نشریه تصمیم گیری و تحقیق در عملیات
سال چهارم شماره 3 (پاییز 1398)

In this paper, we present a method for charaterizing the solution set of nonconvex optimization problems via their dual problems. In fact, the constrainted optimization problem which is considerd has pseudoconvex and locally Lipschitz functions, which are not necessarily convex and smooth, and include a wide class of non-convex non-smooth functions. In the proposed method, a dual problem is formulated to characterizations of the solution set of the primal problem in a mixed type of Wolfe type and Mond-Weir type. First, we introduce some of the properties of the Lagrangian functions associated to these problems and then we explain the proof of the characterization of their solution sets.

Shortest path problem is one of the practical issues in optimization, and there are many efficient algorithms in this area. In this issue, a network of some nodes and arcs is considered in which, each arc has a specific parameter such as distance or cost. The main objective is to find the shortest or least costly route between two distinct points. By considering an additional parameter and adding a new limitation, as a capacity constraint, the problem will be closer to the real world condition. This extended issue is known as the constrained shortest path problem and has a higher complexity order and practical algorithms are needed to solve it. In this study, an effective algorithm is presented that obtains the optimal solution within a short time. In this method, a repetitive pattern is used so that, in each iteration, the relaxed model, after adding a logical cut, is solved. The results of the implementation of the proposed algorithm on different networks show its efficiency.

In today’s highly competitive business environment, which is known by characteristics of low profitability, high customer expectations for high quality products and a minimum waiting time, make companies efforts to transform constraints into opportunities for gaining competitive advantage by optimizing their business processes. In such situation, appropriate supplier selection can play a key role in the efficiency and effectiveness of the organization and have a direct impact on reducing costs, profitability and flexibility of a company.The purpose of this research is to provide a supplier selection model with simultaneous consideration of two sources of inventory control and pricing in the supply chain. To assess the validity and reliability of the model, the actual data of the Seven Diamond Industries Company including input materials (Hot Roll) and products (galvanized sheets) have been used. Proposed model is coded in the GAMS software and its results have been analyzed.

Crises are the inevitable realities of human life; which is an accident that occurs naturally or suddenly or increasingly by human and to address it, there is a need for urgent and fundamental measures.When the crisis occurs, pre-determined storage locations will play an important role in relief; therefore, the selection of suitable places for warehouses is one of our main goals in this research. In this research, a bi-objective linear programing model with integer variables is developed. The proposed model attempt to minimize total cost along with maximizing the minimum weight of open shelter areas while deciding on the location of shelter areas, the assigned population points to each open shelter area and controls the utilization of open shelter areas. In order to solve proposed model, some of well-known multi-objective, exact methods includes a weighted sum method, LP-metric method, and goal programing approach are employed.Finally, the best open shelter areas with considering the minimum cost is obtained, which these results can be useful for crisis organizations.

Balanced Scorecard used as a tool of strategic assessment and suggested that all performance of organizations should not only be studied financial metrics but must non-financial metrics also be considered. BSC concept encompasses a larger area of the business segment. However, Balanced Scorecard is in practice very complex and in terms of the measurement system and implementation is very successful. But it could be concluded that there are still shortcomings which some scholars have identified it. For this reason were suggested innovative methods to reform the traditional model and performance indicators, such as Balanced Scorecard Knowledge-Based System (BSCKBS), the Proactive BSC Methodology (PBCSM), Lean Balanced Scorecard Card (LBSC), Balanced IT Scorecard (BITS), BSC - Analytic Network Process (ANP) and BSC - Control Objectives for Information Technology (COBIT). In the present study, innovative methods were introduced for reform the traditional model of BSC according to historical recognition method, were studied. The results show that in recent year's wealth of researches is done on the use of new approaches in the field of management accounting in particular BSC, with the aim of eliminating defects in the traditional model and help in decision making for strategic decision making.

The problem of solving optimal control of Singular problems in the classic method has a complexity that is solved by approximation of the equations in the problem with orthogonal bases instead of solving the dynamic equation system of a set of static problems. In return for a more relaxed solution, it will face some errors in the computation .however, it has an appropriate precision. Legendre and Fourier series are presented using the specifications of the Fourier transform of Legendre and Fourier series . In this algorithm, the state variables, and the state - derivative variables and the control vector are extended by the orthogonal basis of Legendre and Fourier series with unknown coefficients. in order to compute optimal control vector and optimal path of linear Singular systems with quadratic cost function , we are introduced by using the properties of orthogonal functions introduced by the coefficients and .using the proposed method , the system dynamics are converted into algebraic equations and the problem of dynamic optimization of dynamic space has been mapped to static space optimization problem with quadratic cost function and linear constraints . First, it is used to solve the problem using an orthogonal basis of raw material and then the problem solving with orthogonal basis of Fourier series is repeated. Finally, the application and effectiveness of the proposed method are presented.

Organizational culture is one of the core values in an organization and it makes organizations different .Organizational culture plays an underlying role in enhancing the quality of service delivery, and enhances cohesion and increases productivity and innovation in the organization. The main purpose of this study is to determine the organizational culture level at Golnour Company by using Denison's model. The research is of theoretical and applied type and the data used are of quantitative type, the Denison organizational culture questionnaire was used for data collection. The statistical population of the study consists of managers and staff of Glenour Company in Isfahan province. The research data were analyzed by Kruskal-Wallis test, plotting histograms, concentration and dispersion data analysis and Spearman correlation test. The results show that all indicators and items are strongly correlated and neglecting the poor performance in each of the indicators will affect other aspects of organizational culture and will lead to undesirable intra-organizational and extra-organizational outcomes in different dimensions.