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Introduktion av fjärropererade passagerarfärjor i nationell sjöfart: Kvalitativ studie av risker och juridiska utmaningar
No full textRemotely operated passenger ferries have the potential to change maritime transport, but current regulations are designed for traditional ships with onboard crews. This study examines how Swedish national regulations can be applies to remotely operated passenger ferries in commercial operations within Swedish territorial waters. It identifies legal challenges, implementation risks, and maps ongoing projects, tests and future visions.
The study was conducted at Chalmers university of technology using av qualitative research approach. A legal analysis of The Swedish Maritime Code (1994:1009), The Vessel Safety Act (2003:364) and The Vessell Safety Ordinance (2003:438) identified 64 regulatory obstacles, with crew requirements and the shipmasters’ role being major issues. The literature review highlights the lack of a clear definition of autonomous ships, which creates uncertainty in legal interpretation.
The study identifies several risks associated with the implementation of remotely operated passenger ferries, including communication failures, cyberattacks and technical malfunctions that may affect safety. Operational challenges include emergency evacuation risks, such as in the event of a fire, as well as unclear responsibility in case of incidents. The SWOT-analysis highlights opportunities, threats, strengths and weaknesses in implementing remotely operated passenger ferries and integrates the result from the different methods into a comprehensive overview.
The study highlights the advantages of Sweden rapidly adapting its national regulations, which could position the country as a leading actor with the ability to influence developments and drive innovation. At the same time, a swift implementation and regulatory adjustment entail risks. If Sweden establishes its own rules before international guidelines are set, this could lead to future needs for extensive revisions, high economic costs and legal uncertainties. There is also a lack of legal precedents, creating uncertainties regarding legal issues such as owner liability
Näringsåtervinning ur avloppsvatten för livsmedelsproduktion genom alg- och bakterieodling för produktion av råvara till fiskfoder
No full textDenna teoretiska studie undersöker potentialen för näringsåtervinning ur avloppsvatten flöden, med särskilt fokus på kväve och fosfor – två grundläggande ämnen för livsmedels produktion. I dagens linjära sanitetssystem går dessa näringsämnen ofta förlorade, vilket
bidrar till miljöförstöring och uteblivna resursmöjligheter. Studien utforskas möjlighe ten att omvandla näringsämnen i avloppsvatten till livsmedel genom att jämföra olika
produktionsvägar för fiskfoder. De valda alternativen inkluderar mikroalger, makroalger,
metanoxiderande bakterier (MOB) och väteoxiderande bakterier (HOB). Dessa jämförs
huvudsakligen utifrån fiskproduktion och energieffektivitet, men även utifrån skalbarhet,
för att ge en helhetsbild. Resultaten visar att makroalger är den värdekedja med högst
potential för fiskproduktion och är mest energieffektiv per producerat kilogram fisk. Sam tidigt uppvisar MOB den lägsta årliga totala energiförbrukningen samt ytbehovet för
att återvinna allt kväve och fosfor, vilket tyder på den mest effektiva värdekedjan för
att ta tillvara dessa resurser. Studien belyser potentialen i att kombinera cirkulära av loppssystem med innovativa metoder för hållbar livsmedelsproduktion och ger insikter för
framtida utveckling av resurseffektiv akvakultur och avloppshanterin
Evaluation of Synchronous Condensers in Modern Power Grids for Enhancing Grid Stability
No full textAbstract
As renewable energy sources increasingly replace conventional synchronous generation, the resulting decline in system inertia and reactive power capability presents growing challenges for maintaining power system stability. Synchronous condensers (SCs) offer a potential solution by enhancing voltage stability through high fault current injection, providing dynamic reactive power support, and contributing to frequency stability via rotational inertia. This thesis investigates the ability of SCs to improve power system stability, with a focus on voltage regulation and frequency support. Simulations were conducted in DIgSILENT PowerFactory on two grid models of varying strength and complexity, referred to as the robust grid and the
islanded grid. Three SC ratings, 8 MVA, 67 MVA, and 200 MVA, were evaluated to determine their effectiveness under different fault scenarios and deployment strategies. In the robust grid model, SCs had a limited impact on mitigating voltage dips due to the high short-circuit capacity (SCC) of the system and in the case of a short distance between the SC and the fault. However, notable voltage recovery improvements were observed under weakened grid conditions and at more vulnerable locations. Performance between the 67 MVA and 200 MVA units was similar, though deploying multiple smaller SCs may provide redundancy benefits. Regarding frequency support, the high system inertia in the robust grid limited improvements
in the rate of change of frequency (RoCoF) and frequency nadir, which were more evident in the islanded model. In the weaker islanded system, the deployment of an 8 MVA SC significantly improved both voltage and frequency stability. The SC effectively mitigated voltage dips, enhanced voltage recovery, and improved the Ro- CoF and frequency nadir during disturbances. Its positive impact was consistent across all placement locations, making the deployment strategy less critical. These results highlight the value of SCs in supporting voltage and frequency stability, particularly in low-inertia systems, more vulnerable grids, and weak points within robust networks
Neural networks in materials exploration - Computational thermodynamic screening of doped CaMnO3 with oxygen vacancies for chemical looping combustion
No full textTraction Control of Heavy Vehicles using Road Information
No full textLoss of traction, especially while climbing a hill on low-friction surfaces with heavy
vehicles, significantly compromises safety and performance. This thesis presents
an approach that integrates future road information, such as friction coefficients
and slope, to control vehicle velocity and optimize wheel slip in real time. Using
road information data, the controller setup anticipates the wheel speed needed for
a reference velocity and gives the necessary torque to be at that wheel speed while
also adhering to the constraints. A decoupled architecture with three modules is
used to leverage different control systems for different subproblems. Firstly, a differential
lock controller decides which differential setting should be used. Secondly,
a Model Predictive Controller (MPC) tracks a reference velocity while adhering
to constraints. Finally, a Wheel Speed Controller (WSC) is used to give out the
necessary torque to control the wheel speed. The decoupling is mainly done to
keep the computation times close to real-time implementations for heavy-duty truck
platforms. Extensive simulations were done on both synthetic and real-life data to
validate the controller pipeline for varying road profiles. Overall, the results indicate
that preview based traction control can noticeably improve operational safety and
performance for heavy vehicles in off-road and low-friction scenarios
Streamlining APQP and PPAP for Enhanced Supplier Quality - A Capability-Based Case Study at a Global OEM
No full textIn the dynamic market of Original Equipment Manufacturers (OEMs), maintaining customer satisfaction while attracting new business depends on the consistent delivery of high-quality products. As OEMs rely on suppliers for critical components, ensuring supplier compliance with specifications and performance expectations is essential. To support this, industry-standard frameworks such as Advanced Product Quality Planning (APQP) and the Production Part Approval Process (PPAP) developed by Automotive Industry Action Group (AIAG), are used to guide collaboration, reduce risk, and validate quality throughout the product development lifecycle.
This thesis investigates how APQP and PPAP are applied at a global OEM and identifies organizational and procedural challenges affecting their use. Using the Capability Maturity Model Integration (CMMI) framework, the study assesses current practices, identifies key gaps, and proposes targeted actions to improve process maturity. The research is based on interviews with internal stakeholders across SQM, R&D, procurement, logistics, and digital, supported by internal documentation and key informants.
The findings highlight challenges such as fragmented task ownership, inconsistent system usage, limited cross-functional involvement, and gaps in training and supplier integration. To address these, the study outlines short- and long-term actions including clearer role definitions, improved digital alignment, and formalized training routines.
The thesis contributes to quality and operations management by demonstrating how maturity models like CMMI can support structured improvement of APQP and PPAP in complex, cross-functional environments
Skillnader i skadeutfall i fordonskrockar mellan könen, med hänsyn till sätesposition
No full textThis bachelor thesis examines how injury outcomes in traffic collisions differ between
men and women, with particular attention to their seating position within the vehicle
at the time of the crash. By using data from the Crash Investigation Sampling
System (CISS) database, this study uses statistical modeling to determine whether
being a driver, front-seat passenger or other passenger affects the injury risk. Research
shows that drivers and front-seat passengers tend to experience more severe
injuries than other passengers. However, different findings suggest that no seat position
is more safe than the others and therefore highlight the importance of continuing
to develop vehicle safety systems. Furthermore, this study emphasizes the existing
limitations in safety systems, as they are primarily designed around the average
male body. Ethical and social aspects are considered in relation to a socio-economic
perspective and also a demographic representation in crash testing. The conclusion
is that while certain person profiles, such as shorter women, who use seatbelts and
driving at lower speeds often result in lower risk of injury, while heavier and taller
men driving at higher speeds without the usage of seatbelts are at greater risk of
injury. Future research should include data from more countries with different traffic
rules and more years of data points for a better understanding and more applicable
model
Wideband MMIC Power Limiters for Integrated Receivers
No full textThis thesis explores the feasibility of designing wideband power limiter circuits that
can be manufactured using monolithic microwave integrated circuit (MMIC) technologies,
with a primary focus on gallium nitride (GaN). Three complete limiter
circuits have been designed and simulated with different performances, along with
one limiter needing external activation. No measurements of the circuits have been
made. Three of the designs were made for a 0.15 μm GaN process, and the last
for a GaAs process incorporating PIN diodes. The GaN-based limiters use switchtransistors
to achieve the limiting behavior with different means of activation, and
are designed to operate in the 2−6 GHz frequency band. The minimum frequency is
limited by the leakage power level, and the upper frequency by small-signal performance.
The most promising complete GaN limiter keeps the leakage below 25dBm
for input powers up to 50dBm. The GaAs limiter utilizes PIN diodes in an antiparallel
configuration to achieve limiting. It operates in the 2 − 18 GHz range,
making it a suitable option when this type of process is available. The leakage is
below 17.5dBm for input powers up to 48dBm. It is, however, unclear whether
the limiter itself will survive powers that large. Although the designs presented
here seem to perform well in terms of power and bandwidth, the insertion losses are
slightly higher than what is generally accepted