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STUDIES ON MOLEcULAR WEIgHT DISTRIBUTION OF cARBON FIBER POLYMER PREcURSORS SYNTHESIZED USINg MIXED SOLVENTS

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chinese Journal of Polymer Science 2012年第5期30卷 664-673页

作者： g.Santhana Krishnan A.Burkanudeen N.Murali Hemant Phadnis Materials Science Division CSIRNational Aerospace LaboratoriesBangalore-560017India Post graduate and Research Department of chemistry Jamal Mohammed CollegeBharathidasan UniversityTiruchirappalliIndia Malvern Application Laboratory Naimex HouseBangalore-560045India

The molecular weight distributions were estimated for carbon fiber polymer precursors such as poly（acrylonitrile-co-itaconic acid） synthesized by semi batch solution polymerization in mixed solvents media with the azonitrile compounds as initiator under the different ratios of solvent and non solvent from 0.75 to 2.5 in weight. The copolymer was characterized by using Fourier transform infrared spectroscopy （FTIR） and nuclear magnetic resonance （1H-NMR） analyses. The molecular weight distributions were evaluated by Mv/Mn ratios estimated from viscosity and osmotic measurements, and Mw/Mn estimated from size exclusion chromatography. The molecular weight distributions of these polymers as determined from M, JMn and Mw/Mn are 2.9 to 3,2 and 2.0 to 2.5 respectively. The molecular distributions were close to a narrow distribution of 2.0 when the solvent/non-solvent ratio was varied between 1.4 and 2.0. Intrinsic viscosity [η] as a function of molecular weight of poly（acrylonitrile-co-itaconic acid） was evaluated by means of low angle laser light scattering with size exclusion chromatography （SEc-LALLS） and viscometry with SEc （SEc-VIScO）. The relationship between [η] and Mw for poly（acrylonitrile-co-itaconic acid） in DMF at 50℃ was [q] = 1.1×10-5 Mw0.79, where [η] is obtained in dL/g.

关键词： Molecular weight distribution Size exclusion chromatography Osmometry Viscometry Polyacrylonitrilecopolyrner.

Implementation aspects of a phase-field approach for brittle fracture

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Frontiers of Structural and civil Engineering 2019年第2期13卷 417-428页

作者： g.D.HUYNH X.,ZHUANg H.NgUYEN-XUAN Institute of continuum Mechanics Leibniz-Universitat Hannover30167 HannoverGermany center for Interdisciplinary Research in Technology Ho Chi Minh CityUniversity of Technology (HUTEH)Ho Chi Minh City Vietnam

This paper provides a comprehensive overview of a phase-field model of fracture in solid mechanics setting. We start reviewing the potential energy governing the whole process of fracture including crack initiation, branching or merging. Then, a discretization of system of equation is derived, in which the key aspect is that for the correctness of fracture phenomena, a split into tensile and compressive terms of the strain energy is performed, which allows crack to occur in tension, not in compression. For numerical analysis, standard finite element shape functions are used for both primary fields including displacements and phase field. A staggered scheme which solves the two fields of the problem separately is utilized for solution step and illustrated with a segment of Python code.

关键词： phase-field modeling FEM staggered scheme fracture

Network coding-aware cache replacement policy in on-demand broadcast environments

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Journal of Harbin Institute of Technology(New Series) 2012年第5期19卷 92-100页

作者：陈君 LEE Victor c S cHAN Edward School of Information Management Wuhan UniversityWuhan 430072China Dept.of computer Science City University of Hong KongHong KongChina

Network coding has been proved to be an effective technique in improving the performance of data broadcast systems because clients requesting different data items can be served simultaneously in one broadcast. Previous studies showed that its efficiency is highly related to the content of clients' cache. However, existing data broadcast systems do not take network coding information into account when making cache replacement decisions. In this paper, we propose two networks coding-aware cache replacement policies called DLRU and DLRU-cP to supplement network coding assisted data broadcast in on-demand broadcast environments. In DLRU, both data access and decoding contribution are taken into account to make replacement decisions. DLRU-cP is based on DLRU but allows clients to retrieve decodable data items that have not been requested yet. The performance gain of our proposed cache replacement policies over traditional cache replacement policy is shown in the simulation results, which demonstrate conclusively that the proposed policies can effectively reduce the overall response time.

关键词： Network coding cache replacement on-demand broadcast mobile computing

A novel indicator system for catalytic spectrophotometric determination and speciation of inorganic selenium species (Se(Ⅳ), Se(Ⅵ)) at trace levels in natural lake and river water samples

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Rare Metals 2011年第5期30卷 477-487页

作者： Ramazan gürkan Halil brahim Ulusoy Mehmet Akay Pinar Bulut Department of chemistry Faculty of Science University of Cumhuriyet

A novel catalytic kinetic method is proposed for the determination of Se（Ⅳ）, Se（Ⅵ）, and total inorganic selenium in water based on the catalytic effect of Se（Ⅳ） on the reduction of celestine blue by sodium sulfide at pH 7.0 phosphate buffer. The fixed-time method was adopted for the determination and speciation of inorganic selenium. Under the optimum conditions, the two calibration graphs are linear with a good correlation coefficient in the range 2-20 and 20-200 μg·L-1 of Se（Ⅳ） for the fixed-time method at 30℃. The experimental and theo- retical detection limits of the developed kinetic method were found to be 0.21 and 2.50 μg·L-1 for the fixed-time method （3 min）. All of the variables that affect the sensitivity at 645 nm were investigated, and the optimum conditions were established. The interference effect of various cations and anions on the Se（Ⅳ） determination was also studied. The selectivity of the selenium determination was greatly improved with the use of the strongly cation exchange resin such as Amberlite IR120 plus as long as chelating agents of thiourea and thiosulphate. The proposed kinetic method was validated statistically and through recovery studies in natural water samples. The relative standard deviations （RSDs） for ten replicate measurements of 2, 10, and 20 μg·L-1 of Se（Ⅳ） change between 0.35% and 5.58%, while the RSDs for ten replicate measurements of 3, 6, and 12 μg·L-1 of Se（Ⅵ） change between 0.49% and 1.61%. Analyses of a certified standard reference material （NIST SRM 1643e） for selenium using the fixed-time method showed that the proposed kinetic method has good accuracy. The Se（Ⅳ）, Se（Ⅵ）, and total inorganic selenium in lake and river water samples have been successfully determined by this method after selective reduction of Se（Ⅵ） to Se（Ⅳ）.

关键词： selenium speciation celestine blue catalytic effect kinetic spectrophotometry natural waters

Lipid enhancement in microalgae by temporal phase separation:Use of indigenous sources of nutrients

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chinese Journal of chemical Engineering 2018年第1期26卷 175-182页

作者： Nidhin Sreekumar Ajit Haridas g.S.godwin N.Selvaraju National Institute of Technology(NITc) CalicutIndia National Institute for Interdisciplinary Science and Technology(NIIST) Council of Scientific&Industrial Research(CSIR)ThiruvananthapuramIndia

Microalgae have been recommended as superior candidate for fuel production because of their advantages of higher photosynthetic efficiency, biomass & lipid productivity, and faster growth rate as compared to other energy crops. To meet up all these criteria, we have developed a continuous outdoor micro-algal raceway pond reactor(RPR) and a lab scale indoor tubular photo bioreactor(PBR) for biofuel production. An attempt to utilise indigenous sources of nutrients to improve the economics also revealed that micro-algal culturing can also be used as a mode of nutrient removal and water treatment. The photosynthetic rate and lipid production were enhanced by arresting daytime cell division and promoting night-time cell division. A 50% lipid improvement was observed for the particular algal consortia. Microscopic studies revealed that temporal phase separation could be achieved by adjusting nutrient distribution pattern. To monitor temporal phase separation, it is required to know DNA multiplication model. Quantification of g DNA in RPR confirmed that cell division happens during the night which positively affects the photosynthetic efficiency and lipid productivity of microalgae.

关键词： Temporal phase separation Lipid enhancement Microalgae Biodiesel

High-Performance InTiZnO Thin-Film Transistors Deposited by Magnetron Sputtering

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chinese Physics Letters 2013年第12期30卷 126-129页

作者： LIU Ao LIU guo-Xia SHAN Fu-Kai ZHU Hui-Hui B.c.Shin W.J.Lee c.R.cho college of Physics Science Qingdao UniversityQingdao 266071 Lab of New Fiber Materials and Modern Textile Growing Base for State Key LaboratoryQingdao UniversityQingdao 266071 Electronic ceramics center DongEui UniversityBusan 614714South Korea college of Nanoscience and Nanotechnology Pusan National UniversityBusan 609735South Korea

InTiZnO thin-film transistors(ITZO TFTs)with Al_(2)O_(3)gate dielectrics are fabricated by magnetron sputtering at room *** bottom-gate-type ITZO TFTs with amorphous Al_(2)O_(3)gate dielectrics are operated in the enhancement mode and exhibit a mobility of 50.4 cm^(2)/V·s,threshold voltage of 1.2 V,subthreshold swing of 94.5 mV/decade,and on/off-current ratio of 7×10^(6).We believe that ITZO deposited at room temperature is an appropriate semiconductor material to produce high-mobility TFTs for developing flexible electronic devices.

关键词： temperature mobility film

Rotational Forms of Large Eddy Simulation Turbulence Models:Modeling and Mathematical Theory

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chinese Annals of Mathematics,Series B 2021年第1期42卷 17-40页

作者： Luigi c.BERSELLI Roger LEWANDOWSKI Dinh Duong NgUYEN Universita di Pisa Dipartimento di MatematicaVia Buonarroti 1/c1-56127 Pisa Italy IRMAR UMR CNRS 6625University of Rennes 1 and FLUMINANCE TeamINRIA RennesFrance

In this paper the authors present a derivation of a back-scatter rotational Large Eddy Simulation model,which is the extension of the Baldwin&Lomax model to nonequilibrium *** model is particularly designed to mathematically describe a fluid filling a domain with solid walls and consequently the differential operators appearing in the smoothing terms are degenerate at the *** the derivation of the model,the authors prove some of the mathematical properties coming from the weighted energy estimates,which allow to prove existence and uniqueness of a class of regular weak solutions.

关键词： Fluid mechanics Turbulence models Rotational Large Eddy Simulation models Navier-Stokes equations

Ophiolites and Intra-Oceanic Island Arc Assemblages of Eastern Australia, New caledonia and New Zealand

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Acta geologica Sinica(English Edition) 2017年第S1期91卷 1-3页

作者： Jonathan c.AITcHISON School of Earth and Environmental Sciences University of QueenslandSt LuciaBrisbaneQLD 4072Australia

Throughout the Phanerozoic the eastern margin of gondwana and related fragments such as New caledonia and New Zealand that are now dispersed from it grew through the addition of ophiolites and associated intra-oceanic island arc *** how and why this occurred remains controversial with two main competingmodelsreferredtoaseither‘quantum’or‘accordion’*** quantum model envisages continental growth through the additional of discrete intra-oceanic assemblages analogous to contemporary tectonic settings in Taiwan,Timor and Papua New guinea(Aitchison and Buckman,2012).The alternative regards eastern Australia as the type example of a different style of convergent plate margin referred to as an‘extensional accretionary orogeny’(collins,2002).The oldest Phanerozoic ophiolites and intra-oceanic island arc assemblages are of cambrian age and are widely reported from the Lachlan Fold Belt in the eastern Australian states of Victoria and NSW(Spaggiari et al.,2003;greenfield et al.,2011).Similar rocks are also known from Mount Read in Tasmania(Berry and crawford,1988;crawford and Berry,1992;Mulder et al.,2016),the Weraerai terrane and its correlatives in the New England orogen further east in northeastern NSW(Aitchison et al.,1994;Aitchison and Ireland,1995)and Queensland,the Takaka terrane in NW Nelson,New Zealand(Münker and cooper,1999)and the Bowers terrane in Northern Victoria Land,Antarctica(Weaver et al.,1984;Münker and crawford,2000;Rocchi et al.,2011;Palmeri et al.,2012).The Late Ordovician saw the development of the intra-oceanic Macquarie island arc(glen et al.,1998;glen et al.,2007).This system contains important economic mineral *** way in which these arcrocks developed and were juxtaposedagainst a surrounding suite of Lachlan Fold Belt,eastern Australia remains the subject of investigation(see Aitchison and Buckman,2012 for discussion).In a similar area,enigmatic rocks of the Tumut ophiolite also crop out(graham et al.,1996;Belousova

关键词： New caledonia and New Zealand

Impact analysis of compressor rotor blades of an aircraft engine

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Frontiers of Structural and civil Engineering 2019年第3期13卷 505-514页

作者： Y B SUDHIR SASTRY B g KIROS F HAILU R BUDARAPU Department of Aeronautical Engineering Institute of Aeronautical EngineeringDundigalHyderabad 500043India Department of Aeronautical Engineering College of EngineeringDefense UniversityBishoftu 1041Ethiopia School of Mechanical Sciences Indian Institute of Technology BhubaneswarBhubaneswar 752050India

Frequent failures due to foreign particle impacts are observed in compressor blades of the interceptor fighter MIg-23 aircraft engines in the Ethiopian air force,supplied by the Dejen Aviation *** this paper,we made an attempt to identify the causes of failure and hence recommend the suitable materials to withstand the foreign particle *** and stress analysis of one of the recently failed MIg-23 gas turbine compressor blades made up of the following Aluminum based alloys:6061-T6,7075-T6,and 2024-T4,has been performed,apart from the impact analysis of the rotor blades hit by a granite *** numerical results are correlated to the practical *** on the modal,stress and impact analysis and the material properties of the three considered alloys,alloy 7075-T6 has been recommended as the blade material.

关键词： axial flow compressor rotor and stator blades aircraft engine stress and impact analysis aluminum alloys