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Wzrost wydajności ciągarek wielostopniowych można osiągnąć przy wyższych prędkościach jeśli zapobiega się zrywaniu drutu w trakcie procesu ciągnienia. Jedną z niedogodności ciągnienia przy dużych szybkościach jest wymaganie, by dynamika systemu zapewniała stabilność i nieza­wodność działania maszyny. Siły rozciągające w drucie muszą być utrzymane na stałym poziomie przez szybką synchronizację prędkości wszystkich bębnów. Główną rolę w tym procesie pełnią czujniki przemieszczenia, które działają w pętli sprzężenia zwrotnego systemu sterującego dostar­czając informacji o stanie drutu. W pracy analizowano oddziaływania między czujnikami i bębna­mi napędzanymi przez serwomotory i badano doświadczalnie koncepcję zastosowania rolkowego czujnika przemieszczenia w ciągarce wielostopniowej. W tym celu wykonano pomiary na dwu stopniach ciągarki przy różnych prędkościach ciągnienia, a rezultaty zaprezentowano w pracy. Pokazują one, że zmiany prędkości bębnów i przemieszczeń kątowych mechanizmu rolkowego, który utrzymuje drut w napięciu, są bardzo szybkie, co potwierdza dobrą dynamikę sterowania ciągarki.

As the level of complexity of modern rotating machinery grows, the need for an effective and efficient maintenance process increases as well. In the last decade, researchers all over the world have shown strong aspiration to optimize the diagnostics phase in rotating machinery. This paper highlights some of the latest research on the detection of typical faults in rotating machinery such as mass rotor imbalance, misalignment, rub and looseness, bearing and gear faults. Various techniques for condition monitoring have been researched, and in this paper, they have been classified into three groups: physics-based, data-driven, and physics-based data-driven methods. Although most of the research falls into the first two prior mentioned groups, an intent to introduce a novel method, their symbiosis, has emerged in the last few years. The great potential for future work on physics-based data-driven methods in the field of rotating machinery has been briefly discussed. [ABSTRACT FROM AUTHOR]

A reliable operation of generators is highly dependent on the electrical and mechanical integrity of stator end-winding vibration and has been a major concern in the last two decades. This paper focuses on the experience in hammer impact testing of end-winding vibrations of parallel phase leads and series loop caps in two hydro generators in a different temperature state. The measurements were conducted using hammer testing on the two generators separately and a discussion and comparison of the results was presented in order to perceive the dependence of the temperature and dynamic characteristics of the structures. Introductory, a brief survey of recent research progress in monitoring the end-winding vibrations in generators is presented. Subsequently, a detailed description of the performed measurement, starting from the identification of the object and conducted testing methodology according to established standards is systematically exposed. Ultimately, a paramount accent will be put on the experimental results for the measured natural frequencies of the generators, perspectives and propositions on subsequent scientific will definitely not be left out. [ABSTRACT FROM AUTHOR]

The results of the simulations of the blade group resonant stresses in a FE environment and fatigue life calculation are presented in this paper. Numerical calculation for determination of natural frequencies, mode shapes and dynamic stresses, based on FEM and NISA package is used. Analyses are made on the blade group with three blades with rectangular cross section and typical turbine blades with taper, pretwist and asymmetric airfoil as well. The influence of the position of the lacing wire on the resonant stresses is analyzed. Three-dimensional finite element models of the blade group are made by using twenty node isoparametric solid elements. The number of degrees of freedom is different for each model (more than 30000 DOF). The fatigue life and consequent life prediction according the stress load history of the blades is made. The results of the investigation are given in tables and graphics. [ABSTRACT FROM AUTHOR]

This paper elaborates the procedures for scaling prototype structure to scale model according to similitude laws keeping the dynamic properties of the original structure. The scaling procedures are very suitable for experiments where the purpose is not only to check the strength of the structure, but also to investigate the performance of other dynamic devices mounted on the primary structure such as dynamic absorbers. In such cases, the use of condensation methods comes to mind in order to reduce the original d.o.f. and make the model structure behave same in the first several modes as the original structure. [ABSTRACT FROM AUTHOR]

The recent expansion of wireless sensor networks (WSN) in urban cities has led to possibility of generation of large amounts of information data from the environmental monitoring systems among which one of the most concerning is the excessive urban noise pollution. As opposed to the conventional noise mapping procedures that involve costly and time-consuming measurement process with a traditional high-priced noise level meter, the low-cost wireless sensor networks provide a method for achieving data collection and analysis with a higher level of granularity. This paper presents a wireless noise sensor unit design for continuous environmental noise level monitoring as a framework for the realization of the Internet of Things (IoT) and „Smart city" concept. The concept involves the complete noise data information system, from sensor structure to data visualization and data analysis. The overall design, characteristics and performance of the sensing system for continuous measuring urban noise pollution is discussed. [ABSTRACT FROM AUTHOR]

The fault detection of rotating electrical machines has become very attractive field of research from vibrational aspect, because these machines are susceptible to failure due to thermal, electrical, mechanical or environmental stresses. Therefore, the vibrational analysis of generators as rotating machines will be beneficial for the generator design in the initial stage and also for online monitoring and faults diagnostics during generator operation. This paper presents a novel methodology for hammer impact testing („bump-test") of stators end-winding vibrations with an accent on the influence of the physical parameters such as temperature. Introductory, a brief survey of recent research in the area is presented. Furthermore, a detailed description of the used instrumentation and conducted testing methodology according to established standards is systematically exposed. The measurement methodology is implemented on two generators, a cold one in its' repairing phase and second identical, generator in a warm condition in order to detect the damaged elements and to investigate the influence of the temperature on the dynamic characteristics (natural frequencies and rigidity) of the structures. A year later, series of same measurements on one of the generators during a process of its' cooling were conducted. This work provides graphical, as well as numerical results for the dynamical behaviour of the structures under different thermal conditions. Ultimately, a conclusion for the dependence between the temperature and the dynamics parameters of the generator is drawn. [ABSTRACT FROM AUTHOR]