Tehoelektroniikan ohjausyksikön suunnittelu rinnakkaiskytkettyjen DC/DC-muuntimien ohjaukselle

The ongoing electrification of both passenger and commercial vehicles is driving the increased demand for reliable high-power charging stations. These advanced direct current (DC) fast charging stations are capable of delivering power levels exceeding 400 kW, usually with the help of multiple DC/DC converters operating in parallel configuration. As powerlevels increase, the role of DC/DC converters becomes critical for ensuring accurate power delivery and maintaining high uptime at DC charging stations. To optimize total charging station performance, these converters must operate efficiently, minimizing power losses during power conversion. Achieving this requires fast and reliable communication between the power electronics controller and the multipleDC/DC converters, ensuring the desired power output with peak efficiency across the operating range of the system. This thesis presents the design and implementation of a power electronics communication controller capable of controlling parallel-connected DC/DC converters. The Fast Serial Interface communication protocol, developed by Texas Instruments, is used to establish fast and reliable communication between the controller and the DC/DC converters. A model-based design approach is employed to accelerate the development and testing of the software, utilizing automated code generation for Texas Instruments C2000 microcontrollers in Simulink environment. The developed communication system enables synchronization of pulse-width modulation (PWM) signals for the parallel-connected DC/DC converters and manages load distribution to minimize stress on the individual converter. This approach allows for the control of software-defined power converters with faster control loops,leading to improved efficiency and enhanced load management across the DC/DC converters. In summary, this work advances DC charging station technology by providing a robust communication system that enhances the performance, reliability, and control efficiency of DC/DC converters.Liikenteen sähköistyminen lisää luotettavien ja suuritehoisten latausjärjestelmien kysyntää. Nämä kehittyneet tasavirtalatausjärjestelmät kykenevät tuottamaan yli 400kW:n lataustehon, yleensä useiden rinnakkaiskytkettyjen DC/DC-muuntimien ansiosta. Tehojen kasvaessa, DC/DC-muuntimien merkitys korostuu, sillä nämä mahdollistavat korkean tehosiirron, hyötysuhteen ja käyttöasteen latausjärjestelmille. Latausjärjestelmän hyötysuhteen maksimoimiseksi on tärkeää, että DC/DC-muuntimet pyrkivät minimoimaan tehohäviöt, jotka syntyvät tehosiirron aikana. Tämän edellyttää nopeaa ja luotettavaa kommunikointia tehoelektroniikan ohjausyksikön ja useiden DC/DC-muuntimien välillä. Tässä työssä suunnitellaan ja kehitetään tehoelektroniikan ohjausjärjestelmä, joka mahdollistaa kommunikoinnin useiden DC/DC-muuntimien ja tehoelektroniikan ohjausyksikön välillä. Kommunikointiprotokollana käytetään Texas Instrumentsin kehittämää Fast Serial Interface tiedonsiirtoväylää, joka mahdollistaa nopean ja luotettavan kommunikoinnin DC/DC-muuntimien välillä. Ohjauksen kehittämisessä hyödynnetään mallipohjaista suunnittelua, jossa voidaan hyödyntää automaattista koodin generointia ja siten laadukkaampaa koodin testausta ja dokumentointia. Koodi generoidaan Texas Instrumentsin C2000 reaaliajassa toimivalle mikrokontrollille. Tässä työssä kehitetty kommunikoinnin ohjausjärjestelmä mahdollistaa DC/DCmuuntimien PWM signaaleiden synkronoinnin sekä kuorman jakamisen muuntimien välillä. Nopea kommunikointijärjestelmä mahdollistaa tarkan ohjauksen useiden DC/DC-muuntimien välillä, jolla muuntimien hyötysuhdetta koko toiminta-alueella sekä kuormanhallintaa voidaan parantaa latauksen aikana. Tämä edistää latausjärjestelmien kehitystä tarjoamalla luotettavan ja nopean kommunikoinnin useille rinnakkaiskytketyille DC/DC-muuntimille, joilla muuntimien hyötysuhdetta, tehokkuutta ja luotettavuutta voidaan parantaa

The sensuous and relational potential of reading picturebooks: Designing for a civic engagement strategy

This thesis investigates how sensuous awareness, and relational aesthetics can inform and contribute to the civic engagement strategies of the reading promotion project Den Nordiska Bokslukaren (Bokslukaren). As Bokslukaren is a Nordic initiative, that seeks to promote both reading in the Nordic region as well as the reading of modern Nordic picturebooks, it has the potential to connect and civically engage children through the act of reading. Using Design-Based Research as a methodological framework, the research explores the interconnection of theory and practice through an iterative design process. Throughout the design process’ problem phase, the thesis explores contemporary research in the intersection of education and pedagogy including concepts such as children’s picturebooks, literacy competencies and civic engagement. The literature review draws out the connection between early childhood civic engagement, literacy skills and critical thinking, showing how these not only affect but are being affected by the students’ level of cultural participation and social background as well. Subsequently, this impacts the upholding of our democracy and Nordic welfare societies. During the design process’ second phase, the thesis explores a set of design principles, which lay the foundation for the creation and testing of first a mock-up and then a prototype of the final design: A set of Conversation Cards created to engage and scaffold the adults reading with children. The third design phase includes an evaluation with stakeholders, ensuring both collaborative elements as well as input from the initiators behind Bokslukaren. Civic engagement is a skill that needs to be taught and trained, which shows the importance of strengthening the pedagogical personnels’ ability to teach this skill. As the findings and reflections from the final phase show, the cards have the potential to prompt a more embodied understanding of the act of reading and its democratic potential. By using sensuous awareness and relational aesthetics in the design, the cards invite pedagogical personnel to explore a more holistic approach to civic engagement

The environmental value of nuclear power in Finland: A case study of Olkiluoto 3

As countries grapple with the dual challenges of decarbonization and energy security, the role of nuclear power remains hotly debated. While many studies have focused on the environmental consequences of nuclear plant closures, far less is known about the real-world impact of new nuclear capacity entering the grid. This paper fills that gap by examining the commissioning of Olkiluoto 3 (OL3)—Finland’s first new large-scale nuclear reactor in decades. High-frequency data from 2022 to 2023 are used to estimate OL3’s marginal effect on emissions through a fixed-effects regression approach inspired by wind power research. The results show that OL3 significantly reduces CO2 (–56.34 kg/MWh), SOx (–0.66 kg/MWh), and NOx (–0.11 kg/MWh), with the largest offsets observed during high-demand periods. Most of these reductions stem from the displacement of fossil fuel-based generation and electricity imports. Monetizing these benefits using established social cost estimates yields a total environmental value exceeding €107 million during the ramp-up phase, rising to about €384 million annually under full operation. These findings provide empirical support for the role of nuclear power in reducing emissions, improving air quality, and displacing imported electricity—highlighting its value in carbon-neutrality strategies and energy security planning

A unified fracture model for cleavage and ductile fracture

Publisher Copyright: © 2025, Association of American Publishers. All rights reserved.With increased plastic deformation strength, the body-centers cubic materials tend to switch from ductile fracture model to cleavage fracture, despite the increase caused by either intrinsic microstructure or alloy manipulation or extrinsic loading conditions, e.g., lowering temperatures. Due to the significant difference in failure mechanisms, current modeling approaches, either the fracture mechanics or damage mechanics-based models, treat them with separate and decoupled strategies. However, many recent developments in high-strength engineering materials or applications under extreme conditions encounter more often the meeting and interaction of these two fracture modes. This study, therefore, aims to propose a unified fracture model that is capable of predicting both ductile and cleavage fracture under a consistent mechanics framework and autonomously switching the models depending on the loading conditions. The model is calibrated and validated by high-strength bcc steels with tensile strength 1000 MPa and under quasi-static deformation at room temperature. The failure mechanisms are analyzed and confirmed by fracto graphy and the microstructure features controlling the two fracture models are investigated by multi scale microstructure characterization. The developed model as well as the microstructure-property correlation eventually provides inspiration for formulating a meso-scale mechanism-based model to bridge with the mechanics-based model and also shed light on material design with tailored fracture resistance.Peer reviewe

Automatic Classification of Voice Disorders and Phonation Types from Speech Signals

Speech is the most natural form of human communication that not only conveys a message in the form of language, but also transfers information about speaker attributes such as emotions, age, and state of health. Systems that automatically classify this para- and extra-linguistic information have received considerable attention in speech technology. One area of this research is the study of automatic classification of voice disorders from speech. This area has potential applications in voice care as it provides objective and cost-effective analysis tools compared to subjective and time- consuming auditory-perceptual assessments currently performed by clinicians. This thesis investigates the effectiveness of various feature extraction methods and supervised machine learning (ML) and deep learning (DL) techniques in the development of automatic speech-based classification systems for two tasks: (1) classification of voice disorders and (2) classification of phonation types. Multiple classification systems are built, each designed to address a specific topic. The first topic is the study of systems to detect voice disorders in various laryngeal diseases from sustained phonation of vowels. Moreover, the application of data augmentation (DA) is studied in this topic. As the second topic, the thesis investigates the detection of dysarthria and the multi-class classification of the severity level of dysarthria from speech. As the third topic, the thesis investigates the classification of three phonation types (breathy, modal, and pressed). In the classification of voice disorders, the use of convolutional neural networks (CNNs) with 2- dimensional spectral feature representations achieved better performance than 1-dimensional features. Moreover, the use of DA methods in the system training showed absolute accuracy improvements of up to about 4%. In the classification of dysarthria, the use of pre-trained model- based features showed in the best cases absolute accuracy improvements of about 10% compared to conventional features. Furthermore, fine-tuning the pre-trained models resulted in features with better generalization capabilities in dysarthria detection. In the classification of phonation types, the use of the neck surface accelerometer (NSA) signal showed better classification performance compared to the speech signal. In addition, pre-trained model-based features outperformed the conventional features for both speech and NSA signals. In conclusion, this thesis resulted in improvements in automatic, speech-based classification of voice disorders by combining ML and DL classifiers with spectral and pre-trained model-based features and by taking advantage of NSA in the classification of phonation types

Technical, environmental, and safety aspects in LignoSphere pilot plant design

Publisher Copyright: © 2024 The Author(s)The development of pilot plants is important in establishing new technology to close the gap between lab-scale and full-scale operations by minimizing technical uncertainties. Currently, limited research is available to evaluate different aspects of pilot plants for producing lignin-based materials before commercialization. This paper focuses on designing a safe and eco-friendly pilot plant for optimizing production of dried colloidal lignin particles (CLPs). The process starts with dissolving lignin in a ternary solvent mixture, introducing it into water to generate CLPs via self-assembly, recovering the solvents, and spray-drying CLPs. Based on reported lab-scale results, a detailed study was conducted to design the pilot plant, considering the technical, safety, and environmental factors according to standards and European Union legislation. The planned daily capacity of the pilot plant was 20 kg with 2.2 M€ fixed capital costs. This process design research can be applied in similar processes that involve lignin dissolution before scale-up.Peer reviewe

Lanthanum doped hafnium oxide thin films deposited on a lateral high aspect ratio structure using atomic layer deposition: A comparative study of surface composition and uniformity using x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry

Publisher Copyright: © 2024 The AuthorsHafnium oxide (HfO2) thin films doped with lanthanum (La) can achieve ferroelectricity, making the material applicable in transistor and memory technologies. To downscale future devices in the semiconductor industry, the application of the doped HfO2 material requires deposition on complex microscopic three-dimensional (3D) structures. A widely used process for the preparation of doped HfO2 thin films is atomic layer deposition (ALD). With 3D geometries, it is challenging to deposit materials homogeneously and to effectively characterize them. To forego the difficulties in film characterization, two-dimensional (2D) PillarHall lateral high aspect ratio (LHAR) test structures are used. These structures expose a lateral surface to facilitate the conformality analysis of thin films deposited using two different ALD processes. In this work, we aim to further advance the arsenal of analysis techniques used to characterize La doped HfO2 thin films by using x-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to analyze uniformity and composition. The XPS technique can be applied and established as a method for the optimal analysis of thin films deposited on LHAR structures. Both techniques provide a complementary analysis of material formation, elemental distribution, measurement along the LHAR depth range, and can probe differences between deposition processes.Peer reviewe

Interfacial Modification for High-Efficient Reversible Protonic Ceramic Cell with a Spin-Coated BaZr0.1Ce0.7Y0.2O3−δ Electrolyte Thin Film

Publisher Copyright: © 2024 American Chemical Society.Slurry spin coating is an effective approach for the fabrication of protonic ceramic electrolyte thin films. However, weak adhesion between the electrode and spin-coated electrolyte layers in electrochemical cells due to the low sinterability of the proton-conducting perovskite materials usually lead to a high interfacial resistance and thus a low performance. Herein, we report a method to improve the interfacial connection and boost the performance of protonic ceramic cells based on a BaZr0.1Ce0.7Y0.2O3−δ (BZCY) electrolyte. Ni-BZCY anode functional layer, BZCY electrolyte layer and La0.6Sr0.4Co0.2Fe0.8O3−δ-BZCY cathode functional layer are all fabricated by slurry spin coating. The electrode functional layers and the components of the electrolyte slurry influence the microstructure of the single cell and the kinetics of the electrochemical processes significantly. A peak power density of 2345 mW cm-2 is achieved at 700 °C in the fuel cell mode, and a current density of -3.0 A cm-2 is obtained at an applied voltage of 1.3 V in the electrolysis mode.Peer reviewe

Link between T-Linear Resistivity and Quantum Criticality in Ambipolar Black Phosphorus

Publisher Copyright: © 2024 American Chemical SocietyThe interplay between strong Coulomb interactions and kinetic energy leads to intricate many-body competing ground states owing to quantum fluctuations in 2D electron and hole gases. However, the simultaneous observation of quantum critical phenomena in both electron and hole regimes remains elusive. Here, we utilize anisotropic black phosphorus (BP) to show density-driven metal-insulator transition with a critical conductance ∼e2/h which highlights the significant role of quantum fluctuations in both hole and electron regimes. We observe a T-linear resistivity from the deep metallic phase to the metal-insulator boundary at moderate temperatures, while it turns to Fermi liquid behavior in the deep metallic phase at low temperatures in both regimes. An analysis of the resistivity suggests that disorder-dominated transport leads to T-linear behavior in the hole regime, while in the electron regime, the T-linear resistivity results from strong Coulomb interactions, suggestive of strange-metal behavior. Successful scaling collapse of the resistivity in the T-linear region demonstrates the link between quantum criticality and the T-linear resistivity in both regimes. Our study provides compelling evidence that ambipolar BP could serve as an exciting testbed for investigating exotic states and quantum critical phenomena in hole and electron regimes of 2D semiconductors.Peer reviewe

Digital services and competitive advantage: Strengthening the links between RBV, KBV, and innovation

Research into the Resource-Based View (RBV) and Knowledge-Based View (KBV) of firms has evolved over the last 30 years from being focused on the control of physical resources, through knowledge-based digital resources, to innovation. This paper considers a service perspective of RBV-KBV to help explain differences in the competitive advantage attributable to digital and physical resources. Such an understanding helps explain the evolution of RBV-KBV research over the last 30 years and strengthens the links between the established research themes of RBV, KBV, and innovation. Competitive advantage can be created and retained through digital resources but sustainable competitive advantage for digital service firms relies on those physical resources that provide the dynamic capabilities to innovate, and so continually develop the digital resources.Peer reviewe