[diss] Insinööritieteiden korkeakoulu / ENG

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Industrial Metaverse: Revolutionizing Industry 5.0 with Digital Twins and Extended Reality
(Aalto University, 2024) Tu, Xinyi; Ala-Laurinaho, Riku, Dr., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Mechatronics Research Group, DigiTwin Lab; Insinööritieteiden korkeakoulu; School of Engineering; Tammi, Kari, Prof., Aalto University, School of Engineering, Finland
The industrial sector is experiencing a paradigm shift to Industry 5.0, which emphasizes the integration of human ingenuity and advanced technologies. Central to this transformation is the convergence of digital twins and extended reality (XR), which together foster a more humancentric, technology-augmented industrial ecosystem. The dissertation looks into these transformative technologies within the context of the industrial metaverse, addressing the challenges that have impeded the convergence of digital and physical spaces in industrial settings. Foremost among these challenges is the limitation of current industrial XR solutions, which lack dynamic data interaction with digital twins and robust evaluation of control accuracy. This work addresses this gap by developing a mixed reality interface that actively interacts with a digital twinbased industrial crane, accompanied by measurement protocols for accessing the application's control accuracy. This application serves as a practical entry point into the industrial metaverse, illustrating how digital and physical elements can be synchronized for enhanced operation. Expanding on this foundation, the thesis tackles the scarcity of systematic integration of XR and digital twins across varied industrial machinery and environmental settings. By introducing the TwinXR method and implementing it on two case studies, the work enables scalable, efficient XR application development that leverages digital twin descriptions for enhanced information management and system interoperation across diverse industrial settings. Finally, the research proposes a comprehensive architecture of the industrial metaverse that extends beyond prevailing consumer-centric architectures and their narrow focus on XR. This architecture integrates physical factories with the metaverse through data flow and knowledge synchronization facilitated by the interplay of digital twins and semantic models. A case study on in-plant material flow tracking illustrates the practical application and benefits of this architecture in meeting the complex demands of industrial systems. Overall, the dissertation provides a thorough exploration of the industrial metaverse, traversing from focused applications to broader integration methodology, culminating in an expansive architectural design. The findings highlight the transformative impact of the industrial metaverse in the Industry 5.0 context, where digital twins and XR consolidate to reshape industrial processes and enhancing human-machine collaboration.
Demand Response and Energy Resilience Through Electric Vehicles - Advanced Modelling Techniques and Economic Implications
(Aalto University, 2024) Einolander, Johannes; Lahdelma, Risto, Prof., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Energy Conversion and Systems; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof., Aalto University, Department of Mechanical Engineering, Finland
The energy transition, a historical shift towards renewable energy to combat climate change, introduces significant challenges, for instance, for power grid stability due to the intermittent nature of renewables. This increased variability, along with decreased possibilities for power generation regulation, necessitates an increase in flexibility from novel sources. Flexibility of electricity use, that is, the intentional adjustment of consumption based on external signals, is called demand response. One of the key components of the energy transition is the electrification of transportation. Large-scale adoption of electric vehicles can result in additional stress for power grid balancing, however, through demand response, the growing electric vehicle fleets can become an important source of the much-needed flexibility and improve energy resilience. The opportunities enabled by intelligent control of electric vehicle charging extend beyond power grid balancing, offering significant benefits for a diverse range of stakeholders. For households and individual consumers, participation in demand response can lead to considerable financial benefits and reductions in electricity costs. These advantages are further amplified through adoption of bidirectional electric vehicle charging, which, beyond financial savings, can improve household energy resilience and enable self-sustainment during power outages. This dissertation explores the multifaceted benefits and implications of electric vehicle demand response and bidirectionality focusing especially on the economic implications on the national and household levels, and on the novel utilization of electric vehicles in power outage self-sustainment. To achieve these objectives, this dissertation introduces several novel methodologies based on multivariate copulas and linear programming for event-based electric vehicle charging, demand response, and outage self-sustainment modelling. Based on the findings, the rapidly growing electric vehicle fleet can be expected to become a major source of flexibility and demand response, offering substantial benefits for power grid stability, and presenting significant economic potential. For households, utilization of electric vehicles in demand response can already yield substantial cost savings, with highest annual savings gained through bidirectional operation. Moreover, bidirectional electric vehicle charging is found to be extremely effective in sustaining household electricity use during power outages. This improvement in household energy resilience can act as a significant non-monetary incentive for bidirectional charger adoption.
Learning to See Flow - A Worker-centric Exploration Towards Task Planning and Control in Construction
(Aalto University, 2024) Görsch, Christopher; Lavikka, Rita, Dr., VTT, Finland; Peltokorpi, Antti, Prof., Aalto University, Department of Civil Engineering, Finland; Rakennustekniikan laitos; Department of Civil Engineering; Operations Management in Construction; Insinööritieteiden korkeakoulu; School of Engineering; Seppänen, Olli, Prof., Aalto University, Department of Civil Engineering, Finland
Construction projects are inherently wasteful. One reason for this is sub-optimal work preconditions for workers limiting task performance. Task pre-conditions and performance are coordinated by traditional production planning and control, which focuses on coordinating process flow, while detailed operations flow management is often left to workers. This pattern is reapplied across projects with no significant improvement to wasted efforts in task performance. In such a scenario, workers coordinate preconditions mainly autonomously. While management theory promotes autonomous decision-making for improved task performance, productivity in the construction industry has little enhanced due to a lack of understanding of aspects favoring operations flow and autonomous decision-making. This study investigated the effects of workers' task planning and control (TP&C) practices on operations flow to derive aspects of improving task performance. A mixed method approach (survey and time-motion study) in mechanical, electrical, and plumbing (MEP) work was applied. The results show that workers constantly perform TP&C activities. Their TP&C behavior differs between pre- and in-task planning. Its extent depends primarily on individual perceptions, which are impacted by trade-specifics, crew size, and other situational factors. TP&C maintains and fragments direct work (DW), on average, every 3.5 minutes. Short-term fragments support the continuation of DW, while medium- and long-term disturbances include significant wasted effort that must be mitigated. The study's theoretical contribution draws parallels between Plato's cave allegory and operations flow. Currently, workers rely on limited, subjective TP&C activities, similar to prisoners in the cave who have a limited understanding of reality. The findings indicate a need for collective, technology-enabled efforts to overcome the limits of subjective, decentralized decisions based on non-relevant information. A paradigm shift in the industry is encouraged to overcome the lack of timely, detailed, and relevant information supporting workers' situational awareness. Production planning should build on operations design involving workers to improve prefabrication, constructability, and site logistics. Production control can track location and movement to better understand the causes of disturbances, which are correlated with increased motion. Overall, the thesis promotes a systemic change in the construction industry in which operations flow is actively and not passively coordinated so that workers are not groping in the dark like the prisoners in Plato's cave.
Dynamic heating control in power and energy reduction and renovation of multifamily apartment buildings
(Aalto University, 2024) Hajian, Hatef; Kurnitski, Jarek, Prof., Tallinn University of Technology, Estonia; Airaksinen, Miimu, D Sc., SRV Group, Finland; Rakennustekniikan laitos; Department of Civil Engineering; Indoor Air Quality; Insinööritieteiden korkeakoulu; School of Engineering; Salonen, Heidi, Prof., Aalto University, Department of Civil Engineering, Finland
Energy renovation involves retrofitting existing buildings with energy-efficient technologies and introducing practices to reduce energy consumption, peak power, and greenhouse gas emissions. To support the renovation targets, this study has two objectives. First, it sought to conduct a comprehensive investigation of how dynamic heating control systems can reduce heating energy and power needs in existing buildings. This entailed evaluating the impact of reducing HC temperatures, developing a dynamic heating control algorithm, and integrating flow limiters into the heating system to enhance energy performance. Although there have been high expectations of potential energy savings achievable through dynamic heating control, our study revealed that actual energy savings may not be realized. However, significant reductions in peak power needs were quantified. This led to a study of sizing conditions to ascertain the extent to which smaller heat exchangers could be employed by implementing capacity limits through flow control. Second, the dissertation aimed to assess the efficacy of Finnish renovation practices based on Asumisen rahoitus ja kehittämiskeskus (ARA) renovation subsidies. This involved evaluating the effects of implementing various renovation packages on energy consumption in typical residential buildings in Finland, along with assessing the accuracy of Energy Performance Certificates (EPCs) and the actual energy savings achieved in the renovated buildings. Calibrated reference building simulation models validated with on-site measured data were used throughout the study. In the heating control analysis, lowering the HC temperatures resulted in a marginal energy saving of 0.6 kWh/m²a (equivalent to 0.8% of Space Heating (SH) energy) while maintaining the indoor air temperature at 21°C, revealing the almost nonexistent potential for energy savings. The developed dynamic control algorithm, enabling a reduction of the HC during domestic hot water peaks, led to a significant power reduction of more than 10% without compromising indoor air temperature. The introduction of the primary side flow limit reduced the heating sizing power and DH mass flow rate by 5.5% and 12.4%, respectively, under designed outdoor temperature conditions, enabling a more efficient use of DH system capacity. In the analysis of common renovation packages based on heat pumps and window replacements, it was noticed that official EPCs overestimated before the renovation energy use as well as energy saving by a factor of almost two because of heavily overestimated infiltration and ventilation. Renovations undertaken with ARA renovation grants generally showed good energy savings. However, typical support for about 25% of the total cost of shallow renovations dropped below 10% in a deep renovation, which was not economically feasible. These findings underscore the importance of enhancing the accuracy of EPCs in assessing energy performance.
Applications of convex optimization in naval engineering
(Aalto University, 2024) Ritari, Antti; Salazar, Mauro, Asst. Prof., Eindhoven University of Technology, The Netherlands; Coraddu, Andrea, Assoc. Prof., Delft University of Technology, The Netherlands; Konetekniikan laitos; Department of Mechanical Engineering; Mechatronics; Insinööritieteiden korkeakoulu; School of Engineering; Tammi, Kari, Prof., Aalto University, School services, ENG, Finland
Convex optimization is a class of nonlinear optimization with many useful theoretical and computational properties. The global optimum can be computed very efficiently, even for largescale problems. The numerical solvers for convex optimization require no initial guesses or parameter tuning. This thesis focuses on applying convex optimization to model several important nonlinear problems in naval engineering. Chapter 2 presents the theoretical background for this work. The thesis is written as a collection of articles, and the remaining chapters summarize the results of the articles. Chapter 3 formulates conceptual-stage marine vessel design problems as geometric programs. Although geometric programs are nonconvex, they can be reformulated as convex problems with no sacrifice in fidelity. This reformulation creates a novel possibility for fast systemlevel design optimization. Chapter 4 considers the problem of generating time-optimal trajectories for energy-limited surface vessels. The convexification techniques developed in this chapter lay the path for employing computationally robust convex optimization methods in a real-time environment with strict runtime and reliability requirements. Chapters 5 and 6 model problems that include discrete decisions. The first problem deals with lifetime fuel and power system selection, and the second problem involves hybrid power source energy management.
Solar-assisted sorption-enhanced gasification of polyethylene terephthalate (PET) plastic waste - Experimentation and process modelling
(Aalto University, 2024) Li, Shouzhuang; Vuorinen, Ville, Prof., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Energy Conversion and Systems; Insinööritieteiden korkeakoulu; School of Engineering; Järvinen, Mika, Prof., Aalto University, Department of Mechanical Engineering, Finland
Polyethylene terephthalate (PET) is a common plastic that has been widely used in packaging and textiles. In European Union countries, only 10% of PET plastic was recycled in a closed loop, and the remained was discarded in nature. Therefore, we proposed the solar-assisted sorptionenhanced gasification (SEG) to produce H2 and other materials from PET waste. This research aims to study the solar-assisted SEG of PET waste by experiments to obtain the optimized operating conditions, and then use them in Aspen Plus modelling to investigate the techno-economic performance of the system. This research was divided into four tasks: three experiments of PET steam gasification, PET steam gasification with CaO, and solar-assisted Ca looping process in bubbling fluidized beds, and the Aspen Plus modelling of SEG of PET integrated with a steam power plant and a LiBr-H2O absorption chiller to recover the excess heat in the process. Four journal papers were published accordingly to research tasks. Publication 1 revealed that gas yields increased significantly with the increasing temperatures, and the total tar yields dropped. The effect of temperature on gas products was more remarkable than steam-to-PET ratio and residence time. Carbon balance analysis showed that half of the carbon in PET was converted into tars, and CO2 was the dominant gas product. Publication 2 reported that adding CaO promoted H2 and CO2 yields and reduced tars, meaning that CaO mainly acted as a catalyst at the examined conditions at examined temperatures. Correlations between gas products and three operating parameters: temperature, CaO-to-PET ratio, and steam-to-PET ratio were fitted with the help of response surface methodology, and the gas yields were predicted well. Publication 3 studied the solarassisted Ca looping process and obtained the optimized combined temperatures of carbonation 650 °C and calcination 850 °C to minimize CaO deactivation and maximize the energy-carrying capacity, considering a reasonable mass flow rate between the solar calciner and the gasifier. Publication 4 discovered that the energy and exergy efficiencies of the integrated system were 60%–70% for both day and night modes. The annual production of H2 and benzene were 684 t and 6286 t, respectively, with an annual 19 kt of PET feedstock and capturing 21 kt of CO2. The project is feasible when the benzene price is greater than 1092 €/t and the CO2 prices are higher than 80 - 120 €/t. The results show that there is a potential to implement solar-assisted SEG of PET plastic waste to produce H2 and other valuable chemicals. This research provides a novel method for PET plastic waste upcycling sustainably with zero CO2 emission and a renewable heat source without burning additional fuels to achieve the zero plastic waste goal in the future.
Adapting Nordic Buildings for Enhanced Summertime Resilience in the Face of Climate Change
(Aalto University, 2024) Velashjerdi Farahani, Azin; Jokisalo, Juha, Dr., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Heating, Ventilation and Air conditioning; Insinööritieteiden korkeakoulu; School of Engineering; Kosonen, Risto, Prof., Aalto University, Department of Mechanical Engineering, Finland
In the face of escalating climate change impacts, understanding the resilience of buildings to extreme weather events, particularly in cold climates, is crucial for mitigating risks to human thermal comfort and well-being. This thesis addresses this issue by investigating the resilience of different buildings to climate change and its associated hot summers in Nordic climates. Through a combination of field measurements and simulation studies, the research assesses indoor overheating risks, energy consumption, and power demand in different building types, while also exploring the relationship between indoor and outdoor temperatures during heatwaves. The findings reveal significant challenges posed by high overheating risks in residential buildings, particularly in older ones in comparison to the newer ones designed based on the latest building codes. The study highlighted the effectiveness of passive strategies in mitigating risks. However, results showed that there is a need for mechanical cooling systems in residential buildings to ensure comfortable and healthy indoor temperatures during current and future heat events. The needed cooling electricity was shown to be considerably small compared to other energy consumptions in the buildings. Additionally, the study identifies strong correlations between indoor and outdoor temperatures during the hot summers that weakened during the prolonged heatwaves. This highlights the complex and dynamic nature of these relationships under different environmental conditions and emphasizes the importance of considering extreme heat events in the design and operation of buildings in cold climates. In office buildings, all-air and air-water systems were found to perform equally in terms of cooling energy consumption and indoor temperature conditions under a changing climate. While the maximum cooling power demand would be higher with the all-air system (ventilative) during extreme weather conditions. However, the cooling electricity increased up to 47% in the future average climate and up to 128% in the future extreme climate with the air-water system, and up to 51% in the future average climate and 108% in the future extreme climate with the all-air system by 2050 depending on the CO2 emission scenario.
Prefabrication in Construction: A Systemic Approach to Impact and Implementation
(Aalto University, 2024) Chauhan, Krishna; Seppänen, Olli, Prof., Aalto University, Department of Civil Engineering, Finland Lavikka, Rita, Dr., VTT, Finland; Rakennustekniikan laitos; Department of Civil Engineering; Construction Management; Insinööritieteiden korkeakoulu; School of Engineering; Peltokorpi, Antti, Prof., Aalto University, Department of Civil Engineering, Finland
Compared to other industries, the construction industry is widely recognised as complex, fragmented and non-innovative. To address this issue, prefabrication, as a potential solution offering disruptive innovations, can drive the construction industry towards greater industrialisation. Numerous studies have extensively examined the impact of prefabrication and presented its advantages over traditional methods. However, the implementation of prefabricated solutions remains limited in construction projects. One of the primary causes of this issue is the lack of consensus about the benefits of prefabrication among all parties involved. Previous research has overlooked systemic viewpoint to analyse the impacts of prefabrication implementation in construction projects. The objective of this study is to enhance the understanding of prefabrication adoption through a systemic approach, enabling a comprehensive analysis of its impacts and implementation. This study employs mixed methods consisting of qualitative and quantitative techniques. Qualitative data are collected through the analysis of multiple case studies, interviews, workshops, and documents. Quantitative data is gathered through a questionnaire survey. To achieve the desired objectives, the research is conducted in two parts: first on impact analysis and second on implementation approaches. The impact analysis includes the development of a comprehensive method which adopts a systemic, multi-stakeholder perspective for evaluating the direct and indirect monetary and nonmonetary impacts of prefabrication. Using this method, the impacts of four prefabrication products are examined. The subsequent analysis of this research focuses on identifying benefits of prefabrication for each stakeholder without compromising the interests of the other parties involved. The study is carried out in both new building and renovation projects. The research findings indicate a direct relationship between the extent of product modularity and monetary and non-monetary benefits. Despite the possibility of higher direct expenses for prefabricated products, the cost may be less than traditional construction due to indirect benefits. The study further highlights the key benefits and challenges of implementing prefabricated products. The benefits include shorter project schedules, enhanced quality, and improved workflow, while the challenges include the immutability of heritage buildings, old building tolerances and limited construction spaces. This study makes significant contribution in two key areas. First, it proposes a method for evaluating the impact of prefabrication considering systemic perspective and analyses both monetary and non-monetary effects which holds potential in decision-making processes for the choice between prefabrication and onsite construction. Second, it provides empirical evidence of the advantages that each project party can gain from implementing prefabrication.
Pyrolysis and Cracking of Nordic Timbers Under External Heat Exposure
(Aalto University, 2024) Rinta-Paavola, Aleksi; Rakennustekniikan laitos; Department of Civil Engineering; Fire Safety Engineering; Insinööritieteiden korkeakoulu; School of Engineering; Hostikka, Simo, Prof., Aalto University, Department of Civil Engineering, Finland
Timber as a construction material has been gaining renewed interest in recent times. However, wood is inherently associated with an increased risk to fire safety. To address the fire risks of wood construction, regulators impose prescriptive building codes that define the limits for use of timber in construction. Performance-based fire safety design is the only method to realize timber construction projects that go beyond the boundaries set by prescriptive building codes. Computational fluid dynamics (CFD) -based fire simulation is a common tool in performancebased fire safety engineering. In realistic CFD fire simulations involving wooden surfaces, wood is defined by a material model that predicts char front progress and release of combustible volatiles, thus interacting with flaming in the gaseous phase. This thesis proposes material models for spruce and pine woods for use in performance-based fire safety design. The thesis also provides an experimental dataset of direct observations of cracking on surface of charring timber to help in implementation of cracking effects to material models in later research. During this work, two independent material models were developed for the studied wood species of spruce and pine: one that assumes wood decomposing through pyrolysis as a single component (single reaction), and another that observes pyrolysis as a sum of individual decomposition reactions of wood primary components: hemicellulose, cellulose and lignin (parallel reactions). Material properties and decomposition kinetics of wood were studied by use of various microscale experimental methods, such as thermogravimetry and differential scanning calorimetry. Cone calorimeter experiments were used in estimation of any remaining model parameters, and in material model validation. The single reaction model arises as the preferable option, offering a similar quality of fit to the experimental data as the more complex parallel reactions model, but without the associated increased model uncertainty. Validation using large-scale experiments revealed that the model is highly sensitive to the surrounding oxygen concentration of the surrounding atmosphere, and inclusion of the oxidation reaction is important for correct fire spread prediction. Formation of cracks on charring spruce, pine and birch woods was studied in real time using an infrared camera. The experiments revealed a linear relationship between heat flux and the inverse of the square root of crack formation time, analogously to the time to ignition in ignition model for thermally thick solids. Contrary to expectations, the number of cracks did not grow consistently as a function of heat flux. The analytical formulation of a previously existing cracking model predicts the number of cracks in correct order of magnitude, but not accurately.
Sector-Coupling and Renewable Energy Integration in Low-Carbon District Heating: Perspectives of Economics, Environment and Supply Security
(Aalto University, 2024) Javanshir, Nima; Syri, Sanna, Prof., Aalto University, Department of Mechanical Engineering, Finland; 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
In the face of a global climate crisis, the imperative to reduce carbon emissions throughtransforming our energy infrastructure is paramount. This dissertation focuses on decarbonizing District Heating (DH) systems in Finland by integrating power-to-heat (P2H) technologies, including heat pumps and electric boilers, and renewable energy sources such as wind power, considering diverse energy market scenarios. Given the substantial role of heating in Finland's energy demand and the prevalence of DH systems, this topic is pivotal in meeting both national and international environmental objectives. The study encompasses case studies for Finnish cities, analyzing systems including a mid-sized network reliant on local fuels biomass and high-emission fuel peat and the large-scale networks of Helsinki metropolitan region, still dependent on imported fossil fuels, primarily natural gas and coal. This approach covers environmental and economic aspects, considering the fluctuating global fossil fuel prices and the increasing costs associated with carbon dioxide emissions allowances and fuel taxes. This dissertation evaluates the feasibility of partly electrified DH systems under different market conditions, including periods of low, regular, and high energy market prices, including Europe's 2022 energy crisis. This thesis also explores the technical and economic potential of electrified DH systems in the electricity and various balancing markets across different scenarios through modeling and simulation of the case studies. The findings indicate significant environmental benefits as a reduction in carbon dioxide emissions. However, this transition is not without its challenges. Notably, increased reliance on biomass combustion and electricity market volatility were recognized, potentially leading to further environmental and energy security issues. Economically, while electrification offers protection against the volatility of fossil fuel prices and promises long-term economic advantages, the initial investment and potential increases in consumer heating costs present challenges in the short to medium term. The participation of electrified DH systems in balancing markets could provide additional operational profits, yet complexities of system operation and management require careful consideration. DH systems were found to be resilient even under extreme energy prices, however, shutting down combined heating and power plants (CHP) would result in significant losses in potential electricity market income. In conclusion, the electrification of DH systems in Finland presents a promising pathway towards a sustainable heating sector. However, achieving this goal requires a balanced and integrated approach, incorporating technological innovation, strategic planning, and economic incentives.
Inorganic foundry binders for sustainable sand molding
(Aalto University, 2024) Anwar, Nurul; Jalava, Kalle, Dr., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Materials to Products; Insinööritieteiden korkeakoulu; School of Engineering; Orkas, Juhani, Prof., Aalto University, Department of Mechanical Engineering, Finland
A good sand mold is an indispensable prerequisite to obtaining a good metal casting. Although sand casting is one of the oldest metal forming technique known to humans, research for alternative molding materials has never stopped, most notably to meet increasing demand for quality, better economics and to meet ever increasing environmental restrictions and regulations. The principal material of sand molds are the sand, binder and different additives depending on the application. Growing worldwide demands for sustainable manufacturing and an increased adoption of additive manufacturing across foundry industry are two underlying motivations for the search of alternative material in this dissertation. Although different organic binders are popularly used in sand molding, there is concern over the volatile organic compounds (VOCs) emitted from thermal breakdown at elevated temperature. Also, the use of 3D printed sand molds is on the rise, which usually employ greater volume of binder than traditional method. It is therefore necessary to use more environmentally friendly binders. In recent times, the interest in inorganic binders have re-emerged due to their environmental friendliness. However, the performance of these need to be properly tested before widespread introduction to foundry practices. Additionally, although silica is the most widely used sand for sand casting, alternatives are sought for various reasons like worker health safety, increased scrutiny for silica sand mining etc. This dissertation is a summary of 4 publications which explored many different sands, binders and additives. Inorganic binders were a focus of these tests while organic binders were also used in some tests to provide a fiducial reference point. The dissertation aims to facilitate the choice of mold materials with a more extensive outlook into their characteristics through a serious of sand, mold and casting quality test. Examples include sand flowability test, mold strength tests, loss on ignition tests, gas emission tests, SEM imaging of fracture surface, 3D scanning of mold and casts for mesh-to-mesh analysis, surface roughness of castings etc. Data from this dissertation will help in part the transition from the use of organic liquid binder to solid inorganic binder, enabling foundries to switch to more sustainable practices. Special emphasis is given to inorganic solid silicate binder, as it has the potential in the sustainability front as well as the simplification of 3D printing of sand molds. Effect of five different additives on solid silicate binder was found out that will aid in further development of the binder. Performance of a heat resistant 3D printed plastic pattern material was explored as well, which can be used with heat hardened inorganic molds.
Amplifying Unheard Voices - Towards Inclusive Innovation and Development
(Aalto University, 2024) van der Marel, Floris; Konetekniikan laitos; Department of Mechanical Engineering; Swinburne University of Technology; Insinööritieteiden korkeakoulu; School of Engineering; Björklund, Tua, Prof., Aalto University, Department of Mechanical Engineering, Finland; Kocsis, Anita, Prof., Swinburne University of Technology, Australia
An increasingly diverse engineering workforce supports innovation and creativity. However, whether diversity translates to improved organisational performance depends on whether employees are able to voice issues and ideas. Voice is conceptualised as employees' ability to speak up and be heard. While much research has been done by industrial relations, human resource management, and organisational behaviour scholars, their different ontological assumptions have made it difficult to integrate the learnings. As such, much is still unknown about how socioorganisational factors influence employee voice, particularly in a more diverse workforce. Building on existing literature, I argue that motivation at work and assessment of voice opportunities are key indicators of employees' resolution to voice or not. Both work motivation and voice opportunity assessment are influenced by collaborative sensemaking and former voicing attempts. In this dissertation, I dive deeper into the nuance and intricacies that influence diverse employees' experiences in creative contexts. Based on semi-structured interviews with 130 designers, engineers, and hospital employees targeting job motivation and voice opportunity assessments, I identify patterns across different contexts that might apply to other contexts worldwide. One study applies an action research approach, teaching design to the hospital employees to shed light on changed perceptions and frames as a result of a participatory design intervention. Each study highlights the highly social context of creativity and innovation, influenced by continuous interactions with people around them. Indeed, my results suggest that both motivation and voice opportunity assessment were influenced by stubborn beliefs present in collaborative sensemaking, disproportionately impacting historically unheard voices. Additionally, spirals of silence might hinder attempts to amplify unheard voices due to ingrained silence as a result of previous failed attempts by employees similar to them. In conclusion, I argue that more attention should be paid to the role of collaborative sensemaking in employee voice in order to leverage diverse voices toward inclusive innovation and development.
Enhancing the structural stress assessment of distorted lightweight ship deck structures
(Aalto University, 2024) Mancini, Federica; Romanoff, Jani, Prof., Aalto University, Department of Mechanical Engineering, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Marine and Arctic Technology; Insinööritieteiden korkeakoulu; School of Engineering; Remes, Heikki, Prof., Aalto University, Department of Mechanical Engineering, Finland
Pursuing enhanced ship performance has driven lightweight structural solutions into modern cruise ship design. Among available strategies, the employment of thin steel plates in welded superstructure decks appears achievable, more sustainable and economically feasible. However, thin plates are susceptible to complex welding-induced distortions, which cannot be disregarded in the fatigue and limit state analysis of the welded structure. Since the effect of those distortions is not entirely considered by ship design rules, its evaluation requires full-field scanning of welded plates to be modelled in costly numerical analyses. This thesis investigates computationally efficient structural stress assessment approaches on buttwelded 4 mm-thick plates in stiffened panels from actual shipyard production, resulting in average to severe initial distortions according to classifications in the marine structures community. The distortion measurement and characterisation are followed by the 3D geometrically non-linear finite element analysis (GNL-FEA) of the panels under tension, simulating the effect of hull girder bending on the superstructure decks. The 3D model is validated against uni-axial tensile tests on the panels. Thereafter, a gradual scale reduction from 3D to 2D and 1D models is performed numerically and analytically, where the von Kármán kinematic assumption accounts for the geometric non-linearity. As a last step, a beam model is developed for a simple half-sine curvature and considering the effect of weld rigidity. In characterising the distortions, both amplitude and slope parameters need to be considered. For multi-buckled shapes with amplitudes below the plate thickness, a 2D analytical model neglecting the geometric discontinuity due to the weld can predict global structural stresses over the panel plate field; however, the weld cross-section must be considered in the local structural stress assessment of the welded area. For the latter, the 1D GNL-FEA of a distorted longitudinal profilelocated within 60% of the plate width results in less than 10% error. The 1D finite element model remains reliable if the distortion is included up to its first buckle from the weld location. Consequently, the analytical beam model can be adapted to the butt-welded area between thin plates in stiffened panels. Such an adaptation requires future research on the geometric parameters and boundary conditions in beam modelling.
On-demand ridesharing operation: matching, pricing, and routing
(Aalto University, 2024) Zhou, Ze; Rakennetun ympäristön laitos; Department of Built Environment; Spatial Planning and Transportation Engineering; Insinööritieteiden korkeakoulu; School of Engineering; Roncoli, Claudio, Assoc. Prof., Aalto University, Department of Built Environment, Finland
Excessive private vehicles in densely populated cities, together with the increasing need for mobility, have been constantly challenging the existing transportation systems. Fortunately, mobility on-demand services, such as ride-hailing and ridesharing, are becoming a growing trend in megacities due to their convenience and cost-effectiveness. These services are envisioned as enablers of a shift from car ownership to vehicle usage. Nonetheless, the impact of mobility on-demand service on transport systems is complicated and largely depends on governance and operation strategies. Accordingly, this dissertation aims at developing novel management strategies, involving matching, pricing, and routing, to improve ridesharing system efficiency. Meanwhile, the impact of such methods on urban transportation systems is evaluated. Firstly, an innovative strategy is proposed to integrate vehicle assignment with the prediction of time-dependent link travel times. We unify the assignment and routing problem into a linear integer problem where k-shortest paths are provided to reduce congestion. The results indicate that the proposed strategy can significantly improve ridesharing system performance, such as reducing the passengers' waiting and travel times, by mitigating congestion effects arising from ridesharing fleets. Additionally, we account for traveller's modal choice and ridesharing pricing fairness. A novel discounting method is designed based on the proposed fairness principles. Moreover, computationally efficient optimisation models are constructed accounting for co-existing ride-hailing and ridesharing services. The real travel dataset is utilised to assess the proposed method. The results indicate that the proposed optimisation strategy, considering traveller behaviour and fairness, can significantly improve fleet performance while maintaining fair service quality. Lastly, we present a simulation-based service assessment framework to test online ridesharing strategies with shared autonomous vehicles. Individual socio-demographic features are considered in generating future demand for SAVs. Travellers' mode choices are explicitly modelled, and advanced ridesharing strategies, involving optimal matching and pricing, are tested in a mixed-traffic urban network, with both private cars and shared autonomous vehicles. Compared to rule-based methods, optimal matching and fairness pricing combined method can greatly improve both fleet performance and transportation efficiency. In summary, this dissertation reveals that dynamic ridesharing offers a promising pathway toward achieving more sustainable mobility, provided it is properly managed.
Replacing fossil fuels in district heating - modelling investments, impacts, and uncertainties
(Aalto University, 2024) Lindroos, Tomi J.; Rämä, Miika, D.Sc. (Tech.), VTT Technical Research Centre of Finland, Finland; Konetekniikan laitos; Department of Mechanical Engineering; Insinööritieteiden korkeakoulu; School of Engineering; Syri, Sanna, Prof., Aalto University, Department of Mechanical Engineering, Finland
Heating and cooling, including industrial heat, consume half of the final energy use in the EU and only 20% of it is produced from renewable sources. District heating (DH) could help decarbonizing heating, but DH sector must reduce its current emission first. In this Thesis, energy system modelling is applied to study investments to fossil-free DH production and related uncertainties. This Thesis uses an existing long-term energy system model TIMES-VTT and develops new more detailed DH models that capture additional real-life constraints and have faster solve times allowing extended uncertainty analysis. The electrification route includes many scalable technologies to replace fossil fuels in DH generation. Large heat pumps were the most robust of the studied investment options unless suffering from high electricity grid fees and taxes. However, local excess heat sources are often significantly smaller than the heat demand, especially in large cities. Ambient heat sources, such as sea water or air, could complement the available heat sources, but this depends highly on local conditions and heat demand density. The biomass route provides a range of well-rounded technologies to replace fossil fuels in district heating. However, this Thesis further strengthens the conclusion that there is not enough biomass available to replace all fossil fuels in DH even in Finland. Increasing biomass demand and decreasing forest sinks in the EU create significant uncertainties over the future availability and price of sustainable biomass. Certain upcoming technologies, such as nuclear district heating and bioenergy with carbon capture and storage, seem promising future decarbonization options, but they need technology development and demonstration units first. In the course of work, large system models proved to be more flexible the more detailed DH models. As a result, large system models indicated faster decarbonization leading to a situation where studies giving background information for climate and energy policies have lower-cost and faster decarbonization of heating sector than what may be achievable. Each modelling study should consider a large range of uncertainties, or they risk drawing flawed conclusions based on too narrow set of modelled cases and assumption ranges. The main sources of uncertainties in the results of this Thesis were related to the variability of electricity generation and price, biomass availability and price, natural gas price, investment costs of new units, breakthrough of new technologies, and the required phase of emission reductions.
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.
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.
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.
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.
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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