[diss] Insinööritieteiden korkeakoulu / ENG

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    Predicting the probability distribution of ice load amplitudes on ship hull in different ice and operational conditions
    (Aalto University, 2024) Kotilainen, Mikko; Vanhatalo, Jarno, Assoc. Prof., Helsinki University, Finland; Kujala, Pentti, Prof. Emer., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Marine and Arctic Technology; Insinööritieteiden korkeakoulu; School of Engineering; Suominen, Mikko, Asst. Prof., Aalto University, Mechanical Engineering, Finland
    Due to their large cargo carrying capacities, ships are an environmentally and economically efficient mode for transporting cargo. During winters, the ships must navigate in ice-prone waters and hence shipping in ice-covered waters is an important engineering topic. To protect human lives and the environment during the shipping operations, we must understand the forces the ship hull sustains during the shipping operations. However, because of many uncertainties in the ice microstructure, and the ice breaking process, the forces required for breaking the ice cannot be resolved deterministically, but rather statistically. This work analyzed full-scale ice load data and the measured covariate conditions at the instant the load occurred to examine how the load distribution changes in different conditions. The work used Bayesian hierarchical models with Gaussian process priors to infer how the load probability distribution parameters and their uncertainties change as a function of condition covariates. The ice thickness was modeled using a Gaussian process model with a Student-t error model, whereas the ship speed was interpolated linearly. Different ice load models were compared via their posterior predictions, and the Weibull model was found to have the best posterior predictions. According to the trained models, the ice load levels were changing with conditions, increasing in thicker ice, whereas the speed effect was more convoluted across models. In addition to analyzing the loads from one bow frame, the research was able to identify local temporal maxima of loads by analyzing force measurements from three adjacent frames in the bow shoulder area. After identifying the peak loads from the data, the stereo camera photos were analyzed at the peak load occurrence times to study how the ice response affected the peak load distribution. The work investigated further the cases where the peak load was caused by a rotating ice cusp, studying how the cusp area was affected by the ice thickness and ship speed, and how the peak load was affected by the cusp's size and ship speed. The cusp area increased in slower speeds and thicker ice, whereas the peak loads increased with slower speeds and larger cusps.
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    Autonomous Vehicle Perception and Navigation in Adverse Conditions
    (Aalto University, 2024) Seppänen, Alvari; Konetekniikan laitos; Department of Mechanical Engineering; Autonomous Mobility Laboratory; Insinööritieteiden korkeakoulu; School of Engineering; Tammi, Kari, Prof., Aalto University, School of Engineering Finland
    Autonomous mobility has gained popularity in recent years due to the promise of safer and more efficient transportation systems. However, multiple challenges hinder the realization of fully autonomous transportation, e.g., safety, operational environment limitations, and efficiency. This thesis addresses challenges related to the perception and navigation of outdoor mobile robots in adverse conditions. These conditions refer to adverse weather and limited communication between a remote operator and the robot. Adverse weather conditions affect the perception systems, namely light detection and ranging (LiDAR) sensors, causing specific types of noise to the data. This work aims to denoise this data and thus provide clean data for downstream systems. Two deep-learning-based denoising approaches are proposed: a supervised approach that utilizes a spatiotemporal module and a selfsupervised multi-echo approach. The supervised method's spatiotemporal module enables efficient data usage and generalization from semi-synthetic to fully real-world data. The self-supervised approach learns by predicting the correlation of data points to their neighbors and utilizes multiecho point clouds for recovering the points representing solid objects. Experiments show that both approaches achieved state-of-the-art performance. Another challenge addressed in this thesis is the navigation in adverse conditions. These challenges refer to limited remote communication caused, for example, by adverse weather conditions. The limited communication between teleoperators and semi-autonomous mobile robots is studied. Semi-autonomous control strategies are proposed to aid the teleoperators when communication signal limits the system's performance. Experiments with a mobile robot prototype revealed that the strategies improved the navigation. Future research should focus on testing the denoising with downstream algorithms and assessing the control strategies in more complex environments. Many adverse and unexpected scenarios must be addressed to realize fully autonomous vehicles in complex environments. Therefore, more unified solutions tackling multiple issues simultaneously are desired in future research.
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    Transition towards carbon neutral district heating by utilising low-temperature heat
    (Aalto University, 2024) Hiltunen, Pauli; Syri, Sanna, Prof., Aalto University, Department of Mechanical Engineering, Finland; Volkova, Anna, Prof., Tallinn University of Technology, Estonia; Konetekniikan laitos; Department of Mechanical Engineering; Energy Conversion and Systems; Insinööritieteiden korkeakoulu; School of Engineering; Syri, Sanna, Prof., Aalto University, Department of Mechanical Engineering, Finland
    Heating and cooling sector accounts for more than half of the total energy demand in European Union. Traditionally, fossil fuels have had a large share in producing heat to buildings and domestic hot water. Therefore, to mitigate the climate change and achieve European Union's climate goals, decarbonisation of the sector is essential. The war in Ukraine and energy crisis in 2022 increased the pressure to reduce the dependency of imported fossil fuels in heating even more. The transition of old infrastructure to low-carbon heat sources will take decades and will likely happen step-by-step. In this thesis, the transition to carbon-neutral production in Espoo district heating system was investigated. Especially, the role of low-temperature waste heat from the data centres in Espoo during the transition and feasibility of electrified district heating during electricity price shocks were studied. Utilising heat from district heating network's return water to provide heating and improve the energy efficiency were investigated in the campus of Tallinn Technical University was studied in this thesis as well. Utilising the return water of district heating in low-temperature energy cascades has been discussed as an option to reduce distribution losses in newly built or refurbished areas during the transition to low-temperature district heating. Use of heat from return water reduces the return temperature of the district heating network, which has a positive impact on the energy efficiency of the entire system. Electrification of district heating reduces the consumption of combustible fuels and can help balancing the electricity markets with high share of intermittent power production such as wind or solar power. Furthermore, digitalisation of the society will increase the already high energy demand of IT sector. Cooling of data centres produces large quantities of waste heat, which can be utilised in district heating. The results of this thesis show that district heating can provide environmentally sustainable alternative to the university campus heated by a natural gas-fired boiler reducing carbon emissions and primary energy consumption. Implementing a sub-network utilising low-temperature heat from the city's district heating network could reduce the emissions and primary energy consumption even more by lowering the heat losses and improving the efficiency of power and heat production in the combined heat-and-power plants. Waste heat from data centres can provide economical heat source for base load production in district heating systems, but it suits poorly for peak demand production during the heating season due to the mismatch between waste heat load and heat demand. Increasing electricity price hinders the profitability of heat pumps priming the low-temperature waste heat. However, heat pumps proved to produce economically viable heat even with high electricity prices, if the costs of fossil fuels are high as well, as it happened in 2021.
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    Evaluation of Smart AND Sustainable City Development: What Indicators to Use, Why and When?
    (Aalto University, 2024) Huovila, Aapo; Airaksinen, Miimu, Senior Vice President, Dr., SRV Group Plc, Finland; Kazi, Sami (Abdul Samad), Research Team Leader, Adjunct Professor, Dr., VTT Technical Research Centre of Finland Ltd & Hanken School of Economics, Finland; Rakennetun ympäristön laitos; Department of Built Environment; Real Estate Economics; Insinööritieteiden korkeakoulu; School of Engineering; Junnila, Seppo, Prof., Aalto University, Department of Built Environment, Finland
    Sustainability and smartness are among the most common concepts that cities use to formulate their goals, and cities use indicators to keep track of progress towards those goals. The selection of indicators is difficult due to the abundance of frameworks designed for specific purposes but requiring expert knowledge to be correctly applied. Poor indicator selection can have serious negative consequences and lead to unintended incentives. In this dissertation, I developed a taxonomy for indicator selection and comparison in smart and sustainable cities. I analysed 1500 indicators against this taxonomy, considering differences in conceptual focus, application sector and indicator type, and made recommendations on indicators' applicability to specific evaluation needs. The results revealed clear differences between smart and sustainable city indicators. Smart city indicators predominantly focus on measuring short-term efficiency in technology deployment and fail to demonstrate the benefits of the technology. In contrast, sustainability indicators emphasise long-term impacts. Since technology implementation should not be an end goal but a means toward other goals, this dissertation recommends integrating smart and sustainable city indicators and adopting a new concept, "Smart sustainable cities". Cities are encouraged to combine different indicator types to keep track of short and long-term impacts. Furthermore, I more deeply analysed two indicators (building energy efficiency and cities' carbon emissions), and also their selection and use are full of pitfalls. While the traditional, globally regulated building energy efficiency indicator (kWh/m2) properly measured the physical properties of buildings, it penalised environmentally beneficial measures that increased building use. Therefore, alternative functional units were developed to reward higher building occupancy and space efficiency. The methods differentiating cities' carbon emission reporting include scope, boundaries and the definition of compensation allowed for carbon neutrality. Although cities typically focus on emissions caused within their boundaries, there is an increasing trend to cover emissions caused by consumption in cities but actualising elsewhere. City emissions are primarily affected by national measures, and cities need activity-based indicators to monitor the impact of local actions. This dissertation's main contribution is the taxonomy for indicator selection. I recommend the following process for indicator selection: 1) City goals (balance between smart and sustainable indicators), 2) Purpose of evaluation (indicator type), 3) Scope of evaluation (sectoral coverage, functional unit, assessment method), 4) Availability of data and resources (selection of feasible indicators). Future studies are recommended to test this process's usefulness in different evaluation settings.
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    Timber-only Structures & Architecture - Exploring the Potential of Using Salvaged Timber and Wooden Nails
    (Aalto University, 2024) Ruan, Gengmu; Rakennustekniikan laitos; Department of Civil Engineering; Insinööritieteiden korkeakoulu; School of Engineering; Fink, Gerhard, Assoc. Prof., Aalto University, Department of Civil Engineering, Finland; Filz Günther H., Prof., Universität Innsbruck, Austria
    In light of the serious environmental challenges, it is urgent to ease the current dramatic increase of CO2 emissions. The building sector, as one of the major contributors to global CO2 emissions, is on the move to a more conscious and environmentally compatible thinking. The use of natural resources, short transport, low processing of raw material, and prolonging life cycles of existing building components, are some of the keywords in this context. In this thesis, a concept of timber-only structures and architecture was proposed to explore possible sustainable solutions for future building construction. Specifically, salvaged timber and wooden nails were used as the only material and connector for building structures. This research consists of three main research phases: The first phase was initiated by a pedestrian trail project, which searched for a more cost-efficient and more sustainable solution to replace the traditional trail-making in Finland. The solution was mainly based on two individual parts – (i) an investigation on the wooden nails in terms of usage, nailing arrangements, and structural behavior, and (ii) an investigation on salvaged timber in terms of availability, planar arrangements, and resulting patterns. The outputs from the individual investigations were merged in the trail design, where full-scale prototypes were built up and an exhibition was performed. The second phase rethought the design process of the trail. A systematic review of integrated design concepts was conducted. Inspired by the review, a concept of using feedback loops was proposed to reinterpret the design process of the trail. This feeding-back process also informed a more complex structure to be studied in the following phase. In the third phase, a planar rectangular slide-in reciprocal frame (RF) system was proposed. A systematic investigation was carried out regarding structural performance, assembly logic, possible layouts, and resulting architectural spaces. As a showcase, a canopy was designed and built by applying the outputs from the investigation, and then exhibited to the public. According to the overall process of the exploration using salvaged timber and wooden nails, the concept of timber-only structures and architecture showed its potential in various aspects: (i) wooden nails can provide sufficient load-bearing capacity for structural applications, at least for less-loaded structures or structures with low safety requirements; (ii) salvaged timber brings both structural and aesthetic values for new constructions; (iii) using feedback loops to interpret the building design process can bring more holistic solutions compared to the traditional linear design approach; and (iv) the planar rectangular slide-in RF system brings unique architectural features and structural benefits, but they are associated with large deformations and a brittle failure mode in terms of structural behaviour.
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    Development of the framework and the methodologies towards nZEBs in Finland
    (Aalto University, 2024) Alam, Sadaf; Lahdelma, Risto, Prof., Aalto University, Department of Mathematics and Systems Analysis, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Energy Efficiency and Systems; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof., Aalto University, Department of Mathematics and Systems Analysis, Finland
    The emerging trends for deep-retrofit of existing buildings in Europe require the formulation of strategies for nearly zero-energy buildings (nZEBs) and achieving benchmarks as outlined in the Energy Performance of Buildings Directive (EPBD) recast. The fundamental process of retrofitting to an explicit high performance necessitates the development of robust and diverse methodologies to be used during the early stages of planning in retrofit projects. The construction sector lacks the extensive use of such methods for early decision-making that are essential to accelerate building renovation in Europe. Perhaps literature suggests that there is a huge mismatch between the predicted and measured performance is referred to as the "Performance Gap". The most prominent causes of this uncertainty of energy performance savings identified in the literature are; specification uncertainty in building modeling, poor practice in operation, lack of proper knowledge and skills in the construction industry, facility managers, etc. Low carbon building energy technologies for low carbon generation are diverse. People's adoption of low carbon buildings increases the use of different types of renewables, and each technology utilises various natural resources in a variety of ways and the economic, social, and environmental impacts Thus, it is important to evaluate the social acceptance of low carbon buildings to understand the social perceptions of the people in terms of usage of low carbon buildings and climate challenges. The role of key stakeholders in the industry becomes highly responsible for achieving the energy performance targets. Thus, this research presents the application of combined i) research techniques and ii) building simulation and optimization strategies that shall support the decision-making in retrofitting buildings to low-energy, Nearly zero energy, and comfortable buildings. The findings of this research can provide classical knowledge in many ways. For example, (1) they provide us with a new approach to know how and what kind of steps have already been taken to create awareness about low carbon building energy technology and climate change so far in Finland, and (2) they help us to analyse public perceptions towards low carbon building applicability and to acquire knowledge about what different kinds of low carbon building energy technologies they (participants) are aware of. 3) Attitudes and approaches of the stakeholders towards nearly zero energy buildings (nZEBs). Societal acceptance study contributes to the sustainable development of low-carbon buildings meeting current and future-oriented societal needs. It will provide specific observations concerning the impact of low carbon buildings on society. This study will empower construction industry stakeholders to address the barriers, gaps, and challenges identified in retrofit projects, as well as inform the formulation of policies aimed at promoting retrofit uptake.
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    Torsion as a design driver for structures and architecture
    (Aalto University, 2024) Elmas, Serenay; Markou, Athanasios., Dr., Aalto University, Department of Civil Engineering, Finland; Rakennustekniikan laitos; Department of Civil Engineering; Arkkitehtuurin laitos; Department of Architecture; Structures and Architecture; Insinööritieteiden korkeakoulu; School of Engineering; Taiteiden ja suunnittelun korkeakoulu; School of Arts, Design and Architecture; Filz, Günther H., Assoc. Prof. (Visitor), Aalto University, Department of Architecture, Finland
    Twisted forms, with origins dating back to ancient times, have a prominent presence in architectural history, embodying both aesthetic appeal and structural complexity. This thesis bridges architecture and engineering disciplines to examine a beam element assembled from four thin plywood strips under large rotational and translational deformations, resulting in a unique twisted form. The central question guiding our exploration is whether such flexibly twisted members can enhance structural performance, while embracing their aesthetic values. This research touches on many related viewpoints, including the architectural, artistic, engineering, and pedagogical perspectives, as documented by publications, and showcased by several experimental full-scale structures and exhibitions. The geometry of the twisted beam is derived from the intentional deformation of a thin-walled square tube, where each strip of the tube is hinged-joined along its longitudinal edges. The equilibrium geometry of the beam emerges through a delicate interplay between material, its properties, and physical rules within defined boundary conditions, as a case for self-organized form. The resulting geometry has been presented as a novel cantilever beam, utilizing elastic torsion for structures and architecture [Pub. I], and as a structural element compared with standardized profiles [Pub. II]. Given the observed large deformations, it was crucial to ascertain the residual stress state before proceeding with any subsequent architectural application. In this light, the plywood strip has investigated in detail by considering each individual ply. Furthermore, a parametric model has employed that highlights the potential significant effects of minor changes in the strip's geometric parameters on its overall performance, underlining the geometrically nonlinear behaviour of actively twisted and bent plywood [Pub. III]. Full-scale prototypes provide insights into practical challenges and advantages of the chosen methods, processes, and material, demonstrating its lightness in its applications in a kinematic pavilion [Pub. V], its rapid assembly from identical strips, and utilising standard stock material, while minimizing material waste by applying a simple cutting pattern. Built pavilions showcase how the presented lightweight beam element can be applied to ephemeral architectural scale structures [Pub. IV], as well as elevating it from a mere object to an integral part of a holistic, experimental architectural narrative. They highlight the non-tangible aspects of architecture. Through the presentation of concepts such as harnessing unconventional structural materials like plywood, the reduction of material consumption through an exploration of equilibrium geometries, and the emphasis on the significance of assembly logic, we aspire to influence the current mindset, with a view to positively shaping the future of the building sector, society, and the environment.
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    Numerical modeling of thermal stratification driven combustion regimes
    (Aalto University, 2024) Shahanaghi, Ali; Kaario, Ossi, Prof., Aalto University, Department of Mechanical Engineering, Finland; Karimkashi Arani, Shervin, Dr., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Energy Conversion and Systems Research Group; Insinööritieteiden korkeakoulu; School of Engineering; Vuorinen, Ville, Prof., Aalto University, Department of Mechanical Engineering, Finland
    This dissertation is related to the research areas of computational physics and chemistry. The purpose of the study is to determine the role of temperature stratification in the secondary combustion of gasoline surrogates within the end-gas of spark ignition (SI) engines. Specifically, it highlights the influence of the Negative Temperature Coefficient (NTC) on the prevalence of various combustion regimes, including spontaneous, subsonic, and supersonic ignition, detonation, and deflagration (flame), within one and two-dimensional (1D/2D) scenarios. Gaining a deeper understanding of these phenomena facilitates understanding of the interaction between pressure oscillations, reaction front propagation, and fuel chemistry at SI engine-relevant conditions. Computational fluid dynamics (CFD) simulations of reacting flows, incorporating finite rate chemistry, efficient simulation methods, and high-performance computing, enable the investigation of the underlying physical and chemical processes in such reacting flows. This dissertation consists of three appended journal publications and their brief summary. In Publication I, a diagnostic approach distinguishes between secondary spontaneous ignition and flame of primary reference fuel (PRF) and PRF-ethanol (PRF-E) blends, in 1D setups. In Publication II, established 1D regime diagrams (detonation peninsula) are reconstructed for the PRF and PRF-E mixtures analyzing induced pressure levels from hotspot ignition (i.e. subsonic/supersonic ignition, and detonation modes). In Publication III, 2D phenomena are explored involving converging shock/detonation fronts and shockwave reflection-induced detonation, using the novel ARCFoam numerical framework. In essence, Publication I explores the prevalence of combustion modes at two extremes within the range of studied modes, namely flame and spontaneous ignition in a 1D setting. Publication II focuses on the pressure oscillations induced by hotspot ignition regimes within the 1D framework. Lastly, in Publication III, further geometrical considerations are introduced by investigation of hotspot ignition in 2D scenarios. The main conclusions of this dissertation are as follows: 1) NTC chemistry of the studied fuels is the dominant factor in manipulating the reactivity, inducing secondary combustion modes, and amplified pressure levels. 2) Given the dominance of auto-ignition in the presence of NTC and the impact of thermal stratification on ignition characteristics, density-based 1D/2D CFD simulations are preferred for analyzing underlying combustion regimes. 3) While the detonation peninsula predicts the initial ignition regime induced by hotspot ignition, NTC chemistry and 2D effects such as front curvature and shock reflection can significantly alter combustion dynamics. 4) Apart from the complexity of the flow field and the employed numerical techniques, the resourceintensive nature of finite rate chemistry solution remains the primary bottleneck in such reactive CFD simulations.
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    Drought in Water Abundant Finland - Data and Tools for Drought Management
    (Aalto University, 2024) Ahopelto, Lauri; Veijalainen, Noora, Dr., Finnish Environment Institute, Finland; Professor Varis, Olli, Prof., Aalto University, Department of Built Environment, Finland; Rakennetun ympäristön laitos; Department of Built Environment; Water and Development Research Group; Insinööritieteiden korkeakoulu; School of Engineering; Keskinen, Marko, Prof., Aalto University, Department of Built Environment, Finland
    Droughts pose a risk to all societies, even those with abundant water resources. Climate change will affect this risk, and societies should adapt accordingly. Though Finland has a low drought risk, recent droughts have had a clear impact, especially on agriculture and water supply, but also forestry, hydropower, and ecosystems. While Finland's water governance and water security are generally at a good level, drought has so far gained little attention and operative drought management plans and strategies are absent. This dissertation studies drought risks in Finland and provides recommendations on how to improve drought management. Drought risk can generally be understood as a combination of three factors: vulnerability, exposure, and hazard. Several drought indices, models, and weather data generation are used in the dissertation to better understand drought hazard and to quantify drought frequency, severity, and other characteristics of drought events in Finland. The dissertation also considers how drought hazard might change due to climate change. The results are discussed in relation to different sectors and within the broader water governance context in Finland. The results from the drought index analyses provide detailed information on drought characteristics in Finland. The findings show that choosing the best drought indices for different contexts is difficult, emphasizing the need to use several indices. For the Sirppujoki basin case study (a river basin in southwestern Finland), 2o different standardized drought indices were calculated for two drought events of 2002–2003 and 2018 as well as for the years 2040–2069. In addition, weather data generation coupled with hydrological modeling was tested for the basin. This dissertation reveals that drought risks will likely increase due to climate change, predominantly in the south and southwest Finland. Based on evapo-transpiration-dependent indices, drought events are predicted to increase especially during the growing season. This is particularly worrying for the agricultural sector, since only a few percent of fields have irrigation systems. However, the climate scenarios have a large variation, emphasizing the need for more research as well as flexible climate change adaptation. To address the growing drought risk in Finland, adaptation measures against drought impacts are suggested. A national drought strategy, together with bot-tom-up drought management plans, would mitigate the increasing drought risks. These should be accompanied with a systematic drought management process with an early warning system.
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    Utilization of short-term thermal energy storage for demand response and peak power reduction in district-heated buildings
    (Aalto University, 2024) Ju, Yuchen; Jokisalo, Juha, Senior Scientist, Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; HVAC Technology; Insinööritieteiden korkeakoulu; School of Engineering; Kosonen, Risto, Prof., Aalto University, Department of Mechanical Engineering, Finland
    The European Commission has set ambitious targets to cut at least 55% of greenhouse gas emissions from 1990 levels by 2030 and to realize carbon neutrality by 2050. In 2020, space heating consumed 28% of the total energy consumption in Germany while only 18% was produced by renewable sources. In Finland, district heating is the most common source of space heating. In 2020, it covered 45% of the market share of space heating for residential, commercial, and public buildings. Therefore, decarbonization strategies should be developed for district heating systems and the connected buildings. When renewable energies are utilized more in production, there is the demand to enhance the smart readiness of buildings. Demand side management is an approach to adjusting consumer energy use and power demand according to the production pattern. By utilizing short-term thermal energy storage, such as building thermal mass and thermal energy storage tanks, energy flexible strategies could be applied to buildings and their energy systems for peak power cutting and load shifting. This thesis investigated energy flexibility and the benefits of demand response based on dynamic district heat prices of space heating and a thermal storage tank for district-heated buildings. The meaning of building-level rule-based demand response control strategies on district heating production was also analyzed in the thesis. There were three different production scenarios. The first scenario utilized a biofuel CHP as the basic source and three gas boilers for backup. The second one had a biofuel CHP and a green-electricity heat pump as the basic source and two gas boilers as backup. The last one included a heat pump as the basic unit and an electric heater as backup used grid electricity. In addition, strategies were also developed for peak shaving and peak power limiting with a 5 m3 short-term thermal storage tank. Demand response of space heating cuts up to 9.6% of heating costs for building owners. The demand response control of the storage tank decreases the district heat energy cost by 3.4%. When employing the demand response control of space heating and the storage tank, it gains 12.8% of district heat energy cost savings. In addition, thermal energy storage provides the potential for peak shaving and peak power limiting. It reflects a higher peak shaving potential for colder days with a 31.5% maximum peak power decrease of a Finnish office building. The maximum heating power is limited by 43% and the power fee reduces by 41.2% without compromising room air and ventilation supply air temperatures. The large-scale demand response application decreases the total district heating demand from 3.6% to 3.9% with higher financial benefits and less CO2 emissions. Moreover, it increases the full load operation hours of renewable energy generation units, reducing emissions. Therefore, demand response effectively decreases fossil fuel usage and improves the energy resiliency of district heating systems.
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    Supporting agency for sustainability - Exploring the contributions of universities and workplaces to the sustainability competencies and agency of engineering graduates
    (Aalto University, 2024) Karvinen, Meeri; Rakennetun ympäristön laitos; Department of Built Environment; Water and Environmental Engineering; Insinööritieteiden korkeakoulu; School of Engineering; Keskinen, Marko, Ass. Prof., Aalto University, Department of Built Environment, Finland
    The societal sustainability transformation requires actions from all organizations. University graduates have the opportunity to catalyze the transformation already in the early career, provided they have adequate competencies from the education, and the workplaces ensure sufficient opportunities to influence. Particularly engineering graduates play a significant role through a solution-oriented approach. This dissertation investigates how universities support graduates in developing the required competencies and agency for sustainability using Nordic universities and the water and environmental engineering field in Finland as case examples. The thesis combines three research contexts, sustainability in higher education, engineering education and transition to working life, which together create a unique, broad theoretical framework for the explorations. The study utilizes surveys, interviews, and workshops to focus on the integration of sustainability in university operations, on the competencies needed for the early career ('employability') and for promoting sustainability, and on graduate role and agency in the workplaces. The findings show that sustainability is generally considered as important. The employers are also satisfied with graduate contributions. However, Nordic universities could take a stronger 'whole university approach' in integrating sustainability to better support graduate sustainability agency. Supporting teachers in sustainability education revealed to need particular emphasis. In engineering, employability competencies are prioritized over sustainability. In promoting sustainability, graduates are expected to take a knowledgeable, independent, even transgressive role. While they do bring new insights and 'green' values, the graduates have challenges to connect their work to sustainability and they feel lacking power to influence. A hybrid graduate competency profile is suggested that promotes both employability and sustainability competencies: substance knowledge, key sustainability competencies, and sustainability knowledge. Followingly, this dissertation encourages engineering educators to explore new pedagogical approaches that particularly develop the personal dispositions and agency of students and facilitate framing own work to a sustainability context. It further highlights the role of universities in supporting the teachers and workplaces in supporting the graduates. In addition, collaborative agency for sustainability among the graduates, workplaces and education is encouraged, as intensified collaboration around sustainability can clarify the role of the graduates in catalyzing the sustainability transformation in workplaces. It can also encourage teachers to try new approaches for teaching sustainability, students to develop adequate competencies, and workplaces to create practices that support graduates in contributing to sustainability.
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    Evaluation of Hydrogen Embrittlement Effect on Mechanical Strength of Modern Martensitic High-Strength Steels - Experimental Analysis and Artificial Neural Network-based Prediction
    (Aalto University, 2024) Fangnon, Eric A. K.; Malitckii, Evgenii, Dr., Aalto University, Department of Mechanical Engineering, Finland; Yagodzinskyy, Yuriy, Dr., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Materials to Products; Insinööritieteiden korkeakoulu; School of Engineering; Vilaça, Pedro, Prof., Aalto University, Department of Mechanical Engineering, Finland
    Hydrogen embrittlement (HE) is a challenge affecting several engineering materials, with a significant impact on steels, targeting critical components in high-value industrial applications. To better understand the HE phenomenon and its impact on the mechanical performance of newly developed martensitic steels, this dissertation focuses on the following three key issues: (i) enhancement of experimental conditions for the accurate measurement of hydrogen concentration (CH) in metalic materials, (ii) assessment of the mechanical strength of steels under different hydrogenation and mechanical loading conditions, and (iii) a new artificial neural network (ANN)-based tool, applied initially to investigate the relationship between the hydrogen thermal desorption spectroscopy (TDS) and steel's susceptibility to H-induced damage, is further developed to predict the relation between CH and mechanical strength at failure, with reduced requisite experimental testing. A specimen cooling system was developed and integrated with the air-lock in a TDS apparatus with the objective of enhancing the accuracy of CH measurements in the studied steels. The application of the new specimen cooling system, enabling temperatures down to 213˚K, proved to provide a significant improvement in CH measurement, allowing more accurate analysis of obtained thermal desorption spectra, valuable for H-trapping analysis. The H-uptake and mechanical performance of four martensitic steel grades with varying prior austenite grain (PAG) morphology were studied by monotonic uniaxial tensile testing and TDS in different H-charging conditions. The results demonstrate that the H-uptake under the same Hcharging conditions, without external mechanical loading, does not vary between the steels. However, a variation in H-uptake was evident with external mechanical loading. This variation does not directly depend on, or correlate with the different PAG morphology. Furthermore, the results showed that CH in the steel has a greater influence on the H-enhanced creep rates leading to failure, than the magnitude of the applied loads, during constant load mechanical testing conditions. The developed dense ANN tools, encompassing three different models, were evaluated for the prediction of steel's susceptibility to HE and CH responsible for the H-induced failure with an approximate accuracy of about 98%. Enhancing the ANN models with training data may yield a powerful tool for the HE characterization of steels. This can be done with a reduced dependency on time-consuming experimental testing with hazardous and complex apparatus.
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    Out of the WASH box – Towards a wider contextualization of the water, sanitation, and hygiene sector
    (Aalto University, 2024) Juvakoski, Anni; Vahala, Riku, Dr., Finnish Water Utilities Association, Finland; Levchuk Golubtsova, Irina, Dr., University of Eastern Finland, Finland; Rakennetun ympäristön laitos; Department of Built Environment; Water and Environmental Engineering; Insinööritieteiden korkeakoulu; School of Engineering; Varis, Olli, Distinguished Prof., Aalto University, Deparment of Built Environment, Finland
    Water, sanitation, and hygiene (WASH) have perennially been recognized as a key approach to improved health in low-income areas. Whereas water sector proponents tend to emphasize it as the key approach, there are many other factors that are important and deeply interwoven with WASH. This interdisciplinary dissertation revisits this premise by attempting to provide "out-of-the-box" insight the water sector has been calling for with four contrasting studies. To generate such novel insight, we have expanded the WASH context to uncharted territory (impacts on mental health – Paper II, and functionality in new climates – Paper III). Additionally, we have turned WASH actors that are commonly research subjects (WASH professionals – Paper IV, and municipalities – Paper I) into research objects. In practice, the role of WASH was scrutinized with tools of quantitative analysis (Paper I), psychology frameworks (Paper II), empirical microbiology (Paper III), and qualitative interview analysis (Paper IV). Based on our results, the traditional thinking of the water field that adequate drinking water is the most essential need of people may be somewhat insufficient. We showed how waste management may be more strongly associated with severe diarrhea in the context of Brazil (Paper I). Moreover, if overall health equals "physical, mental, and social well-being" as defined by the WHO ever since 1948, then mental health impacts of suboptimal WASH also require attention. We found this to be essential in Paper II, especially in terms of drinking water service inequalities. Considering WASH in new contexts is also an important way to help improve health globally. The Russian full-scale war in Ukraine has made frugal point-of-use water treatment in Europe more relevant than in decades. In Paper III, we discovered that one of the most inexpensive drinking water treatment methods around, solar drinking water disinfection (SODIS), also works in cold climates and is hence a potential method for places such as Ukraine. Finally, we found that the unresearched views of WASH practitioners and innovators play significant roles in determining which WASH methods are used at a local level (Paper IV). In short, this dissertation showed how improving health especially in low- and middle-income areas would benefit from contextualizing WASH more widely than before and managing other equally important housing-related factors alongside it.
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    Renewable fuels for compression ignition engines in various transport modes: effect of fuel properties on end-use performance
    (Aalto University, 2024) Wojcieszyk, Michał; Kaario, Ossi, Prof., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Research Group of Energy Conversion; Insinööritieteiden korkeakoulu; School of Engineering; Larmi, Martti, Prof., Aalto University, Department of Mechanical Engineering, Finland
    This doctoral dissertation belongs to the field of energy technology and focuses on the system level analysis of renewable liquid fuels for transportation purposes. Light-duty, heavy-duty and marine segments were in the scope of the study while compression ignition (CI) engine technology was the common powertrain. Based on statistical methods, the research linked engine performance with fuel properties, which has not been demonstrated yet. In this approach, data-driven black box modeling exploiting the multilinear regression method together with significance analysis and validations was successfully applied. The dissertation consists of four publications in peer-reviewed journals. Publication I concentrates on passenger cars and renewable drop-in fuels like hydrotreated vegetable oil (HVO) and traditional biodiesel (FAME). The experimental results from driving cycle test procedures are utilized in the model development. As an outcome, volumetric fuel consumption and carbon dioxide (CO2) emissions are predicted for light-duty fleet based exclusively on lower heating value, cetane number and density. In Publication II, the performance of heavy-duty vehicles is analyzed and predicted for various neat alternative fuels and their blends with fossil diesel. Simulations for new blending components are executed using heating value, density and cetane number. Publication III focuses on marine transport and suggests a model capable of predicting CO2 emissions from a medium-speed marine CI engine based on heating value, density and viscosity turned out to be significant properties. In Publication IV, the end-use challenges for the deployment of renewable fuels in the market are discussed and recommended interventions suggested. The novel approach presented in this doctoral dissertation enabled to link fuel properties with engine performance indicators like fuel consumption and tailpipe CO2 emissions. Three state-of-the-art models with high accuracy (coefficient of determination over 0.9 and all p-values below 0.05) were demonstrated in Publications I-III. The results from the modeling work represent the collective effect of fuel properties on end-use performance from the fleet perspective. Furthermore, all four publications support the deployment of renewable fuels in transportation by providing relevant modeling tools (Publications I-III) and recommendations (Publication IV) to decision makers. The outcomes of the dissertation serve for an unbiased comparison of the most promising fuel options that could be fitted to the existing infrastructure with minimum effort.
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    Understanding ice fracture using Digital Image Correlation - From microstructural crack arrest to comparison with the visco-elastic fictitious crack model
    (Aalto University, 2024) Ahmad, Waqas; Bossuyt, Sven, Prof., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Marine and Arctic Technology; Insinööritieteiden korkeakoulu; School of Engineering; Tuhkuri, Jukka, Prof., Aalto University, Department of Mechanical Engineering, Finland
    Different parameters influence the fracture of ice. These include variation in microstructure of ice and experimental conditions such as loading rate and temperature etc. Conventionally fracture of ice has been studied using linear variable differential transducers (LVDTs) and lasers to record deformation and acoustic emissions to study the propagation of cracks in ice. This thesis discusses the use of Digital Image Correlation (DIC) in ice fracture mechanics to achieve higher spatial resolution and study the influence of the grains on a propagating crack. Analysis of S2 saline and freshwater ice experiments was done by developing a DIC postprocessing method that used cross-correlation of the Heaviside function to find a propagating crack tip. Moreover, a quantitative method was developed to find the size of the deformation zone ahead of the crack by using the decrease in the stiffness (slope of the force-COD plot) as a measure of deformation near the initial crack tip. Saline ice fracture experiment were conducted using load-control configuration. The thin section analysis coupled with crack propagation history obtained from DIC showed that the microstructure influenced the crack arrest events. Moreover, along with intermittent crack growth, localized stable crack growth was observed from the full field data which was also linked with the microstructure. Crack growth was intergranular during stable crack growth while transgranular growth was observed during unstable propagation. The upper bound of the fracture process zone (FPZ) ahead of the crack tip was also measured for floating freshwater ice experiments. This deformation zone (DZ) included both the permanent deformations in the FPZ and the elastic deformations. Comparison of the measured results with the visco-elastic fictitious crack model (VFCM) showed that the estimated FPZ size from VFCM depends on the nature of crack growth. The model overestimated the size of the FPZ if the specimen failed without intermittent crack growth. The specimens that failed with intermittent crack growth resulted in similar magnitude of lengths for the FPZ and DZ. However, VFCM underestimated the width of the FPZ compared to the critical crack opening displacement measured from DIC. Lastly, the accuracy of the calculated FPZ size using VFCM was found to be dependent on the accuracy of the crack tip opening displacement (CTOD). 
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    Performance of modern mechanical and natural ventilation systems in apartment buildings under a changing Nordic climate
    (Aalto University, 2024) Kravchenko, Ilia; Kilpeläinen, Simo, PhD., Aalto university, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; HVAC Team; Insinööritieteiden korkeakoulu; School of Engineering; Kosonen, Risto, Prof., Aalto university, Department of Mechanical Engineering, Finland
    Ventilation systems in new buildings and retrofitted ventilation systems in old buildings in Finland are designed to consistently provide a high level of indoor environment along with high energy efficiency. New buildings are implemented with balanced mechanical ventilation with kitchen boosting, which requires precise control of supply and exhaust airflows to preserve balance. Retrofitted buildings are equipped with self-regulating inlet devices to mitigate the natural ventilation dependency on outdoor conditions. The main objective of the study is to investigate the performance of these modern ventilation systems of apartment buildings in various operational conditions, such as occupant behaviour, possible maintenance shortages, microbial pollution resistance and urban microenvironment under changing climate. The performance analysis of the mechanical ventilation in the new buildings showed a significant imbalance between the supply and exhaust airflows during boosting conditions so buildings with high airtightness might encounter significant pressure difference over the envelope. Additionally, analysis of intermittent and continuous nighttime mechanical ventilation long-term operation under humid and cold with microbial pollution showed the extinction of colonies by the end of the experiment regardless of the chosen strategy. The performance analysis of a retrofitted apartment building with natural ventilation showed a significant effect of occupant behaviour, poor maintenance and the possibility of opening windows on the CO2 concentration besides the effect of outdoor conditions. The apartments on higher floors showed high levels of CO2 and risk for overheating, and small apartments tend to overheat more despite a higher air change rate. Improving the envelope airtightness does not benefit the indoor air quality. The effect of urban microenvironment parameters on the performance of large building stock was assessed to understand its ability to mitigate overheating during heatwaves. The most substantial influence of the urban microenvironment was observed during short heatwaves. The leading factors of indoor temperature decrement were low sea distance and high levels of greenery around buildings. The influence of urban microenvironment factors during the long midsummer heatwave was lower, but the green view index showed the most consistent temperature-reducing influence. This research can present the performance of modern ventilation systems in the climate of the Nordic region, emphasizing the need for a precise understanding of each new step in building energy-efficiency advisement to prevent shortcomings and ensure high indoor conditions.
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    Methanol production via carbon dioxide hydrogenation for the maritime sector - Techno-economic assessment and social acceptance
    (Aalto University, 2023) Nyári, Judit; Järvinen, Mika, Prof., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Energy Conversion and Systems; Insinööritieteiden korkeakoulu; School of Engineering; Santasalo-Aarnio, Annukka, Assist. Prof., Aalto University, Department of Mechanical Engineering, Finland
    Interest in Power-to-X technologies, where X stands for various chemical molecules produced from renewable electricity via water electrolysis, has recently accelerated. Methanol is one of these X molecules, where, in addition to hydrogen, captured carbon dioxide also participates in the synthesis. Methanol is an excellent alternative fuel for the maritime industry due to its high energy density, ease of storage and distribution thanks to its liquid state at ambient conditions, biodegradability, and water miscibility. This research has investigated the utilisation of synthetic methanol and the techno-economics of its production. The techno-economics part has focused on assessing large-scale synthetic methanol plants, while the utilisation part investigated methanol usage as an alternative marine fuel from the social acceptance point of view. Aspen Plus® was utilised for the process modelling environment in the techno-economic part. The developed plants ranged from industrial-scale comparable in output to fossil methanol plants to smaller but still large-scale plants. The energy efficiency of these plants was around 80%, and the differences can be attributed mainly to the varying targets of the heat integration. Furthermore, a new parameter was introduced to the process simulation environment, the implemented kinetic model describing methanol synthesis. The selected three kinetic models were first compared in a simple one-pass reactor and later in full-scale synthetic methanol plants. The most recent model has outperformed the other two in all technical key performance indicators. The most recent kinetic model also predicts the lowest levelised cost of methanol, which was 801 €/tonne, 10% below the worst-performing model. Overall, the levelised cost of methanol was calculated to be around 700-900 €/tonne, which is around 75% higher than the current fossil methanol price at 395 €/tonne. Moreover, a series of sensitivity analyses were also conducted, which found that synthetic methanol's production cost is significantly influenced by the cost of electricity and the potential co-sale of the oxygen by-product from the electrolyser. In this research, the developed one-pass reactor model in Aspen Plus® was also used to verify a mathematical model in computational fluid dynamics describing synthetic methanol synthesis and the process conditions' effect. In the utilisation part of this research, passengers of roll-on/roll-off passenger vessels were questioned about their knowledge and preferences of alternative marine fuels and other emission mitigation tools. The research found that most passengers are willing to accept increased fare prices when the vessel runs on alternative marine fuels. Furthermore, passengers prefer lower-emitting fuels and fuel production technologies; however, they lack the knowledge to decide consciously.
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    Advancing safety in autonomous shipping through modern hazard analysis methods - A System-Theoretic Approach
    (Aalto University, 2023) Chaal, Meriam; Bahootoroody, Ahmad, Dr., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Safe and Efficient Marine and Ship Systems; Insinööritieteiden korkeakoulu; School of Engineering; Valdez Banda, Osiris A., Prof., Aalto University, Department of Mechanical Engineering, Finland
    The maritime industry is currently undergoing a substantial transformation towards autonomous shipping, where human involvement in operational activities is diminishing, emphasizing safety and efficiency improvements. This transition, however, introduces new safety challenges that necessitate rigorous risk assessment and innovative safety frameworks. This thesis commences with an exploration of the historical development of risk, safety, and reliability considerations in autonomous shipping through a bibliometric review. Additionally, the future research directions and the potential risk assessment methods adequate for the complex autonomous ships are analysed. System Theoretic Process Analysis (STPA) is a key focus of this study. The thesis provides and investigate a model of the STPA organizational control structure within the maritime operational paradigm, seeking to reveal safety challenges of the transition to autonomy. An essential aspect of the work presented in this thesis involves integrating STPA with established marine risk assessment procedures, utilizing Bayesian Networks to quantify risks. The proposed framework scrutinizes the selection of Risk Control Options (RCOs) within Marine Risk Assessment (MRA) process and examines the potential incorporation of STPA-BN within the Formal Safety Assessment (FSA) process. Drawing upon conventional maritime practices, the thesis offers an approach to develop safety control structure of autonomous ship systems and provides an analysis of the control structure components of Autonomous Navigation Systems (ANS). Hence identifies unique safety challenges posed by these innovations. In summary, this doctoral thesis serves as a technical compass guiding the maritime industry towards enhanced safety in the age of autonomous shipping. By leveraging modern hazard analysis methods, particularly STPA, and integrating them into established risk assessment practices, this research seeks to catalyse a shift towards advanced system-theoretic risk assessment processes in the maritime industry, acknowledging the evolving regulatory landscape and the complexity of the challenges at hand.
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    Managing risks in maritime remote pilotage using the basis of the Formal Safety Assessment
    (Aalto University, 2023) Basnet, Sunil; BahooToroody, Ahmad, D.Sc., Aalto University, Marine and Arctic Technology, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Research group on Safe and Efficient Marine and Ship Systems; Insinööritieteiden korkeakoulu; School of Engineering; Valdez Banda, Osiris A., Prof. Aalto University, Department of Mechanical Engineering, Finland
    Maritime pilotage is conducted in congested areas, where the risk of collision and grounding accidents is high. Hence, the pilotage operation is safety critical and has been established as a mandatory service in many countries. However, with Remote Pilotage (RP) and related technological transformation, there is a need to adapt risk management methods to address emerging risks. This thesis aims to develop a framework to manage risks in RP by identifying gaps in the Formal Safety Assessment (FSA) framework and proposes novel solutions to fulfill them. The thesis investigates Model-Based Systems Engineering (MBSE) for creating unambiguous system description models for the risk management process. Furthermore, this thesis addresses the selection challenge in MBSE by proposing a framework that assists system developers in choosing suitable MBSE language. Building upon the model, the thesis combines, System-Theoretic Process Analysis (STPA) and Bayesian Network (BN) for hazard identification and risk analysis. To reduce the limitations of other STPA-BN studies, the thesis explores the application of complexity reduction techniques such as the Parent Divorcing Technique, Noisy-OR gates, and the sub-models. Moreover, the thesis extends the STPA-BN method with a cost-benefit analysis using Influence Diagrams (IDs) for selecting a cost-effective Risk Control Option (RCO). Lastly, the thesis provides a methodology for the automatic generation of a BN risk model using an incident database and programming language, which facilitates real-time risk monitoring. The proposed frameworks and solutions are then applied to RP for managing risks in early design phases. System description models, developed with selected MBSE language, are used together with STPA to identify the RP risk events such as losses, accidents, hazards, and causal factors. For each of these risk events, the occurrence probability is determined using a BN model. The model shows that the losses with high occurrence probability are loss of customer satisfaction, damage to the ship, injury to people, and damage to the environment. Furthermore, the model shows that collision and contact accidents have a higher occurrence probability than grounding during RP in Finnish fairways. For controlling these risk events in RP, an ID is developed and numerous RCOs are evaluated based on cost-benefit analysis. As a result, a cost-effective RCO for RP is proposed in the thesis. Finally, an automatic generation of BN risk models using a pilotage incident database and Python is demonstrated. The developed tool generates and updates the BN model providing the occurrence probability of risk events for real-time risk monitoring. The results of this thesis demonstrate the applicability and effectiveness of the proposed framework. Furthermore, this thesis provides an essential foundation for managing risks in RP and facilitates its development. Last but not least, the thesis provides tools and methods supporting stakeholders in making risk-based decisions involving advanced systems.
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    Verification of vessel resistance in old brash ice channels through model scale tests
    (Aalto University, 2023) Matala, Riikka; Suominen, Mikko, Dr., Aalto University, Department of Mechanical Engineering - Academy Research Fellow, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Marine and Arctic Technology; Insinööritieteiden korkeakoulu; School of Engineering; Kujala, Pentti, Prof. Emer., Aalto University, Department of Mechanical Engineering, Finland
    Winter navigation is vital for the societies and communities living close to the polar region to ensure the year-round security of supply. Winter navigation in the Baltic Sea is based on intergovernmental cooperation on icebreaker assistance and the Finnish-Swedish Ice Class Rules. The icebreaker fleet assists merchant ships with ice-classification by providing escort on request. The ship's eligibility for icebreaker assistance depends on the current traffic restrictions, which define the lowest allowed ice class and gross tonnage to acquire assistance. The ice class of the ship sets requirements for the minimum engine power for a ship, aiming to verify sufficient ice performance for the ship with specific ice class in an old brash ice channel, which is a typical operational condition for assisted ships. Model scale tests are an essential way to verify the ship's ice performance. Ship's performance in ice is one of the key factors in the winter navigation system, however, recent environmental standards have generated substantial changes in the merchant fleet bow shapes, meaning verifying model scale practices suitability in the new circumstances is crucial. This thesis investigates ship's resistance in frequently operated, old brash ice channels using experiments on brash ice and ship correlation tests in full scale and in model scale. Through analysing the processes forming the resistance and determining the forces contributing to the processes, it scrutinises the ice properties contributing to the forces. As the thesis shows, the current model scale test practices do not sufficiently simulate all substantial processes which contribute to ship's resistance in brash ice. The results indicate that the current practices are suboptimal for realistically and uniformly simulating ship's resistance: based on evidence from correlation tests, the model tests performed according to the current practices might overestimate the brash ice resistance of certain new bow types. To secure uniform and accurate ice performance predictions for all ice-classed ships, this thesis proposes a new approach for performing a model scale test in an unconsolidated old brash ice channel. The main discovery of the thesis is to show that realistic simulation of ship resistance in an old brash ice channel in physical model scale tests necessitates realistic simulation of brash ice fragment interaction. It does this through introducing a novel methodology for model scale simulations that improve the current problems of the modelling of ice-ice interaction. This leads to improved simulation of processes, which are related to displacing the brash ice mass sideways. The new scaling approach abandons the current practice of scaling down the ice flexural strength and proves that solid ice fragments more realistically model the interaction between the ice fragments when compared to traditional model ice with scaled-down strength. The understanding acquired within this thesis improves the performance predictions in brash ice channels.