Band Signals Research Articles

An interpretable anti-noise convolutional neural network for online chatter detection in thin-walled parts milling

Chatter is a notoriously unstable phenomenon that can adversely affect both surface quality and machining efficiency. To achieve high-performance machining, the development of online chatter detection is of paramount importance. Nevertheless, changes in chatter frequency with cutting position and noise interference during the thin-walled parts milling process present significant challenges to chatter detection. To tackle this issue, an adaptive frequency band attention module (AFBAM) is designed, which is characterized by not relying on prior knowledge (namely modal parameters, frequency spectrum analysis, etc.), and adaptively enhances the frequency band containing abundant chatter information and reduces noise interference by learning time-frequency domain characteristics of signals. After AFBAM highlights the relevant frequency band of input signal, a discriminative feature attention module (DFAM) is constructed to adaptively recalibrate feature responses of each convolutional layer utilizing the global information. DFAM enhances relevant features and suppresses irrelevant features, thus improving the discriminative feature learning and redundant information suppression abilities of network. In addition, both AFBAM and DFAM exhibit clear physical interpretability, which improves the interpretability of network. Based on AFBAM and DFAM, an interpretable anti-noise convolutional neural network for online chatter detection, named AD-CNN, is established. Milling experiments with pocket-shaped thin-walled parts are conducted under different cutting parameters. The results show that the proposed method enables better detection accuracy and anti-noise ability than other state-of-the-art methods. Furthermore, visualization analysis of AFBAM and DFAM brings new insights into the interpretability of convolutional neural network in the field of chatter detection.

Predicting rock-paper-scissors choices based on single-trial EEG signals.

Decision prediction based on neurophysiological signals is of great application value in many real-life situations, especially in human-AI collaboration or counteraction. Single-trial analysis of electroencephalogram (EEG) signals is a very valuable step in the development of an online decision-prediction system. However, previous EEG-based decision-prediction methods focused mainly on averaged EEG signals of all decision-making trials to predict an individual's general decision tendency (e.g., risk seeking or aversion) over a period rather than on a specific decision response in a single trial. In the present study, we used a rock-paper-scissors game, which is a common multichoice decision-making task, to explore how to predict participants' single-trial choice with EEG signals. Forty participants, comprising 20 females and 20 males, played the game with a computer player for 330 trials. Considering that the decision-making process of this game involves multiple brain regions and neural networks, we proposed a new algorithm named common spatial pattern-attractor metagene (CSP-AM) to extract CSP features from different frequency bands of EEG signals that occurred during decision making. The results showed that a multilayer perceptron classifier achieved an accuracy significantly exceeding the chance level among 88.57% (31 of 35) of participants, verifying the classification ability of CSP features in multichoice decision-making prediction. We believe that the CSP-AM algorithm could be used in the development of proactive AI systems.

High modulation laser systems integrated with hybrid pulse generators for high speed fiber transmission systems

Abstract This study has simulated the high modulation laser systems integrated with hybrid pulse generators for high speed fiber transmission systems. The directly modulated laser with raised cosine/Gaussian pulse generators are employed for ultra-high data rates for modified multi band range applications. The total estimated light power after fiber cable system is demonstrated based on electro-absorption, phase, and single drive MZM measured modulators. The light base band signal and noise signal configuration is clarified after fiber cable system based on various proposed modulators. The degree of signal polarization configuration is studied after fiber cable system based on various modulators. Signal power level with Q, BER, signal eye height, and the total estimated electrical modulated signal power are evaluated after receiver system after receiver side based on proposed modulators.

WebRTC over 5 G: A Study of Remote Collaboration QoS in Mobile Environment

The increasing demand for remote collaboration and remote working has become crucial to daily life owing to the Covid-19 pandemic and the development of internet-based video distribution services. Furthermore, low-latency remote collaboration, such as teleoperation and support applications designed for in-vehicle environments, has gained considerable attention. The 5 G technology is considered as a key infrastructure for remote collaboration. This study aimed to evaluate the actual 5 G capability to achieve high quality of service (QoS) for remote collaboration. We designed and implemented a measurement tool to monitor the QoS of remote collaboration under real-world 5 G conditions. We performed measurements encompassing the various 5 G frequency bands. During these experiments, we employed various tools to obtain detailed mobile signal conditions to analyze the relationship between various environmental factors (e.g. signal quality, band, handoff, geographic conditions, and mobility) and the QoS performance of remote collaboration in a real-world 5 G environment. This study elucidated the correlation between the WebRTC performance and various environmental factors as well as the performance improvement potential by leveraging the communication technologies of multiple mobile carriers. The collected data has been made publicly available to foster research on QoS and 5 G.

High efficiency coupling fibers with different types of photo detectors for the management of noise multiplication and efficient bandwidth

Abstract This work has clarified the high efficiency coupling fibers with different types of photo detectors for the management of noise multiplication and efficient bandwidth. As well as the study of the base band signal to noise base band form ratios are clarified with EDFA base band amplifier length variations. Max Q form factor with EDFA amplifier base band length variations is also demonstrated. The optimum base band electrical signal form power is simulated with EDFA base band amplifier length variations. The simulative study of Ge and InGaAs PIN photo-detectors performance evaluation are studied in the presence of the soliton transmission fiber systems. The dispersion management by the soliton technique to reach the value around zero. The max base band signal power form is clarified versus time based Ge and InGaAs PIN photo-detectors. Total base band electrical power form based Ge and InGaAs PIN photo-detectors are demonstrated. Max signal base form power amplitude band is simulated with the spectral base band frequency based Ge and InGaAs PIN photo-detectors. The max signal base form power amplitude band is studied versus time based Ge PIN photo-detectors.

Assessing cognitive workloads of assembly workers during multi-task switching

Complex assembly tasks with multiple manual operations and steps often require rapid judgment and action under time pressure and cause most human-related errors. The task switching and action transitions are major sources of these errors. This study intends to implement an electroencephalography (EEG) approach to quantitatively evaluate the mental workload during task switching and transition. The time–frequency and spectrum analysis were utilized to compute and reflect the task demand between the intervals of individual tasks. This study developed an experiment to validate the proposed assessment approach and benchmark the results with the National Aeronautics and Space Administration task load index (NASA-TLX) subjective evaluation scale analysis. The results show that the average value of the power spectral densities (PSDs) of the gamma band signal of the AF4 channel and the beta band signal of Channel F3 show distinctive signal patterns among task stages and intervals. During the interval between the idling stage and the part selection stage, the peak of the PSD envelope increased from 18 to 27 Hz, suggesting advanced cognition increases the mental workload of the interval between different tasks. Therefore, the task switching period cannot be regarded as rest and need to be optimized with better task organization.

Оптическая гильберт-томография газовых струй

Hilbert-optics and signal conversion methods form the basis for modern information and measurement technologies. The Hilbert transform in the frequency space is physically reduced to a certain phase transformation of the Fourier spectrum of the signal in a wide frequency band. The article discusses the possibility of Hilbert tomography using the example of studying the isothermal flow of a freon-22 jet. An optical system based on the IAB-463M modernized wide-aperture shadow device has been developed. This system makes it possible to perform four-angle diagnostics of the studied phase object using probing light beams. The beams orientation is defined at angles of 0, π/2, π/4 and 3π/4 to the optical axis of the shadow device. This makes it possible to simultaneously register all four tomographic projections in the form of Hilbert images in separate sections of the CCD-matrix of the high-speed camera. The use of the iterative Gershberg-Papulis scheme for finding the parameters of the medium under study based on Hilbert tomography data is further proposed. This algorithm for reconstructing a function from its Radon data obtained by a limited number of projections consists in iterative transitions from estimating the function in the Fourier plane to its estimate in the spatial domain, corrected based on a priori information. The spectrum of the restored function is determined on the entire frequency plane as a result of an iterative process, which makes it possible to determine the values of the required function.

High-precision non-invasive RBC and HGB detection system based on spectral analysis.

Non-invasive blood composition analysis based on dynamic spectrum (DS) theory has gained significant attention due to its non-invasive, simple, and fast performance. However, most of the multi-wavelength photoplethysmography (PPG) detection devices used to obtain DS are composed of halogen light sources and spectrometers and cannot detect effective PPG signals in the visible light short band (400-620nm), which limits the detection accuracy of blood components with significant absorption spectral differences in that band. Therefore, this paper designs a multi-wavelength spectral acquisition system that can measure high signal-to-noise ratio (SNR > 65dB) PGG signals at wavelengths of 405, 430, 450, 505, 520, and 570nm and combines this system with a halogen lamp spectrometer acquisition system for non-invasive blood component detection. Furthermore, this paper collects the DS of 272 subjects with the combined system and establishes a predictive model for DS with the content of red blood cell (RBC) and hemoglobin (HGB) components. The results show that, compared with the halogen lamp spectrometer acquisition system, the correlation coefficient (Rp) of RBC and HGB prediction model established by the combined system has increased by 0.0619 and 0.0489, respectively, and the root mean square error (RMSE) has decreased by 0.08 1e12/L and 0.85g/L, which confirm the feasibility of the designed multi-wavelength spectrum acquisition system to enhance the accuracy of blood component detection.

Differences in generation and maintenance between ictal and interictal generalized spike-and-wave discharges in childhood absence epilepsy: A magnetoencephalography study

PurposeChildhood absence epilepsy (CAE) is characterized by impaired consciousness and distinct electroencephalogram (EEG) patterns. However, interictal epileptiform discharges (IEDs) do not lead to noticeable symptoms. This study examines the disparity between ictal and interictal generalized spike-and-wave discharges (GSWDs) to determine the mechanisms behind CAE and consciousness. MethodsWe enrolled 24 patients with ictal and interictal GSWDs in the study. The magnetoencephalography (MEG) data were recorded before and during GSWDs at a sampling rate of 6000 Hz and analyzed across six frequency bands. The absolute and relative spectral power were estimated with the Minimum Norm Estimate (MNE) combined with the Welch technique. All the statistical analyses were performed using paired-sample tests. ResultsDuring GSWDs, the right lateral occipital cortex indicated a significant difference in the theta band (5–7 Hz) with stronger power (P = 0.027). The interictal group possessed stronger spectral power in the delta band (P < 0.01) and weaker power in the alpha band (P < 0.01) as early as 10 s before GSWDs in absolute and relative spectral power. Additionally, the ictal group revealed enhanced spectral power inside the occipital cortex in the alpha band and stronger spectral power in the right frontal regions within beta (15–29 Hz), gamma 1 (30–59 Hz), and gamma 2 (60–90 Hz) bands. ConclusionsGSWDs seem to change gradually, with local neural activity changing even 10 s before discharge. During GSWDs, visual afferent stimulus insensitivity could be related to the impaired response state in CAE. The inhibitory signal in the low-frequency band can shorten GSWD duration, thereby achieving seizure control through inhibitory effect strengthening.

A New Dual-Input Deep Anomaly Detection Method for Early Faults Warning of Rolling Bearings.

To address the problem of low fault diagnosis accuracy caused by insufficient fault samples of rolling bearings, a dual-input deep anomaly detection method with zero fault samples is proposed for early fault warning of rolling bearings. First, the main framework of dual-input feature extraction based on a convolutional neural network (CNN) is established, and the two outputs of the main frame are subjected to the autoencoder structure. Then, the secondary feature extraction is performed. At the same time, the experience pool structure is introduced to improve the feature learning ability of the network. A new objective loss function is also proposed to learn the network parameters. Then, the vibration acceleration signal is preprocessed by wavelet to obtain multiple signals in different frequency bands, and the two signals in the high-frequency band are two-dimensionally encoded and used as the network input. Finally, the unsupervised learning of the model is completed on five sets of actual full-life rolling bearing fault data sets relying only on some samples in a normal state. The verification results show that the proposed method can realize earlier than the RMS, Kurtosis, and other features. The early fault warning and the accuracy rate of more than 98% show that the method is highly capable of early fault warning and anomaly detection.

The frontooccipital interaction mechanism of high-frequency acoustoelectric signal.

Based on acoustoelectric effect, acoustoelectric brain imaging has been proposed, which is a high spatiotemporal resolution neural imaging method. At the focal spot, brain electrical activity is encoded by focused ultrasound, and corresponding high-frequency acoustoelectric signal is generated. Previous studies have revealed that acoustoelectric signal can also be detected in other non-focal brain regions. However, the processing mechanism of acoustoelectric signal between different brain regions remains sparse. Here, with acoustoelectric signal generated in the left primary visual cortex, we investigated the spatial distribution characteristics and temporal propagation characteristics of acoustoelectric signal in the transmission. We observed a strongest transmission strength within the frontal lobe, and the global temporal statistics indicated that the frontal lobe features in acoustoelectric signal transmission. Then, cross-frequency phase-amplitude coupling was used to investigate the coordinated activity in the AE signal band range between frontal and occipital lobes. The results showed that intra-structural cross-frequency coupling and cross-structural coupling co-occurred between these two lobes, and, accordingly, high-frequency brain activity in the frontal lobe was effectively coordinated by distant occipital lobe. This study revealed the frontooccipital long-range interaction mechanism of acoustoelectric signal, which is the foundation of improving the performance of acoustoelectric brain imaging.

Distributed sub-Nyquist sampling and parameters measurement of common frequency support MEDS signals

Parameters measurement of multiple exponentially damped sinusoids (MEDS) signals is of great significance in many areas. However, recent technologies are most based on Nyquist sampling theory and thus require very high sampling rate for wide band signals. In this paper, a distributed sub-Nyquist sampling and parameters measurement method is proposed for common frequency support MEDS signals. The proposed method can measure the parameters of P common frequency support MEDS signals by P+1 distributed sub-Nyquist sampling channels. A subspace based parameters estimation algorithm is proposed to estimate the unknown amplitudes, frequencies and damping factors of the measured MEDS signals. It can be determined that K(P+1)+P⌈K/P⌉ samples are sufficient for parameters measuring of P MEDS signals with K common frequency components, which is much smaller than previous works. Finally, we design a hardware prototype to verify the effectiveness of the proposed method. Simulation and hardware experiments have demonstrated the effectiveness and noise robustness of the proposed method.

Structural design of new mesh-type high-damping rail pad and comparative experimental study on the mechanical property with the traditional rail pads

Commonly used rail pads (RPs) in urban rail transit fastening systems comprise prismatic and grooved rail pads (PRP and GRP). This research introduced novel mesh-type and mesh-type high-damping rail pads (NMTRP and MTHDRP) to mitigate RP’s stress and enhance damping efficiency while optimizing elastic material utilization. A finite element model (FEM) of the fastening system was established and validated through stiffness and hammering tests of the RPs. The FEA results revealed that the mesh-type RP offered advantages in uniform stress distribution and efficient material usage. The MTHDRP has a significantly lower stress level than the PRP and GRP because of the damping block, it will prolong the MTHDRP’s service life. Both NMTRP and MTHDRP displayed reduced static and dynamic stiffness in comparison to PRP and GRP. Notably, MTHDRP demonstrated the lowest dynamic-to-static stiffness ratio at 1.45, indicating superior dynamic stiffness retention capacity relative to the other three RPs. The hammering test found that the MTHDRP exhibited the highest damping ratio among the four RPs and consistently lower vibration amplitudes in the time and frequency domains at the rail, clip, track bed, and ground when compared to the other RPs. Furthermore, analysis of the 1/3 octave frequency band of the acceleration signal underscored MTHDRP’s excellence, with vibration levels reduced by 4.31, 4.37, 4.21, and 1.43 dB at the rail, clip, track bed, and ground, respectively, in comparison to PRP. These findings affirm the superior vibration reduction performance of MTHDRP relative to the other three RPs and underscore its potential for enhanced foundation protection when incorporated into rail systems.

Analysis of Paired Trading Strategies Based on Boll Bands

The development of information technology makes quantitative investment strategy widely used by various investors. Among them, pairing trading strategy has attracted the attention of a large number of investors. In this paper, the validity of paired trading is verified and the validity of Bollinger band signals used for paired trading is tested. To be specific, this paper takes Shanghai and Shenzhen 300 component stocks and China Securities 500 component stocks as data sets. In this paper, the correlation coefficient method is used to match the stocks. This study uses the closing price data of stocks in each pairing group from August 2021 to August 2022 for training, and backtests the training results with trading data from August 2022 to February 2023. From the yield index, the backtest group can get the highest yield of 23.4%. In addition, according to the analysis, the probability of positive returns in the backtest group is up to 80%.

Analysing Gamma Frequency Components in EEG Signals: A Comprehensive Extraction Approach

Gamma band activity is a high-frequency (30-100 Hz) oscillation of the electroencephalogram (EEG) that has been linked to a variety of cognitive processes including attention, memory and learning. However, extracting gamma band activity from EEG data can be challenging due to the relatively low signal-to-noise ratio of gamma band signals and the presence of other frequency bands such as beta and alpha. In this paper, we present a method for extracting gamma band activity from EEG data. We evaluated our method on a dataset of EEG data recorded from dyslexic patients. We found that our method was able to successfully extract gamma band activity from the EEG data. The extracted gamma band activity was significantly correlated with the subjects' performance on the visual attention task. Our results suggest that our method is an easy and straightforward approach for extracting gamma band activity from EEG data. This could be used to study the neural basis of cognitive processes in a variety of research settings.

Simple and low-latency multipoint-to-point aggregation architecture using commercial optical transceivers for uplink fronthaul.

The increasing demand of real-time applications poses a huge challenge to building next-generation radio access network (NG-RAN) with higher stability and lower system complexity. Parallel signal detection (PSD), which aggregates signals of different intermediate frequencies (IFs) on different wavelengths with a single photodiode (PD), becomes a promising candidate for uplink mobile fronthaul with the advantage of low-latency. However, high requirements on the transmitters inhibit the large-scale deployment of radio units (RU). In this paper, we propose an economical, low-latency, multipoint-to-point (MP2P) uplink fronthaul architecture capable of aggregating four end-users with commercial 25G-class optical modules and a single PD. With delta-sigma modulation (DSM), commercial off-the-shelf optical modules can replace analog transmitters in traditional systems. As a demonstration, we aggregated 4 × 380.16-MHz 5 G new radio (NR) orthogonal frequency division multiplexing (OFDM) signals in an IF band with a fixed interval of 400 MHz over 20 km fiber with 4 users.

Comparative study for performance efficiency of conventional optical transmitter with spatial optical transmitter through CWDM fiber system

Abstract This paper presents the comparative study for performance efficiency of conventional optical transmitter with spatial optical transmitter through coarse wavelength division multiplexed fiber system. The spatial light source mode polar and rectangular configuration are clarified in x directions. The lighted power signal through CWDM fiber system is simulated and measured with the use of conventional and spatial light transmitters. The lighted base band signal through CWDM fiber system is clarified with the use of conventional and spatial light transmitters. The lighted base band signal with spectral wavelength through CWDM fiber system is simulated with the use of conventional and spatial light transmitters. The Q base band signal quality factor and bit error signal rates are studied in the same configuration after receiver photodiode system with the use of conventional and spatial light transmitters.

Continuous wave light sources with various optical modulators for signal quality optical fiber systems enhancement

Abstract This study clarified the simulation study of the continuous wave light sources with various optical modulators for signal quality optical fiber systems enhancement. The lighted signal power spectrum is measured and tested with various optical modulators after fiber media system. Also the lighted base band modulated signal power value is demonstrated with different light modulators after fiber media system of the reach up to 10 km. The electrical modulated base band signal power value is clarified with various light modulators after receiver PIN system. Moreover, the electrical modulated signal base band power amplitude spectrum quality and data error system rate values are numerically clarified and measured with different light modulators after receiver PIN system. The electro-light modulators that are used namely amplitude, phase, frequency modulators and Mach–Zehnder modulator (MZM).

Fabry-Pérot optical frequency comb based mm-wave RoF system using pilot-assisted equalizer.

The emergence of the millimeter wave (mm-Wave; 30 GHz to 300 GHz) frequency band holds a lot of promise for addressing the congestion at low frequency in future mobile networks. Among many mm-Wave generation schemes, optical heterodyning is considered one of the most promising approaches due to its scalability and potential for integration on chip. Employing optical frequency combs (OFC) for optical heterodyning alleviates the significant phase distortions/noise introduced by the optical sources. However, any residual phase noise in these systems can deteriorate the transmission performance. Here we demonstrate a high-capacity mm-Wave radio-over-fiber (RoF) system using Fabry-Pérot (FP) laser comb overcoming the typical limitations of this source. The temporal phase perturbation induced by the frequency fluctuation of the FP laser is theoretically analyzed, and then estimated and compensated by a pilot-based phase equalizer. Performance evaluation of the proposed phase equalizer is conducted through experiment and simulation. Enabled by the proposed compensation scheme, ten 200 MHz filtered orthogonal frequency division multiplexing (f-OFDM) signal bands modulated by 16-quadrature amplitude modulation (QAM) are transmitted over 10 km fiber, with the ability to serve multiple users. The transmission of 16-QAM modulated single carrier signals with 2 GBd and 8 Gbps data rate is also performed for comparison, which offers better resilience to phase noise, demonstrating the first commercial Quantum Well FP laser-based optical heterodyning mm-Wave RoF system for both multi-carrier and single carrier signals.

Methods of reducing antenna bandwidth requirements for envelope elimination and restoration transmitter

The task of radio transmitting path efficiency increasing is relevant both for stationary high-power applications and for autonomous low-power devices. The highest efficiency can be achieved in switching operating modes (classes D, E, F). For the amplification of modern spectrally efficient broadcast and telecommunication signals with variable amplitude, for example, with OFDM, the use of switching operating modes is possible only with the use of "synthetic" amplification methods. The most promising for application can be considered Envelope Elimination and Restoration (EER) method, which is successfully used in the field of high-power broadcasting in the LF, MF and HF bands, and is the object of a large number of studies aimed at expanding its scope. Transmitting devices of radio communication and broadcasting systems in some cases are forced to work with an electrically short antenna. However, when operating with OFDM signals to a narrow-band load, high-efficiency EER transmitters require matching with an antenna circuit with an SWR of at least 1.05 in the signal frequency band. Thus, the task of antenna bandwidth requirements reducing for EER transmitter is relevant. To solve it, a simulation model was previously developed and verified to study the operation of EER switching RF power amplifiers for a narrow-band load. With its help, the dependence of output signal distortion level on the envelope path LPF parameters was studied. This article proposes and analyzes hardware circuit solutions aimed at reducing the transmitter sensitivity to antenna bandwidth. The analysis of hardware methods for reducing the EER transmitter sensitivity to the resonant antenna SWR (passband) showed the following: 1. The damping circuit, together with a double-sided loaded envelope path LPF, allows you to reduce antenna SWR requirements to a maximum value of 1.22, while the allowable antenna bandwidth can be reduced to five signal bands. 2. The high-pass filter diplexer proposed in this paper, together with a double-sided loaded envelope path LPF, makes it possible to reduce antenna SWR requirements to a maximum value of 1.47, and the allowable antenna bandwidth can be reduced to 2.5 signal bands. The disadvantages of this method include the need, depending on the antenna used, for individual design and manufacture of high-pass filter diplexers installed in the low-frequency path of each amplifying cell of the transmitter. To expand the range of antennas used, it is possible to switch capacitors of the high-pass filter diplexer from a set of 2 ... 3 pieces. Data on the production of transmitters with the proposed HPF diplexer has not been found to date. 3. Multi-phase PWM when using a 2nd order unilaterally loaded low-pass filter and installing 2nd harmonic rejectors of the operating frequency in the cells of the RF path allows you to work on antennas with a bandwidth of up to half the signal bandwidth. Restrictions on the antenna bandwidth and its SWR are imposed only by the uneven antenna frequency response in the transmitted signal band. The disadvantages of this method include the need to install narrow-band rejectors that block the power supply circuit of each RF cell in terms of the 2nd harmonic, which makes such a transmitter a custom product for a fixed operating frequency. 4. The most promising solution should be considered the use of a high-pass filter diplexer, which allows relatively simple means to expand the permissible SWR of a narrow-band antenna in the signal band from the initial value of 1.05 to 1.47.