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Investigation of ship vulnerability to SGISC based failure modes in different sea areas
No full textThis thesis investigates the vulnerability of ships to dynamic stability failure, as defined
by the Second Generation Intact Stability Criteria (SGISC). The study addresses a
key limitation of SGISC, which uses a standard wave scatter table based on North
Atlantic data. This study aims to investigate the effect of different sea areas on the
applicability of SGISC by using modern hindcast wave data. The studied sea zones
are selected based on high-traffic global shipping routes for cargo and ro-ro passenger
(ropax) vessels and are aligned with zones defined in the Global Wave Statistics
(GWS) database. Level 2 vulnerability assessments are performed for three of the five
stability failure modes within the SGISC: pure loss of stability, parametric rolling, and
excessive acceleration. Four sample ships representing a large and small container
ship, a bulk carrier, and a ropax vessel are studied under multiple loading conditions
and wave environments using NAPA software.
The vulnerability analysis of all failure modes and sample ships revealed that the
standard wave scatter table consistently gave higher vulnerability index values than
the other zones studied. Based on the results, it is concluded that the standard wave
scatter table (Rev.1) is suitable to use as a wave environment input for approving ships
for unrestricted operations. Among all sea areas, the Pacific Ocean zones experienced
the highest vulnerability to cargo ships, whereas Ropax vessels showed the highest
vulnerability in the European sea areas. When comparing all sample ships, the fine-hull
ropax vessel is most vulnerable to parametric rolling and pure loss of stability, whereas
the bulk carrier is most susceptible to excessive acceleration due to its fuller hull form
Simulating the Sawtooth Instability in Tokamak Plasmas Implementation in the European Transport Simulator (ETS)
No full textIdentification of Loads Based on Historical Data
No full textTo tackle the forthcoming electricity grid tension in Gothenburg, Sweden, this thesis introduces a two-step machine learning approach for managing electricity demand. Initially, consumers are grouped using K-Means clustering according to their past patterns of usage in order to identify categories with the most fluctuating behaviour. Subsequently, several Long Short-Term Memory (LSTMs)—Vanilla, Stacked, Bidirectional, and CNN-LSTM—are trained for predicting electricity demand for such high-impact consumer groups in response to real-time, varying price signals. These models are evaluated using mean absolute error (MAE), root mean square error (RMSE), and loss measures. Among these examined architectures, CNN-LSTM exhibits the most consistent and stable performance across test and prediction datasets. This approach minimises the data and computation needed for deep learning but
allows for more customised forecasting. The proposed solution provides a resourceefficient and scalable solution for energy suppliers who wish to monitor changes in demand in response to price changes
From forest to framework: Exploring temporary disaster shelters in bamboo
No full textWe bare witness to increasing climate-related
disasters, and the need for rapid, cost-effective,
and sustainable emergency shelters has become
more urgent than ever. This study explores the
potential of bamboo temporary shelters as a viable
solution for displaced communities in Brazil, with
a focus on the early stages of disaster relief (1–4
weeks post-disaster). By utilizing the Guadua
and Bambusa species, a fast-growing and locally
available material, the thesis investigates how
bamboo can offer a lightweight, biodegradable,
and easily assembled shelter alternative. Taking
into account the principles of sustainability and
humanitarian aid, the research aims to develop a
shelter design that prioritizes ease of construction,
environmental responsibility, and adaptability
to the subtropical conditions of Região Serrana
region in the State of Rio de Janeiro.
The methodology combines field visits, literature
reviews, and hands-on design experimentation.
Site visits in the Região Serrana region provide
experience into local needs and environmental
factors, while research into aid organization
guidelines aligns the project with international
standards for temporary housing. The study
engages with contemporary bamboo construction
discourse through literature and practical learning
at TIBÁ (Institute of Applied Ecology and Low
Impact Architecture), a center specialising in
bio-architecture. The design process follows an
iterative approach, employing physical modeling
and full-scale prototyping of bamboo structures to
evaluate structural integrity, assembly efficiency,
and material performance.
This study contributes to the ongoing dialogue
on sustainable disaster relief by exploring the
feasibility of bamboo as a scalable, low-cost,
and rapidly deployable shelter material. By
focusing on self-assembly and biodegradability,
the proposed shelter design minimizes reliance
on specialized labor while reducing long-term
environmental impact. The findings aim to inform
both architectural practice and humanitarian
efforts, offering a practical blueprint for integrating
bamboo-based solutions into disaster response
strategies in Brazil and beyond
Trafikverkets väg mot målet: en klimatneutral infrastruktur 2040
No full textEtt av samhällets största utmaningar är klimatförändringar, där infrastrukturbranschen har en viktig roll i att minska växthusgasutsläppen. Trafikverket har som mål att bli klimatneutrala till 2040, vilket innebär att nå målet fem år tidigare än det nationella målet i Sveriges politiska ramverk. Cirkulär ekonomi och ett livscykelperspektiv kommer vara centrala strategier i studien och det krävs nya sätt att tänka för materialanvändning.
Infrastrukturprojekt använder stora mängder material i ett till linjärt materialsystem, dvs. utvinning av råvara, användning och avfallshantering. För att förebygga detta behöver flödena ställas om till mer I cirkulära alternativ där målet är målet att materialflöden för produkter och komponenter ska återanvändas eller återvinnas. Trafikverket behöver i en cirkulär ekonomi utveckla system för spårning och rapportering av materialflöden, enligt EU’s avfallsdirektiv (Europeiska unionen, 2008) för att identifiera resurser som bidrar till Trafikverkets klimatmål.
Syftet med studien är att undersöka olika material och tekniker inom väginfrastrukturprojekt för att utvärdera livscykeltänkande (LCT) för att skapa cirkulära flöden.
Den viktigaste slutsatsen var behovet av samordning mellan aktörer och förändring i rutiner och arbetssätt för en lyckad cirkulär omställning. Studien bygger på intervjuer och tidigare studier om cirkulär ekonomi och infrastruktur. Studien är avgränsad till svensk infrastruktur
Bridging the gap; circular economy adoption in residential renovation through stakeholder lenses; stakeholder perspectives; professionals and non-professionals
No full textThe construction and renovation sector is an major contributor to global greenhouse
gas emissions, which has led to growing interest in circular economy strategies.
While principles such as reduce, reuse, and recycle are increasingly adopted in new
construction, their practical application in residential renovation remains limited and
less studied. This thesis explores how circular economy principles are understood
and applied in interior renovation projects by both professionals, including architects
and project managers, and non-professionals, including homeowners and tenants.
The study is based on a mixed methods approach, combining qualitative interviews
with professionals and a quantitative survey distributed to residents. The findings
show that although professionals are aware of the environmental benefits of circular
strategies, they often face challenges such as limited time, unclear regulations, and
concerns about the quality of reused materials. Knowledge of circular economy
practices remains limited among non-professionals. These actors tend to base their
decisions primarily on functionality, durability, and cost, placing less emphasis on
the use of recycled or reused materials.
The research identifies several enablers that could strengthen the use of circular
economy in residential renovation, including clear policy support, incentives, better
digital tools, and stronger collaboration between stakeholders. The study also
emphasizes the need for targeted education to close the knowledge gap between
professionals and non-professionals. By presenting both technical and behavioral
insights, this thesis offers practical guidance for advancing sustainability in small scale
renovation contexts and contributes to ongoing discussions about circularity
in the built environment
Sustainability assessment using multicriteria analysis for wastewater handling
No full textThis study presents a sustainability assessment of three wastewater treatment technologies—
Activated Sludge (AS), Membrane Bioreactor (MBR), and Aerobic Granular Sludge (AGS)—
using the case of the Västra Stranden Wastewater Treatment Plant (WWTP) in Halmstad, Sweden.
A Multi-Criteria Decision Analysis (MCDA) approach was applied to evaluate and compare the
technologies across environmental, economic, technical, and social dimensions. Two different
weighting methods were tested: a traditional percentage-based model and a value-based model
using Weighted Score Ratios (WSR). Data collection included quantifiable performance indicators,
expert judgment from professionals at Laholmsbuktens VA (LBVA), and input from students in
an advanced wastewater engineering course.
The value-based model assigns monetary values to each sustainability criterion, helping to clarify
trade-offs and improve transparency in the decision-making process. Results from both workshops
showed that the value-based approach was more effective in identifying which criteria had the
greatest influence on overall sustainability.
This study highlights the strengths of combining technical data with structured stakeholder input
and suggests that value-based MCDA models can support more robust and balanced decisions in
wastewater planning
Automation of a PCB teststation with UR3 - An Applied Study in Collaborative Robotics and Test Process Engineering
No full textManual testing of printed circuit boards (PCBs) is a time consuming and repetitive process that can lead to ergonomic strain and inefficient productivity. This thesis explores how collaborative robots can be used to automate the PCB testing process in a lab scalen environment. The objective was to design, build and evaluate a prototype test station using the UR3 collaborative robot to perform automated pick and place, handling, test initiation and sorting of PCBs. The system was developed in two parallel configurations. The first used the UR3s built in interface called Polycope and interacted directly with the other components through the robots I/Os. The second setup combined a Raspberry Pi with Python programming and Real Time Data Exchange (RTDE) to enable external control, vision based positioning and more dynamic system behavior. A fixed camera mounted above the conveyor was used to implement edge detection for identifying the PCB's orientation while capacitive sensors and PWM-regulated motors supported component detection and transport. To support the physical integration of components, a number of custom designed mechanical parts were prototyped using 3D printing. These included gripper mounts, sensor housings, camera holders, claws and sorting trays, all tailored to match the layout and functional needs of the station. Testing showed that the UR3 robot could reliably automate the core steps of the test process. The PolyScope-based system provided high repeatability under fixed conditions, while the Python-based setup allowed for greater flexibility and modularity. Some challenges remained in the implementation of vision-based positioning, particularly in terms of distinguishing the PCB from the conveyor background. However the overall system fulfilled the defined functional goals and demonstrated the possibility of using a collaborative robot to improve efficiency, reduce physical workload and increase consistency in test workflow
Från data till hållbarhet: Digitala tvillingar och återbruk i samspel
No full textDenna studie undersöker hur digitala tvillingar, som är en kontinuerligt uppdaterad
3D-kopia av en byggnad, kan underlätta återbruk av material inom bygg- och
fastighetsbranschen. Syftet är att utforska digitala tvillingars potential för
informationshantering, spårbarhet och planering vid återbruk samt att identifiera
tekniska, organisatoriska och ekonomiska hinder för implementering. Bygg- och
fastighetsbranschen står inför stora hållbarhetsutmaningar, där återbruk är en viktig
del av omställningen mot en mer cirkulär ekonomi.
Studiens metod bygger på en kvalitativ fallstudiestrategi med fokus på
fastighetsbolaget Wallenstam samt intervjuer med annat fastighetsbolag och en
leverantör av digitala tvillingar. Data samlades in genom semistrukturerade intervjuer
och analyserades tematiskt. Studien avgränsades till ombyggnationsprojekt och
lokalanpassningar i Sverige.
Resultatet från studien visar på en tydlig potential för digitala tvillingar att stödja
återbruksarbete, särskilt genom bättre överblick över material och förbättrad logistik.
Dock är kopplingen mellan digitala tvillingar och återbruk inte allmänt etablerad i
branschen. Hinder för användning av digitala tvillingar inkluderar bristfällig
dokumentation i äldre byggnader, höga kostnader för detaljerad digitalisering,
avsaknad av standardiserade processer för återbruk samt behov av digital kompetens
och attitydförändring. Även varierande marknadsefterfrågan och brist på ekonomiska
incitament utgör hinder för en fullskalig implementering av verktygen i samspel.
Studien slutsats är att digitala tvillingar tekniskt sett kan möjliggöra effektivare
återbruk, men att detta förhindras av befintliga organisatoriska, tekniska och
marknadsmässiga utmaningar. Att realisera potentialen av digitala tvillingar kräver
investeringar i pålitliga data, utveckling av processer, kompetenshöjning samt en ökad
vilja och efterfrågan från alla aktörer. Studien kan därmed ge vägledning för företag
som överväger att implementera digitala tvillingar för mer hållbara byggprocesse
Correlated Effective Field Theory Truncation Errors: From Neutron-Proton Scattering Amplitudes to Observables
No full textThe strong force governing Nucleon-Nucleon (NN) scattering can be modelled with
an Effective Field Theory (EFT) of low-energy quantum chromodynamics. The Feyn man diagrams contributing to this force are considered order-by-order in an expan sion with decreasing importance. NN scattering observables can then be predicted
by considering all contributions up to some finite order, while neglected orders result
in predictable truncation errors. Contrary to previous studies, the EFT truncation
errors of different NN observable types should not be considered independent since
all of them depend on only five complex so-called scattering amplitudes. Instead,
truncation errors must be correlated not only across energies and scattering angles
but also across different observable types. In this thesis, we modelled and investi gated such correlations between the uncertainties of different neutron-proton scat tering observables resulting from a truncation of the chiral EFT guided by Weinberg
power counting.
We applied a Bayesian uncertainty-quantification model, consisting of a fixed kernel Gaussian process, on the leading order chiral EFT truncation errors of the
neutron-proton scattering amplitudes. The resulting errors were then propagated to
errors of various observables. We considered both Saclay and helicity conventions
for the NN scattering amplitudes with their specific angular boundary constraints.
Firstly, we found that the symmetry constraints of amplitudes propagate to observ ables, resulting in angle- and energy-dependent uncertainties. Secondly, we observed
strong angle-dependent correlations and rigid inequalities between different observ able types, cutting the joint posteriors into characteristic shapes traced back to
their amplitude dependencies. Finally, we examined the extent to which our error
model violates the unitarity constraint of the scattering operator by comparing the
optical-theorem and integrated total cross section. There was little to no correlation
between the uncertainties of these theoretically identical expressions. While we suc cessfully incorporated unitarity on average, future studies are necessary to explicitly
implement unitarity constraints into the error model.
This work is an important step in a larger effort to understand correlated
EFT truncation errors, considering rigorously the correlation between different NN
scattering observable types. The resulting error model could enhance the physical
robustness of EFT parameter inference and the reliability of theoretical predictions
for nuclear observables