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User-focused App Development for Räddningsmissionen Application for donations from companies
No full textThe project is revolved around an mobile app called “ResursRätt” by Räddningsmissionen. The app allows companies to donate residual products that Räddningsmissionen then sells for a low price in their stores. The app collects information on what is donated and how the delivery of said products will be done. Räddningsmissionen either picks up the delivery or the companies delivery it to their warehouse. The goal of the project is to improve the user experience of the app, this is done through a user study where different potential users are interview. Users also got to test the original app and express their opinions of it. The users inputs where then used in creating different concepts and prototypes. The prototypes where made in Figma before moving on to coding the final version of the new app. The users also got to try the prototype and give inputs that where implemented in final version. The final result of the project landed in a more improved upon UI that is more efficient and practical than the original version
Investigation and optimization of photonic molecule microcombs with low repetition rates
No full textFrequency combs are a key technology for many applications, such as optical clocks,
precision spectroscopy, and wavelength division multiplexing (WDM) in optical communications.
Integrated frequency combs leveraging the Kerr nonlinearity can operate
with milliwatt-level pump powers, though their conversion efficiency (CE) typically
remains below 10%. In recent years, photonic molecules have been introduced
to overcome the problem of generally low CE observed in microcombs. Reported
efficiencies have exceeded 50% by transitioning from single cavities to photonic
molecule configurations. To date, these levels of CE have only been demonstrated
for microresonators with an FSR of 100 GHz. For low FSR photonic molecules, this
improvement is challenging due to higher intrinsic losses and a power distribution
across a larger cavity volume. In this thesis, we used Ikeda map-based simulations
to identify critical design parameters for achieving higher CE in low FSR configurations.
We characterized existing chips and compared measured comb spectra with
simulations to extract key parameters and quantify the currently achievable CE for
different FSRs. This data was used to analyze the influence of multiple parameters
on the CE, including coupling factors, input power, and comb detuning. Based
on these investigations, we developed improved parameter sets for microresonators
with repetition rates of 25 GHz and 50 GHz. The simulated CE increased from 25%
(simulation of existing devices) to over 45% for the 25 GHz design. For the 50 GHz
design, we present a parameter set that achieves a CE of over 65%. These CE values
can be achieved over a range of commonly used input powers in the milliwatt
regime. Our results demonstrate the potential to design photonic molecules with
tailored FSRs, enabling greater flexibility across applications
Sensor fusion med LiDAR för antispinn till Chalmers Formula Students bil
No full textI detta arbete presenteras en implementation samt framtagande av ett antispinnsystem för autonomkörning av Chalmers Formula Students bil. Implementationen bygger på ett ROS2-nätverk som exekverar python, C++ och C-kod i en integrerad dator. Metoden bygger på att skatta en markhastighet från LiDAR data, vilket bearbetas tillsammans med hjulhastigheten och IMU-data för att beräkna glidfaktorn. Detta skickas till ett reglersystem för att justera vridmomentet med målet att nå den optimala glidfaktorn för maximal acceleration. Resultaten visar att markhastighet kan estimeras från LiDAR-data och därefter beräkna glidfaktorn. Slutsatsen av projektet är att ett antispinnsystem kan baseras på LiDAR-odometri
Förvaringsanordning för strålskyddsprodukt mellan operationer
No full textMasterPeace is a radiation protection product used during minimally invasive surgeries to reduce healthcare staff’s exposure to ionizing radiation. Currently, there is no dedicated storage system for this product, which this thesis aims to investigate. The project was carried out in collaboration with Texray AB and was based on study visits,
including observations and interviews with healthcare professionals at Sahlgrenska Universitetssjukhuset and Hallands Sjukhus Varberg. Following this, idea and concept
generation was conducted to develop a solution that improves the working environment and workflow by simplifying the handling and storage of MasterPeace. Evaluation methods were then used to select a concept, which was further refined and optimized in dialogue with users. To ensure stability, calculations were also performed on the final concept.
The result is a mobile stand that stores MasterPeace with the flexibility to be repositioned for space optimization in the operating room. MasterPeace is hung using eyelets located in the corners of the product, which simplifies handling and improves drying capability. The final concept thus contributes to a more ergonomic, time-efficient and simplified use of MasterPeac
Hemp matters; exploring the architectural potential of hemp and lime materials in Sweden
No full textThe building industry has a significant and
undeniable impact on the environment,
characterized by high energy consumption,
harmful chemical pollution, and waste
generated from non-renewable resources.
Hemp Matter(s) focuses on hemp-lime, one
of many biomaterials with the potential to
provide innovative, durable, and ecological
alternatives to conventional building systems,
ultimately supporting the development of
more resilient architecture. This exploration of
hemp-lime’s architectural potential in Sweden
examines the material’s life cycle, using
circularity as a guiding principle for creating
sustainable built environments.
The research began with the question: How can
hemp-based materials help architecture move
towards more sustainable and regenerative
practices? A literature review helped build
foundational knowledge of the constructive
properties of hemp-lime while identifying
issues and challenges related to its use. A
collaboration with the Swedish company
EVIA provided experience-based insights and
helped bridge the gap between architectural
design and construction processes
throughout the research. The production of
samples was followed by laboratory testing,
which yielded data on the material’s thermal
and mechanical performance. Additional
findings highlighted the multiple benefits of
hemp as a rotational crop, including improved
soil structure and CO2 sequestration. Hemp’s
supply chain shows potential for supporting
the regional economy by being locally grown,
processed, and manufactured. Moreover, the
insulation material fosters circularity, as it can
be reused, recycled, or biodegraded.
These findings were applied in a design
proposal for a showroom located in Lindome,
at EVIA’s production site. The project explores
the architectural expression of hemp-lime,
and its modest scale allows for detailed
design of construction elements. It presents
replicable and adaptable solutions based on
prefabricated wall panels.
Hemp Matter(s) aims to shine a light on
the re-emergence of hemp as a reliable,
sustainable, and beautiful building material,
while hopefully contributing one more small
step towards a healthier and more resilient
society
Evaluation of Electric Heater Performance in Exhaust Aftertreatment Systems
No full textIncreasingly stringent vehicle emission standards call for improved performance of exhaust aftertreatment systems. A common problem is emissions during cold starts when the exhaust temperature is not sufficient to heat up the catalysts to operating conditions. Traditionally, this challenge is met by supplying additional exhaust heat using engine-based thermal management techniques by injecting additional fuel or decreasing engine efficiency. However, these techniques come with penalties such as increased fuel consumption and noise. An alternate solution is to use an electric heater to heat up the exhaust gases flowing into the catalysts. This can provide a large amount of heat close to the catalyst to enable them to reach operating temperatures quickly.
This study investigates the performance of an electric heater installed upstream of the silencer in a 380 hp 13-liter heavy-duty diesel engine. Tests in an air flow rig, an engine test cell were complemented with 1D simulations to evaluate catalyst heating performance, reduction of nitrogen oxides and energy consumed by the heater in steady and transient cycles. A major finding in this study was the effect of flow maldistribution limiting the effectiveness of the heater and the aftertreatment system. 1D models were found to be useful in testing different test cases but are challenged by flow maldistribution into the aftertreatment system.
The results show that a 10 kW heater works to improve nitrogen oxide emissions but need to be used in combination with engine modes that have low nitrogen oxide emissions. The performance of the system was also found to be significantly affected by the installation by heat losses in the exhaust flow
Realistisk träningsdata med 3D Gaussian Splatting: Bygga digitala tvillingar för generering av ground-truth-data i Unreal Engine 5
No full textModerna industrimiljöer blir alltmer komplexa och automatiserade, vilket ökar behovet av autonoma robotar för intern logistik. För att dessa robotar ska kunna arbeta effektivt och säkert krävs högkvalitativ träningsdata. Framtagningen av sådan data har traditionellt sett varit en resurskrävande process.
Detta kandidatarbete utvärderar, som ett ’proof-of-concept’, potentialen hos 3D Gaussian Splatting (3DGS) för att skapa fotorealistiska digitala tvillingar av industriella miljöer. Syftet är att från dessa tvillingar automatiskt generera syntetisk ground-truth-data.
Metoden innefattade fotografering av verkliga industrimiljöer (AB Volvos fabrik i Tuve, Chalmers produktionssystemslabbet) och skapande av 3D Gaussian Splatting modeller. Efter importering till Unreal Engine 5 utvecklades funktionalitet som simulerade scenarion och automatiskt genererade bildpar bestående av en simulerad vy och en motsvarande segmenteringskarta för semantisk segmentering.
Resultaten visade att 3D Gaussian Splatting kan producera detaljerade digitala tvillingar, trots viss kvalitetsförlust vid import till Unreal Engine 5. Den automatiska datagenereringen var effektiv och producerade syntetisk data som möjliggjorde träning av en segmenteringsmodell. Modellen kunde klassificera objekt i verkliga fabriksbilder, om än med vissa identifierade begränsningar.
Slutsatsen är att 3DGS är en lovande teknik för att effektivisera framtagning av träningsdata. Trots utmaningar med bildtagning och bristande stöd för 3DGS i Unreal Engine 5 visar arbetet att den undersökta metoden är lovande för att underlätta utvecklingen av avancerade maskinlärningsmodeller
RANS-based aerodynamic optimization of a pickup truck: performance assessment and verification of add-on improvements
No full textPickup trucks represent a significant share of the global automotive market yet
remain characterized by poor aerodynamic efficiency due to their inherent bluffbody geometry. This study investigates the aerodynamics of a generic double-cab
pickup truck, in two configurations: the open and closed bed, using steady state
RANS turbulence model and wind tunnel validation. Three turbulence models,
Realizable k − ε, Lag EB k − ε, and SST k − ω were evaluated against experimental
data to determine the most accurate approach for predicting drag trends across
configurations. The Lag EB k−ε model demonstrated superior fidelity in predicting
∆CD trends and was selected for the baseline flow topology study and optimization
phases. The baseline flow topology analysis identified various critical sources of
drag and the generation of a distinct pair of counter-rotating vortex that negatively
impacts the drag generation. Several aerodynamic add-on devices were designed
and assessed, including a sealed cabin-bed gap, a shortened tailgate, and a rearcab spoiler. Results indicate that sealing the cabin-bed gap yields a drag reduction
of approximately 2.0%. The optimal configuration, combining the gap seal with
the spoiler, achieved a drag reduction of 3.2% for the open bed configuration and
2.4% for the closed bed configuration. These findings demonstrate that targeted
management of the cabin wake and gap flow can significantly mitigate form drag
without altering the primary vehicle architecture
Evaluating the Impact of Compression on Inverted Index Search Engine Performance
No full textEfficient compression of inverted indexes is vital for scalable search engines, yet the literature lacks a comprehensive comparison of both modern integer-specific and dictionary-based codecs. This thesis bridges that gap by integrating VarByte, Simple8b, FOR, PFOR/NewPFOR/FastPFOR alongside LZ4, Snappy, and Zstandard into Apache Lucene Core and rigorously benchmarking their impact on compression ratio, indexing throughput, and query latency. Our systematic evaluation uncovers the distinct trade-offs — integer codecs tend to enable faster indexing at the expense of larger footprints, while dictionary schemes offer stronger space savings with moderate latency overhead. Finally, we distill these insights into a lightweight decision-support selection tree that guides practitioners to the optimal codec choice based on their specific application priorities. Keywords
