Transient Response Research Articles (Page 1)

The transient dynamics of electromagnetically induced transparency (EIT) are fundamental to understanding coherent light–atom interactions and the advancement of quantum technologies such as optical switching and quantum memory. However, in room-temperature atomic vapors, Doppler broadening significantly alters these dynamics, yet a comprehensive understanding of its impact on the transient EIT response remains lacking. In this study, we combine analytical and numerical methods to investigate the absorption dynamics of a weak probe field in a three-level Λ-type system driven by a strong coupling field, based on the optical Bloch equations and Laplace transform techniques. Our results show that the transient response is highly sensitive to both the atomic spontaneous emission rate and the Rabi frequency of the coupling field. Increasing the coupling field intensity not only accelerates the approach to steady state but also induces oscillatory dynamics and negative absorption. Under Doppler broadening, the time required to reach steady state increases by approximately three orders of magnitude compared to the Doppler-free case—an effect that is surprisingly insensitive to temperature variations across the 100–400 K range. Moreover, restoring a short steady-state time under broadened conditions necessitates increasing the coupling laser intensity by two orders of magnitude. These findings provide key insights into the influence of Doppler broadening on coherent transient processes and offer practical guidelines for the design of room-temperature atomic devices, including quantum memories and optical modulators.

Nonlocal hydraulic-thermo-poro-visco-elastic transient impact responses of non-Gaussian laser-heated temperature-dependent saturated cylindrical unlined tunnel

Metal-free aminobenzoic acid-derived Schiff bases are attractive antimicrobial leads because their azomethine (–C=N–) functionality enables tunable electronic properties and target engagement. We investigated whether halogenation on the phenolic ring would modulate the redox behavior and enhance antibacterial potency, and hypothesized that heavier halogens would favorably tune physicochemical and electronic descriptors. We synthesized three derivatives (SB-3/Cl, SB-4/Br, and SB-5/I) and confirmed their structures using FTIR, 1H- and 13C-NMR, UV-Vis, and HRMS. For SB-5, single-crystal X-ray diffraction and Hirshfeld analysis verified the intramolecular O–H···N hydrogen bond and key packing contacts. Cyclic voltammetry revealed an irreversible oxidation (aminobenzoic ring) and, for the halogenated series, a reversible reduction associated with the imine; peak positions and reversibility trends are consistent with halogen electronic effects and DFT-based MEP/LHS descriptors. Antimicrobial testing showed that SB-5 was selectively potent against Gram-positive aerobes, with low-to-mid micromolar MICs across the panel. Among anaerobes, activity was more substantial: Clostridioides difficile was inhibited at 0.1 µM, and SB-3/SB-5 reduced its sporulation at sub-MICs, while Blautia coccoides was highly susceptible (MIC 0.01 µM). No activity was detected against Gram-negative bacteria at the tested concentrations. In the fungal assay, Botrytis cinerea displayed only a transient fungistatic response without complete growth inhibition. In mammalian cells (HeLa), the compounds displayed clear concentration-dependent behavior . Overall, halogenation, particularly iodination, emerges as a powerful tool to couple redox tuning with selective Gram-positive activity and a favorable cellular tolerance window, nominating SB-5 as a promising scaffold for further antimicrobial optimization.

Scalable, high-speed, small-footprint photonic switching platforms are essential for advancing optical communication. An effective optical switch must operate at high duty cycles with fast recovery times, while maintaining substantial modulation depth and full reversibility. Colloidal nanocrystals, such as indium tin oxide (ITO), offer a scalable platform to meet these requirements. In this work, the transmission of ITO nanocrystals near their epsilon-near-zero wavelength is modulated by two-cycle optical pulses at a repetition rate of one megahertz. The modulator exhibits a broad bandwidth spanning from 2 to 2.5µm. Sensitive fieldoscopy measurements resolve the transient electric-field response of the ITO for the first time, showing that the modulation remains reversible for excitation fluences up to 1.2mJ cm-2 with a modulation depth of 10%, and becomes fully irreversible beyond 3.3mJ cm-2, while reaching modulation depth of up to 20%. Field sampling further indicates that at higher excitation fluences, the relative contribution from the first cycle of the optical pulses is reduced. These findings are crucial for the development of all-optical switching, telecommunications, and sensing technologies capable of operating at terahertz switchingfrequencies.

ABSTRACT In this paper, we chart a path to a method that enables us to extract temporal and spatially varying pressure loading effects on the transient response of steel plates under near‐field blast loading, employing ultra‐high‐speed cameras and DIC to measure the transient deformation field. The study addresses the challenges of obtaining full‐field, high‐fidelity DIC measurements in extreme blast environments by conducting small‐scale detonations in close proximity to steel target plates using two ultra‐high‐speed camera systems. A comprehensive error analysis of these systems is reported and challenges the historic norms of reported accuracy and repeatability in such testing, showing that errors as low as 0.01 mm can be achieved in transient measurements. Pressure measurements obtained via non‐contact DIC are compared with data from Hopkinson pressure bar measurements, providing cross‐validation of the methods. This research highlights the critical influence of several factors on the reliability of the results, including the chosen camera system, the geometry of the target plate and the errors introduced during DIC processing. The study demonstrates that, with careful attention to experimental design, short exposure times, thorough error evaluation for each camera system and consideration of the structural response, blast test results from DIC can be independent of the camera system used. Furthermore, the study finds that the design of the plate for obtaining accurate impulse distributions is more critical than the inherent camera system uncertainties. Within these limitations, the spatial distribution and temporal development of the impulse loading inferred from the DIC velocity data shows excellent correlation with direct measurements of impulse applied to a nominally rigid target by an identical explosive detonation. This offers a path to a method that could achieve the hitherto impossible task of extracting accurate data on the blast load applied in the extreme nearfield to deforming targets.

In the striated muscle, the molecular motor myosin II functions in two bipolar arrays in each thick filament, converting chemical energy into steady force and shortening by cyclic ATP-driven interactions with nearby actin filaments. The fundamental steps in energy transduction are the working stroke, an inter-domain tilting of the lever arm about the actin-attached catalytic domain, generating up to ∼5 pN force or ∼10 nm of filament sliding, and the release of the ATP hydrolysis product orthophosphate (Pi) from the nucleotide-binding site, which is associated with a large free energy release. The two events are not simultaneous, as first demonstrated by the force response to a stepwise change in [Pi] (the Pi transient), showing the saturation kinetics characteristic of a two-step reaction. However, while high-resolution crystal structures of the myosin motor suggest that Pi release precedes the working stroke, in vitro functional studies indicate that it follows the working stroke. High-resolution sarcomere-level mechanics applied to single muscle fibers, allowing myosin motor synchronization by step perturbations in length or load, revealed that the kinetics of the working stroke is independent of [Pi] and depends only on the load. Moreover, this approach highlights the need for two unconventional pathways of the chemo-mechanical cycle: an early detachment of the force-generating motors and the possibility for attached motors to slip to the next actin monomer farther from the sarcomere center during shortening. Transient and steady-state responses to stepwise changes in load or [Pi] can be fitted with a structurally and biochemically explicit model in which the Pi release step is orthogonal to the progression of the working stroke. Model simulations indicate that the rate of Pi release depends on motor conformation, which resolves longstanding unanswered questions such as the dependence of Pi transient kinetics on the final level of [Pi] under any load and clarifies the issue of the relative timing between the working stroke and Pi release: at high loads, Pi release precedes the execution of the working stroke, while at low loads, the working stroke state transitions are fast enough to occur with Pi still bound to the catalytic site.

This paper presents a novel strategy to achieve adjustable frequency stability in hybrid interconnected power systems with high penetration of renewable energy sources (RESs). The considered system incorporates real-world RESs data to emulate practical grid operation, addressing the challenges posed by RESs variability and intermittency more realistically than previous works. The proposed approach integrates a hybrid energy storage systems (HESSs) with load frequency control (LFC) based on a proportional derivative–proportional integral (PD-PI) controller. The HESSs leverage the complementary strengths of plug-in electric vehicles (PEVs) and superconducting magnetic energy storage (SMES) units, with PEVs providing long-term energy balancing and SMES ensuring rapid transient response. The PD-PI controller is applied to simultaneously manage both LFC and HESSs operation, with its parameters optimally tuned using the electric eel foraging optimizer (EEFO) to ensure precise and effective controller. Comparative analyses demonstrate that the PD-PI controller significantly outperforms traditional proportional integral derivative (PID) controllers in maintaining frequency stability under high-RESs penetration and load disturbances. Specifically, the proposed strategy improves system performance by 55% compared to SMES-based PD-PI controllers and by 45% compared to PEVs-based PD-PI controllers. While the approach is most effective in hybrid systems with available PEVs infrastructure and SMES units, its applicability may be limited in power systems lacking such resources or facing large-scale, long-duration disturbances. Furthermore, the effectiveness of the proposed strategy has been validated under cyber attack conditions ,and system parameters variations. Overall, the findings confirm the critical role of the proposed strategy in mitigating frequency fluctuations during periods of high renewable energy penetration, thereby offering a robust solution for the challenges faced by modern power systems.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-23283-6.

Lower lung field tuberculosis (LLFTB) is an uncommon presentation of pulmonary tuberculosis and is often misdiagnosed as bacterial pneumonia or other lower respiratory tract infections. Its atypical radiographic pattern and transient response to empirical antibiotics can delay definitive diagnosis. We report the case of a 50-year-old male who presented with recurrent episodes of acute febrile respiratory illness, each separated by a two-week symptom-free interval. The patient required hospitalization on three occasions. Each episode showed partial remission with empirical antibiotic therapy, but symptoms recurred after antibiotic withdrawal. Chest radiography demonstrated infiltrates confined to the lower lung fields. HRCT (high resolution computerised tomography) imaging’s documented nodular infiltrates in right middle and lower lobe with mild pleural effusion. Given the recurrent nature and incomplete resolution, flexible bronchoscopy was performed as a point-of-care diagnostic tool, revealing endobronchial changes suggestive of tuberculosis and yielding bronchial washings positive for Mycobacterium tuberculosis on GeneXpert MTB/RIF assay. The patient was initiated on standard first-line anti-tubercular therapy with marked clinical and radiological improvement, and no further relapses over a 6-month follow-up. LLFTB can mimic recurrent bacterial pneumonia. Early bronchoscopy at the point of care facilitates timely diagnosis and initiation of specific therapy, preventing repeated hospitalizations and morbidity.

Traditional heat diffusion systems are typically regulated using Proportional–Integral–Derivative (PID) controllers. PID controllers still remain the backbone of numerous industrial control applications due to their simplicity, robustness, and efficiency. However, traditional tuning methods—such as Ziegler–Nichols or Cohen–Coon—often exhibit limitations when applied to systems with nonlinear dynamics, time-varying behaviors, or parametric uncertainties. To address these challenges, Fuzzy Logic Controllers (FLC) have emerged as a promising hybrid strategy, by translating quantitative and imprecise linguistic inputs into quantitative control actions, thereby enabling more adaptive and precise regulation. This is achieved through the integration of fuzzy inference mechanisms that dynamically adjust PID gains in response to changing system conditions. This study proposes a fuzzy logic control strategy for a heat diffusion system and conducts a comparative analysis against conventional PID control. The methodology encompasses system modeling, design of the fuzzy inference system, and simulation studies. To improve transient response and address time delays, additional features such as Anti-Windup compensation and a Smith Predictor are integrated into the control scheme. The final validation step involves the introduction of simulated environmental disturbances, including abrupt temperature drops, to evaluate the controller’s robustness. Simulation results demonstrate that the proposed FLC provides superior dynamic performance compared to the conventional PID controller, achieving approximately 5–7% faster rise time and 8–10% lower settling time. The incorporation of an anti-windup mechanism did not yield significant benefits in this application. In contrast, the integration of a Smith Predictor further reduced oscillatory behavior and substantially improved disturbance rejection, tracking accuracy, and adaptability under simulated thermal variations. These results underscore the effectiveness of the FLC in handling systems with time delays and nonlinearities, reinforcing its role as a robust and adaptable control strategy for thermal processes with complex dynamics.

The loss factor of wood material is frequency related, which directly affects the calculation method of dynamic responses for wood structures. In this paper, the relationship between loss factor and damping coefficient was determined based on equal dissipated energy. Combined with the time-domain and frequency-domain methods, a modal superposition method was proposed to calculate the dynamic response of wood structures. Compared with the frequency-domain method, the proposed method can additionally consider the transient vibration responses of wood structures. Compared with the equivalent time-domain method based on constant loss factor, the proposed method can additionally consider the influence of frequency related loss factor. The proposed method should be preferred to calculate dynamic responses of wood structures.

Structural dynamics analysis is essential for predicting the behavior of engineering systems under dynamic forces. This study presents a hybrid framework that combines analytical modeling, machine learning, and optimization techniques to enhance the accuracy and efficiency of dynamic response predictions for Single-Degree-of-Freedom (SDOF) systems subjected to harmonic excitation. Utilizing a classical spring–mass–damper model, Fourier decomposition is applied to derive transient and steady-state responses, highlighting the effects of damping, resonance, and excitation frequency. To overcome the uncertainties and limitations of traditional models, Extended Kalman Filters (EKFs) and Physics-Informed Neural Networks (PINNs) are incorporated, enabling precise parameter estimation even with sparse and noisy measurements. This paper uses Adam followed by LBFGS to improve accuracy while limiting runtime. Numerical experiments using 1000 time samples with a 0.01 s sampling interval demonstrate that the proposed PINN model achieves a displacement MSE of 0.0328, while the Eurocode 8 response-spectrum estimation yields 0.047, illustrating improved predictive performance under noisy conditions and biased initial guesses. Although the present study focuses on a linear SDOF system under harmonic excitation, it establishes a conceptual foundation for adaptive dynamic modeling that can be extended to performance-based seismic design and to future calibration of Eurocode 8. The harmonic framework isolates the fundamental mechanisms of amplitude modulation and damping adaptation, providing a controlled environment for validating the proposed PINN–EKF approach before its application to transient seismic inputs. Controlled-variable analyses further demonstrate that key dynamic parameters can be estimated with relative errors below 1%—specifically 0.985% for damping, 0.391% for excitation amplitude, and 0.692% for excitation frequency—highlighting suitability for real-time diagnostics, vibration-sensitive infrastructure, and data-driven design optimization. This research deepens our understanding of vibratory behavior and supports future developments in smart monitoring, adaptive control, resilient design, and structural code modernization.

The article is devoted to the synthesis, implementation, simulation and experimental study of a real-time Lyapunov-based two-degree-of-freedom model reference adaptive controller (MRAC) for an axial-piston pump. The controller of the developed real-time system determinates control signal values applied to the electro-hydraulic proportional valve. The proportional valve is an actuator for driving the swash plate swivel angle of the pump. The swash plate swivel angle determines the displacement volume of the flow rate of the pump. The MRAC is synthesized based on the experimentally identified mathematical model. To conduct the identification and experimental investigation of the controller, the authors have used an existing laboratory test setup. The comparison of the designed MRAC with conventional PI controller is performed. The control performance analysis is based on integral square error (ISE) in transient responses of the pump flow rate at different flow rate references and loads.

Abstract The demand for resilient and energy-efficient infrastructure has driven the development of advanced passive damping systems. Conventional tuned liquid column dampers (TLCDs) are effective for vibration control in medium—to high-rise buildings, but their application in low-rise structures is constrained due to the difficulty in finding a practical, feasible length of TLCD for tuning. To overcome this limitation, this study introduces a novel compliant-tuned liquid column ball damper (CTLCBD), which combines fluid-based damping with smart material adaptability. The CTLCBD integrates a freely moving ball acting as dynamic orifice to enhance energy dissipation and a smart shape memory alloy-based compliant mechanism to enable adaptive tuning. This hybrid design is specifically suited for low- to mid-rise buildings with natural periods between 0.3 and 0.8 s. Experimental validation was performed on a three-story scaled structure subjected to real earthquake ground motions encompassing a wide range of intensities and frequency contents. Structural response was evaluated using peak acceleration, RMS acceleration, and velocity-to-acceleration ratios. The CTLCBD consistently improved seismic performance, achieving average reductions of 31% in RMS acceleration and 21% in peak acceleration, confirming effective suppression of both sustained and transient responses. Overall, the CTLCBD demonstrates significant potential as an adaptable and efficient passive vibration control device, offering a promising solution to improve seismic resilience in short-period, low-to-mid-rise structures.

Effect of purification methods on the physicochemical and biological properties of Nata de fique: A sustainable material for biomedical applications.

In-situ growing of 3D hierarchical flowerball-like CdS/O-doped g-C3N4 nanosheets as a novel photocatalyst for superior H2 evolution.

Effect of apparent pore-fluid compressibility and degree of saturation with atmospheric pressure on wave-induced transient pore pressure response

In high-temperature testing scenarios that rely on contact, fine-wire thermocouples demonstrate commendable dynamic performance. Nonetheless, their thermal inertia leads to notable dynamic nonlinear inaccuracies, including response delays and amplitude reduction. To mitigate these challenges, a novel dynamic error correction approach is introduced, which combines a Continuous Restricted Boltzmann Machine, Deep Belief Network, and Physics-Informed Neural Network (CDBN-PINN). The unique heat transfer properties of the thermocouple’s bimetallic structure are represented through an Inverse Heat Conduction Equation (IHCP). An analysis is conducted to explore the connection between the analytical solution’s ill-posed nature and the thermocouple’s dynamic errors. The transient temperature response’s nonlinear characteristics are captured using CRBM-DBN. To maintain physical validity and minimize noise amplification, filtered kernel regularization is applied as a constraint within the PINN framework. This approach was tested and confirmed through laser pulse calibration on thermocouples with butt-welded and ball-welded configurations of 0.25 mm and 0.38 mm. Findings reveal that the proposed method achieved a peak relative error of merely 0.83%, superior to Tikhonov regularization by −2.2%, Wiener deconvolution by 20.40%, FBPINNs by 1.40%, and the ablation technique by 2.05%. In detonation tests, the corrected temperature peak reached 1045.7 °C, with the relative error decreasing from 77.7% to 5.1%. Additionally, this method improves response times, with the rise time in laser calibration enhanced by up to 31 ms and in explosion testing by 26 ms. By merging physical constraints with data-driven methodologies, this technique successfully corrected dynamic errors even with limited sample sizes.

Animal reproduction is composed of several stages, which collectively determine overall productivity. Yet, it is not fully understood how different productivity components contribute to population change. To bridge this gap, we leveraged integrated population modelling and transient life-table response experiments, together with population-level data on lesser snow geese (Anser caerulescens caerulescens) breeding on Wrangel Island, Russia, from 1970 to 2022. We assessed contributions of breeding propensity, clutch size, nest success, egg survival, hatching success and pre-fledging survival to population change, and tested hypotheses about the effects of environmental drivers and density dependence on different components. Breeding propensity contributed the most to variation in population growth, followed by nest success. These two components were negatively affected by the timing of snow melt. We found no overall deleterious effects of climate change on productivity. Density dependence had a positive effect on multiple productivity components, likely through predator swamping. Our results show the importance of breeding propensity to the population dynamics of this long-lived animal, which is notable because this productivity component is often overlooked. Our results also demonstrate that the effects of environmental conditions and density dependence can differ among animal populations of different sizes, locations and life histories.

Organic electrochemical transistors (OECTs) are crucial for next-generation (bio-)electronic devices but are often constrained by the use of aqueous electrolytes, which introduce crosstalk, hinder miniaturization, and limit circuit integration. Here, a photo-patternable solid-state electrolyte based on 𝜄-carrageenan (𝜄-CGN) and poly(ethylene glycol) diacrylate (PEGDA) is presented, enabling high-performance OECTs and complementary circuits. The 𝜄-CGN electrolyte exhibits high ionic conductivity (>10 mS cm-1), comparable to a 0.1 m NaCl aqueous electrolyte, while supporting precise patterning down to 15 µm, fast transient response times, minimal hysteresis, and excellent stability in both p- and n-type OECTs. Compact solid-state NAND/NOR gates (500 × 800 µm2), 4-input NAND gates (1600 × 800 µm2, 8 OECTs), and half-adders (2 × 1 mm2, 18 OECTs) are demonstrated, all exhibiting correct logic functions and low-voltage operation. To highlight its potential for implantable bioelectronics, solid-state spiking circuits, monolithically integrated with flexible cuff electrodes, are developed for vagus nerve stimulation in mice. These findings establish 𝜄-CGN-based solid-state electrolytes as a promising platform for scalable, implantable circuits, paving the way for next-generation bioelectronic devices.

A fast transient response capless low-dropout regulator with NMOS-FVF structure