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

Network Infrastructure Cables

2 Power Cords (Mains)

These stem from the main network cables and connect to distribution poles, manholes, or building facades. These cables are distributed through adequate piping. They run via interspersed small underground pipes and accessible local street access points called chambers. This set of power cables is called the mains.

3 Distribution Cables

This is the network of branches feeding through lateral paths using lower capacity cables. This set is called the distribution network. These network cables, in turn, divide and end at interconnection points, from which the various subscriber lines originate.

These interconnection points are of two types:

• If they are outdoors and contain a small number of pairs, they

CAV Rotary Injection Pump Fundamentals

In CAV rotary injection pumps, fuel is sent from the transfer pump to the hydraulic head at a pressure regulated by a valve. The metering valve precisely controls the fuel flow, which is governed by the throttle position and the speed regulator assembly. The distributor then raises the fuel pressure from the transfer level to the injection pressure, distributing it to the various nozzles.

Fuel Pressure Transfer Mechanism

Under normal operating conditions, the generated pressure causes the control piston to move to the right, against the action of its spring. This pressure is applied to the valve through a conduit from the transfer pump. When the pressure exceeds the limits set by the adjusting screw, regulation

Electronics and Electricity

Electronics is the science and technology concerned with the study of electrons and their applications in information processing and transmission.

Direct Current (DC)

Direct current (DC) is the flow of electrons in a single, constant direction with consistent voltage and current over time.

Alternating Current (AC)

Alternating current (AC) is a variable current where voltage and current continuously change direction. The most common type of AC used in homes is sinusoidal, meaning it's a periodic electrical signal that repeats at regular intervals.

Transformers

Transformers are used to increase voltage for electricity transmission from power plants and then decrease it for safe household consumption.

Key AC Parameters

• Cycle:

Issue 31: Fuel Injection Power Systems

Food for Fuel Injection

This system supplies power to the combustion engine, replacing the carburetor with a system that injects gasoline directly into the air intake. Advantages of fuel injection systems:

• High performance
• Less fuel consumption
• Fast adaptation
• Reduced pollutants

Injection can be direct or indirect. Direct injection sprays fuel directly into the cylinder, maximizing engine power but requiring higher pressure. Indirect injection sprays gasoline into the intake manifold, with a simpler installation due to lower pressure requirements. Injection can also be continuous or discontinuous.

Mechanical Fuel Injection

Mechanical injection systems are powered by the internal combustion engine or lack an actuator.... Continue reading "Fuel Injection Power Systems: Operation and Types" »

Practical Work No. 7

Topic: Media Guided - Part 2

1. What are the physical media used in telecommunications networks that are mentioned in the text?
2. In reference to copper wires, what are the main variants that exist?
3. What are some of the major disadvantages of bare wire lines?
4. How are UTP cables used? Features of these cables provide each one of their technical characteristics.
5. What are underground multipair cables? What is their utility, and how is their isolation?
6. What are aerial multipair cables and what is their use?
7. What is Coaxial Cable? Depict it graphically.
8. What is referred to as the characteristic impedance of coaxial cables? What are the normal values of the characteristic impedance?
9. What is referred to as attenuation and what is its unit?
10. How

Axles

Axles are intended to support rotating bodies without turning the shaft itself. They are primarily subject to bending loads.

Shafts

Shafts are machine parts that always rotate with the components they support. They transmit power or torque and are subject to both torsion and bending loads. Shafts can be solid or hollow. When a keyway is present, consideration must be given to the shaft diameter due to stress concentration.

Bearings and Supports

Both axles and shafts require support points to bear their weight, facilitate rotation, and prevent displacement. Bearings are the components that provide these supports for shafts and axles.

Bearing Types

Friction Bearings

In friction bearings, the shaft or axle slides within the bearing surface. The... Continue reading "Axles, Shafts, Bearings, and Couplings" »

Mechanisms

Mechanisms are components used to transmit or transform movement. They can transmit linear motion, used for raising objects, or circular motion, used to change speed.

Levers

A lever is a rigid bar that pivots around a fixed point called a fulcrum. One end of the lever applies a force, while the other end moves a resistance.

Types of Levers

Depending on the positions of the fulcrum, force, and resistance, there are three types of levers:

• First-Class Lever

  The fulcrum is located between the force and the resistance. Example: Scissors, which are essentially two first-class levers joined together.

• Second-Class Lever

  The resistance is located between the fulcrum and the force. Example: Wheelbarrows.

• Third-Class Lever

  The force is located between

What are Plastics?

In chemistry and technology, plastics are polymeric organic materials. They are giant molecules formed by carbon atoms linked with hydrogen, oxygen, and to a lesser extent, chlorine, fluorine, nitrogen, or silicon.

Key Properties of Plastics

• Affordable
• Low density
• Waterproof
• Electrical insulators
• Thermal insulators, although not highly resistant to heat
• Resistant to corrosion and weathering
• Resistant to many chemical factors
• Some are recyclable, but not all are biodegradable or easily recycled
• Easy to work with
• Burning some plastics can be highly polluting

Origin of Plastics

Polymers can be classified based on their origin:

• Natural: Occur spontaneously in natural products like cellulose, rubber, and casein.
• Artificial: Industrially obtained

Serrated cutting is a metal removal operation that can divide a piece into two or more parts by removing material between them. The manual process consists of the sawing and the forward movement of the saw. The effectiveness depends on operator skill and the number of sawing strokes per second.

Bow or Frame

This tool supports the saw blade. It consists of a rigid, U-shaped arch. At the ends of the arch are two mutually perpendicular blocks that hold the saw. One of these blocks is controlled by a mobile or wing nut, and a handle serves as a grip.

The arches of saws can be fixed or extensible. The advantage of the extensible type is that it allows the assembly of saw blades of various sizes.

Saw Blade

A saw blade is made of thin, laminated carbon... Continue reading "Serrated Cutting: Techniques and Tools for Metalworking" »

Oil Tank Functions and Design

The oil tank, or reservoir, serves several critical functions in a hydraulic system.

Key Objectives of an Oil Tank

• Store System Fluid: To provide an adequate supply of hydraulic fluid for the system.
• Contaminant Settlement: To allow contaminants in suspension to settle out of the fluid.
• Temperature Regulation: To help maintain the fluid temperature within desired limits by dissipating heat.
• Air Dissipation: To facilitate the release of dissolved air or foam from the fluid.

Baffle Positioning in Oil Tanks

The position of baffles inside the tank is very important. Firstly, they establish separation between the suction line and the return line, preventing aerated or contaminated return oil from being immediately drawn back... Continue reading "Hydraulic System Components: Functions and Principles" »