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Holmgren, Johan
Publications (10 of 47) Show all publications
Abid, M. A., Amouzad Mahdiraji, S., Lorig, F., Holmgren, J., Mihailescu, R.-C. & Petersson, J. (2023). A Genetic Algorithm for Optimizing Mobile Stroke Unit Deployment. Paper presented at 27th International Conference on Knowledge Based and Intelligent Information and Engineering Systems (KES 2023), Athens, Greece, 6-8 September 2023. Procedia Computer Science, 225, 3536-3545
Open this publication in new window or tab >>A Genetic Algorithm for Optimizing Mobile Stroke Unit Deployment
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2023 (English)In: Procedia Computer Science, ISSN 1877-0509, Vol. 225, p. 3536-3545Article in journal (Refereed) Published
Abstract [en]

A mobile stroke unit (MSU) is an advanced ambulance equipped with specialized technology and trained healthcare personnel to provide on-site diagnosis and treatment for stroke patients. Providing efficient access to healthcare (in a viable way) requires optimizing the placement of MSUs. In this study, we propose a time-efficient method based on a genetic algorithm (GA) to find the most suitable ambulance sites for the placement of MSUs (given the number of MSUs and a set of potential sites). We designed an efficient encoding scheme for the input data (the number of MSUs and potential sites) and developed custom selection, crossover, and mutation operators that are tailored according to the characteristics of the MSU allocation problem. We present a case study on the Southern Healthcare Region in Sweden to demonstrate the generality and robustness of our proposed GA method. Particularly, we demonstrate our method's flexibility and adaptability through a series of experiments across multiple settings. For the considered scenario, our proposed method outperforms the exhaustive search method by finding the best locations within 0.16, 1.44, and 10.09 minutes in the deployment of three MSUs, four MSUs, and five MSUs, resulting in 8.75x, 16.36x, and 24.77x faster performance, respectively. Furthermore, we validate the method's robustness by iterating GA multiple times and reporting its average fitness score (performance convergence). In addition, we show the effectiveness of our method by evaluating key hyperparameters, that is, population size, mutation rate, and the number of generations.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
genetic algorithm, mobile stroke unit (MSU), optimization, healthcare, time to treatment
National Category
Communication Systems Neurology
Identifiers
urn:nbn:se:mau:diva-64632 (URN)10.1016/j.procs.2023.10.349 (DOI)
Conference
27th International Conference on Knowledge Based and Intelligent Information and Engineering Systems (KES 2023), Athens, Greece, 6-8 September 2023
Funder
The Kamprad Family Foundation
Available from: 2023-12-20 Created: 2023-12-20 Last updated: 2023-12-20Bibliographically approved
Fredriksson, H., Holmgren, J., Dahl, M. & Lövström, B. (2023). A Median-Based Misery Index for Travel Time Reliability. Paper presented at The 14th International Conference on Ambient Systems, Networks and Technologies (ANT), March 15-17 ,2023,Leuven ,Belgium. Procedia Computer Science, 220, 162-169
Open this publication in new window or tab >>A Median-Based Misery Index for Travel Time Reliability
2023 (English)In: Procedia Computer Science, E-ISSN 1877-0509, Vol. 220, p. 162-169Article in journal (Refereed) Published
Abstract [en]

Travel time reliability is vital for both road agencies and road users. Expected travel time reliability can be used by road agencies to assess the state of a transportation system, and by road users, to schedule their trips. Road network deficiencies, such as insufficient traffic flow capacity of a road segment or poor road design, have a negative impact on the reliability of travel times. Thus, to maintain robust and reliable travel times, the detection of road network deficiencies is vital. By continuously analyzing travel times and using appropriate travel time reliability measurements, it is possible to detect existing deficiencies or deficiencies that may eventually occur unless necessary actions are taken. In many cases, indices and measurements of travel time reliability are related to the distribution of the travel times, specifically the skewness and width of the distribution. The current paper introduces a median-based misery index for travel time reliability. The index is robust and handles travel times that follow a skewed distribution well. The index measures the relative difference between the slow travel speeds and the free-flow travel speed. The index is inspired by the median absolute deviation, and its primary application is to detect routes or road segments with potential road network deficiencies. To demonstrate the applicability of the index, we conducted an empirical case study using real travel speed data from the European route E4 in Sweden. The results from the empirical case study indicate that the index is capable of detecting road segments with slow travel speeds regardless of the travel speed distribution.

Place, publisher, year, edition, pages
Elsevier, 2023
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:mau:diva-64312 (URN)10.1016/j.procs.2023.03.023 (DOI)2-s2.0-85164538353 (Scopus ID)
Conference
The 14th International Conference on Ambient Systems, Networks and Technologies (ANT), March 15-17 ,2023,Leuven ,Belgium
Funder
Swedish Transport Administration
Available from: 2023-12-12 Created: 2023-12-12 Last updated: 2023-12-22Bibliographically approved
Amouzad Mahdiraji, S., Abid, M. A., Holmgren, J., Mihailescu, R.-C., Lorig, F. & Petersson, J. (2023). An Optimization Model for the Placement of Mobile Stroke Units. In: Teresa Guarda; Filipe Portela; Jose Maria Diaz-Nafria (Ed.), Advanced Research in Technologies, Information, Innovation and Sustainability: Third International Conference, ARTIIS 2023, Madrid, Spain, October 18–20, 2023, Proceedings, Part I. Paper presented at Advanced Research in Technologies, Information, Innovation and Sustainability, Third International Conference, ARTIIS 2023, Madrid, Spain, October 18–20, 2023 (pp. 297-310). Springer
Open this publication in new window or tab >>An Optimization Model for the Placement of Mobile Stroke Units
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2023 (English)In: Advanced Research in Technologies, Information, Innovation and Sustainability: Third International Conference, ARTIIS 2023, Madrid, Spain, October 18–20, 2023, Proceedings, Part I / [ed] Teresa Guarda; Filipe Portela; Jose Maria Diaz-Nafria, Springer, 2023, p. 297-310Conference paper, Published paper (Refereed)
Abstract [en]

Mobile Stroke Units (MSUs) are specialized ambulances that can diagnose and treat stroke patients; hence, reducing the time to treatment for stroke patients. Optimal placement of MSUs in a geographic region enables to maximize access to treatment for stroke patients. We contribute a mathematical model to optimally place MSUs in a geographic region. The objective function of the model takes the tradeoff perspective, balancing between the efficiency and equity perspectives for the MSU placement. Solving the optimization problem enables to optimize the placement of MSUs for the chosen tradeoff between the efficiency and equity perspectives. We applied the model to the Blekinge and Kronoberg counties of Sweden to illustrate the applicability of our model. The experimental findings show both the correctness of the suggested model and the benefits of placing MSUs in the considered regions.

Place, publisher, year, edition, pages
Springer, 2023
Series
Communications in Computer and Information Science, ISSN 1865-0929, E-ISSN 1865-0937 ; 1935
Keywords
Optimization, MILP, Time to Treatment, Mobile Stroke Unit (MSU), MSU Placement
National Category
Neurology Computational Mathematics
Identifiers
urn:nbn:se:mau:diva-64865 (URN)10.1007/978-3-031-48858-0_24 (DOI)2-s2.0-85180781530 (Scopus ID)978-3-031-48857-3 (ISBN)978-3-031-48858-0 (ISBN)
Conference
Advanced Research in Technologies, Information, Innovation and Sustainability, Third International Conference, ARTIIS 2023, Madrid, Spain, October 18–20, 2023
Available from: 2024-01-08 Created: 2024-01-08 Last updated: 2024-01-08Bibliographically approved
Amouzad Mahdiraji, S., Holmgren, J., Alshaban, A., Mihailescu, R.-C., Petersson, J. & Al Fatah, J. (2022). A Framework for Constructing Discrete Event Simulation Models for Emergency Medical Service Policy Analysis. Paper presented at 12th International Conference on Current and Future Trends of Information and Communication Technologies in Health care (ICTH 2022) October 26-28, 2022, Leuven, Belgium. Procedia Computer Science, 210, 133-140
Open this publication in new window or tab >>A Framework for Constructing Discrete Event Simulation Models for Emergency Medical Service Policy Analysis
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2022 (English)In: Procedia Computer Science, E-ISSN 1877-0509, Vol. 210, p. 133-140Article in journal (Refereed) Published
Abstract [en]

Constructing simulation models can be a complex and time-consuming task, in particular if the models are constructed from scratch or if a general-purpose simulation modeling tool is used. In this paper, we propose a model construction framework, which aims to simplify the process of constructing discrete event simulation models for emergency medical service (EMS) policy analysis. The main building blocks used in the framework are a set of general activities that can be used to represent different EMS care chains modeled as flowcharts. The framework allows to build models only by specifying input data, including demographic and statistical data, and providing a care chain of activities and decisions. In a case study, we evaluated the framework by using it to construct a model for the simulation of the EMS activities related to acute stroke. Our evaluation shows that the predefined activities included in the framework are sufficient to build a simulation model for the rather complex case of acute stroke.

Place, publisher, year, edition, pages
Elsevier, 2022
National Category
Probability Theory and Statistics
Identifiers
urn:nbn:se:mau:diva-56003 (URN)10.1016/j.procs.2022.10.129 (DOI)2-s2.0-85144819456 (Scopus ID)
Conference
12th International Conference on Current and Future Trends of Information and Communication Technologies in Health care (ICTH 2022) October 26-28, 2022, Leuven, Belgium
Available from: 2022-11-14 Created: 2022-11-14 Last updated: 2024-02-05Bibliographically approved
Amouzad Mahdiraji, S., Holmgren, J., Mihailescu, R.-C. & Petersson, J. (2022). A Micro-Level Simulation Model for Analyzing the Use of MSUs in Southern Sweden. Paper presented at 11th International Conference on Current and Future Trends of Information and Communication Technologies in Healthcare (ICTH 2021) November 1-4, 2021, Leuven, Belgium. Procedia Computer Science, 198, 132-139
Open this publication in new window or tab >>A Micro-Level Simulation Model for Analyzing the Use of MSUs in Southern Sweden
2022 (English)In: Procedia Computer Science, E-ISSN 1877-0509, Vol. 198, p. 132-139Article in journal (Refereed) Published
Abstract [en]

A mobile stroke unit (MSU) is a special type of ambulance, where stroke patients can be diagnosed and provided intravenous treatment, hence allowing to cut down the time to treatment for stroke patients. We present a discrete event simulation (DES) model to study the potential benefits of using MSUs in the southern health care region of Sweden (SHR). We included the activities and actions used in the SHR for stroke patient transportation as events in the DES model, and we generated a synthetic set of stroke patients as input for the simulation model. In a scenario study, we compared two scenarios, including three MSUs each, with the current situation, having only regular ambulances. We also performed a sensitivity analysis to further evaluate the presented DES model. For both MSU scenarios, our simulation results indicate that the average time to treatment is expected to decrease for the whole region and for each municipality of SHR. For example, the average time to treatment in the SHR is reduced from 1.31h in the baseline scenario to 1.20h and 1.23h for the two MSU scenarios. In addition, the share of stroke patients who are expected to receive treatment within one hour is increased by a factor of about 3 for both MSU scenarios.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Ischemic stroke; stroke transport; MSU; DES; time to treatment; stroke logistics
National Category
Computational Mathematics
Identifiers
urn:nbn:se:mau:diva-54479 (URN)10.1016/j.procs.2021.12.220 (DOI)2-s2.0-85124617439 (Scopus ID)
Conference
11th International Conference on Current and Future Trends of Information and Communication Technologies in Healthcare (ICTH 2021) November 1-4, 2021, Leuven, Belgium
Available from: 2022-08-22 Created: 2022-08-22 Last updated: 2024-02-05Bibliographically approved
Fredriksson, H., Dahl, M., Lövström, B., Holmgren, J. & Lennerstad, H. (2022). Modeling of road traffic flows in the neighboring regions. Procedia Computer Science, 198, 43-50
Open this publication in new window or tab >>Modeling of road traffic flows in the neighboring regions
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2022 (English)In: Procedia Computer Science, E-ISSN 1877-0509, Vol. 198, p. 43-50Article in journal (Refereed) Published
Abstract [en]

Traffic flows play a very important role in transportation engineering. In particular, link flows are a source of information about the traffic state, which is usually available from the authorities that manage road networks. Link flows are commonly used in both short-term and long-term planning models for operation and maintenance, and to forecast the future needs of transportation infrastructure. In this paper, we propose a model to study how traffic flow in one location can be expected to reflect the traffic flow in a nearby region. The statistical basis of the model is derived from link flows to find estimates of the distribution of traffic flows in junctions. The model is evaluated in a numerical study, which uses real link flow data from a transportation network in southern Sweden. The results indicate that the model may be useful for studying how large departing flows from a node reflect the link flows in a neighboring geographic region.

Place, publisher, year, edition, pages
Elsevier, 2022
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:mau:diva-56807 (URN)10.1016/j.procs.2021.12.209 (DOI)2-s2.0-85124595881 (Scopus ID)
Available from: 2022-12-19 Created: 2022-12-19 Last updated: 2024-02-05Bibliographically approved
Alassadi, A., Lorig, F. & Holmgren, J. (2022). Population Generation for Agent-based Simulations of Stroke Logistics Policies: A Case Study of Stroke Patient Mobility. International Journal on Advances in Life Sciences, 14(1&2), 12-21
Open this publication in new window or tab >>Population Generation for Agent-based Simulations of Stroke Logistics Policies: A Case Study of Stroke Patient Mobility
2022 (English)In: International Journal on Advances in Life Sciences, E-ISSN 1942-2660, Vol. 14, no 1&2, p. 12-21Article in journal (Refereed) Published
Abstract [en]

For acute medical conditions, for instance strokes, the time until the start of the treatment is a crucial factor to prevent a fatal outcome and to facilitate the recovery of the patient’s health. Hence, the planning and optimization of patient logistics is of high importance to ensure prompt access to healthcare facilities in case of medical emergencies. Computer simulation can be used to investigate the effects of different stroke logistics policies under realistic conditions without jeopardizing the health of the patients. The success of such policies greatly depends on the behavior of the individuals. Hence, agent-based simulation is particularly well-suited as it imitates human behavior and decision-making by means of artificial intelligence, which allows for investigating the effects of policies under different conditions. Agent-based simulation requires the generation of a realistic synthetic population, that adequately represents the population that shall be investigated such that reliable conclusions can be drawn from the simulation results. In this article, we propose a process for generating an artificial population of potential stroke patients that can be used to investigate the effects of stroke logistics policies using agent-based simulation. To illustrate how this process can be applied, we present the results from a case study in the region of Skåne in southern Sweden, where a synthetic population of stroke patients with realistic mobility behavior is simulated. 

Place, publisher, year, edition, pages
International Academy, Research and Industry Association (IARIA), 2022
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:mau:diva-56757 (URN)
Available from: 2022-12-15 Created: 2022-12-15 Last updated: 2024-04-26Bibliographically approved
Alassadi, A., Lorig, F. & Holmgren, J. (2021). An Agent-based Model for Simulating Travel Patterns of Stroke Patients. In: Wanwan Li; Manuela Popescu (Ed.), DIGITAL 2021: Advances on Societal Digital Transformation. Paper presented at DIGITAL 2021 – Advances on Societal Digital Transformation, 14-18 November 2021, Athens, Greece (pp. 11-16). ThinkMind
Open this publication in new window or tab >>An Agent-based Model for Simulating Travel Patterns of Stroke Patients
2021 (English)In: DIGITAL 2021: Advances on Societal Digital Transformation / [ed] Wanwan Li; Manuela Popescu, ThinkMind , 2021, p. 11-16Conference paper, Published paper (Refereed)
Abstract [en]

For patients suffering from a stroke, the time until the start of the treatment is a crucial factor with respect to the recovery from this condition. In rural regions, transporting the patient to an adequate hospital typically delays the diagnosis and treatment of a stroke, worsening its prognosis. To reduce the time to treatment, different policies can be applied. This includes, for instance, the use of Mobile Stroke Units (MSUs), which are specialized ambulances that can provide adequate care closer to where the stroke occurred. To simulate and assess different stroke logistics policies, such as the use of MSUs, a major challenge is the realistic modeling of the patients. In this article, we present an approach for generating an artificial population of stroke patients to simulate when and where strokes occur. We apply the model to the region of Skåne, where we investigated the relevance of travel behavior on the spatial distribution of stroke patients.

Place, publisher, year, edition, pages
ThinkMind, 2021
Keywords
Agent-based Social Simulation, Synthetic Population, Population Generation, Mobile Stroke Unit
National Category
Transport Systems and Logistics Computer and Information Sciences
Identifiers
urn:nbn:se:mau:diva-48338 (URN)978-1-61208-927-0 (ISBN)
Conference
DIGITAL 2021 – Advances on Societal Digital Transformation, 14-18 November 2021, Athens, Greece
Available from: 2021-12-27 Created: 2021-12-27 Last updated: 2021-12-27Bibliographically approved
Dytckov, S., Lorig, F., Holmgren, J., Davidsson, P. & Persson, J. A. (2021). An Individual-Based Simulation Approach to Demand Responsive Transport. In: Intelligent Transport Systems, From Research and Development to the Market Uptake: . Paper presented at 4th International Conference on Intelligent Transport Systems, Virtual Event, December 3, 2020 (pp. 72-89). Springer
Open this publication in new window or tab >>An Individual-Based Simulation Approach to Demand Responsive Transport
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2021 (English)In: Intelligent Transport Systems, From Research and Development to the Market Uptake, Springer, 2021, p. 72-89Conference paper, Published paper (Refereed)
Abstract [en]

This article demonstrates an approach to the simulation of Demand Responsive Transport (DRT) – a flexible transport mode that typically operates as a combination of taxi and bus modes. Travellers request individual trips and DRT is capable of adjusting its routes or schedule to the needs of travellers. It has been seen as a part of the public transport network, which has the potential to reduce operational costs of public transport services, to provide better service quality for population groups with limited mobility and to improve transport fairness. However, a DRT service needs to be thoroughly planned to target the intended user groups, attract a sufficient demand level and maintain reasonable operational costs. As the demand for DRT is dynamic and heterogeneous, it is difficult to simulate it with a macro approach. To address this problem, we develop and evaluate an individual-based simulation comprising models of traveller behaviour for both supply and demand sides. Travellers choose a trip alternative with a mode choice model and DRT vehicle routing utilises a model of travellers’ mode choice behaviour to optimise routes. This allows capturing supply-side operational costs and demand-side service quality for every individual, what allows for designing a personalised service that can prioritise needy groups of travellers improving transport fairness. By simulating different setups of DRT services, the simulator can be used as a decision support tool.

Place, publisher, year, edition, pages
Springer, 2021
Series
Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, ISSN 1867-8211, E-ISSN 1867-822X ; 364
National Category
Transport Systems and Logistics Computer Sciences
Research subject
Transportation studies
Identifiers
urn:nbn:se:mau:diva-41490 (URN)10.1007/978-3-030-71454-3_5 (DOI)2-s2.0-85104409614 (Scopus ID)978-3-030-71454-3 (ISBN)978-3-030-71453-6 (ISBN)
Conference
4th International Conference on Intelligent Transport Systems, Virtual Event, December 3, 2020
Available from: 2021-03-30 Created: 2021-03-30 Last updated: 2024-02-05Bibliographically approved
Mahdiraji, S. A., Holmgren, J., Mihailescu, R.-C. & Petersson, J. (2021). An Optimization Model for the Tradeoff Between Efficiency and Equity for Mobile Stroke Unit Placement. In: Innovation in Medicine and Healthcare: Proceedings of 9th KES-InMed 2021. Paper presented at 9th KES-InMed 2021 (pp. 183-193). Springer
Open this publication in new window or tab >>An Optimization Model for the Tradeoff Between Efficiency and Equity for Mobile Stroke Unit Placement
2021 (English)In: Innovation in Medicine and Healthcare: Proceedings of 9th KES-InMed 2021, Springer, 2021, p. 183-193Conference paper, Published paper (Refereed)
Abstract [en]

A mobile stroke unit (MSU) is an ambulance, where stroke patients can be diagnosed and treated. Recently, placement of MSUs has been studied focusing on either maximum population coverage or equal service for all patients, termed efficiency and equity, respectively. In this study, we propose an unconstrained optimization model for the placement of MSUs, designed to introduce a tradeoff between efficiency and equity. The tradeoff is based on the concepts of weighted average time to treatment and the time difference between the expected time to treatment for different geographical areas. We conduct a case-study for Sweden’s Southern Health care Region (SHR), generating three scenarios (MSU1, MSU2, and MSU3) including 1, 2, and 3 MSUs, respectively. We show that our proposed optimization model can tune the tradeoff between the efficiency and equity perspectives for the MSU(s) allocation. This enables a high level of equal service for most inhabitants, as well as reducing the time to treatment for most inhabitants of a geographic region. In particular, placing three MSUs in the SHR with the proposed tradeoff, the share of inhabitants who are expected to receive treatment within an hour potentially improved by about a factor of 14 in our model.

Place, publisher, year, edition, pages
Springer, 2021
Series
Smart Innovation, Systems and Technologies, ISSN 2190-3018, E-ISSN 2190-3026 ; 242
Keywords
Driving time estimation, Efficient coverage, Equal treatment, Mobile stroke unit, Time to treatment, Tradeoff function, Efficiency, Optimization, Equal services, Expected time, Geographical area, Optimization modeling, Stroke patients, Time-differences, Unconstrained optimization, Weighted averages, Patient treatment
National Category
Communication Systems
Identifiers
urn:nbn:se:mau:diva-45147 (URN)10.1007/978-981-16-3013-2_15 (DOI)2-s2.0-85111101237 (Scopus ID)9789811630125 (ISBN)
Conference
9th KES-InMed 2021
Available from: 2021-08-23 Created: 2021-08-23 Last updated: 2024-02-05Bibliographically approved
Projects
Smart Public Environments II; Malmö University
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