Analysis of tribological behaviour of titanium nitride-coated stainless steel with the use of wavelet-based methods

Tribological behaviour is characterized by the strong nonlinear effects in its response, which are hardly identified with standard signal processing methods. One of the challenges in the analysis of wear phenomena is identification of its propagation and potential quantification. In our study, we propose application of wavelet-based methods, i.e. continuous wavelet transform and scale index for analysis of the dynamical response in the tribological pair. The analysed parameter will be the coefficient of friction, which is slightly changing with wear of the tribological pair. The performed analysis shows the variable response of the system in each considered state. Moreover, results obtained with wavelets are useful for its determination. The proposed methods can be particularly useful in the transportation applications, where the quantification of the friction force between the sliding counterparts is a crucial parameter, responsible for the power losses. Early and efficient identification of wear allows to predict damage and avoid undesirable downtime or time-consuming exchange of a worn out part.

Modelling visibility judgments using models of decision confidence

How can we explain the regularities in subjective reports of human observers about their subjective visual experience of a stimulus? The present study tests whether a recent model of confidence in perceptual decisions, the weighted evidence and visibility model, can be generalized from confidence to subjective visibility. In a postmasked orientation identification task, observers reported the subjective visibility of the stimulus after each single identification response. Cognitive modelling revealed that the weighted evidence and visibility model provided a superior fit to the data compared with the standard signal detection model, the signal detection model with unsystematic noise superimposed on ratings, the postdecisional accumulation model, the two-channel model, the response-congruent evidence model, the two-dimensional Bayesian model, and the constant noise and decay model. A comparison between subjective visibility and decisional confidence revealed that visibility relied more on the strength of sensory evidence about features of the stimulus irrelevant to the identification judgment and less on evidence for the identification judgment. It is argued that at least two types of evidence are required to account for subjective visibility, one related to the identification judgment, and one related to the strength of stimulation.

Метод трансляционного переноса для оценки стабильности нестационарного квантового стандарта частоты

Continuous wavelet transform is used to analyze the operation of a non-stationary signal of a quantum frequency standard. The method of translational transfer is proposed, with the help of which the boundary phenomena in this transformation are eliminated. The spectral integrals of the quantum frequency standard signal in various frequency ranges are calculated. A wavelet dispersion is introduced, which makes it possible to determine the moments of time when the signal fluctuations are the strongest. The comparison of the wavelet variance with the usual variance and with the Allen variance is carried out.

Cyclostationary Approach for Instabilities Detection and Condition Monitoring of Centrifugal Compressor

This study intends to explore the capabilities of the cyclostationary approach for instabilities detection and operating conditions monitoring of centrifugal compressors. Cyclostationary approach offers powerful signal analysis methods, applicable to different processes. It was proven useful for analysis of vibration, acoustic and pressure data for systems exhibiting periodicity. Cyclostationarity has been used for extracting subtle changes between cycles of the periodic signal which could be used for condition monitoring. Recent research focuses on employing this method for fault indication. Cyclostationary approach has not been extensively used in the field of turbomachinery, except for a few cases when it was proven to give a better insight into flow structure than standard signal processing techniques and allow for the detection of instabilities in flow systems. Thus, the cyclostationary approach may be suitable for instabilities detection and condition monitoring in centrifugal compressors. This paper exploits various techniques employing a cyclostationary framework for instabilities detection and operating conditions monitoring with the use of pressure signals from the low-speed centrifugal compressor. The most prospective cyclostationarity-based indicators are applied for the detection of instabilities. Due to a lack of second-order cyclostationarity, the study confines to the analysis of first-order cyclostationarity strongly exhibited in the compressor pressure signal. First-order cyclostationarity analysis provides an indication of instabilities and working conditions differentiation, but due to time-domain sampling, it is not fully robust and reliable. The highest potential is perceived in the cyclostationary approach use to extract changes between cycles. Different measures of change in variability could serve as a valuable indicator of instabilities.

A zero-cost attention-based approach to promote cleaner streets

In an effort to inform interventions targeting littering behaviour, we estimate how much a change in trash-bag colour increases trash can visibility in Paris. To that end, we apply standard Signal Detection techniques to test how much changing trash-bag colour from grey to red affects subjects' detection rates. In three pre-registered studies (total N = 922), we find that changing trash bag colour from grey to red translates into a 28% increase in the perceived number of bins. This means that a zero-cost change of trash-bag colour from grey to red is equivalent to installing 8,400 additional bins in the city ofParis, in terms of perceived density. Replication studies investigating additional colour changes show that changing the colour from grey to either green or blue further increases visibility, with blue exhibiting the highest increase in visibility.

A window of subliminal perception

Under labels such as unconscious processing and subliminal perception, identification of stimuli falling below the subjective threshold has been found remarkably accurate in some experiments while completely at chance in others. Here, we first demonstrate the existence of a window of subliminal perception in humans using different experimental paradigms and analysis methods. We then show that the standard signal detection theory (SDT) model is unable to accounts for this window and extend it until it is. We finally compare a range of models on empirical data. The models performing best are notable for their absence of hierarchical levels, indicating that the window could be a base property of any phenomenally conscious system. The models further explain previously incompatible findings in the literature, and they allow for estimations of peaks in subthreshold perception across the spectrum of stimulus saliency, which may be used in further studies of subliminal perception.

Performance analysis of the Karhunen–Loève Transform for artificial and astrophysical transmissions: denoizing and detection

ABSTRACT In this work, we propose a new method of computing the Karhunen–Loève Transform (KLT) applied to complex voltage data for the detection and noise level reduction in astronomical signals. We compared this method with the standard KLT techniques based on the Toeplitz correlation matrix and we conducted a performance analysis for the detection and extraction of astrophysical and artificial signals via Monte Carlo (MC) simulations. We applied our novel method to a real data study-case: the Voyager 1 telemetry signal. We evaluated the KLT performance in an astrophysical context: our technique provides a remarkable improvement in computation time and MC simulations show significant reconstruction results for signal-to-noise ratio (SNR) down to −10 dB and comparable results with standard signal detection techniques. The application to artificial signals, such as the Voyager 1 data, shows a notable gain in SNR after the KLT.

Wideband centimetre range detector

An experimental study of the diode detector of the centimeter wavelength range has been carried out. A brief description of the circuit and design is given. The experiment was carried out on an installation containing a standard signal generator, a digital oscilloscope, a power supply, and a offset panel. The results of the experiment are the amplitude and amplitude-frequency characteristics of the detector. The following parameters have been shown to be achieved: operating frequency range of at least 8-18 GHz, voltage sensitivity of at least 100 μV / μW, dynamic range of input signals at least 35 dB, voltage sensitivity unevenness of no more than 1.6 dB.