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Chinese Physics Letters 2007年第9期24卷 2639-2641页

作者： B.I.GULIYEV r.f.EMINBEYLI A. KOrKUT Yuzuncii Yll University Art and Science Faculty Physics Department 65080 Van Turkey

The fermi energy, cyclotron energy and cyclotron effective mass of degenerate electron gas in a sizeoquantized semiconductor thin film with non-parabolic energy bands are studied. The influences of quantizing magnetic field on these quantities in two-band approximation of the Kane model are investigated. It is shown that the fermi energy oscillates in a magnetic field. The period and positions of these oscillations are found as a function of film thickness and concentration of electrons. Cyclotron energy and cyclotron effective mass are investigated as a function of film thickness in detail The results obtained here are compared with experimental data on GaAs quantum wells.

关键词： coated conductor buffer layer self-epitaxy CeO2

Appraisal of the structure and facilities available in selected pig farm houses in Ondo State

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International Journal of Agricultural and Biological Engineering 2011年第2期4卷 59-63页

作者： f r falayi Department of Agricultural Engineering Federal University of TechnologyAkure Ondo StateNigeria

A study was carried out to evaluate various pig housing units in six selected local government areas of Ondo State,specifically for their structural deficiencies and their effects on animal *** pig farmers were visited in each of the local *** were administered and on the spot assessments of the housing systems and facilities and state of health of the animals were carried *** data obtained were coded accordingly and were subjected to appropriate statistical *** was observed that intensive system of housing is mostly practised and it constituted about 60%,semi-intensive housing method were about 17%and 23%were the extensive system *** level of pig rearing is very low in the state;about 23%of the total number of farms kept between 11 and 20 pigs while less than 4%kept above 100 ***,twelve farms kept exotic breed and nine farms kept local or indigenous breed,that is,40%and 30%*** of the farms visited were infested with diseases that were identified as skin diseases,worm and swine *** were also losses due to high piglet mortality *** housing units were not properly constructed and had leaking roof due to weak construction materials used and the pattern of *** were not cemented and there were inadequate provision of wallowing and feeding *** is concluded that the problems encountered by the pig farmers in the study area was directly linked with structurally inadequate housing unit and it is therefore recommended that the housing units should be properly constructed with new corrugated zinc,well cemented floor and there should be adequate provision of wallowing units and feeding *** are advised to make use the services of professionals such as agricultural engineers who specialises in farm structure for the design and construction of their farm structures.

关键词： pig housing wallowing diseases skin

Highly electroactive N–fe hydrothermal carbons and carbon nanotubes for the oxygen reduction reaction

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Journal of Energy Chemistry 2020年第11期29卷 260-270页

作者： r.G.Morais N.rey-raap J.L.figueiredo M.f.r.Pereira Associate Laboratory LSrE-LCM Departamento de Engenharia QuimicaFaculdade de EngenhariaUniversidade do PortoR.Dr.Roberto Frias s/n4200-465PortoPortugal

Glucose-derived carbons were prepared by hydrothermal carbonization of glucose followed by carbonization or activation to obtain carbon materials with different microporosities. These microporous carbons and carbon nanotubes(CNTs) were functionalized with melamine and/or iron(Ⅱ) phthalocyanine(fePc)following three different methodologies:(i) functionalization with melamine via thermal treatment,(ii)incorporation of the lowest amount of fePc reported in the literature via incipient wetness impregnation followed by thermal treatment and(iii) functionalization with melamine followed by fe Pc *** chemical and textural characterization of the prepared materials and their electrochemical assessment allowed to understand the role of microporosity in the incorporation of fePc and its effect on the oxygen reduction reaction(Orr). It was observed that fePc was preferentially incorporated inside the porous structure, especially in samples with more developed microporosity. However, functionalization with melamine modified the textural properties and the surface chemistry, favoring the incorporation of fePc on the surface. regarding the electrochemical performance, the presence of fePc greatly enhanced the electroactivity of the microporous catalysts. An onset potential of 0.88 V and a four-electron pathway were obtained for glucose-derived carbons, whereas the limiting current densities and kinetic current densities rose by 126% and 222%, respectively, in comparison to the base sample. Notwithstanding, the highest electrochemical activity was observed for the sample prepared with CNTs, due to the synergy between the active metal centers and their highly graphitic carbon structure. The electrochemical parameters of CNTfeP csurpass the commercial Pt/C. The half-wave potential is 40 mV higher, the limiting current density increases by 17%, and a negligible production of by-products(rved.

关键词： Iron(Ⅱ)phthalocyanine Hydrothermal carbons Carbon nanotubes Oxygen reduction reaction Electrocatalysis

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

Enhanced Photocatalytic Activity in p-NiO Grafted n-TiO_2 Porous Coatings

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Journal of Materials Science & Technology 2015年第4期31卷 355-360页

作者： S.Bassaki H.Niazi f.Golestani-fard r.Naghizadeh r.Bayati School of Metallurgy and Materials Engineering Iran University of Science and Technology Intel Corporation

We synthesized NiO-loaded TiO2porous p-n junctions by electrophoretic enhanced micro arc oxidation（EEMAO） technique which is a relatively simple and new method for producing composite *** structure,chemical composition,and surface morphology of the NiO—TiO2coatings were investigated by X-ray diffraction（XrD）,X-ray photoelectron spectroscopy（XPS）,and scanning electron microscopy（SEM） techniques,*** efficiency of the samples was studied through measuring the decomposition rate of 4-chlorophenol under UV *** showed that the coatings mainly consisted of anatase,rutile,and nickel oxide *** was observed that a finer surface morphology,*** pores,was obtained at lower ***,the amount of nickel oxide loaded to the TiO2host increased with the *** NiO-TiO2composite coatings showed a higher photoactivity than pure TiO2coatings revealing the effective role of NiO in decreasing the recombination rate of photogenerated electrons and *** maximum photocatalytic reaction rate constants for TiO2and NiO—TiO2samples were obtained as 0.0064 and 0.0131 min-1,*** also found that there was an optimum concentration of NiO where a maximum photocatalytic activity was achieved.A correlation between growth variables,structure,and photocatalytic efficiency was established.

关键词： Nickel oxide Titanium dioxide p-n junctions Photoc

Electricity Tariff Aware Model Predictive Controller for Customer Battery Storage with Uncertain Daily Cycling Load

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Journal of Modern Power Systems and Clean Energy 2022年第1期10卷 140-148页

作者： Dejan P.Jovanović Gerard f.Ledwich Geoffrey r.Walker Institute of Electrical and Electronic Engineers QueenslandAustralia School of Electrical Engineering and robotics Queensland University of TechnologyBrisbaneAustralia

To optimally control the energy storage system of the battery exposed to the volatile daily cycling load and electricity tariffs,a novel modification of a conventional model predictive control is *** uncertainty of daily cycling load prompts the need to design a new cost function which is able to quantify the associated *** modelling a probabilistic dependence among flow,load,and electricity tariffs,the expected cost function is obtained and used in the constrained *** proposed control strategy explicitly incorporates the cycling nature of customer ***,for daily cycling load,a fixed-end time and a fixed-end output problem are *** is demonstrated that the proposed control strategy is a convex optimization *** stochastic and robust model predictive controllers evaluate the cost concerning model constraints and parameter ***,the expected cost across the flow variations is *** density function of load probability improves load prediction over a progressive prediction horizon,and a nonlinear battery model is utilized.

关键词： residential energy systems battery storage model predictive control nonlinear optimization cost of daily electricity consumption

Microstructural development and mechanical properties of drop tube atomized Al-2.85 wt%fe

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Journal of Materials Science & Technology 2022年第9期104卷 41-51页

作者： Mehmet r.Abul robert f.Cochrane Andrew M.Mullis School of Chemical&Process Engineering University of LeedsLeeds LS29JTUK

Al-2.85 wt%fe alloy has been subjected to non-equilibrium container-less solidification using a 6.5 m drop *** samples were collected and sieved into 7 sizes fractions ranging from 850μm to 53μm,with the estimated cooling rates being 150 to 11000 K s^(-1)*** analysis was employed on all droplet size fractions for identification and evolution of the phases,showing that Al,Al_(6)fe and Al_(13)fe_(4)were formed for all sizes while Al_(5)fe_(2)was observed only in droplets≤150μm in *** evaluation was conducted by using SEM and optical microscopy,showing that droplet larger than 300μm in diameter exhibited distinct morphologies;microcellular,dendriticα-Al with inter-dendritic Al_(13)fe_(4)eutectic and an AI-Al_(6)fe eutectic *** increasing cooling rate,the Al-Al_(6)fe region *** analysis reveals that increasing the cooling rate increased the dissolved fe content inα-Al from 0.37 wt%fe to 1.105 wt%fe,and correspondingly the eutectic fraction decreased from 49.7 vol.%to 26.7 vol.%.Measurement of the lamellar spacing allowed the eutectic growth velocity and interfacial undercooling to be calculated,wherein the Al-rich boundary of the eutectic coupled zone could be *** shows a coupled zone skewed significantly towards the intermetallic side of the *** order to understand the effect of non-equilibrium the solidification on the mechanical properties micro hardness of the droplets was *** micro-hardness has risen from 55.3 HV_(0.01)to 66.5 HV_(0.01)for≥850μm and≤75μm droplets,respectively.

关键词： Al-fe alloys Container-less solidification Microstructure TEM Micro-hardness

remarkably high fracture toughness of HfNbTaTiZr refractory high-entropy alloy

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Journal of Materials Science & Technology 2022年第28期123卷 70-77页

作者： X.J.fan r.T.Qu Z.f.Zhang Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Nano Science and Technology Institute University of Science and Technology of ChinaSuzhou 215132China

High-entropy alloys(HEAs)with face-centered cubic(fCC)phase such as CoCrfeMnNi or CoCrNi generally exhibit ultra-high fracture toughness but relatively low *** contrast,body-centered cubic(BCC)HEAs often display higher strengths,but the few reports on fracture toughness measurement demonstrate low toughness *** we show that the BCC HfNbTaTiZr refractory HEA,which possesses a combination of high strength,good tensile ductility and excellent high-temperature properties,also exhibits a remarkably high fracture *** using the"single specimen"compliance method for J-integral measurement according to the ASTM E1820–17 standard,its fracture toughness K_(JIC)was experimentally determined to be 210 MPa m^(1/2),which renders this HEA among the toughest metallic *** excellent damage tolerance makes the HEA promising for applications as high-temperature structural materials such as in aerospace field.

关键词： High-entropy alloys BCC structure fracture toughness J-integral

Modelling a Skin-Pass rolling Process by Means of Data Mining Techniques and finite Element Method

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Journal of Iron and Steel research International 2012年第5期19卷 43-49页

作者： r Escribano r Lostado f J Martínez-de-Pisón A Pernía E Vergara EDMANS Group Mechanical Engineering Department of the University of La Rioja Logroo 26004 La Rioja Spain

An experience is presented using the finite element method （fEM） and data mining （DM） techniques to develop models that can be used to optimieze the skin-pass rolling process based on its operating conditions. A fE model based on a real skin-pass process is built and validated. Based on this model, a group of fE models is simulated with different adjustment parameters and with different materials for the sheet; both variables are chosen from pre-set ranges, from all fE model simulations, a database is generated; this database is made up of the above mentioned adjustment parameters, sheet properties and the variables of the process arising from the simulation of the model. Various types of data mining algorithms are used to develop predictive models for each of the variables of the *** best predictive models can be used to predict experimentally hard-to-measure variables （internal stresses, internal straine, etc.） which are useful in the optimal design of the process or to be applied in real time control systems of a skin-pass process in -plant.

关键词： skin-pass rolling predictive model finite element method data mining

A rANS-Vof Numerical Model to Analyze the Output Power of An OWC-WEC Equipped with Wells and Impulse Turbines in A Hypothetical Sea-State

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China Ocean Engineering 2020年第6期34卷 760-771页

作者： Paulo r.f.Teixeira rafael A.A.C.Gonçalves Eric Didier Engineering School Universidade Federal do Rio Grande-FURGRio GrandeRS 96203-900Brazil Harbours and Maritime Structures Division Hydraulics and Environment DepartmentLaboratório Nacional de Engenharia Civil-LNECLisbon 1700-066Portugal

Wave energy is a renewable source with significant amount in relation to the global demand. A good concept of a device applied to extract this type of energy is the onshore oscillating water column wave energy converter(OWC-WEC). This study shows a numerical analysis of the diameter determination of two types of turbines, Wells and Impulse, installed in an onshore OWC device subjected to a hypothetical sea state. Commercial software fLUENT?,which is based on rANS-Vof(reynolds-Averaged Navier-Stokes equations and Volume of fluid technique), is employed. A methodology that imposes air pressure on the chamber, considering the air compressibility effect, is used. The mathematical domain consists of a 10 m deep flume with a 10 m long and 10 m wide OWC chamber at its end(geometry is similar to that of the Pico's plant installed in Azores islands, Portugal). On the top of the chamber, a turbine works with air exhalation and inhalation induced by the water free surface which oscillates due to the incident wave. The hypothetical sea state, represented by a group of regular waves with periods from 6 to 12 s and heights from 1.00 to 2.00 m(each wave with an occurrence frequency), is considered to show the potential of the presented methodology. Maximum efficiency(relation between the average output and incident wave powers) of46% was obtained by using a Wells turbine with the diameter of 2.25 m, whereas the efficiency was 44% by an Impulse turbine with the diameter of 1.70 m.

关键词： wave energy oscillating water column Wells turbine Impulse turbine rANS-Vof compressible air