Duman E.,Ozyegin University |
Uysal M.,Dogus University |
Alkaya A.F.,Marmara University
Information Sciences | Year: 2012
We propose a new nature inspired metaheuristic approach based on the V flight formation of the migrating birds which is proven to be an effective formation in energy saving. Its performance is tested on quadratic assignment problem instances arising from a real life problem and very good results are obtained. The quality of the solutions we report are better than simulated annealing, tabu search, genetic algorithm, scatter search, particle swarm optimization, differential evolution and guided evolutionary simulated annealing approaches. The proposed method is also tested on a number of benchmark problems obtained from the QAPLIB and in most cases it was able to obtain the best known solutions. These results indicate that our new metaheuristic approach could be an important player in metaheuristic based optimization. © 2012 Elsevier Inc. All rights reserved.
Uykan Z.,Dogus University
IEEE Transactions on Neural Networks and Learning Systems | Year: 2013
The Hopfield neural network (HNN) has been widely used in numerous different optimization problems since the early 1980s. The convergence speed of the HNN (already in high gain) eventually plays a critical role in various real-time applications. In this brief, we propose and analyze a generalized HNN which drastically improves the convergence speed of the network, and thus allows benefiting from the HNN capabilities in solving the optimization problems in real time. By examining the channel allocation optimization problem in cellular radio systems, which is NP-complete and in which fast solution is necessary due to time-varying link gains, as well as the associative memory problem, computer simulations confirm the dramatic improvement in convergence speed at the expense of using a second nonlinear function in the proposed network. © 2012 IEEE.
Kumru M.,Dogus University |
Kumru Pi.Yi.,Kocaeli University
Applied Soft Computing Journal | Year: 2013
Failure mode and effects analysis (FMEA) is one of the well-known techniques of quality management that is used for continuous improvements in product or process designs. While applying this technique, determining the risk priority numbers, which indicate the levels of risks associated with potential problems, is of prime importance for the success of application. These numbers are generally attained from past experience and engineering judgments, and this way of risk assessment sometimes leads to inaccuracies and inconsistencies during priority numbering. Fuzzy logic approach is preferable in order to remove these deficiencies in assigning the risk priority numbers. In this study, a fuzzy-based FMEA is to be applied first time to improve the purchasing process of a public hospital. Results indicate that the application of fuzzy FMEA method can solve the problems that have arisen from conventional FMEA, and can efficiently discover the potential failure modes and effects. It can also provide the stability of process assurance. © 2012 Elsevier B.V.
Kumru M.,Dogus University
Applied Soft Computing Journal | Year: 2013
Quality control systems focus on maintaining standards in manufactured products. To improve the homogeneity of batches received by final users and to detect manufacturing defaults, a visual control stage is integrated into production line before the packing operation. At this stage, the products are inspected, mostly by human eye, for their obvious external defects; e.g., chips, cracks, scratches, holes and pitting, lumps, spots, notches, and glazing. This task is often referred to as visual inspection which is important to categorize the final products into quality-constant batches. Prototypes are of invaluable help while inspecting the visual attributes of products. Visual quality of products is assessed with respect to these standard units and some quality ratings are made there on the results. However, assessing visual quality is somewhat an ambiguous and troublesome work. Therefore, it will be helpful to utilize a decision making technique, such as fuzzy logic, to facilitate and improve the process. This paper addresses first to the significance of visual inspection and assessment of visual quality of industrial products, and second, gives a unique application of visual quality assessment of vitreous china ceramic sanitary wares by using fuzzy logic method. © 2013 Elsevier B.V. All rights reserved.
Gozgor G.,Dogus University
Journal of International Trade and Economic Development | Year: 2014
Recent and ongoing literature strongly implies the existence of a significant and robust impact of trade openness (liberalisation) and globalisation on unemployment, particularly in developed economies. This paper empirically investigates the impacts of four different measures of trade openness and globalisation on the unemployment rate in an unbalanced panel framework. The analysis focuses on the G7 countries: Canada, France, Germany, Italy, Japan, the United Kingdom (UK), and the United States (US). Robust empirical findings from panel data estimates demonstrate that, along with macroeconomic indicators and market size, all the measures of trade openness and globalisation are significantly and negatively associated with the unemployment rate. Therefore, we conclude that the continuation of the globalisation process instead of protectionism is of great importance in reducing the unemployment rate in developed economies. © 2013, © 2013 Taylor & Francis.