Pulse Signal Research Articles

Repeated K-means Clustering Algorithm For Radar Sorting

In modern electronic warfare, a number of radar emitters are in operation, causing radar receivers to receive high-density signal pulses that occur simultaneously. To analyze the radar signals more accurately and identify enemies, the sorting process of high-density radar signals is very important before analysis. Recently, machine learning algorithms, specifically K-means clustering, are the subject of research aimed at improving the accuracy of radar signal sorting. One of the challenges faced by these studies is that the clustering results can vary depending on how the initial points are selected and how many clusters number are set. This paper introduces a repeated K-means clustering algorithm that aims to accurately cluster all data by identifying and addressing false clusters in the radar sorting problem. To verify the performance of the proposed algorithm, experiments are conducted by applying it to simulated signals that are generated by a signal generator.

Flexible pressure sensor with metallic reinforcement and graphene nanowalls for wearable electronics device

In recent years, flexible pressure sensors have been seen widespread adoption in various fields such as electronic skin, smart wearables, and human-computer interaction systems. Owing to the electrical conductivity and adaptability to flexible substrates, vertical graphene nanowalls (VGNs) have recently been recognized as promising materials for pressure-sensing applications. Our study presented the synthesis of high-quality VGNs via plasma enhanced chemical vapor deposition and the incorporation of a metal layer by electron beam evaporation, forming a stacked structure of VGNs/Metal/VGNs. Metal nanoparticles attached to the edges and surfaces of graphene nanosheets can alter the charge transport paths within the material to enhance the responsiveness of the sensor. This layered structure effectively fulfilled the requirements of flexible pressure sensors, exhibiting high sensitivity (40.15 kPa-1), low response time (88 ms), and short recovery time (97 ms). The pressure sensitivity remained intact even after 1000 bending cycles. Additionally, the factors contributing to the impressive pressure-sensing performance of this composite were found and its capability to detect human pulse and finger flexion signals was demonstrated, making it a promising candidate for applications of wearable electronics devices.

An accurate semi-empirical model for PMT pulse signal analysis.

The energy information of pulse signals is significantly important for applications such as computed tomography (CT), positron emission tomography (PET), and research on defects in condensed matter. Time-over-threshold (TOT) and multi-voltage threshold (MVT) are commonly used digitization methods in sampling pulse signal. However, both approaches rely on a mathematical model of the pulse signal to derive energy information. This study proposes a semi-empirical mathematical model for pulse signals formation process in scintillation crystal-coupled photomultiplier tube(PMT) probes, by utilizing the CR-RC shaping method. This mathematical model accurately describes output of the PMT pulse signals. This study analyzes a substantial dataset of pulse signals, comparing the performance of the newly designed mathematical model with that of the double exponential function in terms of their ability to fit pulse signals. The results indicate that the mathematical model developed herein achieves an average R2 of 0.9255, significantly surpassing the 0.9155 of the double exponential function, thereby demonstrating its superior fitting efficacy.

A New Way of Resolver to Digital Converter in a Steady System

This paper presents a simple method to detect the phase of a rotor based on the resolver equipped motor in a steady status. There are three pulses signals which are used to produce the phase edge at 0 degree, 90 degrees, 180 degrees and 360 degrees. This can be used to reset the integrator which is used to integrate the phase differences. Meanwhile the carrier edge can be used to counted as the phase angle of rotor. When the system is in a steady status it is easy to get the phase angle by using a digital counter.

Optically Modulated Nanofluidic Ionic Transistor for Neuromorphic Functions

Neuromorphic systems that can emulate the behavior of neurons have garnered increasing interest across interdisciplinary fields due to their potential applications in neuromorphic computing, artificial intelligence and brain‐machine interfaces. However, the optical modulation of nanofluidic ion transport for neuromorphic functions has been scarcely reported. Herein, inspired by biological systems that rely on ions as signal carriers for information perception and processing, we present a nanofluidic transistor based on a metal‐organic framework membrane (MOFM) with optically modulated ion transport properties, which can mimic the functions of biological synapses. Through the dynamic modulation of synaptic weight, we successfully replicate intricate learning‐experience behaviors and Pavlovian associate learning processes by employing sequential optical stimuli. Additionally, we demonstrate the application of the International Morse Code with the nanofluidic device using patterned optical pulse signals, showing its encoding and decoding capabilities in information processing process. This study would largely advance the development of nanofluidic neuromorphic devices for biomimetic iontronics integrated with sensing, memory and computing functions.

Self-Powered Wearable Displacement Sensor for Continuous Respiratory Monitoring and Human-Machine Synchronous Control.

Flexible wearable electronic devices play a vital role in daily monitoring, medical diagnosis, and human-computer interaction, and such devices have a great demand for portability, integration, comfort, and self-power. In this study, a triboelectric nanogenerator integrated into a flexible chest belt is proposed as a displacement sensor to monitor the displacement and frequency of thoracic expansion. Based on three parallel interpolation electrode structures with phase differences, the Triboelectric Nanogenerators's(TENG) output signal pulse number can characterize the sliding displacement, with a resolution of more than 1mm and a durability of more than 700,000 cycles. Based on the flexible printed circuit processing technology, the volume of the sensor is less than 8.5cm3, and the weight is less than 3.2g, which improves the portability of the device. Based on wireless radio frequency technology, the collected signals are transmitted to the upper computer, and then the monitoring of respiratory physiological signals and the human-machine synchronous control of the ventilator are achieved within the overshoot of 1.5% and the control error of 5% through a simulation machine. This work provides a sensing method for daily and medical respiratory monitoring and demonstrates the enormous potential of frictional electric sensors in intelligent medical applications.

SIMTAM: Generation Diversity Test Programs for FPGA Simulation Tools Testing Via Timing Area Mutation

Field-Programmable Gate Array (FPGA) timing simulation is essential in electronic circuit design, allowing for the verification of timing characteristics like delays and clock frequencies. However, bugs in timing simulation tools can lead to inaccurate results, potentially causing designers to miss critical issues in chip performance. Traditional testing methods often fall short in thoroughly assessing these tools, as current FPGA testing primarily focuses on synthesis and behavioral simulation, neglecting timing aspects. To address this issue, we propose SIMTAM for testing timing simulation tools. Specifically, SIMTAM consists of three components: equivalent delay region construction, diversity program segment generation, and differential testing. Given a seed circuit design file written by hardware description language such as Verilog, the delay region construction component randomly identifies delay structures for inertial delay in the design file to construct equivalent delay sleep regions. In the sleep region, the simulator skips the signal pulse whose width is less than the specified delay, thus ensuring the equivalence of the variations. The diversity program segment generation component combines Verilog expressions using generation operators and inject them into the sleep region to generate diverse design files. The differential testing component compares the seed and variant design files to find compilation inconsistency issues. In five months, SIMTAM reported 16 bugs to developers in two popular timing simulation tools Iverilog and Vivado; ten of which are confirmed.

SINGLE-CYCLE PULSE WAVEFORM RECOGNITION METHOD BASED ON SVM

The single-cycle pulse waves’ morphological characteristics can reflect rich physiological and pathological information about the human cardiovascular system, playing an important role in continuous blood pressure monitoring and cardiovascular disease risk warning. Pulse signals belong to weak physiological signals, and the acquisition process is easily affected by factors such as adjacent channel interference and motion artifacts, leading to abnormal cycles and affecting subsequent feature extraction. Therefore, based on support vector machines (SVM), a single-cycle pulse waveform recognition algorithm is proposed. Using a multi-channel pulse wave acquisition device to collect radial artery pulse signals from 150 subjects. Preprocess the signal to obtain a single-cycle pulse waveform. A total of 54 frequency domain and time-frequency domain feature parameters were extracted by using Fourier transform and wavelet transform to extract the frequency domain and time-frequency domain features. Use the principal components analysis (PCA) method to reduce parameter dimensions. Using the SVM for model training to achieve the classification of single-cycle effective pulse signals, pseudo noise and interference signals. The results show that the algorithm’s classification accuracy is 97.42%, indicating that the algorithm can effectively identify pulse signals, pseudo noise and interference signals, laying the foundation for modeling and suppressing interference signals in the next step.

METHODS OF COMPLEX USE OF ELECTROMAGNETIC WAVES FOR SEARCHING FOR HYDROCARBONS

The study of sounding modes based on the complex use of modulated and radio pulse signals for determining the properties of anisotropic medium above hydrocarbons was carried out. For the frequency modulation mode, regularities in the change in the components of the permittivity tensor of the medium for the right -hand polarization of electromagnetic waves were established with varying modulation parameters. The modulus and phase of the surface impedance components Ż11 and Ż21 were investigated. The revealed manifestations of an abrupt change in the real components of the permittivity tensor component 3  are of practical importance for exploration geophysics. The resonant frequencies and imaginary component for the right-hand polarization of electromagnetic waves of the permittivity tensor of the medium for modulated, dual-frequency and radio pulse signals were calculated. The modeling results can be used in electrical exploration for developing methods and equipment for searching and detecting hydrocarbons.

On the theory of spectral compression-assisted optical temporal differentiation

Bandwidth limitation represents a significant factor that degrades the performance of optical devices. The dimensions, composition and configuration of optical devices impose intrinsic constraints on processing broadband optical pulse signals. The enhancement of the response bandwidth of optical devices represents a significant challenge. In this study, we put forward the theory of self-similar spectral compression (SSSC), which involves solving the nonlinear Schrödinger equation with variable coefficients by using the Taylor expansion and residual theorem. The spectral waveform can be precisely preserved in the process of SSSC, leading to a predictable compression factor without pedestals. To demonstrate the effectiveness of the proposed SSSC, we present a case study by designing an on-chip optical time-domain differentiator (OTD) system including a silicon-based tapered spiral waveguide. A 200-fs chirped pulse is well differentiated at multiple orders in the OTD system. Although the linear loss of spiral waveguide has a detrimental impact on SSSC, the broadband spectrum can still be self-similarly compressed, leading to a reduction of differentiation deviation of 22.5 times. The proposed SSSC theory offers valuable guidance for designing all-optical signal processing systems with high spectral resolution and low signal error.

A Robust Low‐Power Power‐On‐Reset Circuit With Dual Threshold Method

ABSTRACTIn this paper, a robust low‐power power‐on‐reset (POR) circuit with dual threshold method is proposed. The current‐based circuit exhibits good robustness with respect to process, voltage, temperature, and supply ramp variations. In contrast to conventional delay‐based pulse generation approaches, a dual threshold method is introduced to generate POR and brown‐out‐reset (BOR) pulse signals, resulting in ultralow quiescent current and a compact area. Implemented in the 55‐nm CMOS process, the proposed circuit achieves an accurate trigger‐point voltage with a temperature coefficient of 90.4 ppm/°C and a deviation to the ramp time of 2.9% for a range from 100 μs to 1 s. Furthermore, the quiescent current and active area are 0.3 nA and 4834 μm2, respectively, making it particularly suitable for energy harvesting systems.

Alkali Ion-Accelerated Gelation of MXene-Based Conductive Hydrogel for Flexible Sensing and Machine Learning-Assisted Recognition.

Conductive hydrogels are promising active materials for wearable flexible electronics, yet it is still challenging to fabricate conductive hydrogels with good environmental stability and electrical properties. In this work, a conductive MXene/LiCl/poly(sulfobetaine methacrylate) hydrogel system was successfully prepared with an impressive conductivity of 12.2 S/m. Interestingly, the synergistic effect of MXene and a lithium bond can significantly accelerate the polymerization process, forming the conductive hydrogel within 1 min. In addition, adding LiCl to the hydrogel not only significantly increases its water retention ability, but also enhances its conductivity, both of which are important for practical applications. The flexible strain sensors based on the as-prepared hydrogel have demonstrated excellent monitoring ability for human joint motion, pulse, and electromyographic signals. More importantly, based on machine learning image recognition technology, the handwritten letter recognition system displayed a high accuracy rate of 93.5%. This work demonstrates the excellent comprehensive performance of MXene-based hydrogels in health monitoring and image recognition and shows potential applications in human-machine interfaces and artificial intelligence.

Performance study of a new LiCAF:Ce detector developed for high-efficient neutron detection in intense γ-ray fields

When detecting fast and thermal neutrons in intense γ-ray fields, it is challenging to discriminate between pulse signals due to neutron and γ-rays, even when using pulse-shape-discrimination techniques, because the trailing pulse signals overlap at high pulse rates. Some nuclear facilities have faced challenging problems for dispersed nuclear fuel (or nuclear fuel debris), radioactive wastes, and other radioactive materials during decommissioning. Particularly, high-efficiency neutron detection in intense γ-ray fields is required for exploring dispersed nuclear fuel and for criticality monitoring. LiCaAlF6 (LiCAF):Ce has suitable properties of high 6Li density and fast decay times for high-efficiency neutron detection in intense γ-ray fields. A new LiCAF:Ce detector with an ultra-thick (99 μm) crystal and optimized readout was developed. The neutron detection performance in an intense γ-ray field was investigated and compared to that using a Li glass (KG2) detector. The LiCAF:Ce and KG2 detectors were used to detect a sealed 252Cf neutron source (neutron emission rate of ∼ 4.11 × 105 s-1) using a 5 cm thick high-density polyethylene (HDPE) block moderator located at the front of the detector. At the air kerma rates at the front surface of the HDPE block (Ds ) of up to 1.07 Gy/h, the effective neutron count rate (n eff) for the LiCAF:Ce detector was the same within margins of errors, but it decreased by 5.7 ± 0.8% at 2.97 Gy/h. In contrast, for the KG2 detector, with Ds increased up to 1.07 Gy/h, n eff for KG2 increased up to 20 ± 1.0 % at 1.07 Gy/h. Then, n eff decreased by 20 ± 1.0% at 2.97 Gy/h. Therefore, the LiCAF:Ce detector exhibited a smaller influence on neutron count rates by γ-rays compared to the KG2 detector because of the faster decay time and optimization of digital pulse processing.

Assessment of arteriosclerosis based on lognormal fitting

Objective. Pulse pressure waves contain information about human physiology. There is a need for a simple, accurate way to know cardiovascular health in the clinic, so as to realize the implementation of convenient and effective early health monitoring for patients with arteriosclerosis.Approach. This study proposes an arteriosclerosis assessment method based on fitting a lognormal function, along with improving a conventional electronic sphygmomanometer. During the deflation phase of blood pressure measurement, the cuff pressure was kept constant (40 mmHg) and an additional 10 s of pulse signal was acquired. To derive the pulse pressure waveforms for a single cycle, the acquired pulse data of 101 cases were preprocessed in this study, including filtering for noise removal, onset point identification, removal of baseline drift, and normalization. In this study, an improved pulse resolution algorithm is proposed for the multimodal problem of the pulse wave, combining waveform matching and threshold setting, and finally obtaining the resolution parameters of the lognormal function with an average error less than 1.5%.Main results. According to the correlation analysis, the resolved parametersA1,W2,C2,W3, andC3were significantly correlated with brachial-ankle Pulse Wave Velocity, and the absolute correlation range in 0.17-0.53, which can be used as a reference index for arteriosclerosis. An arteriosclerosis assessment model was constructed based on the support vector mechanism, and the prediction accuracy was 91.1%.Significance. This study provides a new solution idea for the arteriosclerosis assessment method as well as the pulse resolution algorithm, which has a greater reference value.

Artificial Neural Network-Based Hybrid Controller for Electric Vehicle Applications

Power management among different energy sources of electric vehicles (EV) is one of the complex issues during the transition from one to another. A specific control is modeled based on the current and speed range of the electric motor named as Measurement of Parameter-Based Controller (MPBC), which will play a key role during transition of energy sources as per the load requirement. Two bidirectional converters are utilized to control the pulse signals generated by the traditional controllers which are connected at the battery and Supercapacitors (SCap) ends, which are treated as passive sources of the system. The Controller's artificial neural network (ANN), fuzzy logic (FLC), and proportional-integral (PI) are utilized to generate the pulse signal to the switches present in the converters by load. Further, specific controller MPBC is combined with three controllers ANN/FLC/PI individually and obtained three separate hybrid controllers as per the proposed control technique. The MPBC+PI/FLC/ANN controller-based MATLAB/Simulink model was designed, and applied to the electric motor individually at different load conditions. This model considered three different power delivery states from the PV array and assessed the motor's performance under different load scenarios. Compare the three hybrid controllers' final results to find out which one is more effective than the others.

Finite-difference time-domain simulation of THz light pulse with orbital angular momentum produced using a spiral phase plate

A silicon spiral phase plate (SPP) was proposed for a pulsed terahertz signal to produce orbital angular momentum with a topological charge of $l=1$. The resulting field distribution after the signal passes through the SPP was simulated using finite-difference time-domain method and observed at different propagation distances. It shows that the helical spatial structure and optical vortex were best observed at the farthest distance of 7.5 cm. Additionally, the cross-section field distribution at different times as the signal passes through the SPP indicates a helical wavefront structure. Moreover, the output of a source with different central frequencies was observed when using the same SPP and showed a hollow distribution indicating a vortex despite not being located in the center.

Design and Implementation of Eight-Way Call System Based on Digital Integrated Circuits

This paper introduces the construction of an eight-channel call system using medical callers. The circuit enables the call signal to be sent to the 74HC148 priority encoder for encoding if any of the channels make a call. The encoded signal is processed by the 74LS283 and then output from the 74LS373 latch to the 4511BD decoding and driving circuit. The output of the decoding and driving circuit is displayed on the display circuit, showing the number of the channel that made the call. Meanwhile, the control signal triggers a monostable oscillator circuit composed of a 555 timer, which generates a temporary stable output signal with a pulse width of about 2s. The pulse signal drives a multivibrator circuit composed of a 555 timer, which causes the LED to work and output an alarm signal. The alarm state can be eliminated manually by pressing a key.

Automated sleep apnea detection from snoring and carotid pulse signals using an innovative neck wearable piezoelectric sensor

This study introduces an innovative wearable neck piezoelectric sensor (NPS) that measures snoring vibrations and carotid pulsations, offering a significant advancement in sleep apnea syndrome (SAS) diagnosis. Utilizing advanced algorithms like discrete wavelet transform and dynamic thresholding, the NPS detects snoring events with 83% accuracy, comparable to polysomnography, and calculates key metrics such as the snoring index (SI) and normalized snoring vibration energy (SVE%). Unlike traditional methods, the SVE% from NPS directly correlates with subjective assessments of snoring severity. It also measures carotid pulsation metrics such as pulse rate and the standard deviation of normal-to-normal intervals, achieving 85% accuracy in sleep phase determination against polysomnography. Moreover, NPS surpasses traditional methods in SI and SVE% accuracy, closely aligning with clinical evaluations of SAS severity. This user-friendly technology automates the measurement of critical snoring metrics, transforming SAS diagnosis and treatment by enhancing accessibility and efficiency for healthcare providers and patients.

Percutaneous decannulation of extracorporeal membrane oxygenation using MANTA device: A real-world single-center experience.

The MANTA vascular closure device (VCD) represents a novel approach to achieving hemostasis after large-bore femoral access procedures. Numerous clinical studies have evaluated the efficacy of the MANTA device across a range of patient populations undergoing different procedures. However, there is still a paucity of data available concerning the use of MANTA devices in aiding the decannulation of venoarterial extracorporeal membrane oxygenation (VA-ECMO). To present our single-center experience of utilizing the MANTA VCD in patients undergoing this procedure. This single-center study included all patients undergoing percutaneous decannulation of femoral VA-ECMO using the MANTA plug-based VCD between January 2021 and October 2023 at University Hospitals Cleveland Medical Center. Inclusion criteria were adult patients who required prolonged (> 24 hours) hemodynamic support with VA-ECMO. Outcomes included all-cause mortality, hemostasis, bleeding, limb ischemia, and site infection. This is a retrospective cohort study of 19 patients with a mean age of 56.8 years. Twelve of them were males with a mean body mass index of 29. The most common extracorporeal membrane oxygenation indication was acute coronary syndrome complicated by cardiogenic shock at 36.8%. The mean length of intensive care unit stay for these patients was 18.8 ± 8.42 days. Seventeen out of 19 patients survived to discharge. The MANTA device was successfully deployed in 19 patients, with 10 procedures conducted at the bedside and 9 in an operating room setting. Complete hemostasis was achieved within 5 minutes of MANTA deployment in 17 out of 19 patients. In 2 patients manual compression after Manta deployment was required to achieve adequate hemostasis. Additionally, acute lower extremity ischemia was noted in two patients, necessitating endovascular interventions. No infections were reported at the site of MANTA deployment. Overall, based on our experience and that of other centers, the MANTA VCD has proven to be a simple, safe, and effective percutaneous technique for facilitating in the OR, but most of all it opens the opportunity for bedside VA-ECMO decannulation. Post-decannulation ischemic complications are higher in this series of sick patients when compared with elective procedures like transcatheter aortic valve replacement and endovascular aneurysm repair. Additionally, operators should be mindful of the incidence of ischemic complications. Distal Doppler pulse signals should always be checked, to indicate bailout options when this occurs.

Contrasting effect of high-Z coating on proton acceleration from thin transparent low-Z foil target

Abstract In the present work, we investigate the impact of a thin metallic coating on proton acceleration from transparent dielectric foils. A substantial difference in the experimental results is observed based on the placement of the thin metal coating—either on the front surface (the side facing the laser) or on the rear surface of the foil. In the former case, we observed an enhancement in both the energy and flux of the accelerated protons/ions. However, in the latter case, the thin metal coating was found to have a highly detrimental effect on the acceleration process. Measurements conducted on transmitted laser pulse signals confirm the crucial role of the intensity-dependent target material transparency and the laser pre-pulse playing vital roles in determining the proton/ion acceleration dynamics. Numerical simulations involving radiation hydrodynamics followed by two-dimensional particle-in-cell simulations confirm the experimental observations.