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Preparation of porous polyimide microspheres by thermal degradation of block copolymers

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Particuology 2014年第3期12卷 63-70页

作者： li Wang Jianjun Lu Miaoqing liu li lin Jingjing li Key Laboratory of Coal Science and Technology Taiyuan University of Technology

A new preparation method has been developed for thermally stable porous polyimide microspheres. Porous polyimide microspheres were prepared using trib]ock copolymers that consisted of a thermally stable polyimide derived from pyromellitic dianhydride/4,4＇-oxydianiline as the continuous phase and a thermally labile polyether as the dispersed phase. Spheres of copolymers were generated in a nonaqueous emulsion and then gradually heated to complete the imidization to form a microphase-separated structure. Subsequently, thermal treatment at a slightly reduced pressure removed the labile blocks and produced pores. Under suitable decomposition conditions, the pore size of the porous polyimide was in the range of 200-400nm.

关键词： Block copolymer sphere Microphase separation Polyimide Porous microsphere Porous polymer

SPECIAL SECTION IN MEMORY OF PROFESSOR BRITTON CHANCE

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Journal of Innovative Optical Health Sciences 2011年第2期4卷 I0001-I0003页

作者： lin li Department of Radiology University of Pennsylvania

Britton Chance,an Olympic gold medalist in sailing(Helsinki,1952),was also one of the best and most legendary sailors in *** Chance was born in Wilkes-Barre,Pennsylvania,USA on July 24th,*** received a *** in 1935,an *** 1936 and a *** in Physical Chemistry in 1940,all from the University of *** Cambridge University he received his second *** in Physiology in 1942.

关键词： SPEC Chance Pennsylvania

Effects of Nb on the microstructure and mechanical properties of 38MnB5 steel

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International Journal of Minerals,Metallurgy and Materials 2018年第10期25卷 1181-1190页

作者： li lin Bao-shun li Guo-ming Zhu Yong-lin Kang Ren-dong liu School of Material Science and Engineering University of Science and Technology BeijingBeijing 100083China Ansteel Technology Center Anshan 114009China

The effects of the microalloying element niobium(Nb) on the microstructure and mechanical properties of the hot stamped steel 38 Mn B5 were investigated. The impact of Nb addition on the microstructure was studied through scanning electron microscopy(SEM), transmission electron microscopy(TEM), and X-ray diffraction(XRD). The experimental results indicated that the microstructures of the steel containing Nb were finer than those of the steel without Nb. Moreover, Nb mainly presented as a second-phase particle in 38MnB5 steel, and the particles included Nb carbonitrides. In addition, the tensile strength and elongation of the hot rolled and hot stamped steels were also measured, and they demonstrated that the appropriate addition of Nb was beneficial to the mechanical properties of 38 MnB5. Under the same conditions, the tensile strength of 38 MnB5 Nb was higher than that of 38 MnB5, which increased from 2011 to 2179 MPa. The yield strength also increased from 1316 to 1476 MPa, and the elongation increased from 5.92% to 6.64%. Overall, Nb had a positive effect on the performance of the hot stamped steel.

关键词： hot stamping steel CCT curve microstructure mechanical properties precipitation

Anaerobic oxidation of methane coupled to sulfate reduction: Consortium characteristics and application in co-removal of H_2S and methane

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Journal of Environmental Sciences 2019年第2期31卷 238-248页

作者： lin li Song Xue Jingru Xi State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental SciencesChinese Academy of Sciences National Engineering Laboratory for VOCs Pollution Control Material & Technology University of Chinese Academy of Sciences State Key Laboratory of Applied Microbiology Southern China Guangdong Institute of MicrobiologyGuangdong Academy of Sciences

Anaerobic sludge from a sewage treatment plant was used to acclimatize microbial colonies capable of anaerobic oxidation of methane(AOM) coupled to sulfate reduction. Clone libraries and fluorescence in situ hybridization were used to investigate the microbial ***-reducing bacteria(SRB)(e.g., Desulfotomaculum arcticum and Desulfobulbus propionicus)and anaerobic methanotrophic archaea(ANME)(e.g., Methanosaeta sp. and Methanolinea sp.)coexisted in the enrichment. The archaeal and bacterial cells were randomly or evenly distributed throughout the consortia. Accompanied by sulfate reduction, methane was oxidized anaerobically by the consortia of methane-oxidizing archaea and SRB. Moreover, CH_4 and SO_4^(2-) were consumed by methanotrophs and sulfate reducers with CO_2 and H_2S as products. The H_3CSH produced by methanotrophy was an intermediate product during the process. The methanotrophic enrichment was inoculated in a down-flow biofilter for the treatment of methane and H_2S from a landfill site. On average, 93.33% of H_2S and 10.71% of methane was successfully reduced in the biofilter. This study tries to provide effective method for the synergistic treatment of waste gas containing sulfur compounds and CH_4.

关键词： Anaerobic methane oxidation Sulphate reduction Microbial population 13C isotope-labelling Potential pathway Landfill gas

Characterization of the airborne bacteria community at different distances from the rotating brushes in a wastewater treatment plant by 16S rRNA gene clone libraries

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Journal of Environmental Sciences 2013年第1期25卷 5-15页

作者： Yunping Han lin li Junxin liu Department of Water Pollution Control Technology Research Center for Eco-Environmental SciencesChinese Academy of Sciences

Biological risks of bioaerosols emitted from wastewater treatment processes have attracted wide attention in the recent years. However, the culture-based analysis method has been mostly adopted for detecting the bacterial community in bioaerosols, which may result in the underestimation of total microorganism concentration as not all microorganisms are cultivable. In this study, oligonucleotide fingerprinting of 16S rRNA genes was applied to reveal the composition and structure of the bacterial community in bioaerosols from an Orbal oxidation ditch in a Beijing wastewater treatment plant （WWTP）. Bioaerosols were collected at different distances from the aerosol source, rotating brushes, and the sampling height was 1.5 m which is the common respiratory height of a human being. The bacterial communities of bioaerosols were diverse, and the lowest bacterial diversity was found at the sampling site just after the rotating brush rotating brush. A large proportion of bacteria in bioaerosols were affiliated with Proteobacteria and Bacteroidetes. Numerous bacteria present in the bioaerosols also emerged in water, indicating that the bacterial community in the bioaerosols was related to that of the aerosols＇ sources. The forced aeration of rotating brushes brought about observably distinct bacterial communities between sampling sites situated before and after the rotating brush. Isolation sources of closest relatives in bioaerosols clone libraries were associated with the aqueous environment in the WWTP. Common potential pathogens in bioaerosols as well as those not reported in previous research were also analyzed in this study. Measures should be adopted to reduce the emission of bioaerosols and prevent their exposure to workers.

关键词： airborne bacteria genetic structure clone library wastewater treatment plant rotating brushes

Packet： a privacy-aware access control policy composition method for services composition in cloud environments

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Frontiers of Computer Science 2016年第6期10卷 1142-1157页

作者： li lin Jian HU Jianbiao ZHANG College of Computer Science Beijing University of Technology Beijing 100124 China Beijing Key Laboratory of Trusted Computing Beijing 100124 China National Engineering Laboratory for Classified Information Security Protection Beijing 100124 China

Combining different independent cloud services must coordinate their access control policies. Otherwise unauthorized access to composite cloud service can occur when there＇s a conflict among different cloud service providers＇ access control policies, and then it will bring serious data security and privacy issues. In this paper, we propose Packet, a novel access control policy composition method that can detect and resolve policy conflicts in cloud service composition, including those conflicts related to privacyaware purposes and conditions. The Packet method is divided into four steps. First, employing a unified description, heterogeneous policies are transformed into a unified attributebased format. Second, to improve the conflict detection ef- ficiency, policy conflicts on the same resource can be eliminated by adopting cosine similarity-based algorithm. Third, exploiting a hierarchical structure approach, policy conflicts related to different resources or privacy-aware purposes and conditions can be detected. Fourth, different conflict resolution techniques are presented based on the corresponding conflict types. We have successfully implemented the Packet method in Openstack platform. Comprehensive experiments have been conducted, which demonstrate the effectiveness of the proposed method by the comparison with the existing XACML-based system at conflict detection and resolution performance.

关键词： cloud service composition access control privacy policy composition unified policy format conflict detection similarity analysis conflict resolution

Performance of two biofilters with neutral and low pH treating off-gases

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Journal of Environmental Sciences 2008年第12期20卷 1409-1414页

作者： liU Jianwei liU Junxin li lin Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China

Two different functional biofilters were carried out and compared for the treatment of off-gas containing multicomponent odors and volatile organic compounds (VOCs) in this study. The effects of pH values and the empty bed retention time (EBRT) on the performance of the bioreactors were studied; and the characteristics of microbial populations in the two biofilters were also determined. The experimental results indicated that the removal effciencies of hydrophilic compounds such as butyric acid and ammonia ...

关键词： waste gas treatment biofiltration VOCs and odors bacteria fungi

Dynamic characteristics of a cyclic-periodic structure with a piezoelectric network

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Chinese Journal of Aeronautics 2015年第5期28卷 1426-1437页

作者： li lin Deng Pengcheng Fan Yu School of Energy and Power Engineering Beihang University Collaborative Innovation Center for Advanced Aero-Engine Laboratoire de Tribologie et Dynamique des Systemes Ecole Centrale de Lyon – 36Avenue Guy de Collongues Ecully 69134 France

This paper deals with a cyclic-periodic structure with a piezoelectric network. In such a system, there is not only mechanical connection but also electrical connection between adjacent periodic sectors. The objective is to learn whether the presence of a piezoelectric network would change the dynamic characteristics of the system. The background of the research is about vibration reduction of a bladed disk in an aero-engine, and the system is simulated by a lumped parameter model. The dynamic equations of the system are derived, and then the analytical solution corresponding to the eigenvalue problem is given. The vibration responses to single traveling wave excitations （EO excitations） and multiple traveling wave excitations （NEO excitations） are studied. The results show that the presence of a piezoelectric network would change the natural frequencies of the system compared with those of the system with the piezoelectric shunt circuit. The forced response is sensitive to the connection type and the elements of the network. An energy analysis of the electro-mechanical coupling system has been performed to understand its dynamic behavior, and the following conclusion is obtained： a vibration reduction to excitations whose primary har- monic component is not zero can be achieved by a parallel piezoelectric network, while a reduction to other excitations should be based on a series piezoelectric network.

关键词： Cyclic-periodic structures Electro-mechanical dynamicbehavior Energy analysis Piezoelectric networks Vibration reduction

Solution to Stochastic LQR Problem with Multiple Inputs

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Journal of Systems Science & Complexity 2017年第3期30卷 568-578页

作者： XU Juanjuan li lin ZHANG Huanshui School of Control Science and Engineering Shandong UniversityJinan 250061China.

This paper considers the stochastic linear quadratic regulation （LQR） problem for Ito stochastic systems with multiple input controllers. The explicit controllers are given in terms of two Riccati equations by introducing one new costate and establishing the homogeneous relationship be- tween the state and the new costate. More importantly, it is more computation saving for the derived Riccati equations than the one derived by augmentation technique.

关键词： Ito stochastic system multiple inputs Riccati equation stochastic LQR.