Showing 7 results for Rezaie
M. Rezaiee-Pajand and M.r. Salari,
Volume 15, Issue 1 (7-1994)
Abstract
This paper is about discrete sensitivity analysis. A triangular bending element with constant moment and six degrees of freedom is used. The required derivatives for sensitivity analysis are calculated explicitly. These formulations, finite element method and sequential linear programming are utilized to find shape optimization of plate bending structures. The numerical examples, which show the ability of the derivatives, are presented.
M. Rezaiee-Pajand and H. Asghari,
Volume 15, Issue 2 (1-1997)
Abstract
This paper is on the elasto-plastic analysis of plane stress problems. A five-parameter yield surface is presented. This yield criterion uses associate flow along with mixed hardening rule. The analytical formulations are written and related computer program for non-linear analysis is prepared. Finally, based on the formulations, numerical examples are solved.
M. Rezaiee – Pajand and S. Payman,
Volume 21, Issue 2 (1-2003)
Abstract
This paper discusses the effective length factor of columns in Khorjini frames. In order to find this factor, a proper approximated method is proposed. In addition, accurate analysis is performed and the results are compared with those from the proposed technique. The comparison demonstrates the accuracy of presented FORMULATIONS. The proposed method is similar to Julian and Lawrence's, which is used for rigid frames.
Keywords: Khorjini Frame, Effective Length, Bifuraction Load, Rotational Stiffness, Matrix Structural Analysis, Column Factor.
M. Rabbani, K. Rezaie, M. M. Lotfi and M. Abadi,
Volume 23, Issue 1 (7-2004)
Abstract
In this paper, a new method for developing a lower bound on exact completion time distribution function of stochastic PERT networks is provided that is based on simplifying the structure of this type of network. The designed mechanism simplifies network structure by arc duplication so that network distribution function can be calculated only with convolution and multiplication. The selection of duplicable arcs in this method differs from that of Dodin’s so that it must be considered a different method. In this method, best duplicable arcs are adopted using a new mechanism. It is proved that duplicating numbers is minimized by this method. The distribution function of this method is a lower bound on exact network distribution function and an upper bound on distribution function of Dodin’s and Kleindorfer’s methods. After the algorithm for the method is presented, its efficiency is discussed and illustration examples will be used to Compare numerical results from this method with those from exact network distribution and Dodin’s method.
Gh. Moslehi and A. R. Rezaie,
Volume 23, Issue 2 (1-2005)
Abstract
In this paper, two-dimensional cutting stock problem with demand has been studied.In this problem, cutting of large rectangular sheets into specific small pieces should be carried out hence, the waste will be minimized. Solving this problem is important to decrease waste materials in any industry that requires cutting of sheets. In most previus studies, the demand of pieces has not been usually considered. The cutting problems belong to the category of Np-hard problems. So finding a desirable solution in a suitable time is practically impossible and heuristic methods must be used. A meta-heuristic algorithm using SA approach is presented.Then attempt will be made to regulate the SAs parameters. Initial solutions are produced with a rule based
algorithm and two internal and main SAs are used that lead to better performance of the algorithm. Due to lack of benchmark or test problems, two procedures for generating random problems is presented and are used to study efficiency of the algorithm. For this purpose, problems about 10 to 50 types of pieces with maximum demands of 2400 are generated and solved using the proposed algorithm. The results indicate that the algorithm capable of finding a solution with less than 6% of waste for problems with 30 types of pieces and total demands of 500.
Rabbani, K. Rezaie and N. Seid Foroush Lahiji,
Volume 24, Issue 1 (7-2005)
Abstract
Time-cost trade-off is one of the most important subjects in project management and of interest to contractors. The goal of time-cost trade-off is sensivity analysis of project costs to changes in activity duration in order to obtain the best combination of activity duration decrease, in a way that the sum of project costs is minimized. In the heuristics presented in this area, time crashing is on the base of the minimum cost slope of activities. But since projects are usually performed over
long periods, they can be affected by interest rate. In this paper, a new heuristic algorithm is presented in order to obtain the best combination of activity duration decrease while the monetary value is taken into account, with the goal of minimizing the sum of present value of project costs
N. Zakeri, H.r. Rezaie, J. Javadpour, M. Kharaziha,
Volume 39, Issue 4 (Journal of Advanced Materials-Winter 2021)
Abstract
In recent years, nanoceramics have been used in scaffolds to emulate the nanocomposite with a three-dimensional structure of natural bone tissue. In this regard, polycaprolactone biopolymer is widely used as a scaffold in bone tissue engineering. The goal of this research is to produce porous scaffolds of polycaprolactone - zeolite biocomposite with suitable mechanical, bioactive and biological properties for bone tissue engineering applications. The nanocomposite scaffolds were synthesized by solvent casting/particulate leaching and freeze-drying approaches. Microscopic investigations showed generation of pores with an average size of 200-400μm after addition of ceramic phase. Energy dispersive X-ray analysis confirmed uniform distribution of ceramic phase in polycaprolactone matrix. FTIR results determined the binding type of zeolite nanoparticles to the polycaprolactone matrix as physical bonding. The results of mechanical tests showed the increase in young’s modulus after addition of ceramic phase (from 0.04 to 0.3 and 3 to 7 MPa, respectively). The hydrophilicity of polycaprolactone increased after adding nanozeolite and more weight loss was observed for scaffold containing 20% zeolite (53.52 6 1.6%) with an increase in the rate of hydroxyapatite formation. The results showed that the prepared scaffolds have potential for cancellous bone tissue engineering application.
