Applied Mechanics and Materials Vol. 832

Abstract: This paper analyses issues of progressive road traffic noise reducing devices design and evaluating the quality of asphalt road surfaces from the perspective of the Permanent Sustainable Development, which is one of the horizontal priorities of the National Strategic Reference Framework for the period from 2007 to 2013. The horizontal priority (HP) Permanent Sustainable Development (PSD) of the National Strategic Reference Framework (NSRF) has been complementary affecting the objectives of the NSRF. The purpose of the HP is to ensure targeted achievement on several priorities of the NSRF, which cannot be provided by a single Operational Program (OP), but requires a coordinated approach combining several specific priorities / priority axes / actions, or more precisely the projects of particular OPs. Within the specific objective of enhancing the quality of the environment has been directly defined sub-goal - to reduce noise pollution of environment. The scientific paper is concerned with measurements of the noise production and sound propagation on four different roads, where the source of the noise was the same vehicle driving at five different speeds.

Abstract: Technologies dedicated to the rapid prototyping uses a wide range of materials. The mostly used plastic materials are based on polymers. It is for example an Acrylonitrile Butadiene Styrene (ABS), Nylon, Polycarbonate (PC), or composites based on different polymers. New devices designed for the production of a prototype models, based on Fused Deposition Modeling (FDM) are able to work with environmentally friendly and biodegradable materials as Polylactic acid (PLA). The aim of this paper is to show the possibility of using materials based on organic polymers whose properties are comparable to conventionally used polymers. Presented are measured and statistically evaluated data related to basic properties of PLA material.

Abstract: Changes in the climate over the past decades have caused weather extremes that bring numerous unwanted phenomena. Many of these irregularities cause unusually high and low temperatures, intense droughts and devastating floods. All of the listed natural disasters caused by weather extremes affect a wide range of fields which are crucial for our everyday life and its quality. The most affected areas are health and safety, agriculture, industry, transportation. It is therefore evident that the effect of extreme weather in any form can bring not only financial loses, but also a loss of human lives. Based on these facts it is of great interest that the effects of these natural forces are minimised or totally eliminated. This paper deals with the performance of a newly designed mobile flood barrier in real simulated field test conditions. Construction of the barriers was designed solely by the Slovak University of Technology at its Faculty of Mechanical Engineering with the intention of providing effective, economic and safe flood barriers system with a short assembly time. The undertaken testing was focused on the performance of the flood barriers under static pressure by the deflection measurements. The testing consisted of the following steps: experiment design, on sight mounting and fine-tuning of the whole measuring apparatus and evaluation of the gathered data. To simulate real conditions which the barrier will experience during its use, a life size model of the flood barrier segment was constructed and tested. The measurement setup, measurement procedures, the outcomes of the deformation testing together with the resulting deflection model are presented in the following pages of this paper.

Abstract: This contribution describes developments in the area of plastic recycling aimed at the reuse of waste materials for the manufacture of a useful product. Throughout development of the concept “modular flood barrier structure”, the recovery of plastic materials was assessed, primarily, plastic waste from automobiles and industry. The investigators filed a utility model application, no. SK 5847 Y12, entitled “Modular flood barrier structure”. Terms of the type and composition of source material, polypropylene (PP) and polyethylene (PE) were the materials chosen. The article describes the theoretical analysis of the proposed barriers as a starting point for a design and technological design.

Abstract: The contribution deals with the trimming of beef cattle hooves by means of a new method, specifically with a liquid water jet. Present methods of trimming hooves are outdated; almost nowhere are new modern technologies used for this purpose. The use of more contemporary methods would enable a reduction in the high labour demands to accomplish this task. But the main advantage of this new method is increasing so-called animal WELFARE. Present-day methods which are performed mechanically are always stressful, and many times also painful, for the animal. In the article we will specifically focus on the possibility of trimming the hooves of beef cattle by means of a water jet. The original research was focused on the size of the basic parameters such as pressure, flow, nozzle diameter and cutting time. The results of this initial research serve as a step towards further research, whose goal will be the design and testing of complex equipment for trimming beef cattle hooves by cutting with a liquid water jet.

Abstract: This article deals with the performance of heat pipes, depending on the operating temperature and positions (operation angle). There is described the essential function of the heat pipe manufacturing process. Measurements were carried at an operating temperature of 40 °C to 90 °C. Stainless heat pipes were made of three kinds of materials AISI 304, AISI 310, AISI 316 and filled with a distilled water, up to 20% of the heat pipe inner volume. For each material was selected heat pipe with the best results. The heat pipes were measured at various angles of vertical inclination (0 ° - 90 °), at the working temperature 90 ° C. The performance was measured on the experimental device. Presented results show the progress of individual measurements and the effect of operating parameters on the performance of heat pipes.

Abstract: This work deals with heat transfer over heat pipe. In the introduction is knowledge about heat pipes. In the experimental part is influence of working conditions to heat transfer calculations of heat pipes Currently the problem with the increasing number of electronic devices is a problem with the outlet Joule heating. One of more alternatives of outlet joules heating without the using of mechanical equipment is the use of the heat pipe. Heat pipes are easy device to manufacture and maintenance of low input investment cost. The advantage of using the heat pipe is use it in hermetic closed electronic device which is separated exchange of air between the device and the environment. This experiment deals with the influence of changes in the working tube diameter, working position and changing the working medium depending on performance parameters. The result of this paper is finding the optimal working conditions with ideal working substance for the greatest heat transfer for 1cm² sectional area tube. One of more alternatives using heat pipes is a heat transfer Joule heating without the using of mechanical equipment.

Abstract: Sprinkled tube bundles with a thin liquid film flowing over them are used in various technology processes where it is necessary to separate the vapour and liquid phases quickly and efficiently at low temperatures with a corresponding decrease of pressure around the tube bundle. In ideal conditions water boils at the whole surface of an exchanger, but in practice it must be considered that in original spots of contact between water and the exchanger wall the water will not boil at the tubes' surface but the cooling liquid will merely be heated-up. The article focuses on these processes. Experiments have been carried out at a tube bundle consisting of copper tubes of 12 mm diameter placed horizontally one above another that have been heated by water of an average input temperature approx. 40 °C. This bundle has been sprinkled by cool water at temperature of 15 °C and pressure has been gradually decreased using an exhauster at constant flow rates of heating and falling film liquid inside an experimental device's chamber. Was tested flow of sprinkled liquid in the range of 4-9 liters per minute, which corresponds to the range of Reynolds numbers of about 300 to 600 [-]. The result of these experiments is a studied heat transfer coefficient at the surface of a sprinkled tube bundle during heating of the cooling liquid with a transition into boiling of the liquid at the bundle. At a flow of 8 liters per minute were acquired sequence thermal camera FLIR SC 660. After evaluation of the sequences were generated maps of the temperature field according to decreasing the pressure and its standard deviation. From the contour graphs can evaluate the thermal stability of the liquid film on the spray tube bundle.

Abstract: This article is focused on formation of unwanted deposits in the municipal waste incinerator and their influence on incinerator operation. The solid deposits build up on heat transfer surfaces in flue gas channel of waste incinerator. The power stations fired solid fuels sometimes can have problems with growing of deposits. On this point of view, the municipal waste incinerators are a special category, because the municipal waste contains a lot of different types of compounds. Formation of deposits on heat transfer surfaces has in generally bad influence on operating parameters of waste incinerator. Deposits decrease the heat transfer from the flue gas into the working fluid and thereby it reduces the efficiency of incineration facility. The effect of decreasing of heat transfer ability was investigated on large-scale waste incinerator in Brno, where were monitored changes of operating parameters before and after the planned shutdown of the device. Deposits can too affect the shape of flue gas channel and thereby reduce his size. It can have more negative impact on waste incinerator operation.

Abstract: An article is about mechanical effect of the physic-mechanical material properties on the radial pressure in the compression chamber during the compacting process of wood. Some general methods that describe the transformation process of axial pressure into the radial pressure are shown, As well as the mathematical or experimental methods specifying dependencies and physical conditions. Mathematical finite element method in this area is very useful, but rarely used. Common problems using FEM are the proper definition of the physical material properties in a particular stage of compaction. Material properties are greatly influenced by a number of factors such as moisture, fraction size, chemical composition, current temperature, radial macro structure, axial macrostructure, current pressure and others. The chamber material and the manufacturing processes or the state of wear has an impact on the physical conditions. In terms of tensile elastic deformations, these complex effects reflect and can be merged into several properties. The conversion of axial to radial pressure indicates that some properties of the compacted material have a major impact on the process, such as friction between material and chamber, elastic modulus and Poisson's ratio. The geometry of the pressing chamber also has a significant impact. This paper does not deal so much with the pressing chamber geometry but more so with the characteristics embodied in experimentally measurable quantities. The measurement of these properties in combination with the application of FEM methods proves to be a highly progressive method for understanding the compaction process and the engineering design of compaction machines for the production of briquettes and pellets. The article urges further examination and measurement of a wider range of material properties in the densification process.