Topic Review
Sonic Boom Prediction and Minimization
NASA describes the sonic boom as “thunder-like noise a person on the ground hears when an aircraft […] flies overhead faster than the speed of sound”. Sonic boom results from the coalescence of the shock waves generated by an aircraft flying supersonicly trough their propagation into the atmosphere to the ground.
  • 794
  • 08 Nov 2023
Topic Review
End Effectors in Agricultural Robotic Harvesting Systems
An end effector is a peripheral device attached to a robot’s wrist, enabling interaction during a task. For harvesting robots, the end effector is considered the contact point between the robot and the product to be harvested. Robotic systems have been designed to cover labor shortage, to increase the speed of harvesting, and to improve the efficiency of harvesting.
  • 794
  • 30 Aug 2022
Topic Review
Chang Bogo-Class Submarine
The Chang Bogo-class submarine (Hangul: 장보고급 잠수함, Hanja: 張保皐級潛水艦) is a variant of the Type 209 diesel-electric attack submarine initially developed by Howaldtswerke-Deutsche Werft (HDW) of Germany , intended for service with the South Korean Navy and Indonesian Navy. A Daewoo (DSME)-upgraded model of the Chang Bogo class Type 209 is being independently exported by Korea to Indonesia in 2012, after a series of heavy competitions from Russian, French, and German-Turkish consortiums including from Germany's original Type 209. The variant is being considered for possible purchase by Thailand as well, as both newly built and second-hand options. The class is named for ancient Korean maritime figure Jang Bogo.
  • 794
  • 28 Nov 2022
Topic Review
Postcrossing
Postcrossing is an online project that allows its members to send and receive postcards from all over the world. The project's tag line is "send a postcard and receive a postcard back from a random person somewhere in the world!” Its members, also known as postcrossers, send postcards to other members and receive postcards back from other random postcrossers. Where the postcards come from is always a surprise. Postcrossing is the union of the words "postcard" and "crossing" and its origin "is loosely based on the Bookcrossing site". However, the "crossing" or exchange of postcards works in a different way. A member sends a postcard to another postcrosser and receives a postcard back from a random postcrosser. Exchanges between the same two members only occur once; although direct swaps between members happen, they are not part of the official happenings on the site. The project is completely free and anyone with an address can create an account. The postcards and postage fees to mail them are the responsibility of each user. By February 2018 Postcrossing had more than 719,000 members in 212 countries who had registered and exchanged over 45 million postcards that traveled over 229 billion kilometers. The highest concentration of Postcrossing members reside (in order) in Russia, Taiwan, China, the United States, Germany, the Netherlands, Poland, Belarus, Ukraine, Finland and the Czech Republic, each with over 20,000 members. Globally, most postcrossers reside in North America, Europe and East Asia. Of particular note, Postcrossing is popular in eastern European and former-Soviet states. As of January 2012, more than a quarter of the combined total of postcards were sent from Finland, Russia, Estonia, Latvia, Lithuania, Belarus and Ukraine.
  • 793
  • 04 Nov 2022
Topic Review
Sandwich Composites
Structural sandwich composites have been widely used in many engineering fields, and this trend is expected to continue due to their superior mechanical properties, thermal insulation and acoustic damping. However, to further improve their mechanical properties, literature reports significant benefits obtained with nano-reinforcements. In this context, nanoclays are the most popular nano-reinforcements for polymeric nanocomposites, due to their relatively high ion exchange capacity, high aspect ratio and economic advantages. In order to stablish a systematic understanding for application in design procedures, this work intends to summarize all studies available in the open literature about this topic.
  • 793
  • 28 Oct 2020
Topic Review
Alternative Fuels in Maritime Sector
The current sulfur oxide (SOx), nitrogen oxide (NOx), and greenhouse gases (GHG) regulations have pressured international maritime transportation to adopt lower-emission fuels. Alternative fuels have received strong attention due to the fact they can be cleaner and environmentally friendly and, in some options, similar to the heavy fuel oil (HFO) and marine gas oil (MGO) used. The liquefied natural gas (LNG) is undoubtedly the main low carbon alternative with many ships already operating with this source in the world. Eighty-eight percent of the papers referred to LNG as an important source in the maritime sector for greenhouse gases (GHG) reduction. Hydrogen is one of the most cited options (16.2%). In a tank-to-wheel assessment, H2 from fossil sources has nil GHG emissions, which can also be highly carbon-intensive when analyzed from a well-to-wheel perspective. Biodiesel is a renewable and low carbon source, which represented 14.5% of total mentions. This option, together with hydrotreated vegetable oil (HVO) (3.8%) and straight vegetable oil (SVO) (3.4%) are sources that can be blended into the current marine engines without further modification. 
  • 793
  • 12 Aug 2022
Topic Review
Design of Brushless Doubly Fed Machines
Doubly fed induction generators (DFIGs) are the most widely used generators in wind turbines. However, due to the incessant failures of their slip rings and brushes, the operating and maintenance costs of DFIG based wind turbines are high; this is even worse in remote areas like offshore wind sites. Research interest on brushless doubly fed induction machines (BDFMs) is increasing, as they offer higher reliability compared to doubly fed induction generators (DFIGs) in wind turbines.
  • 793
  • 05 May 2022
Topic Review
I4.0, Servitisation, and Circular Economy
Industry 4.0 (I4.0) technologies have been highlighted in recent literature as enablers of servitisation. Simultaneously, businesses are advised to implement a circular economy (CE) to bring new opportunities. However, it is pertinent to mention that little attention has been given to assess the role of I4.0 in adopting the CE and servitisation in a fully integrated manner. This research fills this gap by developing a conceptual framework through a systematic literature review of 139 studies investigating the relationship between the I4.0, CE, and servitisation. This study identifies the impact of these variables on a firm’s operational and financial performance (revenue stream, growth, and profitability). Our research findings advocate that adopting I4.0 technologies to the business and manufacturing model enables sustainability, energy and resource efficiency while enhancing performance and offering innovative products through smart services. Thus, firms must systematically adopt I4.0 technologies to support a CE model that creates value through servitisation. This study identifies the research gaps that are unexplored for practitioners and future researchers while providing insight into the role of I4.0 in implementing CE in the servitisation business model.
  • 792
  • 23 Jun 2021
Topic Review
Jupiter (Rocket Family)
The Jupiter family of super heavy-lift launch vehicles was part of the proposed DIRECT Shuttle-Derived Launch Vehicle architecture. It was intended to be the alternative to the Ares I and Ares V rockets which were under development for the US Project Constellation. Major benefits were projected from re-using as much hardware and facilities from the Space Shuttle program as possible, including cost savings, experience with existing hardware, and preserving the workforce.
  • 792
  • 23 Nov 2022
Topic Review
UV-C Irradiation
Amongst the surface treatment technologies to emerge in the last few decades, UV-C radiation surface treatment is widely used in food process industries for the purpose of shelf life elongation, bacterial inactivation, and stimulation.
  • 792
  • 21 Jun 2022
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