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Pressurized Water Nuclear Reactor Downcomer Flow Simulation
Aljaž Kekec, 2021, undergraduate thesis

Abstract: In the diploma thesis the flow pattern and conditions in the downcomer of a pressurized water nuclear reactor were simulated, to study coolant mixing inside the primary circuit. This was done using computational dynamics software Ansys CFX. The nuclear reactor in Krško (Slovenia) was used as a basis for the model. The downcomer geometry was simplied for a more feasible study. Three separate simulations were done: one with normal conditions, one with loss of coolant accident conditions and one with a modified geometry. The flow was then studied at different condition at the same levels using velocity contours. The results showed that the axial velocity profiles at the downcomer outlet are not completely uniform.
Keywords: Nuclear Power Plant, Pressurized Water Reactor, Downcomer, Flow simulation, Ansys CFX
Published: 13.10.2021; Views: 99; Downloads: 10
.pdf Full text (2,49 MB)

Monte Carlo simulation of air resistance on an ellipsoid in motion
Veronika Bukina, 2021, master's thesis

Abstract: The main goal of the master's thesis was the analysis of air resistance on the body in motion in a model that does not require solving the Navier-Stokes equations, but works on the basis of mechanics and statistical physics. The model was a Monte Carlo (MC) simulation of the motion of ideal gas molecules in a closed container in which a body was placed, moving along one of the axes. For the most part of calculations, the approach was used when the body was fixed in the middle of the simulation cell, and one of the components of the molecular velocity had an additional term that simulated the flow, as if the body was moving at this speed in the opposite direction. First of all, a linear dependence of the drag force on speed was found for low flow speed for a flat plate, which was predicted by linear drag law. For high molecular flow rates, the quadratic dependence predicted by the Bernoulli equation was clearly observed. The results of calculating the corresponding resistivity coefficients for the flat plate were in agreement with the analytical values for both regimes of speeds. By analogy, a simulation was made for a spherical body, which also demonstrated a strong quadratic dependence at high speeds and the drag coefficient value is approximately equal to the analytical one. In the following, we studied systematically ellipsoids with circular cross-section, where we varied the ratio between semiaxes in the direction of motion and perpendicular direction, respectively. The results for the ellipsoid showed that the drag coefficient value is maximum for a flat plate (a limiting case of an ellipsoid, when the semiaxis in the direction of motion tends to 0) and decreases with stretching of the body along the flow axis. When the Maxwell distribution of molecular speeds that was mainly used was replaced with uniform Root-Mean-Square (RMS) speed the results for drag coefficient were slightly different.
Keywords: Air resistance, drag force, quadratic drag law, drag coefficient, Monte Carlo (MC) simulation, Maxwell distribution.
Published: 13.10.2021; Views: 86; Downloads: 7
.pdf Full text (1,64 MB)

Measurement and modelling of power SiC MOSFET transistors
Darjan Molnar, 2021, master's thesis

Abstract: The increasing demand for smaller, faster, and more efficient switch mode power supplies (SMPS) and energy converters has led to the development of new power MOSFET technologies, such as SiC (silicon carbide) power MOSFET transistors. Switching parameters, output voltages and currents and power consumption need to be measured accurately to assess different types of power electronics components more efficiently in today’s rapid implementation of new energy transfer and modulation technology. The need for improving switching circuits in power electronics and trying to use simple simulation circuits for designing PCBs to measure output values of said power electronics transistors is the basis of this thesis. Even though manufacturers of power electronics transistors provide data on drain-source voltages and currents, these are mostly measured for specific conditions regarding pulse duration, gate-source voltage, case temperature of the transistor etc., and as such do not provide information as to where the limits of the drain source voltages and currents for different measurement parameter values are. The goal of the thesis is to find a way to measure the limits of drain-source voltages and currents of power electronics transistors (in this case a SiC MOSFET transistor), and to see if a simple SPICE-model could be built for other power electronic transistors as well, based on the results of this thesis.
Keywords: SiC, MOSFET, transistor, simulation, PCB
Published: 02.06.2021; Views: 193; Downloads: 27
.pdf Full text (4,35 MB)

Laboratorijski oblagalnik tablet
Matej Štrucl Rojko, 2020, undergraduate thesis

Abstract: V diplomskem delu je predstavljen razvoj naprave za oblaganje tablet. Posebnost te naprave je transparentno zunanje ohišje, ki omogoča spremljanje in nadzor procesov med postopkom oblaganja. V programskem okolju SOLIDWORKS je bil izdelan virtualni 3D model in tehnična dokumentacija. S pomočjo vtičnika Flow Simulation je bila narejena numerična simulacija za optimizacijo toka zraka skozi vhodni nastanek. Na podlagi načrtov je podjetje RAJH PLUS d.o.o. izdelalo delujoč prototip.
Keywords: laboratorijski oblagalnik tablet, konstruiranje, Solidworks Flow Simulation
Published: 24.09.2020; Views: 288; Downloads: 57
.pdf Full text (2,88 MB)

Ergonomsko oblikovanje delovnega mesta na montažni liniji žarometov
Aljaž Majcen, 2020, undergraduate thesis

Abstract: V diplomski nalogi ergonomsko oblikovanje delovnega mesta na montažni liniji žarometov je predstavljena ergonomska analiza delovnega mesta na montažni liniji žarometov. V uvodu je predstavljeno podjetje, znanstvena veda ergonomija, ter njena načela. Opisani sta tudi ergonomski metodi OWAS in RULA, ter programski paket Tecnomatix Jack. Osrednji del diplomske naloge predstavlja predstavitev delovnega mesta, ki je predmet analize, ocena kontrole z vidika ergonomskih načel in opravljene ergonomske analize. Analize so opravljene ročno in računalniško z uporabo paketa Human simulation Jack. V zaključnem delu diplome so predstavljeni rezultati vseh analiz in predlogi izboljšav.
Keywords: ergonomija, Human simulation Jack, OWAS, RULA, ergonomske metode, ergonomska analiza
Published: 22.09.2020; Views: 353; Downloads: 79
.pdf Full text (2,56 MB)

Electrified powertrain configurator
Jernej Kosi, 2019, master's thesis

Abstract: This master’s thesis describes the development, use and simulation results of the Excel based electrified powertrain configurator tool. First, different electrified powertrains are introduced and divided based on the powertrain type. Within the scope of this master’s thesis, we focused on battery electric vehicles. A mathematical vehicle model was developed to describe different battery electric vehicle powertrain architectures. The mathematical vehicle model was implemented in Excel. The performance of the Excel tool was demonstrated by simulating various driving cycles. To evaluate the accuracy and usability of the tool, simulation results from Excel tool were compared with those from AVL Cruise.
Keywords: electrified powertrain, vehicle longitudinal dynamic, driving simulation, Excel, tool development
Published: 23.12.2019; Views: 578; Downloads: 0

Technological valley of death as an emergent evolutionary phenomenon
Petra Fic, 2019, master's thesis

Abstract: Perceptual researchers often argue that natural selection supports veridical perceptions, respectively those that accurately reflect the environment. They also claim that beings whose perceptions are truer are also more fit. This assumption was tested using standard tools of evolutionary game theory in a simple environment. The result was that more veridical perceptions are not necessarily more successful. In the majority of the parameter space, veridical perceptions are extinct in competition with simplified perceptions, based on adaptive behavior in a given environment. In the thesis, we build upon mentioned territorial games introduced by Mark, Marion, and Hoffman in 2010, and extend four of their territory perception and selection strategies with two novel ones that together constitute a model of technological readiness valley of death. Whenever utility of a resource is not monotonous in the amount of that resource, the technological valley of death emerges. While the development of the science behind these models is in its infancy, modeling and understanding the phenomenon may shed light on progress and related phenomena in society.
Keywords: evolution, perception, utility, Monte Carlo simulation, game theory
Published: 22.11.2019; Views: 576; Downloads: 81
.pdf Full text (1,56 MB)

Ergonomska študija in optimizacija delovnega mesta končne kontrole
Matic Breznik, 2018, undergraduate thesis

Abstract: V diplomskem delu je ročno in s pomočjo programske opreme Human simulation Jack ocenjeno delovno mesto končne kontrole v podjetju KLS Ljubno, d. o. o. Bistvo dela sta ergonomska študija in optimizacija delovnega mesta. V uvodnem delu je predstavljeno podjetje, pomen ergonomije in obrazložitev, kako se bom lotil rešitve problema. V osrednjem delu je prikazana celotna analiza delovnega mesta in izsledki, ki so bili pridobljeni ročno ter z uporabo programske opreme. V zaključnem delu pa so predstavljeni optimizacija in predlogi za izboljšanje delovnega mesta, z največjim poudarkom na uvedbi kontrolne linije za končno kontrolo.
Keywords: ergonomija, optimizacija, Human simulation Jack, končna kontrola, OWAS, analiza ledvenega dela hrbtenice
Published: 17.09.2018; Views: 703; Downloads: 114
.pdf Full text (3,51 MB)

Design of geometry and numerical simulation of the operating characteristic of the rotor of the wind turbine
aljaž Janič, 2018, undergraduate thesis

Abstract: The diploma thesis consists of design and numerical simulation of the wind turbine. Geometries are designed according to two theories, the Betz theory and the Schmitz theory. I used Solidworks for 3D modeling of the both rotors. Using Ansys software package, we performed numerical simulations of a rigid body for two different wind speed regimes. We were interested in the angular velocity of the spinning blades, which in combination with moment give us power.
Keywords: Renewable energy, wind energy, numerical simulation, wind turbine, blade design, Betz and Schmitz theory
Published: 09.08.2018; Views: 834; Downloads: 162
.pdf Full text (2,19 MB)

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