Search results for " engineering"
showing 10 items of 38291 documents
Effect of Cu doping on Ba0.95Pb0.05TiO3 electrical properties studied by means of electrical impedance spectroscopy
2019
The ceramics of 0.95BaTiO3–0.05PbTiO3+Xwt.%CuO (X = 0.05, 0.1, 1, 3) were prepared by a solid phase reaction. The structural and morphology studies were carried out by means of X-ray diffraction te...
Bandgap behavior and singularity of the domain-induced light scattering through the pressure-induced ferroelectric transition in relaxor ferroelectri…
2018
[EN] In this letter, we have investigated the electronic structure of A(x)Ba(1-x)Nb(2)O(6) relaxor ferroelectrics on the basis of optical absorption spectroscopy in unpoled single crystals with A = Sr and Ca under high pressure. The direct character of the fundamental transition could be established by fitting Urbach's rule to the photon energy dependence of the absorption edge yielding bandgaps of 3.44(1) eV and 3.57(1) eV for A = Sr and Ca, respectively. The light scattering by ferroelectric domains in the pre-edge spectral range has been studied as a function of composition and pressure. After confirming with x-ray diffraction the occurrence of the previously observed ferroelectric to pa…
Analog isolated electronic dynamometer based on a magnetoresistive current sensor.
2017
In this work, an electronic system is presented to measure the force applied by a solenoid. The originality of the work is focused on the use of a magnetoresistive current sensor to provide the isolation barrier needed in the actual industrial plant where the solenoids are working. The design of the electronic system is presented as well as experimental measurements as a result of a calibration process showing a negligible hysteresis with that specific sensor. The magnetoresistive current sensor is used to develop transmission functions rather than playing its usual sensing roles.
From EFTA to EC/EU and Back to EFTA? The European Economic Area (EEA) As a Possible Scenario for the UK-EU Relations After Brexit
2018
Brexit is announced to take place and it appears, that the most probable scenario for the UK is the “Norway-Option”, i.e., to (again) become a member of the European Free Trade Association (EFTA) and join the EEA. The chapter identifies the major claims of the leave-campaign to analyse, whether by doing so, the Brexit proponents will achieve what they campaigned for. Furthermore, the paper explains the functioning of the EEA, exploring the potential changes for the UK, the EU, and the EEA/EFTA.
Nonlinear optical response of bulk ZnO crystals with different content of intrinsic defects
2018
Abstract The nonlinear optical (NLO) properties of native defect-rich ZnO single crystals were studied in details within the excitation of the continuous wave (CW) and pulsed laser radiation at 532 nm (2.33 eV). Analysis of the experimental data of optical elastic scattering, Fourier transform infrared (FTIR), near infrared–visible–ultraviolet (NIR–Vis–UV) spectra recorded in reflection and absorption modes, and data of photoluminescence (PL) spectroscopy confirmed the contribution of both intrinsic defects and their clusters, being determined before by neutron diffraction and XRD analysis. It was shown that the high sensitivity of the NLO diagnostics via self-action of a laser beam is due …
RBS and ERD cross-sections and optical model parameters for the analysis of lithium, boron and nickel
2000
Abstract Elastic scattering cross-sections for RBS analysis of nickel by 7 Li and 11 B ion backscattering near the Coulomb barrier have been determined. The lithium ion measurements were performed in the energy range of 8–15 MeV at the laboratory angles of 115° and 135°. For boron ions the energies between 14 and 24 MeV and scattering angles of 89°, 110° and 130° were used. For the analysis of lithium and boron by ERD the scattering cross-sections have been calculated by kinematically reversing the backscattering process. The calculated 58 Ni ion energies thus varied between 65 and 125 MeV for lithium and between 75 and 130 MeV for boron recoils. For the Li + Ni and B + Ni systems the thres…
Early detection and classification of bearing faults using support vector machine algorithm
2017
Bearings are one of the most critical elements in rotating machinery systems. Bearing faults are the main reason for failures in electrical motors and generators. Therefore, early bearing fault detection is very important to prevent critical system failures in the industry. In this paper, the support vector machine algorithm is used for early detection and classification of bearing faults. Both time and frequency domain features are used for training the support vector machine learning algorithm. The trained classier can be employed for real-time bearing fault detection and classification. By using the proposed method, the bearing faults can be detected at early stages, and the machine oper…
Investigation and reduction of losses on inverter-fed induction motors
2017
An electric motor is more effective and flexible when supplied by a frequency converter. The frequency converter not only produces the fundamental voltage but also a set of higher harmonics which cause additional losses in the motor. Losses in the frequency converter are normally neglected in the drive dimensioning due to insufficient data available from manufacturers. Motor's losses can be reduced by increasing the switching frequency of frequency converters. An increase of the switching frequency may result in higher losses in the frequency converter. This work investigates analytically and experimentally the dependence of the losses of modern motor and frequency converter on a switching …
Design and experimental validation of a magnetic device for stem cell culture.
2020
Cell culture of bone and tendon tissues requires mechanical stimulation of the cells in order to mimic their physiological state. In the present work, a device has been conceived and developed to generate a controlled magnetic field with a homogeneous gradient in the working space. The design requirement was to maximize the magnetic flux gradient, assuring a minimum magnetizing value in a 15 mm × 15 mm working area, which highly increases the normal operating range of this sort of devices. The objective is to use the machine for two types of biological tests: magnetic irradiation of biological samples and force generation on paramagnetic particles embedded in scaffolds for cell culture. The…
Inhomogeneous electron distribution in InN nanowires: Influence on the optical properties
2012
In this work, we study theoretically and experimentally the influence of the surface electron accumulation on the optical properties of InN nanowires. For this purpose, the photoluminescence and photoluminescence excitation spectra have been measured for a set of self-assembled InN NWs grown under different conditions. The photoluminescence excitation experimental lineshapes have been reproduced by a self-consistent calculation of the absorption in a cylindrical InN nanowires. With the self-consistent model we can explore how the optical absorption depends on nanowires radius and doping concentration. Our model solves the Schrodinger equation for a cylindrical nanowire of infinite length, a…