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HandWiki is the world's largest wiki-style encyclopedia dedicated to science, technology and computing. It allows you to create and edit articles as long as you have external citations and login account. In addition, this is a content management environment that can be used for collaborative editing of original scholarly content, such as books, manuals, monographs and tutorials.

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Setspn
Kerberos (/ˈkɜːrbərɒs/) is a computer-network authentication protocol that works on the basis of tickets to allow nodes communicating over a non-secure network to prove their identity to one another in a secure manner. Its designers aimed it primarily at a client–server model, and it provides mutual authentication—both the user and the server verify each other's identity. Kerberos protocol messages are protected against eavesdropping and replay attacks. Kerberos builds on symmetric-key cryptography and requires a trusted third party, and optionally may use public-key cryptography during certain phases of authentication. Kerberos uses UDP port 88 by default. The protocol was named after the character Kerberos (or Cerberus) from Greek mythology, the ferocious three-headed guard dog of Hades.
  • 1.9K
  • 25 Oct 2022
Topic Review
Emergency Position-Indicating Radiobeacon Station
An emergency position-indicating radiobeacon (EPIRB) is a type of emergency locator beacon, a portable battery powered radio transmitter used in emergencies to locate airplanes, vessels, and persons in distress and in need of immediate rescue. In the event of an emergency, such as the ship sinking or an airplane crash, the transmitter is activated and begins transmitting a continuous radio signal which is used by search and rescue teams to quickly locate the emergency and render aid. The signal is detected by satellites operated by an international consortium of rescue services, COSPAS-SARSAT. The basic purpose of this system is to help rescuers find survivors within the so-called "golden day" (the first 24 hours following a traumatic event) during which the majority of survivors can usually be saved. The feature distinguishing modern EPIRBs, often called GPIRBs, from other types of emergency beacon is that it contains a GPS receiver and broadcasts its position, usually accurate within 100 metres (330 ft), to facilitate location. The standard frequency of a modern EPIRB is 406 MHz. It is an internationally regulated mobile radiocommunication service that aids search and rescue operations to detect and locate distressed boats, aircraft, and people. It is distinct from a Satellite emergency position-indicating radiobeacon station. The first form of these beacons was the 121.500 MHz ELT, which was designed as an automatic locator beacon for crashed military aircraft. These beacons were first used in the 1950s by the U.S. military and were mandated for use on many types of commercial and general aviation aircraft beginning in the early 1970s. The frequency and signal format used by the ELT beacons was not designed for satellite detection, which resulted in a system with poor location detection abilities and with long delays in detection of activated beacons. The satellite detection network was built after the ELT beacons were already in general use, with the first satellite not being launched until 1982, and even then, the satellites only provided detection, with location accuracy being roughly 20 kilometres (12 mi). The technology was later expanded to cover use on vessels at sea (EPIRB), individual persons (PLB and, starting in 2016, MSLD). All have migrated from using 121.500 MHz as their primary frequency to using 406 MHz, which was designed for satellite detection and location. Since the inception of Cospas-Sarsat in 1982, distress radiobeacons have assisted in the rescue of over 28,000 people in more than 7,000 distress situations. In 2010 alone, the system provided information used to rescue 2,388 persons in 641 distress situations.
  • 3.2K
  • 27 Oct 2022
Topic Review
Sound Trap
A sound trap, also known as a duct silencer, sound attenuator, or muffler, is a special acoustical treatment of Heating Ventilating and Air-Conditioning (HVAC) ductwork designed to reduce transmission of noise through the ductwork, either from equipment into occupied spaces in a building, or between occupied spaces. In its simplest form, a sound trap consists of an baffle within the ductwork. These baffles often contain sound-absorbing materials. The physical dimensions and baffle configuration of sound traps are selected to attenuate a specific range of frequencies. Unlike conventional internally-lined ductwork, which is only effective at attenuating mid- and high-frequency noise, sound traps can achieve broader band attenuation in relatively short lengths. Certain types of sound traps are essentially a Helmholtz resonator used as a passive noise-control device.
  • 2.1K
  • 25 Oct 2022
Topic Review
FreeTrack
FreeTrack is a general-purpose optical motion tracking application for Microsoft Windows, released under the GNU General Public License, that can be used with common inexpensive cameras. Its primary focus is head tracking with uses in virtual reality, simulation, video games, 3D modeling, computer aided design and general hands-free computing to improve computer accessibility. Tracking can be made sensitive enough that only small head movements are required so that the user's eyes never leave the screen. A camera is positioned to observe a rigid point model worn by the user, the points of which need to be isolated from background light by means of physical and software filtering. Motion is tracked with up to six degrees of freedom (6DOF): yaw, pitch, roll, left/right, up/down and forward/back. Windows-compatible video devices like webcams are supported, as well as special Nintendo Wii Remote camera, iPhone Truedepth camera with Eyeware Beam, and NaturalPoint cameras (TrackIR, SmartNav and OptiTrack). FreeTrack can output head-tracking data to programs directly using its own open interface, as well as TrackIR, SimConnect and FSUIPC interfaces. Programs that support these interfaces are regarded as being FreeTrack-compatible. FreeTrack can also emulate mouse, keyboard, and joystick (via PPJoy) if a program does not support a direct interface. FreeTrack is coded in Delphi 7 and uses DirectShow and DirectX. Head tracking is achieved using implementations of DeMenthon's four-point iterative pose estimation algorithm (POSIT) and Alter's three point geometric algorithm.
  • 1.4K
  • 24 Oct 2022
Topic Review
Necrotizing Ulcerative Gingivitis
Acute necrotizing ulcerative gingivitis (ANUG) is a common, non-contagious infection of the gums with sudden onset. The main features are painful, bleeding gums, and ulceration of inter-dental papillae (the sections of gum between adjacent teeth). This disease, along with necrotizing (ulcerative) periodontitis (NP or NUP) is classified as a necrotizing periodontal disease, one of the seven general types of gum disease caused by inflammation of the gums (periodontitis). The often severe gum pain that characterizes ANUG distinguishes it from the more common chronic periodontitis which is rarely painful. If ANUG is improperly treated or neglected, it may become chronic and/or recurrent. The causative organisms are mostly anaerobic bacteria, particularly Fusobacteriota and spirochete species. Predisposing factors include poor oral hygiene, smoking, poor nutrition, psychological stress, and a weakened immune system. When the attachments of the teeth to the bone are involved, the term NUP is used. Treatment of ANUG is by removal of dead gum tissue and antibiotics (usually metronidazole) in the acute phase, and improving oral hygiene to prevent recurrence. Although the condition has a rapid onset and is debilitating, it usually resolves quickly and does no serious harm. The informal name trench mouth arose during World War I as many soldiers developed the disease, probably because of the poor conditions and extreme psychological stress.
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  • 24 Oct 2022
Topic Review
Karakandu
Karakandu or Karakanda was a powerful legendary Jain emperor of Kalinga (Odisha and North Andhra), who is said to have lived between 9th Century B.C to 6th Century B.C. He is a celebrated hero of many Jain and Buddhist religious scriptures. Ancient Buddhist text of Kumbhakara Jataka mentions him to be the Pratyekabuddha or the enlightened living being. Karakandu was a great devotee of the 23rd Jain tirthankar Parshvanatha who had preached Jainism in Kalinga around 850 B.C. Karakandu was also refereed as the "Bull among Kings" by Mahavira, the 24th Jain tithankar. Successive Jain writers over the years have placed him in the group of four Chakravati kings of the Indian subcontinent during his time who also were considered as prateykabudhhas namely, Nagnajit of Gandhara, Nemi or Nimi of Videha, Durmukha or Dwimukha of Panchala and Karakandu of Kalinga. After achieving victory over many kings and ruling for a long term, Karakandu became a Jain Sramana and left the throne and kingdom in charge of his son. During his time Kalinga was a Jain stronghold often described as the Kalinga Jinasana which may be compared to the later era Buddhist Janapadas. It was Jain monk Kanakmara's work in Apabrhamasa or Prakrit language known as Karakandu Cariu which gives detailed events about his life.
  • 1.1K
  • 24 Oct 2022
Topic Review
N747PA
N747PA, was the registration of a Boeing 747-121. Also known as Clipper Juan T. Trippe, it was the second 747 ever built. It was purchased by Pan Am in 1970. Following an accident in 1971, the aircraft continued service with Pan Am until its collapse in 1991. It served as a freighter until 1997 when it was used as a source of spare parts. In 2000 it was purchased by a South Korean couple and converted into a restaurant. After laying abandoned for years following the restaurant's failure in 2005, the aircraft was finally scrapped in 2010.
  • 2.1K
  • 24 Oct 2022
Topic Review
Scalable Link Interface
Scalable Link Interface (SLI) is a brand name for a multi-GPU technology developed by Nvidia for linking two or more video cards together to produce a single output. SLI is a parallel processing algorithm for computer graphics, meant to increase the available processing power. The initialism SLI was first used by 3dfx for Scan-Line Interleave, which was introduced to the consumer market in 1998 and used in the Voodoo2 line of video cards. After buying out 3dfx, Nvidia acquired the technology but did not use it. Nvidia later reintroduced the SLI name in 2004 and intended for it to be used in modern computer systems based on the PCI Express (PCIe) bus; however, the technology behind the name SLI has changed dramatically.
  • 1.2K
  • 24 Oct 2022
Topic Review
Satellite Geodesy
Satellite geodesy is geodesy by means of artificial satellites — the measurement of the form and dimensions of Earth, the location of objects on its surface and the figure of the Earth's gravity field by means of artificial satellite techniques. It belongs to the broader field of space geodesy. Traditional astronomical geodesy is not commonly considered a part of satellite geodesy, although there is considerable overlap between the techniques. The main goals of satellite geodesy are: Satellite geodetic data and methods can be applied to diverse fields such as navigation, hydrography, oceanography and geophysics. Satellite geodesy relies heavily on orbital mechanics.
  • 3.2K
  • 24 Oct 2022
Topic Review
Berylliosis
Berylliosis, or chronic beryllium disease (CBD), is a chronic allergic-type lung response and chronic lung disease caused by exposure to beryllium and its compounds, a form of beryllium poisoning. It is distinct from acute beryllium poisoning, which became rare following occupational exposure limits established around 1950. Berylliosis is an occupational lung disease. While there is no cure, symptoms can be treated.
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  • 24 Oct 2022
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