Tumbling take-offs on floor exercise apparatuses of varying stiffness properties may contribute to apparatus behaviors that lead to increased injury exposure. The purpose of this pilot study was to compare the kinematics, kinetics, and timing performance characteristics of a springfloor and a spring-floor with an added Air Floor™. Five male international gymnasts performed a forward handspring to forward somersault and a round off, flic flac, backward somersault on a standard spring-floor and a spring-floor with an Air Floor™. Performances were measured via high-speed video kinematics (lower extremity joint angles and positions), electromyography of eight lower extremity muscles, mean peak forces on the feet, and timing. Comparisons of spring-floor types, lower extremity joint angles, lower extremity muscle activations, foot forces, and selected durations were determined. The spring floor with Air Floor™ resulted in longer take-off contact durations than spring-floor alone. Dynamic knee angles may indicate an unexpected and potentially injurious motion of the triceps surae musculotendinous structures. This pilot and hypothesis generating study has suggested future research examining dynamic knee position and angle changes, the role of spring-floor vibration and stiffness in take-offs, and take-off muscle activation alignment with the stiffness of the spring-floor. Pragmatically, there appears to be a convergence of evidence indicating that a slower frequency response of the spring floor may assist tumbling performance and reduce stress and strain in the lower extremity.

Tumbling take-offs on floor exercise apparatuses of varying stiffness properties may contribute to apparatus behaviors that lead to increased injury exposure. The purpose of this pilot study was to compare the kinematics, kinetics, and timing performance characteristics of a springfloor and a spring-floor with an added Air Floor™. Five male international gymnasts performed a forward handspring to forward somersault and a round off, flic flac, backward somersault on a standard spring-floor and a spring-floor with an Air Floor™. Performances were measured via high-speed video kinematics (lower extremity joint angles and positions), electromyography of eight lower extremity muscles, mean peak forces on the feet, and timing. Comparisons of spring-floor types, lower extremity joint angles, lower extremity muscle activations, foot forces, and selected durations were determined. The spring floor with Air Floor™ resulted in longer take-off contact durations than spring-floor alone. Dynamic knee angles may indicate an unexpected and potentially injurious motion of the triceps surae musculotendinous structures. This pilot and hypothesis generating study has suggested future research examining dynamic knee position and angle changes, the role of spring-floor vibration and stiffness in take-offs, and take-off muscle activation alignment with the stiffness of the spring-floor. Pragmatically, there appears to be a convergence of evidence indicating that a slower frequency response of the spring floor may assist tumbling performance and reduce stress and strain in the lower extremity.

This thesis aims to address the incompatibility issues between Scania's 600 mm silencers and the second position 2 o'clock PTO adapted crossmember, by exploring redesign possibilities. The goal is to enable the co-mounting of these components, expanding customization options and enhancing Scania's modularization capabilities. The research investigates various design constraints and parameters associated with the crossmember were gathered in a QFD, and compares the structural rigidity and manufacturing processes of new crossmember concepts to Scania's standard crossmember. The evaluation of concepts is conducted using a Pugh's matrix analysis, which allows for performance assessment and comparison. The investigation reveals that two concepts, namely the Z-beam and trusses-based designs, show the most promise. The Z-beam can be manufactured using either sheet metal or casting methods, while the trusses concept can be realized through laser cutting or CNC machining. Both concepts demonstrate comparable structural rigidity to the current adapted and standard crossmembers. They exhibit good stress distribution, possess potential for further weight reduction, and importantly, are compatible with Scania's modularization system. Additionally, these concepts can effectively accommodate a 2 o'clock PTO and the 600 mm silencers, resolving the incompatibility issue. / Denna avhandling syftar till att adressera inkompabiliteten mellan Scanias 600 mm ljuddämpare och den nuvarande klockan 2 PTO-anpassade tvärbalken i den andra tvärbalkspositionen. Genom att utforska möjligheter till omkonstruktion strävar avhandlingen efter att möjliggöra sammontering av dessa komponenter, vilket utvidgar anpassningsalternativen och förbättrar Scanias modulära system. Forskningen undersöker olika begränsningar och parametrar för tvärbalken som fastställs i en QFD, samt jämför den strukturella styvheten och tillverkningsprocesserna för nya tvärbalkskoncept med Scanias standardtvärbalk. Utvärderingen av koncepten genomförs med hjälp av en Pugh-matrisanalys, vilket möjliggör bedömning och jämförelse av prestanda. Undersökningen visar att två koncept, nämligen Z-balken och fackverk-baserade designen, visar mest lovande resultat. Z-balken kan tillverkas antingen i plåt eller gjutas, medan fackverks-konceptet kan förverkligas genom laserskuren plåt eller CNC-bearbetning. Båda koncepten uppvisar jämförbar strukturell styvhet med den nuvarande anpassade och standardtvärbalken. De visar även en god fördelning av belastningar, har potential för ytterligare viktreducering och är kompatibla med Scanias modulsystem. Dessutom är dessa koncept kompatibla med en klockan 2 PTO i andra tvärbalkspositionen och Scanias 600 mm ljuddämpare, vilket löser imkompabilitetsproblemet.

Uppdragsbeskrivningen till detta examensarbete kom från Sweparts verksamhet i Liatorp. Målet med examensarbetet var att utreda hur tillverkningsprocessen av Sweparts kraftuttag kan effektiviseras i avseende: kapacitet, mätt i antal produkter samt investeringskostnader och operatörslöner, genom att använda simuleringsprogrammet ExtendSim. En kartläggning av dagens den nuvarande monteringslinan gjordes för att få en få en klar bild av monteringsprocessen, processtider och antal operatörer, för att sedan kunna simulera en realistisk version av den nuvarande monteringslinan. En litteraturstudie av simulering, diskret händelsestyrd simulering, ExtendSim samt val av sannlikhetsfördelning gjordes för att fördjupa kunskapen inom ämnet simulering. När den nuvarande monteringslinan simulerats och verifierats, simulerades de valda nio scenarierna. De fem första scenarierna experimenterades det med olika antal operatörer, uppdelning av stationer och antal testmaskiner. De resterande tre var sammanslagna PTO- linor med olika antal operatörer och testmaskiner. Dessa analyserades med ett antal indikatorer: antal produkter efter åtta timmar, genomsnittlig kö och väntetid framför testmaskin samt utnyttjandegrad av operatörer. Resultatet av simuleringarna visade att de scenario 3 gav flest produkter efter åtta timmar med två testmaskiner och fyra operatörer. Följt av scenario 2, med tre testmaskiner och fem operatörer. Resultatet i avseende investeringskostnader och operatörslöner efter 15 år var bäst för scenario 8, med sammanslagen PTO- lina med två testmaskiner och tre operatörer. Scenario 4 var näst bäst med två testmaskiner och tre operatörer. / The objective for this thesis came from Swepart's operations in Liatorp. The aim of the thesis was to investigate how the manufacturing process of Swepart's power take-off can be improved in terms of: capacity, measurement in number of products and investment costs and operator salaries, by using the simulation program ExtendSim. A survey of today's current assembly line was made to get a clear picture of the assembly process, process times and number of operators, in order to then simulate a realistic version of the current assembly line. A literature study of simulation, discrete event-controlled simulation, ExtendSim and choice of truth distribution were made to deepen the knowledge in the subject of simulation. When the current assembly line was simulated and verified, the selected nine scenarios were simulated. The first five scenarios were experimented with different numbers of operators, division of stations and number of test machines. The remaining three were merged PTO lines with different numbers of operators and test machines. These were analyzed with a number of indicators: number of products after eight hours, average queue and waiting time in front of the test machine and the utilization rate ofoperators. The result of the simulations showed that the third scenario gave the most products after eight hours with two test machines and four operators. Followed by the second scenario, with three test machines and five operators. The result in terms of investment costs and operator salaries after 15 years was best for the eight scenario, with combined PTO line with two test machines and three operators. The fourth scenario was came in second, with two test machines and three operators.

A combined wing and propeller model is presented as a low-cost approach to preliminary modeling of slipstream effects on a finite wing. The wing aerodynamic model employs a numerical lifting-line method utilizing the 3D vortex lifting law along with known 2D airfoil data to predict the lift distribution across a wing for a prescribed upstream flowfield. The propeller/slipstream model uses blade element theory combined with momentum conservation equations. This model is expected to be of significant importance in the design of tail-sitter vertical take-off and landing (VTOL) aircraft, where the propeller slipstream is the primary source of air flow past the wings in some flight conditions. The algorithm is presented, and results compared with published experimental data.

Wave energy has great potential in energy harvesting, but due to its high system cost per electricity production, it is still in the pre-commercialization stage for grid connection. A wave energy converter (WEC) system that harvests energy through wave motion consists of a wave energy converter and a power take-off (PTO). A wave energy converter, usually a floating buoy, absorbs the hydrodynamic motion from wave and generates a mechanical oscillation. A power take-off (PTO) with mechanical transmission, which harvests the electrical energy through the mechanical energy, usually includes a transmission that converts linear motions from the buoy to rotational motions, an electromagnetic generator that produces electricity from a rotational shaft, and a power electronics converter that converts the ac electric power from the generator and charges the output dc battery or the ac grid. The models of the WEC system are usually oversimplified in a multi-physics study. A PTO model as an ideal actuator with 100 % efficiency will show a different frequency response than the real tested results and can make the controller design invalid. A conventional regular-wave circuit model shows discrepancies in power and force prediction in time-domain under irregular wave conditions. A model that can bring the multiple fields together, and provides an accurate prediction from irregular wave dynamics and non-ideal PTO mechanism is needed. A methodology that converts mechanical transmission equations into a circuit model is created. The equivalent circuits of mechanical components such as one-way clutches, gears, a ball screw, mechanical couplings, and generator are derived respectively to describe the dry frictions, viscous damping, and mechanical compliances in these components. The non-ideal efficiency and force of the PTO are predicted in electrical simulations by integrating these sub-circuit models. The circuit model is simplified, and its parameters are categorized as dc and ac unknowns. Using PTO with a mechanical-motion-rectifier (MMR) gearbox as an example, the dc and ac tests on the PTO are performed sequentially to extract two sets of parameters through linear regression or nonlinear curve fitting. The simulated efficiencies of 30 – 80% match well with experimental results. The model is validated through its prediction capability over 25 test conditions on input forces, output voltages, and efficiencies, with correlation coefficients R2 value of 0.9, 0.98, and 0.981, respectively. An equivalent circuit model of fluid-body dynamics for irregular waves, applicable to real ocean conditions with frequency-dependent radiation damping, is developed. Different from PTO modeling, the time-invariant circuit is created from a fourth-order RLC equivalent circuit through transfer function approximation in the frequency domain and Brune network. The circuit-based wave energy converter (WEC) model is verified by comparing the results with the predictions of a detailed model under irregular wave conditions in the time and frequency domains based on a point absorber type of WEC with a power take-off (PTO). The results show that the developed model gives an accurate dynamic prediction for a WEC under both regular and irregular conditions. Along with the PTO model, the circuit-based W2W model is completed for control and design optimization of the WEC system. Wave energy converter systems have faced various challenges such as reciprocal wave motion, high peak-to-average power ratio, and potential wave height from hundred-year storm conditions. These could lead to an overdesigned power take-off (PTO) of the system and significantly reduce the lifetime of the power electronics converter. The power ratio between the peak and the average power of the wave power converter is around 10 – 20 times. Power optimization is necessary to reduce the over design ratio of the power electronics converter. The design guideline that optimizes the power ratings for the power converter and the generator is introduced. The methodology is developed from the W2W circuit model taking the losses of the power converter and the generator into consideration. By optimizing the power limiting and field-weakening controls, the ratio from the average output power to the rated power of the power converter is reduced to 2.4 in the maximum wave condition, and 15 in the annual wave profile. A maximum energy control algorithm on the power electronics in wave energy application is developed to increase the total energy produced from the power converter in a wave energy converter (WEC) system. A 4-D damping and power leveling maps for maximum energy are built for the algorithm. The maps are based on the irregular W2W circuit model and reliability analysis on the IGBT module. From the yearly wave mission profile, the strategy is proved to increase energy by 16 times or increase the lifetime from 3 to 18 years in exchange for 6 % of average output power than the conventional maximum power algorithm. In conclusion, this work provides a new circuit-based perspective for co-designing the multi-disciplinary WEC system. The methodologies of circuit modeling can benefit the co-design process of other mechatronic power systems, such as electric vehicle or renewable energy system. The newly invented mechanical device – the mechanical motion rectifier, is understood thouroughly via the non-ideal electrical model. The commercialization of wave energy converter is driven forward through the reduction of the levelized cost of electricity (LCoE) which is made possible by increasing the energy production and optimizing the cost per output power of the generation and power conditioning stages. / Doctor of Philosophy / Wave energy, if all been harvested along the U.S. coastline, can power around 65% of the energy consumption in U.S.. Comparing to other renewable energy sources like solar or wind, ocean wave can provide up to 90% of steady uptime. With the high energy density (2-3 kW/m2), it can produce more energy with the same amount of installation area comparing to the energy density of wind turbine (0.6 kW/m2) and solar panel(0.2 kW/m2). The predictability of wave provides advantages like planning installation, power dispatching, and maintenance activities. Although with all these advantages, wave energy converter system is still in the research stage due to its high system cost per electricity production. One of the challenges that need to be solved is the irregularity from the wave motion that leads to high instantaneous peak power into the wave energy converter, which usually reaches up to 10 - 20 times of the average power. The high peak power will not only bring high mechanical/electrical stress but also result in an overrating design of the components in the system. Another obstacle that prevents the wave energy system from moving forward is the high testing cost from the validations in wave-energy-test sites or tank-test sites. A high-fidelity multi-disciplinary system model, including hydrodynamics, mechanical dynamics, electromagnetics, and power electronics, is needed to predict the behavior of the system and reduce the cost of design validation. This work provides a unified circuit-based perspective for co-designing the multi-disciplinary wave energy system. The efficiencies and mechanical dynamics of the system are accurately predicted via the non-ideal electrical model. These methodologies of circuit modeling can also benefit the co-design process of other mechatronic power systems, such as electric vehicles or renewable energy systems. The peak of the irregular power is controlled by the power-leveling and field-weakening control, and as a result, the overdesign ratio of the power converter reduces from 11.1 to 2.4. Through proper design of the converter's control algorithm, the total produce electric energy is increased by 15 times, as well as the lifetime of the power electronics extended from 3 years to 18 years. Therefore, the commercialization of wave energy converter is driven forward through the reduction of the levelized cost of electricity (LCoE), which is made possible by optimizing the component lifetime and the output energy utilizing the developed circuit-based wave-to-wire model.

Point absorber style marine energy harvesters have been investigated based on their structure, energy harvesting efficiency, and reliability along with costs. However, due to the continuously varying ocean conditions and climates, the system usually suffers low power output and reliability from low input and high Peak to Average Ratio (PAR). Therefore, a Mechanical Motion Rectifier (MMR) based point absorber is introduced in this thesis to promote the harvesting efficiency and reduce the PAR by unifying the input rotation, and allow disengagement inside the gearbox during low power output phase. A 1:20 scale full system was then designed, prototyped, and tested based on the MMR. The bench test results show that the proposed MMR based point absorber could improve the energy conversion efficiency by 10 percent, which brings feasibility to the implementation. Traditional Wave Energy Converter(WEC) can only harvest ocean waves while ocean current is also one of the significant energy sources widely existing in ocean. In order to further increase the energy harvesting efficiency, one individual energy input source shows its limits. A vast majority of places around the world tends to co-exist both marine waves and current, and extracting energy from both sources could potentially increase the electric power output. Therefore, the Hybrid Wave and Current Energy Harvester (HWCEC) is introduced along with the hybrid gearbox. It is capable of harvesting energy from both ocean waves and current simultaneously so that the electric power output is significantly higher from a combined system. Tank test data shows 38-79 percent of electric power output promotion of an HWCEC compared to a regular WEC, and 70 percent reduced PAR in irregular wave condition. After that, system electric damping has been thoroughly investigated on both electrical side and mechanical side. The best power output corresponding electrical resistance is identical to the generator internal resistance while the best gear ratio of 3.5 is determined via both simulation and tank test. Furthermore, the system's PAR has been investigated by analyzing the trend of the peak occurrence. Tank test data shows the HWCEC's output power peak occurrence is at roughly 20 percent located at its PAR average. Therefore, the HWCEC system can promote energy harvesting efficiency to the combined system design, and improve its reliability from a significantly reduced peak to average ratio. It also gives HWCEC a large variety of deployable locations compared to a regular WEC under more marine environment. Furthermore, a new design of the Hybrid model, Hybrid LITE, is then developed, which not only features the HWCEC features, but also a lightweight, immersive and inflatable design for fast deployment and transportation. Since the system is built with an open water chassis, the overall system robustness is significantly improved since no water sealing is required on the powertrain compared to the HWCEC. / Master of Science / Ocean contains enormous amount of Marine Hydrokinetic (MHK) energy including ocean waves, tidal streams, and ocean current. Marine energy was investigated due to its continuous, massive and high-density hydrokinetic power output. In order to better serve the needs for ocean surface applications and take advantage of high energy density compared to other renewable energy sources, Wave Energy Converters (WEC) has been investigated, which harvests energy from the ocean wave. In the past years of study, it came to our attention that places such as the west coast of the U.S., northern Europe, and the Mediterranean area tend to have both abundant marine wave and current energy. Therefore, a new design of the Hybrid Wave and Current Energy Converter (HWCEC) is investigated for higher power output. In order to combine the energy sources from waves and current, a Hybrid Gearbox was selected to joint the power and unifies the motion from the wave for a higher efficiency. Simulations and 1:10 ratio co-existing wave and current basin test have been conducted for the HWCEC. By using the same system, single wave or current input are used as the baselines and the dual input HWCEC has demonstrated great benefit and potential. The electric damping and the gearbox ratio of the HWCEC are studied for the best power output in both simulation and tank test. The result shows that the HWCEC could promote up to 38-71 percent of electricity output in a regular wave condition, and 79 percent in irregular wave condition. The Peak to Average Ratio (PAR) is a key factor for system's mechanical reliability. The testing shows that the HWCEC can reduce 70 percent of the peak motion and contribute to the average, which is an indirect indicator of the system's better reliability. Furthermore, to align the needs of the design for real-life applications, The Hybrid LITE Converter idea was then developed for special deployment requirements for the future application of the Hybrid system. It has a novel open-system design with the implementation of a newly designed hybrid gearbox. This converter has the potential of promoting the reliability, deployability and weight reduction for easy transportation from its open system design compared to HWCEC. The system modeling could be done as future work varies from the changing deployment locations for higher electric power output.

The electrification of the truck is crucial to meet the strategic vision of the European Union (EU) to contribute to net-zero greenhouse gas emissions for all sectors of the economy and society. The battery-electric truck is very efficient to reduce the emissions and has also a lower Total Cost of Ownership (TCO) compared to diesel trucks. Thus, the energy consumption of the battery-electric truck needs to be analysed in detail, and the differences in the conventional powertrain, recuperation by regenerative braking during driving and charging during standing, need to be considered. This master thesis aims to analyse the energy consumption of the battery-electric truck during driving and standing charging. For driving cycle simulation the Vehicle Energy Consumption calculation TOol (VECTO) and MATLAB are used. Different variations, such as payload, rolling resistance, air drag, and Power Take Off (PTO), are considered in the driving cycle simulation. The driving cycle simulation is verified by calculating the energy balance and compared with the on-road test results. For the standing charging simulation, MATLAB is used to analyse the charging loss with different battery packs and charging speeds. The results are shown with the Sankey diagram and other illustrative tools. Seen from the simulation results, the usable energy of the battery pack is enough for the truck to complete the designed driving cycle. The main loss in the powertrain is the Power Electronic Converter (PEC) and the electric machine. To increase the range and reduce energy loss, using a higher efficiency PEC and electric machine is an efficient method. For the charging simulation, the current Combined Charging System (CCS) standard charging station can charge the battery-electric truck with adequate voltage and reasonable charging time. The main loss during the charging comes from the charging station. / Elektrificering av lastbilen är avgörande för att uppfylla Europeiska Unionens (EUs) strategiska vision att bidra till nettonollutsläpp av växthusgaser för alla sektorer i samhället. Den batterielektriska lastbilen är väldigt effektiv för att reducera utsläppen och är också mer ekonomisk med en lägre Total Cost of Ownership (TCO) jämfört med diesel lastbilar. Således behöver energiförbrukningen för den batterielektriska lastbilen analyseras i detalj, och skillnaderna i den konventionella drivlinan, återhämtning genom regenerativ bromsning under körning och laddning, måste övervägas. Detta examensarbete syftar till att analysera energiförbrukningen för den batterielektriska lastbilen under körning och laddning. För körcykelsimuleringar används the Vehicle Energy Consumption calculation TOol (VECTO) och MATLAB. Olika variationer, såsom nyttolast, rullmotstånd, luftmotstånd och Power Take Off (PTO), beaktas i körcykelsimuleringen. Körcykelsimuleringen verifieras genom att beräkna energibalansen som jämförs med experimentella testresultat utförda på väg. För laddningssimuleringen används MATLAB för att analysera laddningsförlusten med olika batteripaket och laddningshastigheter. Resultaten visas med Sankey diagram och andra illustrativa verktyg. Simuleringsresultaten visar att batteripaketets användbara energi är tillräckligt för att lastbilen ska kunna slutföra den planerade körcykeln. Den största förlusten i drivlinan är kopplat till the Power Electronic Converter (PEC) och den elektriska maskinen. För att öka räckvidden och minska energiförlusten är det ett effektivt sätt att en använda PEC och en elektrisk maskin med högre effektivitet. För laddningssimuleringen kan den nuvarande stationen med Combined Charging System (CCS) standard ladda batteriladdaren med tillräcklig spänning och med rimlig laddningstid. Huvudförlusten under laddningen kommer från laddstationen.

Adoption of a streamlined BIM workflow throughout the AEC projects’ lifecycle will provide the project stakeholders with the rich information embedded in the parametric design models. Users can incorporate this rich information in various activities, improving efficiency and productivity of project activities and potentially enhancing accuracy and reducing errors and reworks. Two main challenges for such a streamlined information flow throughout the AEC projects that haven’t been sufficiently addressed by previous research efforts include lack of semantic interoperability and a large gap and misalignment of information between available BIM information provided by design activities and the required information for performing preconstruction and construction activities. This research effort proposes a framework for a knowledge-based system (KBS) that encapsulates domain experts’ knowledge and represents it through modularized rule set libraries as well as connected design automation and optimization solutions. The research attempts to provide a methodology for automatic semantic enrichment of design models as well as automated detailed design to fill the information gap between design and preconstruction project activities, streamlining BIM workflow and enhancing its value in the AEC projects.

Building Information Modeling (BIM) plays an important role in today's construction industry. Models are tools that help stakeholders communicate, visualize building geometry, perform trade coordination and clash detection among others. A less popular aspect of BIM that shows high potential is the quantity take-off (QTO) feature. Yet, its implementation among commercial general contractors (GC) has not received as much attention. The purpose of this study was to identify how the BIM QTO features were being implemented among commercial general contractors, what challenges they faced and how they worked to overcome those challenges. Through a three-step process including semi structured interviews with estimators, preconstruction, BIM and Virtual Design Construction (VDC) managers, valuable insights on the BIM QTO implementation state among general contractors were gathered and analyzed. Links between BIM QTO benefits, project design phases and delivery methods, software, training, leadership and jurisdictions were discussed. The data indicated that BIM QTO's benefits were best leveraged through early general contractor involvement, the adequate contract framework, trained BIM QTO estimators, and early and strategic communication between owners, designers and estimators. The conditions for increased efficiency were discussed along with the solutions to the common BIM-based QTO challenges.