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Nonlinear flutter analysis of stiffened composite panels in super-sonic flow

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science china(Physics,Mechanics & Astronomy) 2010年第2期53卷 336-344页

作者： yuAN KaiHua & QIU zhiping school of Aeronautic science and engineering,beijing university of Aeronautics and Astronautics,beijing 100191,china 1. school of Aeronautic science and engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China

The flutter instability of stiffened composite panels subjected to aerodynamic forces in the supersonic flow is investigated. Based on Hamilton's principle,the aeroelastic model of the composite panel is established by using the von Karman large deflection plate theory,piston theory aerodynamics and the quasi-steady thermal stress theory. Then,using the finite element method along with Bogner-Fox-Schmit elements and three-dimensional beam elements,the nonlinear equations of motion are derived. The effect of stiffening scheme on the flutter critical dynamic pressure is demonstrated through the numerical example,and the nonlinear flutter characteristics of stiffened composite panels are also analyzed in the time domain. This will lay the foundation for design of panel structures employed in aerospace vehicles.

关键词： panel flutter piston theory finite element method quasi-steady thermal stress critical dynamic pressure stiffened composite panel

Flexible, thermal processable, self-healing, and fully bio-based starch plastics by constructing dynamic imine network

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Green Energy & Environment 2024年第10期9卷 1610-1618页

作者： Xiaoqian Zhang Haishan Zhang Guowen Zhou zhiping Su Xiaohui wang State Key Laboratory of Pulp and Paper engineering South China University of Technology

The serious environmental threat caused by petroleum-based plastics has spurred more researches in developing substitutes from renewable *** is desirable for fabricating bioplastic due to its abundance and renewable ***,limitations such as brittleness,hydrophilicity,and thermal properties restrict its widespread *** overcome these issues,covalent adaptable network was constructed to fabricate a fully bio-based starch plastic with multiple advantages via Schiff base *** strategy endowed starch plastic with excellent thermal processability,as evidenced by a low glass transition temperature （Tg=20.15℃）.Through introducing Priamine with long carbon chains,the starch plastic demonstrated superior flexibility （elongation at break=45.2%） and waterproof capability （water contact angle=109.2°）.Besides,it possessed a good thermal stability and self-adaptability,as well as solvent resistance and chemical *** work provides a promising method to fabricate fully bio-based plastics as alternative to petroleum-based plastics.

关键词： Bioplastic Covalent adaptable networks Schiff base chemistry Thermal processability Self-healing

Molecular mechanism of dehydrin in response to environmental stress in plant

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Progress in Natural science:Materials International 2007年第3期17卷 237-246页

作者： ZHANG yuxiu , wang Zi and XU Jin (Department of Bioengineering, school of Chemical and environmental engineering, china university of Mining and technology (beijing), beijing 100083, china Department of Biology, Graduate university of Chinese Academy of sciences, beijing 100049, china) [a]Department of Bioengineering School of Chemical and Environmental Engineering China University of Mining and Technology (Beiing) Beijing China [b]Department of Biology Graduate University of Chinese Academy of Sciences Beijing China

Dehydrins, known as the D-11 subgroup of late embryogenesis abundant (LEA) protein, are an immunologically distinct family of proteins, which typically accumulate in desiccation-tolerant seed embryo or in vegetative tissues in response to various environmental stresses such as drought, salinity and freezing. The existence of conservative sequences designated as K, S, and Y segments is a structural feature of dehydrins, and the K segment found in all dehydrins represents a highly conserved 15 amino acid motif (EKKGIMDKIKEKLPG) and forms an amphiphilicα-helix. According to the arrangement of these domains and clustering analysis, dehydrins are subdivided into 5 subtypes: YnSK, Kn, KnS, SKn and YnK. Different types of dehydrins are induced by different environmental stress in plants. Study results showed that dehydrins might play important protective roles under abiotic stress via a number of different mechanisms, including improving or protecting enzyme activities by the cryoprotective activity in responding to freeze/thaw or dehydration; stabilizing vesicles or other endomembrane structures by function as the membrane stabilizer during freeze induced dehydration, and preventing the membrane system from the oxidative damage induced by reactive oxygen radicals as the radical scavenger. Here, the gene expression and molecular mechanisms of dehydrin in response to stress in plants are discussed.

关键词： dehydrin stress mechanism.

Global optimization of double protograph LDPC codes for JSCC scheme

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science china(Information sciences) 2024年第6期67卷 455-456页

作者： Qiwang CHEN Chen CHEN yu-Cheng HE zhiping XU Xiamen Key Laboratory of Mobile Multimedia Communications College of Information Science and EngineeringHuaqiao University Key Laboratory of Underwater Acoustic Communication and Marine Information technology (Xiamen university) Ministry of Education school of Ocean Information engineering Jimei University

A double low-density parity-check (D-LDPC) coding system was proposed in[1]as a typical joint source-channel coding(JSCC) scheme[1–5].In this system,two LDPC coding matrices perform source and channel coding,*** important concept in a D-LDPC coding system is the introduction of a linking matrix between the check nodes (CNs)of the source coding matrix and the variable nodes (VNs) of the channel LDPC coding matrix.

关键词： JOINT SOURCE DESIGN

Photocatalytic degradation of formaldehyde by diffuser of solar light pipe coated with nanometer titanium dioxide thin films

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science china(Technological sciences) 2010年第1期53卷 150-154页

作者： WU YanPeng1,ZHANG WenMing1,MA ChongFang2,LU yuanWei2 & LIU Li1 1 school of Civil and environmental engineering,university of science and technology beijing,beijing 100083,china 2 College of environmental and Energy engineering,beijing university of technology,beijing 100022,china 1. school of Civil and environmental engineering University of Science and Technology Beijing Beijing 100083 China2. College of Environmental and Energy Engineering Beijing University of Technology Beijing 100022 China

The even and transparent nanometer TiO2 thin films named DegussaP25 as photocatalysis deposited on the surface of diffusers of solar light pipe were prepared by sol-gel *** rugged side of the diffusers of solar light pipe was coated evenly with DegussaP25 solution for the quality of 1.75 *** experiments had showed that when the coated side was away from the sun the lighting degree may be reduced compared with that facing the *** average reduction was only 3.03%,which would not have a significant impact on *** are important parts of a light pipe which can diffuse light evenly to the place needed to be *** experiments showed that in a sunny summer day under the direct sunlight,the solar light pipe combined with photocatalysis could reduce the formaldehyde volume fraction in a box of 0.1 m3 from 1.0×10-6 to 0.16×*** 1 h of photodegradation the formaldehyde volume changed from 1.0×10-6 down to 0.1×10-6 with faster and more complete degradation of *** rate of degradation under cloudy and partly cloudy conditions was slower than that under sunny *** was slower in winter than in summer under sunny *** experimental results also showed that the performance of photocatalysis combined with diffusers of light pipe had better effect in a small *** performance in large space,such as open space,will be the next work in the future,which will be a great challenge.

关键词： solar light pipes diffusers photocatalysis decomposition formaldehyde titanium dioxide

Recovery of Level Pillar between Open-pit and Underground Mine by Using Underhand Heading Fill Method

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Journal of university of science and technology beijing 2001年第4期8卷 244-247页

作者： Sijing Cai, Hai Zhao,Shangjun Ying 1) Civil and environmental engineering school, university of science and technology beijing, beijing 100083, china 2)Fujia Mine, him Nickel Corporation, Jilin 132311, china Univ Sci & Technol beijing Sch Civil & Environm Engn Beijing 100083 Peoples R China Jilin Nickel Corp Fujia Mine Jilin 132311 Peoples R China

The upper part of the Fujia deposit was mined out by open-pit, and the lower part is being mined underground. The level pillar between open-pit and underground mine had a thickness of 24 m, a length of 300 m and a maximum width of 35 in. As the level pillar contained about 5.2 million ton ore of high nickel grade, it was necessary to recover the level pillar. Because of special need of safety, underhand heading cut-and-fill stoping method was used. For the first two layers of heading, the cemented fill materials were a mix of water and high-aluminum-content cement with silicate gelling agent; and for other heading layers, total tailings was added into the fill mix in order to reduce the cement consumption. Finally, the level pillar was recovered successfully.

关键词： level pillar underhand heading method fill materials with silicate gelling agent

Thermal Stability and Strengthening Effect of Coherent Precipitates in a (FeCoNi)_(92)Al_(2.5)Ti_(5.5) High Entropy Alloy

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Acta Metallurgica Sinica(English Letters) 2024年第9期37卷 1491-1500页

作者： yuqi Liu Feng wang Songyang Chen Hui wang zhiping Xiong Khurram Yaqoob Zhangwei wang Min Song tate Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083China State Key Laboratory for Advance Metals and Materials University of Science and Technology BeijingBeijing100083China National Key Laboratory of science and technology on Materials Under Shock and Impact Beijing100081China school of Chemical and Materials engineering National University of Sciences and TechnologyH-12Islamabad44000Pakistan

The coarsening behavior and strengthening effect of L1_(2)-Ni_(3)(Ti,Al)precipitates in a face-centered-cubic(FCC)(FeCoNi)_(92)Al_(2.5)Ti_(5.5) high entropy alloy have been systematically *** coherent L1_(2) precipitates,uniformly distributed throughout the FCC matrix,consistently retain a spherical *** coarsening rate coefficient of precipitate is determined by employing the Philippe-Voorhees(PV)model,suggesting excellent thermal ***,the elemental partitioning and compositional evolution of the L1_(2) precipitates is analyzed by atom probe tomography,which identify aluminum(Al)as the slowest diffusion species during the coarsening *** addition,the precipitation strengthening effect is quantified to ascertain the optimal size of the *** study enhances the understanding of precipitate coarsening in high entropy alloys,presenting valuable insights into their thermal stability and mechanical properties.

关键词： High entropy alloy L1_(2)precipitates Coarsening kinetics Precipitation hardening

The Self-assembling and Application of Inorganic Anti-bacterial Material Made of Natural Nanoporous Carrier

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Journal of Wuhan university of technology(Materials science) 2008年第6期23卷 771-774页

作者：孙春宝 school of Civil and environmental engineering University of Science and Technology Beijing

The inorganic antimicrobial material was inhibited to the microbes with the added metal ion,*** primary wet product carrying 5%-10% zinc ion was generated under the following conditions：temperature was 95 ℃,solution zinc concentration was 1.2-2.0 mol/L,and the ratio of Zn solution to zeolite weight was 5：*** final stable product was manufactured after baking in an oven for 1-3 h at the temperature of 500-900 ℃.The baked material was tested for its disinfection effectiveness and coloring effect when mixed with paint *** on the final batch of tests,the zinc content of this anti-microbial product was further optimized.

关键词： inorganic antimicrobial nanoporous material antibacterial coating zeolite self-assembling

Process optimization of reaction of acid leaching residue of asbestos tailing and sodium hydroxide aqueous solution

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science china(Technological sciences) 2009年第1期52卷 204-209页

作者： DU GaoXiang1,3, ZHENG ShuiLin2 & DING Hao1 1 school of Materials science and technology, china university of Geosciences (beijing), beijing, 100083, china 2 school of Chemical and Environment engineering, china university of Mining and technology (beijing), beijing 100083, china 3 Hebei Qinghe Refractory Group Co. Ltd., Xingtai 054804, china 1. school of Materials science and technology China University of Geosciences (Beijing) Beijing 100083 China 3. Hebei Qinghe Refractory Group Co. Ltd. Xingtai 054804 China 2. school of Chemical and Environment engineering China University of Mining and Technology (Beijing) Beijing 100083 China

Silica is the major component of the acid leaching residue of asbestos tailing. The waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous solution. Compared to the high temperature reaction method, this process is environmental friendly and low cost. In this paper, the reaction process of the residue and the sodium hydroxide aqueous solution is optimized. The optimum reaction process parameters are as follows: the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue, the reaction temperature is 90℃, the reaction time is 1 h, and the ratio of the liquid/solid is 2.0. The significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide > the ratio of the liquid/solid > the reaction time > the reaction temperature. The significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. The significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. Under the optimum conditions, the leaching ratio of the SiO2 is 77.5%, and the modulus of the sodium silicate is 3.15. The XRD analysis result indicates that the major components of the alkali leaching residue are serpentine, talc, quartz and some albite.

关键词： asbestos tailing acid leaching residue sodium hydroxide process optimization