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.

Visar 1 - 2 av 2

Senast inlagda

Resurshantering och arbetsplanering inom Barnintensivvården

(2025) Borg, August; Nyström, Hugo

Syftet med denna studie är att undersöka organisatoriska utmaningar och förbättringsmöjligheter på intensivvårdsavdelning barn på Sahlgrenska Universitetssjukhuset. Avdelningen har komplexa bemanningsbehov på grund av varierande vårdnivåer och ett patientflöde som består av både planerade operationer och akuta inläggningar. Schemaläggningen är i dagsläget till stor del manuell och påverkas av begränsad digitalisering, bristande standardisering samt ett fragmenterat informationsflöde. Genom en kombination av observationer, intervjuer och dataanalys har flera problemområden identifierats: ineffektiv schemaläggning, brist på standardiserade rutiner, outnyttjade data om förväntad vårdtid och begränsad användning av vårdtyngd i resursplanering. Studien föreslår ett antal förbättringsåtgärder, såsom AI-baserad schemaplanering, standardisering enligt Lean-principer, visuell styrning för ökad informationsöversikt och införande av Fast track-rutiner för förutsägbara patientgrupper. Syftet med dessa förslag är att minska administrativ belastning, effektivisera resursanvändningen, förbättra både arbetsmiljö och vårdkvalitet samt förbättra patientflödet. Resultaten visar på vikten av att utveckla avdelningen mot en lärande organisation där både tyst och explicit kunskap tas tillvara i det kontinuerliga förbättringsarbetet TEKNIKENS EKONOMI OCH ORGANISATION Avdelning för Supply and Operations Management CHALMERS TEKNISKA HÖGSKOLA Göteborg, Sverige 2025 Resurshantering och arbetsplanering inom Barnintensivvården August Borg Hugo Nyström © August Borg, 2025 © Hugo Nyström, 2025 Teknikens ekonomi och organisation Chalmers tekniska högskola 412 96 Göteborg Sverige Telefon + 46 (0)31-772 1000 Göteborg, Sverige 2025 Göteborg, Sverige 2025 Resurshantering och arbetsplanering inom Barnintensivvården August Borg Hugo Nyström Institutionen för Teknikens ekonomi och organisation Chalmers tekniska högskola Syftet med denna studie är att undersöka organisatoriska utmaningar och förbättringsmöjligheter på intensivvårdsavdelning barn på Sahlgrenska Universitetssjukhuset. Avdelningen har komplexa bemanningsbehov på grund av varierande vårdnivåer och ett patientflöde som består av både planerade operationer och akuta inläggningar. Schemaläggningen är i dagsläget till stor del manuell och påverkas av begränsad digitalisering, bristande standardisering samt ett fragmenterat informationsflöde. Genom en kombination av observationer, intervjuer och dataanalys har flera problemområden identifierats: ineffektiv schemaläggning, brist på standardiserade rutiner, outnyttjade data om förväntad vårdtid och begränsad användning av vårdtyngd i resursplanering. Studien föreslår ett antal förbättringsåtgärder, såsom AI-baserad schemaplanering, standardisering enligt Lean-principer, visuell styrning för ökad informationsöversikt och införande av Fast track-rutiner för förutsägbara patientgrupper. Syftet med dessa förslag är att minska administrativ belastning, effektivisera resursanvändningen, förbättra både arbetsmiljö och vårdkvalitet samt förbättra patientflödet. Resultaten visar på vikten av att utveckla avdelningen mot en lärande organisation där både tyst och explicit kunskap tas tillvara i det kontinuerliga förbättringsarbetet.

Building a Motor Test Bench Prototype

(2025) Andersson, Elin; Nilsson, Felix

In modern production machines, numerous electrical motors are used, and failures are common. To reduce downtime and improve reliability, anomaly detection by sensors can be used. The anomaly detection algorithms can discover abnormal patterns in the motor’s performance and thus, give an early indication when failure is underway. An issue with this, however, is that the subject is complicated to study, as real-life production machines are difficult to test with different failure scenarios. The purpose of this project was to set up a test bench with two DC motors and sensors that could be used for studying anomaly detection algorithms. A test bench was built with an MDF board as the base. On the board, two 3D-printed motor holders for the DC motors were attached along with two axis holders to mount an axis between the motors. An Arduino Mega was connected to control the motors and adjust the speed with a potentiometer. Additionally, a temperature sensor and a 3-axis accelerometer sensor were applied to the motor and connected to the Arduino Mega. In conclusion, a prototype of a test bench for further development was created.

Shaping Rewards with Temporal Information to Guide Reinforcement Learning

(2025) Lundgren, Linus

Reinforcement learning (RL) methods that apply pretrained Vision-Language Models (VLMs) to compute rewards typically use a single observation of the environment to do so. This is problematic because any information emerging from the sequential nature of RL, i.e. temporal information, is therefore disregarded. This thesis explored how temporal information can be incorporated into the VLM reward computation, by first distinguishing between fixed and adaptive temporal information. In fixed temporal information, additional inputs are provided to describe the environment’s progression through time, but these inputs remain unchanging throughout each episode. In contrast, adaptive temporal methods take additional inputs that can change as the episode progresses. Positional and directional rewards were defined to take advantage of fixed and adaptive temporal information respectively, along with new supervised finetuning methods for the directional reward functions. Evaluated with a sample efficiency metric over 6 robotic manipulation tasks, the best new positional rewards performed 18.4% better than previous methods, while directional rewards performed 23.0% better. Combining positional and directional rewards showed a 25.4% improvement, which was the best performance achieved by any method in this thesis.

Modeling and Evaluation of the Olshammar engine. A simulation based approach of a five-stroke turbocharged engine using Siemens Amesim.

(2025) Hansson, Wilhelm; Åberg, Fredrik

Internal combustion engines (ICEs) have been used since the 19th century and remain relevant as of 2025, although the field faces major challenges. The future of ICEs will heavily rely on new inventions and technological advancements. This thesis addresses one such invention: the Olshammar engine, a five-stroke engine concept featuring a lowpressure exhaust cylinder. The purpose of this study is to examine how the Olshammar engine performs in comparison to a conventional four-stroke engine. There are several software tools available for modeling and simulating ICEs, and in this study, Siemens Amesim was used. Initially, a two-cylinder petrol baseline engine was modeled and optimized, providing the reference for modeling the Olshammar engine. The results show that the Olshammar engine reduces brake-specific fuel consumption (BSFC) across the operating range of 2000–5000 rpm, with the largest improvement at 3000 rpm, where BSFC is reduced by approximately 4 %. This corresponds to a fuel conversion efficiency of ηf = 35.2% compared to ηf = 33.7% for the baseline engine. Furthermore, the simulations indicate that the improvement in BSFC can be attributed to the power contribution from the exhaust cylinder, resulting from the recovery of expansion work. Additional assessment of key parameters contributing to performance improvements suggests that tuning the exhaust cylinder offset relative to the combustion cylinders, as well as adjusting the bore-to-stroke ratio, can further enhance overall performance. Siemens Amesim proved to be a well-suited tool for ICE modeling, to the extent that it could replace GTPower in the ICE course at Chalmers in the future. Finally, the findings of this study demonstrate how the design and optimization of the Olshammar engine contribute to improved fuel efficiency compared to conventional four-stroke designs.

Analys och implementering av EMI-reducerande tekniker i DC/DC-omvandlare

(2025) Bälter, Kevin

As electronic systems become increasingly compact and efficient, the demands on electromagnetic compatibility (EMC) continue to rise. DC-DC converters are a common source of electromagnetic interference (EMI) in many applications, particularly in automotive and industrial environments. This study aims to analyze and implement techniques to reduce conducted EMI in a buck converter. While the requirements defined in the CISPR 25 standard serve as a reference, meeting the standard was not an explicit objective of this work. Through simulations in LTspice and practical measurements in an EMC chamber, several filtering solutions were evaluated, including π-filters, common-mode (CM) and differential mode (DM) filters, as well as complementary techniques such as RC filters, ferrite beads, and increased input capacitance. The results show that the π-filter provided the most consistent attenuation across a wide frequency range (150 kHz–80 MHz), while the CM filter performed better at higher frequencies. The best overall EMI performance was achieved using a combination of a π-filter, increased input capacitance (320 µF), and a ferrite bead. The study also demonstrates that filter placement, grounding quality, and parasitic characteristics of components significantly affect performance. Finally, suggestions for further improvement are discussed, including the implementation of spread spectrum techniques and alternative CM filter designs to achieve improved low-frequency suppression.