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Topic Review
Distributed Generation Integration into Grid
According to [25], DGs could also be defined as a small source of power production for storage (usually within the range of less than a kW and tens of MW), which is not a portion of the huge, centralized power network and is located close to the load. Another school of thought defines DGs as power pockets usually located near consumers, which have a relatively small capacity of 30 MW or less, with the ability to economically support the distribution grid. This description involves DG technologies such as photovoltaic systems, concentrating solar power, micro turbines, reciprocating engines and fuel cells.
  • 3.6K
  • 16 Sep 2021
Topic Review
Rolls-Royce Phantom VII
The Rolls-Royce Phantom VII is a full-sized luxury saloon car made by Rolls-Royce Motor Cars. Launched in 2003, it was the first Rolls-Royce developed and introduced after BMW purchased the right to use the Rolls-Royce name and logo in 1998. It is credited with successfully reviving the Rolls-Royce brand and restoring Rolls-Royce's reputation as a maker of luxury cars. The Phantom Drophead Coupé and Phantom Coupé are two-door derivatives of the Phantom launched in 2007 and 2008, respectively. From 2003 until the launch of the smaller Ghost in 2009, the Phantom was the only car produced by Rolls-Royce. The Phantom acted as the company's flagship model, but was less exclusive than all previous Phantoms (none of which surpassed the 600 per year).
  • 3.6K
  • 05 Dec 2022
Topic Review
Architecture and Challenges of Industrial Internet of Things
The inherent complexities of Industrial Internet of Things (IIoT) architecture make its security and privacy issues becoming critically challenging. Numerous surveys have been published to review IoT security issues and challenges. The studies gave a general overview of IIoT security threats or a detailed analysis that explicitly focuses on specific technologies. However, recent studies fail to analyze the gap between security requirements of these technologies and their deployed countermeasure in the industry recently. Whether recent industry countermeasure is still adequate to address the security challenges of IIoT environment are questionable.
  • 3.6K
  • 21 Oct 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.
  • 3.6K
  • 29 Oct 2020
Topic Review
Fault-Tolerant Control
Fault-tolerant controllers (FTCs) can be defined as controllers that are able to tolerate faults and keep the control performance in the ideal range in the presence of faults. FTC approaches can be categorized into two main categories: Passive FTCs and Active FTC. Passive FTCs are not dependent on fault detection and isolation (FDI) modules and can keep the desired controller performance without considering the type and size of fault. Active FTCs are equipped with the FDI module and behave differently to different kinds of fault.
  • 3.6K
  • 27 Oct 2020
Topic Review
Laser Powder Bed Fusion
Laser powder bed fusion (LPBF) is the most used metal additive manufacturing technique, and it is based on the efficient interaction between a high-energy laser and a metal powder feedstock. The reuse of the powder feedstock is crucial to make the process cost-efficient and environmentally friendly. However, since studies of the mechanical and microstructural properties of parts produced with reused powders show scattered results, a closer look to the powder, heat source and shielding gas properties and to how they interact during the LPBF process is presented.  
  • 3.6K
  • 29 Oct 2020
Topic Review
Space Shuttle Main Engine
The Aerojet Rocketdyne RS-25, otherwise known as the Space Shuttle main engine (SSME), is a liquid-fuel cryogenic rocket engine that was used on NASA's Space Shuttle and is planned to be used on its successor, the Space Launch System. Designed and manufactured in the United States by Rocketdyne (later known as Pratt & Whitney Rocketdyne and Aerojet Rocketdyne), the RS-25 burns cryogenic liquid hydrogen and liquid oxygen propellants, with each engine producing 1,859 kN (418,000 lbf) of thrust at liftoff. Although the RS-25 can trace its heritage back to the 1960s, concerted development of the engine began in the 1970s, with the first flight, STS-1, occurring on April 12, 1981. The RS-25 has undergone several upgrades over its operational history to improve the engine's reliability, safety, and maintenance load. Subsequently, the RS-25D is the most efficient liquid fuel rocket engine currently in use. The engine produces a specific impulse (Isp) of 452 seconds (4.43 km/s) in a vacuum, or 366 seconds (3.59 km/s) at sea level, has a mass of approximately 3.5 tonnes (7,700 pounds), and is capable of throttling between 67% and 109% of its rated power level in one-percent increments. The RS-25 operates at temperatures ranging from −253 °C (−423 °F) to 3300 °C (6000 °F). The Space Shuttle used a cluster of three RS-25 engines mounted in the stern structure of the orbiter, with fuel being drawn from the external tank. The engines were used for propulsion during the entirety of the spacecraft's ascent, with additional thrust being provided by two solid rocket boosters and the orbiter's two AJ-10 orbital maneuvering system engines. Following each flight, the RS-25 engines were removed from the orbiter, inspected, and refurbished before being reused on another mission.
  • 3.6K
  • 24 Oct 2022
Topic Review
Wooden Boats of World War 2
Splinter fleet or Splinter navy was a nickname given to the wooden boats used in World War II. The boats served in many different roles during the war. These boats were built in small boatyards on the West coast and East coast, Great Lakes and the Gulf of Mexico. They could be built quickly, in just 60 to 120 days. Most of the boats were built by boatyards that already had the tools and knowledge from building yachts, sailboats and motor boats. Many were built by craftsmen in family-owned small businesses. Under the Emergency Shipbuilding Program and War Shipping Administration contracts went out to over fifty boatyards across the country. The boats were built for the US Navy, the, United States Army Air Forces , United States Coast Guard, and US Army. Some of the wooden boats went to Allied nations on the Lend-Lease program. In addition to new boat construction, some wooden boats built between 1910 and 1941 were acquired for the war effort, some used as-is and others converted for war use. Wooden boats have lighter weight and are easier to repair than steel hull boats. These wooden boats ranged from 19 to 200 feet in length. Some worked near shore and others working in the open ocean, called the Blue-water navy. The Splinter fleet is in contrast to the more common steel hull war ships and Merchant Marine ships. After the war, many of these boats were deemed not needed. Many were abandoned or destroyed, a few served in the Korean war and a few in the Vietnam War, some sold to private and some donated. During World War I there was a debate as to if wooden boats and ships should be used in war time. William Denman, President of the Emergency Fleet Corporation supported the building of wooden ships for the war and General Goethals disapproved. In the end, both men turned in their resignation over the heated debate. During World War II the situation was different. There was a shortage of steel and steel shipyards, so there was no debate about the need for a vast wooden fleet of boats and ships.
  • 3.6K
  • 14 Oct 2022
Topic Review
Blended Learning
Blended learning is an approach to education that combines online educational materials and opportunities for interaction online with traditional place-based classroom methods. It requires the physical presence of both teacher and student, with some elements of student control over time, place, path, or pace. While students still attend "brick-and-mortar" schools with a teacher present, face-to-face classroom practices are combined with computer-mediated activities regarding content and delivery. Blended learning is also used in professional development and training settings. Since blended learning is highly context-dependent, a universal conception of it is difficult. Some reports have claimed that a lack of consensus on a hard definition of blended learning has led to difficulties in research on its effectiveness. A well-cited 2013 study broadly defined blended learning as a mixture of online and in-person delivery where the online portion effectively replaces some of the face-to-face contact time rather than supplementing it. Additionally, a 2015 meta-analysis that historically looked back at a comprehensive review of evidence-based research studies around blended learning, found commonalities in defining that blended learning was "considered a combination of traditional f2f [face to face] modes of instruction with online modes of learning, drawing on technology-mediated instruction, where all participants in the learning process are separated by distance some of the time." This report also found that all of these evidence-based studies concluded that student achievement was higher in blended learning experiences when compared to either fully online or fully face-to-face learning experiences. "Blended learning" is sometimes used in the same breath as "personalized learning" and differentiated instruction.
  • 3.6K
  • 17 Oct 2022
Topic Review
Passive Films
The outstanding corrosion resistance of many metals and alloys results from the presence of a thin oxide-“passive”-film on the bare metal surface formed during its exposure to an oxidising environment. Once a film is formed, typically 1-3 nm thick, the reaction rate between the metallic material and the environment will be several orders of magnitude lower. The original theory of film formation goes back to Michael  Faraday, who in the 19th century studied iron surfaces and found them “altered”. A review of the early days of passive film research has been written by Uhlig (1979). A general introduction to the theory of passivity has been published by Sato (1990), whereas the electronic properties of passive films on different materials have been  reviewed by Schultze and Lohrengel (2000). The characterisation of the composition and structure of such thin films and the study of their interaction with corrosive environments requires a combination of sophisticated experimental techniques, namely electrochemical methods, XPS, ESCA, AES, SIMS, ISS, ARXPS, XANES, ICP-AES/MS, and others, which are leading to advanced progress over the past two decades.
  • 3.5K
  • 21 Dec 2020
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