检索结果-南通市图书馆

Progress in Natural Science:Materials International 2019年第2期29卷 198-209页

作者： H.Felhi M.Smari a.bajorek K.Nouri E.Dhahri L.Bessais Applied Physics Laboratory Sfax Faculty of Sciences University of Sfax Center for Functionalized Magnetic Materials (FunMagMa) Immanuel Kant Baltic Federal University A.Che?kowski Institute of Physics University of Silesia in Katowice Silesian Center for Education and Interdisciplinary Research University of Silesia in Katowice CMTR ICMPE UMR 7182 CNRS-UPEC

In this work, a novel series of multiferroic materials BiMn2O5doped by Neodyme has been prepared by a sol-gel method at low temperature. The crystallographic studies using X-ray diffraction and Rietveld Refinement techniques showed the formation of single-phase samples for all compositions, crystallizing in a mullite-type orthorhombic perovskite structure, space group Pbam(Z = 4). The SEM techniques confirmed the formation of single-phase materials with excellent mapping distribution. Raman and infrared spectroscopic measurements were performed and combined with lattice dynamics simulations to describe the room-temperature vibrational properties of all samples. The X-ray Photoelectron Spectroscopy(XPS) were measured in the energy range of 0–1400 eV at room temperature. The Fermi level EFwas defined with the accuracy of 0.127, 0.32 and 0.48 eV for BiMn2O5, Bi0.9Nd0.1Mn2O5and Bi0.8Nd0.2Mn2O5respectively. The X-ray photoelectron spectroscopy shows the existence of Mn4+state. Magnetic measurements indicate Neél temperature TNat 31, 40 and 61 K for BiMn2O5,Bi0.9Nd0.1Mn2O5and Bi0.8Nd0.2Mn2O5respectively.

关键词： Multiferroics X-ray photoelectron spectroscopy Fermi level Magnetic properties

Microstructure and electrical resistivity in the GdNi_(5–x)Cu_x intermetallic series

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Rare Earths 2017年第1期35卷 71-78页

作者： Anna.bajorek Grazyna Chelkowska A. Chelkowski Institute of Physics University of Silesia Katowice Poland Silesian Center for Education and Interdisciplinary Research University of Silesia Chorzow Poland

The effect of the Ni/Cu substitution on the electrical resistivity and microstructure of the polycrystalline GdNi5-xCux series was studied. The value of temperature of phase transition（T_（ph）） estimated from temperature dependence of electrical resistance varied non-linearly across copper doping from 32.5 K（x=0.0） to 29.1 K（x=5.0）. The value of residual resistivity（ρo） estimated at low temperature range decreased from 27.28 μΩcm（x=0.0） to 9.44 μΩcm（x=5.0）, which was discussed as the influence of microstructure. In order to describe the temperature dependence of resistivity ρ（T） a variety of approaches were applied due to different scattering mechanisms occurring at high and low temperature ranges. The change within ρ（T） curvature was evidenced at low temperature range across copper doping. The temperature variation of the resistivity was quite peculiar for Cu-rich compounds（x=4.8, x=5.0）, which might be correlated with the incommensurate magnetic structure derived from the weakly negative interaction between the nearest neighbours of Gd. The correlation between microstructure and resistivity was observed.

关键词： intermetallics rare earth alloys and compounds crystal structure electrical resistivity scanning electron microscopy

Analysis and Identification of Corona Parameters on Overhead Power Lines in Case of Direct Lightning Strikes

在线全文

学校读者我要写书评

暂无评论

高电压技术 2013年第8期39卷 1988-1994页

作者： bajorek J Maslowski G Ziemba R Department of Electrical and Computer Engineering Rzeszow University of Technology Rzeszow Poland

This paper presents a method for determining specific models of overhead power lines with presence of corona phenomenon. The obtained models provide stable numerical solutions for computer simulation of transients caused by direct lightning strikes. The corona non- linear charge-voltage characteristics obtained from experimental tests are used for identification of the corona parameters based on System Identification Toolbox implemented in Matlab package. Different transfer functions, which give the same waveshapes of overvoltages are de- termined using two parametric models. A circuit representation of the obtained transfer functions is proposed and the corona model is implemented in the EMTP-RV as a hierarchical structure composed of a overhead power line divided into sections with corona branches. Some computer simulations of lightning overvoltages propagated in a typical 220 kV power line due to direct lightning strikes to a line tower are presented. The proposed method and the model implemented in EMTP-RV are still valid for multi-conductor lines and for higher voltages of power lines but new corona nonlinear charge-voltage characteristics are required as an input parameter for the identification procedure.

关键词：架空电力线路直接雷击电晕系统辨识工具箱计算机模拟非线性特性参数模型鉴定

Corrosion study of resorbable Ca60Mg15Zn25 bulk metallic glasses in physiological fluids

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2017年第5期27卷 627-634页

作者： Rafa? Babilas Anna.bajorek Adrian Radoń Ryszard Nowosielski Institute of Engineering Materials and Biomaterials Silesian University of Technology A.Chelkowski Institute of Physics University of Silesia

The corrosion activity of amorphous plates of Ca60Mg15Zn25alloy was *** biocompatible elements were selected for the alloy *** electrochemical corrosion and immersion tests were carried out in a multi-electrolyte fluid and Ringer's *** corrosion behavior was observed for the samples tested in a multi-electrolyte fluid despite the active dissolution of Ca and Mg in Ringer's *** experimental results indicated that reducing concentration of NaCl from 8.6 g/dm3for Ringer's solution to 5.75 g/dm3caused the decrease of the corrosion *** volume of the hydrogen evolved after 480 min in Ringer's solution（40.1 ml/cm2）was higher in comparison with that obtained in a multi-electrolyte fluid（24.4 ml/cm2）.The values of opencircuit potential(EOCP)for the Ca60Mg15Zn25glass after 1 h incubation in Ringer's solution and a multielectrolyte fluid were determined to be-1553 and-1536 m V vs.a saturated calomel electrode（SCE）.The electrochemical measurements indicated a shift of the corrosion current density(jcorr)from 1062μA/cm2for the sample tested in Ringer's solution to 788μA/cm2for the specimen immersed in a multi-electrolyte *** corrosion products analysis was conducted by using the X-ray photoelectron spectroscopy（XPS）.The corrosion products were identified to be CaCO3,Mg（OH）2,CaO,MgO and Zn *** mechanism of corrosion process was proposed and described based on the microscopic *** X-ray diffraction and Fourier transform infrared spectroscopy（FTIR）also indicated that Ca（OH）2,CaCO3,Zn（OH）2and Ca(Zn（OH）3)2·2H2O mainly formed on the surface of the studied alloy.

关键词： Ca-based metallic glasses X-ray photoelectron spectroscopy FTIR spectroscopy X-ray diffraction Corrosion resistance Hydrogen evaluation

Modeling of Nonlinear Elements During Lightning Overvoltage Simulations

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

高电压技术 2008年第12期34卷 2595-2601页

作者： J. bajorek M. Korzeniowski G. Maslowski R. Ziemba Rzeszow University of Technology W. Pola 2 35-959 Rzeszow Poland

The paper presents some problems of lightning overvoltage modeling in transmission lines with nonlinear *** presented results were obtained mostly for fast front transients of subsequent lightning return stroke *** effectiveness of numerical algorithms of nonlinear models and possibilities of their development for such transients are *** simulations carried out by application of EMTP show that nonlinear models of back-flashover and ZnO arresters work properly,while the implemented corona model can not be used for relatively large peak values of subsequent lightning return-stroke currents.

关键词：雷电过电压仿真非线性无件模型

Structure and corrosion resistance of Al–Cu–Fe alloys

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2020年第3期30卷 393-401页

作者： Rafa? Babilas Anna.bajorek Monika Spilka Adrian Radoń Wojciech ?oński Department of Engineering Materials and Biomaterials Silesian University of Technology Institute of Physics University of Silesia in Katowice ?ukasiewicz Research Network-Institute of Non-Ferrous Metals

The microstructure and electrochemical properties of Al–Cu–Fe alloys with the atomic compositions of Al65Cu20Fe15,Al78Cu7Fe15and Al80Cu5Fe14Si1have been *** alloys were produced by induction melting of pure elements with copper mold *** microstructure of the alloys was analyzed by X-ray diffraction and high-resolution transmission electron *** formation of quasicrystalline phases in the Al–Cu–Fe alloys was *** presence of intermetallic phases was observed in the alloys after crystallization in a form of ingots and *** electrochemical measurements were conducted in 3.5%NaCl *** electronic structure of the alloys was determined by X-ray photoelectron *** post corrosion surface of the samples was checked using a scanning electron microscope equipped with the energydispersive X-ray *** was observed that the Al65Cu20Fe15alloy had the highest corrosion *** improved corrosion resistance parameters were noted for the plate samples rather than those in the as-cast *** the hardness of the Al65Cu20Fe15alloy was significantly higher than the other alloy samples.

关键词： Al-Cu-Fe alloys Copper mold casting X-ray diffraction High-resolution transmission electron microscopy X-ray photon spectroscopy Electrochemical impedance spectroscopy

Testing of Lightning Protective System of a Residential Structure： Comparison of Data Obtained in Rocket-triggered Lightning and Current Surge Generator Experiments

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

高电压技术 2008年第12期34卷 2575-2582页

作者： G. Maslowski V.A. Rakov S. Wyderka J. bajorek B.A. DeCarlo J. Jerauld G.H. Schnetzer J. Schoene M.A. Uman K.J. Rambo D.M. Jordan W. Krata Rzeszow University of Technology Rzeszow 35-959 Poland University of Florida Gainesville 32611 USA

We present a comparison of data obtained during testing of lightning protective system of a residential structure in rocket-triggered lightning experiment at the International Center for Lightning Research and Testing(ICLRT)at Camp Blanding,Florida,and current surge generator experiment at Rzeszow University of Technology in *** different configurations of LPS were tested in Poland with the dc grounding resistances of the entire system 4.09 Ω(LPS 1a),1.65 Ω(LPS 1b),and 2.88 Ω(LPS 2).For LPS 1a with three ground rods the value of the peak current entering the electrical circuit neutral was about 56% of the injected current peak,and for LPS 1b with two additional ground rods and two 5 m long buried horizontal conductors it was about 16%.For LPS 2 with five ground rods interconnected by a buried loop conductor this ratio was 21%.The current waveshapes in the ground rods differed from the injected current waveshapes and the current waveshapes in other parts of the test system,especially,for poorer-grounding LPS *** surge-generator results are consistent with those of triggered-lightning experiments at Camp Blanding,Florida(DeCarlo et al.,2008 [2]).

关键词：居民区雷电保护系统试验电流冲击发生器