Reverse supply chain is a process dealing with the backward flows of used/damaged products or materials. Reverse supply chain includes activities such as collection, inspection, reprocess, disposal and redistribution. A well-organized reverse supply chain can provide important advantages such as economic and environmental ones. In this study, we propose a general framework and formulate a m...

In the present paper, we consider a mathematical model of two microbial species competing for two complementary nutrients with internal storage and different removal rates. The competitive exclusion, coexistence, and bi-stabilty are predicted in this model as those in the two-species Lotka-Volterra competition model.

Even if Computer-Aided Geometric Design modelers are now based on powerful mathematical models for curves and surfaces, there are important needs for tools to create, analyze and modify these objects. Designing product shapes with free-form curves and surfaces is still a tedious task and modifying the shape obtained is even more difficult and, most of the time, needs recreating a part up to the...

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...

During the clinical years, medical students frequently experience physical and mental health problems, which are exacerbated by their work schedules. To address this issue, we develop a bi-objective mathematical model in study. The two objectives of 1) balancing workload each student group 2) minimizing deviation among groups. In addition, includes constraints on ward rotation sequencing. requi...

The transportation of hazardous materials is always accompanied by considerable risk that will impact public and environment security. As an efficient and reliable transportation organization, a multimodal service should participate in the transportation of hazardous materials. In this study, we focus on transporting hazardous materials through the multimodal service network and explore the haz...

The multi-objective optimization problem is the main purpose of generating an optimal set of targets known as Pareto optimal frontier to be provided the ultimate decision-makers. The final selection of point of Pareto frontier is usually made only based on the goals presented in the mathematical model to implement the considered system by the decision-makers. In this paper, a mathematical model...

Today, sustainable development is one of the important issues in regard to the economy of a country. This issue magnifies the necessity for increased scrutiny towards issues such as environmental considerations and product recovery in closed-loop supply chains (CLSCs). The most important motivational factors influencing research on these topics can be considered in two general groups: environme...

Recently, scholars and practitioners have shown an increased interest in the field of sustainable supplier selection and order lot-sizing. While several studies have recently carried out on this field, far too little attention has been given to formulating a multi-objective model for the integrated problem of multi-period multi-product order lot-sizing and sustainable supplier selection under i...