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Kundundersökningar har visat att det undersökta pappersbruket bör förbättra sina leveransledtider. En lösning för detta anses vara en förändring av nuvarande produktionsstrategi. Den nuvarande produktionsstrategin är kundorderproduktion och de alternativa strategierna som kommer att undersökas under studien är lagerorderproduktion och hybridsystem. Syftet med studien är att undersöka, jämföra och analysera olika produktionsstrategier (lagerorderproduktion, kundorderproduktion och hybridsystem) samt att utvärdera deras inverkan på lagerstyrningen. För att uppnå syftet har studien baserats på tre frågeställningar: Vilka för- och nackdelar har produktionsstrategierna på färdigvarulagret samt vilka nyckeltal behöver identifieras? Vilka problem gällande produktion- och lagerstyrning stöter en produktionsplanerare i ett pappersbruk på? Vilken påverkan har produktionsstrategierna på färdigvarulagret hos det undersökta pappersbruket utifrån identifierade nyckeltal. Frågeställningarna besvarades genom att utföra en litteraturstudie om olika produktionsstrategier och lagerstyrning. Med hjälp av litteraturstudien har lämpliga nyckeltal identifierats för att analysera inverkan på lagerstyrning. Utöver litteraturstudien har intervjuer utförts för att skapa en bredare förståelse kring hur det undersökta pappersbruket i helhet ser på produktionsstrategier och dess inverkan på lagerstyrning. Slutligen utfördes en deskriptiv analys för att beräkna de identifierade nyckeltalen. Resultatet från första frågeställningen visade att olika produktionsstrategier kan bidra med olika för- och nackdelar. Dessutom anses en fördel vara en bidragande faktor till en nackdel, exempelvis för hybridsystem kan en förbättring av leveranstider medföra till problem med lagerfyllning. Det är viktigt att även ta hänsyn till hur marknaden ser ut och vilka faktorer som kan påverka samt vad kunderna efterfrågar. Resultatet från andra frågeställningen presenterade tre sammanfattande problem från de utförda int, Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet

Kundundersökningar har visat att det undersökta pappersbruket bör förbättra sina leveransledtider. En lösning för detta anses vara en förändring av nuvarande produktionsstrategi. Den nuvarande produktionsstrategin är kundorderproduktion och de alternativa strategierna som kommer att undersökas under studien är lagerorderproduktion och hybridsystem. Syftet med studien är att undersöka, jämföra och analysera olika produktionsstrategier (lagerorderproduktion, kundorderproduktion och hybridsystem) samt att utvärdera deras inverkan på lagerstyrningen. För att uppnå syftet har studien baserats på tre frågeställningar: Vilka för- och nackdelar har produktionsstrategierna på färdigvarulagret samt vilka nyckeltal behöver identifieras? Vilka problem gällande produktion- och lagerstyrning stöter en produktionsplanerare i ett pappersbruk på? Vilken påverkan har produktionsstrategierna på färdigvarulagret hos det undersökta pappersbruket utifrån identifierade nyckeltal. Frågeställningarna besvarades genom att utföra en litteraturstudie om olika produktionsstrategier och lagerstyrning. Med hjälp av litteraturstudien har lämpliga nyckeltal identifierats för att analysera inverkan på lagerstyrning. Utöver litteraturstudien har intervjuer utförts för att skapa en bredare förståelse kring hur det undersökta pappersbruket i helhet ser på produktionsstrategier och dess inverkan på lagerstyrning. Slutligen utfördes en deskriptiv analys för att beräkna de identifierade nyckeltalen. Resultatet från första frågeställningen visade att olika produktionsstrategier kan bidra med olika för- och nackdelar. Dessutom anses en fördel vara en bidragande faktor till en nackdel, exempelvis för hybridsystem kan en förbättring av leveranstider medföra till problem med lagerfyllning. Det är viktigt att även ta hänsyn till hur marknaden ser ut och vilka faktorer som kan påverka samt vad kunderna efterfrågar. Resultatet från andra frågeställningen presenterade tre sammanfattande problem från de utförda int, Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet

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When several trains are planned to use the same infrastructure resource, there is always a risk for spreading of delays, which can be hard to recover from. It is a challenge for the Infrastructure Manager to make timetables that accommodate as much traffic as possible, without causing bad on-time performance. Timetable planners are in need of quantitative indicators to assess timetable robustness and accurate methods for how to make the timetable more robust. In this paper we assess the robustness for single-track lines with non-periodic timetables. At single-track lines, trains use the line for running in both directions and the trains can only pass or overtake each other at passing loops. This makes the system more sensitive for delays. In this paper we present a robustness indicator which captures the dependencies between trains at a single-track line. The indicator can be used to illustrate weaknesses in a timetable and also to indicate where and how to insert more robustness. In a simulation study, we show that it is possible to improve the performance by making small timetable adjustments according the indicator, without increasing runtimes or capacity utilization.

The purpose of this paper is to provide insights into how supply chain management canbe taught using megagames as a pedagogical motor. This study has had a longitudinalaction research approach to student centred learning as it builds on a previous paper onintroducing a theme of cross-functional decision-making through combining lectures,case assignment, and computer-based tools. Combining case work and the megagame hasled to activity independence and room for new reflections. What can be seen is thatexchanging the computer-based tool for a megagame has allowed students a deeperunderstanding of not only decision-making, but also decision-formulation.

This paper explores opportunities for information systems to support emergency response to multiple natural hazards. Interviews were conducted with 12 representatives from actors of the Swedish emergency response system about response to multiple natural hazards. Challenges and needs connected to five themes influencing the response effort were identified: Cooperation, Resource management, Command and control, Common operational picture, and Risk management. The results illuminate a lack of technology to support decisions and analyses during emergency response to both single and multiple natural hazards. Based on this, the paper suggests and discusses information systems and decision support tools to assist in satisfying the identified needs. The findings can inform policy makers in emergency response of where to concentrate the development of collaborative preparedness and response work, and the scientific community of future research directions., Funding agencies: This research is part of the project EMMUNE, funded by the Swedish Civil Contingencies Agency (MSB) and FORMAS, a Swedish research council for sustainable development.

This paper explores opportunities for information systems to support emergency response to multiple natural hazards. Interviews were conducted with 12 representatives from actors of the Swedish emergency response system about response to multiple natural hazards. Challenges and needs connected to five themes influencing the response effort were identified: Cooperation, Resource management, Command and control, Common operational picture, and Risk management. The results illuminate a lack of technology to support decisions and analyses during emergency response to both single and multiple natural hazards. Based on this, the paper suggests and discusses information systems and decision support tools to assist in satisfying the identified needs. The findings can inform policy makers in emergency response of where to concentrate the development of collaborative preparedness and response work, and the scientific community of future research directions., Funding agencies: This research is part of the project EMMUNE, funded by the Swedish Civil Contingencies Agency (MSB) and FORMAS, a Swedish research council for sustainable development.

This paper explores opportunities for information systems to support emergency response to multiple natural hazards. Interviews were conducted with 12 representatives from actors of the Swedish emergency response system about response to multiple natural hazards. Challenges and needs connected to five themes influencing the response effort were identified: Cooperation, Resource management, Command and control, Common operational picture, and Risk management. The results illuminate a lack of technology to support decisions and analyses during emergency response to both single and multiple natural hazards. Based on this, the paper suggests and discusses information systems and decision support tools to assist in satisfying the identified needs. The findings can inform policy makers in emergency response of where to concentrate the development of collaborative preparedness and response work, and the scientific community of future research directions., Funding agencies: This research is part of the project EMMUNE, funded by the Swedish Civil Contingencies Agency (MSB) and FORMAS, a Swedish research council for sustainable development.

This paper explores opportunities for information systems to support emergency response to multiple natural hazards. Interviews were conducted with 12 representatives from actors of the Swedish emergency response system about response to multiple natural hazards. Challenges and needs connected to five themes influencing the response effort were identified: Cooperation, Resource management, Command and control, Common operational picture, and Risk management. The results illuminate a lack of technology to support decisions and analyses during emergency response to both single and multiple natural hazards. Based on this, the paper suggests and discusses information systems and decision support tools to assist in satisfying the identified needs. The findings can inform policy makers in emergency response of where to concentrate the development of collaborative preparedness and response work, and the scientific community of future research directions., Funding agencies: This research is part of the project EMMUNE, funded by the Swedish Civil Contingencies Agency (MSB) and FORMAS, a Swedish research council for sustainable development.

This paper explores opportunities for information systems to support emergency response to multiple natural hazards. Interviews were conducted with 12 representatives from actors of the Swedish emergency response system about response to multiple natural hazards. Challenges and needs connected to five themes influencing the response effort were identified: Cooperation, Resource management, Command and control, Common operational picture, and Risk management. The results illuminate a lack of technology to support decisions and analyses during emergency response to both single and multiple natural hazards. Based on this, the paper suggests and discusses information systems and decision support tools to assist in satisfying the identified needs. The findings can inform policy makers in emergency response of where to concentrate the development of collaborative preparedness and response work, and the scientific community of future research directions., Funding agencies: This research is part of the project EMMUNE, funded by the Swedish Civil Contingencies Agency (MSB) and FORMAS, a Swedish research council for sustainable development.

Due to high demand and capacity consumption, railway timetables are often sensitive to disturbances. To maintain punctual operations, it is important that timetables are robust, and methods are needed that make them robust without consuming too much capacity. In this paper, we demonstrate how a policy change in the form of new timetable planning rules can be used to achieve more robust timetables. We present the use of the rules in a real-world case from 2019, when our rules were applied for the Swedish Southern mainline. In this paper, we describe how a new policy for scheduling trains can be applied, and we discuss implications observed when going from research to practice. We also describe how the proposed rules affect train paths and runtimes. The outcome of the rules is measured in a comprehensive evaluation of the traffic performance based on empirical operational data. The results from this study show that practical knowledge is necessary when developing a policy, as well as when developing a timetabling model. Insights, given to us by experienced timetable planners, can be used to enhance optimisation models and make the models more applicable in the real world. The main contribution of this paper is to show that it is possible to increase timetable robustness with a minor policy change based on previously presented research results. Even with relatively small timetable modifications, we can learn from the operational data that the new rules had the intended effect and that overall punctuality can be increased., Funding Agencies|Trafikverket (The Swedish Transport Administration)

Recognition of spatio-temporal traffic patterns at the network-wide level plays an important role in data-driven intelligent transport systems (ITS) and is a basis for applications such as short-term prediction and scenario-based traffic management. Common practice in the transport literature is to rely on well-known general unsupervised machine-learning methods (e.g., k-means, hierarchical, spectral, DBSCAN) to select the most representative structure and number of day-types based solely on internal evaluation indices. These are easy to calculate but are limited since they only use information in the clustered dataset itself. In addition, the quality of clustering should ideally be demonstrated by external validation criteria, by expert assessment or the performance in its intended application. The main contribution of this paper is to test and compare the common practice of internal validation with external validation criteria represented by the application to short-term prediction, which also serves as a proxy for more general traffic management applications. When compared to external evaluation using short-term prediction, internal evaluation methods have a tendency to underestimate the number of representative day-types needed for the application. Additionally, the paper investigates the impact of using dimensionality reduction. By using just 0.1% of the original dataset dimensions, very similar clustering and prediction performance can be achieved, with up to 20 times lower computational costs, depending on the clustering method. K-means and agglomerative clustering may be the most scalable methods, using up to 60 times fewer computational resources for very similar prediction performance to the p-median clustering.

This paper presents a novel mathematical model, integrating timetabling and vehicle scheduling problems for electric buses. The objective is to minimize the number of buses while satisfying constraints concerning routing and charging, including design choices for where to install charging stations. The aim of the paper is to illustrate and discuss the effects of solving the timetabling and vehicle scheduling of electric buses (including where to install charging infrastructure) separately, compared to solving them jointly in one single step. For that purpose, we perform tests with: i) given timetable, that is, solving only the vehicle scheduling problem, ii) fixed headways for each line, and iii) variable headways. A small test case based on actual bus lines from Va center dot stra Fro center dot lunda, Gothenburg, Sweden, is used. From the numerical experiments, we verify that combining the two planning steps can significantly reduce the number of vehicles needed., Funding Agencies|Swedish Energy Agency [40377-1]

Policymakers must find efficient public transport solutions to promote sustainability and provide efficient urban mobility in the course of urban growth. A growing number of research papers are applying Geographically weighted regression (GWR) to model the relationship between public transport demand and its influential factors. However, few studies have considered the rapid development of journey inference from ticket transaction data. Similarly, the potential of GWR to analyze spatio-temporal changes that reflect changes in transportation supply and thus provide a measure for evaluating the local success of transport supply changes has yet to be exploited. In this paper, we use inferred journeys from smart card inferences as the dependent variable and analyze how public transport demand responds to a set of explanatory variables, emphasizing transport supply. Consequently, GWR and its successor Multiscale Geographically Weighted Regression (MGWR) are applied to analyze the spatially varying impact of transport supply changes for seven consecutive time frames between autumn 2017 and spring 2020, allowing conclusions about local changes in transport demand, as well as the benchmarking of transport supply changes. The (M)GWR frameworks predictive power is evaluated by training the model with past transport supply data and testing the model with data from the following consecutive years. The conducted analyses reveal that the (M)GWR model, using inferred journeys and transport supply data, can retrospectively predict the impact of transport supply changes on travel behavior and thus provides conclusions about the success of transport policies., Funding Agencies|Linkoping University

On-site activities are typically performed when the end-product is immovable once it has been assembled and/or due to weight and space constraints in the production and transportation system. It is primarily a customer order driven type of production with a high level of customization. However, some customer order driven and/or customization activities can, or should, be performed off-site, but these aspects are typically treated in isolation of each other. There is therefore a need to make a combined assessment of on-site activities, customer order driven production, and customization activities. The purpose of this paper is thus to develop a typology that provides a holistic view of on-site activities in relation to customer order driven and customization activities. A flow-based three-dimensional typology is developed to assess combinations of three dimensions: flow driver, flow differentiation, and flow location. The property of each dimension is determined using decoupling points. The typology represents how on-site activities impact the feasibility of customer order driven and customization activities. “On-site” is defined as pursuing activities at the site where the final delivery is made. The findings show that forecast driven activities are risky to perform on-site and these should instead be performed before delivery to the site (off-site). The typology is applied to three case companies to illustrate its applicability to building construction. Future studies should extend the typology application to other types of construction and ETO industries to enable benchmarking of site-based production to other contexts with similar challenges related to on-site/off-site production.

To simulate bicycle traffic accurately, it is essential to capture how bicyclists react to features of the infrastructure such as the longitudinal gradient of a bicycle path. Bicycling requires human-powered motion, and the power output provided by bicyclists differ significantly among bicyclists due to physical capabilities and preferences. Therefore, the objective of this paper is to investigate the connection between power output and gradient in bicycle traffic, with the purpose of developing a power-based model that predicts accurately the speed of bicyclists. Based on trajectory data of free-riding bicyclists travelling on a non-flat bicycle path segment, we estimate changes in power output as a function of gradient considering the physical forces acting on a bicycle. The results suggest a linear correlation between power output and gradient; while bicyclists increase their power output on the uphill as gradient increases, they decrease their power output on the downhill as gradient increases. By implementing this correlation into a traffic simulation algorithm, we show that the simulation captures well the impact of gradients in a population of bicyclists as it reproduces similar speed profiles. We conclude that bicyclists adapt their power output to compensate for the gradient and its associated change in speed, and that the impact of gradient varies greatly among bicyclists. Furthermore, we conclude that power-based modelling of free-riding bicyclists is an attractive alternative to investigate further.

Due to high demand and capacity consumption, railway timetables are often sensitive to disturbances. To maintain punctual operations, it is important that timetables are robust, and methods are needed that make them robust without consuming too much capacity. In this paper, we demonstrate how a policy change in the form of new timetable planning rules can be used to achieve more robust timetables. We present the use of the rules in a real-world case from 2019, when our rules were applied for the Swedish Southern mainline. In this paper, we describe how a new policy for scheduling trains can be applied, and we discuss implications observed when going from research to practice. We also describe how the proposed rules affect train paths and runtimes. The outcome of the rules is measured in a comprehensive evaluation of the traffic performance based on empirical operational data. The results from this study show that practical knowledge is necessary when developing a policy, as well as when developing a timetabling model. Insights, given to us by experienced timetable planners, can be used to enhance optimisation models and make the models more applicable in the real world. The main contribution of this paper is to show that it is possible to increase timetable robustness with a minor policy change based on previously presented research results. Even with relatively small timetable modifications, we can learn from the operational data that the new rules had the intended effect and that overall punctuality can be increased., Funding Agencies|Trafikverket (The Swedish Transport Administration)

Recognition of spatio-temporal traffic patterns at the network-wide level plays an important role in data-driven intelligent transport systems (ITS) and is a basis for applications such as short-term prediction and scenario-based traffic management. Common practice in the transport literature is to rely on well-known general unsupervised machine-learning methods (e.g., k-means, hierarchical, spectral, DBSCAN) to select the most representative structure and number of day-types based solely on internal evaluation indices. These are easy to calculate but are limited since they only use information in the clustered dataset itself. In addition, the quality of clustering should ideally be demonstrated by external validation criteria, by expert assessment or the performance in its intended application. The main contribution of this paper is to test and compare the common practice of internal validation with external validation criteria represented by the application to short-term prediction, which also serves as a proxy for more general traffic management applications. When compared to external evaluation using short-term prediction, internal evaluation methods have a tendency to underestimate the number of representative day-types needed for the application. Additionally, the paper investigates the impact of using dimensionality reduction. By using just 0.1% of the original dataset dimensions, very similar clustering and prediction performance can be achieved, with up to 20 times lower computational costs, depending on the clustering method. K-means and agglomerative clustering may be the most scalable methods, using up to 60 times fewer computational resources for very similar prediction performance to the p-median clustering.

Recognition of spatio-temporal traffic patterns at the network-wide level plays an important role in data-driven intelligent transport systems (ITS) and is a basis for applications such as short-term prediction and scenario-based traffic management. Common practice in the transport literature is to rely on well-known general unsupervised machine-learning methods (e.g., k-means, hierarchical, spectral, DBSCAN) to select the most representative structure and number of day-types based solely on internal evaluation indices. These are easy to calculate but are limited since they only use information in the clustered dataset itself. In addition, the quality of clustering should ideally be demonstrated by external validation criteria, by expert assessment or the performance in its intended application. The main contribution of this paper is to test and compare the common practice of internal validation with external validation criteria represented by the application to short-term prediction, which also serves as a proxy for more general traffic management applications. When compared to external evaluation using short-term prediction, internal evaluation methods have a tendency to underestimate the number of representative day-types needed for the application. Additionally, the paper investigates the impact of using dimensionality reduction. By using just 0.1% of the original dataset dimensions, very similar clustering and prediction performance can be achieved, with up to 20 times lower computational costs, depending on the clustering method. K-means and agglomerative clustering may be the most scalable methods, using up to 60 times fewer computational resources for very similar prediction performance to the p-median clustering.

Due to high demand and capacity consumption, railway timetables are often sensitive to disturbances. To maintain punctual operations, it is important that timetables are robust, and methods are needed that make them robust without consuming too much capacity. In this paper, we demonstrate how a policy change in the form of new timetable planning rules can be used to achieve more robust timetables. We present the use of the rules in a real-world case from 2019, when our rules were applied for the Swedish Southern mainline. In this paper, we describe how a new policy for scheduling trains can be applied, and we discuss implications observed when going from research to practice. We also describe how the proposed rules affect train paths and runtimes. The outcome of the rules is measured in a comprehensive evaluation of the traffic performance based on empirical operational data. The results from this study show that practical knowledge is necessary when developing a policy, as well as when developing a timetabling model. Insights, given to us by experienced timetable planners, can be used to enhance optimisation models and make the models more applicable in the real world. The main contribution of this paper is to show that it is possible to increase timetable robustness with a minor policy change based on previously presented research results. Even with relatively small timetable modifications, we can learn from the operational data that the new rules had the intended effect and that overall punctuality can be increased., Funding Agencies|Trafikverket (The Swedish Transport Administration)

This study is about rescheduling freight trains to reduce the eff ects of major interruptions. In this paper, we consider that the interruption is an unexpected marshallingyard closure. We develop a macroscopic Mixed-Integer Linear Programming (MILP)model to reschedule railway timetables. One important principle is that we simultaneously reschedule several trains, instead of one-by-one. Furthermore, we consider arescheduling strategy of letting trains wait on the way when the destination yard havea closure. The model considers stopping restrictions and the capacity of each segmentand station. The order of the trains aff ected by the interruption is not fi xed. We presentexperimental results of three diff erent cases, which are all based on artifi cial data.

This study is about rescheduling freight trains to reduce the effects of major interruptions. In this paper, we consider that the interruption is an unexpected marshalling-yard closure. We develop a macroscopic Mixed-Integer Linear Programming (MILP) model to reschedule railway timetables. One important principle is that we simultaneously reschedule several trains, instead of one-by-one. Furthermore, we consider a rescheduling strategy of letting trains wait on the way when the destination yard have a closure. The model considers stopping restrictions and the capacity of each segment and station. The order of the trains affected by the interruption is not fixed. We present experimental results of three different cases, which are all based on artificial data.

Spiral Galaxies is a pencil-and-paper puzzle played on a grid of unit squares: given a set of points called centers, the goal is to partition the grid into polyominoes such that each polyomino contains exactly one center and is 180 degrees rotationally symmetric about its center. We show that this puzzle is NP-complete, ASP-complete, and #P-complete even if (a) all solutions to the puzzle have rectangles for polyominoes; or (b) the polyominoes are required to be rectangles and all solutions to the puzzle have just 1 x 1, 1 x 3, and 3 x 1 rectangles. The proof for the latter variant also implies NP/ASP/#P-completeness of finding a noncrossing perfect matching in distance-2 grid graphs where edges connect vertices of Euclidean distance 2. Moreover, we prove NP-completeness of the design problem of minimizing the number of centers such that there exists a set of galaxies that exactly cover a given shape.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Spiral Galaxies is a pencil-and-paper puzzle played on a grid of unit squares: given a set of points called centers, the goal is to partition the grid into polyominoes such that each polyomino contains exactly one center and is 180 degrees rotationally symmetric about its center. We show that this puzzle is NP-complete, ASP-complete, and #P-complete even if (a) all solutions to the puzzle have rectangles for polyominoes; or (b) the polyominoes are required to be rectangles and all solutions to the puzzle have just 1 x 1, 1 x 3, and 3 x 1 rectangles. The proof for the latter variant also implies NP/ASP/#P-completeness of finding a noncrossing perfect matching in distance-2 grid graphs where edges connect vertices of Euclidean distance 2. Moreover, we prove NP-completeness of the design problem of minimizing the number of centers such that there exists a set of galaxies that exactly cover a given shape.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Spiral Galaxies is a pencil-and-paper puzzle played on a grid of unit squares: given a set of points called centers, the goal is to partition the grid into polyominoes such that each polyomino contains exactly one center and is 180 degrees rotationally symmetric about its center. We show that this puzzle is NP-complete, ASP-complete, and #P-complete even if (a) all solutions to the puzzle have rectangles for polyominoes; or (b) the polyominoes are required to be rectangles and all solutions to the puzzle have just 1 x 1, 1 x 3, and 3 x 1 rectangles. The proof for the latter variant also implies NP/ASP/#P-completeness of finding a noncrossing perfect matching in distance-2 grid graphs where edges connect vertices of Euclidean distance 2. Moreover, we prove NP-completeness of the design problem of minimizing the number of centers such that there exists a set of galaxies that exactly cover a given shape.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Spiral Galaxies is a pencil-and-paper puzzle played on a grid of unit squares: given a set of points called centers, the goal is to partition the grid into polyominoes such that each polyomino contains exactly one center and is 180 degrees rotationally symmetric about its center. We show that this puzzle is NP-complete, ASP-complete, and #P-complete even if (a) all solutions to the puzzle have rectangles for polyominoes; or (b) the polyominoes are required to be rectangles and all solutions to the puzzle have just 1 x 1, 1 x 3, and 3 x 1 rectangles. The proof for the latter variant also implies NP/ASP/#P-completeness of finding a noncrossing perfect matching in distance-2 grid graphs where edges connect vertices of Euclidean distance 2. Moreover, we prove NP-completeness of the design problem of minimizing the number of centers such that there exists a set of galaxies that exactly cover a given shape.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Spiral Galaxies is a pencil-and-paper puzzle played on a grid of unit squares: given a set of points called centers, the goal is to partition the grid into polyominoes such that each polyomino contains exactly one center and is 180 degrees rotationally symmetric about its center. We show that this puzzle is NP-complete, ASP-complete, and #P-complete even if (a) all solutions to the puzzle have rectangles for polyominoes; or (b) the polyominoes are required to be rectangles and all solutions to the puzzle have just 1 x 1, 1 x 3, and 3 x 1 rectangles. The proof for the latter variant also implies NP/ASP/#P-completeness of finding a noncrossing perfect matching in distance-2 grid graphs where edges connect vertices of Euclidean distance 2. Moreover, we prove NP-completeness of the design problem of minimizing the number of centers such that there exists a set of galaxies that exactly cover a given shape.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Specific Operations Risk Assessment (SORA) is a qualitative methodology for assessing risks of drone operations. In this paper, SORA is compared to and complemented with quantitative estimations of the risk (earlier called HFRM: High-fidelity risk modeling). We highlight intrinsic shortcomings of both SORA and HFRM, and show how HFRM may help to deal with SORA’s ambiguities. (We do not have a recipe to remedy HFRM’s drawbacks with the help of SORA, but suggest a possible regulatory fix to HFRM, addressing its deficiency.) With its focus on ground risk, this paper complements the works of TU Dresden which suggested integrating “agent simulation as air risk assessment in SORA” [Fricke et al., ATM Seminar 2021] and of SESAR’s ER4 BUBBLES project “proposing a quantitative risk analysis which enhances or replaces the qualitative model of SORA” (also for the air risk) [BUBBLES Deliverable 4.1]; we also connect to CORUS observations on SORA shortcomings and use U-space services for addressing them. Our work advocates for stricter regulations, including digitalization and automation not only in definitions, but also in mandates/requirements. Our arguments are illustrated on simple synthetic cases and on real-world experimental examples from urban areas.

This paper explores tradeoffs between ground impact and efficiency of drone flights in urban scenarios. We give an algorithm which produces a set of routes with different lengths and varying number of people affected by the drone. We also present an interactive online visualization tool allowing the user to modify flightpaths in order to explore routing options. Our path finder and the GUI are implemented for a metropolitan area of Norrköping municipality in Sweden. The methods studied in this paper may give UTM service provider the tools to negotiate flightplans which will be acceptable by both the regulator and the drone operator.

Introduction. The ongoing urbanization trend makes local governments densify their built environment, hence stimulating construction and renovation works in urban areas. Construction intrinsically strongly relies on logistics activities, which in turn are the source of environmental nuisances. The latter are referred to as external costs when they are not borne by the polluter himself, such as greenhouse gas emissions, air pollution, congestion, etc. Accurate external cost calculations require accurate data to consider significant calculation-variables. However, current calculations are often based on the number of vehicles used and on transported volume rather than vehicle- or tonne-kilometres, hence not adequate to conduct external cost calculations. Methods. The MIMIC-project1 aims to reduce the impact of construction logistics. Therefore, an integrated impact assessment framework will be developed, assessing the economic and environmental influence of different off-site construction logistics solutions. The necessary data to conduct such an impact assessment are however not always available, complicating calculations. This paper highlights the current gap in accurate data on urban construction logistics flows, the considerable uncertainty about existing figures on construction transport and their methodology, and presents the data availability issue in the development of such a framework, using empirical research. Results. Logistics flows data are typically scattered amongst different actors and various in format. Harmonizing different data categories and sources to feed the framework with relevant logistics variables, this paper presents what is possible to calculate using available data in 4 pilot cases in Belgium, Sweden, Norway and Austria. The various data sources highlight the complexity to develop a framework flexible enough to cope with specific local constraints, whilst generic enough to allow comparability across the European cases, and ultimately acro

The challenge of how cities can be designed and developed in an inclusive and sustainable direction is monumental. Smart city technologies currently offer the most promising solution for long-term sustainability. However, smart city projects have been criticised for ignoring diverse needs of the local population and increasing social divides. A sustainable urban environment depends as much on creating an inclusive space that is safe, accessible and comfortable for a diverse group of citizens as it does on deploying "smart" technologies for energy efficiency or environmental protection. This is because citizens will be more likely to adopt technologies promoting sustainability if they are well-aligned with their lived needs and experiences. In this paper, we present the rationale behind an ongoing interdisciplinary research project that aims to address exactly the problem outlined above by using a participatory design approach. Focusing on a smart city test site in Sweden where sensors are currently being deployed to collect data on noise, particles, vehicle numbers and types (amongst other), the goal is to bring local residents and government representatives into dialogue with technical developers by adopting a "meet-in-the-middle" approach. This paper comprises a brief presentation of early findings and a reflection on this approach., Funding Agencies | FORMAS Swedish Research Council Formas; Swedish Research Council for Sustainable Development [2019-01281]

The challenge of how cities can be designed and developed in an inclusive and sustainable direction is monumental. Smart city technologies currently offer the most promising solution for long-term sustainability. However, smart city projects have been criticised for ignoring diverse needs of the local population and increasing social divides. A sustainable urban environment depends as much on creating an inclusive space that is safe, accessible and comfortable for a diverse group of citizens as it does on deploying "smart" technologies for energy efficiency or environmental protection. This is because citizens will be more likely to adopt technologies promoting sustainability if they are well-aligned with their lived needs and experiences. In this paper, we present the rationale behind an ongoing interdisciplinary research project that aims to address exactly the problem outlined above by using a participatory design approach. Focusing on a smart city test site in Sweden where sensors are currently being deployed to collect data on noise, particles, vehicle numbers and types (amongst other), the goal is to bring local residents and government representatives into dialogue with technical developers by adopting a "meet-in-the-middle" approach. This paper comprises a brief presentation of early findings and a reflection on this approach., Funding Agencies | FORMAS Swedish Research Council Formas; Swedish Research Council for Sustainable Development [2019-01281]

The challenge of how cities can be designed and developed in an inclusive and sustainable direction is monumental. Smart city technologies currently offer the most promising solution for long-term sustainability. However, smart city projects have been criticised for ignoring diverse needs of the local population and increasing social divides. A sustainable urban environment depends as much on creating an inclusive space that is safe, accessible and comfortable for a diverse group of citizens as it does on deploying "smart" technologies for energy efficiency or environmental protection. This is because citizens will be more likely to adopt technologies promoting sustainability if they are well-aligned with their lived needs and experiences. In this paper, we present the rationale behind an ongoing interdisciplinary research project that aims to address exactly the problem outlined above by using a participatory design approach. Focusing on a smart city test site in Sweden where sensors are currently being deployed to collect data on noise, particles, vehicle numbers and types (amongst other), the goal is to bring local residents and government representatives into dialogue with technical developers by adopting a "meet-in-the-middle" approach. This paper comprises a brief presentation of early findings and a reflection on this approach., Funding Agencies | FORMAS Swedish Research Council Formas; Swedish Research Council for Sustainable Development [2019-01281]

The challenge of how cities can be designed and developed in an inclusive and sustainable direction is monumental. Smart city technologies currently offer the most promising solution for long-term sustainability. However, smart city projects have been criticised for ignoring diverse needs of the local population and increasing social divides. A sustainable urban environment depends as much on creating an inclusive space that is safe, accessible and comfortable for a diverse group of citizens as it does on deploying "smart" technologies for energy efficiency or environmental protection. This is because citizens will be more likely to adopt technologies promoting sustainability if they are well-aligned with their lived needs and experiences. In this paper, we present the rationale behind an ongoing interdisciplinary research project that aims to address exactly the problem outlined above by using a participatory design approach. Focusing on a smart city test site in Sweden where sensors are currently being deployed to collect data on noise, particles, vehicle numbers and types (amongst other), the goal is to bring local residents and government representatives into dialogue with technical developers by adopting a "meet-in-the-middle" approach. This paper comprises a brief presentation of early findings and a reflection on this approach., Funding Agencies | FORMAS Swedish Research Council Formas; Swedish Research Council for Sustainable Development [2019-01281]

ntroduction. The ongoing urbanization trend makes local governments densify their built environment, hence stimulating construction and renovation works in urban areas. Construction intrinsically strongly relies on logistics activities, which in turn are the source of environmental nuisances. The latter are referred to as external costs when they are not borne by the polluter himself, such as greenhouse gas emissions, air pollution, congestion, etc. Accurate external cost calculations require accurate data to consider significant calculation-variables. However, current calculations are often based on the number of vehicles used and on transported volume rather than vehicle- or tonne-kilometres, hence not adequate to conduct external cost calculations. Methods. The MIMIC-project1 aims to reduce the impact of construction logistics. Therefore, an integrated impact assessment framework will be developed, assessing the economic and environmental influence of different off-site construction logistics solutions. The necessary data to conduct such an impact assessment are however not always available, complicating calculations. This paper highlights the current gap in accurate data on urban construction logistics flows, the considerable uncertainty about existing figures on construction transport and their methodology, and presents the data availability issue in the development of such a framework, using empirical research. Results. Logistics flows data are typically scattered amongst different actors and various in format. Harmonizing different data categories and sources to feed the framework with relevant logistics variables, this paper presents what is possible to calculate using available data in 4 pilot cases in Belgium, Sweden, Norway and Austria. The various data sources highlight the complexity to develop a framework flexible enough to cope with specific local constraints, whilst generic enough to allow comparability across the European cases, and ultimately acros, MIMIC

The challenge of how cities can be designed and developed in an inclusive and sustainable direction is monumental. Smart city technologies currently offer the most promising solution for long-term sustainability. However, smart city projects have been criticised for ignoring diverse needs of the local population and increasing social divides. A sustainable urban environment depends as much on creating an inclusive space that is safe, accessible and comfortable for a diverse group of citizens as it does on deploying "smart" technologies for energy efficiency or environmental protection. This is because citizens will be more likely to adopt technologies promoting sustainability if they are well-aligned with their lived needs and experiences. In this paper, we present the rationale behind an ongoing interdisciplinary research project that aims to address exactly the problem outlined above by using a participatory design approach. Focusing on a smart city test site in Sweden where sensors are currently being deployed to collect data on noise, particles, vehicle numbers and types (amongst other), the goal is to bring local residents and government representatives into dialogue with technical developers by adopting a "meet-in-the-middle" approach. This paper comprises a brief presentation of early findings and a reflection on this approach., Funding Agencies | FORMAS Swedish Research Council Formas; Swedish Research Council for Sustainable Development [2019-01281]

Evacuation preparedness includes ensuring proper infrastructure, resources and planning for moving people from a dangerous area to safety. This is especially important and challenging during mass gatherings, such as large concerts. In this paper, we present the Emergency Exit Layout Problem (EELP) which is the problem of locating a given number of emergency exits and deciding their width such that the time it takes to evacuate the crowd from an arena is minimized. The EELP takes into account the geography of the arena and its surroundings, as well as the number of pedestrians in the crowd and the distribution of these within the arena. The EELP is formulated as a two-stage stochastic mixed integer linear program to handle the uncertainty related to the location of the possible incidents and the distribution of the pedestrians. Two cases are studied, a large concert planned at the Leangen trotting track in Trondheim and a smaller indoor arena. For each case, the EELP is solved for different scenarios, and the suggested layouts are evaluated using an agent-based simulation model. In particular, the potential of incorporating detailed assessment regarding the location and probability of specific incidents and the distribution of pedestrians are investigated. The computational study shows that making a more detailed risk assessment has little effect on the large concert, but a significant impact on the location of the emergency exits for the smaller indoor case. The results also indicate that it is more important to consider the location and probability of specific incidents rather than the pedestrian distribution., Funding Agencies|We would like to thank the Norwegian Research Council for funding part of the research through the AXIOM project, and the Swedish Contingencies Agency for funding part of the project through the Center for advanced research in emergency response (CARER). W; Norwegian Research Council; Swedish Contingencies Agency; Center for advanced research in emergency response (CARER)

Historically, the paper market has consisted of few customers with high demands. However, the market has changed and nowadays it consists of many customer with lower demands, which causes problems in the warehouse process of Braviken Papermill. The main problem is that the utilization rates in the storage bays are low due to the relatively large bays compared to the order quantities. The purpose of this project is to develop a new set of bays that fits the current market and increases the utilization rates. The goal of the new set is to decrease the amount of manual operations and instead use the full potential of the allocation system. The new set of bays consist of four bay types, dimensioned for 2, 4, 8 and 16 reel stacks respectively. Several experiments are done, and the new set of bays performs better than the current one, in terms of the utilization rates for storage events in the bays. The average utilization rate is significantly higher for the new set compared to the current. A decrease in effective storage space can be compensated by an increased degree of utilization. Also, it is beneficial with more and smaller bays in a market situation like the one of Holmen Paper.

Historically, the paper market has consisted of few customers with high demands. However, the market has changed and nowadays it consists of many customer with lower demands, which causes problems in the warehouse process of Braviken Papermill. The main problem is that the utilization rates in the storage bays are low due to the relatively large bays compared to the order quantities. The purpose of this project is to develop a new set of bays that fits the current market and increases the utilization rates. The goal of the new set is to decrease the amount of manual operations and instead use the full potential of the allocation system. The new set of bays consist of four bay types, dimensioned for 2, 4, 8 and 16 reel stacks respectively. Several experiments are done, and the new set of bays performs better than the current one, in terms of the utilization rates for storage events in the bays. The average utilization rate is significantly higher for the new set compared to the current. A decrease in effective storage space can be compensated by an increased degree of utilization. Also, it is beneficial with more and smaller bays in a market situation like the one of Holmen Paper.

Construction Logistics has recently emerged as an important consideration forIndustrialized House Building (IHB). Previous research has demonstrated that construction logistics improves IHB through: the clarification of interfaces along the supply chain; increased supply chain efficiency; more productive construction sites; the transfer of value-adding activities from site to the supply chain; and the integration of site and supply chain. IHB research has commonly focused on buildings as product, their technical design and production, as well as the processof these activities. IHB companies seek the integration ofthese two aspects. However, there is growing realization of the value ofintegrating the supply chainthrough a focus on logistics. This paper argues that in order to achieve atripartiteintegrationof product, process, and logistics,thatfirst an overarching company-level logistics strategy is required.Astrategic perspectiveenables a separation of high-level logistics decisions from those that are operational in nature, in the same way that product platforms have assisted IHB. This separation iscritical in overcoming the peculiarities of construction. This authorsidentifydesign-thinkingas a powerful tool to assist in the future implementation of logistics strategy in order todrive the creation of contextually specificlogisticssolutions.Two company case studies from Sweden revealtwo distinct forms of logistics strategy.Thesecase studies, through comparative analysis, show how logistics strategies for IHB might emerge asdesign-led ‘logistics platforms’thatutilize theprinciples of standardization, modularity, and re-usability in order to achieve the flexibility demanded byconstruction. This paper proposes that a focus onIHBlogistics strategyas a platform be implemented to allow effective integration of construction’ssupply chain. The result of this approach is a re-usable,continually improving platform forconstruction logistics that can co-ordinate differing produ

This is the second article in a suite of articles investigating relations between Stackel-type systems and Painleve-type systems. In this paper, we construct isomonodromic Lax representations for Painleve-type systems found in the previous paper by Frobenius integrable deformations of Stackel-type systems. We first construct isomonodromic Lax representations for Painleve-type systems in the so-called magnetic representation and then, using a multitime-dependent canonical transformation, we also construct isomonodromic Lax representations for Painleve-type systems in the nonmagnetic representation. Thus, we prove that the Frobenius integrable systems constructed in Part I are indeed of Painleve-type. We also present isomonodromic Lax representations for all one-, two-, and three-dimensional Painleve-type systems originating in our scheme. Based on these results we propose complete hierarchies of that follow from our construction.

This is the second article in a suite of articles investigating relations between Stackel-type systems and Painleve-type systems. In this paper, we construct isomonodromic Lax representations for Painleve-type systems found in the previous paper by Frobenius integrable deformations of Stackel-type systems. We first construct isomonodromic Lax representations for Painleve-type systems in the so-called magnetic representation and then, using a multitime-dependent canonical transformation, we also construct isomonodromic Lax representations for Painleve-type systems in the nonmagnetic representation. Thus, we prove that the Frobenius integrable systems constructed in Part I are indeed of Painleve-type. We also present isomonodromic Lax representations for all one-, two-, and three-dimensional Painleve-type systems originating in our scheme. Based on these results we propose complete hierarchies of that follow from our construction.

Software-Defined Networking (SDN) architecture was developed to address the shortcomings of traditional network architectures. It allows system administrators to easily manage and configure the network by separating and abstracting the control plane from the data plane. All the knowledge and intelligence of SDN is concentrated in a software entity called the SDN controller, making the network programmable. However, a large-scale SDN architecture, particularly in the IoT domain, requires the implementation of a physically distributed control mechanism. Such a mechanism, based on the East/West interface raises many challenges in terms of scalability, reliability, security, consistency, and traceability. The development of the Blockchain allows addressing some of these challenges. In this paper, we present a design using Blockchain technology to improve SDNs in terms of trackability and discuss the adaptations required for large-scale deployment. Experimental results clearly show that the use of a proof-of-authority consensus algorithm in combination with a Merkle tree approach reduces the impact in terms of latency as well as in terms of Gas consumption.

Purpose Contingency studies within logistics and supply chain management have shown a need for longitudinal studies on fit. The purpose of this paper is to investigate the logistics strategy from a process of establishing fit perspective. Design/methodology/approach A large Swedish building contractor's logistics strategy process was analysed using a longitudinal single-case study for a period of 11 years (2008–2019). Findings The case study reveals three main constraints to logistics strategy implementation: a dominant purchasing organisation, a lack of incentives and diverging top-management priorities. This suggests that logistics strategy fit is not a conscious choice determined by contextual factors. Research limitations/implications Establishing fit is a continuous cycle of regaining fit between the logistics context and logistics strategy components. Fit can be achieved by a change to the logistics context or to logistics strategy components. Practical implications Logistics managers may need to opt for satisfactory fit in view of the costs incurred by changing strategy versus the benefits to be gained from a higher degree of fit. Originality/value This paper adopts a longitudinal case design to study the fit between the logistics context and strategy, adding to the body of knowledge on organisational design and strategy in logistics and supply chain management., Funding: Development Fund of the Swedish Construction Industry (SBUF); Lars Erik Lundberg Foundation for Research and Education; [13843]

Global warming exceeding 1.5°C above pre-industrial levels will very likely lead to unavoidable increases of several climate hazards in the coming decades. Climate change phenomena can increase the risk of several extreme weather events, leading to risks of what is commonly considered as natural hazards, for instance landslides and forest fires. These chains or networks of events are termed natural multi-hazards or compound natural events, referring to a primary event or a driver that directly triggers or increases the probability of one or more secondary events by changing the environment. The very likely increase of single and compound natural hazards due to climate change require increased attention since it may imply new challenges to emergency response systems and new threats to society. Especially, how emergency response systems can prepare for and respond to these hazards by using knowledge of the interactions between different natural events. The purpose of this thesis is to increase the knowledge on interactions between natural hazards, investigate how multiple natural hazards lead to challenges for emergency response systems, and how these challenges can be addressed. The purpose can be further divided into three objectives: (i) to identify relevant multiple natural hazards in a Swedish context, (ii) to identify planning and decision-making challenges these hazards may imply for emergency response systems, and (iii) to develop a decision support tool addressing one of these challenges. The objectives have been addressed in three sub-studies, one for each of the objectives, leading to the production of four papers. The first sub-study focused on the first objective and resulted in the construction of a national natural hazard interaction framework for Sweden, which is presented in Paper 1. The second sub-study focused on the second objective, leading to the identification of needs for information, planning, and decision support systems in the Swedish e, Funding agencies: Swedish Civil Contingencies Agency, and FORMAS, a Swedish research council for sustainable development.

This is the second article in a suite of articles investigating relations between Stackel-type systems and Painleve-type systems. In this paper, we construct isomonodromic Lax representations for Painleve-type systems found in the previous paper by Frobenius integrable deformations of Stackel-type systems. We first construct isomonodromic Lax representations for Painleve-type systems in the so-called magnetic representation and then, using a multitime-dependent canonical transformation, we also construct isomonodromic Lax representations for Painleve-type systems in the nonmagnetic representation. Thus, we prove that the Frobenius integrable systems constructed in Part I are indeed of Painleve-type. We also present isomonodromic Lax representations for all one-, two-, and three-dimensional Painleve-type systems originating in our scheme. Based on these results we propose complete hierarchies of that follow from our construction.

This is the second article in a suite of articles investigating relations between Stackel-type systems and Painleve-type systems. In this paper, we construct isomonodromic Lax representations for Painleve-type systems found in the previous paper by Frobenius integrable deformations of Stackel-type systems. We first construct isomonodromic Lax representations for Painleve-type systems in the so-called magnetic representation and then, using a multitime-dependent canonical transformation, we also construct isomonodromic Lax representations for Painleve-type systems in the nonmagnetic representation. Thus, we prove that the Frobenius integrable systems constructed in Part I are indeed of Painleve-type. We also present isomonodromic Lax representations for all one-, two-, and three-dimensional Painleve-type systems originating in our scheme. Based on these results we propose complete hierarchies of that follow from our construction.

This is the second article in a suite of articles investigating relations between Stackel-type systems and Painleve-type systems. In this paper, we construct isomonodromic Lax representations for Painleve-type systems found in the previous paper by Frobenius integrable deformations of Stackel-type systems. We first construct isomonodromic Lax representations for Painleve-type systems in the so-called magnetic representation and then, using a multitime-dependent canonical transformation, we also construct isomonodromic Lax representations for Painleve-type systems in the nonmagnetic representation. Thus, we prove that the Frobenius integrable systems constructed in Part I are indeed of Painleve-type. We also present isomonodromic Lax representations for all one-, two-, and three-dimensional Painleve-type systems originating in our scheme. Based on these results we propose complete hierarchies of that follow from our construction.

In this paper we develop two methods for the use of mobile phone data to support the estimation of long-distance mode choice models. Both methods are based on logit formulations in which we define likelihood functions and use maximum likelihood estimation. Mobile phone data consists of information about a sequence of antennae that have detected each phone, so the mode choice is not actually observed. In the first trip-based method, the mode of each trip is inferred by a separate procedure, and the estimation process is then straightforward. However, since it is not always possible to determine the mode choice with certainty (although it is possible in the majority of cases), this method might give biased results. In our second antenna-based method we therefore base the likelihood function on the sequences of antennae that have detected the phones. The estimation aims at finding a parameter vector in the mode choice model that would explain the observed sequences best. The main challenge with the antenna-based method is the need for detailed resolution of the available data. In this paper we show the derivation of the two methods, that they coincide in case of certainty about the chosen mode and discuss the validity of assumptions and their advantages and disadvantages. Furthermore, we apply the first trip-based method to empirical data and compare the results of two different ways of implementing it.

Purpose This paper explores the operationalization of production network coordination - the production transfer (PT) - and the relationships between transfer risk sources, preventive actions, supply chain disruptions, corrective actions and losses to better understand how to mitigate the risk and achieve an effective transfer process. Design/methodology/approach A longitudinal field study of a PT process from Norway to Spain was studied in depth for 25 months. Findings The paper presents the implications of three areas of importance for PT success: (1) how the transfer influences the plant roles, (2) the cross-locational management of the transfer project at the sender and receiver and (3) whether adapting the transferred production to the receivers environment is an enabler or an inhibitor of transfer success. Practical implications The findings about how to mitigate the transfer risk and the frameworks of risk sources, supply chain disruptions, losses and preventive and corrective actions, along with the examples from the in-depth study, can aid the practitioners in managing PTs and achieving the relocation goals. Originality/value This is one of the first studies of PT, which is from the perspective of both transfer parties, and addresses both preventive and corrective actions and all the transfer phases. Moreover, this study addresses the operational aspects of production network coordination, which received limited attention in earlier research., Funding Agencies|Research Council of Norway