Digital twins are seen as one of the key technologies of Industry 4.0. Although many research groups focus on digital twins and create meaningful outputs, the technology has not yet reached a broad application in the industry. The main reasons for this imbalance are the complexity of the topic, the lack of specialists, and the unawareness of the twin opportunities. The project 'Digital Twin Academy' aims to overcome these barriers by focusing on three actions: Building a digital twin community for discussion and exchange, offering multi-stage training for various knowledge levels, and implementing realworld use cases for deeper insights and guidance. In this work, we focus on creating a flexible learning platform that allows the user to select a training path adjusted to personal knowledge and needs. Therefore, a mix of basic and advanced modules is created and expanded by individual feedback options. The usage of personas supports the selection of the appropriate modules.

Digital Twins are softwarized mirrors of physical systems. They can represent their corresponding physical counterparts in real-world applications and reflect the behavior of the latter under different scenarios with decent accuracy. In this thesis, we consider the case where an application requests data from multiple digital twins, each representing a physical system. The digital twins are hosted on execution servers located between the application and the set of physical devices. Each digital twin has to be periodically updated by its physical system and uses a portion of the execution server’s computing resource to refresh itself. Due to the scarcity of computation resources of the execution servers, in this thesis, we have tackled the problem of optimal digital twin placement onto a limited set of execution servers. We are aiming at minimizing the latency of the digital twins’ responses to the application’s requests while keeping the age of information of served data below a certain threshold. We first formulate the problem as an integer quadratic program (IQP) and then transform it into a semidefinite program (SDP). We prove that the problem is NP-complete and propose polynomial-time approximation algorithms that solve the problem with different trade-offs between the accommodation of the application’s request latency and the achievement of data age targets. / Thesis / Master of Applied Science (MASc)

Heightened awareness of the impact of climate change has led to rapidly increasing penetration of renewable energy resources in electric energy distribution systems. Those distributed energy resources (DERs), mostly inverter-based, can act as resiliency sources for the grid but also introduce new control and stability challenges. In this thesis, a cyber-physical system (CPS) testbed is proposed combining a real-time electro-magnetic transient power system simulation and a practical model for communication network simulation. By regularly updating the CPS testbed with real-world SCADA information, a digital twin is effectively created. The digital twin allows the testing of novel microgrid control and cybersecurity strategies. Simulations using the Virginia Tech Electric Service (VTES) as a test case demonstrate the capability of adequately controlled resources, including solar PV, energy storage, and a synchronous generator, to enhance resilience by providing energy to critical loads. The DERs comply with IEEE disturbance ride-through requirements and switching transients are maintained within acceptable limits. A comprehensive DER-based resiliency plan is developed and validated for the Virginia Tech smart grid. / M.S. / In the last two decades, the increased occurrence of major power outages in the United States underscores the critical need to improve the reliability and resilience of the power grid. Massive investments have been made to install information and communications technology enabling near real-time monitoring and control of the smart grid. Simultaneously, heightened awareness of the impact of climate change led to rapidly increasing penetration of renewable energy resources at the distribution system level. Those distributed energy resources, mostly inverter-based, can act as resiliency sources for the grid but also introduce new control and stability challenges. In this work, a comprehensive testbed is proposed for the real-time simulation of both the power systems and communication networks. This method allows the testing of novel microgrid control and cybersecurity strategies. The testbed is used to develop and validate a resiliency plan for the Virginia Tech Electric Service using distributed energy resources.

Mobile computation offloading (MCO) is a way of improving mobile device (MD) performance by offloading certain task executions to a more resourceful edge server (ES), rather than running them locally on the MD. This thesis first considers the problem of assigning the wireless communication bandwidth and the ES capacity needed for this remote task execution, so that task completion time constraints are satisfied. The objective is to minimize the average power consumption of the MDs, subject to a cost budget constraint on communication and computation resources. The thesis includes contributions for both soft and hard task completion deadline constraints. The soft deadline case aims to create assignments so that the probability of task completion time deadline violation does not exceed a given violation threshold. In the hard deadline case, it creates resource assignments where task completion time deadlines are always satisfied. The problems are first formulated as mixed integer nonlinear programs. Approximate solutions are then obtained by decomposing the problems into a collection of convex subproblems that can be efficiently solved. Results are presented that demonstrate the quality of the proposed solutions, which can achieve near optimum performance over a wide range of system parameters. The thesis then introduces algorithms for static task class partitioning in MCO. The objective is to partition a given set of task classes into two sets that are either executed locally or those classes that are permitted to contend for remote ES execution. The goal is to find the task class partition that gives the minimum mean MD power consumption subject to task completion deadlines. The thesis generates these partitions for both soft and hard task completion deadlines. Two variations of the problem are considered. The first assumes that the wireless and computational capacities are given and the second generates both capacity assignments subject to an additional resource cost budget constraint. Two class ordering methods are introduced, one based on a task latency criterion, and another that first sorts and groups classes based on a mean power consumption criterion and then orders the task classes within each group based on a task completion time criterion. A variety of simulation results are presented that demonstrate the excellent performance of the proposed solutions. The thesis then considers the use of digital twins (DTs) to offload physical system (PS) activity. Each DT periodically communicates with its PS, and uses these updates to implement features that reflect the real behaviour of the device. A given feature can be implemented using different models that create the feature with differing levels of system accuracy. The objective is to maximize the minimum feature accuracy for the requested features by making appropriate model selections subject to wireless channel and ES resource availability. The model selection problem is first formulated as an NP-complete integer program. It is then decomposed into multiple subproblems, each consisting of a modified Knapsack problem. A polynomial-time approximation algorithm is proposed using dynamic programming to solve it efficiently, by violating its constraints by at most a given factor. A generalization of the model selection problem is then given and the thesis proposes an approximation algorithm using dependent rounding to solve it efficiently with guaranteed constraint violations. A variety of simulation results are presented that demonstrate the excellent performance of the proposed solutions. / Thesis / Doctor of Philosophy (PhD) / Mobile devices (MDs) such as smartphones are currently used to run a wide variety of application tasks. An alternative to local task execution is to arrange for some MD tasks to be run on a remote non-mobile edge server (ES). This is referred to as mobile computation offloading (MCO). The work in this thesis studies two important facets of the MCO problem. 1. The first considers the joint effects of communication and computational resource assignment on task completion times. This work optimizes task offloading decisions, subject to task completion time requirements and the cost that one is willing to incur when designing the network. Procedures are proposed whose objective is to minimize average mobile device power consumption, subject to these cost constraints. 2. The second considers the use of digital twins (DTs) as a way of implementing mobile computation offloading. A DT implements features that describe its physical system (PS) using models that are hosted at the ES. A model selection problem is studied, where multiple DTs share the execution services at a common ES. The objective is to optimize the feature accuracy obtained by DTs subject to the communication and computation resource availability. The thesis proposes different approximation and decomposition methods that solve these problems efficiently.

In the domain of social design, this thesis introduces a design project that explores a place-centric view on interaction design to address issues of participation, representation, and place. The project aims to envision possible futures of city-scaled digital twins as places that enable collective engagement within communities and between citizens and cities. It explores this aim with a methodology grounded in co-design- and ethnographic values, focusing on the place of Ringön in Gothenburg. The final design outcome of the study is an augmented reality-based application connected to the city-scaled digital twin of Gothenburg. The application introduces a concept that enables citizens to express location-based social and cultural values and engage in common concerns. It enables the City of Gothenburg to communicate with citizens and develop an enriched understanding of the identity and character of places in Gothenburg. The study hopes to contribute with knowledge to the body of work within social design that explores how sustainable smart cities can develop from a bottom-up perspective, in a more participatory and socially sustainable way.

Ports are actively pursuing greater operational efficiency to effectively handle the increasing global flow of goods, while striving to improve the energy efficiency of their operations to comply with new environmental regulations. As a result, innovation-leading ports have begun to recognize the potential of digital twins to overview, coordinate and optimize port processes, resulting in energy savings, and reductions of costs and of CO2 emissions. While digital twins have gained momentum in other domains such as smart manufacturing and aerospace, their adoption in ports has been comparatively slow. This can be explained, among other things, by the multi-stakeholder nature of the port and the high complexity of the often interconnected port processes. Thus, this thesis, grounded in the context of ports, discusses what constitutes a digital twin, proposes characteristics to assess the maturity of existing digital twins, and introduces and evaluates mathematical models to support a key port process, which can be used as components of a digital twin for the port. The thesis is composed of three papers:  Paper 1 is based on an extensive literature review, through which digital twins among different domains are studied in depth in order to transfer insights from these to the port domain. The resulting discussion of what constitutes a port’s digital twin and the requirements that a port’s digital twin must fulfil, together with a discussion of use cases of how port digital twins can contribute to energy savings, form the basis of Paper 1.  Paper 2 discusses how digital twins’ maturity can be assessed within six maturity levels and presents milestones for their implementation. Notably, Interoperability is identified as the highest maturity level, as the numerous stakeholders and their respective digital twins must work together to reach a coordinated system of systems performance. Using this assessment demonstrates that only a few innovation-leading ports have developed sophisticated digital twinning solutions so far.  Paper 3 is dedicated to coordinating container retrieval with stacking, combining two key port operations. Thus, it can present a key modeling component of a port digital twin, considering jointly the goals of reducing the energy demanding crane movements, as well as keeping schedules tight to avoid port congestion issues. This is directly reflecting the potentially conflicting perspectives of different stakeholders in the port context. The provided optimization model and algorithm show that jointly addressing both problems may lead to a reduced efficiency of both individual objectives, but from a systems perspective, leads to a higher overall port efficiency. / Hamnar strävar aktivt efter ökad operativ effektivitet för att hantera den ökande globala varuflödet, samtidigt som de strävar efter att förbättra energieffektiviteten. Som ett resultat har ledande hamnar börjat se potentialen hos digitala tvillingar för att skapa överblick samt koordinera och optimera processer i hamnen. Målet med användningen av digitala tvillingar är energibesparingar samt minskning av kostnader och CO2-utsläpp. Medan digitala tvillingar har använts inom andra områden såsom tillverknings-, flyg- och rymdindustrin, har införandet i hamnar varit jämförelsevist långsamt. Detta kan förklaras, bland annat, av hamnens många olika involverade aktörer och den höga komplexiteten i de ofta sammanlänkade hamnprocesserna. Därför fokuserar denna avhandling, med utgångspunkt i hamnkontexten, vad som utgör en digital tvilling, presenterar egenskaper för olika mognadsnivåer hos befintliga digitala tvillingar, och introducerar samt utvärderar matematiska modeller som kan bli delkomponenter i en digital tvilling för hamnen. Avhandlingen består av tre artiklar: Artikel 1 bygger på en omfattande litteraturöversikt, inom vilken digitala tvillingar för olika områden studeras ingående för att överföra insikter från dessa till hamndomänen. Detta resulterar i en presentation av vad som utgör en hamns digitala tvilling och de krav som en hamns digitala tvilling måste uppfylla, tillsammans med en diskussion om möjliga sett på vilka hur hamnens digitala tvillingar kan bidra till energibesparingar. Artikel 2 presenterar ett ramverk för hur mognaden hos digitala tvillingar kan bedömas baserat på sex mognadsnivåer och presenterar milstolpar för deras implementering. Noterbart är att interoperabilitet identifieras som den högsta mognadsnivån, eftersom de många intressenterna och deras respektive digitala tvillingar måste koordineras för att nå en fungerande system-av-systemnviå. Genom att använda denna bedömning visar det sig att endast några få innovationsledande hamnar hittills har utvecklat sofistikerade digitala tvillinglösningar. Artikel 3 fokuserar på koordinering av containerupphämtning koordinerat med staplings effektivitet, två viktiga hamnaktivieter. Därför representerar dessa en viktig modelleringskomponent i en hamns digitala tvilling, med beaktande av målen att minska de energikrävande kranrörelse, samt behovet av att hålla planerade tider för att undvika trängsel och väntan. Detta speglar direkt de potentiellt konfliktfyllda perspektiven hos olika intressenter i hamnkontexten. Den utvecklade optimeringsmodellen och algoritmen visar att gemensam hantering av båda dessa problemen kan leda till en minskad effektivitet för de respektive individuella målen, men en ökad effektivitet från ett systemperspektiv för hamnen som helhet.

Digital twins (DT) describe the integration of the physical and digital worlds with the aim of optimizing real world operations and functions. The digital twin concept has gained increasing attention across industries in the past decade including the building sector. However digital twins remain ambiguous with various existing definitions and characteristics. While DTs include all life cycle phases, ultimately their goal is optimization of operations during the use phase. Of the building life cycle phases, building facilities management (FM) is responsible for considerable costs and energy consumption and has potential for improvement through DT implementation. Along with increased building information modeling (BIM) implementation, recent advances in data driven technologies have encouraged the exploration of DT in the building sector. BIM has been coupled with technologies such as internet of things (IoT), data analytics, and cloud computing to optimize various FM functions often resembling DT. This study has reviewed existing literature on digital twins in facilities management using a structured literature review and characterized similar characteristics and definitions by different authors. Additionally, DT implementation in different FM application areas was quantified and analyzed. Results show that DT implementation in FM is still at nascent stages with major challenges surrounding standardization and data integration. / Master of Science / Digital twins (DT) describe the integration of the physical and digital worlds with the aim of optimizing real world operations and functions. The digital twin concept has gained increasing attention across industries in the past decade including the building sector. However digital twins remain ambiguous with various existing definitions and characteristics. DTs include all building life cycle phases from design, construction, to operation and maintenance. Ultimately their goal is optimization of operations also referred to as facilities management during the use phase. Of the building life cycle phases, building facilities management (FM) is responsible for considerable costs and energy consumption and has potential for improvement through DT implementation. Building information modeling (BIM) describes geometric and semantic information of physical assets and has been used to optimize operations in FM. Along with increased BIM implementation, recent advances in data driven technologies have encouraged the exploration of DT in the building sector. BIM has been coupled with technologies such as internet of things (IoT), data analytics, and cloud computing to optimize various FM functions often resembling DT. This study has reviewed existing literature on digital twins in facilities management using a structured literature review and characterized similar characteristics and definitions by different authors. Additionally, DT implementation in different FM application areas was quantified and analyzed. Results show that DT implementation in FM is still at nascent stages with major challenges surrounding standardization and data integration.

KPMG has recognized that large manufacturing corporates in Sweden are experiencing impaired growth possibilities and have therefore started to turn to startups to help with innovation. Corporates have traditionally focused on growth through product improvement or market expansion but have recently started to shift their focus to acquisitions and partnerships with high potential startups. However, since there are many differences between corporates and startups the collaboration can be difficult to handle, especially when it comes to integration. This study aims to investigate what types of startups large corporates are currently looking to collaborate with and to create a practical framework that can act as a guide to increase the chance of successfully integrating a startup into a corporate's operations. This study is a qualitative study that examines several Swedish manufacturing companies by delving into their specific cases. A thematic analysis, document and literature review is presented, and the results indicate that Swedish manufacturing corporates want startups with technologies that boost digital transformation (AI, IoT, digital twins) to increase predictability, traceability, and optimization. They also want to increase sustainability initiatives in terms of both technologies and materials. This is followed by a framework for how a successful corporate-startupintegration should be done. The results from the study contribute to the work of improving collaboration between startups and corporates and the results from this study can help create economic benefits, promote social sustainability, and address environmental challenges more effectively. / KPMG har uppmärksammat att stora tillverkningsföretag i Sverige upplever försämrade tillväxtmöjligheter och har därför börjat vända sig till startups för att få hjälp med innovation. Företag har traditionellt fokuserat på tillväxt genom produktförbättringar eller marknadsexpansion, men har nyligen börjat skifta fokus till förvärv och partnerskap med startups med hög potential. Då det finns stora skillnader mellan stora företag och startups kan samarbetet vara svårt att hantera, särskilt när det gäller integration. Denna studie syftar till att undersöka vilka typer av startups som stora företag vill samarbeta med och att skapa ett praktiskt ramverk som kan fungera som en guide för att öka chansen att framgångsrikt integrera ett startup i företagets verksamhet. Denna studie är en kvalitativ studie som undersöker flera svenska tillverkningsföretag. En tematisk analys, dokument- och litteraturgranskning presenteras, och resultaten indikerar att svenska tillverkningsföretag vill ha startups med teknik som främjar digital transformation (AI, IoT, digitala tvillingar) för att öka förutsägbarhet, spårbarhet och optimering. De vill också öka hållbarhetsinitiativen när det gäller både teknik och material. Detta följs av ett ramverk för hur en framgångsrik integration mellan företag och startups bör gå till. Resultaten från studien bidrar till arbetet med att förbättra samarbetet mellan startups och företag och resultaten från denna studie kan bidra till att skapa ekonomiska fördelar, främja social hållbarhet och hantera miljöutmaningar mer effektivt

The industry has during the past decades been changing towardsdigitalization at a rapid pace, adapting new frameworks and digitalsolutions, with the thrive to improve efficiency, and output quality.This thesis covers how a hyped industry concept, digital twin, incontext of smart manufacturing, could be applied in this changingclimate. Focus is put on what strategies a Product LifecycleManagement (PLM) principal could adapt when approaching theutilization of digital twins, in a customer setting. The research project, using a qualitative exploration format,incorporated a thorough review of journal articles and standards,interconnected with conducted interviews with industry experts, inorder to develop two strategies on how to approach the conceptof digital twins. The two-part strategies were formed on the basis of Mintzberg(1978) emergent and deliberate strategies. The former, consisted ofIDEF0 function modeling diagramming, where a digital twin businessprocess was portrayed, based on the literature review and interviewdata. The latter, approached the digital twin application challenge ina theoretical manner, based on the concept’s high risk anduncertainty, incorporating organizational structure theory andinnovation theory. The two strategies showed two different pathsto approach the digital twin phenomena and how to, boththeoretically and practically, adapt digital twins in a customer setting.

Around the world, people are becoming more sedentary and less physically active. These behaviors are two examples of habits causing lifestyle diseases and premature death. The Health Dialogue (Hälsosamtal) is a method used in Sweden today, which attempts to prevent people from being diagnosed with lifestyle caused diseases. Today, the Health Dialogue does not offer an opportunity to perform follow-up of lifestyle goals created during the Health Dialogue, which is an important missing piece of the method. Follow-up regarding goals can benefit from being combined with digital twin technology, since this type of technology can potentially prevent negative habits by providing personalized predictions of bodily functions. In this thesis, a design prototype was created, combining the Health Dialogue with digital twin technology as an attempt to increase motivation towards a healthier lifestyle. Three hypotheses were proposed and evaluated through a user test containing the created design prototype. The results of the evaluation showed some support for the hypotheses for some participants, but overall, not enough to show support for motivation while using the prototype. However, the design and evaluation method can help in further development of an application that might contribute to motivation of a healthier lifestyle in the future.