Academic articles

A multi-paradigm, whole system view of health and social care for age-related macular degeneration

This paper presents a hybrid simulation model for the management of an eye condition called age-related macular degeneration, which particularly affects the elderly. The model represents not only the detailed clinical progression of disease in an individual, but also the organization of the hospital clinic in which patients with this condition are treated and the wider environment in which these patients live (and their social care needs, if any, are met). The model permits a ‘whole system’ societal view which captures the interactions between the health and social care systems

Advancement simulation of tunnel boring machines

In mechanized tunneling a significant loss of performance resulting from weak spots in the supply chain or unforeseen geological conditions is a frequent and costly problem. Furthermore, disturbances of critical machine components can have such impact on the production that unforeseen modifications become necessary. Due to the sequential character the malfunction of one element might evoke cascading-effects which may result in a complete standstill of the tunneling progress. Transparent evaluation of applicable tunnel boring machine designs is essential in order to improve the productivity, avoid unplanned interruptions and to estimate the project duration in general. In order to meet these defiances, this paper presents a multimethod simulation model to investigate the advancement rate of tunnel boring machines. Processrelated disturbances can be considered easily within the presented simulation model. Simulation experiments demonstrate the purposive functionality of the model and visualize the significant influence of technical failure on the overall project performance

Hybrid simulation of renewable energy generation and storage grids

The share of renewable energy sources in energy production is growing steadily. Domestic homes can be equipped with solar panels, micro combined heat and power systems, batteries, and they can become adaptive consumers. They can also deliver energy to the grid and react to the energy supply. This paper presents a hybrid simulation approach for the analysis of a grid of domestic homes equipped with different technological options with respect to efficiency and costs. For energy storage and energy flows the system dynamics modeling paradigm is used whereas control decisions are modeled as statecharts. The highly intermittent solar irradiation and also the electric power and heat demands are implemented as stochastic models. The component-based design allows for quick creation of new case studies. As examples, different homes with batteries, micro combined heat and power systems, or energy carrier carbazole as energy storage are analyzed

Agent-based simulation of the software development process: a case study at AVL

Software development projects are difficult to manage due to the high uncertainty in their various phases. Simulation is one of the tools that has been used to help software project managers produce project plans. Research into software process simulation modeling (SPSM) shows the dominance of discrete-event simulation and system dynamics. This paper supports the use of ABS in SPSM. We propose a practical effort function to estimate developers’ behavior. The other contribution of this paper is to demonstrate how the ABS model can be developed, calibrated and validated using data readily available to many software development companies/departments. This paper focuses on the construction phase of a tailored Rational Unified Process used in a geographically distributed software development department at AVL. The results look promising but more work needs to be done to include ABS into one of the mainstream simulation paradigms in SPSM

Using a scalable simulation model to evaluate the performance of production system segmentation in a combined MRP and Kanban system

In this paper two different possible machine allocation policies are studied for a production system consisting of MRP and kanban controlled materials. Performance measures are inventory costs, backorder costs and service level. In policy one, the production system is segmented into one segment for MRP planned materials and one for kanban controlled materials. Policy two implements common machine groups for both kinds of materials. A scalable production planning simulation model is applied which is set up by parameterization of the respective database without any model implementation work. For high set-up times and low number of items, we find that whenever utilization of the production system is high, the production system segmentation policy is preferable. However, for medium and low utilization values common machine groups perform best in all scenarios. The scalable simulation model for different kinds of production systems contributes to further research in this field

A simulation study of the effect of mosque design on egress times

The Mosque prayer hall is perhaps the only architectural space designed for a large number of floorseated occupants. A critical issue in the design of mosques is determining the number and configuration of exit locations. This paper describes a discrete-event simulation model developed to assess the effect of mosque prayer hall configuration on the egress times of the occupants. The simulation model takes into consideration the behavioral aspects of the mosque occupants such as shoe placement and pickup, after prayer lingering, late egress of front rows, after prayers, and congregations inside and outside the mosque. Most of the various exit configurations possible in mosque design are modeled and assessed for total egress time as well as flow rates. It is shown that one-sided exit location out performs all other configurations. The study presents the first such analysis of mosque egress and the results should of great interest to architects and researchers alike

Complex agent interactions in operational simulations for aerospace design

Product complexity in the aerospace industry has grown fast while design procedures and techniques did not keep pace. Product life cycle implications are largely neglected during the early design phase. Also, aerospace designers fail to optimize products for the intended operational environment. This study shows how a design, simulated within its anticipated operational environment, can inform about critical design parameters, thereby creating a more targeted design improving the chance of commercial success. An agent-based operational simulation for civil Unmanned Aerial Vehicles conducting maritime Search-andRescue missions is used to design and optimize aircrafts. Agent interactions with their environment over the product life-cycle are shown to lead to unexpected model outputs. Unique insights into the optimal design are gained by analysis of the operational performance of the aircraft within its simulated environment

Hybrid simulation with loosely coupled system dynamics and agent-based models for prospective health technology assessments

Due to the ageing of the world population, the demand for technology innovations in healthcare is growing rapidly. All stakeholders (e.g., patients, healthcare providers and health industry) can take profit of innovative products, but the development degenerates often into a time consuming and cost-intensive process. Prospective Health Technology Assessment (ProHTA) is a new approach that combines the knowledge of an interdisciplinary team and uses simulation techniques to indicate the effects of new innovations early before the expensive and risky development phase begins. In this paper, we describe an approach with loosely coupled system dynamics and agent-based models within a hybrid simulation environment for ProHTA as well as a use-case scenario with an innovative stroke technology

The service productivity learning cockpit – a business-intelligence tool for service enterprises

Computer simulation is a way to imitate business processes based on reality. Due to the fact that the environment in hospitals is highly dynamic with local autonomy of stakeholders participating in the business processes, we found an agent–based modeling and simulation (ABMS) approach to be most suitable and it is therefore applied in this context. From an inception to a running simulation, followed by an analysis of the output, we need to keep in mind our user’s physical problem as well as their capability of digesting the results. An interface between a computer modeler/programmer’s deliverable and a user like a hospital manager who learns from the simulated behavior of physical reality, is a visualization tool. We call this tool a “Learning Cockpit” (LC). Although a manager has experience in managing their business and they use personal qualities to positively drive their organization in challenging business environments, a simulation provides them additional support in decision process. With the help of simulation, they should be able to clearly and concisely grasp the information about the current operations, the resources involved and the inherent costs to get an output. They should be able to measure the performance of the current setup, and if necessary, make some changes and bring more value to the organization

Saving and Restoring Anylogic 6 Model Snapshot

We are pleased to announce a new feature available in AnyLogic 6 Professional Edition: now you are able to save the full state of a model (the snapshot) during runtime to a file, restore it at a later time and continue running simulation from the same point. This feature may be useful in several cases:

  • Resilience: when a simulation takes very long time to complete, it may make sense to save its state periodically so that you do not have to start everything...