On cubic polyhedral graphs with prescribed adjacency properties of their faces

AbstractWe consider classes of cubic polyhedral graphs whose non-q-gonal faces are adjacent to q-gonal faces only. Structural properties of some classes of such graphs are described. For q = 5 we show that all the graphs in this class are cyclically 4-edge-connected. Some cyclically 4edge-connected and cyclically 5-edge-connected non-Hamiltonian members from this class are presented

Authentication, authorization and accounting of packet oriented transmission in mobile networks

Práca sa zaoberá princípmi autentizácie, autorizácie a účtovania v paketových mobilných sieťach. V práci je popísaný vývoj mobilných sietí štvrtej generácie, architektúra týchto sietí a funkcie jednotlivých častí siete. Ďalej sa práca venuje opisu funkcií riadenia zásad a účtovania. Detailne sú vysvetlené postupy, ktoré zaisťujú bezpečnosť používateľa v sieti, procesy pri jeho autentizácii a autorizácii. Práca tiež popisuje postupy pri účtovaní v mobilnej sieti a všetky možností účtovania v systéme experimentálnej mobilnej siete.Concern of this thesis is priciples of authentication, authorisation and charging in packet oriented mobile networks. In thesis is description of evolution of fourth generation mobile networks, architecture of these networks and function of each part in network. Next part of the thesis decribes functions of policy and charging control. Procedures, which provide security of user in network, authentication and authorization of user, are explained in detail. Thesis describes procedures of charging in mobile networks and all options of charging in system of experimental mobile network.

Effect of the weight reduction of a gear wheel on modal characteristics

The paper deals with the influence of gear weight reduction on its modal properties. The aim of the paper is to use the simulation tools to introduce the dependence of natural frequencies on the change in the shape of the gear, which is reflected in the change in weight. At the beginning of the paper, the theory and experimental bases of vibration testing and analysis are introduced to understand the principles of modal parameter specification. Verification of the boundary conditions used in the simulation was performed using the experimental method and it is described in the next part of the article. Tests confirmed the consistency of the values achieved by both approaches. Thus, the same boundary conditions could be used to specify the dependence of natural frequencies on the change in the geometry of the gear (which is associated with weight reduction). Numerical analysis was performed by FEM analysis using PTC Creo software. Experimental modal analysis was performed using a PULSE measurement system.Ministry of Education, Science, Research and Sport of SR [KEGA 007TUKE-4/2018, VEGA 1/0440/18

Study of the sound absorption properties of 3D-printed open-porous ABS material structures

Noise pollution is a negative factor that affects our environment. It is, therefore, necessary to take appropriate measures to minimize it. This article deals with the sound absorption properties of open-porous Acrylonitrile Butadiene Styrene (ABS) material structures that were produced using 3D printing technology. The material's ability to damp sound was evaluated based on the normal incidence sound absorption coefficient and the noise reduction coefficient, which were experimentally measured by the transfer function method using an acoustic impedance tube. The different factors that affect the sound absorption behavior of the studied ABS specimens are presented in this work. In this study, it was discovered that the sound absorption properties of the tested ABS samples are significantly influenced by many factors, namely by the type of 3D-printed, open-porous material structure, the excitation frequency, the sample thickness, and the air gap size behind the sound-absorbing materials inside the acoustic impedance tube. © 2020 by the authors.Ministry of Education, Science, Research, and Sport of the Slovak Republic [KEGA 007TUKE-4/2018, APVV-19-0550]; European Regional Development Fund in the Research Centre of Advanced Mechatronic Systems within the Operational Programme Research, Development, and Education [CZ.02.1.01/0.0/0.0/16_019/0000867

Terrestrial laser scanning – effective technology for creating building information models

Building information modeling is a process for creating and managing information on a construction project across the project lifecycle. The lifecycle of building includes also a stage of reconstruction and technology of terrestrial laser scanning is an effective method to create 3D building information models of the real state. Laser Scanning is a non-contact technology that captures the shape of physical objects and gives exact representation of the building geometry. Current scanning technology has the ability to send out thousands of beams per second, resulting in a ‘point cloud’ of data. This study offers an overview of the survey planning stages, field operation, processing of point cloud data and the possibility to integrate data into the building information modeling

Impact of management decisions based on managerial competencies and skills developed trough BIM technology on performance of construction enterprises

Management of construction enterprises requires experience or managerial competencies. To achieve successful results of construction enterprises and projects, for example as cost reducing, increasing revenues, shortening construction time, both are necessary. Building information modeling represents technology for developing of managerial skills for managers. Main aim of research is to analyze and quantify the management decisions based on managerial competencies developed through building information modeling on results of construction enterprises in Slovakia. Cost reducing, increasing of revenues and shortening construction time are main monitored by enterprise and project results. Research hypotheses are based on the assumption that building information modeling has a positive impact on development of managerial competencies and skills and manager’s t decisions

Influence of domain walls thickness, density and alignment on Barkhausen noise emission in low alloyed steels

This study deals with the characterization of low alloyed steels of diferent yield strengths (varying in the range of 235–1100 MPa) via Barkhausen noise emission. The study investigates the potential of this technique to distinguish among the low alloyed steels and all signifcant aspects contributing to Barkhausen noise, such as the residual stress state, microstructure expressed in terms of dislocation density, grain size, prevailing phase, as well as associated aspects of the domain wall substructure (domain wall thickness, energy, their spacing and density in the matrix). Barkhausen noise in the rolling as well as transversal direction grows along with the yield strength (up to 500 MPa) and the corresponding grain refnement of ferrite. As soon as the martensite transformation occurs in a high strength matrix, this evolution saturates, and remarkable magnetic anisotropy is developed when Barkhausen noise in the transversal direction grows at the expense of the rolling direction. The contribution of residual stresses as well as the domain wall thickness is only minor, and the evolution of Barkhausen noise is driven by the density of the domain walls and their realignment.Web of Science131art. no. 568

Mechanical vibration damping and compression properties of a lattice structure

The development of additive technology has made it possible to produce metamaterials with a regularly recurring structure, the properties of which can be controlled, predicted, and purposefully implemented into the core of components used in various industries. Therefore, knowing the properties and behavior of these structures is a very important aspect in their application in real practice from the aspects of safety and operational reliability. This article deals with the effect of cell size and volume ratio of a body‐centered cubic (BCC) lattice structure made from acrylonitrile butadiene styrene (ABS) plastic on mechanical vibration damping and compression properties. The samples were produced in three sizes of a basic cell and three volume ratios by the fused deposition modeling (FDM) technique. Vibration damping properties of the tested 3D‐printed ABS samples were investigated under harmonic excitation at three employed inertial masses. The metamaterial behavior and response under compressive loading were studied under a uniaxial full range (up to failure) quasi‐static compression test. Based on the experimental data, a correlation between the investigated ABS samplesʹ stiffness evaluated through both compressive stress and mechanical vibration damping can be found. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education, Science, Research, and Sport of the Slovak Republic [APVV-19-0550, KEGA 005TUKE-4/2021]; European Regional Development Fund in the Research Centre of Advanced Mechatronic Systems project within the Operational Programme Research, Development, and Education [CZ.02.1.01/0.0/0.0/16_019/0000867]CZ.02.1.01/0.0/0.0/16_019/0000867; Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky: APVV‐ 19‐0550; Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGA: 005TUKE‐4/202

Polypyrrole nanotubes decorated with gold particles applied for construction of enzymatic bioanodes and biocathodes

The novel composites of gold nanoparticles and polypyrrole nanotubes (Au-x@PNT) were prepared and used as a platform for fabrication of bioelectrode interfaces. Changing the conditions of composite preparation caused variations in a gold architecture, electrical conductivity and a biocompatibility. These features could be easily adjusted by setting up a proper fabrication protocol. The Au-x@PNT-chitosan matrix was utilized for fabrication of bioelectrode interfaces with physisorbed oxidoreductases. Biocatalytic activity of such physisorbed fructose dehydrogenase (FDH), laccase (Lac) and bilirubin oxidase (BOD) was investigated with biocatalytic current density up to j = 2.45 mA cm(-2) obtained for a bioanode based on direct electron transfer of FDH. Performance of biocathodes with immobilized Lac and BOD showed current density up to 232 mu A cm(-2) in presence of a redox mediator.NPRP grant from the Qatar National Research Fund (Qatar Foundation) [6-381-1-078

EFFECT OF ECOLOGICAL ENERGY CARRIERS ON FLOW CHARACTERISTICS OF TRACTOR HYDRAULIC PUMP

This paper deals with the effect of ecological energy carrier on flow characteristics of a hydraulic pump. A hydraulic oil MOL Farm UTTO Synt was used as an ecological energy carrier. After completing 900 engine hours, the flow efficiency of the hydraulic pump decreased by Δηpr = 1.197 %. Oil samples were taken from the agricultural tractor Zetor Forterra 114 41. These samples were subjected to an IR spectroscopy analysis in an accredited laboratory WearCheck, Hungary. The following oil properties were examined: kinematic viscosity at 40 °C, viscosity index, silicium and ferrum content