Electrified powertrain configuratorJernej 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: 469; Downloads: 0
Analyzing the process of patent aubmission with a special emphasis on the phases of the research processMitja Ruzzier
, Tine Nagy
, Robert Ravnihar
, 2009, original scientific article
Abstract: This article presents some findings about the process of patenting of Slovenian and foreign researchers in scientific research. Based on the reviewed literature and with help of our conceptual model, we establish that the patenting process can be divided into three separate phases: knowledge detection phase, knowledge dissemination phase and knowledge transfer phase. During the process of researching and patenting, a variety of factors affect the results, which can be divided into two groups: internal and external factors. In Slovenia, patents are statistically significant for researchers working and exploring in the fields of natural science and engineering. Research results in the form of a patent largely depend on financial support and work experiences of individual researchers or research groups. The commercialization of a patent means a successful ending of the research process, as many positive benefits are expected.
Keywords: researchers patenting activity, researchers patenting productivity, process of innovation, patenting process, patent driving forces, patent driving areas, academic entrepreneurship
Published: 28.11.2017; Views: 614; Downloads: 74
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The influence of electric arc activation on the speed of heating and the structure of metal in weldsOleksandr Savytsky
, Mychailo Savytsky
, Darko Bajić
, Yuriy Shkrabalyuk
, Tomaž Vuherer
, 2016, original scientific article
Abstract: This paper presents the results of a research related to the impact of electric arc activation onto drive welding energy and metal weld heating speed. It is confirmed that ATIG and AMIG methods, depending on metal thickness, single pass weldability and chemical composition of activating flux, enable the reduction of welding energy by 2-6 times when compared to conventional welding methods. Additionally, these procedures create conditions to increase metal weld heating speed up to 1,500-5,500 °C/s-1. Steel which can be rapidly heated, allows for a hardened structure to form (with carbon content up to 0.4%), together with a released martensitic structure or a mixture of bainitic-martensitic structures. Results of the research of effectiveness of ATIG and AMIG welding showed that increase in the penetration capability of electric arc, which increases welding productivity, is the visible side of ATIG and AMIG welding capabilities.
Keywords: arc welding, active flux, penetration, heating speed, driving energy
Published: 07.07.2017; Views: 518; Downloads: 273
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Prevention of wrong-way driving on freewaysDarja Topolšek
, 2007, review article
Abstract: Traffic accidents that occur on freeways often end tragically because of high driving speed. Wrong-way driving is also one of the causes of accidents on freeways. Research is based on the analysis of traffic accident data caused by wrong-way driving on freeways and considering valid technical specifications for connections and junctions design elements. Research is based on the analysis of the data of traffic accidents that occurred because of wrong-way driving on freeways and on the consideration of valid technical specifications concerning connections and junction design elements. The thesis presents possible countermeasures for prevention of wrong-way driving and consequential decrease in the number of traffic accidents. The proposed prevention countermeasures of wrong-way driving on freeways could greatly reduce incorrect traffic vehicle movements that are the consequence of wrong-way driving and thus positively enhance the traffic safety level on freeways.
Keywords: wrong-way driving, freeway, multilevel connections, multilevel junctions, traffic safety, traffic accidents, countermeasures
Published: 05.06.2017; Views: 687; Downloads: 89
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Behavioural comparison of drivers when driving a motorcycle or a carDarja Topolšek
, Dejan Dragan
, 2015, original scientific article
Abstract: The goal of the study was to investigate if the drivers behave in the same way when they are driving a motorcycle or a car. For this purpose, the Motorcycle Rider Behaviour Questionnaire and Driver Behaviour Questionnaire were conducted among the same drivers population. Items of questionnaires were used to develop a structural equation model with two factors, one for the motorcyclist's behaviour, and the other for the car driver's behaviour. Exploratory and confirmatory factor analyses were also applied in this study. Results revealed a certain difference in driving behaviour. The principal reason lies probably in mental consciousness that the risk-taking driving of a motorbike can result in much more catastrophic consequences than when driving a car. The drivers also pointed out this kind of thinking and the developed model has statistically confirmed the behavioural differences. The implications of these findings are also argued in relation to the validation of the appropriateness of the existing traffic regulations.
Keywords: driving behaviour, motorcycle rider behaviour, car driver behaviour, traffic accidents, structural equation modelling, violations, errors
Published: 01.06.2017; Views: 511; Downloads: 100
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Dynamical and statistical properties of time-dependent one-dimensional nonlinear Hamilton systemsDimitrios Andresas
, 2015, doctoral dissertation
Abstract: We study the one-dimensional time-dependent Hamiltonian systems and their statistical behaviour, assuming the microcanonical ensemble of initial conditions and describing the evolution of the energy distribution in three characteristic cases: 1) parametric kick, which by definition means a discontinuous jump of a control parameter of the system, 2) linear driving, and 3) periodic driving. For the first case we specifically analyze the change of the adiabatic invariant (the canonical action) of the system under a parametric kick: A conjecture has been put forward by Papamikos and Robnik (2011) that the action at the mean energy always increases, which means, for the given statistical ensemble, that the Gibbs entropy in the mean increases (PR property). By means of a detailed rigorous analysis of a great number of case studies we show that the conjecture largely is satisfied, except if either the potential is not smooth enough (e.g. has discontinuous first derivative), or if the energy is too close to a stationary point of the potential (separatrix in the phase space). We formulate the conjecture in full generality, and perform the local theoretical analysis by introducing the ABR property. For the linear driving we study first 1D Hamilton systems with homogeneous power law potential and their statistical behaviour under monotonically increasing time-dependent function A(t) (prefactor of the potential). We used the nonlinear WKB-like method by Papamikos and Robnik J. Phys. A: Math. Theor., 44:315102, (2012) and following a previous work by Papamikos G and Robnik M J. Phys. A: Math. Theor., 45:015206, (2011) we specifically analyze the mean energy, the variance and the
adiabatic invariant (action) of the system for large time t→∞. We also show analytically that the mean energy and the variance increase as powers of A(t), while the action oscillates and finally remains constant. By means of a number of detailed case studies we show that the theoretical prediction is correct. For the periodic driving cases we study the 1D periodic quartic oscillator and its statistical behaviour under periodic time-dependent function A(t) (prefactor of the potential). We compare the results for three different drivings, the periodic parametrically kicked case (discontinuous jumps of $A(t)$), the piecewise linear case (sawtooth), and the smooth case (harmonic). Considering the Floquet map and the energy distribution we perform careful numerical analysis using the 8th order symplectic integrator and present the phase portraits for each case, the evolution of the average energy and the distribution function of the final energies. In the case where we see a large region of chaos connected to infinity, we indeed find escape orbits going to infinity, meaning that the energy growth can be unbounded, and is typically exponential in time.
The main results are published in two papers:
Andresas, Batistić and Robnik Phys. Rev. E, 89:062927, (2014) and
Andresas and Robnik J. Phys. A: Math. Theor., 47:355102, (2014).
Keywords: one-dimensional nonlinear Hamiltonian systems, adiabatic invariant, parametric kick, periodic driving, linear driving, energy distribution, WKB method, action
Published: 02.03.2015; Views: 1884; Downloads: 68
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On fracture behaviour of inhomogeneous materials - a case study for elastically inhomogeneous bimaterialsOtmar Kolednik
, Jožef Predan
, G.X. Shan
, N.K. Simha
, Franz Dieter Fischer
, 2005, original scientific article
Abstract: This paper presents a case study, examining the influence of a sharp bimaterial interface on the effective crack driving force in a fracture mechanics specimen. The inhomogeneity of the elastic modulus in linear elasticand non-hardening and hardening elastic-plastic bimaterials is considered. The interface is perpendicular to the crack plane. The material properties and the distance between the crack tip and the interface are systematically varied. The effect of the material inhomogeneity is captured in form of a quantity called "material inhomogeneity term",▫$C_inh$▫. This term can be evaluated either by a simple post-processing procedure, following a conventional finite element stress analysis, or by computing the J-integral along a contour around the interface, ▫$J_int$▫. The effective crack driving force,▫$J_tip$▫, can be determined as the sum of ▫$C_inh$▫ and the nominally applied far-field crack driving force, ▫$J_far$▫. The results show that ▫$C_inh$▫ can be accurately determined by both methods even in cases where ▫$J_tip$▫-values are inaccurate. When a crack approaches a stiff/compliant interface,▫$C_inh$▫ is positive and ▫$J_tip$▫ becomes larger than ▫$J-far$▫. A compliant/stiff transition leads to a negative ▫$C_inh$▫, and ▫J_tip$▫ becomes smaller than ▫$J_far$▫. The material inhomogeneity term, ▫$C_inh$▫, can have the same order of magnitude as ▫$J_far$▫. Based on the numerical results, the dependencies of ▫$C_inh$▫ on the material parameters and the geometry are derived. Simple expressions are obtained to estimate ▫$C_inh$▫.
Keywords: mechanics of structures, fracture toughness, inhomogeneous materials, J-integral, crack driving force, interface, material force
Published: 01.06.2012; Views: 1064; Downloads: 14
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On the local variation of the crack driving force in a double mismatched weldJožef Predan
, Nenad Gubeljak
, Otmar Kolednik
, 2007, original scientific article
Abstract: A material inhomogeneity in the direction of crack extension causes a difference between the near-tip crack driving force, Jtip, and the nominally applied far-field crack driving force, Jfar. This difference can be quantified by a material inhomogeneity term, Cinh, which is evaluated by a post-processing procedure to a conventional finite element stress analysis. The magnitude of the material inhomogeneity term is evaluated for cracks in an inhomogeneous welded joint made of a high-strength low-alloy steel. Both a crack proceeding from the under-matched (UM) to the over-matched (OM) and from the OM to the UM weld metal are treated. The effects of the inhomogeneity of the different material parameters (modulus of elasticity, yield strength, and strain hardening exponent) on Cinh and Jtip are systematically studied. The results demonstrate that the material inhomogeneity term is primarily influenced by the inhomogeneity of the yield strength. A crack growing towards an OM/UM interface experiences an accelerated crack growth rate or a pop-in, an UM/OM interface leads to a reduced crack growth rate or a crack arrest. The application of global assessment methods of the mismatch effect which are included in the Engineering Treatment Model (ETM) or in the Structural Integrity Assessment Procedures for European Industry (SINTAP) is discussed.
Keywords: crack driving force, material inhomogeneity, mismatched weld, interface, J-integral, finite element modeling
Published: 31.05.2012; Views: 1158; Downloads: 70
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Using neural networks in the process of calibrating the microsimulation models in the analysis and design of roundabouts in urban areasIrena Ištoka Otković
, 2011, dissertation
Abstract: The thesis researches the application of neural networks in computer program calibration of traffic micro-simulation models. The calibration process is designed on the basis of the VISSIM micro-simulation model of local urban roundabouts.
From the five analyzed methods of computer program calibration, Methods I, II and V were selected for a more detailed research. The three chosen calibration methods varied the number of outgoing traffic indicators predicted by neural networks and a number of neural networks in the computer program calibration procedure. Within the calibration program, the task of neural networks was to predict the output of VISSIM simulations for selected functional traffic parameters - traveling time between the measurement points and queue parameters (maximum queue and number of stopping at the roundabout entrance). The Databases for neural network training consisted of 1379 combinations of input parameters whereas the number of output indicators of VISSIM simulations was varied. The neural networks (176 of them) were trained and compared for the calibration process according to training and generalization criteria. The best neural network for each calibration method was chosen by using the two-phase validation of neural networks.
The Method I is the calibration method based on calibration of a traffic indicator -traveling time and it enables validation related to the second observed indicator – queue parameters. Methods II and V connect the previously described calibration and validation procedures in one calibration process which calibrates input parameters according to two traffic indicators.
Validation of the analyzed calibration methods was performed on three new sets of measured data - two sets at the same roundabout and one set on another location. The best results in validation of computer program calibration were achieved by the Method I which is the recommended method for computer program calibration.
The modeling results of selected traffic parameters obtained by calibrated VISSIM traffic model were compared with: values obtained by measurements in the field, the existing analysis methods of operational roundabouts characteristics (Lausanne method, Kimber-Hollis, HCM) and modeling by the uncalibrated VISSIM model. The calibrated model shows good correspondence with measured values in real traffic conditions. The efficiency of the calibration process was confirmed by comparing the measured and modeled values of delays, of an independent traffic indicator that was not used in the process of calibration and validation of traffic micro-simulation models.
There is also an example of using the calibrated model in the impact analysis of pedestrian flows on conflicting input and output flows of vehicles in the roundabout. Different traffic scenarios were analyzed in the real and anticipated traffic conditions.
Keywords: traffic models, traffic micro-simulation, calibration of the VISSIM model, computer program calibration method, neural networks in the calibration process, micro-simulation of roundabouts, traffic modeling parameters, driving time, queue parameters, delay
Published: 02.06.2011; Views: 4051; Downloads: 298
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