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RISS 인기검색어
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- 저자 : Lifeng Zheng (검색결과 6 건)
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Distributed Optimization over General Directed Networks with Random Sleep Scheme
Zheng Wang,Lifeng Zheng,Huaqing Li 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.10
Distributed optimization aims at optimizing a global objective function which is described by a sum of local objective functions through local information processing and sharing. This paper studies the problem of distributed optimization over a network in which underlying graph is generally directed strongly connected. Most existing distributed algorithms require each agent to observe the gradient of the local objective function per iteration, which leads to heavy computational cost. A computation-efficient distributed optimization algorithm incorporating a random sleep scheme is proposed by incorporating a rescaling gradient technique to address the unbalancedness of the directed graph. The implementation of the proposed algorithm allows agents not only locally allocates the weights on the received information, but also independently decides whether to execute gradient observation at each iteration. Theoretical analysis verifies that the proposed algorithm is able to seek the optimal solution with probability one. Simulations are shown to demonstrate the effectiveness of the proposed algorithm, show correctnessof the theoretical analysis, and investigate the tradeoffs between convergence performance and computation cost.
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Zheng Si,Yanlong Li,Lifeng Wen,Xiaoqi Du 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.8
Mass concrete structures are prone to suffer temperature destruction during construction and operation because of their own mechanical properties and the role of cement hydration; therefore, the law of temperature field and temperature stress changes is crucial. This paper is based on the heat conduction theory and contact friction element theory under general external load. The heat conduction matrix, node thermal load vector, equivalent stiffness-constraint matrix and equivalent load vector of the contact friction element are each added to the whole heat conduction matrix, thermal load vector and total stiffness matrix, and the total load vector according to the finite element integration rule to establish the thermal-stress calculation model of the contact friction element. Combined with the Qi River inverted siphon project, this paper analyzed the temperature field and temperature stress using the three-dimensional finite element method, considering the changes of concrete thermodynamic parameters with age and the outside air temperature and other conditions, and obtained the distribution and variation in temperature field and temperature stress during the construction of an inverted siphon. The research results are of great significance for temperature control and crack prevention of inverted siphon structures. The thermal-stress calculation model of the contact friction element overcomes the limitations that it is difficult to use the current contact surface model to perform the temperature field simulation and further improves the application of the contact friction element model in the simulation of the temperature field and the temperature stress of mass concrete.
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Zheng Ruan,Pan Yuan,Titao Jing,Tao Xing,Lifeng Yan 한국고분자학회 2018 Macromolecular Research Vol.26 No.3
A novel pH-sensitive carborane and cyanine dye conjugated polypeptide and its micelles has been designed and synthesized for potential near infrared fluorescence imaging-guided boron neutron capture therapy (BNCT). The amphiphilic polymer we synthesized with tertiary amine as functional group could self-assemble to micelle nanoparticles at neutral pH, and responsive to acidic solution for the disassembly of the micelles for drug release. The tertiary amine sensitive induced process was observed via dynamic light scattering (DLS) and transmission electron microscopy (TEM). The efficiency of cell killing ability is studied by MTT assays and fluorescence microscope measurement, indicating a new intelligent system for potential NIR imaging-guided therapy.
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Engineering of a Bacillus subtilis Strain Deficient in Cellulase: Application in Degumming of Ramie
Qi Yang,Shengwen Duan,Lifeng Cheng,Xiangyuan Feng,Ke Zheng,Chunliang Xie,Zhiyuan Liu,Yuande Peng 한국섬유공학회 2019 Fibers and polymers Vol.20 No.1
Degumming is the most important step before ramie fibers are used in textile industry. Conventional chemical degumming technology with alkaline treatment at high temperature causes critical problems in environment. In addition to multiple degumming enzymes (e.g. pectinases and xylanases), Bacillus subtilis strain 168 can also produce cellulase which brings irreversible damage to ramie fibers. In this study, a strain deficient in cellulase was constructed by insertional inactivation of gene eglS to make it suitable for microbial degumming. Results showed that the cellulase activity was not detected in strain ΔeglS, after 25 h of incubation with strain ΔeglS, the weight loss of the ramie fibers was 20.20 %. Though the residual gum content of ramie fibers obtained in microbial degumming process was 19.67 %, microbial intervention followed by diluted alkaline solution treatment showed lower residual gum content (2.73 %) than chemical degumming (2.96 %). The single fiber breaking strength value of ramie fibers from bio-chemical degumming process reached 27.19 cN, which was the highest of three samples. Moreover, bio-chemical degumming process resulted in a 75 % decrease of alkali dosage as compared with chemical degumming process. This study provides a suggestion to genetically modify wild-type strain in order to protect ramie fibers from cellulase damage, and indicates a sustainable alternative for the traditional chemical degumming in the textile industry.
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Sphingobacterium bambusae sp. nov., Isolated from Soil of Bamboo Plantation
Shengwen Duan,Zhengchu Liu,Xiangyuan Feng,Ke Zheng,Lifeng Cheng 한국미생물학회 2009 The journal of microbiology Vol.47 No.6
A Gram-negative, non-motile, non-spore-forming bacterial strain designated IBFC2009T was isolated from soil of a bamboo plantation. The strain could grow at 11°C~39°C, pH 6.0~9.0, and in the presence of 0~5% NaCl. Based on 16S rRNA gene sequence analysis, Strain IBFC2009T belonged to the genus Sphingobacterium and showed the highest sequence similarity of 94.6% (S. composti T5-12T) with the type strains within the genus. The major fatty acids were summed feature 3 (iso-C15:0 2-OH and/or C16:1 ω7c, 34.4%), iso-C15:0 (22.4%), C16:0 3-OH (15.2%), and iso-C17:0 3-OH (12.8%). The G+C content of the genomic DNA was 41.0 mol%. According to the phenotypic and genotypic characteristics, Strain IBFC2009T should represent a novel species of the genus Sphingobacterium, for which the name Sphingobacterium bambusae sp. nov. is proposed. The type strain is IBFC2009T (=CCTCC AB 209162T =KCTC 22814T).
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