Shokri Selim | King Fahd University of Petroleum and Minerals (original) (raw)

Papers by Shokri Selim

We consider the queueing system denoted by MIMN/1/N where customers are served in batches of maxi... more We consider the queueing system denoted by MIMN/1/N where customers are served in batches of maximum size N. The model is motivated by a traffic application. The timedependent probability distribution for the number of customers in the system is obtained in closed form. The solution is used to predict the optimal service rates during a finite time horizon.

Due to increase in environmental concerns along with stringent government legislations, forcing i... more Due to increase in environmental concerns along with stringent government legislations, forcing industry practitioners and policy makers to tak e a fresh look at the impact of their supply chain activities on the environment. Various carbon regulatory mechanisms have been proposed by governmental agencies around the globe, which aims to curb the carbon emission. In this paper, optimization models based on carbon regulatory policies for a closed-loop supply chain design and logistics operations are p resented. Specifically, the following three common regulatory policies are considered: strict carbon caps, carbon tax, and carbon cap-and-trade. The proposed models optimize not only costs but also em issions in the supply chain operations. The models capture: the trade-o�° s that exist between location and transportation modes d ecisions; and the trade-o�° s between costs and emissions in the supply chain operations. Numerical experiment illustrates different policies and th eir impact ...

International Journal of Industrial Engineering-theory Applications and Practice, 2018

Climate change attributed by greenhouse gas emissions have triggered some countries to implement ... more Climate change attributed by greenhouse gas emissions have triggered some countries to implement various carbon regulatory mechanisms to curb and regulate industrial carbon emissions. To be effective, the industry environmental footprint needs to address holistically via closed-loop supply chains (CLSC). This research proposes an optimization approach to address CLSC design problem with carbon footprint considerations. It integrates the carbon emission policies into supply chain’s strategic, tactical and operational selection decisions. A robust counterpart of the proposed model is developed based on three alternative uncertainty sets. The model extends further to investigate the impact of the three commonly practiced carbon regulatory policies including carbon cap, carbon tax, and carbon cap-and-trade on the supply chain strategic and operational decisions. Numerical results indicate that carbon cap-and-trade policy is the most flexible and efficient policy as compared to carbon ca...

Computers & Operations Research, 2022

Abstract This paper introduces discrete production systems where units are produced one at a time... more Abstract This paper introduces discrete production systems where units are produced one at a time. These systems exist in industry but to the best of our knowledge, they have not been addressed in the open literature. Manufacturing of large iron castings and special precast panels are examples of such production systems. We consider the case where the production process is imperfect resulting in non-conforming units that would be reworked. We assume that the rework process is imperfect and repeated as many times as needed until a conforming unit is produced or the production run ends. The outcomes of this process can be presented by a tree where each branch represents a sequence of production and rework attempts. We call each branch a scenario. The possible number of branches/scenarios is enormously huge, even for reasonable production periods. We employ novel ideas to characterize all branches/scenarios in order to develop the probability mass function for the number of conforming units produced in a given length of the production period. We also, find the expected number of production attempts and rework attempts and the net cost of producing a conforming unit.

International Journal of Engineering Business Management, 2019

The literature has several models that jointly determine the economic production quantity (EPQ) a... more The literature has several models that jointly determine the economic production quantity (EPQ) and the rate of production. Very few models define production rate explicitly. In this article, the cutting speed controls the production rate and the proportion nonconforming. Thus, we propose a model that integrates EPQ, machining economics and quality. Even though the objective function of the model is non-convex, we show for realistic values of some technical parameters that a local minimum of the proposed mathematical model is also global. Examples clearly show the effect of the production economics factors on the optimal machining speed and production quantity.

IEEE Access, 2019

To maximize profitability and meet customers' expectations, assembly plants strive to enhance ope... more To maximize profitability and meet customers' expectations, assembly plants strive to enhance operations and minimize costs. Using discrete-event system simulation and optimization, this paper investigates different scenarios to enhance operations efficiency and presents a decision support tool to aid operational decision making in an air conditioner assembly plant. Specifically, simulation is used to evaluate the system-wide impact of an optimal sequencing rule at a bottleneck station; in addition, a multi-objective simulation optimization problem is solved to enable manufacturers to evaluate their time/cost tradeoffs. Using actual data from a previous month, the simulation study illustrates possible savings throughout the evaluated alternatives. To sustain the study outcomes, we combine mathematical programming and simulation into an integrated decision support tool. Overall, this study illustrates the benefits of solution approach to a real-life system.

Transportation Research Part D: Transport and Environment, 2017

Pattern Recognition, 1991

In this paper, the problem of achieving 'semi-fuzzy' or 'soft' clustering of multidimensional dat... more In this paper, the problem of achieving 'semi-fuzzy' or 'soft' clustering of multidimensional data is discussed.A technique based on thresholding the results of the fuzzy c-means algorithm is introduced.The proposed approach is analysed and contrasted with the soft clustering method (see S. Z. Selim and M. A. Ismail, Pattern Recognition 17, 559-568) showing the merits of the new method.Separation of clusters in the semi-fuzzy clustering context is introduced and the use of the proposed technique to measure the degree of separation is explained.

Procedia CIRP, 2015

Due to increase in environmental concerns along with stringent government legislations, forcing i... more Due to increase in environmental concerns along with stringent government legislations, forcing industry practitioners and policy makers to take a fresh look at the impact of their supply chain activities on the environment. Various carbon regulatory mechanisms have been proposed by governmental agencies around the globe, which aims to curb the carbon emission. In this paper, optimization models based on carbon regulatory policies for a closed-loop supply chain design and logistics operations are presented. Specifically, the following three common regulatory policies are considered: strict carbon caps, carbon tax, and carbon cap-and-trade. The proposed models optimize not only costs but also emissions in the supply chain operations. The models capture: the trade-o s that exist between location and transportation modes decisions; and the trade-o s between costs and emissions in the supply chain operations. Numerical experiment illustrates different policies and their impact on the costs and the effectiveness of emission reduction. The results from the models can help policy makers to predict the impact of regulatory policies on overall emissions in the supply chain operations.

Pattern Recognition, 1991

In this paper we discuss the solution of the clustering problem usually solved by the K-means alg... more In this paper we discuss the solution of the clustering problem usually solved by the K-means algorithm. The problem is known to have local minimum solutions which are usually what the K-means algorithm obtains. The simulated annealing approach for solving optimization problems is described and is proposed for solving the clustering problem. The parameters of the algorithm are discussed in detail and it is shown that the algorithm converges to a global solution of the clustering problem. We also find optimal parameters values for a specific class of data sets and give recommendations on the choice of parameters for general data sets. Finally, advantages and disadvantages of the approach are presented.

2007 IEEE/ACS International Conference on Computer Systems and Applications, 2007

In today's online connected world, almost all corporate networks use some form of perimeter firew... more In today's online connected world, almost all corporate networks use some form of perimeter firewalls to manage Internet connections and enforce a security policy at the corporate gateway. Although it can considerably enhance network security and protect business-critical information, a firewall with thousands of rules can become a bottleneck for network performance. The primary goal of this paper is to present a new rule order optimizer based on simulated annealing to find optimal configurations that minimize the average number of rule comparisons while preserving precedence relationships among disjoint rules. The proposed approach is evaluated and its effectiveness is compared with another approximate solution under several firewall configurations and policy profiles.

Ann Arbor, 1994

... and Shokri Z. SELIM Department of Systems Engineering King Fahd University of Petroleum and M... more ... and Shokri Z. SELIM Department of Systems Engineering King Fahd University of Petroleum and Minerals Dhahran 31261, Saudi Arabia. ... [4] J. L Bentley and D. Wood, "An optimal worst-case algorithm for reporting intersections of rectangles", IEEE Trans. Comupt., Vol. ...

Pattern Recognition, 1984

This paper discusses new approaches to unsupervised fuzzy classification of multidimensional data... more This paper discusses new approaches to unsupervised fuzzy classification of multidimensional data. In the developed clustering models, patterns are considered to belong to some but not necessarily all clusters. Accordingly, such algorithms are called 'semi-fuzzy' or 'soft" clustering techniques. Several models to achieve this goal are investigated and corresponding implementation algorithms are developed. Experimental results are reported. Soft clustering algorithms Semi-fuzzy classification Fuzzy ISODATA algorithm Fuzzy unsupervised learning Fuzzy clustering models Fuzzy pattern recognition

Pattern Recognition, 1994

Summary Two new algorithms for fuzzy clustering are present ed. Convergence of the proposed algor... more Summary Two new algorithms for fuzzy clustering are present ed. Convergence of the proposed algorithms is proved. An empirical study of their c onvergence behavior is discussed. The performance of the new algorithms is compared with the fuzzy c-means algorithm by testing them on four published data se ts. Experimental results show that the new algorithms are faster and lead

IEEE Transactions on Power Systems, 1998

This paper presents a simulated annealing algorithm (SAA) to solve the unit commitment problem (U... more This paper presents a simulated annealing algorithm (SAA) to solve the unit commitment problem (UCP). New rules for randomly generating feasible solutions are introduced. The problem has two subproblems: a combinatorial optimization problem; and a nonlinear programming problem. The former is solved using the SAA while the latter problem is solved via a quadratic programming routine. Numerical results showed an improvement in the solutions costs compared to previously obtained results

IEEE Transactions on Power Systems, 1999

IEEE Transactions on Pattern Analysis and Machine Intelligence, 1986

IEEE Transactions on Pattern Analysis and Machine Intelligence, 1984

Fuzzy Sets and Systems, 1994

Fuzzy Sets and Systems 61 (1994) 177-188 177 North-Holland A relaxation approach to the fuzzy clu... more Fuzzy Sets and Systems 61 (1994) 177-188 177 North-Holland A relaxation approach to the fuzzy clustering problem Mohamed S. Kamel Department of Systems Design, University of Waterloo, Waterloo, Ont., Canada Shokri Z. Selim Department of Systems Engineering, ...

European Journal of Operational Research, 1993

The problem of sequencing jobs on a weaving machine is considered where setup costs are included.... more The problem of sequencing jobs on a weaving machine is considered where setup costs are included. The structure of the setup cost is utilized to develop a polynomial time solution algorithm. The algorithm involves computing the shortest path of a network. An example is solved.

We consider the queueing system denoted by MIMN/1/N where customers are served in batches of maxi... more We consider the queueing system denoted by MIMN/1/N where customers are served in batches of maximum size N. The model is motivated by a traffic application. The timedependent probability distribution for the number of customers in the system is obtained in closed form. The solution is used to predict the optimal service rates during a finite time horizon.

Due to increase in environmental concerns along with stringent government legislations, forcing i... more Due to increase in environmental concerns along with stringent government legislations, forcing industry practitioners and policy makers to tak e a fresh look at the impact of their supply chain activities on the environment. Various carbon regulatory mechanisms have been proposed by governmental agencies around the globe, which aims to curb the carbon emission. In this paper, optimization models based on carbon regulatory policies for a closed-loop supply chain design and logistics operations are p resented. Specifically, the following three common regulatory policies are considered: strict carbon caps, carbon tax, and carbon cap-and-trade. The proposed models optimize not only costs but also em issions in the supply chain operations. The models capture: the trade-o�° s that exist between location and transportation modes d ecisions; and the trade-o�° s between costs and emissions in the supply chain operations. Numerical experiment illustrates different policies and th eir impact ...

International Journal of Industrial Engineering-theory Applications and Practice, 2018

Climate change attributed by greenhouse gas emissions have triggered some countries to implement ... more Climate change attributed by greenhouse gas emissions have triggered some countries to implement various carbon regulatory mechanisms to curb and regulate industrial carbon emissions. To be effective, the industry environmental footprint needs to address holistically via closed-loop supply chains (CLSC). This research proposes an optimization approach to address CLSC design problem with carbon footprint considerations. It integrates the carbon emission policies into supply chain’s strategic, tactical and operational selection decisions. A robust counterpart of the proposed model is developed based on three alternative uncertainty sets. The model extends further to investigate the impact of the three commonly practiced carbon regulatory policies including carbon cap, carbon tax, and carbon cap-and-trade on the supply chain strategic and operational decisions. Numerical results indicate that carbon cap-and-trade policy is the most flexible and efficient policy as compared to carbon ca...

Computers & Operations Research, 2022

Abstract This paper introduces discrete production systems where units are produced one at a time... more Abstract This paper introduces discrete production systems where units are produced one at a time. These systems exist in industry but to the best of our knowledge, they have not been addressed in the open literature. Manufacturing of large iron castings and special precast panels are examples of such production systems. We consider the case where the production process is imperfect resulting in non-conforming units that would be reworked. We assume that the rework process is imperfect and repeated as many times as needed until a conforming unit is produced or the production run ends. The outcomes of this process can be presented by a tree where each branch represents a sequence of production and rework attempts. We call each branch a scenario. The possible number of branches/scenarios is enormously huge, even for reasonable production periods. We employ novel ideas to characterize all branches/scenarios in order to develop the probability mass function for the number of conforming units produced in a given length of the production period. We also, find the expected number of production attempts and rework attempts and the net cost of producing a conforming unit.

International Journal of Engineering Business Management, 2019

The literature has several models that jointly determine the economic production quantity (EPQ) a... more The literature has several models that jointly determine the economic production quantity (EPQ) and the rate of production. Very few models define production rate explicitly. In this article, the cutting speed controls the production rate and the proportion nonconforming. Thus, we propose a model that integrates EPQ, machining economics and quality. Even though the objective function of the model is non-convex, we show for realistic values of some technical parameters that a local minimum of the proposed mathematical model is also global. Examples clearly show the effect of the production economics factors on the optimal machining speed and production quantity.

IEEE Access, 2019

To maximize profitability and meet customers' expectations, assembly plants strive to enhance ope... more To maximize profitability and meet customers' expectations, assembly plants strive to enhance operations and minimize costs. Using discrete-event system simulation and optimization, this paper investigates different scenarios to enhance operations efficiency and presents a decision support tool to aid operational decision making in an air conditioner assembly plant. Specifically, simulation is used to evaluate the system-wide impact of an optimal sequencing rule at a bottleneck station; in addition, a multi-objective simulation optimization problem is solved to enable manufacturers to evaluate their time/cost tradeoffs. Using actual data from a previous month, the simulation study illustrates possible savings throughout the evaluated alternatives. To sustain the study outcomes, we combine mathematical programming and simulation into an integrated decision support tool. Overall, this study illustrates the benefits of solution approach to a real-life system.

Transportation Research Part D: Transport and Environment, 2017

Pattern Recognition, 1991

In this paper, the problem of achieving 'semi-fuzzy' or 'soft' clustering of multidimensional dat... more In this paper, the problem of achieving 'semi-fuzzy' or 'soft' clustering of multidimensional data is discussed.A technique based on thresholding the results of the fuzzy c-means algorithm is introduced.The proposed approach is analysed and contrasted with the soft clustering method (see S. Z. Selim and M. A. Ismail, Pattern Recognition 17, 559-568) showing the merits of the new method.Separation of clusters in the semi-fuzzy clustering context is introduced and the use of the proposed technique to measure the degree of separation is explained.

Procedia CIRP, 2015

Due to increase in environmental concerns along with stringent government legislations, forcing i... more Due to increase in environmental concerns along with stringent government legislations, forcing industry practitioners and policy makers to take a fresh look at the impact of their supply chain activities on the environment. Various carbon regulatory mechanisms have been proposed by governmental agencies around the globe, which aims to curb the carbon emission. In this paper, optimization models based on carbon regulatory policies for a closed-loop supply chain design and logistics operations are presented. Specifically, the following three common regulatory policies are considered: strict carbon caps, carbon tax, and carbon cap-and-trade. The proposed models optimize not only costs but also emissions in the supply chain operations. The models capture: the trade-o s that exist between location and transportation modes decisions; and the trade-o s between costs and emissions in the supply chain operations. Numerical experiment illustrates different policies and their impact on the costs and the effectiveness of emission reduction. The results from the models can help policy makers to predict the impact of regulatory policies on overall emissions in the supply chain operations.

Pattern Recognition, 1991

In this paper we discuss the solution of the clustering problem usually solved by the K-means alg... more In this paper we discuss the solution of the clustering problem usually solved by the K-means algorithm. The problem is known to have local minimum solutions which are usually what the K-means algorithm obtains. The simulated annealing approach for solving optimization problems is described and is proposed for solving the clustering problem. The parameters of the algorithm are discussed in detail and it is shown that the algorithm converges to a global solution of the clustering problem. We also find optimal parameters values for a specific class of data sets and give recommendations on the choice of parameters for general data sets. Finally, advantages and disadvantages of the approach are presented.

2007 IEEE/ACS International Conference on Computer Systems and Applications, 2007

In today's online connected world, almost all corporate networks use some form of perimeter firew... more In today's online connected world, almost all corporate networks use some form of perimeter firewalls to manage Internet connections and enforce a security policy at the corporate gateway. Although it can considerably enhance network security and protect business-critical information, a firewall with thousands of rules can become a bottleneck for network performance. The primary goal of this paper is to present a new rule order optimizer based on simulated annealing to find optimal configurations that minimize the average number of rule comparisons while preserving precedence relationships among disjoint rules. The proposed approach is evaluated and its effectiveness is compared with another approximate solution under several firewall configurations and policy profiles.

Ann Arbor, 1994

... and Shokri Z. SELIM Department of Systems Engineering King Fahd University of Petroleum and M... more ... and Shokri Z. SELIM Department of Systems Engineering King Fahd University of Petroleum and Minerals Dhahran 31261, Saudi Arabia. ... [4] J. L Bentley and D. Wood, "An optimal worst-case algorithm for reporting intersections of rectangles", IEEE Trans. Comupt., Vol. ...

Pattern Recognition, 1984

This paper discusses new approaches to unsupervised fuzzy classification of multidimensional data... more This paper discusses new approaches to unsupervised fuzzy classification of multidimensional data. In the developed clustering models, patterns are considered to belong to some but not necessarily all clusters. Accordingly, such algorithms are called 'semi-fuzzy' or 'soft" clustering techniques. Several models to achieve this goal are investigated and corresponding implementation algorithms are developed. Experimental results are reported. Soft clustering algorithms Semi-fuzzy classification Fuzzy ISODATA algorithm Fuzzy unsupervised learning Fuzzy clustering models Fuzzy pattern recognition

Pattern Recognition, 1994

Summary Two new algorithms for fuzzy clustering are present ed. Convergence of the proposed algor... more Summary Two new algorithms for fuzzy clustering are present ed. Convergence of the proposed algorithms is proved. An empirical study of their c onvergence behavior is discussed. The performance of the new algorithms is compared with the fuzzy c-means algorithm by testing them on four published data se ts. Experimental results show that the new algorithms are faster and lead

IEEE Transactions on Power Systems, 1998

This paper presents a simulated annealing algorithm (SAA) to solve the unit commitment problem (U... more This paper presents a simulated annealing algorithm (SAA) to solve the unit commitment problem (UCP). New rules for randomly generating feasible solutions are introduced. The problem has two subproblems: a combinatorial optimization problem; and a nonlinear programming problem. The former is solved using the SAA while the latter problem is solved via a quadratic programming routine. Numerical results showed an improvement in the solutions costs compared to previously obtained results

IEEE Transactions on Power Systems, 1999

IEEE Transactions on Pattern Analysis and Machine Intelligence, 1986

IEEE Transactions on Pattern Analysis and Machine Intelligence, 1984

Fuzzy Sets and Systems, 1994

Fuzzy Sets and Systems 61 (1994) 177-188 177 North-Holland A relaxation approach to the fuzzy clu... more Fuzzy Sets and Systems 61 (1994) 177-188 177 North-Holland A relaxation approach to the fuzzy clustering problem Mohamed S. Kamel Department of Systems Design, University of Waterloo, Waterloo, Ont., Canada Shokri Z. Selim Department of Systems Engineering, ...

European Journal of Operational Research, 1993

The problem of sequencing jobs on a weaving machine is considered where setup costs are included.... more The problem of sequencing jobs on a weaving machine is considered where setup costs are included. The structure of the setup cost is utilized to develop a polynomial time solution algorithm. The algorithm involves computing the shortest path of a network. An example is solved.