In physics, and in particular as measured by radiometry, radiant energy is the energy of electromagnetic and gravitational radiation. As energy, its SI unit is the joule (J). The quantity of radiant energy may be calculated by integratingradiant flux (or power) with respect to time. The symbol Qe is often used throughout literature to denote radiant energy (“e” for “energetic”, to avoid confusion with photometric quantities). In branches of physics other than radiometry, electromagnetic energy is referred to using E or W. The term is used particularly when electromagnetic radiation is emitted by a source into the surrounding environment. This radiation may be visible or invisible to the human eye.
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by a radio receiver connected to another antenna. Radio is very widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing and other applications.
In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking and satellite communication among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraft and missiles, a beam of radio waves emitted by a radar transmitter reflects off the target object, and the reflected waves reveal the object’s location. In radio navigation systems such as GPS and VOR, a mobile receiver receives radio signals from navigational radio beacons whose position is known, and by precisely measuring the arrival time of the radio waves the receiver can calculate its position on Earth. In wireless radio remote control devices like drones, garage door openers, and keyless entry systems, radio signals transmitted from a controller device control the actions of a remote device.
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Radio broadcasting is transmission of audio (sound), sometimes with related metadata, by radio waves intended to reach a wide audience. In terrestrial radio broadcasting the radio waves are broadcast by a land-based radio station, while in satellite radio the radio waves are broadcast by a satellite in Earth orbit. To receive the content the listener must have a broadcast radio receiver (radio). Stations are often affiliated with a radio network which provides content in a common radio format, either in broadcast syndication or simulcast or both. Radio stations broadcast with several different types of modulation: AM radio stations transmit in AM (amplitude modulation), FM radio stations transmit in FM (frequency modulation), which are older analog audio standards, while newer digital radio stations transmit in several digital audio standards: DAB (digital audio broadcasting), HD radio, DRM (Digital Radio Mondiale). Television broadcasting is a separate service which also uses radio frequencies to broadcast television (video) signals.
A radio format or programming format (not to be confused with broadcast programming) describes the overall content broadcast on a radio station. The radio format emerged mainly in the United States in the 1950s, at a time when radio was compelled to develop new and exclusive ways to programming by competition with television. Since then, the formula has spread as a reference for commercial radio programming worldwide.
A radio format aims to reach a more or less specific audience according to a certain type of programming, which can be thematic or general, more informative or more musical, among other possibilities.[nb 1] Radio formats are often used as a marketing tool and are subject to frequent changes.
Except News/Talk, All-Talk or Sports formats, most programming format is based on predominantly to commercially music. However the term also includes the news, bulletins, DJ talk, jingles, commercials, competitions, traffic news, sports, weather and community announcements between the tracks.
Throughout its historical development, the American radio industry has changed its formats not only to contend against the newer and more competitive forms of entertainment media – such as television –, as well to pleasure the contemporary tastes of the American audience and earn profits by meeting the entertainment demands more sufficiently to the benefit of all parties affected. Indeed, the same phenomena has happened in other parts of the world.
Radio-frequency (RF) engineering is a subset of electronic engineering involving the application of transmission line, waveguide, antenna and electromagnetic field principles to the design and application of devices that produce or utilize signals within the radio band, the frequency range of about 20 kHz up to 300 GHz.
It is incorporated into almost everything that transmits or receives a radio wave, which includes, but is not limited to, mobile phones, radios, Wi-Fi, and two-way radios. RF engineering is a highly specialized field that typically includes the following areas of expertise:
A radio program, radio programme or radio show is a segment of content intended for broadcast on radio. It may be a one-time production or part of a periodically recurring series. A single program in a series is called an episode.
In the 1950s, a small but growing cohort of Rock and pop music fans, dissatisfied with the BBC’s output, would listen to Radio Luxembourg, but to some extent and probably not enough to have any impact on the BBC’s monopoly and invariably only at night, when the signal from Luxembourg was stronger. During the post-1964 period, western Europe offshore radio (such as Radio Caroline broadcasting from ships at anchor or abandoned forts) helped to supply the demand for the pop and rock music. The BBC launched its own pop music station, BBC Radio 1, in 1967.
The international broadcasts became highly popular in major world languages. Of particular impact were programmes by BBC World Service, Voice of America, Radio Moscow, China Radio International, Radio France Internationale (RFI), Deutsche Welle (DW), Radio Free Europe/Radio Liberty (RFE/RL), Vatican Radio and Trans World Radio etc.
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300 gigahertz (GHz) to as low as 30 hertz (Hz). At 300 GHz, the corresponding wavelength is 1 mm, and at 30 Hz is 10,000 km. Like all other electromagnetic waves, radio waves travel at the speed of light in vacuum. They are generated by electric charges undergoing acceleration, such as time varying electric currents. Naturally occurring radio waves are emitted by lightning and astronomical objects.
RAM – Random-access memory
Random-access memory (RAM /ræm/) is a form of computer memory that can be read and changed in any order, typically used to store working data and machine code. A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the physical location of data inside the memory. In contrast, with other direct-access data storage media such as hard disks, CD-RWs, DVD-RWs and the older magnetic tapes and drum memory, the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement.
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Real-time computer graphics or real-time rendering is the sub-field of computer graphics focused on producing and analyzing images in real time. The term can refer to anything from rendering an application’s graphical user interface (GUI) to real-time image analysis, but is most often used in reference to interactive 3D computer graphics, typically using a graphics processing unit (GPU). One example of this concept is a video game that rapidly renders changing 3D environments to produce an illusion of motion.
Real-time computing (RTC), or reactive computing is the computer science term for hardware and software systems subject to a “real-time constraint”, for example from event to system response. Real-time programs must guarantee response within specified time constraints, often referred to as “deadlines”.
Real-time responses are often understood to be in the order of milliseconds, and sometimes microseconds. A system not specified as operating in real time cannot usually guarantee a response within any timeframe, although typical or expected response times may be given. Real-time processing fails if not completed within a specified deadline relative to an event; deadlines must always be met, regardless of system load.
A real-time system has been described as one which “controls an environment by receiving data, processing them, and returning the results sufficiently quickly to affect the environment at that time”. The term “real-time” is also used in simulation to mean that the simulation’s clock runs at the same speed as a real clock, and in process control and enterprise systems to mean “without significant delay”.
Real-time software may use one or more of the following: synchronous programming languages, real-time operating systems, and real-time networks, each of which provide essential frameworks on which to build a real-time software application.
Systems used for many mission critical applications must be real-time, such as for control of fly-by-wire aircraft, or anti-lock brakes, both of which demand immediate and accurate mechanical response.
Real-time text (RTT) is text transmitted instantly as it is typed or created. Recipients can immediately read the message while it is being written, without waiting.
Real-time text is used for conversational text, in collaboration, and in live captioning. Technologies include TDD/TTY devices for the deaf, live captioning for TV, Text over IP (ToIP), some types of instant messaging, captioning for telephony/video teleconferencing, telecommunications relay services including ip-relay, transcription services including Remote CART, TypeWell, collaborative text editing, streaming text applications, next-generation 9-1-1/1-1-2 emergency service. Obsolete TDD/TTY devices are being replaced by more modern real-time text technologies, including Text over IP, ip-relay, and instant messaging.
During 2012, the Real-Time Text Taskforce (R3TF) designed a standard international symbol to represent real-time text, as well as the alternate name Fast Text to improve public education of the technology.
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realme is a Chinese smartphone manufacturer headquartered in Shenzhen. The company was founded on May 4, 2018 by Sky Li (Li Bingzhong), who was former vice president of Oppo. It’s a spinoff from Oppo who collectively owns it with BBK Electronics.
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Red Hat, Inc. is an American multinational software company that provides open source software products to enterprises. Founded in 1993, Red Hat has its corporate headquarters in Raleigh, North Carolina, with other offices worldwide. It became a subsidiary of IBM on July 9, 2019.
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Reddit (/ˈrɛdɪt/, stylized in all lowercase) is a social news aggregation, web content rating, and discussion website, recently including livestream content through Reddit Public Access Network.
Registered members submit content to the site such as links, text posts, images, and videos, which are then voted up or down by other members. Posts are organized by subject into user-created boards called “communities” or “subreddits”, which cover a variety of topics such as news, politics, science, movies, video games, music, books, sports, fitness, cooking, pets, and image-sharing. Submissions with more up-votes appear towards the top of their subreddit and, if they receive enough up-votes, ultimately on the site’s front page. Despite strict rules prohibiting harassment, Reddit’s administrators spend considerable resources on moderating the site.
In engineering, redundancy is the duplication of critical components or functions of a system with the intention of increasing reliability of the system, usually in the form of a backup or fail-safe, or to improve actual system performance, such as in the case of GNSS receivers, or multi-threaded computer processing.
In many safety-critical systems, such as fly-by-wire and hydraulic systems in aircraft, some parts of the control system may be triplicated, which is formally termed triple modular redundancy (TMR). An error in one component may then be out-voted by the other two. In a triply redundant system, the system has three sub components, all three of which must fail before the system fails. Since each one rarely fails, and the sub components are expected to fail independently, the probability of all three failing is calculated to be extraordinarily small; often outweighed by other risk factors, such as human error. Redundancy may also be known by the terms “majority voting systems” or “voting logic”.
A relational database is a digital database based on the relational model of data, as proposed by E. F. Codd in 1970. A software system used to maintain relational databases is a relational database management system (RDBMS). Many relational database systems have an option of using the SQL (Structured Query Language) for querying and maintaining the database.
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Remote administration refers to any method of controlling a computer from a remote location. Software that allows remote administration is becoming increasingly common and is often used when it is difficult or impractical to be physically near a system in order to use it. A remote location may refer to a computer in the next room or one on the other side of the world. It may also refer to both legal and illegal (i.e. hacking) remote administration (see Owned and Trojan).
Remote patient monitoring
Remote patient monitoring (RPM) is a technology to enable monitoring of patients outside of conventional clinical settings, such as in the home or in a remote area, which may increase access to care and decrease healthcare delivery costs.
Incorporating RPM in chronic-disease management may significantly improve an individual’s quality of life, by allowing patients to maintain independence, prevent complications, and to minimize personal costs. RPM facilitates these goals by delivering care through telecommunications. This form of patient monitoring can be particularly important when patients are managing complex self-care processes such as home hemodialysis. Key features of RPM, like remote monitoring and trend analysis of physiological parameters, enable early detection of deterioration; thereby reducing emergency department visits, hospitalizations, and the duration of hospital stays.
With the COVID-19 pandemic, health systems rapidly adopted remote patient monitoring technology. Within the next 5 years,[when?] the RPM market is expected to double in size.
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Groupe Renault (UK: /ˈrɛnoʊ/ REN-oh, US: /rəˈnɔːlt, rəˈnoʊ/ rə-NAWLT, rə-NOH, French: [ɡʁup ʁəno], also known as the Renault Group in English; legally Renault S.A.) is a French multinational automobile manufacturer established in 1899. The company produces a range of cars and vans, and in the past has manufactured trucks, tractors, tanks, buses/coaches, aircraft and aircraft engines, and autorail vehicles.
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The Renault–Nissan–Mitsubishi Alliance is a French-Japanese strategic alliance between the automobile manufacturers Renault (based in Boulogne-Billancourt, France), Nissan (based in Yokohama, Japan) and Mitsubishi Motors (based in Tokyo, Japan), which together sell more than 1 in 9 vehicles worldwide. Originally known as the Renault–Nissan Alliance from 1999 onwards, Renault and Nissan became strategic partners in 1999 and have nearly 450,000 employees and control ten major brands: Renault, Nissan, Mitsubishi, Infiniti, Renault Samsung, Dacia, Alpine, Datsun, Venucia and Lada. The car group sold 10.6 million vehicles worldwide in 2017, making it the leading light vehicle manufacturing group in the world. The Alliance adopted its current name in September 2017, one year after Nissan acquired a controlling interest in Mitsubishi and subsequently made Mitsubishi an equal partner in the Alliance.
As of December 2019, the Alliance is one of the world’s leading electric vehicle manufacturing groups, with global sales of over 800,000 electric vehicles since 2010. The top selling vehicles of the Alliance EV line-up are the Nissan Leaf and the Renault Zoe all-electric cars.
The strategic partnership between Renault, Nissan and Mitsubishi is not a merger or an acquisition. The three companies are joined together through a cross-sharing agreement. The structure was unique in the auto industry during the 1990s consolidation trend and later served as a model for General Motors and the PSA Group, and Mitsubishi, as well as the Volkswagen Group and Suzuki, though the latter combination failed. The Alliance itself has broadened its scope substantially, forming additional partnerships with automakers including Germany’s Daimler and China’s Dongfeng.
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Research is “creative and systematic work undertaken to increase the stock of knowledge”. It involves the collection, organization, and analysis of information to increase understanding of a topic or issue. A research project may be an expansion on past work in the field. To test the validity of instruments, procedures, or experiments, research may replicate elements of prior projects or the project as a whole.
The primary purposes of basic research (as opposed to applied research) are documentation, discovery, interpretation, and the research and development (R&D) of methods and systems for the advancement of human knowledge. Approaches to research depend on epistemologies, which vary considerably both within and between humanities and sciences. There are several forms of research: scientific, humanities, artistic, economic, social, business, marketing, practitioner research, life, technological, etc. The scientific study of research practices is known as meta-research.
Research and development
Research and development (R&D, R+D), known in Europe as research and technological development (RTD), is the set of innovative activities undertaken by corporations or governments in developing new services or products and improving existing ones. Research and development constitutes the first stage of development of a potential new service or the production process.
The Ricoh Company, Ltd. (/ˈriːkoʊ/) (株式会社リコー, Kabushiki-gaisha Rikō) is a Japanese multinational imaging and electronics company. It was founded by the now-defunct commercial division of the Institute of Physical and Chemical Research (Riken) known as the Riken Concern, on 6 February 1936 as Riken Sensitized Paper (理研感光紙, Riken Kankōshi). Ricoh’s headquarters are located in Ota, Tokyo.
RKO Pictures was an American film production and distribution company. In its original incarnation, as RKO Radio Pictures, Inc. (a subsidiary of Radio-Keith-Orpheum, aka: RKO) it was one of the Big Five studios of Hollywood’s Golden Age. The business was formed after the Keith-Albee-Orpheum (KAO) theater chain and Joseph P. Kennedy’s Film Booking Offices of America (FBO) studio were brought together under the control of the Radio Corporation of America (RCA) in October 1928.[a] RCA chief David Sarnoff engineered the merger to create a market for the company’s sound-on-film technology, RCA Photophone. By the mid-1940s, the studio was under the control of investor Floyd Odlum.
Road transport or road transportation is a type of transport by using roads. Transport on roads can be roughly grouped into the transportation of goods and transportation of people. In many countries licensing requirements and safety regulations ensure a separation of the two industries. Movement along roads may be by bike or automobile, truck, or by animal such as horse or oxen. Standard networks of roads were adopted by Romans, Persians, Aztec, and other early empires, and may be regarded as a feature of empires. Cargo may be transported by trucking . companies, while passengers may be transported via mass transit. Commonly defined features of modern roads include defined lanes and signage. Various classes of road exist, from two-lane local roads with at-grade intersections to controlled-access highways with all cross traffic grade-separated.
The nature of road transportation of goods depends on, apart from the degree of development of the local infrastructure, on the distance the goods are transported by road, the weight and volume of an individual shipment, and the type of goods transported. For short distances and light, small shipments a van or pickup truck may be used. For large shipments even if less than a full truckload a truck is more appropriate. (Also see Trucking and Hauling below). In some countries cargo is transported by road in horse-drawn carriages, donkey carts or other non-motorized mode. Delivery services are sometimes considered a separate category from cargo transport. In many places fast food is transported on roads by various types of vehicles. For inner city delivery of small packages and documents bike couriers are quite common.
People are transported on roads. Special modes of individual transport by road such as cycle rickshaws may also be locally available. There are also specialist modes of road transport for particular situations, such as ambulances.
A robot is a machine—especially one programmable by a computer— capable of carrying out a complex series of actions automatically. Robots can be guided by an external control device or the control may be embedded within. Robots may be constructed on the lines of human form, but most robots are machines designed to perform a task with no regard to their aesthetics.
Robotics is an interdisciplinary branch of engineering and science that includes mechanical engineering, electronic engineering, information engineering, computer science, and others. Robotics deals with the design, construction, operation, and use of robots, as well as computer systems for their control, sensory feedback, and information processing.
A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. Data sent through the internet, such as a web page or email, is in the form of data packets. A packet is typically forwarded from one router to another router through the networks that constitute an internetwork (e.g. the Internet) until it reaches its destination node. A Cisco ASM/2-32EM router deployed at CERN in 1987
A router is connected to two or more data lines from different IP networks. When a data packet comes in on one of the lines, the router reads the network address information in the packet header to determine the ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey.
The most familiar type of IP routers are home and small office routers that simply forward IP packets between the home computers and the Internet. More sophisticated routers, such as enterprise routers, connect large business or ISP networks up to the powerful core routers that forward data at high speed along the optical fiber lines of the Internet backbone.
Routing is the process of selecting a path for traffic in a network or between or across multiple networks. Broadly, routing is performed in many types of networks, including circuit-switched networks, such as the public switched telephone network (PSTN), and computer networks, such as the Internet.
In packet switching networks, routing is the higher-level decision making that directs network packets from their source toward their destination through intermediate network nodes by specific packet forwarding mechanisms. Packet forwarding is the transit of network packets from one network interface to another. Intermediate nodes are typically network hardware devices such as routers, gateways, firewalls, or switches. General-purpose computers also forward packets and perform routing, although they have no specially optimized hardware for the task.
The routing process usually directs forwarding on the basis of routing tables. Routing tables maintain a record of the routes to various network destinations. Routing tables may be specified by an administrator, learned by observing network traffic or built with the assistance of routing protocols.
Routing, in a narrower sense of the term, often refers to IP routing and is contrasted with bridging. IP routing assumes that network addresses are structured and that similar addresses imply proximity within the network. Structured addresses allow a single routing table entry to represent the route to a group of devices. In large networks, structured addressing (routing, in the narrow sense) outperforms unstructured addressing (bridging). Routing has become the dominant form of addressing on the Internet. Bridging is still widely used within local area networks.
The Routing Information Protocol (RIP) is one of the oldest distance-vector routing protocols which employs the hop count as a routing metric. RIP prevents routing loops by implementing a limit on the number of hops allowed in a path from source to destination. The largest number of hops allowed for RIP is 15, which limits the size of networks that RIP can support.
RIP implements the split horizon, route poisoning and holddown mechanisms to prevent incorrect routing information from being propagated.
In RIPv1 routers broadcast updates with their routing table every 30 seconds. In the early deployments, routing tables were small enough that the traffic was not significant. As networks grew in size, however, it became evident there could be a massive traffic burst every 30 seconds, even if the routers had been initialized at random times.