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Impedance measurement techniques for DC-biased systems
(2025) Henriksson
Abstract This thesis compiles information about six methods for impedance measurement of DC biased systems. It describes a physical interface for low-voltage Devices Under Test (DUTs) using the shunt-through method with DC-blocking capacitors. The interface is used to measure impedance versus frequency of three pouch cells of different dimensions and chemistries. In addition to the cell measurements, a separate set of measurements are carried out on inductors and capacitors with and without the use of the DC-blocking interface. The measurements show how parameters such as heat, conductor length and measurement setup affect the measured impedance. An interface model is presented that explains in what frequency and DUT impedance ranges each parasitic interface parameter affects the measurement results, and in what way. The conclusion of the thesis is that the used capacitor-based impedance measurement method was not accurate when measuring the low impedance of an electric vehicle battery cell. However, with the modification and improvements outlined in the thesis, the interface type could be used to measure devices with larger impedance, such as a complete high voltage electric vehicle battery consisting of the same cells.
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The evaluation of sufficiency strategies in the building sector using life cycle assessment
(2025) Eriksson, Lina
The building sector has a monumental impact on the planet’s environmental state. Despite ongoing efforts, emissions are growing, partly due to increasing consumption, where resource improvements are consumed by expenditure. Efficiency and renewables through technology and sustainable resources cannot reduce the impact of growing demand without a decrease in overall consumption. In recent years, sufficiency has been highlighted as a mitigation strategy with great potential to reduce the environmental impact of the built environment. However, there are few clear examples of definite strategies in the building sector. Furthermore, many building sustainability frameworks include a life cycle assessment, but the result is typically presented as total impact per m2. This makes sufficiency problematic to evaluate, as the main strategies for the building sector are to reduce impact by reducing building and unit size, material demand, and energy consumption. There are currently few examples of sufficiency in LCA, and none are related to the building sector. For sufficiency to be successful in the building sector, the effect of the strategies needs to be quantifiable by LCA, as this is a prevalent method within sustainability and building performance analysis. This thesis explores how LCA can be applied to estimate the effect of sufficiency strategies within housing. The study implements the idea of Sufficiency LCA, using a sufficiency functional unit along with the conventional functional unit, evaluating possible measurements and the effect of strategies. Furthermore, the influence of functional units is studied by testing various units that could change the perception of the building’s impact and provide a more holistic assessment. The thesis concludes that a comparison to show the impact saved is required to evaluate sufficiency. One option is through an additional functional unit measuring the savings effect (a sufficiency functional unit), which is most effective for sufficiency strategies regarding unit sizes and functions. The second option is comparative analysis with other products, which works better for strategies concerning material use. Furthermore, including area per capita or capita as a functional unit would better present the function and size of a building, along with highlighting crucial sufficiency strategies, such as density and co-living. Moreover, multiple trade-offs can be seen between embodied and operational emissions and between production, maintenance, and end-of-life stages for materials.
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Chalmershindret 2025
(2025) Anton, Emelie; Ekvall, Hanna; Jacobsson, Petter; Koningen, Ellen; Lindvall, Lina; Nilsson, Ida; Rapp, Johanna; Rosén, Victoria; Sjöblom, Alicia; Westberg, Ellen
Chalmershindret är ett årligt projekt i samarbete mellan Chalmers tekniska högskola och Göteborg Horse Show, där studenter utvecklar mätteknik för att analysera ekipagets prestation i hästhoppning. Årets projekt syftade till att mäta tiden över och mellan hinder med hjälp av geofoner som mäter markvibrationer. Utifrån vibrationsdata tränades en AI-modell för att identifiera avstamp och landning vid ett hinder. Projektgruppen delades in i en teknikgrupp samt en PR- och designgrupp. Teknikgruppen utvecklade mätutrustningen, medan PR- och designgruppen fokuserade på publikupplevelse, marknadsföring och hinderdesign. Projektet avslutades med mätningar och publikaktiviteter på Göteborg Horse Show 2025. Resultatet av mätningarna visade på vissa brister i AI-modellens tidsuppskattningar, och det kunde konstateras att mer träningsdata hade behövts för pålitligare resultat. Därför kompletterades mätningarna under Göteborg Horse Show med manuell tidtagning. Däremot visar vibrationsteknik potential för att i framtiden kunna bli ett användbart och effektivt analysverktyg för att mäta mellantider och tid i luften.
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Study of the effect of additives on the adsorption and antibacterial properties of cellulose-based composites
(2025) Magnusson Rune, Jessika
Air pollution, especially indoors, presents a need for air cleaning technologies to mitigate hazards of particulate matter, poisonous gases and biological contaminants. For removal of gaseous pollutants, such as VOCs, the most common method is adsorption using adsorbents. The company Adsorbi produces a novel adsorbent which, compared to the current standard adsorbent activated carbon, has a higher adsorption capacity and a more reliable uptake. To improve chemisorption, the material is functionalized with an additive in the form of an amine-based polymer. However, this additive is of fossil origin, which raises environmental concerns and the need for replacements. In this project, four alternative, more sustainable amine-based additives - chitosan, graphitic nitride, gelatine, and dodecyl dipropylene triamine (henceforth referred to as Y-amine) - were incorporated into Adsorbi's material, separately and in combination with the original additive and using three different methods of addition. The production involved granulation - a method of mixing dry powder with a liquid binder to form granules. The resulting prototypes were subsequently evaluated in terms of size distribution, bulk density, pollution and moisture uptake using a gravimetric study, and microbial properties using disk diffusion and broth dilution assays. All prototypes adsorbed the VOC acetaldehyde, with variations in adsorption capacity, adsorption rate, and saturation time. These variations are attributed to (i) the diverse chemical reactivity of the additives - mainly to the presence of primary amines - and (ii) the different bulk densities of the granules. Higher reactivity resulted in increased adsorption rates and higher bulk densities resulted in shorter saturation times. Increase in viscosity or volume of the liquid binder produced larger granules and varying compositions resulted in different bulk densities, highlighting the importance of production procedure. Microbial evaluations gave contradicting results. When submerged in growth media, the adsorbents exhibited antibacterial properties, which is attributed to leaching of two material components identified as antibacterial in their raw form. Both Y-amine and the original amine-based additive have antibacterial properties, the effects of which are apparent in the disk diffusion assay. The Y-amine prototypes in the broth dilution, unexpectedly, exhibited growth, which is attributed to the inherent variability of live bacteria, susceptibility testing and contaminated materials. Although the procedure needs to be optimized, the results suggest all alternative additives evaluated, particularly Y-amine, chitosan, and graphitic nitride, can be successfully incorporated into Adsorbi's material, producing functional adsorbents.
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