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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.
  • 448
  • 06 Dec 2022
Topic Review
Circular Connector
The term Circular Connector applies to any electrical connector possessing multipin interconnects with cylindrical contact housings and circular contact interface geometries. Circular connectors are selected for ease of engagement and disengagement, their ability to conveniently house different types of contacts, their wide range of allowable contact voltages and currents, their ease of environmental sealing and their rugged mechanical performance. In military, aerospace, and other high-reliability applications, the MIL-DTL-5015 and MIL-DTL-38999 are among the most commonly specified types. The primary disadvantage of the circular design is loss of panel space when used in arrays when compared to rectangular connectors.
  • 447
  • 09 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. 
  • 446
  • 26 Oct 2023
Topic Review
Apollo Energy Systems
Apollo Energy Systems is a U.S. multinational alternative energy corporation headquartered in Pompano Beach, Florida, that develops, produces, and markets fuel cell power plants, electric propulsion systems, and alternative energy generation equipment. The company was founded by Robert R. Aronson in 1966 as the Electric Fuel Propulsion Corporation (EFP) in New Orleans, Louisiana. It later became known as the Electric Auto Corporation (EAC), and in 2001 changed to Apollo Energy Systems.
  • 445
  • 16 Nov 2022
Topic Review
Attribute-Based Access Control in Smart Home IoT Environments
Technological advancements have allowed for the integration of the internet of things (IoT) with home and residential buildings, presenting an advanced method of increasing the usability, security, and quality of life of the user. This is called a smart home network, which is a home equipped with various devices, such as lighting, heating, and monitoring systems that smartphones or computers on the network can control.
  • 445
  • 24 Aug 2023
Topic Review
Energy Management Systems in Microgrids
Microgrids usually employ distributed energy resources such as wind turbines, solar photovoltaic modules, etc. When multiple distributed generation resources with different features are used in microgrids, managing these resources becomes an important problem. The generated power of solar photovoltaic modules and wind turbines used in microgrids is constantly changing with solar irradiation and wind speed. Due to this impermanent and uncertain nature of renewable energy resources, generally, energy storage systems are employed in microgrid systems. To control the distributed energy resources and energy storage units and sustain the supply and demand balance within the microgrid and provide sustainable and reliable energy to the loads, energy management systems are used. Many methods are used to realize and optimize energy management in microgrids. 
  • 445
  • 26 Feb 2024
Topic Review
EIS and IRT for Evaluating Lithium Batteries
During lithium-ion batteries (LIBs) ordinary operation, safety concerns are related to the possibility of overheating and, in extreme cases, to the risk of fire or explosion. Hence, it is crucial to implement proper safety measures in the design, manufacturing, and in the second life of LIBs, through a proper design of thermal management systems or short circuit protection. Regarding their durability, LIBs can face degradation over time due to repeated charge–discharge cycles. This might affect their charge retention capacity and their lifespan. Hence, ongoing research is being conducted to improve these aspects through advancements in materials, electrode design, and battery management systems. LIB development focuses on improving their efficiency by using environmentally friendly materials. The non-destructive testing (NDT) of LIBs can be classified into several categories. The commonly accepted taxonomy is based on their underlying physical principle of measurement, e.g., electromagnetic waves, thermal waves, mechanical waves, etc.
  • 441
  • 16 Nov 2023
Topic Review
Tesla Valve Microfluidics
The Tesla valve (TV), a valvular conduit invented by Nicola Tesla over a century ago, has recently acquired significant attention and application in various fields because of the growing interest in microfluidics and nanofluidics. The unique architecture of TV characterized by an asymmetrical design and an arc-shaped channel has long been an intriguing yet underrated design for building a passive component in a microfluidic system. While previously regarded as a technology without significant use, TV structures have been implemented in thermal manipulation fluidics, micromixers and micropumps, benefitting the advancement of urgently demanding technology in various areas, such as in biomedical diagnostics through wearable electronics and medical instruments, lab on a chip, chemosensors and in application toward sustainable technology manifested in fuel cell devices.
  • 440
  • 05 May 2023
Topic Review
Microgrid Energy Market
Electricity generation using distributed renewable energy systems is becoming increasingly common due to the significant increase in energy demand and the high operation of conventional power systems with fossil fuels. Microgrids are rapidly becoming attractive because they assist in reducing the load congestion on the traditional power system, have a less environmental impact, intensify the power generation capacity, are easy to install, offer localized generation to the consumers, and are highly efficient with increased reliability.
  • 439
  • 20 Apr 2023
Topic Review
Existing Mobile Broadband Performance Measurements
Globally, mobile broadband (MBB) penetration has increased due to the widespread use of smart devices, better mobile network coverage, and the ongoing quest for faster wireless and mobile communication technology. This has led to a tremendous rise in the number of internet subscribers, which is positively impacting the social and economic well-being of society at large. Terrestrial mobile network operators (MNOs) are responsible for providing MBB services to end users, but some of them do not offer the advertised speeds or theoretical speeds specified by 3GPP specifications. Therefore, periodic impartial and unbiased performance measurement studies of the quality of service (QoS) provided by the MNOs as perceived by the end users are required to help MNOs enhance the capabilities of their MBB networks and provide services at an acceptable quality.
  • 436
  • 07 Apr 2023
Topic Review
Multiport Single Element Mimo Antenna Systems
In response to the increasing demand for voice, data, and multimedia applications, the next generation of wireless communication systems is projected to provide faster data rates and better service quality to customers. Techniques such as Multiple-Input–Multiple-Output (MIMO) and diversity are being studied and implemented to meet the needs of next-generation wireless communication systems. Embedding multiple antennas into the same antenna system is seen as a promising solution, which can improve both the system’s channel capacity and the communication link’s quality. For small handheld and portable devices, embedding many antennas into a single device in a small area and at the same time providing good isolation becomes a challenge.
  • 435
  • 19 Jan 2023
Topic Review
Power System Stabilizers
A power system (PS) is a complex system consisting of devices for the generation, transmission, distribution, processing, and consumption of electric energy. The expansion of a PS causes a number of new stability problems that scientists try to solve in various ways, including the use of appropriate devices and control systems, the most popular of which are power system stabilizers (PSSs). It should be emphasized that the use of classic power system stabilizers in the modern digital voltage regulators of synchronous generators does not require large financial outlays (a PSS is implemented as an additional fragment of the voltage regulator program code) compared to other solutions improving PS stability (e.g., FACTS systems).
  • 433
  • 03 Mar 2023
Topic Review
Design Improvements of DC Circuit Breaker
While traditional AC mechanical circuit breakers can protect AC circuits, many other DC power distribution technologies, such as DC microgrids (MGs), yield superior disruption performance, e.g., faster and more reliable switching speeds. However, novel DC circuit breaker (DCCB) designs are challenging due to the need to quickly break high currents within milliseconds, caused by the high fault current rise in DC grids compared to AC grids. In DC grids, the circuit breaker must not provide any current crossing and must absorb surges, since the arc is not naturally extinguished by the system. Additionally, the DC breaker must mitigate the magnetic energy stored in the system inductance and withstand residual overvoltages after current interruption. These challenges require a fundamentally different topology for DCCBs, which are typically made using solid-state semiconductor technology, metal oxide varistors (MOVs), and ultra-fast switches.
  • 433
  • 06 Sep 2023
Topic Review
Protection of Multi-Terminal HVDC Grids
Multi-terminal HVDC grids facilitate the integration of various renewable resources from distant locations; in addition, they enhance the reliability and stability of the grid. Protection is one of the major obstacles in realizing reliable and secure multi-terminal HVDC grids.
  • 432
  • 04 Jan 2023
Topic Review
LoRa Technology
Low-power wide-area networks (LPWANs) constitute a variety of modern-day Internet of Things (IoT) applications. Long range (LoRa) is a promising LPWAN technology with its long-range and low-power benefits. Performance enhancement of LoRa networks is one of the crucial challenges to meet application requirements, and it primarily depends on the optimal selection of transmission parameters. 
  • 431
  • 23 May 2023
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.
  • 430
  • 25 Aug 2023
Topic Review
Indoor Localization
Indoor localization has become a paramount component across many fields, such as healthcare, security, and retail. These diverse applications require accurate and reliable indoor localization systems to optimize functionality and performance. Outdoor localization systems rely on GPS and Point of Interest (POI) data. POI data is used in many geospatial applications, providing semantic information for places of interest and has many geospatial applications. On the other hand, indoor systems demand specialized techniques that consider the unique characteristics of indoor environments, such as complex building structures, multiple floors, and potential signal interference. In response to these challenges, various approaches were developed to achieve precise geolocation within an indoor setting. These methods include multilateration, weighted centroid, and Grid-based RSS. 
  • 429
  • 28 Sep 2023
Topic Review
Grid-Forming Inverters
The electrical grid is predominantly characterized by synchronous generators (SGs). These generators provide a consistent voltage and frequency, facilitating the synchronization of VSIs and their connection at the point of common coupling (PCC) for injecting power into the main grid. These inverters operate as current sources and are known as grid-following inverters. The imperfections of grid-following inverters arise when the grid is absent, as this concept fails to produce instantaneous voltage and frequency set points. Therefore, this operating mode has been significantly modified, from following the grid to leading it. This concept is known as grid-forming (GFM) inverters, which can independently set up and keep the voltage and frequency within their nominal ranges without the need for the main grid.
  • 428
  • 29 Dec 2023
Topic Review
Smart Contract Design in Distributed Energy Systems
Blockchain technology and, in particular, smart contracts based on it, offers a new, decentralized mechanism for entering into and fulfilling contracts in diverse markets. Energy markets are no exception, and indeed, the decentralized nature of the blockchain may be particularly important for them as the penetration of residential prosumers offering microgeneration to the grid grows. 
  • 427
  • 28 Jul 2023
Topic Review
Electric Vehicle Grand Prix
The Electric Vehicle Grand Prix (stylized as evGrand Prix) is an electric go-kart race held at Purdue University and the Indianapolis Motor Speedway.
  • 427
  • 10 Oct 2022
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