Pulse Detection Method Research Articles

Characterization of sugar composition in Chinese royal jelly by ion chromatography with pulsed amperometric detection

An ion chromatography coupled with pulsed amperometric detection (IC-PAD) method was developed for the determination of sugars in royal jelly (RJ). The method enables quantification of 19 sugars with higher sensitivity than HPLC method. Good linearity was observed in the range of 0.02–500 mg L–1 with coefficients of determination (R2) ≥ 0.9994. The limits of detection (LODs) and limits of quantification (LOQs) were in the range of 1.0–110 μg L–1 and 3.7–380 μg L–1, respectively. The average recoveries ranged from 91.0% to 108.0%. This simple method can be an effective alternative to GC method, which requires complicated purification and derivatization steps. It was used for the analysis of 100 Chinese RJ samples from three different areas and the results of analyzed sugars were found to be in agreement with those reported in literatures. The sugar profile results have suggested that some minor sugars are better markers for discrimination in relation to geographical origin.

Surface Discharge Analysis of High Voltage Glass Insulators Using Ultraviolet Pulse Voltage

Surface discharges are precursors to flashover. To pre-empt the occurrence of flashover incidents, utility companies need to regularly monitor the condition of line insulators. Recent studies have shown that monitoring of UV signals emitted by surface discharges of insulators is a promising technique. In this work, the UV signals’ time and frequency components of a set of contaminated and field-aged insulator under varying contamination levels and degrees of ageing were studied. Experimental result shows that a strong correlation exists between the discharge intensity levels under varying contamination levels and degree of ageing. As the contamination level increases, the discharge level of the insulator samples also intensifies, resulting in the increase of total harmonic distortion and fundamental frequencies. Total harmonic distortion and fundamental frequencies of the UV signals were employed to develop a technique based on artificial neural networks (ANNs) to classify the flashover prediction based on the discharge intensity levels of the insulator samples. The results of the ANN simulation showed 87% accuracy in the performance index. This study illustrates that the UV pulse detection method is a potential tool to monitor insulator surface conditions during service.

Surface discharge characteristics and initiation mechanism of PEEK in nitrogen under semi-square voltage

The surface discharge behaviors of polyetheretherketone (PEEK) in nitrogen under both positive and negative semi-square voltage were investigated using the current pulse detection method by non-inductive resistor and optical signal detection method by photomultiplier and digital camera. A 50Hz positive or negative semi-square voltage was applied to a rod-plane electrode system, and two types of surface discharge in a voltage cycle were found: one forward discharge and one back discharge. The characteristics and initiation mechanism of the two types of surface discharge were explored. The experimental results showed that surface discharges between cycles were independent. Based on the independence, the time-lag characteristics of surface discharge were obtained. An improvement on Laue-Zuber time-lag theory was made to fit the time-lag characteristics of forward discharge and back discharge. The mean time-lag decreased with the increase of voltage for both forward discharge and back discharge, and the relation between mean time-lag and applied voltage could be modeled by inverse power law. Comparative analysis on the characteristics of back discharge and forward discharge under opposite voltage was performed, and the characteristics of back discharge and forward discharge under opposite voltage were homogenous. In addition, the initiation mechanism of the two types of discharge was discussed. The initiation of forward discharge is believed to be mainly determined by the time-lag and the electric field caused by the applied voltage, while the initiation of back discharge is believed to be mainly determined by the time-lag and the electric field induced by the residual surface charge left by the forward discharge in the same cycle. Verification tests under positive semi-square voltage with different fall time were conducted to validate the initiation mechanism.

The metal thickness detection using pulsed eddy-current computation and detection method

Through detecting method of pulsed eddy-current (PEC) and according to thickness testing model of multi-layer metal, infer the mathematical model of eddy current testing method in single-layer metal. Use Maxwell field equations to find solutions of vector magnetic potential in its boundary conditions thus infer the impedance of hollow coil placed right above metal. Analyze the variation relationship between induced current and metal thickness in theory level. (1) Obtain three characteristic signals of induced current: altitude of current peak value (ACPV), time of reaching current peak (TRCP) and time of traversing zero point (TTZP). The thickness of the metal and the distance between the metal and coil were obtained. (2) Introduce the concept of the lift-off intersection point (LOI) and puts forward a new method of metal thickness detection based on the LOI. By analyzing the results of the experiment, it confirms the feasibility of the LOI of measurement in the metal thickness.

Development of a diagnostic method for Parkinson's disease by reverse-phase high-performance liquid chromatography coupled with integrated pulsed amperometric detection

We developed a diagnostic method for Parkinson's disease by simultaneously analyzing biogenic amines and their metabolites using reverse-phase high-performance liquid chromatography coupled with integrated pulsed amperometric detection (RP-HPLC-IPAD) method. Dopamine (DA), 3, 4-dihydroxyphenylacetic acid (DOPAC), serotonin (5-HT), 5-hydroxyindolacetic acid (5-HIAA), and homovanillic acid (HVA) were used as biomarkers to diagnose Parkinson's disease. All target components were detected with good sensitivity using sodium hydroxide (as a post-column eluent). The limit of detection (S/N = 3) and limit of quantification (S/N = 10) of the target components ranged from 0.020 to 2.400 ng and from 0.080 to 8.000 ng, respectively. The coefficients of linear regression ranged from 0.9996 to 1.0000, all inter-day and intra-day precision values were <3.43%, and the average recovery and RSD ranged from 97.55 to 103.60% and 0.22 to 4.79% for mice striatum samples. This method exhibited good selectivity, sensitivity, and reproducibility and can be used directly without any pretreatment steps. Our method will be useful as a tool to diagnose Parkinson’s disease.

Multi-pulse laser ranging method for pre-detection with high frequency resonance

Based on the measurement principle of pulse time-of-flight, non-cooperative target ranging technology using a pulsed laser diode (LD) as a light source has received widespread attention in recent years. Using leading edge timing method to directly detect pulses, its measuring range is about a few tens of meters and only a cm-level single-shot accuracy could be reached due to the limitations of its pulse width and eye-safe laser power of the LD, which cannot meet the needs of most applications. Especially, in order to increase its receiver channel bandwidth from hundreds of MHz to even a few GHz to reduce its work error, its distance measurement accuracy and ranging distance are significantly degraded as its signal-to-noise ratio (SNR) decreases. When a target is out of its measuring range, the back diffused laser pulse signal with an SNR of much less than 1 will be too weak to be extracted even with digital correlation processing technology.In this paper, using a pre-detection with high frequency resonance and multi-pulse correlation processing, a new ranging method to solve long ranging targets with high precision is proposed for the first time. Through the pre-detection circuit with high frequency resonance, a pulsed photocurrent signal is amplified and filtered, and then converted into a bipolar attenuation oscillation signal. Thereafter, its SNR is further improved by a new pulse function constructed through multi-pulse correlation processing. The peak of the new pulse is constant and its zero crossing point is found to be the timing point to calculate the target distance. The method has a better SNR and a high timing accuracy. And the detected ranging distance could be increased over one thousand meters or more. Theoretical calculation results show that the minimum detectable peak current of light pulse is around 17 nA in the method. Comparing with the direct pulse detection method, its SNR can increase 60 times. When a received peak of a photocurrent pulse is within a dynamic range of 1:10000, its work error is less than 0.1 ps. A pulsed laser rangefinder is developed based on the principle. And its average laser emission power is about 1 mW. Its measurement ranging without cooperative target is greater than 2000 m. Its distance measurement accuracy increases up to ± (3 mm+2 ppm) in a range of 1.5-300 m. For a long ranging target, its distance measurement accuracy is ± (10 mm+10 ppm). The rangefinder system is used in a total station product and can be used to measure large-scale engineering structures (such as roads, bridges, dams, tunnels, subways, etc.), building structures and industrial sites.

Detection of multipoint pulse waves and dynamic 3D pulse shape of the radial artery based on binocular vision theory

Background and objectivePulse signals contain a wealth of human physiological and pathological information. How to get full pulse information is especially challenging, and most of the traditional pulse sensors can only get the pulse wave of a single point. This study is aimed at developing a binocular pulse detection system and method to obtain multipoint pulse waves and dynamic three-dimensional pulse shape of the radial artery. MethodsThe proposed pulse detection approach is image-based and implemented by two steps. First, a new binocular pulse detection system is developed based on the principle of pulse feeling used in traditional Chinese medicine. Second, pulse detection is achieved based on theories and methods of binocular vision and digital image processing. In detail, the sequences of pulse images collected by the designed system as experimental data are sequentially processed by median filtering, block binarization and inversion, area filtering, centroids extraction of connected regions, to extract the pattern centroids as feature points. Then stereo matching is realized by a proposed algorithm based on Gong-shape scan detection. After multipoint spatial coordinate calculation, dynamic three-dimensional reconstruction of the thin film shape is completed by linear interpolation. And then the three-dimensional pulse shape is achieved by finding an appropriate reference time. Meanwhile, extraction of multipoint pulse waves of the radial artery is accomplished by using a suitable reference origin. The proposed method is analyzed from three aspects, which are pulse amplitude, pulse rate and pulse shape, and compared with other detection methods. ResultsAnalysis of the results shows that the values of pulse amplitude and pulse rate are consistent with the characteristics of pulse wave of the radial artery, and pulse shape can correctly present the shape of pulse in space and its change trend in time. The comparison results with the other two previously proposed methods further verify the correctness of the presented method. ConclusionsThe designed binocular pulse detection system and proposed algorithm can effectively detect pulse information. This tactile visualization-based pulse detection method has important scientific significance and broad application prospects and will promote further development of objective pulse diagnosis.

Validated high-performance anion-exchange chromatography with pulsed amperometric detection method for the determination of residual keratan sulfate and other glucosamine impurities in sodium chondroitin sulfate

An efficient and sensitive analytical method based on high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) was devised for the determination of glucosamine (GlcN) in sodium chondroitin sulfate (CS). Glucosamine (GlcN) is intended as marker of residual keratan sulfate (KS) and other impurities generating glucosamine by acidic hydrolyzation. The latter brings CS and KS to their respective monomers. Since GlcN is present only in KS we developed a method that separates GlcN from GalN, the principal hydrolytic product of CS, and then we validated it in order to quantify GlcN. Method validation was performed by spiking CS raw material with known amounts of KS. Detection limit was 0.5% of KS in CS (corresponding to 0.1μg/ml), and the linear range was 0.5–5% of KS in CS (corresponding to 0.1–1μg/ml). The optimized analysis was carried out on an ICS-5000 system (Dionex, Sunnyvale, CA, USA) equipped with a Dionex Amino Trap guard column (3mm×30mm), Dionex CarboPac-PA20 (3mm×30mm) and a Dionex CarboPac-PA20 analytical column (3mm×150mm) using gradient elution at a 0.5ml/min flow rate. Regression equations revealed good linear relationship (R2=0.99, n=5) within the test ranges. Quality parameters, including precision and accuracy, were fully validated and found to be satisfactory. The fully validated HPAEC-PAD method was readily applied for the quantification of residual KS in CS in several raw materials and USP/EP reference substance. Results confirmed that the HPAEC-PAD method is more specific than the electrophoretic method for related substance reported in EP and provides sensitive determination of KS in acid-hydrolyzed CS samples, enabling the quantitation of KS and other impurities (generating glucosamine) in CS.

Simultaneous determination of 13 carbohydrates using high-performance anion-exchange chromatography coupled with pulsed amperometric detection and mass spectrometry.

A simple, accurate, and highly sensitive method was developed for the determination of 13 carbohydrates in polysaccharide of Spirulina platensis based on high-performance anion-exchange chromatography coupled with pulsed amperometric detection and mass spectrometry. Samples were extracted with deionized water using ultrasonic-assisted extraction, and the ultrasound-assisted extraction conditions were optimized by Box-Behnken design. Then the extracted polysaccharide was hydrolyzed by adding 1mol/L trifluoroacetic acid before determination by high-performance anion-exchange chromatography coupled with pulsed amperometric detection and confirmed by high-performance anion-exchange chromatography coupled with mass spectrometry. The high-performance anion-exchange chromatography coupled with pulsed amperometric detection method was performed on a CarboPac PA20 column by gradient elution using deionized water, 0.1mol/L sodium hydroxide solution, and 0.4mol/L sodium acetate solution. Excellent linearity was observed in the range of 0.05-10mg/L. The average recoveries ranged from 80.7 to 121.7%. The limits of detection and limits of quantification for 13 carbohydrates were 0.02-0.10 and 0.2-1.2μg/kg, respectively. The developed method has been successfully applied to ambient samples, and the results indicated that high-performance anion-exchange chromatography coupled with pulsed amperometric detection and mass spectrometry could provide a rapid and accurate method for the simultaneous determination of carbohydrates.

A novel method for pulsometry based on traditional iranian medicine

Arterial pulse measurement is one of the most important methods for evaluation of healthy conditions. In traditional Iranian medicine (TIM), physician may detect radial pulse by holding four fingers on the patient's wrist. By using this method, under standard condition, the detected pulses are subjective and erroneous, in case of weak and/or abnormal pulses, the ambiguity of diagnosis may rise. In this paper, we present an equipment which is designed and implemented for automation of traditional pulse detection method. By this novel system, the developed noninvasive diagnostic method and database based on the TIM are way forward to apply traditional medicine and diagnose patients with present technology. The accuracy for period measuring is 76% and systolic peak is 72%.

Detection of UV Pulse from Insulators and Application in Estimating the Conditions of Insulators

Abstract Solar radiation in the band of 240–280 nm is absorbed by the ozone layer in the atmosphere, and corona discharges from high-voltage apparatus emit in air mainly in the 230–405 nm range of ultraviolet (UV), so the band of 240–280 nm is called UV Solar Blind Band. When the insulators in a string deteriorate or are contaminated, the voltage distribution along the string will change, which causes the electric fields in the vicinity of insulators change and corona discharge intensifies. An UV pulse detection method to check the conditions of insulators is presented based on detecting the UV pulse among the corona discharge, then it can be confirmed that whether there exist faulty insulators and whether the surface contamination of insulators is severe for the safe operation of power systems. An UV-I Insulator Detector has been developed, and both laboratory tests and field tests have been carried out which demonstrates the practical viability of UV-I Insulator Detector for online monitoring.

Three Pulse Cable Fault Detection Method Based on Wavelet Threshold Denoising

This paper introduced the principle of three pulse method and the method’s advantages and disadvantages on cable fault detection, modeled three pulse detection method of cable fault in the Simulink environment, analyzed the Wavelet threshold denoising effect on cable fault detection accuracy under different threshold selection rules, and proposed a three pulse detection method based on the wavelet threshold de-noising.

Development of a liquid chromatographic method for the quantification of paromomycin. Application to in vitro release and ex vivo permeation studies

We have developed a reversed phase high performance liquid chromatography pulsed amperometric detection (RPHPLC-PAD) method for the determination of paromomycin. It is sensitive, repeatable, and selective without the pretreatment step.Trifluoroacetic acid–water was utilized as the eluent and detected by PAD under NaOH alkaline conditions. The paromomycin detection limit (S/N=3.3) was 2μgmL−1 and the quantification limit (S/N=10) was 6μgmL−1. Coefficients of linear regression were higher than 0.99 for concentrations between 6.25 and 200μgmL−1. The intra and inter-day precision (RSD) was less than 6.5%. The average recoveries were 97.53–102.01%. The proposed HPLC-PAD method presented advantageous performance characteristics and it can be considered suitable for the evaluation of paromomycin loaded nanogel formulation in ex vivo permeation and in vitro release studies.

Surface Crack Detection for Carbon Fiber Reinforced Plastic Materials Using Pulsed Eddy Current Based on Rectangular Differential Probe

Aiming at the surface defect inspection of carbon fiber reinforced composite, the differential and the direct measurement finite element simulation models of pulsed eddy current flaw detection were built. The principle of differential pulsed eddy current detection was analyzed and the sensitivity of defect detection was compared through two kinds of measurements. The validity of simulation results was demonstrated by experiments. The simulation and experimental results show that the pulsed eddy current detection method based on rectangular differential probe can effectively improve the sensitivity of surface defect detection of carbon fiber reinforced composite material.

Development and validation of an indirect pulsed electrochemical detection method for monitoring the inhibition of Abl1 tyrosine kinase

A new method for monitoring the enzyme inhibition of Abl1 tyrosine kinase by liquid chromatography–indirect pulsed electrochemical detection (LC–InPED) was developed. In this method, adsorption of a peptide analyte at the noble metal electrode suppresses the oxidation of polyols under alkaline condition to elicit an indirect response resulting in a negative peak of the target peptide. Among the reagents tested, d-gluconic acid sodium salt gave the best overall signal to noise (S/N) values for the indirect detection of p-Abltide, the product of Abl1 enzymatic reaction. 50μM d-gluconic acid sodium salt dissolved in a mixture of 78% water–22% acetonitrile–0.03% trifluoroacetic acid (TFA) was used as the mobile phase. Chromatographic separation was achieved on an Alltima C18 (I.D. 5μm; 250mm×4.6mm) column with the mobile phase flow rate of 0.5ml/min. 0.5M sodium hydroxide was added post-column to maintain alkaline conditions in the PED cell. The limit of quantification (LOQ) was 0.2μM for p-Abltide, which was about 50-fold lower than direct PED analysis. The residual plot of the linear calibration curve indicated a good fit with a linear model within the investigated concentration range of p-Abltide. Intra- and inter-day precision was not more than 6.5% and accuracy was from −5.75% to +1.54%. The validated LC–InPED method was successfully applied for monitoring of p-Abltide in Abl1 enzyme reaction and the inhibition study of Abl1. The determined IC50 values of model inhibitors, imatinib, nilotinib and dasatinib, were 601.4nM (R2=0.99), 32.3nM (R2=0.99) and 1.3nM (R2=0.98), respectively. These results were consistent with literature data. To the best of our knowledge this is the first time a LC–InPED method has been used to monitor an enzyme reaction.

Camera calibration by using fringe patterns and 2D phase-difference pulse detection

Camera calibration is the most essential and usually the first step in computer vision applications. The results highly depend on the accuracy of the feature extraction. Conventional feature extraction methods suffer from perspective and lens distortion. In this paper, a novel feature extraction method is proposed by using fringe patterns groups as calibration target. Each group comprises six sinusoidal, in which, three are used for calculating vertical phases and the other three for horizontal phases. A three-step phase shift algorithm is used for wrapped phase calculation. Then, feature points are detected with a 2D phase-difference pulse detection method and refinement is done by simple interpolation. Finally, camera calibration is done by using these features as control points, experimental results indicated the proposed method accurate and robust.

Determination of γ-aminobutyric acid in leaf, stem and root bark of mulberry by high-performance anion exchange chromatography-integrated pulsed amperometric detection

Summary A simple high-performance anion-exchange chromatography-integrated pulsed amperometric detection method was developed to determine the gammaaminobutyric acid (GABA) content in mulberry. GABA was separated in anion-exchange column under isocratic condition of 20 mM sodium hydroxide solution and detected at integrated pulsed amperometric detection at pico-gram levels. The contents of GABA in the leaf, stem, and root bark of mulberry were calculated without any derivatization or sample purification process using this method. This method showed good linearity, precision, and accuracy for GABA analysis.

R Wave Detection for Real-time Processing using Nonlinear Transform and Dynamic Thresholding

Heart rate variability (HRV) is considered important for understanding the activity of autonomic nervous system. In that sense, it is very important to detect R waves in ECG and measure the intervals between consecutive R waves. A method for detecting R wave by thresholding is generally useful but the static thresholding method often fails to detect the R waves when an ECG has very noisy waveform like fetal ECG. In this study, we have proposed a method for pulse detection using nonlinear transform and dynamic thresholding and evaluated our proposed method by computer simulation. In the results, the method with Teager-Kaiser energy operator detects all pulses from a noisy simulation signal from which the method with square operator fails to detect some pulses.

ANALYSIS AND APPLICATION OF LIDAR WAVEFORM DATA USING A PROGRESSIVE WAVEFORM DECOMPOSITION METHOD

Abstract. Due to rich information of a full waveform of airborne LiDAR (light detection and ranging) data, the analysis of full waveform has been an active area in LiDAR application. It is possible to digitally sample and store the entire reflected waveform of small-footprint instead of only discrete point clouds. Decomposition of waveform data, a key step in waveform data analysis, can be categorized to two typical methods: 1) the Gaussian modelling method such as the Non-linear least-squares (NLS) algorithm and the maximum likelihood estimation using the Exception Maximization (EM) algorithm. 2) pulse detection method—Average Square Difference Function (ASDF). However, the Gaussian modelling methods strongly rely on initial parameters, whereas the ASDF omits the importance of parameter information of the waveform. In this paper, we proposed a fast algorithm—Progressive Waveform Decomposition (PWD) method to extract local maxims and fit the echo with Gaussian function, and calculate other parameters from the raw waveform data. On the one hand, experiments are implemented to evaluate the PWD method and the results demonstrate its robustness and efficiency. On the other hand, with the PWD parametric analysis of the full-waveform instead of a 3D point cloud, some special applications are investigated afterward.

Analysis of saikosaponins in Bupleuri Radix and Caihu‐shugan‐san using reversed‐phase HPLC with pulsed amperometric detection

A simple and sensitive reversed-phase (RP) HPLC coupled with pulsed amperometric detection (PAD) method was developed to determine the saikosaponin content in Bupleuri Radix or Caihu-shugan-san. Four saikosaponins in Bupleuri Radix and Caihu-shugan-san were extracted with a 6:4 solution of 10 mM sodium phosphate buffer (pH 8)/100% ethanol. Pulsed amperometric detection of carbohydrates in four major saikosaponins was highly sensitive when used with a water-acetonitrile gradient on an alkaline RP column with a post-column delivery system. The limits of detection (S/N=3) and of quantification (S/N=10) of saikosaponins were 0.01-0.02 and 0.03-0.05 μg/mL, respectively. The intra- and inter-day precision (RSDs) were each <9.7% and the average recoveries were 95.0-97.6% in Bupleuri Radix. This method can be used to analyze saikosaponins in Bupleuri Radix and Caihu-shugan-san.