Notes, abstracts, papers, exams and problems of Technology

Electrical Protection Devices

Protection devices safeguard electrical installations and connected components from potential overloads. They also protect people from electric shock, preventing current leakage to the ground and the consequent economic damage to the user.

Fuses

A fuse is connected in series with the circuit so that all the current flows through it. It consists of a base with two fixed contacts, a plug-piece cartridge or blade, and fusible material surrounded by a medium that acts as a means of extinction.

• Overload: Occurs when the current value in an electrical installation exceeds the fuse's rating.
• Short circuit: Occurs when a fault in an installation element or an accident causes a sudden surge in current, causing the fuse to blow.

DVD Data Storage

The DVD data zone consists of a highly reflective layer called the land. Projections known as pits rise from this land. These pits represent recorded data. The data track is recorded helically from the inside to the outside of the disc.

Pixelated Images and Freezing

If a DVD player displays pixelated images and freezes with different discs, the first step is to clean the lens.

DVD Photodetector Composition and Function

(Information needed)

DVD Servo Systems

DVD players have five servo systems:

1. Focus Control
2. Track Monitoring
3. Coil Monitoring (Tracking)
4. Sled Servo
5. Disc Speed Control

Symptoms of a Dirty Lens and Cleaning Procedure

A dirty lens can cause various playback issues. Here's how to clean it:

1. Moisten one end of a cotton swab with isopropyl

Cybersecurity Threats: Semantic Attacks and Hoaxes

A semantic attack tricks users into believing they are interacting with a legitimate website, while they are actually interacting with a fake. A hoax is an email containing false information, often inviting the recipient to spread viruses or forward the email to collect email addresses for spam. Hoaxes themselves can be considered a form of semantic attack.

Access Control Measures for Computer Systems

Various access control measures can be implemented on computer systems:

• Human Systems: Security guards.
• Biometrics: Fingerprint, voice, and iris recognition.
• Electronics: Security cameras, sensors, and electronic locks.
• Logic: Magnetic cards and passwords.

Understanding Interrupt Requests (IRQ)

An Interrupt

Simple Machines

Simple machines are basic devices formed by a single element. Their primary function is to multiply human force. Ancient philosophers identified five key simple machines: the lever, the wheel and axle, the inclined plane, the screw, and the wedge.

Types of Machines

• Drive Machines: These machines focus solely on producing motion.
• Operational Machines: These machines perform specific tasks, such as a vacuum cleaner.

Elements of a Machine

• Mechanisms: Moving parts that transmit motion to other machine components.
• Structure: Supports the mechanisms.
• Engine/Motor: Generates motion or force.

Force

Force is anything that can change the motion of a body or cause deformation. It is measured in Newtons (N). Approximately 0.1 N is the force exerted... Continue reading "Simple Machines and Mechanisms" »

Why Must an Ohmmeter be Calibrated When Changing Ranges?

What is Calibration?

An ohmmeter must be calibrated each time you change the measuring range to verify the proper operation of the instrument. When calibration is not performed, the needle may deflect incorrectly on the ohmmeter scale. Calibration involves measuring a known resistance standard and comparing it with the ohmmeter reading. This should be done at several points on the instrument's scale and for various scales.

Connecting an Ammeter to Measure Current Through a Resistor

Series vs. Parallel Connection

In which of the two forms mentioned would you connect an ammeter to measure the intensity of current flowing through resistor R? Justify your answer.

The correct way to connect an ammeter... Continue reading "Ohmmeter Calibration and Circuit Analysis Techniques" »

When you need to make a motion transmission, you usually work directly with axes: We support a fixed, usually cylindrical axis, which serves as another element, such as a wheel or a pulley, to turn around. Tree: It's a bar, usually cylindrical, that transmits circular motion. Coupling: The element that allows joining two trees or two axes. Wheel Bearings: These are two completely smooth rim wheels that are in direct contact with one another for moving forward. Gearboxes: We have a minimum of two formed mechanisms, sprockets, constructed in such a way that matches the outgoing motion and transmits circular motion and power. Types of Gears: Cylindrical straight, helical, and bevel. A series of small items would not be possible without the proper... Continue reading "Understanding Motion Transmission Mechanisms in Machinery" »

Palmer Micrometer: Precision Measurement

A Palmer micrometer is a direct-reading measuring instrument. It provides the length value directly, enabling measurements with a precision of 0.01 mm and, in some models, 0.001 mm.

Micrometer Parts

• Body
• Tube
• Rotating drum
• Friction screw
• Circular graduation
• Linear graduation
• Brake
• Mobile probe
• Fixed and insulating probe handles

Micrometer Management

A micrometer can be used to measure parts on marble, on machines, or as support for serial investigations. The measurement procedure is as follows:

1. Open the tool to a range slightly greater than the dimension to be measured.
2. Position the piece between the probes.
3. Gently rotate the drum until the probes support against the piece. This should be done by acting through the

Heavy Work

This term refers to the part of a building's construction that includes the foundation, structural framework, walls, and roof girders.

Joist

A smaller beam, sometimes supported by principal beams or girders. In the context of poplar wood, this name also refers to the first piece carved with an axe from the tip of the trunk, typically 5 feet long.

Cuarton

This term indicates a piece obtained by sawing a whole tree crosswise. Generally, this name is given to sawn pieces with a thickness and width ranging from 2 to 6 inches.

Crowbar / Prop

This term can refer to:

• Vertical uprights or props used to support the formwork for concrete slabs and beams. Shims are often placed at their base to adjust the height.
• A sturdy lever or bar used for prying

Industrial Processes and Materials

Item 1: Production Cycle and Industry Types

1. The Production Cycle:

Industries can be classified into:

• Extractive Industries
• Processing Industries

2. Extraction of Raw Materials:

According to the type of resource:

• Mineral energetics
• Non-metallic rocks and minerals
• Hydrocarbons
• Plant and animal materials

3. Processing Industries:

• Steel and metal
• Petrochemicals
• Paper and artificial wood industries
• Textiles and leather
• Industrial ceramics, glass, and building materials

4. Automobile Manufacturing Process:

1. Realization of parts by melting and molding.
2. Union of parts by welding, adhesives, or threaded elements.
3. Realization of finishing by coating with paints, enamels, and varnishes.
4. Control, product warehousing, and packaging.

5. Saving

Camera Types for Video and Television

The camera's function is to capture the image. We can find a wide variety of video and television cameras, from cheaper designs to more sophisticated markets. We can find a great variety of models. When choosing a camera, several factors must be considered: price, practical aspects (e.g., weight), operational characteristics, and performance (image quality).

Studio Cameras

Studio cameras, for example, are used on set and are usually connected to a production control room. They create high-quality images. They tend to be large, bulky, heavy, expensive, and difficult to transport. They usually incorporate a prompter.

EFP Cameras

EFP stands for Electronic Field Production. These are lightweight cameras. Normally,... Continue reading "Camera Types and Supports for Video Production" »