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Ultra Density Optical
Ultra Density Optical (UDO) is an optical disc format designed for high-density storage of high-definition video and data. The format was introduced by Sony to replace the Magneto-optical disc format. Overview An Ultra Density Optical disc, or UDO, is a 133.35 mm (5.25") ISO cartridge optical disc which can store up to 30 GB (gigabytes) of data. The second generation UDO2 media format was introduced in April 2007 and has a capacity of up to 80 GB. It utilizes a design based on the Magneto-optical disc, but uses Phase Change technology combined with a blue violet laser. A UDO/UDO2 disc that can store substantially more data than a magneto-optical (MO) disc. This is due to the shorter wavelength (405 nm) of the blue-violet laser employed. MOs use a 650 nm-wavelength red laser. Because its beam width is shorter when burning to a disc than a red-laser for MO, a blue-violet laser allows more information to be stored digitally in the same amount of space. Current generations of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Disc
An optical disc is a flat, usuallyNon-circular optical discs exist for fashion purposes; see shaped compact disc. disc-shaped object that stores information in the form of physical variations on its surface that can be read with the aid of a beam of light. Optical discs can be reflective, where the light source and detector are on the same side of the disc, or transmissive, where light shines through the disc to be detected on the other side. Optical discs can store analog information (e.g. LaserDisc), digital information (e.g. DVD), or store on the same disc (e.g. CD Video). Their main uses are the distribution of media and data, and long-term archival. Design and technology The encoding material sits atop a thicker substrate (usually polycarbonate) that makes up the bulk of the disc and forms a dust defocusing layer. The encoding pattern follows a continuous, spiral path covering the entire disc surface and extending from the innermost track to the outermost track ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autoloader (data Storage Device)
An autoloader or auto-loader is a mechanical aid or replacement for the personnel that load ammunition into crew-served weapons without being an integrated part of the gun itself. The term is generally only applied to larger weapons, such as naval weapons, tanks, and artillery; that would otherwise have a dedicated person or persons loading them. An autoloader extracts a shell and propellant charge from the ammunition storage rack/compartment and loads it into a magazine or belt, if the gun has one, or directly into the chamber of the gun if it does not. It often replaces a human loader. Automation can streamline and speed the loading process, resulting in a more effective design. The potential benefits of an autoloader in a vehicle is a higher firerate and a smaller turret and crew amount. The autoloader takes up internal space and could need room in the turret ring like the Des Moines-class cruiser or require an extended turret bustle like the Type 90 tank, and is also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audiovisual Introductions In 2000
Audiovisual (AV) is electronic media possessing both a sound and a visual component, such as slide-tape presentations, films, television programs, corporate conferencing, church services, and live theater productions. Audiovisual service providers frequently offer web streaming, video conferencing, and live broadcast services. The professional audio visual industry has companies that provide hardware, software and services. These organizations are commonly referred to as ''systems integrators'' and perform both the installation and integration of different types of AV equipment from multiple manufacturers into spaces to create the AV experience for the user or audience. Computer-based audiovisual equipment is often used in education, with many schools and universities installing projection equipment and using interactive whiteboard technology. Components Aside from equipment installation, two significant elements of audiovisual are wiring and system control. If either of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Migration
Data migration is the process of selecting, preparing, extracting, and transforming data and permanently transferring it from one computer storage system to another. Additionally, the validation of migrated data for completeness and the decommissioning of legacy data storage are considered part of the entire data migration process. Data migration is a key consideration for any system implementation, upgrade, or consolidation, and it is typically performed in such a way as to be as automated as possible, freeing up human resources from tedious tasks. Data migration occurs for a variety of reasons, including server or storage equipment replacements, maintenance or upgrades, application migration, website consolidation, disaster recovery, and data center relocation. The standard phases , "nearly 40 percent of data migration projects were over time, over budget, or failed entirely." Thus, proper planning is critical for an effective data migration. While the specifics of a data mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Retention
Data retention defines the policies of persistent data and records management for meeting legal and business data archival requirements. Although sometimes interchangeable, it is not to be confused with the Data Protection Act 1998. The different data retention policies weigh legal and privacy concerns economics and need-to-know concerns to determine the retention time, archival rules, data formats, and the permissible means of storage, access, and encryption. Implementation In the field of telecommunications, "data retention" generally refers to the storage of call detail records (CDRs) of telephony and internet traffic and transaction data ( IPDRs) by governments and commercial organisations. In the case of government data retention, the data that is stored is usually of telephone calls made and received, emails sent and received, and websites visited. Location data is also collected. The primary objective in government data retention is traffic analysis and mass surve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Integrity
Data integrity is the maintenance of, and the assurance of, data accuracy and consistency over its entire Information Lifecycle Management, life-cycle. It is a critical aspect to the design, implementation, and usage of any system that stores, processes, or retrieves data. The term is broad in scope and may have widely different meanings depending on the specific context even under the same general umbrella of computing. It is at times used as a proxy term for data quality, while data validation is a prerequisite for data integrity. Definition Data integrity is the opposite of data corruption. The overall intent of any data integrity technique is the same: ensure data is recorded exactly as intended (such as a database correctly rejecting mutually exclusive possibilities). Moreover, upon later Data retrieval, retrieval, ensure the data is the same as when it was originally recorded. In short, data integrity aims to prevent unintentional changes to information. Data integrity is no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Authenticity
In information security, message authentication or data origin authentication is a property that a message has not been modified while in transit (data integrity) and that the receiving party can verify the source of the message. Description Message authentication or data origin authentication is an information security property that indicates that a message has not been modified while in transit (data integrity) and that the receiving party can verify the source of the message. Message authentication does not necessarily include the property of non-repudiation. Techniques Message authentication is typically achieved by using message authentication codes (MACs), authenticated encryption (AE), or digital signatures. The message authentication code, also known as digital authenticator, is used as an integrity check based on a secret key shared by two parties to authenticate information transmitted between them. It is based on using a cryptographic hash or symmetric encrypti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Professional Disc
Professional Disc (PFD) is a digital recording optical disc format introduced by Sony in 2003 primarily for XDCAM, its tapeless camcorder system. It was one of the first optical formats to utilize a blue laser, which allowed for a higher density of data to be stored on optical media compared to infrared laser technology used in the CD and red laser technology used in the DVD format. Technology PFD uses a 405 nm wavelength and a numerical aperture (NA) of 0.85 for the laser, allowing 23 GB of data to be stored on one 12 cm disc – the equivalent to nearly five single-layer DVDs, and a 1x speed data transfer rate of 88 Mbit/s for reading and 72 Mbit/s for writing. After the 23 GB disc was released, a dual-layer 50 GB was developed and released. This format is sometimes confused with the Blu-ray Disc format, another optical disc format using blue-violet lasers and supported by Sony. Even the PFD's caddy and Blu-ray's original caddy (later dropped) l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lens (optics)
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), usually arranged along a common axis. Lenses are made from materials such as glass or plastic and are ground, polished, or molded to the required shape. A lens can focus light to form an image, unlike a prism, which refracts light without focusing. Devices that similarly focus or disperse waves and radiation other than visible light are also called "lenses", such as microwave lenses, electron lenses, acoustic lenses, or explosive lenses. Lenses are used in various imaging devices such as telescopes, binoculars, and cameras. They are also used as visual aids in glasses to correct defects of vision such as myopia and hypermetropia. History The word ''lens'' comes from , the Latin name of the lentil (a seed of a lentil pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Numerical Aperture
In optics, the numerical aperture (NA) of an optical system is a dimensionless number that characterizes the range of angles over which the system can accept or emit light. By incorporating index of refraction in its definition, has the property that it is constant for a beam as it goes from one material to another, provided there is no refractive power at the interface (e.g., a flat interface). The exact definition of the term varies slightly between different areas of optics. Numerical aperture is commonly used in microscopy to describe the acceptance cone of an Objective (optics), objective (and hence its light-gathering ability and Optical resolution, resolution), and in fiber optics, in which it describes the range of angles within which light that is incident on the fiber will be transmitted along it. General optics In most areas of optics, and especially in microscopy, the numerical aperture of an optical system such as an objective lens is defined by \mathrm = n \sin \t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diffraction
Diffraction is the deviation of waves from straight-line propagation without any change in their energy due to an obstacle or through an aperture. The diffracting object or aperture effectively becomes a secondary source of the Wave propagation, propagating wave. Diffraction is the same physical effect as Wave interference, interference, but interference is typically applied to superposition of a few waves and the term diffraction is used when many waves are superposed. Italian scientist Francesco Maria Grimaldi coined the word ''diffraction'' and was the first to record accurate observations of the phenomenon in 1660 in science, 1660. In classical physics, the diffraction phenomenon is described by the Huygens–Fresnel principle that treats each point in a propagating wavefront as a collection of individual spherical wavelets. The characteristic pattern is most pronounced when a wave from a Coherence (physics), coherent source (such as a laser) encounters a slit/aperture tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spatial Resolution
In physics and geosciences, the term spatial resolution refers to distance between independent measurements, or the physical dimension that represents a pixel of the image. While in some instruments, like cameras and telescopes, spatial resolution is directly connected to angular resolution, other instruments, like synthetic aperture radar or a network of weather stations, produce data whose spatial sampling layout is more related to the Earth's surface, such as in remote sensing and satellite imagery. See also * Image resolution Image resolution is the level of detail of an image. The term applies to digital images, film images, and other types of images. "Higher resolution" means more image detail. Image resolution can be measured in various ways. Resolution quantifies ... * Ground sample distance * Level of detail * Resel References Accuracy and precision {{physics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
