Chalmers Open Digital Repository
Välkommen till Chalmers öppna digitala arkiv!
Här hittar du:
- Studentarbeten utgivna på lärosätet, såväl kandidatarbeten som examensarbeten på grund- och masternivå
- Digitala specialsamlingar, som t ex Chalmers modellkammare
- Utvalda projektrapporter
Forskningspublikationer, rapporter och avhandlingar hittar du i research.chalmers.se
Enheter i Chalmers ODR
Välj en enhet för att se alla samlingar.
Senast inlagda
Post
Cyclic carbonates as green reactants for improving thermoplastic properties of lignocellulosic materials
(2023) Tansatien, Rattanapon; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Larsson, Anette; Henrik-Klemens, Åke; Jonasson, Katarina
Lignocellulosic materials are attractive raw materials for producing thermoplastics with more sustainable
manufacturing. They come from a renewable source that can reduce the dependency on
conventional fossil-based feedstock and has good tensile properties. However, their polymeric chains
have poor mobility because of the multiple hydrogen bonds of their hydroxyl groups, which is an essential
obstacle for thermoplastic processing. To improve their thermoplasticity, their hydroxyl groups can
be converted by chemical modifications that introduce the side groups that can increase the flowability
of their chains. In this study, unbleached softwood kraft pulp was oxyalkylated with cyclic carbonates
(propylene carbonate and ethylene carbonate), acting as a reactant and medium. These two reactants
create low environmental impacts because of their biodegradability and low toxicity. In addition, they
are also safer compounds from their high boiling point, flash point, and vapor pressure. The influence
of temperature, catalysts, and reaction time were investigated. The molecular structures, purity, and
thermal properties of the modified products were also evaluated. The chemical modification with ethylene
carbonate provides the highest yields and appears to be the most effective pathway to substitute
hydroxyl groups with the alkyl side chains. In addition, the products from the chemical modifications
with ethylene carbonate have a higher purity and are easier to separate than the products from the
chemical modifications with propylene carbonate. Increasing the temperature and amount of catalyst
promotes the substitutions on the hydroxyl group. Finally, the modified pulp from chemical modification
with ethylene carbonate at a higher temperature and amount of catalyst has better thermal
properties than the unmodified pulp. The glass-transition temperature (Tg) of the modified pulp can
be detected at approximately 180 °C while the Tg of its raw material is above 220 °C, so the polymeric
chains of modified pulp become more flowable.
Post
In situ synthesis of gold nanorods on SiO₂-substrates
(2023) Wilson, Sean; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Andersson, Martin; Hulander, Mats; Uusitalo, Maja
The implantation of a medical device introduces a high risk of infection and bacterial
biofilm formation on the device surface. These biomaterials-associated infections
(BAI) are difficult to treat using conventional methods, such as high dosages
of antibiotic treatments, as the bacteria are protected by the biofilm. A promising
treatment is to modify the implant surfaces with gold nanorods, which can photothermally
eradicate bacteria beneath the biofilm with heat generated from localized
surface plasmon resonance (LSPR). As such there is a need to develop methods that
reliably produce gold nanorods of a size that produces LSPR at wavelengths within
the biological window and that stably bind the particles to the material surface homogeneously.
In this thesis, a method has been developed to grow gold nanorods in situ on
SiO2-glass and silicon wafers by binding gold nanoparticle seeds to surfaces using
(3-Mercaptopropyl)- trimethoxysilane (MPTMS) as a linking molecule. The seeds
were then grown into rods using a modified growth solution. The method has also
been adapted to surface sensitive analysis to demonstrate the increased possibility
to study anisotropic nanoparticles this method brings. In situ quartz crystal microbalance
(QCM-D) analysis was used to study the formation of the self-assembled
monolayer of MPTMS, the chemisorption of gold nanoparticle seeds, and how the
growth rates of the particles vary over time, possibly due to both their increasing
size as well as variations in solution concentrations.
The developed method produced nanorods with a demonstrated rod yield of ~69%
directly on SiO2-glass surfaces. The rods had an aspect ratio (AR) that could
be customised to tune the wavelength of LSPR. The ability to tune the optical
properties of the rods could allow this method to be used to grow gold nanorods for
other applications, such as sensing, as well. Here the tuning was used to demonstrate
the effect of silver ions within the growth solution and to produce nanorods with
LSPR at the near infrared (NIR) wavelength of ~800nm in the biological window.
Post
Bielliptic surfaces and their geometry
(2024) Liu, Xudong; Chalmers tekniska högskola / Institutionen för matematiska vetenskaper; Eriksson, Dennis; Eriksson, Dennis
Geometry is a high concern in modern mathematics. One way to begin the study
is by handling a nice example. The bielliptic surfaces can play such a role. It is
constructed using elliptic curves, some nice curves in some way equivalent to a torus.
The prerequisites of bielliptic surfaces involve algebraic geometry and elliptic curves.
The final result is about the intersection of bielliptic surfaces, so the intersection
theories of surfaces will also be introduced. Works of classification and works of
Néron-Severi lattices are crucial for the study of bielliptic surfaces in the last section.
Algebraic geometry focuses on the method of solving geometry problems in algebraic
ways. The fundamental of the study is abstract algebra. It studies curves,
surfaces, and some other higher-dimension objects like hyperspaces. The key point
is describing geometry structures by zeros of polynomials. Many results are derived
over the complex field, where many nice properties can be found.
The elliptic curve is a kind of algebraic curve of genus one. Weierstrass equations are
the algebraic forms of elliptic curves. The composition law defines an operation on
the elliptic curves. Another important property is that the lattices over the complex
field determine the elliptic curves, which can be derived from the construction of the
Weierstrass ℘-function. Isogenies are introduced as the maps between elliptic curves.
The topic of intersection theory on surfaces concerns the intersection number of two
curves on the given surface, which is the number of intersection points counted with
algebraic multiplicity. The definition of intersection number can be generalized to n
varieties in high dimensions. In the article, the situation of two curves on a surface
is enough. One important result is Bézout’s theorem, a theorem of the intersection
number of plane curves.
The definition of bielliptic surfaces is based on the elliptic curves. With all the
knowledge before, the final result about the intersection number of bielliptic surfaces
can be given.
Post
Fault Tracing Bot in Electric Drive Software Using Machine Learning
(2023) Jai Prakash, Soundarya; Gopinath, Hariharan; Chalmers tekniska högskola / Institutionen för elektroteknik; Eriksson, Thomas; Farsi, Mohammad
The Electric Drive Software Continuous Deployment (EDCD) team at Volvo Car Corporation is working towards figuring out the automation of the analysis of the build log data obtained as a result of the continuous software integration for Electronic Control Unit (ECUs) using Machine Learning. Machine Learning is expected to be used in building a fault tracing bot, whose main goal is to analyse the provided log data and find the underlying meaning or information through it with minimum or zero human interaction. As this is an ongoing process and the creation of such log data will never really end, this project could make it easier for the analysis of big projects in getting instant data. At first, we are working on the data cleaning and the preprocessing of the big unstructured log data, followed by the labeling of the data by the clustering process. Lastly, the machine learning algorithm is used to predict the classification of the newly fed data. Many different machine learning algorithms have been implied to compare and get the best accuracy predicting algorithm among them.
Post
User Centered Concept Development of a Hybrid Ski Binding
(2022) Ohlslöf, Anton; Ågren, Hampus; Chalmers tekniska högskola / Institutionen för industri- och materialvetenskap; Chalmers University of Technology / Department of Industrial and Materials Science; Almius, Håkan; Sannes, Patrik
Abstract
The aim of this study was to understand the strength and weaknesses of current hybrid ski
bindings, based on user centered research and benchmarking. Further on, to develop a high
performance binding concept, based on the identified market gaps and user insights. After
the conducted research a thorough market analysis and user segmentation could be
presented. These results were further synthesized into a product statement explaining what
the design concept set out to achieve:
The product should be a trustworthy and robust solution that provides the user with
full alpine performance and touring possibilities. Through a transparent construction
and self explanatory interactive features, the user should be able to seamlessly
switch between ride modes and spend as much time as possible skiing.
The resulting concept is in essence an alpine binding toe piece with a modular pintech
attachment positioned on top. It is a product with a separation of functions that embodies the
need for robustness and ease of use found throughout the research. Positive aspects of the
design are the low Stack height in Ski mode, multi-directional elasticity and easy changing of
modes. While the negatives are the high stack height in touring mode along with the
exposed pintech attachment in ski mode. The conclusion was therefore drawn that the
proposed solution is a viable option to bring to market, but the stack height in touring mode
needs to be further evaluated along with prolonged durability testing of a prototype strong
enough for the slopes.
4