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  • Public defence: 2024-05-13 13:00 Amiga, https://kth-se.zoom.us/j/68751222626, Stockholm
    Behdad, Zinat
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS.
    Integrated Sensing and Communication in Cell-Free Massive MIMO2024Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Future mobile networks are anticipated to not only enhance communication performance but also facilitate new sensing-based applications. This highlights the essential role of integrated sensing and communication (ISAC) in sixth-generation (6G) and beyond mobile networks. The seamless integration of sensing and communication poses challenges in deployment and resource allocation. Cell-free massive multiple-input multiple-output (MIMO) networks, characterized by multiple distributed access points, offer a promising infrastructure for ISAC implementation. However, the effective realization of ISAC necessitates joint design and resource allocation optimization. In this thesis, we study ISAC within cell-free massive MIMO systems, with a particular emphasis on developing power allocation algorithms under various scenarios.

    In this thesis, we explore two scenarios: utilizing existing communication signals and incorporating additional sensing signals. We propose power allocation algorithms aiming to maximize the sensing performance while meeting communication and power constraints. In addition, we develop two maximum a posteriori ratio test (MAPRT) target detectors under clutter-free and cluttered scenarios. Results indicate that employing additional sensing signals enhances sensing performance, particularly in scenarios where the target has low reflectivity. Moreover, although the clutter-aware detector requires more advanced processing, it leads to better sensing performance. Furthermore, we introduced sensing spectral efficiency (SE) to measure the effect of resource block utilization, highlighting the integration advantages of ISAC over orthogonal resource sharing approaches. 

    In the next part of the thesis, we study the energy efficiency aspects of ISAC in cell-free massive MIMO systems with ultra-reliable low-latency communications (URLLC) users. We propose a power allocation algorithm aiming to maximize energy efficiency of the system while meeting communication and sensing requirements. We conduct a comparative analysis between the proposed power allocation algorithms and a URLLC-only approach which takes into account only URLLC and power requirements. The results reveal that while the URLLC-only algorithm excels in energy efficiency, it is not able to support sensing requirements.   Moreover, we study the impact of ISAC on end-to-end (including radio and processing) energy consumption. Particularly, we present giga-operations per second (GOPS) analysis for both communication and sensing tasks. Two optimization problems are formulated and solved to minimize transmission and end-to-end energy through blocklength and power optimization. Results indicate that while end-to-end energy minimization offers substantial energy savings, its efficacy diminishes with sensing integration due to processing energy requirements.

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  • Persson, Jan-Gunnar
    Fluid mechanics.
    Heat Exchange in Liquid Injected Compressors1986Licentiate thesis, monograph (Other academic)
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  • Olanders, Martin
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lättkonstruktioner, marina system, flyg- och rymdteknik, rörelsemekanik.
    Structural Health Monitoring using Vertically Aligned Carbon Nanotubes for Cryogenic Tanks2023Independent thesis Advanced level (degree of Master of Fine Arts (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    By structural health monitoring (SHM) of composite structures, their sustainability, safety and economics can be improved. On one hand, it enables using components to their full life or having them replaced early before otherwise unforeseen failure. On the other hand, it may make structures lighter as designs with smaller safety margins would be possible. Cryogenic liquid hydrogen tanks for aircraft would need to become lighter to enable such fossil-free aviation, which could require SHM. Vertically aligned carbon nanotubes (VACNT) have been used as embedded sensors in composites for temperature and strain sensing while other architectures of nanotubes have been used to detect fatigue damage. In this work, VACNT embedded in carbon fibre/epoxy composites are cycled both thermally and mechanically to investigate their suitability to detect damage in composite cryogenic tanks. It was found VACNT retain their strain sensing ability after cycling to cryogenic temperatures and that a relationship of increasing electrical resistance to increased cycling and damage is possible. That indicates VACNT are suitable for SHM of cryogenic tanks, but more testing and better electrical insulation of the VACNT is needed to confirm this.

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  • Antonelli, Dario
    et al.
    Aliev, Khushid
    Soriano, Marco
    Samir, Kousay
    KTH, School of Industrial Engineering and Management (ITM), Production engineering.
    Monetti, Fabio Marco
    KTH, School of Industrial Engineering and Management (ITM), Production engineering.
    Maffei, Antonio
    KTH, School of Industrial Engineering and Management (ITM), Production engineering, Industrial Production Systems.
    Exploring the limitations and potential of digital twins for mobile manipulators in industry2024In: 5th International Conference on Industry 4.0 and Smart Manufacturing (ISM 2023), Elsevier BV , 2024, Vol. 232, p. 1121-1130Conference paper (Refereed)
    Abstract [en]

    This paper explores the qualification of a digital twin (DT) for a mobile manipulator (MOMA) in industrial applications. We discuss the development of different DT models based on various industrial needs and highlight the dependence of model accuracy on online sensor precision. Limitations of DTs for MOMA are examined, including challenges in respecting qualifiers due to the inability to incorporate unstructured aspects of the factory environment. Through a case study and some examples, we show the latent potential and limitations of DTs for MOMA in industrial contexts. The challenges of fidelity, real-time operation, and environment modeling are discussed. It is emphasized that creating a true digital twin of a mobile manipulator is hindered by the inability to include the complete surrounding environment. Recommendations for future research focus on addressing these limitations to enhance the effectiveness of DTs for MOMA in Industry 4.0 and smart manufacturing.

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  • Monetti, Fabio Marco
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production engineering, Industrial Production Systems.
    Maffei, Antonio
    KTH, School of Industrial Engineering and Management (ITM), Production engineering, Industrial Production Systems.
    Towards the definition of assembly-oriented modular product architectures: a systematic review2024In: Research in Engineering Design, ISSN 0934-9839, E-ISSN 1435-6066, Vol. 35, no 2, p. 137-169Article in journal (Refereed)
    Abstract [en]

    The success of a product in the market is largely defined by the quality of design decisions made during the early stages of development. The product design requires designers to balance multiple objectives such as functionality, cost, and user satisfaction, while addressing the challenges posed by increasing product variants and customization demands. To tackle these challenges, one approach is to structure a comprehensive model that incorporates design for assembly (DFA) guidelines during the formulation of product architecture in the conceptual phase of development. While numerous strategies have been proposed in the literature, information is often scattered, making it difficult for readers to gain a comprehensive understanding of the topic. This paper systematically reviews the role and impact of DFA in product development, consolidating and presenting the information coherently. The review provides an overview of the methods developed, along with their potential benefits and limitations. A common framework is identified that defines the structure of the models, helping designers integrate assembly consideration into their design processes, thus reducing assembly time, cost, and complexity. The framework describes the operational setting, including the domain and context in which models operate, and offers a classification of possible methods and desired outputs. Additionally, the review identifies the industry in which case studies have been most frequently presented, and the software used to facilitate the process. By connecting with such a framework, future models can be created following a structured approach, and existing models can be classified and upgraded accordingly.

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  • Jeong, Yongkuk
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production engineering, Advanced Maintenance and Production Logistics.
    Flores-García, Erik
    KTH, School of Industrial Engineering and Management (ITM), Production engineering, Advanced Maintenance and Production Logistics.
    Wiktorsson, Magnus
    KTH, School of Industrial Engineering and Management (ITM), Production engineering, Advanced Maintenance and Production Logistics.
    Integrating Smart Production Logisticswith Network Diagrams: A Frameworkfor Data Visualization2024In: Proceedings of the 11th Swedish Production Symposium / [ed] Joel Andersson, Shrikant Joshi, Lennart Malmsköld, Fabian Hanning, 2024, p. 601-612Conference paper (Refereed)
    Abstract [en]

    This paper introduces a framework that integrates smart production logistics(SPL) with network diagrams. This integration enhances visibility in the materialand information flow within the manufacturing sector, thereby adding valuethrough data visualization. Drawing from a detailed case study in the automotiveindustry, we outline the essential components of network diagrams that are tailoredto depict spatial-temporal data linked with material handling processes in an SPLcontext. This integrated approach presents managers with a new tool for optimizingplanning and executing tasks related to the transport of materials and information.Furthermore, while the framework brings about significant technological progress,it also emphasizes the managerial implications of SPL data visualization. In particular,it highlights its potential to foster informed decision-making, resource optimization,and strategic forecasting. The paper also discusses prospective researchavenues, stressing the importance of dynamic diagrams that decode complex patternsfrom digital data and the incorporation of sustainability metrics in SPL assessments.

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  • Public defence: 2024-05-15 10:00 https://kth-se.zoom.us/j/67779557414, Stockholm
    Khodadadi, Abolfazl
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electric Power and Energy Systems. KTH Royal Institute of Technology.
    Electricity Market Design Strategies for Hydro-dominated Power Systems: Exploring Optimal Bidding, Planning, and Strategic Operation through Various Market Design Strategies2024Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The existing wholesale power markets in Nordic countries play a vital role in ensuring the planned balance between supply and demand. However, these markets do not guarantee real-time operational security of the power system. This responsibility falls on the transmission system operator (TSO), who balances consumption and generation in real-time to maintain a secure state.

    To address these issues, a series of research studies have been performed in this thesis to delve into the intricacies of Nordic balancing markets and propose strategies to enhance their efficiency and effectiveness. These studies have been conducted around the hydropower units as the main generation sources in the Nordic electricity markets. These studies recognize the potential benefits of versatile balancing markets and increased trade of flexible resources with Continental Europe. 

    Additionally, the research results shed light on the optimal bidding strategies for hydropower plants (HPPs) in the day-ahead energy and manual frequency restoration reserve (mFRR) markets. HPPs play a crucial role as a flexible energy source, and their participation in these markets requires careful planning and decision-making. The studies consider various factors such as market rules, mFRR capacity market, future electricity prices, and the impact of active-time duration of balancing energy market offers on revenue generation. This inclusion provides a more realistic revenue portfolio for the operators based on the possibility of not being dispatched in the balancing market. 

    Furthermore, the research explores the concept of flexible stochastic scheduling strategies in hydropower-dominated energy markets. By considering day-ahead energy markets, mFRR markets, and the interaction between different market setups. These strategies provide the necessary flexibility for both the planning and operational stages. The aim is to maximize the profits of the hydropower units while addressing the opportunity cost of saving water and meeting the mFRR capacity requirements imposed by the TSO. Participation in new market setups is an increasingly interesting framework for the operator after the recent introduction of those markets and the results of this section help them to form more profitable decision-making frameworks for their assets. 

    Moreover, the optimal strategic portfolio assessment of HPPs in a multi-settlement market is discussed. Recognizing the increasing electricity prices and the growing penetration of renewable energy resources, these studies leverage bilevel programming problems to model the strategic behavior of HPPs in day-ahead and frequency containment reserve markets. The proposed approaches aim to enhance decision-making processes, promote market efficiency, and enable effective asset management in a dynamic and evolving energy landscape to make more informed multi-market trading decisions. 

    Also, the research examines the dimensioning of frequency restoration reserves in a multi-area power system, specifically focusing on the Nordic case study. By adopting a sequential dimensioning methodology and employing chance-constrained optimization, the studies allocate reserves based on system needs, optimize line flows, and reduce total reserve requirements. The results highlight the potential for sharing reserves among bidding zones in the Nordic synchronous area, contributing to a more efficient and coordinated power system operation.

    Lastly, a thorough investigation has been performed to assess the effectiveness of the current contract-for-difference contracts as the main support schemes for the development of new renewable energy assets. Case studies have been conducted to demonstrate quantitatively the pros and cons of different proposals and provide new hints for policy-makers about their future decisions. 

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  • Girondi, Massimo
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Software and Computer systems, SCS.
    Scazzariello, Mariano
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Software and Computer systems, SCS.
    Maguire Jr., Gerald Q.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Communication Systems, CoS.
    Kostic, Dejan
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Software and Computer systems, SCS.
    Toward GPU-centric Networking on Commodity Hardware2024In: 7th International Workshop on Edge Systems, Analytics and Networking (EdgeSys 2024),  April 22, 2024, Athens, Greece, New York: ACM Digital Library, 2024Conference paper (Refereed)
    Abstract [en]

    GPUs are emerging as the most popular accelerator for many applications, powering the core of machine learning applications. In networked GPU-accelerated applications input & output data typically traverse the CPU and the OS network stack multiple times, getting copied across the system’s main memory. These transfers increase application latency and require expensive CPU cycles, reducing the system’s efficiency, and increasing the overall response times. These inefficiencies become of greater importance in latency-bounded deployments, or with high throughput, where copy times could quickly inflate the response time of modern GPUs.We leverage the efficiency and kernel-bypass benefits of RDMA to transfer data in and out of GPUs without using any CPU cycles or synchronization. We demonstrate the ability of modern GPUs to saturate a 100-Gbps link, and evaluate the network processing timein the context of an inference serving application.

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  • Al-Taher, Ali
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Ahmad, Saman
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Minskning av klimatpåverkan hos betong genom användning av gröna bindemedel: En studie av tryckhållfasthetsutvecklingen2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Concrete is one of the most common building materials in the world. Many different types ofconcrete have been developed and adapted over the millennia of human use. However, global-scale concrete production generates a significant amount of carbon dioxide emissions. Thisstudy aims to explore how partly substituting conventional cement with green binders inconcrete affects its carbon footprint and compressive strength. By using alternative binderswith lower environmental impact, this work seeks to improve both the strength and climateimpact of concrete over time.The methodology of this study involves creating five different concrete recipes and testingcompressive strength. The recipes vary in terms of the binders used (and the particle size ofthe aggregate in one recipe). Cubes with different concrete recipes were cast, cured, andsubjected to compression tests, with cubes from the standard recipe exhibiting the highestcompressive strength.An analysis of the climate impact was conducted by calculating the carbon emissionsproduced during the manufacturing of the various binders. The results showed that the silicamixture exhibited the highest potential for carbon reduction, with a 52% reduction comparedto the conventional recipe (Batch 1). The Merit mixture and the LC3 mixture also showedsignificant reductions in carbon emissions (47% and 44% reduction compared to Batch 1,respectively). However, a reduction in compressive strength was noted in the cubes, with theLC3 mixture displaying a significant weakening.The conclusions of the study emphasize the importance of exploring alternative binders tocreate more sustainable concrete production. At the same time, the need to fine-tune thecomposition of binders (and any additives) to achieve optimal compressive strength ishighlighted. By leveraging green binders and optimizing material choices, the constructionsector can contribute to reducing climate impact and promote a more sustainable future.

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  • Quoreshi, Arvin
    KTH, School of Engineering Sciences (SCI), Physics.
    Mathematical Modeling of Plasma Dynamics and Dielectric Recovery in Vacuum Interrupters for HVDC Circuit Breakers2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To ensure the safe operation of high-voltage direct current grids, circuit breakers are used to disconnect a faulty link from the rest of the grid. Incorporating vacuum interrupters as a part of these circuit breakers constitutes an outstanding technology for such DC interruptions. However, testing the interrupters take a long time and can be very expensive. Hence, to reduce the time and cost of testing the interrupters, the purpose of this project was to find the most important parameters to test in a vacuum interrupter to evaluate it for use in a DC circuit breaker. This was done by modeling the particle density, before and after current-zero, and the post-arc current using a new model along with existing ones. Review of existing research was also included to support the models in order to draw conclusions regarding reignitions and restrikes. dI/dt before current-zero, dV /dt after current-zero, and contact gap length were found to be the key contributors for reignition, while temperature, contact surface condition and contact gap length were of great importance for restrikes. These breakdowns should occur around the center of the contact surface, or at surface protrusions. The following parameters should be varied when testing vacuum interrupters: dI/dt before current-zero, ranging from 10 A µs−1 to 800 A µs−1; arcing current, from 1 kA to 20 kA; arcing time, from 1 ms to 4 ms before current-injection; dV /dt after current-zero, from 0.5 kV µs−1 to 20 kV µs−1; maximum TRV from 5 kV to 25 kV, to find the threshold voltage for failed interruption; and gap length, from 1 mm to 10 mm, to find the critical gap length. Furthermore, temperature should also be measured, though measuring postarc current seems to be of lesser importance. To minimize damage to the interrupter, it was recommended to start with higher gap lengths with low values on everything else.

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  • Svensson, Emilie
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Detection of Marijuana Components Adsorbed on Dust: A Dual Approach of Thermal Desorption GC/MS and Detection Dog Analysis2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Detection dogs are an important tool utilized by police forces and customs, but their method of detection is not fully known. The odor profile of a substance is of major importance during dog detection, but they are difficult to research chemically due to the disconnection between concentration and contribution to the odor profile. The purpose of this research was to increase the knowledge regarding the mechanism of detection dogs in relation to adsorbed components on dust, as well as of how the odor profile of marijuana differs to that of dust contaminated with marijuana. Lemon and lime were utilized as model systems and pieces of peel were analyzed directly. Terpenes and terpenoids were the main compounds of interest. The research consisted of a dual approach, utilizing both thermal desorption gas chromatography mass spectrometry (TD-GC/MS), and detection dog analysis in the form of selection exercises. Office dust and bought particulate matter (PM)-like standard dust with an aerodynamic diameter of about 10 µm was contaminated with marijuana, lemon, lime, and a cannabis terpene mix in desiccators for 1, 3, and 7 days. A secondary marijuana contamination was also conducted, where the 1-day dust sample contaminated with marijuana was used to contaminate new dust and PM samples, and dust samples were also taken in storage units of packaged illicit drugs. From the laboratory contaminated samples with marijuana, a total of 25 compounds of interest were detected by TD-GC/MS from the dust samples, and 57 from the PM samples. From the direct TD-GC/MS analysis of lemon peel, it was evident that more monoterpenes (C10H18) than sesquiterpenes (C15H24) were detected, and the contrary was found for the lemon contaminated dust and PM samples. This entails that the odor profiles of marijuana as is and adsorbed on dust or PM is also likely to differ. Still, the detection dogs were able to detect the dust and PM samples which had been co-stored with marijuana for 1 day, and some also alerted to a few of the secondary contaminated marijuana samples as well as the samples from marijuana storages. None or only a few compounds of interest were detected by TD-GC/MS in some of the samples the detection dogs alerted to, which highlights the higher sensitivity of detection dogs, and thus the difficulty of chemically researching odor profiles the dogs can detect. All in all, detection dog analysis of dust collected at scenes of interest may be a viable method to detect marijuana, and perhaps other illicit drugs.

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  • Johansson, Nils
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Strategic Sustainability Studies.
    Breddad rekrytering handlar om mer än föräldrarnas utbildningsbakgrund2024In: Universitetsläraren, ISSN 0282-4973, Vol. April 12Article in journal (Other (popular science, discussion, etc.))
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  • Johansson, Nils
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Strategic Sustainability Studies.
    Återvinn inte askan från våra sopor2024In: Forskning & Framsteg, ISSN 0015-7937, Vol. 11 AprilArticle in journal (Other (popular science, discussion, etc.))
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  • Ayed, Tarek
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Detecting Outliers in Few-Shot-Learning Support Sets2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Few-shot-learning is a machine learning research area where a model infers a task it has not been trained on. In Computer Vision classification, this means classifying samples among classes the model has not seen during training, and given only a few examples of each class, typically less than 5. The quality of these few labeled samples (i.e. the support set) is highly impactful on the performance of the model. In particular, the presence of outliers in the support set quickly degrades the model’s ability to learn the classification task [1] [2]. We propose a method to detect these outliers using KNN and Isolation Forest and an already trained FSL backbone. We achieve more than 91.3% AUROC on CUB [3] and 89.3% on MiniImageNet [4] for 5-shot tasks. We also show that this method scales reliably to 10-shot and 500-shot setups and that these results are highly reliant on the quality of the used backbone.

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  • Majid, Maria
    KTH, School of Electrical Engineering and Computer Science (EECS).
    A Qualitative Investigation of Speech Language Pathologists on The Acceptance of High-Tech AAC Among Their Patients Using Extended Technology Acceptance Model2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Due to the advancement in AAC technology, set of medical conditions can be assisted using high-tech AAC, serving more patients with varying communication needs. There need to be more studies about the acceptance of HT-AAC among individuals with complex communication needs, by understanding their attitude and behavioral intentions towards this technology. This thesis aims to extend previous literature and address the gap by exploring the perceptions of SLPs' regarding the acceptance of high-tech AAC and the perceived pitfalls associated with using HT-AAC. An exploratory research method combined with qualitative approach was chosen to answer the research questions and serve the purpose of the study. SLPs recognize the importance of HT-AAC in various aspects of their patients' lives. The findings highlight the need for comprehensive support, specialized training, and addressing implementation challenges to maximize HT-AAC acceptance and usage. By addressing these aspects, HT-AAC can enhance the communication and overall quality of life for patients with communication difficulties.

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  • Penacho Riveiros, Alejandro
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Asynchronous Multiagent Algorithms for Warehouse Robot Coordination2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As e-commerce companies experience increasing demands, the need to efficiently manage logistic centers has motivated the development of new multiagent algorithms specialized in this task. This work deals with the specific problem of coordinating large groups of robots to deliver boxes from their original positions to their targets in a short amount of time, while avoiding collisions between each other. The solution proposed here divides the problem in two different parts, one concerned with the long-term delivery strategy and the other with the pathfinding. The first problem is tackled by a new algorithm, inspired by multiagent rollout and multiagent dynamic programming, which is capable of dealing with very complex problems by focusing on smaller subproblems in it. The second problem is solved using multiagent dynamic programming, optimizing the paths of the robots sequentially. The performance of the methods developed is analyzed, and then they are combined in a final program in order to provide a complete solution to the problem. The resulting program manages efficiently the robots in a computational simulation of the warehouse.

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  • Hellberg, Louise
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Reduce the gender gap in computer science education using creative programming2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Women are lacking in Science, Engineering, Technology, and Mathematics (STEM). One of the proven solutions to reduce this gap is to offer extra support to the students needing it. Further, creativity has been shown to give positive effects on females’ participation in STEM. In this thesis, a creative tool for programming education in junior high schools in Sweden was developed to give alternatives to how programming is taught and further evaluate the possible contributions it can give. The tool was tested among 14 students participating in a face-to-face workshop. To further evaluate the tool use, the study participants took part in interviews and a survey. The results show that further iterations of the tool would have been needed since the tested tool was not perceived as easy to use. Regarding perceived usefulness, the tool is on the right path since the results indicate it was fun to use but again, improvements need to be done. The contributions made are therefore an exploration of the creative alternative to programming learning in the Swedish school. Furthermore, to find out what improvements needed to be done to offer an, by users, accepted tool. Offering creative programming tools will hopefully attract a more diverse group of people to programming and decrease the gender gap within computer science.

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  • Heyman, Hugo
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Enabling geospatial hybrid-collaboration on a multi-user touch interface through hand-chord based interaction: Collaborative single-display teamwork without any widget or button2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sharing a single, large touchscreen between several collaborating users is the research area of multi-user touchscreen interfaces, also named collaborative groupware. Collaborative groupware concerns how to best facilitate teamwork over such shared digital spaces. The technology is used in a number of high-technological and expert-dominated domains including emergency coordination, urban planning, military strategy, etc. This thesis investigates the problem of how to facilitate such mixed-focus work on a multi-user touchscreen in a two-dimensional geospatial context - a digital map - while avoiding the problematic use of widgets and click interfaces. Through a background study of previous work, a new solution is suggested. It is a handchord-input-based interface that uses hand-pattern recognition to interface with multiple users simultaneously and provides graphical tools to enable and enhance geospatial collaborative work. This solution is implemented and evaluated in two user studies. The first investigates the solution in the aspects of practical interfacing, tool impact, and hybrid collaboration on small teams of two. A second smaller expert user study evaluates the technique in the aspects of responsiveness, effectiveness, and representation; with more formalized procedures. The results show that a strong majority of users in the first study could successfully and quickly learn chord-input interfacing, and use it to access a variety of functionality with effectivity and enhancement of collaboration. The results of the second survey received moderately positive feedback in all aspects, with reserved opinions for its usage potential. These results indicate that chord-based interfacing, successfully implemented, could contribute to improved teamwork and task-solving in relevant collaborative contexts.

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  • Alobaidi, Murtadha
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Trabulsiah, Abdullah
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Mapping out the Key Security Components in Relational Databases (MK-SCoRe): Enhancing the Security of Relational Database Technology2024Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Relational database security has become an increasingly important issue for organizations worldwide in the current era of data-driven operations. The urgent need for an extensive knowledge of relational database security components in relational databases is addressed in this thesis. Database security is constantly improving, but there is still a lack of research that analyzes these important factors. Because of this gap, databases are not sufficiently secured from new cyber threats, which endangers its accessibility, confidentiality, and integrity. The problem that the thesis addresses is the lack of comprehensive research covering all key security components in relational databases which, presents a challenge for organizations seeking to comprehensively secure their database systems. The purpose of this thesis is to systematically map the key security components essential to relational databases. The goal is to assist organizations and Database professionals to secure their relational databases against diverse cyber threats. Using a qualitative and exploratory methodology, the research analyzes a wide range of literature on database security. The research offers a balanced and comprehensive perspective on the current security landscape in relational databases by integrating theoretical study with structured interviews. This method guarantees that all essential security components is fully investigated. The results of this thesis involve a detailed mapping of the key security components within relational databases, which are uniquely informed by a combination of academic research and empirical findings from structured interviews with Database security experts. This thesis analyzes these security components based on how well they address current security threats, how well they secure databases, and how well they can adapt to different organizational needs.

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  • Popova, Kristina
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Human Centered Technology, Media Technology and Interaction Design, MID.
    Park, Joo Young
    KTH, School of Electrical Engineering and Computer Science (EECS), Human Centered Technology, Media Technology and Interaction Design, MID.
    Demir, Arife Dila
    Estonian Academy of Arts.
    Conquering the Silence, Exploring the Uncomfortable Together: A Collective Exploration of Discomfort as a Design Resource2023Conference paper (Refereed)
    Abstract [en]

    Building on feminist HCI, care ethics and soma design, we invite design practitioners to collectively explore otherwise hidden and isolating experience of discomfort. By discomfort we understand a range of first-person experiences: from physical pain to a slight sense of unease related to social interaction. The purpose of the workshop is to explore uncomfortable feelings and sensations, which are present in our bodies but whose existence is rarely acknowledged and shared. We will engage in the exploration through a one day workshop combining bodily exercises with collaborative design activities. The first goal of the workshop is to materialise corporeal discomfort and experiment with different ways of articulating experience. The second goal is to explore and change the process of designing together through. We will pay attention to the uncomfortable in order to develop the ways of working together that are based on our shared vulnerabilities rather than privileges and shed light on how collective immersion of bodily discomfort could spark a caring and generative design process.

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  • Rusli, Andri
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Evaluation on the impact of low and high chip basic density (CBD) and H-Factor variation delignification rate of Eucalyptus species2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The improvement in people’s fashion lifestyle has stimulated an increase in textile demand, including the use of dissolving pulp. Dissolving pulp with high purity of cellulose content and unique properties has been an attractive material in the textile industry. Eucalyptus wood has been broadly used in dissolving pulp production, especially in Indonesia and Brazil. Eucalyptus wood offers several advantages such as high cellulose content and rapid growth that make it an ideal raw material. In this study, eucalyptus with low and high basic density, were selected in the dissolving pulp process. Better knowledge and understanding of the cooking delignification process of two different densities of eucalyptus could be used to achieve excellent cooking performance such as pulp yield and quality.

    The main objective of this thesis was to investigate the impact of chips basic density of eucalyptus in the dissolving pulp process. The dissolving pulp process method followed the APRIL company process standard. The prehydrolysis temperature was set at 110 oC to 165 oC with ramping 2 oC/min, neutralization temperature was set at 150 oC and the mild cooking temperature at 155 oC, while the cooking chemical concentration effective alkali 20% and sulfidity 30% were kept constant but the H-Factor targets were varied. The physical and chemical properties of eucalyptus were analyzed and the unbleached pulp produced was then analyzed for screened pulp yield, lignin content, pentosan, viscosity, and brightness. Furthermore, the fiber morphology was investigated with SEM and the lignin structure was investigated with 2D-NMR.

    The findings indicate that the high basic density eucalyptus wood exhibited superior behaviors and demonstrated ideal raw material in dissolving pulp production. The results of lower pentosan levels attributed to lower hemicellulose content, and higher S/G ratio were favorable in the dissolving pulp process. Moreover, the higher basic density of the wood chips resulting in higher screened pulp yield and achieved lower specific wood consumption have a huge positive economy. Additionally, it can lower the logistics cost. Hence, high basic density eucalyptus wood has good potential for future development and larger plantations.

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  • Bäck Westermark, Emmy
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Glad, Samuel
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Svinnanalys av gips2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The construction and real estate sector currently accounts for 40% of Sweden's waste. In theyear 2020, the industry generated 14.2 million tons of waste, a significant increase fromprevious years. Time constraints, lack of expertise, and insufficient resources for workersresult in material damage and waste during the planning, design, and production stages.The overall objective of this thesis is to conduct a current situation analysis of constructionsites, with a specific focus on investigating the amount of gypsum waste and the reasons for itsoccurrence. Through this analysis, a deeper understanding of material procurement andhandling on construction sites is sought. Additional goals include deepening knowledge in thefield and demonstrating correlations between procurement, handling, and waste throughcollected data. The aim is also to identify the factors contributing to material waste anddetermine the stage of the execution process where the waste occurs.The research questions addressed in this study are: What is the primary reason for gypsumwaste? In which stage of the execution process does the most gypsum waste occur?To answer these questions, interviews, a literature review, and site visits have been conducted.The work has been carried out in collaboration with Prolog, which is involved in the logisticalsolution for Barkarbystaden and has facilitated access to key individuals from the project forinterviews. Prolog has also shared comprehensive information about the Barkarbystadenproject, which has been beneficial for both site visits and interviews.Respondents unanimously agreed that gypsum waste primarily consists of scraps resultingfrom the need to cut gypsum boards to fit the wall. To maximize the reduction of gypsumwaste, solutions should be developed to minimize these scraps. Many of these scraps can bereused, but reusing them is not automatic, as they are often discarded extensively.Waste occurs during the production stage, but there are also opportunities for improvement inthe procurement stage. Differences in how procurement and waste management are handledwere observed after the interviews. Respondents shared the opinion that gypsum is notconsidered a necessary material for ordering in excess. Reusing, relocating, and returninggypsum are often deemed time-consuming and, therefore, costly. To encourage these activities,some form of reward should be introduced to make them more economically attractive thandisposing of gypsum.

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  • Fernández Schrunder, Alejandro
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electronics and Embedded systems.
    Huang, Yu-Kai
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electronics and Embedded systems.
    Rodriguez, Saul
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electronics and Embedded systems.
    Rusu, Ana
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electronics and Embedded systems.
    A Bioimpedance Spectroscopy Interface for EIM Based on IF-Sampling and Pseudo 2-Path SC Bandpass ΔΣ ADC2024In: IEEE Transactions on Biomedical Circuits and Systems, ISSN 1932-4545, E-ISSN 1940-9990, p. 1-13Article in journal (Refereed)
    Abstract [en]

    This paper presents a low-noise bioimpedance (bio-Z) spectroscopy interface for electrical impedance myography (EIM) over the 1 kHz to 2 MHz frequency range. The proposed interface employs a sinusoidal signal generator based on direct-digital-synthesis (DDS) to improve the accuracy of the bio-Z reading, and a quadrature low-intermediate frequency (IF) readout to achieve a good noise-to-power efficiency and the required data throughput to detect muscle contractions. The readout is able to measure baseline and time-varying bio-Z by employing robust and power-efficient low-gain IAs and sixth-order single-bit bandpass (BP) ΔΣ ADCs. The proposed bio-Z spectroscopy interface is implemented in a 180 nm CMOS process, consumes 344.3 - 479.3 μ W, and occupies 5.4 mm 2 area. Measurement results show 0.7 mΩ/√Hz sensitivity at 15.625 kHz, 105.8 dB SNR within 4 Hz bandwidth, and a 146.5 dB figure-of-merit. Additionally, recording of EIM in time and frequency domain during contractions of the bicep brachii muscle demonstrates the potential of the proposed bio-Z interface for wearable EIM systems.

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  • Lázár, Enikő
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab. Department of Cell and Molecular Biology, Karolinska Institute, 17165 Solna, Sweden.
    Mauron, Raphaël
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Andrusivova, Zaneta
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Gene Technology.
    Foyer, Julia
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Gene Technology.
    Larsson, Ludvig
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Shakari, Nick
    Department of Biochemistry and Biophysics, Stockholm University, Science for Life Laboratory, 171659 Solna, Sweden.
    Marco Salas, Sergio
    Department of Biochemistry and Biophysics, Stockholm University, Science for Life Laboratory, 171659 Solna, Sweden.
    Sariyar, Sanem
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Cellular and Clinical Proteomics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Hansen, Jan Niklas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Cellular and Clinical Proteomics. KTH, Centres, Science for Life Laboratory, SciLifeLab. Department of Bioengineering, Stanford University, Stanford, CA 94305, USA.
    Vicari, Marco
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Gene Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Czarnewski, Paulo
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Gene Technology.
    Braun, Emelie
    Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17165 Solna, Sweden.
    Li, Xiaofei
    Division of Neurodegeneration, Department of Neurobiology, Care Sciences and Society, Karolinska Institute, 17165 Solna, Sweden.
    Bergmann, Olaf
    Department of Cell and Molecular Biology, Karolinska Institute, 17165 Solna, Sweden; Department of Pharmacology and Toxicology, University Medical Center Goettingen, 37075 Goettingen, Germany; Center for Regenerative Therapies Dresden, TU Dresden, 01307 Dresden, Germany.
    Sylvén, Christer
    Department of Medicine, Karolinska Institute, 14157 Huddinge, Sweden.
    Käller Lundberg, Emma
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Cellular and Clinical Proteomics. Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Pathology, Stanford University, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, San Francisco, San Francisco, CA 94158, USA.
    Linnarsson, Sten
    Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17165 Solna, Sweden.
    Nilsson, Mats
    Department of Biochemistry and Biophysics, Stockholm University, Science for Life Laboratory, 171659 Solna, Sweden.
    Sundström, Erik
    Division of Neurodegeneration, Department of Neurobiology, Care Sciences and Society, Karolinska Institute, 17165 Solna, Sweden.
    Adameyko, Igor
    Department of Physiology and Pharmacology, Karolinska Institute, 17165 Solna, Sweden; Department of Neuroimmunology, Medical University of Vienna, 1090 Vienna, Austria.
    Lundeberg, Joakim
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Gene Technology.
    Spatial Dynamics of the Developing Human HeartManuscript (preprint) (Other academic)
    Abstract [en]

    Heart development relies on a topologically defined interplay between a diverse array of cardiac cells. We finely curated spatial and single-cell measurements with subcellular imaging-based transcriptomics validation to explore spatial dynamics during early human cardiogenesis. Analyzing almost 80,000 individual cells and 70,000 spatially barcoded tissue regions between the 5.5th and 14th postconceptional weeks, we identified 31 coarse- and 72 fine-grained cell states and mapped them to highly resolved cardiac cellular niches. We provide novel insight into the development of the cardiac pacemaker-conduction system, heart valves, and atrial septum, and decipher heterogeneity of the hitherto elusive cardiac fibroblast population. Furthermore, we describe the formation of cardiac autonomic innervation and present the first spatial account of chromaffin cells in the fetal human heart. In summary, our study delineates the cellular and molecular landscape of the developing heart’s architecture, offering links to genetic causes of heart disease.

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  • Sariyar, Sanem
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Cellular and Clinical Proteomics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Sountoulidis, Alex
    Science for; Laboratory, Solna, SwedenDepartment of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
    Hansen, Jan N.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Cellular and Clinical Proteomics. KTH, Centres, Science for Life Laboratory, SciLifeLab. Department of Bioengineering, Stanford University, Stanford, CA, USA.
    Marco Salas, Sergio
    Science for Life Laboratory, Solna, Sweden; Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden..
    Mardamshina, Mariya
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Cellular and Clinical Proteomics.
    Martinez Casals, Ana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Cellular and Clinical Proteomics. KTH, Centres, Science for Life Laboratory, SciLifeLab. Department of Bioengineering, Stanford University, Stanford, CA, USA.
    Ballllosera Navarro, Frederic
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Cellular and Clinical Proteomics. KTH, Centres, Science for Life Laboratory, SciLifeLab. Department of Bioengineering, Stanford University, Stanford, CA, USA.
    Andrusivova, Zaneta
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Gene Technology.
    Li, Xiaofei
    Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.
    Czarnewski, Paulo
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Gene Technology.
    Lundeberg, Joakim
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Gene Technology.
    Linnarsson, Sten
    Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.
    Nilsson, Mats
    Science for Life Laboratory, Solna, Sweden; Department of Biochemistry and Biophysisc, Stockholm University, Stockholm, Sweden.
    Sundström, Erik
    Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.
    Samakovlis, Christos
    Science for Life Laboratory, Solna, Sweden; Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; Molecular Pneumology, Cardiopulmonary Institute, Justus Liebig University, Giessen, Germany.
    Käller Lundberg, Emma
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Cellular and Clinical Proteomics. Department of Bioengineering, Stanford University, Stanford, CA, USA; Department of Pathology, Stanford University, Stanford, CA, USA.
    Ayoglu, Burcu
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Protein Science, Cellular and Clinical Proteomics.
    High-parametric protein maps reveal the spatial organization in early-developing human lungManuscript (preprint) (Other academic)
    Abstract [en]

    The respiratory system, encompassing the lungs, trachea, and vasculature, is essential for terrestrial life. Although recent research has illuminated aspects of lung development, such as cell lineage origins and their molecular drivers, much of our knowledge is still based on animal models, or is deduced from transcriptome analyses. In this study, conducted within the Human Developmental Cell Atlas (HDCA) initiative, we describe the spatiotemporal organization of lung during the first trimester of human gestation in situ and at protein level. We used high-parametric tissue imaging on human lung samples, aged 6 to 13 post-conception weeks, using a 30-plex antibody panel. Our approach yielded over 2 million individual lung cells across five developmental timepoints, with an in-depth analysis of nearly 1 million cells. We present a spatially resolved cell type composition of the developing human lung, with a particular emphasis on their proliferative states, spatial arrangement traits, and their temporal evolution throughout lung development. We also offer new insights into the emerging patterns of immune cells during lung development. To the best of our knowledge, this study is the most extensive protein-level examination of the developing human lung. The generated dataset is a valuable resource for further research into the developmental roots of human respiratory health and disease.

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  • Subasic, Nihad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Engineering Design, Mechatronics and Embedded Control Systems.
    Velander, Johanna
    Department of Computer Science and Media Technology, Linnaeus University, Sweden.
    What Do We Do With All the Data: Learning Analytics2023In: Book of abstracts: International Symposium on Digital TransformationAugust 21-23, 2023, Linnaeus University, Växjö, Växjö: Linnaeus University , 2023Conference paper (Refereed)
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  • Ronne, August
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Method for Automated Accessibility Testing of Web Application Components (AAT-WAC): Proposal for a Method for Automated Accessibility Testing of Web Applications Built Using a Component-based Architecture2024Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    It would be difficult to imagine the world we live in without the World Wide Web. We depend on it for communication, entertainment, transfer of capital, access to essential services, and many other things. Even though it feels like the Web is everywhere, its usage is still growing, and so is its importance. However, a significant portion of the world’s population is made up of people with disabilities, and if the Web and its content is not made accessible to them, they cannot participate in this integral part of modern society. Making sure that the resources we access through the Web are accessible to people with disabilities is a difficult task. Those who create applications for the internet need to test them to identify accessibility issues. Today, much of the content on the Web is divided into units called components. It would be advantageous if there was a method for automated accessibility testing of these components. The problem is that no such method exists. Components—in this context—refer to the parts that make up a webpage. When you are, for example, viewing a news article online, the heading could be a component, as could the comments section, and so on. A majority of the world’s webpages are constructed using this architecture, where a set of reusable components with different functionality make up the page you are visiting. The purpose of this thesis is to create a method for automated accessibility testing of these web application components. The goal is that the created method should be useful for web developers and testers in their work to create a Web that is more accessible for people with disabilities, and therefore contribute in some way to a more accessible society. The chosen research methodology was qualitative and exploratory, and followed the design science research-paradigm. The methodology consisted of four distinct phases, a literature study phase, a preliminary design phase, an evaluation of the preliminary design phase, and an improved design phase. The literature study phase laid the groundwork for creating a method proposal in the preliminary design stage. This method was then evaluated in the evaluation stage. This evaluation consisted of a partial implementation of the framework, together with interviews with respondents with relevant experience. Using this evaluation, an improved method was created in the improved design phase. The result of this thesis is the Automated Accessibility Testing of Web Application Components Method (AAT-WAC). The evaluations that were conducted proved that AAT-WAC method met all of the stipulated evaluation criteria, and that the method was useful when implemented in a real-world industrial context. The literature study proved that no other methods similar to the AAT-WAC method existed.

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  • Janetzky, Fredrik
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Wallin, Markus
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Low-code Performance Evaluation and its Impact on Software Development2024Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Low-code is a modern approach to software development and has grown rapidly in recent years. By hiding complexity behind layers of abstraction, it allows inexperienced developers to create complex applications in a shorter amount of time. This thesis sets out to evaluate the current state of low-code as well as a few of the available low-code development platforms and how well their finished applications perform. A simple order management system was implemented in three low-code development platforms, Mendix, OutSystems, and Airtable, in order to gain experience in all of them. The platforms were then evaluated with respect to user experience and performance. The created applications load time and memory usage were measured in three different tests. It was found that there are plenty of low-code platforms that exist for different purposes, and that they all have their own learning curve depending on how flexible they aim to be. The performance of their respectively created applications is also similar to each other, with the only major differences being by design.

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  • Adamsson, Johan
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Run-time specialization for compiled languages using online partial evaluation2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Partial evaluation is a program transformation technique that specializes a program with respect to part of its input. While the specialization is typically performed ahead-of-time, moving it to a later stage may expose additional opportunities and allow for faster residual programs to be constructed. In this thesis, we present a method for specializing programs at run-time, for compiled code, using an online partial evaluator. Although partial evaluation has several applications, the evaluation of the method primarily focuses on its performance benefits. The main research problem addressed in this thesis is that of incorporating an online partial evaluator in compiled code. The partial evaluator is a sourceto-source translator that takes and produces an abstract syntax tree (AST). Our approach consists of three parts, namely that of partially evaluating, obtaining a partially evaluable representation and run-time code emitting. Concretely, we use the concept of lifting to store an AST in the compiled code that the partial evaluator then specializes at run-time. The residual code is thereafter naively just-in-time (JIT) compiled through dynamically linking it back to the executable as a shared library. We evaluate the method on several programs and show that the specialized programs sometimes are faster even with a low recursion depth. Though, while the results are promising, the overhead is typically significant and therefore the break-even points are large. Further research, for example using an efficient JIT compiler, is required to better evaluate the performance benefits of the approach.

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  • Public defence: 2024-05-03 10:00 Kollegiesalen, Brinellvägen 8, Stockholm
    Mohammadi, Mohammad
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Risk Management in Tunneling Projects: Estimation and Planning2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cost overruns and schedule delays are frequently observed occurrences in the construction of transport infrastructure projects. Such phenomena lead to the mismanagement of significant amounts of both public and private resources.An examination of the literature reveals that uncertainty stands out as one of the potential primary causes of cost overruns and schedule delays. To address the impact of uncertainty on time and cost estimations in transport infrastructure projects, probabilistic approaches can be employed. 

    In this doctoral thesis, first a conceptual risk model has been formulated specifically for the purpose of enhancing time and cost estimations in tunneling projects. This risk model serves as a tool to scrutinize and contrast existing probabilistic time and cost estimation models for tunnel projects, aiming to identify potential areas for improvement. Furthermore, the conceptual model is utilized to delve into the factors influencing the accuracy of subjective assessments regarding the input parameters in time estimation models. It also explores methods for incorporating the role of tunneling phases into the subjective assessment of these input parameters.

    Then, enhancements and updates are introduced to the existingKTH model for time and cost estimation in tunneling projects. This model primarily targets three main sources of uncertainty: variability in construction performance, geological uncertainties, and the potential incidence of disruptive events. The analysis and improvements related to modelling of construction performance involve three sequential steps. In the first step, the construction process is modeled using the work breakdown structure (WBS), enabling a more realistic assessment of tunneling time. Subsequently, in the second step, PERT distributions are employed to model the uncertainty in the duration of unit activities, compared to the commonly used triangular distributions. The third step involves a detailed examination of a real tunnelling project's data to identify components contributing to construction performance variability for unit activities. This analysis pinpoints three main components: typical performance variability, minor performance delays, and minor machinery delays. These components are integrated into the KTH model, resulting in its further update concerning construction performance variability. 

    A novel approach is introduced into the KTH model by leveraging the Metropolis-Hastings (MH) algorithm within the framework of Markov Chain Monte Carlo (MCMC) simulation to address geological uncertainties along the tunnel route. This method facilitates round-by-round simulation of the tunneling process and allows the model to accommodate uncertainty in the critical path for tunneling projects involving multiple headings. These enhancements aim to improve decision-making processes and mitigate risks associated with schedule delays and cost overruns. Additionally, the magnitude of disruptive events are now modeled as stochastic variables, an improvement on the original version of the KTH model.

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    Kappa
  • André, Hampus
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Sustainability Assessment and Management.
    Opening the black box of the use phase in circular economy life cycle assessments: Environmental performance of shell jacket reuse2024In: Journal of Industrial Ecology, ISSN 1088-1980, E-ISSN 1530-9290Article in journal (Refereed)
    Abstract [en]

    Life cycle assessment (LCA) is highly needed and widely used to assess the environmental performance of circular economy (CE) measures such as reusing and sharing. However, the results of such LCAs are hampered by limited knowledge about the use phase of consumer products and oversimplification of important use phase aspects such as product functionality, user behavior, displacement, and rebound effects. This paper aims to validate the usefulness of a framework designed to assist practitioners in the generation and utilization of such knowledge in LCAs of circular measures. To validate the framework, a case study is used: reuse of shell jackets enabled by “premium secondhand” stores for outdoor equipment and clothing. The paper demonstrates that conclusions about the environmental performance of reuse can easily be altered depending on the functional unit definition, whether real user behavior data are used, and whether imperfect displacement and rebound effects are considered. For instance, shell jacket life cycles that include reuse and thus may be labeled “circular” have significantly higher environmental impact per use occasion than “linear” ones (used by one principal user the entire lifespan), since “circular” shell jackets are used less frequently, in particular during their first use span. Through facilitating the generation and utilization of environmentally relevant use phase data, which are otherwise often overlooked, the framework seems capable of supporting a better understanding of the environmental performance of CE measures.

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  • Lindenfors, Simon
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Engineering Design, Mechatronics and Embedded Control Systems.
    Rahmanian, Shaya
    KTH, School of Industrial Engineering and Management (ITM), Engineering Design, Mechatronics and Embedded Control Systems.
    Comparison of Linear Time Varying Model Predictive Control and Pure Pursuit Control for Autonomous Vehicles2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this project was to compare two control algorithms designed to steer an autonomous vehicle. The comparison was made using a simulated environment to evaluate the performance of both controllers. The simulation used in this project was designed in Python and used an algorithm which randomly constructed roads from predefined road segments to create paths for the vehicle to follow. In this environment the Linear Time Varying (LTV)-Model Predictive Controller (MPC) and Pure Pursuit Controller (PPC) algorithms were evaluated. The thesis compared how well they follow paths, the average control cost of completing tasks, how well they handle input constraints, and the computational time for each algorithm. The data was collected by driving along three sets of randomly generated roads with both control algorithms. One set mostly straight, one with some turns, and one with mostly turns. An Analysis of Variance (ANOVA) test was used to make the comparison between the performance of the two algorithms. The results showed that both algorithms performed well. The PPC had low computation time and used less control, but it also had larger position errors. The LTV-MPC had higher computation time, but smaller position errors at the cost of larger control values. The conclusion is that the MPC is preferable if computational capabilities are available. Room for future work exists in the form of comparing additional controller types for autonomous vehicles and exploring different tuning parameters for the MPC controller. The simulation could also be expanded to more accurately reflect real world conditions.

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  • Dincel, Seren
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Lighting Design.
    Besenecker, Ute
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Lighting Design.
    Koch, Daniel
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Urban Design.
    Zielinska-Dabkowska, Karolina M.
    Gdańsk University of Technology, Faculty of Architecture (GUT).
    Light formed through urban morphology and different organism groups: First findings from a systematic review.2024In: IOP Conference Series: Earth and Environment, ISSN 1755-1307, E-ISSN 1755-1315, Vol. 1320, p. 1-12, article id 012002Article in journal (Refereed)
    Abstract [en]

    The prevailing implementation and usage of contemporary lighting technologies and designpractices in cities have created over-illuminated built environments. Recent studies indicate that exposureto electric lighting effects formed through spatial characteristics has visual, physiological, andbehavioural effects on both humans and non-humans, such as wildlife. In order to gain a betterunderstanding of the impact that electric lighting has on space and different organism groups, acomprehensive literature review was conducted applying PRISMA 2020 systematic review guidelines.Results of the searches from various databases, such as Web of Science, PubMed and Scopus, identified5260 related studies. A total of 55 papers connected to four themes: (1) urban morphology; (2) humanvisual impressions; (3) ecological impacts; and (4) design approaches and methods were analysed with afocus on urban morphology. The review provided the following general findings: lighting propertiesalone are inadequate to depict visual impressions of pedestrians, patterns formed through light interactingwith spatial characteristics can contribute to understanding how spaces are visually perceived and helpcharacterising the exposure of wildlife organisms to potential disturbances.

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    Dincel_2024_IOP_Conf._Ser.__Earth_Environ._Sci._1320_012002
  • Wickberg, Adam
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History, History of Science, Technology and Environment. Max Planck Institute for the History of Science, Berlin, Germany.
    Gärdebo, Johan
    Department of History of Science and Ideas, Uppsala University, Uppsala, Sweden; Department of History and philosophy of science, Cambridge University, Cambridge, UK.
    Computation, data and AI in Anthropocene history2024In: History & Technology, ISSN 0734-1512, E-ISSN 1477-2620, p. 1-19Article in journal (Refereed)
    Abstract [en]

    This essay engages with recent scholarship on the epistemology of AI, data and automation, to assert how these practices are becoming increasingly central both to the projects of monitoring and of managing a global environment. We also review Jürgen Renn’s recent contribution The Evolution of Knowledge (2020) in relation to the history of environmental data. Using Renn as point of departure, we stake out a way for understanding the Anthropocene through the interaction between data and environment, taking into account the deeper political implications of datafication. We conclude with discussions about how historians of technology and environment could play an important role in assessing the opportunities and risks of AI for global environmental justice before their full-scale implementation is a fait accompli. In face of the Anthropocene, there is a general need today for integrative efforts of bridging knowledge from natural, technical, social and humanistic domains, and therefore a strong imperative for humanistic studies to transposetools, methodologies, and insights into the realms of policymaking, and legislation. Thus, assessments of AI and environment must account for these historical processes in the present as well as offer critical analysis of the full ontological spectrum from object to epistemology via data and mediation.

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  • Battah, Natalie
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Lysekil Center2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Now more than ever, we are exposed to the consequences of floods and their spatial implications. Climate change is one of the most dramatic global challenges of our time and is presenting a serious threat to even the most advanced coastal cities. 

    Lysekil is a municipality on the west coast of Sweden. Lysekil is surrounded by harbors and piers on all sides facing the sea. The Lysekil Center proposal is about rebuilding the existing fishmarket, but also having a natural meeting point for ferries, boats, cars and pedestrians. At the same time, a landscape has been designed with a focus on managing a sea level rise of 1.5 meters.

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  • Allvin, Karin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Ibrahim, Jimmy
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Entering the Hosh House2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This research project explores the Hosh house typology, a historic dwelling type in Baghdad facing rapid decline and extinction. The study critically examines historic documentation and employs a wide range of methods to expand knowledge and understanding of the Hosh house. By building an archive around selected architectural objects, the research provides insights in various fields, including architectural anthropology, heritage, craftmanship and sustainable construction. The study draws from scarce and dated documentation, providing new translations of German books on Iraqi architecture, while simultaneously questioning and challenging these findings. The study explores the reasons behind the disappearance of the Hosh house, including urbanization, preference for modern technology and social attitudes. The findings highlight the characteristics and layouts of the Hosh house, presenting the ideal and compromised versions of its design. It also incorporates contemporary sources, such as interviews with local enthusiasts, to fill knowledge gaps and provide a contemporary perspective on the vanishing architectural tradition. Overall, this project contributes to the understanding of the Hosh house's cultural significance within Iraqi architecture and cultural heritage, while emphasizing the need for updated sources and in situ inventories. 

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  • af Petersens, Ellen
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Öppet lager [Open Storage]2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thesis, Öppet Lager, (Open Storage) attaches a public structure to Moderna Museet’s off-site storage to bring together the showing and storing of art. As it is inevitable that large institutions cannot show their full collections, many of their works of art will be stored away from the public. Moderna Museet currently has 283 artworks on display at Skeppsholmen which is around 0.25 percent out of their collection of 140 000 pieces. As collections continue to grow the percentage of what is shown decreases, and the storage spaces fill up. To open the storages of art Öppet Lager addresses the conflict between showing and storing art and how objects could be displayed without compromising the administrative functions of transportation, conservation, and research. By proposing an alternative way to store art, the project aims to create greater access to works of art that would otherwise be sleeping deep in storages.

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  • Adamsone, Darta
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    The common ground workshop, caring for industrial heritage2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Historical hydroelectric stations are part of an aging industrial heritage that is still extremely relevant today through its form of generating energy. Many stations built in the 20th c. are categorized as architectural heritage, therefore protected against demolition or radical change, thus also a radical expansion that would allow to modernize the station and allow for bigger energy output. Viskafors power station in Borås (Sweden) built in 1917 for the former local textile factory,  is a small-scale power station that is marked as architectural heritage, currently owned by Vattenfall.  The town of Viskafors is one of many factory towns along the river and as the industry went bankrupt in the 1970-ties it has become a suburb to the city of Borås. The only public buildings in Viskafors are schools. The town once defined by the industry is now left with an inaccessible waterfront and plenty of unused and unattainable space.The former factory grounds and the restricted area around the hydroelectric station, railway and regional road block the waterfront.The latest station renovation happened in 2013, leaving the second floor and the lift tower empty. Forming another void in the total space that Viskafors has to offer.Can this void be used as leverage to explore the potential of formerly unattainable space within the station and in connection to the waterfront? Keeping this in mind, this thesis aims to find meaningful ways to inhabit and repurpose formerly unattainable space as it is today; to find methods of organizing complex landscapes; initiate a discussion of new thinking of potential hybrid scenarios for the complexities of our future settlements.Can the future be a link to the past and vice versa?The project space stretches from the street level approaching the building to the rooftop, extends into the empty space of the station's second floor, and continues over the other side of the river. The existing second-floor space dimensions are  33 m x 11m x 5.5 m forming a box space. In theory, a box space this size holds infinite potential as long as it remains empty and has no walls, this project aims to explore the method of placing programmed pavilions/interventions as a space-organizing method of work and extending the approach to the rest of the project site area.The aim is to keep the hydroelectric station running while inhabiting the empty space surrounding it, and learning how to live with it.

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  • van de Kamp, Carsten Thomas
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    Providing reliable product size recommendations -- A Bayesian model for sparse, cross-merchant sales and return data in fashion e-commerce2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fashion webshops face high return rates, which is both an unsustainable and very costly practice. A significant part of returns is made because of size and fit-related issues. We introduce four models for providing product size recommendations based on cross-merchant sales and return data. This data is typically highly sparse and noisy, making the development of a size recommendation system challenging. Moreover, we do not have access to fit feedback or the reason why a consumer made a return. We assess model performance on both a proprietary data set consisting of shoe purchases and a publicly available data set containing rentals of various categories of women's apparel. Our baseline model predicts the probability of fit for a specific consumer-article combination based on the average catalog size of all articles purchased and kept by that particular consumer. This model outperforms two more advanced models deriving true size variables for consumers and articles on both data sets. The fourth model we develop is a Bayesian size recommendation model, which is fitted with mean-field variational inference. It performs comparably to baseline on unseen data. However, it has the added benefit of being able to filter out low-confidence recommendations, such that higher performance can be achieved at the cost of a lower coverage level. All models show signs of overfitting to training data, and hence we recommend future research to focus on developing a variant of the Bayesian model with fewer degrees of freedom. Results suggest that such a model could be able to provide even better product size recommendations.

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  • Plonczak, Antoni
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    Explaining Turbulence Predictions from Deep Neural Networks: Finding Important Features with Approximate Shapley Values2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Deep-learning models have been shown to produce accurate predictions in various scientific and engineering applications, such as turbulence modelling, by efficiently learning complex nonlinear relations from data. However, deep networks are often black boxes and it is not clear from the model parameters which inputs are more important to a prediction. As a result, it is difficult to understand whether models are taking into account physically relevant information and little theoretical understanding of the phenomenon modelled by the deep network can be gained. 

    In this work, methods from the field of explainable AI, based on Shapley Value approximation, are applied to compute feature attributions in previously trained fully convolutional deep neural networks for predicting velocity fluctuations in an open channel turbulent flow using wall quantities as inputs. The results show that certain regions in the inputs to the model have a higher importance to a prediction, which is verified by computational experiments that confirm the models are more sensitive to those inputs as compared to randomly selected inputs, if the error in the prediction is considered. These regions correspond to certain strongly distinguishable features (visible structures) in the model inputs. The correlations between the regions with high importance and visible structures in the model inputs are investigated with a linear regression analysis. The results indicate that certain physical characteristics of these structures are highly correlated to the importance of individual input features within these structures.

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  • in 't Veld, Niels Floris Leonardus
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    Comparing two approaches of modelling fish harvesting strategies using optimal control2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Optimal control is a paradigm for solving optimization problems involving dynamical systems, which are to be controlled. It is able to solve fish harvesting problems, in which we want to optimize harvesting out-take by considering fishing as a control function that acts on the state of the dynamical system, which represents the growth of fish species in the environment. Other modelling aspects of optimal control are defining terminal costs and running costs, e.g. maximizing profit. We keep the terminal condition comparable for a different number of species. It is based on the initial population. By using the optimal control Hamiltonian and Pontryagin’s Maximum Principle we can calculate the optimal state trajectories corresponding to suitable optimal controls. The Hamiltonian is dependent on the state equation and the running costs. We present two approaches of modelling the running costs. An approach that is not directly translatable to the fish harvesting problem, but it leads to a smooth Hamiltonian, which greatly simplifies derivation and computation. The other, which is equivalent to maximizing profit, leads to a non-smooth Hamiltonian. This leads to jump-discontinuous derivatives needed for computation. We propose to regularize the derivatives of the Hamiltonian using suitable smooth functions, such that it is equivalent to regularizing the Hamiltonian directly. We give details for implementing both approaches up to systems of n competing species. After which we go into detail on algorithms and programming structure implemented. Finally, in modest numerical experiments, for one and two species, we show the relation between the optimal control and the terminal costs. But more interestingly, that the smooth Hamiltonian models are inadequate and regularized Hamiltonian models are the preferred choice. Intriguingly, the latter approach results in steady state solution, wherethe control acts as a stabilizer.

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  • Storkamp, Vendela
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Flemingsberg, Under Construction2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The project explores the possibilities for more sustainable urban development by studying the impact of construction sites on the living environment and public space. The project is focused on the area of Flemingsberg, which in the coming years will be in an extensive development period with a lot of planned new construction and infrastructure. The transformation is planned to last until at least 2050, and for residents and visitors to the area, this means a major intervention in the living environment. Where cranes, fences and excavated materials define the cityscape. To create a bridge through time, the project proposes built interventions for meeting places and focus on the existing needs in the area.The project thus surveys Flemingsberg in depth while trying to create architectural solutions that can be applied in similar situations where large building areas affect the living environment for a long time. All as part of a more socially sustainable urban development. 

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  • Lindeberg, Tony
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Computational Science and Technology (CST).
    Orientation selectivity properties for the affine Gaussian derivative and the affine Gabor models for visual receptive fields2024Report (Other academic)
    Abstract [en]

    This paper presents a theoretical analysis of the orientation selectivity of simple and complex cells that can be well modelled by the generalized Gaussian derivative model for visual receptive fields, with the purely spatial component of the receptive fields determined by oriented affine Gaussian derivatives for different orders of spatial differentiation.

    A detailed mathematical analysis is presented for the three different cases of either: (i) purely spatial receptive fields, (ii) space-time separable spatio-temporal receptive fields and (iii) velocity-adapted spatio-temporal receptive fields. Closed-form theoretical expressions for the orientation selectivity curves for idealized models of simple and complex cells are derived for all these main cases, and it is shown that the orientation selectivity of the receptive fields becomes more narrow, as a scale parameter ratio $\kappa$, defined as the ratio between the scale parameters in the directions perpendicular to vs. parallel with the preferred orientation of the receptive field, increases. It is also shown that the orientation selectivity becomes more narrow with increasing order of spatial differentiation in the underlying affine Gaussian derivative operators over the spatial domain.

    For comparison, we also present a corresponding theoretical orientation selectivity analysis for purely spatial receptive fields according to an affine Gabor model. The results from that analysis are consistent with the results obtained from the affine Gaussian derivative model,in the respect that the orientation selectivity becomes more narrow when making the receptive fields wider in the direction perpendicular to the preferred orientation of the receptive field.

    The affine Gabor model does, however, comprise one more degree of freedom in its parameter space, compared to the affine Gaussian derivative model, where a variability within that additional dimension of the parameter space does also strongly influence the orientation selectivity of the receptive fields. In this respect, the relationship between the orientation selectivity properties and the degree of elongation of the receptive fields is more direct for the affine Gaussian derivative model than for the affine Gabor model.

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  • Yelnyk, Volodymyr
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    RBF method for solving Navier-Stokes equations2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis explores the application of Radial Basis Functions (RBFs) to fluid dynamical problems. In particular, stationary Stokes and Navier-Stokes equations are solved using RBF collocation method. An existing approach from the literature, is enchanced by an additional polynomial basis and a new preconditioner. A faster method based on the partition of unity is introduced for stationary Stokes equations. Finally, a global method based on Picard linearization is introduced for stationary Navier-Stokes equations.

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  • Bosik, Geni
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Gergis, Fadi
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Identifiering och Klassificering av trafikljussignaler med hjälp av maskininlärningsmodeller: Jämförelse, träning, testning av maskininlärningsmodeller för identifiering och klassificering av trafikljussignaler.2024Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis explored the development of advanced machine learning models to improve autonomous transportation systems. By focusing on the identification and classification of traffic light signals, the work contributes to the safety and efficiency of self-driving vehicles. Areview of models such as the Single Shot MultiBox Detector (SSD), as an object detectionmodel, and InceptionV3 and VGG16, as classification models, was conducted, with particular emphasis on their training and testing processes.The results, in terms of validation accuracy and validation loss, showed that the InceptionV3model performed well across various parameters. This model proved to be robust and adaptable, making it a good choice for the project's goal of accurate and reliable classification oftraffic light signals.On the other hand, the VGG16 model showed varying results. While it performed well undercertain conditions, it proved to be less robust at certain parameter settings, especially at higherbatch sizes, which led to lower validation accuracy and higher validation loss.

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  • Granger, Etienne
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    Innovative KPIs for Web-based Building Energy Performance Monitoring in the Tertiary Sector2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today, energy monitoring webplatforms are increasingly numerous in the tertiarysector, especially due to recent French regulations which aim at reducingthe power consumption of office buildings. In order for these webplatforms tomake a difference, they need to deliver clear-cut messages to the users, throughrelevant key performance indicators (KPIs) adjusted to their will and supposed to"translate" information provided by massive data collected. However, most webplatformslike theWavePlatform by Smart Building Energies lack such customizedKPIs and if they have any, they only pay attention to energy consumption aspects,without even going into detail. In addition, with the growing development of IoTobjects, there are less and less buildings’ data that can’t be measured or collected.Consequently, this study dwells on the potential KPIs that could be displayed foroffice buildings on a common energy monitoring webplatform, i.e. theWavePlatform.KPIs about occupancy, comfort, power, plug loads and charging stationsare first described. Then, the study examines the potential of energy signaturesin terms of KPIs and energy consumption’s prediction. Finally, a connection ismade between thermal comfort (related to occupancy) and energy use : howmuch energy is used to reach a certain level of thermal comfort ? This analysis isinnovative because it sets on equal footing comfort (tightly linked to occupants’productivity, hence value creation) and energy use (synonym of waste of money).As a whole, the first steps were to make the most of theWavePlatform, using allits functionalities. Then, Excel was used as an optional tool if theWavePlatformcouldn’t help. All created KPIs have required both usages, underlining the possiblelimits of energy monitoring webplatforms. However, there is no doubt thatthese data collectors represent powerful tools with many improvements to come.Eventually, this study confirms the fact that it could be possible to help decisionmakers take well considered action through relevant KPIs adjusted to their officebuilding and their needs. Massive data are exploitable and full of meanings, onlyif they are rearrange in a way they can be impactful and clearly understandableby users.

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  • Lindeberg, Tony
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Computational Science and Technology (CST).
    Do the receptive fields in the primary visual cortex span a variability over the degree of elongation of the receptive fields?2024Report (Other academic)
    Abstract [en]

    This paper presents results of combining (i) theoretical analysis regarding connections between the orientation selectivity and the elongation of receptive fields for the affine Gaussian derivative model with (ii) biological measurements of orientation selectivity in the primary visual cortex, to investigate if (iii) the receptive fields can be regarded as spanning a variability in the degree of elongation.

    From an in-depth theoretical analysis of idealized models for the receptive fields of simple and complex cells in the primary visual cortex, we have established that the directional selectivity becomes more narrow with increasing elongation of the receptive fields. By comparison with previously established biological results, concerning broad vs. sharp orientation tuning of visual neurons in the primary visual cortex, we demonstrate that those underlying theoretical predictions, in combination with these biological results, are consistent with a previously formulated biological hypothesis, stating that the biological receptive field shapes should span the degrees of freedom in affine image transformations, to support affine covariance over the population of receptive fields in the primary visual cortex.

    Based on this possible indirect support for the working hypothesis concerning affine covariance, we formulate a set of testable predictions that could be used to, with neurophysiological experiments, judge if the receptive fields in the primary visual cortex of higher mammals could be regarded as spanning a variability over theeccentricity or the elongation of the receptive fields, and, if so, then also characterize if such a variability would, in a structured way, be related to the pinwheel structure in the visual cortex.

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  • Verhage, Billy
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    Evaluating volatility forecasts, A study in the performance of volatility forecasting methods2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, the foundations of evaluating the performance of volatility forecasting methods are explored, and a mathematical framework is created to determine the overall forecasting performance based on observed daily returns across multiple financial instruments. Multiple volatility responses are investigated, and theoretical corrections are derived under the assumption that the log returns follow a normal distribution. Performance measures that are independent of the long-term volatility profile are explored and tested. Well-established volatility forecasting methods, such as moving average and GARCH (p,q) models, are implemented and validated on multiple volatility responses. The obtained results reveal no significant difference in the performances between the moving average and GARCH (1,1) volatility forecast. However, the observed non-zero bias and a separate analysis of the distribution of the log returns reveal that the theoretically derived corrections are insufficient in correcting the not-normally distributed log returns. Furthermore, it is observed that there is a high dependency of abslute performances on the considered evaluation period, suggesting that comparisons between periods should not be made.

    This study is limited by the fact that the bootstrapped confidence regions are ill-suited for determining significant performance differences between forecasting methods. In future work, statistical significance can be gained by bootstrapping the difference in performance measures. Furthermore, a more in-depth analysis is needed to determine more appropriate theoretical corrections for the volatility responses based on the observed distribution of the log returns. This will increase the overall forecasting performance and improve the overall quality of the evaluation framework.

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  • van de Linde, Storm
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    Linear Eigenvalue Problems in Quantum Chemistry2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, a method to calculate eigenpairs is implemented for the Multipsi library. While the standard implemtentations use the Davidson method with Rayleigh-Ritz extraction to calculate the eigenpairs with the lowest eigenvalues, the new method uses the harmonic Davidson method with the harmonic Rayleigh-Ritz extraction to calculate eigenpairs with eigenvalues near a chosen target. This is done for Configuration Interaction calculations and for Multiconfigurational methods. From calculations, it seems the new addition to the Multipsi library is worth investigating further as convergence for difficult systems with a lot of near-degeneracy was improved.

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  • Staal, Dock
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    A divergence-free cut finite element discretization for the Stokes interface problem2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    We introduce a new, accurate, stable, and divergence-free cut finite element discretization for the Stokes interface problem. The method is based on the Brezzi-Douglas-Marini-elements (\textbf{BDM}-elements). We provide analysis to demonstrate that the proposed scheme results in a pointwise divergence-free velocity field, and we prove consistency, continuity, coercivity, and an inf-sup result. 

    Additionally, we present three numerical experiments that support the theoretical results. We utilize the element pair $(\textbf{BDM}_1, Q_0)$, that is, \textbf{BDM}$_1$-elements for the velocity and piecewise constant polynomials for the pressure. These numerical experiments show that the method is robust and attains an optimal convergence order of two for the velocity and one for the pressure

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