Dynamic Circuit Research Articles

Calculation method of external fault short-circuit current for variable-speed pumped storage units based on time-domain dynamic circuit

The calculation method of the external fault short-circuit current of large units with clear mechanisms and practicality is of great value in engineering practice. Due to the special AC excitation structure and control mode, the external fault short-circuit characteristics of variable-speed pumped storage units (VSPSUs) are very different from those of conventional units. Therefore, this paper proposes a calculation method for external fault short-circuit current based on a time-domain dynamic circuit. According to the excitation and control characteristics of VSPSUs under external fault, the VSPSU under external fault is divided into two cases: continuous excitation and jumper action. Based on space vector analysis, the time-domain dynamic circuit models are established, respectively. On this basis, the analytical formula of the external fault short-circuit current of VSPSUs is derived by combining the transition boundary conditions of the two cases and the dynamic characteristics of the stator flux linkage. Finally, the comparison with PSCAD/EMTDC simulation results shows that the proposed VSPSUs’ external fault short-circuit current calculation method has high accuracy and practical value, which can meet the needs of primary equipment selection and relay protection of variable-speed pumped storage power plants.

Aturan Cramer Berbantuan Excel pada Materi Rangkaian Listrik Searah Dua Loop untuk Mengukur Kemampuan Berpikir Komputasi Peserta Didik

Computational thinking is one of the abilities needed in the 21st century. One of the subjects that requires this ability is physics. One material that is considered difficult is dynamic electrical circuits. The aim of this research is to measure students' computational thinking abilities in solving two-loop electrical circuit problems using Cramer's rules with the help of Microsoft Excel. This research method is included in qualitative descriptive research with a research sample of 10 class XII students at a high school in Banyuwangi. The data collection technique is in the form of student test results in the form of essay questions or descriptions where each question refers to an indicator of computational thinking. The research results showed that 6 people were in the good category for problem decomposition indicators, 8 people were pattern recognition indicators, 7 people were indicators of algorithmic thinking, and 6 people were indicators of abstraction and generalization

Real-Time Machine Learning for Multi-User Massive MIMO: Symbol Detection Using Multi-Mode StructNet

In this paper, we develop a learning-based symbol detection algorithm for massive MIMO-OFDM systems. To exploit the structure information inherited in the received signals from massive antenna array, multi-mode reservoir computing is adopted as the building block to facilitate over-the-air training in time domain. In addition, alternating recursive least square optimization method, and decision feedback mechanism are utilized in our algorithm to achieve the real-time learning capability. That is, the neural network is trained purely online with its weights updated on an OFDM symbol basis to promptly and adaptively track the dynamic environment. Furthermore, an online learning-based module is devised to compensate the nonlinear distortion caused by RF circuit components. On top of that, a learning-efficient classifier named StructNet is introduced in frequency domain to further improve the symbol detection performance by utilizing the QAM constellation structural pattern. Evaluation results demonstrate that our algorithm achieves substantial gain over traditional model-based approach and state-of-the-art learning-based techniques under dynamic channel environment and RF circuit nonlinear distortion. Moreover, empirical result reveals our NN model is robust to training label error, which benefits the decision feedback mechanism.

Analytical calculation method of a liquid-cooling eddy current brake considering magnetic saturation and skin effect

In this article, a clear and concise analytical method for predicting the performance of a Liquid-cooling eddy current brake (LC-ECB) is proposed. The LC-ECB has a coolant channel in the rotor to allow direct cooling of the inner surface of the stator. The static air-gap magnetic field distribution is obtained by the dynamic magnetic equivalent circuit (MEC) method, and the magnetic flux leakage and global magnetic saturation effects are fully considered. The magnetic field intensity distribution function of the eddy current reaction magnetic field is derived for the first time based on Ampere circuital theorem. Considering the local magnetic saturation and skin effect, a novel double-iteration algorithm based on the conservation principle of magnetic pressure drop is applied to obtain the transient air-gap flux density distribution, and then the brake torque expression is obtained. The finite element method (FEM) and experimental results show that the proposed method is feasible and effective. The new model is easy to program and can be easily used in the initial design and optimization of LC-ECB.

An Active Power Dynamic Oscillation Damping Method for the Grid-Forming Virtual Synchronous Generator Based on Energy Reshaping Mechanism

The grid-forming virtual synchronous generator (GFVSG) with large virtual inertia can provide a friendly grid-connected operational mode for power electronic converters, but it may also introduce the active power dynamic oscillation problems similar to traditional synchronous generators. In view of this, the dynamic equivalent circuit model of the GFVSG grid-tied active power-angle is established firstly, and, then, the understanding of the GFVSG active power oscillations under variable disturbances is revealed from the perspective of circuit energy flow in this paper. On this basis, an active power dynamic oscillation damping method based on an energy reshaping mechanism for the GFVSG is proposed, and a parameter design method using the second-order equivalent reduced-order control model is given. The MATLAB 2016a simulation as well as experimental test platforms of a 100 kV·A GFVSG grid-connected system are established, then, both the feasibility and effectiveness of the proposed active power dynamic oscillation damping method are verified by using the simulation and experimental comparison results.

DC operating points of Mott neuristor circuits

In 1960 Hewitt Crane conceptualized neuristors as electronic logic networks that could mimic action potential generation by biological neurons. In 2012 Mott memristors were presented as nano-scale electronic devices for physically constructing neuristor networks. Both the original Mott memristor model and the simplified model presented in 2020 are stiff nonlinear first-order ordinary differential equations (ODEs) that describe the voltage controlled threshold switching and current controlled negative differential resistance, attributed to a Mott insulator-to-metal phase transition. By design, a Mott neuristor contains two identical Mott memristors plus linear resistors and capacitors (no inductors), which enables alternating threshold switching by the memristors to generate periodic (AC) output voltage spikes in response to a DC current or voltage input. This paper presents a steady-state analysis of dynamic neuristor models, including four-, five-, and six-state variables (each of which is a system of first-order ODEs involving the states) based on the original phenomenological model of the Mott memristor. Specifically, it reveals the unique stable operating points that occur for applied currents or voltages below the amounts needed to induce resistive switching. These DC operating points represent the physically meaningful “OFF” states for the circuit when the neuristor does not output voltage spikes. Jacques Hadamard's mathematical criteria for a well-posed physical model (existence, uniqueness, continuity, stability) motivated the search for these DC operating points (OFF states), which are needed for efficiently initializing neuristor models before conducting dynamic neuristor simulations. The key result of our analysis is the neuristor steady-state eq. (29) which is useful for understanding neuristor OFF states as well as the role of negative-differential resistance (NDR) in the operation of the Mott memristor model and neuristor circuits. In addition to the steady-state analysis, three numerical examples of dynamic neuristor circuit operation are also given and MATLAB code for the dynamic four-state model is available for interested readers.

Dynamic Electrical Circuit Modeling of a Proton Exchange Membrane Electrolyzer for Frequency Stability, Resiliency, and Sensitivity Analysis in a Power Grid

Dynamic Electrical Circuit Modeling of a Proton Exchange Membrane Electrolyzer for Frequency Stability, Resiliency, and Sensitivity Analysis in a Power Grid

Construction of cascade circuits for dynamic temporal regulation and its application to PHB production

BackgroundTo maximize the production capacity and yield of microbial cell factories, metabolic pathways are generally modified with dynamic regulatory strategies, which can effectively solve the problems of low biological yield, growth retardation and metabolic imbalance. However, the strategy of dynamic regulating multiple genes in different time and order is still not effectively solved. Based on the quorum-sensing (QS) system and the principle of cascade regulation, we studied the sequence and time interval of gene expression in metabolic pathways.ResultsWe designed and constructed a self-induced dynamic temporal regulatory cascade circuit in Escherichia coli using the QS system and dual regulatory protein cascade and found that the time intervals of the cascade circuits based on the Tra, Las system and the Lux, Tra system reached 200 min and 150 min, respectively. Furthermore, a dynamic temporal regulatory cascade circuit library with time intervals ranging from 110 to 310 min was obtained based on this circuit using promoter engineering and ribosome binding site replacement, which can provide more selective synthetic biology universal components for metabolic applications. Finally, poly-β-hydroxybutyric acid (PHB) production was taken as an example to demonstrate the performance of the cascade circuit library. The content of PHB increased 1.5-fold. Moreover, circuits with different time intervals and different expression orders were found to have different potentials for application in PHB production, and the preferred time-interval circuit strain C2-max was identified by screening.ConclusionsThe self-induced dynamic temporal regulation cascade circuit library can enable the expression of target genes with sequential changes at different times, effectively solving the balance problem between cell growth and product synthesis in two-stage fermentation and expanding the application of dynamic regulatory strategies in the field of metabolic engineering.

Reprogramming of cis-regulatory networks during skeletal muscle atrophy in male mice

A comprehensive atlas of cis-regulatory elements and their dynamic activity is necessary to understand the transcriptional basis of cellular structure maintenance, metabolism, and responses to the environment. Here we show, using matched single-nucleus chromatin accessibility and RNA-sequencing from juvenile male C57BL6 mice, an atlas of accessible chromatin regions in both normal and denervated skeletal muscles. We identified cell-type-specific cis-regulatory networks, highlighting the dynamic regulatory circuits mediating transitions between myonuclear types. Through comparison of normal and perturbed muscle, we delineated the reprogramming of cis-regulatory networks in response to denervation, described the interplay of promoters/enhancers and target genes. We further unveil a hierarchical structure of transcription factors that delineate a regulatory network in atrophic muscle, identifying ELK4 as a key atrophy-related transcription factor that instigates muscle atrophy through TGF-β1 regulation. This study furnishes a rich genomic resource, essential for decoding the regulatory dynamics of skeletal muscle in both physiological and pathological states.

Design and analysis of a microminiature omnidirectional wave energy-harvesting device based on a spatial slider–crank mechanism

Energy-harvesting devices using wave energy and ocean current energy can provide higher endurance and operation capacity for small floating or mobile equipment in offshore operations. In this paper, a microminiature omnidirectional wave energy-harvesting device based on a spatial slider–crank mechanism was designed for equipment whose length is less than ordinary ocean wavelength. It can harvest the ocean wave energy from the omnidirectional swing of the buoy and convert the reciprocating swing motion of the buoy into the unidirectional rotation motion of the generator to improve the energy conversion efficiency. The dynamic model and equivalent circuit model of the energy-harvesting device were established by the Lagrangian method and circuit-based analysis method, respectively. The model was simulated, and the effects of parameters such as crank length, wave period, etc. were investigated. The results showed that the device has good energy-harvesting performances, especially in medium and low sea conditions. In addition, the performance of the device can be improved by adjusting the length of the crank and rod.

Analysis on Rotor Vibration Characteristics under Dynamic Rotor Interturn Short Circuit Fault in Synchronous Generators

A dynamic rotor interturn short circuit fault may occur during synchronous generator operation. However, there is no method to analyze the generator’s characteristics under the dynamic rotor interturn short circuit fault and identify the fault. In order to solve this problem, a new dynamic rotor interturn short circuit fault analysis model is creatively proposed through mathematical derivation. Firstly, the rotor vibration characteristics and the mechanical response under magnetic pull excitation are theoretically analyzed. In addition, a finite element modeling method for the dynamic rotor interturn short circuit fault is proposed, and an experimental device is designed. The model of a synchronous generator under the dynamic rotor interturn short circuit fault is established to obtain the rotor’s unbalanced magnetic pulls and mechanical responses by finite element calculation. Finally, the rotor vibrations are tested on a CS-5 prototype generator. The validity of the model is verified by finite element calculation and an experiment. This paper provides theoretical support for the diagnosis of a synchronous generator’s dynamic rotor interturn short circuit fault.

Development of in vitro cardiovascular tissue models within capillary circuit microfluidic devices fabricated with 3D stereolithography printing

This study presents the development and morphology analysis of bioinspired 3D cardiovascular tissue models cultured within a dynamic capillary circuit microfluidic device. This study is significant because our in vitro 3D cardiovascular tissue models retained within a capillary circuit microfluidic device provide a less expensive, more controlled, and reproducible platform for more physiologically-relevant evaluation of cellular response to microenvironmental stimuli. The overall aim of our study is to demonstrate our cardiovascular tissue model (CTM) and vascular tissue model (VTM) actively changed their cellular morphology and exhibited structural reorganization in response to biophysical stimuli provided by microposts within the device tissue culture chambers during a 5-day period. The microfluidic device in this study was designed with the Young–Laplace and Navier–Stokes principles of capillary driven fluid flow and fabricated with 3D stereolithography (SLA) printing. The cardiac tissue model and vascular tissue model presented in this study were developed by encapsulating AC16 cardiomyocytes (CTM) and Human umbilical vein endothelial cells (VTM) in a fibrin hydrogel which were subsequently loaded into a capillary circuit microfluidic device. The cardiovascular tissue models were analyzed with fluorescent microscopy for morphological differences, average tube length, and cell orientation. We determined the VTM displayed capillary-like tube formation and the cells within both cardiovascular tissue models continued to elongate around microposts by day-5 which indicates the microfluidic system provided biophysical cues to guide cell structure and direction-specific organization.

Hierarchical quantum circuit representations for neural architecture search

Quantum circuit algorithms often require architectural design choices analogous to those made in constructing neural and tensor networks. These tend to be hierarchical, modular and exhibit repeating patterns. Neural Architecture Search (NAS) attempts to automate neural network design through learning network architecture and achieves state-of-the-art performance. We propose a framework for representing quantum circuit architectures using techniques from NAS, which enables search space design and architecture search. We use this framework to justify the importance of circuit architecture in quantum machine learning by generating a family of Quantum Convolutional Neural Networks (QCNNs) and evaluating them on a music genre classification dataset, GTZAN. Furthermore, we employ a genetic algorithm to perform Quantum Phase Recognition (QPR) as an example of architecture search with our representation. Finally, we implement the framework as an open-source Python package to enable dynamic circuit creation and facilitate circuit search space design for NAS.

Front Cover: Enzyme‐Free Nucleic Acid Circuits for Fold‐Change Detection (ChemPlusChem 9/2023)

The cover picture shows an enzyme-free nucleic acid synthetic circuit constructed by the toehold-mediated DNA strand displacement reaction, where a fold-change input (top left) elicits a similar response (bottom right). This work is anticipated to shed new light on the design of DNA dynamic circuits. More information can be found in the Research Article by Hao Pei, Tong Zhu, and co-workers.

Nontraditional Design of Dynamic Logics Using FDSOI for Ultra-Efficient Computing

In this paper, we propose a non-traditional design of dynamic logic circuits using Fully-Depleted Silicon on Insulator (FDSOI) FETs. FDSOI FET allows the threshold voltage ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V_t</i> ) to be adjustable (i.e., low-Vt and high-Vt states) by using the back gate bias. Our design utilizes the front and back gates of an FDSOI FET as the input terminals and proposes the dynamic logic gates (like; NAND, NOR, AND, OR, XOR, and XNOR) and circuits (like; half adder and full adder). It requires fewer transistors to build dynamic logic gates and achieves high performance with low power dissipation compared to conventional dynamic logic designs. The compact industrial model of FDSOI FET (BSIM-IMG) has been used to simulate dynamic logic gates and is fully calibrated to reproduce the 14nm FDSOI FET technology node data. Calibration is performed for both electrical characteristics and process variations. The simulation results show an average improvement in transistor count, propagation delay, power, and power-delay product of 23.43%, 57.16%, 47.05%, and 77.29%, respectively, compared to the conventional designs. Further, our design reduces the charge sharing effect, which affects the drivability of the dynamic logic gates. In addition, we have analyzed the impact of the process, supply voltage, and load capacitance variations on the propagation delay of the dynamic logic family in detail. The results show that these variations have a minor impact on the propagation delay of the proposed FDSOI-based dynamic logic gates compared to the conventional dynamic logic gates.

A Compact Bandwidth and Frequency-Range Reconfigurable CM Filter Using Varactor-Loaded Dual-Slot-Based Defected Ground Structure

A reconfigurable common-mode (CM) filter with a wide tunable bandwidth and frequency-range is proposed in this article. The filter adopts four compact dual-slot-based defected ground structure (DGS) cells to achieve a wide suppression of CM noise. To simplify the design, only one varactor and one dc-blocking capacitance are loaded on one DGS cell directly, which retains the original structure of the DGS cell. A wide continuously adjustable frequency range and bandwidth can be achieved when different voltages are applied to different varactors. A dynamic equivalent circuit model is built to explain the filter's working principle, which is helpful to obtain the filtering characteristics under different varactor parameters quickly and accurately. In order to verify the feasibility of the scheme, a DGS-based filter with an area of 19 mm × 9.2 mm is implemented under the microstrip line. The simulated results show the filter can achieve a continuously tunable CM suppression of frequency range from 1.9 to 7.3 GHz, and a tunable bandwidth using different voltage supplies. Good agreement between full-wave simulation and measured results is observed.

In Situ Measurement of Dynamic Internal Short Circuit Resistance during Nail Penetration of Lithium-Ion Cells and its Implications on Cell Robustness and Abuse Tolerance

Here we report a method for in situ measurement of internal short circuit (ISC) resistance during nail penetration testing of lithium-ion cells. The method is demonstrated with dry cells, wet dummy cells, and working cells using a small nail and slow penetration speed. ISC current and ISC temperature are also measured during the tests. It is confirmed that the ISC resistance changes dramatically, by several orders of magnitude, during nail penetration. More importantly, it is found that the stable resistance after full penetration is much higher than the lowest dynamic resistance at earlier stages of nail penetration. Analysis based on such a stable ISC resistance would underestimate the risk of thermal runaway during nail penetration tests. It is also found that ISC in some cases may be mitigated due to melting or rupture of aluminum foil surrounding the nail, implying a mechanism that may be able to be used towards the design of more robust/abuse tolerant Li-ion cells. Lastly, it is found that nail penetration using a larger nail reduces ISC resistance during penetration of cells but the general behaviors of ISC resistance are similar to those during smaller nail penetration.

Design and analysis of asymmetrical low-k source side spacer halo doped nanowire metal oxide semiconductor field effect transistor

In this paper, we propose a low-k source side asymmetrical spacer halo-doped nanowire metal oxide semiconductor field effect transistor (MOSFET) design and analysis. High-k spacer materials are now being researched extensively for improving electrostatic control and suppressing short-channel effects in nanoscaled electronics. However, the high-k spacers' excessive increase in fringe capacitance degrades the dynamic circuit performance. Surprisingly, this approach achieves a significant reduction in gate capacitance by maximizing the use of high-k spacer material. Three different structures, symmetrical dual-k spacer, low-k drain side asymmetrical spacer, low-k source side asymmetrical spacer halo doped nanowire MOSFET architectures are simulated and among them low-k source side asymmetrical spacer halo doped nanowire MOSFET architecture giving lower gate capacitance. After doing 3D simulations in Silvaco technology computer-aided design (TCAD) we observed that the gate capacitance and intrinsic delay are 1.23x10&lt;sup&gt;-17&lt;/sup&gt; farads and 1.11x10&lt;sup&gt;-12&lt;/sup&gt; seconds respectively for low-k source side asymmetrical spacer architecture and these are less as compared to high-k spacer architecture. So, the proposed structure is highly recommended for digital applications.

Electrical Circuits Simulator in Null-Flux Electrodynamic Suspension Analysis

This paper employed an electrical circuit simulator to investigate an electrodynamic suspension system (EDS) for passenger rail transport applications. Focusing on a null-flux suspension system utilizing figure-eight-shaped coils (8-shaped coils), the aim was to characterize the three primary electromagnetic forces generated in an EDS and to compare the findings with existing literatures. The dynamic circuit theory (DCT) approach was utilized to model the system as an electrical circuit with lumped parameters, and mutual inductance values between the superconducting (SC) coil and the upper and lower loops of the 8-shaped coil were calculated and inputted into the simulator. The results were compared with experimental data obtained from the Yamanashi test track. The comparison demonstrated close alignment between the theoretical expectations and the obtained experimental curves, validating the accuracy of the proposed model. The study highlights the advantages of this new approach, including faster computation times and efficient implementation of modifications. Overall, this work contributes to the ongoing development and optimization of null-flux suspension Maglev systems.

Simulator for personnel of Yumaguzinskaya HPP

During the operation of hydroelectric power plants, issues arise of improving the skills of hydroelectric power plant personnel, which can be ensured by the introduction of simulators for targeted training of personnel to work both in normal operating conditions and in pre-emergency and emergency situations as close as possible to real ones. It should be noted that the developers of simulators in the Russian energy sector peviously focused on the creation of simulators for thermal power plants, leaving hydroelectric power plants overshadowed. To date, TEST JSC has developed and implemented simulators for Irkutskaya, Bratskaya, Ust-Ilimskaya, Krasnoyarskaya, Ondskaya, Pavlovskaya and Yumaguzinskaya HPPs. This paper discusses the development for the Yumaguzinskaya HPP: a simulator with dynamic computer-aided mnemonic circuits of hydraulic units and electrical circuits of one of the Russian hydroelectric power plants, which will arouse interest among readers of the journal and potential customers. The article describes the prototype facility, the composition of the simulator, which includes a model of the facility and operating modes, a model of the control system, a model of the protection system, a model of locks, a model of emergency and warning alarms, describes in detail the educational and methodological support of the simulator complex, including models of training scenarios, an introductory model, a monitoring program, protocols and instructions. The organization of effective simulator training of operational and maintenance personnel on the simulator for operational switching of the Yumaguzinskaya HPP is achieved through the implementation in the simulator of the following main simulated subsystems: trainee's workplace model, instructor's workplace model, control object model, control system model, training system model. The hydroelectric power plant simulator presented in the paper is versatile and can find practical application both as a tool for training and examination of knowledge of operational personnel, and as a means for conducting occupational skills contests.