A novel method of contactless measurement of turbine vlade vibration during increasing (decreasing) operational speed is presented. The method is based on evaluation of time differences of blade passages along contactless sensors placed on the stator, and substitutional data correction using a numerical model. The method has been verified both numerically and experimentally. For the experimental research on the bladed model wheel of the Institute of Thermomechanics and subsequent applications under operating conditions, two new types of sensors functioning on magnetoresistive and induction principle have been developed. and Obsahuje seznam literatury
The vibrodiagnostic system VDS-UT2 was developed for the investigation of a tram wheel operational vibration and deformation. The system consists of measuring, acquisition and processing tools for monitoring of tram wheels and their operational parameters, e.g. static and dynamic deformation, displacement, velocity, acceleration and temperature. The measuring on a rotating wheel is realized both by telemetric and by top-timing system. Measured data can be remote-observed via Internet connection with the control PC. The acquisition system by Starmans Electronics s.r.o. provides continuous analog and digital data logging. The control PC processes digital logical signals and evaluates time intervals representing circumferential turning angles between disk and rim.. In the contribution, the diagnostic system is described and the measured data including damage analysis are presented. and Obsahuje seznam literatury
The new test approach for evaluation of thermo-visco-elastic parameters of elastomers is designed, realized and discussed herein. The main attention is devoted to a kinematically excited rubber beam specimen under transient resonant sweep excitation. Mechanical material characteristics, i.e. Young modulus and loss angle, are identified from analytical formulas of frequency function based on measured dynamic loading and response signals. Heat material constants were estimated indirectly by numerical thermo-mechanical FE model and matching numerical and experimental results. The 'sweep' regime tests serve for estimation of thermal and mechanical dependences. Long-term fatigue tests with cyclic resonant loading enable analysis of material degradation, such as hardening and permanent deformations. and Obsahuje seznam literatury
Surface-enhanced Raman spectroscopy (SERS) traditionally requires special substrates, typically in the form of noble metal nanostructures, and facilitates detection of molecules at extremely low concentrations. In this work, we present fabrication of novel type of SERS active substrates that combine promising properties of metal nanostructures and graphene, and demonstrate their application in biosensing. The graphene-metal hybrids are fabricated by guided assembly of colloidal gold nanoparticles on e-beam pre-patterned silicon substrate. Gold nanoparticles are then subsequently covered with graphene. The usefulness of such structures in SERS biosensing is tested upon detection of Rhodamine 6G molecules. and Povrchem zesílená Ramanova spektroskopie (SERS) tradičně využívá speciálně upravených povrchů, nejčastěji ve formě kovových nanostruktur, a umožňuje detekci látek o velmi nízkých koncentracích. Tato práce pojednává o přípravě nového typu substrátu vhodného pro metodu SERS kombinujícího výhodné vlastnosti jak kovových struktur, tak i grafenu. Grafen-kovové hybridní nanostruktury byly vyrobeny řízenou depozicí zlatých kuliček na elektronovým svazkem ozářený křemíkový substrát a následným překrytím vrstvou grafenu. Možnost využití výsledných struktur v oblasti biosenzorů byla dále testována při detekci molekul rhodaminu nanesených na jejich povrch.