Högskolebiblioteket i Halmstad Publikationer
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Kontrollerad inbromsning av spindelmotor
No full textMålet är att utveckla ett säkerhetsprogram som möjliggör kontrollerad inbromsning av en spindelmotor som används i en CNC-maskin. Syftet var att säkerställa en säker inbromsning vid hastighetsavvikelser större än ±3 procent från en fördefinieradhastighetsprofil, samt att på ett tillförlitligt sätt detektera dessa avvikelser. Arbetet fokuserade på att analysera begränsningarna i den befintliga hårdvarukonfigurationen. Matematiska modeller användes för att uppskatta den kinetiska energi som omvandlas till värme vid olika bromsperioder för de olika verktygen fräs, borr och såg. Mätningar av bromsenergi gjordes både genom externa och interna oscilloskop under testkörningar. Resultaten visade att systemets maximala bromseffekt begränsades av motorn. Den snabbaste möjliga bromstid fastställdes till 1,2 sekunder för motor samt fräsverktyg och 0,1 sekunder för borren. Slutsatsen från arbetet var att den begränsande faktorn i hårdvarukonfigurationen inte var maxeffekten utan snarare den logik i frekvensomriktarens som inte kan bearbeta strömmen på kortare tid. Eftersom studien möjliggör en kontrollerad inbromsning samt en metodik för att styra hastighetsprofilerna för de olika verktygen, bidrar detta till en förbättrad arbetsmiljö runt maskinen.The goal is to develop a safety program that can control the braking of a spindle motor used in a CNC machine. The purpose was to guarantee safe braking in case of speed deviations greater than ±3 percent from a predefined speed profile, as well as to reliably detect these deviations. The work focuses on analyzing the limitations of the existing hardware configuration. Mathematical models are used to estimate the kinetic energy that is converted into heat at different braking periods for the different tools milling, drilling and sawing. Measurements of braking energy were made both through external and internal oscilloscopes during test runs. The results showed that the maximum braking power of the system was limited by the engine. The fastest possible braking time was determined to be 1.2 seconds for the motor and milling tool and 0.1 seconds for the drill. The conclusion from the work was that the limiting factor in the hardware configuration was not the maximum power, but rather the logic of the frequency converter that cannot process the current in a shorter time. As the studies assume a controlled braking and a methodology to control the speed profiles of the various tools, this contributes to an improved working environment around the machine
The carryback problem : Exploring how geometrical solution can solve the carryback with EDEM
No full textThis thesis investigates the issue of material residue in Volvo Construction Equipment´s A40 dumper by exploring parameters that affect how material gets stuck in the dumper, then later implementing geometrical solutions to reduce this issue. Since full-scale testing and experimenting would be impossible due to costs and time limitations the majority of tests were done through DEM calculations using the DEM simulation software EDEM, with the chosen material for this project being clay. With Volvo aiming to transition to produce only fully electrical dumpers by 2040, current heat-based solutions using exhaust pipes will no longer be viable, thus alternative solutions must be pursued. Initially the project focused on small scale physical experiments, with the aim to create a better understanding how moisture affects clays cohesive and adhesive properties and also be able to use potential findings in later simulations. However, due to scaling and material compaction limitations the project moved on to full scale simulations instead. A realistic baseline simulation of the A40 dumper was developed, modeling cohesive clay material by adjusting different parameters such as particle size, surface energy and plasticity to reflect the correct material behavior. Based on a real-world case from a customer of Volvo where wear plates were implemented on an A60 dumper which in turn led to a reduced carryback, several geometrical implementations of plates to the A40 were simulated. The geometrical changes included adding plates to the side walls, front part and the ramp at the rear of the dumper, where each area was simulated separately to identify each plate’s impact on the carryback. Each implementation was evaluated for its impact on the amount and location of carryback, allowing for a systematic study of how geometry affects flow behavior and material detachment during the unloading process. The customer inspired design was further improved using the optimized angles found during the different angle studies, resulting in a significant reduction in carryback mass. It is expected that these changes can improve the already beneficial design of the customer dumper and reinforced the claim that smoother geometry and fewer sharp corners can help to prevent material buildup. The results suggest that DEM simulations can serve as a valuable tool for virtually exploring dumper design alternatives, offering insight into carryback behavior and the influence of key parameters. While this method allows for early evaluation of potential geometry changes their alignment with manufacturing constraints, it cannot by itself lead to design optimization. Instead, the findings should be seen as an initial step toward understanding the problem and lays the groundwork for future design improvements. Ultimately, this study contributes to Volvo’s longterm efforts toward fossil-free and efficient construction machinery
Cyberbrottens pussel : Rekonstruktion av cyberangrepp
No full textWhich piece do you start with in a puzzle without an end? The aim of this study was to investigate whether the analysis of cybercrime can be streamlined using moderntechnologies and tools. A quantitative experimental method was employed, analyzing an existing dataset. Through both manual analysis and language model-based processing, the study examined which digital traces are most useful for reconstructing cyberattacks. The results showed that certain artifacts could be linked to specific attacks. The language models demonstrated varying capabilities in analysis and filtering tasks, ranging from high accuracy to an inability to perform the analysis. The conclusion drawn is that timeline reconstruction can be made more efficient through careful selection of artifacts and adaptation to the nature of the attack. AI models can support the analytical process, but they still require human oversight and must be aligned with forensic standards. The study highlights both the potential and limitation of current technologies and emphasizes the need for continued research in this field. Particularly important is the development of robust frameworks to ensure data integrity and legal defensibility in automated analyses. The hope is that future innovations will reduce the workload for IT forensics professionals while improving the reliability of cybercrime investigations
Young adults in the gig economy : A qualitative study on working conditions, well-being and future prospects
No full textDenna kandidatuppsats undersöker unga vuxnas erfarenheter av gig-arbete i Sverige, med fokus på motivation, välbefinnande och framtidstro. I takt med att traditionella anställningsformer ersätts av tillfälliga uppdrag förändras villkoren för arbete.Studien bygger på femton semistrukturerade intervjuer med gig-arbetare i åldern 18-30inom olika branscher. Med hjälp av tematisk analys (Braun & Clarke, 2006) samt SelfDetermination Theory och Bourdieus fältteori identifieras centrala teman i deltagarnas berättelser. Resultaten visar en dubbel verklighet: många uppskattar friheten och flexibiliteten i gig-arbete, men den bristande tryggheten påverkar deras välbefinnande och framtidstro negativt. Uppsatsen belyser behovet av att kombinera flexibilitet med tryggare strukturer för att främja ett hållbart arbetsliv för unga i gig-ekonomin. Young Adults’ Experiences of Gig-Work - Motivation, Well-Being, and the Struggle for StabilityThis bachelor’s thesis examines young adults’ experiences of working in the gig economy in Sweden, focusing on motivation, well-being, and future outlook. As gig work becomes more common and traditional employment forms are replaced by short-term assignments, new conditions for work are emerging.The study is based on fifteen semi-structured interviews with gig workers aged 18–30 across various industries. Using thematic analysis (Braun & Clarke, 2006) and supported by Self-Determination Theory and Bourdieu’s field theory, the study identifies key themes in the participants’ experiences. Findings highlight a dual reality: while many appreciate the flexibility and autonomy of gig work, the lack of security negatively affects wellbeing and future prospects. The thesis stresses the importance of combining flexibility with more stable structures to support sustainable working conditions for young people in the gig economy
Föräldra- och tränarbeteende som prediktorer för psykologisk trygghet och psykologiskt välbefinnande hos unga idrottare
No full textThe aim of the present study was to test part of Vella et al. (2024) socioecological model examining whether parental and coaching behaviors predict psychological safety and whether psychological safety, in turn, predicts psychological well-being among young athletes aged 16-22 (M=17.96, SD=1.85). A survey was administered to 100 participants from both team and individual sports, and the relationships were analyzed using regression. The results showed that coaching behavior accounted for 34% of the variance in perceived psychological safety, whereas parental behavior explained 19.3%. Furthermore, psychological safety accounted for 26.4% of the variance in the athletes’ psychological well-being. The measurement instruments used in the study have previously demonstrated high reliability and validity: parental behavior was assessed with the Youth Sport Parental Support Questionnaire (YSPS-Q), coaching behavior with the Coaching Behaviour Scale for Sport (CBS-S), psychological safety with the Sport Psychological Safety Inventory (SPSI), and psychological well-being with the Eudaimonic Well-being in Sport Scale (EXBSS). The analysis indicated that bothcoaches’ and parents’ actions play a significant role in athletes’ experience of psychological safety, which is in turn linked to their psychological well-being. Supportive behaviors from both groups were associated with an increased sense of security, with coaching behavior exhibiting a slightly stronger association than parental behavior. However, it is important to note that although these actors contribute substantially to shaping psychological safety, they cannot fully explain the complexity of the phenomenon. Moreover, the study suggests that perceived safety has a moderate link to athletes’ psychological well-being, implying that other factors may also be relevant. These findings are consistent with Vella et al. (2024), who emphasize that psychological safety co-varies with both coaching and parental behaviors, and that these relationships are central to the mental health of young athletes.Syftet med föreliggande studie var att testa en del av Vella et al. (2024) socioekologiska modell för att undersöka om föräldrabeteende och tränarbeteende predicerar psykologisk trygghet och om psykologisk trygghet predicerar psykologiskt välbefinnande hos unga idrottare i åldern 16-22 år (M=17.96, SD=1.85). Genom en enkätstudie med 100 deltagande idrottare från både lag- och individuella sporter, analyserades sambanden med hjälp av regressionsanalyser. Resultaten visade att tränarbeteende förklarade 34% av variationen i den upplevda psykologiska tryggheten, medan föräldrabeteende stod för 19,3%. Vidare förklarade psykologisk trygghet 26,4% av variationen i idrottarnas psykologiska välbefinnande. Mätinstrumenten som användes har tidigare visat hög reliabilitet och validitet. Föräldrabeteende mättes med Youth Sport Parental Support Questionnaire (YSPS-Q), tränarbeteende mättes med Coaching Behaviour Scale for Sport (CBS-S), psykologisk trygghet mättes med Sport Psychological Safety Inventory (SPSI), och psykologiskt välbefinnande mättes med Eudaimonic Well-being in Sport Scale (EXBSS). Analysen visade att både tränare och föräldrars agerande spelar en markant roll i idrottares upplevelse av psykologisk trygghet, vilket i sin tur är kopplat till deras psykologiska välbefinnande. Stödjande beteende från båda dessa grupper var förknippade med en ökad känsla av trygghet, där tränarens insatser framträdde med en något större effekt jämfört med föräldrarnas. Det är emellertid viktigt att notera att även om dessa aktörer bidrar väsentligt till att forma den psykologiska tryggheten, kan de inte ensam förklara hela komplexiteten i fenomenet. Vidare indikerar studien att den upplevda tryggheten har en måttligt koppling till idrottarnas psykologiska välbefinnande, vilket tyder på att även andra faktorer kan vara relevanta. Resultaten överensstämmer med Vella et al. (2024), som framhåller att psykologisk trygghet samvarierar med beteenden från både tränare och föräldrar, och att dessa relationer är centrala i sammanhanget för unga idrottare.
Test Track Development for a Solar Car
No full textThis thesis details the design, construction, and testing of a test rig for the Halmstad University solar car. In the current era, there is an increasing demand for sustainable modes of transportation. Solar cars represent a significant potential for sustainable transportation. The participating universities aim to construct their solar vehicle and determine which institution has built the most effective one through participation in the Bridgestone World Solar Challenge. Since operating a solar car on public roads is not permitted in all countries, test rigs can be utilized for indoor testing. This thesis will comprehensively explain the process of creating a test rig and a detailed analysis of the most suitable components and materials for its construction. Firstly, the sequence of steps followed to develop the frame will be explicated in the method section. Several literature reviews will be conducted in the theoretical section of the thesis. These will cover the following topics: existing design methods, finite element analysis, bearings, braking systems, and welding techniques. These studies should provide insight into the current landscape of the various subjects. They should enhance understanding of the genesis of choices of particular components/techniques for the frame development. After this, a discussion of the results will be conducted. The final test rig was designed following a series of iteration processes following the generative cycle delineated in the method. The design incorporates several key components, which are described here. The frame comprises steel box sections, consisting of a readily weldable material capable of withstanding the forces exerted upon it. The utilisation of gas welding in the assembly process is predicated on the economic efficiency of this technique. The front wheels of the solar car will be fastened with tensioning straps in the designated spaces, while the driven rear wheel will ride on two rollers mounted along both sides in a bearing with a bearing housing. Roller bearings are selected for their ability to withstand high speeds and forces. The rollers are composed of aluminium, a material chosen for its low weight and inertia. The simulation of road resistance is realized by using eddy current brakes, which function on the principle of a counteracting magnetic field. The operation of these brakes is non-contact, a factor that confers a significant advantage in terms of wear. Last, a critical review will be outlined regarding this thesis's collaboration, sustainability, social, economic, and environmental aspects
Challenges in smart home usage: Focusing on end user experience and energy consumption
No full textSmart home technologies and their associated energy optimization solutions have the potential to significantly reduce energy consumption. However, various challenges prevent some current and prospective users from fully engaging with these technologies, thereby limiting their effectiveness in promoting energy efficiency. This thesis examines the concept of smart homes, user interactions with these technologies, and the challenges that hinder their adoption and use. The primary objective is to identify and analyze the obstacles that prevent end users from utilizing energy optimization features effectively. By gaining a comprehensive understanding of these challenges, this research aims to contribute to the development of more accessible and user-friendly smart home solutions that facilitate energy savings and carbon footprint reduction.Smarta hem teknologi och deras associerade energioptimering lösningar har potentialen att drastiskt reducera energikonsumtionen. Dock finns det olika utmaningar som hindrar några nuvarande och potentiella användare från att fullt engagera sig med dessa teknologier, därigenom begränsas deras effektivitet vid främjande av effektivt energianvändande. Denna uppsats undersöker konceptet av smart homes, användarinteraktioner med dessa teknologier, och utmaningarna som hindrar deras fulla tillämpning och användning. Det primära målet är att identifiera och analysera de utmaningar som förhindrar slutanvändare från att utnyttja energioptimering lösningar effektivt. Genom att förskaffa en omfattande förståelse av dessa utmaningar, är denna uppsats syfte att bidra till utvecklingen av mer tillgängliga och användarvänliga smart home lösningar som faciliterar energisparande och minskningen av koldioxidutsläpp
Den fysiska klassrumsmiljöns påverkan på elevers läsning : En studie om lärares syn på den fysiska klassrumsmiljön och dess betydelse för elevers läsning
No full textIn recent years, several national and international assessments have indicated a downward trend in students’ reading abilities, highlighting the importance of investigating factors that can promote reading. This study aims to explore how the physical classroom environment influences students’ reading motivation and engagement in grades F–3. The problem formulation stems from a desire to understand which aspects of the physical classroom environment may affect students’ reading, as well as how teachers can intentionally design the environment to enhance students’ motivation. The study adopts a pedagogical perspective and is based on Vischer’s (2007) theoretical framework Environment Comfort, where physical environment, functionality, and psychological impact serve as analytical concepts. Data collection was carried out through semi-structured interviews with eight active teachers from two schools. The analysis, inspired by thematic analysis, shows that classrooms offering accessible and varied book choices, flexible seating arrangements, and safe, inspiring reading spaces have a positive impact on students’ engagement in reading. The teacher’s role as a reading role model and as a guide in the design of reading environments emerges as particularly important. The results also show that small changes in the classroom environment can have significant effects on both students’ motivation and concentration. The study’s conclusions emphasize the importance of consciously designing the classroom environment to support students’ reading. Furthermore, the significance of viewing the classroom environment as an active and integrated part of the educational practice is highlighted
Remote Operation of Electrically Power-Assisted Cycles : Implementation of V2X Communication for EPACs
No full textThis thesis investigated the development of a real-time wireless data transmissionsystem for electrically power-assisted cycles using vehicle-to-everything communication in combination with controller area network bus integration. The mainobjective was to design a prototype capable of transmitting structured and authenticated data, such as unique identifiers, from an external control unit to acycle without affecting its normal operation. A prototype was implemented using two microcontrollers, a Raspberry Pi Pico andan ESP32, a controller area network transceiver module, and a wireless router.The system was designed to operate over a Wi-Fi network and enable one-way,low-latency data transmission from the control unit to the cycle. The softwareand hardware were developed to ensure compatibility, real-time performance, andfault tolerance. Initial testing confirmed that the system established a stable wireless connection,transmitted structured data packets, and logged timestamped messages for latency analysis. The measured latency met the requirements for non-critical realtime applications. Additional testing was planned to evaluate performance acrosslonger distances and in more complex environments. This work demonstrated the technical feasibility of a lightweight and secure wireless communication system for electrically assisted bicycles. The results provideda foundation for future developments such as smart infrastructure interaction,remote diagnostics, and management of bicycle fleets
Automatic brightness adjustment for display and interior illumination : Sensor Data Processing and Perceptual Mapping
No full textThis report focuses on the initial signal processing stages of an automatic brightness control system for vehicle displays, specifically ambient light sensing, filtering, and perceptual brightness mapping, guided by principles of human visual perception. The system replaces fixed day/night behavior with a dynamic, contextaware approach that balances responsiveness and visual comfort. Key techniques include adaptive filtering, hysteresis logic and perceptual mapping based on Stevens’ Power Law. The system applies asymmetric ramping to handle rapidly changing lighting conditions, reacting faster to brightness increases and more gradually when dimming. Manual user adjustments are supported without overriding adaptive behavior. Simulation results indicate smooth and perceptually aligned brightness transitions with reduced output variability compared to conventional methods. Although part of a larger system, this work concentrates on the foundational signal handling and control logic. Further research and real-world testing are recommended before vehicle deployment.Denna rapport behandlar utvecklingen och simuleringen av ett automatiskt ljusstyrningssystem för fordonsdisplayer med fokus på de inledande signalbehandlingsstegen. Arbetet omfattar omgivningsljusavkänning, signalfiltrering och perceptuell ljusstyrkemappning baserat på principer från den mänskliga ljusuppfattningen. Målet är att uppnå en dynamisk och kontextmedveten styrning som ersätter traditionellt statiska dag-/nattlägen samtidigt som visuell komfort och systemrespons optimeras. Systemet använder centrala tekniker såsom adaptiv filtrering, hystereslogik och en logaritmisk mappningsfunktion enligt Stevens lag. För att hantera snabba förändringar i ljusmiljön tillämpas asymmetrisk rampning där ökningar i ljusstyrka behandlas snabbare än minskningar. Det finns även stöd för manuell justering utan att den adaptiva funktionen inaktiveras. Simuleringsresultat visar att systemet genererar mjuka och perceptuellt anpassade ljusstyrkeövergångar med minskad variation jämfört med konventionella metoder. Även om arbetet utgör en del av ett större projekt, ligger fokus i denna rapport på den grundläggande signalhanteringen och styrlogiken. Vidare forskning och tester i verkliga fordonsmiljöer rekommenderas inför praktisk utveckling och implementering