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Fractal Analysis of Robertson-Stiff Fluid Flow in Porous Media

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Chinese Physics Letters 2012年第6期29卷 203-206页

作者： YUN mei-Juan zheng Wei Key Laboratory of Systems Science in Metallurgical Process of Hubei Province Wuhan University of Science and TechnologyWuhan 430081 State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu 610500 State Key Laboratory of Geodesy and Earth’s Dynamics Institute of Geodesy and GeophysicsChinese Academy of SciencesWuhan 430077

The Robertson-Stiff (RS) fluid is the representative fluid which may be reduced to Bingham,power-law and Newtonian fluids under appropriate *** present fractal models for the flow rate,velocity,starting pressure gradient and effective permeability for RS fluids in porous media based on the fractal characteristics of porous media and capillary *** proposed models are expressed as functions of the fractal dimensions,porosity,maximum pore size and the representative length of the porous *** parameter in the proposed expressions has clear physical meaning,and the proposed models relate the flow characteristics of the RS fluids to the structural parameters of the porous *** analytical expressions reveal the physical principles of RS fluid flow in porous media.

关键词： fractal porous dimensions

Ad hoc distributed mutual exclusion algorithm based on token-asking

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Journal of Systems Engineering and Electronics 2007年第2期18卷 398-406页

作者： Wang zheng Liu Xin'song Li mei'an School of Economic Information Engineering Southwestern Univ. of Finance and Economics Chengdu 610074 P.R.China 8010 R&D Computer Science and Engineering College Univ. of Electronic Science and Technology Chengdu 610054 P.R.China

The solution of distributed mutual exclusion is difficult in Ad hoc networks owing to dynamic topologies and mobility. Based on the analysis of the properties of Ad hoc networks and the disadvantages of the traditional algorithms, an improved Ad hoc system model was given and a novel algorithm was presented as AHDME （Ad Hoc Distributed Mutual Exclusion）; it was based on the token-asking algorithms. It utilized broadcast to search for the token and to decrease the message complexity of multi-hop Ad hoc networks. Lamport＇s timestamp was improved to ensure the time sequence and to prevent nodes from starvation. When compared to traditional algorithms, AHDME does not require the fixed size of request queues and the global system information, which adapts itself to the frequent arrival/departures and the limited computing capability of nodes in Ad hoc networks. Performance analysis and simulation results show that the AHDME algorithm has low message complexity, small space complexity, and short response delay.

关键词： Ad hoc Distributed mutual exclusion Token-asking Logical timestamp.

Image Classification with Superpixels and Feature Fusion Method

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Journal of Electronic Science and Technology 2021年第1期19卷 70-78页

作者： Feng Yang zheng Ma mei Xie the School of Information and Communication Engineering University of Electronic Science and Technology of ChinaChengdu 611731

This paper presents an effective image classification algorithm based on superpixels and feature *** from classical image classification algorithms that extract feature descriptors directly from the original image,the proposed method first segments the input image into superpixels and,then,several different types of features are calculated according to these *** increase classification accuracy,the dimensions of these features are reduced using the principal component analysis(PCA)algorithm followed by a weighted serial feature fusion *** constructing a coding dictionary using the nonnegative matrix factorization(NMF)algorithm,the input image is recognized by a support vector machine(SVM)*** effectiveness of the proposed method was tested on the public Scene-15,Caltech-101,and Caltech-256 datasets,and the experimental results demonstrate that the proposed method can effectively improve image classification accuracy.

关键词： Dimension reduction feature fusion image classification.

Rheological Behavior of the Melts for Polyethylene-based Montmorillonite Nanocomposites

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Chemical Research in Chinese Universities 2006年第5期22卷 651-657页

作者： YANG Hong-mei zheng Qiang DU Miao Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 P. R. China National Engineering Research Center for Compounding and Modification of Polymer Materials Guiyang 550025 P. R. China

The viscoelastic properties of melts of nanocomposites with partially exfoliated structures, which were composed of low-density polyethylene （LDPE）, ethylene vinyl acetate copolymer （EVA）, and montmofillonite and modified by cetyltrimethyl ammonium bromide and octadecyltrimethyl ammonium bromide, were studied. The results obtained through measurements of the dynamic storage modulus G′, the dynamic loss modulus G″, and the transiem stress relaxation modulus G（t） of the composites, reveal that the viscoelastic properties of the composites strongly depend on the amount of montmorillonite that is exfoliated into the composites. With the increase in montmoriUonite content, the composites show an obvious property of pseudo solid-like materials within the region of lower frequencies （ω）. The montmorillonite layers are aligned along the stress direction, and the dependence of dynamic modulus on ω, appears quite different for the composites before and after being exposed to a large amplitude oscillatory shears.

关键词： Rheological behavior Nanocomposite Polyethylene Montmorillonite

Interaction of multi-walled carbon nanotubes and zinc ions enhances cytotoxicity of zinc ions

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Science China Chemistry 2016年第7期59卷 910-917页

作者： lin Wang Jia-Hui Liu zheng-mei Song Yi-Xin Yang Aoneng Cao Yuanfang Liu Haifang Wang Institute of Nanochemistry and Nanobiology Shanghai University College of Life Science and Technology Beijing University of Chemical Technology Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular Engineering Peking University

More and more nanomaterials enter the environment along with their production, application and deposal. They may alter the biological effect of pollutants already existing in the real environment by different interactions. Therefore efforts should also be paid to investigate the combined toxicity of nanomaterials and pollutants. Herein, we studied the combined toxicity of oxi- dized multi-walled carbon nanotubes （O-MWCNTs） and zinc ions on ceils. It is found that cytotoxicity of the combined O-MWCNTs and zinc ions elevates significantly, compared with O-MWCNTs or zinc ions alone. This result comes from the assays of cell morphology, cell viability and proliferation, cell membrane integrity, mitochondrial membrane potential and cell apoptosis. Mechanism studies indicate that O-MWCNTs absorb zinc ions and form slight aggregation. These enhance remark- ably the cellular uptake of O-MWCNTs, and thus induce the death of cells by bringing in more zinc ions into cells. Our study indicates that the existence of nanomaterials could change the bioconsequence of other pollutants and emphasizes the im- portance of the combined toxicity research in the presence of nanomaterials.

关键词： carbon nanotube cytotoxicity zinc ion synergistic effect adsorption aggregation

Further developments of a multi-phase transport model for relativistic nuclear collisions

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Nuclear Science and Techniques 2021年第10期32卷 110-142页

作者： Zi-Wei lin Liang zheng Department of Physics East Carolina UniversityGreenvilleNC 27858USA School of Mathematics and Physics China University of Geosciences(Wuhan)Wuhan 430074China

A multi-phase transport(AMPT)model was constructed as a self-contained kinetic theory-based description of relativistic nuclear collisions as it contains four main components:the fluctuating initial condition,a parton cascade,hadronization,and a hadron ***,we review the main developments after the first public release of the AMPT source code in 2004 and the corre-sponding publication that described the physics details of the model at that *** also discuss possible directions for future developments of the AMPT model to better study the properties of the dense matter created in relativistic collisions of small or large systems.

关键词： QGP Transport model Heavy-ion collisions

Laboratory investigation on hydraulic fracture propagation in sandstone-mudstone-shale layers

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Petroleum Science 2022年第4期19卷 1664-1673页

作者： Jiang-Chuan He Kuang-Sheng Zhang Han-Bin Liu mei-Rong Tang Xue-lin zheng Guang-Qing Zhang PetroChina Changqing Oilfield Company Xi′an710018ShaanxiChina College of Petroleum Engineering China University of Petroleum(Beijing)Beijing102249China State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Beijing)Beijing102249China

During the stimulating unconventional reservoirs, the vertical propagation of hydraulic fractures is crucial for enlarging the stimulated reservoir volume, especially in multi-layers of sandstone, mudstone and shale(sand-mud-shale). To investigate the effects of lithological interface and fracturing fluid viscosity on the fracture propagation vertically in the multi-layers, hydraulic fracturing experiments in laboratory were performed on the outcrop samples of 30 cm × 30 cm × 30 cm collected from Yanchang Formation in Ordos Basin. The results show that hydraulic fractures are multi-branched and zig-zagged when they initiate in shale, simple when they commence in sandstone or mudstone. Hydraulic fractures created with low-viscosity fracturing fluid can only cross sandstone from mudstone, but those induced by high-viscosity fracturing fluid can cross the sand-mud-shale layers. Furthermore, the high-viscosity fracturing fluid reduces the fractures complexity in shale, facilitating vertical fracture propagation. The injection pressure fluctuates slightly as the hydraulic fracture extends from shale to sandstone or mudstone, otherwise it fluctuates significantly. From the laboratory investigation, a hydraulic fracturing scheme for Chang 7 Member was proposed, with its feasibility proved in field tests.

关键词： Sandstone-mudstone-shale Multi-layers Hydraulic fracturing experiments Lithological interface

Identification and characterization of a cytochrome P450 C YP6CX1 putatively associated with insecticide resistance in Bemisia tabaci

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Insect Science 2011年第5期18卷 484-494页

作者： Hua-mei Zhuang Kuan-Fu Wang lin zheng Zu-Jian Wu Tadashi Miyata Gang Wu Key Laboratory of Biopesticide and Chemical Biology Ministry of Education Fujian Agriculture and Forestry University Fuzhou Fujian China Laboratory of Applied Entomology Graduate School of Bioagricultural Sciences Nagoya University Nagoya Japan

The novel full length of cytochrome P450 gene has been isolated in insecticideresistant （named CYP6CXlvl） and -susceptible （named CYP6CXlv2） Bemisia tabaci, which was identified as B biotype, in Shangjie, Fujian, China （Sj）. CYP6CX1 （1 940 bp contained a 1 557 bp open reading frame） included conserved domains common to CYP6 members, such as heme-binding motif PFGEGPRFCIA, putative ＂meander＂-binding sequence ETLR and PERF in helix-K, oxygen-binding motif AGLDPV and conserved sequence PEKFNP near the carboxyl end. There were four different replacements of amino acid residues between R and S B. tabaci （Thr300 Ala, Thr354Pro, Arg486His and Ile503Thr）, among which the substitution Ile503Thr was located in the substrate recognition sites region. The mRNA transcription level of CYP6CXlvl was 2.38-fold as high as that of CYP6CXlv2. The results indicated that the CFP6CX1 from the B biotype B. tabaci in Sj was one of the CYP6 members, and enhanced CYP6CX1 expression and substitute of amino acid residues might be involved in the resistance mechanisms in field B. tabaci.

关键词： Bemisia tabaci biotype cytochrome P450s monooxygenases insecticide resistance

Correlation between Polyphenol Contents and Antioxidant Activities in Different Echinacea Purpurea Varieties

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Current Medical Science 2023年第4期43卷 831-837页

作者： Xiao-jing lin zheng-shi-yu LAI Qun LUO mei KONG Min-jian LIANG Hong WU mei BAI Guangdong Technology Research Center for Traditional Chinese Veterinary Medicine and Natural Medicine South China Agricultural UniversityGuangzhou 510642China Qilu Animal Health Products Company Jinan 250033China State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources College of Life SciencesSouth China Agricultural UniversityGuangzhou 510642China

Objective:Polyphenols are complex compounds containing multiple phenolic hydroxyl *** are widely distributed in plants and have antioxidant *** the antioxidant activities of the cultivated varieties of Echinacea are similar to or better than those of the wild ones and the relationship between the accumulation of polyphenols and their antioxidant activities are still not ***:Folin-Ciocalteu method,high performance liquid chromatography(HPLC),2,2-diphenyl-1-picrylhydrazyl(DPPH)radical scavenging assay,ferric ion reducing antioxidant power(FRAP)assay,2,2'-azino-bis(3-ethylbenzothiazoline-6)-sulfonic acid(ABTS)radical scavenging assay,and Fe^(2+)chelating ability assay were used,respectively,to detect the total polyphenols and 5 kinds of caffeic acid derivatives(chicoric acid,caffeic acid,caftaric acid,chlorogenic acid,and 1,5-dicaffeoylquinic acid)in the roots,stems,leaves,and flowers,and the antioxidant activities of 3 varieties of Echinacea:*** L.,cultivar ***'Aloha',and ***'White Swan'.Results:*** *** the highest contents of total polyphenols,5 caffeic acid derivatives and antioxidant activities,followed by ***'White Swan'and ***'Aloha',***'White Swan'had the strongest ability to remove the DPPH,ABTS·^(+)and free radicals,and to chelate Fe^(2+);*** *** the strongest ability to reduce *** correlation analyses revealed that the contents of total polyphenols and caffeic acid derivatives of *** *** ***'White Swan'were correlated with their antioxidant ***:*** *** the most appropriate material for the development of medicinal ***'White Swan'could be used as a substitute for *** *** terms of its antioxidant activity.

关键词： antioxidant activity caffeic acid derivatives Echinacea purpurea medicinal plants total polyphenol