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Topic Review
High Temperature Superconducting Flux Pumps for Contactless Energization
The development of superconducting technology has seen continuously increasing interest, especially in the area of clean power systems and electrification of transport with low CO2 emission. Electric machines, as the major producer and consumer of the global electrical energy, have played a critical role in achieving zero carbon emission. The superior current carrying capacity of superconductors with zero DC loss opens the way to the next-generation electric machines characterized by much higher efficiency and power density compared to conventional machines. The persistent current mode is the optimal working condition for a superconducting magnet, and thus the energization of superconducting field windings has become a crucial challenge to be tackled, to which high temperature superconducting (HTS) flux pumps have been proposed as a promising solution. An HTS flux pump enables current injection into a closed superconducting coil wirelessly and provides continuous compensation to offset current decay, avoiding excessive cryogenic losses and sophisticated power electronics facilities.
  • 748
  • 01 Jun 2022
Topic Review
Metamaterial-Based Absorptive Structures
Metamaterials are artificially-engineered synthetic materials having periodic arrangements of sub-wavelength metallic/dielectric structures or resonators. Metamaterials have demanded a lot of recognition, due to their exotic and unique attributes such as negative-refraction, microwave cloaking, absorption of the inverse Doppler effect, etc. After the investigation of the first ‘perfect meta-absorber’ proposed in 2008, metamaterial absorbers (MMAs) have drawn significant interest from the microwave and optics community. These MMAs have multifarious features compared with the conventional Salisbury absorbers, such as a low-profile and light weight. Moreover, they are thinner, more compact, and more efficient than conventional absorbers. They have many applications for wireless communication and other optical systems, including MIMO antenna isolation, EM interference reduction, stealth technology, and solar photovoltaics.
  • 748
  • 16 Nov 2022
Topic Review
Thermomechanical Stress in Microelectronics Packaging Durability
Reflow soldering is the main connection technology of surface mounting. Firstly, the solder in paste form is stencil-printed onto the solder pads of the applied substrate, and then surface mounted devices are placed onto the solder deposits. Finally, the whole assembly is heated over the melting temperature of the solder alloy, which melts and forms solder joints. Surface mounting technology needs a low defect rate which is determined by process parameters, material properties, and the printed circuit board design. Accompanying the experiment and measurement, the identification and elimination of root causes can be effectively improved with numerical modelling, which also grants details to such physical mechanisms that are not even conventionally measurable.
  • 748
  • 25 Aug 2023
Topic Review
Sustainable Energy Systems in Southern African Development Community
The Southern African Development Community (SADC) region includes all the countries located in the southernmost region of Africa, with the Democratic Republic of Congo on the northern boundary of the region. In 2017, more than 341 million people were living in SADC, representing around 33% of SSA’s total population of 1.02 billion, and with an annual growth rate of 2%.  Hydropower is the main renewable energy source in most member states, including Angola, the Democratic Republic of Congo, Lesotho, Malawi, Mozambique, Namibia, and Zambia. Therefore, to accelerate energy access for a higher share of the population, countries like South Africa, Botswana, and Zimbabwe are continuing to exploit mainly non-renewable energy sources, particularly coal. Additionally, SADC needs to face the reduction of GHG emissions to ensure sustainability, and to this end, every effort should be made to guarantee carbon neutrality and a zero-carbon economy.
  • 744
  • 04 Nov 2022
Topic Review
Energy Efficiency of Induction Motor Drives
Despite activities to introduce low-carbon energy sources worldwide, the share of conventional facilities burning organic fuels remains high. One approach to address this problem is to look for solutions to reduce energy consumption. There are various research projects in the area of energy efficiency that lead to diverse results—such as models, methodologies, new data and theories. On the other hand, induction motor drives are becoming a major consumer of electric power because of their wide range of applications. 
  • 744
  • 26 Oct 2023
Topic Review
Architecture-Level Optimization on Silicon Photomultipliers
Sensors based on single-photon avalanche diodes (SPADs) are nowadays employed in a wide variety of single-photon counting and fast-timing applications, e.g., high-energy physics; time of flight (TOF) ranging and 3D imaging; Raman spectroscopy; and bio-medicine, including fluorescence-lifetime imaging microscopy and positron emission tomography (PET), to name a few. SiPMs are the most common sensors in PET applications, where they detect the light produced by the interaction between gamma photons and scintillator crystals. 
  • 743
  • 07 Feb 2022
Topic Review
Spiking Neural P Systems
Spiking neural P system (SNPS) is a popular parallel distributed computing model. It is inspired by the structure and functioning of spiking neurons. It belongs to the category of neural-like P systems and is well-known as a branch of the third generation neural networks. SNPS and its variants can perform the task of fault diagnosis in power systems efficiently.
  • 739
  • 30 Jun 2021
Topic Review
Bioretention Systems Optimization and Design Characterization Model
Urban stormwater has become a persistent concern on a global scale due to its adverse environmental implications. It is the prime vector of aquatic contaminants worldwide that causes pollutants when water bodies drain. Bioretention systems are increasingly used to alleviate setbacks associated with stormwater run-off in urban locales. It has played a substantial role in the implementation of low impact development (LID), a concept that addresses urban stormwater problems caused by land changes and development. The use of LID technologies is an innovative approach.
  • 739
  • 30 Jun 2022
Topic Review
Decoupling Recurrent Neural Networks in Training and Testing
Recurrent neural networks (RNN) have been shown to outperform other architectures when processing temporally correlated data, such as from wireless communication signals. However, traditional usage assumes a fixed observation interval during both training and testing despite the sample-by-sample processing capabilities of RNNs. Rather than assuming that the testing and observation intervals are equivalent, the observation intervals can be “decoupled" or set independently. This opens the door for processing variable sequence lengths in inference  by defining a decision criteria. "Decoupling" can potentially reduce training times and will allow for trained networks to be adapted to different applications without retraining -- including applications in which the sequence length of the signal of interest may be unknown. 
  • 739
  • 22 Jul 2022
Topic Review
Plasmonic Circuitry
Plasmonics is the study of plasmons, quasiparticles of plasma oscillation in solids such as metals, semi-metals, metal oxides, nitrides, doped semiconductors, etc. An effort is currently being made to implement plasmons in electric circuits, or in an electric circuit analog, to combine the size efficiency of electronics with the data capacity of photonic integrated circuits. Plasmonics can be understood as "light-on-metal-dielectric-interfaces," where electrons oscillate at the surface of a metal due to strong resonant interactions with the electric field of incident light. Due to the high scattering rate of electrons, ohmic losses in plasmonic signals are generally large, which limits the signal transfer distances to the sub-centimeter range, unless hybrid optoplasmonic light guiding networks, or plasmon gain amplification are used. Both surface plasmon polaritons propagating along the metal-dielectric interfaces and localized surface plasmon modes supported by metal nanoparticles are characterized by large momentum values, which enable strong resonant enhancement of the local density of photon states, and can be utilized to enhance weak optical effects of opto-electronic devices.
  • 737
  • 27 Sep 2022
Topic Review
Power-Flow Study
In power engineering, the power-flow study, or load-flow study, is a numerical analysis of the flow of electric power in an interconnected system. A power-flow study usually uses simplified notations such as a one-line diagram and per-unit system, and focuses on various aspects of AC power parameters, such as voltages, voltage angles, real power and reactive power. It analyzes the power systems in normal steady-state operation. Power-flow or load-flow studies are important for planning future expansion of power systems as well as in determining the best operation of existing systems. The principal information obtained from the power-flow study is the magnitude and phase angle of the voltage at each bus, and the real and reactive power flowing in each line. Commercial power systems are usually too complex to allow for hand solution of the power flow. Special purpose network analyzers were built between 1929 and the early 1960s to provide laboratory-scale physical models of power systems. Large-scale digital computers replaced the analog methods with numerical solutions. In addition to a power-flow study, computer programs perform related calculations such as short-circuit fault analysis, stability studies (transient and steady-state), unit commitment and economic dispatch. In particular, some programs use linear programming to find the optimal power flow, the conditions which give the lowest cost per kilowatt hour delivered. A load flow study is especially valuable for a system with multiple load centers, such as a refinery complex. The power flow study is an analysis of the system’s capability to adequately supply the connected load. The total system losses, as well as individual line losses, also are tabulated. Transformer tap positions are selected to ensure the correct voltage at critical locations such as motor control centers. Performing a load flow study on an existing system provides insight and recommendations as to the system operation and optimization of control settings to obtain maximum capacity while minimizing the operating costs. The results of such an analysis are in terms of active power, reactive power, magnitude and phase angle. Furthermore, power-flow computations are crucial for optimal operations of groups of generating units. The Open Energy Modelling Initiative promotes open source load-flow models and other types of energy system models.
  • 737
  • 06 Dec 2022
Topic Review
Stress Detection Using Empatica E4 and Machine Learning
In response to challenging circumstances, the human body can experience marked levels of anxiety and distress. To prevent stress-related complications, timely identification of stress symptoms is crucial, necessitating the need for continuous stress monitoring.
  • 736
  • 22 Nov 2023
Topic Review
Conspectus of Photovoltaic Systems
A photovoltaic (PV) system is composed of a PV panel, controller and boost converter. The PV panel is a power-generating device. A controller is an electronic device that controls the circulating circuits in a PV system to collect as much PV output as possible from the solar panel. The boost converter is an intermediate device that regulates the PV output based on the duty cycle provided by the controller.
  • 734
  • 19 Jan 2023
Topic Review
Non Linear Current-Voltage Characteristics
The current-voltage (IV) curve of a solar photovoltaic (PV) array provides valuable insights into its behavior under varying conditions, including partial shading. Under normal, unshaded conditions, the IV curve depicts a characteristic shape where the current increases linearly with voltage until it reaches a peak known as the maximum power point (MPP). 
  • 734
  • 16 Oct 2023
Topic Review
Applications of the Smart Grid Served by 6G
A well-functioning smart grid is an essential part of an efficient and uninterrupted power supply for the key enablers of smart cities. To effectively manage the operations of a smart grid, there is an essential requirement for a seamless wireless communication system that provides high data rates, reliability, flexibility, massive connectivity, low latency, security, and adaptability to changing needs.
  • 734
  • 27 Oct 2023
Topic Review
Idiot Light
An idiot light, sometimes "tell-tale" or "warning light", is an indicator of malfunction of a system, indicated by a binary (on/off) illuminated light, symbol or text legend. The "idiot light" terminology arises from popular frustration with automakers' use of lights for crucial functions which could previously be monitored by gauges, so a troublesome condition could be detected and corrected early. Such early detection of problems with, for example, engine temperature or oil pressure or charging system operation is not possible via an idiot light, which lights only when a fault has already occurred – thus providing no advance warnings or details of the malfunction's extent. The Hudson automobile company was the first to use lights instead of gauges for oil pressure and the voltmeter, starting in the mid-1930s.
  • 733
  • 01 Dec 2022
Topic Review
Power Electronics Revolutionized
Key parameters examined include bandgap, critical electric field, electron mobility, voltage/current ratings, switching frequency, and device packaging. The historical evolution of each material is traced from early research devices to current commercial offerings. Significant focus is given to SiC and GaN as they are now actively competing with Si devices in the market, enabled by their higher bandgaps.
  • 733
  • 13 Nov 2023
Topic Review
Power Grid Infrastructural Resilience against Extreme Events
Extreme weather events are one of the main causes of large-scale power outages in distribution systems. The changing climate has led to an increase in the frequency and severity of these events, which, if not mitigated, are expected to lead to more instances of widespread outages and the severe societal and economic damages that ensue. Protecting the power grid against such events, which are high impact yet low frequency, requires a paradigm shift in grid design practices.
  • 727
  • 19 Jan 2023
Topic Review
Conservation Voltage Reduction in Modern Power Systems
Conservation voltage reduction (CVR) is a potentially effective and efficient technique for inertia synthesis and frequency support in modern grids comprising power electronics (PE)-based components, aiming to improve dynamic stability. In conventional power systems with synchronous generators, CVR utilization strategies aiming to conserve energy are split into two broad categories namely, open-loop and closed-loop techniques. Electromechanical voltage regulating devices, such as on-load tap changers (OLTCs), line drop compensators, and capacitor banks, are used to utilize CVR through open-loop procedures without measuring the voltage as a feedback signal. 
  • 726
  • 22 Mar 2023
Topic Review
Application of Radio Frequency Identification in IoT Field
RFID (radio frequency identification) technology appeared nearly 70 years ago. Deployed more widely only from the early 2000s, it is now booming and its development is still accelerating. As its name indicates, its original function was the identification (of objects, animals, people) and its applications were then essentially aimed at traceability, access control and logistics. If this type of use is still relevant today with more and more new application contexts and more and more efficient RFID tags, RFID has also evolved by integrating new capabilities. These new tags, known as augmented tags, include an information capture function. With the explosion of connected objects and the emergence of the Internet of Things (IoT), this old technology that is RFID still has a promising future and will probably be more and more present in our private and professional environments in all fields: logistics, industry, agriculture, building, health and even space.
  • 725
  • 14 Nov 2022
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