstructure can be observed clearly on the surface of PDMS replicas and the static contact angle on PDMS replicas was enhanced dramatically by the existence of these microstructures.

关键词： hydrophobic bionics surface structure nano/micro replication

Improving mechanical properties of AZ91D magnesium/A356 aluminum bimetal prepared by compound casting via a high velocity oxygen fuel sprayed Ni coating

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Journal of Magnesium and Alloys 2022年第4期10卷 1075-1085页

作者： guangyu Li Wenming Jiang feng guan Junwen Zhu Yang Yu Zitian Fan State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

In this paper,a Ni coating was deposited on the surface of the A356 aluminum alloy by high velocity oxygen fuel spraying to improve the performance of the AZ91D magnesium/A356 aluminum bimetal prepared by a compound *** effects of the Ni coating as well as its thickness on microstructure and mechanical properties of the AZ91D/A356 bimetal were systematically researched for the first *** demonstrated that the Ni coating and its thickness had a significant effect on the interfacial phase compositions and mechanical properties of the AZ91D/A356 *** 10μm’s Ni coating cannot prevent the generation of the Al-Mg intermetallic compounds(IMCs)at the interface zone of the AZ91D/A356 bimetal,while the Ni coating with the thickness of 45μm and 190μm can avoid the formation of the Al-Mg *** the Ni coating was 45μm,the Ni coating disappeared and transformed into Mg-Mg_(2)Ni eutectic structures+Ni_(2)Mg_(3)Al particles at the interface *** a thickness of 190μm’s Ni coating,part of the Ni coating remained and the interface layer was composed of the Mg-Mg_(2)Ni eutectic structures+Ni_(2)Mg_(3)Al particles,Mg_(2)Ni layer,Ni solid solution(SS)layer,Al_(3)Ni_(2) layer,Al_(3)Ni layer and sporadic Al_(3)Ni+Al-Al_(3)Ni eutectic structures from AZ91D side to A356 side in *** interface layer consisting of the Mg-Ni and Al-Ni IMCs obtained with the Ni coating had an obvious lower hardness than the Al-Mg *** shear strength of the AZ91D/A356 bimetal with a Ni coating of 45μm thickness enhanced 41.4%in comparison with that of the bimetal without Ni coating,and the fracture of the bimetal with 45μm’s Ni coating occurred between the Mg matrix and the interface layer with a mixture of brittle fracture and ductile fracture.

关键词： Magnesium/aluminum bimetal Microstructure Mechanical properties Ni coating Compound casting High velocity oxygen fuel spraying

Microstructure evolution,mechanical properties and fracture behavior of Al-xSi/AZ91D bimetallic composites prepared by a compound casting

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Journal of Magnesium and Alloys 2024年第5期12卷 1944-1964页

In this paper,the effect of the Si content on microstructure evolution,mechanical properties,and fracture behavior of the Al-xSi/AZ91D bimetallic composites prepared by compound casting was investigated *** obtained results showed that all the Al-xSi/AZ91D bimetallic composites had a metallurgical reaction layer(MRL),whose thickness increased with increasing Si content for the hypoeutectic Al-Si/AZ91D composites,while the hypereutectic Al-Si/AZ91D composites were *** MRL included eutectic layer(E layer),intermetallic compound layer(IMC layer)and transition region layer(T layer).In the IMC layer,the hypereutectic Al-Si/AZ91D composites contained some Si solid solution and flocculent Mg_(2)Si+Al-Mg IMCs phases not presented in the hypoeutectic Al-Si/AZ91D ***,increasing Si content,the thickness proportion of the T layer increased,forming an inconsistent preferred orientation of the *** shear strengths of the Al-xSi/AZ91D bimetallic composites enhanced with increasing Si content,and the Al-15Si/AZ91D composite obtained a maximum shear strength of 58.6 MPa,which was 73.4% higher than the Al-6Si/AZ91D *** fractures of the Al-xSi/AZ91D bimetallic composites transformed from the T layer into the E layer with the increase of the Si *** improvement of the shear strength of the Al-xSi/AZ91D bimetallic composites was attributed to the synergistic action of the Mg_(2)Si particle reinforcement,the reduction of oxidizing inclusions and the ratio of Al-Mg IMCs as well as the orientation change of the MRL.

关键词： Al/Mg bimetallic composites Si content Mg_(2)Si reinforcement Microstructure Mechanical properties Fracture behavior