Chalmers Open Digital Repository
Not a member yet
26247 research outputs found
Sort by
Cost-optimization and feasibility of e-methanol production powered by offshore wind energy
No full textDigital Peer-Reviewer with LLM-integration
No full textThis project develops an AI-powered web application to automate academic peer review processes and assess research novelty. Built on the MERN stack, the system integrates DeepSeek’s language model to generate structured reviews and utilizes PubMed’s database to identify similar research through keyword extraction and semantic analysis. Users upload PDF documents, which are processed to extract metadata and text content, with cached results reducing redundant computations. Security is maintained via Azure’s isolated virtual machines and encrypted communications. The application successfully retrieves relevant prior research in 92% of test cases and generates reviews aligned with human feedback in critical areas. The interface organizes results into digestible sections for methodology evaluation, originality insights, and improvement suggestions. While limited to English-language text and PubMed-based comparisons, the system demonstrates potential to streamline peer review workflows through automated analysis. Future expansions could address multilingual support and broader literature databases
A method for detecting horizontal gene transfer events of antibiotic resistance genes using phylogenetic trees
No full textAn algorithm, named the HGT-score algorithm, to computationally assess horizontal gene transfer of antibiotic resistance genes spread was developed using a methodology based on phylogenetic trees and host taxonomy labels. Applying the HGT-score algorithm on validation data showed that the algorithm detects horizontal gene transfer events. This work serves as a good starting point for further investigation and improvements.
The results are two-fold, consisting of the developed methods themselves, and the results that the methods generated when applied on real data. Antibiotic resistance gene (ARG)-based phylogenetic trees were cross-sectioned at different lengths from the root, named cutoffs. A cutoff generates flat clusters of leaves, encoding ARG similarity between hosts within each cluster. Distantly related host bacteria may end up in the same cluster if their genomes contain identical or similar antibiotic resistance genes. HGT-scores were given to clusters depending on the taxonomic similarity of member hosts, with higher dissimilarity resulting in a higher HGT-score.
The method was validated on a labelled dataset of ARGs, where the labels sorted ARGs into HGT-prone genes and non-HGT-prone genes. The HGT-prone data scored higher than non-HGT labelled data, particularly in specific cutoff regions. It is therefore plausible that the method scores HGT events higher, and that the cutoff is an important factor to account for in drawing conclusions as to when the events occurred.
Lastly, there are several directions to explore in order to improve the method. The HGT-score method is dependent on three key parameters: cutoff, cluster-level statistic, and p. These parameters should all be investigated and calibrated for different use case scenarios. A variant of the method should be investigated, using well-conserved genes rather than taxonomy as the base of gene tree-host species dissimilarity. This opens up the possibility of detecting HGT events across more closely related bacteria. Another interesting direction is fine-tuning cutoffs. Finer cutoffs could provide better resolution in critical parts of the phylogenetic gene trees where many bifurcations occur
Assessment of swashplateless rotor systems for sensor carrying drones: An investigation into control, efficiency, and feasibility
No full textThis thesis investigates two rotorhead configurations, a fully articulated dual hinge
and a semi-rigid teetering hinge rotor, for potential use in swashplateless helicopters
or drones, aiming to expand the understanding of their respective mechanical and
aerodynamical behaviours. Experiments were conducted on a fixed test rig designed
for easy interchangeability between the two rotor types. Both rotors were tested
with identical blades at fixed pitch angles of 8°, 10°, and 12°, using the same control
system.
Three test types were performed. First, a constant roll input was applied while
rotor speed varied from 500 to 3000 RPM, across three increasing roll magnitudes.
Second, a step response test measured the time required for the rotor to transition
from maximum to minimum roll output, assessing dynamic response. Third, a roll
sweep test was conducted at approximately 2500 RPM using stepwise increases in
roll input. High-speed video analysis was used to observe dynamic behaviour.
Results show that the fully articulated dual hinge rotor provides more effective
thrust vectoring across all roll inputs and RPMs, while operating at significantly
lower vibration levels. Both rotors exhibited similar energy consumption and roll
rates. While the dual hinge rotor’s improved thrust control and smoother operation suggest advantages for general purpose drones and helicopters, especially those
carrying sensitive sensors and equipment, the semi-rigid teetering hinge rotor’s simplicity and robustness is attractive for applications where mechanical reliability,
weight reduction, and ease of maintenance are prioritized. Further exploration of
teetering rotor concepts, especially in alternative configurations and with a further
optimized control system, may reveal additional potential not fully captured in this
study
Air-path control of a heavy-duty hydrogen internal combustion engine
No full textHydrogen internal combustion engines (H2-ICEs) offer a promising zero-carbon option to conventional diesel engines in the heavy-duty industry. This technology presents challenges in air-fuel ratio (AFR) control due to the wide flammability range and fast combustion characteristics of hydrogen. Maintaining the relative AFR (λ) value within acceptable limits is critical to reducing NOx emissions while ensuring stable engine operation. This thesis studies the feasibility of implementing an air-path λ-control strategy to improve AFR regulation in the engine. A grey-box modeling approach was employed to map system parameters for the gas transport dynamics, utilizing engine test cell data collected under various operating conditions. The estimated parameters were then used to design and tune a feedback controller with dead time compensation. The control strategy was tested in a simulation environment, demonstrating improved λ tracking with minimal impact on the engine performance compared to a baseline strategy. The results demonstrate that air-path lambda control is a promising approach for managing the air-fuel ratio in H2-ICEs, with potential for further improvements under extended operating conditions
Enhancing sEMG contaminant classification accuracy through statistical feature analysis and machine learning: Enabling improved sEMG signal quality
No full textCan the most prevalent contaminants in Electromyography (EMG) signals be accurately identified and classified during an EMG examination? EMG with applications are highly affected by signal contaminants, decreasing efficiency and accuracy. The thesis aims in particular to assist home users and non-technical hospital personnel in detecting EMG contaminations, and in the future, guide how to remove contaminants
without filtering. This thesis presents two machine learning models for EMG contaminant classification: a single-label model and a multi-label model. A comprehensive feature evaluation was conducted to identify signal features that could differentiate signals of different contaminations and signal-to-noise ratios. Combining time and frequency domain features improved the ability to distinguish between different contaminants at various signal-to-noise ratios, enhancing overall classification accuracy. EMG signals from public databases were artificially contaminated with the three most common EMG contaminants: Electrocardiography (ECG) interference, Motion Artefact (MA) and White Gaussian Noise (WGN). Among several machine learning algorithms, a Random Forest model type achieved the highest accuracy. Two different models, one single-label model and one multi-label model, provide the possibility to either detect the most prominent or all present contaminants. The models utilise five-second segments to classify the EMG signal, allowing for quick feedback on possible contaminations. While offline performance was strong, online validation revealed challenges related to signal variability and generalisation. Still, the approach demonstrates promising potential for classification of EMG signal contaminants in clinical settings, providing the opportunity to improve the quality of EMG signals during examinations or when used with an assistive technology, improving the user’s quality of life
Kv Bolmörten; a building lost in changing context; how to retain reuse and reinvent a neglected structure
No full textBuildings are often seen as static entities created to perfection on the drawing board, yet
in reality, most cities are filled with ‘ordinary’ buildings constructed to meet the simple
needs of their inhabitants - needs that, at different rates always will require reinvention.
Monuments in all their glory, are part of a cities identity, but most cities identity has been
shaped and curated by the evolving relationship between a typical ‘ordinary’ building
and its inhabitant. Resulting in cities constant continual change. With that in mind will
this thesis consider how we, as architects, can care for these already existing structures.
This thesis will use a neglected structure located in the southern part of central
Gothenburg as an example of the buildings we live and interact with, without paying
much attention to its qualities. Today, Gothenburg is developing large parts of its
central areas, making the question of how we navigate change in the built environment
highly relevant. The block Kv. Bolmörten is currently situated in a context that is rapidly
transforming from industrial to residential use in just a few years - making the block lost
in changing context. The thesis will results in a proposal exploring how to retain, reuse
and reinvent the neglected block to sustain a purpose and endure in its new context - at
least until it needs to adapt again.
By proposing a new program and making Kv. Bolmörten go from passive to active for its
surrounding results in a number of interventions. Implementing adaptive interventions
focusing on necessary and pragmatic aspects does the thesis seek for effective and
aesthetic outcomes. Supported by drawings, visualizations and models is the proposal
exploring different scales of interventions with help of materiality and textures, merging
old and new. The result manifests that the imperative approach to rehabilitate rather
than demolish, is not only more sustainable, it can lead to an altogether richer urban
environment. The thesis serves as an example how to balance preservation with the
inevitable need for continual change and modernization
Designing a Mobile User Interface for Tree Professionals
No full textConducted in collaboration with Husqvarna Group, this study explores the specific user requirements of arborists and loggers in the context of mobile fleet management, aiming to design a user-centered interface that enhances their daily workflows. Currently, Husqvarna Fleet Services offers limited value to tree professionals, as its user interface and features are not sufficiently tailored to the unique needs of arborists and loggers. Using the Double Diamond design process, the study employed qualitative methods including interviews and observations to identify user needs and translate them into clear user requirements. The defined user requirements covered areas such as machine data, battery management, GPS tracking, service and maintenance, and theft prevention. An ideation phase was initialized, including brainwriting and Crazy 8’s, creating the foundation for the prototyping. The prototype was evaluated through user testing with both end-users and product specialists, indicating high perceived usability. The prototype demonstrated high usability and through user tests key features were evaluated. Features adding the most value, which can increase the adoption of a mobile user interface for arborists and loggers, were real-time equipment tracking, reminders when forgetting or losing equipment, theft prevention, battery labeling, battery status and identification, and purchase of spare parts, supporting a more efficient and user-centered mobile user interface for tree professionals. Suggested future work includes broader end-user testing, investigating potential position tracking systems, and the process of purchasing spare parts, among others
Living with water; an exploration of how a waterfront housing area can be designed with a holistic approach to water
No full textThe main purpose of this master’s thesis is to explore the
topic of housing by water, and how proximity to water
could be used as a quality to enhance resident wellbeing
while simultaneously handling present and future
water-related sustainability challenges.
The research questions are: 1) How can a waterfront
residential neighbourhood be designed with a holistic
approach to water in order to enhance well-being while
addressing water-related environmental challenges? 2)
How can a waterfront residential block and its dwellings
be designed to utilise water as a quality in order to
enhance resident well-being? and 3) How can waterrelated
environmental challenges be handled and
utilised to create qualities in a waterfront residential
block and its dwellings?
The thesis is structured into four parts. In the first part,
a theoretical framework is created based on a literature
review of the concepts water access, water and wellbeing,
and water management; a review of eight
reference projects of housing by water; as well as a
review of three study trips to Copenhagen, Barcelona
and Oslo. In the second part, nine design strategies
– three for each key concept and three for three
different scales; neighbourhood, block and dwelling –
are presented based on the theoretical framework. In
the third part, the design strategies are implemented
in a residential design project by the waterfront in
Lindholmen in central Gothenburg. The design project
covers the neighbourhood, block and dwelling scale.
In the fourth part, the design proposal is discussed in
relation to the research questions and design strategies.
To conclude, the design strategies support the creation
of an environment which can enhance well-being while
addressing urban water challenges through a holistic
approach to water. The design proposal demonstrates
how architecture has the capacity not only to respond to
environmental challenges, but also how to use them as
a driving force to create qualities which enhance human
well-being. The design presents a vision for how water
can be integrated into the built environment in various
ways on the neighbourhood, block and dwelling scales,
thereby creating sustainable environments for living
with water