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Topic Review
Cryptography
Cryptography, or cryptology (from Ancient Greek: "hidden, secret"; and γράφειν graphein, "to write", or -λογία -logia, "study", respectively), is the practice and study of techniques for secure communication in the presence of adversarial behavior. More generally, cryptography is about constructing and analyzing protocols that prevent third parties or the public from reading private messages. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, information security, electrical engineering, digital signal processing, physics, and others. Core concepts related to information security (data confidentiality, data integrity, authentication, and non-repudiation) are also central to cryptography. Practical applications of cryptography include electronic commerce, chip-based payment cards, digital currencies, computer passwords, and military communications. Cryptography prior to the modern age was effectively synonymous with encryption, converting readable information (plaintext) to unintelligible nonsense text (ciphertext), which can only be read by reversing the process (decryption). The sender of an encrypted (coded) message shares the decryption (decoding) technique only with intended recipients to preclude access from adversaries. The cryptography literature often uses the names "Alice" (or "A") for the sender, "Bob" (or "B") for the intended recipient, and "Eve" (or "E") for the eavesdropping adversary. Since the development of rotor cipher machines in World War I and the advent of computers in World War II, cryptography methods have become increasingly complex and their applications more varied. Modern cryptography is heavily based on mathematical theory and computer science practice; cryptographic algorithms are designed around computational hardness assumptions, making such algorithms hard to break in actual practice by any adversary. While it is theoretically possible to break into a well-designed system, it is infeasible in actual practice to do so. Such schemes, if well designed, are therefore termed "computationally secure"; theoretical advances (e.g., improvements in integer factorization algorithms) and faster computing technology require these designs to be continually reevaluated, and if necessary, adapted. Information-theoretically secure schemes that cannot be broken even with unlimited computing power, such as the one-time pad, are much more difficult to use in practice than the best theoretically breakable, but computationally secure, schemes. The growth of cryptographic technology has raised a number of legal issues in the Information Age. Cryptography's potential for use as a tool for espionage and sedition has led many governments to classify it as a weapon and to limit or even prohibit its use and export. In some jurisdictions where the use of cryptography is legal, laws permit investigators to compel the disclosure of encryption keys for documents relevant to an investigation. Cryptography also plays a major role in digital rights management and copyright infringement disputes in regard to digital media.
  • 3.0K
  • 28 Nov 2022
Topic Review
Location-Based Social Networks
There are several definitions for “geosocial network” or “location-based social network”: the first formal definition was given by Quercia et al. in 2010, who defined it as “a type of social networking in which geographic services and capabilities such as geocoding and geotagging are used to enable additional social dynamics”. One year later, Zheng refined this definition by stating that “a location-based social network (LBSN) does not only mean adding a location to an existing social network so that people in the social structure can share location embedded information but also consists of the new social structure made up of individuals connected by the interdependency derived from their locations in the physical world as well as their location-tagged media content, such as photos, video, and texts”. In 2013, Roick and Heuser defined LBSNs simply as “social network sites that include location information into shared contents”. Finally, one most recent definition is given by Armenatzoglou and Papadias and is the following: “geosocial network (GeoSN) is an online social network augmented by geographical information”.
  • 3.0K
  • 17 Jan 2022
Topic Review
Delphi (IDE)
Delphi is an integrated development environment (IDE) for rapid application development of desktop, mobile, web, and console software, developed by Embarcadero Technologies. It is also an event-driven language. Delphi's compilers use their own Object Pascal dialect of Pascal and generate native code for Microsoft Windows, macOS (IA-32 only), iOS, Android and Linux (x64 only). Since 2016, there have been new releases of Delphi every six months, with new platforms being added approximately every second release. Delphi includes a code editor, a visual designer, an integrated debugger, a source code control component, and support for third-party plugins. The code editor features Code Insight (code completion), Error Insight (real-time error-checking), and refactoring. The visual forms designer has traditionally used Visual Component Library (VCL) for native Windows development, but the FireMonkey (FMX) platform was later added for cross-platform development. Database support in Delphi is very strong. A Delphi project of a million lines to compile in a few seconds – one benchmark gave 170,000 lines per second. Delphi was originally developed by Borland as a rapid application development tool for Windows as the successor of Turbo Pascal. Delphi added full object-oriented programming to the existing language, and since then the language has grown to support generics and anonymous methods, and native Component Object Model (COM) support. In 2006, Borland’s developer tools section was transferred from Borland to a wholly owned subsidiary known as CodeGear, which was sold to Embarcadero Technologies in 2008. In 2015, Embarcadero was purchased by Idera Software, but the Embarcadero mark was retained for the developer tools division. Delphi and its C++ counterpart, C++Builder, are interoperable. They share many core components, notably the IDE, VCL, and much of the runtime library. In addition, they can be used jointly in a project. For example, C++Builder 6 and later can consume Delphi source code and C++ in one project, while packages compiled with C++Builder can be used from within Delphi. In 2007, the products were released jointly as RAD Studio, a shared host for Delphi and C++Builder, which can be purchased with either or both.
  • 3.0K
  • 02 Nov 2022
Topic Review
Isosceles Triangle
In geometry, an isosceles triangle (/aɪˈsɒsəliːz/) is a triangle that has at least two sides of equal length. Sometimes it is specified as having exactly two sides of equal length, and sometimes as having at least two sides of equal length, the latter version thus including the equilateral triangle as a special case. Examples of isosceles triangles include the isosceles right triangle, the golden triangle, and the faces of bipyramids and certain Catalan solids. The mathematical study of isosceles triangles dates back to ancient Egyptian mathematics and Babylonian mathematics. Isosceles triangles have been used as decoration from even earlier times, and appear frequently in architecture and design, for instance in the pediments and gables of buildings. The two equal sides are called the legs and the third side is called the base of the triangle. The other dimensions of the triangle, such as its height, area, and perimeter, can be calculated by simple formulas from the lengths of the legs and base. Every isosceles triangle has an axis of symmetry along the perpendicular bisector of its base. The two angles opposite the legs are equal and are always acute, so the classification of the triangle as acute, right, or obtuse depends only on the angle between its two legs.
  • 3.0K
  • 07 Nov 2022
Topic Review
Heteroscedasticity
In statistics, a vector of random variables is heteroscedastic (or heteroskedastic; from Ancient Greek hetero "different" and skedasis "dispersion") if the variability of the random disturbance is different across elements of the vector. Here, variability could be quantified by the variance or any other measure of statistical dispersion. Thus heteroscedasticity is the absence of homoscedasticity. A typical example is the set of observations of income in different cities. The existence of heteroscedasticity is a major concern in regression analysis and the analysis of variance, as it invalidates statistical tests of significance that assume that the modelling errors all have the same variance. While the ordinary least squares estimator is still unbiased in the presence of heteroscedasticity, it is inefficient and generalized least squares should be used instead. Because heteroscedasticity concerns expectations of the second moment of the errors, its presence is referred to as misspecification of the second order. The econometrician Robert Engle was awarded the 2003 Nobel Memorial Prize for Economics for his studies on regression analysis in the presence of heteroscedasticity, which led to his formulation of the autoregressive conditional heteroscedasticity (ARCH) modeling technique.
  • 2.9K
  • 14 Oct 2022
Topic Review
Integration of Blockchain Technology with Cloud Computing
Blockchain technology’s desirable characteristics are decentralization, integrity, immutability, verification, fault tolerance, anonymity, audibility, and transparency. There are many benefits of blockchain technology concerning cloud computing, including those associated with business data handling, privacy, and encryption. 
  • 2.9K
  • 29 Nov 2022
Topic Review
Forensic Photography
Forensic photography may refer to the visual documentation of different aspects that can be found at a crime scene. It may include the documentation of the crime scene, or physical evidence that is either found at a crime scene or already processed in a laboratory. Forensic photography differs from other variations of photography because crime scene photographers usually have a very specific purpose for capturing each image. As a result, the quality of forensic documentation may determine the result of an investigation, in that with the absence of good documentation, investigators may find it impossible to conclude what did or did not happen. Crime scenes can be major sources of physical evidence that is used to associate or link suspects to scenes, victims to scenes, and suspects to victims. Locard's exchange principle is a major concept that helps determine these relationships of evidence. It is the basic tenet of why crime scenes should be investigated. Anything found at a crime scene can be used as physical evidence as long as it is relevant to the case, which is why the documentation of a crime scene and physical evidence in its true form is key for the interpretation of the investigation. Knowing that crucial information for an investigation can be found at a crime scene, forensic photography is a form of documentation that is essential for retaining the quality of discovered physical evidence. Such physical evidence to be documented include those found at the crime scene, in the laboratory, or for the identification of suspects. All forensic photography must consider three elements at a crime scene: the subject, the scale, and a reference object. Also, the overall forensic photographs must be shown a neutral and accurate representation.
  • 2.9K
  • 21 Nov 2022
Topic Review
Autonomous Spaceport Drone Ship
An autonomous spaceport drone ship (ASDS) is an ocean-going vessel derived from a deck barge, outfitted with station-keeping engines and a large landing platform. Construction of such ships was commissioned by aerospace company SpaceX to allow for recovery of rocket first-stages at sea for high-velocity missions which do not carry enough fuel to return to the launch site after lofting spacecraft onto an orbital trajectory. SpaceX has two operational drone ships and has a third under construction as of early 2018. Just Read the Instructions operates in the Pacific for launches from Vandenberg Air Force Base ; Of Course I Still Love You operates in the Atlantic for launches from Cape Canaveral. A Shortfall of Gravitas is under construction. (As of August 2018), 23 Falcon 9 flights have attempted to land on a drone ship, with 17 of them succeeding. The ASDS ships are a key component of the SpaceX reusable launch system development program which aims to significantly lower the price of space launch services through "full and rapid reusability." Any flights going to geostationary orbit or exceeding escape velocity will require landing at sea, encompassing about half of SpaceX missions.
  • 2.9K
  • 27 Oct 2022
Topic Review
Artificial Intelligence-Based Decision Support Systems in Project Sustainability
Decision support systems (DSS) is a computer-based aid, which is designed to assist project managers in decision making when the tasks at hand are of a complex nature. Artificial intelligence (AI) is “the theory and development of computer systems able to perform tasks normally requiring human intelligence, such as visual perception, speech recognition, decision-making, and translation between languages”. The use of artificial intelligence (AI)-based decision support systems (DSS) has been gaining in popularity. AI technologies are becoming powerful tools throughout the world for improving project management; however, the advancement of construction management is still in its infancy and is adapting to the use of AI at a much slower pace than other sectors
  • 2.9K
  • 15 Aug 2022
Topic Review
Driving Mechanisms/Motion of Screw Drive
In recent years, interest in in-pipe robot research has been steadily increasing. This phenomenon reflects the necessity and urgency of pipe inspection and rehabilitation as several pipe networks have become outdated around the globe. In-pipe robots can be divided into several groups in accordance with their locomotion principles, each with its own advantages and best suited application scope. Research on the screw drive in-pipe robot (SDIR) has had a rising trend due to the robot’s simple driving mechanism design and numerous advantages. 
  • 2.9K
  • 09 Nov 2020
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