Response Speed Research Articles

Natural photosensitizer extraction from Delonix regia flowers for future photosensor for DSSCs applications

This study explores the utilization of Delonix regia (DR) (Gulmohar flower) as a natural photosensitizer in the fabrication of self-powered photosensors via dye-sensitized solar cells (DSSCs). Various photoanodes, including ZnO, ZnO/TiO2, and ZnO/TiO2/Nb2O5, were investigated for their performance enhancement in DR-based photosensors. The photoanodes were fabricated using different deposition methods sensitized with DR photosensitizer and characterized through X-ray diffraction analysis, Field emission scanning electron microscopy (FE-SEM), UV–visible, Fluorescence spectroscopy, and Fourier transform infrared spectroscopy (FTIR) analysis. The absorbance spectrum results indicate improved photosensitizer adsorption in visible light for the ZnO/TiO2/Nb2O5/DR photoanode compared to other configurations. The scanning electron microscopy (SEM) cross-section image of ZnO/TiO2/Nb2O5 confirmed the formation of a multilayer photoanode. Chronoamperometry experiments were conducted to evaluate the photo sensing behavior, focusing on sensitivity, photoresponsivity, specific detectivity, and quantum efficiency within the solar spectrum range. Among the devices, ZnO/TiO2/Nb2O5 exhibited the highest photoresponsivity (1.2 × 10 −3 A/W) and photodetectivity (26.78 × 104 Jones), demonstrating promising advancements in DR-sensitized photosensors. This research highlights the exceptional performance of DR-sensitized photoanodes, particularly ZnO/TiO2/Nb2O5, in advancing the capabilities of photo-sensing devices. The investigated configuration exhibited a rapid response speed of 723 ms and a remarkable sensitivity of 89.87% in detecting photo signals. These findings emphasize the potential of DR photosensitizers to enhance photo-sensing activities, with significant implications for diverse applications in photodetection. By leveraging the unique properties of DR, particularly its incorporation into ZnO/TiO2/Nb2O5, this study underscores the promising prospects for developing efficient self-powered photosensors. The insights gleaned from this work pave the way for further exploration and optimization in organic photosensors.

PCLOS based fractional-order sliding mode stochastic path following control for underactuated marine vehicles with multiple disturbances and constraints

This paper investigates the stochastic path following control of underactuated marine vehicles (UMVs) subject to multiple disturbances and constraints. Firstly, the complex marine environment in which UMVs navigate typically contains stochastic components, thus the multiple disturbances are categorized as slow-varying deterministic disturbances and stochastic disturbances. Secondly, a position-constrained line-of-sight (PCLOS) based fractional-order sliding mode stochastic (FSMS) control strategy is established to achieve path following control of UMVs. A PCLOS guidance law based on universal barrier Lyapunov function is proposed to ensure that the position errors remain within the constraint ranges, which is versatile for systems with symmetric constraints or without constraints. An FSMS controller based on fractional-order theory and sliding mode control is designed to improve the dynamic response speed of the system and effectively attenuate chattering phenomenon. A stochastic disturbance observer is developed to estimate the slow-varying deterministic disturbances in the stochastic system, and auxiliary dynamic compensators are used to mitigate the impact of input constraints. Lastly, theoretical analysis indicates that the closed-loop system is stable and the position constraint requirements are satisfied. Comparative simulations illustrate the effectiveness of the proposed control strategy.

Interval Type-2 Fuzzy Neural Network Based Cascade Predictive Control of Superheated Steam Temperature

Abstract The superheated steam temperature (SST) suffers from complex dynamic characteristics such as nonlinearity and large time delay. To deal with the negative effects, this paper proposes a cascade predictive control strategy (CPC-PI) based on interval type-2 fuzzy neural network (IT2FNN) to improve the performance of SST. First, this paper proposes the IT2FNN model for modeling the SST model. And then on the basis the local linearized IT2FNN model, the CPC-PI strategy is designed. In the following, fuzzy self-regulation of the weight factor in the CPCPI is carried out to further improve the dynamic response speed and stability of SST. Finally, the comparative simulations verify that the IT2FNN-based CPC-PI control strategy with self-regulated weight factor is superior to the PI-PI control strategy and the IT2FNN-based CPC-PI control strategy with fixed weight factor.

Voltage stability control strategy for DC microgrid based on adaptive virtual DC motor

The large-scale integration of distributed energy sources and power electronic devices results in the DC microgrid exhibiting significant low inertia and weak damping characteristics. This, in turn, leads to inevitable fluctuations in the DC bus voltage, which endanger the stable operation of the DC system. Energy storage devices can provide equivalent inertia. To enhance the inertia and response speed of the DC bus interface converter, this paper proposes a power allocation parameter adaptive virtual DC motor control strategy based on a hybrid energy storage unit. The strategy introduces power allocation control to regulate the energy storage converter on the basis of virtual inertia parameter adaptive control, thereby enabling the energy storage converter to simulate the inertia and damping characteristics of a DC generator. The small-signal stability of the system is analyzed by establishing a small-signal model of the photovoltaic energy storage system and utilizing the impedance ratio criterion. Finally, the proposed control strategy is validated through simulation. The results demonstrate that the strategy effectively mitigates the fluctuations in bus voltage under varying photovoltaic power and sudden load changes, ensures the power distribution in the hybrid energy storage system, and enhances the dynamic response of the system.

Biomimetic soft actuator: Rapid response to multiple stimuli with programmable control

Stimuli-responsive soft actuators have attracted increasing attention in multiple fields since they exhibit unique advantages in safe interaction with humans and adaptability to dynamic environments. However, the study of untethered stimuli-responsive soft actuators has been limited by the slow response speed, irreversible deformations or inability in responding to multiple stimuli. Taking inspiration from the growth process of lotus leaves, we propose a novel design for an untethered soft actuator comprising graphene oxide (GO) and polyethylene (PE), which shows sensitive response to multiple stimuli, including moisture, light, heating, cooling, and elective volatile organic compounds (VOCs), and exhibits significant deformation at a rapid rate (up to 90.5°/s). The high sensitivity of the actuators enables them to be powered by the neglected energy in daily life instead of requiring specialized energy sources, paving the way for the green and sustainable development in soft robotics. In addition, the bending modes and bending degrees of actuators can be programmed to meet the personalized needs of complex three-dimensional structures. Based on GO/PE actuators, a variety of multi-stimuli-responsive intelligent devices have been developed to demonstrate their application potential in arts, bionics, soft robotics and wearable devices, including interesting WordArt, Chinese paper-cut art pieces, artificial iris, soft crawling robots and a smart cloth unit with adjustable breathability.

Self-powered Schottky barrier photodetectors based on P3HT:PC61BM bulk heterojunction films

By employing the classic system poly(3-hexylthiophene-2,5-diyl): [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC61BM), organic bulk heterojunction films were applied on an indium tin oxide substrate using a one-step spin-coating method, without requiring any complex manufacturing processes, to obtain self-powered photodetectors (PDs) with a simple preparation process. The fullerene material was introduced to create a bulk heterojunction film with proper phase separation and greatly enrich the donor/acceptor dissociation interface, thus improving the high exciton binding energy and short exciton diffusion distance. The built-in electric field formed by the Schottky junction at the interface between the active layer and electrode can enhance the separation of excitons and the transport of charge carriers, realizing optical detection without external energy sources. Moreover, femtosecond transient absorption was employed to investigate the exciton dynamics in organic films and analyze the working mechanism of self-powered detection performance. The long-lived behavior of carriers and the formation of charge transfer states were further verified, which contributed to the enhanced performance of the device. As a result, the self-powered PD-based Schottky bulk heterojunction presents a high light on/off ratio of over 104 (0 V) and fast response speed with rise and decay times of 33 and 36 µs, respectively, under a 532 nm light illumination. These results provide theoretical and experimental verification of this technique for the development of self-powered PDs in the field of organic materials.

Balancing Carrier Dynamics in Oxygen-Vacancy-Tuned Amorphous Ga2O3 Thin-Film Self-Powered Photoelectrochemical-Type Solar-Blind Photodetector Arrays for Underwater Imaging.

Underwater imaging technology plays a pivotal role in marine exploration and reconnaissance, necessitating photodetectors (PDs) with high responsivity, fast response speed, and low preparation costs. This study presents the synergistic optimization of responsivity and response speed in self-powered photoelectrochemical (PEC)-type photodetector arrays based on oxygen-vacancy-tuned amorphous gallium oxide (a-Ga2O3) thin films, specifically designed for solar-blind underwater detection. Utilizing a low-cost one-step sputtering process with controlled oxygen flow, a-Ga2O3 thin films with varying oxygen vacancy (VO) concentrations are fabricated. By balancing the trade-offs among electrocatalytic reactions, charge transfer, carrier recombination, and trapping, both the responsivity and response speed of a-Ga2O3-based self-powered PEC-PDs are simultaneously improved. Consequently, the optimized PEC-PDs demonstrated exceptional performance, achieving a responsivity of 33.75mA W-1 and response times of 12.8ms (rise) and 31.3ms (decay), outperforming the vast majority of similar devices. Furthermore, a pronounced positive correlation between anomalous transient photocurrent spikes and the concentration of VO defects is observed, offering compelling evidence for VO-mediated indirect recombination. Finally, the proof-of-concept solar-blind underwater imaging system, utilizing an array of self-powered PEC-PDs, demonstrated clear imaging capabilities in seawater. This work provides valuable insight into the potential for developing cost-effective, high-performance a-Ga2O3 thin-film-based PEC-PDs for advanced underwater imaging technology.

A Data-Driven Predictive Control Method for Modeling Doubly-Fed Variable-Speed Pumped Storage Units

In this study, a data-driven model predictive control (MPC) method is proposed for the optimal control of a doubly-fed variable-speed pumped storage unit. This method combines modern control theory with the dynamic characteristics of the pumped storage unit to establish an accurate dynamic model based on actual operating data. In each control cycle, the MPC uses the system model to predict future system behavior and determines the optimal control input sequence by solving the constrained optimization problem, thereby effectively dealing with the nonlinearity, time-varying characteristics, and multivariable coupling problems of the system. When compared with a traditional PID control, this method significantly improves control accuracy, response speed, and system stability. The simulation results show that the proposed MPC method exhibits better steady-state error, overshoot, adjustment time, and control energy under various operating conditions, demonstrating its advantages in complex multivariable systems. This study provides an innovative solution for the efficient control of doubly-fed variable-speed pumped storage units and lays a solid foundation for the efficient utilization of new energy sources.

Аналіз даних теплового режиму комутаційного обладнання комп’ютерних мереж на основі відновлення сигналів температурних датчиків

The article considers the task of analyzing distributed data of temperature modes of chips of switching equipment of computer networks. For this, a temperature measurement system using a temperature sensor is used. In the case when the temperature sensor is inside the chip, the speed of the measurement system's response to temperature changes is satisfactory. However, when the sensor is outside the chip, due to the inertness of the thermal contact, the response speed of the measuring system is low. In this situation, the effectiveness of the control system becomes unsatisfactory. To overcome the inertness of temperature sensors, it is proposed to analyze the distributed data that is received in digital form on the data processing server by restoring the distorted signals of nonlinear measuring subsystems «chip – temperature sensor» based on the use of their mathematical models in the form of a partial sum of the Volterra integro-power series. The identification of the mathematical model of the measurement subsystem is carried out on a finite interval of time by conducting a series of experiments using test signals. The method of reducing the number of test signals based on taking into account the specificity of the impact of nonlinearity on the results of experiments is considered. The obtained model is the basis for solving the inverse problem of restoring the signal of temperature influence at the sensor input. Since this problem is incorrect, it is suggested to supplement the model with a regularization parameter and reduce the problem to a correct one. To use the model over an infinite period of time, a computer modeling technique is proposed using restarts of computing processes, which are carried out in several streams with a shift in time. The result of calculations is formed by combining fragments from different streams. To check the reliability of the results obtained by applying the developed method, the solutions of the model problems are given.

Improved Performance of the Permanent Magnet Synchronous Motor Sensorless Control System Based on Direct Torque Control Strategy and Sliding Mode Control Using Fractional Order and Fractal Dimension Calculus

This article starts from the premise that one of the global control strategies of the Permanent Magnet Synchronous Motor (PMSM), namely the Direct Torque Control (DTC) control strategy, is characterized by the fact that the internal flux and torque control loop usually uses ON–OFF controllers with hysteresis, which offer easy implementation and very short response times, but the oscillations introduced by them must be cancelled by the external speed loop controller. Typically, this is a PI speed controller, whose performance is good around global operating points and for relatively small variations in external parameters and disturbances, caused in particular by load torque variation. Exploiting the advantages of the DTC strategy, this article presents a way to improve the performance of the sensorless control system (SCS) of the PMSM using the Proportional Integrator (PI), PI Equilibrium Optimizer Algorithm (EOA), Fractional Order (FO) PI, Tilt Integral Derivative (TID) and FO Lead–Lag under constant flux conditions. Sliding Mode Control (SMC) and FOSMC are proposed under conditions where the flux is variable. The performance indicators of the control system are the usual ones: response time, settling time, overshoot, steady-state error and speed ripple, plus another one given by the fractal dimension (FD) of the PMSM rotor speed signal, and the hypothesis that the FD of the controlled signal is higher when the control system performs better is verified. The article also presents the basic equations of the PMSM, based on which the synthesis of integer and fractional controllers, the synthesis of an observer for estimating the PMSM rotor speed, electromagnetic torque and stator flux are presented. The comparison of the performance for the proposed control systems and the demonstration of the parametric robustness are performed by numerical simulations in Matlab/Simulink using Simscape Electrical and Fractional-Order Modelling and Control (FOMCON). Real-time control based on an embedded system using a TMS320F28379D controller demonstrates the good performance of the PMSM-SCS based on the DTC strategy in a complete Hardware-In-the-Loop (HIL) implementation.

Enhancing Health Services through Telemedicine: Addressing the Gaps in LBW Monitoring and Training at Puskesmas Gedangan, Sidoarjo Regency

Puskesmas in Sidoarjo Regency do not yet have facilities for monitoring LBW in real time via android either by health workers at the health centre or the patient's family. Puskesmas Gedangan serves communities spread across several villages with a coverage area spread across several villages. This is an obstacle for families to get access to monitor the patient's progress, because the patient is in the NICU or ICU room. Another thing is that there is no training for users in the use of telemedicine-based Baby Incubator equipment. The role of users and families of patients is very important to keep the equipment in good condition. However, operating trainings based on new technology for users have never been conducted. Efforts to solve the above problems are to carry out counselling and assistance in the use of baby incubator equipment to users including nurses, midwives and other non-health worker users, so as to increase the knowledge of officers or users which in turn will have an impact on increasing the productivity of officers or users and improving the quality of service at the health centre. The purpose of this Community Service is to increase the role and participation of Poltekkes Kemenkes Surabaya in improving the degree of public health in the Puskesmas Gedangan area, Sidoarjo Regency. The results of community service through the application of telemedicine-based Baby Incubator at Puskesmas Gedangan are increased knowledge and skills regarding telemedicine-based baby incubator equipment. This will improve health services, especially for babies who need intensive care. The implementation of this technology provides significant benefits, including increased accessibility of health services, speed of response to patient health conditions, family involvement in care, and efficient use of resources. Assistance to Puskesmas personnel and patient families in the form of training, monitoring and evaluation of the use of appropriate technology in the form of Telemedicine-based baby incubator utilization.

Ultra‐Fast Weak Light Detectors Based on van der Waals Stacked 2D Semiconductor/h‐BN Heterostructures

AbstractFast and sensitive detectors for weak light are crucial in various fields like real‐time monitoring, medical diagnosis, and astronomy. However, photodetectors using 2D materials face challenges in achieving both a low detection limit for weak light and fast response. Here, a vertical vdW graphene/indium selenide (InSe)/hexagonal boron nitride (h‐BN) heterostructure on a gold electrode is provided, demonstrating an ultra‐low detection limit of 47.4 nW cm−2 and an ultra‐fast response speed of 327 ns. Vertical photodetectors feature nanoscale channel length, thus reducing scattering and recombination of carriers. The high potential barrier of multilayer h‐BN effectively blocks carrier transport, resulting in ultra‐low dark current and minimal power dissipation. Additionally, enhanced light absorption in InSe by the metal‐insulator‐semiconductor structure improves the sensitivity to weak light detection. More importantly, the built‐in field at the graphene/InSe interface can promote the separation of photo‐generated carriers to improve the collection efficiency. These factors jointly reduce the detection limit and response time simultaneously for weak light. This vertical vdW heterostructure comprising a 2D semiconductor/h‐BN offers a solution to make the majority of 2D semiconductors applicable in ultra‐fast weak light detectors.

Exploring the Efficacy of a ChatGPT-Based Application in Enhancing Oral English Proficiency for Chinese ESL Students

This research explores the impact of Chat GPT AI Characters on ESL learning, comparing them to traditional peer practice in language education. It investigates AI's influence on language proficiency, engagement, and response quality, drawing from literature on ESL challenges. Using mixed methods—pre- and post-test questionnaires, classroom experiments—the study evaluates two groups' language fluency, response speed, and answer quality. Thematic analysis uncovers student perspectives, while statistical methods like t-tests and correlation studies highlight group differences. Ethical considerations prioritize privacy and consent. Anticipated outcomes include improved language skills and engagement. Acknowledging limitations in sample size and cultural biases, this study illuminates AI's role in ESL education, informing future teaching practices.

What is a State-of-the-Art Definition of Supply Chain Resilience in 2024 – With a Systematic Literature Review

In light of escalating disruptions to global supply chains catalysed by events such as the COVID-19 pandemic and the Russo-Ukrainian war, the imperative of enhancing supply chain resilience (SCR) has become increasingly pronounced. The existence of varying definitions of SCR complicates efforts to quantitatively measure and assess resilience. To elucidate the essence of supply chain resilience, we conducted a meticulous systematic literature review (SLR) aimed at crystallizing a scientifically rigorous definition of SCR. Our SLR methodology involved comprehensive preparation and judicious paper selection, followed by a thorough analysis of supply chain resilience definitions. This analysis was conducted via the dimensions of three typical characteristics—preparedness, reaction, and recovery—and four foundational pillars—focus event, performance level, speed, and adaptive response. As a result, a robust definition of SCR is proposed, synthesizing insights from the three typical characteristics theory and the four pillars theory, supplemented with meaningful additions. The research contributes to developing frameworks for supply chain resilience measurement.

Ultrathin Ga2O3 Photodetector with Fast Response and Trajectory Tracking Capability Fabricated by Liquid Metal Oxidation.

Low-dimensional Ga2O3 demonstrates a unique ultraviolet photoresponse and could be used in various electronic and optical systems. However, the low-dimensional Ga2O3 photodetector is faced with the challenges of a complex preparation process and poor device performance. In this work, ultrathin Ga2O3 layers with ∼7 nm thickness are prepared on quartz rods by UV exposure to liquid gallium. Benefiting from low-density oxygen vacancy defects cured by UV exposure, the low-dimensional Ga2O3 photodetector exhibits a high response speed (rise: 64.7 μs; fall: 51.4 μs) and an exceptional linear dynamic range of 120 dB. Furthermore, the photodetector array based on these ultrathin Ga2O3 shows an effective trajectory tracking capability by monitoring UV source motion. This work develops a simple preparation method to construct a low-dimensional UV photodetector array with fast response and useful trajectory tracking capability, exhibiting the significance of ultrathin Ga2O3 in UV optoelectronics.

Short-Term Hydro-Wind-PV peak shaving scheduling using approximate hydropower output characters

With the massive construction of wind and photovoltaic (PV) power plants, the uncertainty of their output poses challenges for grid peak regulation. Hydropower, characterized by convenient regulation, fast response speed, and low cost, is an ideal choice for compensating for wind and PV energy generation. Mixed-Integer Linear Programming (MILP) is employed to work out short-term scheduling of hydro-wind-PV power. However, considering hydropower scheduling alone is already highly complex, and incorporating the deviations in wind and PV energy further reduces the solution efficiency. In practical scheduling, operators often rely on empirical scheduling methods that can yield satisfactory results. To enhance solution quality and improve the scalability and efficiency of the MILP method, a short-term optimization scheduling model for hydropower plants has been proposed and applied to the Hongshui River cascade system. The case study shows that the model can perform calculations in just 2 s, demonstrating extremely high computational efficiency. This can significantly enhance decision-making in cascaded hydropower scheduling. At the same time, the model leaves sufficient reserve capacity to address the uncertainty of wind and solar power output while reducing the residual load by 0.8 %, which is beneficial for the stable operation of the grid.

(Invited) Development of Fiber-Optic Hydrogen Sensor Using Platinum-Supported Tungsten Trioxide-Silica Composite Film

A fiber-optic hydrogen gas sensor using a platinum-supported tungsten oxide-silica composite film was fabricated. This sensor utilizes the absorption of the evanescent field interaction in the hydrogen sensitive clad which was composed of WO3 and SiO2, coated on a silica core with sol-gel process. As a first step, transmission spectra of sensing film itself were measured. The transmittance of the sensitive film decreased in the range of wavelengths above about 500 nm after exposure to pure hydrogen, and the change in transmittance at 1300 nm was greater than that at 850 nm. Then, fiber optic sensor device was fabricated, and the amount of propagating light was measured. In the case of using the light source with a wavelength of 1300 nm, the sensitivity with respect to the hydrogen response was nearly twice and the response speed was faster, compared with those at 850 nm.

Oxidation-induced graded bandgap narrowing in Two-dimensional tin sulfide for high-sensitivity broadband photodetection

Two-dimensional (2D) layered group-IV monochalcogenides with large surface-to-volume ratio and high surface activity make that their structural and optoelectronic properties are sensitive to air oxidation. Here, we report the utilization of oxidation-induced gradient doping to modulate electronic structures and optoelectronic properties of 2D group-IV monochalcogenides by using SnS nanoplates grown by physical vapor deposition as a model system. By a precise control of oxidation time and temperature, the structural transition from SnS to SnSOx could be driven by the layer-by-layer oxygen doping and intercalation. The resulting SnSOx with a graded narrowing bandgap exhibits the enhanced optical absorption and photocurrent, leading to the fabricated SnSOx photodetector with remarkable photoresponsivity and fast response speed (<64 μs) at a broadband spectrum range of 520–1550 nm. The peak responsivity (7294 A/W) and detectivity (9.54 × 109 Jones) of SnSOx device are at least two orders of magnitude larger than those of SnS photodetector. Moreover, its photodetection performance can be competed with state-of-the-art of 2D materials-based photodetectors. This work suggests that the air oxidation could be utilized as an efficient strategy to engineer the electronic and optical properties of SnS and other 2D group-IV monochalcogenides for the development of high-performance broadband photodetectors.

Biomimetic Transparent Slippery Surface for the Locomotion of Photocontrol Droplets and Bubbles.

Directed transportation and collection of liquids and bubbles play a vital role in the survival of ecosystems. Among them, the optical response control is widely used in the fields of microfluidic chips and chemical synthesis because of its high remote operation and fast response speed. However, due to poor light transmission, the development direction of traditional near-infrared (NIR) absorbing materials in the field of visualization is limited, and there are few reports of manufacturing an operating platform that can realize the directional movement of droplets/bubbles on a single platform. Here, a transparent photo-responsive PBFS platform is prepared for droplet and bubble manipulation by coating the etched glass substrate with Prussian blue (PB) nanocubes. When near-infrared (NIR) irradiation on the PBFS platform, PB nanocubes trigger heat production by photothermal means, due to the action of Marangoni force, the surface tension on the left and right sides of the droplets and bubbles is not uniform, forming a surface tension gradient, thereby driving the movement of the droplets and bubbles. The control platform has good application potential in the field of microchemical reaction and biomedical engineering and brings new solutions to the field of transparent photothermal materials.

The enhanced characteristics of bipolar phototransistor with huge amplification

Heterojunction devices based on low-dimensional materials have the potential for convenient and efficient photodetection applications. In this study, we demonstrate a van der Waals (vdW) heterojunction device constructed by p-ZrGeTe4 and n-MoS2. Forming a p-n junction, the response speed of the device increased by 6 orders of magnitude compared to devices with individual MoS2. To further improve the responsivity of the device, a bipolar phototransistor (PTD) was prepared based on the p-n junction. The PTD achieves the photocurrent gain of almost 40. This PTD achieves high responsivity of 1.48 A W−1, and the corresponding specific detectivity can reach 3 × 1014 Jones in low frequencies. Under low frequencies, the noise of the device is dominated by generation–recombination noise; and as the frequency increases, it gradually becomes dominated by 1/f noise. The PTD is competitive in optoelectronics and promising in high-performance integrated devices.