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Topic Review
Variable-Pitch Propeller
A variable-pitch propeller or controllable-pitch propeller (CPP) is a type of propeller with blades that can be rotated around their long axis to change the blade pitch. Reversible propellers—those where the pitch can be set to negative values—can also create reverse thrust for braking or going backwards without the need to change the direction of shaft revolution.
  • 2.5K
  • 23 Nov 2022
Topic Review
IPTV
Internet Protocol television (IPTV) is the delivery of television content over Internet Protocol (IP) networks. This is in contrast to delivery through traditional terrestrial, satellite, and cable television formats. Unlike downloaded media, IPTV offers the ability to stream the source media continuously. As a result, a client media player can begin playing the content (such as a TV channel) almost immediately. This is known as streaming media. Although IPTV uses the Internet protocol it is not limited to television streamed from the Internet, (Internet television). IPTV is widely deployed in subscriber-based telecommunications networks with high-speed access channels into end-user premises via set-top boxes or other customer-premises equipment. IPTV is also used for media delivery around corporate and private networks. IPTV in the telecommunications arena is notable for its ongoing standardisation process (e.g., European Telecommunications Standards Institute). IPTV services may be classified into three main groups:  Live television and live media, with or without related interactivity; Time-shifted media: e.g. catch-up TV (replays a TV show that was broadcast hours or days ago), start-over TV (replays the current TV show from its beginning); Video on demand (VOD): browse and view items in a stored media catalogue.
  • 2.5K
  • 27 Oct 2022
Topic Review
Radeon HD 7000 Series
The Radeon HD 7000 Series, based on "Southern Islands", is further products series in the family of Radeon GPUs developed by AMD. AMD builds Southern Islands series graphics chips based on the 28 nm manufacturing process at TSMC. The primary competitor of Southern Islands, Nvidia's GeForce 600 Series (also manufactured at TSMC), also shipped during Q1 2012, largely due to the immaturity of the 28 nm process.
  • 2.5K
  • 08 Nov 2022
Topic Review
Satellite Constellations
The New Space Economy encourages constellations of satellites that are being proposed in large numbers by private companies. They will provide communication, enable global monitoring of Earth, and enhance space observation. Mostly enabled by technology miniaturization, satellite constellations require a coordinated effort to face the technological limits in spacecraft operations and space traffic. In this Topic Review, we provide a survey of the upcoming satellite constellations and an overview of future challenges to be faced.
  • 2.5K
  • 27 Oct 2020
Topic Review
Permanent Magnet Linear Synchronous Motor
In high-end testing and manufacturing equipment, a trend exists whereby the traditional servo feed system with a ball screw and rotary motor will gradually be replaced by a direct drive system. The precision motion system driven by a permanent magnet linear synchronous motor (PMLSM) offers several advantages, including high speed, high acceleration, and high positioning accuracy. However, the operating precision of the feed device will be affected by the PMLSM robustness to nonlinear and uncertain disturbances, such as cogging force, friction, thermal effects, residual vibration, and load disturbance.
  • 2.5K
  • 29 Apr 2021
Topic Review
Semiconductor Gas Sensors
Semiconductor materials include metal oxides, conducting polymers, carbon nanotubes, and 2D materials. Metal oxides are most often the first choice due to their ease of fabrication, low cost, high sensitivity, and stability. Some of their disadvantages are low selectivity and high operating temperature. Conducting polymers have the advantage of a low operating temperature and can detect many organic vapors. They are flexible but affected by humidity. Carbon nanotubes are chemically and mechanically stable and are sensitive towards NO and NH3, but need dopants or modifications to sense other gases. Graphene, transition metal chalcogenides, boron nitride, transition metal carbides/nitrides, metal organic frameworks, and metal oxide nanosheets as 2D materials represent gas-sensing materials of the future, especially in medical devices, such as breath sensing.
  • 2.5K
  • 10 Dec 2020
Topic Review
Panel Van
A panel van (or panelvan) is a form of solid (rigid-bodied, non-articulated) van, smaller than a lorry or truck, without rear side windows. In the UK this body style is referred to as a "car-derived van" and in North American as a "sedan delivery" (while the term "panel van" or "cargo van" generally refers to larger, truck-based vans such as the Ford E-Series and Chevrolet Express). In Australia panel vans were a development of the Australian "ute" (utility), a variety of pickup, based on a car chassis, these often utilizing the floorpan of the station wagon model. In North America a two-door station wagon base was used with only front seats and steel sheet-metal panels in place of the rear and side windows. Panel vans are widely used in many parts of the world for transporting cargo. In some national usages it is distinct from a purpose-designed van in that it is based on the chassis of a family car design. In places where they are distinct from a "van", they have less cargo space but better agility and maneuverability, making them particularly suited for cities with narrow streets or heavy traffic.
  • 2.5K
  • 11 Nov 2022
Topic Review
List of Oldest Surviving Ships
This is a list of the oldest ships in the world which have survived to this day without significantly losing their original form. It includes warships, yachts, tall ships, and vessels recovered during archaeological excavations. It does not include reconstructions or replicas, partially complete wreckage, or ships which have been located but remain underwater. For example, the Mary Rose, whose remains consist only of a partial hull, is not included here. Vessels listed are sorted by date of launching as most accurately known.
  • 2.5K
  • 07 Nov 2022
Topic Review
Ethical Dilemmas in Emerging Technologies
Emerging technologies have featured prominently in the research on technology ethics, which is progressively concentrating on early-stage intervention in technological innovation. Techno Ethics (TE) serves as a multidisciplinary research field that incorporates theories and techniques from various domains including communications systems, sociology, innovation, ethical theories, and principles. Cybercrime is an umbrella term for all illicit activities made possible by access to an IT infrastructure including unauthorized access, unlawful data comparison interception, system disruption, digital identity fraud, etc. The goal of cybersecurity (counterpart to cybercrime) is to assist people in mitigating risks in their systems, networks, and data, ensuring security and privacy. To secure cyberspace, formal and informal resources, including equipment, people, infrastructure, services, policies, training, and technologies are used. As more firms post details to demonstrate their public commitment to ethical ideals while promoting security, discussions regarding ethical standards for emerging technologies are becoming more common. 
  • 2.5K
  • 13 Feb 2023
Topic Review
Stereolithography
Being the earliest form of Additive manufacturing, Stereolithography (SLA) fabricates 3D objects by selectively solidifying the liquid resin through photopolymerization reaction. The ability to fabricate objects with high accuracy as well as a wide variety of materials brings much attention to stereolithography. Since its invention in 1980s, SLA underwent four generations of major technological innovation over the past 40 years. These innovations have thus result in a diversifies range of stereolithography systems with dramatically improved resolution, throughput, and materials selection for creating complex 3D objects and devices. In this paper, we review the four generations stereolithography processes, which are scanning, projection, continuous and volumetric stereolithography. For each generation, representative stereolithography system configurations are also discussed in detail. In addition, other derivative technologies, such as scanning-projection, multi-material, and magnetically assisted stereolithography processes, are also included in this review.
  • 2.5K
  • 16 Sep 2020
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