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Hot Deformation Characteristics of 34Crmo4 Steel

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Journal of Iron and Steel Research International 2010年第12期17卷 65-69页

作者： S v Sajadi Far m Ketabchi m R Nourani mining and metallurgical Engineering Department Amirkabir University of Technology

The 34Crmo4 （AISI 4130） steel is extensively utilized in the compressed natural gas cylinders. Due to the importance of thermomechanical processing in the production of these cylinders, the dynamic reerystallization （DRX） characteristics of 34Crmo4 steel were investigated. The effect of hot deformation parameters such as temperature and strain rate on the dynamic restoration processes of a 34Crmo4 alloy was studied. Hot compression tests were performed in the temperature range of 900 to 1 100 ℃ and the strain rate range of 0. 001 to 0.1 s-1. Hot workability of this alloy has been analyzed by employing flow localization parameter. The flow curves observed are typical of occurrence of dynamic recrystallization and have exhibited single or multiple peaks in flow stress curve before reaching steady state, depending on the temperature and strain rates. The flow stress decreases with the increase of deformation temperature and the decrease of strain rate. Finally the activation energy obtained in this research is 490. 749 kJ/mol.

关键词： 34Crmo4 steel hot deformation activation energy dynamic recrystalization

Plasma electrolytic oxidation of the magnesium alloy mA8 in electrolytes containing TiN nanoparticles

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Journal of materials Science & Technology 2017年第5期33卷 461-468页

作者： D.v.mashtalyar S.v.Gnedenkov S.L.Sinebryukhov I.m.Imshinetskiy A.v.Puz Institute of Chemistty Far Eastern BranchRussian Academy of Sciences 159Prosp.100-1etya VladivostokaVladivostok 690022Russia Far Eastern Federal University 8 Sukhanova St.Vladivostok690950Russia

The formation of protective multifunctional coatings on magnesium alloy mA8 using plasma electrolyt- ic oxidation （PEO） in an electrolytic system containing nanosized particles of titanium nitride was investigated. Electrochemical and mechanical properties of the obtained layers were examined. It was established that microhardness of the coating with the nanoparticle concentration of 3 gl-1 increased twofold （4.2 ± 0.5 GPa）, while wear resistance decreased （4.97 × 10-6 mm3 N-1 m-1）, as compared to re- spective values for the PEO-coating formed in the electrolyte without nanoparticles （2.1 ± 0.3 GPa, 1.12 × 10.5 mm3 N-1 m-1）.

关键词： magnesium alloys Protective coatings Plasma electrolytic oxidation Corrosion titanium nitride Nanoparticles

Nature Inspired Improved Firefly Algorithm for Node Clustering in WSNs

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Computers, materials & Continua 2020年第8期64卷 753-776页

作者： v.manikandan m.Sivaram Amin Salih mohammed v.Porkodi Department of Computer Networking College of Engineering and Computer ScienceLebanese French UniversityErbil44001Iraq College of Engineering and Computer Science Lebanese French UniversityErbil44001Iraq Department of Information Technology College of Engineering and Computer ScienceLebanese French UniversityErbil44001Iraq

Wireless Sensor Networks(WSNs)comprises low power devices that are randomly distributed in a geographically isolated *** energy consumption of nodes is an essential factor to be ***,an improved energy management technique is designed in this investigation to reduce its consumption and to enhance the network’s *** can be attained by balancing energy clusters using a meta-heuristic Firefly algorithm model for network *** improved technique is based on the cluster head selection technique with measurement of the tour length of *** Division multiple Access(TDmA)scheduler is also improved with the characteristics/behavior of fireflies and also *** last,the development approach shows the progression of the network lifetime,the total number of selected Cluster Heads(CH),the energy consumed by nodes,and the number of packets *** approach is compared with Ad hoc On-Demand Distance vector(AODv),Dynamic Source Routing(DSR)and Low Energy Adaptive Clustering Hierarchy(LEAH)*** is performed in mATLAB with the numerical outcomes showing the efficiency of the proposed *** energy consumption of sensor nodes is reduced by about 50%and increases the lifetime of nodes by 78%more than AODv,DSR and LEACH *** parameters such as cluster formation,end to end delay,percentage of nodes alive and packet delivery ratio,are also evaluated...The anticipated method shows better trade-off in contrast to existing techniques.

关键词： Cluster head wireless sensor network LEAH TDmA firefly AODv DSR

Effects of variable retention harvesting on canopy transpiration in a red pine plantation forest

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Ecological Processes 2022年第1期11卷 374-385页

作者： Alanna v.Bodo m.Altaf Arain School of Earth Environment and SocietyMcMaster University1280 Main Street WestHamiltonON L8S 4K1Canada mcmaster Centre for Climate Change McMaster University1280 Main Street WestHamiltonON L8S 4K1Canada

Background:variable Retention Harvesting(vRH)is a forest management practice applied to enhance forest growth,improve biodiversity,preserve ecosystem function and provide economic revenue from harvested *** are many different forms and compositions in which vRH is applied in forest *** this study,the impacts of four different vRH treatments on transpiration were evaluated in an 83-year-old red pine(Pinus Pinus resinosa)plantation forest in the Great Lakes region in *** vRH treatments included 55%aggregated crown retention(55A),55%dispersed crown retention(55D),33%aggregated crown retention(33A),33%dispersed crown retention(33D)and unharvested control(CN)*** vRH treatments were implemented in 1-ha plots in the winter of 2014,while sap flow measurements were conducted from 2018 to ***:Study results showed that tree-level transpiration was highest among trees in the 55D treatment,followed by 33D,55A,33A and CN *** found that photosynthetically active radiation(PAR)and vapor pressure deficit(vPD)were major controls or drivers of transpiration in all vRH *** study suggests that dispersed or distributed retention of 55%basal area(55D)is the ideal forest management technique to enhance transpiration and forest ***:This study will help researchers,forest managers and decision-makers to improve their understanding of water cycling in forest ecosystem and adopt the best forest management regimes to enhance forest growth,health and resiliency to climate change.

关键词： variable Retention Harvesting Forest management Transpiration Sap flow Red pine Great Lakes region

Al–TiO_2–Gr powder metallurgy hybrid composites with cold upset forging

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Rare metals 2014年第6期33卷 686-696页

The cold upsetting studies were carried out for the aluminium metal matrix hybrid composites in the present study. Aluminium metal matrix hybrid composites were synthesised through powder metallurgy route from ball-milled powders to yield the following compositions：Al ＋ 2.5 wt% TiO2＋ 2 wt% Gr, Al ＋ 2.5 wt% TiO2＋ 4 wt% Gr, Al ＋ 5.0 wt% TiO2＋ 2 wt% Gr and Al ＋ 5.0 wt% TiO2＋ 4 wt% Gr. The compaction process was carried out using suitable punch and die in 40 k N hydraulic press, and sintering was done in an electric muffle furnace at the temperature of 590 °C for 3 h. The sintered preforms were subjected to incremental compressive loading of 10 k N until the cracks were found at the free surface. The true axial stress, true hoop stress, true hydrostatic stress and true effective stress were calculated for all the preforms, and all these stresses are correlated with the true axial strain. The stress ratio parameters（rz/reff, rh/reff, rz/rmand rh/rm） of the all preforms were correlated with true axial strain. The maximum true axial stress, true hoop stress, true effective stress and hydrostatic static stress are obtained for the composite containing5 wt% of TiO2 and 4 wt% of graphite and the minimum ones are obtained for composite containing 2.5 wt% of TiO2 and 2 wt% of graphite.

关键词： metal matrix composites Cold upsetting Powder metallurgy

Effect of Process Parameters on Tensile Strength of Friction Stir Welded Cast Lm6 Aluminium Alloy Joints

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Journal of materials Science & Technology 2009年第5期25卷 655-664页

作者： m.Jayaraman R.Sivasubramanian v.Balasubramanian Department of mechatronics Engineering Kongu Engineering CollegeErodeTamil NaduIndia Department of mechanical Engineering Coimbatore Institute of TechnologyCoimbatoreTamil NaduIndia Centre for materials Joining&Research(CEmAJOR) Department of Manufacturing EngineeringAnnamalai UniversityAnnamalainagarTamil NaduIndia

This paper reports the effect of friction stir welding （FSW） process parameters on tensile strength of cast Lm6 aluminium alloy. Joints were made by using different combinations of tool rotation speed, welding speed and axial force each at four levels. The quality of weld zone was investigated using macrostructure and microstructure analysis. Tensile strength of the joints were evaluated and correlated with the weld zone hardness and microstructure. The joint fabricated using a rotational speed of 900 r/min, a welding speed of 75 mm/min and an axial force of 3 kN showed superior tensile strength compared with other joints. The tensile strength and microhardness of the welded joints for the optimum conditions were 166 mPa and 64.8 Hv respectively.

关键词： Lm6 aluminium alloy Friction stir welding Tool rotation speed Welding speed Axial force Tensile strength

Fabrication of plain carbon steel/high chromium white cast iron bimetal by a liquid–solid composite casting process

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International Journal of minerals,metallurgy and materials 2015年第9期22卷 950-955页

作者： v.Javaheri H.Rastegari m.Naseri Division of Research and Development Isfahan Casting Industries Co.(ICI) Department of Engineering Birjand University of Technology

High-chromium white cast iron （HCWCI） is one of the most widely used engineering materials in the mining and cement industries. However, in some components, such as the pulverizer plates of ash mills, the poor machinability of HCWCI creates difficulties. The bimetal casting technique is a suitable method for improving the machinability of HCWCI by joining an easily machined layer of plain carbon steel （PCS） to its hard part. In this study, the possibility of PCS/HCWCI bimetal casting was investigated using sand casting. The investigation was conducted by optical and electron microscopy and non-destructive, impact toughness, and tensile tests. The hardness and chemical composition profiles on both sides of the interface were plotted in this study. The results indicated that a conventional and low-cost casting technique could be a reliable method for producing PCSYdCWCI bimetal. The interfacial microstructure comprised two distinct lay- ers： a very fine, partially spheroidized pearlite layer and a coarse full pearlite layer. moreover, characterization of the microstructure revealed that the interface was free of defects.

关键词： bimetals carbon steel cast iron casting interfaces microstructure mechanical properties

Photoluminescence,structural and antibacterial properties of co-dopedβ-Ca_(3)(PO_(4))_(2)-type phosphates Ca_(8)CuRE(PO_(4))_(7)(RE=Eu-Er)

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Journal of Rare Earths 2024年第9期42卷 1658-1668,I0002页

作者： Ivan v.Nikiforov Ekaterina v.Iliin Bogdan I.Lazoryak Sergey m.Aksenov Pavel v.Slukin Dina v.Deyneko Department of Chemistry Lomonosov Moscow State University119991MoscowRussia Laboratory of Arctic mineralogy and material Sciences Kola Science CentreRussian Academy of Sciences184209ApatityRussia Geological Institute Kola Science CentreRussian Academy of Sciences184209ApatityRussia State Scientific Center of Applied microbiology and Biotechnology of Rospotrebnadzor 24 Block A142279ObolenskRussia

Novel Ca_(8)CuRE(PO_(4))_(7)where RE^(3+)=Eu^(3+),Tb^(3+),Dy^(3+),Ho^(3+)and Er^(3+)were synthesized by a solid-state method in *** structures of the samples were characterized by powder X-ray diffraction using Rietveld refinement to determine the occupation of crystal *** samples are found to have a centrosymmetric structure with space group R3c,as shown by dielectric *** synthesized Ca_(8)CuRE(PO_(4))_(7)samples have multifunctional *** Cu^(2+)ions provide antibacterial properties,while the rare earth elements ions exhibit luminescence properties,and theβ-Ca_3(PO_(4))_(2)-type host is *** photoluminescence properties of RE^(3+)ions were studied and compared with other simmilar Ca_(8)mRE(PO_(4))_(7)phosphates,where m is a divalent *** photoluminescence intensity quenching in terms of energy transfer from RE^(3+)to Cu^(2+)is *** bioactive properties were studied in relation to antibacterial activity against *** and *** syntesized Ca_(8)CuRE(PO_(4))_(7)samples demonstrate very high and stable inhibition of bacteria *** correlation between crystal structure and properties is *** combining multiple approaches to the directio nal design of such materials,several important properties within a single chemical compound to achieve biovisualization and bioactive properties simultaneously can be combined.

关键词： β-Ca_(3)(PO_(4))_(2) Whitlockite-type structure Bioactive phosphates TCP Photoluminescence Rare earths

Biochemical Factors Affecting the Quality of Products and the Technology of Processing Deep-Sea Fish, the Giant Grenadier Albatrossia pectoralis

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Journal of Ocean University of China 2020年第3期19卷 681-690页

作者： PIvNENKO T.N. KARPENKO Yu.v. KRASHCHENKO v.v. POZDNYAKOvA Yu.m. ESIPENKO R.v. Far Eastern State Technical Fisheries University Vladivostok 690087Russia

The composition of muscle tissues of a deep-sea species, the giant grenadier(Albatrossia pectoralis), and a mesopelagic species, the Alaska pollock(Theragra chalcogramma), are compared. Grenadier is proved to have a higher moisture content(91.7%) and lower protein(7.4%) and lipid(0.3%) contents. The factors responsible for the softening and moisture separation during processing of grenadier are identified. Contents of some fractions of non-protein nitrogenous components, including trimethylamine oxide(TmAO) and free amino acids, are clarified. The proportion of the main myofibrillar proteins myosin and actin, which is considered as an indicator of efficiency of structure formation in fish muscle tissue during processing, is almost 20% lower in giant grenadier than in pollock. The effects of endogenous protease, Са^2+-ATPase and transglutaminase on the processes of autolysis, denaturation, and possibility of myofibrillar proteins cross-linking were also studied. The proposed technology of getting a nutritionally balanced, gel-like, ready-to-use foodstuff from grenadier fillet includes its enrichment with pollock muscle tissue and supplementing with a binary structure-forming agent containing collagen and chitosan. Nutritional value of the products is assessed by the method of biological assay and by determining the denaturation changes of myofibrillar proteins. The modes of fine mincing and thermal processing, as well as the shelf-life of the finished product are justified. The developed technology of producing a ready-to-eat food from giant grenadier will allow a more efficient use of this underutilized resource.

关键词： giant grenadier Alaska pollock myosin actin proteases ATPase transglutaminase softening structure formation ready-to-eat foodstuffs