Analyzovanie tesniacých vlastností skrutkového spoja s oceľovým tesnením použitím metódy konečných prvkov

This article deals with study of contact pressure/gap distribution on a bolted joint of a hydrostatic transmission. The study was performed via numerical analyses with support of ANSYS a finite element method software package. The main focus in the results evaluation is aimed on evaluation of the contact pressure/gap on the bolted joint after tightening individual bolts and after applying operational loads on the hydrostatic unit. Operational loads in the analyses were represented by applying of an operational pressure into the individual areas of the unit. The operational pressure was applied in two time steps of the Finite Element Method analysis to simulate normal and reverse mode of the hydrostatic transmission. Numerical results were verified through experimental measurements carried out by using FujiFilm tests.Tento článok sa zaoberá skúmaním rozloženia kontaktného tlaku resp. kontaktnej vôle skrutkového spoja hydrostatického prevodníka. Skúmanie týchto ukazovateľov bolo realizované numerickými analýzami s využitím konečno-prvkového softvéru ANSYS Workbench. Cieľom príspevku je vyhodnotenie kontaktného tlaku/vôle skrutkového spoja po uťahovaní jednotlivých skrutiek a po aplikácii prevádzkového zaťaženia hydrostatickej jednotky. Prevádzkové zaťaženie v analýzach predstavovalo aplikáciu prevádzkového tlaku do jednotlivých oblastí jednotky. Pracovný tlak bol aplikovaný v dvoch časových krokoch konečno- prvkovej analýzy, nakoľko bol simulovaný normálny a reverzný chod hydrostatického prevodníka. Numerické výsledky boli následne porovnané s experimentálnymi meraniami, ktoré boli vykonané pomocou FujiFilm testov

Detection and Prediction of a Pair of Unmanned Aircraft Contact

In the current world of increasing density of unmanned aerial vehicle operations in the airspace, there is an enhanced emphasis on their safety due to the potential for mid-air collision, either with another aircraft or with each other. At the same time, unmanned aerial vehicles are also being used in the context of introducing smart technologies into maintenance processes, where there is also a need to prevent a potentially possible conflict when two drones come close together. The paper introduces a mathematical model for tactical prediction of a conflict between a pair of drones. The tactical prediction of drone conflict is intended to alert the drone operator to an immediate potentially dangerous situation. The mathematical simulation in this paper extrapolates the 3D trajectory in the direction of the relative velocity vector of the convergence over the advance time. If the extrapolated trajectory has at least one point in common with the conflict space of the other drone, the conflict is signalled to the drone operator. This model can then be used in practice to simulate flight operations in shared airspace or to develop the currently required rules in selected situations

Time Average Synchronization in Thermoelastic Stress Analysis

AbstractThermoelastic stress analysis is noncontacting technique used to obtain stress field on the material surface by measuring changes of the surface temperature by infrared camera. Roughly 1MPa change in stress state causes a temperature change of 1 mK in steel. Because of extremely small temperature measurement it is necessary to reduce noise. Thermoelastic stress analysis expects adiabatic conditions so that the specimen is usually loaded by cyclic load. Lock-in principle is most frequently method used to extract signal from statistical noise. However, it is necessary to ensure a synchronization link between IR camera and loading machine. In the case of large displacement of the test object it is necessary to be eliminated. In the contribution is presented an algorithm which requires only knowledge of the temporal signal and identification of displacement by using Lock-in technology and time average synchronization to determine infrared field

Influence of imperfections on dynamic properties of oscillating rod

© 2020 Institute of Physics Publishing. All rights reserved. The paper deals with the analysis of the influence of boundary conditions on the dynamic properties of a mechanical system. The steel bar is fixed in one place so that it is inserted under the hydraulic press. The pressure force in the press changes and models the imperfect fixation of the bar. The effect of bond imperfection is evaluated based on rod vibration analysis. This problem is solved computationally, by FEM and the results are compared with experimental measurement

Finite element simulation of tensile test of composite materials manufactured by 3D printing

© 2020 Institute of Physics Publishing. All rights reserved. A principle of 3D printing is based on formation of continuous layers of materials up to a formation of the final shape. Materials for production of given components are composite materials, especially on the basis of so-termed CFRP, CRP, (carbon fibre - so-termed polymers reinforced by carbon fibres). The objective of this paper is to predict the deformation length of carbon/onyx composite laminates using Finite Element Analysis (FEA) and compare with universal testing machine INOVA FU 160 deformation results through the tensile load. Specimen were printed at raster orientation angles of 0°, 45° and 90° to test orientation effects on part strength. 16 ply CFRP specimens with various stacking sequences were analysed for their strength and displacements. A shell model has been established for simulation of the tensile test composite specimen which enables to understand the mechanical strength and strain at failure of the composite materials. The simulations of experiment are provided in FEM program ANSYS and ANSYS/Workbench

ECONOMIC EFFECTIVENESS AND RELIABILITY EVALUATION OF ERGATIC BASE COMPLEX

V súčasnosti okrem technickej spoľahlivosti je veľmi dôležitou aj ekonomická stabilita a efektívnosť leteckých podnikov, resp. ich súčastí. Je v záujme každého prevádzkovateľa, aby jeho technické komplexy ako napr. ergatický bázový komplex boli nie len spoľahlivé, ale aj ekonomicky efektívne, čo nám pomáha si utvoriť celkovú predstavu nie len o kvalite jednotlivých prvkov, ale systému tj. podniku ako celku. Na stanovenie kvality práce so zložitými systémami možno použiť rôzne metódy. Navrhnutá metóda pri vyhodnotení využíva ukazovateľ efektívnosti skúšok spoľahlivosti, ktoré sú súčasťou zavádzania nových zložitých systémov do ergatického bázového komplexu, kedy výstupy skúšok vytvárajú vyčíslenú charakteristiku podľa ktorej je možné odhadnúť úroveň zhody medzi vynaloženými nákladmi a ich samotnou prevádzkou. Pri spracovávaní danej problematiky prostredníctvom MATLAB bolo nevyhnutné pracovať s optimalizáciou finančných nákladov na udržanie spoľahlivosti vyššie uvedených komplexov ako aj nepredvídaných nákladov prevádzkovateľa napr. letiskového bázového systému.Recently, an economic stability and effectiveness of airlines and their branches are important, besides the technical reliability. Within the interest of each provider is to have not only a reliable and economically effective ergatic base complex, as a technical complex, but also the quality of particular elements of the system, and the company itself. Various methods are used to determine the quality of work with complex systems. The proposed method uses the effectiveness index of reliability tests which are a part of the implementation of new complex systems into the ergatic base complex, where the tests´ outputs create a quantified characteristics according to which it is possible to estimate the level of conformity between the costs and real operation. When solving this problem through MATLAB it was necessary to take into account the optimization of financial expenses to maintain the reliability of the above mentioned complexes as well as the unexpected expenses of the provider (for example a provider of airport base system)

Biochemical and Genetic Interactions of Phospholipase D Alpha 1 and Mitogen-Activated Protein Kinase 3 Affect Arabidopsis Stress Response

Phospholipase D alpha 1 (PLDα1, AT3G15730) and mitogen-activated protein kinases (MAPKs) participate on signaling-dependent events in plants. MAPKs are able to phosphorylate a wide range of substrates putatively including PLDs. Here we have focused on functional regulations of PLDα1 by interactions with MAPKs, their co-localization and impact on salt stress and abscisic acid (ABA) tolerance in Arabidopsis. Yeast two-hybrid and bimolecular fluorescent assays showed that PLDα1 interacts with MPK3. Immunoblotting analyses likewise confirmed connection between both these enzymes. Subcellularly we co-localized PLDα1 with MPK3 in the cortical cytoplasm close to the plasma membrane and in cytoplasmic strands. Moreover, genetic interaction studies revealed that pldα1mpk3 double mutant was resistant to a higher salinity and showed a higher tolerance to ABA during germination in comparison to single mutants and wild type. Thus, this study revealed importance of new biochemical and genetic interactions between PLDα1 and MPK3 for Arabidopsis stress (salt and ABA) response

Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae

We systematically surveyed period variations of superhumps in SU UMa-type dwarf novae based on newly obtained data and past publications. In many systems, the evolution of superhump period are found to be composed of three distinct stages: early evolutionary stage with a longer superhump period, middle stage with systematically varying periods, final stage with a shorter, stable superhump period. During the middle stage, many systems with superhump periods less than 0.08 d show positive period derivatives. Contrary to the earlier claim, we found no clear evidence for variation of period derivatives between superoutburst of the same object. We present an interpretation that the lengthening of the superhump period is a result of outward propagation of the eccentricity wave and is limited by the radius near the tidal truncation. We interpret that late stage superhumps are rejuvenized excitation of 3:1 resonance when the superhumps in the outer disk is effectively quenched. Many of WZ Sge-type dwarf novae showed long-enduring superhumps during the post-superoutburst stage having periods longer than those during the main superoutburst. The period derivatives in WZ Sge-type dwarf novae are found to be strongly correlated with the fractional superhump excess, or consequently, mass ratio. WZ Sge-type dwarf novae with a long-lasting rebrightening or with multiple rebrightenings tend to have smaller period derivatives and are excellent candidate for the systems around or after the period minimum of evolution of cataclysmic variables (abridged).Comment: 239 pages, 225 figures, PASJ accepte

Zarządzanie i handel zagraniczny w małych i średnich przedsiębiorstwach w warunkach integracji europejskiej: materiały z konferencji

Z przedmowy: "Integracja europejska to proces łączenia, scalania się odrębnych ekonomicznie, społecznie, kulturowo gospodarek europejskich krajów. Proces integracji prowadzi do istotnych przekształceń w sferze gospodarki, strategiach organizacji i funkcjonowania przedsiębiorstw, handlu międzynarodowym, działalności marketingowej, strukturach organizacyjnych i mechanizmach ekonomicznych przedsiębiorstw i instytucji działających w krajach integrujących się. Proces integracji to w praktyce proces dostosowywania się struktur gospodarczych; tworzenia związków kooperacyjno-produkcyjnych; powstawania trwałych więzi ekonomicznych między przedsiębiorstwami integrujących się krajów a więc proces kształtowania jednolitego obszaru gospodarczego z odrębnych a często także wzajemnie konkurencyjnych krajów, gospodarek, regionów, gałęzi, branż. Proces międzynarodowej integracji gospodarczej to w dużej mierze proces tworzenia komplementamości przedsiębiorstw i instytucji, komplementamości międzygałęziowej i wewnątrz gałęziowej, w produkcji i wymianie jak też kształtowanie niezbędnej infrastruktury technicznej i ekonomicznej umożliwiającej tworzenie sytemu trwałych powiązań gospodarczych między poszczególnymi krajami."(...

Analysis of Using Time Series Method for Prediction of Number of Passengers at the Airport

At present, one of the most frequently discussed topics, not only at international conferences, but also within the EU, is the issue of airport financing, as well as the thresholds at which airports can cover their operational costs and when the need for support is justified. The Strategic Airport Development Plan and the Airport Business Plan are one of the most important support documents for making the right decision for airport financing and prepare the project for operational and investment aid. For preparing these documents is significant the category of the airport, that means the number of passengers. This paper is focused on the methodology how can be predict the number of passengers from previous data by used the time series method