Excitation System Research Articles

Design and simulation of a superconducting machine excitation system taking into account the three-dimensional magnetic leakage

The optimized design of a new high-temperature superconducting rotating pole machine is presented. Its main structural feature is the use of a double stator core which separates the synchronous machine pole shoe from the pole body to rotate separately as the machine rotor, allowing the superconducting coil to operate in a stationary state. The inner stator core, the stationary dewar and the rotor core together form the excitation system of the machine. The excitation coil windings adopt a rectangular cross-section, with flux divertor strategically placed between the high-temperature superconducting coils. This configuration aims to modulate the background magnetic field, specifically reducing the perpendicular magnetic field component. This mitigation minimizes the impact of ambient magnetic fields on the superconducting coil’s current carrying capacity, ensuring an optimized magnetic field environment for its operation. Through the integration of these modifications, the technical and economic parameters of the enhanced high-temperature superconducting machine have been significantly improved. The optimization of design, coupled with detailed calculations of the 3D electromagnetic field, was achieved utilizing the commercial software Ansys EM module.

Inorganic nanoparticles promoted synthesis of oxygen-containing heterocycles

Abstract Since many of the U.S. Food and Drug Administration (FDA)-approved medications contain oxygen-containing heterocyclic molecules, they have been discovered to be quite important. Moreover, over the past 10 years, the field of reusable nanocatalysts has expanded quickly. Therefore, the development of nanotechnology has led to a wide range of applications for nanocatalysis in the synthesis of heterocyclic molecules. The domains of organic chemistry and pharmaceuticals have recently shown a great deal of interest in nanocatalyzed organic processes. Such nanocatalysts enable non-toxic, simpler, environmentally friendly, and more affordable synthetic processes that give only the most desirable compounds in higher quantities and provide simple catalyst separation. As a result of their efficient methods for separating catalysts and products, nanocatalysts were chosen over other catalysts for the synthesis of heterocyclic compounds. This review emphasized the preparation of nanocatalysts, synthetic approaches, and recycling studies of highly excited catalytic systems employed for the synthesis of oxygen-containing heterocyclic compounds.

Calculated Values of Three-phase Short-circuit Currents in the Power Supply System of the Synchronous Generator Excitation System

In this article, the calculated values of three-phase short-circuit currents in the power supply system of the excitation system of the STS type are considered-2100-250-2,5 UHL4 synchronous generator type SV-1130-220-44- UHL4.

Switching attack modeling and vulnerability analysis of generator for dynamics study

This paper presents novel insights about cyber-attacks in the power network and their consequence in terms of stability. Compared to existing cyber-attack related studies in power systems, the work discusses switching attack construction and evaluates the impact on generator dynamics. As such, the study is in two folds: (i) switching attack construction, with selection of switching instants based on system states and (ii) vulnerability analysis of power system components, circuit breaker, governor system and excitation system of generators. The role of inherently present communication delay/state variable delay becomes important as it has direct impact on dynamic performance of the system. The impact of the constant and timedependent delay on the stability is addressed by determining the time-delay margin using Lyapunov-Krasovskii functional. Thereafter, the condition for successful switching attack construction is given in terms of delay margin. The accuracy of the derived condition for successful switching attack is demonstrated via real-time co-simulation (RTDS) and MATLAB software. The vulnerability of power system components in IEEE 3-machine, 9-bus network are analysed as individuals or their combinations when subjected to switching attacks. The adequacy related to power system stability as a consequence of cyber-attacks is investigated with an estimation of RoCoF of generators.

Fuzzy system of automatic tuning of electromagnetic excitation system of vibration-frequency liquid density meter

A fuzzy system for setting the location of electromagnetic exciter of vibration-frequency density meter is presented, taking into account the possible nonlinearities of the object. This paper proposes a system and algorithm for tuning the location of electromagnetic exciter of vibration-frequency density meter using fuzzy set theory. The use of fuzzy control methods allowed us to obtain a system for tuning the location of the electromagnetic exciter of the vibration-frequency density meter without the use of cumbersome computational procedures characteristic of the classical control method.

Modeling and Operating Characteristics of Excitation System for Variable Speed Pumped Storage Unit with Full-Size Converter

The variable speed pumped storage unit with a full-size converter (FSC-VSPSU) can provide fast and flexible regulation capacity for the power grid, assisting the rapid development of the new energy-dominated power systems, and its application is gradually becoming widespread. The excitation system of FSC-VSPSU is crucial for maintaining the motor-port voltage and further supports the stable operation of the entire unit. However, there is currently no research on excitation system modeling, and their essential operating characteristics have not been discussed in detail, which needs further study. With this aim, this paper firstly establishes a detailed transfer function model for FSC-VSPSU, which is then used to study the influence rules of FSC-VSPSU parameters on the operating characteristics. In addition, based on the summarized operating characteristics, the excitation system can be optimized, and its complexity is greatly reduced while ensuring the original performance of the unit. Finally, the results of the simulation can verify the correctness of the established model and the explored operating characteristics.

Dynamic theory and experimental testing in ipsilateral offset dual-motor excitation system

This paper addresses unbalanced trajectories of dual-motor vibrating screens by proposing a dynamic theory and experimental testing. First, based on the Lagrange equation, the dynamic model of ipsilateral offset dual-motor excitation system is established. Subsequently, the steady response is worked out by solving the differential equation of motion of the vibrating body. Then, the synchronization condition and synchronization stability criterion of the system are determined employing the small parameter method and the Routh–Hurwitz criterion. Numerical analysis methods are given to reveal the relationship between structural parameters and synchronization characteristics of the vibration system. Moreover, an mechanical–electric coupling model is developed to study dynamic characteristics. The results demonstrate that synchronization condition can be described with capture torque and difference of output torque between motors. The synchronization ability is enhanced by improving installation distance of the motors. Additionally, increasing angle β or decreasing angle θ of the motors is in favor of optimization of centroid trajectory; swing oscillation of the box can be controlled by adjusting the main inclination angle of motors; in such a condition, equilibrium of motion trajectory of system is enhanced. Finally, the validity method for designing vibrating screen is verified through theoretical calculations, simulation analysis, and experiments.

Analysis of random induced dynamic response of rural roads considering friction effect and nonlocal effect under the load of construction vehicles

Abstract The objective of this paper is to propose a novel computational model for solving the problem of accurately evaluating the randomly induced road vibration response of engineering vehicles traveling on rural roads. The computational model, first, focuses on the unique pavement characteristics of rural roads, constructs a tire grounding function model and innovatively introduces a dynamic friction factor, and successfully develops a coupled stochastic excitation system model for the interaction between the dynamic loads of 1/4 vehicle tires and the pavement of rural roads by applying the power spectral density function of the rural roads and combining it with the elastic roller model of the vehicle tires. Second, considering the nonlocal superposition effect of the soil skeleton of the roadbed, a coupled vibration response model of a 1/4 automobile rural road is successfully developed, and a validation method is given. Finally, the coupled vibration response characteristics of engineering vehicles and rural roads under random excitation at different speeds are analyzed. The analysis results show that the model proposed in this paper can well predict the degree and influence the range of rural road vibration caused by random excitation of construction vehicles traveling at any speed.

Fast creation of data-driven low-order predictive cardiac tissue excitation models from recorded activation patterns

Excitable systems give rise to important phenomena such as heat waves, epidemics and cardiac arrhythmias. Understanding, forecasting and controlling such systems requires reliable mathematical representations. For cardiac tissue, computational models are commonly generated in a reaction–diffusion framework based on detailed measurements of ionic currents in dedicated single-cell experiments.Here, we show that recorded movies at the tissue-level of stochastic pacing in a single variable are sufficient to generate a mathematical model. Via exponentially weighed moving averages, we create additional state variables, and use simple polynomial regression in the augmented state space to quantify excitation wave dynamics. A spatial gradient-sensing term replaces the classical diffusion as it is more robust to noise. Our pipeline for model creation is demonstrated for an in-silico model and optical voltage mapping recordings of cultured human atrial myocytes and only takes a few minutes.Our findings have the potential for widespread generation, use and on-the-fly refinement of personalised computer models for non-linear phenomena in biology and medicine, such as predictive cardiac digital twins.

Phenomenological Model of Electrotechnical Systems Based on a Synchronous Generator With an Excitation System

Phenomenological Model of Electrotechnical Systems Based on a Synchronous Generator With an Excitation System

Design and Analysis of Inductive Power Transfer System for Electric Machine Excitation

Design and Analysis of Inductive Power Transfer System for Electric Machine Excitation

Integration of nonlinear two-photon excited fluorescence and photocatalysis boosts overall water splitting performance.

A nonlinear two-photon excited fluorescence photocatalytic system was constructed for the first time by integrating (ZnO)1-x(GaN)x photocatalyst and a fluorescence solution of phenanthridine derivatives. This work offers a strategy for increasing the photocatalytic solar spectral utilization rate and boosting the expectation for photocatalytic solar-to-hydrogen efficiencies.

Mineral oil emulsion species and concentration prediction using multi-output neural network based on fluorescence spectra in the solar-blind UV band.

The accurate monitoring of oil spills is crucial for effective oil spill recovery, volume determination, and cleanup. Oil slicks become emulsified under the effects of wind and waves, which increases the consistency of the oil spills. This phenomenon makes oil spills more challenging to handle and exacerbates environmental pollution. In this study, the variation of the solar-blind ultraviolet (UV) fluorescence spectra obtained from simulated oil spills with different oil types and oil-water ratios was investigated. By designing and constructing a multi-angle excitation and detection system, an apparent fluorescence peak of the oil emulsions was observed at around 290 nm under 220 nm excitation. By utilizing competitive adaptive reweighted sampling (CARS) and multi-output neural network algorithms, both the types and concentrations of the emulsified oils were obtained simultaneously. The classification accuracy for identifying the oil type exceeds 98%, and the mean absolute percentage error (MAPE) for concentration regression is around 2%. The results indicate that active solar-blind UV fluorescence could become a supplementary method for on-site oil spill detection to achieve comprehensive monitoring of oil spills. This study provides potential applications for UV-induced fluorescence spectrometry in oil spill on-site monitoring during the daytime.

Bispectral analysis and simulation modeling of quadratic nonlinear system with specific turbulent-fluctuation-excitation-response types

There exists a kind of quadratic nonlinear system with specific type of turbulent fluctuation excitation in nature, which belongs to a special non-Gaussian input signal system. Its characteristic is that the input signal spectrum is generated by turbulent fluctuations, and the power spectrum distribution of this turbulence fluctuation signal is close to Gaussian distribution. Starting with the work of Choi et al. (<ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://doi.org/10.1016/0022-460X(85)90370-0">1985 <i>J. Sound Vib</i><i>.</i> <b>99</b> 309</ext-link>) and Kim et al. [<ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://ieeexplore.ieee.org/document/1145286">1987 <i>IEEE J. Ocean. Eng.</i> <b>OE-12</b> 568</ext-link>), we extend the simulation of a specific turbulent fluctuation excited response-type quadratic nonlinear system represented by the wave excited mooring ship response, and fully develop the internal development of turbulence based on bispectral analysis technology. We also extend the simulation system and conduct systematic modeling analysis. The complete iterative method [<ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://doi.org/10.1088/1402-4896/ab725f">2020 <i>Phys. Scr.</i> <b>95</b> 055202</ext-link>] is used to solve the model, and calculate the linear transfer function and quadratic nonlinear transfer function. The comparison of simulation and modeling results with the real systems and their models confirms the correctness of the results from system simulation, system modeling, and model solving. The results obtained are all in line with expectations. The coherence analysis shows that the quadratic coherence of the random wave-ship swaying system is much greater than the linear coherence, but the linear coherence of the fully developed turbulence is greater for the near Gaussian input type. The reverse computation verification or comparison with real systems indicates that the turbulence simulation and system modeling method in this work have good accuracy and high efficiency in solving algorithms, and the research results can be effectively applied to the model description and system analysis of the quadratic nonlinear systems related to specific turbulent fluctuation excitation response.

Design and Test of High-Low Voltage Excitation System for HTS Synchronous Condenser

Design and Test of High-Low Voltage Excitation System for HTS Synchronous Condenser

Real‐Time Live Imaging of Osteoclast Activation via Cathepsin K Activity in Bone Diseases

AbstractIntravital fluorescence imaging of functional osteoclasts within their intact disease context provides valuable insights into the intricate biology at the microscopic level, facilitating the development of therapeutic approaches for osteoclast‐associated bone diseases. However, there is a lack of studies investigating osteoclast activity within deep‐seated bone lesions using appropriate fluorescent probes, despite the advantages offered by the multi‐photon excitation system in enhancing deep tissue imaging resolution. In this study, we report on the intravital tracking of osteoclast activity in three distinct murine bone disease models. We utilized a cathepsin K (CatK)‐responsive two‐photon fluorogenic probe (CatKP1), which exhibited a notable fluorescence turn‐on response in the presence of active CatK. By utilizing CatKP1, we successfully monitored a significant increase in osteoclast activity in hindlimb long bones and its attenuation through pharmacological intervention without sacrificing mice. Thus, our findings highlight the efficacy of CatKP1 as a valuable tool for unraveling pathological osteoclast behavior and exploring novel therapeutic strategies.

Real‐time implementation for vulnerability of power components under switching attack based on sliding mode

AbstractIn recent years, cyber security‐related studies in the power grid have drawn wide attention, with much focus on its detection, mainly for data injection type of attacks. The vulnerability of power components as a result of attack and their impact on generator dynamics have been largely ignored so far. With the aim of addressing some of these issues, the authors propose a novel approach using real‐time sliding surface‐based switching attack (SA) construction. This approach targets the circuit breaker, excitation system, and governor system of the generator. The vulnerability of these power components to cyber‐physical attacks and assessment of their potential impact on the stability of generator are discussed. The study is presented to show the progression of cascading generator dynamics on account of single or multiple time instants of SA launched on these power components. The results are discussed according to criteria in terms of deviations in rotor speed of the generator and identify some of possible combinations of power components that are most critical to grid stability. The proposed study is implemented on standard IEEE 3‐machine, 9‐bus network in real‐time digital simulator via transmission control protocol/internet protocol (TCP/IP) communication network established as cyber‐physical system. The sliding surface‐based SA algorithm developed in MATLAB is launched from another computer.

Real-Time Live Imaging of Osteoclast Activation via Cathepsin K Activity in Bone Diseases.

Intravital fluorescence imaging of functional osteoclasts within their intact disease context provides valuable insights into the intricate biology at the microscopic level, facilitating the development of therapeutic approaches for osteoclast-associated bone diseases. However, there is a lack of studies investigating osteoclast activity within deep-seated bone lesions using appropriate fluorescent probes, despite the advantages offered by the multi-photon excitation system in enhancing deep tissue imaging resolution. In this study, we report on the intravital tracking of osteoclast activity in three distinct murine bone disease models. We utilized a cathepsin K (CatK)-responsive two-photon fluorogenic probe (CatKP1), which exhibited a notable fluorescence turn-on response in the presence of active CatK. By utilizing CatKP1, we successfully monitored a significant increase in osteoclast activity in hindlimb long bones and its attenuation through pharmacological intervention without sacrificing mice. Thus, our findings highlight the efficacy of CatKP1 as a valuable tool for unraveling pathological osteoclast behavior and exploring novel therapeutic strategies.

Friction Saturated Limit Cycle Oscillations—Test Rig Design and Validation of Numerical Prediction Methods

Abstract In this paper, an experimental test rig for friction saturated limit cycle oscillations is proposed to provide a validation basis for corresponding numerical methods. Having in mind the application of turbine blades, an instrumented beam-like structure equipped with an adjustable velocity feedback loop and dry frictional contacts is designed and investigated. After dimensioning the test rig by means of a simplified one-dimensional beam model and time domain simulations, the specific requirements of limit cycle oscillations for the design of the frictional contact, the velocity feedback loop and the excitation system are discussed and possible solutions are presented. Also appropriate measuring principles and evaluation techniques are assessed. After commissioning of the test rig, the influence of the negative damping and the normal contact force on the limit cycle oscillations is measured and the practical stability is investigated. The test rig shows linear dynamics for sticking contact and highly repeatable limit cycles. The measured results are discussed regarding the consistency with theory and compared to the predictions of a three dimensional reduced order model solved in frequency domain by the harmonic balance solver OrAgL. It is demonstrated that the numerical modeling strategy is able to accurately reproduce the measured limit cycle oscillations, which stabilized for different contact normal forces and self-excitation levels.

High-power system for acoustic excitation of plates

"This paper introduces a device dedicated to acoustic excitation for modal analysis of plates. A particular setup is requested since the system should produce acoustic excitation with high power in the 10…120 Hz frequency range. The system comprises a signal generator, an amplifier powered by a car starter or a battery, and a subwoofer. This system permits setting the generated frequency around the resonance frequency with reasonable frequency and amplitude stability. We present the system’s design and test its performance on a rectangular plate. In our laboratory experiments, we achieved the desired structural behavior. Keywords: modal analysis, acoustic excitation, subwoofer, frequency estimation."