This presenting master’s thesis deals with a problem of digitaly controled room temperature using the software PLC. The result of this work was creating of an algorithm to control temperature on the requested leve ofl setpoint, minimizing operating costs of the building. The PLC softwares from different manufacturers were analyzed and compared with conventional PLC. The testing facility was disigned and used to control the temperature in the room and data visualization. Room temperature was regulated by PS controller or two point regulator.

This final thesis deals with adaptive control of small brewery. Contains a short description of brewing technology and adaptive control. Includes design of small brawery and control system based on STM32F407 Cortex-M4 microcontroller. For online identification is used Recursive Least Squares Method. The controller function perform a modified PSD controller with filtered derivative component, reducing the first overshot and dynamic antiwindup. The proposed adaptive controller is implemented into microcontroller. Created device i used for semi-automatic beer production.

Simulations are a powerful tool used to reduce development time and cost in the vehicle industry. However, the models used in simulations are simplifications of reality, and there are commonly contradicting requirements between accuracy and computational efficiency. Vehicles are constructed with a large number of parts joined together with bolts, welds and other joints. At these locations and other places where different surfaces come in contact, the contact can have a considerable effect on the dynamic behaviour of the part and capturing this effect in simulations can be difficult because of their nonlinear nature.  This thesis aims to evaluate different methods for simulating contacts and their effects under dynamic conditions. The thesis is performed at Scania, one of the top commercial vehicle manufacturer, which aims to increase the use of simulations in the design of their vehicles to have better designs with lower cost and time investments.  This thesis uses the multibody simulation software Adams Car to evaluate two different contact simulation methods, one developed by Adams and the other is the softwareMamba developed by Magna. Mamba defines special modes called Joint-interface modes, which capture the deformation in the vicinity of the contact. The contact simulations are compared with some of the existing simulation methods and physical test data by implementing it on cases where contact plays an important role in dynamic behaviour. Two such cases are identified as the leaf spring and the frame-subframe assembly. For the leaf spring example, the stiffness and energy dissipation were compared for Mamba simulations with the Adams built-in multi-beam model and physical test data. The stiffness with the Mamba contact model better matched the test data, but the energy dissipation was better modelled with the Adams leaf spring model. For the frame-subframe assembly, the effect of the Mamba contact modes was evaluated for random vibration tests by comparing acceleration Power Spectral Density (PSD), relative displacement and Operating Deflection Shape (ODS) analysis. The Adams contact model was also implemented for this case but could not converge to a solution. Improvement in accuracy was observed with Mamba contact simulations compared to simulations which ignored contact, but with the drawback of significantly higher simulation times. / Simuleringar är ett kraftfullt verktyg som används för att minska utvecklingstiden och kostnaderna i fordonsindustrin. De modeller som används i simuleringar är dock förenklingar av verkligheten, och det finns vanligtvis motstridiga krav mellan noggrannhet och beräkningseffektivitet. Fordon är konstruerade med ett stort antal delar sammanfogade med bultar, svetsar och andra skarvar. På dessa platser och andra platser där olika ytor kommer i kontakt kan kontakten ha en avsevärd effekt på delens dynamiska beteende och att fånga denna effekt i simuleringar kan vara svårt på grund av deras olinjära karaktär. Detta examensarbete syftar till att utvärdera olika metoder för att simulera kontakter och deras effekter under dynamiska förhållanden. Examensarbetet har utförts hos Scania, en av de främsta tillverkarna av kommersiella fordon, som har som mål att öka användningen av simuleringar i utformningen av sina fordon för att få bättre konstruktioner med lägre kostnads och tidsinvesteringar. Detta examensarbete använder multikroppssimuleringsprogramvaran Adams Car för att utvärdera två olika kontaktsimuleringsmetoder, en utvecklad av Adams och denna andra är Mamba som är utvecklad av Magna. Mamba definierar ‘Joint interface modes’, som fångar upp deformationen i närheten av kontakten. Kontaktsimuleringen med Mamba jämförs med några av de befintliga simuleringsmetoderna samt fysiska testdata genom att implementera den i fall där kontakt spelar en viktig roll i det dynamiska beteendet. Två sådana fall identifieras som bladfjädern och ram-subramenheten. För blad-fjäder exemplet jämfördes styvhet och energiförlust för Mamba simuleringar med Adams inbyggda multi-balksmodell och fysiska testdata. Styvheten med Mamba-kontaktmodellen stämde bättre överens med testdata, men energiförlusten modellerades bättre med Adams bladfjädermodell. För ram-subramenheten utvärderades effekten av kontaktmoderna i Mamba för slumpmässiga vibrationstest genom att jämföra spektraltätheten för accelerationerna Power Spectral Density (PSD), relativ förskjutning och Operating Deflection Shape (ODS) analys. Adams kontaktmodell implementerades också för detta fall men kunde inte konvergera till en lösning. Förbättring i noggrannhet observerades med Mamba kontaktsimuleringar jämfört med simuleringar som ignorerade kontakt, men med nackdelen med betydligt längre simuleringstider.

In this thesis a train-track-bridge interaction (TTBI) model is developed in order to study the dynamic amplification from track irregularities on railway bridges traversed by freight trains. These simulations are of great importance since rail freight transport is expected to increase in order to meet the climate goals. The shift of the freight industry is however not accomplished without complications, because of the heavier and more frequent transportation higher demand is put on the infrastructure supporting the railways. In order to adequately assess the bearing capacity of the railway bridges, more detailed models assessing the dynamic behavior of the bridges are needed. The research underlying the current model in Eurocode were made during the 1970s (ORE, 1976) and the 1990s (ERRI, 1999) which were based on very simplified relations of the interaction and irregularities. Two research questions are therefore established in this thesis. The first one is if the current dynamic amplification factor in Eurocode which accounts for track irregularities is over conservative and secondly if the same factor is suitable to utilize for both section forces and deflections. The model developed in order to answer the stated research questions is a 2D model (considering only vertical excitation) with a linearized Hertz contact spring coupling the vehicle subsystem to the track-bridge system. The bridges examined in the thesis are limited to simply supported bridges with a span length between 4-20 m carrying a ballasted track. The studied train speeds vary between 60 - 120 km/h in order to replicate the speed range utilized by freight trains. The quality of the track (irregularities) is varied between a standard variation of 0.5-5 mm and is generated based on the German power spectral density (PSD) function. Research have previously been carried out in the field of TTBI system but have mostly been focusing on high-speed railway engineering and few studies have been performed on heavy transportation. One of the pioneers in the field of TTBI modelling is Wanming Zhai and the model developed in this thesis is validated against one of his 2D models. Based on the simulations performed in this thesis it is evident that the current model in Eurocode EN 1991-2 is over conservative and in great need of a revision. The model presented in this thesis is for the case with the largest dynamic amplification (120 km/h and a 4 m span length) significantly lower than the model presented in Eurocode. From the sensitivity analysis it is possible to conclude that many of the parameters in the system have low influence on the dynamic amplification while others have considerable influence. The parameters that have a considerable influence might be more suitable with a probabilistic approach instead of a deterministic which was utilized in this thesis. / I denna avhandling upprättas en tåg-spår-bro interaktionsmodell i syfte att studera den dynamiska förstorningsfaktorn som uppkommer av ojämnheter från spåret för järnvägsbroar trafikerade av godståg. Dessa typer av simuleringar är viktiga då järnvägstransporter förväntas öka för att klara av att möta de klimatmål som fastställts. Denna ökning av järnvägstransporter genomförs dock inte utan problem. Ökningen medför fler och tyngre transporter vilket skapar problem för järnvägsinfrastrukturen (främst broarna). För att med säkerhet kunna fastställa bärförmågan hos broarna, behövs mer avancerade modeller än de som idag finns i Eurokod. Modellerna som finns angivna i Eurokod bygger på forskning genomförd under 70- (ORE, 1976) och 90-talet (ERRI, 1999), där det användes väldigt förenklade interaktions- och ojämnhets-modeller. På grund av detta har två frågeställningar upprättats. Den första är om den dynamiska förstoringsfaktorn som används i Eurokod för att ta hänsyn till ojämnheterna i spåret är överdrivet konservativ och den andra är om samma faktor är lämplig att använda för både snittkrafter och nedböjning. Modellen som upprättats för att besvara dessa forskningsfrågor är en 2D modell (vertikalt led) med en linjäriserad Hertz kontaktfjäder för att koppla samman fordonet med spår-bro systemet. Broarna som har studerats i denna avhandling är endast fritt upplagda broar med en spannlängd mellan 4-20 m med ballasterat spår. Tåg-hastigheten har varierats mellan 60-120 km/h i syfte att simulera relevanta hastigheter för godståg. Spårkvalitén (ojämnheterna) har beskrivits m.h.a. standardavvikelsen från det perfekta spårläget och har varierats mellan 0.5-5 mm. Dessa ojämnheter har genererats baserat på den tyska power spectral density (PSD) funktionen. Tidigare forskning har utförts inom ämnet tåg-spår-bro interaktion men med huvudsaklig fokus på höghastighetståg/resonans-beteenden och få studier har genomförts på godståg. En av föregångsmännen inom ämnet är Wanming Zhai, och modellen som upprättas i denna avhandling har därav validerats mot hans 2D modell. Baserat på simuleringarna i denna avhandling är det tydligt att den nuvarande modellen som används i Eurokod EN 1991-2 är överdrivet konservativ och i stort behov av en uppdatering. Det fall med stört dynamisk förstoringsfaktor (120 km/h och en spannlängd på 4 m) som behandlas i denna rapport är avsevärt lägre än det som återfinns i Eurokod. Från känslighetsanalysen som genomfördes kunde det fastställas att många av parametrarna i systemet har en låg inverkan på förstoringsfaktorn. För parametrarna som dock hade inflytande skulle ett probabilistiskt angreppssätt kunna vara mer passande än det deterministiska som använts i denna avhandling.

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Future mobile communications systems reaching for ever increasing data rates require higher bandwidths than those typical used in today’s cellular systems. By going to higher bandwidth the (for low bandwidth) flat fading radio channel becomes frequency selective and time dispersive. Due to its inherent robustness against time dispersion Orthogonal Frequency Division Multiplex (OFDM) is an attractive candidate for such future mobile communication systems. OFDM partitions the available bandwidth into many subchannels with much lower bandwidth. Such a narrowband subchannel experiences now due to its low bandwidth an almost flat fading leading in addition to above mentioned robustness also to simple implementations. However, one potential drawback with OFDM modulation is the high Peak to Average Ratio (PAR) of the transmitted signal: The signal transmitted by the OFDM system is the superposition of all signals transmitted in the narrowband subchannels. The transmit signal has then due to the central limit theorem a Gaussian distribution leading to high peak values compared to the average power. A system design not taking this into account will have a high clip rate: Each signal sample that is beyond the saturation limit of the power amplifier suffers either clipping to this limit value or other non-linear distortion, both creating additional bit errors in the receiver. One possibility to avoid clipping is to design the system for very high signal peaks. However, this approach leads to very high power consumption (since the power amplifier must have high supply rails) and also complex power amplifiers. The preferred solution is therefore to apply digital signal processing that reduces such high peak values in the transmitted signal thus avoiding clipping. These methods are commonly referred to as PAR reduction. PAR reduction methods can be categorized into transparent methods – here the receiver is not aware of the reduction scheme applied by the transmitter – and non-transparent methods where the receiver needs to know the PAR algorithm applied by the transmitter. This master thesis would focus on transparent PAR reduction algorithms. The performance of PAR reduction method will be analysed both with and without the PSD constrained. The effect of error power on data tones due to clipping will be investigated in this report.

The study aims to determine the relationship between the talent mindset (TM) and organisational commitment (OC) of academic heads of departments. There is a vast problem in the higher education sector with regards to retaining academic staff members. In order for higher education institutions to attract and more specifically retain academic talent, one needs to implement a sound talent management model. Before such a model can be implemented with success, the organisation first needs to have a positive talent mindset. The relationship between talent mindset and organisational commitment may provide a means to develop appropriate interventions or strategies in order to enhance the talent mindset by focusing on improving the organisational commitment and vice versa. Two instruments, namely the Talent Mindset Index (TMI) and Organisational Commitment Questionnaire (OCQ), were administered to a sample of 116 heads of departments at a leading university in South Africa, 53 completed questionnaires were obtained. The responses were analysed using correlation analysis and quantitative techniques. Results confirm that the presence of OC is associated with a positive TM. Therefore, the study provides evidence that there is a correlation between OC and the TM of academic heads of departments. Thus, if management utilises existing techniques to increase OC, this should lead to the enhancement of the heads of departments’ TM. The enhanced TM would equip them to implement a talent management model to attract and retain academic staff. / Dissertation MCom University of Pretoria, 2014 / Human Resource Management / unrestricted

Road damage identification is still largely based on visual inspection methods and profilometer data. Visual inspection methods heavily rely on expert knowledge which is often very subjective. They also result in traffic flow interference due to the need for redirection of traffic to alternative routes during inspection. In addition to this, accurate high-speed profilometers, such as scanning vehicles, are extremely expensive often requiring strong economic justifications for their acquisition. The low-cost profilometers are very slow, typically operating at or less than walking speeds, causing their use to be labour-intensive if applied to large networks.This study aims at developing a road damage identification methodology for both paved and unpaved roads based on modelling the road-vehicle interaction system with an artificial neural network. The artificial neural network is created and trained with vehicle acceleration data as inputs and road profiles as targets. Then the trained neural network is consequently used for reconstruction of road profiles upon simulating it with vertical vehicle accelerations. The simulation process is very fast and can often be completed in a very short time thus making it possible to implement the methodology in real-time. Three case studies were used to demonstrate the feasibility of the methodology and the results on field tests carried out on mine vehicles with crudely measured road profiles showed a majority of the tested roads were reconstructed to within a fitting accuracy of less than 40% at a correlation level of greater than 55% which in this study was found to be practically acceptable considering the limitations imposed by the sizes of the haul trucks and their tyres as well as the quality of the road profiles and lack of control in the vehicle operation. / Thesis (PhD)--University of Pretoria, 2015. / Mechanical and Aeronautical Engineering / Unrestricted

The objective of the thesis is to create software, which implements industrial PID controller enabling smooth switch-over and automatic tuning of parameters. The next objective is to create visualization for this controller. Whole controller have to be implemented into PLC Power Panel (B&R company). At the beginning of the thesis there is theoretical description of all implemented algorithms (discrete control algorithms derived from PID, smooth switch-over, antiwindup, identification algorithms). In the following there is designed program structure, which is state machine-shaped. All algorithms are implemented in ANSI C at first as s-function for Matlab/Simulink program, which enables to simulate and verify the controller. Implementation of controller into PLC Power Panel through the use of Automation Studio program from B&R company is described in the next part. Visualization is created in the same program. Simulations and verifications on mathematical and physical model demonstrates functionality of implemented algorithms, but also points out some problems associated with the use of identification algorithms in real world (noise, quantization in A/D and D/A converter).

Beetle-killed trees and woody residues degenerate and may lead to wildfires and uncontrolled CO2 emission. Woody biomass is known as a neutral CO2 solid fuel since it generates the same amount of CO2 that takes from atmosphere during its growing up. Cofiring woody biomass with coal in existing coal power plants is a reasonable solution to reduce the net amount of CO2 emission and decrease the risk of wildfires. However, there are some challenges ranging from providing and handling the woody biomass to the operation of cofiring woody biomass with coal. Co-milling of the fuels and ash deposition on the heat exchanger surfaces during cofiring are among the most critical challenges. A CFD model simulated the behavior of the pulverized particles and evaluate the impact of geometry and operational changes on mill performance. In addition, we measured the ash deposit rate derived from cofiring woody biomass with coal in a pilot combustor (1500 kW) and full-scale furnace. Moreover, we developed a model to predict ash deposit rate during combustion of coal and its blend with a variety of biomass. The post-processing analysis of CFD modelling of co-milling woody biomass with coal shows that the entrained large woody biomass particles exit the pulverizer along with the fine coal particles due to their lower density than that of coal particles. Some simple geometry and operational changes can optimize mill performance by reducing the number of large biomass particles in the product stream. Therefore, it makes the particle size distribution (PSD) of the product stream of co-milling more like that of coal. The collected data set of fly ash particles and ash deposit samples shows that the ash formation and deposit rates were not impacted significantly by cofiring woody biomass with coal. The concentration of alkali metals in the ash aerosol during cofiring was slightly higher than that of coal. Cofiring in pilot scale combustor made a tri-modal PSD of ash aerosol particles; however, the distribution was bimodal in the full-scale boiler. The ash deposit rates during cofiring in 1500 kW combustor were higher (30 to 70%) at locations closer to the burner at short operation times. Our developed model of ash deposit rate investigated two types of stickiness models of fly ash particles to the surface of heat exchanger: melt fraction stickiness model (MFSM) and kinetic energy stickiness model (KESM). The developed model suggested that the MFSM, which is based on the melt fraction of ash and our novel approach to condensation of alkali vapor species, was more accurate in predicting ash deposit rate of a variety of fuel combustion of a 100-kW combustor. The model calculated four mechanisms: inertial impaction, thermophoresis, condensation, and eddy impaction.