Synchronous Detection Research Articles

A Multi-component Signal Decomposition Application Research on Improved Algorithm Based on Improved Wavelet Ridge

Multi-component signal decomposition method with noise has become a research hotspot of equipment condition monitoring. Aiming at the iterative divergence problem of traditional wavelet ridge extraction algorithm for multi-component harmonic signals widely existing in mechanical and electrical systems, in order to achieve the goal of high decomposition accuracy and anti-noise performance of multi-component signals, the relationship between the initial scale and the extracted components is analyzed. Compared with the time domain of noisy harmonic signals, an improved wavelet ridge extraction algorithm is proposed （WRSD） After the instantaneous frequency of a component is obtained by this extraction algorithm, the component can be separated from the original signal and its instantaneous amplitude can be obtained by using the synchronous demodulation method. This method has high accuracy and certain anti-noise performance for instantaneous frequency estimation. Through simulation analysis and engineering application, the key zero point in intelligent manufacturing equipment of high-performance composite parts can be realized Fault detection of components.

A joint design method of frame synchronization code and LDPC code

Frame synchronization word (FSW) is an important basis in signal synchronization detection. In our work, the joint design of frame synchronization words and error correcting code are proposed which through regularly distributing the frame synchronization words among the information bits to improve the decoding performance of the LDPC. Frame synchronization word should be added to the information sequence corresponding to the position with the check matrix larger column weight which can guarantee that more Frame synchronization words are received by the check node in the decoding iteration. The frame synchronization word is known to the receiver which play an important role in decoding iteration. The results of simulation show that the algorithm makes an obvious improvement in decoding performance when the signal-noise ratio (SNR) is lower than 1 dB.

Synchronous detection of heavy metal ions in aqueous solution by gold nanoparticle surface-enhanced laser-induced breakdown spectroscopy

Heavy metal ion-induced water pollution has become a severe environmental problem in the world.

The impact of PSS autocorrelation on cell search based on robust maximum likelihood scheme in LTE system

Robust Maximum Likelihood scheme for primary synchronization signal (PSS) detection and integer frequency offset (IFO) in Long Term Evolution (LTE) system has the best performance of cell search [5]. This scheme provides good synchronization performance based on correlation properties of Zadoff-Chu (ZC) sequences and reduced-rank representation of channel frequency response in multi-path propagation fading environment. The three ZC sequences used for PSS in LTE system cannot be said to have sufficient correlation properties in considering impact of symbol timing error. In this paper, we evaluate impact of the autocorrelation of PSS on PSS detection and IFO estimation and raise an issue of using other ZC sequence with better correlation properties. The simulation results show that PSS detection and IFO estimation performances are improved by using proposed ZC sequence.

Electrocardiogram Signal Denoising by Hilbert Transform and Synchronous Detection

An efficient method for Electrocardiogram (ECG) signal denoising based on synchronous detection and Hilbert transform techniques is presented. The goal of the method is to decompose a noisy ECG signal into two components classified according to their energy: (1) component with high energy representing the dominant component which is the clean ECG signal, and (2) component with low energy representing the sub-dominant component which is the contaminant noise. The investigated approach is validated through out some experimentations on MIT-BIH ECG database. Experimental results show that random noises can be effectively suppressed from ECG signals.

Peculiarities of prismatic input of narrow-band radiation into Ag-ion diffusion waveguide

The peculiarities of prism coupling elements input and output of narrow-band radiation into ion diffusion waveguide are researched. Gradient waveguide with a thickness of 1.67 μm was formed by ion exchange in K8 glass. The output signal intensity dependence on the input and output angles of incidence radiation was measured by developed automatic hardware-software system based on synchronous detection method to improve the signal-to-noise ratio. It was shown the maximum of output signal is reached at equal input and output angles.

Software-Defined Cyber–Energy Secure Underwater Wireless Power Transfer

Underwater wireless power transfer (UWPT) is a critical infrastructure for supplying power to underwater devices, such as underwater sensors and autonomous underwater vehicles. Enabling a software-defined architecture for UWPT promises to build a flexible and programmable underwater energy network. Although it is crucial that UWPT be made more resilient to cyberattacks and energy stealing, this remains an open challenge. In this article, we propose a software-defined UWPT (SD-UWPT) system that is both cyber and energy secure. A moving target defense approach and an active synchronous detection method are developed to protect the SD-UWPT against scanning-based attacks and power bot attacks. To enable energy-secure UWPT, an impedance measurement based approach is further established to prevent energy stealing. Through comprehensive evaluations, we validate the benefits of SD-UWPT and demonstrate the effectiveness of the proposed cyber–energy secure strategies against various attacks.

Evaluation of droplet digital PCR for quantification of SARS-CoV-2 Virus in discharged COVID-19 patients.

The worldwide severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak has led to the rapid spread of coronavirus disease (COVID-19). The quantitative real time PCR (qPCR) is widely used as the gold standard for clinical detection of SARS-CoV-2. However, more and more infected patients are relapsing after discharge, which suggests qPCR may fail to detect the virus in some cases. In this study, we selected 74 clinical samples from 43 recovering inpatients for qPCR and Droplet Digital PCR (ddPCR) synchronous blind detection, and established a cutoff value for ddPCR diagnosis of COVID-19. The results showed that at a cutoff value of 0.04 copies/μL, the ddPCR sensitivity and specificity are 97.6% and 100%, respectively. In addition, we also analyzed 18 retained samples from 9 discharged patients who relapsed. Although qPCR showed all 18 samples to be negative, ddPCR showed 12 to be positive, and there was only one patient with two negative samples; the other eight patients had at least one positive sample. These results indicate that ddPCR could significantly improve the accuracy of COVID-19 diagnosis, especially for discharged patients with a low viral load, and help to reduce misdiagnosis during recovery.

Single Sideband Hartley Amplitude Modulation

It is developed a method of information transmission with application of amplitude Single Sideband Hartley modulation (SSBH) allowing to increase of radio channel length for optical and fiber optic signal transmission systems where single sideband amplitude modulation (SSB) is used. Increase of communication range is provided due to application a sum of two orthogonal oscillations of the same frequency as a carrier (Hartley wave). It provides energy gain in 6 dB and 1.41 times increase of the amplitude of output signal of synchronous detector comparing to SSB in case of the same radiation power of transmitter and the same sensitivities of SSBH and SSB signals receivers. Application of SSBH and SSB modulation allows to provide the energy gain in transmitting channel approximately 15–20 times comparing to amplitude modulation (AM) application. It also provides increased security of SSBH transmission since in case of absence of modulation signal the transmitter does not radiate, that allows to provide energy saving in case of transmitter power supply with battery. Depending on the need we can use both upper and lower side bands.

Target-triggered entropy-driven amplification system-templated silver nanoclusters for multiplexed microRNA analysis

MicroRNAs (miRNAs) are important biomarkers for the diagnosis, prognosis, and treatment of human diseases. Sensitive and selective detection of multiple miRNAs simultaneously will greatly facilitate the early and accurate diagnosis of cancers. Herein, a novel entropy-driven amplification system-templated silver nanoclusters sensing platform was developed for the multiplexed analysis of tumor-associated miRNAs. The sensing platform was constructed by coupling target-triggered entropy-driven catalysis with luminescence adjustable DNA-templated silver nanoclusters (Ag NCs). In the presence of target miRNA, the sensing platform initiates the branch migration and strand displacement of the complex, which has a six-base cytosine loop for stabilizing the luminous Ag NCs. The target is cyclically generated for new catalysis while turning off the fluorescence of Ag NCs; this is accompanied by a significantly amplified optical readout. In this study, two different complex-stabilized Ag NCs systems were proposed, the yellow-emitting Ag NCs and red-emitting Ag NCs biosensors enabled the analysis of miRNA-141 and miRNA-155 with detection limits of 6.1 pM and 8.7 pM, respectively. Impressively, owing to the excellent selectivity, flexibility, and narrow-band excitation of the platform, the multiplexed synchronous detection of miRNA-141 and miRNA-155 were achieved in buffer, biological cell lysates and human serum samples with satisfactory results. The simple, flexible, and convenient strategy provides a powerful tool for multiple biomarkers analysis and related clinical applications.

Colorectal EMR outcomes in octogenarians versus younger patients referred for removal of large (≥20 mm) nonpedunculated polyps

Data are limited on safety and outcomes of colorectal EMR in octogenarians (≥80 years old). We sought to review outcome data for patients aged≥80 in a prospectively collected database of patients referred for large polyp removal. We retrospectively evaluated a database of patients referred for large (≥20mm) nonpedunculated polyp removal. From 2000 to 2019, we compared the rates of follow-up, recurrence, adverse events, and synchronous neoplasia detection between younger patients and patients aged≥80. There were 167 patients aged≥80 years and 1686<80 years. Patients in the elderly group returned for surveillance less often (67.1% vs 75.1%, P= .024), had greater first follow-up recurrence rates (27.5% vs 13.8%, P< .001), but had similar adverse event rates (1.8% vs 2.8%, P= .619) compared with younger patients. Rates of synchronous neoplasia were similar and high in both groups. EMR is safe and well tolerated for large polyp removal in patients over 80 years old. Patients aged≥80 years are less likely to present for follow-up after EMR. They had a higher recurrence rate and a similarly high prevalence of synchronous precancerous lesions. Follow-up after EMR should be encouraged in the elderly, and an attempt to clear the colon of synchronous disease at the time of the initial EMR may be warranted.

Photobleaching reduction in modulated super-resolution microscopy.

Important breakthroughs in far-field imaging techniques have been made since the first demonstrations of stimulated emission depletion (STED) microscopy. To date, the most straightforward and widespread deployment of STED microscopy has used continuous wave (CW) laser beams for both the excitation and depletion of fluorescence emission. A major drawback of the CW STED imaging technique has been photobleaching effects due to the high optical power needed in the depletion beam to reach sub-diffraction resolution. To overcome this hurdle, we have applied a synchronous detection approach based on modulating the excitation laser beam, while keeping the depletion beam at CW operation, and frequency filtering the collected signal with a lock-in amplifier to record solely the super-resolved fluorescence emission. We demonstrate here that such approach allows an important reduction in the optical power of both laser beams that leads to measurable decreases in photobleaching effects in STED microscopy. We report super-resolution images with relatively low powers for both the excitation and depletion beams. In addition, typical unwanted scattering effects and background signal generated from the depletion beam, which invariably arises from mismatches in refractive index in the material composing the sample, are largely reduced by using the modulated STED approach. The capability of acquiring super-resolution images with relatively low power is quite relevant for studying a variety of samples, but particularly important for biological species as exemplified in this work.

Desarrollo de Técnicas de Muongrafía para Estudios Densitométricos de Objetos de Importancia Estratégica

La muongrafía es una técnica de prospección no destructiva que permite la determinación de la estructura interna de grandes estructuras tanto naturales como artificiales, por ejemplo volcanes. Esto es posible al construir una imagen con base en la absorción diferencial del flujo direccional de muones atmosféricos producto de la interacción de rayos cósmicos con la atmósfera. Este trabajo doctoral es desarrollado con el propósito principal de aportar en el avance de la muongrafía como técnica de prospección en Geofísica. El trabajo se compone de dos lineas de trabajo, una experimental y una teórica. La experimental se basa en el desarrollo de un prototipo de detector de astropartículas con base en centelladores plásticos y fotomultiplicadores, para esto se usa una electrónica de adquisición desarrollada para el proyecto AMIGA en el Observatorio Pierre Auger y materiales centelladores de plástico. La segunda linea de trabajo trata del estudio del detector y las estructuras de investigación a través de simulaciones computacionales y modelos teóricos. Durante los dos primeros años se completaron los créditos de cursos solicitados por el doctorado, Ademas se trabajó en el estudio de la respuesta de la electrónica, los pulsos, técnicas de análisis de datos y el acople de fotomultiplicadores con los centelladores. Gracias a esto se avanzo en el desarrollo del prototipo y se investigo la posibilidad de incrementar la resolución espacial a través de la detección sincrónica usando electrónicas conectadas al mismo centellador. Actualmente iniciamos el trabajo en los modelos computacionales, estamos estudiando e investigando con respecto a los candidatos a objetos de estudio, destacando el volcán Copahue, volcán Peteroa y la posibilidad de realizar mediciones bajo tierra.

A Combined Filter for Synchronous Detection in Underwater Acoustic Mobile Communication System

A scale-stretching combined filter is proposed for underwater acoustic mobile communication receivers. The combined filter consists of the sum of signals with different time stretching and shifting. Based on the matched filtering theory, Doppler stretching scales, time shift, and the order of each component of the combined filter are derived. The method proposed in this paper improves the matching degree of the filter with wideband Doppler echo signals with different moving speeds. Simulation results show that the combined filter proposed in this paper can improve the detection probability and synchronization time estimation accuracy of wideband Doppler echo. In addition, the combined filter proposed in this paper has the same calculation amount as the matched filter. This feature makes this filter suitable for the synchronous detection of underwater acoustic mobile communication with real-time operation and low power consumption requirements.

Synchronous single-photon detection with self-resetting, GHz-gated superconducting NbN nanowires

We demonstrate a GHz-gated operation of resonator-coupled superconducting nanowire single-photon detectors suitable for synchronous applications. In comparison with conventional dc-biased nanowire detectors, this method prevents the detector from latching and can suppress dark counts and background noise. Using a gating frequency of 3.8 GHz and a fast, synchronized laser diode, we show that the detector's operation point follows the oscillating current and its detection efficiency depends on the relative frequency and phase of the bias and modulated optical signal. The obtained experimental results are in good agreement with simulations, showing that the duty cycle of a gated detector can be adjusted in a wide range in the case of a pronounced saturation of the current-dependent detection efficiency. This operation mode could be suitable for applications such as quantum key distribution and time-of-flight laser ranging.

Synchronism and Direction Detection in High-Resolution/High-Density Electromagnetic Encoders

Recently, electromagnetic encoders with synchronous reading and direction detection capability have been reported. Such structures are useful for the implementation of (i) displacement/velocity sensors and (ii) chipless-RFID systems based on near-field coupling and sequential bit reading. In the latter, synchronous reading and motion direction detection are a need in order to avoid false readings of the identification (ID) code, if the relative velocity between the reader and the encoder is not constant, and to read the correct ID code (rather than the inverse one), respectively. On the other hand, synchronous reading and motion direction detection, are essential to determine the encoder direction in displacement/velocity sensors, as well as to provide the absolute position of the encoder, provided that the whole encoder is encoded with the Bruijn sequence. In this paper, synchronous reading and direction detection in high-resolution/high-density electromagnetic encoders based on chains of linearly-shaped metallic inclusions are reported. To this end, it is necessary to add two chains of metallic inclusions to the one containing the ID code. In the reader side, three harmonic signals are necessary in order to generate the clock signals and to obtain the ID code. The reader consists of a microstrip line loaded with three pairs of open-ended folded stubs positioned face-to-face by their extremes. By displacing the encoder chains over the extreme of the stubs, at short distance, stub coupling is enhanced when a metallic inclusion lies on top of the stubs, and the frequency response of the reader is shifted towards lower frequencies. Thus, by injecting three (properly tuned) harmonic signals at the input port of the microstrip transmission line, three amplitude modulated (AM) signals are generated by tag motion at the output port of such transmission line, and the envelope functions contain the velocity, the ID code and the absolute position. The reported reader/encoder system exhibits superior space resolution and information density as compared to other similar systems based on synchronous reading.

Triplex qRT-PCR with specific probe for synchronously detecting Bovine parvovirus, bovine coronavirus, bovine parainfluenza virus and its applications.

Bovine parvovirus (BPV), bovine coronavirus (BCoV) and bovine parainfluenza virus (BPIV) are common etiologies causing gastrointestinal and respiratory diseases in dairy herds. However, there are few reports on the synchronous detection of BPV, BCoV and BPIV. The present article aimed to develop a quick and accurate RT-PCR assay to synchronously detect BPV, BCoV and BPIV based on their specific probes. One pair universal primers, one pair specific primers and one specific probe was designed and synthesized. After the concentrations of primer and probe and annealing temperature were strictly optimized, the specificity, sensitivity and repeatability of the established triplex probe qRT-PCR were evaluated, respectively. The results showed the recombinant plasmids of pMD18-T-BPV, pMD18-T-BCoV and pMD18-T-BPIV were 554bp, 699bp and 704bp, respectively. The optimal annealing temperature was set at 45.0°C for triplex qRT-PCR. The triplex probe qRT-PCR can only synchronously detect BPV, BCoV and BPIV. Detection sensitivities were 2.0×102, 2.0×102 and 2.0×101 copies/μL for BPV, BCoV and BPIV, being 1000-fold greater than that in the conventional PCR. Detection of clinical samples demonstrated that triplex probe qRT-PCR had a higher sensitivity and specificity. The intra-assay and inter-assay coefficient of variation were lower than 2.0%. Clinical specimens verified that the triplex qRT-PCR had a higher sensitivity and specificity than universal PCR. In conclusion, this triplex probe qRT-PCR could detect only BPV, BCoV and BPIV. Minimum detection limits were 2.0×102 copies/μL for BPV and BCoV, and 2.0×101 copies/μL for BPIV. The sensitivity of this triplex probe qRT-PCR was 1000-fold greater than that in the conventional PCR. The newly qRT-PCR could be used to monitor or differentially diagnose virus infection.

Complexity-Effective Sequential Detection of Synchronization Signal for Cellular Narrowband IoT Communication Systems

Narrowband Internet of Things (NB-IoT) is one of the most promising low-power wide-area technologies to support low cost, massive connection, deep coverage, and low-power consumption. This article proposes a complexity-effective narrowband secondary synchronization signal (NSSS) detection scheme for the cellular NB-IoT communication system. By taking advantage of the NSSS sequence, the search space of NSSS hypotheses is reduced by decoupling the detection of complementary Walsh sequence and Zadoff-Chu sequence in a sequential manner. Such a detection strategy allows reduced-complexity NSSS detection in the NB-IoT system. Both numerical and simulation results are presented to verify the effectiveness of the proposed NSSS detection scheme. The simulation results show that the proposed NSSS detector achieves a considerable complexity reduction at the cost of some performance degradation, compared to the conventional NSSS detector.

Double Samples Synchronous Detection Sensor based on Up-Core Photonic Crystal Fiber

Photonic crystal fiber (PCF) sensors based on surface plasmon resonance (SPR) have the characteristics of high sensitivity, flexible structure, high nonlinear effect and high-quality transmission. However, in the application of PCF sensors, there are generally problems such as low detection efficiency, difficulty in coating air holes and complicated operations of microfluidic filling. These limitations fundamentally limit the development and application of this technology. In this paper, a double samples synchronous detection sensor based on up-core PCF is proposed and the area of the center large air hole can be increased effectively by moving the core upward, which can reduce its coating difficulty. Furthermore, the outer surface coating of the PCF filled with the liquid to be measured has the advantages of simple operation and easy implementation compared with the inner coating of the air hole. The sensor can simultaneously detect two kinds of microfluidics, thus improving the detection efficiency. This structure does not have the characteristics of rotational symmetry, which greatly reduces the fiber confinement loss and has high sensitivity. The simulation results show that the maximum sensitivity of the designed sensor is up to 8300 nm/RIU, and the minimum resolution of the spectrometer is assumed to be 0.01 nm, at this time, the resolution of the sensor can reach 1.20 × 10-6 RIU. The proposed structure has important scientific significance and application prospects for promoting the practical development of sensing technology and improving the efficiency of microfluidic detection.

A continuously scanning separate-crystal single-photon x-ray interferometer

The feasibility of a new design and measurement concept of a combined optical and x-ray interferometer (COXI) is demonstrated here. Mechanical noise in the x-ray interferometer can be cancelled efficiently with fast and synchronous detection of the optical interferometer phase and x-ray counts. The scan-length requirement of the decadic step method of conventional COXI setups is reduced by more than one order of magnitude due to the correlation between single-photon interference events. The actual scan length of the shown setup is limited to 4 µm. It is estimated that a future update will enable us to measure the lattice parameter of 28Si, at least with the targeted relative statistical reproducibility of 3 × 10−9.