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1.
Periodic arrays of chiral domains generated from the self-assembly of micropatterned achiral lyotropic chromonic liquid crystal
Geonhyeong Park, Simon Čopar, Ahram Suh, Minyong Yang, Uroš Tkalec, Dong Ki Yoon, 2020, original scientific article

Abstract: Achiral building blocks forming achiral structures is a common occurrence in nature, while chirality emerging spontaneously from an achiral system is usually associated with important scientific phenomena. We report on the spontaneous chiral symmetry-breaking phenomena upon the topographic confinement of achiral lyotropic chromonic liquid crystals in periodically arranged micrometer scale air pillars. The anisotropic fluid arranges into chiral domains that depend on the arrangement and spacing of the pillars. We characterize the resulting domains by polarized optical microscopy, support their reconstruction by numerical calculations, and extend the findings with experiments, which include chiral dopants. Well-controlled and addressed chiral structures will be useful in potential applications like programmable scaffolds for living liquid crystals and as sensors for detecting chirality at the molecular level.
Keywords: physical chemistry, atmospheric chemistry, chromatography, deformation, silicon, symmetry breaking, chiral domains, liquid crystal
Published in DKUM: 03.04.2025; Views: 0; Downloads: 1
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2.
Processing of signals produced by strain gauges in testing measurements of the bridges
Boštjan Kovačič, Rok Kamnik, Andrej Štrukelj, Nikolai Ivanovich Vatin, 2015, published scientific conference contribution

Abstract: Practical example of signal processing from strain gauge, inductive transducer and total station measurements are used to illustrate the features of the bridge load testing measurements. FFT provides accurate representation of physical behavior for static and dynamic signals obtained when loading the bridge. As a reference measurement the signal from inductive transducer was taken. A static part of the load test was also geodetically measured and theoretically calculated. The results are comparable.
Keywords: bridges, measurements, strain gauge, load test, deformation, strain, signal processing
Published in DKUM: 12.07.2023; Views: 445; Downloads: 33
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3.
GNSS monitoring of geologically demanding areas
Boštjan Kovačič, Boško Pribičević, Rok Kamnik, 2016, original scientific article

Abstract: Displacement research using the three-dimensional global navigation satellite system (GNSS) as part of geodetic monitoring is becoming the key investigation for establishing a cause-and-effect relationships model between external natural factors, on the one hand, and the criteria that describes the level of functionality and safety of the observed natural or artificial object, on the other, in cases of motion of an object in space and time. The main objective of the deformation analysis is to confirm the stabilities of the reference points of a geodetic network, which are used to determine the movements of the control points that are stabilized on the observed objects. The assumption about the stabilities of certain reference points must be based on reasonable grounds, underpinned by measurements and proven by numerical methods. This is one part of the results of the deformation analysis when determining the extent of the movements and deformations. To do this a transformation is used in which a comparison is made between the coordinates of the points for two separate epochs. On the basis of the estimated transformation parameters, possible movements can be concluded within the reference points, i.e., on whether the datum parameters have changed. After confirming the stability of the geodetic network the coordinate differences of identical points measured within the different time windows can be determined as displacements and/or deformations of an object. In this paper one viaduct was assessed through geology and tectonic activities and also a load test of the viaduct was performed. The viaduct is in a quite active region, but the load test showed that the bridge response to the load is as expected.
Keywords: geodesy, geotehnics, monitoring, GNSS measurements, geology, deformation analysis, geodetic network
Published in DKUM: 18.06.2018; Views: 1784; Downloads: 81
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4.
Modeling of a geocell-reinforced pavement : an experimental validation
Samo Peter Medved, Bojan Žlender, Stanislav Lenart, Primož Jelušič, 2016, original scientific article

Abstract: This article details how the serviceability of a flexural pavement structure is improved by incorporating the Cellular Confinement System (geocells). For this purpose, two different pavement structures, with and without embedded geocells, were manufactured in a laboratory and an accelerated traffic type of loading was applied. The vertical and horizontal cyclic loads were applied simultaneously to simulate the effect of principal stress rotation. A comparative study between the conventional flexible pavement and the geocell-reinforced flexible pavement is presented. Additionally, numerical models of the laboratory tests were built and the results were compared. The simulation of the experimental tests using the Traffic Load Simulator (TLS) are carried out using the FEM and advanced models that describe the permanent strain behavior of the unbound granular material. The development of permanent deformation within the pavement structure, with and without the geocells, is also presented through the numerical model, which was verified by the experimental results.
Keywords: flexible pavement, reinforcement, geocell, traffic load simulator, permanent deformation, numerical modeling
Published in DKUM: 18.06.2018; Views: 1313; Downloads: 104
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5.
A new method for testing the anti-permeability strength of clay failure under a high water pressure
Fu-wei Jiang, Ming-tang Lei, Xiao-zhen Jiang, 2015, original scientific article

Abstract: It is difficult to judge the failure of clay seepage under a high water pressure.This paper presents a new method to assess clay failure based on the anti-permeability strength, which is the critical water pressure to destroy the clay. An experiment is designed to test the value that avoids the problem of the time-consuming, traditional method to test clay seepage deformation. The experimental system and the process of testing are introduced in this paper. With a self-designed experimental system and method, 18 groups of sample were tested. The results show that the clay thickness and the seepage paths influence the anti-permeability strength. It also indicates that water infiltrates into the clay under the condition that its pressure exceeds a minimum value (P0).
Keywords: clay failure, seepage deformation, anti-permeability strength, high water pressure
Published in DKUM: 15.06.2018; Views: 1410; Downloads: 171
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6.
Analysis of a dilatometer test in over-consolidated sediments, basin of the Duero river, Spain
Félix Escolano Sánchez, Manuel Bueno Aguado, 2015, original scientific article

Abstract: A dilatometer test is a useful method for in-situ geotechnical surveys. It can be compared with the results obtained using a mathematical model. The mathematical model of concentric rings shown in this article is governed by the constitutive equation of the “Hardening Soil Model”. A large number of tests made on the Dueñas Geological Facies, with a consistency ranging from firm clays to soft rocks, are compared to the model results. In this way, the “Hardening Soil Model” parameters are adjusted to the Dueñas Facies materials.
Keywords: Dueñas, geotechnical parameters, hardening soil model, soft rocks and clays deformation
Published in DKUM: 14.06.2018; Views: 1304; Downloads: 103
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7.
A multiscale approach to deformation and fracture of heat-resistant steel under static and cyclic loading
P. O. Maruščak, Denys Baran, Vladimir Gliha, 2013, original scientific article

Abstract: Regularities of static and cyclic deformation, damage and fracture of heat-resistant steel 25Kh1M1F, based on the approaches of physical mesomechanics and 3D interferometry method, are presented in this paper. The applicability of these techniques for different hierarchy levels of deformation was studied. The investigation of scanning microscope photos was conducted for several dissipative structures, fragmentation of the material, localisation of macrodeformation and subsequent failure on macro- and mesolevel. It is shown that the used modern techniques of experimental analysis are very efficient in understanding deformation and damage evolution in materials.
Keywords: fracture, heat-resistant steel, cyclic loading, fatigue, plastic deformation
Published in DKUM: 18.08.2017; Views: 1465; Downloads: 366
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8.
The different methods of displacement monitoring at loading tests of bridges or different structures
Boštjan Kovačič, Rok Kamnik, Andrii Bieliatynskyi, 2016, published scientific conference contribution

Abstract: 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.
Keywords: bridges, measurements, strain gauge, load test, deformation, strain, signal processing
Published in DKUM: 02.08.2017; Views: 1262; Downloads: 354
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9.
Deformation analysis of bridges in exceptional transport in Slovenia
Rok Kamnik, Boštjan Kovačič, Andrej Štrukelj, 2010, other scientific articles

Abstract: In August 1999 an exceptional transportation of two steamers of 666 tonnes was performed from the Port of Koper to the Nuclear power plant in Krško. The transport covered a distance of about 200km and represented one of the largest exceptional transports in Slovenia ever. Finding the best route represented one of the major issues, because the steamers had to cross more than 50 problematic sections and bridges, most of which have not been designed for such heavy loads. It was necessary to load-test almost all bridges on the route to determine whether those bridges need any extra supports or not. Consequently, a logistic operator has an important and indispensable role and becomes a co-modeller of logistic service. A deformation analysis or a polynomial interpolation of vertical displacements could also be used. Therefore, a laboratory load test of a concrete plate was made. The concrete plate was loaded with hydraulic cylinder PZ 100 with extensiometer up to 21kN. Every increase of load by 3kN was measured with Nikon Ser 800 total station.
Keywords: deformation analysis, exceptional transport, bridges, Slovenia
Published in DKUM: 01.06.2017; Views: 1476; Downloads: 307
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10.
Superplastic deformation of an X7093 Al alloy
Srdjan Tadić, Aleksandar Sedmak, Radica Prokić-Cvetković, Abdsalam Eramah, Rebeka Rudolf, 2014, original scientific article

Abstract: We have investigated the superplastic deformation mechanism of a powder-metallurgy, high-zinc X7093 Al alloy. The objective was to examine the rate-controlling mechanisms that govern its superplastic deformation. The investigations were carried out in the temperature range 490–524 °C and strain rates of 4.17 × 10–5 s–1 to 2.1 × 10–2 s–1. The maximum ductility was slightly more than 500 % at 524 °C and 4.2 × 10–4 s–1. The values of the stress exponent (n) and the activation energy (Q) indicated that the deformation is rate-controlled by the climb within the grain-boundary diffusion path. The existence of a temperature-dependent threshold stress was confirmed.
Keywords: superplasticity, Al alloys, deformation mechanisms
Published in DKUM: 23.03.2017; Views: 1349; Downloads: 89
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