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Sensitivity Analysis of Hybrid Powertrain Pre-calibration Algorithms : magistrsko delo
Simon Šegula, 2023, master's thesis

Abstract: Currently, meeting the new fuel consumption and emissions standards is the biggest challenge in the automotive industry. One of the solutions is hybridization of the vehicle’s powertrain. This brings with it larger complexity of the vehicle control unit and its pre-calibration. This thesis explores gear shift map and load point shift map, which are two pre-calibration maps included in the vehicle control unit. More specifically it delves in to how the pre-calibration maps are created and how changing their parameters impacts the fuel consumption of the vehicle. Algorithms and optimization simulations were created and performed using AVL’s tool called the Powertrain system optimizer (PSO) which was created within the MATLAB software.
Keywords: Hybrid electric vehicle, Hybrid powertrain, Gear shift map, Load point shift map, Pre-calibration.
Published in DKUM: 23.11.2023; Views: 346; Downloads: 0

Development of a methodology to calibrate a pedestrian microsimulation model : doctoral dissertation
Chiara Gruden, 2022, doctoral dissertation

Abstract: Walking, as a mode of transport, is becoming widespread, in a world, where urban conglomerates are broadening and becoming denser. Modern lifestyle trends on a side, and eco-friendly policies on the other, push people into walking habits, increasing the need for a suitable, attractive, accessible, connected and safe walking infrastructure. To reach such a result, it is necessary to understand, what are the needs of the users of this infrastructure, taking into consideration the behavioral specificities and the safety needs of pedestrians. In this process pedestrian microsimulation models, surrogate safety techniques, and technologies able to measure specific traits of pedestrian dynamics play a central role. The firsts allow to reproduce repeatedly in a virtual environment a specific infrastructure and to study the response of pedestrians. Nevertheless, to be accurate and efficient, they need to go through long and tedious calibration and validation processes, that are often seen as an important limitation by technicians. Surrogate safety techniques are methods, that are based on the concept, that it is possible to predict the safety level of a location, using near accidents. The main advantage of such techniques is that they are proactive. Till this moment, these techniques have been mainly applied to on-field measurements and are primarily centered on motorized road users. Less interest has been shown for vulnerable road users, especially for pedestrians, who have been less extensively studied. Finally, an element that could highly affect pedestrian safety is their reaction time. Nevertheless, its measurement has long been a big issue. Eye-tracking technology could be one of the solutions, allowing to analyze the directions and objects fixated by pedestrians. These listed issues are also the topics that are addressed by this research work. Focusing on the study of the action of pedestrians while crossing the road on an unsignalized crosswalk set on a roundabout entry leg, the dissertation thesis aims at studying the crossing time, reaction time and surrogate safety aspects typical of pedestrians at the recalled location. The main purpose of the research work is to develop a methodology to calibrate pedestrian Social Force Model at a selected location, using a specifically formulated neural network as a tool to fine-tune model's behavioral parameters. Eight parameters have been chosen to be fine-tuned, five of those are related to pedestrian behavior and three of them are related to car-following behavior. After the selection of input parameters, a feedforward network has been formulated. Its application in the framework of the whole calibration process has brought to considerably positive results, finding a combination of input parameters that improved the performance of the microsimulation model of 37 % in comparison to the default one. The outputs of the calibrated model have been used to calculate three measures of surrogate safety, and also in this case results demonstrated an improvement in the calculation of surrogate safety measures when using the calibrated outcomes in comparison to their calculation on the “default” model outputs. Finally, reaction time measurement and prediction have been addressed by the thesis, in order to be able to describe pedestrian crossing action in its completeness. Quantitative eye-tracking outputs have been the starting point for the calculation of pedestrian reaction time at different locations, and they allowed to create a database of behavioral, geometric, regulatory and flow characteristics, which was the foundation for the formulation of a new prediction model for pedestrian reaction time. The prediction model, which consists of a cascade-correlation neural network, gave a good response to the learning and generalization steps, turning a 74 % correlation between the measured reaction time values and the predicted ones, and being able to follow the variability of these values.
Keywords: pedestrian, microsimulation model, calibration, neural network, surrogate safety indicators, reaction time.
Published in DKUM: 03.10.2022; Views: 785; Downloads: 96
.pdf Full text (5,93 MB)

Simulation of automotive air-conditioning system in 1D simulation software : diplomsko delo
Marko Copot, 2019, undergraduate thesis

Abstract: The development of state-of-the-art vehicles requires advanced simulations tools in heating, ventilation and air-conditioning (HVAC). The focus of this thesis is the construction of an automotive HVAC model, its calibration and the simulation of the behaviour of the HVAC model in various ambient conditions. The theoretical background of refrigeration system as part of the HVAC system is presented. The model is constructed with following components: compressor, condenser, throttling device, evaporator and battery chiller, which is a heat exchanger between coolant and refrigerant. The description and role of each component in the HVAC model is presented. All heat exchangers are calibrated, which is done with multiple simulations that have defined input data. The results are compared to experimental data. With addition of vehicle cabin with air recirculation, HVAC control logic is implemented. The behaviour of the system is simulated in defined environmental conditions. The results of the simulations are presented in graphs and tables.
Keywords: 1D simulations, air-conditioning, HVAC, calibration, thermodynamics, cooling
Published in DKUM: 23.09.2019; Views: 1386; Downloads: 98
.pdf Full text (1,54 MB)

How to test the reliability of instruments used in mirotremor horizontal-to-vertical spectral ratio measurements
Izidor Tasič, Franc Runovc, 2010, original scientific article

Abstract: The reliability of a horizontal-to-vertical spectral ratio (HVSR) curve depends on the results obtained by a verified seismological system. Seismic microzonation provides the basis for a site-specific risk analysis and it can be evaluated using the microtremor HVSR method, where the data are recorded using modern seismological systems. Changes in the transfer function of seismological systems affect the HVSR curve and, consequently, also its interpretation, if these changes are not detected and taken into consideration while performing the microtremor spectral calculations. The reliability of the seismic microzonation performed by such a procedure becomes questionable. An algorithm is developed with a two references system, where the influence of the transfer function on the HVSR curve by the tested system can be evaluated without any a-priori knowledge regarding the transfer functions of any of the systems. This approach is applied to a Lennartz Le-3D/5s seismometer and to a TROMINO seismological system, where two Streckeisen STS2 seismometers are used as the reference systems.
Keywords: seismic microzonation, horizontal-to-vertical spectral ratio method, ambient vibrations, microtremor, seismic system transfer function, reliability and calibration of seismic systems
Published in DKUM: 11.06.2018; Views: 1077; Downloads: 56
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Development of smart energy meter using arm platform
Darijo Topić, 2017, master's thesis

Abstract: This master thesis describes the development of smart electricity energy meter on the ARM platform. In general, the commercial electrical energy meters are measuring only the total active energy, therefore, users cannot also monitor other important power consumption parameters. The goal of this thesis is to develop a prototype of smart ARM based energy meter, which is capable to measure several power consumption parameters and display them on a webpage in real-time. In the thesis the complete design of the ARM based smart energy meter is presented in detail. Further, the development of user interface for displaying measured data on the webpage in real-time is also presented. These results are presented both in textual and graphical form. Additionally, the theory of electric power consumption measurements and some commercial energy meters are presented.
Keywords: energy meter, ARM processor, power consumption, internet of things, calibration, green environment, energy consumption measurement, emoncms
Published in DKUM: 16.11.2017; Views: 2348; Downloads: 278
.pdf Full text (5,10 MB)

Analysis of neural network responses in calibration of microsimulation traffic model
Irena Ištoka Otković, Damir Varevac, Matjaž Šraml, 2015, original scientific article

Abstract: Microsimulation models are frequently used in traffic analysis. Various optimization methods are used in calibration, and the one method that has shown success is neural networks. This paper shows the responses of neural networks during calibration of a microsimulation traffic model. We analyzed two calibration methods by applying neural networks and comparing their neural network learning (according to their achieved correlation and the mean error of prediction) and their generalization ability (comparison of generalization results was analyzed in two steps). The best correlation between the microsimulation results and neural network prediction was 88.3%, achieved for the traveling time prediction, on which the first calibration method is based.
Keywords: microsimulation traffic models, calibration, response of neural networks, traveling time, queue parameters
Published in DKUM: 02.08.2017; Views: 1289; Downloads: 376
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Analysis of the influence of car-following input parameters on the modelled travelling time
Irena Ištoka Otković, Tomaž Tollazzi, Matjaž Šraml, 2013, other scientific articles

Abstract: The calibration process is a basic condition of traffic model application in local conditions. The choice of input parameters, which are used in calibration process, influences the success of the calibration process itself; therefore, the goal is to choose parameters with a larger influence on the modelling process. This paper offers a detailed analysis of car-following input parameters and their influence on the modelled travelling time. The experimental basis was a one-lane roundabout, and the tool used for traffic simulation was the VISSIM microsimulation traffic model. The results show that the car-following input parameters should be a part of the set of input parameters, which will enter the process of calibration. The examined car-following input parameters affect the capacity of intersections and results show that it is necessary to revise the range of input values of one of the observed car-following input parameters.
Keywords: car-following input parameters, input parameters for the process of calibration, VISSIM
Published in DKUM: 11.07.2017; Views: 1220; Downloads: 146
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Calibration of electronic levels using a special sine bar
Bojan Ačko, 2005, original scientific article

Abstract: Electronic levels are designated for the precise measurement of inclination angles within the range of +- 3 mm/m. They are very often used for checking the straightness of machine tool guides as well as the flatness of different kindsof machine tool tables and surface plates. Typical resolution of such instruments is 1 m/m. Electronic levels are calibrated by using very precise angle generators. One such generator is a sine bar. Sine bars are cheap and enable fast and simple calibrations. Commercial sine bars however are not precise enough. We, therefore, decided to design a special sine bar, which would be able to generate angles within an uncertainty of 1 mžm. This sine barwas designed by the laboratory staff and manufactured in our workroom. We have also created a calibration procedure, which has already been accredited. Uncertainty analysis, including experimental measurements, shows that the planned uncertainty has been reached. The sine bar design, calibration procedure and uncertainty evaluation are presented in this article.
Keywords: production measurements, measuring uncertainty, calibration, inclination angles, flatness measurements, sine bar, electronic level
Published in DKUM: 01.06.2012; Views: 3010; Downloads: 113
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Thread gauge calibration for industrial applications
Tadeja Primožič Merkač, Bojan Ačko, 2010, original scientific article

Abstract: There are two most commonly used methods for calibration of thread rings, with different measuring uncertainty. The method of mechanical sensing with two balls is mostly used on one-axial measuring machines and on coordinate measuring machines. However, the method of calculating the core diameter of the thread ring combined with the technique of adaptation (in accordance with the method of the smallest squares) is used on the profile scanner. The required tolerances, which are very narrow for adjustable and laboratory thread ring, so the measuring uncertainty may be too high when using the method of mechanical sensing with two balls, and the low quality of some control rings, are the decisive factors for choosing an appropriate method in the industry. This also depends on the laboratoryćs capability of executing a specific method. The measurements of the core diameter of thread rings, which are the main topic of this article, were included into an international inter-comparison in which the main subject was the same thread ring as the one mentioned in this article.
Keywords: thread ring gauge, calibration, pitch diameter, measurement uncertainty, dimensional measurements
Published in DKUM: 31.05.2012; Views: 2304; Downloads: 41
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