we study the history and recent developments in nonelementarymodel theory focusing on the framework of abstractelementary classes. we discuss the role of syntax and semanticsand the motivation to generalize first order model theory to nonelementaryframeworks and illuminate the study with concrete examplesof classes of models. this first part introduces the main conceps and philosophies anddiscu...

The time - cost tradeoff problem is one of the most critical issues in the project scheduling field and so far, a lot of research has been done with a variety of quantitative and qualitative approaches on this subject. In this research, we intend to provide a two - objective mathematical model which balances crash and delay for activities. So that it provides the right tools for decision makers...

this paper investigates the problem of just-in-time permutation flow shop scheduling with limited buffers and linear job deterioration in an uncertain environment. the fuzzy set theory is applied to describe this situation. a novel mixed-integer nonlinear program is presented to minimize the weighted sum of fuzzy earliness and tardiness penalties. due to the computational complexities, the prop...

the first purpose of this study is to present an alternative robust model in order to describe ruminal degradation kinetics of forages and to minimize the fitting problems. for this purpose, the korkmaz-uckardes (ku) model, which has a logarithmic structure, was developed. the second purpose of this study is to estimate, by using the korkmaz-uckardes (ku)model, the parameters tp (the time to pr...

for non-darcy flow in submerged porous media a one- dimensional mathematical model has been developed. rockfill detention dams are one of these porous media that comprised of relatively homogenous coarse rockfill which can be used to reduce flood discharge and hydrograph peak. in this research the focus was on the rockfill detention dams in submerged condition. the existence of overtopping rock...

One of the most important issues in area of health and hygiene is location-allocation of organ harvesting centers and transplant centers according to coordination between supply and demand. In this paper, a mathematical model is presented for location-allocation of organ harvesting centers and transplant centers. The proposed model does not only minimize the present value of the total system co...

This study obtains some wave solutions of the B-type Kadomtsev Petviashvili equation by applying modified exponential function method (MEFM). Due to nature MEFM, two different cases are presented here, which we analyzed obtain more in this structure. More can be obtained analyzing situations. When resulting analyzed, hyperbolic, trigonometric, and rational functions observed. It has been checke...