1. Numerical analysis of low-enthalpy deep geothermal energy extraction using a novel gravity heat pipe designUrban Gselman, Vid Peršak, Darko Goričanec, 2024, izvirni znanstveni članek Opis: Geothermal energy, derived from the Earth’s internal heat, can be harnessed due to the
geothermal gradient between the Earth’s interior and its surface. This heat, sustained by radiogenic
decay, varies across regions, and is highest near volcanic areas. In 2020, 108 countries utilised
geothermal energy, with an installed capacity of 15,950 MWe for electricity and 107,727 MWt for
direct use in 2019. Low-enthalpy sources require binary systems for power production. Open-loop
systems face issues like scaling, difficult water treatment, and potential seismicity, while closed-loop
systems, using abandoned petroleum or gas wells, reduce costs and environmental impacts greatly.
The novel geothermal gravity heat pipe (GGHP) design eliminates parasitic power consumption by
using hydrostatic pressure for fluid circulation. Implemented in an abandoned well in north-east
(NE) Slovenia, the GGHP uses a numerical finite difference method to model heat flow. The system
vaporises the working fluid in the borehole, condenses it at the surface, and uses gravitational flow
for circulation, maintaining efficient heat extraction. The model predicts that continuous maximum
capacity extraction depletes usable heat rapidly. Future work will explore sustainable heat extraction
and potential discontinuous operation for improved efficiency.
Ključne besede: geothermal energy, geothermal gravity heat pipe, numerical modelling, single well closed-loop heat exchanger
Objavljeno v DKUM: 03.09.2024; Ogledov: 41; Prenosov: 2
 Celotno besedilo (3,23 MB) |
2. Single-tray VLM vs dual-tray VLM : quantitative throughput comparisonGoran Đukić, Tihomir Opetuk, Brigita Gajšek, Tone Lerher, 2021, izvirni znanstveni članek Opis: In this paper quantitative comparison of resulting throughputs for single-tray and dual-tray VLM devices is presented. Comparison is based on mathematical models for throughput approximating dual command times of VLM's crane, for selected parameters of VLM device (height and crane's velocity) and selected picking times per delivered tray. Analysis showed that throughput increase achieved by using dual-tray VLM's depends mostly on the average picking time relative to the expected dual command time of the VLM's crane. Highest improvements are possible for picking time equal to expected dual command time and amounts over 80%, however for extremely low or high picking times improvements are significantly reduced.
Ključne besede: order-picking, throughput model, vertical lift module systems, quantitative analysis, intralogistics, dual-tray VLM, single-tray VLM
Objavljeno v DKUM: 12.08.2024; Ogledov: 48; Prenosov: 7
Celotno besedilo (1009,78 KB)
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4. Recycling of acetate and ammonium from digestate for single cell protein production by a hybrid electrochemical-membrane fermentation processDanfei Zeng, Yufeng Jiang, Carina Schneider, Yanyan Su, Claus Hélix-Nielsen, Yifeng Zhang, 2023, izvirni znanstveni članek Ključne besede: resource reclamation, single cell protein, electrodialysis, forward osmosis, Saccharomyces cerevisiae
Objavljeno v DKUM: 10.05.2024; Ogledov: 180; Prenosov: 9
Celotno besedilo (1,71 MB)
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5. Current control of battery pack modules in parallel connection according to SoCMario Vražić, Antonio Persic, Peter Virtič, Tomislav Ivanis, 2023, izvirni znanstveni članek Opis: Electric vehicles, especially cars, have been in the spotlight for some time now. In the focus of environmentalists, engineers, users, media, etc. With the growth and advancement of the market for such vehicles, other electric vehicles are also focussing on. One of such vehicles is boats, particularly smaller boats up to 8–10 meters in length. Of course, the biggest problem here is charging. The general idea is to use battery modules that can be easily carried and enable hot swapping. This paper investigates scenarios and simulations of the control system for hot swapping of the battery module. Simulations of connection of two and three battery modules to parallel operation and current control are presented in this paper, as well as applied control rules.
Ključne besede: battery pack, battery modules, parallel connection, Bidirectional multiple input single output synchronous DC/DC converter, BMISO DC/DC converter, Hotplugin, Smart SoC control, Advanced SoC control
Objavljeno v DKUM: 08.04.2024; Ogledov: 370; Prenosov: 13
Celotno besedilo (880,89 KB)
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6. Three-Phase load current reconstruction using singleshunt current measurement and modified vector modulation for three-level DC-AC converter : doctoral dissertationHaris Kovačević, 2022, doktorska disertacija Opis: This doctoral thesis focuses on the development of Space Vector Modulation (SVM) techniques adjusted for single-shunt current measurement and applied to the three-level three-phase voltage source inverter. Based on the single-shunt current measurement, three-phase load currents are then reconstructed.
An overview of existing multilevel topologies and their main operating principles is provided within the thesis. To evaluate proposed SVM techniques adjusted for single-shunt current measurement, a three-level three-phase diode clamped voltage source inverter topology is selected. The main advantages of the selected topology are high efficiency, reduced semiconductor stress, the low capacitance of DC-link capacitors, etc. To reconstruct the three-phase load currents, a single-shunt is positioned inside the middle branch of the DC-link.
An overview of existing modulation techniques for two-level and multilevel inverters is provided within the thesis. To reconstruct three-phase load currents, three SVM methods are proposed within the thesis. Due to the lack of a current measurement window, while the voltage vector is positioned near sector or region boundary areas, additional modifications are required. The first SVM method shifts the SVM signals to ensure the minimum current measurement window needed for measurement with minimum additional vector injection. Such an approach ensures the high modulation index values greater than 0.8 with the smallest current ripple due to the SVM signal symmetry. The second method intentionally injects the colinear voltage vector into the existing vector combination to ensure the minimum time window required for current measurement. As a drawback, a smaller modulation index compared to the first method can be achieved. As an advantage, a very low modulation index of less than 0.2 can be achieved. The third method simplifies the second method by using a single SVM pattern. Such a method can be used only for very low modulation indexes and can be applied for two-level and three-level inverters.
The proposed SVM methods are implemented within the Digital Signal Processor (DSP). Experimental results confirm the proper operation of the proposed methods applied to the three-level diode clamped voltage source inverter.
Ključne besede: single-shunt, three-level inverter, SVM modification, current reconstruction, vector injection
Objavljeno v DKUM: 09.03.2023; Ogledov: 396; Prenosov: 54
Celotno besedilo (12,21 MB) |
7. Foreign insolvent debtor : some essential questions a creditor is facing in international collective insolvency proceedingsJorg Sladič, 2012, izvirni znanstveni članek Opis: Creditors in international trade are often faced with issues of an insolvent foreign debtor who often has property and assets in several states. In such a case creditors are faced with difficulties of international collective insolvency proceedings. The introductory parts of the article examines the standard questions like the question of a single, universal property of an individual or legal person and on the other hand the principles of territoriality and universality in public international law as far as the effects of foreign collective insolvency proceedings are concerned. The article then deals with issues of the centre of main interests as the point of contact and issues opened with the application of the lex concursus.
Ključne besede: private international law, insolvency law, principle of territoriality, principle of universality, principle of single universal assets and property, recognition of decisions of foreign courts rendered in collective insolvency proceedings, recognition of effects of a foreign collective insolvency proceedings, centre of main interests
Objavljeno v DKUM: 01.08.2018; Ogledov: 1079; Prenosov: 54
Celotno besedilo (235,44 KB) |
8. Numerical modeling of floating prefabricated vertical drains in layered soilIkhya Ikhya, Helmut Schweiger, 2012, izvirni znanstveni članek Opis: This paper presents a comparison of field measurements and a numerical model of settlements based on the construction of an embankment on soft soil for the Cirebon Power Plant Project in Indonesia, where prefabricated vertical drains (PVDs) were installed. In the numerical model, floating PVDs in two soil layers for two- and one-way drainage conditions are examined in order to determine the optimum penetration depth. In this study, good agreement between the field measurements of the settlements and the numerical prediction could be achieved. An interesting result of this study is that the differences in the stiffness and/or the permeability in the unimproved area below the PVD tip have a significant influence on the optimum penetration depth (L/H) in the two-soil-layer condition. The numerical study showed that it is possible to use floating PVDs in single drainage conditions if the second layer is stiffer and/or more permeable than the first layer.
Ključne besede: two soil layers, floating prefabricated vertical drain, double and single drainage, numerical model, soft clay, consolidation
Objavljeno v DKUM: 13.06.2018; Ogledov: 1247; Prenosov: 93
Celotno besedilo (727,36 KB)
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9. Advantages and disadvantages of the single European patentKlara Glazer, 2015, izvirni znanstveni članek Opis: In February 2013, the European Union successfully completed more than 30 years of negotiations and formally signed an agreement establishing a single European patent. The agreement brought about a more competitive patent law compared with that in the United States and Japan. The agreement resulted in a number of advantages, especially for small and medium-sized enterprises, such as the reduction of costs by as much as 80%, simplification of procedures, and the adoption of the Unified Patent Court. With the new unitary patent, intellectual property will grow in importance. Yet experts warn that the new patent results in new forms of unwanted behavior, such as forum shopping and the emergence of patent trolls. This study presents both sides-the pros and cons-to predict the effects on business and cover the widest possible range of experts, providing their views on the topic.
Ključne besede: Single European patent, single patent court, reduce costs, patent trolls, simplified procedures, forum shopping, European Union
Objavljeno v DKUM: 03.11.2017; Ogledov: 1560; Prenosov: 169
Celotno besedilo (312,36 KB)
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