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Topic Review
Drone Detection and Defense Systems
Drones are small and low-cost unmanned aerial vehicles (UAVs). With the decrease in the cost and size of drones in recent years, their number has also increased exponentially. As such, the concerns regarding security aspects that are raised by their presence are also becoming more serious.
  • 2.5K
  • 10 Mar 2022
Topic Review
Bongo Drum
Bongos (Spanish: bongó) are an Afro-Cuban percussion instrument consisting of a pair of small open bottomed hand drums of different sizes. They are struck with both hands, most commonly in an eight-stroke pattern called martillo (hammer). They are mainly employed in the rhythm section of son cubano and salsa ensembles, often alongside other drums such as the larger congas and the stick-struck timbales. Bongo drummers (bongoseros) emerged as the only drummers of son cubano ensembles in eastern Cuba toward the end of the 19th century. The instrument remained important as son groups evolved into larger conjuntos and orchestras in Havana in the 1940s, at which point they began to share the stage with congas. Bongos later reached the United States, where they are commonly played in salsa, Afro-Cuban jazz, Latin rock and other genres. Bongo drums are about 20 centimetres (8 in) high and have diameters of approximately 20 centimetres (8 in) and 25 centimetres (10 in) (the smaller drum is called macho, male, and the larger drum, hembra, female). They are the smallest drums in Latin percussion, some models being only 15 centimetres (6 in) in diameter. The shells of the drums and the bridge (the small block that joins them) are usually made of wood, although fiberglass is also common. The heads are typically made of calfskin and attached to the shells via steel hardware that enables their tuning. Originally, metal tacks were used, so tuning had to be done by heating the skins.
  • 2.5K
  • 02 Nov 2022
Topic Review
Layer-Scale Transfer Techniques
Layer transfer is a technique to transfer a layer of a particular semiconductor material, often of a wafer-scale size, from the original substrate to the target substrate of interest.
  • 2.5K
  • 26 Apr 2021
Topic Review
Out-of-Autoclave Process for Composite Manufacturing
Composite materials have gained increased usage due to their unique characteristic of a high-stiffness-to-weight ratio. High-performing composite materials are produced in the autoclave by applying elevated pressure and temperature. The process is characterized by numerous disadvantages, such as long cycle time, massive investment, costly tooling, and excessive energy consumption. As a result, composite manufacturers seek a cheap alternative to reduce cost and increase productivity. The out-of-autoclave (OoA) process manufactures composites by applying vacuum, pressure, and heat outside of the autoclave.
  • 2.5K
  • 20 Jul 2022
Topic Review
Messerschmitt Me 323
The Messerschmitt Me 323 Gigant ("Giant") was a German military transport aircraft of World War II. It was a powered variant of the Me 321 military glider and was the largest land-based transport aircraft of the war. A total of 213 are recorded as having been made, 15 being converted from the Me 321.
  • 2.5K
  • 17 Oct 2022
Topic Review
Ordnance QF 6-pounder
The Ordnance Quick-Firing 6-pounder 7 cwt,[note 1] or just 6-pounder, was a British 57 mm gun, serving during the Second World War as a primary anti-tank gun of both the British and United States Army (as the 57 mm Gun M1). It was also used as the main armament for a number of armoured fighting vehicles. Although designed before the start of the war, it did not reach service until the North African Campaign in April 1942. There, it replaced the 2-pounder as an anti-tank gun, allowing the 25-pounder gun-howitzer to revert to its intended artillery role.
  • 2.5K
  • 03 Nov 2022
Topic Review
Wind Turbine Blade Failures
The wind turbine is a complex structure. Although there is no single approach and there is variability in the commercial designs, a typical WTB is a thin-walled multi-cellular hollow airfoil shaped cross-section. For its manufacture, a number of materials and material systems are used for structural purposes (fibre composites and sandwich composite systems) as well as aesthetic purposes (primers, UV gel coats, paint, etc). The potential causes of wind turbine blade failures can be classified into the following four categories:1. damage from lightning;2. failures due to fatigue;3. leading edge erosion;4. damage from icing.The types of damage caused to wind turbine blades—originating from the above four different sources—along with their significance to the turbine’s performance and secure operation, are detailed in the following sub-sections.
  • 2.5K
  • 11 Oct 2021
Topic Review
Virtual Reality and Robots
There is a significant amount of synergy between virtual reality (VR) and the field of robotics. However, it has only been in approximately the past five years that commercial immersive VR devices have been available to developers. This new availability has led to a rapid increase in research using VR devices in the field of robotics, especially in the development of VR interfaces for operating robots. 
  • 2.5K
  • 25 Jan 2021
Topic Review
Ghazal
The ghazal (Bengali: গজল, Sylheti: ꠊꠏꠟ, Punjabi: ਗ਼ਜ਼ਲ, Urdu: غزَل , Hindi: ग़ज़ल, Persian: غزل‎, Azerbaijani: qəzəl, Turkish: gazel, Uzbek: gʻazal, Pashto: غزل‎, Template:Lang-gu,) is a form of amatory poem or ode, originating in Arabic poetry. A ghazal may be understood as a poetic expression of both the pain of loss or separation and the beauty of love in spite of that pain. The ghazal form is ancient, tracing its origins to 7th-century Arabic poetry. The ghazal spread into South Asia in the 12th century due to the influence of Sufi mystics and the courts of the new Islamic Sultanate, and is now most prominently a form of poetry of many languages of the Indian subcontinent and Turkey. A ghazal commonly consists of between five and fifteen couplets, which are independent, but are linked – abstractly, in their theme; and more strictly in their poetic form. The structural requirements of the ghazal are similar in stringency to those of the Petrarchan sonnet. In style and content, due to its highly allusive nature, the ghazal has proved capable of an extraordinary variety of expression around its central themes of love and separation.
  • 2.5K
  • 24 Nov 2022
Topic Review
Abiotic and Biotic Polymer Degradation Mechanisms
Polymer degradation is defined as an irreversible change of the chemical structure, physical properties, and visual appearance due to the chemical cleavage of the polymer’s constitutive macromolecules by one or more mechanism. More than one mechanism can simultaneously take place due to the action of external factors, and one mechanism can be more dominant than others at any time. External factors associated with the environment, such as heat, humidity, radiation, and acidic or alkaline conditions, could modify the degradation process and its rate. The degradation process can alter polymer properties such as mechanical, optical, electrical, discoloration, phase separation or delamination, erosion, cracking, and crazing. The four main abiotic mechanisms associated with polymer degradation are mechanical, thermal (or thermo-oxidative), photo (photo-oxidative), and hydrolytic (chemical) degradation, some of which can be assisted by catalysis. In addition, ozone degradation (chemical) is considered a mechanism of degradation for polymers but is less common. The biotic degradation involves the action of microorganisms by enzymatic action.
  • 2.5K
  • 27 Oct 2022
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