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Fog computing (FC) designates a decentralized computing structure placed among the devices that produce data and cloud. Such flexible structure empowers users to place resources to increase performance. However, limited resources and low delay services obstruct the application of new virtualization technologies in the task scheduling and resource management of fog computing. Scheduling and load balancing (LB) in the cloud computing have been widely studied. However, countless efforts in LB have been proposed in the fog architectures. This presents some enticing challenges to solve the problem of how tasks are routed between different physical devices between fog nodes and cloud. Within fog, due to its mass and heterogeneity of devices, the scheduling is very difficult. There are still few studies that have been conducted. LB is a very interesting and important study area in FC as it aims to achieve high resource utilization. There are various challenges in LB such as security and fault tolerance. The main objective of this paper is to introduce an effective dynamic load balancing technique (EDLB) using convolutional neural network and modified particle swarm optimization, which is composed of three main modules, namely: (i) fog resource monitor (FRM), (ii) CNN-based classifier (CBC), and (iii) optimized dynamic scheduler (ODS). The main purpose of EDLB is to achieve LB in FC environment via dynamic real-time scheduling algorithm. This paper studies the FC architecture for Healthcare system applications. The FRM is responsible for monitoring each server resource and save the server's data into table called fog resources table. The CNN-based classifier (CBC) is responsible for classifying each fog server to suitable or not suitable. The optimized dynamic scheduler (ODS) is responsible for assigning the incoming process to the most appropriate server. Comparing EDLB with other previous LB algorithms, it reduces the response time and achieves high resource utilization. Hence, it is an efficient way to ensure the continuous service. Accordingly, EDLB is simple and efficient in real-time systems in fog computing such as in the case of healthcare system. Although several methods in LB for FC have been introduced, they have many limitations. EDLB overcomes these limitations and achieves high performance in various scenarios. It achieved better makespan, average resource utilization and load balancing level as compared to previously mentioned LB algorithms.

Continuous, wide field-of-view, high-efficiency, and fast-response beam steering devices are desirable in a plethora of applications. Liquid crystals (LCs)—soft, bi-refringent, and self-assembled materials which respond to various external stimuli—are especially promising for fulfilling these demands. In this paper, we review recent advances in LC beam steering devices. We first describe the general operation principles of LC beam steering techniques. Next, we delve into different kinds of beam steering devices, compare their pros and cons, and propose a new LC-cladding waveguide beam steerer using resistive electrodes and present our simulation results. Finally, two future development challenges are addressed: Fast response time for mid-wave infrared (MWIR) beam steering, and device hybridization for large-angle, high-efficiency, and continuous beam steering. To achieve fast response times for MWIR beam steering using a transmission-type optical phased array, we develop a low-loss polymer-network liquid crystal and characterize its electro-optical properties.

Electrooptic modes with fast response and high contrast ratio are highly desirable in modern photonics and displays. Ferroelectric liquid crystals (FLCs) are especially promising for fulfilling these demands by employing photoalignment technology in FLC cells. Three electrooptic modes including surface stabilized FLC (SSFLC), deformed helix ferroelectric (DHF) mode, and electrically suppressed helix (ESH) mode are reviewed with the corresponding electrooptic effects like bi- and multi-stable switching, continuous modulation of grayscale or phase, and high contrast switching. The general operation principles FLC electrooptic modes are described, and then the characteristics of each modes for potential applications are summarized. With the advantages of controllable anchoring energy, the photoalignment provides FLC samples with uniform alignment and high contrast ratio. The fast FLCs with a high resolution and high contrast can be used in the next generation display including field sequential color FLC microdisplays, as well as switchable 2D/3D televisions.

We demonstrated a fast switchable dual-model grating based on a polymer-stabilized sphere phase liquid crystal. To form binary periodicity layers, the polymer-stabilized sphere phase liquid crystal precursor was sequence ultraviolet cured at an isotropic and sphere phase. This grating jointly modulated both the phase and the amplitude, had six times the diffraction efficiency of that fabricated with polymer-stabilized blue phase liquid crystal. Moreover, the dual-model tunable grating shown polarization-independent and submillisecond response time, which may hold a great potential application in diffractive optics.

Recently, flexible airflow sensors have attracted significant attention due to their impressive characteristics and capabilities for airflow sensing. However, the development of high‐performance flexible airflow sensors capable of sensing airflow over large areas remains a challenge. In this work, it is proposed that a hair‐like flexible airflow sensor, based on laser direct writing and electrostatic flocking, offers an efficient technology for airflow sensing. The airflow sensor exhibits high sensitivity (5.25% s m−1), fast response time (39.83 ms), a wide detection range (3.48 – 18.36 m s−1), minimal disturbance to the airflow field, simplified fabrication, and cost efficiency. The airflow sensor, with excellent conformal monitoring capabilities, is capable to detect airflow on different surfaces. The sensor's excellent flexibility and efficient fabrication process enable it to be easily integrated into arrays and deployed on large‐area surfaces to provide information, including airflow velocity, direction, and point of incidence. The hair‐like airflow sensor has significant potential for applications in environmental monitoring, intelligent robots, wearable electronics, and tactile sensing. A hair‐like flexible airflow sensor is designed for large‐area airflow sensing with carbon fibers implanted on a laser‐induced graphene substrate. The flexible airflow sensor features a wide detection range and fast response time, effectively identifying airflow changes. It is expected to demonstrate reliability in large‐area airflow sensing in numerous applications through its excellent performance.

Two-dimensional (2D) materials have recently provided a new perspective on optoelectronics because of their unique layered structure and excellent physical properties. However, their potential use as optoelectric devices has been limited by the trade-off between photoresponsivity and response time. Here, based on a vertically stacked atomically thin p-n junction, we propose a gap-mode plasmon structure that simultaneously enables enhanced responsivity and rapid photodetection. The atomically thin 2D materials act as a spacer for enhancing the gap-mode plasmons, and their short transit length in the vertical direction allows fast photocarrier transport. We demonstrate a high responsivity of up to 8.67 A/W with a high operation speed that exceeds 35 MHz under a 30 nW laser power. Spectral photocurrent, absorption, and a numerical simulation are used to verify the effectiveness of the gap-mode plasmons in the device. We believe that the design strategy proposed in this study can pave the way for a platform to overcome the trade-off between responsivity and response time.

Optics-based sensors, called optodes, for oxygen are used for routine operations on autonomous instrumentation and profiling platforms with great success. Observations of oxygen gradients with high spatial and temporal resolution become increasingly important, while shortcomings still exist, namely, time constant problems, stability issues, or accuracy levels, that limit leveraging their full scientific and operational potential. Here, we demonstrate the utility of a novel, although currently not commercially available optode, the HydroFlash O 2 . It was manufactured by Kongsberg Maritime Contros GmbH between 2014 and 2019, and peer-reviewed studies illustrate its use until today. Our work comprises its first integrated characterization with data from 13 HydroFlash O 2 optodes assessing oxygen, temperature, salinity and hydrostatic pressure dependence, long-term stability and drift, response time, and air-calibration compatibility. We multi-point calibrated this optode up to a root mean square error (RMSE) of <1  µ mol L -1 (mean RMSE: 1.79 ± 0.50 µ mol L -1 ), depending on the fit model type. Our laboratory setup yielded a temperature-dependent response time of τ 63%  = 3.31 ± 0.58 s, showing no significant difference between a weakly turbulent and turbulent flow, and was at least 50 % faster compared to the two most common optodes in oceanography, i.e., 4330 (Aanderaa) and SBE 63 (Sea-Bird Scientific). We assessed its pressure dependence between 0–5797 dbar, yielding an overall factor of 2.372 ± 0.409 % per 1,000 dbar based on three multi-point calibrated, drift-corrected optodes and five CTD (conductivity - temperature - depth) profiles. Ship-underway, mooring, and CTD-cast applications promise high-quality observations, including fast oxygen level changes. The optode revealed a strong sensitivity of the sensor spot, causing erroneous oxygen measurements when exposed to direct solar irradiation during an Argo float test profile. The drift assessment covering a maximum time span of approximately 3 years is based on two optodes and yielded linear (R 2 = 0.98) and exponential ( τ = 2.35 ± 0.30 yr, 95 % CI) drift behaviors. The HydroFlash O 2 is applicable in low to high oxygen, pressure, and temperature conditions, yet we do not call for additional performance studies unless the manufacturer reactivates its production and reduces sensor spot issues. In an ocean affected by climate change, reliable oxygen optodes will contribute crucial information about the global oxygen and carbon budget, e.g., through observations in the mixed layer, thermocline, or deep sea, and require assessments of existing and promising instrumentation.

'LCD vs. OLED: who wins?' is a heated debatable question. Each technology has its own pros and cons. We review recent advances in liquid crystal displays (LCDs) from three performance metrics: response time, contrast ratio, and viewing angle, which determine the final-perceived image quality. To enhance LCD performance, ultra-low viscosity materials, quantum dots, and new device structures have been explored, and their working mechanisms investigated. Another round of LCD innovation is around the corner.

Purpose Successive Approximation Register-Analog to Digital Converter (SAR-ADC) has been achieved notable technological advancement since the past couple of decades. However, it’s not accurate in terms of size, energy, and time consumption. Many projects proposed to make it energy efficient and time-efficient. Such designs are unable to deliver two parallel outputs. Design/methodology/approach To this end, this study introduced an ultra-low-power circuitry for the two blocks (bootstrap and comparator) of 11-bit SAR-ADC. The bootstrap has three sub-parts: back-bone, left-wing and right-wing, named as bat-bootstrap. The comparator block has a circuitry of the two comparators and an amplifier, named as comp-lifier. In a bat-bootstrap, the authors plant two capacitors in the back-bone block to avoid the patristic capacitance. The switching system of the proposed design highly synchronized with the short pulses of the clocks for high accuracy. This study simulates the proposed circuits using a built-in Cadence 90 nm Complementary Metal Oxide Semiconductor library. Findings The results suggested that the response time of two bat-bootstrap wings and comp-lifier are 80 ns, 120 ns, and 90 ns, respectively. The supply voltage is 0.7 V, wherever the power consumption of bat-bootstrap, comp-lifier and SAR-ADC are 0.3561µW, 0.257µW and 35.76µW, respectively. Signal to Noise and Distortion Ratio is 65 dB with 5 MHz frequency and 25 KS/s sampling rate. The input referred noise of the amplifier and two comparators are 98µVrms, 224µVrms and 224µVrms, respectively. Originality/value Two basic circuit blocks for SAR-ADC are introduced, which fulfill the duality approach and delivered two outputs with highly synchronized clock pulses. The circuit sharing concept introduced for the high performance SAR-ADCs.

Purpose RF transceiver module is considered a vital part of any wireless communication system. This module consists of two important parts the RF transceiver and analog-to-digital converter (ADC). Usually, both these parts – RF transceiver and ADC – are used to enhance the perspective of size and power. The data processing in 4G communication makes hurdles and need research attention to make it faster and smaller in size. Accuracy and fast processing are the critical challenges in the modern communication system. Design/methodology/approach After theoretical and practical investigations, this research work proposes key new techniques for the RF transceiver module. These techniques will make RF transceiver small, power-efficient and on the other hand, make dual SAR-ADC more effective as well. The proposed design has no intermediate frequency where the RF transceiver is reduced its major blocks from five to four, which includes crystal oscillator, phase lock loop, power amplifier and low noise amplifier. Moreover, the shared circuitry is introduced in the architecture of the SAR-ADC for the production of dual outputs, specifically in bootstrapped switch and comparator. Findings The miniaturized RF transceiver and SAR-ADC are well tested separately before the plantation on the printed circuit board (PCB). The operating voltage and frequency of the RF transceiver module are 1.2 V and 5.8 GHz, where the sampling rate, bandwidth and output power are 25 MHz, 200 MHz and 5 dBm, respectively. The core area of the PCB is 58.13 mm2. The bandwidth efficiency is 93% using surface acoustic wave less transmitter. The circuit is based on the library of 90 nm CMOS technology. Originality/value The entire circuit is highly synchronized with the input and reference clocks to avoid self-interference.