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Modeling and Analysis of Mechanization Projects of Wheat Production by GERT Networks

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Agricultural Sciences in China 2010年第7期9卷 1078-1083页

作者： Reza Abdi Hamid Reza Ghasemzadeh Shamsollah Abdollahpour Majid Sabzeparvar Adel Dabbag Mohamadi Nasab faculty of Agriculture University of Tabriz faculty of Industrial University of Science and Industry(Iran)

In crop production systems,all operations such as seed bed preparation,etc.,must be accomplished on time,if yield reduction and low quality product are to be *** all operations in mechanized cropping projects require precise scheduling,planning and *** basic approach in all scheduling techniques is to form a network of activities and events relationships that graphically portrays the sequential relations between the tasks in a *** a network would as a powerful tool available a farm manager to plan,schedule,monitor and control a *** GERT（Graphical Evaluation and Review Technique） networks have most of advantages associated with networks and available system analyst in exact evaluation of certain types of networks,in this research it was used and mechanized wheat production system was simulated,modeled and *** activities,events and path were *** showed that the network model was able to answer any statistic questions concerning with the *** models,particularly GERT networks are increasingly powerful tool for modeling,scheduling,planning,controlling,and analyzing of agricultural mechanization projects.

关键词： GERT networks mechanization project scheduling wheat

Structural and electronic characteristics of pure and doped ZnO varistors

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Chinese Physics B 2012年第11期21卷 352-360页

作者： A.Sedky E.El-Suheel Physics Department Faculty of ScienceKing Faisal University Physics Department Faculty of ScienceAssiut University

We report here the structural, surface morphology, mechanical, and current voltage characteristics of Zn1-xMxO ceramic samples with various x and M （0.00≤〈 x ≤ 0.20, M = Ni, Cu）. It is found that the considered dopants do not influence the well-known peaks related to the wurtzite structure of ZnO ceramics, while the shapes and the sizes of grains are clearly affected. The average crystalline diameters deduced from the SEM micrographs are between 2.06 μm and 4.8 μm for all samples. The oxygen element ratio is increased by both dopants. Interestingly, the potential barrier can be formed by adding Cu up to 0.20, while it is completely deformed by 0.025 Ni addition. The breakdown field can be enhanced up to 4138 V/cm by 0.025 Cu addition, followed by a decrease with further increase of Cu up to 0.20. On the other hand, a gradual decrease in Vickers microhardness is reported for both dopants, and the values in the Ni samples are higher compared to those in the Cu samples. The electricul conductivity is generally improved by Ni, while the addition of Cu improves it only in the over doped region （≥ 0.10）. These results are discussed in terms of the differences of valency and ferromagnetic ordering.

关键词： semiconductors chemical synthesis impurity electronic transport

Instability of equilibrium of nonholonomic systems with dissipation and circulatory forces

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Applied Mathematics and Mechanics(English Edition) 2011年第2期32卷 211-222页

作者： M.VESKOVI V.OVI A.OBRADOVI faculty of Mechanical Engineering University of Kragujevac faculty of Mechanical Engineering University of Belgrade

The paper discusses the equilibrium instability problem of the scleronomic nonholonomic systems acted upon by dissipative, conservative, and circulatory forces. The method is based on the existence of solutions to the differential equations of the motion which asymptotically tends to the equilibrium state of the system as t tends to negative infinity. It is assumed that the kinetic energy, the Rayleigh dissipation function, and the positional forces in the neighborhood of the equilibrium position are infinitely differentiable functions. The results obtained here are partially generalized the results obtained by Kozlov et al. （Kozlov, V. V. The asymptotic motions of systems with dissi- pation. Journal of Applied Mathematics and Mechanics, 58（5）, 787-792 （1994）. Merkin, D. R. Introduction to the Theory of the Stability of Motion （in Russian）, Nauka, Moscow （1987）. Thomson, W. and Tait, P. Treatise on Natural Philosophy, Part I, Cambridge University Press, Cambridge （1879））. The results are illustrated by an example.

关键词： nonholonomic constraint instability potential dissipative force

Optical and electrical characterizations of nanoparticle Cu_2S thin films

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Chinese Physics B 2014年第4期23卷 476-481页

作者： M.Saadeldin H.S.Soliman H.A.M.Ali K.Sawaby Physics Department Faculty of Science Cairo University Physics Department Faculty of Education Ain-Shams University

Copper sulfide thin films are deposited onto different substrates at room temperature using the thermal evaporation technique. X-ray diffraction spectra show that the film has an orthorhombicchalcocite （7-Cu2S） phase. The atomic force microscopy images indicate that the film exhibits nanoparticles with an average size of nearly 44 nm. Specrtophotometric measurements for the transmittance and reflectance are carried out at normal incidence in a spectral wavelength range of 450 nm-2500 nm. The refractive index, n, as well as the absorption index, k is calculated. Some dispersion parameters are determined. The analyses of el and e2 reveal several absorption peaks. The analysis of the spectral behavior of the absorption coefficient, c~, in the absorption region reveals direct and indirect allowed transitions. The dark electrical resistivity is studied as a function of film thickness and temperature. Tellier＇s model is adopted for determining the mean free path and bulk resistance.

关键词： physical properties of Cu2S thermal evaporation nanoparticle Cu2S thin films

Bending of orthotropic plates resting on Pasternak's foundations using mixed shear deformation theory

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Acta Mechanica Sinica 2011年第6期27卷 956-962页

作者： A.M.Zenkour Department of Mathematics Faculty of Science King AbdulAziz University Department of Mathematics Faculty of Science Kafrelsheikh University

The mixed first-order shear deformation plate theory（MFPT） is employed to study the bending response of simply-supported orthotropic *** present plate is subjected to a mechanical load and resting on Pasternak＇s model or Winkler＇s model of elastic foundation or without any elastic *** examples are presented to verify the accuracy of the present *** results for deflection and stresses are *** proposed MFPT is shown simplely to implement and capable of giving satisfactory results for shear deformable plates under static loads and resting on two-parameter elastic *** results presented here show that the characteristics of deflection and stresses are significantly influenced by the elastic foundation stiffness,plate aspect ratio and side-to-thickness ratio.

关键词： Mixed theory Bending Rectangular plates Pasternak's model

Formation of hydrogen atom in 2s state in proton–sodium inelastic scattering

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Chinese Physics B 2015年第3期24卷 136-142页

作者： Sabbah A.Elkilany Department of Mathematics Faculty of ScienceAd Dammam University Department of Mathematics Faculty of ScienceKafrelsheikh University

The inelastic collision of protons with sodium atoms are treated for the first time within the framework of the coupledstatic and frozen core approximations. The method is used for calculating partial and total cross-sections with the assumption that only two channels（elastic and hydrogen formation in 2s state） are open. In each case, the calculations are carried out for seven values of the total angular momentum l（0≤ l≤ 6）. The target is described using the Clementi Roetti wave functions within the framework of the one valence electron model. We use Lipmann–Swinger equation to solve the derived equations of the problem, then apply an iterative numerical method to obtain the code of computer to calculate iterative partial cross-sections. This can be done through calculating the reactance matrix at different values of considered energies to obtain the transition matrix that gives partial and total cross sections. The present results for total hydrogen（2s state）formation cross sections are in agreement with results of other available ones in wide range of incident energy.

关键词： proton–sodium inelastic scattering hydrogen formation

On the stability of equilibria of nonholonomic systems with nonlinear constraints

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Applied Mathematics and Mechanics(English Edition) 2010年第6期31卷 751-760页

作者： V.OVI M. VESKOVI D. DJURI A. OBRADOVI faculty of Mechanical Engineering University of Belgrade faculty of Mechanical Engineering University of Kragujevac

Lyapunov＇s first method, extended by V. V. Kozlov to nonlinear mechani- cal systems, is applied to the study of the instability of the position of equilibrium of a mechanical system moving in the field of conservative and dissipative forces. The mo- tion of the system is limited by ideal nonlinear nonholonomic constraints. Five cases determined by the relationship between the degree of the first nontrivial polynomials in Maclaurin＇s series for the potential energy and the functions that can be generated from the equations of nonlinear nonholonomic constraints are analyzed. In the three eases, the theorem on the instability of the position of equilibrium of nonholonomic systems with linear homogeneous constraints （V. V. Kozlov （1986）） is generalized to the case of nonlin- ear nonhomogeneous constraints. In the other two cases, new theorems are set extending the result from V. V. Kozlov （1994） to nonholonomic systems with nonlinear constraints.

关键词： Lyapunov first method nonholonomic system instability of equilibrium

Further Bounds for Hardy Type Differences

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Acta Mathematica Sinica,English Series 2012年第6期28卷 1091-1102页

作者： Kristina KRULI Josip PEARI Dora POKAZ faculty of Textile Technology University of Zagreb faculty of Civil Engineering University of Zagreb

In this paper we define a functional as a difference between the right-hand side and lefthand side of the refined Boas type inequality using the notation of superquadratic and subquadratic functions and study its properties, such as exponential and logarithmic convexity. We also, state and prove improvements and reverses of new weighted Boas type inequalities. As a special case of our result we obtain improvements and reverses of the Hardy inequality and its dual inequality. We introduce new Cauchy type mean and prove monotonicity property of this mean.

关键词： Inequalities Boas inequality superquadratic function subquadratic function

ELASTODYNAMIC ANALYSIS OF A FUNCTIONALLY GRADED HALF-PLANE WITH MULTIPLE SUB-SURFACE CRACKS

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Acta Mechanica Solida Sinica 2012年第1期25卷 90-99页

作者： Rasul Bagheri Mojtaba Ayatollahi Alibakhsh Kasaeian faculty of Engineering Zanjan University faculty of New Sciences and Technologies University of Tehran

The stress fields are obtained for a functionally graded half-plane containing a Volterra screw *** elastic shear modulus of the medium is considered to vary *** dislocation solution is utilized to formulate integral equations for the half-plane weakened by multiple smooth cracks under anti-plane *** integral equations are of Cauchy singular type at the location of dislocation which are solved *** examples are solved and the stress intensity factors are obtained.

关键词： functionally graded materials half-plane multiple cracks screw dislocation