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EFFECT OF FRACTIONAL ORDER PARAMETER ON THERMOELASTIC BEHAVIORS OF ELASTIC MEDIUM WITH VARIABLE PROPERTIES

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Acta Mechanica Solida Sinica 2015年第6期28卷 682-692页

作者： Yingze Wang Dong Liu Qian Wang Jianzhong Zhou department of energy and power Engineering Jiangsu University department of mechanical Engineering Jiangsu University

This paper is concerned with the thermoelastic behaviors of an elastic medium with variable thermal material properties. The problem is in the context of fractional order heat conduction. The governing equations with variable thermal properties were established by means of the fractional order calculus. The problem of a half-space formed of an elastic medium with variable thermal material properties was solved, and asymptotic solutions induced by a sudden temperature rise on the boundary were obtained by applying an asymptotic approach. The propagations of thermoelastic wave and thermal wave, as well as the distributions of displacement, temperature and stresses were obtained and plotted. Variations in the distributions with different values of fractional order parameter were discussed. The results were compared with those obtained from the case of constant material properties to evaluate the effects of variable material properties on thermoelastic behaviors.

关键词： generalized thermoelasticity fractional order heat conduction variable thermal material properties asymptotic solution thermal shock

NUMERICAL AND EXPERIMENTAL STUDY OF FLOW AROUND TWO PLATES HAVING ASYMMETRIC BEVELED TRAILING EDGE

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Journal of Hydrodynamics 2008年第5期20卷 624-628页

作者： MOSALLEM M. M. department of mechanical power Engineering and energy Faculty of Engineering Minia University Minia

The flow around two plates having asymmetric beveled trailing edge placed side-by-side in a uniform stream were investigated both numerically and experimentally. Two plates with spacing ratio of 1.0 and beveled trailing edge of angle 20° were tested at Reynolds numbers equal to 3.97×10^4. The numerical simulation results displayed that the flow separates on one plate beveled trailing edge surface. The vortex formation and shedding from this plate led to deflecting the flow toward the other plate and consequently the wake behind the plates showed an asymmetric development. The photographs obtained from the flow visualization confirmed the numerical results concerning the flow separation and vortex formation. It was also found that the computed pressure distribution on the two plate surfaces was different, particularly on the beveled trailing edge surfaces and on the fiat sides.

关键词： Flow wake two plates vortex shedding beveled trailing edge

Adsorption of boron and its relationship with morphologies of TiC

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Rare Metals 2016年第9期35卷 705-710页

作者： Hai-Min Ding Xiao-Liang Fan Xin-Chun Zhang Ze-You Zheng School of energy power and mechanical Engineering North China Electric Power University

First-principle calculations were performed to study the adsorption of boron and its relationship with the morphologies of Ti *** is found that although the adsorption of boron on all the low-index Ti C crystal planes is thermally favorable,it will be adsorbed more easily by C-terminated {111} and {011} planes,while less possible to be adsorbed by {001}.The study of the formation of B–B clusters indicates that the distribution of boron adatoms on C-terminated（111） and {011} planes will be more uniform,and the diffusion of the adatom further confirms the above *** to the geometry relationship and growth rate of different crystal planes,it is deduced that the adsorption of boron on Ti C will seriously impede the growth of {111} and {011} planes,which can make Ti C grow into hexagonal platelets.

关键词： Ti C Adsorption Surfaces and interfaces First-principle calculations

Performance Assessment of Air-Cooled Steam Condenser with Guide Vane Cascade

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Journal of Thermal Science 2019年第5期28卷 993-1003页

作者： ZHANG Xuelei LI Yunpeng CHEN Haiping School of energy Power and Mechanical Engineering North China Electric Power University

Ambient wind has an unfavourable impact on air-cooled steam condenser(ACSC) performance. A new measure to improve ACSC performance is proposed by setting a diffusion type guide vane cascade beneath the ACSC platform. The numerical models are developed to illustrate the effects of diffusion type guide vane cascade on ACSC performance. The simulation results show that this vane cascade can cause the increases in coolant flows across almost all fans due to its diffusion function and lower flow resistance. Meanwhile, the guide vane cascade also decreases the fan inlet temperatures because of the uniform flow field around the condenser cells. Comparing with the case without guide device, the overall heat transfer efficiency is increased by 11.2% for guide vane cascade case under the condition of 9 m/s. The heat transfer efficiency firstly enhances and then decreases with decreasing stagger angle of guide vane under a certain wind speed. The optimum stagger angle corresponding to the maximum heat transfer efficiency is about 65.5°. The heat transfer efficiency always enhances as increasing vane cascade height, and a vane cascade with 20 m to 30 m height may be suitable to the ACSC as considering the cost.

关键词： air-cooled steam condenser ambient wind guide vane cascade heat transfer

Tribological application and mechanism of epicuticular wax

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Friction 2019年第1期7卷 44-58页

作者： Xuwen ZHONG Yanqiu XIA Xin FENG School of energy power and mechanical Engineering North China Electric Power University

The plant cuticle is a complex mixture of omnipresent, commonly monofunctional, fatty acid derivatives and taxon-specific, generally bifunctional, specialty compounds. This study explored expanded applications for these substances. Four types of plant cuticles were distilled from leaves and the resulting lipid mixtures were analyzed using gas chromatography-mass spectrometry. These were then used as additives for a synthetic ester lubricant. A reciprocating friction and wear testing machine was utilized to investigate the resulting tribological properties. The worn surfaces of the lower discs were observed and analyzed using optical microscopy and time-of-flight secondary ion mass spectrometry. The results reveal that cuticular waxes can modify the friction properties of the base oil. Furthermore, cuticular waxes demonstrate better performance when compared to the commercially available additive molybdenum dithiocarbamates. A protective adsorption film was identified as the reason for the improved friction reduction and anti-wear properties of the lubricant on the friction pair. This study provides a reference for the study of new types of non-sulfur, phosphorus, and other active element additives and demonstrates considerable potential for the economical utilization of plant leaf waxes.

关键词： epicuticular wax tribological application GC-MS TOF-SIMS adsorption

Correlation between valence electronic structure and magnetic properties in RCo_5(R=rare earth) intermetallic compound

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Chinese Physics B 2016年第6期25卷 165-171页

作者：薛智琴郭永权 North China Electric power University School of Energy Power and Mechanical Engineering

The magnetisms of RCo5（R = rare earth） intermetallics are systematically studied with the empirical electron theory of solids and molecules（EET）.The theoretical moments and Curie temperatures agree well with experimental *** calculated results show strong correlations between the valence electronic structure and the magnetic properties in RCo5 intermetallic *** moments of RCo5 intermetallics originate mainly from the 3d electrons of Co atoms and 4f electrons of rare earth,and the s electrons also affect the magnetic moments by the hybridization of d and s *** is found that moment of Co atom at 2c site is higher than that at 3g site due to the fact that the bonding effect between R and Co is associated with an electron transformation from 3d electrons into covalence *** the heavy rare-earth-based RCo5 intermetallics,the contribution to magnetic moment originates from the 3d and 4f *** covalence electrons and lattice electrons also affect the Curie temperature,which is proportional to the average moment along the various bonds.

关键词： EET theory electronic structure Curie temperature RCo5 intermetallics

Conductive and tribological properties of TiN-Ag composite coatings under grease lubrication

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Friction 2021年第4期9卷 774-788页

作者： Feihu LIN Yanqiu XIA Xin FENG School of energy power and mechanical Engineering North China

TiN-Ag composite coatings were prepared by pulsed bias arc ion plating.X-ray diffraction(XRD)and energy dispersive X-ray spectroscopy(EDS)were applied to analyze the compositions of the *** properties of the coatings were studied using an MFT-R4000 ball-on-disk friction tester in the presence of lubricating greases containing multilayer *** electron microscopy(SEM),Raman spectroscopy,and X-ray photoelectron spectroscopy(XPS)were used to analyze the worn surface compositions of the lubricating *** results show that with the decrease in Ag in the film,hardness increased but electrical conductivity *** coating with 10 at%Ag content shows the best friction-reducing and anti-wear properties,which can be attributed to the moderate content of Ag embedded in the TiN crystal gap that enhanced the grain bonding force to improve the anti-wear and self-lubricating *** can be adsorbed on the coating as a solid lubricant.

关键词： silver tribology contact resistance lubricating grease

Correlation between electronic structure and energy band in Eu-doped CuInTe_2 semiconductor compound with chalcopyrite structure

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Chinese Physics B 2017年第10期26卷 157-164页

作者：王泰郭永权李帅 School of energy power and mechanical Engineering North China Electric Power University

The Eu-doped Cu（In, Eu）Te2 semiconductors with chalcopyrite structures are promising materials for their applications in the absorption layer for thin-film solar cells due to their wider band-gaps and better optical properties than those of CuInTe2. In this paper, the Eu-doped CuInTe2 （CuIn1-xEuxTe2, x = 0, 0.1, 0.2, 0.3） are studied systemically based on the empirical electron theory （EET）. The studies cover crystal structures, bonding regularities, cohesive energies, energy levels, and valence electron structures. The theoretical values fit the experimental results very well. The physical mechanism of a broadened band-gap induced by Eu doping into CuInTe2 is the transitions between different hybridization energy levels induced by electron hopping between s and d orbitals and the transformations from the lattice electrons to valence electrons for Cu and In ions. The research results reveal that the photovoltaic effect induces the increase of lattice electrons of In and causes the electric resistivity to decrease. The Eu doping into CuInTe2 mainly influences the transition between different hybridization energy levels for Cu atoms, which shows that the 3d electron numbers of Cu atoms change before and after Eu doping. In single phase CuIn1-xEuxTe2, the number of valence electrons changes regularly with increasing Eu content, and the calculated band gap Eg also increases, which implies that the optical properties of Eu-doped CuIn1-xEuxTe2 are improved.

关键词： CuIn1-xEuxYe2 EET solar cells valence electronic structures band gap

Synthesis, structure, optical, and electric properties of Ce-doped CuInTe_2 compound

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Chinese Physics B 2014年第12期23卷 469-475页

作者：付丽郭永权 School of energy power and mechanical Engineering North China Electric Power University

Ce-doped Cu In Te2（CICT） semiconducting compounds are successfully synthesized. The phase structures, optical,and electric properties are investigated using powder X-ray diffraction（XRD）, field emission scanning electron microscopy（FESEM）, X-ray photoelectron spectrometer（XPS）, Raman spectrometer, ultraviolet and visible spectrophotometer（UVVis）, and a standard four-probe method. Cu In1-xCex Te2 crystallizes into a tetragonal structure with predominant orientation along the [112] direction. The lattice parameters are a = 6.190（6） A–6.193（0） A and c = 12.406（5） A–12.409（5） A. Ce prefers to occupy the 4b crystal position. According to the analysis of XPS spectra, Ce shows the mixture of valences 4＋and 3＋. Raman spectra reveal that the photon vibrating model in the CICT follows A1 mode in a wavenumber range of123 cm^-1–128 cm^-1. UV-Vis spectra show that the band gap Eg values before and after 0.1 mole Ce doped into Cu In Te2 are 1.28 e V and 1.16 e V, respectively. It might be due to the mixture of valences for Ce. Ce doped into Cu In Te2 still shows the semiconductor characteristics.

关键词： CuIn1-xCexTe2 chalcopyrite Raman spectrum band gap semiconductor