Serafettin Alpay - Academia.edu (original) (raw)

Papers by Serafettin Alpay

Eskişehir Osmangazi Üniversitesi Mühendislik ve Mimarlık Fakültesi Dergisi, Jun 30, 2008

International Journal of Energy Research, 2006

Predictions of wind energy potential in a given region are based on on-location observations. The... more Predictions of wind energy potential in a given region are based on on-location observations. The time series of these observations would later be analysed and modelled either by a probability density function (pdf) such as a Weibull curve to represent the data or recently by soft computing techniques, such as neural networks (NNs). In this paper, discrete Hilbert transform has been applied to characterize the wind sample data measured on I Á zmir Institute of Technology campus area which is located in Urla, I Á zmir, Turkey, in March 2001 and 2002. By applying discrete Hilbert transform filter, the instantaneous amplitude, phase and frequency are found, and characterization of wind speed is accomplished. Authors have also tried to estimate the hourly wind data using daily sequence by Hilbert transform technique. Results are varying.

In a job shop production system, assigning exact due dates is an important task for scheduling pe... more In a job shop production system, assigning exact due dates is an important task for scheduling performance. On the other hand, predicting due dates accurately is very difficult because of several decision factors should be considered. Many due date assignment models proposed in the literature but none of them is perfect and can produce the best due dates for all jobs arrived to the dynamic job shop environment. So using more than one due date assignment model for all job set may be reasonable. In this study a dynamic solution methodology for determining the most appropriate due date assignment models for the jobs arrived to the shop to optimize the aimed objective function by considering the related decision factors in a dynamic job shop environment is presented.

Scientia Iranica

This paper proposes a new linearized mathematical model to solve integrated cell formation and jo... more This paper proposes a new linearized mathematical model to solve integrated cell formation and job scheduling problem. The model aims to minimize the exceptional elements, voids and the make-span of the jobs. The results of test problems show that the proposed model is very effective to obtain best solutions for small sized problems in reasonable computation times. However, due to the NP-hard nature of the considered problem, the best solutions couldn't be obtained in acceptable times for large sized test problems whereas the real-life applications of the problem addressed here are often much larger in size. To meet the requirement of solving larger sized problems, Genetic Algorithm (GA), which is, today, considered as one of the artificial intelligence and machine learning technique and Marine Predators Algorithm (MPA) as a new and a nature-inspired metaheuristic, are proposed. The success of the algorithms was investigated and compared. The test results reveal the fact that the MPA with optimized parameters has a high potential to solve real life problems. At last, an attempt is made to redesign an existing real-life production system by the proposed algorithms. Eventually, a considerable improvement is obtained on performance compared to the current situation of the system.

International Conference on Information Technology: New Generations, 2008

Shop-floor control system plays important role to handle the problems come from the dynamic natur... more Shop-floor control system plays important role to handle the problems come from the dynamic nature of the shop- floor. In this study, an Agent-Based Shop-Floor Control System is designed. Agents in the system are Marketing Agent, Production Planning Agent, Purchasing Agent and Shop-Floor Agents: Job, Machine and Cell. Designed distributed system contains heterogeneous units and was designed as hybrid control

GAZI UNIVERSITY JOURNAL OF SCIENCE

Highlights • The paper focuses on an integrated cell formation and part scheduling problem. • The... more Highlights • The paper focuses on an integrated cell formation and part scheduling problem. • The objectives of the proposed model are the minimization of EEs in cells and makespan of the jobs. • The validity of the model is tested on numerical examples that are derived from the literature. • The developed mathematical model improves the overall system performance.

International Journal of Mining, Reclamation and Environment

Open Geosciences

Deciding on equipment from a set of feasible alternatives for excavation purpose in open pit mine... more Deciding on equipment from a set of feasible alternatives for excavation purpose in open pit mines is a critical task for the engineers and contractors since it considerably affects the project costs and productivity. Alternatives of rock excavation equipment, which are deemed suitable for the diggability of rock units in open pits, can have many technical specifications or factors that should be considered simultaneously. It can be successfully selected in a scientific way by employing multi-criteria decision making methods by means of taking the advantage of engineering knowledge, intuition and past experiences. In this study, we select the most convenient hydraulic excavator for a magnesite mine by fuzzy multi criteria decision making methods: fuzzy TOPSIS and fuzzy VIKOR. The fuzzy approach allows the experienced engineers to compare the multiple criteria (technical factors) and the possible alternatives of rock excavation machines by simply using linguistic expressions in their...

Expert Systems with Applications, 2016

International Journal of Production Research, 2009

... The experimental results show that the ANN-based due date assignment models are superior to t... more ... The experimental results show that the ANN-based due date assignment models are superior to the regression-based and conventional models. ... Main Effects Plot for MSL Due Date Model Dispatching Rule Shop Util. Rate MAL MSL Figure 1. Main effects plot for MAL and MSL. ...

Iea Aie, 2007

ABSTRACT Although most real manufacturing systems have dynamic job shop structures, there is no g... more ABSTRACT Although most real manufacturing systems have dynamic job shop structures, there is no general analytic method that has been found for analyzing them yet and computer simulation is still an outstanding tool. One of the most difficult problems in a dynamic job shop environments is to assign the optimal due dates. Due date assignment is an important task in shop-floor control, affecting both timely delivery and customer satisfaction. The ability to meet the due dates, however, is dependent not only on reasonableness of the due dates but also on the scheduling or dispatching procedures. In this paper, an agent based dynamic job shop simulation system is designed and developed to help the decision makers who have to mainly solve the problems of selecting correct due date assignment models and dispatching rules depending on selected performance criteria in their multi machine dynamic stochastic job shop environment.

Lecture Notes in Computer Science, 2006

ABSTRACT In this research, the factors have significant effect on due date predictability for on ... more ABSTRACT In this research, the factors have significant effect on due date predictability for on time delivery in a dynamic job shop were studied. For this aim a new due date assignment model was proposed and an experimental study in a simulated dynamic job shop was performed. The results indicate that the proposed due date assignment model is adequate to meet the assigned due dates for on time delivery and the number of jobs in the queues of the machines on a job’s route is the most important factor affects the due date predictability.

Lecture Notes in Computer Science, 2007

ABSTRACT Although most real manufacturing systems have dynamic job shop structures, there is no g... more ABSTRACT Although most real manufacturing systems have dynamic job shop structures, there is no general analytic method that has been found for analyzing them yet and computer simulation is still an outstanding tool. One of the most difficult problems in a dynamic job shop environments is to assign the optimal due dates. Due date assignment is an important task in shop-floor control, affecting both timely delivery and customer satisfaction. The ability to meet the due dates, however, is dependent not only on reasonableness of the due dates but also on the scheduling or dispatching procedures. In this paper, an agent based dynamic job shop simulation system is designed and developed to help the decision makers who have to mainly solve the problems of selecting correct due date assignment models and dispatching rules depending on selected performance criteria in their multi machine dynamic stochastic job shop environment.

Lecture Notes in Computer Science, 2007

Underground mining method selection (UMMS) is one of the most important decisions that should be ... more Underground mining method selection (UMMS) is one of the most important decisions that should be made by mining engineers. Choosing a suitable underground mining method to carry out extraction from a mineral deposit is very important in terms of the economics, ...

Fifth International Conference on Information Technology: New Generations (itng 2008), 2008

ABSTRACT Shop-floor control system plays important role to handle the problems come from the dyna... more ABSTRACT Shop-floor control system plays important role to handle the problems come from the dynamic nature of the shop- floor. In this study, an Agent-Based Shop-Floor Control System is designed. Agents in the system are Marketing Agent, Production Planning Agent, Purchasing Agent and Shop-Floor Agents: Job, Machine and Cell. Designed distributed system contains heterogeneous units and was designed as hybrid control architecture. The study focuses on constructing an Agent-Based Shop-Floor Control System which has ability to manage dynamic scheduling activities. Shop-Floor Agents work in a harmony with each other in order to generate the schedules dynamically.

Tunnelling and Underground Space Technology, 2009

Underground mining method selection is one of the most important decisions that mining engineers ... more Underground mining method selection is one of the most important decisions that mining engineers have to make. Choosing a suitable underground mining method to extract a mineral deposit is very important in terms of economics, safety and productivity of mining ...

Journal of Mining Science, 2008

ABSTRACT The authors propose a number of modified versions of well-known multicriterion optimizat... more ABSTRACT The authors propose a number of modified versions of well-known multicriterion optimization methods and discuss their application to select an optimal underground chromite mining technique.

ABSTRACT This research presents a new application of greedy randomised adaptive search procedure ... more ABSTRACT This research presents a new application of greedy randomised adaptive search procedure (GRASP) to address a production sequencing problem for mixed-model assembly line in a just-in-time (JIT) production system in two different cases. In the former case, small size sequencing problems are considered and two objectives are presented; minimisation of setups and optimisation of stability of material usage rates. These two objectives are inversely correlated with each other, so simultaneous optimisation of both is challenging. This type of problem is NP-hard. The GRASP, with path relinking, searches for efficient frontier where simultaneous optimisation of number of setups and usage rates is desired. Several test problems are solved via GRASP and its performance is compared to solutions obtained via complete enumeration and simulated annealing (SA), tabu search (TS) and genetic algorithms (GA) approaches from the literature. Experimental results reveal that the GRASP with path relinking provides near-optimal solutions in terms of the two objectives and its 'average inferiority%' and 'average percentile' performances are superior to that of other heuristics. In the latter case, the goal is to explore varying the emphasis of these two conflicting objectives. Larger sequencing problems are considered and solved via GRASP with path relinking. Its objective function values are compared to the solutions obtained via a SA approach from the literature. Experimental results show that GRASP also provides good performance on large size problems and its percentage improvement is better than that of SA. Overall results also show, however, that the GRASP performs poorly with regard to CPU time.

International Journal of Production Research, 2009

ABSTRACT This research presents a new application of greedy randomised adaptive search procedure ... more ABSTRACT This research presents a new application of greedy randomised adaptive search procedure (GRASP) to address a production sequencing problem for mixed-model assembly line in a just-in-time (JIT) production system in two different cases. In the former case, small size sequencing problems are considered and two objectives are presented; minimisation of setups and optimisation of stability of material usage rates. These two objectives are inversely correlated with each other, so simultaneous optimisation of both is challenging. This type of problem is NP-hard. The GRASP, with path relinking, searches for efficient frontier where simultaneous optimisation of number of setups and usage rates is desired. Several test problems are solved via GRASP and its performance is compared to solutions obtained via complete enumeration and simulated annealing (SA), tabu search (TS) and genetic algorithms (GA) approaches from the literature. Experimental results reveal that the GRASP with path relinking provides near-optimal solutions in terms of the two objectives and its 'average inferiority%' and 'average percentile' performances are superior to that of other heuristics. In the latter case, the goal is to explore varying the emphasis of these two conflicting objectives. Larger sequencing problems are considered and solved via GRASP with path relinking. Its objective function values are compared to the solutions obtained via a SA approach from the literature. Experimental results show that GRASP also provides good performance on large size problems and its percentage improvement is better than that of SA. Overall results also show, however, that the GRASP performs poorly with regard to CPU time.

Eskişehir Osmangazi Üniversitesi Mühendislik ve Mimarlık Fakültesi Dergisi, Jun 30, 2008

International Journal of Energy Research, 2006

Predictions of wind energy potential in a given region are based on on-location observations. The... more Predictions of wind energy potential in a given region are based on on-location observations. The time series of these observations would later be analysed and modelled either by a probability density function (pdf) such as a Weibull curve to represent the data or recently by soft computing techniques, such as neural networks (NNs). In this paper, discrete Hilbert transform has been applied to characterize the wind sample data measured on I Á zmir Institute of Technology campus area which is located in Urla, I Á zmir, Turkey, in March 2001 and 2002. By applying discrete Hilbert transform filter, the instantaneous amplitude, phase and frequency are found, and characterization of wind speed is accomplished. Authors have also tried to estimate the hourly wind data using daily sequence by Hilbert transform technique. Results are varying.

In a job shop production system, assigning exact due dates is an important task for scheduling pe... more In a job shop production system, assigning exact due dates is an important task for scheduling performance. On the other hand, predicting due dates accurately is very difficult because of several decision factors should be considered. Many due date assignment models proposed in the literature but none of them is perfect and can produce the best due dates for all jobs arrived to the dynamic job shop environment. So using more than one due date assignment model for all job set may be reasonable. In this study a dynamic solution methodology for determining the most appropriate due date assignment models for the jobs arrived to the shop to optimize the aimed objective function by considering the related decision factors in a dynamic job shop environment is presented.

Scientia Iranica

This paper proposes a new linearized mathematical model to solve integrated cell formation and jo... more This paper proposes a new linearized mathematical model to solve integrated cell formation and job scheduling problem. The model aims to minimize the exceptional elements, voids and the make-span of the jobs. The results of test problems show that the proposed model is very effective to obtain best solutions for small sized problems in reasonable computation times. However, due to the NP-hard nature of the considered problem, the best solutions couldn't be obtained in acceptable times for large sized test problems whereas the real-life applications of the problem addressed here are often much larger in size. To meet the requirement of solving larger sized problems, Genetic Algorithm (GA), which is, today, considered as one of the artificial intelligence and machine learning technique and Marine Predators Algorithm (MPA) as a new and a nature-inspired metaheuristic, are proposed. The success of the algorithms was investigated and compared. The test results reveal the fact that the MPA with optimized parameters has a high potential to solve real life problems. At last, an attempt is made to redesign an existing real-life production system by the proposed algorithms. Eventually, a considerable improvement is obtained on performance compared to the current situation of the system.

International Conference on Information Technology: New Generations, 2008

Shop-floor control system plays important role to handle the problems come from the dynamic natur... more Shop-floor control system plays important role to handle the problems come from the dynamic nature of the shop- floor. In this study, an Agent-Based Shop-Floor Control System is designed. Agents in the system are Marketing Agent, Production Planning Agent, Purchasing Agent and Shop-Floor Agents: Job, Machine and Cell. Designed distributed system contains heterogeneous units and was designed as hybrid control

GAZI UNIVERSITY JOURNAL OF SCIENCE

Highlights • The paper focuses on an integrated cell formation and part scheduling problem. • The... more Highlights • The paper focuses on an integrated cell formation and part scheduling problem. • The objectives of the proposed model are the minimization of EEs in cells and makespan of the jobs. • The validity of the model is tested on numerical examples that are derived from the literature. • The developed mathematical model improves the overall system performance.

International Journal of Mining, Reclamation and Environment

Open Geosciences

Deciding on equipment from a set of feasible alternatives for excavation purpose in open pit mine... more Deciding on equipment from a set of feasible alternatives for excavation purpose in open pit mines is a critical task for the engineers and contractors since it considerably affects the project costs and productivity. Alternatives of rock excavation equipment, which are deemed suitable for the diggability of rock units in open pits, can have many technical specifications or factors that should be considered simultaneously. It can be successfully selected in a scientific way by employing multi-criteria decision making methods by means of taking the advantage of engineering knowledge, intuition and past experiences. In this study, we select the most convenient hydraulic excavator for a magnesite mine by fuzzy multi criteria decision making methods: fuzzy TOPSIS and fuzzy VIKOR. The fuzzy approach allows the experienced engineers to compare the multiple criteria (technical factors) and the possible alternatives of rock excavation machines by simply using linguistic expressions in their...

Expert Systems with Applications, 2016

International Journal of Production Research, 2009

... The experimental results show that the ANN-based due date assignment models are superior to t... more ... The experimental results show that the ANN-based due date assignment models are superior to the regression-based and conventional models. ... Main Effects Plot for MSL Due Date Model Dispatching Rule Shop Util. Rate MAL MSL Figure 1. Main effects plot for MAL and MSL. ...

Iea Aie, 2007

ABSTRACT Although most real manufacturing systems have dynamic job shop structures, there is no g... more ABSTRACT Although most real manufacturing systems have dynamic job shop structures, there is no general analytic method that has been found for analyzing them yet and computer simulation is still an outstanding tool. One of the most difficult problems in a dynamic job shop environments is to assign the optimal due dates. Due date assignment is an important task in shop-floor control, affecting both timely delivery and customer satisfaction. The ability to meet the due dates, however, is dependent not only on reasonableness of the due dates but also on the scheduling or dispatching procedures. In this paper, an agent based dynamic job shop simulation system is designed and developed to help the decision makers who have to mainly solve the problems of selecting correct due date assignment models and dispatching rules depending on selected performance criteria in their multi machine dynamic stochastic job shop environment.

Lecture Notes in Computer Science, 2006

ABSTRACT In this research, the factors have significant effect on due date predictability for on ... more ABSTRACT In this research, the factors have significant effect on due date predictability for on time delivery in a dynamic job shop were studied. For this aim a new due date assignment model was proposed and an experimental study in a simulated dynamic job shop was performed. The results indicate that the proposed due date assignment model is adequate to meet the assigned due dates for on time delivery and the number of jobs in the queues of the machines on a job’s route is the most important factor affects the due date predictability.

Lecture Notes in Computer Science, 2007

ABSTRACT Although most real manufacturing systems have dynamic job shop structures, there is no g... more ABSTRACT Although most real manufacturing systems have dynamic job shop structures, there is no general analytic method that has been found for analyzing them yet and computer simulation is still an outstanding tool. One of the most difficult problems in a dynamic job shop environments is to assign the optimal due dates. Due date assignment is an important task in shop-floor control, affecting both timely delivery and customer satisfaction. The ability to meet the due dates, however, is dependent not only on reasonableness of the due dates but also on the scheduling or dispatching procedures. In this paper, an agent based dynamic job shop simulation system is designed and developed to help the decision makers who have to mainly solve the problems of selecting correct due date assignment models and dispatching rules depending on selected performance criteria in their multi machine dynamic stochastic job shop environment.

Lecture Notes in Computer Science, 2007

Underground mining method selection (UMMS) is one of the most important decisions that should be ... more Underground mining method selection (UMMS) is one of the most important decisions that should be made by mining engineers. Choosing a suitable underground mining method to carry out extraction from a mineral deposit is very important in terms of the economics, ...

Fifth International Conference on Information Technology: New Generations (itng 2008), 2008

ABSTRACT Shop-floor control system plays important role to handle the problems come from the dyna... more ABSTRACT Shop-floor control system plays important role to handle the problems come from the dynamic nature of the shop- floor. In this study, an Agent-Based Shop-Floor Control System is designed. Agents in the system are Marketing Agent, Production Planning Agent, Purchasing Agent and Shop-Floor Agents: Job, Machine and Cell. Designed distributed system contains heterogeneous units and was designed as hybrid control architecture. The study focuses on constructing an Agent-Based Shop-Floor Control System which has ability to manage dynamic scheduling activities. Shop-Floor Agents work in a harmony with each other in order to generate the schedules dynamically.

Tunnelling and Underground Space Technology, 2009

Underground mining method selection is one of the most important decisions that mining engineers ... more Underground mining method selection is one of the most important decisions that mining engineers have to make. Choosing a suitable underground mining method to extract a mineral deposit is very important in terms of economics, safety and productivity of mining ...

Journal of Mining Science, 2008

ABSTRACT The authors propose a number of modified versions of well-known multicriterion optimizat... more ABSTRACT The authors propose a number of modified versions of well-known multicriterion optimization methods and discuss their application to select an optimal underground chromite mining technique.

ABSTRACT This research presents a new application of greedy randomised adaptive search procedure ... more ABSTRACT This research presents a new application of greedy randomised adaptive search procedure (GRASP) to address a production sequencing problem for mixed-model assembly line in a just-in-time (JIT) production system in two different cases. In the former case, small size sequencing problems are considered and two objectives are presented; minimisation of setups and optimisation of stability of material usage rates. These two objectives are inversely correlated with each other, so simultaneous optimisation of both is challenging. This type of problem is NP-hard. The GRASP, with path relinking, searches for efficient frontier where simultaneous optimisation of number of setups and usage rates is desired. Several test problems are solved via GRASP and its performance is compared to solutions obtained via complete enumeration and simulated annealing (SA), tabu search (TS) and genetic algorithms (GA) approaches from the literature. Experimental results reveal that the GRASP with path relinking provides near-optimal solutions in terms of the two objectives and its 'average inferiority%' and 'average percentile' performances are superior to that of other heuristics. In the latter case, the goal is to explore varying the emphasis of these two conflicting objectives. Larger sequencing problems are considered and solved via GRASP with path relinking. Its objective function values are compared to the solutions obtained via a SA approach from the literature. Experimental results show that GRASP also provides good performance on large size problems and its percentage improvement is better than that of SA. Overall results also show, however, that the GRASP performs poorly with regard to CPU time.

International Journal of Production Research, 2009

ABSTRACT This research presents a new application of greedy randomised adaptive search procedure ... more ABSTRACT This research presents a new application of greedy randomised adaptive search procedure (GRASP) to address a production sequencing problem for mixed-model assembly line in a just-in-time (JIT) production system in two different cases. In the former case, small size sequencing problems are considered and two objectives are presented; minimisation of setups and optimisation of stability of material usage rates. These two objectives are inversely correlated with each other, so simultaneous optimisation of both is challenging. This type of problem is NP-hard. The GRASP, with path relinking, searches for efficient frontier where simultaneous optimisation of number of setups and usage rates is desired. Several test problems are solved via GRASP and its performance is compared to solutions obtained via complete enumeration and simulated annealing (SA), tabu search (TS) and genetic algorithms (GA) approaches from the literature. Experimental results reveal that the GRASP with path relinking provides near-optimal solutions in terms of the two objectives and its 'average inferiority%' and 'average percentile' performances are superior to that of other heuristics. In the latter case, the goal is to explore varying the emphasis of these two conflicting objectives. Larger sequencing problems are considered and solved via GRASP with path relinking. Its objective function values are compared to the solutions obtained via a SA approach from the literature. Experimental results show that GRASP also provides good performance on large size problems and its percentage improvement is better than that of SA. Overall results also show, however, that the GRASP performs poorly with regard to CPU time.