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Monday, June 10, 2019

Electrothermal-Chemical Technology


Electrothermal-chemical (ETC) technology is an attempt to increase accuracy and muzzle energy of future tankartillery, and close-in weapon system guns by improving the predictability and rate of expansion of propellants inside the barrel. An electrothermal-chemical gun uses a plasma cartridge to ignite and control the ammunition's propellant, using electrical energy to trigger the process. ETC increases the performance of conventional solid propellants, reduces the effect of temperature on propellant expansion and allows for more advanced, higher density propellants to be used.

The technology has been under development since the mid-1980s and at present is actively being researched in the United States by the Army Research LaboratorySandia National Laboratories and defense industry contractors, including FMC CorporationGeneral Dynamics Land SystemsOlin Ordnance, and Soreq Nuclear Research Center. It is possible that electrothermal-chemical gun propulsion will be an integral part of US Army's future combat system and those of other countries such as Germany and the United Kingdom. ETC technology offers a medium-risk upgrade and is developed to the point that further improvements are so minor that it can be considered mature.

Nevertheless, there is substantial existing evidence that ETC technology is viable and worth the money to continue development. Furthermore, it can be integrated into current gun systems. ETC increases the performance of conventional solid propellants, reduces the effect of temperature on propellant expansion and allows for more advanced, higher density propellants to be used. It will also reduce pressure placed on the barrel in comparison to alternative technologies that offer the same muzzle energy given the fact that it helps spread the propellant's gas much more smoothly during ignition. Currently, there are two principal methods of plasma initiation: the flashboard large area emitter (FLARE) and the triple coaxial plasma igniter (TCPI).

Cloaking Device


cloaking device is a hypothetical or fictional stealth technology that can cause objects, such as spaceships or individuals, to be partially or wholly invisible to parts of the electromagnetic (EM) spectrum. However, over the entire spectrum, a cloaked object scatters more than an uncloaked object. Fictional cloaking devices have been used as plot devices in various media for many years. Developments in scientific research show that real-world cloaking devices can obscure objects from at least one wavelength of EM emissions. Scientists already use artificial materials called metamaterials to bend light around an object.  An operational, non-fictional cloaking device might be an extension of the basic technologies used by stealth aircraft, such as radar-absorbing dark paint, optical camouflage, cooling the outer surface to minimize electromagnetic emissions (usually infrared), or other techniques to minimize other EM emissions, and to minimize particle emissions from the object.

 The use of certain devices to jam and confuse remote sensing devices would greatly aid in this process, but is more properly referred to as "active camouflage". Alternatively, metamaterials provide the theoretical possibility of making electromagnetic radiation pass freely around the 'cloaked' object. Optical metamaterials have featured in several recent proposals for invisibility schemes. "Metamaterials" refers to materials that owe their refractive properties to the way they are structured, rather than the substances that compose them. Using transformation optics it is possible to design the optical parameters of a "cloak" so that it guides light around some region, rendering it invisible over a certain band of wavelengths.

These spatially varying optical parameters do not correspond to any natural material, but may be implemented using metamaterials. There are several theories of cloaking, giving rise to different types of invisibility. In 2014, scientists demonstrated good cloaking performance in murky water, demonstrating that an object shrouded in fog can disappear completely when appropriately coated with metamaterial. This is due to the random scattering of light, such as that which occurs in clouds, fog, milk, frosted glass, etc., combined with the properties of the metamaterial coating. When light is diffused, a thin coat of metamaterial around an object can make it essentially invisible under a range of lighting condition.



Vehicular Communication Systems


Vehicular communication systems are computer networks in which vehicles and roadside units are the communicating nodes, providing each other with information, such as safety warnings and traffic information. They can be effective in avoiding accidents and traffic congestion. Both types of nodes are dedicated short-range communications (DSRC) devices. DSRC works in 5.9 GHz band with bandwidth of 75 MHz and approximate range of 300 m. Vehicular communications is usually developed as a part of intelligent transportation systems (ITS). The main motivation for vehicular communication systems is safety and eliminating the excessive cost of traffic collisions. According to the World Health Organization (WHO), road accidents annually cause approximately 1.2 million deaths worldwide; one fourth of all deaths caused by injury. A study from the American Automobile Association (AAA) concluded that car crashes cost the United States $300 billion per year. It can be used for automated traffic intersection control.

 However the deaths caused by car crashes are in principle avoidable. The U.S. Department of Transportation states that 21,000 of the annual 43,000 road accident deaths in the US are caused by roadway departures and intersection-related incidents. This number can be significantly lowered by deploying local warning systems through vehicular communications. Departing vehicles can inform other vehicles that they intend to depart the highway and arriving cars at intersections can send warning messages to other cars traversing that intersection. Studies show that in Western Europe a mere 5 km/h decrease in average vehicle speeds could result in 25% decrease in deaths.

V2V (short for vehicle to vehicle; see also VANET) is an automobile technology designed to allow automobiles to "talk" to each other. The systems will use a region of the 5.9 GHz band set aside by the United States Congress in 1999, the unlicensed frequency also used by WiFi. V2V is currently in active development by General Motors, which demonstrated the system in 2006 using Cadillac vehicles. Other automakers working on V2V include BMWDaimlerHondaAudiToyotaVolvo and the Car-to-Car communication consortium. V2V is also known as VANETs (vehicular ad hoc networks). It is a variation of MANETs (mobile ad hoc networks), with the emphasis being now the node is the vehicular. In 2001, it was mentioned in a publication that ad hoc networks can be formed by cars and such networks can help overcome blind spots, avoid accidents, etc.

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