Řada strojní. 2012, roč. 58 / Mechanical Series. 2012, vol. 58

Permanent URI for this collectionhttp://hdl.handle.net/10084/111977

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Now showing 1 - 20 out of 38 results

Traffic conflicts as safety indicator - current state and development
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Zajíc, Pavel; Křivda, Vladislav; Řezáč, Miloslav
Traffic conflicts observed and recorded on the road represent a source of information for the most prevalent surrogate road safety indicators. In spite of the questions concerning their reliability and validity, this method stays on the threshold of further progress. Thanks to easier availability of more advanced information technologies and progress in stored data analysis methodology.
The effect of strain rate on the properties and microstructure of the DC 06 steel
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Tatíček, František; Pilvousek, T.; Pacak, T.; Turza, Lukáš
The effect of strain rate on the process of flat forming at room temperature has not been clearly defined yet. So far, the effect of strain rate has only been assessed for hot forming technology. The current industry specialising in flat forming technology place great emphasis on the reduction of material consumption and the number of rejected pressed parts, on the increase of productivity and quality of work, use of advanced pressing machines (e.g. servo presses), etc. All the aforesaid make us ask how to modify the boundary conditions of the pressing process in order to meet the requirements. It shows that standard conditions influencing the pressing process, e.g. pressure generated by the holder, lubrication, application of draw beat, are not able to influence the process to the full extent and it is necessary to seek potential in other boundary conditions. It becomes more and more obvious that strain rate has a major impact on the pressing process. This article aims to describe the influence of strain rate on the formability in flat forming technology and on the behaviour of microstructure after deformation in various material lots of the DC06 steel.
The base unit for biodiesel production controlling
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Plšek, Stanislav; Vašek, Vladimír
This work describes the control of biodiesel production from renewable and waste raw materials. Biodiesel for internal combustion engines are currently produced and used with all its advantages (reducing CO2, produced from renewable materials) and disadvantages (higher nitrogen oxide emissions). For production of biodiesel was implemented and deployed controlling system based on programmable logic controller Saia. Programmable logic controllers are widely used and deployed from the smallest to the largest manufacturing processes in industry. The control system maintains the required parameters of a chemical reaction, in which biodiesel is created from renewable or waste raw materials.
Usability of low-pass filters on biomass combustion quantities
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Placier-Zavala, Emmanuel; Plaček, Viktor
Quantities measured during biomass combustion experiments are heavily burdened with a considerable noise. Usage of common linear low-pass filters is able to smooth measured time rows but it also introduces typical dynamic delay of filtered data. The article presents comparison of three commonly used linear filters – Butterworth, Bessel and Chebishev. An effort to smooth measured data without introducing dynamic delay led us to use some of less common non-linear filters. The article further presents usage of Threshold and Gaussian weighted average non-linear filters and compares them with the linear ones.
Calibration of biaxial NC positioning table
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Peták, Tomáš; Kureková, Eva
This contribution describes procedures and interpretation techniques of calibration biaxial positioning table carried out in the Institution of automatization, measurement and applied informatics STU in Bratislava. Characteristics of table axes, which is installed as a part of information and control system laboratory are demonstrated by calibration. As method for calibration was used direct comparison method. The Aim of this work is to specify a calibration method, design of measurement model, execution of the measurement experiments, statistical evaluation of the measurements, specification of source of uncertainties and interpretation of the results of calibration in terms of the chosen methodology. As a standard was chosen laser interferometer XL 80 from Renishaw to fulfill requirements for high accuracy and repeatability measurements of NC table axes. Laser interferometer is used in the geometrical quantities measurement such as length, angle, straightness, flatness or perpendicularity. Advantage of this standard is the software, which allows evaluation of measurement according to ISO standards and the others. As a result of this work is to determine the positioning errors of NC table with application of corrections of these errors. Finally is made positioning control of table axes by re-execution of the measuring experiments.
Proposal of the power supply for DC and AC electric motors
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Mitaľ, Dušan; Kormoš, Miroslav
The article deals with measuring system by Steiger Mohilo. The unit serves for measuring rotations of low power electric motors without contact specially intended for laboratories. There is available to measure AC motors and also DC motors using mostly in white appliances. The contribution also deals with finding suitable power supplies for these motors and their continual regulation provided on our markets.
Laboratory and pilot research of pyrolysis process
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Mikulová, Zuzana; Honus, Stanislav; Juchelková, Dagmar; Strakoš, Vladimír
Pyrolysis is a suitable recycling method that leads to a creation of 3 pyrolyzed phases (gas, liquid and solid) and every phase has its possible utilisation. Pyrolysis is a complicated process and its description in the light of system analysis by means co called transport system enables its reduc-tion on a system of masses transport and a system of energy transport. A transport system consists of accumulative elements (a reservoir), transformation elements (a pyrolysis retort, a burner) and transport elements (pipes). In a system of pyrolysis, by means of transformation elements, the follow-ing actions are realised: a flow of mass and energy, transformation of input material to a pyrolyzed phase in a transformation element and storage of products in accumulative elements. Quantity and composition of pyrolyzed products are dependent on process conditions of a pyrolysis especially temperature. Pyrolysis of scrap tyres was tested in a laboratory thermic analyzer and in semi opera-tional unit of Pyromatic. Presented article presents results obtained from both devices.
Advanced modeling of surface roughness with artificial neural network, Taguchi method and genetic algorithm
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Madić, Miloš; Radovanović, Miroslav
Modern manufacturing requires reliable and accurate models for the prediction of machining performance. Predicting surface roughness before actual machining plays a very important role in machining practice. This paper presents the modeling methodology for predicting the surface roughness in turning of unreinforced polyamide based on artificial neural networks (ANNs), Taguchi method and genetic algorithm (GA). The machining experiment was conducted based on Taguchi’s experimental design using L27 orthogonal array. Input variables consisted of cutting speed, feed rate, depth of cut and tool nose radius, while surface roughness (Ra) was considered as output variable. To systematically identify optimum settings of ANN design and training parameters, Taguchi method was applied. Furthermore, a simple procedure based on GA for enhancing the ANN model prediction accuracy was applied. Statistically assessed as an accurate model, ANN model equation was graphically presented in the form of contour plots to study the effect of the cutting parameters on the surface roughness.
Implementation of a cacuum effector for the ABB IRB 140 industrial robot
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Lipina, Jan; Greguš, Petr; Tomáš, Jaroslav; Krys, Václav; Khludova, Ekaterina
The article describes the implementation of the vacuum effector [1]. Based on requirements such as a 1kg load capacity, a maximum acceleration of 10 m/s2 and a source of energy – an air of 5bar pressure, it addresses a effector´s body design, presents a calculation of suction cups and also a test of the implemented vacuum effector including its evaluation.
Comprehensive expression of durability for the selected cutting tools in comparison with standard ISO 3685
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Duplák, Ján; Hatala, Michal
Durability of cutting tool defines lifetime of this cutting tool and it determines its suitability for select technological operation. Technical science defines a lot of different factors, that they may be cause of shorter cutting tool lifetime. Some types of cutting materials are defined by means of descriptions in standards ISO, some types by means of catalogues from the manufacturer. There are a lot of types of cutting materials they have not been defined theirs properties exactly yet and theirs properties have to be defined on experiments. There is a presumption that descriptions in standards ISO are not correct and these standards have to be examined and verified, because that this fact have to be confirmed or disproved. Accuracy and completeness technical standards ISO are very important part quality of manufacturing. Only correct standards ISO should be used like instruction, or tool for manufacturing process of companies. The article describes process how to define and analytically express durability dependence for selected cutting tools, specifically high speed steel (HSS), cutting ceramic (Al2O3) and sintered carbide (P20+TiN).
Analysis shock to start and stop an elevator
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Crăciun, Ioana; Ungureanu, Mioriţa
The paper studies the dynamics of an elevator, the theoretical determination of jerk at the start and stop of an elevator for a certain tachogram. Maximum shock acceptable values are imposed by standards.
Influence of the surface contact phenomena on the structural changes and nano-layers generation
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Beneš, Libor
This work is dealing with a study of the micro/structure transformation that is induced by rolling contact friction and adhesive wear, respectively, in the rail-wheel/rail system. Several small rail-surface samples, we term them as the “chips”, as well as a railway wheel samples were chosen for the analyses of the surface changes on the rail/wheel surface. A multitude of different experiments were carried out in order to analyse the microstructure changes at the surface and the near-surface region of the material samples and, thus, to contribute to the understanding of the complex rail/wheel rolling contact phenomena - and mainly, its degradation mechanisms. The formation of nano-structured martensite and carbides on the rail and wheel surface causes the extremely high microhardness valuees and the strong corrosion resistance of the so called White Etching Layers (WEL).
Determination of volumetric losses in hydrodynamic pump using numerical modelling
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Zavadil, Lukáš; Drábková, Sylva
This paper deals with the numerical modelling of the flow in the single-stage centrifugal pump. The main objective is to determine leakage losses through annular seals at the suction side of the pump. Leakage through a shaft seal is not included in the simulation. The amount of liquid that circulates from the impeller discharge back to suction of the pump is determined in dependence on the flow rate. Losses in the pump are further discussed as well as the possibility of their prediction.
Application of SBRA method in mechanics of continetal plates
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Wandrol, Ivo; Frydrýšek, Karel; Kalenda, Pavel
This paper shows the probabilistic SBRA Method application to the model of the behaviour of the lithosphere of the Earth. The method extends our initial work where we created the geomechanical model of the lithosphere. The basic idea was about the generation of thermoelastic waves due to thermal expansion of the rock mass and the ratcheting mechanisms.
Set covering problem in transport nets expanding models
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Teichmann, Dušan; Hlavsová, Markéta; Konupčíková, Erika
The article deals with the problem of optimal coverage of utility centres in transport network. We can often encounter similar types of tasks in a real life. A lot of cases relate to the public utility systems that mean systems intended for providing basic public services to all population in a certain territory. These services can include services of Integrated Rescue System. The tasks of this category are called max D tiling tasks in a scientific literature. The classic version of max D cover task is known for quite a long time but its shape does not always cover real traffic conditions. The aim of the article is to show other modifications of the basic variation of the tasks. The authors expect the proposed application will enable mathematical apparatus to be used to solve problems of this type to the greater extent.
Design of a gear air engine whit use of „HCR” gearing
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Sniehotta, Patrik
In the design of a gear air engine is the size of the tooth space fundamental. Most current calculations, however, cannot, especially for non-standard "HCR" gearing, this problem satisfactorily describe.Therefore, it is preferable to use for this type of air engine ,,HCR“ gearing, which maintaining the desired performance, while reduce the overall dimensions of the air engine. This article shows the possibility of calculating the exact size of the tooth space using numerical methods and shows the advantages of a gear air engine whit ,,HCR” gearing, compared to a gear air engine whit standard gearing.
Mathematical solution of a linear hydraulic servomechanism
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Řepka, Radim; Pavlok, Bohuslav
In this paper the mathematical model of linear hydraulic servomechanism for lifting heavy loads which was used to creation a mathematical model in Matlab Simulink and also Matlab SimHydraulics is described. Calculated results of piston rod velocity for various operating conditions are compared to each other in the section of results evaluation.
Use of numerical simulation at optimisation of technological processes of cold bulk forming
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Rusz, Stanislav; Tylšar, Stanislav; Kedroň, Jan; Salajka, Michal; Brumar, Tomáš
The paper deals with numerical and physical modelling aimed at optimisation of production technology and designing of manufacturing tools with use of finite-element method. For the topic of cold bulk forming a manufacture of pressed insert, used in industry as a component for damping system for passenger cars, was simulated. It is a rotationally symmetric component, which is subjected to high axial load, and strength and fatigue characteristics of which depend substantially on service life and reliability of the whole damping system. This component was subjected to analysis of distribution of flow stress and deformation intensity at combined extrusion from the viewpoint of their load with use of simulating software Simufact.Forming 10.0. The simulation process ran smoothly, without sudden changes of the shape leading to formation of possible internal defects.
Finite difference method used for the beams on elastic foundation - part 2 (applications)
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Nikodým, Marek; Frydrýšek, Karel
This article (as a continuation of the former work published in this journal), is focused on the theory and applications of beams on elastic (Winkler's) foundation. For solution of these problems of mechanics, the Finite Difference Method can be applied. Practical examples (i.e. beams with constant or variable stiffness of foundation) are explained and solved (Matlab software).
Finite difference method used for the beams on elastic foundation - part 1 (theory)
(Vysoká škola báňská - Technická univerzita Ostrava, 2012) Nikodým, Marek; Frydrýšek, Karel
This article is focused on the theory of straight and curved beams on elastic (Winkler's) foundation. For solution of these problems of mechanics, the Finite Difference Method (i.e. Central Difference Method) can be applied. The basic information about finite differences and their application are explained.

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