Key Engineering Materials Vol. 597

Abstract: In order to determine the fuel consumption during operation of locomotive it is necessary to work out the characteristics of fuel consumption vs. power produced by propulsion system. These characteristics can be obtained during tests in a diagnostic stand equipped with water rheostat, which allows to simulate any load on the main generator. Another method depends on utilization data from monitoring system of the propulsion system, obtained during regular operation of the locomotive. The main disadvantage of this method is lack of long-term constant loads, which is caused by frequently changing operating conditions. This has a major impact on the measuring error, which can be minimized by suitable utilization of a large number of measurements. Practical remarks of those methods usage have been presented in this paper.

Abstract: A preliminary evaluation has been made of a possibility of bottoming of a conventional Brayton cycle cooperating with the CHP power plant with the organic Rankine cycle installation. Such solution contributes to the possibility of annual operation of that power plant, except of operation only in periods when there is a demand for the heat. Additional benefit would be the fact that an optimized backpressure steam cycle has the advantage of a smaller pressure ratio and therefore a less complex turbine design with smaller final diameter. In addition, a lower superheating temperature is required compared to a condensing steam cycle with the same evaporation pressure. Bottoming ORCs have previously been considered by Chacartegui et al. for combined cycle power plants [ Their main conclusion was that challenges are for the development of this technology in medium and large scale power generation are the development of reliable axial vapour turbines for organic fluids. Another study was made by Angelino et al. to improve the performance of steam power stations [. This paper presents an enhanced approach, as it will be considered here that the ORC installation could be extra-heated with the bleed steam, a concept presented by the authors in [. In such way the efficiency of the bottoming cycle can be increased and an amount of electricity generated increases. A thermodynamic analysis and a comparative study of the cycle efficiency for a simplified steam cycle cooperating with ORC cycle will be presented. The most commonly used organic fluids will be considered, namely R245fa, R134a, toluene, and 2 silicone oils (MM and MDM). Working fluid selection and its application area is being discussed based on fluid properties. The thermal efficiency is mainly determined by the temperature level of the heat source and the condenser conditions. The influence of several process parameters such as turbine inlet and condenser temperature, turbine isentropic efficiency, vapour quality and pressure, use of a regenerator (ORC) will be presented. Finally, some general and economic considerations related to the choice between a steam cycle and ORC are discussed.

Abstract: The article systematises submarines, which are presently in service, according to their propulsion types (both conventional and nuclear), power output, and submersion depth. Contemporary types of propulsion systems installed and used in submarines are discussed. Calculations were performed for the PWR type nuclear propulsion system and the supercritical turbine propulsion system (supercritical reactor cooled with light water). Preliminary designs of turbines have been worked out for these two variants, and the systems were compared with respect to cycle efficiency and turboset efficiency.

Abstract: The article discusses the impact of the quality of biogas fuel for operation of generating sets with internal combustion engines. There are presented selected investigation results of landfill biogas fueled gensets operation. The article includes also discussion of the possibility of increasing the efficiency of biogas fuelled cogeneration systems. It also presents guidelines for the optimal design of landfill biogas fueled engines, ensuring their reliability.

Abstract: The paper presents method of the modal parameters identification based on the Particle Swarm Optimization (PSO) algorithm. The basic PSO algorithm is modified in order to achieve fast convergence and low estimation error of identified parameters values. The procedure of identification as well as algorithm modifications are presented and some simple examples for the SISO systems are provided. Results are compared with the results obtained for Least Square Complex Exponential (LSCE) method.

Abstract: The paper presents the method of the surveillance of the self-excited chatter vibration. At first, the workpiece modal parameters are estimated based on experimental data which leads to verification of computational model. Then, for selected surface points optimal spindle speeds are calculated. By considering sufficient amount of points it is possible to build a map of optimal spindle speeds. Experimental results show that this map may be used effectively for eliminating chatter in case of the process of ball end milling of a curved flexible detail.

Abstract: Performance and security are software (SW) application attributes situated on the opposite corners of system design. In the most drastic example the most secure component is the one totally isolated from the outside world, with communication performance reduced to zero level (e.g. disconnected physically from the network, placed inside a Faraday cage to eliminate possible wireless accessibility). On the other hand the most performance-optimized system is the one with all security rules taken off. Obviously such extreme implementations cannot be accepted, thus a reasonable trade-off between security and performance is desired, starting from the appropriate design, resulting in the adequate implementation, confirmed by security and performance testing in production environment. Unit testing (UT) is a well-know method of examining the smallest portion of SW application source code – units: methods, classes, interfaces in order to verify whether they behave as designed. Ideally, each UT test case is separated from others, taking advantage of stubs and mocks to provide full isolation from external test factors. This paper is an extension to research about joint security testing and performance testing for improving quality of distributed applications working in public-private network environments,addressing SW quality assessment at different, unit test level.

Abstract: The purpose of the research is to assess the increase of the muscle strength and power. Movement of the human body when the moving one impacts a stationary or moving body is taken under consideration. The waveform produced by an impact is transformed into frequency domain. The acceleration record is transformed as a complex spectrum, by the use of a Discrete Fourier Transformation. In this paper the applications of the discrete Fourier transform is discussed and it was pointed out that it can be fruitfully applied to analyze movement techniques during competition or training exercises. The acceleration response spectrum contains knowledge about efficiency of certain techniques. It has distinct features which can show that the energy is concentrated around several discrete frequencies. Data from the shape of a frequency response spectra curve can provide the coach and the performer with valuable information on technique and also give information on recommendations with respect to corrections and adjustments that can lead to performance enhancement. In this paper, the technique of a database creation is proposed what allows us to establish a particular set of circumstances under a specified protocol to observe and evaluate the implications of the resulting observations.

Abstract: In the paper, effects of numerical investigations are presented. Vibrations of mechanical and electromechanical systems are considered and compared. In the system, a continuous beam is considered as the main vibrating element. Two energy dissipations methods are compared: viscous dampers and DC generators. To increase the damping effectiveness, velocity amplification is proposed, i.e., a mechanism is introduced between the beam and the damping element, and the mechanism configuration is set as closed to the singular position of it. According to some observed fundamental differences in the guiding physical properties of some blocks present in the considered system, two structurally different sub-models are introduced in the numerical model of the complete system. The first sub-model corresponds to the amplification mechanism (considered as composed of rigid elements). The mechanism is modelled as a multibody system. The second sub-model corresponds to the continuous beam. The beam is modelled with used of the finite elements technique. To joint the sub-models, constraint equations are proposed. They express a revolute joint that is present between the mechanisms second rod and the beam enforced to vibrate.

Abstract: This paper presents investigations of an expansion process for the manufacturing of hollow shaped polymeric micro-components and provides first fundamentals for applications. The forming principle of the developed process is based on the inner pressurization of a heated micro-tube within a die cavity. In a first step, experimental trials were conducted with a test device for free expansion to investigate the formability of polymeric micro tubes. PA6 and PET with an outer diameter 630-1340 μm were investigated. Based on the free expansion results obtained, demonstrator micro-components were designed to investigate the requirements for suitable tool design in the manufacture of polymeric micro hollow components. The demonstrators were of polymeric micro tubes, PA6 and PET with outer diameter of 1340 μm and wall thickness of 170 μm