This paper documents the use of a discrete event simulation model to compare the effectiveness of forecasting systems available to support routine forecasts of criminal events in security applications. Military and po...
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ISBN:
(纸本)9781479939503;9781479920778
This paper documents the use of a discrete event simulation model to compare the effectiveness of forecasting systems available to support routine forecasts of criminal events in security applications. Military and police units regularly use forecasts of criminal events to divide limited resources, assign and redeploy special details, and conduct unit performance assessment. We use the simulation model to test the performance of available forecasting methods under a variety of conditions, including the presence of trends, seasonality, and shocks. We find that, in most situations, a simple forecasting method that fuses the outputs of crime hot-spot maps with the outputs of univariate time series methods both significantly reduces modeling workload and provides significant performance improvement over the three currently used methods: naive forecasts, Holt-winters smoothing, and ARIMA models.
In the context of earth-moving (EM) projects, process-based simulation platforms have demonstrated their effectiveness in predicting project durations, costs, and resource requirements. However, these simulators are d...
ISBN:
(纸本)9781479939503;9781479920778
In the context of earth-moving (EM) projects, process-based simulation platforms have demonstrated their effectiveness in predicting project durations, costs, and resource requirements. However, these simulators are developed by simulation expert using advanced programming techniques. Therefore, understanding the details of these models or enhancing them to fit a particular purpose can be a daunting task. This paper presents Earth-Sim, an EM template developed using the SimFC simulation platform. Earth-Sim mimics the behaviors found in an earlier version of the SIMPHONY EMS template. SIMPHONY EMS was chosen because a) it is a well-recognized template which models all activities within the EM process;and b) it has been validated against data obtained from construction job-sites. This paper explains how Earth-Sim was developed solely using the common elements found in SimFC without any programming. Furthermore, the results obtained from Earth-Sim are compared against results from SIMPHONY EMS to illustrate the validity of the outputs.
In most medium and large sized cities around the world, freight transportation operations might have a noticeable impact on urban traffic mobility as well as on city commercial activities. In order to reduce both traf...
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ISBN:
(纸本)9781479939503;9781479920778
In most medium and large sized cities around the world, freight transportation operations might have a noticeable impact on urban traffic mobility as well as on city commercial activities. In order to reduce both traffic congestion and pollution levels, several initiatives have been traditionally implemented. One of the most common strategies concerns the allocation of urban distribution warehouses near the city center in order to consolidate freight delivery services. This paper considers the integrated problem of locating distribution centers in urban areas and the corresponding freight distribution (vehicle routing). The combined problem is solved by using a hybrid algorithm which employs Monte Carlo simulation to induce biased randomness into several stages of the optimization procedure. The approach is then validated using real-life data and comparing our results with results from other works already available in the existing literature.
Due to the complexity of split delivery vehicle routing problem (SDVRP), a simulation based optimization approach is proposed. A simulation model is used to capture the dynamics and uncertainties of the system and eva...
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ISBN:
(纸本)9781479939503;9781479920778
Due to the complexity of split delivery vehicle routing problem (SDVRP), a simulation based optimization approach is proposed. A simulation model is used to capture the dynamics and uncertainties of the system and evaluate the system performance. Three split policies, LOS-policy, LDD-policy and LWT-policy are designed to implement the order split/consolidation. To optimize the route of orders in a consolidation, a genetic algorithm is developed and integrated with the simulation model. Experimental results showed that the average order size has significant impact on consolidation and split policies. Split delivery outperforms non-split delivery significantly when the average order size occupies about 60% of a truckload. Large arrival rate of orders also benefits split delivery. Sparse distribution of customers deteriorates the performance of split delivery. In various experimental scenarios, LDD-policy is always better than LOS-policy and LWT-policy.
simulation models are commonly used to study traffic systems. Accurate traffic predictions need proper characterization of the traffic flow and knowledge of related parameters representing the state of the traffic flo...
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ISBN:
(纸本)9781479939503;9781479920778
simulation models are commonly used to study traffic systems. Accurate traffic predictions need proper characterization of the traffic flow and knowledge of related parameters representing the state of the traffic flow in the models. To correctly estimate the traffic flow in real time, we need to reconstruct the event by answering such critical questions as the source of the congestions. The availability of sensor data from the real traffic provides information that can be assimilated into a traffic simulation model for improving predicted results. In this paper, we use the sequential Monte Carlo methods to assimilate real time sensor data into the simulation model MovSim, an open-source vehicular-traffic simulator, to reconstruct events such as the slow vehicles that cause the traffic jam. Related experimental results are presented and analyzed.
This paper presents a literature survey on recent use of discrete-event simulation in real-world manufacturing logistics decision-making. The sample of the survey consists of 52 relevant application papers from recent...
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ISBN:
(纸本)9781424405008
This paper presents a literature survey on recent use of discrete-event simulation in real-world manufacturing logistics decision-making. The sample of the survey consists of 52 relevant application papers from recent wintersimulationconference proceedings. We investigated what decisions were supported by the applications, case company characteristics, some methodological issues, and the software tools used. We found that the majority of applications has been reported in production plant design and in the evaluation of production policies, lot sizes, WIP levels and production plans/schedules. Findings also suggest that general-purpose DES software tools are suitable in most of these cases. For different possible reasons, few applications for multi-echelon supply chain decision-making have been reported. Software requirements for supply chain simulations also seem to differ slightly from those for established application areas. The applications described were carried out in a variety of different industries, with a clear predominance in the semiconductor and automotive industries.
Most building energy simulation software offers significant building energy performance capabilities;however, its use is limited to design phase only. There is significant benefit to have these energy simulation model...
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ISBN:
(纸本)9781479939503;9781479920778
Most building energy simulation software offers significant building energy performance capabilities;however, its use is limited to design phase only. There is significant benefit to have these energy simulation models available during operation phase for detection and diagnostics. Since simulation models and real building states are not coupled, the models are initialized in an empty state or run through a warm-up period (i.e., off-line simulation). This paper develops the need and research requirements for on-line simulation of building energy processes where current state variables obtained from sensors and meters in buildings are used to initialize the model. Based on the simulation results, a new corrective decision is made and implemented in the real process. This paper argues that on-line simulation can provide decision makers with reliable energy models to test different technical and behavioral interventions, and improve predictions of building performance, compared to the results obtained with existing off-line models.
Tactical planning of resources in healthcare clinics concerns elective patient admission planning and the intermediate term allocation of resource capacities. Its main objectives are to achieve equitable access for pa...
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ISBN:
(纸本)9781479939503;9781479920778
Tactical planning of resources in healthcare clinics concerns elective patient admission planning and the intermediate term allocation of resource capacities. Its main objectives are to achieve equitable access for patients, to serve the strategically agreed number of patients, and to use resources efficiently. In this paper, we describe a simulation model for an outpatient healthcare clinic facing multiple issues related to patient admission and resource workflow. The main problems identified at the clinic are: 1) phones are not answered promptly and 2) patients experience long wait time to check in and check out. The simulation model focuses on the front desk operations. We investigate different resource allocation policies and report on computational results based on a real clinic, historical data, and both patient and management performance measures.
Workers' absence behavior is not only determined by individuals' personal characteristics or situations, but also strongly affected by workgroup-level properties, such as social norms. This is because workers ...
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ISBN:
(纸本)9781479939503;9781479920778
Workers' absence behavior is not only determined by individuals' personal characteristics or situations, but also strongly affected by workgroup-level properties, such as social norms. This is because workers gather the how-to-behave information not only from formal rules, but also by interacting with their peers to obtain group and organizational approval. Despite the increasing attention being paid to the social control of workers' absence behavior in organizations, to date relatively little work has been done studying the impact of workers' influence networks, in which the social control takes place, on absence behavior. In this paper, we apply agent-based modeling and simulation (ABMS) to study the impact of workers' influence networks on absence behavior. Our simulation results suggest that small social networks of workers could be more effective than big networks in reducing absenteeism when the social control is active.
This paper proposes a Systems Modeling Language (SysML)-based simulation model aggregation framework to develop aggregated simulation models with high accuracy. The framework consists of three major steps: 1) system c...
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ISBN:
(纸本)9781479939503;9781479920778
This paper proposes a Systems Modeling Language (SysML)-based simulation model aggregation framework to develop aggregated simulation models with high accuracy. The framework consists of three major steps: 1) system conceptual modeling, 2) simulation modeling, and 3) additive regression model-based parameter estimation. SysML is first used to construct the system conceptual model for a generic seedling propagation system in terms of system structure and activities in a hierarchical manner (i.e. low, medium and high levels). simulation models conforming to the conceptual model are then constructed in Arena. An additive regression model-based approach is proposed to estimate parameters for the aggregated simulation model. The proposed framework is demonstrated via one of the largest grafted seedling propagation systems in North America. The results reveal that 1) the proposed framework allows us to construct accurate but computationally affordable simulation models for seedling propagation system, and 2) model aggregation increases the randomness of simulation outputs.
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