Frequency Modulation Operation Research Articles

Monolithic three-dimensional hafnia-based artificial nerve system

Artificial nerve systems that mimic the tactile perception ability of human skin could be adopted in the realization of devices for a hyperconnected society, including prosthetic devices, interfaces for virtual reality, and smart sensors. The system consists of a pressure sensor, memory, and signal processing circuit, which possess the capability of generating sensory neuron-like signals. Although technological advances have been made in semiconductor-based memory and transistors over the decades, sensor technology is still relying on micro-electromechanical systems, which are hard to realize miniaturization/high-density and high-performance technology. Here, we demonstrate a monolithic three-dimensional integrated artificial nerve on the basis of ferroelectric HfxZr1-xO2 for use in the core element of neuromorphic memory and a self-powered piezoelectric pressure sensor. The morphotropic phase boundary (MPB) state of hafnia film was formed between orthorhombic and tetragonal phases for high piezoelectric performance. The MPB-based sensor was integrated with self-rectifying ferroelectric tunnel junction memory and silicon-based ring oscillator. We realized a frequency-modulated pulse-like synaptic signal with pressure detection ability over a wide range of 1–50 kPa and a good sensitivity of 0.35 mV/kPa. Also, we demonstrate the real-time frequency-modulated operation of the artificial nerve system by adjusting the functional properties of the hafnia films.

Contributions of reactor geometry and ultrasound frequency on the efficiency of sonochemical reactor

An intermediate-scale reactor with 10L capacity and two transducers operating at 700 and 950 kHz frequencies was developed to study the scalability of the sonolytic destruction of Per and Polyfluoroalkyl substance (PFAS). The impact of frequency, height of liquid or power density, and transducer position on reactor performance was evaluated with the potassium iodide (KI) oxidation and calorimetric power. The dual frequency mode of operation has a synergistic effect based on the triiodide concentration, and calorimetric power. The triiodide concentration, and calorimetric power were higher in this mode compared to the combination of both frequencies operating individually. The sonochemical efficiency for an intermediate-scale reactor (10L) was similar that obtained from a bench-scale reactor (2L), showing the scalability of the sonolytic technology. The placement of the transducer at the bottom or side wall of the reactor had no significant impact on the sonochemical reactivity. The superposition of the ultrasonic field from the dual transducer mode (side and bottom) did not produce a synergistic effect compared to the single transducer mode (bottom or side). This can be attributed to a disturbance due to the interaction of ultrasonic fields of two frequencies from each transducer. With the encouraging results scaling up is in progress for site implementation.

Angular momentum sensitivity of a MEMS gyroscope for condensed matter systems

The angular momentum carries crucial information on the physical nature of quantum matter. We propose and analyze MEMS gyroscope techniques suitable for measuring the angular momentum of mesoscopic quantum matter specimens at low temperatures. We bear in mind that it is not always possible to implement mode-matched gyroscopes, which we will refer to as degenerate gyroscopes, for the maximal signal sensitivity for these applications due to the constraints given by the cryogenic environment and the types of samples available for experiments. Because the analysis of non-degenerate gyroscopes in the literature is somewhat limited, we analyze and compare the ultimate angular momentum sensitivity of both degenerate and non-degenerate gyroscopes under amplitude and frequency modulation operation. Calculation based on our prototype device shows that the frequency modulation extends the operational range and improves sensitivity at low temperatures.

Degradation of sulfamerazine using ultrasonic horn and pilot scale US reactor in combination with different oxidation approaches

The present study aimed at utilizing ultrasonic horn (USH) and ultrasonic reactor (USR) having provision for dual frequency operation for the successful and cost-effective degradation of sulfamerazine (SMZ). USH and USR were combined with UV, persulfate (PS), peroxymonosulfate (PMS), Fenton (Fe2+/H2O2) and Fenton like (Fe3+/H2O2) process in detailed investigation to establish the optimal loading for obtaining the improved degradation of SMZ quantified in terms of the synergistic index values. A mathematical model was also developed to explain the complex SMZ degradation kinetics for all the AOPs. Significantly higher SMZ degradation (>99 %) was achieved for various combined approaches as USH/PS, USH/PMS, USH/Fe2+/H2O2, USH/Fe3+/H2O2, USH/PS/UV, USH/PMS/UV, USH/Fe2+/H2O2/UV, and USH/Fe3+/H2O2/UV, demonstrating the significant role of SO4¯ and OH radicals in intensifying the oxidation of the SMZ molecules. The pilot scale study with USR also demonstrated effective SMZ degradation using combined AOPs with maximum removal as 94.14 % for USR (22 + 44 kHz)/Fe3+/H2O2/UV. The dual frequency mode of operation was observed to be more efficient than the single frequencies. The cost estimation study based on of cavitational yield revealed that the most cost-effective system was the USR (22 + 44 kHz)/Fe3+/H2O2/UV with a degradation cost of 0.57 ₹/L (0.0069 $/L).

A Three-Phase Dual-Output T-Type Three-Level Converter

A novel three-phase dual-output T-type three-level converter (DO-T-TLC) topology is proposed in this article. The proposed topology has the dc-link and two sets of three-phase ac voltage output terminals. The topology of DO-T-TLC is introduced. Then, the operating principle of multiplexing switches and the available switching states of converter are analyzed, including current path, output phase voltage level, and blocking voltage of different switching states. The phase disposition pulsewidth modulation scheme with dc offsets is discussed in detail, and the key problems of the modulation scheme under both the common frequency and different frequency operation modes, such as voltage level selection, displacement angle constraint, and modulation index range, are studied. For the imbalance of two series capacitors in the dc-link, the mechanism is first revealed, and then a dc-link capacitor voltage balance method to control the average neutral point current is proposed. When DO-T-TLC is used in different operation modes, the ability and effect of this method to balance capacitor voltages are summarized. A low-power three-phase prototype is built, and the experimental results are given to verify the feasibility of the proposed topology and the effectiveness of the modulation scheme to control the voltage balance.

Artificial Intelligence Control System Applied in Smart Grid Integrated Doubly Fed Induction Generator-Based Wind Turbine: A Review

Wind-driven turbines utilizing the doubly-fed induction generators aligned with the progressed IEC 61400 series standards have engrossed specific consideration as of their benefits, such as adjustable speed, consistent frequency mode of operation, self-governing competencies for voltage and frequency control, active and reactive power controls, and maximum power point tracking approach at the place of shared connection. Such resource combinations into the existing smart grid system cause open-ended problems regarding the security and reliability of power system dynamics, which needs attention. There is a prospect of advancing the art of wind turbine-operated doubly-fed induction generator control systems. This section assesses the smart grid-integrated power system dynamics, characteristics, and causes of instabilities. These instabilities are unclear in the wind and nonlinear load predictions, leading to a provisional load-rejection response. Here, machine learning computations and transfer functions measure physical inertia and control system design’s association with power, voltage, and frequency response. The finding of the review in the paper indicates that artificial intelligence-based machine and deep learning predictive diagnosis fields have gained prominence because of their low cost, less infrastructure, reduced diagnostic time, and high level of accuracy. The machine and deep learning methodologies studied in this paper can be utilized and extended to the smart grid-integrated power context to create a framework for developing practical and accurate diagnostic tools to enhance the power system’s accuracy and stability, software requirements, and deployment strategies.

Mapping of cavitation intensity in a novel dual-frequency ultrasonic reactor of capacity 10 L

Mapping of a dual-frequency ultrasonic reactor was performed based on measurements of local cavitation intensity at various horizontal and vertical planes in the reactor for single frequency operation (22 kHz or 44 kHz) and dual-frequency operation (22 + 44 kHz) at varying input power of 250 and 450 W. The average cavitation intensity ranged between 73.6 and 86.7 W/cm2, 38.75 and 64.4 W/cm2, 86.7 and 100.6 W/cm2 for the operating frequencies of 22, 44 and 22 + 44 kHz respectively at maximum input power of 450 W depending on the location. Bubble dynamics simulations at various frequencies were also performed using the Keller-Miksis equation and the trends of bubble radius, collapse temperature and pressure were found to effectively match the experimental findings for cavitation intensity. The work has clearly elucidated the dependency of the cavitational activity on location, power dissipation and operating frequency mode with dual-frequency operating showing higher cavitation intensity.

Research on the Primary Frequency Modulation Operation of 650MW Nuclear Power Steam Turbine Unit in China

Research on the Primary Frequency Modulation Operation of 650MW Nuclear Power Steam Turbine Unit in China

Optical frequency comb generation from a 1.65 µm single-section quantum well laser.

Optical frequency combs (OFCs) in the 1.65 µm wavelength band are promising for methane sensing and extended high-capacity optical communications. In this work, a frequency-modulated (FM) OFC is generated from a 1.65 µm single-section quantum well laser. This is characterized by a 1 kHz-wide beatnote signal at ∼19.4 GHz. Typical FM optical spectra are shown and optical linewidth of the OFC narrows through the mutual injection locking process in the comb formation. No distinct pulse train is observed on oscilloscope, which conforms with the FM operation. Furthermore, to add further evidence that four-wave mixing (FWM) is the driving mechanism of the comb formation, FWM frequency conversion characterization is conducted on a semiconductor optical amplifier (SOA) fabricated together with the tested laser. An efficiency of ∼-30 dB confirms the capability of FM mode locking.

An air insulated linear pulse transformer for electrodischarge technology

A linear pulse transformer with air insulation at atmospheric pressure was created and tested under both constant resistance and non linear loads. The maximum power of the transformer output pulse reached ∼500 MW at a matched load with a charge voltage 50 kV. The transformer transferred ∼60% of the stored energy to the load over a characteristic time of about 1 μs. The scalability the generator was studied by connecting two identical transformers in series which gave a power output of ∼850 MW with doubled output voltage and reduced current. The frequency mode of operation was studied using one and two transformers with a charge voltage of 50 kV and a load that was, close to matched. In both cases, the power maximum and jitter showed no significant changes at any of the frequencies tested (up to 5 Hz). These results mean that the use of this generator can be recommended for a wide field of applications due to its scalability and low internal impedance.

Radially Pleated Disk Resonator for Gyroscopic Application

In this paper, we propose a radially pleated disk resonator for gyroscopic application. The structure is made up of concentrically nested radially pleated rings that are interconnected by straight spokes, which has the potential to provide higher thermo-elastic quality factor and larger vibration amplitude. Decaying time constant of 31 s is experimentally obtained at resonant frequency of 3 kHz. A frequency-tuning model is proposed and verified, based on which, the frequency-tuning characters of the radially pleated disk resonator are thoroughly investigated. The Coriolis coupling factor <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\kappa $ </tex-math></inline-formula> of the radially pleated disk resonator is precisely measured by constructing a concise quadrature frequency-modulation operation, which gives the values of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\kappa $ </tex-math></inline-formula> = 0.7687 and agrees well with the calculated value of 0.7768. This work provides a new strategy for designing high performance MEMS gyroscope structure, and gives a good template for gyroscopic resonator characterization. [2021-0096]

Mapping of suspended sediment transport using acoustic methods in a Pantanal tributary.

Generally, fluvial systems are used for different objectives including energy production, water supply, recreation, and navigation. Thus, many impacts must be considered with their use. An understanding of sediment dynamics in fluvial systems is often of value for a variety of objectives, given that erosion and depositional processes can change the fluvial system morphology and can substantially alter the fluvial environment. In this sense, sediment monitoring is important because it helps to explain and quantify sediment dynamics in the environment. Hence, this study presents an innovative sediment monitoring technique: the use of the acoustic Doppler current profiler, commonly used to obtain discharge measurements, to obtain suspended sediment concentration (SSC). This paper aims to describe the application of additional corrections to the ADP-M9 signal to obtain SSC from measurement campaigns that used the ADP only for discharge measurements. The analyses were based on traditional sediment sampling methods and discharge measurements, with the ADP-M9, from 7 field campaigns at the Taquari River, a major tributary from the Alto Paraguay Basin, in the Pantanal Biome, known as the largest freshwater wetland system in the world. The correlation was assessed considering the following: (a) the equipment frequency operation mode (Smart Pulse or Fixed Frequency) and (b) by checking the influence of the sediment attenuation coefficient. Furthermore, extrapolation was conducted in filtered and unmeasured areas of the ADP to map the suspended sediment concentration over the entire cross section. Results indicate that ADP correlations can be an effective tool for estimating SSC in the Taquari River when samples cannot be collected. Correlations could be applied to past and future ADP measurements made at the location where the correlation was created, as long as similar environmental conditions are present as when the correlation was developed. The described technique can expand the amount of sediment data available at a monitoring site even with reduced traditional sampling and by leveraging instruments used for other monitoring purposes.

Automatic Analysis Method for Cause of Disqualification in Remote Test of The Primary Frequency Regulation

In this paper, the factors affecting the correct operation rate of primary frequency modulation are analyzed in the light of the primary frequency modulation test of thermal power generating set and the assessment index of primary frequency modulation of power grid. Furthermore, effective solutions and countermeasures are put forward to make the unit meet the technical requirements and performance requirements of primary frequency modulation operation under various working conditions, and meet the requirements of safe operation of power grid and production of the unit.

Performance prediction of annular linear induction pump under constant slip frequency operation

This paper predicts the performance of annular linear induction pumps (ALIPs) under constant slip frequency operation mode. Predictions are made using a two-dimensional finite element method (FEM) based model. Two pumps, one with medium gap and other of large gap, are analyzed. Effect of constant slip frequency operation on important parameters like developed pressure, input current, efficiency has been studied. Comparison with normal constant frequency fixed voltage operation of ALIP is also presented. It is observed that constant slip frequency operation leads to higher efficiencies due to lower losses. Operation at constant slip frequency makes skin depth and magnetic Reynolds number constant even when flow decreases. Using different V/f modes with constant slip frequency, the pressure-flow characteristics of ALIP can be modified to meet different load characteristics.

Development of the body power supply for ECRH on EAST

Electron cyclotron resonance heating (ECRH) plays a major role of plasma heating and it is also an important way of inhibiting plasma instability. The high frequency modulation operation of ECRH system is proposed, which is helpful for the suppression of non-classical tearing modes (NTMs). A 30kV/100mA high voltage body power supply (BPS) with 5 kHz modulation ability for 1MW/1000s Gyrotron has been developed. The BPS adopts linear power supply technology, switching power supply technology and pulse step modulation (PSM) technology. A modulation from 0 up to 100 % is possible, and the rising time is less than 20us. The output voltage ripple factor of the BPS is less than 0.5%. The test results show that the BPS can meet the requirements of ECRH system, and it has strong generality, which can provide reference for the design of other body power supply.

A Novel Space-Vector Modulation Method for Nine-Switch Converter

Nine-switch converter (NSC) has been presented as a dual-output converter with common frequency (CF) or different frequency (DF) operation modes. This paper proposes a novel space-vector modulation (SVM) method for the NSC that supports both the CF and DF modes. This method is based on the simplification of the space-vector diagram of NSC into that of six-switch converter, and the SVM method for NSC can be done like conventional SSC. The proposed voltage vector selection method without using common logical xor operation and the calculation method for dwelling times of voltage vectors are described in detail. In addition, the modulation indices for two ac terminals of NSC have been analyzed deeply, and the derived fitting equations can guide engineering application. The performance of the proposed SVM is verified by the simulation and experimental results, and the low total harmonic distortions and harmonic components for phase currents prove the effectiveness of the proposed method.

Extraction of polyphenols and antioxidants from pomegranate peel using ultrasound: influence of temperature, frequency and operation mode

SummaryThe objective of this research was to investigate the effects of temperature (40–70 °C), frequency (37 and 80 kHz) and ultrasonic operation mode (normal, pulse and sweep), and their interactions on the recovery of phenolic compounds and antioxidants present in pomegranate peel using ultrasound‐assisted extraction. The content of individual phenolic compounds, total phenolic compounds (TPC), antioxidant capacity (AC) and total extract yield (X0) were analysed. Significant effects were observed between some sources of variation in recovery of individual compounds at TPC and X0, and no significant effect was observed for AC. The process and conditions studied shown to be interesting to extract antioxidants, since a high antioxidant capacity was verified in the extracts. Temperatures around 50–60 °C, using 37 kHz frequency, and normal or pulse modes were the conditions that provided better yields of phenolic compounds and X0. Regarding AC, the best condition observed was at 70 °C, 80 kHz frequency and continuous mode.

High Scale-Factor Stability Frequency-Modulated MEMS Gyroscope: 3-Axis Sensor and Integrated Electronics Design

This paper reports the developments toward an integrated, tri-axial, frequency-modulated, consumer-grade, and microelectromechanical system (MEMS) gyroscope. A custom low-power (160 μ A), low-phase-noise integrated circuit is designed specifically for frequency-modulated operation. Both yaw- and pitch-rate sensing systems are demonstrated by coupling the circuit with two novel micromachined structures fabricated with a 24- μ m-thick industrial process. In operation, both gyroscopes show a repeatable and stable scale factor, with less than 0.55% of part-to-part variability, obtained with no any calibration, and 35 ppm/ $^{\circ }$ C of variability over a 25–70 $^{\circ }$ C temperature range.

Temporal characteristics of quantum cascade laser frequency modulated combs in long wave infrared and THz regions.

We consider here a time domain model representing the dynamics of quantum cascade lasers (QCLs) generating frequency combs (FCs) in both THz and long wave infrared (LWIR λ = 8-12µm) spectral ranges. Using common specifications for these QCLs we confirm that the free running laser enters a regime of operation yielding a pseudo-randomly frequency modulated (FM) radiation in the time domain corresponding to FCs with stable phase relations in the frequency domain. We provide an explanation for this unusual behavior as a consequence of competition for the most efficient regime of operation. Expanding the model previously developed in [Opt. Eng. 57(1), 011009 (2017)] we analyze the performance of realistic THz and LWIR QCLs and show, despite the vastly different scale of many parameters, that both types of lasers offer very similar characteristics, namely FM operation with an FM period commensurate with the gain recovery time and an FM amplitude comparable with the gain bandwidth. We also identify the true culprit behind pseudo-random dynamics of the FM comb to be spatial hole burning, rather than the more pervasive spectral hole burning.

Source detection and propagation of equal frequency voltage flicker in nonradial power system

Nowadays electric power quality problems such as flicker (voltage fluctuation) are major concerns of electric companies and industrial consumers. Identification of flicker sources is an important stage in the flicker reduction process. Flicker source can be modeled as a nonlinear load whose admittance is intermittent and time-variant. In the steady state, fluctuation of voltage amplitude is a function of the impedance of flicker sources. In this paper, after calculating the gradient of voltage amplitudes and constructing a Jacobian matrix, criteria for flicker source detection are proposed. Therefore, by measuring voltage and current of each load in the power system, the contaminative loads are identified. In the next step, flicker propagation throughout the power system is investigated. For identifying the dominant flicker source, an algorithm based on a directed graph method is proposed. For different operation modes of flicker sources, the effects of their locations on dominating are analytically interpreted. The proposed methods are tested in a typical nonradial power system in which several flicker sources have been operated. The flicker sources are operated with equal fluctuation frequency and different operation modes. Simulation results show a good performance for the single point proposed method in flicker source detection. These results confirm that the proposed algorithm can identify dominant flicker source as expected for our theory.