DC Drift Research Articles

An inserting pilot frequency-doubling millimeter wave radio over fiber system without bit walk-off effect by polarization modulator

Abstract An inserting pilot frequency-doubling millimeter-wave (MMW) radio over fiber (ROF) system is proposed to overcome fiber dispersion by polarization modulator (PoIM). At the central station, the optical carrier is first split into two beams, one beam is used as the pilot, and the other is modulated by a PolM with a composite radio frequency drive signal which is formed by combining the phase modulated data signal and the amplified data signal. By adjusting key parameters of the system, the output main components of the PolM are ±1st order sidebands, the downlink data signal is modulated only on the +1st order sideband. At the base station (BS), the pilot is reflected out by a fiber Bragg grating (FBG) and used as the optical carrier of uplink for carrier reuse. By feeding the output signal of the FBG into the photodetector, the frequency-doubling MMW signal with downlink is produced. In the case of BER is 10−9, and the length of fiber is 40 km and 80 km, the power penalty is 0.51 dB and 2.54 dB for the downlink, 0.49 dB and 4.72 dB for the uplink, respectively. Compared to the downlink of a conventional ROF system, in the 40 km and 80 km fiber transmission distance, our scheme raises the sensitivity of the receiver to 3.42 dB and 2.85 dB, respectively. Our designed ROF system can overcome the bit walk-off effect and have no problems with extinction ratio limitation and the DC drift. Carrier reuse realized by inserting a pilot can overcome the problems of downlink performance degradation and tunability restriction caused by conventional carrier reuse methods

Precision Biometrics Based on PPG Measured From an IoT Device With OPDs, Real-Time Quality Check Through PSD, DC Drift, and Deep Learning

Precision Biometrics Based on PPG Measured From an IoT Device With OPDs, Real-Time Quality Check Through PSD, DC Drift, and Deep Learning

Optical switch with an ultralow DC drift based on thin-film lithium tantalate.

We present an electro-optic (EO) switch with ultralow DC drift on a thin-film lithium tantalate (TFLT) platform, even with SiO2 cladding and without post-annealing processes. The flat Vπ and EO responses have been measured across various driving frequencies, input optical powers, and temperatures. Stable optical switching is achievable in the low-frequency range. The experiment also demonstrated superior long-term stability (up to 2 h) compared to thin-film lithium niobate optical switches under similar on-chip optical power conditions (around -8 dBm).

Railroad bridge monitoring using Dragonfly® piezoelectric strain gauge

Structural Health Monitoring (SHM) applied to civil structures such as bridges, high-rise towers, and electricity pylons can help plan their maintenance, detect damages or un-expected events, and extend their remaining operating lifetime. Metallic foil strain gauge and vibrating wire are the historic sensors used to measure strain on civil structures. However, civil structures are designed to undergo little deformation in service (0.1-50 µdef). Both SG and vibrating wire are limited by their resolution around 1 µdef. Moreover, they are known for their DC drift over time, which complexifies long term monitoring. There is therefore a need for more sensitive and less prone to drift sensors in the time domain. Dragonfly new piezoelectric strain gauges, with a resolution three order of magnitude over classic sensors, solve these issues and enable new applications. Dragonfly sensors consist in an extremely thin piezoelectric ceramic packaged in a flexible PCB and pre-wired with a SMA connector. The flexible sensor is glued with cyanoacrylate glue to the object to be studied. This paper presents the implementation of Dragonfly sensors on a railroad bridge. With a single sensor, it has been possible to identify the bridge girder first two resonance using ambient noise, train passage loading for fatigue-life analysis, train passage reproducibility, and pedestrian passage on the walkway. A complete comparison with classic metallic foil strain gauge is detailed.

High-Frequency Hall Effect and Transverse Electric Galvanomagnetic Waves in Current-Biased 2D Electron Systems

We derive the electrodynamic conductivity tensor for 2DESs with dc drift with account for the high-frequency Hall effect (interaction of dc current with ac magnetic field). We demonstrate the limitations of the quasistatic approach which neglects this effect. With the help of electrodynamic conductivity we find a novel two-dimensional transverse electric (TE) electromagnetic mode. This mode is non-reciprocal with dispersion \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega = {\\mathbf{k}}{{{\\mathbf{u}}}_{0}}$$\\end{document} and manifests itself in lowering the reflection coefficient of 2DES at the resonance frequency. In addition, we predict birefringence of an incident evanescent TE wave on a 2DES system with drift and find hints of Cerenkov amplification in the low frequency limit. We discuss the limiting cases when the quasistatic approach is suitable.

Study on Temporary Unloading for Chatter Vibration Suppression Using Fixed Superabrasive Polishing Stone with Five-Joint Closed-Link Small Robot and Voice Coil Motor Thrust Control

In this study, an existing superfinishing method used for polishing glass surfaces was refined using a five-joint closed-link compact robot with fixed abrasive grains. In previous studies, a voice coil motor was used to control the constant-pressure pressing force while maintaining the polishing force for a relatively short period. However, maintaining the polishing force for long periods is imperative for achieving a high-quality polished surface. Thus, in this study, a strain gauge load cell was adopted in addition to a conventional piezoelectric force sensor to maintain the polishing force for a long period. First, the amounts of DC drift of the piezoelectric force sensor and strain gauge type load cell were compared to confirm the necessity of signal processing as well as the compatibility of long-term force measurement and high-frequency vibration measurement by application. Further, a method was proposed in which the change in the pressing force was recorded from the connected sensor; when the pressing force fluctuated, chatter vibrations were determined to occur, and the pressing force was temporarily set to 0 N. This method could obtain a better polished surface than the proportional-integral-differential (PID) control, which simply controls the pressing force at a constant value. Finally, chatter vibrations could be determined by detecting high-frequency sounds using a sound level meter. Notably, a finely polished surface could be obtained.

Improved Federal Test Procedure (FTP75) driving cycle performance for PMSM‐fed hybrid electric vehicles using artificial neural network

SummaryThe sensorless speed control of permanent magnet synchronous motor (PMSM) is gaining popularity in hybrid electric vehicle (HEV) applications leading to its enhanced safety, reliability, and cost savings. Speed control using vector control for PMSM‐fed HEV requires the speed encoder. When the speed sensor information fails, the inverter must ensure power delivery to the PMSM continuously by estimating the speed; this mode of operation is referred as limp‐home mode in HEV. In this paper, a speed sensorless scheme has been proposed for PMSM‐based HEV during limp‐home mode operation. This paper presents a model reference adaptive system (MRAS) speed estimator based on an adaptive neural network controller (NNC) for speed estimation of PMSM. In the HEV application, in case of speed/position encoder failure, the speed of the PMSM can be estimated by stator flux using stator current.The proposed method employs stator currents in the reference model to eliminate the DC drift problem. Furthermore, the NNC is employed in the adaptation mechanism to improve the Federal Test Procedure (FTP75) driving cycle performance. The performance of the proposed control scheme has been validated with dSPACE 1104 R & D rapid development controller using vector control for the PMSM during variable speed and torque, including the zero‐speed applications

Simple and low-cost motion-sensorless control approach for the IPMSM with elimination of DC offset and steady-state error

Voltage type flux observer has attracted much attention because of its less mathematical calculations and ease of implementation. The only issue with the flux estimation approach is the integration mechanism; using a pure integrator may cause integrator saturation and a DC bias issue, whereas using the low pass filter (LPF) and a self-adaptive band-pass filter (SABPF) would result in magnitude and phase angle errors. This work offers an improved flux linkage estimation approach with a proportional integral (PI) DC offset compensator, resolving the DC drift issue associated with the observer’s pure integrator. Compared to the standard voltage type flux observer, the DC offset is removed, the LPF and phase adjustment are eliminated, and low-speed armature position estimate accuracy is improved. The proposed method can reduce calculation. As a result, the control period is reduced. The Matlab Simulink framework findings are presented to validate the performance and effectiveness of the proposed strategy.

Removal of artifact in bio signal using ECG for QRS detection

This paper proposed a removal of artifacts in bio signal, which is used to improve the signal strength by using Pan Tompkins algorithm for QRS signal detection. This algorithm is compared with different filtering technique such as noise cancellation filter, squaring filter, moving average and differentiator filter. Recorded bio signal and SNR ratio measurement will be shown in simulation result using MATLAB 2018a software tool, this filtering technique data contains noisy input signal with 3 second time delay. The sampling rate of the ECG signal is 200Hz on power line noise from machine power supply, ECG signal wandering after cancellation DC drift and normalization process. Efficacy of the filters for removing the artifact and generate the effect on the ECG waveform, in terms of accuracy rate, the SNR ratio of ECG in pipeline architecture has 93% of efficiency is achieved.

Signal Preprocessing for Heartbeat Detection Using Continuous-Wave Doppler Radar

A signal preprocessing method is proposed for effectively monitoring heartbeats from signals obtained using a continuous-wave (CW) Doppler radar. The proposed method consists of windowing with a size optimized for heartbeat detection, detrending to minimize the effect of dc drift, and data reconstruction to increase the fast Fourier transform (FFT) resolution. A window size of 3 s effectively extracts the heartbeat alone from the received signals of the CW radar, which comprised respiration, motion, and heartbeat signals. The effect of the low-frequency noise caused by the internal heat generation of hardware components is reduced by the detrending technique, and the low resolution of the FFT, due to a small number of samples, is improved through reconstruction by combining data from three windows. The signal-to-noise ratio of the measured waveform was improved to 5.83 dB using the proposed method in a 5.8-GHz CW radar. For the data acquired for 60 s, the proposed method showed a heartbeat detection accuracy of 95.8% by using a signal processing time 13% lower than that of the conventional method.

Effect of La3+ ion doped Co-Zn nano ferrites: Structural, optical, electrical and magnetic properties

Lanthanum substituted Co Zn Fe 2 O 4 fabricated nano ferrite powder was conformed single phase cubic spinal structure from the XRD and particle size conformed by the TEM. Optical and electric properties was studied. VSM was used to investigate magnetic characteristics from room temperature. • Effect of La 3+ ion doped Co-Zn nanoferrites were synthesised through the citrate gel auto-combustion method. • Rietveld refinement was used to analyse XRD data and confirmed the nano-range particles with spinel ferrites. • FE-SEM, EDAX, FTIR, TEM, AFM, FTIR, DC electrical resistivity, dielectric studies, and VSM studies are conducted. Lanthanum ion doped with large percentages of zinc cobalt ferrite (Co 0.1 Zn 0.9 La x Fe 2-x O 4 ) nanoparticles with an ‘x’ range of from 0.000 to 0.030 (with the step of x=0.005) were manufactured through the citrate gel auto-combustion method. The fabricated synthesised powder was analysed to find out the structural characterization from the XRD, FE-SEM, EDAX, TEM, FTIR, and AFM. The average crystallite size was confirmed and nanometer ranges were exposed from the XRD and TEM images, which ranged between 10 nm and 15 nm and the FCC spinel structure. The lattice parameter is found to increase from 8.392 A o to 8.452 A o with the substitution of La 3+ ion, and a monotone diffraction peak (311) shows towards minor angles of degrees (35.33° to 35.13°). The surface area increases from 122.8 to 186.3 m 2 g -1 with the addition of La 3+ ion. From FTIR the bond lenth (ν 1 ) ranges from 512 cm −1 to 530 cm −1 , increasing with doped La 3+ ion content. In the AFM analysis, the surface roughness decreases from 10 nm to 6.5 nm. The prepared samples the results of magnetic, temperature variation of dielectric, and DC resistivity studies were discussed. The dielectric constant reduces dramatically as the substituted lanthanum ion concentration rises with temperature, although it remains stable in the three previously described ranges. DC resistivity, curie temperature, and drift mobility have an inverse relationship with temperature increase. The magnetic properties of hysteresis loops indicate a shift from harder to softer magnetic moments. The Ms and Mr decrease as the lanthanum ion concentration in Co-Zn ferrite increases, from 15.19 emu/g to 9.30 emu/g, and from 3.81 emu/g to 2.33 emu/g and the magnetic moment decreases from 0.6539 to 0.4045. The prepared nano ferrite particles were suited as magnetic adsorbents in the departure of impurities from waste water.

Non-linear photonic loop mirror based co-site interference canceller

Full duplex-in band (FDIB) is a well-established solution for increasing the data rate and spreading the link range for future communication systems. FDIB systems need no additional bandwidth requirement. However, they are confronted with a major interference challenge on the same site, called co-site interference (CSI). Long-established co-site interference cancellation (CSIC) methods achieve a cancellation depth upto 35 dB, conversely it has space containments, manufacturing imperfections, induces noise penalties and limits isolation bandwidth. To overcome these problems, RF photonic CSIC methods have been developed, which have produced 30 dB wide-band interference suppression. They also increase bandwidth, have a flexible structure, minimize losses and prevent periodic power fading. But these systems have a problem of inherent DC drift, low maintenance of coherence, and low isolation at low transmission power. Thus, there is a high need for photonic CSIC designs of FDIB systems that operate over wider bandwidths and at higher transmission powers. Here, a newfangled CSIC system based on a non-linear photonic loop and frequency down-conversion is proposed. It shows excellent CSIC suppression of greater than 61 dB, for a single frequency signal of interest (SOI) with maximum RF power of 13 dBm. Without frequency down-conversion, the system maintains an average cancellation depth of 62.541 dB for single frequency SOI. After frequency down conversion, the system maintains an average cancellation depth of 61.208 dB for narrow band SOI. The system attains 18% error vector magnitude at −20 dB RF output power, which confirms the comprehensive quality of the system.

A Straightforward Quadrature Signal Generator for Single-Phase SOGI-PLL With Low Susceptibility to Grid Harmonics

Suppressing the negative effects of grid voltage harmonics on the estimated frequency of a phase-locked loop (PLL) is a challenge in literature. This article proposes an easy-to-implement quadrature signal generator (QSG) to attenuate the oscillations on the estimated frequency in single-phase grid-connected inverters, which use second-order generalized integrator (SOGI)-PLL. It is shown that SOGI exerts a stronger filtering effect in generating the quadrature signal than the in-phase signal. Against this background, in this work, a modified integrator is introduced into the path of the in-quadrature signal to generate another in-phase component with much lower harmonic content. The proposed method imposes only a small computational burden on the existing SOGI-PLL compared to the previously presented methods that address the input voltage harmonic problem. Moreover, this method can work properly within the allowable range of grid voltage frequency deviations. The proposed integrator benefits from an error-decaying mechanism to overcome dc drift in pure integrators. The integrator has been designed based on theoretical equations. The validity of the proposed QSG and theoretical equations is evaluated using simulations and experimental studies. A fixed-point representation of the proposed QSG is also provided for implementation on low-cost microcontrollers.

Methodology for the determination of human respiration rate by using Doppler radar and Empirical Modal Decomposition

In this work, a methodology is presented for the determination of the respiration rate of a person under test (PUT), the detection of movements, as well as the elimination of the spurious effects produced by the movements of the PUT. The methodology is based on Empirical Modal Decomposition (EMD) applied to the phase signal obtained by means of a quadrature Doppler radar operating in S band. The EMD allows to automatically eliminate the continuos component (CC) which is present in the phase signal since one of the main characteristics of the modes generated by the EMD is that its mean is equal to zero. On the other hand, the first mode of the EMD is used for the detection of movements while the sum of the second and third modes are used for the elimination of the CC drift caused by the DC drift and the high frequency components produced by the movements of the PUT. The proposed methodology was successfully tested in a PUT at rest and performing movements of the head, arm and combination of head, arm, and torso. The average respiration rate measured was 20.78 breaths / min with a standard deviation of 2.53 breaths/min.

Rotor Flux Estimator Design With Offset Extractor for Sensorless-Driven Induction Motors

In sensorless drive of induction motors (IMs), the design of a voltage model (VM) for flux estimation is challenging because of its inherent problems with dc saturation and drift. In the implementation of VM, various strategies have been studied in the flux estimator design. The closed-loop (CL) style flux estimator is a popular scheme owing to its good performance in a wide speed range. However, the CL style suffers from dc drift problems because of an offset at the back electromotive force. Based on the fact that dc drift always persists in the CL style flux estimator, this article proposes an offset extractor (OE) using a parallel structure of two CL style flux estimators. Moreover, a crossover strategy is applied to the comparative flux used in the CL scheme. This strategy guarantees low-speed operation including zero speed. When offset compensation using the proposed OE is applied to the flux estimator in a feedforward manner, the proposed flux estimator exhibits good performance in a wide speed range with robustness to the offset. Compared with the conventional methods, the proposed OE and flux estimator are verified in various situations by simulation and experiment in a sensorless-driven IM.

Resistive switching effect in RE-Doped cobalt ferrite nanoparticles

Spinel ferrite along with numerous important properties, also exhibit resistive switching effect. Cerium (Ce) doped Co-ferrite nanoparticles having composition CoFe2-xCexO4 (where x = 0.0, 0.05, 0.15, 0.20) were synthesized by co-precipitation synthesis route. X-ray Diffraction analysis confirmed the formation of cubic spinel phase with minor amount of impurities. Frequency dependent dielectric and electrical properties were studied at room temperature within frequency range of 20 Hz to 3 MHz. Dielectric constant, dielectric losses and AC conductivity decreases with cerium substitutions which is usual trend observed in ferrite materials. Modified Debye function was employed to fit Dielectric constant (ε′)- frequency (f) data. Jonscher's power law was employed to study AC conductivity. DC resistivity decreased with increasing temperature. DC resistivity and drift mobility decreased with cerium substitution while activation energy increased. Current–Voltage (I–V) curves of the synthesized composition were studied at room temperature. Current–Voltage (I–V) curves showed nonlinear hysteresis loop like behavior. Current follow different values for forward and reversed applied DC voltage which confirmed that resistive switching effect exit in studied samples. Sample with Ce composition x = 0.25 exhibit larger hysteresis loop than that of other compositions. This shows that sample for Ce composition x = 0.25, can be employed for nonvolatile Resistive Random-Access Memory (ReRAM) applications. Resistive switching effect was explained by utilizing Space-charge-limited current (SCLC) conduction model and by formation of a Schottky barrier at the metal-semiconductor interface.

A Dual-Channel PPG Readout System With Motion-Tolerant Adaptability for OLED-OPD Sensors.

An adaptive PPG (Photoplethysmography) readout system for a dual-channel OLED-OPD flexible sensor is designed and developed with motion artifact (<1Hz) and ambient lighting interference successfully compensated without any additional motion sensors. The compensation is made possible by adopting multi-feedbacks and an additional reference OPD channel to cancel effectively DC drifts. In result, the quality of measured PPG is improved to the level such that long-time, continuous quality monitoring of bio-sign such as heart rate (HR) is possible. The readout is designed with an auto-programmable band-pass trans-impedance amplifier (TIA) of a 100dbΩ gain with a continuous-type DC-current cancellation loop. The rest of the readout consists of a 0.5 Hz low-pass filter, an additional second-order band-pass filter (0.1-10Hz), a difference amplifier, a motion reference channel, an analog multiplexer, a programmable gain amplifier (PGA), a digital control and a programmable DAC-PWM based auto-intensity tuned OLED driver. The readout is fabricated in an area of 9 mm2 via the TSMC 180nm process. The experiment result shows that the developed OLED-OPD readout senses well as small as 1nA current, with a measured dynamic range >90dB (1nA to 100 µA) and input-referred noise of 0.26 nA/√H, with power consumption of 460µW. The DC drift is successfully reduced to 1% of its average. The accuracy for heart rate is 96%.

АНАЛИЗ ИСПОЛЬЗОВАНИЯ ФИЛЬТРА КАЛМАНА В ПРОЦЕДУРЕ ДЕТЕКТИРОВАНИЯ СИГНАЛА В СИСТЕМЕ С MIMO И ПРИЕМНИКОМ ПРЯМОГО ПРЕОБРАЗОВАНИЯ

Introduction: The procedure for detecting a quadrature amplitude modulation (QAM) signal in a communication system with multiple transmitting and receiving antennas (MIMO) is considered, which consists of two stages: obtaining soft solutions using the recurrent Kalman filtering algorithm, finding hard solutions by criterion of minimum distance between soft decision vectors and possible information symbols on each receiving antenna. The Kalman algorithm evaluates symbols at i-th time point in iterations. A comparison is made of noise immunity of QAM signal reception obtained using the Zero Forcing methods, the minimum mean square error (RMS), and recurrent Kalman procedure. Signal processing takes place under channel conditions with Rayleigh fading and Doppler spread spectrum. Cases are considered when the channel matrix is known exactly and when it is estimated by least squares method (LSM) using a first-order polynomial approximation for channel matrix elements. The channel matrix takes into account not only signal distortions due to the propagation medium, but also distortions obtained in the direct conversion receiver, such as amplitude and phase imbalance between signal quadratures, frequency shift due to non-ideal demodulation procedure, as well as DC drift. Result: The computational complexity of the detector based on Kalman algorithm is analyzede.

Adaptive neuro fuzzy inference system based decoupled control for neutral point clamped multi level inverter fed induction motor drive

The presence of an integrator in a reference model of a rotor flux-based model reference adaptive system (RF-MRAS) and non-linearity of the inverter in the output voltage degrade the speed response of the sensorless operation of the electric drive system in terms of DC drift, initial value issues, and inaccurate voltage acquisition. To improve the speed response, a compensating voltage component is supplemented by an amending integrator. The compensating voltage is a coalition of drift and offset voltages, and reduces DC drift and initial value issues. During low-speed operation, inaccurate voltage acquisition distorts the stator voltage critically, and it becomes considerable when the stator voltage of the machine is low. Implementing a three-level neutral point clamped inverter in speed-sensorless decoupled control of an induction motor improves the performance of the drive with superior quality of inverter output voltage. Further, the performance of the induction motor drive is improved by replacing the proportional-integral (PI) controller in the adaption mechanism of RF-MRAS with an adaptive neuro-fuzzy inference system (ANFIS) controller. A prototype model of the three-level neutral point clamped inverter (3L-NPC)-fed induction motor drive is fabricated in a laboratory, and its performance for a RF-MRAS, modified RFMRAS, and modified RFMRAS using ANFIS are compared using different benchmark tests.

Transient and steady‐state study of a speed sensorless IPMSM drive with an advanced integrator‐based stator flux estimator

In this paper, an advanced integrator is proposed for the estimation of stator flux in a direct torque control (DTC) drive. A two-level lookup table-based direct torque-controlled interior permanent magnet synchronous motor (IPMSM) drive is implemented. DTC has the inherent disadvantage of DC drift and saturation in stator flux estimation due to a pure integrator. In the proposed work, a different approach to estimate stator flux is reported overcoming the constraints of a pure integrator in DTC. An advanced integrator with an adaptive controller is implemented to determine the stator flux and enrich the performance of the drive. A comparison of transient and steady-state analysis is carried out when IPMSM is fed by a low-pass filter-based DTC and proposed stator flux estimator-based DTC. To make the system mechanically robust, stator current-based model reference adaptive control is executed to estimate the motor speed. A mathematical derivation for the stability study of the adaptation mechanism is carried out using Popov's hyperstability criteria. The proposed algorithm is implemented in the MATLAB/Simulink environment and the soundness of the proposed work is presented by simulation results. Moreover, the experimental analysis using dSPACE1104 justifies the simulation results of the proposed system.