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On the microstructural origin of premature failure of creep strength enhanced martensitic steels

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journal of Materials Science & Technology 2021年第28期87卷 269-279页

作者： j.Li c.Xu G.Zheng W.j.Dai c.c.Bu G.chen MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology Engineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing210094China Nanjing jiuzhu New Materials Institute co. Ltd.Nanjing211151China condensed Materials Laboratory co. Ltd.Yangzhou225200China Yangzhou chengde Steel Pipe co. Ltd.Yangzhou225200China

The creep strength enhanced martensitic steels are key material for the main power generating units in ultra-supercritical *** on the evaluation of their creep rupture life show there is an overestimation of rupture life after long-term creep,which is known as premature ***,the microstructural origin of the premature failure remains *** in this study,we have carefully investigated the microstructural transformations and their influences on creep rupture behavior,showing that the evolution of martensite and M_(23)c_(6) carbides as well as Laves phase are responsible for the premature *** using multi-step TTP-LMP method,we confirmed a three-stage creep rupture behavior under different stress *** quantitative analysis showed that the coarsening of M_(23)c_(6) carbides and recovery of martensite exert equal and dominant effects on the premature failure in the medium stress region,while precipitation and coarsening of Laves phase are responsible for the premature failure in the low stress region.

关键词： creep strength enhanced martensitic steel Premature failure M_(23)c_(6)carbides Martensite recovery Laves phase

Flow characteristics in a parallel-plate porous channel under convective boundary conditions and triple diffusion for the non-Darcy porous matrix

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Propulsion and Power Research 2021年第4期10卷 396-411页

作者： j.c.Umavathi department of Mathematics Gulbarga UniversityGulbarga585106KarnatakaIndia

This article inspects the effect of triple diffusion in a vertical conduit encapsulated with porous matrix and subjected to third kind boundary *** kind boundary condition is a combination of Dirichlet and Neumann boundary conditions which specifies a linear combination of function and its derivative values on the *** chemical reaction along with viscous and Darcy dissipation effects are *** the Boussinesq approximation,the soultal buoyancy effects due to concentration gradients of the dispersed components are taken into *** suitable transformations,the conservation equations are reduced into dimensionless form and the dimensionless parameters evolved are thermal Grashof number (0≤Λ_(1)≤20),solutal Grashof number(for species 1 and 2,0≤Λ_(2);Λ_(3)≤20),porous (2≤σ≤8) and inertial parameters (0≤Ι≤6),Biot numbers(at the left and right walls,1≤Bi_(1);Bi_(2)≤10),Brinkman number (0≤Br≤1),Schmidt numbers (0≤Sc_(1);Sc_(2)≤6),Soret numbers (Sr_(1) =Sr_(2) =1) and temperature difference ratio (R_(T) = 1).Adopting perturbation technique,the analytical solutions which are applicable only when the Brinkman number is less than one is *** for any values of the Brinkman number,Runge-Kutta shooting method is *** impact of selected parameters on the momentum,heat and dual species concentration fields are presented in the form of *** solutions computed by numerical method are justified by comparing with the analytical *** numerical and analytical solutions are equal in the absence of Darcy and viscous dissipations and the discrepancy advances as the Brinkman number *** the solutions obtained are also justified by comparing the results with Zanchini[1]in the absence of chemical reaction for clear *** thermal field is augmented with the Brinkman number for symmetric and asymmetric Biot *** the profiles are highly distinct at the cold plate for unequal Biot numbers

关键词： Mixed convection Robin boundary conditions Darcy-Forchheimer-Brinkman model Soret number Runge-Kutta shooting method

Measuring the condition of Saline Wetlands Threatened by Agricultural Intensification

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Pedosphere 2008年第1期18卷 11-23页

作者： c.cASTAEDA j.HERRERO j.HERRERO Soils and Irrigation department Agri-Research Center of AragonPO Box 72750080 Zaragoza (Spain)

The saline wetlands,or'saladas',of Monegros desert,NE Spain,contain biodiversity that depends on the estab- lishment of a prognostic monitoring system that can warn of approaching irreversible *** the context of a lack of existing biodiversity inventories for the saladas,we determined their state of conservation and vulnerability using seven physical indicators:escarpment continuity,cropping,stone dumping,size,water occurrence,distance to roads,and proximity to irrigated *** features were combined into three meaningful indexes,i.e.,conservation,current vulnerability,and future vulnerability,thus creating an assessment of the preservation or degradation of saladas in the context of encroaching agricultural irrigation *** proposed indexes produced consistent results and showed that a great number of the Monegros wetlands were threatened,regardless of their size or frequency of water *** 20% of the saladas studied were classified as being in a good or very good conservation,whereas 50% were in bad or very bad shape.A high current vulnerability was found for 60% of the *** saladas located in land to be irrigated, we predicted that 73% would have a high or very high future ***,58% of the saladas were in bad or very bad condition and fully 65% of the saladas,variable in size,presented a bad or very bad *** approach provides a monitoring strategy for the conservation of saline wetlands threatened by agricultural intensification,especially irrigation.

关键词： agricultural landscape desert irrigation Monegros playa

State of the Art on Micromilling of Materials,a Review

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journal of Materials Science & Technology 2012年第8期28卷 673-685页

作者： M.A.cmara j.c. campos Rubio A.M. Abro j.P. Davim department of Mechanical Engineering Universidade Federal de Minas GeraisAv.Ant onio Carlos6627-Pampulha Belo Horizonte MGCEP:31.270-901Brazil department of Mechanical Engineering University of AveiroCampus Universitrio de Santiago3810-193AveiroPortugal

The trend towards miniaturization has increased dramatically over the last decade, especially within the fields concerned with bioengineering, microelectronics, and aerospace. Micromillin8 is among the principal manu- facturing processes which have allowed the development of components possessing micrometric dimensions, being used to the manufacture of both forming tools and the final product. The aim of this work is to present the principal aspects related to this technology, with emphasis on the work material requirements, tool ma- terials and geometry, cutting forces and temperature, quality of the finished product, process modelling and monitoring and machine tool requirements. It can be noticed that size effect possesses a relevant role with regard to the selection of both work material （grain size） and tooling （edge radius）. Low forces and temper- ature are recorded during micromillin8, however, the specific cutting force may reach high values because of the ploughing effect observed as the uncut chip thickness is reduced. Finally, burr formation is the principal concern with regard to the quality of the finished part.

关键词： Micro-milling Micromachining Size effect Miniaturization

Responses of Iron-Reducing Bacteria to Salinity and Organic Matter Amendment in Paddy Soils of Thailand

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Pedosphere 2012年第3期22卷 375-393页

作者： A.j.BONGOUA-deVISME c.MUSTIN j.BERTHELIN Laboratory of Microorganism-Mineral-Organic Matter interactions in Soil (LIMOS) Nancy-UniversityB.P.7023954506 Vandoeuvre-les-Nancy (France) National center of Scientific Research (cNRS)-Laboratory of Microorganism-Mineral-Organic Matter Interactions in Soil (LIMOS) UMR 7137CNRSNancy-UniversityB.P.7023954506 Vandoeuvre-les-Nancy (France)

In paddy soils of Thailand, the addition of organic matter （OM） is used to efficiently limit the effect of salinity on rice culture and production. OM used as an amendment and fertilizer promotes the reduced condition and increases iron solubilization without provoking ferrous toxicity. In this study, the intricate biogeochemical role of iron-reducing bacteria （IRB） involved in the quality of water and soil of paddy fields, particularly when the paddy fields were subject to salinity and organic matter addition, were studied in paddy fields of Thailand. The results demonstrated that the addition of OM increased the proliferation of cultivable IRB and their specific activity. cultivable IRB communities decreased in the presence of salt. The presence of salt modified the structure of the bacterial populations by favoring the development of alkaline and moderately halophilic bacteria （Virgibacillus spp., Occanobacillus spp., and PaenibaciUus spp.）. The paddy soils studied contained very diversified （halosensitive, halotolerant, and halophilic） IRB populations that could be adapted to a variety of salinity conditions （0-90 g L-1 NacI） using different organic substrates （glucose, acetate, and soil organic matter） to maintain significant activities under extreme conditions of salinity. The rhizosphere of rice stimulated IRB community growth without organic matter, whereas organic matter addition limited the rhizosphere effect on IRB cultivable number in saline condition. The interactive action of salinity and organic amendment had a negative impact on the rhizosphere effect. The presence of specific iron-reducing populations （fermentative, iron-respiring, anaerobic, and facultative anaerobic）, having different behaviors under salt and redox stresses, appeared to be a key factor that contributed to the control or enhancement of the quality of water and soil in paddy fields.

关键词： bacterial communities bacterial populations organic substrates paddy fields rhizosphere

Mixed convection flow in vertical channel with boundary conditions of third kind in presence of heat source/sink

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Applied Mathematics and Mechanics(English Edition) 2012年第8期33卷 1015-1034页

作者： j.c.UMAVATHI j.PRATHAP KUMAR jAWERIYA SULTANA department of Mathematics Gulbarga UniversityGulbarga 585106KarnatakaIndia

The effects of viscous dissipation and heat source/sink on fully developed mixed convection for the laminar flow in a parallel-plate vertical channel are investigated. The plate exchanges heat with an external fluid. Both conditions of equal and different reference temperatures of the external fluid are considered. First, the simple cases of the negligible Brinkman number or the negligible Grashof number are solved analytically. Then, the combined effects of buoyancy forces and viscous dissipation in the presence of heat source/sink are analyzed by a perturbation series method valid for small values of the perturbation parameter. To relax the conditions on the perturbation parameter, the velocity and temperature fields are solved by using the Runge-Kutta fourth-order method with the shooting technique. The velocity, temperature, skin friction, and Nusselt num- bers at the plates are discussed numerically and presented through graphs.

关键词： mixed convection viscous fluid perturbation method Runge-Kuttashooting method heat source/sink

The removal of arsenic from (ground)-water by adsorbent loaded in polymeric microspheres

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journal of Harbin Institute of Technology(New Series) 2012年第1期19卷 63-66页

作者： FIGOLI A HOINKIS j cRIScUOLI A FRANZ c de RYcKE M BLOcK c deOWAN S A ISLAM R DRIOLI E Institute on Membrane Technology (ITM-cNR) Via Pietro BucciCubo 17C87030 Rende ( CS) Italya Karlshrue University of Applied Sciences Moltkestr. 30 76133KarlshrueGermany Sustainable Process Materials Engineering GROUP T-Leuven Engineering CollegeVesaliusstraat 133000 LeuvenBelgium

Arsenic is a natural tasteless and odourless element,existing in the earth's crust at average levels of between two and five thousands micrograms per liter (parts per million) . Arsenic is highly toxic to humans, who are exposed to it primarily from air,food and water. The occurrence of arsenic in groundwater is due to geological composition of soil. High concentrations of arsenic in water are the result of dissolution or desorption of ferric oxides and the oxidation of mineral arsenopyrites. Arsenic in drinking water has an important impact on the human health,especially in the less developed countries. Different methods exist to remove arsenic from aquatic media,and one of them is by adsorption. In this work,the adsorption of both As(III) and As(V) by means of novel microspheres has been investigated. In particular,TiO2 has been embedded into polymeric microspheres PES (PolyEtherSulphone) and PEEK-Wc (PolyEtherEther-Ketone) . The main advantages of this encapsulation adsorption material are: no loss of adsorbents into the water stream,easy to be used and scaled-up.

关键词： arsenic removal adsorption TiO2 polymeric microspheres

Mechanical Properties and defective Effects of 316LN Stainless Steel by First-Principles Simulations

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journal of Materials Science & Technology 2011年第11期27卷 1029-1033页

作者： X.Q. Li j.j. Zhao j.c. Xu X. Liu Key Laboratory of Materials Modification by Laser Ion and Electron Beams Ministry of Education Dalian University of Technology Dalian 116024 China college of Advanced Science and Technology Dalian University of Technology Dalian 116024 China School of chemical Engineering Dalian University of Technology Dalian 116024 China

In current International Thermonuclear Experimental Reactor （ITER） design, the 316LN austenitic stainless steel （316LN SS） is used for first-wall/blanket structures. Thus, it is necessary to study the fundamental mechanical properties and irradiation effect of 316LN SS. A random solid solution model of Fe-cr-Ni-Mn- Mo-Si alloy is used for describing 310LN S$. Using first-principles approaches, the elastic constants and ideal strength of the alloy were calculated. Such alloy exhibits good ductile behavior according to the theoretical values of cauchy pressure and ratio of bulk modulus and shear modulus. Within the 256-atom supercell, inclusion of single vacancy defect further enhances the ductility of the alloy, and the existence of interstitial （Fe, H, He） atoms enhances the Young＇s modulus.

关键词： Stainless steel Mechanical properties Vacancy Interstitial

A Dimension-Reduction Interval Analysis Method for Uncertain Problems

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computer Modeling in Engineering & Sciences 2017年第3期113卷 239-259页

作者： j.c.Tang c.M.Fu State Key Laboratory of Advanced design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha City410082P.R.China college of Mechanical Engineering University of South ChinaHengyang 421001P.R.China

In this paper,an efficient interval analysis method called dimension-reduction interval analysis(DRIA)method is proposed to calculate the bounds of response functions with interval variables,which provides a kind of solution method for uncertainty analysis problems of complex structures and ***,multi-dimensional function is transformed into multiple one-dimensional functions by extending dimension reduction method to the interval analysis ***,all the one-dimensional functions are transformed to standard quadratic form by second order Taylor expansion *** a result,the multi-dimensional function is approximately represented by the functions that each interval variable occurs once,and interval power arithmetic can be used to efficiently calculate the bounds of response functions in restricted ***,three numerical examples and an engineering application are investigated to demonstrate the validity of the proposed method.

关键词： Interval uncertainty interval analysis dimension-reduction method over estimation