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Cykeln i centrum; en bristanalys utifrån tillgänglighet, kvalitet och säkerhet
No full textAtt främja hållbara transportmedel i svenska städer har blivit en större och viktigare
punkt i dagens samhälle och fler satsningar genomförs för att främja cykeltrafik. I
Kungsbacka ska kommunen anlägga en ny evenemangsarena i innerstadens södra del,
som staden identifierat som en målpunkt för kommunens växande befolkning. Inför
detta arbete har kommunen uppmärksammat att innerstaden behöver utvecklas, både
för att möta de utmaningar som en ökad mängd cyklister innebär samt för att bli mer
cykelvänligt för att också uppmuntra fler till att välja cykeln som transportmedel.
Detta arbete redogör de brister som förekommer i cykelinfrastrukturen i Kungsbackas
innerstad. Arbetet inleddes med en litteraturstudie vars syfte var att ta reda på tre vanligt
förekommande bristande aspekter, som bestämdes till: tillgänglighet, kvalitet och
säkerhet. Litteraturstudien stod även som grund för resterande metoder i form av
observationer, en enkätundersökning och GIS-analyser. Resultatet från dessa metoder
visade brister inom alla tre valda aspekter. Enskilda brister från de olika aspekterna
visades även hänga ihop med varandra. I slutet presenteras åtgärder som kan
implementeras i Kungsbacka, eller liknande orter, för att förbättra de brister som
förekommer i Kungsbackas innerstad
Renaturalization factory; participatory fabrication of nature
No full textAs a result of rapid urbanization
certain challenges have increased such
as environmental pressure and social
exclusion. This calls for sustainable
ways of dealing with continuous city
expansion. Evenemangsområdet is
at the center of discussions about
how Gothenburg should expand but
the municipality’s proposal has been
critiqued not least because of its
exclusive process and its ignorance
towards local ecological values.
The objective of this thesis is to
explore possible futures for a site
within Evenemangsområdet by
speculating about how that site could
become renaturalized through citizen
engagement. The site is currently
underused, both from a human and
nonhuman perspective, meaning that it
provides little value to either group.
The research is qualitative and partially
speculative. Through a case study
analysis, mapping of opportunities,
and speculative design, the thesis
focuses on social and ecological
sustainability, and alternative
tools for urban designers through
the following themes: human and
nonhuman actors, temporary activation,
disruptive architecture, wilderness,
renaturalization, speculation, scenario,
prototyping, participation, and
alternative mapping.
The site analysis focuses on social,
cultural and ecological aspects
and makes out the foundation for
the speculative design proposal
that follows. It focuses on the two
local assets that frame the site:
Stora Katrinelund landeri and
Mölndalsån. The thesis results in
a speculative design proposal of a
temporary activation project – the
Renaturalization Factory. With a
common mission to renaturalize the
site, people could mobilize around the
Garden Cart, a prototype that facilitates
collective gardening. The goal of the
factory is to convert asphalted areas
into a renaturalized landscape. The
activation would be the operation of the
factory.
As the Anthropocene makes itself heard
through climate disasters around the
world, it seems as if more people come
to realize the urgency of the situation.
Through the activistic and disruptive
activity of breaking up asphalt to plant
seeds of future ecological resistance,
the Renaturalization Factory engages
those who are scared, angry and
hopeful. Those who see the site as a
site of opportunities.
This thesis is a statement to move more
radically towards ecologically and
socially sustainable urban practice
Implementation of LiDAR and SLAM on a Small-Scale Autonomous Platform
No full textAutonomous driving (AD) technology continues to evolve with goals of enhancing road safety, lowering emissions and increasing transportation efficiency. Modern solutions rely on sensors including GPS, radar, camera and LiDARs to perceive their surroundings and enabling safe and precise navigation. Continued research and development in this field require accessible and adaptable platforms for doing so on.
This thesis, conducted in collaboration with Infotiv AB, builds on two previous master theses and focuses on developing such a platform and expanding it, making the development more available. The autonomous platform 4 (AP4) is a small-scale autonomous platform based on the Ninebot GoKart, which has been implemented with a Raspberry Pi 4b and ROS2 environment.
The focus of this thesis was to add onto the existing platform by integrating a LiDAR and explore sensor fusion possibilities with an IMU, both in simulation and in real-life. By doing this, the work aimed to improve localization and path planning through simultaneous localization and mapping (SLAM) to further improve the AP4. This was done while simultaneously keeping the platform modular and scalable.
A LiDAR and IMU pipeline has been integrated both in simulation and on the physical platform. For evaluation, a local go-kart track was rendered and used as grounds for both cases. The simulations proved that the concept using SLAM with a LiDAR and sensor fusion of an IMU can work for self driving on a small-scale platform. However, the implementation to the physical environment highlights the necessities of well tuned sensors and position estimations
Performance and Cost Analysis of GaN and Si Devices in Two-Level and Three-Level NPDC Voltage Source Inverter Topologies
No full textAbstract
This thesis presents a comparative study of two-level and three-level three-phase inverter topologies utilizing Silicon MOSFETs and Gallium Nitride HEMTs. The analysis focuses on performance metrics, including power loss, total harmonic distortion, common mode currents, and cost-effectiveness. The investigated system is a low-voltage (< 60 V DC) inverter intended to drive a permanent magnet synchronous machine-based water pump in data center cooling applications. All simulations are conducted in LTspice and the results show that the Gallium Nitride-based two-level inverter operating at 16 kHz achieves a system efficiency of 98.27 %, and a total harmonic distortion of 2.87 %. In contrast, the corresponding
Silicon-based two-level inverter exhibits a lower efficiency, 97.79%, and a total harmonic distortion of 2.88 %. When the switching frequency of the Gallium Nitride two-level inverter is increased to 200 kHz, the total harmonic distortion is reduced significantly to 0.25 %, while the power loss increases slightly. Three-level neutral-point diode clamped inverters exhibit lower common mode currents due to reduced amplitude of the switching voltage. However, the three-level Gallium Nitride inverter at 200 kHz shows a slightly increased total harmonic distortion of 0.78 % compared to its two-level counterpart at the same frequency, which can be attributed to the non-ideal behavior of clamping diodes and voltage variations
over the DC-link capacitors. Analyzing the theoretical and simulated power losses in the semiconductors, Gallium Nitride transistor showed a reduction of 86.21% in switching losses when compared to Silicon MOSFETs in a two-level inverter. The three-level Gallium nitride inverter further reduced the switching losses by 69.92% compared to the two-level Gallium
nitride inverter. However, the conduction and diode losses in the neutral-point diode clamped inverter increased the total power loss, making the two-level inverter more efficient in comparison. At high switching frequencies, above 723 kHz, the theoretical model predicts that the three-level inverter will be more efficient. The cost analysis shows that although the Gallium Nitride-based two-level inverter has a higher initial cost, its improved efficiency offsets this over time. At a switching frequency of 16 kHz, the break-even point is approximately six years, after which the accumulated energy savings equal the additional upfront investment
Mekanisk hållfasthet för lödfogar för kretskortskomponenter
No full textThis thesis deals with the mechanical properties of solder joints used to fix components on
circuit boards. The focus is on the inverter that is part of electric vehicle powertrains. The
work is performed at Infimotion, a company specializing in electric powertrains. Today, there
is a lack of data on the service life of solder joints under thermal and mechanical stress.
The purpose of the project has been to analyze how different types of solder joints - THT
(Through-hole technology), SMT (Surface mount technology) and BGA (Ball grid array) -
are affected by vibrations and temperature changes. The work includes both theoretical
calculations and simulations in FEM software to identify stress levels and identify potential
causes of failure.
The results obtained show that it is the thermal loads that cause the highest stresses in the
solder joint, especially due to different thermal expansion coefficients of the material for
solder joint, circuit board and component. It also appears that the solder joints that meet the
requirements of the IPC-A-610 (Class 3) standard, exhibit a lower stress than those that do
not meet the requirements. This indicates a better lifetime and reliability if the requirements
of the standard are met.
It can be concluded after the completion of the work that the thermal load is the most critical
factor, and that combined loads (thermal + mechanical) exacerbate damage growth.
As further work, it is suggested to do further calculations with more accurate mesh to find a
result that converges. Also calculate more accurately on fatigue by calculating with varying
thermal load and mechanical load together. Also perform tensile tests and thermal load to
validate the simulation result
Economic analysis of electrolyzer / fuel cell-based energy storage systems via price arbitrage operation
No full textTear down fences not buildings Sockenbacka in transformation
No full textUrban development in the Western world increasingly focuses on densifying
and transforming sites with complex conditions. In Helsinki, where the 2016
city plan directs growth around transport nodes, business districts are now
emerging as opportunities for urban transformation.
The Sockenbacka business district in northwest Helsinki has the highest
rate of vacant office space in the capital region of Finland. While the City
of Helsinki is about to explore how housing can be integrated here, current
densification practices favour demolition and rebuilding, despite high
environmental costs. Instead of replacing them, this thesis explores how
existing buildings and structures in business districts can be transformed and
reused for housing and other purposes, rethinking sustainable urban planning.
Drawing on theories of transformation and adaptive reuse, the thesis defines
design approaches for transformation and reuse. These are applied in a
transformation-driven pre-study for a local master plan. Methods include
site visits, literature review, iterative design process, and discussions with
professional planners.
The analysis identifies areas suitable for residential transformation, areas to be
kept as business-focused, and others best suited for mixed-use. Particularly,
the district south of Gjuteriet station and west of Vichtisvägen is explored
more closely. The reuse potential of existing buildings is assessed based
on their characteristics and context, and a future mixed-use urban plan is
envisioned for these blocks.
The thesis gives a spark for imagining a possible mixed-use future for
Sockenbacka through transformation and reuse of its existing building stock.
Realising this potential, however, requires integration into higher levels of
planning, and close collaboration with existing property owners. The thesis
also demonstrates how planning for transformation challenges conventional
planning scales.
As a contribution to transformative urban planning in Helsinki, the work
encourages a shift in planning practices, from demolition toward reusebased
approaches. It calls on planners to rethink norms, collaborate across
disciplines, and, to tear down fences, not buildings
Effektiv temperatur hos transmonkvantbitar - En jämförelse av mätmetoder och kryostatuppställningar
No full textDetta kandidatarbete syftar till att bidra till forskningen om den effektiva temperaturen,
Teff, hos transmon-kvantbitar och dess koppling till kryostatkonfigurationer. Vi har jämfört
och utsett den bästa av tre mätmetoder för bestämning av den effektiva temperaturen
hos transmon-kvantbitar genom litteraturstudier och experimentell implementering i en
kryostatuppställning i lågtemperaturgränsen. Vidare har vi implementerat den utsedda
mätmetoden i fyra olika kryostatuppställningar för att dra slutsatser om vilka specifika
kryostatkomponenter som orsakar en högre effektiv temperatur hos transmon-kvantbitar.
Genom litteraturstudier identifierades tre mätmetoder; single-shot-metoden, Rabipopulationsmetoden
och korrelationsmetoden. För vidare jämförelse implementerades
dessa metoder i en kryostatuppställning. Utifrån resultaten utsågs single-shot-metoden
som den bästa metoden på basis av följande jämförelsekriterier; den effektiva temperaturen,
Teff, och dess osäkerhet, δTeff, R2-måttet för alla gjorda kurvanpassningar, samt
metodspecifika prestandaparametrar. Nackdelen med både Rabi-populationsmetoden och
korrelationsmetoden var brusiga mätningar som gav upphov till opålitliga resultat medan
fördelen med single-shot-metoden var att den trots osäkerhet gav pålitliga resultat.
Single-shot-metoden tillämpades i fyra olika kryostatuppställningar med samma temperatur.
Resultaten påvisade att potentiella fördelar var avsaknaden av en kvantbegränsad
förstärkare och en dämpning på 80 dB på ingångsledningen medan potentiella nackdelar
var otillräcklig filtrering i kryostaternas lägsta kammare, för låg dämpning på ingångsledningen
(60 dB), förekomsten av en kvantbegränsad förstärkare och avsaknaden
av en isolator i kryostaternas näst lägsta kammare.
I framtida arbeten föreslår vi att man implementerar Rabi-populationsmetoden och
korrelationsmetoden med fler iterationer för att undersöka om det undertrycker bruset
i mätningarna. Vi rekommenderar även att mätmetoderna implementeras i flera olika
kryostatuppställningar för att göra en mer omfattande jämförelse. För en mer systematisk
och pålitlig kryostatkomponentjämförelse anser vi att mätningar borde göras i en kryostat
där enskilda komponenter byts ut
