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International Journal of minerals,metallurgy and materials 2019年第2期26卷 210-221页

作者： P.Subramani m.manikandan School of mechanical Engineering Vellore Institute of Technology

Weldments were produced using gas tungsten arc welding(GTAW) and pulsed current gas tungsten arc welding(PcGTAW) techniques with ERNicr-3 filler wire. macro examination revealed that the resultant weldments were free from defects. A refined microstructure was observed in the weldment fabricated through PcGTAW. Scanning electron microscopy(SEm) analysis revealed secondary phases in the grain boundaries. Energy-dispersive X-ray spectroscopy(EDS) analysis revealed that microsegregation of cr carbide precipitates was completely eradicated through PcGTAW. The microsegregation of Nb precipitates was observed in the GTA and PcGTA weldments. X-ray diffraction(XRD) analysis revealed the existence of m_(23)c?_6 cr-rich carbide and Ni_8Nb phases in the GTA weldments. By contrast, in the PcGTA weldments, the Ni_8Nb phase was observed. The cr_2Ti phase was observed in both the GTA and the PcGTA weldments. Tensile tests showed that the strength and ductility of the PcGTA weldments were slightly higher than those of the GTA weldments.

关键词： Ni-based superalloy welding pulse current microsegregation chromium carbide

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极具工程化潜力的好氧颗粒污泥技术

中国给水排水 2006年第8期22卷 1-7页

作者：郝晓地陈新华戴吉 m.de Kreuk m.c.m.van Loosdrecht 北京建筑工程学院可持续环境生物技术研发中心北京100044 代尔夫特理工大学Kluyver生物技术实验室

介绍了形成好氧颗粒污泥的工艺条件及其在去除有机物、脱氮、除磷方面的最新研究进展,并总结了好氧颗粒污泥的代谢机理。与传统的活性污泥法相比,好氧颗粒污泥反应器具有微生物浓度高、沉淀速度快、占地面积小等独特优点,在未来几年内... 详细信息

介绍了形成好氧颗粒污泥的工艺条件及其在去除有机物、脱氮、除磷方面的最新研究进展,并总结了好氧颗粒污泥的代谢机理。与传统的活性污泥法相比,好氧颗粒污泥反应器具有微生物浓度高、沉淀速度快、占地面积小等独特优点,在未来几年内该技术将得到实际应用。

关键词：好氧颗粒污泥序批式反应器溶解氧有机物负荷率

Investigation of effect of near-fault motions on substandard bridge structures

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Earthquake Engineering and Engineering Vibration 2011年第1期10卷 1-11页

作者： Austin Brown m. Saiid Saiidi Dynamic certification Laboratories Department of civil & Environmental Engineering

The objective of this study was to investigate the effects of near-fault ground motions on substandard bridge columns and piers. To accomplish these goals, several large scale reinforced concrete models were constructed and tested on a shake table using near- and far-field ground motion records. Because the input earthquakes for the test models had different characteristics, three different measures were used to evaluate the effect of the input earthquake. These measures are peak shake table acceleration, spectral acceleration at the fundamental period of the test specimens, and the specimen drift ratios. For each measure, force-displacement relationships, strains, curvatures, drift ratios, and visual damage were evaluated. Results showed that regardless of the measure of input or response, the near-fault record generally led to larger strains, curvatures, and drift ratios. Furthermore, residual displacements were small compared to those for columns meeting current seismic code requirements.

关键词： near-fault reinforced concrete bridge columns dynamic response

Structural,morphological and optical properties of new Eu-doped and vacancied lead molybdato-tungstates

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Journal of Rare Earths 2018年第6期36卷 635-641页

作者： m.Piotkowska E.Tomaszewicz Faculty of chemical Technology and Engineering Department of Inorganic and Analytical ChemistryWest Pomeranian University of TechnologySzczecinAI.Piast6w 4271-065 SzczecinPoland

A new tetragonal,scheelite-type Pb_(1-3 x)■_xEU_(2 x)(moO_4)_(1-3 x)(WO_4)_(3 x)(0 3 eV) and their band gap nonlinearly decreases with increasing dopant concentration.

A new tetragonal,scheelite-type Pb_(1-3 x)■_xEU_(2 x)(moO_4)_(1-3 x)(WO_4)_(3 x)(0cancies) solid solution was synthesized via solid state reaction method. The X-ray diffraction(XRD) and scanning electron microscopy(SEm) results confirm the formation of single, tetragonal scheelite-type phases(space group I4_1/a) with the average crystallite size in the range of ～20-100 μm. Substitution of Pb^(2+) with Eu^(3+) is relatively easy despite the large difference in ionic radii, and the formation of vacancies is necessary to compensate the excess positive charge in PbmoO_4 framework. A change in lattice parameters(both a and c as well as lattice parameter ratio c/a) and progressive deformation of moO_4 and WO_4 tetrahedra with increasing Eu concentration are observed. Thermal stability of Eu-doped materials strongly depends on the concentration of Eu3+ ions. The Pb_(1-3 x)■_xEu_(2 x)(moO_4)_(1-3 x)(WO_4)_(3 x) solid solution for x=0.0098 shows the highest melting point(1057 ℃) which is slightly higher than that of pure PbmoO_4(1040 ℃). The UV-vis diffuse reflectance spectroscopy(DRS) and the Tauc plots were used to extrapolate the optical indirect band gap(E_g) of doped materials. Eu-doped ceramics are insulators(E_g > 3 eV) and their band gap nonlinearly decreases with increasing dopant concentration.

关键词： molybdato-tungstate Scheelites Thermal stability Optical properties Rare earths

Vibration analysis of FG annular sector in moderately thick plates with two piezoelectric layers

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Applied mathematics and mechanics(English Edition) 2019年第6期40卷 783-804页

作者： S.AZARIPOUR m.BAGHANI School of mechanical Engineering College of Engineering University of Tehran

Free vibration of functionally graded (FG) annular sector plates embedded with two piezoelectric layers is studied with a generalized differential quadrature (GDQ) method. Based on the first-order shear deformation (FSD) plate theory and Hamilton’s principle with parameters satisfying maxwell’s electrostatics equation in the piezoelectric layers, governing equations of motion are developed. Both open and closed circuit (shortly connected) boundary conditions on the piezoelectric surfaces, which are respective conditions for sensors and actuators, are accounted for. It is observed that the open circuit condition gives higher natural frequencies than a shortly connected condition. For the simulation of the potential electric function in piezoelectric layers, a sinusoidal function in the transverse direction is considered. It is assumed that properties of the FG material (FGm) change continuously through the thickness according to a power distribution law. The fast rate convergence and accuracy of the GDQ method with a small number of grid points are demonstrated through some numerical examples. With various combinations of free, clamped, and simply supported boundary conditions, the effects of the thicknesses of piezoelectric layers and host plate, power law index of FGms, and plate geometrical parameters (e.g., angle and radii of annular sector) on the in-plane and out-of-plane nat-ural frequencies for different FG and piezoelectric materials are also studied. Results can be used to predict the behaviors of FG and piezoelectric materials in mechanical systems.

关键词： free vibration annular sector piezoelectric functionally graded material (FGm) first-order shear deformation (FSD)

Ion motion effects on the generation of short-cycle relativistic laser pulses during radiation pressure acceleration

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High Power Laser Science and Engineering 2014年第2期2卷 1-7页

作者： W.P.Wang X.m.Zhang X.F.Wang X.Y.Zhao J.c.Xu Y.H.Yu L.Q.Yi Y.Shi L.G.Zhang T.J.Xu c.Liu Z.K.Pei B.F.Shen State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences

The effects of ion motion on the generation of short-cycle relativistic laser pulses during radiation pressure acceleration are investigated by analytical modeling and particle-in-cell simulations. Studies show that the rear part of the transmitted pulse modulated by ion motion is sharper compared with the case of the electron shutter only. In this study, the ions further modulate the short-cycle pulses transmitted. A 3.9 fs laser pulse with an intensity of 1.33×1021W cm-2is generated by properly controlling the motions of the electron and ion in the simulations. The short-cycle laser pulse source proposed can be applied in the generation of single attosecond pulses and electron acceleration in a small bubble regime.

关键词： radiation pressure acceleration short-cycle pulses particle-in-cell simulations.

Stochastic asymptotical synchronization of chaotic markovian jumping fuzzy cellular neural networks with mixed delays and the Wiener process based on sampled-data control

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chinese Physics B 2013年第7期22卷 564-573页

作者： m. Kalpana P. Balasubramaniam Department of mathematics Gandhigram Rural InstituteDeemed University

We investigate the stochastic asymptotical synchronization of chaotic markovian jumping fuzzy cellular neural networks （mJFcNNs） with discrete, unbounded distributed delays, and the Wiener process based on sampled-data control using the linear matrix inequality （LmI） approach. The Lyapunov–Krasovskii functional combined with the input delay approach as well as the free-weighting matrix approach is employed to derive several sufficient criteria in terms of LmIs to ensure that the delayed mJFcNNs with the Wiener process is stochastic asymptotical synchronous. Restrictions （e.g., time derivative is smaller than one） are removed to obtain a proposed sampled-data controller. Finally, a numerical example is provided to demonstrate the reliability of the derived results.

关键词： stochastic asymptotical synchronization fuzzy cellular neural networks chaotic markovian jumping parameters sampled-data control

Spontaneous combustion of coals and coal-shales

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International Journal of mining Science and Technology 2018年第6期28卷 933-940页

作者： m.Onifade B.Genc The School of mining Engineering University of the Witwatersrand

Spontaneous combustion of coal is a well-known phenomena around the globe. Apart from the coal itself,burning coal-shales is becoming a problem in the South African coal mines. Serious incidents of spontaneous combustion have been reported as a result of self-heating of reactive coal-shales. The intrinsic properties and spontaneous combustion tests of 28 selected coal and coal-shale samples were conducted and a relationship between the two has been established. Intrinsic properties were obtained by using the proximate and ultimate analysis, and spontaneous combustion liability tests results were obtained by using the Wits-Ehac and Wits-cT indices. The experimental results show that intrinsic properties of these materials complement to the spontaneous combustion liability tests results. comparative analyses of intrinsic properties and spontaneous combustion characteristics indicate similarities between the mechanism of coal oxidation and that of the oxidative processes undergone by coal-shales. For the tested samples, coal samples have a higher intrinsic spontaneous combustion reactivity rating than the ***, an increase in carbon, moisture, hydrogen, volatile matter, nitrogen and a decrease in ash content indicate an increased proneness to self-heating. The concentration of pyrite found in the coal-shales accelerates self-heating. The event of spontaneous combustion can occur if coal-shales absorb sufficient oxygen when subjected to atmospheric conditions.

关键词： Spontaneous combustion coal-shales Proximate and ultimate analysis Wits-Ehac index Wits-cT index

microstructural evolution and mechanical properties of nanostructured cu-Al-Ni shape memory alloys

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International Journal of minerals,metallurgy and materials 2012年第4期19卷 333-338页

作者： m. Izadinia K. Dehghani mining and metallurgical Engineering Department Amirkabir University of Technology

The melt spinning technique, with an applied cooling rate of about 106 K/s, was used to produce a nanostructured cu＋13.2Al＋ 5.1Ni （in wt%） shape memory alloy. The properties of nanostructured ribbons were then compared with those of conventional coarse struc- ture. The microstructural evolution was characterized using scanning electron microscopy （SEm）, atomic force microscopy （AFm） and X-ray diffraction （XRD） techniques. microhardness measurements indicate a two-fold increase in hardness because of the produced nanos- lructure. comparing to its coarse structure, the nanostructured cu-A1-Ni shape memory alloy exhibited the enhanced mechanical properties including a ductility of 6.5% and a pronounced plateau in the stress-strain curve.

关键词： copper allosy shape memory effect melt spinning mechanical properties microstructural evolution

Kerosene-alumina nanofluid flow and heat transfer for cooling application

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Journal of central South University 2016年第4期23卷 983-990页

作者： m.mahmoodi Sh.Kandelousi Department of Aerospace Engineering Malek-Ashtar University of Technology Department of mechanical Engineering Babol University of Technology

Kerosene-alumina nanofluid flow and heat transfer in the presence of magnetic field are studied. The basic partial differential equations are reduced to ordinary differential equations which are solved semi analytically using differential transformation method. Velocity and temperature profiles as well as the skin friction coefficient and the Nusselt number are determined analytically. The influence of pertinent parameters such as magnetic parameter, nanofluid volume fraction, viscosity parameter and Eckert number on the flow and heat transfer characteristics is discussed. Results indicate that skin friction coefficient decreases with increase of magnetic parameter, nanofluid volume fraction and viscosity parameter. Nusselt number increases with increase of magnetic parameter and nanofluid volume fraction while it decreases with increase of Eckert number and viscosity parameter.

关键词： magnetic field nanofluid heat transfer differential transformation method