The purpose of this study is to propose a prototype expert decision support system for the suppli... more The purpose of this study is to propose a prototype expert decision support system for the supplier evaluation and selection processes. In regard to the proposed system called ESESS (Expert Supplier Evaluation and Selection System), the application of expert system approach in supplier evaluation and selection was studied. The proposed prototype system aims to assist the decision maker during the
ABSTRACT In this study, we model bandwidth provider selection and task allocation problem as an e... more ABSTRACT In this study, we model bandwidth provider selection and task allocation problem as an expected cost minimization problem with stochastic constraints. Two important parameters of quality of service (QoS), namely delay and jitter are considered as random variables to capture stochastic nature of telecom network environment. As solution methodology, stochastic model is converted into its deterministic equivalent and then a novel heuristic algorithm is proposed to solve resulting non-linear mixed integer programming model. We analyze how different prices, quality and task distribution affect the optimal behavior of the firm. Finally, performance of solution procedure is tested by several randomly generated scenarios and by a relaxation of this problem as tight lower bound.
In this study, we model bandwidth provider selection and task allocation problem as an expected c... more In this study, we model bandwidth provider selection and task allocation problem as an expected cost minimization problem with stochastic constraints. Two important parameters of quality of service (QoS), namely delay and jitter are considered as random variables to capture stochastic nature of telecom network environment. As solution methodology, stochastic model is converted into its deterministic equivalent and then a novel heuristic algorithm is proposed to solve resulting non-linear mixed integer programming model. We analyze how different prices, quality and task distribution affect the optimal behavior of the firm. Finally, performance of solution procedure is tested by several randomly generated scenarios and by a relaxation of this problem as tight lower bound.
In this study, we model bandwidth provider selection and task allocation problem as an expected c... more In this study, we model bandwidth provider selection and task allocation problem as an expected cost minimization problem with stochastic constraints. Two important parameters of quality of service (QoS), namely delay and jitter are considered as random variables to capture stochastic nature of telecom network environment. As solution methodology, stochastic model is converted into its deterministic equivalent and then a novel heuristic algorithm is proposed to solve resulting nonlinear mixed integer programming model. We analyze how different prices, quality and task distribution affect the optimal behavior of the firm. Finally, performance of solution procedure is tested by several randomly generated scenarios and by a relaxation of this problem as tight lower bound.
Firms acquire network capacity from multiple suppliers which offer different Quality of Service (... more Firms acquire network capacity from multiple suppliers which offer different Quality of Service (QoS) levels. After acquisition, day-to-day operations such as video conferencing, voice over IP and data applications are allocated between these acquired capacities by considering QoS requirement of each operation. In optimal allocation scheme, it is generally assumed each operation has to be placed into resource that provides equal or higher QoS Level. Conversely, in this study it is showed that former allocation strategy may lead to suboptimal solutions depending upon penalty cost policy to charge degradation in QoS requirements. We model a cost minimization problem which includes three cost components namely capacity acquisition, opportunity and penalty due to loss in QoS.
Abstract My Project Istanbul is the name of the Research Fund given by Istanbul Metropolitan Muni... more Abstract My Project Istanbul is the name of the Research Fund given by Istanbul Metropolitan Municipality for research projects directed to Municipality related subjects, and carried out by about 22 Universities located in Istanbul. Due to restricted funds, ...
Equipments and systems on board ship, although well designed, will not remain safe or reliable if... more Equipments and systems on board ship, although well designed, will not remain safe or reliable if they are not maintained. The general objective of the maintenance process is to make use of the knowledge of failures and accidents to achieve the maximum possible safety with the lowest possible cost. In this insight, this study proposes a risk-assessment methodology for preventive maintenance planning evaluation based upon a reliability model for marine engine systems, which allows the use of flexible intervals between maintenance interventions. Failure Mode and Effect Analysis (FMEA) approach is chosen as a risk assessment methodology in this paper to synthesize the potential failure modes in order to identify early response and smoothly promote a preventive maintenance planning. As a case application fuel oil system is comparatively assessed. In the paper, it is seen that the proposed risk-assessment methodology provides invaluable supports to construct risk-based preventive maintenance planning for fuel oil system onboard ship.
The purpose of this study is to propose a prototype expert decision support system for the suppli... more The purpose of this study is to propose a prototype expert decision support system for the supplier evaluation and selection processes. In regard to the proposed system called ESESS (Expert Supplier Evaluation and Selection System), the application of expert system approach in supplier evaluation and selection was studied. The proposed prototype system aims to assist the decision maker during the
ABSTRACT In this study, we model bandwidth provider selection and task allocation problem as an e... more ABSTRACT In this study, we model bandwidth provider selection and task allocation problem as an expected cost minimization problem with stochastic constraints. Two important parameters of quality of service (QoS), namely delay and jitter are considered as random variables to capture stochastic nature of telecom network environment. As solution methodology, stochastic model is converted into its deterministic equivalent and then a novel heuristic algorithm is proposed to solve resulting non-linear mixed integer programming model. We analyze how different prices, quality and task distribution affect the optimal behavior of the firm. Finally, performance of solution procedure is tested by several randomly generated scenarios and by a relaxation of this problem as tight lower bound.
In this study, we model bandwidth provider selection and task allocation problem as an expected c... more In this study, we model bandwidth provider selection and task allocation problem as an expected cost minimization problem with stochastic constraints. Two important parameters of quality of service (QoS), namely delay and jitter are considered as random variables to capture stochastic nature of telecom network environment. As solution methodology, stochastic model is converted into its deterministic equivalent and then a novel heuristic algorithm is proposed to solve resulting non-linear mixed integer programming model. We analyze how different prices, quality and task distribution affect the optimal behavior of the firm. Finally, performance of solution procedure is tested by several randomly generated scenarios and by a relaxation of this problem as tight lower bound.
In this study, we model bandwidth provider selection and task allocation problem as an expected c... more In this study, we model bandwidth provider selection and task allocation problem as an expected cost minimization problem with stochastic constraints. Two important parameters of quality of service (QoS), namely delay and jitter are considered as random variables to capture stochastic nature of telecom network environment. As solution methodology, stochastic model is converted into its deterministic equivalent and then a novel heuristic algorithm is proposed to solve resulting nonlinear mixed integer programming model. We analyze how different prices, quality and task distribution affect the optimal behavior of the firm. Finally, performance of solution procedure is tested by several randomly generated scenarios and by a relaxation of this problem as tight lower bound.
Firms acquire network capacity from multiple suppliers which offer different Quality of Service (... more Firms acquire network capacity from multiple suppliers which offer different Quality of Service (QoS) levels. After acquisition, day-to-day operations such as video conferencing, voice over IP and data applications are allocated between these acquired capacities by considering QoS requirement of each operation. In optimal allocation scheme, it is generally assumed each operation has to be placed into resource that provides equal or higher QoS Level. Conversely, in this study it is showed that former allocation strategy may lead to suboptimal solutions depending upon penalty cost policy to charge degradation in QoS requirements. We model a cost minimization problem which includes three cost components namely capacity acquisition, opportunity and penalty due to loss in QoS.
Abstract My Project Istanbul is the name of the Research Fund given by Istanbul Metropolitan Muni... more Abstract My Project Istanbul is the name of the Research Fund given by Istanbul Metropolitan Municipality for research projects directed to Municipality related subjects, and carried out by about 22 Universities located in Istanbul. Due to restricted funds, ...
Equipments and systems on board ship, although well designed, will not remain safe or reliable if... more Equipments and systems on board ship, although well designed, will not remain safe or reliable if they are not maintained. The general objective of the maintenance process is to make use of the knowledge of failures and accidents to achieve the maximum possible safety with the lowest possible cost. In this insight, this study proposes a risk-assessment methodology for preventive maintenance planning evaluation based upon a reliability model for marine engine systems, which allows the use of flexible intervals between maintenance interventions. Failure Mode and Effect Analysis (FMEA) approach is chosen as a risk assessment methodology in this paper to synthesize the potential failure modes in order to identify early response and smoothly promote a preventive maintenance planning. As a case application fuel oil system is comparatively assessed. In the paper, it is seen that the proposed risk-assessment methodology provides invaluable supports to construct risk-based preventive maintenance planning for fuel oil system onboard ship.
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Papers by Hasan H. Turan