Ruzelan Khalid

A Discrete Event Simulation Model for Evaluating the Performances of an M/G/C/C State Dependent Queuing System

M/G/C/C state dependent queuing networks consider service rates as a function of the number of residing entities (e.g., pedestrians, vehicles, and products). However, modeling such dynamic rates is not supported in modern Discrete Simulation System (DES) software. We designed an approach to cater this limitation and used it to construct the M/G/C/C state-dependent queuing model in Arena software. Using the model, we have evaluated and analyzed the impacts of various arrival rates to the throughput, the blocking probability, the expected service time and the expected number of entities in a complex network topology. Results indicated that there is a range of arrival rates for each network where the simulation results fluctuate drastically across replications and this causes the simulation results and analytical results exhibit discrepancies. Detail results that show how tally the simulation results and the analytical results in both abstract and graphical forms and some scientific justifications for these have been documented and discussed.

Optimal production cycle time for inventory model with linear time dependent exponential distributed deterioration

We study an inventory system with linear time varying exponential distributed deterioration in which production and demand rates are constant.The mathematical model is developed to obtain the total cost per unit time of an inventory system.The inventory controlling systems in terms of first order differential equations are solved numerically.The optimal cycle time is derived and the results are applied to numerical problems.The effect of changes in the model parameters on decision variables and the average total cost of an inventory system are studied through numerical examples.

Combining Simulation and Animation of Queueing Scenarios in a Flash-Based Discrete Event Simulator

eLearning is an effective medium for delivering knowledge and skills to scattered learners. In spite of improvements in electronic delivery technologies, eLearning is still a long way away from offering anything close to efficient and effective learning environments. Much of the literature supports eLearning materials which embed simulation will improve eLearning experience and promise many benefits for both teachers and learners. This paper presents an application framework for Discrete Event Simulation (DES), written in Adobe Flash and its ActionScript 2 scripting language. Based on the framework, a set of DES components has been designed and constructed to ease both construction and embedding of multimedia enriched and animated DES models into web-based eLearning environments.

Developing a two-stage approach of super efficiency slack-based measure in the presence of non-discretionary factors and mixed integer-valued data envelopment analysis

Abstract An alternatve approach of super efficiency slack-based measure data envelopment analysis has been proposed to make the projection of an efficient decision making unit strongly-Pareto efficient. The approach however did not examine the simultaneous effect of non-discretionary factors and integer requirements on efficiency measures. To obtain more accurate efficiency measures, this paper proposes a two-stage approach of super efficiency slack-based measure in non-discretionary factors and mixed integer requirements. Both new factors and requirements were first integrated into the existing approach. The optimal solution of the proposed approach was then obtained by transforming its fractional form to a linear form. Thus, the scalar measures of the proposed approach can now deal directly with discretionary mixed integer input saving-output surplus and discretionary mixed integer input excess-output shortfall. The practicability of the proposed approach was tested using empirical data of Malaysian community colleges.

Extended optimal stochastic production control model with application to economics

This study considers an inventory control system meeting uncertain demand in continuous time.The demand is a function of both time and price, with the price evolves as a Wiener process with no drift. The goal is to use the stochastic optimal control principle to completely solve a production planning model for the demand rate.A stochastic optimal control problem is formulated in which the stochastic differential equations of a type known as Ito’s equations are considered which are perturbed by a Markov diffusion process and analyzed by the optimal control of a single dimension stochastic production planning model. The existence of a complete solution to the associated HJB equation is established and the optimal policy is characterized. Numerical examples and solutions of this optimal control model are then presented.

A hybrid integer data envelopment analysis based on an alternative approach of super slack based measure for measuring super efficiency and inefficiency of decision making units

Conventional data envelopment analysis (DEA) models assume that all values of input and output variables are non-integers. However, in many situations of real life DEA application, some of the input and/or output variables are to be integers.The rounding process of the non-integer values to their nearest integers can cause inaccurate efficiency and performance measurement. Thus, it is important to develop a non-radial hybrid integer DEA model. Moreover, the projection of decision making units (DMUs) in the existing super efficiency slack based measure hybrid integer model may not be strongly Pareto-efficient.Thus, our hybrid integer DEA model is developed based on an alternative super efficiency slack based measure DEA model for ranking efficient and inefficient DMUs.The developed model can project efficient DMUs resulted from super efficiency strongly Pareto-efficient by identifying input excesses and output shortfalls of non-integer and integer slack variables. It then discriminates inefficient DMUs whose efficiency scores resulted from super efficiency slack based measure model equal to one.An application to measure the efficiency of 41 academic departments at National Cheng Kung University in Taiwan (NCKU) is used to test the applicability of developed models. The results showed that 51.20% of the departments (DMUs) were super efficiency. Moreover, the result also showed that most of the inefficient departments were caused by their input excesses of expenses and teaching space, and output shortfalls associating with publications and grants.

Investigating data envelopment analysis model with potential improvement for integer output values

The decrement of input proportions in DEA model is associated with its input reduction. This reduction is apparently good for economy since it could reduce unnecessary cost resources. However, in some situations the reduction of relevant inputs such as labour could create social problems. Such inputs should thus be maintained or increased. This paper develops an advanced radial DEA model dealing with mixed integer linear programming to improve integer output values through the combination of inputs. The model can deal with real input values and integer output values. This model is valuable for situations dealing with input combination to improve integer output values as faced by most organizations.

Optimal control of a continuous review production inventory system with Gamma distributed deterioration

This paper develops the production inventory models with and without Gamma distributed deteriorating items. The production system with inventory level dependent demand is considered here and the Pontryagin maximum principle is used to determine the optimal control, which is the production rate that minimizes the optimal inventory control model, while satisfying the system dynamics. The necessary optimality conditions associated with and without Gamma distributed deteriorating items are derived from the Hamiltonian functions. The optimal inventory levels and the optimal production rates are derived and numerical simulations are used to illustrate the theoretical results.

Queuing network approach for building evacuation planning

The complex behavior of pedestrians in a limited space layout can explicitly be modeled using an M/G/C/C state dependent queuing network. This paper implements the approach to study pedestrian flows through various corridors in a topological network. The best arrival rates and their impacts to the corridors’ performances in terms of the throughput, blocking probability, expected number of occupants in the system and expected travel time were first measured using the M/G/C/C analytical model. These best arrival rates were then fed to its Network Flow Programming model to find the best arrival rates to source corridors and routes optimizing the network’s total throughput. The analytical results were then validated using a simulation model. Various results of this study can be used to support the current Standard Operating Procedures (SOP) to efficiently and safely evacuate people in emergency cases.

Simulated annealing with probabilistic analysis for solving traveling salesman problems

Simulated Annealing (SA) is a widely used meta-heuristic that was inspired from the annealing process of recrystallization of metals. Therefore, the efficiency of SA is highly affected by the annealing schedule. As a result, in this paper, we presented an empirical work to provide a comparable annealing schedule to solve symmetric traveling salesman problems (TSP). Randomized complete block design is also used in this study. The results show that different parameters do affect the efficiency of SA and thus, we propose the best found annealing schedule based on the Post Hoc test. SA was tested on seven selected benchmarked problems of symmetric TSP with the proposed annealing schedule. The performance of SA was evaluated empirically alongside with benchmark solutions and simple analysis to validate the quality of solutions. Computational results show that the proposed annealing schedule provides a good quality of solution.