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Unwanted signals in electrical systems frequently overpower the desired signal. In an attempt to increase the ratio, the desired signals are amplified proportionately to the undesired ones. Frequency selective circuits, often known as filters, can be used to separate desired signals from undesirable ones as signals can be identified by their frequency characteristics. Analog filters are available in both active and passive varieties, each having unique properties. A first order band pass active filter is developed and characterized in this study. The Operational Amplifier (OP AMP 741) is the active element in this case. With the Band Width (BW), Cut-off Frequencies (FL and FH), Center Frequency (FC), and Quality factor (Q) provided, the Transfer Function (TF) equation is generated and defined. [ABSTRACT FROM AUTHOR]

Relevance. The necessity to improve the accuracy of analysis and prediction of potential fire hazard of rock-coal massifs by using electromagnetic methods of endogenous fire detection. Taking into consideration that the increase in coal temperature changes a number of its parameters, such as dielectric permittivity and electrical resistivity, it is reasonable to use the method of electromagnetic reconnaissance in locating the focus of fire. Aim. To analyze the theoretical and practical knowledge about the anomalies formed in the area of spontaneous combustion and to evaluate the effectiveness of electromagnetic methods for locating the spontaneous combustion zones of a coal massif. Objects. Physical parameters of the ignition zone of the coal massif, such as dielectric permittivity and electrical resistivity, as well as the range of the GPR central frequency, allowing clearly defining the boundaries of the ignited zone. Method. Reviewing the proposed methods of determining the parameters serving for correct location of the fire zone. For GPR it is necessary to determine the center frequency of the standard antenna unit and resolution, then to estimate the rational frequency range of GPR. Results. Allow us to draw conclusions about the methods used to determine the rational range of GPR center frequency – it can be calculated by solving the system of equations of the signal attenuation function and energy potential of GPR, by the experimental value of the target function, including the depth and detail of sounding as a function of frequency, or on the basis of a complex parameter of GPR, including the radiated power of the antenna, the number of accumulations and the reflection coefficient from the boundaries. Taking into account such physical features of the fire zone as drying the rock-angle massif and the shape of the anomalous zone, the rational range of the center frequency for the GPR "OKO-2" was determined.

Filtering is very popular and important in the field of Electrical and Electronic Engineering. In the field of Telecommunication, filter is used in multiplexing whereby several different signals are transmitted through the same transmission channel and never mixed up because of virtue of their separated frequencies and are separated at the end of their receiving end again by the process of demultiplexing. In entertainment industries, audio circuits in the form of filters are used to give music distinct tones of bass, treble etc. In radio transmission, filters are used in separating transmission channels both in FM and AM bands thereby giving each station a distinctive transmission channel. In amplification devices using amplifiers, attempt in amplifying intelligent signals results in the amplification of unwanted signals in the form of noise. To minimize or reduce this, filters are used in removing the unwanted signals. Filters come in different forms but broadly it can be classified into analog and digital filters. It can also be classified by the nature of components used in its design. By this classification we have active and passive filters. In this paper, the development and characterization of a first order high pass active filter is shown.. Operational Amplifier chip OP AMP 741 was used in achieving this. The Transfer Function (TF) equation of the filter is derived with the Band Width (BW), Cut-off Frequency (Fc) and the Quality Factor (Q) specified. The developed first order Active High Pass filter was tested by application of varied frequencies with fixed input voltage to its input while the performance monitored at the output. Finally the frequency response plots indicative of the designed specification in ratio of Vo/Vin and in dB were plotted and shown. [ABSTRACT FROM AUTHOR]

The lifestyle of any person depends on his ability to hear his surrounding sounds or voices. This is because each of our sense organs works interrelated. Without an ability to proper hearing, he/she cannot respond to the other person leading to a very less or no communication to the society. Although he has a good talent and knowledge within, he cannot be able to communicate or express unless he has a good hearing ability. Also, he faces emotive problems caused by a reduction in self-confidence. So, a requirement of designing an efficient hearing aid is much necessary to resolve the hearing loss problem. In this paper, design of an efficient alterable ten band Finite Impulse Response filter bank for the hearing aid is achieved. Among the various windowing techniques available, Hamming window is preferred to design the FIR filter owing to its relatively sharp main lobe width and also the first few lobes have good attenuation. In this filterbank, variability in the subband bandwidths is achieved by simply altering each subband's bandwidth and center frequency. Unlike fixed filterbank, the proposed design provides the advantage of matching most of the audiograms of different hearing-impaired persons more accurately with simple procedure leading to low cost and low hardware complexity. Also using an FIR filter in the filterbank leads to highly stable design. Thus, a design of highly qualitative filterbank compared to fixed bandwidth designs with high audiogram matching and less matching error is implemented.

An active inductor (AI) circuit is a widely used component in tuning circuits, filters, oscillators, etc. These circuits offer various advantages over spiral inductors, namely less chip area consumption, high-quality factor (Q-factor), easy tunability, etc., and are also easier to be integrated with an IC. This paper brings together the various grounded AIs constructed using CMOS technology, most of which have been proposed in the last two decades. A detailed analysis has been presented along with the assessment of the various AI designs, with respect to a number of factors, like inductance value and power consumption. Furthermore, these circuits have been exploited to realize a common application such as a band pass filter, and the resulting behaviour of each design has been noted as well to give a fair comparison among all. The simulations have been carried out in Cadence Virtuoso, using 90 nm CMOS technology. To obtain an unbiased comparison, a common supply voltage of 1.2 V is used for simulating all the circuits. [ABSTRACT FROM AUTHOR]

Considering the difficulty of selecting sensitive fault features in bearing health diagnosis, a fault diagnosis method based on complete center frequency distribution feature (CCFDF) is proposed. By making full use of the sensitivity of the center frequency to the signal spectrum distribution in variational mode decomposition (VMD) and extracting the complete distribution feature of the center frequency under different parameter combinations, CCFDF can effectively characterize the difference in bearing vibration signals under different health conditions and avoid the parameter setting problem in VMD. Finally, two groups of experimental data are used to verify the effectiveness of the method, and the recognition accuracy was 99% and 97%, respectively. Therefore, this method can effectively characterize the difference characteristics of different signals and achieve the final bearing fault diagnosis. [ABSTRACT FROM AUTHOR]

Air quality has a significant impact on human health, in order to alleviate the air pollution and improve the ability to predict the air quality. In this paper, a prediction model of air quality index composed of variational mode decomposition and temporal convolutional network was proposed. First, in order to reduce the non-stationarity and randomness of the time series, the original air quality index sequence was decomposed by variational mode decomposition, and the decomposition number was determined by the central frequency method to decompose into multiple relatively stable sub-sequences with different frequency scales. Then, the decomposed sub-stable sequence was predicted by the time convolutional network. Finally, the prediction data were integrated and reconstructed to obtain the final prediction results. Comparing the results of other forecasting models by performance evaluation metrics, the combined forecasting model proposed in this paper reduced RMSE by 20.9%, 19.2%, 5.1%, 29.9%, 23.7% on the Beijing dataset. MAPE reduced by 26.6%, 22.3%, 19.5%, 28.9%, 15.0%, respectively. MAE decreased by 19.1%, 20.6%, 9.6%, 29.5%, 23.5%. R2 increased by 4.6%, 4.0%, 0.8%, 14.9%, 5.5% respectively. This proves the accuracy and reliability of the proposed model. [ABSTRACT FROM AUTHOR]

The deployment of UWB, 5G and WiFi6 systems underground in coal mines has problems such as multiple base stations, multiple transmission cables, multiple power supply equipment, high system costs, and heavy maintenance workload. Integrating UWB, 5G and WiFi6 antennas into the same integrated base station or sub station can effectively solve the above problems. However, the distance between UWB, 5G and WiFi6 antennas in the integrated base station is close, resulting in high mutual interference. Choosing different operating frequency bands is an effective method to solve the high mutual interference between UWB, 5G and WiFi6 antennas in integrated base stations. To be compatible with ground equipment, the selection range of mining WiFi6 and 5G operating frequency bands is relatively small, while the selection range of UWB operating frequency bands is relatively large. At present, the positioning system for mine personnel and vehicles mainly uses the UWB mainstream chip DW1000, with a center frequency of 3.5, 4.0, 4.5 and 6.5 GHz. The UWB with a center frequency of 3.5 GHz is similar to the 5G operating frequency band of 3.5 GHz. It is not suitable for selection. The three frequency bands of UWB with center frequencies of 4.0, 4.5 and 6.5 GHz are not similar to the 5G and WiFi 6 frequency bands. The frequency band with smaller attenuation can be selected as the center frequency of the mining UWB. The underground testing results of coal mines show that the path loss of the 4.0 GHz signal is the smallest, and the transmission distance is the farthest under the same other conditions. This not only solves the problem of interference between UWB, 5G and WiFi6, but also reduces the number of base stations and system costs. It is easy to use and maintain. Therefore, the UWB center frequency should preferably be 4.0 GHz.

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The multi-angle Doppler method was introduced for the estimation of velocity vectors by measuring axial velocities from multiple directions. We have recently reported that the autocorrelation-based velocity vector estimation could be ameliorated significantly by estimating the wavenumbers in two dimensions. Since two-dimensional wavenumber estimation requires a snapshot of an ultrasonic field, the method was first implemented in plane wave imaging. Although plane wave imaging is predominantly useful for examining blood flows at an extremely high temporal resolution, it was reported that the contrast in a B-mode image obtained with a few plane wave emissions was lower than that obtained with focused beams. In this study, the two-dimensional wavenumber analysis was first implemented in a framework with focused transmit beams. The simulations showed that the proposed method achieved an accuracy in velocity estimation comparable to that of the method with plane wave imaging. Furthermore, the performances of the methods implemented in focused beam and plane wave imaging were compared by measuring human common carotid arteries in vivo. Image contrasts were analyzed in normal and clutter-filtered B-mode images. The method with focused beam imaging achieved a better contrast in normal B-mode imaging, and similar velocity magnitudes and angles were obtained by both the methods with focused beam and plane wave imaging. In contrast, the method with plane wave imaging gave a better contrast in a clutter-filtered B-mode image and smaller variances in velocity magnitudes than those with focused beams. [ABSTRACT FROM AUTHOR]

As a stable and widely covered signal resource, a Global Navigation Satellite System (GNSS) plays an important part in micro-Doppler extraction in a near field. This paper aims at the problems associated with rotor blade target recognition and proposes a novel solution based on phase compensation. First, the mathematical mechanism of flicker distribution in a time-frequency field is analyzed, and phase compensation is used to achieve the Doppler focusing, and then the blade number can be estimated. Second, according to the that the minimum delta frequency principle between the center frequency and standard frequency, the rotation velocity of the rotor blade is obtained. Next, blade lengths can be calculated through the flicker bandwidth in the time-frequency domain. Finally, the simulation experiments validate the effectiveness of the proposed method.

Aiming at the problem that it is difficult to extract fault features of electrolytic capacitors of NPC three-level inverters, a fault feature extraction method combining variational modal decomposition and modal energy is proposed. The method obtains the current deviation signal by collecting the current signal at the output end of the NPC three-level inverter and combining with the reference current signal. According to the characteristics of the frequency distribution of the current deviation signal, the modal repetition rate is used to optimize the parameters of the VMD decomposition scale. The current deviation signal is decomposed by VMD, and the bandwidth-limited modal component with the center frequency is obtained. According to the information entropy of the modal components, the characteristic components that can characterize the capacitor fault are determined, and then the modal energy of the characteristic components is calculated, the eigenvectors are constructed, the characteristic change rules are sought, and they are classified. The results show that this method can accurately reflect the working state of electrolytic capacitors. [ABSTRACT FROM AUTHOR]

Although color flow imaging is one of the representative applications of the Doppler method, it can estimate only the velocity component in the direction of ultrasonic propagation, that is, the axial velocity component. The vector Doppler method with high-frame-rate plane wave imaging overcomes such a limitation by estimating the blood flow velocity vectors using the axial velocities obtained by emitting plane waves in multiple directions. The autocorrelation technique can be used for the estimation of the axial velocity using the phase shift of an ultrasonic echo signal between two transmit–receive events. The technique also requires the frequency of the received echo signal. Although the center frequency of the emitted ultrasonic signal is commonly used in the estimation of axial velocities, the center frequency should be estimated from the received signals. In this study, a method for the estimation of the center frequency designed particularly for the high-frame-rate plane wave imaging was developed. The proposed method estimates the wavenumbers of the received signal in lateral and vertical directions to estimate the wavenumber in the axial direction, from which the center frequency was estimated. The beam steering angle was also estimated from the wavenumbers in the two directions. The effect of the proposed method was validated in simulations. The absolute bias error (ABE) and root-mean squared error in estimated velocity vectors obtained by plane wave imaging with three beam steering angles (−15°, 0°, and 15°) were reduced from 9.27% and 14.80% to 1.15% and 8.75%, respectively, by the proposed method. The applicability of the proposed method to in vivo measurements was also demonstrated using the in vivo recordings of human common carotid arteries. Physiologically consistent blood flow velocity distributions were obtained with respect to three subjects using the proposed method. [ABSTRACT FROM AUTHOR]

In the field of underwater acoustic signal processing, the ship radiated noise contains a large amount of ship information, which is of great significance to the ship identification. The traditional method relies too much on the operator and prior knowledge, which seriously reduces the efficiency and accuracy of the ship radiated noise identification. This paper presented a novel ship radiated noise feature extraction method based on compression sensing and center frequency. Firstly, to compression sensing of the ship radiated noise, enhance its line spectrum energy. Then, the ship radiated noise is decomposed by empirical mode decomposition to obtain multiple intrinsic mode function, calculate the mutual information entropy of adjacent intrinsic mode function to determine the key parameter K of the variational mode decomposition. Finally, perform variational model of ship radiated noise based on K, extract the center frequency of maximum energy intrinsic mode function as the ship radiated noise recognition feature. Experimental results show that the proposed feature extraction method can classify ship radiated noise quickly and effectively, and reduce the dependence on operators and prior knowledge.

Bionic wavelet transform is a continuous wavelet, based on adaptive time frequency technique. This paper presents a speech recognition system for recognizing isolated words by discretizing the continuous Bionic Wavelet (BW). Conversion from continuous to discrete is achieved by adopting central frequency and thresholding techniques. The BW features of noisy signal are processed through MFCC to obtain the optimal features of the speech signal. SVM, Artificial Neural Network (ANN) and LSTM techniques are used to improve the recognition rate by enhancing the speech signals. The experiments are conducted on FSDD and Kannada data set. The speech feature vector is calculated using the parameters extracted by Bionic wavelet with different central frequencies of Morlet, Daubechies and Bior3.5, coiflet5 mother wavelets. The obtained Bionic-MFCC optimal features are fed to SVM, ANN and LSTM models for the classification and recognition process. The performance of the models is tabulated for correct recognition that varies from 95% to 96% among these models. The models are tested for various SNRs noise levels like 5 dB, 10 dB, 15 dB and the recognition accuracies of these models are presented for convoluted noisy speech data.

The multi-angle Doppler method was introduced for the estimation of velocity vectors by measuring axial velocities from multiple directions. We have recently reported that the autocorrelation-based velocity vector estimation could be ameliorated significantly by estimating the wavenumbers in two dimensions. Since two-dimensional wavenumber estimation requires a snapshot of an ultrasonic field, the method was first implemented in plane wave imaging. Although plane wave imaging is predominantly useful for examining blood flows at an extremely high temporal resolution, it was reported that the contrast in a B-mode image obtained with a few plane wave emissions was lower than that obtained with focused beams. In this study, the two-dimensional wavenumber analysis was first implemented in a framework with focused transmit beams. The simulations showed that the proposed method achieved an accuracy in velocity estimation comparable to that of the method with plane wave imaging. Furthermore, the performances of the methods implemented in focused beam and plane wave imaging were compared by measuring human common carotid arteries in vivo. Image contrasts were analyzed in normal and clutter-filtered B-mode images. The method with focused beam imaging achieved a better contrast in normal B-mode imaging, and similar velocity magnitudes and angles were obtained by both the methods with focused beam and plane wave imaging. In contrast, the method with plane wave imaging gave a better contrast in a clutter-filtered B-mode image and smaller variances in velocity magnitudes than those with focused beams.

This paper presents a bandwidth and center frequency tunable bandpass filter with wide tuning range. The proposed filter employs two cascade cross‐shaped resonators. The cross‐shaped resonator can generate two independent tunable transmission zeros by introducing two microwave varactors. The center frequency and bandwidth can be tuned by adjusting the DC bias voltages applied to the varactors. For demonstration, a filter example was designed, fabricated and measured. The tuning 3‐dB bandwidth from 20% to 30% is achieved when the center frequency is tuned from 3.5 to 5 GHz. Meanwhile the insertion loss is less than 4 dB with a high selectivity. The size of the filter is 0.32λg × 0.36λg where λg is the guided‐wavelength at the center frequency. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of SDU Journal of Engineering Sciences & Design / Mühendislik Bilimleri ve Tasarım Dergisi is the property of Journal of Engineering Sciences & Design and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study was to investigate whether human listeners are able to detect a binaurally uncorrelated arbitrary-noise fragment embedded in binaurally identical arbitrary-noise markers [a break in correlation, break in interaural correlation (BIAC)] in either frequency-constant (frequency-steady) or frequency-varied (unidirectionally frequency gliding) noise. Ten participants with normal hearing were tested in Experiment 1 for up-gliding, down-gliding, and frequency-steady noises. Twenty-one participants with normal hearing were tested in Experiment 2a for both up-gliding and frequency-steady noises. Another nineteen participants with normal hearing were tested in Experiment 2b for both down-gliding and frequency-steady noises. Listeners were able to detect a BIAC in the frequency-steady noise (center frequency = 400 Hz) and two types of frequency-gliding noises (center frequency: between 100 and 1,600 Hz). The duration threshold for detecting the BIAC in frequency-gliding noises was significantly longer than that in the frequency-steady noise (Experiment 1), and the longest interaural delay at which a duration-fixed BIAC (200 ms) in frequency-gliding noises could be detected was significantly shorter than that in the frequency-steady noise (Experiment 2). Although human listeners can detect a BIAC in frequency-gliding noises, their sensitivity to a BIAC in frequency-gliding noises is much lower than that in frequency-steady noise.

This study was to investigate whether human listeners are able to detect a binaurally uncorrelated arbitrary-noise fragment embedded in binaurally identical arbitrary-noise markers [a break in correlation, break in interaural correlation (BIAC)] in either frequency-constant (frequency-steady) or frequency-varied (unidirectionally frequency gliding) noise. Ten participants with normal hearing were tested in Experiment 1 for up-gliding, down-gliding, and frequency-steady noises. Twenty-one participants with normal hearing were tested in Experiment 2a for both up-gliding and frequency-steady noises. Another nineteen participants with normal hearing were tested in Experiment 2b for both down-gliding and frequency-steady noises. Listeners were able to detect a BIAC in the frequency-steady noise (center frequency = 400 Hz) and two types of frequency-gliding noises (center frequency: between 100 and 1,600 Hz). The duration threshold for detecting the BIAC in frequency-gliding noises was significantly longer than that in the frequency-steady noise (Experiment 1), and the longest interaural delay at which a duration-fixed BIAC (200 ms) in frequency-gliding noises could be detected was significantly shorter than that in the frequency-steady noise (Experiment 2). Although human listeners can detect a BIAC in frequency-gliding noises, their sensitivity to a BIAC in frequency-gliding noises is much lower than that in frequency-steady noise. [ABSTRACT FROM AUTHOR]

• The convergence property of VME model is first revealed and proved theoretically. • A central frequency identification strategy is presented to detect TCFs of latent modes. • A bandwidth estimation strategy is built to determine the balance parameter efficiently. • Our SSEVM can correctly extract the fault-related mode from the mechanical signal. • The proposed method is validated by one numerical case and two experimental cases. Variational mode extraction (VME) has attracted increasingly attentions due to its characteristic of extracting a specific mode from the complicated signal. Nevertheless, its performance depends on the initial center frequency (ICF) and the balance parameter. To address the issue of setting ICF, a convergence property of VME is first explored by feeding different ICFs into the variational model. During this exploration, a convergence tendency phenomenon of center frequency (CF) is found from the optimization procedure of VME and a mathematical proof is successfully conducted on this phenomenon. As a result, a CF identification strategy is designed to determine the ICFs for the expected modes automatically, where a calibration operation is synchronously built to improve the identification accuracy of ICFs. In addition, to determine the balance parameter efficiently, a bandwidth estimation strategy with a solid theoretical basis is constructed motivated by the filtering structure of VME model. Finally, a spectral structure inducing efficient variational model is proposed to adaptively extract the faulty modes from the complicated signal by combining the CF identification strategy and the bandwidth estimation strategy. The effectiveness of the proposed method for bearings fault diagnosis is verified by a simulated and two experimental cases and its superiority is also confirmed by comparing with some classical and advanced methods. [ABSTRACT FROM AUTHOR]

This paper proposes a simple and effective feedback structure to implement the variable-Q band-pass filter. An effective variable-Q band-pass filter can be designed by using integral-plus-derivative in the feedback pass. The stability of the model is shown in both continuous and discrete-time systems. Also, we demonstrate that the model could indeed achieve the desired center frequency as a precise filter. The efficiency of the proposed feedback structure is demonstrated using simulation. [ABSTRACT FROM AUTHOR]

A novel method for early looseness state identification of bolted joint beams is proposed in this paper based on generalized variational mode decomposition (GVMD) and a similarity index. In the proposed method vibration signals are decomposed by GVMD, which has the property of the multiscale and fixed-frequency decomposition. To effectively extract the desired modes, the frequency band allocation is designed through flexibly defining scale parameters and prior center frequencies according to the characteristics of the signal itself and real needs. A new similarity index is formed based on the centroid frequency ratio of sensitive vibration modes to reliably identify early looseness state. The effectiveness of the proposed method is verified by impulse experiments of bolted joint transverse beam and bolted joint vertical beam. The results indicate that compared with other methods, the proposed method can effectively identify the early looseness state of the bolted joint beams, and has a good repeatability. [ABSTRACT FROM AUTHOR]

Traditional filters usually have low Q and gain values and it is difficult to adjust their center frequencies. Moreover, it is very complicated to analyze their transmission charateristics through conventional methods. Therefore, in this paper, a tunable differential N-path bandpass filter that uses a new adjoint network method to analyze the transmission characteristics of the differential N-path structure is proposed. The filter circuit adopts a novel circuit structure consisting of two differential N-path structures, two transconductance amplifiers and an off-chip transformer. The differential structure eliminates even harmonics, the transconductance amplifier increases the circuit gain and the off-chip transformer acts as a balun, improving the filter's Q value and achieving impedance matching. Unlike the traditional switching capacitance method used for analyzing the differential circuit structure, the method proposed in this paper does not involve complicated calculus operations. In fact, the method greatly simplifies these complex operations, and the transmission function of the circuit can be obtained through simple algebraic operations. The proposed filter was designed using TSMC 180 nm CMOS process. Simulation results for a differential four-path bandpass filter formed under 1.2 V supply voltage show that the gain of the filter is greater than 8.5 dB, the center frequency can be adjusted from 0.1 GHz to 1 GHz, the in-band insertion loss S11 is greater than 10 dB, the out-of-band IIP3 is greater than 10 dBm, the out-of-band rejection is 28 dB and the noise figure is less than 2.2 dB at f s = 3 0 0 MHz. [ABSTRACT FROM AUTHOR]

• Build a fiber Bragg grating-based sensing device to monitor breathing and heartbeat signals. • The respiratory and heart rate signals were decomposed using a variational modal decomposition algorithm, and the respiratory and heart rates were determined from spectrograms. • Heart rate measurement is the same as that of the electrocardiograph, and respiratory rate measurement error is within 0.2 bpm. • An adaptive K-value algorithm is proposed to determine the number of decomposition layers for the variational modal decomposition. • Realization of physiological health monitoring in the comfort of the home. A fiber Bragg grating (FBG)-based acquisition method for heartbeat and respiration was designed for portable home-based cardiopulmonary physiological parameter detection. The ballistocardiogram (BCG) is susceptible to noise interference during the acquisition process. In order to improve the accuracy of heart rate and respiration rate solving, the adaptive K-value-based variational modal decomposition (K-VMD) algorithm is proposed. First, the algorithm obtains the optimal solution by calculating the difference frequency of the last component of the neighboring K-values. Second, a threshold value is set according to the frequency variation. Again, the optimal K value is automatically selected according to the threshold. The problem of over-decomposition or under-decomposition can be solved by using the optimal K-value decomposition. Finally, heart rate and respiration rate are estimated using the power spectrum based on Welch's method. In 15 comparison experiments, the K-VMD algorithm was in perfect agreement with the ECG signal 13 times, and the other three conventional methods were 9, 7, and 5 times, respectively. The maximum error of the K-VMD algorithm was 1 bpm, and the other three conventional methods were 2 bpm, 3 bpm, and 3 bpm, respectively. The maximum error in the respiratory rate detection of this algorithm in the position of the diaphragm is ±0.2 bpm. It can be seen that the present algorithm can effectively reduce noise interference and improve monitoring accuracy. And it can provide data support for obtaining the characteristic waveform of cardiac shock signals and respiratory signals. It has certain practical applications. [ABSTRACT FROM AUTHOR]

Significance: In the photoacoustic (PA) technique, the laser irradiation in the time domain (i.e., laser pulse duration) governs the characteristics of PA imaging-it plays a crucial role in the optical-acoustic interaction, the generation of PA signals, and the PA imaging performance., Aim: We aim to provide a comprehensive analysis of the impact of laser pulse duration on various aspects of PA imaging, encompassing the signal-to-noise ratio, the spatial resolution of PA imaging, the acoustic frequency spectrum of the acoustic wave, the initiation of specific physical phenomena, and the photothermal-PA (PT-PA) interaction/conversion., Approach: By surveying and reviewing the state-of-the-art investigations, we discuss the effects of laser pulse duration on the generation of PA signals in the context of biomedical PA imaging with respect to the aforementioned aspects., Results: First, we discuss the impact of laser pulse duration on the PA signal amplitude and its correlation with the lateral resolution of PA imaging. Subsequently, the relationship between the axial resolution of PA imaging and the laser pulse duration is analyzed with consideration of the acoustic frequency spectrum. Furthermore, we examine the manipulation of the pulse duration to trigger physical phenomena and its relevant applications. In addition, we elaborate on the tuning of the pulse duration to manipulate the conversion process and ratio from the PT to PA effect., Conclusions: We contribute to the understanding of the physical mechanisms governing pulse-width-dependent PA techniques. By gaining insight into the mechanism behind the influence of the laser pulse, we can trigger the pulse-with-dependent physical phenomena for specific PA applications, enhance PA imaging performance in biomedical imaging scenarios, and modulate PT-PA conversion by tuning the pulse duration precisely., (© 2024 The Authors.)

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pipeline plays an important role in various systems of the ship. However, due to the harsh environment, leakage often occurs in ship pipeline. This paper proposes a method to identity and locate the pipeline leakage. Using the variational mode decomposition (VMD) algorithm, the vibration signal is decomposed into band-limited intrinsic mode functions (BIMFs). The effective BIMFs are then selected by the correlation coefficient. Center frequency and energy value of the effective BIMFs are extracted as feature vector. Radial Basis Function (RBF) neural network is then used as a tool to identify and locate the leakage. The proposed method is finally verified by experiments. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)