Notes, summaries, assignments, exams, and problems for Technology

C. Thomsen's Classification of Materials and Historical Ages

C. Thomsen classified materials and historical ages: Stone Age (Paleolithic, Neolithic), Copper Age, Bronze Age, Iron Age. Other materials include wood, bone, ceramics, and leather.

Types of Materials

• Natural (e.g., wood, marble, granite)
• Artificial (created by changing natural materials)
• Synthetic (created in laboratories)

Historical Use of Materials

1. New needs lead to new materials.
2. New materials lead to new scientific discoveries.
3. Major discoveries of natural materials lead to further development of artificial materials.
4. Conflicts and wars arise over the control of natural resources.
5. Artificial materials evolve significantly during wartime.

Ceramics

Clay (mud) bricks, billets, fine porcelain... Continue reading "Material Science and Communication Technologies" »

Mechanical Properties of Metals

Mechanical properties are the properties that express the behavior of metals under forces aimed at altering their shape. A summary of the different types of fundamental forces to which any structure or machine can be subjected are: tension, compression, shear, bending, torsional buckling, or a combination of these.

Resistance

Resistance is the ability of a metal to withstand an external load of the types mentioned above without breaking. As each load type has its corresponding resistance, it is usual to work with a resistance lower than that which would cause breakage in the plastic period of the material, i.e., working within the elastic period.

Hardness

There are two types of hardness: physical, which is the ability... Continue reading "Understanding Mechanical Properties of Metals" »

Main Elements of Home Wiring

At the entrance of the home, the following are typically located:

• Limit Switch (ICPM): A power control switch that prevents power consumption from exceeding a set limit. It also protects against short circuits.
• Differential Switch: Detects current leaks and cuts off the power supply.
• Meter: Located in the meter room or within the house, it informs the utility company of energy consumption.
• Switch: Consists of three cables: two for power supply and a third for grounding to prevent leakage.

Wiring Diagram

The electrical panel with the limiter and differential should be as close as possible and at a height of 1.5 to 1.8 meters. Each circuit is protected by a miniature circuit breaker (PIA) that trips when exceeding a certain... Continue reading "Home Wiring, Plumbing, HVAC, Gas, and Domotics Explained" »

Substations are the centers or facilities that transform the stresses of transportation or distribution tensions between transmission and distribution voltages simultaneously.

Substations in Our Region

Substations (in our region) are responsible for transforming regular or distribution voltages (25kV / 11kV). Transformer stations can be of various types and transform the voltage to low voltage distribution tension. Renewable energy installations, substations, and transformer stations are subject to compliance with regulations and standards, also typical of power companies, usually very demanding for construction and exploitation.

Substations and Receiving Stations

Substations and receiving stations are an important link between the power production,... Continue reading "Substations and Receiving Stations: Function and Classification" »

Questionnaire 5

1. Preventing Grid Contact

To prevent contact between a person and a grid, ensure there is no galvanic connection between them. Natural elements like land or soil can act as galvanic connections.

2. Default Voltage (UD) and Contact Voltage (UC)

• Default Voltage (UD): The voltage between a source or ground masses and a reference point in case of a fault.
• Contact Voltage (UC): The portion of the default voltage, or voltage from the ground, that could be experienced by a person.

3. UNE 20,460 Direct Contact Protection

The UNE 20,460 standard defines the following protection measures against direct contacts:

• Protection by insulation of active parts.
• Protection by barriers or enclosures.
• Protection by obstacles.
• Protection by distance.
• Additional

Data Storage Components

Data storage refers to devices like hard disks, CD-ROMs, floppy disks, and USB drives.

Directory

A directory is an area within a storage unit used for organizing and storing files, as well as other directories or subdirectories.

Subdirectories

A subdirectory is a directory located within another directory, used for further organization of files.

File

A file is the fundamental unit of information storage.

Memory Management Modes

Real Mode Memory Management

Real Mode managed memory using three distinct layers for different functions, typically found in operating systems like Windows 9x or ME.

Protected Mode Memory Management

Protected Mode manages memory as a flat, single address space, common in operating systems such as Windows

Data Modeling Concepts: True or False

• False: ProcessAnalyst typically focuses on business process modeling, not primarily on designing detailed entity-relationship models.
• False: An analyst's concerns extend beyond just designing an information system; they include requirements gathering, process analysis, and more.
• False: Referential integrity is a rule ensuring consistency between related tables, typically involving primary and foreign keys, not governing general data types within attributes.
• True: A domain is a constraint that governs the permissible data types and values for an attribute.
• True: An occurrence (or instance) of an entity is uniquely identified by a primary key.
• True: A Data Architect initiates the process by building a conceptual

Silica (SiO₂)

From natural opal and quartz to beach sand.

Uses:

• Traditional: Glass, porcelain
• Current: Silicon, optical fibers
• Elementary silicon is used to manufacture microchips for electronic devices

Features:

Semiconductor, can be an insulator or a conductor of electricity depending on the conditions.

Fiber Optics

A very fine thread of transparent material (glass, plastic, etc.) through which light pulses are sent that represent data to be transmitted. The light source can be a laser or LED.

They are used in telecommunications, allowing a large amount of information to be sent quickly.

Composites

Composites are formed by two or more chemically different components, which are not mixed at the microscopic level. They maintain individuality, but at the... Continue reading "Silica, Fiber Optics, Composites, Cyborgs, and Nanotechnology" »

Mechanical Power Transmission Systems

Shafts and Couplings

A shaft is a rotating machine element that transmits power or energy. A shaft can also be cylindrical and support rotating parts without transmitting power. Couplings connect two shafts:

• Rigid Coupling: Shafts are aligned and maintain their position during rotation (using flanges and couplings).
• Flexible Coupling: Allows for slight misalignment between shafts during operation.

Gear Trains and Powertrains

A gear train refers to a pair of meshing gears. A powertrain consists of two or more gear pairs that alter the rotational speed of the final shaft.

Joints

Joints transmit motion and forces. These forces can be in opposite, same, or different directions.

Chains and Belts

• Chain: Ideal for dusty