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Prediction of the form of a hardened metal workpiece during the straightening process
Tadej Peršak, Jernej Hernavs, Tomaž Vuherer, Aleš Belšak, Simon Klančnik, 2023, izvirni znanstveni članek

Opis: In industry, metal workpieces are often heat-treated to improve their mechanical properties, which leads to unwanted deformations and changes in their geometry. Due to their high hardness (60 HRC or more), conventional bending and rolling straightening approaches are not effective, as a failure of the material occurs. The aim of the research was to develop a predictive model that predicts the change in the form of a hardened workpiece as a function of the arbitrary set of strikes that deform the surface plastically. A large-scale laboratory experiment was carried out in which a database of 3063 samples was prepared, based on the controlled application of plastic deformations on the surface of the workpiece and high-resolution capture of the workpiece geometry. The different types of input data, describing, on the one hand, the performed plastic surface deformations on the workpieces, and on the other hand the point cloud of the workpiece geometry, were combined appropriately into a form that is a suitable input for a U-Net convolutional neural network. The U-Net model’s performance was investigated using three statistical indicators. These indicators were: relative absolute error (RAE), root mean squared error (RMSE), and relative squared error (RSE). The results showed that the model had excellent prediction performance, with the mean values of RMSE less than 0.013, RAE less than 0.05, and RSE less than 0.004 on test data. Based on the results, we concluded that the proposed model could be a useful tool for designing an optimal straightening strategy for high-hardness metal workpieces. Our results will open the doors to implementing digital sustainability techniques, since more efficient handling will result in fewer subsequent heat treatments and shorter handling times. An important goal of digital sustainability is to reduce electricity consumption in production, which this approach will certainly do.
Ključne besede: sustraightening process, hardened workpiece, manufacturing, U-Net convolutional neural network, modeling, point cloud, digital sustainability
Objavljeno v DKUM: 02.04.2024; Ogledov: 120; Prenosov: 15
.pdf Celotno besedilo (10,52 MB)
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An experimental investigation of BPMN-based corporate communications modeling
Gregor Polančič, Boštjan Orban, 2023, izvirni znanstveni članek

Opis: Purpose Despite corporate communications having an immense impact on corporate success, there is a lack of dedicated techniques for their management and visualization. A potential strategy is to apply business process management (BPM) approach with business process model and notation (BPMN) modeling techniques. Design/methodology/approach The goal of this study was to gain empirical insights into the cognitive effectiveness of BPMN-based corporate communications modeling. To this end, experimental research was performed in which subjects tested two modeling notations – standardized BPMN conversation diagrams and a BPMN extension with corporate communications-specific concepts. Findings Standard conversation diagrams were demonstrated to be more time-efficient for designing and interpreting diagrams. However, the subjects made significantly fewer mistakes when interpreting the diagrams modeled in the BPMN extension. Subjects also evolved positive perceptions toward the proposed extension. Practical implications BPMN-based corporate communications modeling may be applied to organizations to depict how formal communications are or should be performed consistently, effectively and transparently by following and integrating with BPM approaches and modeling techniques. Originality/value The paper provides empirical insights into the cognitive effectiveness of corporate communications modeling based on BPMN and positions the corresponding models into typical process architecture.
Ključne besede: corporate communication, BPMN, controlled experiment, conversation diagrams, cognitive effectiveness, modeling
Objavljeno v DKUM: 26.03.2024; Ogledov: 104; Prenosov: 17
.pdf Celotno besedilo (1,63 MB)
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Sustainable operations of last mile logistics based on machine learning processes
Jerko Oršič, Borut Jereb, Matevž Obrecht, 2022, izvirni znanstveni članek

Opis: The last-mile logistics is regarded as one of the least efficient, most expensive, and polluting part of the entire supply chain and has a significant impact and consequences on sustainable delivery operations. The leading business model in e-commerce called Attended Home Delivery is the most expensive and demanding when a short delivery window is mutually agreed upon with the customer, decreasing possible optimizing flexibility. On the other hand, last-mile logistics is changing as decisions should be made in real time. This paper is focused on the proposed solution of sustainability opportunities in Attended Home Delivery, where we use a new approach to achieve more sustainable deliveries with machine learning forecasts based on real-time data, different dynamic route planning algorithms, tracking logistics events, fleet capacities and other relevant data. The developed model proposes to influence customers to choose a more sustainable delivery time window with important sustainability benefits based on machine learning to predict accurate time windows with real-time data influence. At the same time, better utilization of vehicles, less congestion, and fewer failures at home delivery are achieved. More sustainable routes are selected in the preplanning process due to predicted traffic or other circumstances. Increasing time slots from 2 to 4 h makes it possible to improve travel distance by about 5.5% and decrease cost by 11% if we assume that only 20% of customers agree to larger time slots.
Ključne besede: supply chain management, real-time, home delivery, business modeling, e-commerce, time window
Objavljeno v DKUM: 19.02.2024; Ogledov: 158; Prenosov: 20
.pdf Celotno besedilo (1,54 MB)
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Analysis of higher-order bézier curves for approximation of the static magnetic properties of NO electrical steels
Ermin Rahmanović, Martin Petrun, 2024, izvirni znanstveni članek

Opis: Adequate mathematical description of magnetization curves is indispensable in engineering. The accuracy of the description has a significant impact on the design of electric machines and devices. The aim of this paper was to analyze the capability of Bézier curves systematically, to describe the nonlinear static magnetic properties of non-oriented electrical steels, and to compare this approach versus the established mathematical descriptions. First, analytic functions versus measurements were analyzed. The Bézier curves were then compared systematically with the most adequate analytic functions. Next, the most suitable orders of Bézier curves were determined for the approximation of nonlinear magnetic properties, where the influence of the range of the input measurement dataset on the approximation process was analyzed. Last, the extrapolation capabilities of the Bézier curves and analytic functions were evaluated. The general conclusion is that Bézier curves have adequate flexibility and significant potential for the approximation and extrapolation of nonlinear properties of non-oriented electrical steels.
Ključne besede: analytical modeling, anhysteretic curve, applied mathematics, Bézier curve, curve fitting, first magnetization curve, major loop, mathematical modeling, non-oriented electrical steel
Objavljeno v DKUM: 01.02.2024; Ogledov: 229; Prenosov: 13
.pdf Celotno besedilo (4,90 MB)

Text mining tourism literature
Ajda Pretnar Žagar, Tomaž Curk, 2021, objavljeni znanstveni prispevek na konferenci

Opis: Literature reviews are essential for understanding a specific domain as they map the main topics of current re-search. Our aim was to provide a framework for retrieving articles from online databases and analyzing them in a single script. We provide the analytical pipeline as open-source (https://github.com/tourism4-0/BibMine). The main research focus was on analyzing 318 abstracts from scientific papers on tourism and innovation, which we report in Zach et al. (2019). We used LDA topic modeling to uncover ten main topics, which we analyzed using pyLDAvis visualization. We used saliency and relevance scores to determine the main words that de-scribe a topic. The uncovered topics range from climate change and land use to smart destinations, travel expe-riences, and ICT. We performed similar analyses for the term "stakeholders," where we also observed the main verbs related to the query. Since verbs best define an activity, we used them to determine how stakeholders are involved in tourism development. Finally, we analyzed papers with the keyword "technology," where energy efficiency, VR, web technology, and augmented tourist experiences were the main topics.
Ključne besede: text mining, literature review, meta-analysis, topic modeling, tourism
Objavljeno v DKUM: 24.01.2024; Ogledov: 155; Prenosov: 3
.pdf Celotno besedilo (24,52 MB)
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Experimental validation of a dynamic photovoltaic/thermal collector model in combination with a thermal energy storage tank
Klemen Sredenšek, Sebastijan Seme, Bojan Štumberger, Miralem Hadžiselimović, Amor Chowdhury, Zdravko Praunseis, 2021, izvirni znanstveni članek

Opis: The primary objective of this paper is to present a dynamic photovoltaic/thermal collector model in combination with a thermal energy storage tank. The added value of the proposed model is the use and integration of existing dynamic models for describing the entire photovoltaic/thermal system. The presented model was validated using measurements on the experimental system located at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor. The validation was carried out based on three different weather conditions—sunny, cloudy, and overcast. The validation results were evaluated using the normalized root mean square error and mean absolute percentage error for the temperature and output power of the photovoltaic/thermal collector and the temperature of the thermal energy storage tank. The model results concurred with the measurements, as the average mean absolute percentage error values for the temperature and output power of the photovoltaic/thermal collector and thermal energy storage tank temperature were 5.82%, 1.51%, and 7.58% respectively.
Ključne besede: photovoltaic/thermal collector, thermal energy storage tank, dynamic modeling, temperature distribution, output power
Objavljeno v DKUM: 13.11.2023; Ogledov: 206; Prenosov: 13
.pdf Celotno besedilo (8,22 MB)
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Experimental validation of a thermo-electric model of the photovoltaic module under outdoor conditions
Klemen Sredenšek, Bojan Štumberger, Miralem Hadžiselimović, Sebastijan Seme, Klemen Deželak, 2021, izvirni znanstveni članek

Opis: An operating temperature of the photovoltaic (PV) module greatly affects performance and its lifetime. Therefore, it is essential to evaluate operating temperature of the photovoltaic module in different weather conditions and how it affects its performance. The primary objective of this paper is to present a dynamic thermo-electric model for determining the temperature and output power of the photovoltaic module. The presented model is validated with field measurement at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor, Slovenia. The presented model was compared with other models in different weather conditions, such as clear, cloudy and overcast. The evaluation was performed for the operating temperature and output power of the photovoltaic module using Root-Mean-Square-Error (RMSE) and Mean-Absolute-Error (MAE). The average RMSE and MAE values are 1.75C and 1.14C for the thermal part and 20.34 W and 10.97 W for the electrical part.
Ključne besede: dynamic modeling, thermo-electric model, accuracy, measuring device, temperature, output power, PV module
Objavljeno v DKUM: 13.11.2023; Ogledov: 266; Prenosov: 16
.pdf Celotno besedilo (9,51 MB)
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Design of thermal power plant modernization and rehabilitation model for the new market demands and challenges
Martin Bricl, Jurij Avsec, 2021, izvirni znanstveni članek

Opis: The article presents the model for the rehabilitation of existing conventional thermal power plants in order to lower the consumption of fossil fuels. Instead of them, the model uses an alternative energy source - sun irradiation. The proposed rehabilitation model is theoretically calculated and designed. The model in the software environment Matlab Simulink was developed, based on previous calculations and determined parameters. In this article, it is presented the combination of Clausius - Rankine process and solar central receiver system. The model enables simultaneous calculations of exit model parameters for the complete model, based on predetermined entering parameters of the model.
Ključne besede: Clausius Rankine process, solar central receiver system, modeling, analysis, Matlab Simulink software environment
Objavljeno v DKUM: 10.11.2023; Ogledov: 189; Prenosov: 13
.pdf Celotno besedilo (1001,15 KB)
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Designing and sculpting a fantasy character in the software Blender : diplomsko delo
Ognen Cvetanoski, 2023, diplomsko delo

Opis: This thesis delves into the visual communications and techniques of 3D character sculpting within the Blender software. The objective of this study is to understand how each element from visual communications and graphic design theory is crucial for the creation of a coherent, intriguing and engaging character. Through an extensive look at the three sculptural tenets, the research presents an overview of the necessary guidelines to be considered for any sculpting process. Furthermore, we sketch the first iteration of our character upon analyzing already existing fantastical characters. In this study we delve into the basics of the Blender software and its sculpting capabilities along with its various tools and brushes. Additionally, we focus on the creation of realistic materials which are going to be rendered in the software's own Cycles render engine. Lastly, in the postprocessing stage we will elevate the final product to appear more striking and appealing for the audience.
Ključne besede: Blender, Digital sculpting, Modeling, Design.
Objavljeno v DKUM: 13.10.2023; Ogledov: 291; Prenosov: 33
.pdf Celotno besedilo (6,57 MB)

Development and optimisation of a business intelligence system : master's thesis
Mark Žohar, 2023, magistrsko delo

Opis: In the fast-paced business landscape, unexpected events can pose significant challenges for companies. A lot of times, business intelligence presents a solution for companies in dealing with changes and improving organizational efficiency. As part of this master’s thesis, we have developed a business intelligence system that assists in the planning of new releases of smartphone components. We have simulated data and created reports, which can help the stakeholders to plan and analyze important milestones easily. We have tested two different data structures and showed how star schema is the most beneficial data structure for our BI system. We achieved this by restructuring data into a star schema model at different stages of migration and then compared the size of data and responsiveness of operations.
Ključne besede: business intelligence, star schema, data modeling
Objavljeno v DKUM: 27.06.2023; Ogledov: 321; Prenosov: 44
.pdf Celotno besedilo (1,69 MB)

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