| | SLO | ENG | Cookies and privacy

Bigger font | Smaller font

Search the digital library catalog Help

Query: search in
search in
search in
search in
* old and bologna study programme

Options:
  Reset


1 - 10 / 49
First pagePrevious page12345Next pageLast page
1.
2.
Review of Antlions (Insecta: Neuroptera: Myrmeleontidae) in North Macedonia
Dušan Devetak, Ana Nahirnić, Predrag Jakšić, Vesna Klokočovnik, Tina Klenovšek, Davide Badano, Jan Podlesnik, 2023, original scientific article

Abstract: We present the state of knowledge on the family Myrmeleontidae occurring in North Macedonia based on published records, museum specimens and new samples, and provide a comprehensive species list. North Macedonia represents only 3.9% of the area of the Balkan Peninsula but harbours 19 species belonging to 14 antlion genera, i.e., 61% of the peninsular fauna. We report collection localities, literature records and biological data for each species. Three species, Nemoleon poecilopterus, Neuroleon assimilis and Myrmeleon inconspicuus, are reported for the first time in North Macedonia. The genus Nemoleon Navás is also reported for the first time in the country.
Keywords: Myrmeleontidae, checklist, distribution, new records, Balkan Peninsula
Published in DKUM: 15.04.2024; Views: 157; Downloads: 4
.pdf Full text (497,47 KB)
This document has many files! More...

3.
4.
Static model of temperature distribution in a photovoltaic module
Klemen Sredenšek, Sebastijan Seme, Gorazd Hren, 2021, original scientific article

Abstract: The primary objective of this paper is to present a static model for calculating the temperature distribution in a photovoltaic module using the finite element method. The paper presents in more detail the theoretical background of solar radiation, heat transfer, and the finite element method. The results of the static model are evaluated using temperature measurements of a photovoltaic model, which were performed at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor. The results of the regression analysis show a good concurrence between the measured and modelled values of the temperature of the photovoltaic module, especially on days with a higher share of the direct component of solar radiation.
Keywords: photovoltaic module, temperature distribution, heat transfer, finite element method
Published in DKUM: 13.11.2023; Views: 237; Downloads: 6
.pdf Full text (2,01 MB)
This document has many files! More...

5.
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, original scientific article

Abstract: 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.
Keywords: photovoltaic/thermal collector, thermal energy storage tank, dynamic modeling, temperature distribution, output power
Published in DKUM: 13.11.2023; Views: 268; Downloads: 13
.pdf Full text (8,22 MB)
This document has many files! More...

6.
Proportional-integral controllers performance of a grid-connected solar PV system with particle swarm optimization and Ziegler-Nichols tuning method
Klemen Deželak, Peter Braciník, Klemen Sredenšek, Sebastijan Seme, 2021, original scientific article

Abstract: This paper deals with photovoltaic (PV) power plant modeling and its integration into the medium-voltage distribution network. Apart from solar cells, a simulation model includes a boost converter, voltage-oriented controller and LCL filter. The main emphasis is given to the comparison of two optimization methods-particle swarm optimization (PSO) and the Ziegler-Nichols (ZN) tuning method, approaches that are used for the parameters of Proportional-Integral (PI) controllers determination. A PI controller is commonly used because of its performance, but it is limited in its effectiveness if there is a change in the parameters of the system. In our case, the aforementioned change is caused by switching the feeders of the distribution network from an open-loop to a closedloop arrangement. The simulation results have claimed the superiority of the PSO algorithm, while the classical ZN tuning method is acceptable in a limited area of operation.
Keywords: photovoltaic power plant, optimization, PI controllers, distribution system
Published in DKUM: 10.11.2023; Views: 297; Downloads: 12
.pdf Full text (3,36 MB)
This document has many files! More...

7.
Uporaba indikatorjev tehnične analize pri napovedi trendov na borznih in deviznih trgih
Urška Repušič, 2023, undergraduate thesis

Abstract: V diplomski nalogi ugotavljamo uporabnost indikatorjev tehnične analiz pri napovedi trendov na borznih in deviznih trgih, v zadnjem delu diplomske naloge ugotavljamo tudi uporabnost in pomen kombiniranja različnih indikatorjev tehnične analize. Vključili smo tudi pomen in uporabnost poznavanja tržnih struktur in njihovo kombiniranje z indikatorji tehnične analize. Investitorji na borznih in deviznih trgih si prizadevajo razumeti, katere indikatorje in katere tržne strategije v okviru posameznega indikatorja uporabiti z namenom obvladovanja prisotnih tveganj pri trgovanju na teh trgih in tudi za maksimiranje dobičkov. V diplomski nalogi so s teoretičnega in praktičnega vidika predstavljeni izbrani indikatorji tehnične analize, tržni trendi in strukture ter pomen in uporabnost kombiniranja različnih indikatorjev ter tržnih struktur. V diplomski nalogi smo ugotovili, da ima pri napovedih trenda na borznih in deviznih trgih veliko vlogo vsebinsko razumevanje posameznega indikatorja tehnične analize, branje grafikonov z vključenimi indikatorji in identificiranje signalov pri odločanju o trgovanju, pri določevanju vstopnih in izstopnih točk ter pri določanju kratkoročnih in dolgoročnih trendov. Iz praktičnim primerov, vključenih v diplomski nalogi se je ugotovilo, katere indikatorje je potrebno uporabiti za različne tržne strategije in katere kombinacije indikatorjev je smiselno uporabit za pridobitev dodatnih potrditev pravilnosti načrtovane strategije investiranja.
Keywords: MA, ADX, Parabolic SAR, MACD, RSI, stohastični oscilator, OBV, MFI, Accumulation/Distribution, pasovi bollingerja, ATR, Fibonacci nivoji.
Published in DKUM: 09.11.2023; Views: 264; Downloads: 17
.pdf Full text (3,96 MB)

8.
Use of active elements for providing suitable voltage profiles and prevent overloads in radial distribution networks
Marko Vodenik, Matej Pintarič, Gorazd Štumberger, 2022, original scientific article

Abstract: The article deals with the issue of providing suitable voltage profiles and preventing congestion of network elements in distribution networks. Active network elements and network users’ energy flexibility services are used to provide a suitable voltage profile and prevent congestion in distribution networks. The discussed active network elements include a transformer with on-load tap changer, reactive power compensation devices, energy storage systems, distributed energy resources, and network users’ energy flexibility services, where the active consumers adjust their consumption, production and storage of energy. Based on the Backward Forward Sweep load flow computation method, the case studies are performed for the discussed low voltage distribution network, where the measurement results were available. The case studies for preventing overload of the distribution transformer are performed using a battery energy storage system and network users’ energy flexibility services. The case studies for providing suitable voltage profiles are performed using all listed active elements and a combination of different active elements. In addition, to provide suitable voltage profiles, the existing conductors are replaced with conductors of a larger cross-section. Technically acceptable solutions that can provide a suitable voltage profile and prevent the overloading of network elements in the most demanding operating conditions are presented in this article.
Keywords: voltage profile, radial distribution network, load flow calculations, active network elements, energy flexibility
Published in DKUM: 30.10.2023; Views: 496; Downloads: 5
.pdf Full text (5,24 MB)
This document has many files! More...

9.
The use of differential evolution to determine maximum generation and load values in the distribution network
Eva Tratnik, Janez Ribič, Matej Pintarič, Miran Rošer, Gorazd Štumberger, Miloš Beković, 2022, original scientific article

Abstract: By integrating renewable energy sources into the existing distribution network, the characteristics and local stability of the network is highly impacted. The network, which was built with the goal of a directed energy flow from large conventional sources connected to the transmission network via the distribution network to consumers, can change the direction of the energy flow. The adoption of environmental commitments and directives encourages the integration of local dispersed energy sources, which can worsen voltage conditions in the distribution network. To avoid excessive local production, distribution network operators must limit the installation of new generati on units, as it is necessary to take into account the quality of power supply by monitoring its network parameters, such as the appropriate voltage profi le and the rati o between acti ve and reacti ve power. On the other hand, excessive loads due to the mass transiti on of household heati ng and transport towards electricity can also pose a problem for high-quality electricity supply due to the excessive voltage drop. The arti cle presents an algorithm for determining the maximum size of unit producti on and the maximum load at a node in the distributi on network. Also demonstrated is the use of variable tap transformer technology, which adjusts the tap of the transformer to provide an appropriate voltage profi le in the network. The enti re analysis was performed on a model of a real medium-voltage network, in which solar and hydropower plants are already included. The model was verifi ed by comparing its calculated values with actual measurements. The goal was to determine the size of the unit’s maximum producti on, as well as the size of the maximum load, by using the diff erenti al evoluti on algorithm, while keeping voltage profi les within the permissible limits. The results of the analysis are presented in the article.
Keywords: distribution network, renewable energy sources, optimisation method, voltage profile
Published in DKUM: 30.10.2023; Views: 379; Downloads: 12
.pdf Full text (1,63 MB)
This document has many files! More...

10.
The Impact of coal and CO2 emission coupon market-driven prices on the economic operation of thermal power plants
Martin Bricl, Jurij Avsec, 2022, published scientific conference contribution abstract

Keywords: heat capacity peak, first-order phase change, domain size distribution, averaging
Published in DKUM: 27.10.2023; Views: 224; Downloads: 4
.pdf Full text (14,78 MB)
This document has many files! More...

Search done in 6.37 sec.
Back to top
Logos of partners University of Maribor University of Ljubljana University of Primorska University of Nova Gorica