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In low intermediate frequency (low-IF) receivers, image interference rejection is one of the core tasks to be accomplished. Conventional active polyphase filters (APPFs) are unable to have a sufficient image rejection ratio (IRR) at high operating frequencies due to the degradation of the IRR by the amplitude and phase imbalances produced by the secondary pole. The proposed solution to the above problem is a frequency-dependent image rejection enhancement technique based on secondary pole compensation. By adjusting the dominant pole frequency of the high-pass filter (HPF) appropriately, the proposed technique can theoretically completely reject the image interference signal even in the presence of the secondary pole. The proposed APPF is simulated and fabricated in a 180-nm CMOS process. The simulation results show that the proposed technique can improve the IRR of the APPF by more than 30 dB at the operating frequency of hundreds of MHz. The measured IRR is better than −31 dB at the frequency from 95 to 105 MHz. Unlike conventional schemes, the proposed design is from the perspective of frequency correlation, which makes the operating frequency no longer limited by the secondary pole frequency. In addition, the proposed design also has an excellent IRR for quadrature input signals with phase imbalance. [ABSTRACT FROM AUTHOR]

This study presents a novel approach utilizing a phononic crystal-based Notch filter in conjunction with the Fano resonance principle to distinguish between different molar fractions of Ethyl lactate within a mixture of Ethyl lactate and 2-Methoxy ethanol. This research marks the first instance of employing a Notch filter configuration in this specific solid–solid structure. The sensor design proposed features a 2D phononic crystal composed of a square lattice of PMMA as the base material, interspersed with circular Tungsten pillars measuring 7 mm × 7 mm in total size. The setup includes a direct waveguide linked to a single ring resonator, with each round of the ring resonator filled with varying concentrations of Ethyl lactate. The transmission frequency is notably affected by the different molar fractions of Ethyl lactate, in relation to their respective sound velocity and mass density characteristics. Furthermore, the efficacy of the sensor is validated using the Fano Anderson model, which closely aligns with the sensor's performance. Additionally, the sensor design exhibits high-quality factor (Q), sensitivity (S), figure of merit (FOM), and limit of detection (LOD) with average values of 66,607, 314.54 Hz/%, 1048, and 477 × 10–7, respectively. It is capable of detecting variations in Ethyl lactate molar fractions, potentially indicating the presence of food additives or fragrances. [ABSTRACT FROM AUTHOR]

ABSTRACT Electrical Interference (EI: radiated electromagnetic and/or power line interference) is a common problem in clinical neurophysiology with many causes and thus various conceivable solutions. Although newer digitized electrodiagnostic (EDX) systems have markedly reduced EI issues, it remains a possible impediment in achieving high quality studies. So that the electrodiagnostic medicine consultant (EMC) can problem solve EI, this monograph details the fundamental functional concepts and terminology of electronic amplification and recording electrodes from a practical perspective. This information is then utilized in a proposed standard operating protocol (SOP) to help the EMC address a wide variety of EI sources. Three major EI sources are considered: the EDX system/operator error, the environment, and the patient. The first is a thorough assessment of the recording electrodes from the perspective of clean electrodes, security of attachment, appropriate gel application, proper lead connections to both the patient and instrument, and similarity of electrode composition. Second is how adverse environmental conditions are mitigated through isolating the EDX instrument from nearby large generator sources, unplugging unnecessary equipment, keeping the amplifier close to the patient along with short and braided electrode leads, and utilize filtering (both 60 Hz and total bandwidth) with appropriate caution to avoid unwanted signal distortion. Third, the patient and EMC interaction must be considered. Specifically, all electronic devices that can be removed should be powered down and relocated as far as feasible from the EDX system, including digital watches, cell phones, TENS units, and other such devices. A systematic application of the above proposed protocol should solve the majority of EI issues. [ABSTRACT FROM AUTHOR]

Notch filters usually involve high costs, great difficulties in processing, and very limited tunability. By coating a nematic liquid crystal (LC) layer onto a well‐designed quasi‐bound states in the continuum (quasi‐BICs) metasurface, this work designs and demonstrates a high‐Q tunable filtering system with precise tunability in the near‐infrared spectral range. Optimal structural parameters and the filtering performance are first determined by numerical simulations and then confirmed in experiments. The precise tunability is enabled by modifying the LC molecules’ principal axes with an applied voltage, where the least distinguishable central wavelength interval is smaller than 0.3 nm, and the largest Q factor extracted from experiments can be ≈256.1. Compared to most of the commercial notch filters that work in the visible region and have no tunability, this work achieves an ultra‐narrowband filtering system that features low manufacture difficulty and cost, and great control of light propagation. The proposed design also opens new avenues for developing BIC‐based high‐Q devices with enhanced signal‐to‐noise ratio and multifunctional properties. [ABSTRACT FROM AUTHOR]

The circuit of an operational amplifier notch filter, using a simulated inductance, is revisited, to reveal its versatility in that, by suitable design and choice of the output point, one can obtain all kinds of filters – all-pass, low-pass, high-pass, band-pass, and band-stop – null as well as notch. Detailed analysis is followed by simulation, to bring out the important characteristics, and considerations in design for a prescribed specification. [ABSTRACT FROM AUTHOR]

This article introduces a new, low cost and complexity, wideband Ku/K‐band combined low‐noise amplifier (LNA) Filter designed for large satellite phased array systems in advanced 22 nm Fully Depleted Silicon on Insulator Technology. The LNA achieves the required 20 dB gain through a two‐stage configuration using the cascode configuration. To effectively reject the transmitter (TX) signal, the LNA integrates 4 distributed parallel LC notch filters. Measured IP1dB at 29 GHz (TX band) demonstrates a 25 dB increase compared to IP1dB at 19 GHz (RX Band), with a remarkable 15 dB enhancement over the LNA without the filter. The 1‐dB gain bandwidth spans from 16 to 21 GHz, representing a 27% fractional bandwidth. Over the entire bandwidth, input/output return losses exceed 10 dB, maintaining a low noise figure (NF) of less than 3.5 dB. Inclusion of two filters at the input and middle of the first stage results in approximately 0.6 dB of increase in NF when compared to the LNA without the filter. [ABSTRACT FROM AUTHOR]

The paper introduces a new approach for designing fractional-order inverse Chebyshev low-pass filters (FOICLF), with an emphasis on filters with an order of 1+α. The coefficients for these filters are determined through Gray Wolf Optimization by approximating filter response with the ideal response of same order FOICLF. Stability tests are conducted, and filters are implemented using Multiple Input Single Output topology with commercial ICs. Comparative analysis reveals close proximity between the ideal response of FOICLF and the designed filters, featuring maximum and mean square errors of –22.48 dB and –61.07 dB, respectively, for 1.7 order. Results are benchmarked against existing literature, highlighting superior performance in stopband and passband magnitude errors and stopband attenuation. Process, Voltage, and Temperature analysis assesses the impact of the parameter variations on the –3 dB frequency, assuring the robustness of designed filters with relative standard deviations ranging from 0.003% to 3.013% for the 1.7 order filter. [ABSTRACT FROM AUTHOR]

Reducing the amount of car accidents and the deaths that result from them requires close monitoring of drivers' health and alertness. Identifying driver weariness has been a major practical concern and problem in recent years. A number of machine learning algorithms have been used for monitoring the driver's health system, even though accurate and early identification is more challenging. In order to overcome this issues, vehicle driver health is monitored using wearable ECG based on an optimized Deep Belief Network (DBN) is proposed. The collected ECG raw signal is pre-processed using a notch filter and high pass filter and an adaptive sliding window to improve the signal quality. After that, Wavelet Packet Decomposition (WPD) and the Short Time Fourier Transform (SIFT) are used to extract features from the pre-processed signal. It enables for the extraction of both time and frequency domain data. In order to classify whether a driver is fit to drive, is under stress, or has a heart condition, the extracted statistical features are sent for further classification using an optimized Deep Belief Neural Network (DBN). The walrus optimization technique is utilized to set the learning rate of the DBN classifier in an optimal manner. To prevent collisions between vehicles, the driver will be alerted via a buzzer system in the event of stress or heart problems. According to the results of the experimental research, the proposed technique achieves 95.1% accuracy, 92.5% precision, 96.5% specificity, 93% of recall, and 92.7% of the f1-score. Thus, the driver health monitoring system can be accurately detected using this automated model. [ABSTRACT FROM AUTHOR]

In this study, the fundamentals of electroencephalography signals, their categorization into frequency sub-bands, the circuitry used for their acquisition, and the impact of noise interference on signal acquisition are examined. Additionally, design specifications for medical-grade and research-grade EEG circuits and a comprehensive analysis of various analog front-end architectures for electroencephalograph (EEG) circuit design are presented. Three distinct selected case studies are examined in terms of comparative evaluation with generic EEG circuit design templates. Moreover, a novel one-channel battery-supplied EEG analog front-end circuit designed to address the requirements of usage protocols containing strong compound muscle movements is introduced. Furthermore, a realistic input signal generator circuit is proposed that models the human body and the electromagnetic interference from its surroundings. Experimental simulations are conducted in 50 Hz and 60 Hz electrical grid environments to evaluate the performance of the novel design. The results demonstrate the efficacy of the proposed system, particularly in terms of bandwidth, portability, Common Mode Rejection Ratio, gain, suppression of muscle movement artifacts, electrostatic discharge and leakage current protection. Conclusively, the novel design is cost-effective and suitable for both commercial and research single-channel EEG applications. It can be easily incorporated in Brain–Computer Interfaces and neurofeedback training systems. [ABSTRACT FROM AUTHOR]

The transmission spectrum of a twin-waveguide cavity is systematically analyzed based on coupled mode theory, using the transfer matrix method (TMM). The results show that the traveling-wave transmission spectra of the twin-waveguide cavity is entirely determined by the coherent coupling effect involving the parameters of the effective refractive indices of the upper and lower waveguides, the coupling length Lc, and the ratio of the cavity length L to the coupling length (L/Lc). Filters with single, double, or triple-notch filtering could be obtained by choosing an appropriate L/Lc value. When the facet reflection is taken into consideration, the traveling-wave transmission spectrum is modified by the Fabry––Perot (FP) resonance, making it a standing-wave transmission spectrum. As a result, resonance splitting has been observed in the transmission spectrum of twin-waveguide resonators with high facet reflectivity. Further analysis shows that such an abnormal resonance phenomenon can be attributed to the destructive interference between the two FP resonance modes of the upper and lower waveguide through coherent coupling. In addition, narrow bandwidth amplification has also been observed through asymmetric facet reflections. Undoubtedly, all these unique spectral characteristics should be beneficial to the twin-waveguide cavity, achieving many more functions and being widely used in photonic integration circuits (PICs). [ABSTRACT FROM AUTHOR]

The application of active magnetic bearings (AMBs) in high-speed rotating machinery faces the challenge of micro-vibration. This research addresses the vibration control of a high-speed magnetically suspended turbo molecular pump (MSTMP) with rotor mass imbalance vibration and multi-stage-blade modal vibration. A novel integrated AMB controller consisting of parallel co-frequency adaptive notch filter (ANF) and cascaded multi-frequency improved double-T notch filters (DTNFs) is proposed. To suppress rotor mass imbalance vibration, a bandwidth factor rectification method of the ANF based on displacement stiffness perturbation is designed. To suppress multi-stage-blade modal vibration, a multi-objective constrained optimization method of cascaded improved DTNFs based on linear normalization is designed. Simulation and experimental results validate that the proposed structure improvement of the addition of an AMB controller and multi-parameter optimization of the algorithm can effectively improve not only the phase stability margin and the notch vibration performance of the magnetically suspended rotor (MSR) system but also the efficiency and practicability of the algorithm. At rotational speeds of 12,000 rpm , 15,000 rpm , 18,000 rpm , and 21,000 rpm , the suppression of co-frequency synchronous vibration is approximately maintained between −30.94 dB and −30.56 dB. At the rated speed of 24,000 rpm , compared with other algorithms, the value of the rotor displacement converges from 0.08 mm to 0.03 mm , a reduction of 62.50%. The convergence time decreases from 3.67 s to 2.85 s , a reduction of 22.34%. [ABSTRACT FROM AUTHOR]

An innovative method of obtaining the weights for a Finite Impulse Response (FIR) notch filter using the Eigen-approach is proposed. The Eigen-approach was used to identify the frequencies of the source signals by determining the eigenvector corresponding to the minimum eigenvalue of the autocorrelation matrix. The FIR notch filter was constructed by shifting the root corresponding to the desired signal, which filtered out all other undesired signals. The obtained results indicate that using the Eigen-approach to generate a selective FIR notch filter is a viable solution. [ABSTRACT FROM AUTHOR]

The achievable performance of conventional repetitive control (CRC) is constrained by the error amplification at the non-harmonic frequencies, the intrinsic sensitivity to the signal period shift and the limited tracking frequency range under fixed sampling rate. To remedy these undesirable behaviors, a notch-filter-based repetitive control (NF-RC) is proposed based on the spectrum-selection filtering scheme in this paper with application to fast tool servos (FTSs). The loop-shaping property of this NF-RC can be flexibly designed by the cascade of a series of parameterized IIR notch filters without the aforementioned limitations of the CRC, so as to provide a unified formula for various RCs and even resonant control schemes. A general realization along with several simplified versions of the IIR notch filter is derived for the digital implementation of the NF-RC. Comparative trajectory tracking experiments on a self-developed FTS have validated the superiorities of the proposed NF-RC in terms of the performance improvement for periodic reference tracking, the robustness against the signal period variations and the trackable frequency range under fixed sampling rate. Taking advantage of an excellent comprehensive performances of the NF-RC scheme, the radial sinusoidal surface and the water-drop surface were successfully produced with high form precision and excellent surface quality after the FTS-based diamond turning. • A novel notch-filter-based repetitive control (RC) scheme is proposed. • This RC scheme can suppress the nonperiodic errors amplification. • This RC scheme can maintain the robustness against the signal frequency fluctuation. • This RC scheme can track any harmonic references under a fixed sampling rate. • This RC scheme provides a unified design framework for various existing RCs. • Two high-accuracy micro-structured surfaces are fabricated with this RC scheme. [ABSTRACT FROM AUTHOR]

In low intermediate frequency (low-IF) receivers, image interference rejection is one of the core tasks to be accomplished. Conventional active polyphase filters (APPFs) are unable to have a sufficient image rejection ratio (IRR) at high operating frequencies due to the degradation of the IRR by the amplitude and phase imbalances produced by the secondary pole. The proposed solution to the above problem is a frequency-dependent image rejection enhancement technique based on secondary pole compensation. By adjusting the dominant pole frequency of the high-pass filter (HPF) appropriately, the proposed technique can theoretically completely reject the image interference signal even in the presence of the secondary pole. The proposed APPF is simulated and fabricated in a 180-nm CMOS process. The simulation results show that the proposed technique can improve the IRR of the APPF by more than 30 dB at the operating frequency of hundreds of MHz. The measured IRR is better than −31 dB at the frequency from 95 to 105 MHz. Unlike conventional schemes, the proposed design is from the perspective of frequency correlation, which makes the operating frequency no longer limited by the secondary pole frequency. In addition, the proposed design also has an excellent IRR for quadrature input signals with phase imbalance.

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A simple technique for frequency-static multi-notch/transmission-zero (TZ) creation in RF filters with single- and dual-band bandpass transfer functions is presented. It is based on the direct connection of two identical inline filtering units without stopband TZs in an in-parallel configuration by means of unequal input/output transmission-line segments for each branch. Unlike in typical transversal-signal-interference and channelized filter architectures, the overall length of these connecting transmission-line segments for both branches is the same. Thus, the multi-notch/TZ generation in the whole filtering action is accomplished by differently distributing this total electrical length between the input/output transmission-line segments for the two branches. As such, enhanced selectivity in the filtering response with several embedded notches when compared to the filtering transfer function of an isolated branch can be obtained. To experimentally demonstrate the generality of this approach, two proof-of-concept filter prototypes corresponding to a 2$/$3-GHz microstrip dual-band bandpass filter (BPF) and a 62-GHz waveguide BPF are built and tested.

The suppression of load swing angle of tower crane system is crucial for its safe operation. The existing anti-swing control methods have achieved good results in restraining the swing angle. However, these anti-swing control methods do not consider the buffeting of steel wire rope and load, which poses potential safety hazards. To solve this problem, a method to suppress the swing angle of tower crane system considering wire rope buffeting was proposed. Specifically, firstly, the nonlinear buffeting mechanism model was established for the tower crane in a horizontal motion, and then the nonlinear buffeting torque transmitted to the main shaft of the motor after the buffeting of the system was calculated, the equivalent reverse of the buffeting torque was used as the compensating torque. Secondly, the notch filter was used to filter out other disturbances apart from the compensating torque. After that, the compensating torque was superposed with the control torque calculated by a sliding mode anti-sway control law to control the output torque of the drive motor. Finally, the simulation and experimental results demonstrate that the proposed method achieves better control effectiveness in the pendulum angle suppression. [ABSTRACT FROM AUTHOR]

Robots in space are necessarily extremely light and lack structural stiffness resulting in natural frequencies of resonance so low as to reside inside the attitude controller's bandwidth. A variety of input trajectories can be used to drive a controller's attempt to ameliorate the control-structural interactions where feedback is provided by low-quality, noisy sensors. Traditionally, step functions are used as the ideal input trajectory. However, step functions are not ideal in many applications, as they are discontinuous. Alternative input trajectories are explored in this manuscript and applied to an example system that includes a flexible appendage attached to a rigid main body. The main body is controlled by a reaction wheel. The equations of motion of the flexible appendage, rigid body, and reaction wheel are derived. A benchmark feedback controller is developed to account for the rigid body modes. Additional filters are added to compensate for the system's flexible modes. Sinusoidal trajectories are autonomously generated to feed the controller. Benchmark feedforward whiplash compensation is additionally implemented for comparison. The method without random errors with the smallest error is the sinusoidal trajectory method, which showed a 97.39% improvement when compared to the baseline response when step trajectories were commanded, while the sinusoidal method was inferior to traditional step trajectories when sensor noise and random errors were present. [ABSTRACT FROM AUTHOR]

In recent years, hydrogen energy has garnered attention as a potential solution for mitigating greenhouse gas emissions. However, concerns regarding the inherent risk of hydrogen gas leakage and potential explosions have necessitated the development of advanced sensors. Within our research group, we have innovated an ultrathin platinum (Pt) film hydrogen sensor that gauges resistance changes in Pt thin films when exposed to hydrogen gas. Notably, the sensitivity of each sensor is contingent upon the thickness of the Pt film. To address the challenge of detecting hydrogen using multiple sensors, we integrated the ultrathin Pt film as a resistance element within a twin-T type notch filter. This filter exhibits a distinctive reduction in output signals at a specific frequency. The frequency properties of the notch filter dynamically alter with changes in the resistance of the Pt film induced by hydrogen exposure. Consequently, the ultrathin Pt film hydrogen sensor monitors output signal variations around the notch frequency, responding to shifts in frequency properties. This innovative approach enables the electrical control of sensor sensitivity by adjusting the operating frequency in proximity to the notch frequency. Additionally, the simultaneous detection of hydrogen by multiple sensors was successfully achieved by interconnecting sensors with distinct notch frequencies in series. [ABSTRACT FROM AUTHOR]

Several layers of defense can be implemented in a global navigation satellite system (GNSS) receiver to improve its performance in the presence of interference. These layers include the use of pre-correlation mitigation techniques, post-correlation quality indicators to screen measurements, and fault detection and exclusion (FDE) at the position solution level. This paper provides a characterization of the interactions between these layers of interference mitigation and a measurement quality check. Data collected in the presence of increasing levels of jamming were processed using different interference mitigation techniques, including robust interference mitigation (RIM) and the adaptive notch filter (ANF). A software defined radio (SDR) approach was adopted and measurements were generated by considering five interference-mitigation techniques. Position solutions were then computed using a forward-backward approach for receiver autonomous integrity monitoring (RAIM). Signals from GPS, Galileo, and Beidou were processed and both single and dual-constellation solutions were analyzed. The analysis revealed that interference mitigation allows the receiver to track a larger number of signals even in the presence of high levels of jamming power. This increased measurement availability was then effectively exploited by RAIM techniques to provide more reliable solutions. Measurements from several constellations further improved the reliable availability of the position solutions. [ABSTRACT FROM AUTHOR]

In this paper, a new compact dual-band bandpass filter (DB-BPF) is proposed using parallel coupled lines. The design method is based on introducing transmission zeros (TZs) in the frequency response of a single-wideband filter. In the proposed structure, three coupled lines and a multi-mode resonator are used to realize the wide bandpass filter. Meanwhile, two coupled lines that are connected at the end and loaded by an open-circuit stub are employed to make a new notch filter. The proposed DB-BPF is designed and fabricated on Rogers RO3210 substrate for Wireless Local Area Networks (WLANs) applications. The simulation results show good agreement with measurements. The measured results exhibit two passbands centered at 2.4 and 5.2 GHz, having an insertion loss of less than 0.1 dB and 0.9 dB, respectively. Low insertion loss, compact size, and high attenuation between two passbands are the main advantages of the proposed DB-BPF. [ABSTRACT FROM AUTHOR]

In this study, the fundamentals of electroencephalography signals, their categorization into frequency sub-bands, the circuitry used for their acquisition, and the impact of noise interference on signal acquisition are examined. Additionally, design specifications for medical-grade and research-grade EEG circuits and a comprehensive analysis of various analog front-end architectures for electroencephalograph (EEG) circuit design are presented. Three distinct selected case studies are examined in terms of comparative evaluation with generic EEG circuit design templates. Moreover, a novel one-channel battery-supplied EEG analog front-end circuit designed to address the requirements of usage protocols containing strong compound muscle movements is introduced. Furthermore, a realistic input signal generator circuit is proposed that models the human body and the electromagnetic interference from its surroundings. Experimental simulations are conducted in 50 Hz and 60 Hz electrical grid environments to evaluate the performance of the novel design. The results demonstrate the efficacy of the proposed system, particularly in terms of bandwidth, portability, Common Mode Rejection Ratio, gain, suppression of muscle movement artifacts, electrostatic discharge and leakage current protection. Conclusively, the novel design is cost-effective and suitable for both commercial and research single-channel EEG applications. It can be easily incorporated in Brain–Computer Interfaces and neurofeedback training systems.

The transmission spectrum of a twin-waveguide cavity is systematically analyzed based on coupled mode theory, using the transfer matrix method (TMM). The results show that the traveling-wave transmission spectra of the twin-waveguide cavity is entirely determined by the coherent coupling effect involving the parameters of the effective refractive indices of the upper and lower waveguides, the coupling length Lc, and the ratio of the cavity length L to the coupling length (L/Lc). Filters with single, double, or triple-notch filtering could be obtained by choosing an appropriate L/Lc value. When the facet reflection is taken into consideration, the traveling-wave transmission spectrum is modified by the Fabry––Perot (FP) resonance, making it a standing-wave transmission spectrum. As a result, resonance splitting has been observed in the transmission spectrum of twin-waveguide resonators with high facet reflectivity. Further analysis shows that such an abnormal resonance phenomenon can be attributed to the destructive interference between the two FP resonance modes of the upper and lower waveguide through coherent coupling. In addition, narrow bandwidth amplification has also been observed through asymmetric facet reflections. Undoubtedly, all these unique spectral characteristics should be beneficial to the twin-waveguide cavity, achieving many more functions and being widely used in photonic integration circuits (PICs).

The application of active magnetic bearings (AMBs) in high-speed rotating machinery faces the challenge of micro-vibration. This research addresses the vibration control of a high-speed magnetically suspended turbo molecular pump (MSTMP) with rotor mass imbalance vibration and multi-stage-blade modal vibration. A novel integrated AMB controller consisting of parallel co-frequency adaptive notch filter (ANF) and cascaded multi-frequency improved double-T notch filters (DTNFs) is proposed. To suppress rotor mass imbalance vibration, a bandwidth factor rectification method of the ANF based on displacement stiffness perturbation is designed. To suppress multi-stage-blade modal vibration, a multi-objective constrained optimization method of cascaded improved DTNFs based on linear normalization is designed. Simulation and experimental results validate that the proposed structure improvement of the addition of an AMB controller and multi-parameter optimization of the algorithm can effectively improve not only the phase stability margin and the notch vibration performance of the magnetically suspended rotor (MSR) system but also the efficiency and practicability of the algorithm. At rotational speeds of 12,000 rpm, 15,000 rpm, 18,000 rpm, and 21,000 rpm, the suppression of co-frequency synchronous vibration is approximately maintained between −30.94 dB and −30.56 dB. At the rated speed of 24,000 rpm, compared with other algorithms, the value of the rotor displacement converges from 0.08 mm to 0.03 mm, a reduction of 62.50%. The convergence time decreases from 3.67 s to 2.85 s, a reduction of 22.34%.

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the rising prevalence of wearable biomedical devices for recording diverse biosignals, the potential for inaccurate interpretations due to noise susceptibility, including false alarms and misdiagnoses, is increasingly recognized. This study presents the systematic design and evaluation of a current-mode-based active notch filter aimed at eliminating the pervasive power-line interference (PLI) that corrupts biosignals. The filter is constructed using a modern and versatile current-mode analog building block (ABB), specifically the voltage differencing gain amplifier (VDGA). The design of this second-order filter incorporates a single VDGA as an active component and two capacitors as passive components, eliminating the need for resistors. Employing this filter, the influence of the 50Hz PLI on biological signals is effectively suppressed. The filter exhibits desirable properties of the current-mode circuit, including reduced power consumption, an expanded dynamic range, and enhanced accuracy. Key parameters of the filter, such as the pole frequency and the quality factor, can be electronically adjusted and orthogonally tuned via the bias currents of the VDGA. To validate its functionality, the proposed filter design was simulated using the PSPICE simulator with the MAX435 IC's macro-model. The simulation results revealed a notch depth and total harmonic distortion (THD) of -52.9 dB and -55 dB, respectively. The performance of this filter was subsequently compared with existing analog notch filters detailed in the literature. Given its efficacy and simplicity, the proposed filter is deemed suitable for deployment in high-performance biomedical detection equipment. [ABSTRACT FROM AUTHOR]

Trade-off between transient response and grid-side current quality is a well-known issue of single-phase mains-connected power converters. A dual-loop control structure (usually based on PI or type-II controllers) is typically employed in such systems to regulate the DC link voltage to a constant reference (in order to maintain power balance) while forcing the grid-side current to have a specific shape (in order to comply with power quality requirements). Introducing notch term/s (tuned to certain multiple/s of the mains base frequency) into one of the loops allows either for the improvement of the dynamic performance without worsening the total harmonic distortion of grid-side current or for the enhancement of the current quality without impairing the dynamic response. Since the maximum tolerable value of total harmonic distortion is typically imposed by a certain power quality standard, it is desirable to enhance the transient response of the power converter system as much as possible while keeping the total harmonic distortion at the maximum allowed value. However, universal off-grid operating power conversion systems must support both 50 Hz and 60 Hz mains; consequently, tuning the notch term/s to 50 Hz multiple/s would not be sufficient for a 60 Hz mains operation and vice-versa. Consequently, this work examines the possibility of introducing a dual-notch term into the control loop in order to cover both above-mentioned base frequencies. It is demonstrated that under typical base frequency uncertainty values, the performances of dual-notch terms are nearly decoupled so that the term tuned to a 50 Hz frequency (and optionally to its multiples) has nearly no influence at a 60 Hz mains operation and vice-versa. Consequently, the methodology allows for the improvement of the dynamics of universal grid-connected power converters without total harmonic distortion (THD) deterioration. A stability analysis of the proposed control structure is carried out and quantitative design guidelines, allowing for the attainment of an optimized dynamic response for a given maximum tolerable total harmonic distortion, minimum allowed phase margin and a certain base frequency uncertainty, are established. It is shown that a DC link voltage loop bandwidth of 52 Hz may be attained while keeping the grid-side current THD below 5%. Simulations and experimental results support well the proposed design methodology. [ABSTRACT FROM AUTHOR]

Dual Active Bridge (DAB) converter is well suited for off-board fast Electric Vehicle Charging Stations (EVCS) and in DC microgrid-connected EVCS applications. However, proper modification in DAB converter topology is crucial for fast charging, as the charging current is very high, and any oscillations would shorten the EV battery life. As per literature, DAB converter topology integrated with a series inductor at the output for EV battery charging reduces the output current ripple by 40%. However, as per our observation, potentially unstable dynamics are introduced in the system with the inclusion of an LC filter. This affects the controller stability; hence, these dynamics must be damped using active or passive damping. Passive damping is less efficient due to the considerable losses it produces, partly induced by low-frequency noise and partly from switching-frequency noise. Also, placing the damping at the selective resonant frequency is very complex. In comparison, active damping offers selective placement and loss reduction. This paper presents the DAB converter mathematical modeling using the generalized average model (GAM) and the average output current linearization model (AOCLM). The paper presents stability analysis and proposes a novel and robust approach to control the dynamics in the current and voltage control loops during EV charging, thereby reducing battery degradation. The charge flow to the battery is controlled using Constant Current Constant Voltage (CCCV) algorithm. The proposed scheme also eliminates the need for extra sensors by selectively attenuating the oscillations at the frequency of interest. The performance of the proposed model for EV fast charging application is verified using MATLAB/Simulink and experimentally validated in a real-time simulator OPAL-RT hardware platform.

Electric vehicles (EVs) are a promising solution to reduce carbon dioxide (CO2) emissions, but this reduction depends on the fraction of renewable sources used to generate electricity. Wind energy is thus a vital candidate and has experienced a remarkable surge recently, establishing itself as a leading renewable power source worldwide. The research on Direct-Driven Permanent Magnet Synchronous Generator (PMSG)-based type 4 wind farms has indicated that the Phase-locked Loop (PLL) bandwidth significantly impacts Sub-Synchronous Resonance (SSR). However, the influence of PLL architecture on SSR remains unexplored and warrants investigation. Therefore, this paper investigates PLL architectural variations in PLL Loop Filter (LF) to understand their impact on SSR in type 4 wind farms. Specifically, an in-depth analysis of the Notch Filter (NF)-based enhanced PLL is conducted using eigenvalue analysis of the admittance model of a PMSG-based type 4 wind farm. The findings demonstrate that the NF-based enhanced PLL exhibits superior performance and improved passivity in the sub-synchronous frequency range, limiting the risk of SSR below 20 Hz. Additionally, Nyquist plots are employed to assess the impact on system stability resulting in increased stability margins. In the future, it is recommended to further investigate and optimize the PLL to mitigate SSR in wind farms. [ABSTRACT FROM AUTHOR]

A new method for accurately estimating heart rates based on a single photoplethysmography (PPG) signal and accelerations is proposed in this study, considering motion artifacts due to subjects' hand motions and walking. The method comprises two sub-algorithms: pre-quality checking and motion artifact removal (MAR) via Hankel decomposition. PPGs and accelerations were collected using a wearable device equipped with a PPG sensor patch and a 3-axis accelerometer. The motion artifacts caused by hand movements and walking were effectively mitigated by the two aforementioned sub-algorithms. The first sub-algorithm utilized a new quality-assessment criterion to identify highly noise-contaminated PPG signals and exclude them from subsequent processing. The second sub-algorithm employed the Hankel matrix and singular value decomposition (SVD) to effectively identify, decompose, and remove motion artifacts. Experimental data collected during hand-moving and walking were considered for evaluation. The performance of the proposed algorithms was assessed using the datasets from the IEEE Signal Processing Cup 2015. The obtained results demonstrated an average error of merely 0.7345 ± 8.1129 beats per minute (bpm) and a mean absolute error of 1.86 bpm for walking, making it the second most accurate method to date that employs a single PPG and a 3-axis accelerometer. The proposed method also achieved the best accuracy of 3.78 bpm in mean absolute errors among all previously reported studies for hand-moving scenarios. [ABSTRACT FROM AUTHOR]

The design of a copter has been carried out, that can be used to set up air interference, reducing the probability of impact of the enemy air defense systems, reconnaissance operations, and the transfer of military cargo. The developed hexacopter is capable of carrying a useful load of 2.5-3.0 kg, at a speed of up to 45 km/h, based on a Pixhawk family flight controller using the Arducopter firmware. Stability of the flight of a quadcopter on a frame of 850 mm during a gusty wind of 7-8 m/s in navigation modes for firmware Arducopter ver.4.0.7 has been experimentally tested. The use of software dynamic notch filters to reduce the impact of vibrations from running motors on the readings of the accelerometer and gyroscope is considered. [ABSTRACT FROM AUTHOR]

In practice, the unbalanced mass of the propeller is the leading cause of vibration in a quadcopter. Therefore, this paper proposes an additive-state-decomposition notch dynamic inversion controller to suppress the vibration noise. Firstly, the vibration mechanics model based on unbalanced mass is established and its characteristic frequency is analyzed. Then, the specific form of the notch filter is designed, and this characteristic frequency is taken as its internal parameter. Next, stability analysis shows that the proposed controller guarantees that all attitude signals are globally uniformly ultimately bounded. In particular, the notch filter can effectively reduce the vibration having a specific frequency. Finally, the proposed controller is performed on a real quadcopter to verify its vibration reduction performance. [ABSTRACT FROM AUTHOR]

We propose two single-wavelength notch filters and one dual-wavelength (480 and 620 nm) notch filter to enhance image contrast. The stack structure of the notch filters was designed as (Ta2O5/SiO2)4Ta2O5 in Essential Macleod thin film simulation software. Dual-electron-beam evaporation with ion beam-assisted deposition was used to prepare optical interference filters with different center wavelengths. A multilayer notch filter with a center wavelength of 620 nm was deposited on the front surface of the glass, and then a notch filter with a center wavelength of 480 nm was coated on the rear surface of the same glass. The proposed dual-wavelength (480 and 620 nm) notch filter is a combination of two single-wavelength notch filters coated on a double-sided glass substrate to compensate for residual stress. The transmittance, residual stress, and surface roughness of the proposed notch filter were evaluated using different measuring instruments. The experimental results show that the residual stress of the dual-wavelength notch filter could be reduced to 10.8 MPa by using a double-sided coating technique. The root-mean-square (RMS) surface roughness of the notch filters was measured by using a Linnik microscopic interferometer. The RMS surface roughness was 1.80 for the 620 nm notch filter and 2.09 for the 480 nm notch filter. The image contrast obtained with the three different notch filters was measured using an optical microscope and a CMOS camera. The contrast value could be increased from 0.328 (without a filter) to 0.696 (dual-wavelength notch filter). [ABSTRACT FROM AUTHOR]

Radiography image processing is a technique used for processing radiography images using mathematical operations in which the input is a dental X- ray image or a sequence of X- ray images. The accuracy related segmentation for tooth images forms key point in computer based algorithms. To the great extent image processing techniques has two dimensional images used for processing. The methods of dental X-ray image diagnostic procedure are well established in the dentistry field. This is very useful to the dentist to get extra diagnostic information. Typically, in dental X-ray images, detection of caries and other hard tissues are challenging tasks. These x-ray images have unwanted noises that lead to poor diagnostic information. The main aim of proposed dental image processing system is to remove the unwanted noises at first with the help of robust Hybrid Binary Thresholding with Notch Filter (HBT-NF). The next step with the segmentation of caries, hard tissues from tooth lies with proposed Curvilinear Semantic Deep Convolutional neural network. Finally the teeth are separated from hard tissues and caries at high accuracy of 93.7%. Experimental results on the real dental X-ray images of the proposed system will give better effectiveness compared with other detection methods. [ABSTRACT FROM AUTHOR]

In this paper, a novel multivariate active noise control scheme, designed to attenuate disturbances with high autocorrelation characteristics and preserve background signals, is proposed. The algorithm belongs to the class of feedback controllers and, unlike the popular feedforward FX-LMS approach, does not require availability of a reference signal. The proposed approach draws its inspiration from the iterative learning control and repetitive mode control methods, and employs a modified inverse model learning law. The classical inverse model learning law is well known to offer fast convergence and high steady-state performance, provided that the secondary path is minimum phase and well known. The proposed modified inverse model learning law employs a spectral factorization trick, which allows one to use the method with nonminimum phase plants of arbitrary order. Moreover, our scheme includes a controller bandwidth limiting mechanism that can be used to tune the disturbance rejection bandwidth and to improve the closed-loop robustness to errors in the model of the secondary path. The algorithm's behavior and performance are verified with computer simulations that demonstrate suppression of electrical transformer noise and include realistic models of the secondary path. The results show high-level selective attenuation and fast convergence. [ABSTRACT FROM AUTHOR]

In this paper, a structured illumination microscopy (SIM) image reconstruction algorithm combined with notch function (N-SIM) is proposed. This method suppresses the defocus signal in the imaging process by processing the low-frequency signal of the image. The existing super-resolution image reconstruction algorithm produces streak artifacts caused by defocus signal. The experimental results show that the algorithm proposed in our study can well suppress the streak artifacts caused by defocused signals during the imaging process without losing the effective information of the image. The image reconstruction algorithm is used to analyze the mouse hepatocytes, and the image processing tool developed by MATLAB is applied to identify, detect and count the reconstructed images of mitochondria and lipid droplets, respectively. It is found that the mitochondrial activity in oxidative stress induced growth inhibitor 1 (OSGIN1) overexpressed mouse hepatocytes is higher than that in normal cells, and the interaction with lipid droplets is more obvious. This paper provides a reliable subcellular observation platform, which is very meaningful for biomedical work. [ABSTRACT FROM AUTHOR]

Main drive system of multi-stand hot continuous rolling finishing mill has the characteristics of rapid loading and unloading, frequent acceleration and deceleration, multi-stand coupling and mutual interference, and has high requirements for the performance and reliability of frequency converter. Traditional drive system has some problems, such as complex transformer structure, high harmonic content in power grid measurement, slow motor control response, motor torsional vibration and so on. According to the application characteristics of multi-stand hot continuous rolling finishing mill, this paper proposes a high performance drive system solution. Compared with the traditional system, the proposed system has the advantages of unified circuit, low harmonic content in grid side, fast motor speed response, active suppression of motor torsional vibration and so on. It mainly introduces the main circuit scheme of the mill main drive system, the control principle of the grid side converter, and the vector control principle of the motor. Causes of torsional vibration are analyzed, and the suppression method of motor torsional vibration is introduced. The scheme has been verified by digital simulation and field performance evaluation. Experimental results show that the proposed main drive system has superior dynamic and steady-state performances, the voltage harmonic content is less than 4%, the motor torque can respond to the sudden change of load, multiple motors can work stably, and the transmission system can fully meet the requirements of field hot continuous rolling process.