Noise Pulses Research Articles

Evaluation of Preview Cues to Enhance Recall of Auditory Sequential Information

ABSTRACT In previous work, an auditory vital sign display of five patients was developed. Sounds denoting the vital signs of each patient were delivered in order, with a special sound for any patient whose vital signs were all normal. Although the display was effective, accuracy decreased as the number of abnormal patients increased. We wondered whether accuracy would improve with a preview sound indicating the number of patients with abnormal vital signs in the upcoming sequence. A 3 (preview cue type) x 4 (number of abnormal patients) mixed design was adopted. Preview cue type (between-subjects) was either time-compressed speech, an abstract sound containing white noise pulses to indicate the upcoming number of abnormal patients, or no preview cue. The number of abnormal patients (within-subjects) was zero, one, two, or three. Results showed that the preview cue did not improve non-clinician participants’ ability to identify the location in the sequence or the vital signs of patients with abnormal vital signs. Response accuracy dropped as the number of patients with abnormal vital signs increased. Although it did not hurt performance, the current preview cue did not improve performance. Adding a preview cue may improve performance, but not with the current design.

Detecting hidden transient events in noisy nonlinear time-series.

The information impulse function (IIF), running Variance, and local Hölder Exponent are three conceptually different time-series evaluation techniques. These techniques examine time-series for local changes in information content, statistical variation, and point-wise smoothness, respectively. Using simulated data emulating a randomly excited nonlinear dynamical system, this study interrogates the utility of each method to correctly differentiate a transient event from the background while simultaneously locating it in time. Computational experiments are designed and conducted to evaluate the efficacy of each technique by varying pulse size, time location, and noise level in time-series. Our findings reveal that, in most cases, the first instance of a transient event is more easily observed with the information-based approach of IIF than with the Variance and local Hölder Exponent methods. While our study highlights the unique strengths of each technique, the results suggest that very robust and reliable event detection for nonlinear systems producing noisy time-series data can be obtained by incorporating the IIF into the analysis.

Асимптотически робастный инвариантный алгоритм демодуляции DPSK-сигналов при воздействии внешних помех с априорно неопределенными параметрами

The study aims at synthesizing an asymptotically robust invariant demodulation algorithm for DPSK signals with arbitrary modulation multiplicity used in aircraft communication systems and observed against the background of noise with an unknown probability distribution and a noise complex with a priori uncertain parameters. The analysis of the efficiency of the proposed algorithm is carried out by a computer simulation modeling. The algorithm implies automatic detection and rejection of narrowband pulse noise. This type of interference is typical for radio-navigation systems. It has been shown that the narrowband pulse noise should be eliminated if the signal-to-interference ratio becomes less than -10 dB. The use of the asymptotic robustness principle ensures the stability of the algorithm characteristics to changes in the character of the noise probability distribution density. It was found that the joint application of narrowband pulse interference elimination and the asymptotically robust approach provides reliable demodulation performance both when receiving against the background Gaussian noise and under the action of pulse interference and noise with "heavy tails". In addition, it has been shown that the use of signals with differential phase modulation, direct sequence spread spectrum, and the sidelobe levels of less than 10% effectively suppresses interference caused by multipath signal propagation.

Generation of high performance optical chirped pulse for distributed strain sensing application with high strain accuracy and larger measurement range.

A photonic approach for generating low frequency drifting noise, arbitrary and large frequency chirping rate (FCR) optical pulses based on the Kerr effect in the nonlinear optical fiber is theoretically analyzed and experimentally demonstrated. Due to the Kerr effect-induced sinusoidal phase modulation in the nonlinear fiber, high order Kerr pulse with a large chirping rate is generated. In the concept-proof experiments, the FCR of the mth Kerr pulse has been significantly improved by a factor of 2m+1. In addition, dynamic strain measurement along with a random fiber grating array (RFGA) sensor by using different order Kerr pulse is carried out for demonstrating a large strain measurement range with lower uncertainty sensing capability. Benefiting from the use of a single laser source and large FCR Kerr pulse, the system exhibits a 3.9 µɛ static strain measurable range, 0.24 µɛ measurement uncertainty by using -4th order Kerr pulse that has an FCR up to 0.8 GHz/ns. Note that the FCR of the chirped pulse could be further enhanced by using larger FCR chirped pulse seed or choosing higher order Kerr pulses.

Алгоритм обробки сигналів для вертолітного широкосмугового шумового некогерентного радіовисотоміру

The algorithm for a helicopter or an unmanned aerial vehicle flight altitude measuring based on the processing of broadband and ultra-wideband pulsed stochastic signals has been synthesized for the first time by the maximum likelihood method. When formulating the initial data, mathematical models of the probing signal and the received observation are given, taking into account both various options for input path implementation, which impose restrictions on the observation equation form, and the geometry of the problem. When solving the problem, the statistical characteristics of the given models were found and studied. The calculated observation correlation function contains information about both the signal delay time and the radio pulse envelope, which makes it possible to obtain the algorithm for desired altitude parameter determining by one of two ways: differentiating the likelihood functional by the delay time or by the radio pulse envelope. At the same time, for the first time, the inversion equation for the statistical characteristics of the studied non-stationary processes in the frequency domain has been obtained. Such processes arise due to the presence of a radio pulse envelope. An important feature of the solved synthesis problem is a noise pulse transmitter use that implements the function of the underlying surface sounding, as well as taking into account the fact of the signal structure destruction during its radiation, propagation and reflection. Such a destruction of the signal shape doesn’t make it impossible to synthesize a radar with internal coherent processing algorithms when working on one receiving antenna and requires the search for other signal processing options. The use of a non-deterministic signal in the system also complicates the formalization of the delay time parameter in the likelihood function, since in this case the reference signal cannot be represented as a model or an analytical equation. Following the synthesized algorithm, a simulation model of a pulsed radar with a stochastic probing signal has developed and the results of its modeling are presented. The obtained output effect of the system fully corresponds to the classical theoretical calculations.

QUBIC IV: Performance of TES bolometers and readout electronics

A prototype version of the Q & U bolometric interferometer for cosmology (QUBIC) underwent a campaign of testing in the laboratory atAstroparticle Physics and Cosmology laboratory in Paris (APC). The detection chain is currently made of 256 NbSi transition edge sensors (TES) cooled to 320 mK. The readout system is a 128:1 time domain multiplexing scheme based on 128 SQUIDs cooled at 1 K that are controlled and amplified by a SiGe application specific integrated circuit at 40 K. We report the performance of this readout chain and the characterization of the TES. The readout system has been functionally tested and characterized in the lab and in QUBIC. The low noise amplifier demonstrated a white noise level of 0.3 nV/√Hz. Characterizations of the QUBIC detectors and readout electronics includes the measurement of I-V curves, time constant and the noise equivalent power. The QUBIC TES bolometer array has approximately 80% detectors within operational parameters. It demonstrated a thermal decoupling compatible with a phonon noise of about 5 × 10-17 W/√Hz at 410 mK critical temperature. While still limited by microphonics from the pulse tubes and noise aliasing from readout system, the instrument noise equivalent power is about2 × 10-16 W/√Hz, enough for the demonstration of bolometric interferometry.

Lock-in functional near-infrared spectroscopy for measurement of the haemodynamic brain response.

Here we show a method of the lock-in amplifying near-infrared signals originating within a human brain. It implies using two 90-degree rotated source-detector pairs fixed on a head surface. Both pairs have a joint sensitivity region located towards the brain. A direct application of the lock-in technique on both signals results in amplifying common frequency components, e.g. related to brain cortex stimulation and attenuating the rest, including all components not related to the stimulation: e.g. pulse, instrumental and biological noise or movement artefacts. This is a self-driven method as no prior assumptions are needed and the noise model is provided by the interfering signals themselves. We show the theory (classical modified Beer-Lambert law and diffuse optical tomography approaches), the algorithm implementation and tests on a finite element mathematical model and in-vivo on healthy volunteers during visual cortex stimulation. The proposed hardware and algorithm complexity suit the entire spectrum of (continuous wave, frequency domain, time-resolved) near-infrared spectroscopy systems featuring real-time, direct, robust and low-noise brain activity registration tool. As such, this can be of special interest in optical brain computer interfaces and high reliability/stability monitors of tissue oxygenation.

NOISE INTENSITY, BLOOD PRESSURE, AND PULSE RATE IN TEXTILE INDUSTRY WORKERS

<p><strong>Background: </strong>Noise intensity that exceeds Threshold Limit Value (TLV) can give impacts on non-auditory on the workers in a factory, in the form of an increase in blood pressure and pulse rate. Currently, health problems due to noise have caused the company’s total loss to reach 300 billion dollars due to absenteeism rate, decreased productivity, and treatment for occupational diseases. Research in Indonesia, especially the textile industry in the city of Surakarta, shows that noise from weaving machines with an intensity above 100 dBA affects blood pressure and pulse rate. This research was conducted at textile industry in Surakarta, one of the largest textile companies in Surakarta where the company has not been able to overcome the problem of noise intensity that exceeds the TLV which has the potential to cause blood pressure and pulse disturbances, and even decreased hearing function. This study aims to determine the relationship between noise intensity with blood pressure and pulse rate in textile industry workers. </p><p><strong>Method:</strong> This research is a correlation study, which is connecting the measurement variables of noise intensity with blood pressure and pulse rate. The sample in this study were 30 female workers in the weaving division who met the inclusion and exclusion criteria. The instruments used in measuring noise were sound level meters and sphygmomanometers. Data analysis used the Pearson correlation test to determine the relationship between noise intensity with blood pressure and pulse rate disturbances.</p><p><strong>Result:</strong> The study showed significant correlation between noise intensity and pulse rate with a <em>p </em>value of 0.029, but noise intensity with blood pressure disturbances does not correlate, with a <em>p </em>value of 0.443.</p><p><strong>Conclusion: </strong>There is a relationship between noise intensity and pulse rate of the workers in a factory.</p><p> </p>

High Device Performances and Noise Characteristics of AlGaN/GaN HEMTs Using In Situ SiCN and SiN Cap Layer

We fabricated and characterized AlGaN/GaN high-electron mobility transistors (HEMTs) with a nano-sized in situ cap layer (one is a silicon carbon nitride (SiCN) layer, and the other is a silicon nitride (SiN) layer) comparing to the conventional device without an in situ cap layer. The pulse characteristics and noise behaviors for two devices with in situ cap layers are much superior to those of the reference device without a cap layer, which means that the in situ cap layer effectively passivates the AlGaN surface. On the other hand, the device with an in situ SiCN cap layer showed the excellent device characteristics and noise performances compared to the other devices because of the reduced positive ionic charges and enhanced surface morphology caused by carbon (C) surfactant atoms during the growth of the SiCN cap layer. These results indicate that the AlGaN/GaN HEMT with the in situ SiCN cap layer is very promising for the next high-power device by replacing the conventional HEMT.

Masking Noise Pulses When Collecting a Charge from the Tracks of Single Ionizing Particles in a Majority Element Based on CMOS NAND Logic

Masking Noise Pulses When Collecting a Charge from the Tracks of Single Ionizing Particles in a Majority Element Based on CMOS NAND Logic

Different paradigms of transcranial electrical stimulation improve motor function impairment and striatum tissue injuries in the collagenase-induced intracerebral hemorrhage rat model

BackgroundIn the horizon of therapeutic restrictions in intracerebral hemorrhage (ICH), recently, non-invasive transcranial electrical stimulation (tES) has achieved considerable prosperities. Translational studies have postulated that transcranial direct current stimulation (tDCS) and the other types of tES remain potentially a novel therapeutic option to reverse or stabilize cognitive and motor impairments.ObjectiveThe aim of this study was to comparatively evaluate the effects of the four main paradigms of tES, including tDCS, transcranial alternating (tACS), pulsed (tPCS), and random noise (tRNS) stimulations on collagenase-induced sensorimotor impairments and striatum tissue damage in male rats.MethodsTo induce ICH, 0.5 μl of collagenase was injected into the right striatum of male Sprague Dawley rats. One day after surgery, tES, was applied to the animals for seven consecutive days. Motor functions were appraised by neurological deficit score, rotarod, and wire hanging tests on the day before surgery and postoperative days 3, 7, and 14. After behavioral tests, brain tissue was prepared appropriately to perform the stereological evaluations.ResultsThe results indicated that the application of the four tES paradigms (tDCS, tACS, tRNS, and tPCS) significantly reversed motor disorders in collagenase-induced ICH groups. Further, the motor function improvement of tACS and tRNS receiving rats in wire-hanging and rotarod tests were higher than the other two tES receiving groups. Structural changes and stereological assessments also confirmed the results of behavioral functions.ConclusionOur findings suggest that in addition to tDCS application in the treatment of ICH, other tES paradigms, especially tACS and tRNS may be considered as add-on therapeutic strategies in stroke.

Machine learning method for calculating mode-locking performance of linear cavity fiber lasers

As a commonly used pulse light source, fiber mode-locked lasers are widely used in communication, frequency comb, nonlinear optics and other fields. Although people can accurately predict and analyze the performance of mode-locked pulse with given parameters of fiber laser by existing theories and calculation methods, it is difficult to analyze the mode-locked performance of fiber laser with multi-parameter changes by traditional methods. In this paper, we use machine learning technology to put forward a new view on this problem. Firstly, we use an artificial neural network (ANN) to judge whether a small noise pulse can evolve into a stable mode-locked state in the linear cavity fiber laser. Then, the time domain function of sample pulse is expanded by Fourier series. We use the Fourier coefficients as the network output and train another ANN that can predict the pulse shape quickly and accurately. Finally, we demonstrate how to use the genetic algorithm and the trained network to compute the parameters of the fiber laser when the given pulse width is known. The authors believe that the theoretical ideas and computational models presented in this work have great potential in the dynamics research and fabrication of fiber lasers.

Partial Discharge Pulse Segmentation Approach of Converter Transformers Based on Higher Order Cumulant

As one of the most effective methods to detect the partial discharge (PD) of transformers, high frequency PD detection has been widely used. However, this method also has a bottleneck problem; the biggest problem is the mixed pulse interference under the fixed length sampling. Therefore, this paper focuses on the study of a new pulse segmentation technology, which can separate the partial discharge pulse from the sampling signal containing impulse noise so as to suppress the interference of pulse noise. Based on the characteristics of the high-order-cumulant variation at the rising edge of the pulse signal, a method for judging the starting and ending time of the pulse based on the high-order-cumulant is designed, which can accurately extract the partial discharge pulse from the original data. Simulation results show that the location accuracy of the proposed method can reach 94.67% without stationary noise. The field test shows that the extraction rate of the PD analog signal can reach 79% after applying the segmentation method, which has a great improvement compared with a very low location accuracy rate of 1.65% before using the proposed method.

A Radar Signal Deinterleaving Method Based on Semantic Segmentation with Neural Network

Radar signal deinterleaving is an important part of electronic reconnaissance. This study proposes a new radar signal deinterleaving method based on semantic segmentation, which we call "semantic segmentation deinterleaving" (SSD). We select representative sequence modeling neural network (NN) architectures and input the difference of time of arrival of the pulse stream into them. According to semantics contained in different radar signal types, each pulse in the pulse stream is marked according to the category of semantics contained, and radar signals are deinterleaved. Compared to the traditional deinterleaving method, the SSD method can adapt to complex pulse repetition interval (PRI) modulation environments without searching the PRI or PRI period. Multiple rounds of search and merging operation are not required for radar signals with multiple pulses in a period. Compared to other deinterleaving methods based on NNs, the SSD method does not need to digitize the data and train a network for each target type. The SSD method also does not need to iterate input and output data. The proposed method has high robustness to pulse loss and noise pulses. This research also shows that recurrent NNs still have more advantages than convolutional NNs in this sequence modeling task.

Noncontinuous noise calculated by room response function determined by experimental data

Purpose: Experimental determination of the response room function and its use to estimate the acoustic conditions in rooms with noncontinuous noise sources.Methodology/approach: The detailed parameter calculation of noncontinuous sound fields using the response room function, which is the room response to pulse excitation. The response function can be calculated by analytical or numerical methods and by experimental measurements in production conditions the energy attenuation when a constant noise source is switched off.Findings: Noncontinuous noise has a negative impact on health. The effective noise reduction is determined by the complete and accurate analysis of its energy parameters. The noncontinuous noise estimation based on equivalent levels does not meet the requirements, especially when pulsed noise sources are active. The experimental technique is proposed for the response function calculation and its use in evaluating the noise conditions in rooms with noncontinuous noise sources.Practical implications: The experimental determination of the response function to pulse excitation allows studying the acoustic processes in rooms for the formation of noise conditions when analytical methods cannot be used. The experimentally obtained response function makes it possible to solve problems of changing the noise conditions in rooms with noncontinuous noise sources.

Sequential extraction and recognition of pulse group structure for multi‐function radar

The structure design and switching regulation of pulse groups in multi-function radars (MFRs) are closely related to the work mode. The sequential extraction and recognition of MFR pulse group structure is a fundamental task to analysing and interpreting the work modes and behaviour intentions of an MFR. In this study, the temporal structure of MFR pulse group is expressed hierarchically, which is intensively modelled based on regular grammar. Besides, a corresponding hierarchical automaton is established to sequentially extract and recognise the MFR pulse group structure in pulse train. The hierarchical automaton used for pulse group recognition has a two-layer structure. The bottom layer of the hierarchical automaton realises the sequential input of pulses and recognition of pulse subgroups, and the sequential input of pulse subgroups and recognition of pulse groups are realised at the top layer. The simulation results demonstrate that the proposed method performs satisfyingly in recognising the pulse group structure and is robust to not only pulse noises but also to the emitter number and pulse group scale.

Dynamics and timing-jitter of regenerative RF feedback assisted resonant electro-optic frequency comb

Optical frequency combs have impacted a wide range of applications. The optical cavity assisted resonant electro-optic (EO) comb features broad spectral bandwidth and deterministic repetition-rate. However, the optical pulse timing-jitter is limited by the phase noise of the external RF drive source. To overcome this limitation at high repetition-rate, a regenerative RF feedback assisted resonant EO comb has been experimentally developed, which shows low phase noise of the regenerative RF drive signal. However, yet to date, the nonlinear dynamics and timing-jitter of the resonant EO comb coupled with a regenerative RF feedback loop remain unexplored. Here, for the first time, we quantitatively investigate the dynamics and timing-jitter of the resonant EO comb generation coupled with an optoelectronic oscillator (OEO). Our model indicates the detuning of the seed laser and EO comb cavity resonance determines the nonlinear feedback RF gain of OEO. Numerical simulations reveal the emergence of the bifurcation behaviors of the regenerative RF signal and the distinct EO comb formation dynamics with the increasing feedback RF gain of OEO, which provide the guidelines to achieve stable regenerative resonant EO comb. Moreover, in the presence of the noisy nonlinear feedback RF gain induced by the laser-cavity detuning fluctuations, our timing-jitter model predicts the seed laser frequency noise will be converted to the regenerative RF phase noise and optical pulse timing-jitter under the stable oscillation state of OEO. We highlight the mechanism of the transduction of laser frequency noise to the RF phase noise is differ from the Mach-Zehnder modulator based OEO. Experimentally, we attain a 10 GHz resonant EO comb generation with phase noise of −130 dBc/Hz at 10 kHz offset for the regenerative 10 GHz RF signal and optical pulse timing-jitter of 52.8 fs with an integral range from 100 Hz to 1 MHz. The experimental results agree well with the theoretical models. Our findings offer the solid guidelines for the design of the regenerative RF feedback assisted stable resonant EO comb with an optimized timing-jitter performance.

Pulse Deinterleaving for Multifunction Radars With Hierarchical Deep Neural Networks

Multi-function radars (MFRs) work with pulse groups, and pulses in different groups are weakly correlated, which greatly increases the difficulty for MFR pulse deinterleaving, especially in cases of significant data noises. At present, no relevant research results have been reported to address this problem. In this article, a hierarchical deep learning model will be established to describe the sequential patterns of pulse trains from MFRs. The bottom layer of the model represents discrete pulse groups with continuous vectors, which describes the temporal pattern of pulse groups and makes them machine readable. The top layer uses a recursive neural network to mine the sequential pattern between consecutive pulse groups. The two layers are then synthesized to form a hierarchical model, which is able to describe the semantic correlations between different pulses within MFR pulse trains, and the parameters of subsequent pulse groups and their inner pulses can be predicted based on preceding pulses. Based on the hierarchical model, this article proposes an iterative pulse deinterleaving method and a parallel one for MFRs. Simulation results demonstrate that, the proposed methods perform satisfyingly in separating interleaved pulses from radars of the same or different types, and they are robust to significant pulse noises.

Narwhals react to ship noise and airgun pulses embedded in background noise.

Anthropogenic activities are increasing in the Arctic, posing a threat to niche-conservative species with high seasonal site fidelity, such as the narwhal Monodon monoceros. In this controlled sound exposure study, six narwhals were live-captured and instrumented with animal-borne tags providing movement and behavioural data, and exposed to concurrent ship noise and airgun pulses. All narwhals reacted to sound exposure with reduced buzzing rates, where the response was dependent on the magnitude of exposure defined as 1/distance to ship. Buzzing rate was halved at 12 km from the ship, and whales ceased foraging at 7–8 km. Effects of exposure could be detected at distances > 40 km from the ship.At only a few kilometres from the ship, the received high-frequency cetacean weighted sound exposure levels were below background noise indicating extreme sensitivity of narwhals towards sound disturbance and demonstrating their ability to detect signals embedded in background noise. The narwhal's reactions to sustained disturbance may have a plethora of consequences both at individual and population levels. The observed reactions of the whales demonstrate their auditory sensitivity but also emphasize, that anthropogenic activities in pristine narwhal habitats needs to be managed carefully if healthy narwhal populations are to be maintained.

Highly coherent and multi-octave mid-infrared supercontinuum generations in a reverse-strip AlGaAs waveguide with three zero-dispersion wavelengths.

In this paper, a reverse-strip AlGaAs waveguide with three zero-dispersion wavelengths (ZDWs) is designed. The corresponding three ZDWs are located at 3.74, 6.56, and 8.89 µm. The nonlinearity coefficient of the proposed reverse-strip AlGaAs waveguide is calculated as 2.09W-1m-1 at wavelength 4.9 µm. The effects of pump pulse parameters, waveguide length, and noise coefficient on the nonlinear dynamics of supercontinuum (SC) generation are investigated. When the hyperbolic secant pump pulse with a wavelength of 4.9 µm, peak power of 900 W, and duration of 100 fs is launched into the proposed waveguide and propagated after a 3 mm length, highly coherent and multi-octave mid-infrared (MIR) SC spanning from 2.2 to 14.5 µm (more than 2.7 octaves, at -40dB level) is generated. Finally, a possible fabrication process of the reverse-strip AlGaAs waveguide is introduced. Our research results have important applications in MIR photonics, MIR spectroscopy, optical precision measurement, and more.