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Topic Review

Lexicographical Order

In mathematics, the lexicographic or lexicographical order (also known as lexical order, dictionary order, alphabetical order or lexicographic(al) product) is a generalization of the way words are alphabetically ordered based on the alphabetical order of their component letters. This generalization consists primarily in defining a total order on the sequences (often called strings in computer science) of elements of a finite totally ordered set, often called an alphabet. There are several variants and generalizations of the lexicographical ordering. One variant widely used in combinatorics orders subsets of a given finite set by assigning a total order to the finite set, and converting subsets into increasing sequences, to which the lexicographical order is applied. Another generalization defines an order on a Cartesian product of partially ordered sets; this order is a total order if and only if the factors of the Cartesian product are totally ordered.

2.0K
16 Nov 2022

Topic Review

The Nike+iPod Sports Kit is an activity tracker device, developed by Nike, Inc., which measures and records the distance and pace of a walk or run. The Nike+iPod consists of a small transmitter device attached to or embedded in a shoe, which communicates with either the Nike+ Sportband, a receiver plugged into an iPod Nano. It can also work directly with a 2nd Generation iPod Touch (or higher), iPhone 3GS, iPhone 4, iPhone 4S, iPhone 5, iPhone 5C, iPhone 5S, or a Nike+ Sportwatch. If using the iPod or the iPhone, iTunes software can be used to view the walk or run history. The Nike+iPod was announced on May 23, 2006. On September 7, 2010, Nike released the Nike+ Running App (originally called Nike+ GPS) on the App Store, which used a tracking engine powered by MotionX that does not require the separate shoe sensor or pedometer. This application works using the accelerometer and GPS of the iPhone and the accelerometer of the iPod Touch, which does not have a GPS chip. Nike+Running is compatible with the iPhone 6 and iPhone 6 Plus down to iPhone 3GS and iPod touch. On June 21, 2012, Nike released Nike+ Running App for Android. The current app is compatible with all Android phones running 4.0.3 and up.

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16 Nov 2022

Topic Review

As the next version of Windows NT after Windows 2000, as well as the successor to Windows Me, Windows XP introduced many new features but it also removed some others.

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21 Nov 2022

Topic Review

Central Line (Geometry)

In geometry, central lines are certain special straight lines that lie in the plane of a triangle. The special property that distinguishes a straight line as a central line is manifested via the equation of the line in trilinear coordinates. This special property is related to the concept of triangle center also. The concept of a central line was introduced by Clark Kimberling in a paper published in 1994.

2.0K
27 Sep 2022

Topic Review

Google App Engine

Google App Engine (often referred to as GAE or simply App Engine) is a cloud computing platform as a service for developing and hosting web applications in Google-managed data centers. Applications are sandboxed and run across multiple servers. App Engine offers automatic scaling for web applications—as the number of requests increases for an application, App Engine automatically allocates more resources for the web application to handle the additional demand. Google App Engine primarily supports Go, PHP, Java, Python, Node.js, .NET, and Ruby applications, although it can also support other languages via "custom runtimes". The service is free up to a certain level of consumed resources and only in standard environment but not in flexible environment. Fees are charged for additional storage, bandwidth, or instance hours required by the application. It was first released as a preview version in April 2008 and came out of preview in September 2011.

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17 Oct 2022

Topic Review

RTP Audio Video Profile

The RTP audio/video profile (RTP/AVP) is a profile for Real-time Transport Protocol (RTP) that specifies the technical parameters of audio and video streams. RTP specifies a general-purpose data format, but doesn't specify how encoded data should utilize the features of RTP (what payload type value to put in the RTP header, what sampling rate and clock rate [the rate at which the RTP timestamp increments] to use, etc.). An RTP profile specifies these details. The RTP audio/video profile specifies a mapping of specific audio and video codecs and their sampling rates to RTP payload types and clock rates, and how to encode each data format as an RTP data payload, as well as specifying how to describe these mappings using Session Description Protocol (SDP).

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21 Oct 2022

Topic Review

Level design, or environment design, is a discipline of game development involving creation of video game levels—locales, stages, or missions. This is commonly done using a level editor, a game development software designed for building levels; however, some games feature built-in level editing tools.

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08 Oct 2022

Topic Review

Blackbird (formerly named FORscene) is an integrated internet video platform, video editing software, covering non-linear editing and publishing for broadcast, web and mobile. Designed by Blackbird plc to allow collaborative editing of video at resolutions of up to 540p and up to 60 frames per second on bandwidths as low as 2MBit/s, it is capable of video logging, reviewing, publishing and hosting through HD and 4K to UHD quality from original sources. The system is implemented as a mobile app for Android and iOS devices, a Java applet and a pure JavaScript web application as part of its user interface. The latter runs on platforms without application installation, codec installation, or machine configuration and has Web 2.0 features. Blackbird won the Royal Television Society's award for Technology in the post-production process in December 2005.

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02 Nov 2022

Topic Review

Gadget (Computer Science)

In computational complexity theory, a gadget is a subset of a problem instance that simulates the behavior of one of the fundamental units of a different computational problem. Gadgets are typically used to construct reductions from one computational problem to another, as part of proofs of NP-completeness or other types of computational hardness. The component design technique is a method for constructing reductions by using gadgets. (Szabó 2009) traces the use of gadgets to a 1954 paper in graph theory by W. T. Tutte, in which Tutte provided gadgets for reducing the problem of finding a subgraph with given degree constraints to a perfect matching problem. However, the "gadget" terminology has a later origin, and does not appear in Tutte's paper.

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18 Oct 2022

Topic Review

Perspective Projection Distortion

This page is about graphical perspective projection, specifically about distortion Perspective projection distortion is the mechanism that permits a draftsman or artist to produce linear perspective. It is accomplished by a geometric protocol that exhibits the inevitable distortion of three-dimensional space when “projected," i.e., drawn, on a two-dimensional surface. The words projected/projection here refer to the use of graphics’ lines in the protocol to simulate light ray traces from a Station Point (a supposed observer´s location) to the edges and corners of an object in space, creating thereby or by their extension, an image at the lines’ points of intersection with a Projection Plane. No type of projection can perfectly map the imagery of three dimensional space onto a projection plane because of the image's (mapped on the retina-sphere) undevelopability. This is a distortion of the drawing in itself called perspective projection distortion, and refers to the difference between the drawing and the way the objects depicted on it would look if it was real, but there is another distortion caused by the difference between the location of the supposed observer situated for the drawing process and the location of the real observer of the drawing. These two distortions exist simultaneously. In the special case — and the only instance — in which perspective imagery appears affected only by the perspective projection distortion, the real observer must view the perspective imagery from precisely the supposed station point of the perspective. Real human vision and perspective projection should (unless it is otherwise desired) look the same. The difference should be imperceptible. The base to rate the quality of the perspective projection is the real vision and the difference between them is the perspective projection distortion. Normal human vision should not be considered to present any distortion unless a disturbing factor is involved. Distortion in human vision appears when there is a visual problem involved. The use of lenses can also cause, modify or avoid these distortions. In photography a lens may magnify distortion.

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21 Oct 2022

Topic Review

IBM Optical Mark and Character Readers

IBM designed, manufactured and sold optical mark and character readers from 1960 until 1984. The IBM 1287 is notable as being the first commercially sold scanner capable of reading handwritten numbers.

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17 Nov 2022

Biography

Arun Sharma is an Indian Australian computer science professor and a noted leader within the Australian Higher education, research, innovation, and High Tech sectors. He is a distinguished emeritus professor at the Queensland University of Technology (QUT) where he was the Deputy Vice-Chancellor for Research and Commercialisation from 2004 to 2019.[1][2] He is the Council Chair of the QIMR Bergh

2.0K
09 Dec 2022

Topic Review

IBM App Connect Enterprise

IBM App Connect Enterprise (abbreviated as IBM ACE, formerly known as IBM Integration Bus or WebSphere Message Broker) is IBM's integration broker from the WebSphere product family that allows business information to flow between disparate applications across multiple hardware and software platforms. Rules can be applied to the data flowing through the message broker to route and transform the information. The product is an Enterprise Service Bus supplying a communication channel between applications and services in a service-oriented architecture. IBM ACE provides capabilities to build solutions needed to support diverse integration requirements through a set of connectors to a range of data sources, including packaged applications, files, mobile devices, messaging systems, and databases. A benefit of using IBM ACE is that the tool enables existing applications for Web Services without costly legacy application rewrites. ACE avoids the point-to-point strain on development resources by connecting any application or service over multiple protocols, including SOAP, HTTP and JMS. Modern secure authentication mechanisms, including the ability to perform actions on behalf of masquerading or delegate users, through MQ, HTTP and SOAP nodes are supported such as LDAP, X-AUTH, O-AUTH, and two-way SSL. A major focus of IBM ACE in its latest release is the capability of the product's runtime to be fully hosted in a cloud. Hosting the runtime in the cloud provides certain advantages and potential cost savings compared to hosting the runtime on premises as it simplifies the maintenance and application of OS-level patches which can sometimes be disruptive to business continuity. Also, cloud hosting of IBM ACE runtime allows easy expansion of capacity by adding more horsepower to the CPU configuration of a cloud environment or by adding additional nodes in an Active-Active configuration. Another advantage of maintaining ACE runtimes in the cloud is the ability to configure access to your ACE functionality separate and apart from your internal network using DataPower or API Connect devices. This allows people or services on the public internet to access your Enterprise Service Bus without passing through your internal network, which can be a more secure configuration than if your ESB was deployed to your internal on premises network. IBM ACE embeds a Common Language Runtime to invoke any .NET logic as part of an integration. It also includes full support for the Visual Studio development environment, including the integrated debugger and code templates. IBM Integration Bus includes a comprehensive set of patterns and samples that demonstrate bi-directional connectivity with both Microsoft Dynamics CRM and MSMQ. Several improvements have been made to this current release, among them the ability to configure runtime parameters using a property file that is part of the deployed artifacts contained in the BAR ('broker archive') file. Previously, the only way to configure runtime parameters was to run an MQSI command on the command line. This new way of configuration is referred to as a policy document and can be created with the new Policy Editor. Policy documents can be stored in a source code control system and a different policy can exist for different environments (DEV, INT, QA, PROD). IBM ACE is compatible with several virtualization platforms right out-of-the-box, Docker being a prime example. With ACE, you can download from the global Docker repository a runtime of IBM ACE and run it locally. Because ACE has its administrative console built right into the runtime, once the Docker image is active on your local, you can do all the configuration and administration commands needed to fully activate any message flow or deploy any BAR file. In fact, you can construct message flows that are microservices and package these microservices into a Docker deployable object directly. Because message flows and BAR files can contain Policy files, this node configuration can be automatic and no or little human intervention is needed to complete the application deployment.

2.0K
11 Oct 2022

Topic Review

2 × 2 Real Matrices

In mathematics, the associative algebra of 2×2 real matrices is denoted by M(2, R). Two matrices p and q in M(2, R) have a sum p + q given by matrix addition. The product matrix p q is formed from the dot product of the rows and columns of its factors through matrix multiplication. For let Then q q* = q* q = (ad − bc) I, where I is the 2×2 identity matrix. The real number ad − bc is called the determinant of q. When ad − bc ≠ 0, q is an invertible matrix, and then The collection of all such invertible matrices constitutes the general linear group GL(2, R). In terms of abstract algebra, M(2, R) with the associated addition and multiplication operations forms a ring, and GL(2, R) is its group of units. M(2, R) is also a four-dimensional vector space, so it is considered an associative algebra. The 2×2 real matrices are in one-one correspondence with the linear mappings of the two-dimensional Cartesian coordinate system into itself by the rule The next section displays M(2,R) is a union of planar cross sections that include a real line. M(2,R) is ring isomorphic to split-quaternions, where there is a similar union but with index sets that are hyperboloids.

2.0K
01 Nov 2022

Topic Review

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.

2.0K
25 Oct 2022

Topic Review

Power systems stability with IBGs

Electrical power system stability is of upmost importance for a secure and reliable supply of electrical energy to residential, commercial and industrial premises. Voltage stability of microgrids, as new components of a power system, is an emerging research area within the concept of power system stability. The main purpose of developing microgrids is to facilitate the integration of renewable energy sources into the power grid. Renewable energy sources are normally connected to the grid via power electronic inverters. As various types of renewable energy sources are increasingly connected to the electrical power grid, power systems of the near future will have more inverter-based generators (IBGs) instead of synchronous generators (SGs). Since IBGs have significant differences in their characteristics compared to SGs , particularly with regard to their inertia and capability to provide reactive power, their impacts on the system dynamics are different compared to SGs. A comprehensive review on voltage stability of power systems with the inclusion of inverter-based generators is presented.

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05 Mar 2021

Topic Review

Turbo (formerly Spoon and Xenocode) is a set of software products and services developed by the Code Systems Corporation for application virtualization, portable application creation, and digital distribution. Code Systems Corporation is an American corporation headquartered in Seattle, Washington (state) , and is best known for its Turbo products that include Browser Sandbox, Turbo Studio, TurboServer, and Turbo. Kenji Obata founded Code Systems Corporation in 2006 and introduced Turbo’s precursor, Xenocode. Xenocode was an early application virtualization engine for the Windows platform. Obata serves as the CEO of the corporation, which had become commonly known as Spoon since a rebranding in 2010. Turbo’s tools package conventional software applications for Microsoft Windows in a portable application format that can be delivered via a single executable or streamed over the web. Files and settings automatically synchronize across devices via Turbo’s patented virtualization technology which allows access to local files and printers from web-based applications.

2.0K
09 Nov 2022

Topic Review

Schwarz Triangle Function

In complex analysis, the Schwarz triangle function or Schwarz s-function is a function that conformally maps the upper half plane to a triangle in the upper half plane having lines or circular arcs for edges. Let πα, πβ, and πγ be the interior angles at the vertices of the triangle. If any of α, β, and γ are greater than zero, then the Schwarz triangle function can be given in terms of hypergeometric functions as: where a = (1−α−β−γ)/2, b = (1−α+β−γ)/2, c = 1−α, a′ = a − c + 1 = (1+α−β−γ)/2, b′ = b − c + 1 = (1+α+β−γ)/2, and c′ = 2 − c = 1 + α. This mapping has singular points at z = 0, 1, and ∞, corresponding to the vertices of the triangle with angles πα, πγ, and πβ respectively. At these singular points, This formula can be derived using the Schwarzian derivative. This function can be used to map the upper half-plane to a spherical triangle on the Riemann sphere if α + β + γ > 1, or a hyperbolic triangle on the Poincaré disk if α + β + γ < 1. When α + β + γ = 1, then the triangle is a Euclidean triangle with straight edges: a = 0, [math]\displaystyle{ _2 F_1 \left(a, b; c; z\right) = 1 }[/math], and the formula reduces to that given by the Schwarz–Christoffel transformation. In the special case of ideal triangles, where all the angles are zero, the triangle function yields the modular lambda function. This function was introduced by H. A. Schwarz as the inverse function of the conformal mapping uniformizing a Schwarz triangle. Applying successive hyperbolic reflections in its sides, such a triangle generates a tessellation of the upper half plane (or the unit disk after composition with the Cayley transform). The conformal mapping of the upper half plane onto the interior of the geodesic triangle generalizes the Schwarz–Christoffel transformation. By the Schwarz reflection principle, the discrete group generated by hyperbolic reflections in the sides of the triangle induces an action on the two dimensional space of solutions. On the orientation-preserving normal subgroup, this two dimensional representation corresponds to the monodromy of the ordinary differential equation and induces a group of Möbius transformations on quotients of solutions. Since the triangle function is the inverse function of such a quotient, it is therefore an automorphic function for this discrete group of Möbius transformations. This is a special case of a general method of Henri Poincaré that associates automorphic forms with ordinary differential equations with regular singular points.

1.9K
13 Oct 2022

Topic Review

AI: When a Robot Writes a Play

AI: When a Robot Writes a Play (in Czech: AI: Když robot píše hru) is an experimental theatre play, where 90% of its script was automatically generated by artificial intelligence (the GPT-2 language model). The play is in Czech language, but an English version of the script also exists.

1.9K
23 Nov 2022

Topic Review

Information Assurance

Information assurance (IA) is the practice of assuring information and managing risks related to the use, processing, storage, and transmission of information. Information assurance includes protection of the integrity, availability, authenticity, non-repudiation and confidentiality of user data. IA encompasses not only digital protections but also physical techniques. These protections apply to data in transit, both physical and electronic forms, as well as data at rest . IA is best thought of as a superset of information security (i.e. umbrella term), and as the business outcome of information risk management.

1.9K
21 Nov 2022

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