Abstract:Tidal energy might be extracted in a very similar way as the wind one by using turbines. However, due to environmental conditions, unsteady nature of tidal currents and wave activity, tidal turbines have to fulfill very demanding requirements. Such turbines might be structurally similar to wind turbines, but due to a different medium, the key issue is extracting tidal energy in the most effective way. This paper presents a way in which CFD tools may be used for selecting hydrofoil for tidal turbines.
Abstract:Thermographic cameras are becoming increasingly popular in all kinds of diagnostic testing aiming to assess the technical state of thermal power engineering machinery, equipment and installations. The cameras provide thermograms that enable identification of various irregularities, including thermal bridges. However, it can be observed that their accuracy and reliability depend substantially on the conditions in which tests are carried out. Industrial thermographic testing, especially in thermal power engineering, is one of the most difficult procedures. Apart from the advantages of this particular technique, this paper presents an analysis of the effect of the conditions in which tests are performed on the obtained results. Attention is drawn to parameters characterizing the environment and the tested element surface, such as emissivity, reflected temperature, distance between the camera and the object, air temperature, etc. The sources of errors in the testing and in the interpretation of thermograms are indicated. Methods are also presented that enable elimination of irregularities, which improves the accuracy of the final results.
Lisowski, Edward, Okoński, Stanisław, Czyżycki, Wojciech
Abstract:In this paper, a simulation and an experimental analysis of upsetting a cold ring placed between two rigid plates were conducted. When designing a new process, it is preferable to carry out the simulation studies using FEM, which allow for the prediction of the course and proper selection of process conditions. Due to the complexity of phenomena that occur during plastic formation, it is essential to have a good description of contact phenomena and properties of material in the plastic state. The computer simulation was performed for a specific material – a thick plate of hot-rolled carbon steel with fixed initial dimensions of rings and different values of the coefficient of friction.
Abstract:The popularity of using natural waste products in different branches of industry, including polymer processing, results from the emphasis of international nature conservation organizations on ecological and environmental problems, such as recycling, storage and the disposal of waste products. This paper investigates the effect of two natural fillers: wheat bran and pumpkin seeds obtained from food industry waste products, on selected mechanical properties of LDPE molded pieces. The polymer blends are examined with respect to their basic mechanical properties and microstructure.
Abstract:The paper addresses modelling, simulation and experimental research of a pneumatic cushion. The scope of work included formulating a mathematical model based on air flow equations, building simulation model, carrying out simulations and comparing simulation results with experiments. The simulations were performed in Matlab-Simulink system, while experiments were carried out on a test bench, by means of a real industrial pneumatic cushion. The comparison of the results indicates that the created simulation model is accurate and flexible, and thus can be used in further research which concerns e.g. geometrical modifications or optimization of air consumption.
Abstract:This paper presents an application of matrix FMEA analysis and cause-effect diagram for a double acting hydraulic cylinder. A decomposition of the investigated cylinder has been made and main functions and potential failures for the pair-function relation have been identified. Elements with the greatest probability of failure and cause-effect relationship have been determined.
Abstract:Rapid firing of the Skorpion vz.61 machine gun was registered at a police shooting range. The shooting was executed by a policeman from the secret service. The registration was done with the use of a fast digital camera Phantom v9.1 together with the necessary equipment. With the use of the specialised TEMA software, which serves to analyse the recorded image, the courses of the variation of kinematic quantities characterizing the weapon movement were obtained. On the basis of the courses of the variation of the displacement, velocity and acceleration over time, the behaviour of the machine gun in thirteen characteristic points of its operation was specified.
Abstract:Social and economic development trends require that the economy be based on sustainable consumption and sustainable production patterns by means of implementing an effective recirculation policy – this is also important from an environmental perspective. Consequently, the design of economic processes becomes increasingly complex. This paper presents method and results of environmental life-cycle assessment of selected stages of the concrete recycling process. The results will be used in a further, holistic assessment of managing the concrete waste on the construction site.
Abstract:The southern part of Poland is mostly covered by Carpathian mountains. Carpathian Flysch is especially predisposed for the landslides type of the subsoil. Around 98% of all occurring in the country landslides are located in Carpathians. Many of them became active in May 2010, when periodically dormant landslides and new landslide were activated after intensive rainfall. In addition to the main causes of landslides such as rainwater and its infiltration into the ground layers also the Carpathian Flysch tectonic construction (rock layers collapsing in one direction, with numerous jumps and discontinuity) and some anthropogenic influences (loading, slopes undercutting, improper dehydration, etc.) are typical triggering factors. Landslide activity contributes not only to a significant progress of the relief to which occur, but it also carries devastating consequences for the population living nearby. Landslides are a natural threat for economic activities and people’s lives. They are the cause of the damage not only residential buildings but also road and railways and other infrastructure. The landslide analysed here is located in Tymbark, Limanowa district. This article discusses the influence of the building foundation for initiation and growth of the landslide zone in the Carpathian Flysch. Two types of foundations are analysed – base plate foundation and a continuous footing. In both cases, there is a high risk to occur slip zones (FoS < 1.5). Base plate turns out to be more favorable foundation in this subgrade conditions. Although the displacements are relatively larger than in the other case, slip zone is located quite shallow. In the case of the continuous footing, landslide may form deeper reaching the bedrock.
Abstract:The problematic nature of the identification and assessment of the risk factors is a familiar subject area. As a result of this, many scientists are continually attempting to modify existing methods and develop new approaches to achieve this objective. Therefore, it is recommended to periodically review the methods used – this reveals areas of knowledge in this area which remain undeveloped and also determines which methods can complement or verify each other. In this article, current methods for the identification and qualitative assessment of risk factors are described and compared in a tabular manner; the author also proposes potential approaches for the modification and improvement of these methods.