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Acta Mechanica Solida Sinica 2013年第6期26卷 659-670页

作者： A.M.Zenkour d.S.Mashat A.e.Abouelregal department of Mathematics Faculty of ScienceKing Abdulaziz UniversityP.O.Box 80203Jeddah 21589Saudi Arabia department of Mathematics Faculty of ScienceKafrelsheikh UniversityKafr El-Sheikh 33516Egypt department of Mathematics Faculty of ScienceMansoura UniversityMansoura 35516Egypt department of Mathematics College of Science and ArtsUniversity of AljoufEl-QurayatSaudi Arabia

The present article represents an analysis of reflection of P-wave and SV-wave on the boundary of an isotropic and homogeneous generalized thermoelastic half-space when the boundary is stress-free as well as isothermal. The modulus of elasticity is taken as a linear function of reference temperature. The basic governing equations are applied under four theories of the generalized thermoelasticity： Lord-Shulman （L-S） theory with one relaxation time, Green-Naghdi （G-N） theory without energy dissipation and Tzou theory with dual-phase-lag （dPL）, as well as the coupled thermoelasticity （CTe） theory. It is shown that there exist three plane waves, namely, a thermal wave, a P-wave and an SV-wave. The reflection from an isothermal stress-free surface is stud.e. to obtain the reflection amplitude ratios of the reflected waves for the incidence of P- and SV-waves. The amplitude ratios variations with the angle of incident are shown graphically. Also the effects of reference temperature of the modulus of elasticity and dual-phase lags on the reflection amplitude ratios are discussed numerically.

关键词： generalized thermoelasticity dual-phase-lag variable material properties reflection waves

effects of nano-voids and nano-cracks on the elastic properties of a host medium: xfem modeling with level-set function and free surface energy

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Acta Mechanica Sinica 2019年第4期35卷 799-811页

作者： B.e. Hachi d. Hachi M. Haboussi Laboratoire de développement en Mécanique et Matériaux (LdMM) Université de Djelfa PB 3117 Djelfa Algérie Laboratoire d’Automatique Appliquée et diagnostics Industriels (LAAdI) Université de Djelfa PB 3117 Djelfa Algérie Laboratoire des Sciences des Procédés et des Matériaux (LSPM) Université Paris 13 UPR 3407 CNRS Paris France

This work deals with the influences of nano-heterogeneities in the form of voids/cavities or cracks on the elastic (please confirm which word is correct. effective or elastic? According to the title of paper, I choose elastic.) properties of a host medium. With a relatively large ratio of apparent-surface to volume and particularly strong physical interactions with the surrounding medium at nano-scale, nano-heterogeneities can potentially affect the elastic(effective or elastic?) properties of the parent medium (matrix) containing them in a significant manner. This has been reported by various theoretical and.e.perimental stud.e., some of them are discussed in the present paper. To describe the positive (reinforcement) or negative (degradation) effect of the nano-heterogeneities from the modeling perspective, it is necessary to take into account the energy of interfaces/surfaces between nano-heterogeneities and the matrix which, by the fact of the relatively large extent of their apparent surface and their strong physical interaction with their neighborhood, can no longer be neglected compared to those of the volume energy. Thus, to account for the effects of interfaces/surfaces in a nanostructured heterogeneous medium, the coherent interface model is considered in the present investigation within a periodic homogenization procedure. In this interface/surface model, the displacement vector is assumed to be continuous across the interface while the stress vector is considered to be discontinuous and satisfying the Laplace-Young equations. To solve these equations coupled to the classical mechanical equilibrium problem, a numerical simulation tool is developed in a two-dimensional (2d) context using the eXtended Finite element Method (XFeM) and the Level-Set functions. The developed numerical tool is then used to carry out a detailed analysis about the effect of nano-heterogeneities on the overall mechanical properties of a medium. The nano-heterogeneities are present

关键词： Interface/Surface energy XFeM Level-Set function Periodic homogenization Nano-voids/Nano-cavities Nano-cracks Nano-inclusions/Nano-heterogeneities

Proportional-integral-derivative control of nonlinear half-car electro-hydraulic suspension systems

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2013年第6期14卷 401-416页

作者： John e. d. eKORU Jimoh O. PedRO School of Mechanical Aeronautical and Industrial Engineering University of the Witwatersrand Private Bag 03 WITS 2050 Johannesburg South Africa

This paper presents the development of a proportional-integral-derivative (PId)-based control method for application to active vehicle suspension systems (AVSS). This method uses an inner PId hydraulic actuator force control loop, in combination with an outer PId suspension travel control loop, to control a nonlinear half-car AVSS. Robustness to model uncertainty in the form of variation in suspension damping is tested, comparing performance of the AVSS with a passive vehicle suspension system (PVSS), with similar model parameters. Spectral analysis of suspension system model output data, obtained by performing a road input disturbance frequency sweep, provides frequency response plots for both nonlinear vehicle suspension systems and time domain vehicle responses to a sinusoidal road input disturbance on a smooth road. The results show the greater robustness of the AVSS over the PVSS to parametric uncertainty in the frequency and time domains.

关键词： Force control Proportional-integral-derivative (PId) control Nonlinear half-car Active vehicle suspension system (AVSS) Hydraulic actuator dynamics Model uncertainty

The multi-impurity system in Cd.e.nanoplatelets:electronic structure and thermodynamic properties

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Communications in Theoretical Physics 2024年第3期76卷 165-173页

作者： d A Baghdasaryan V A Harutynyan e M Kazaryan H A Sarkisyan Russian-Armenian University H Emin 1230051YerevanArmenia Institute of Applied Problems of Physics 25 Nersisyan St0014YerevanArmenia

This paper theoretically stud.e. the impurity states and the effects of impurity concentration and configuration on the optical,electrical,and statistical properties of Cd.e.nanoplatelets(NPLs).An image charge-based model of electron-impurity interaction is *** charge-carrier energy spectra and corresponding wave functions depending on the impurity number and configuration are *** electron binding energies are calculated for different NPL *** is shown that the image charge-based interaction potential that arises d.e.to the d.e.ectric constants mismatch is much stronger than the interaction potential that d.e. not take such a mismatch into ***,it is demonstrated that the binding energies are increasing with the number of *** calculate the canonical partition function using the energy levels of the electron,which in turn is used to obtain the mean energy,heat capacity,and.e.tropy of the non-interacting electron *** thermodynamic properties of the non-interacting electron gas that depend on the geometric parameters of the NPL,impurity number,configuration,and temperature are stud.e..

关键词： nanoplateletes thermodynamic properties impurity states

Atomic-scale simulations of material behaviors and tribology properties for BCC metal film

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Chinese Physics B 2016年第1期25卷 412-418页

作者： H d Aristizabal P A Parra P Lopez e Restrepo-Parra PCM Computational Applications Universidad Nacional de Colombia-Sede ManizalesA.A.127ManizalesColombi Universidad Cató1ica de Manizales A.A.357ManizalesColombia

This work has two main purposes：（i） introducing the basic concepts of molecular dynamics analysis to material scientists and.e.gineers, and （ii） providing a better understanding of instrumented indentation measurements, presenting an example of nanoindentation and scratch test simulations. To reach these purposes, three-dimensional molecular dynamics （Md） simulations of nanoindentation and scratch test technique were carried out for generic thin films that present BCC crystalline structures. Structures were oriented in the plane （100） and placed on FCC diamond substrates. A pair wise potential was employed to simulate the interaction between atoms of each layer and a repulsive radial potential was used to represent a spherical tip indenting the sample. Mechanical properties of this generic material were obtained by varying the indentation depth and dissociation energy. The load-unload curves and coefficient of friction were found for each test; on the other hand, dissociation energy was varied showing a better mechanical response for films that present grater dissociation energy. Structural change evolution was observed presenting vacancies and slips as the depth was varied.

关键词： molecular dynamics pair wise potential repulsive radial potential dissociation energy

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今日教育管理 1版

Grafting affects yield and phenolic prof ile of Solanum melongena L. landraces

丛书名：当代教育科学译丛

1989年

作者：（美）d.e.奥洛斯基等张彦杰杨秀文等译

著者原题:d.e.奥洛斯基:本书以当前美国社会发展和变革为背景,针对美国教育实际论述教育管理诸问题。

ISBN: (纸本)7506901455

著者原题:d.e.奥洛斯基:本书以当前美国社会发展和变革为背景,针对美国教育实际论述教育管理诸问题。

关键词：教育学科:管理地点:美国

来源：汇雅图书（南通市图书馆... 评论

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Journal of Integrative Agriculture 2016年第5期15卷 1017-1024页

作者： L Sabatino G Iapichino A Maggio e d’ Anna M Bruno F d’ Anna department of Agricultural and Forest Sciences University of Palermo department of Biological Chemical and Pharmaceutical Sciences and Technologies University of Palermo Regional Centres for Agricultural Technologies (Ce.R.T.A.) University of Foggia

The influence of grafting on agronomical and qualitative characteristics of four Sicilian eggplant landraces was investigated. Grafted and ungrafted plants were compared in the open field in the northern coast of Sicily. Solanum torvum seedlings were used as rootstock. Regard.e.s of genotypes tested, grafting significantly increased total fruit production, marketable production, and number of marketable fruits, but did not affect weight of marketable fruits and waste production. Landrace 2（Sciacca）, with black epidermal tissue and pyriform fruit shape, when grafted onto S. torvum not only gave a higher yield performance than ungrafted plants, but also showed a higher phenolic antioxidant content. Landrace 4（Sicilia）, with black epidermal tissue and small cylindrical fruits also benefited, when grafted onto S. torvum, from a substantial increase in antioxidant fruit content. As consumers＇ demand for fruits and vegetables rich in compounds important for human health is steadily increasing, these landrace/rootstock combinations should deserve more attention by plant nurseries involved in grafted seedling production and interested in the valorization and conservation of eggplant biodiversity.

关键词： eggplant propagation technique yield polyphenols HPLC analysis

Photoluminescence properties of eu3+-doped MgAl2O4 nanoparticles in various surrounding media

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Journal of Rare earths 2019年第8期37卷 806-811,I0001页

作者： I.e.Kolesnikov e.V.Golyeva e.V.Borisov e.Yu Kolesnikov e.Lahderanta A.V.Kurochkin M.d.Mikhailov St.Petersburg State University St.PetersburgRussia Lappeenranta University of Technology LUT LappeenrantaFinland Peter the Great St.Petersburg Polytechnic University St.PetersburgRussia Scientific and Technological Institute of Optical Material Science VNTs S.I.Vavilov State Optical InstituteSt.PetersburgRussia Volga State University of Technology Yoshkar-OlaRussia

eu3+-doped MgAl2O4 nanoparticles were prepared by modified Pechini method.X-ray diffraction analysis shows pure tetragonal spinel phase without any *** average size of synthesized nanoparticles was determined to be about 50-60 nm using scanning electron microscopy and static light scattering *** and.e.citation spectra as well as lifetimes of MgAl2O4:eu3+ nanophosphors were explored in surrounding media with different refractive *** medium d.e. not affect luminescence bands position,whereas 5d0 lifetime monotonically decreases along with increase of medium refractive *** of surrounding media on radiative and nonradiative decay rates,which were calculated using 4f-4f intensity theory,was stud.e. and *** factor of prepared nanoparticles is defined using both radiative and observed lifetimes.

关键词： eu3+ Nanoparticles Filling factor Luminescence Lifetime Rare earths

A study on responses of soil erosion and sediment yield to closing cultivation on sloping land in a small catchment using (137)Cs technique in the Rolling Loess Plateau, China

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Chinese Science Bulletin 2003年第19期48卷 2093-2100页

作者： FeNGMingy d.e.Walling ZHANGXinbao WeNAnbang ChengduInstituteofMountainHazardsandenvironment ChineseAcademyofSciences(CAS)Chengdu610041China departmentofGeographyandArchaeology ExeterUniversityEeterEX44RJUK

Abstract By comparison of volumes and 137Cs contents of the deposited sediments before and after 1993, changes of specific sediment yields and relative sediment contributions from the gully area and from the inter gully area after closing cultivation on the later area on a small catchment of Zhaojia Gully, in the Rolling Loess Plateau, are analyzed in this paper. Closing cultivation in a large scale has not resulted in decrease but increase of specific sediment yield of the catchment, in sharp decrease of the sediment yield and the relative sediment contribution of the inter-gully area, and in increase of the sediment yield and the contribution of the gully area, for a short term. The mean specific sediment yield of 29650 t km-2 a-1 of 1994—1996 in the catchment was 2.2 times the average value of 13413 t km-2 a-1 for a long term. The specific sediment yield of the inter-gully area decreased from the 14335 t km-2 a-1 in 1994 to 7034 t km-2 a-1 in 1995 and 3517 t km-2 a-1 in 1996, while the yield of the gully area varied between 44944 and 62136 t km-2 a-1 during the period of 1994—1996 which was much greater than the value of 21118 t km-2 a-1 before 1993. The relative sediment contribution from the inter-gully area decreased from 23% in 1994 to 15% in 1995 and 6% in 1996, while the contribution from the gully area increased from 77% in 1994 to 85% in 1995 and 94% in 1996. It is suggested that compacting of ploughed soils resulted in increasing of the erosion resistance but in decreasing of the precipitation infiltration, therefore, the soil erosion reduced but the runoff amount increased on the inter-gully area. Increase of delivering runoff from the inter-gully area to the gully area should result in activeness of gully erosion and mass movements, consequently, in increase of the total sediment yield from the catchment.

关键词：沉积量土壤侵蚀倾斜地带汇水盆地 137Cs 起伏黄土高地沉积作用

210Pb(ex) depth distribution in soil and calibration models for assessment of soil erosion rates from 210Pb(ex) measurements

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Chinese Science Bulletin 2003年第8期48卷 813-818页

作者： ZHANGXinbao d.e.Walling FeNGMingyi WeNAnbang StateKeyLaboratoryofLoessandQuaternaryGeology InstituteofEarthEnvironmentCASXi'an710075China departmentofGeographyandArchaeology ExeterUniversityExeterUKEX44RJ ChengduInstituteofMountainHazardsandenvironment ChineseAcademyofSciences(CAS)Chengdu610041China

Three soil cores collected from China and UK show the 210Pbex and 137Cs depth distribution on uncultivated and cultivated land. depth distributions of the two nuclides are very similar. Those nuclide concentrations are higher in the top horizon and decrease exponentially with depth on uncultivated land while the concentrations are almost uni-form throughout the plough layer as a result of mixing asso-ciated with cultivation on cultivated land. 210Pbex reference inventory in the Loess Plateau is 573 mBq·cm-2, a little higher than 520.0 mBq·cm-2 in UK. distribution of artificial fallout 137Cs, produced during the nuclear testing period of the late 1950s and 1960s, is in an unsteady state. In contrast, distribution of natural fallout 210Pbex is in a steady state un-der constant conditions of land.e.vironment and.e.osion processes for a long term, e.g. >100 years. Therefore, mass balances of 137Cs and 210Pbex in soil are different. According to its processes of continues deposition from the atmosphere, nature decay and losses with soil losses, 210Pbex steady state mass balance models for cultivated land as well as for uncul-tivated land are developed to estimate soil erosion rates in this paper. Besides, the proportion of freshly deposited 210Pbex fallout removed by erosion on cultivated land can also be calculated from 210Pbex depth distribution at a reference site of uneroded permanent grass land.

关键词： ^210Pbex 铅土壤侵蚀铯铀