Transient Response Research Articles

Wiener Chaos Random Fourier Series as a Tool to Study the Coupling of Noise With Power System Transient Response

Wiener Chaos Random Fourier Series as a Tool to Study the Coupling of Noise With Power System Transient Response

Transient Response of an Unsaturated Single-Layer Seabed Subjected to a Vertical Compressional Wave

Transient Response of an Unsaturated Single-Layer Seabed Subjected to a Vertical Compressional Wave

Design of 300nA quiescent current and 300mA load capacity LDO with fast transient response

Design of 300nA quiescent current and 300mA load capacity LDO with fast transient response

Investigation on transient response of gas face seals based on a double mass kinematic model considering Coulomb friction

Investigation on transient response of gas face seals based on a double mass kinematic model considering Coulomb friction

A dSPACE-based implementation of ANFIS and predictive current control for a single phase boost power factor corrector

This paper presents an innovative control scheme designed to significantly enhance the power factor of AC/DC boost rectifiers by integrating an adaptive neuro-fuzzy inference system (ANFIS) with predictive current control. The innovative control strategy addresses key challenges in power quality and energy efficiency, demonstrating exceptional performance under diverse operating conditions. Through rigorous simulation, the proposed system achieves precise input current shaping, resulting in a remarkably low total harmonic distortion (THD) of 3.5%, which is well below the IEEE-519 standard threshold of 5%. Moreover, the power factor reaches an outstanding 0.990, indicating highly efficient energy utilization and near-unity power factor operation. To validate the theoretical findings, a 500 W laboratory prototype was implemented using the dSPACE ds1104 digital controller. Steady-state analysis reveals sinusoidal input currents with minimal THD and a power factor approaching unity, thereby enhancing grid stability and energy efficiency. Transient response tests further demonstrate the system’s robustness against load and voltage fluctuations, maintaining output voltage stability within an 18 V overshoot and a 20 V undershoot during load changes, and achieving rapid response times as low as 0.2 s. Comparative evaluations against conventional methods underscore the superiority of the proposed control strategy in terms of both performance and implementation simplicity. By harnessing the strengths of ANFIS-based voltage regulation and predictive current control, this scheme offers a robust solution to power quality issues in AC/DC boost rectifiers, promising substantial energy savings and improved grid stability. The results affirm the potential of the proposed system to set new benchmarks in power factor correction technology.

Annealing temperature-dependent induced supramolecular chiroptical response of copolymer thin films studied by pump-modulated transient circular dichroism spectroscopy

Copolymer thin films showing induced supramolecular chirality are of considerable interest for optoelectronic applications such as organic light-emitting diodes. Here, we introduce a new helicene-like chiral additive with two octyloxy substituents which displays excellent chiral induction properties in an achiral polyfluorene copolymer, leading to a circular dichroism (CD) response of up to 10,000 mdeg. This chiral inducer also displays very good thermal stability, which enables us to perform an extended study on the induced chiroptical properties of the cholesteric copolymer thin films annealed at different temperatures in the range 140–260 °C. Starting from about 180 °C, a distinct change in the morphology of the CD-active film is observed by CD microscopy, from micrometre-size granular to extended CD-active regions, where the latter ones display skewed distributions of the dissymmetry parameter gabs. Broadband Müller matrix spectroscopy finds a pronounced CD and circular birefringence (CB) response and only weak linear dichroism (LD, LD’) and linear birefringence (LB, LB’). Ultrafast transient CD spectroscopy with randomly polarised excitation reveals a clean mirror-image-type transient response, which shows a second-order decay of the S1 population due to singlet–singlet annihilation processes.

Genome-wide profiling of WRKY genes involved in flavonoid biosynthesis in Erigeron breviscapus.

The transcription factors of WRKY genes play essential roles in plant growth, stress responses, and metabolite biosynthesis. Erigeron breviscapus, a traditional Chinese herb, is abundant in flavonoids and has been used for centuries to treat cardiovascular and cerebrovascular diseases. However, the WRKY transcription factors that regulate flavonoid biosynthesis in E. breviscapus remain unknown. In this study, a total of 75 EbWRKY transcription factors were predicted through comprehensive genome-wide characterization of E. breviscapus and the chromosomal localization of each EbWRKY gene was investigated. RNA sequencing revealed transient responses of 74 predicted EbWRKY genes to exogenous abscisic acid (ABA), salicylic acid (SA), and gibberellin 3 (GA3) after 4h of treatment. In contrast, the expression of key structural genes involved in flavonoid biosynthesis increased after 4h in GA3 treatment. However, the content of flavonoid metabolites in leaves significantly increased at 12h. The qRT-PCR results showed that the expression patterns of EbWRKY11, EbWRKY30, EbWRKY31, EbWRKY36, and EbWRKY44 transcription factors exhibited a high degree of similarity to the 11 structural genes involved in flavonoid biosynthesis. Protein-DNA interactions were performed between the key genes involved in scutellarin biosynthesis and candidate WRKYs. The result showed that F7GAT interacts with EbWRKY11, EbWRKY36, and EbWRKY44, while EbF6H has a self-activation function. This study provides comprehensive information on the regulatory control network of flavonoid accumulation mechanisms, offering valuable insights for breeding E. breviscapus varieties with enhanced scutellarin content.

Design of a high-speed MCML D-Latch at 0.6 V in 45 nm CMOS technology

Metal oxide semiconductor (MOS) current mode logic (MCML) is generally preferred for high-speed circuit design. In this paper, a novel low voltage folded (LVF) MCML D-Latch is designed. The existing topologies of the MCML D-Latch consume more power and operate at 1 V. The proposed D-Latch can operate at 0.6V with better delay and power management. MCML circuits minimize delay and perform fast operations, hence it can be used in high-frequency applications. The proposed LVF MCML D–Latch is analyzed with the parameters such as power, delay, power delay product and output noise using cadence virtuoso in 45 nm complementary metal oxide semiconductor (CMOS) technology at a voltage of 0.6 V and a temperature of 27 °C. The proposed technique achieves 62.11% of power reduction, transient response speed improved by 51.23% and noise cancellation becomes 26.13% improvement over the existing circuit. It also achieves 96% of output swing which is more efficient compared to others. Finally, the parametric analysis is performed with different temperatures to verify the stability of the proposed circuit. From the simulated results, it is clear that the proposed LVF MCML D-Latch provides better performance in high-speed phase locked loop (PLL) applications.

Upgrading the dynamic mathematical model of temperature sensors in gaseous media for low Biot number (Bi < 0.1)

A mathematical model incorporating the transient response of NTC thermistors is presented. The internal thermal conduction resistance of the sensor relative to the thermal convection resistance of the medium results in a low Biot number Bi<0.1, yielding a fast dynamic response in gaseous media. This is advantageous in applications requiring minimal fluid interaction. However, negligible energy exchanges occur, introducing measurement uncertainty and ignoring the behavior of the measuring instrument. Therefore, this work proposes an improvement strategy for the mathematical model of these sensors, complementing the conventional model based on the concept of time constant. The strategy considers the heat flow through the thermistor wires in the energy balance, assuming they are semi-infinite solids and applying an approximation to the heat flow formula. Satisfactory improvement results were obtained compared to the conventional model, based on controlled laboratory tests with various gases.

Enhancing photovoltaic system maximum power point tracking with fuzzy logic-based perturb and observe method

Photovoltaic systems have emerged as a promising energy resource that caters to the future needs of society, owing to their renewable, inexhaustible, and cost-free nature. The power output of these systems relies on solar cell radiation and temperature. In order to mitigate the dependence on atmospheric conditions and enhance power tracking, a conventional approach has been improved by integrating various methods. To optimize the generation of electricity from solar systems, the maximum power point tracking (MPPT) technique is employed. To overcome limitations such as steady-state voltage oscillations and improve transient response, two traditional MPPT methods, namely fuzzy logic controller (FLC) and perturb and observe (P&amp;amp;O), have been modified. This research paper aims to simulate and validate the step size of the proposed modified P&amp;amp;O and FLC techniques within the MPPT algorithm using MATLAB/Simulink for efficient power tracking in photovoltaic systems.

A Semianalytical Solution for the Transient Response of One-Dimensional Unsaturated Single-Layer Porous Media with General Boundary Conditions

A Semianalytical Solution for the Transient Response of One-Dimensional Unsaturated Single-Layer Porous Media with General Boundary Conditions

Kinematic modelling of three link robot manipulator and joint torque optimization using genetic algorithm in MATLAB

This research article presents the non-linear dynamic of a three-link robotic manipulator formulated by the Newton-Euler method. The planar manipulator is composed of three links and three revolute joints rotating about the z-axis. The three nonlinear non-homogeneous dynamic equations have been solved graphically with the help of MATLAB by phase variable method. The work represents the graphical solution of the transient response of angular position, and angular velocity of each link member for a predetermined interval of time. With the help of simulated value from MATLAB, torque characteristics have been determined for different torque ratios and optimum torque has been derived using a genetic algorithm to move the manipulator in a proper direction.

New control scheme for a dynamic voltage restorer based on selective harmonic injection technique with repetitive controller

Repetitive controller and selective harmonic injection technique (SHI) in medium and low voltage distribution networks improve dynamic voltage restorer (DVR) DC bus voltages as well as nullify power quality (PQ) problems. DVRs use sinusoidal pulse width modulation (SPWM) firing control, but DC bus use seems to be limited, affecting density, cost, and power packaging. By adding 1/6th of the 3rd harmonic waveform to the basic waveform, SPWM yields the developed model. According to the findings, 15% of DC bus usage improves and produces high voltage AC. Nevertheless, just control systems perturb PQ. The proposed controller uses feed forward and feedback to enhance transient response and justify stable zero error. 3rd third harmonic injection pulse width modulation (THIPWM) improves total harmonic distortion (THD) in the proposed scheme. Power system computer aided design (PSCAD) simulation produced high accuracy for THIPWM and repetitive controllers.

Robust residual generator design for sensor fault detection in twin rotor aerodynamic system

The twin rotor aerodynamic system (TRAS) reflects the dynamics of vertical take-off rotor systems. TRAS considers the coupling effect and gyroscopic disturbance torque as unwanted signals. For safe and reliable TRAS operation, proper control input is vital, along with fast fault indication. This paper addresses the output sensor fault detection problem in the linear model of TRAS subjected to l2-norm bounded disturbance. A robust design of an observer is formulated as H-/H∞ optimization problem to maximize the sensitivity/robustness criterion. The approach minimizes the disturbance effect on the residual signal, which leads to successful fault detection. Furthermore, a linear quadratic regulator-based state feedback controller is proposed to meet the system's desired transient response requirement. The incorporation of an observer-based residual generator for fault detection along with the state-feedback controller differs the current work from the existing work. Successful fault detection in the output sensor of TRAS depicts the good performance of the proposed observer.

Distributed Optical Fiber-Based Radiation Detection Using an Ultra-Low-Loss Optical Fiber

The combination of an ultra-low-loss optical fiber sensitive to ionizing radiation and an optical time domain reflectometer (OTDR) is investigated to explore the feasibility of a single-ended distributed radiation detector. The peculiarity of the tested fiber resides in its regenerative high radiation-induced attenuation (RIA) response in the infrared spectrum (1310 nm), which returns to a low value once the irradiation has ended, combined to its sensitivity, highly increasing with the dose rate. In this work, only some sections of the fiber line were irradiated with 100 kV X-rays at room temperature, to prove the spatially resolved radiation detection capabilities of the system. The transient RIA response of the fiber was characterized at different pre-irradiation doses. A pre-irradiation treatment was shown to stabilize the optical fiber response, improving its RIA vs. dose rate linearity and repeatability. This improved response, in terms of radiation quantification, comes at the cost of a lower detection threshold. This work lays the bases for a distributed radiation detector, with some capabilities in dose rate evaluation.

Four phases of a force transient emerge from a binary mechanical system.

Accurate models of muscle contraction are important for understanding both muscle performance and the therapeutics that enhance physiological function. However, models are only accurate and meaningful if they are consistent with physical laws. A single muscle fiber contains billions of randomly fluctuating atoms that on the spatial scale of a muscle fiber generate unidirectional force and power output. This thermal system is formally constrained by the laws of thermodynamics, and a recently developed thermodynamic model of muscle force generation provides qualitative descriptions of the muscle force-velocity relationship, muscle force generation, muscle force transients, and the thermodynamic work loop of muscle with a thermodynamic (not molecular) power stroke mechanism. To demonstrate the accuracy of this model requires that its outputs be quantitatively compared with experimentally observed muscle function. Here I show that a two-state thermodynamic model accurately describes the experimentally observed four-phase force transient response to both mechanical and chemical perturbations. This is the simplest possible model of one of the most complex characteristic signatures of muscle mechanics.

Discovering two general characteristic times of transient responses in solid oxide cells

A comprehensive understanding of the transient characteristics in solid oxide cells (SOCs) is crucial for advancing SOC technology in renewable energy storage and conversion. However, general formulas describing the relationship between SOC transients and multiple parameters remain elusive. Through comprehensive numerical analysis, we find that the thermal and gaseous response times of SOCs upon rapid electrical variations are on the order of two characteristic times (τh and τm), respectively. The gaseous response time is approximately 1τm, and the thermal response time aligns with roughly 2τh. These characteristic times represent the overall heat and mass transfer rates within the cell, and their mathematical relationships with various SOC design and operating parameters are revealed. Validation of τh and τm is achieved through comparison with an in-house experiment and existing literature data, achieving the same order of magnitude for a wide range of electrochemical cells, showcasing their potential use for characterizing transient behaviors in a wide range of electrochemical cells. Moreover, two examples are presented to demonstrate how these characteristic times can streamline SOC design and control without the need for complex numerical simulations, thus offering valuable insights and tools for enhancing the efficiency and durability of electrochemical cells.

Carbon-decorated diatomite stabilized lauric acid-stearic acid as composite phase change materials for photo-to-thermal conversion and storage

Diatomite is a promising supporting matrix in the preparation of composite phase change material for latent thermal energy storage. Raw diatomite has the advantages of porous space but with a shortage of thermal conductivity than carbon materials. In this work, the carbon-decorated diatomite (DC) matrix was synthesized by a novel template-carbonization method at different calcination temperatures of 600 °C, 800 °C, and 1000 °C. Then, the matrix was used to stabilize binary lauric-stearic acid of LA-SA for the preparation of diatomite-based composite phase change material which is used to explore the application of composite in photo-to-thermal conversion/storage. Results show that the carbon-decorated process on diatomite causes an increment of specific surface area and pore space. Thus, more phase change material being loaded in the matrix leads to a larger heat storage capacity of the composite. The designed composite with a matrix carbonization temperature of 1000 °C, LA-SA/DC-1000, has a loadage of 49.92 %, melting temperature of 31.48 °C, and latent heat of 70.07 J g-1 which is improved by 23 %. Compared with the raw diatomite-based composite, the enhancements of thermal conductivity were 90 % for that of LA-SA/DC-1000. Moreover, the corresponding composite exhibits better photo-to-thermal conversion performance and transient temperature response.

Ca‐doped PrFeO3 photocathodes with enhanced photoelectrochemical activity

Perovskite oxides, renowned for their adaptable structure and optoelectronic characteristics, hold significant potential for applications in catalysis and photoelectrochemical processes. This research investigates the preparation of praseodymium iron oxide (PrFeO3) by spin coating and the impact of incorporating a calcium (Ca) dopant on its photoelectrochemical efficacy as photocathodes. Spin coating of a polymer containing sol‐gel yielded thin films with uniform morphology and porosity, facilitating effective semiconductor/electrolyte interactions, as characterised by scanning electron microscopy analyses. Evaluation of transient photocurrent responses revealed that introducing Ca at a 5 at% doping level significantly enhanced the photoelectrochemical activity of PrFeO3, resulting in an optimal photocurrent of ‐124 µA cm‐2 at +0.43 VRHE under simulated sunlight conditions. This enhancement was accompanied by an incident photon‐to‐current efficiency of 3.8% at +0.43 VRHE and 350 nm, along with an onset potential of +1.1 VRHE. Ultraviolet and visible spectroscopy analyses indicated an increase in light absorption capabilities in the Ca‐doped films and a noticeable reduction in bandgap compared to the undoped counterparts, further supported by incident photon‐to‐current efficiency measurements. The findings underscore the significant role of dopants in augmenting the photocurrent performance of stable perovskite oxides, highlighting their potential in advancing photon conversion technologies.This article is protected by copyright. All rights reserved.

Advancing V2G Technology: Design of an Adaptive Bi-directional Three Phase AFE Converter for High-Power Applications

The grid-connected active front end (AFE) converter is an essential component of the Vehicle-to-Grid (V2G) system. In the current scenario, only a battery charger with unidirectional power capability for various power levels is being developed, which improves the grid’s power quality in compliance with the standard. A bi-directional battery charger with a high-power rating for V2G applications is a challenging task that is the focus of the current research. This paper presents a three-phase bi-directional grid-connected AFE converter for a 15 kW charging system. The novelty of this paper is to design and implement an adaptive synchronous reference frame (SRF) model-based controller for bi-directional power flow between the electric vehicle (EV) and grid. It uses an adaptive constant current/constant voltage (CC/CV) mode while integrating a bi-directional DC/DC converter to the proposed AFE system. The significant advantages of the proposed AFE system are high power quality at the grid side, along with suitable total harmonics distortion (THD) and ripple-free DC output voltage. Moreover, the bi-directional offboard charger responds to inductive and capacitive reactive power requests in less than three grid cycles, demonstrating a rapid reaction to grid commands. This paper achieves a fast transient response with a less peak overshoot to improve the steady-state performance. The performance of AFE is further analyzed using simulations, and it has finally been verified using a 15 kVA AFE converter on the laboratory set-up.