Topic Review
Alternating Current Loss of Superconductors
Alternating current (AC) loss is generated due to the movement of magnetic vortices within the superconductor when experiencing time-varying currents or magnetic fields (or both). AC loss can be categorized into transport current loss and magnetization loss based on the AC source. Particularly, when a superconductor carries a direct current (DC) and is simultaneously exposed to an AC field, dynamic resistance occurs and leads to dynamic loss. Quantification and minimization of AC loss are crucial because the produced heat can not only present severe challenges to the cryogenic systems but also impair the reliability of superconducting devices, leaving a safety hazard. To quantify the AC loss of superconductors, analytical formulae, numerical models, and experimental measurements have been widely adopted. Concerning AC loss minimization techniques, the modification of superconductor structures (filamentation and twisting), flux diverters, as well as winding techniques have been widely exploited. This entry serves to clarify the characteristics and quantification methods of AC loss as well as its minimization techniques in superconductors. It is believed to help deepen the understanding of AC loss and deliver a helpful guideline for future research efforts.
  • 1868
  • 14 Sep 2021
Topic Review
Visible Light Communication
Visible Light Communication (VLC) technology is an emerging technology using visible light modulation that, in the modern world, will mainly facilitate high-speed internet connectivity. VLC technology employs visible light for communication to facilitate high-speed internet connectivity exclusively in the indoor environment. This particular report will tell about some potential applications of VLC and the implementation of LEDs and some of the factors affecting the modulation bandwidth of LEDs for the VLC application.
  • 1861
  • 11 Nov 2020
Topic Review
Autonomous Navigation
Autonomous navigation is a very important area in the huge domain of mobile autonomous vehicles.  Sensor integration is a key concept that is critical to the successful implementation of navigation.  As part of this publication, we review the integration of Laser sensors like LiDAR with vision sensors like cameras.  The past decade, has witnessed a surge in the application of sensor integration as part of smart-autonomous mobility systems. Such systems can be used in various areas of life like safe mobility for the disabled, disinfecting hospitals post Corona virus treatments, driver-less vehicles, sanitizing public areas, smart systems to detect deformation of road surfaces, to name a handful.  These smart systems are dependent on accurate sensor information in order to function optimally. This information may be from a single sensor or a suite of sensors with the same or different modalities. We review various types of sensors, their data, and the need for integration of the data with each other to output the best data for the task at hand, which in this case is autonomous navigation. In order to obtain such accurate data, we need to have optimal technology to read the sensor data, process the data, eliminate or at least reduce the noise and then use the data for the required tasks. We present a survey of the current data processing techniques that implement integration of multimodal data from different types of sensors like LiDAR that use light scan technology, various types of Red Green Blue (RGB) cameras that use optical technology and review the efficiency of using fused data from multiple sensors rather than a single sensor in autonomous navigation tasks like mapping, obstacle detection, and avoidance or localization. This survey will provide sensor information to researchers who intend to accomplish the task of motion control of a robot and detail the use of LiDAR and cameras to accomplish robot navigation
  • 1847
  • 30 Oct 2020
Topic Review
Crowd Sensing
Crowd sensing (also known as participatory sensing, or mobile crowdsensing) is a means of collecting people’s surrounding information via mobile sensing devices. Its highly expressive and powerful sensing capabilities can carry out a big sensing project by fragmenting tasks into small pieces. The key to success is to get more participants to collect higher quality data. 
  • 1774
  • 28 Oct 2020
Topic Review
Electrical Double-Layer Capacitors
Capacitors with superior characteristics (called supercapacitors), which are unavailable in conventional batteries, exhibit excellent functionality in many areas, including power density, charge/discharge cycles, operation over a wide temperature range, and reliability, which have been noted as limits of batteries.
  • 1728
  • 08 Jan 2021
Topic Review
Optical Phase Shifters
Optical phase shifters have the functionality to control the phase of light by a change in the effective refractive index. In a Si photonics platform, it is an essential part composing optical modulators as well as switches in Si photonics. The realization of a silicon optical phase shifter marked a cornerstone for the development of silicon photonics, and it is expected that optical interconnects based on the technology relax the explosive datacom growth in data centers. High-performance silicon optical modulators and switches, integrated into a chip, play a very important role in optical transceivers, encoding electrical signals onto the light at high speed and routing the optical signals, respectively. The development of the devices is continuously required to meet the ever-increasing data traffic at higher performance and lower cost.
  • 1694
  • 08 Jun 2021
Topic Review
Laser Absorption Spectroscopy
Laser absorption spectroscopy (LAS) is an absorption spectroscopic method that employs a laser as the light source and measures the chemical concentration based on detection of a variation of laser beam intensity after transmission along the optical path. 
  • 1671
  • 10 Sep 2020
Topic Review
Edge Couplers
Silicon photonics has drawn increasing attention since recent decades and is promising to act as a key technology for future daily applications due to its various merits including ultra-low cost, high integration density owing to the high refractive index of silicon and compatibility with current semiconductor fabrication process. Optical interconnects is an important issue in silicon photonic integrated circuits to transmit light and fiber-to-chip optical interconnects is vital in application scenarios like data centers and optical transmission systems. There are mainly two categories of fiber-to-chip optical coupling, that is off-plane coupling and in-plane coupling. Grating couplers work under the former category while edge couplers function as in-plane coupling. In this paper, we mainly focus on edge couplers in silicon photonic integrated circuits. We deliver an introduction to the research background, operation mechanism and design principles of silicon photonic edge couplers. The state-of-the-art of edge couplers is reviewed according to different configurations as to the device structure, identifying the performance, fabrication feasibility and applications. In addition, a brief comparison between edge couplers and grating couplers is conducted. Packaging issue is also discussed and several prospective techniques for further improvements of edge couplers are proposed.
  • 1615
  • 27 Oct 2020
Topic Review
Networked Control System
An NCS consists of control loops joined through communication networks in which both the control signal and the feedback signal are exchanged between the system and the controller.
  • 1591
  • 01 Apr 2021
Topic Review
Medium-Voltage Switchgear Condition Monitoring
Switchgear are a key component of the electrical grid. They serve both protective and control roles in distribution electric power with in the grid. It is therefore important to monitor and predict the condition of these assets. Thereby, condition monitoring is divided into three main tasks: breaker drive monitoring, thermal monitoring and partial discharge monitoring. This encyclopedia article provides an overview of the potential failure modes and monitoring techniques. More details can be found in an exhaustive review article, cited below.
  • 1550
  • 29 Oct 2020
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