11. Financial aspects of a seismic base isolation system for a steel high-rack structureVojko Kilar, Simon Petrovčič, Simon Šilih, David Koren, 2013, izvirni znanstveni članek Opis: The paper deals with the effects and costs of implementing a base isolation system for the mitigation of the seismic risk of an existing steel rack structure. Different realistic distributions of the payload mass and occupancy levels, which form different plan asymmetric variants, have been analysed. The results obtained by the pushover analysis (N2 method) are presented as top floor envelopes and as plastic hinge damage patterns. In the presented cost study, the cost of the implementation of the proposed base isolation system is compared with the estimated costs of structural repairs to the damaged structural members of the superstructure, as well as with estimated expenses of the downtime period. The results have shown that base isolation is, in general, not economically feasible for lower ground motion intensities, whereas it could be of great benefit in the case of moderate and high intensities, especially if the downtime period is taken into account. Ključne besede: rack structures, seismic behaviour, base isolation, cost efficiency, mass eccentricity, pushover analysis Objavljeno: 07.08.2017; Ogledov: 40; Prenosov: 2 Polno besedilo (999,00 KB) |
12. Application of "Einstein's riddle" in solving construction machine allocation problemsBorna Dasović, Marko Čorak, Mario Galić, Uroš Klanšek, 2016, izvirni znanstveni članek Opis: “Einstein’s riddle” is a popular example of constraints satisfaction problem. Since its introduction, different forms and variations of the riddle have been presented. Regardless of the variant of the riddle, its solution is considered a tough challenge for humans. Researchers have developed and are still developing mathematical models, as well as computational simulation models for solving it. In this article, the authors have modified a previously published mathematical model and developed a computational spreadsheet model for solving the riddle, which provides a unique solution for the riddle. The model was also tested in a small and medium-scaled form for solving constraint satisfaction problems regarding the allocation of construction machines. The authors have also highlighted the model’s limitations for solving such problems and made suggestions regarding necessary modifications in the model to solve more complex problems in the same domain. Ključne besede: Einstein's riddle, zebra riddle, construction, machine allocation, combinatorial optimization Objavljeno: 02.08.2017; Ogledov: 78; Prenosov: 2 Polno besedilo (437,45 KB) |
13. Analysis of neural network responses in calibration of microsimulation traffic modelIrena Ištoka Otković, Damir Varevac, Matjaž Šraml, 2015, izvirni znanstveni članek Opis: 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. Ključne besede: microsimulation traffic models, calibration, response of neural networks, traveling time, queue parameters Objavljeno: 02.08.2017; Ogledov: 59; Prenosov: 2 Polno besedilo (1,07 MB) |
14. The different methods of displacement monitoring at loading tests of bridges or different structuresBoštjan Kovačič, Rok Kamnik, Andrii Bieliatynskyi, 2016, objavljeni znanstveni prispevek na konferenci Opis: By measuring the displacements and deformations at different structures we deal in the Faculty of Civil Engineering, transportation Engineering and Architecture in University of Maribor for about 20 years. At that time we measured over 600 structures. Most loading tests of bridges and Viaducts were made. The measurements of movements needed to be as precise and accurate as possible. To do that laboratory test of instruments were made to see which instrument gives us reliable results. Displacements can be determined by geodetic and physical methods, depends of the construction. The use of geodetic methods are still preferable. In the paper the measurements with the total station, the level and rotation level, photogrammetry and solutions on the field by physical methods with inductive transducers are presented. We need to measure displacements as quick as possible but efficiently because we can not repeat the measurements under the same conditions. Also the surveying on the bridge and in the lab with the comparison of methods is presented under the different hard terrain conditions - water beneath the construction, big height of the structure, unapproachability, large span structures. Ključne besede: bridges, measurements, strain gauge, load test, deformation, strain, signal processing Objavljeno: 02.08.2017; Ogledov: 56; Prenosov: 3 Polno besedilo (3,15 MB) |
15. Risk assesment of an urban aquifer based on environmental tracersBranka Trček, Primož Auersperger, Albrecht Leis, Jürgen Sültenfuss, 2013, izvirni znanstveni članek Opis: Groundwater from a Pleistocene sandy-gravel aquifer is a drinking water resource for the Union brewery, located near the centre of Ljubljana (Slovenia). A large part of the aquifer recharge area is highly urbanized, which represents a great risk for the groundwater quality assurance. The groundwater dating techniques were used to study the contamination risk of this drinking-water resource. The application of chlorofluorocarbons (CFCs), sulphur hexafluoride (SF6) and tritium-helium-3 (3H-3He) age indicator was tested, as they haven’t been used in Slovene urban areas so far. The results reflect that the 3H-3He dating technique is the most suitable for a groundwater age determination in the study urban aquifer, since SF6 and particularly CFCs concentrations could be affected by the local contaminations. They indicated that average groundwater residence times range from 10 to 30 years. Boreholes that are more distant from the Šišenski hrib hill are more vulnerable to contamination due to flow of young groundwater from a direction of the main aquifer, which is exposed to the urban pollution. The presented results were supplemented with chemical investigations of groundwater organic pollutants. An unknown trace organic pollutant with a base ion mass-to-charge ratio 147 was put into focus. Its identification based on chromatographic separation and a mass spectrometric detection with GC-MS, LC-MS and LC-TOF MS techniques. The newly detected trace organic pollutant in sampled groundwater represents together with the 3H and 3He data a new technique to study the flow paths and contaminant transport in the urban aquifer in both, the lateral and vertical directions. Ključne besede: urban area, intergranular aquifer, contamination risk, environmental tracers Objavljeno: 24.07.2017; Ogledov: 63; Prenosov: 1 Polno besedilo (502,53 KB) |
16. On vulnerability measures of networksRija Erveš, Darja Rupnik Poklukar, Janez Žerovnik, 2013, objavljeni znanstveni prispevek na konferenci Opis: As links and nodes of interconnection networks are exposed to failures, one of the most important features of a practical networks design is fault tolerance. Vulnerability measures of communication networks are discussed including the connectivities, fault diameters, and measures based on Hosoya- Wiener polynomial. An upper bound for the edge fault diameter of product graphs is proved. Ključne besede: discrete optimization, communication network, vulnerability Objavljeno: 21.07.2017; Ogledov: 60; Prenosov: 2 Polno besedilo (189,03 KB) |
17. Quantifying soil complexity using network models of soil porous structureMarko Samec, A. Santiago, J. P. Cardenas, R. M. Benito, A. M. Tarquis, Sacha Jon Mooney, Dean Korošak, 2013, izvirni znanstveni članek Opis: This paper describes an investigation into the properties of spatially embedded complex networks representing the porous architecture of soil systems. We suggest an approach to quantify the complexity of soil pore structure based on the node-node link correlation properties of the networks. We show that the complexity depends on the strength of spatial embedding of the network and that this is related to the transition from a non-compact to compact phase of the network. Ključne besede: soil complexity, soil pore networks, complex systems Objavljeno: 21.07.2017; Ogledov: 41; Prenosov: 0 Polno besedilo (3,85 MB) |
18. Drago Pupavac: Logistički operator - čimbenik dinamičke optimalizacije globalnih logističkih lanacaRatko Zelenika, 2007, recenzija, prikaz knjige, kritika Opis: Temeljni cilj znanstvenog istraživanja ove doktorske disertacije jest učinak logističkih operatora u funkciji snižavanja ukupnih troškova globalnih logističkih lanaca. Da bi se cilj istraživanja i ostvario u odgovarajućim kombinacija korištene su brojne znanstvene metode od kojih se izdvajaju metoda anketiranja, metoda dinamičkog programiranja i metoda mješovitog cjelobrojnog programiranja. Zahvaljujući primijenjenoj znanstvenoj metodologiji mr.sc. Drago Pupavac uspješno je interpretirao dobivene rezultate dokazujući da modelski pristup odabira aktivnih sudionika logističkoga lanca logističkom operatoru daje uvid u sposobnosti potencijalne logističke mreže, opisuje sposobnosti pojedinih izvršitelja u logističkoj mreži, specificira logističke aktivnosti svakog pojedinog logističkog pothvata, daje informacije o troškovima izvršavanja specificiranih logističkih aktivnosti, daje neograničene mogućnosti procjene promjene strukture logističkog lanca, te dokazuje da je logistički operator stanju optimalizirati logističke lance i braniti ih od promjenjivosti i nepostojanosti potražnje. Ključne besede: logistični operater, dinamična optimizacija, globalne logistične verige logistika, transport, promet Objavljeno: 18.07.2017; Ogledov: 65; Prenosov: 1 Polno besedilo (263,66 KB) |
19. Mixed-integer nonlinear programming based optimal time scheduling of construction projects under nonconvex costsRok Cajzek, Uroš Klanšek, 2016, izvirni znanstveni članek Opis: Optimal project scheduling under nonconvex time-cost relations represents a challenging problem in construction management. The nonconvex time-cost relations may appear in a construction project when several different duration options are available for its activities due to alternative technological processes enabled for their realization or wide accessibility of production resources. The source of nonconvexity of the project scheduling optimization problem can also be the project penalty- or bonus-duration relations arranged within the construction contract. The aim of this paper is to present the mixed-integer nonlinear programming (MINLP) based optimal time scheduling of construction projects under nonconvex costs. For this purpose, the MINLP model was developed and applied. A numerical example from literature and an example of construction project time-cost trade-off analysis under practical nonconvex penalty function are given in the paper to demonstrate advantages of MINLP optimization. The example from literature first presented the capability of the MINLP approach to obtain the optimal solution for difficult, highly combinatorial nonconvex discrete project scheduling problem. Thereupon, the following example revealed that the optimal project time-cost curve may take very nonuniform shape on account of discrete nature of activity direct cost options and nonconvex relation between project duration and total cost. In this way, the presented study intends to provide practitioners with new information from the field of optimization techniques for project scheduling as well as an alternative view on performance of total cost when project duration is changed. Ključne besede: extreme environments, construction management, discrete optimization, mixed-integer nonlinear programming, nonconvex costs, time scheduling Objavljeno: 12.07.2017; Ogledov: 59; Prenosov: 6 Polno besedilo (807,33 KB) |
20. Analysis of the influence of car-following input parameters on the modelled travelling timeIrena Ištoka Otković, Tomaž Tollazzi, Matjaž Šraml, 2013, kratki znanstveni prispevek Opis: 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. Ključne besede: car-following input parameters, input parameters for the process of calibration, VISSIM Objavljeno: 11.07.2017; Ogledov: 59; Prenosov: 4 Polno besedilo (680,10 KB) |