The methodology of discrete-event simulation provides a promising alternative to solving complicated construction systems. Given the level of uncertainty that exists in the early estimation phase of mega-projects regarding cost and risk, project simulations have become a central part of decision-making and planning. In this paper, an attempt is made to compare the output generated by a model constructed under the Monte Carlo framework with that of Discrete-Event Simulation to determine the similarities and difference between the two methods. To achieve this, the Simphony modeling (DES) environment is used. The result is then compared to a Monte Carlo simulation conducted by Golder Associates.

The methodology of discrete-event simulation provides a promising alternative to solving complicated construction systems. Given the level of uncertainty that exists in the early estimation phase of mega-projects regarding cost and risk, project simulations have become a central part of decision-making and planning. In this paper, an attempt is made to compare the output generated by a model constructed under the Monte Carlo framework with that of Discrete-Event Simulation to determine the similarities and difference between the two methods. To achieve this, the Simphony modeling (DES) environment is used. The result is then compared to a Monte Carlo simulation conducted by Golder Associates.

Bergkvist insjön AB is a sawmill yard which is capable of producing 350,000 cubic meter of timber every year this requires lot of internal resources. Sawmill operations can be classified as unloading, sorting, storage and production of timber. In the company we have trucks arriving at random they have to be unloaded and sent back at the earliest to avoid queuing up of trucks creating a problem for truck owners. The sawmill yard has to operate with two log stackers that does several tasks including transporting the logs from trucks to measurement station where the logs will be sorted into classes and dropped into pockets from pockets to the sorted timber yard where they are stored and finally from there to sawmill for final processing. The main issue that needs to be answered here is the lining up trucks that are waiting to be unload, creating a problem for both sawmill as well as the truck owners and given huge production volume, it is certain that handling of resources is top priority. A key challenge in handling of resources would be unloading of trucks and finding a way to optimize internal resources.To address this problem i have experimented on different ways of using internal resources, i have designed different cases, in case 1 we have both the log stackers working on sawmill and measurement station. The main objective of having this case is to make sawmill and measurement station to work all the time. Then in case 2, i have divided the work between both the log stackers, one log stacker will be working on sawmill and pocket_control and second log stacker will be working on measurement station and truck. Then in case 3 we have only one log stacker working on all the agents, this case was designed to reduce cost of production, as the experiment cannot be done in real-time due to operational cost, for this purpose simulation is used, preliminary investigation into simulation results suggested that case 2 is the best option has it reduced waiting time of trucks considerably when compared with other cases and it showed 50% increase in optimizing internal resources.

Appointment scheduling involves picking a strategy for sequencing patient appointments such that the wait time per patient is minimized and the idle time and overtime for the doctor are minimized. The goal of this project is to increase the number of scans per day at the echocardiogram clinic in the Hospital for Sick Children. The objectives were realized by performing simulations of the workflow of the echo clinic using simulation software. The simulation model did not precisely reflect the echo clinic, and the disparity was attributed to limitations in the simulation model. Nevertheless, the user accepted the model and six different policy change scenarios were explored. All six scenarios yielded significant increases in average scans per day per sonographer. Scenario IV, which eliminated the use of sonographer schedules, was recommended to be implemented due to ease of implementation and lack of negative effect on patient wait time and sonographer overtime.

The application of Discrete-Event Systems (DES) theory to the problem of guar- anteeably enforcing concurrency constraints in multi-threaded applications has been studied under certain assumptions, namely, the assumption of a static pool of pre- existing instantiated threads, whose creation and termination are not modelled. This work proposes an extension of this case to handle dynamically instantiated and termi- nated threads using a Petri net formalism and an online limited-lookahead state-space search technique. / Thesis (Master, Computing) -- Queen's University, 2010-05-27 17:00:15.99

Appointment scheduling involves picking a strategy for sequencing patient appointments such that the wait time per patient is minimized and the idle time and overtime for the doctor are minimized. The goal of this project is to increase the number of scans per day at the echocardiogram clinic in the Hospital for Sick Children. The objectives were realized by performing simulations of the workflow of the echo clinic using simulation software. The simulation model did not precisely reflect the echo clinic, and the disparity was attributed to limitations in the simulation model. Nevertheless, the user accepted the model and six different policy change scenarios were explored. All six scenarios yielded significant increases in average scans per day per sonographer. Scenario IV, which eliminated the use of sonographer schedules, was recommended to be implemented due to ease of implementation and lack of negative effect on patient wait time and sonographer overtime.

High profit (low volume) products are very attractive economically, and are influencing the direction of manufacture towards product based batch processes. One new system which has a great deal of potential is a "pipeless" plant, in which the reactor moves to different areas of the plant where heating, agitation etc. takes place. There are obvious advantages in its use in providing a means of quickly responding to fast market changes while maintaining high product quality with reduced waste. The basic concept has been successfully demonstrated with several production plants already in operation, mainly in Japan. Nevertheless the safety issues associated with pipeless plants have not been dealt with. Three main areas of further work have been identified in the safe design of computer controlled pipeless batch plants: process, computer control, and scheduling safety. In essence it is a batch process that is carried out, and therefore entails all the safety issues associated with a batch process, such as the sharing of resources. As with all new processes, it is necessary to identify and eliminate as many hazards as possible at the design stage. Computers can introduce hazards as well as benefits. There is extensive use of computer control in automated pipeless plants, and the primary manner in which problems occur is through hardware and software failures. Possible hazards need to be identified and eliminated at the design stage, without losing the benefits of plant flexibility and speed of product changeover. Scheduling is usually concerned with optimum product output, and does not consider safety. One of the biggest problems with moving reactors is collisions. To overcome, or minimise the possibility of this problem, the plant layout and schedule require careful consideration. Simulation is a very useful tool for demonstrating the interaction between the two. The aim of this research is to develop an integrated approach to hazard identification and safety requirement specification. The results of which should be a methodology that allows the user to produce a safe design for an economically attractive pipeless plant for batch processes.

Compliance, the extent to which patients follow a medication regimen, has been recognized as one of the most serious problems facing medical practice today. Recent developments in assessing compliance include electronic compliance monitors (ECM), devices that record the date and time of the release of medication from its original container. This allows utilizing ECM compliance data in statistical analyses related to clinical trials. This thesis proposes ways of dealing with the time-varying nature of compliance. We examine the compliance behaviour from real ECM data through statistical analysis of compliance rate, followed by a time-to-event analysis with respect to first noncompliance event. Then, using discrete event simulation and proportional hazards models we compare analyses using a fixed treatment covariate and time-varying compliance covariate based on pharmacokinetic principles in estimating treatment effect. We observe a reduction of up to 40% in EMSE in favour of the latter model for treatment effect estimation.

Research shows that in a system model, when the production rate is adjusted based on the number of items in queue, the nature of the model changes from an open-loop queueing system to a closed-loop feedback control system. Service-rate adjustment can be implemented in a discrete event simulation model, but the effect of this adjustment has not been thoroughly analyzed in the literature. This research considers the design of feedback signals to generate realistic simulation models of production system behavior. A series of simulation experiments is conducted to provide practical guidance for simulation modelers on how adding a service-rate adjustment feedback loop to a queueing system affects system performance.

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