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In this paper, the analysis of noise and sensitivity for different BP filter designs is observed. Calculation of the voltage noise spectral density, root mean square (RMS) value of the noise voltage, Schoeffler sensitivity and the multi-parameter sensitivity is done for the simply designed (SD) active RC, noise and sensitivity optimized (NO and SO) active RC, operational transconductance amplifiers (OTA-C) and switched capacitor (SC) filter designs. This is observed for the fourth-order Chebyshev band-pass filter, with central frequency fc = 4 kHz, bandwidth 1 kHz and pass-band ripple αmax = −0.1 dB. Cascade of two second-order sections is used for fulfilment realization of all four observing designs. Programming tools, such as MATLAB and SPICE (LTspice), are also used for the analyses. Highlights • We used three different designs and optimization (noise and sensitivity) procedure for design and optimize the fourth-order Chebyshev band-pass filter • Our results suggest which design is best to use for improving noise and sensitivity of this filter • MATLAB and SPICE software were used for calculations and simulations of different band-pass filter designs and analysis of noise and sensitivity

Electroencephalography (EEG) is well known method of recording electrical brain activity with electrodes placed along the scalp. One of the challenging tasks in this field is the removal of electrical signals that are not related to brain activity.In this paper, an algorithm for the removal of the EEG signals corresponding to the eye blink artifacts is presented. The presented algorithm is based on ADJUST artifact removing tool, which uses independent component analysis (ICA) for signal decomposition. For every signal component returned by the ICA algorithm, temporal-spatial features are calculated, upon which every independent component is classified as artifact or non-artifact, and removed accordingly.

In this paper, generation of oscillatory synthetic signal simulating brain network dynamics is proposed. The methods follows the expectations of brain network connectivity, which include expressed phase angle differences and signal mixture. We have generated thirty-two signals simulating two groups of sixteen electrodes. Each signal is a mixture of two signal components. The first signal component is synchronized within a group of electrodes but delayed to obtain different phase angles, while the second signal component is unique to each electrode. This simulation give us possibility to present that all brain regions or sources are not connected with each other and that the phase difference between connected oscillators (sources or channels) is not necessary close to zero and could be arbitrary. Phase locking value (PLV) and phase lag index (PLI) measures of connectivity have been calculated on the synthetic signals.

Brain Computer Interfaces (BCI) are devices that use brain signals for control or communication. Since they don't require movement of any part of the body, BCI are the natural choice for assisted communication when a person is unable to move. In this article, BCI based communicator for persons in locked-in state is described. It is based on P300 brain response of the user, thus does not require prior training, movement or imagination of movement. Auditory paradigm is selected in order to apply the communicator in cases where visual ability is also impaired. The communicator was designed to prove also whether low cost hardware with reduced electrode set could be used efficiently in everyday environment, without the need for expert personnel. The design of the communicator is described first, followed by detailed analyses of the performance when used by either healthy or disabled subjects. It is shown that auditory paradigm is the primary factor that limits the accuracy of communication. Hardware characteristics and reduced electrode set influence the accuracy in a negative way as well, while different questions and answer types produce no major differences.

Traditional electrical power systems were designed with an assumption of unidirectional power flows through electrical networks. For many years power plants had been the only sources of electrical energy, and the energy had been delivered to the consumers by the means of transmission and distribution networks exclusively.With the emergence of distributed generation units, power flows have become bidirectional, which has made it impossible to estimate the voltages and currents in substation feeder nodes by measuring only the values at the beginning of the feeder. As the aforementioned estimation process is the basis of traditional voltage regulation techniques, it is obvious that under the new circumstances existing methods have to be upgraded.The article demonstrates how the open source tool PandaPower along with the Python programming language was utilized to analyze and evaluate several different scenarios of using photovoltaic distributed sources inverters for voltage regulation in low voltage electrical power networks.

This paper describe the analyses of EEG data during and after infrared (IR) stimulation of a head. IR stimulation is a type of photobiomodulation (PBM) therapy, a non-invasive form of therapy that uses light energy to start non – thermal photochemical processes in the cellular structures. IR LEDs at 850 nm were used to generate stimulation modulated with 10 Hz square wave. Spectrum of EEG signals were analyzed, with focus on Alpha frequency band that includes frequency of IR light modulation. Frontal, central, parietal, and occipital electrode sites were taken in consideration in three healthy adults. Changes in Alpha frequency band were observed during stimulation and immediately after (short–term effect). There were no changes between consecutive measurements (long–term effect). Most pronounced change of spectrum was measured for Alpha band and lower frequencies.

Photovoltaic (PV) system inverters usually operate at unitary power factor, injecting only active power into the system. Recently, many studies have been done analyzing potential benefits of reactive power provisioning, such as voltage regulation, congestion mitigation and loss reduction. This article analyzes possibilities for loss reduction in a typical medium voltage distribution system. Losses in the system are compared to the losses in the PV inverters. Different load conditions and PV penetration levels are considered and for each scenario various active power generation by PV inverters are taken into account, together with allowable levels of reactive power provisioning. As far as loss reduction is considered, there is very small number of PV inverters operating conditions for which positive energy balance exists. For low and medium load levels, there is no practical possibility for loss reduction. For high loading levels and higher PV penetration specific reactive savings, due to reactive power provisioning, increase and become bigger than additional losses in PV inverters, but for a very limited range of power factors.

In this paper, noise propagation through a two-stage nonlinear algorithm for measurement of harmonic distortion in power systems according to IEC 61000-4-7 is analyzed. Noise generated in the instrument’s input circuitry is considered as an aggregated noise source without detailed characterization of its origin. The first stage of the measurement algorithm is the discrete Fourier transform (DFT) of the input signal. Noise propagation through the DFT is analyzed by means of probability theory. The result of this analysis, the probability density function (pdf) of the DFT spectrum amplitudes, is used for characterization of the second stage of the measurement algorithm – the root-sum-square grouping of several spectrum components into a single harmonic distortion index. In this way, pdfs of the most common harmonic indices are derived and analyzed. The study presented reveals that noise generated in the input stage produces, besides the already known variance of the results, an offset in the harmonic distortion indices. Analysis of the resulting pdfs implies that an increase in the number of components in the grouping procedure increases the offset error, whereas the standard deviations are essentially independent of the number of components included in the group. The validity of the model derived has been tested with a prototype of a low-cost portable instrument for three-phase power quality measurements.

Power distribution systems often exhibit different harmonic behaviours at different locations. It is not usually possible to completely characterise the distortion at a particular site, however, due to insufficient data about the measured system and instrumentation inability to evaluate or register complete set of measurement quantities. In this paper existing power quality standards are analysed and new harmonic distortion indices are derived. A new index describing the total harmonic distortion in current measurements, TRD, is suggested in order to simplify and standardise harmonic measurements. Another index representing the increase of harmonic voltage distortion with TRD, equivalent harmonic impedance zeq, is proposed as an efficient way of characterising a particular site. The framework described here can be used to predict future harmonic behaviour at any previously measured point. Finally, extensive harmonic measurements of a real distribution system were performed to prove the usefulness of the proposed indices.

In this paper, a virtual instrument for bio-impedance measurements in oral cavity is described and characterized. The instrument is realized by using general purpose USB data acquisition device and LabVIEW. The flexibility of the virtual instrument allows the evaluation of different values and indices, in order to determine most suitable measurement parameter. The realized instrument was tested on electrical models with known impedance values and during in-vivo measurements.