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Topic Review
Prepay Mobile Phone
A prepay mobile device (also commonly referred to as pay-as-you-go (PAYG), pay-as-you-talk, pay and go, go-phone or prepaid) is a mobile device such as a phone for which credit is purchased in advance of service use. The purchased credit is used to pay for telecommunications services at the point the service is accessed or consumed. If there is no credit, then access is denied by the mobile network. Users can top up their credit at any time using a variety of payment mechanisms. The alternative billing method (and what is commonly referred to as a mobile contract) is the postpaid mobile phone, where a user enters into a long-term (lasting 12, 18 or 24 months) or short-term (also commonly referred to as a rolling contract or a 30-day contract) billing arrangement with a mobile network operator or carriage service provider (CSP). "Pay-as-you-go", "PAYG", and similar terms are also used for other non-telecommunications services paid for in the same way.
  • 309
  • 16 Nov 2022
Topic Review
Indonesian Car
Indonesian national car is the categorization of a Low Cost Green Car (LCGC) in Indonesia with the following initial specifications: Priced between 50,000,000 Indonesian rupiah for villagers to Rp 85,000,000 for the general public[1]; Fuel efficiency of at least 20 km/l (56 mpg‑imp; 47 mpg‑US); Made up from at least 60% domestic components.
  • 603
  • 16 Nov 2022
Topic Review
DTS (Sound System)
DTS, Inc. (originally Digital Theater Systems) is an American company that makes multichannel audio technologies for film and video. Based in Calabasas, California, the company introduced its DTS technology in 1993 as a competitor to Dolby Laboratories, incorporating DTS in the film Jurassic Park (1993). The DTS product is used in surround sound formats for both commercial/theatrical and consumer-grade applications. It was known as The Digital Experience until 1995. DTS licenses its technologies to consumer electronics manufacturers. The DTS brand was acquired by Tessera Holding Corporation in December 2016, then Tessera was renamed to Xperi Corporation.
  • 1.9K
  • 15 Nov 2022
Topic Review
Social Learning Tools
Social learning tools are tools used for pedagogical and andragogical purposes that utilize social software and/or social media in order to facilitate learning through interactions between individuals and systems. The idea of setting up "social learning tools" is to make education more convenient and widespread. It also allows an interaction between users and/or the software which can bring a different aspect to learning. People can acquire knowledge by distance learning tools, for instance, Facebook, Twitter, Khan Academy and so on. Social learning tools may mediate in formal or informal learning environments to help create connections between learners, instructors and information. These connections form dynamic knowledge networks. Social learning tools are used in schools for teaching/learning and in businesses for training. Within a school environment, the use of social learning tools can affect not only the user (student) but his/her caretaker as well as his/her instructor. It brings a different approach to the traditional way of learning which affects the student and his/her support circle. Companies also use social learning tools. They used them to improve knowledge transfer within departments and across teams. Businesses use a variety of these tools to create a social learning environment. They are also used in company settings to help improve team work, problem solving, and performance in stressful situations. Social learning tools are used for people who are willing to share their good ideas/thoughts with someone else. The ideas can be related to either the academic studies or any other daily skills that we want to share with others. Social learning tools connect learning to our daily lives. It creates a learning environment more truthful to today's society. There are a couple of common elements that should be present in a social learning tool. Technology should be involved to allow physical and cognitive learning. There should be interactions between the people who use the tool and interactions with the software. Another element is trust. Users should trust the software and what other people have created.
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  • 15 Nov 2022
Topic Review
Last Mile
The last mile or last kilometer is a phrase widely used in the telecommunications, cable television and internet industries to refer to the final leg of the telecommunications networks that deliver telecommunication services to retail end-users (customers). More specifically, the last mile describes the portion of the telecommunications network chain that physically reaches the end-user's premises. Examples are the copper wire subscriber lines connecting landline telephones to the local telephone exchange; coaxial cable service drops carrying cable television signals from utility poles to subscribers' homes, and cell towers linking local cell phones to the cellular network. The word "mile" is used metaphorically; the length of the last mile link may be more or less than a mile. Because the last mile of a network to the user is conversely the first mile from the user's premises to the outside world when the user is sending data, the term first mile is also alternatively used. The last mile is typically the speed bottleneck in communication networks; its bandwidth effectively limits the amount of data that can be delivered to the customer. This is because retail telecommunication networks have the topology of "trees", with relatively few high capacity "trunk" communication channels branching out to feed many final mile "twigs". The final mile links, being the most numerous and thus the most expensive part of the system, as well as having to interface with a wide variety of user equipment, are the most difficult to upgrade to new technology. For example, telephone trunklines that carry phone calls between switching centers are made of modern optical fiber, but the last mile is typically twisted pair wires, a technology which has essentially remained unchanged for over a century since the original laying of copper phone cables. To resolve, or at least mitigate, the problems involved with attempting to provide enhanced services over the last mile, some firms have been mixing networks for decades. One example is fixed wireless access, where a wireless network is used instead of wires to connect a stationary terminal to the wireline network. Various solutions are being developed which are seen as an alternative to the last mile of standard incumbent local exchange carriers. These include WiMAX and broadband over power lines. In recent years, usage of the term "last mile" has expanded outside the communications industries, to include other distribution networks that deliver goods to customers, such as the pipes that deliver water and natural gas to customer premises, and the final legs of mail and package delivery services. The term has also been used to describe education and training providers that more tightly link individuals with job opportunities.
  • 362
  • 15 Nov 2022
Topic Review
Douglas–Grumman Scandal
The Douglas-Grumman Scandal was a bribery scandal that rocked Japan in February 1979, concerning the sale of American fighter jets.
  • 353
  • 15 Nov 2022
Topic Review
Ultrafast Laser Spectroscopy
Ultrafast laser spectroscopy is a spectroscopic technique that uses ultrashort pulse lasers for the study of dynamics on extremely short time scales (attoseconds to nanoseconds). Different methods are used to examine dynamics of charge carriers, atoms and molecules. Many different procedures have been developed spanning different time scales and photon energy ranges; some common methods are listed below.
  • 500
  • 15 Nov 2022
Topic Review
Molten Salt Reactor
A molten salt reactor (MSR) is a class of nuclear fission reactor in which the primary nuclear reactor coolant and/or the fuel is a molten salt mixture. Only two MSRs have ever operated, both research reactors in the United States . The 1950's Aircraft Reactor Experiment was primarily motivated by the compact size that the technique offers, while the 1960's Molten-Salt Reactor Experiment aimed to prove the concept of a nuclear power plant which implements a thorium fuel cycle in a breeder reactor. Increased research into Generation IV reactor designs began to renew interest in the technology, with multiple nations having projects and, as of September 2021, China is on the verge of starting its TMSR-LF1 thorium MSR. MSRs are considered safer than conventional reactors because they operate with fuel already in a molten state, and in event of an emergency, the fuel mixture is designed to drain from the core where it will solidify, preventing the type of nuclear meltdown and associated hydrogen explosions (like what happened in the Fukushima nuclear disaster) that are at risk in conventional (solid-fuel) reactors. They operate at or close to atmospheric pressure, rather than the 75-150 times atmospheric pressure of a typical light-water reactor (LWR), hence reducing the need for large, expensive reactor pressure vessels used in LWRs. Another characteristic of MSRs is that the radioactive fission gases produced are absorbed into the molten salt, as opposed to conventional reactors where the fuel rod tubes must contain the gas. MSR's can also be refueled while operating (essentially online-nuclear reprocessing) while conventional reactors must be shut down for refueling (Heavy water reactors like the CANDU or the Atucha-class PHWRs being a notable exception). A further key characteristic of MSRs is operating temperatures of around 700 °C (1,292 °F), significantly higher than traditional LWRs at around 300 °C (572 °F), providing greater electricity-generation efficiency, the possibility of grid-storage facilities, economical hydrogen production, and, in some cases, process-heat opportunities. Relevant design challenges include the corrosivity of hot salts and the changing chemical composition of the salt as it is transmuted by the neutron flux in the reactor core. MSRs offer multiple advantages over conventional nuclear power plants, although for historical reasons they have not been deployed.
  • 1.7K
  • 15 Nov 2022
Topic Review
Near-Infrared Spectroscopy
Near-infrared spectroscopy (NIRS) is a spectroscopic method that uses the near-infrared region of the electromagnetic spectrum (from 780 nm to 2500 nm). Typical applications include medical and physiological diagnostics and research including blood sugar, pulse oximetry, functional neuroimaging, sports medicine, elite sports training, ergonomics, rehabilitation, neonatal research, brain computer interface, urology (bladder contraction), and neurology (neurovascular coupling). There are also applications in other areas as well such as pharmaceutical, food and agrochemical quality control, atmospheric chemistry, combustion research and astronomy.
  • 1.3K
  • 15 Nov 2022
Topic Review
Straight-Six Engine
The straight-six engine (also referred to as an inline-six engine; abbreviated I6 or L6) is an internal combustion engine, with six cylinders mounted in a straight line along the crankcase with all the pistons driving a common crankshaft (straight engine). The bank of cylinders may be oriented at any angle, and where the bank is inclined away from the vertical, the engine is sometimes called a slant-six (although this is also a Chrysler-specific design). The straight-six layout is the simplest engine layout that possesses both primary and secondary mechanical engine balance, resulting in much less vibration than engines with fewer cylinders.
  • 7.8K
  • 15 Nov 2022
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