Fast Response Characteristics Research Articles

Study on Time Test Systems for Ultra-Fast Photodetectors

The photomultiplier tube (PMT) and silicon photomultiplier (SiPM) of small areas have the characteristics of fast time response, suitable for the detection of fast and extremely weak light signals, and the transit time spread (TTS) can be on the picosecond scale. The test system is generally divided into two types: one is the direct acquisition of the waveform (DAW), (DAW such as the high-sampling oscilloscope), and the other is an indirect acquisition of the waveform (IDAW). In this article, both DAW and IDAW will be used to carry out the comparative test of ultra-fast photodetectors to complete the calibration of the performance of ultra-fast detectors and the study on time test systems. This will be helpful for beam experiments to be carried out in the laboratory and provide effective support for the development of domestic fast PMT.

Coordinated power control of electrochemical energy storage for mitigating subsequent commutation failures of HVDC

Commutation failure is one of the most common faults in high voltage direct current (HVDC) transmission system. Subsequent commutation failures (SCFs) caused by commutation failure will cause large voltage and current swing. Several SCFs may cause DC transmission power interruption, which seriously threatens the safe and stable operation of AC/DC hybrid power grid. With the construction and commissioning of grid-side electrochemical energy storage (EES), it is possible to mitigate SCFs of adjacent HVDC transmission lines using EES with fast power response characteristics. In this paper, the influence mechanism of active and reactive power output of EES on commutation conditions is studied by combining the evolution of cascading outages and SCFs. It is found that reactive power mainly affects AC voltage and active power mainly affects DC current. Based on the mechanism analysis, a coordinated power control strategy for EES is presented. This strategy, combined with EES capacity constraints, can control EES active and reactive power output instructions adaptively according to the degree of AC failure at different stages of SCFs to fully release the transient support capacity of EES. Case studies are undertaken on the Henan multi-infeed UHVDC system and CIGRE-HVDC standard test system, respectively. The simulation results verify the correctness of the proposed EES power control strategy and the effectiveness of the strategy for SCFs mitigation in different systems, different fault types, and different fault degrees.

Big Data Integration Method of Mathematical Modeling and Manufacturing System Based on Fog Calculation

Using big data to promote economic development, improve social governance, and improve service and regulatory capabilities is becoming a trend. However, the current cloud computing for data processing has been difficult to meet the demand, and the server pressure has increased dramatically, so people pay special attention to the big data integration of fog computing. In order to make the application of big data meet people’s needs, we have established relevant mathematical models based on fog calculation, made system big data integration, collected relevant data, designed experiments, and obtained relevant research data by reviewing relevant literature and interviewing professionals. The research shows that big data integration using fog computing modeling has the characteristics of fast response and stable function. Compared with cloud computing and previous computer algorithms, big data integration has obvious advantages, and the computing speed is nearly 20% faster than cloud computing and about 35% higher than other computing methods. This shows that big data integration built by fog computing can have a huge impact on people’s lives.

Design and analysis of permanent magnet synchronous servo motor with low rotational inertia and high torque density

Aerospace servo motor has the characteristics of strong load capacity, fast response and high control accuracy. To satisfy the design target of high dynamic performance and low weight, the high magnetic loading ironless-core array rotor structure is applied to balance the low rotational inertia and high torque density of permanent magnet servo system.

Optimal Control Strategy of Platform Load Oriented to Network and Load Cooperation

In recent years, with the continuous growth of China’s power peak load and the rapid development of renewable energy, a large number of renewable energy sources are connected to the power grid, increasing the uncertainty of power grid operation and posing new major challenges to the power system regulation capacity. Flexible load has the characteristics of wide distribution, fast response, and high economy, which is an important control resource for the future power system. Based on the flexible load of commercial buildings and residential users, this paper studies the resource characteristics and response characteristics, clarifies the resource characteristics and demand response characteristic indexes of commercial and residential users, and establishes the response characteristics model of commercial buildings and residential users. Considering the influence of weather, holidays, incentive mechanism, and other factors on the response of flexible load, the quantitative analysis method of flexible load resource regulation potential for regional power grid dispatching was studied, and the feasibility of flexible load resources directly participating in the load control system was analyzed. Based on the uncertainty and mathematical characterization method of the active response of flexible loads, the optimal combination control strategy of demand response resources was proposed to eliminate the problems of heavy load and overload of regional power grid equipment by using the active response ability of flexible loads. Finally, the IEEE 14-node system is selected for simulation verification, which provides a theoretical basis for alleviating the power grid operation pressure in the peak load period of the power grid in the urban core area, improving the safety and economic operation level of regional power grid dispatching and the utilization rate of power grid equipment assets.

Research on Temperature Measurement Technology of Platinum Film Thermistor

Platinum film thermistor is developed by combining platinum film thermistor with thin film technology, which solves the cost and application problems of platinum film thermistor components. The principle, fabrication process and application of platinum film thermistor are introduced. A temperature acquisition device of platinum film thermistor is designed. It is verified that the platinum film thermistor has the characteristics of fast response and high accuracy. The temperature data of aluminum alloy plate heated at a single point is collected by using the temperature measurement system. The characteristics of the platinum film thermistor model are verified by comparing the collected data with the simulation data. The results show that the platinum film thermistor can accurately and efficiently complete the fine temperature change measurement, which has a broad development prospect.

Hollow hierarchical TiO2-SnO2-TiO2 composite nanofibers with increased active-sites and charge transfer for enhanced acetone sensing performance

• The sensor based on TiO 2 -SnO 2 -TiO 2 composite nanofibers detects acetone down to 1 ppm at 280°C. • The special hollow structure and the increased oxygen vacancies greatly improves the surface gas adsorption behavior. • The enhanced acetone sensing mechanism of TiO 2 -SnO 2 -TiO 2 composite nanofibers is discussed detailed. The construction of heterojunction composite nanomaterials is one of the most promising methods for obtaining gas sensors with high sensitivity, low detection limit and fast response-recovery behavior. Herein, we successfully synthesized hollow TiO 2 -SnO 2 -TiO 2 composite nanofibers. The body consists of hollow SnO 2 nanofibers, and the inner and outer surfaces are surrounded by mixed phase TiO 2 nanoparticles by a simple two-step method. The hollow SnO 2 nanofibers were first fabricated by facile electrospinning technique, and then the TiO 2 nanoparticles were subsequently grown on the hollow SnO 2 nanofibers via the hydrothermal method. When compared with the sensors based on pure hollow SnO 2 nanofibers, the 10 wt% hollow TiO 2 -SnO 2 -TiO 2 hetero-structures sensor had an excellent sensing performance at the low operating temperature of 280°C and the fast response and recovery characteristics at a low concentration (1 ppm). It presented good selectivity and high response toward acetone compared to pure hollow nanofibers. The main reason for the enhanced acetone gas sensing properties and shortens the response-recovery time was attributed to hollow nanosructure and n-n hetero-junction for hollow TiO 2 -SnO 2 -TiO 2 composite nanofibers. In addition, the acetone adsorption-desorption mechanism of the hetero-nanofibers was discussed.

Dynamic Vision Sensor Tracking Method Based on Event Correlation Index

Dynamic vision sensor is a kind of bioinspired sensor. It has the characteristics of fast response, large dynamic range, and asynchronous output event stream. These characteristics make it have advantages that traditional image sensors do not have in the field of tracking. The output form of the dynamic vision sensor is asynchronous event stream, and the object information needs to be provided by the relevant event cluster. This article proposes a method based on the event correlation index to obtain the object’s position, contour, and other information and is compatible with traditional tracking methods. Experiments show that this method can obtain the position information of the moving object and its continuous motion trajectory and analyze the influence of the parameters on the tracking effect. This method will have broad application prospects in security, transportation, etc.

Continuous response fluorescence sensor for three small molecules based on nitrogen-doped carbon quantum dots from prunus lannesiana and their logic gate operation

In this study, an environmentally friendly and water-soluble nitrogen-doped carbon quantum dots (N-CQDs) with quantum yield (QY) of 8.59% were prepared by one-step hydrothermal synthesis without any chemical reagent using the leaves of prunus lannesiana as precursors. The properties and quality of N-CQDs were investigated by Ultraviolet–visible absorption spectroscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, zeta potential, high-resolution transmission electron microscopy and fluorescence spectroscopy. The fluorescence of the prepared N-CQDs can be quenched by Fe3+ through the synergistic effect of the formation of non-fluorescent complex and internal filtration effect (IFE) between Fe3+ and N-CQDs. And the quenched fluorescence can be “turned on” after adding ascorbic acid (AA) because Fe3+ can be released from the surface of N-CQDs through the redox reaction between AA and Fe3+. While the restored fluorescence can be “turned off” again by hydrogen peroxide (H2O2) due to the re-oxidation of Fe2+ to Fe3+. So, the three inputs “logic gate” is achieved and the “on-off-on-off” continuous response fluorescence sensor is formed, which can be applied for the continuous detection of Fe3+, AA and H2O2 with the linear range of 40–260 μM, 10–200 μM and 40–140 μM, respectively. Finally, the sensor was successfully applied to determine Fe3+, AA and H2O2 in real samples with the satisfactory recoveries (95.35%-104.10%) and repeatability (relative standard deviation (RSD) ≤ 1.68%). The continuous response fluorescence sensor prepared by simple green synthesis route has the characteristics of fast response, acceptable sensitivity and good selectivity.

Model predictive control of double-input buck converters

The control system of a multiple-input dc–dc converter should ensure the stability of output voltage and reasonably distribute the power of multiple-input voltage sources. In addition, there is mutual coupling between multiple closed control loops, which makes the design of the control system difficult. Based on the ability of model predictive control (MPC) to deal with constraints explicitly, a model predictive control algorithm based on the state-space averaging method is proposed for a double-input buck converter. First, a state-space averaging model of a double-input buck converter is established. Then, considering the power management of two input power supplies, a model predictive controller is designed based on the model by combining the input constraints with the objective function. Both simulation and experimental results show that the system has good steady-state accuracy and fast dynamic response characteristics under the action of model predictive controller.

Mitochondria-targeted dual-channel colorimetric and fluorescence chemosensor for detection of Sn2+ ions in aqueous solution based on aggregation-induced emission and its bioimaging applications

Several fluorescence and colorimetric chemosensory for Sn2+ detection in an aqueous media have been reported, but applications remain limited for discriminative Sn2+ detection in live human cells and zebrafish larvae. Herein, a mitochondria-targeted Sn2+ “turn-on” colorimetric and fluorescence chemosensor, 2CTA, with an aggregation-induced emission (AIE) response was developed. The sensing of Sn2+ was enabled by a reduction-enabled binding pathway, with the conversion of –C˭O groups to –C–OH groups at the naphthoquinone moiety. The color changed from light maroon to milky white in a buffered aqueous solution. The chemosensor 2CTA possessed the excellent characteristics of good water solubility, fast response (less than 10 s), and high sensitivity (79 nM) and selectivity for Sn2+ over other metal ions, amino acids, and peptides. The proposed binding mechanism was experimentally verified by means of FT-IR and NMR studies. The chemosensor 2CTA was successfully employed to recognize Sn2+ in live human cells and in zebrafish larvae. In addition, a colocalization study proved that the chemosensor had the ability to target mitochondria and overlapped almost completely with MitoTracker Red. Furthermore, a bioimaging study of live cells demonstrated the discriminative detection of Sn2+ in human cancer cells and the practical applications of 2CTA in biological systems.

Electro-hydraulic Composite Emergency Braking System Based on Frequency Reconstruction Control

For four-wheel independently driven (FWID) electric vehicle (EV), in order to guarantee braking reliability, hydraulic braking system and motor anti-drag braking system are usually used at the same time. In this paper, a novel electro-hydraulic composite braking control strategy is given to solve the distribution problem of braking torque between hydraulic braking torque and motor anti-drag braking torque. The high-frequency part of the desired braking torque is distributed to the motor brake through a high-pass filter so as to fully utilize the fast response characteristics of the motor. Meanwhile, the low-frequency part of the desired braking torque is distributed to the hydraulic brake through a low-pass filter so as to reduce the load of the motor. The cost functions are designed to determine the cut-off frequency of low-pass and high-pass filters. Through the joint simulation of Matlab/Simulink and TruckSim, the braking effect of the electro-hydraulic composite braking is better than that of pure hydraulic braking with no motor to modulate the braking torque.

Development of a dual-stage and visual-servo filming robot

This article presents the development of a visual-servo filming robot for dolly & truck style camera movement in filming applications. The robot was implemented with a fast-response slider as the upper stage on top of the slow-response tracked robot body as the lower stage, to improve target tracking performance. A new switching controller was developed, which controlled the stages’ motions by balancing and adjusting the weights of vision error and slider’s noncentering error of the upper stage, thus achieving tracking performance better than the traditional master–slave control strategy. The simulations were carried out to evaluate the tracking performance of the model, particularly focusing on evaluating how the dual stage improves the overall response of the model. The similar evaluation was executed experimentally as well. Both results confirm that the fast-response characteristics of the upper stage can compensate the slow dynamics of lower stage, the tracked robot which is inevitably heavy due to its composition.

A methane telemetry sensor based on near-infrared laser absorption spectroscopy

In order to detect methane leakage accurately and prompt, a methane telemetry sensor is demonstrated based on near infrared absorption spectroscopy and optimized wavelength modulation technology. The distributed feedback diode laser is applied as the light source to cover the selected absorption line of 6046 cm−1 to reduce the interference of CO2 and H2O. The waveform generator and the digital quadrature lock-in amplifier are constructed by the FPGA to produce driving signals and extract WMS-1f and 2f signals. And the “2f/1f” method is adopted to eliminate the environment influence such as light intensity fluctuations and improve the signal-to-noise ratio. This methane sensor has the characteristics of fast response and strong resistance to environmental interference and has great application prospect.

Structural Design and Physical Mechanism of Axial and Radial Sandwich Resonators with Piezoelectric Ceramics: A Review.

Piezoelectric ceramics are inexpensive functional materials which are widely used in sonar detection, home appliances, meteorological detection, telemetry and environmental protection and other applications. Sensors fabricated from these materials are compact and have fast response characteristics. Their underlying functional methodology is based on the direct piezoelectric effect whereby very small mechanical vibration signals are converted into electrical signals. Piezoelectric resonators are based on the reverse piezoelectric effect and they are widely used for the control of precision instruments and precision machinery, microelectronic components, bioengineering devices and other in applications requiring components to provide precision control of the relevant functional mechanism. In this paper, the structural evolution and design mechanism of sandwich resonators based on piezoelectric materials are reviewed, and the advantages and disadvantages of different structures are compared and analyzed. The goal is to provide a comprehensive reference for the selection, application and promotion of piezoelectric resonators and for future structural innovation and mechanism research relevant to sandwich resonators.

Optical Micro/Nanofiber-Enabled Compact Tactile Sensor for Hardness Discrimination.

Optical micro/nanofibers (MNFs) can be applied for ultrasensitive tactile sensing with fast response and compact size, which are attractive for restoring tactile information in minimally invasive robotic surgery and tissue palpation. Herein, we present a compact tactile sensor (CTS) with a diameter of 1.5 mm enabled by an optical MNF. The CTS provides continuous readouts for high-fidelity transduction of touch and pressure stimuli into interpretable optical signals, which permit instantaneous sensing of contact and pressure with pressure-sensing sensitivity as high as 0.108 mN-1 and a resolution of 0.031 mN. Working in pressing mode, the CTS can discriminate the difference in the hardness of two poly(dimethylsiloxane) (PDMS) slats (with shore A of 36 and 40) directly, a hardness resolving ability even beyond the human hands. Benefitting from the fast response feature, the CTS can also be operated in either scanning or tapping mode, making it feasible for hardness identification by analyzing the shape of the response curve. As a proof of concept, the hardness discrimination of a pork liver and an adductor muscle was experimentally demonstrated. Such MNF-enabled compact tactile sensors may pave the way for hardness sensing in tissue palpation, surgical robotics, and object identification.

An ultrafast response and precisely controllable soft electromagnet actuator based on Ecoflex rubber film filled with neodymium-iron-boron

Soft actuator is widely applied in soft grasp and artificial actuation. However, the characteristics of fast response and precise controllability are challenges for soft actuators. In this report, an ultrafast response and precisely controllable soft electromagnet actuator based on Ecoflex rubber film filled with neodymium-iron-boron is proposed. After optimizing the matrix and size of the actuator, the flexible magnetic actuator shows many merits including ultrafast response (<0.1 s), large elongation (<120%), excellent working stability, precision for long time working and customized designs. Based on customized patterns, different kinds of grippers have been made and they can realize the function of grasp and clutching of spherical and cylindrical objects. Furthermore, this actuator can be used on designed devices to build a pump system which can implement liquid injection and liquid blend. The proposed soft actuator has a great prospect in the practical application such as medical devices and soft robotics.

Development of a low capacitance two-axis piezoelectric tilting mirror used for optical assisted micromanipulation

A novel two-axis piezoelectric tilting mirror (PETM) was proposed for optical assisted micromanipulation, which avoided the shortcomings of high capacitance, relatively high cost and complex structure of general multi-axis steering mirrors using piezoelectric ceramic stack actuator. The developed PETM realized two-axis tilting motions via a simple bonded-type piezoelectric composite beam. The parametric sensitivity analyses of the tilting range and the fundamental frequency to the structural parameters were performed via FEM simulation, which facilitated serialization of the PETM. A tentative prototype was fabricated, and an experimental setup was built to carry out verification experiments. The preliminary characteristic tests including coupling motion, hysteresis and tilting motion resolution were accomplished to investigate its performances; the feasibility of closed-loop application of the PETM was confirmed by positioning and tracking experiments, which revealed its features of fast response, high positioning accuracy and feasible motion tracking capacity. Furthermore, the potential application of the PETM to manipulate laser beam in micromanipulation system was demonstrated preliminarily. In brief, the developed PETM realized low capacitance of 13.61 nF per axis to reduce the requirement for power amplifier. It can be a suitable device for optical assisted micromanipulation system by virtue of fast response, simple structure and extensible characteristics.

Performance Analysis of Giant Magnetostrictive Actuator and Its Application on Active Suspension of Train

Active suspension is considered to be a good way to improve the ride comfort of high-speed trains. According to the output index requirements of train’s active suspension, a giant magnetostrictive actuator(GMA) is proposed. This is mainly because giant magnetostrictive materials(GMM) has the characteristics of fast response, large output force and high energy conversion rate. It is verified by experiments that the output force is proportional to the excitation current. It is found in the experiment that the excitation frequency should be greater than 120Hz to obtain a stable output force, and it is also found that preload and excitation frequency will affect response time. On the basis of experiments, a 2-DOF physical and mathematical model of the vertical quarter train is built. An MPC algorithm is designed to control GMA active suspension. Through simulation analysis, the proposed control algorithm is compared with passive suspension and active suspension based on PID control algorithm. Both theory and practice show that the proposed control algorithm is effective.

A Fuzzy Hierarchical Strategy for Improving Frequency Regulation of Battery Energy Storage System

Battery energy storage systems (BESSs) can provide instantaneous support for frequency regulation (FR) because of their fast response characteristics. However, purely pursuing a better FR effect calls for continually rapid cycles of BESSs, which shortens their lifetime and deteriorates the operational economy. To coordinate the lifespan savings and the FR effect, this paper presents a control strategy for the FR of BESSs based on fuzzy logic and hierarchical controllers. The fuzzy logic controller improves the effect of FR by adjusting the charging/discharging power of the BESS with a higher response speed and precision based on the area control error (ACE) signal and the change rate of ACE in a non-linear way. Hierarchical controllers effectively reduce the life loss by optimizing the depth of discharge, which ensures that the state of charge (SOC) of BESS is always in the optimal operating range, and the total FR cost is the lowest at this time. The proposed method can achieve the optimal balance between ACE reduction and operational economy of BESS. The effectiveness of the proposed strategy is verified in a two-area power system.