http://lutpub.lut.fi:80 LUTPub on Lappeenrannan teknillisen yliopiston avoin julkaisuarkisto. LUTPub sisältää Lappeenrannan teknillisen yliopiston kandidaatintöitä ja -tutkielmia, diplomitöitä, pro gradu -tutkielmia, lisensiaatintöitä, väitöskirjoja sekä näiden tiivistelmiä. Lisäksi LUTPubiin on tallennettu artikkeleita, tutkimusaineistoja ja esitysmateriaaleja. LUTPub korvaa aiemmin käytössä olleen Doria-julkaisuarkiston ja se toimii rinnakkaistallenteiden tallennuspaikkana. Wed, 17 Jun 2026 00:39:45 GMT 2026-06-17T00:39:45Z http://lutpub.lut.fi:80/handle/10024/172428 The effect of an active rectifier on motor drive system losses Arsalan, Muhammad This thesis investigated the effect of replacing a passive diode bridge rectifier with an active rectifier in an electric motor system fed by converter and analysed its impacts on system losses and performance. Two converter configurations were developed and compared using MATLAB/Simulink. The first model consisted of a passive diode bridge rectifier connected to a voltage source inverter (VSI), where the inverter output voltage and frequency were regulated using an open-loop volts-per-hertz (U/f) control strategy to control the operation of the induction motor. The second model replaced the passive rectifier stage with an IGBTbased active rectifier while maintaining the same VSI and motor control parameters to provide a fair comparison between both systems. The AFE control system utilized synchronous reference frame control, where the DC-link voltage is regulated through directaxis current control while maintaining improved grid-side current quality. The benchmark used for comparison was a motor test setup. Both the simulation results were compared with those measured from the original motor test setup. The hardware setup motor had a nominal power of 2.2 kW. The performance indicators for the analysis included: the effect of active rectifier on grid side harmonics, effect on the DC ripple, converter losses, effect on the dynamic performance of the motor and effect on the power factor. The results showed that the active front-end converter significantly improved the grid-side performance by reducing harmonic distortion and achieving near-unity power factor compared to the passive diode bridge rectifier. In addition to that, the improved DC-link voltage regulation provided by the active rectifier enhanced motor drive performance by significantly reducing torque and speed ripple under different operating conditions. However, the additional controlled semiconductor devices and high frequency switching operation increased the converter losses. Therefore, the active rectifier provided improved power quality and controllability at the expense of increased converter losses. Thu, 01 Jan 2026 00:00:00 GMT http://lutpub.lut.fi:80/handle/10024/172428 2026-01-01T00:00:00Z http://lutpub.lut.fi:80/handle/10024/172427 Scaling through digital transformation : a comparative study of Revolut and BCC Messina, Filippo This research illustrates the impacts of digitalization on the scaling process and whether the influence differs by organizational context. While digital technologies are often associated with rapid and scalable growth, existing literature provides limited explanation of the conditions under which digitalization effectively translates into scaling outcomes. To address this gap, the study develops a two-dimensional framework integrating digital maturity and scaling orientation, defined as the extent to which firms rely on standardized replication versus local adaptation in structuring their growth. Building on prior research on replicability and scaling (Winter & Szulanski, 2001; DeSantola & Gulati, 2017) and digital transformation (Teece, 2018; Vial, 2019), the framework explains how different configurations lead to distinct scaling dynamics. The empirical analysis is based on a comparative case study of Revolut and BCC Iccrea Group. The findings show that digitalization does not automatically generate scaling. Instead, its impact depends on its alignment with the firm’s scaling orientation. In particular, replication-oriented firms with high digital maturity achieve accelerated scaling, while adaptation-oriented firms experience more gradual, coordination-intensive growth, even when digital capabilities are advanced. This study contributes to the literature by providing a configurational explanation of digital-enabled scaling, demonstrating that scalability emerges from the interaction between technological capabilities and organizational design. It shows that digitalization does not create scaling per se, but amplifies the growth logic already embedded within the firm. Overall, the findings suggest that the key question is not whether digitalization leads to scaling, but under which organizational conditions digital technologies can be effectively leveraged to support scalable growth. Thu, 01 Jan 2026 00:00:00 GMT http://lutpub.lut.fi:80/handle/10024/172427 2026-01-01T00:00:00Z http://lutpub.lut.fi:80/handle/10024/172426 Mechanical design of detector module subsystems for rotating single source CT gantry Granda, Maria This thesis presents the mechanical design and analysis of detector module subsystems for a rotating single-source computed tomography gantry, focusing on detector alignment and heat dissipation. The objective is to develop a feasible concept that integrates medical detector modules, maintains the required imaging geometry, and supports thermal stability. The design is based on fan-beam geometry, mechanical integration requirements, estimated heat loads, material selection, and observations from early prototypes. The detector modules are arranged along a curved arc to meet the required source-to-detector distance, bore clearance, and field-of-view requirements for phantom testing. Defined mounting holes improve positioning repeatability and reduce assembly-related misalignment compared with flexible perforated patterns. The concept also provides electronics support, cable-routing space, airflow paths, and enclosure features for assembly and inspection. A push-pull airflow strategy with additional exhaust ventilation is selected to limit heat accumulation near the electronics. Aluminum 6061-T6 is selected for the main support and enclosure because it balances thermal conductivity, strength, and weight. The proposed subsystem provides a feasible basis for further development of a rotating computed tomography detector assembly. Future work should validate alignment, temperature distribution, airflow, and vibration stability under operating conditions. Thu, 01 Jan 2026 00:00:00 GMT http://lutpub.lut.fi:80/handle/10024/172426 2026-01-01T00:00:00Z http://lutpub.lut.fi:80/handle/10024/172425 Valued, overlooked, and sought after: the subjective well-being of top-performing B2B salespeople Niemi, Jarkko; Metsola, Jaakko; Hautamäki, Pia Top-performing salespeople are invaluable financial assets and role models within sales organizations, yet their well-being remains an unexplored topic in research. This study examines the subjective well-being (SWB) of top-performing business-to-business (B2B) salespeople, focusing on the unique challenges they face – including high performance pressure and what we term the “attention challenge”: the paradoxical experience of being highly valued but also potentially overlooked by management, while simultaneously being frequently sought out by colleagues for advice and support. Drawing on in-depth interviews with 27 top-performing salespeople and a validation webinar with five sales executives, we reveal three interrelated capabilities underpinning top performers’ SWB: work-performance, relational-contribution, and well-being management capability. Our findings extend the sales literature by providing a capability-based framework that integrates eudaimonic well-being perspectives and by introducing the attention challenge as a top performer-specific friction point. The study offers actionable insights for supporting the sustained well-being and performance of top-performing B2B salespeople. Wed, 17 Dec 2025 00:00:00 GMT http://lutpub.lut.fi:80/handle/10024/172425 2025-12-17T00:00:00Z