Fast Response Applications Research Articles

Experimental dynamic thermal properties determination of EPDM/NBR panels with a shape stabilized Phase Change Material based on summer daily temperatures of four cities in Italy

In this work, the evaluation of E-PCM panels based on an elastomeric matrix containing a shape-stabilized paraffinic phase change material with a melting point of 28 °C was carried in a climatic chamber, simulating the summer daily temperature profile of four geographical locations in Italy at different latitudes. The characterization, carried out on testing boxes insulated using the E-PCM panels, allowed the determination of the delay (time lag) and of the dampening (decrement factor) in the propagation of the heat wave when passing from the outer to the inner surface of the walls; the results were correlated to two important parameters, the characteristic admittance and the heat capacity. From the difference between the heat fluxes on the outer and inner surface of the panels it was also possible to quantify the amount of stored energy and to do a comparison with a reference insulating panel (aerogel). Aerogel panels, despite the low thermal conductivity but due to the limited heat capacity and characteristic admittance, were unable to provide an effective insulation during summer conditions while E-PCM panels led to excellent outcomes. Results showed that with a peak of 33 °C in the external temperature, the phase change material limited the internal one at 27 °C with a maximum delay in the peak temperature of 6 h, an overall decrement factor of 0.4, time lag of 3 h and stored energy of 740 kJ/m2 per day. Finally, also the influence of the testing speed on the response of the E-PCM was evaluated through repetition of heating/cooling cycles in the temperature range 19–35 °C, highlighting the necessity of improving the thermal conductivity of the system in case of fast-response applications (cycle length < 3.5 h) and/or to optimize the PCM amount in the panel depending on the energy to be absorbed.

Co-fired lead-free piezoceramic multilayer actuators with ultrahigh electro-strain and remarkable comprehensive properties

Piezoceramic multilayer actuators (MLAs) offer remarkable advantages across various cutting-edge applications, yet the inferior piezoelectric strain and the confined assessment framework of lead-free MLAs constitute substantial obstacles to practical implementation. Herein, we judiciously introduce defect configurations into Ag/Pd co-fired potassium-sodium-niobate-based MLAs by tape-casting technique, achieving a large converse piezoelectric coefficient of 900 pm V−1 at 20 kV cm−1 for each layer, much superior than PZT-5 H counterparts. This lead-free MLA demonstrates fast response time, high temperature stability, impressive fatigue resistance, and good mechanical property. Unlike lead-based material suffering from abundant heat generated under alternating-current electric fields, the high-activated nanosized domains and higher thermal conductivity of this lead-free ceramic collaboratively minimize heat accumulation, presenting advancements for high-frequency utilizations. Moreover, experimental demonstrations reveal that the fast-steering mirror (FSM) apparatus equipped with the lead-free MLA showcases a rotational sensitivity comparable to PZT-based apparatus, exhibiting its extensive prospect for precise positioning and fast-response applications.

Guest Editorial: Special Issue on Power Converters and Control Techniques for Very Fast Response Applications

Efficient power converters capable of changing their output voltage at very high speeds (submicrosecond scale) are mandatory for very fast response (VFR) applications. They are necessary to regulate loads that demand very fast voltage changes and to supply high-frequency-pulsed loads for data processing, communication, and portable equipment. VFR converters likewise become necessary for applications in which the efficient generation of high-frequency waveforms is mandatory: envelope amplifiers (EAs) for envelope tracking (ET) techniques, visible light communication (VLC) transmitters using light-emitting diodes (LEDs), switched-mode radio frequency power amplifiers and high-frequency inverters, among others.

Joint estimation of gas and wind maps for fast-response applications

This work addresses 2D gas and wind distribution mapping with a mobile robot for real-time applications. Our proposal seeks to estimate how gases released in the environment are distributed from a set of sparse and uncertain gas-concentration and wind-flow measurements; such that by exploiting the high correlation between these two magnitudes we may extrapolate their value for unexplored areas. Furthermore, because the air currents are completely conditioned by the environment, we assume a priori knowledge of static elements such as walls and obstacles when estimating both distribution maps. In particular, this joint estimation problem is modeled as a multivariate Gaussian Markov random field (GMRF), combining gas and wind observations under a common maximum a posteriori estimation problem. It considers two lattices of cells (a scalar gas-concentration field and a wind vector field) which are correlated following the physical laws of gas dispersal and fluid dynamics. Finally, we report various experiments in which our proposal is compared to other stochastic gas and gas-wind modeling methods under simulation, to evaluate their performance against a computer fluid-dynamics generated ground-truth, as well as under real and uncontrolled conditions.

Design of oneM2M-Based Fog Computing Architecture

Internet of Things (IoT) technology could provide solutions for many real-world applications, and Big Data analysis of IoT continues the key to realizing smart cities. However, IoT cloud computing cannot yet fully meet the requirements of the low latency and fast response for applications, such as public safety and emergency response services. These deficiencies could be addressed by Fog Computing, which uses front-end devices or serially connected terminal devices to conduct data storage, calculations, or related decentralized control management through decentralized collaborative architecture. According to the original oneM2M IoT architecture, it takes 251.2–537.2 ms of transmission time, for high-resolution image data at front-end edge nodes, but it fails to meet the requirements of low-latency and fast-response applications. To address this, we propose a novel oneM2M-based Fog Computing architecture under which adjacent Fog nodes can coordinate and cooperate with each other to deal with operational requirements. Operations are no longer constrained by a node’s ability to perform tasks or by the requirement of forwarding tasks to the cloud for execution. The proposed computing architecture could transmit high-resolution image data between Fog nodes and then could reduce the transmission time to 16.7–46.2 ms, which is a 94.1% reduction compared with the original oneM2M architecture. In summary, this method could provide low latency and fast response in Fog Computing by maximizing the reduction of the overall end-to-end delay.

Elucidating the role of the ionic liquid in the actuation behavior of thermo-responsive ionogels

The characterization of thermo-responsive ionogels with electrochemical impedance spectroscopy using gold interdigitated electrodes is described. The ionogels are synthesized using poly(N-isopropylacrylamide) as thermo-responsive gel and polymerized in the presence of two ionic liquids: ethyl-3-methylimidazolium ethyl sulfate or trihexyltetradecyl-phosphonium dicyanamide. The changes on the charge-transfer resistance show a clear dependence on the porosity and on the chemical structure of the ionogel. Moreover, the charge-transfer resistance parameter can be used to track in real time the photopolymerization and the hydration process of the ionogels. After exposing them to several drying/rehydration cycles the switching performance is fully understood. The results show that the ionogel with 1-ethyl-3-methylimidazolium ethyl sulfate requires less time to absorb and release water and is excellent for fast response applications. On the contrary, the one with the trihexyltetradecyl-phosphonium dicyanamide ionic liquid presents a more robust actuator behavior and a huge potential to be included in long-term applications. Finally, the observed microstructures have been correlated with the measured charge-transfer resistance providing a better understanding of the actuator behavior of these smart materials.

Bayesian Inference aided analog downscaling for near-surface winds in complex terrain

Assessing atmospheric boundary layer flows in complex terrain for short-range real-time applications demands fast and reliable downscaling from coarser-resolution meteorological data to the relevant scale. An ideal statistical downscaling numerical experiment was performed for surface winds above complex terrain in Israel's northern Negev desert region. Dynamical downscaling have been performed by the WRF model to create a historical database by the following two sets. The first set used 5 nested domains from 40.5km to 0.5km. The second set used 3 nested domains ranging from 40.5km to 4.5km. The 4.5km data (stage 2) was defined as predictors while data on 0.5km (stage 1) served as predictands for statistical downscaling. Two statistical downscaling algorithms: minimal distance analog and a Bayesian inference aided analog (hereafter Bayesian algorithm) were tested by the above data. Unlike most analog algorithms, the Bayesian algorithm refers to the probability to get the best analog instead of the minimal differences between predictands. The comparison of the two algorithms shows that the Bayesian approach yields improved results. The Bayesian algorithm reproduces the 0.5km resolution dynamically downscaled surface winds with an average absolute direction difference of 43 and 20 for calm winds and moderate/strong winds respectively. Its average wind speed error is ~1.1ms−1. ~40days are sufficient to create a representative database. Given the database, the procedure is extremely fast (a few seconds) and easy to operate, which makes it suitable for real-time non-expert fast-response applications.

52.4: Fast Response LCD with Alternate Vertical and Fringe Field Switching

AbstractThe electro‐optic properties of a vertical aligned liquid crystal display device with three‐electrode structure for fast response applications have been studied. The fast response is realized by a three‐electrode structure that can produce electric field horizontally and vertically in an alternative way to turn‐on and turn‐off the LC cell, so that both the turn‐on and turn‐off processes are driven by electric field. The response time, transmittance‐voltage curve, and the bias effect were tested for cells with various stripe widths/gaps. A total response time (rise‐time plus fall‐time) of 1.88 ms was obtained for a vertically‐aligned nematic cell.

The electro-optic properties of a vertically aligned fast response liquid crystal display with three-electrode driving

The electro-optic properties of a vertically aligned liquid crystal device with a three-electrode structure for fast response applications have been studied. The fast response is realized by a three-electrode structure that can produce an electric field horizontally and vertically, alternately to turn the liquid crystal cell on and off so that both the turn-on and turn-off processes are driven by the electric field. The response time, transmittance–voltage curve, and the bias effect were characterized for cells with various stripe widths/gaps. A simple theoretical model was used to explain the bias voltage dependence of the transmission with good agreement with the experimental findings. A total response time (rise-time plus fall-time) of 1.88 ms was obtained.

The Electro-Optic Properties of a Fast Response, Three-Electrode Liquid Crystal Device

The optical properties of a new hybrid aligned nematic liquid crystal (LC) device (Jpn. J. Appl. Phys. 42 (2003) L763) with three-electrode structure for fast response applications have been systematically studied. The transmission shows a clear dependence on the electrode structure, the bias voltage and LC material. The highest transmittance is obtained by optimizing the electrode structure and the bias voltage for a certain cell gap and LC material. The response time is dependent on LC material, but is not sensitive to the bias voltage and cell structure in our experiment.