The telecommunications industry continues to experience fierce competition due to the growth in subscribers and the rapid development of new technologies in the sector. With that hindsight, this study explores the dimensionality of factors that affect mobile phone subscribers’ intention to switch operators. Survey data was collected from 235 mobile phone network subscribers and analyzed using the Partial Least Square Approach to Structural Equation Modelling (SEM). The SEM model was assessed based on the measurement model and the structural model. Factor Loadings, Cross Loadings, Average Variance Extracted Cronbach’s alpha, and Composite reliabilities of the latent variables examined showed that the measurement model exhibited sufficient reliability, discriminant validity and convergent validity. Assessment of the Structural model shows that 77% of the variation in Satisfaction is explained by our model (R2 = 0.77). Furthermore, 18% (R2 = 0.18) of the variation in Intention to Switch was explained by the model. Stone-Geiser Q2 for the endogenous showed that the proposed Structural Equation Model exhibited sufficient predictive relevance. Conclusions were drawn with practical implications of the results also discussed.

This paper examines the optimization of production involving a tandem two-machine system producing a single part type, with each machine being subject to random breakdowns and repairs. An analytical model is formulated with a view to solving an optimal stochastic production problem of the system with machines having up-downtime non-exponential distributions. The model developed is obtained by using a dynamic programming approach and a semi-Markov process. The control problem aims to find the production rates needed by the machines to meet the demand rate, through a minimization of the inventory/shortage cost. Using the Bellman principle, the optimality conditions obtained satisfy the Hamilton-Jacobi-Bellman equation, which depends on time and system states, and ultimately, leads to a feedback control. Consequently, the new model enables us to improve the coefficient of variation (CVup/down) to be less than one while it is equal to one in Markov model. Heuristics methods are used to involve the problem because of the difficulty of the analytical model using several states, and to show what control law should be used in each system state (i.e., including Kanban, feedback and CONWIP control). Numerical methods are used to solve the optimality conditions and to show how a machine should produce.

A new analytical approach was proposed to monitor the reaction between epoxidized soybean oil and diethylene glycol in the presence of ZnCl2 as an epoxide ring opening catalyst for microwave assisted synthesis of polyol. Infrared spectra of the products were used as the input data, being processed by multivariate curve resolution – alternating least squares (MCR-ALS) for quantitative monitoring. The data obtained in different MW powers were analyzed by MCR factor analysis coupled with ALS optimization procedure. Standard deviation of residuals for experimental data and the variance explained at the optimum condition (r2) were 0.135 and 97.24% respectively.

During the past two decades, there has been a growing concern on environmental issues around the world. Firms try to provide better production plans to recycle their used materials to reduce pollution from environment. In fact, lack of management in municipal solid waste for methods of collecting, disposal and processing of them can be significant damage to the environment, This paper presents a mathematical model for pet waste management, which plays essential role on municipal solid waste. The modeling formulation is a nonlinear probable mathematical programming model for chemical recycling the PET waste. In this model, the optimal amount of waste is determined by considering collected operations of reverse logistics and chemical recycling when demand is under uncertainty.

During the past few decades, many organizations have attempted to increase their productivity
through outsourcing parts of their responsibilities. Outsourcing helps firms reduce their low
value added activities and focus on their high value added activities. It also helps organization
save their time and energy which leads to more efficient units. The idea of outsourcing is more
important for project based organizations where the nature of works is different from a
particular project to another one. This paper presents an integrated balanced score card system
with an adaptation of ELECTRE III method to select suitable resources for outsourcing. The
proposed model of the paper is implemented for a case study of subway system in Iran and the
results are discussed.

One of the primary concerns on supply chain management is to select appropriate suppliers based on different criteria, which are often in serious conflict. In this paper, we present a fuzzy TOPSIS technique to prioritize suppliers on reverse logistic network based on different criteria and then the proposed model of this paper applies fuzzy linear programming technique to determine optimum order quantity associated with each supplier. There are three criteria associated with each supplier including technical skills, equipment and ability to analyze. The implementation of the proposed method has been demonstrated in case study.

This paper proposes the social network analysis (SNA), to study interaction among various
activities in a product development process (PDP). The implementation of SNA helps to
measure the properties of information flow and identifies PDP activities and limitations. The
findings of an exploratory research project which explores the potential of SNA, as an improve
tool for visually mapping and analyzing the stakeholders relationships found across the IC
substrates design/manufacturing’s PDP of the Unimicron Technology Corp. From the findings,
the authors prescribe the necessary SNA recommendations to improve the social conditions
within the PDP.

In this paper, a bi-objective mathematical model for emergency services location-allocation
problem on a tree network considering maximum distance constraint is presented. The first
objective function called centdian is a weighted mean of a minisum and a minimax criterion
and the second one is a maximal covering criterion. For the solution of the bi-objective
optimization problem, the problem is split in two sub problems: the selection of the best set of
locations, and a demand assignment problem to evaluate each selection of locations. We
propose a heuristic algorithm to characterize the efficient location point set on the network.
Finally, some numerical examples are presented to illustrate the effectiveness of the proposed
algorithm.

The economic lot scheduling problem (ELSP) is a challenge between sequencing and lot sizing. In this problem, several products must be produced on a single machine in a cyclical production pattern and the primary goal is to minimize the total setup and holding expenditures. Since time affects the value of money, it is necessary to take into account the time value of money when gradual payment is the case. In this paper, a new ELSP model with the consideration of the time value of money is considered. The proposed model of this paper is formulated as a nonlinear mixed integer model and a hybrid GA is presented to solve the resulted model for large-scale problems. The proposed method is solved for some benchmark problems for large-scale problems.

One of the most important issues on quality of building structure is its resistance against
earthquake. Earthquake, as one of natural disasters, has been one of the main reasons of fatal
incidents in developing countries. Any attempt to increase the quality of building structure
could reduce any possible damages an earthquake could cause on society. This paper presents a
system dynamic model to study the importance and behavior of the factors which affect the
construction quality of buildings & apos; structures. The proposed model of this paper is analyzed for a
case study and the results are discussed. The paper also uses DEMATEL technique to compare
the results of the proposed method. The paper concludes that among the whole factors which
affect the construction quality of buildings & apos; structures, the "performance of related
organizations and institutions" is of the most important ones.