MODELING AND INVESTIGATION OF THE REGULATOR WORKING IN THE POINTWISE SLIDING MODE

The main disadvantage of the classic sliding mode is that the control signal is made of high frequency variations. In the recommended pointwisesliding mode the frequency of the variations decreases, since the control signal makes jumps at the isolated points. At the same time, the trajectory remains in a small neighborhood of the plane of switching. In the finish mode, the trajectories that start over the sliding plane reach simultaneously the equilibrium point. It is possible to assume that these regulators will expand the implementation scope of the sliding (quazisliding) modes.

Periodic variability of the z = 2.0 quasar QSO B1312+7837

We report here the first results from a 15-yr long variability monitoring of the z = 2.0 quasar QSO B1312+7837. It shows luminosity changes with a period P ∼ 6.13 yr (P ∼ 2.04 yr at rest frame) and an amplitude of ∼0.2 mag, superimposed on a gradual dimming at a rate of ∼0.55 mag per 100 yrs. Two false periods associated with power peaks in the data windowing function were discarded. The measured period is confirmed with a bootstrapping Monte Carlo simulation. A damped random walk model yields a better fit to the data than a sine-function model, but at the cost of employing some high frequency variations which are typically not seen in quasars. We consider the possible mechanisms driving this variability, and conclude that orbital motion of two supermassive black holes – result from a recent galaxy merger – is a possible explanation.

Joint Ionosonde Studies of F2 Layer Critical Frequency Variations in the Ionosphere Over Kharkiv and Tromsø During Fall Equinox in Quiet and Disturbed Conditions

According to the results of joint ionosonde studies of variations in the ionospheric F2 layer critical frequency over Kharkiv and Tromsø during low solar activity for fall equinox on September 22 – 24, 2020, the features of foF2 variations in middle and low latitudes were investigated for magnetically quiet and magnetically disturbed conditions. On the magnetically quiet day of September 22, 2020, the foF2 values over Kharkiv were found to exceed the foF2 values over Tromsø for the entire time interval of joint observations 02:45 - 16:45 UT. Both over Tromsø and over Kharkiv, a rapid increase in foF2 to its local maximum value was observed after the sunrise. Quasi-periodic variations in foF2 were revealed at high latitudes, which had lower amplitude compared to variations in foF2 over Kharkiv. Over both measuring sites, a pre-sunset local maximum in foF2 was observed. During magnetically disturbed conditions over Tromsø and Kharkiv, quasi-periodic fluctuations in foF2 were observed after the sunrise. Oscillations over Tromsø had lower amplitude than over Kharkiv, and were almost completely suppressed after the onset of a strong magnetic disturbance at high latitudes on September 23, 2020. The foF2 values over Tromsø exceeded its values over Kharkiv in a time interval of 10:45 – 12:15 UT. Comparison of the time variation of foF2 over Tromso on a magnetically quiet day, September 22, 2020, and on a magnetically disturbed day, September 23, 2020, showed that the foF2 value for September 23, 2020 from 10:15 to 15:00 UT exceeded the foF2 values for the same period on September 22, 2020. Comparison of the temporal variations in foF2 over Kharkiv on a magnetically quiet day, September 22, 2020, and on a magnetically disturbed day, September 24, 2020, showed that the foF2 value for September 24, 2020 exceeded its value for September 22, 2020 from 03:00 to 04:45 UT and from 07:00 to 13:00 UT. Magnetic disturbances were found to cause a rapid increase in foF2 values both over Kharkiv and Tromsø, which exceeded foF2 values under magnetically quiet conditions, and also led to a significant increase in the relative amplitudes of traveling ionospheric disturbances over Kharkiv.

Influence of following, regular and irregular long waves on wind-wave growth with fetch: an experimental study

A series of experiments were conducted in a wind-wave tank facility in Marseilles (France) to study the effects of preexisting swell conditions (represented by long mechanically-generated waves) on wind-wave growth with fetch. Both monochromatic and irregular (JONSWAP-type) long wave conditions with different values of wave steepness have been generated in the presence of a constant wind forcing, for several wind velocities. A spectral analysis of temporal wave signals combined with airflow measurements allowed to study the evolution of both wave systems with the aim of identifying the interaction mechanisms transportable to prototype scale. In particular, a specific method is used to separate the two wave systems in the measured bimodal spectra. In fetch-limited conditions, pure wind-wave growth is in accordance with anterior experiments, but differs from the prototype scale in terms of energy and frequency variations with fetch. Monochromatic long waves are shown to reduce the energy of the wind-waves significantly, as it was observed in anterior laboratory experiments. The addition of JONSWAP-type long waves instead results in a downshift of the wind-wave peak frequency but no significant energy reduction. Overall, it is observed that the presence of long waves affects the wind-wave energy and frequency variations with fetch. Finally, in the presence of JONSWAP-type long waves, variations of wind-wave energy and peak frequency with fetch appear in close agreement with the wind-wave growth observed at prototype scale both in terms of variations and nondimensional magnitude.

Trouble Underground: Demand Shocks and the Labor Supply Behavior of New York City Taxi Drivers

We investigate the relevance of targeting behavior in the labor supply decisions of New York City Taxi drivers using exogenous and transitory positive changes in labor demand. Exploiting high-frequency variations in taxi demand due to subway service disruptions, we show that drivers work more when earnings opportunities are greater both when they are above and when they are below their income target. Surpassing the target, however, significantly reduces drivers’ labor supply. Estimates imply that drivers’ response to demand shocks is 40$$\%$$ % smaller once they have reached their daily income target. These results suggest that, while drivers’ behavior seems largely consistent with the prediction of a standard model of labor supply, targeting behavior does nevertheless play an essential role in determining drivers’ decisions.

Moving beyond DSM5 and ICD11: Acoustic Analysis for Psychological Stress on Daily-Wage Workers in India during COVID19

Aim: To observe psychological stress in the acoustic samples of daily-wage workers belonging to different states in IndiaMethod: The study was based on the observations obtained from prior work on detecting psychoacoustic detectors of psychological stress. Acoustic samples were obtained from interviews conducted by NDTV over a period of March-May 2020. Spectrogram and Fundamental Frequency variations were used to identify psychological stressResults: Stark differences existed in mean fundamental frequency plots by daily-wage workers and non-stressed individuals. Distinct density variations were also observed in the acoustic samples between the two groups.Conclusion: Psychoacoustic detectors of psychological stress were confirmed in the acoustic samples of daily wage-workers, concluding that daily-wage workers are under dire psychological stress and are susceptible to stress-related disorders.Keywords: psychological stress, acoustic variations, daily-wage workers

EMG Artifacts Removal from Multi-Channel EEG Signals using Multi-Channel Singular Spectrum Analysis

<div><div><div><p>The Electroencephalogram (EEG) is the brain sig- nals which are most normally debased by Electromyogram (EMG) antiquities. The presence of these EMG antiquities covers the necessary information in an EEG signal. In this paper, we have proposed another strategy named as Multi-channel Singular Spectrum Analysis (MSSA) in light of Singular Value Decomposition (SVD) to expel muscle or EMG antiquities from multi-channel EEG signals. At first, the orthogonal eigenvectors of multi-channel data are estimated by performing SVD which are acquired from the covariance matrix . Since the frequency variations of eigenvectors related to EEG signal are quite low when compared to the EMG signal, so we fix some peak frequency threshold to find out the frequencies related to EEG signal, then the frequencies related to EMG signals are suppressed and the artifact free Multi-channel EEG signal is extracted. Finally, our proposed technique is applied on a noisy sinusoidal signals to test the performance of the proposed method and then it is applied on synthetic EEG signals mixed with the EMG artifacts. Simulation results are then compared with Canonical Correlation Analysis (CCA) to show that the proposed method eliminates EMG antiquities more adequately without amending the required data.</p></div></div></div>

EMG Artifacts Removal from Multi-Channel EEG Signals using Multi-Channel Singular Spectrum Analysis

<div><div><div><p>The Electroencephalogram (EEG) is the brain sig- nals which are most normally debased by Electromyogram (EMG) antiquities. The presence of these EMG antiquities covers the necessary information in an EEG signal. In this paper, we have proposed another strategy named as Multi-channel Singular Spectrum Analysis (MSSA) in light of Singular Value Decomposition (SVD) to expel muscle or EMG antiquities from multi-channel EEG signals. At first, the orthogonal eigenvectors of multi-channel data are estimated by performing SVD which are acquired from the covariance matrix . Since the frequency variations of eigenvectors related to EEG signal are quite low when compared to the EMG signal, so we fix some peak frequency threshold to find out the frequencies related to EEG signal, then the frequencies related to EMG signals are suppressed and the artifact free Multi-channel EEG signal is extracted. Finally, our proposed technique is applied on a noisy sinusoidal signals to test the performance of the proposed method and then it is applied on synthetic EEG signals mixed with the EMG artifacts. Simulation results are then compared with Canonical Correlation Analysis (CCA) to show that the proposed method eliminates EMG antiquities more adequately without amending the required data.</p></div></div></div>

RANCANGBANGUN RANGKAIAN INVERTER SPWM UNIPOLAR 1 FASA DENGAN PENGATURAN FREKUENSI OUTPUT

Changing the dc sgnal to ac signal is done for te purpose of load regulations, such as the ac motor speed, heater and lamp. Inverter work is done by ac rectification first and then converted again to a 1 phase ac signal. The ac output signal is a sinosoidal PWM (SPWM) type of unipolar 220 volts from the input 24 volt dc voltage. Unipolar SPWM signal generation is done by a microcontroller with programming. The number of counts (resolutions) of the SPWM signal and the period are set from the amount in the register, can be set to 8 bits or other constants. The power part of the SPWM inverter is the N channel MOSFET bridge circuit H with IR2110 solid state driver. Step transformer as a load while step-up the inverter output voltage. Determination of the output frequency is set through a rotary encoder that can be adjusted up (increment) or down (decrement). There are 5 frequency variations, namely 30, 40, 50, 60 and 70 Hz. To get the inverter efficiency, the type of MOSFET used is chosen to have the type that has a low RDS (on) value and the right driving pulse, according to the switch configuration. Measurement of the output frequency is done by reading the image on the osciloscope. The observations show a frequency value that is almost the same as the constant. The test results show the difference in output voltage which is reduced at a 30 watt load.