block-flexure is the most common mode of toppling failure in natural and excavated rock slopes. in such failure, some rock blocks break due to tensile stresses and some overturn under their own weights and then all of them topple together. in this paper, first, a brief review of previous studies on toppling failures is presented. then, the physical and mechanical properties of experimental mode...

in this paper, sufficient conditions are investigated for the existence of periodic (not necessarily positive) solutions for nonlinear several time delay population system with feedback control. nonlinear system affected by an periodic external source is studied. existence of a control variable provides  the extension of  some previous results obtained in other studies. we give a illustrative e...

the solutions of mathematical models for the estimation of the kinetic, and biokinetic parameters of naphthalene, anthracene and pyrene during degradation in surface and subsurface soils are presented in this work. the models were developed using the twin concepts of rate-determining step and steady-state approximation method. they described the biodegradation of single and a mixture of polycy...

this study presents a comparison between aluminum and iron plate electrodes on phosphate removal from aqueous solutions by electrocoagulation process. the effectiveness of main operational parameters such as initial ph, initial phosphate concentration and current density were examined. in addition, treated solution and sludge characteristics, energy consumption and electrode mass depletion w...

this paper investigates existence and uniqueness results for the first order fuzzy integro-differential equations. then numerical results and error bound based on the left rectangular quadrature rule, trapezoidal rule and a hybrid of them are obtained. finally an example is given to illustrate the performance of the methods.

maintaining quality and longevity of cut flowers is one of the critical issues in the floriculture industry, especially in cut flowers; and one of the most important problems in chrysanthemum, as one of the most popular cut flowers. therefore, an experiment was conducted based on completely randomized design as pulse treatment with the three factors: tea extracts with 4 levels (5, 10, 20, and 4...

the analytical theory of one dimensional, dispersion free miscible displacement of oil by injection gas with nc component has shown that: the mmp is the lowest pressure at which any one of the initial oil, injection gas or crossover key tie lines becomes critical, which means that its length approaches to zero. in this paper, we propose a method for a solving multi component system based on ana...

asphaltenes are the n-pentane or n-heptane insoluble fractions of crude oil that remain in solution under reservoir temperature and pressure conditions. they are destabilized and start to precipitate when the pressure, temperature and/or composition changes occur during primary production. the precipitated asphaltene particles will then grow in size and may start to deposit onto the production ...

forward osmosis (fo) has recently drawn attention as a promising membrane based method for seawater and brackish water desalination. in this study, we focus on the use of calciun chloride (cacl2) and potassium bicarbonate (khco3) as inorganic salt draw solution candidates due to their appropriate performance in water flux and reverse salt diffusion as well as reasonable cost. the experiments we...