Computer Science: Key Concepts and Technologies

Posted on Dec 8, 2024 in Other subjects

Quality of Service in Computing

These technologies ensure the transfer of a certain amount of data in a given time. Quality of Service (QoS) is the ability to give good service. It is especially important for certain applications such as streaming video or voice.

Measuring QoS

  • Access
  • Performance
  • Reliability
  • Maintainability

Digital Signatures

A digital signature is the result of implementing extremely safe cryptographic procedures on a digital document. It can be attributed to its author and offers a guarantee of integrity. Technically, it is a unique data set encrypted (transformed into a code or character string). ISO 19005-1, published in October 2005, defines the standard requirements.

Chile has a law, Ley 19.799, the Law on Electronic Signatures and Electronic Documents Certification Services.

Requirements

  • Non-repudiation
  • Authorship
  • Exclusivity
  • Integrity

What is Not a Digital Signature

  • A scanned signature or password
  • A fingerprint
  • A password

What is Records Management?

Records management is a set of administrative activities and techniques aimed at the effective and efficient management and organization of documentation. It involves a classification of documents, which can be used for organization.

Examples include:

  • Technical reports
  • Methodologies
  • Courses
  • Seminars
  • Lectures
  • Instructional manuals
  • Organizational manuals
  • Quality manuals
  • User manuals
  • Proposals
  • Project management presentations

Documents are hard to identify. The obvious reason is the large number of different activities that make up the process. However, we can identify some, such as document creation, collection of documents, and document/content management.

What is Collaborative Work?

One collaborative definition by Wikipedians is “intentional group processes to achieve specific objectives, with software tools designed to support and facilitate the work.”

Cooperative learning (teacher-student) versus collaborative learning (the student as the protagonist) is also a collaborative learning community. It is based on all group members sharing their knowledge. Blogs and wikis are examples of what is called “social software.”

Digital Video

A digital video system is handled through the computer. The information processed is a series of established values understood by the computer, based on zeros and ones, known as bits. Digital technology has contributed strongly to image and sound processing, obtaining a high-quality final product.

Differences in the digital video system image quality are totally independent. Quality is affected only during the scanning process. A compressed digital video can reach 1 megabyte (MB) of space on our disk, compared to uncompressed. At a speed of 25 frames per second (fps), every second of our video would occupy 25 MB/second, meaning we would need a lot of space on our PC for just a few seconds.

Data Mining

Data mining uncovers information that is hidden inside databases but in an intelligently automated way. It is a process of analysis, and data mining uses statistical techniques and mathematical models to find patterns, relationships, and trends.

Use

Predictive

TV Standards

Analog

  • NTSC: Analog color TV developed in the United States around 1940. It is used today in most of America and Japan, among other countries.
  • PAL: Of German origin, PAL is used in most African countries, Asia, and Europe, plus Australia and some Latin American countries.
  • SECAM: Invented by a team led by Henri de France working for Thomson.

Digital

  • ISDB: Digital TV and digital radio that Japan has created to allow radio and television stations to convert to digital.
  • DVB: Satellite TV and data communications via satellite (one-way, called sDVB-IP, and bidirectional, called DVB-RCS). One-way access is not broadband since it is made by combining traditional Internet access via PSTN/ISDN modem plus DVB satellite access.
  • ATSC: Responsible for developing the standards of digital TV in the U.S.

Multimedia Devices

Multimedia is any combination of text, graphic art, sound, animation, and video that comes to us by computer or other electronic means. Interactive multimedia allows the end-user to control certain elements of when they should arise. Hypermedia is when a structure is given through which the user can browse. Then, interactive multimedia becomes hypermedia.

Virtual Reality

Virtual reality is an interactive three-dimensional computer simulation in which the user feels artificially introduced into an environment. This environment is perceived as real based on stimuli to the sense organs.

How to Identify a Simulation

  • Simulation: Simulation of the model or the world experience, not necessarily the same as in real life.
  • Interaction: Taking control of the system created. Having man-machine interfaces.
  • Perception: Some will head to the senses by external elements, the simplest recourse to the full force of the imagination.

Information Security

Information security is understood as anything that might affect its direct operation or the results obtained from it, whether it be a danger or harm. There is no 100% secure system.

For a system to be defined as secure, it should have these four characteristics:

  • Integrity: The information can only be changed by someone who is authorized and in a controlled manner.
  • Confidentiality: Information must be legible only to those authorized.
  • Availability: Must be available when needed.

Depending on the Sources of Threat

  • Physical security: Application of physical barriers and control procedures as preventive measures.
  • Environmental security: Deals with security threats that originate in the environment.
  • Logical security: Implementation of barriers and procedures that safeguard access to data and only allow access to those authorized to do so.

Analog Systems

Analog systems represent information as a continuous data stream. An analog video signal can be recorded on a magnetic tape. The parameters that make up the image are luminance, color, and color difference. Examples include component engraving and composition engraving on analog magnetic tape with interlaced scanning.

Biometrics

Biometrics is a technology based on the recognition of physical and non-transferable characteristics of a person, such as a digital fingerprint or iris. The term biometrics is derived from the Greek words “bios” (life) and “metron” (measure).

Biometric systems require two essential devices: software for capture and storage, and a biometric device (reader). In the case of the fingerprint, the device captures the sample, and the software transforms the minutiae of this sample into a numerical sequence through a mathematical algorithm. This numerical sequence, called a registration template, is stored in a secure database and will serve for the following comparisons whenever the authorized person wants to access the system.

Types

  • Voice recognition
  • Retina
  • Iris
  • Body odor

Capturing and Compressing Audio

Sampling

A waveform can be repeated exactly if the sampling rate is at least twice the frequency of the higher frequency component.

Compression Techniques

  • Equal-loudness contour: Such curves, called isophones, represent the equivalent intensity of a 1kHz tone at the frequency of the intensity treated.
  • Temporal masking: If two sound stimuli of different intensities reach our ears close in time, the more intense tone can mask the weaker one, making it inaudible.
  • Simultaneous masking