Publikationer från Linköpings universitet
Not a member yet
58266 research outputs found
Sort by
From balance to breach: cyber threats to battery energy storage systems
No full textBattery energy storage systems are an important part of modern power systems as a solution to maintain grid balance. However, such systems are often remotely managed using cloud-based control systems. This exposes them to cyberattacks that could result in catastrophic consequences for the electrical grid and the connected infrastructure. This paper takes a step towards advancing understanding of these systems and investigates the effects of cyberattacks targeting them. We propose a reference model for an electrical grid cloud-controlled load-balancing system connected to remote battery energy storage systems. The reference model is evaluated from a cybersecurity perspective by implementing and simulating various cyberattacks. The results reveal the system’s attack surface and demonstrate the impact of cyberattacks that can critically threaten the security and stability of the electrical grid
Fragments of Identity in Liquid Modernity : Gender, Identity, and Resistance to Norms on Social Media
No full textSamhället är idag präglat av individualisering, globalisering och digitalisering. Det är en annan värld idag än förr och ungdomar möter nya utmaningar i formandet av identitet. Denna studie ämnar undersöka hur ungdomar på TikTok förhåller sig till sin identitet i relation till rådande normer, moderna valmöjligheter och den maktpåverkan sociala medier innebär, med ett särskilt fokus på personer som beskriver sig som afab [assigned female at birth]. Genom en tematisk analys av videor och kommentarer på TikTok utifrån begrepp och perspektiv från Bauman, Rosa, Giddens och Goffman ämnar vi synliggöra hur samhällsutvecklingen bidrar till en upplevelse av identitet som flytande och förändringsbar. I resultatet framkommer en livssituation präglad av osäkerhet och otrygghet, där individerna tampas med de samhälleliga normernas påfrestningar samt synliggörs den maktpåverkan kreatörer på TikTok besitter.
Social Workers' Attitudes Towards Legal Requirements and Guidelines Regarding the Right to Financial Aid : A Quantitative Survey Study
No full textSyftet med studien var att undersöka socialarbetares attityder till lagkrav och riktlinjer för rätten till ekonomiskt bistånd. Inspiration till denna studie uppkom från politiska debatter och media som uppmärksammat brister och utmaningar med ekonomiskt bistånd i vårt nutida samhälle. Kritiken från dessa forum skapade en nyfikenhet kring vad socialarbetare själva har för upplevelser av lagkrav och riktlinjer som styr deras bedömningar av en persons rätt till ekonomiskt bistånd. En webbenkät skapades därför för att nå ut till urvalet som bestod av socialarbetare från olika kommuner i de tre landsdelarna; Götaland, Svealand och Norrland. Respondenterna av webbenkäten bestod av 118 socialarbetare som är aktiva inom sektorn för ekonomiskt bistånd. Vidare analyserades studiens resultat med hjälp av Rawls social kontraktsteori med fokus på rättviseprinciper; belyste diskrepansen mellan attityderna till lagkrav och riktlinjer. Gällande forskningsresultaten visade det på delade meningar vid jämförelser med den tidigare forskning. Studiens resultat visade att socialarbetare hade en positiv attityd till riktlinjer för rätten till ekonomiskt bistånd utifrån de svar respondenterna angav i enkäten. Dock var socialarbetare mer negativt inställda till lagkraven för rätten till ekonomiskt bistånd, alltså höll flertalet respondenter inte med om påståendena som behandlade lagkrav i enkäten. Resultatet visade också att socialarbetares attityder varierade beroende på vilken landsdel de arbetade inom. I exempelvis Norrland var attityderna mer negativa till riktlinjer än i Götaland och Svealand. Slutligen visade studien att det finns ett samband mellan arbetslivserfarenhet och attityd till riktlinjer. Socialarbetare med längre arbetslivserfarenhet hade en mer negativ attityd till riktlinjer medan socialarbetare med kortare arbetslivserfarenhet hade en mer positiv attityd till riktlinjer. The purpose of the study was to investigate social workers' attitudes towards legal requirements and guidelines for the right to financial assistance. Inspiration for this study arose from political debates and media that drew attention to shortcomings and challenges with financial assistance in our contemporary society. The criticism from these forums created a curiosity about what social workers themselves experience of legal requirements and guidelines that guide their assessments of a person's right to financial assistance. An online survey was therefore created to reach the sample consisting of social workers from different municipalities in the three regions of the country; Götaland, Svealand and Norrland. The respondents to the online survey consisted of 118 social workers who are active in the financial assistance sector. Furthermore, the results of the study were analyzed using Rawls' social contract theory with a focus on principles of justice; highlighting the discrepancy between the attitudes towards legal requirements and guidelines. Regarding the research results, it showed divided opinions when compared with previous research. The results of the study showed that social workers had a positive attitude towards guidelines for the right to financial assistance based on the answers given by the respondents in the questionnaire. However, social workers were more negatively disposed towards the legal requirements for the right to financial assistance, i.e. the majority of respondents did not agree with the statements that dealt with legal requirements in the questionnaire. The results also showed that social workers' attitudes varied depending on which part of the country they worked in. For example, in Norrland, attitudes were more negative towards guidelines than in Götaland and Svealand; the respondents' answers could differ depending on which part of the country they worked in. Finally, the study showed that there is a relationship between work experience and attitude towards guidelines. Social workers with longer work experience had a more negative attitude towards guidelines, while social workers with shorter work experience had a more positive attitude towards guidelines
Personalized Analysis of Left Atrial Blood Flow through Computational Modeling
No full textIn this thesis, the atrial blood flow was modeled using computational fluid dynamics (CFD) to better understand atrial hemodynamics and blood stasis. Atrial hemodynamics and especially stasis are of interest since thrombi can form in the left atrium, travel with the blood stream to the brain, and cause strokes. To model atrial blood flow in a personalized manner, several modeling assumptions and choices need to be made, for example how to model the motion of the atrial wall. There are different approaches to estimate stasis; however, there is no standard method. While it is known that in patients with atrial fibrillation (AF), the stroke risk is increased, the exact mechanisms for this are not fully understood, especially in patients that are in sinus rhythm most of the time. One approach to reduce the stroke risk is to occlude the left atrial appendage (LAA). However, this has not been evaluated for patients in an early phase of AF. The aim of this thesis was to enhance our understanding of left atrial hemodynamics. For this, the blood flow in the left atrium was simulated using CFD based on time-resolved CT images, including the patient-specific geometry and wall motion. In this thesis, different stasis markers are investigated and a new method to quantify atrial hemodynamics was developed, splitting the atrial blood flow into 6 components. Additionally, virtual LAA occlusion was investigated to see how it impacts atrial hemodynamics during sinus rhythm. In this thesis, the atrial blood flow and stasis in 21 paroxysmal AF patients during sinus rhythm were compared to 8 controls. The wall motion tracked from time-resolved CT that was used in the CFD simulations showed similar flow rates as measurements from 4D flow MRI. All stasis markers investigated showed higher stasis in AF patients during sinus rhythm compared to the controls. Atrial flow component analysis revealed how blood travels through the left atrium. In the control group, the blood flow was dominated by components characterizing a direct path through the LA. In the patients with AF, however, an increased amount of blood stays in the LA for more than two heart beats and more blood flows back to the lungs. Virtual LAAO showed a reduction of stasis, for some individuals to similar levels as the control group. For others, stasis was reduced but still high, and stasis was located close to the occlusion device. This could indicate an increased risk for device-related thrombi. In conclusion, this thesis contributes to our understanding of the atrial blood flow. Using CT-based CFD simulations, we could show that stasis is increased in AF patients during sinus rhythm. In the future, adding patient-specific stasis assessment could improve decision-making to prescribe anticoagulants and thus reduce the incidence of cardioembolic strokes.Funding agencies: The Center for Medical Image Science and Visualization (CMIV) at Linköping University, the Swedish Research Council, the Swedish Heart and Lung Foundation, Sweden’s Innovation Agency Vinnova, County Council of Östergötland, Henry och Ella Ståhls Foundation, Konung Gustaf V:s och Drottning Victorias StiftelseThe computations were enabled by resources provided by the National Academic Infrastructure for Supercomputing in Sweden (NAISS), the Swedish National Infrastructure for Computing (SNIC), partially funded by the Swedish Research Council through grant agreement no. 2022-06725, and by the National Supercomputer Centre (NSC), funded by Linköping University.</p
Holding the harasser responsible: Implications of identifying sexual harassment that includes abuse of power and quid pro quo elements as sexual corruption
No full textThis article argues that a perpetrator-based definition of sexual harassment that highlights corrupt aspects of sexual harassment may contribute to a shift in focus from the experience of the harassed, to the actions of the harasser. This argument is based on an analysis of testimonies of sexual harassment from the #metoo call by the Swedish police in 2017, which reference abuse of power and quid pro quo elements. By introducing the recently developed analytical framework of 'sexual corruption', we show how a perpetrator-based definition of sexual harassment may contribute to attributing responsibility to harassers. Identifying sexual harassment that includes the abuse of power and quid pro quo elements as corruption centers on the role of the abuse of power and, thus, the responsibility of the person abusing their position of power. Moreover, this shift bypasses discussions of whether or not the situation was experienced as 'unwelcome' by the harassed, the severity of the act, and questions of coercion and consent. Identifying instances of sexual harassment that include the abuse of power and quid pro quo elements as corruption also closes off attempts to portray it in terms of 'jokes' or banter, which is common in the police context. The article contributes with analytical tools that enable a shift from tracing the experience of the harassed to centering on the actions and responsibility of the harasser.Funding Agencies|Swedish Crime Victim Fund; Forte The Swedish Research Council for Health, Working Life and Welfare</p
Upper secondary school students’ perspectives on un/fairness in group work assessment
No full textStudents' perspectives of un/fairness in group work assessment are known to be related to the issues of varied contributions in group work and how to discern each student's contribution or knowledge from the group's joint work. Students' perceptions of un/fairness in group work assessment are important since it relates to their motivation. This study aims to investigate upper secondary students' perspectives on un/fairness in group work assessment. In the study, 129 upper secondary school students in Sweden between the ages of 15 and 16 years participated. The students were interviewed in 33 focus groups. The interviews were thematically analysed. The study's findings illustrate how ambition, motivation and friendship relations in groups may vary and cause what students perceive as unfairness. Varied ambitions and motivations among group members also appear to breed situations where group members' contributions to group work may vary, which also is perceived by students as unfair. Other factors that can contribute to a perception of unfairness are when knowledge levels vary among group members or friendship relations. How un/fairness is perceived also depends on the level at which the assessment is implemented, group or individual level. The greatest experience of unfairness is generated by implementing group assessment.Funding Agencies|Swedish Research Council [VR 721 2012-5476]</p
Rapport avseende förslag om inrättande av utbildningsvetenskaplig fakultet
No full textI denna rapport föreslås Linköpings universitet att inrätta en Utbildningsvetenskaplig fakultet. Idag benämns Utbildningsvetenskap (UV) ett område. Förslaget motiveras med att forsknings- och utbildningsverksamheten vid UV vuxit avsevärt det senaste decenniet och håller mycket god kvalitet. Verksamheten står sig väl vid en jämförelse med Utbildningsvetenskapliga fakulteter vid andra lärosäten och UV kan tveklöst betraktas som en av landets ledande utbildningsvetenskapliga miljöer. Konkret innebär förslaget att: • LiU manifesterar UVs status som en av landets ledande utbildningsskapligamiljöer avseende forskning, grundutbildning och samverkan • det inrättas en egen anställningsnämnd med ansvar för rekryteringar • den Utbildningsvetenskapliga fakulteten ges samma status som övrigafakulteter vid LiU i officiella och ceremoniella sammanhang och ges möjlighetatt utse hedersdoktorer Syftet är att detta dokument ska utgöra ett kunskapsunderlag till den utredare somutses av rektor
Noise propagation in linear stationary iterations
No full textWe consider a stationary iteration for solving a linear system of arbitrary order. The method includes, e.g. Kaczmarz iteration, the Landweber iteration and the SOR (Gauss-Seidel) iteration. A study of the behavior of the iterates, both theoretically and experimentally, is performed. In particular we compare the behavior with and without noise in the data. The results give insight into the interplay between noise free and noisy iterates. For comparision we also included a Krylov type method CGLS in the experiments. As expected CGLS works well for noise free data but also tends to amplify the noise faster than the other methods, thus making it more critical when to stop the iterations.Funding Agencies|Linkping University</p
Integrated optimisation of multi-pass cutting parameters and tool path with hierarchical reinforcement learning towards green manufacturing
No full textFive-axis machining, especially flank milling, is popular in machining thin-walled freeform surface parts with high energy consumption. Reducing the machining energy consumption is paramount for advancing green manufacturing. Therefore, this paper proposes an energy-efficient integration optimisation of cutting parameters and tool path with hierarchical reinforcement learning (HRL). Firstly, a novel multi-pass machining energy consumption model is developed with cutting and path parameters, based on which the integrated optimisation problem is modelled considering a dynamic workpiece deformation constraint. Secondly, HRL with a Soft Actor Critic agent (HSAC) decouples the model into two Markov Decision Processes at different timescales. The higherlayer plans cutting parameters for each pass on a macro timescale, while the micro-timescale lower-layer performs multiple tool path expansions with the planned cutting parameters, and provides feedback to the higher layer. By hierarchical optimisation and non-hierarchical interaction, the model is efficiently solved. Moreover, curriculum transfer learning is applied to expedite task completion of the lower layer, enhancing interaction efficiency between the two layers. Experiments show that, compared with two benchmarks, the proposed method improves machining energy consumption by 35.02 % and 30.92 %, and reduces machining time by 38.57 % and 27.17 %, providing a promising paradigm of green practices for thin-walled freeform parts and the broader manufacturing industry.Funding Agencies|National Natural Science Foundation of China [51975463, 52105530]; Young Talent Fund of the Shaanxi University Association for Science and Technology [20210409]; China Postdoctoral Science Foundation [2021M692556]; China Scholarship Council [202206280173]</p
Unlearning the child: An ontological politics outlook
No full textThis article examines how we as researchers in a constantly changing world can challenge ourselves by 'unlearning' what we know, and perhaps take for granted, about children. What happens, for example, to the notion of the child in a world of transformation? To address these questions, I argue that we need to explore the act of unlearning both imagined and 'real' children. The act of unlearning encourages confusion, uncertainty, courage, and changes of mind as a way of learning anew. Through explorations of empirical examples from research with and about children, issues such as the no-where child, the now-here child, agency, numerical age, vulnerability, and competence are discussed. The analyses do not offer a coherent alternative. The purpose is rather to shake things up and create openings and possibilities