in this paper, polyacrylamide/chromium acetate gel polymer system was prepared as water shut-off system to control water production in one of the iranian oil reservoirs condition. effect of various parameters such as temperature (90 °c) and water formation from view point of salinity and divalent cations, was evaluated on the gelation kinetic and gel strength using bottle testing method. the re...

this paper introduces an innovative partially destructive method, called “twist-off”, for the assessment of in situ concrete strength. in this method a 40mm diameter metal probe is bonded to a concrete surface by means of a high strength epoxy resin adhesive. to measure the concrete compressive strength, a torque is applied using an ordinary torque-meter and the maximum shear stress at failure ...

in this paper, we introduce the new class of implicit l-stable generalized hybrid methods forthe numerical solution of first order initial value problems. we generalize the hybrid methodswith utilize ynv directly in the right hand side of classical hybrid methods. the numericalexperimentation showed that our method is considerably more efficient compared to wellknown methods used for the numer...

Certain symmetric linear multistep methods have an excellent long-time behavior when applied to second order Hamiltonian systems with or without constraints. For high accuracy computations round-off can be the dominating source of errors. This article shows how symmetric multistep methods should be implemented, so that round-off errors are minimized and propagate like a random walk.

In several recent publications, numerical integrators based on Jacobi elliptic functions are proposed for solving the equations of motion of the rigid body. Although this approach yields theoretically the exact solution, a standard implementation shows an unexpected linear propagation of round-off errors. We explain how deterministic error contribution can be avoided, so that round-off behaves ...

Little attention has focused so far on evaluating the success of online communities. This paper starts to identify some key determinants of sociability and usability that help to determine their success. Determinants of sociability include obvious measures such as the number of participants in a community, the number of messages per unit of time, members’ satisfaction, and some less obvious mea...

Abstract. We construct, analyze and numerically validate a class of conservative, discontinuous Galerkin schemes for the Generalized Korteweg-de Vries equation. Up to round-off error, these schemes preserve discrete versions of the first two invariants (the integral of the solution, usually identified with the mass, and the L–norm) of the continuous solution. Numerical evidence is provided indi...

In this note is presented a method, given nodal values on multidimensional nonconforming spectral elements, for calculating global Fourier-series coefficients. This method is “exact” in that given the approximation inherent in the spectral-element method (SEM), no further approximation is introduced that exceeds computer round-off error. The method is very useful when the SEM has yielded an ada...

time, cost and quality are considered as the main components in managing each project. previous researches have mainly focused on the time-cost trade-off problems. recently quality is considered as the most important factor in project�s success, which is influenced by time acceleration that is the less time is spent the more success is gained. in time-cost-quality trade-off problems, each act...

cumin (cuminum cyminum) is an annual suitable for the dry and semi-dry areas of iran. recently, farmers have chosen to plant cumin because it requires less water and growth time. however, at harvest time, the resistance of cumin seed to shatter is low and, if careful attention is not paid to this fact, a major portion of the crop can be lost. when the connection force of the seed decreases, see...