Predictive analytics and simulation modeling are two complementary disciplines that will increasingly be used together in the future. They share in common a focus on predicting how systems, existing or proposed, will ...
详细信息
ISBN:
(纸本)9781479939503;9781479920778
Predictive analytics and simulation modeling are two complementary disciplines that will increasingly be used together in the future. They share in common a focus on predicting how systems, existing or proposed, will function. The predictions may be values of quantifiable metrics or classification of outcomes. Both require collection of data to increase their validity and accuracy. The coming era of big data will be a boon to both and will accelerate the need to use them in conjunction. This paper discusses ways in which the two disciplines have been used together as well as how they can be viewed as belonging to the same modeling continuum. Various modeling techniques from both disciplines are reviewed using a common notation. Finally, examples are given to illustrate these notions.
Understanding the current manufacturing setup and accurately predicting the performance of a system over time makes modeling and simulation an ideal tool for systems' planning. This case study aims mainly at explo...
详细信息
ISBN:
(纸本)9781479939503;9781479920778
Understanding the current manufacturing setup and accurately predicting the performance of a system over time makes modeling and simulation an ideal tool for systems' planning. This case study aims mainly at exploring the application of modeling and simulation (M&S) in order to evaluate and provide performance results that could help measure the capacity and the capability of an existing mattress production line, and to further investigate whether the production line could cope with the firm's expansion plan over the next five years. The simulation model was built and analyzed using the ProModel discrete-event simulation software. The analysis found that the current production setup could not cope with the demand over the next five years. Therefore, potential improvements within the production line were identified and implemented in an improved scenario model. The results indicated that the new system was able to meet the new demand and cope with the proposed expansion plan.
The modeling and simulation (M&S) literature is rich with procedures, standards, conceptual frameworks, and M&S-related theories that provide frames of reference for M&S validation. However, these works ar...
详细信息
ISBN:
(纸本)9781479939503;9781479920778
The modeling and simulation (M&S) literature is rich with procedures, standards, conceptual frameworks, and M&S-related theories that provide frames of reference for M&S validation. However, these works are disjoint, leading to inconsistencies: common terms used differently, differing terms for similar concepts, varying degrees of detail, and conflicting assumptions. There is no single, unifying frame of reference for validation. This has restricted the development of a common theoretical and practical understanding of validation across the M&S field. This paper introduces the concept of a validation frame of reference;builds a taxonomy of using frames of reference found in the validation literature;and proposes the creation of a unifying theoretical framework for M&S validation to build a foundation for the development of a paradigm of common theoretical and practical understanding of validation across the M&S field.
Faced with a mismatch between demand and resources, Emergency Department (ED) administrators and staff need to gauge the impacts of staff decision processes in lieu of increasing resource levels. In this paper we pres...
ISBN:
(纸本)9781479939503;9781479920778
Faced with a mismatch between demand and resources, Emergency Department (ED) administrators and staff need to gauge the impacts of staff decision processes in lieu of increasing resource levels. In this paper we present REDSim, a spatial agent-based simulation framework for studying emergency departments. REDSim focuses on quantifying the impacts of staff decision processes, such as patient selection, on the length of stay, waiting and boarding times, and other variables. We show REDSim's effectiveness by comparing four patient selection strategies: longest waiting, shortest distance, random, and highest acuity. REDSim showed that although patient length of stay is not significantly reduced (1.4%) the throughput increases 17% when providers select the closest instead of the highest acuity patient for the next task.
Temporal perspectives play a vital role in shaping narratives. Such perspectives include models of time that support the practice of construction management. Although formal representations of time are rarely noticed,...
详细信息
ISBN:
(纸本)9781479939503;9781479920778
Temporal perspectives play a vital role in shaping narratives. Such perspectives include models of time that support the practice of construction management. Although formal representations of time are rarely noticed, they strongly influence the variables and relationships that can be encoded in process models. The objective of this paper is to illustrate the distinct ways in which the time can be formalized and how they impact the understanding of project performance and productivity. It explores existing and new temporal representations on how they contribute to improving reasoning capabilities in construction processes. Existing models differ by whether they use time points or intervals to represent activities (e.g. activity-on-node networks versus Gantt bar charts) and how clearly they communicate changes during execution. While traditional approaches exhibit shortcomings, singularity functions have significant potential for further development and could benefit from conceptual integration with situational simulation toward a powerful and integrated temporal modeling scheme.
This paper studies Work-In-Process (WIP) inventory problems in a multi-tightly-coupled-cells production system. Through an analysis of an AS-IS simulation model, ineffective control of tightly coupled cells cause seri...
详细信息
ISBN:
(纸本)9781479939503;9781479920778
This paper studies Work-In-Process (WIP) inventory problems in a multi-tightly-coupled-cells production system. Through an analysis of an AS-IS simulation model, ineffective control of tightly coupled cells cause serious system bottlenecks, higher WIP inventory levels and longer cycle times. Aiming to resolve these problems, a hybrid control method and a corresponding centralized hybrid controller are developed. This optimized method is used to monitor the changes in WIP and improve WIP control by integrating the Pull and Push modes. In a TO-BE simulation model, the centralized hybrid controller is embedded to execute this optimized control idea. The model is explored with a control objective to maintain the WIP inventory and cycle times at low levels by dynamically regulating the processing rate of distributed workstations. The simulation results demonstrate that this optimized method avoids system instability and eliminates bottlenecks. By comparison, the proposed approach significantly improves the system's performance, rapid response and robustness.
When collecting data to select an alternative from a finite set of alternatives that are described by multiple attributes, one must allocate effort to activities that provide information about the value of each attrib...
详细信息
ISBN:
(纸本)9781479939503;9781479920778
When collecting data to select an alternative from a finite set of alternatives that are described by multiple attributes, one must allocate effort to activities that provide information about the value of each attribute. This is a particularly relevant problem when the attribute values are estimated using experimental data. This paper discusses the problem of allocating an experimental budget amongst two attributes when the non-dominated decision alternatives form a concave efficient frontier. The results of a simulation study suggested allocation rules that take advantage of knowledge of the decision model and, when available, knowledge about the general shape of the frontier. These rules were compared to a default rule that equally allocated the experimental budget across the attributes. A proportional rule that allocated samples based on the value function weights performed well only in some cases;a more sophisticated step rule increased the frequency of correct selection across all weights.
In this paper we present a simulation model for large networks that increases the efficiency compared to a discrete event simulation model. These networks have two different time scales: a fast one and a slow one. The...
详细信息
ISBN:
(纸本)9781479939503;9781479920778
In this paper we present a simulation model for large networks that increases the efficiency compared to a discrete event simulation model. These networks have two different time scales: a fast one and a slow one. The main idea is to replace some of the faster point processes by a "fluid" (called the ghost processes) thus accelerating the execution of the simulation. Using local modularity for the code, there is no need to keep a list of events. Clocks are not necessarily synchronized. When a local clock advances due to a slower event, retrospective calculations recover the fine detail lost in the fluid model. Mathematically, the model is a special case of the Filtered Monte Carlo method. Efficiency improvement results not only from the speed of execution, but also from variance reduction. We provide proofs of unbiasedness. Throughout the paper we use a case scenario of an airport car park.
Based on a discrete-event simulation model, simulation-based Real-time Decision-making (SRDM) is an innovative approach to real-time, goal-directed decision-making. When applied to a flexible manufacturing system, SRD...
详细信息
ISBN:
(纸本)0780381319
Based on a discrete-event simulation model, simulation-based Real-time Decision-making (SRDM) is an innovative approach to real-time, goal-directed decision-making. When applied to a flexible manufacturing system, SRDM makes better decisions than most fixed policies, such as deterministic, stochastic and manual. SRDM even improved over fixed policies optimized within a class of policies by OptQuest, in our numerical experiments. Compared to these fixed policies, SRDM shows greater improvement for more complex systems and is quite robust with respect to modeling errors. SRDM provides an improvement over fixed policies by its ability to implement adaptive policies. Since most real-time decisions in currently deployed manufacturing systems are made either manually or by using fixed policies, our results suggest that using SRDM instead could lead to significant improvement in operating performance.
This paper describes a diagramming methodology, referred to as an Object Flow Diagram (OFD), that is intended to be a key component in the conceptual design of a discrete-event simulation model. It provides an effecti...
详细信息
ISBN:
(纸本)9781479939503;9781479920778
This paper describes a diagramming methodology, referred to as an Object Flow Diagram (OFD), that is intended to be a key component in the conceptual design of a discrete-event simulation model. It provides an effective means for representing salient system elements and their relationships. It draws upon other popular system diagramming methods, such as IDEF0 and IDEF3, to bring the relevant aspects of these tools to the simulation modeler. It is intended to be easy to apply, with few symbols and constructs, yet robust and comprehensive enough to represent a wide variety of systems. It is simulation software neutral and thus provides a basis for model development in any language. A simple example is used to illustrate the approach. The methodology has been used in industry projects and in simulation courses.
暂无评论