Showing papers on "Signal published in 2022"
TL;DR: A height measurement signal model for meter wave polarimetric MIMO radar along with its effective solution is provided and the simulation results prove the accuracy of this approach.
56 citations
TL;DR: In this article, the authors proposed noise subtraction and marginal enhanced square envelope spectrum (MESES) for detecting bearing defects in the centrifugal and axial pump in order to avoid time lag problem which generally occurs in two signals obtained at different time.
39 citations
TL;DR: The data of bearing inner ring, outer ring and compound faults prove that the method can be applied to bearing fault diagnosis and the proposed method has greater advantages in decomposing noisy signals.
38 citations
TL;DR: In this article, a combined electrical and ultrasonic sensor is used to simultaneously and non-intrusively acquire online flowing information, including the water fraction estimated by the normalized voltage from a conductance sensor, the gas fraction calculated by locating the gas-liquid interface through a pulse-wave ultrasonic sensors consisting of three transducers.
23 citations
TL;DR: In this paper, a self-powered fault diagnosis of rolling bearing (SP-FDRB) is conducted based on the triboelectric effect, where flexible interdigital electrodes are glued to the outer ring of a rolling bearing to form a rolling-type free standing mode nanogenerator (RF-TENG).
20 citations
TL;DR: In this paper, the authors proposed a synchronous rectification (SR) scheme based on resonant inductor voltage to reduce the secondary side conduction loss of CLLC bidirectional resonant converter and improve its efficiency.
Abstract: Synchronous rectification (SR) is an effective method to reduce the secondary side conduction loss of CLLC bidirectional resonant converter and improve its efficiency, but the SR driving signal in CLLC converter is hard to determine. Existing SR signal generating methods can be divided into three categories: theoretical calculation, voltage detection, and current detection. Compared with the other two methods, the current detection method has wider applicability and is insensitive to parasitic parameters, but usually requires lossy, bulky and costly current sensors, increasing the cost and size of the converter. This article proposed a SR scheme based on resonant inductor voltage. The polarity of the resonant current is obtained indirectly through the inductor voltage, thereby avoiding the use of current sensors. To handle the false pulses problem caused by parasitic oscillation, a corresponding SR control strategy is proposed. The SR driving signal is then adjusted according to the delay and transient requirements. Experimental results on a 380V/270V 3kW CLLC converter prototype were presented to verify the effectiveness of the proposed SR method.
18 citations
TL;DR: A novel motion estimation method based on phase-domain image processing, named Hilbert phase- based motion estimation, is proposed in this study to identify motions in a more accurate and efficient manner if compared to traditional phase-based motion estimation.
17 citations
TL;DR: Results verify that detectability of Am-MUSIC-driven damage imaging is not limited by damage quantity, and the amelioration expands conventional MUSIC from phased array-facilitated nondestructive evaluation to health monitoring using built-in sparse sensor networks.
16 citations
TL;DR: In this paper, the concept of actively mode-locking in fiber laser is introduced into the OEO, in which an external microwave signal with the frequency integral multiple of the free spectral range of OEO is injected to achieve a mode-locked condition.
Abstract: The optoelectronic oscillator (OEO) is the most widely investigated microwave photonic hybrid system for the generation of microwave signal with high frequency and low phase noise. It has been considered a reasonable and promising solution for obtaining pure microwave signal. Generally, a conventional OEO is used for the generation of only continuous microwave signal owing to the long mode building time of the oscillation cavity, leading to limited application areas. Here, the concept of actively mode-locking in fiber laser is introduced into the OEO, in which an external microwave signal with the frequency integral multiple of the free spectral range of OEO is injected to achieve a mode-locked condition. In this case, an OEO that can directly generate pulsed microwave signal with adjustable central frequency and time duration is demonstrated. Furthermore, by changing the frequency of the injection signal, harmonic mode locking with different orders can be easily achieved, while supermodes are confined. The proposed OEO has great potential in applications such as radars, communications and metrology.
14 citations
TL;DR: In this paper, the authors proposed a CT-based signal separation scheme (CT3S) to retrieve modes and analyzed the error bounds for IF estimation and component recovery with this scheme.
13 citations
TL;DR: In this paper, a self-powered wireless tire pressure sensor system is used for real-time tire pressure and speed monitoring for a bicycle, with a resolution of 5.5 kPa and a precision of about 97% respectively, demonstrating its excellent potential for general applications.
TL;DR: In this article, a UV-curable elastomer for digital light processing (DLP) 3D printing flexible electronics was used for fast recoverability and high stretchability.
Abstract: Previous studies on UV-curable elastomer for digital light processing (DLP) 3D printing flexible electronics mostly focused on higher stretchability and healability, thereby ignoring rapid recovera...
TL;DR: An automatic detector device that operates based on two diagnostic indicators, third to fifth harmonic ratio of the insulator's LC signal and cosine of phase angle difference between fundamental signals of the voltage and LC, designed and built for monitoring insulators state in overhead distribution lines.
Abstract: An automatic detector device (ADD) has been designed and built for monitoring insulators state in overhead distribution lines. The prototyped device is suitable for measurement and analysis of the insulator leakage current ( LC ) on lines of distribution systems to diagnose insulator state. It operates based on two diagnostic indicators, third to fifth harmonic ratio (R3/5%) of the insulator's LC signal and cosine of phase angle difference (P.D%) between fundamental signals of the voltage and LC . Experimental data of the indicators in various conditions and various insulators are used to train a classifier for determining reference values of the indices for insulator state detection. The instrument has two physically separate parts: receiver and transmitter. They communicate via a radio communication channel which improves the effectiveness of incident management. The transmitter samples the LC signal of the target insulator using a ferrite core along with a series of active electronic filters. The sampled LC signal is then sent to the receiver. The transmitted LC signal is analyzed by the microprocessor embedded in receiver CPU. Indicators of the transmitted LC signal are calculated and compared with reference values extracted from the classifier. The receiver determines the insulator's state based on the comparison of the estimated and reference values of diagnostic indicators for the target insulator. The performance of the prototyped ADD was evaluated experimentally in the laboratory as well as on overhead distribution lines. These performance tests confirmed reliable performance of the ADD.
TL;DR: Experimental results show that the proposed method is able to obtain the components of the nonideal signals and the accurate position (velocity) with a small error in real time, while other calibration methods are difficult to apply to fast motion.
Abstract: The sinusoidal encoder is used as an absolute position (velocity) transducer to implement the position (velocity) of actuators in many industrial applications. However, the performance of the position (velocity) can be degraded due to nonideal factors such as differential amplitudes of the encoder signals, offset, and phase shift. To analyze this problem, we formulate the relationship between the coefficients of ideal signals and the nonideal signals characteristic, which is an ellipse formed by plotting the encoder signals versus each other. In this article, we propose a nonideal signal calibration for the imperfect components of existing sinusoidal signals to improve position (velocity) regulation performance. The fictitious cosine function is used to detect the phase shift between the sine and cosine signals, and it can be designed by using the frequency of sinusoidal signals. The proposed method is validated by simulation and experimental implementation, showing noticeable improvement in estimating nonideal signal components, Lissajous error curve, phase distribution, and the position (velocity) error signal. Experimental results show that the proposed method is able to obtain the components of the nonideal signals and the accurate position (velocity) with a small error in real time, while other calibration methods are difficult to apply to fast motion.
TL;DR: In this paper, a smartphone-integrated immunosensor based on non-spectroscopic optical detection was introduced, where wash-free immunosensing was implemented on a polymeric microfluidic chip device fabricated for light signal penetration in retroreflection signal acquisition.
TL;DR: In this article, a room temperature interband cascade laser emitting at 4.54μm was used as a laser source to cover the absorption lines of N2O and CO simultaneously.
Abstract: A highly precise dual gas sensor for measurement of atmospheric nitrous oxide (N2O) and carbon monoxide (CO) was developed and evaluated. A room temperature interband cascade laser emitting at 4.54 μm was used as a laser source to cover the absorption lines of N2O and CO simultaneously. Sensitivity and precision were enhanced by using an improved White cell with 76 m effective optical path length and radio frequency noise perturbation technique to reduce optical interference noise. A method was proposed to correct the laser frequency by calculating the correlation coefficient between the absorption signal with the reference signal, which effectively reduced the long-term drift of the absorption line center to less than 4 × 10−5 cm−1. By further precisely control the temperature and pressure of the absorption cell, a continuous 24 h measurement precision of 65 ppt N2O and 133 ppt CO at 0.1 Hz was demonstrated, with a daily drift less than 1.5 ppt. Finally, the repeatability and reliability of the sensor system were validated by real atmospheric measurements for two consecutive days.
TL;DR: In this article, a multiple-damage-scattered wavefield model is developed, with which the signal representation equation is constructed in the frequency domain, avoiding computationally expensive pixel-based calculation.
TL;DR: In this article, a novel decomposition algorithm termed as data-adaptive Gaussian average filtering (DAGAF) is introduced for biomedical applications. But, the performance of DAGAF in computer experiments is limited.
TL;DR: The comparison with the instantaneous frequency ridge extraction approach further indicates the proposed model-driven Doppler distortion self-tuning method can reach a more accurate correction result in a faster and adaptive process.
TL;DR: In this paper, an algorithm for automatic and quantitative evaluation of peeling and delamination on infrastructure surfaces from laser 3D point cloud data is proposed using state-of-the-art signal and image processing methodologies.
TL;DR: In this article, a high-resolution, in-situ material testing system that integrates acoustic emission (AE) testing with a nanoindentation system for crack generation and detection in thin film stack structures is presented.
TL;DR: A novel automated method for detecting harmonic components in a signal, viz. the periodogram ratio detection (PRD) method, which identifies each harmonic in a spectrum or in a frequency band, if desired and removes little of the energy of the non-harmonic part of the signal by editing only a small number of frequency bins at each harmonic.
TL;DR: In this article, a hybrid-mode pulse-frequency-modulation control method for LLC resonant converter is proposed, where the primary-side resonant current sensing signal of the current-mode control variable is combined with a ramp signal of voltage-mode controller variable to determine an operating frequency.
Abstract: This article presents a new hybrid-mode pulse-frequency-modulation control method for an LLC resonant converter. In the proposed control method, the primary-side resonant current sensing signal of the current-mode control variable is combined with a ramp signal of the voltage-mode control variable to determine an operating frequency. Then, the proposed control method mainly modulates the ramp signal in accordance with the output load condition. Therefore, the control-to-output voltage transfer function has both the current - mode control and voltage-mode control characteristics that provide fast frequency response and stable output voltage regulation in a light-load condition. In addition, since the ramp signal is also used for slope compensation of the resonant current sensing signal, an external slope compensation circuit is not required. A small-signal ac modeling and loop analysis of the proposed method verify the advantages. The proposed control method is implemented into a field programmable gate array (FPGA) board with an analog front-end board. An experiment is carried out on a 288-W LLC resonant converter. The result shows that the proposed control method provides fast dynamic performance and stable operation under a light-load condition without an additional slope compensation circuit.
TL;DR: In this paper, a generalized stochastic resonance (GSR) based instantaneous frequency estimation method is proposed for frequency modulated (FM) signal embedded in strong noise, which can enhance weak FM signals with time varying frequency.
TL;DR: The results of experiments show the optimized flexible mechanism can provide maximum velocity and largest driving force, and the rectified driving signal can enhance the velocity performance for 20.56% and 29.48% more than the normal sawtooth driving signal under 100 Hz and 1000 Hz.
TL;DR: A deep convolutional neural network is used to classify the arterial blood pressure (ABP) signal, which indicates the ABP signal has beneficial information about heart performance as efficient as the ECG signal.
TL;DR: In this paper, a novel method of feature extraction is proposed to identify the RFF of LFM signal, which can provide a new kind of feature of RFF for the recognition with high accuracy.
Abstract: Linear frequency modulation (LFM) is a spread spectrum modulation technique that does not require pseudo-random coding sequences, and it is widely used in radar and sonar technology. In many applications, it is required to distinguish the source of the signal. The radio frequency fingerprint (RFF) is one of the most promising methods to identify the signal sources because of its uniqueness. In this paper, a novel method of feature extraction is proposed to identify the RFF of LFM signal. The proposed method can provide a new kind of feature of RFF for the recognition with high accuracy. The feature can be extracted from the whole signal without separating transient signals and steady-state signals, and it independents of the content of the signal. The proposed method can provide the recognition accuracy as high as 93.68%.
TL;DR: The experimental results show that the sea clutter detection method based on LSTM prediction error frequency domain conversion has strong applicability and higher accuracy, and the detection performance is improved by 30%.
Abstract: Weak signal detection has always been a hot spot in the signal processing field. In this paper, the chaotic and large data size characteristics of sea clutter are analyzed, the advantage of the Long and Short Term Memory network (LSTM) is taken to design a weak signal detection method based on deep learning. The reconstructed phase space signal is used as the input of LSTM network, the length of training data is determined by embedding dimension and delay time, and a chaotic prediction model is established to detect weak signals from the prediction error. In order to improve the detection performance, reduce the missing rate of deep learning method for small feature signal, frequency domain conversion of the prediction error is conducted, the spectrum of the prediction error of different distance gates is compared to locate the coordinates of the weak signal. The experimental results show that the sea clutter detection method based on LSTM prediction error frequency domain conversion has strong applicability and higher accuracy, and the detection performance is improved by 30%.
TL;DR: An adaptive nonlinear ANC system for interior noise, which contains noise signal decomposition, multi-network reconstruction model and Variable step-size LMS (VSS-LMS) algorithm, which can guarantee stable work of the interior noise control.
TL;DR: In this article, the authors proposed a total least squares wavelength-tuning phase-shifting algorithm (TLSWPA) to obtain the signal frequencies and demodulate the initial phases of the measured surfaces simultaneously.