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Exploring effects of property variation on fragmentation of metal rings using a simple model

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defence Technology（防务技术） 2023年第5期23卷 1-7页

作者： J.d.Robson department of Materials The University of ManchesterManchesterM139PLUK

A simple finite element implementation of the Mott model for fragmentation of a thin walled ring has been implemented and used to explore the effect of local variations in fracture strain around the *** model has successfully reproduced the fragment size distributions previously reported,which follow a characteristic“Mott distribution”form,providing sufficient(1000)simulations are *** has been shown that this form is retained even when there are large differences in the random distribution of fracture strains or a different choice of function used to describe the fracture strain *** these cases,the strain rate has a much stronger effect than fracture strain distribution the on the average fragment size and fragment ***,for cases where there are a small number of local defects that strongly reduce the fracture strain at certain locations around the ring,the predicted fragment size distribution develops a bimodal *** is also the case for large but gradual variations in fracture strain with position around the *** results have implications for cases where a small number of large pre-existing defects exist,or processing has led to macrozones in the *** utility of a simple fast running model to study these cases is discussed.

关键词： Fragmentation Mott model Property variation

Effects of jute fibre content on the mechanical and dynamic mechanical properties of the composites in structural applications

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defence Technology（防务技术） 2020年第6期16卷 1098-1105页

作者： Suhad d.Salman Mechanical Engineering department College of EngineeringMustansiriyah UniversityBaghdadIraq

due to notable characteristics,sustainability concept and environmental issues,hybridisation natural with synthetic fibres to fabricate composites have been rapidly gaining market share in different applications(structural,military,aerospace and automotive vehicles).Compression,tension and fatigue tests of various stacking sequences of plain jute/carbon reinforced(PVB)polyvinyl butyral by hot hydraulic press technique were experimentally *** types of fabricated composites with various constituents(jute,carbon and their hybrids)were fabricated and ***,fatigue lifetime of hybrids increases with increasing the carbon content relative to the jute fibre *** the other hand,Jute composites possess high strain compared to pure carbon composite,which gives an overall improvement in mechanical ***,H1 hybrid with Carbon/Jute/Carbon sequences offers similar fatigue stiffness behaviour of H3 hybrid with Carbon/Jute/Carbon/Jute sequences when subjected to cyclic *** composite(C)exhibited the highest fatigue resistance,whiles jute composite(J)possessed the highest strain and semi brittle trends in both mechanical and fatigue *** concluded that plain jute fibres could partially replace high-cost synthetic carbon fibres to produce more eco-friendly hybrids to be utilised in different composites industries.

关键词： Plain woven jute Carbon fabric Hybrid composite Mechanical Cyclic loading Morphological Fatigue properties

A Hybrid Joining Technology for Aluminum/Zinc Coated Steels in Vehicles

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Journal of Materials Science & Technology 2010年第9期26卷 858-864页

作者： C.Y.Choi d.C.Kim d.G.Nam Y.d.Kim Y.d.Park School of Materials Science and Engineering Pusan National UniversityBusan Advanced Welding & Joining R&d division Institute of Industrial Technology Incheon dongnam Technology Service division Korea Institute of Industrial TechnologyBusan department of Advanced Materials Engineering Dong-Eui UniversityBusan

Currently,in the automotive industry,joining of the aluminum alloys with the steel is a crucial problem to be *** joining techniques including resistance spot and gas metal arc welding are not acceptable for those applications due to a number of metallurgical *** investigation was carried out to develop the hybrid joining process combining the resistance spot welding and *** this study,an attempt was made to apply hybrid process to the joining of dissimilar sheet metals,Al-Mg-Si（6000 series） alloy and low carbon steel *** process（resistance spot weld/brazing） using filler metal was found to be effective to overcome the incompatibility between aluminum alloy and *** hybrid joining process of Al alloy sheet and steel sheet did not produce acceptable bond strength,it was proved to have reasonable interfacial bond layer if the optimal process condition was applied.

关键词： Hybrid joining Aluminum alloy Steel Resistance welding Brazing

The drosophila ovary: an active stem cell community

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Cell Research 2007年第1期17卷 15-25页

作者： dánielKirilly Institute of Genetics Szeged 6726 Biological Research Centre of the Hungarian Academy of Sciences Hungary Temesvári krt.62

Only a small number of cells in adult tissues (the stem cells) possess the ability to self-renew at every cell division,while producing differentiating daughter cells to maintain tissue homeostasis for an organism’s *** drosophilaovary harbors three different types of stem cell populations (germline stem cell (GSC),somatic stem cell (SSC) andescort stem cell (ESC)) located in a simple anatomical structure known as germarium,rendering it one of the best modelsystems for studying stem cell biology due to reliable stem cell identification and available sophisticated genetic toolsfor manipulating gene ***,the niche for the GSC is among the first and best studied ones,and studieson the GSC and its niche have made many unique contributions to a better understanding of relationships between stemcells and their *** far,both the GSC and the SSC have been shown to be regulated by extrinsic factors originatingfrom their niche and intrinsic factors functioning *** signaling pathways are required for controlling GSCand SSC self-renewal and differentiation,which provide unique opportunities to investigate how multiple signals fromthe niche are interpreted in the stem *** the drosophila ovary contains three types of stem cells,it also providesoutstanding opportunities to study how multiple stem cells in a given tissue work collaboratively to contribute to tissuefunction and *** review highlights recent major advances in studying drosophila ovarian stem cells andalso discusses future directions and challenges.

关键词： drosophila ovary germline stem cell somatic stem cell escort stem cell

Characteristics of urban ozone level in Hong kong

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Journal of Environmental Sciences 2001年第1期13卷 1-7页

作者： d.Y.C.LEUNG d.N.ZHANG department of Mechanical Engineering The University of Hong KongPokfulam RoadHong KongChina Research Institute of Environmental Engineering East China University of Science and TechnologyShanghai 200237China

The long term trend of ozone level in Hong Kong has been investigated. One of the characteristics of ozone level in Hong Kong is the existence of autumn maximum and summer minimum. Observations of the diurnal variation of ozone level have been made in different area categories. There are early morning peak and afternoon peak occurred in the diurnal variation, which are different from some metropolitans where only an afternoon peak is observed. A negative correlation coefficient was found between monthly ozone level with nitric oxide level. On the contrary, there is a positive correlation between ozone and nitrogen dioxide. The positive correlation coefficient between nitric oxide and nitrogen dioxide shows that the total amount of nitric oxide emitted from a series of moving and fixed sources greatly exceeded the stoichiometric amount of ozone formed from chemical reactions of precursors and long distance transportation.

关键词： ozone urban air pollution Hong kong China

Effectiveness of a fixed-depth sensor deployed from a buoy to estimate water-column cyanobacterial biomass depends on wind speed

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Journal of Environmental Sciences 2020年第7期32卷 23-29页

作者： Justin d.Chaffin douglas d.Kane Alex Johnson F.T Stone Laboratory and Ohio Sea Grant the Ohio State UniversityOH 43456USA division of Natural Science Applied Scienceand MathematicsDefiance CollegeDefiance OHF.T Stone LaboratoryThe Ohio State University and Ohio Sea GrantOH 43456USA

Water quality sondes have the advantage of containing multiple sensors,extended deployment times,high temporal resolution,and telecommunication with stakeholder accessible data ***,sondes that are part of buoy deployments often suffer from typically being fixed at one *** water treatment plants are interested in water quality at a depth of the water intake and other stakeholders(*** and swimmers)are interested in the surface,we examined whether a fixed depth of approximately 1 m could cause over-or under-estimation of cyanobacterial *** sampled the vertical distribution of cyanobacteria adjacent to a water quality sonde buoy in the western basin of Lake Erie during the summers of 2015–2017.A comparison of buoy cyanobacteria RFU(Relative Fluorescence Unit)at 1 m to cyanobacteria chlorophyll a(chla)measured throughout the water column showed occurrences when the buoy both under and overestimated the cyanobacteria chl a at specific *** differences between buoy measurements and at-depth grab samples occurred during low wind speeds(ds allowed cyanobacteria to accumulate at the surface above the buoy’s *** wind speeds(>4.5 m/sec)resulted in better agreement between the buoy and at-depth *** wind speeds 12 hr before sample collection decreased the difference between the buoy and at-depth samples for high wind speeds but not low *** suggest that sondes should be placed at a depth of interest for the appropriate stakeholder group or deploy sondes with the ability to sample at various depths.

关键词： Buoyancy Harmful algal bloom Lake Erie Microcystis Water quality

Release rate kinetics of corrosion inhibitor loaded halloysite nanotube-based anticorrosion coatings on magnesium alloy AZ91d

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Journal of Magnesium and Alloys 2021年第1期9卷 202-215页

作者： Swapnil H.Adsul Uday d.Bagale Shirish H.Sonawane R.Subasri Centre for Sol-Gel Coatings International Advanced Research Centre for Powder Metallurgy and New Materials(ARCI)BalapurHyderabad 500005Telangana StateIndia department of Food and Biotechnology South Ural State UniversityChelyabinsk 454080Russia department of Chemical Engineering National Institute of TechnologyWarangal 506004Telangana StateIndia

Halloysite nanotubes were used as nanocontainers to hold corrosion inhibitors such as Ce^(3+)-Zr^(4+),2-mercaptobenzothiazole and 8-hydroxyquinoline in their *** acid assisted etching of the nanotubes was carried out with a view to increase the lumen diameter and thereby,increase the amount of loading of the corrosion *** morphology of as-received and etched halloysite nanotubes was ob-served using TEM *** loading of corrosion inhibitors was confirmed using SEM-EdS and BET *** microcapsules were used as capping agents for the ends of the loaded HNTs following which,they were dispersed into a hybrid sol-gel silica *** coating method was used to generate coatings on AZ91d substrates followed by heat treatment at 130℃ for 1 *** release rate kinetics of corrosion inhibitors from as-received and etched nanotubes was investigated in buffer solutions of 3.5 wt%NaCl at different *** release mechanism of corrosion inhibitors from the HNT lumen was validated using various semi-empirical *** were also evaluated for their corrosion protection ability using electrochemical techniques after exposure to 3.5 wt%NaCl solution for 120 *** generated using Ce^(3+)-Zr^(4+)loaded into as-received halloysite nanotubes have shown more effective corrosion protection when compared to other corrosion inhibitors after 120 h exposure to the corrosive medium.

关键词： Sol-gel coating Halloysite nanotubes Corrosion inhibitors Release rate Magnesium alloy AZ91d

Luminescence properties of Gd^(3+) containing glasses for ultra-violet(UV) light

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Journal of Rare Earths 2014年第5期32卷 389-393页

作者： d.d.Ramteke R.S.Gedam department of Applied Physics Visvesvaraya National Institute of Technology

Effect of Gd2O3 addition on optical properties of 27.5 Li2O-72.5 B2O3 glass systems was studied. density, differential thermal analysis （dTA）, optical absorption spectra and luminescence technique were used to characterize the prepared glasses. Emis- sion spectra showed two band 6p7/2→8S7/2 （311.5 nm） and 6p5/2→8S7/2 （305 nm） under the excitation of 274 nm. The intense emission at 311.5 nm suggested that these glasses could be useful as source of narrowband UV light.

关键词： glasses rare earths absorption band gap luminescence UV light

Electrical and optical properties of lithium borate glasses doped with Nd_2O_3

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Journal of Rare Earths 2012年第8期30卷 785-789页

作者： R.S. Gedam d.d. Ramteke department of Applied Physics Visvesvaraya National Institute of Technology

Glass series with general formula 25Li2O-（75-x）B2O3-xNd2O3 was prepared by conventional melt quench technique. Electrical and optical characterizations of these glasses were carried out. It was observed that conductivity of glasses decreased and activation energy in- creased with the addition of Nd2O3. The density and refractive index of the glasses increased while optical band gap and radiation length de- creased due to structural changes.

关键词： conductivity density refractive index optical absorption Tauc's plot rare earths