Database Design Fundamentals
Schema Architecture
External Level
Each external view displays only the data relevant to a specific end-user, hiding unnecessary information. Examples: (External View 1), (External View 2).
Conceptual Level
This level describes the overall structure of the database, typically using a relational model where data is stored in tables (Conceptual Schema).
Internal Level
The internal level details the physical data storage, including indexes used for data retrieval (Internal Schema).
Data Independence
Logical
Read MoreEngine Installation Requirements According to European Directives
1. Purpose and Scope
This instruction defines engine installation requirements using portable professional tools receptors. All installations must meet the requirements of applicable European Directives as provided in Article 6 of the Low Voltage Electrotechnical Regulations.
2. General Installation Conditions
Engine installations must comply with UNE 20,460 and the specifications of the installation location. Engines must be installed to prevent accidents from contact with moving parts. They should
Read MoreElectrical Distribution Networks in Low Voltage (LV)
Air Network Components
The electrical distribution air networks in LV consist of the following components: conductors, insulators, and supports.
Conductor Features
Conductors in these networks are typically made of copper or aluminum alloys with adequate electrical and mechanical properties.
- Insulated Conductors: These conductors have a coating that provides resistance to the elements. The voltage is 0.6/1kV, and the minimum cross-section is 16mm2 for copper (Cu). They are used in LV air networks, perched
Steel Structures and Partitions in Building Construction
Steel Structures
Types
- Forged Unidirectional
- Bi-Forged
Variations
- With Board
- With Top and Bottom Board
- With Landfill or Curdled
Forged Steel Features
Made of rolled steel joists (IPE or IPN), offering high resistance with limited deflection.
Entrevigado Solutions
- Rasilla Vaults
- Ceramic or Cement Mortar Blocks
- Wooden Board
Another option is forged steel sheet combined with other methods.
Partitions
Introduction
Partitions subdivide areas for privacy, thermal/acoustic insulation, and housing utilities.
They are categorized
Read MoreFundamentals of Electric Circuits: A Comprehensive Guide
Fundamentals of Electric Circuits
Introduction
When an electric current flows through a conductor, it produces a displacement of electrically charged particles. This movement of charges is what we call electric current. For an electric current to exist, there must be an electric conductor (e.g., ohmic conductors) and an electric field strong enough to generate a force that causes the charges to move. If the electric field is constant, the current is called direct current (DC). If the electric field
Read MoreA Guide to Plastics: Types, Properties, and Applications
Plastics: An Overview
Plastics are substances with diverse structures and properties. They typically lack a fixed boiling point and exhibit elasticity and flexibility, allowing them to be molded into various shapes. In a narrower sense, plastics refer to synthetic materials obtained through polymerization, involving the propagation of carbon atoms in long molecular chains derived from petroleum and other natural substances.
Properties of Plastics
Most plastics share these characteristics:
- Easy to work