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1.
Detection of technical errors and construction optimization for custom tissue arrays at transplanting and casting
Miha Munda, 2018, izvirni znanstveni članek

Ključne besede: tissue arrays, construction problems, optimization, histology
Objavljeno v DKUM: 05.04.2024; Ogledov: 140; Prenosov: 0
.pdf Celotno besedilo (227,21 KB)
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2.
Optimal positioning of mobile cranes on construction sites using nonlinear programming with discontinuous derivatives
Matjaž Hozjan, Uroš Klanšek, 2023, izvirni znanstveni članek

Opis: Mobile cranes represent conventional construction machinery that is indispensable for the erection of most prefabricated buildings, especially those containing heavy components. However, it is also common knowledge that the engagement of these machines has a significant influence on the environment, various social aspects of the construction process, and its economic benefits. Optimal positioning of the mobile crane on the construction site, primarily driven by the contractor’s interest to perform assembly operations with expensive machinery as effectively as possible, considerably reduces not only the costs of engaging such a machine but indirectly also its negative impacts on construction sustainability. This paper discusses an exact nonlinear model for the optimization task. The optimization model consists of a cost objective function that is subject to various duration and positioning constraints for the mobile crane, including bounds on its degrees of freedom of movement and stop positions. Because the model formulation includes discontinuous and non-smooth expressions, nonlinear programming with discontinuous derivatives (DNLP) was employed to ensure the optimal solution was reached. The model provides the mobile crane operator with exact key information that enables the complete and optimal assembly of the building structure under consideration. Additionally, the information gained on the optimal distribution of the mobile crane rental period to assembly operations allows for a detailed duration analysis of the entire process of building structure erection, which can be used for its further improvement. An application example is given in this study to demonstrate the advantages of the proposed approach.
Ključne besede: construction sustainability, mobile crane, nonlinear programming with discontinuous derivatives, optimization, positioning
Objavljeno v DKUM: 18.12.2023; Ogledov: 302; Prenosov: 8
.pdf Datoteka (877,26 KB)
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3.
A review of energy-efficient and sustainable construction scheduling supported with optimization tools
Borna Dasović, Uroš Klanšek, 2022, pregledni znanstveni članek

Opis: This article reviews the accomplishments of studies in which optimization tools were used to develop energy-efficient and sustainable construction schedules. With the increase in global awareness of environmental issues, the construction industry has been forced to explore innovative techniques to make the building process more energy-efficient and sustainable. Project managers can use optimization tools in their scheduling procedures to address these issues in the early stages of the project. Therefore, this paper examines different optimization-based construction scheduling methods and their impact on schedule energy efficiency and the three key sustainability goals: economic viability, social equity, and environmental protection. Such a review has not yet been conducted to the best of our knowledge. This research aims to fill the gap and contribute to understanding advanced optimization tools that can pave the way to energy-efficient and sustainable scheduling practices. After a brief introduction, the background of optimization-based construction scheduling techniques that aim to improve construction management and incorporate these aspects into the decision-making process is explained. Then, these approaches are addressed in detail. It is determined for each study whether it adopted energy efficiency goals and which sustainability dimensions it considered within the proposed optimization model. The results of this study indicate a wide heuristic algorithms application for complex scheduling problems. Meanwhile, mathematical programming is still quite unexplored, especially methods that utilize algebraic modeling languages. This study provides a foundation for further research by addressing the current reach in development and possible knowledge gaps that could be researched in future studies. The paper also discusses the advantages and limitations of different approaches and illustrates the potential for utilizing these methods. Supported by the main review findings, conclusions and recommendations for further research are provided.
Ključne besede: construction, project management, optimization tools, scheduling, sustainability, energy efficiency
Objavljeno v DKUM: 26.09.2023; Ogledov: 317; Prenosov: 13
.pdf Celotno besedilo (1,20 MB)
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4.
Potential of using waste materials in flexible pavement structures identified by optimization design approach
Primož Jelušič, Süleyman Gücek, Bojan Žlender, Cahit Gürer, Rok Varga, Tamara Bračko, Murat V. Taciroğlu, Burak E. Korkmaz, Şule Yarcı, Borut Macuh, 2023, izvirni znanstveni članek

Opis: This paper presents the design of geosynthetic reinforced flexible pavements and their modification by incorporating waste materials into bonded and unbonded layers of the pavement structure. The optimal design of flexible pavements was achieved by minimizing the construction cost of the pavement. The incorporation of waste materials into the pavement structure affects the material properties. Therefore, along with the traffic load, the effects of the material properties of the asphalt concrete, base layer, sub-base layer, and subgrade were analyzed in terms of pavement structure costs and CO2 emissions of materials used in pavement construction. In addition, a comparison was made between pavements with and without geosynthetic reinforcement in terms of design, optimum construction cost, and CO2 emissions. The use of geosynthetics is even more effective in pavement structures that contain waste materials in an unbound layer, both in terms of cost and CO2 emissions. The minimum value of the California Bearing Ratio of the subgrade was determined at which the use of geosynthetic reinforcement for pavement structure with and without the inclusion of waste materials is economically and sustainably justified. The use of geosynthetics could result in a 15% reduction in pavement structure cost and a 9% reduction in CO2 emissions due to the reduced thickness of unbound layers. In addition, reducing the CBR of the unbound layer from 100% to 30% due to the inclusion of waste materials implies a cost increase of up to 13%. While the present study is based on an empirical pavement design method in which pavement thickness is limited by the pavement thickness index, the same minimum thicknesses are obtained in the optimization process regardless of whether the objective function is the minimum construction cost or minimum CO2 emissions.
Ključne besede: pavement design, waste materials, optimization, minimum construction cost, CO2 emissions, geosynthetics, waste management
Objavljeno v DKUM: 18.09.2023; Ogledov: 526; Prenosov: 30
.pdf Celotno besedilo (6,20 MB)
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5.
Planning and construction of the lifting and towing device of the autonomous mobile robot MiR 100 for the delivery of transport trolleys in intralogistics
Tone Lerher, Aleš Belšak, Rok Skerbiš, Jure Tumpej, Žiga Volavšek, Domen Stamenov, Marko Motaln, 2022, objavljeni znanstveni prispevek na konferenci

Opis: Intralogistics is a very important area in warehousing and production for managing the flow of materials and informational flow. In recent years, automation and especially robotisation have had a major impact on throughput performance in intralogistics. Especially important is the transport of materials and products based on automated guided vehicles (AGVs) and autonomous mobile robots (AMRs) with different top modules, such as the lifting and towing device. In this paper, planning and construction of the lifting and towing device of the autonomous mobile robot MiR 100 for the delivery of transport trolleys in intralogistics is presented. Using the engineering design methods, a new design of the lifting and towing device has been proposed and evaluated.
Ključne besede: intralogistics, material handling systems, automation and robotisation, planning and construction, lifting and towing mechanism, simulation and animation
Objavljeno v DKUM: 15.03.2023; Ogledov: 525; Prenosov: 70
.pdf Celotno besedilo (1,45 MB)

6.
Engineering properties of tropical clay and bentonite modified with sawdust
Isaac I. Akinwumi, Oluwapelumi O. Ojuri, Adebanji S. Ogbiye, Colin A. Booth, 2017, izvirni znanstveni članek

Opis: Construction engineers typically avoid the use of expansive soils as construction materials because they are usually difficult to work on and can cause structural failure. This research work investigates how the application of sawdust to tropical clay and bentonite influences their geotechnical properties in order to determine their suitability for use as landfill-liner materials for the effective containment of toxic substances from landfills. X-ray diffractometry, X-ray fluorescence spectroscopy and scanning electron microscopy were used to determine the mineralogical composition, oxide composition and microstructure, respectively, of the clay and the bentonite. A series of laboratory tests were conducted to determine the specific gravity, Atterberg limits, compaction, unconfined compressive strength and permeability characteristics of the clay and the bentonite for varying proportions of sawdust application. Generally, increasing the percentage of sawdust caused a reduction in its specific gravity, maximum dry unit weight and unconfined compressive strength, while it caused an increase in the optimum moisture content and permeability of the modified clay and bentonite. The clay and bentonite both have a sufficiently low permeability that satisfies the hydraulic conductivity requirement for use as clay liners. Eight percent sawdust application to a clay having similar properties as that in this study is recommended as an economic way of modifying it – with the potential of improving its adsorbent property – for use in landfill-liner systems in order to prevent the toxic substances leaching from the landfills, thereby protecting the environment and public health.
Ključne besede: geotechnical properties, hydraulic barrier, landfill, construction, soil improvement, sustainability
Objavljeno v DKUM: 18.06.2018; Ogledov: 1006; Prenosov: 152
.pdf Celotno besedilo (766,16 KB)
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7.
The degree of deterioration of the tunnels of the Prague Metro based on a monitoring assessment
Ivan Vaníček, Martin Vaníček, 2007, izvirni znanstveni članek

Opis: Understanding the ageing of structures is a very important issue from the point of view of assessing the risk inherent in those structures. Geotechnical structures, of course, have their own specific risks. This paper is focused on the tunnels of the Prague Metro, looked at from various aspects, i.e., geology, construction systems, and the influence of flooding. The section of the tunnels that was selected for monitoring is one of the most affected, and has a large system of cracked segments. However, even for this affected section the monitoring systems, based on macro- and micro-approaches, showed no significant deterioration was taking place. Nevertheless, for long-term monitoring a wireless system for data collection and transfer was installed and implemented. The results so far have been very positive.
Ključne besede: tunnel, metro, deterioration, ageing, geology, construction, monitoring assessment, MEMS, geophysical, wireless data transfer, metro flooding
Objavljeno v DKUM: 18.05.2018; Ogledov: 1230; Prenosov: 60
.pdf Celotno besedilo (1,21 MB)
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8.
Back analysis of time-dependet displacement at the Trojane tunnel construction
Jakob Likar, 2004, izvirni znanstveni članek

Opis: The 2,900-metre double tube tunnel of Trojane forms part of the highway section between Celje and Ljubljana and part of the highway road system connecting Lendava and Koper with adjacent roads. The construction of this section, which is of special importance for the Republic Slovenia, has been going on for almost ten years. The highway near Trojane where the tunnel is located, lies on a hilly terrain composed of Permian-carboniferous rocks, which are tectonically badly damaged in some places and marked with broad fault zones, containing tectonically remoulded soil of low strength in terms of deformability properties. Even though the amount of waters coming from the hills during the excavation of the tunnel was relatively small, this water, in combination with extremely damaged weak rock caused the increase of deformations at the construction site. Geological and geotechnical surveying with geometric monitoring and the analyses of stress and deformation changes in the surrounding rocks and support elements were critical in assessing the actual weak-rock conditions during the course of construction. Since the analyses of deformation processes, which had been modelled with PLAXIS 3D TUNNEL PROGRAM, showed great impact on permanent stability of the tunnel, special care was paid to rheological changes in the surrounding rocks and combined in-built support elements. 3D back analyses with SOFT-SOIL-CREEP (SSC) constitutive model, which takes into account rheological phenomena, were carried out. The calculations of primary and secondary stresses and deformations were made for two characteristic areas and determined on the basis of realistic geological mapping during tunnel construction. The first area represented typical rocks of the Trojane tunnel, i.e. shales and siltstone, while the second one was a tectonic zone where geological and geotechnical conditions during excavation were less favourable. The results of back analyses used provided an acceptable possibility for estimating the stress-strain variation during construction as well as an appropriate basis for analysing vertical displacements at the tunnel roof. The calculation results show good correlation with field measurements.
Ključne besede: tunnels, construction, permain-carboniferous rocks, geological-geotechnical conditions, tunnel support, Trojane tunnel, finite element method, costitutive models, back analyses, field mesurement, time dependent analysis
Objavljeno v DKUM: 15.05.2018; Ogledov: 1227; Prenosov: 64
.pdf Celotno besedilo (868,88 KB)
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9.
Survey of accomplishments in BIM implementation in Croatia, the Czech Republic, Germany, and Slovenia
Mario Galić, Vaclav Venkrbec, Franziska Chmelik, Immo Feine, Zoran Pučko, Uroš Klanšek, 2017, izvirni znanstveni članek

Opis: Building information modelling (BIM) may currently be considered the fastest developing concept in the field of construction management, aiming to become a global standard. Although the roots of the concept date back to the mid-1970s, some original expectations are still missing from its implementation. There has been a time gap between its theoretical and practical implementations. While the simultaneous development of information technologies is one reason for the implementation delay, other reasons remain unclear. This paper analyzes the gaps between theoretical and practical BIM application, as well as the legislation regarding BIM implementation in four countries (in alphabetical order: Croatia, the Czech Republic, Germany, and Slovenia). The paper additionally presents a survey of current practical BIM applications as well as general and theoretical feedback from construction projects that implemented BIM.
Ključne besede: construction industry, implementation, project management, survey
Objavljeno v DKUM: 12.01.2018; Ogledov: 1391; Prenosov: 343
.pdf Celotno besedilo (694,12 KB)
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10.
Heuristics for NP-hard optimization problems : simpler is better !?
Janez Žerovnik, 2015, izvirni znanstveni članek

Opis: We provide several examples showing that local search, the most basic metaheuristics, may be a very competitive choice for solving computationally hard optimization problems. In addition, generation of starting solutions by greedy heuristics should be at least considered as one of very natural possibilities. In this critical survey, selected examples discussed include the traveling salesman, the resource-constrained project scheduling, the channel assignment, and computation of bounds for the Shannon capacity.
Ključne besede: optimization, metaheuristics, local search, greedy construction, traveling salesman problem
Objavljeno v DKUM: 17.11.2017; Ogledov: 1627; Prenosov: 291
.pdf Celotno besedilo (709,68 KB)
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