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

Material Science Timeline

• 1769: Discovery of the steam engine (Watt)
• 1831: Discovery of the dynamo (Faraday)
• 1913: Popularization of stainless steel
• 1950: Discovery of silicones and first use in aircraft
• 1960: Perfection of silicon crystals (almost perfect purity)
• 1962: Discovery of the nickel and titanium alloy
• 1971: Presentation of soft contact lenses (Bausch & Lomb)
• 1983: First mobile phone
• 1991: First Web page

Second Industrial Revolution Key Points

• New production systems improve accelerated production.
• Amendment to the way we produce at all levels.
• Minimization of production costs.

Plastics: An Overview

Plastics are characterized by their plasticity, a property that allows them to be easily molded into the most convenient shapes. Their history began... Continue reading "Material Science Timeline and Innovations" »

Network Link Utilization Analysis

Suppose you want to convey 100,000,000 bits via a dedicated link at a speed of 10 Megabits/sec. The distance between the transmitter and receiver is 20,000 meters, and the signal propagation speed is 200,000 km/sec. Information is sent in blocks of 100,000 bits.

a) Stop-and-Wait ARQ Utilization

Calculate the exact link utilization, given that every time the computer receives a complete block, it takes 5 milliseconds to check for errors and save the block to disk before sending the ACK response. Utilization is defined as the total time taken to transmit useful information divided by the total time for transmission, error control, and flow set for that link. The number of bits in the ACK is negligible. Assume Stop-... Continue reading "Calculating Network Link Utilization and Efficiency" »

Mechanisms

Mechanisms are devices that transmit motion to perform a job. They are used to transmit motion in two primary ways:

Linear Motion Transmission

1. Fixed Pulleys

   A fixed pulley is a wheel with a grooved edge that rotates around a central axis. A rope or belt passes through the groove. The force applied at one end of the rope equals the resistance at the other (F = R). The advantage of a fixed pulley is the change in the direction of motion.

2. Movable Pulleys

   In a movable pulley, one end of the rope is fixed, and the resistance hangs from the pulley's axle. The force required is half the resistance (F = R/2).

3. Pulley Systems (Hoists)

   A hoist combines fixed and movable pulleys. The force required is calculated as F = R/(2n), where 'n' is the number

Hydraulic Flow Control Valves for Speed Regulation

Flow control valves are essential components used to regulate the speed of hydraulic actuators. There are three primary methods to implement these valves:

• Meter-In (Entry Regulation): The valve is placed between the pump and the actuator, controlling the fluid entering the system. Excess flow is diverted to the tank via the relief valve. This precise method is ideal for applications where the load consistently opposes actuator movement.
• Meter-Out (Output Regulation): This system is used when the load tends to run away from the actuator, moving in the same direction. The flow controller is installed to restrict the outlet flow from the actuator.
• Bleed-Off (Regulation by Subtraction): The valve is

Filesystem Area Roles

NTFS Filesystem Areas

This section lists and discusses the role of areas of the NTFS file system:

1. Partition Boot Sector: Occupies several sectors. It contains the provision for the volume and file system structure, the location of the MFT and MFT2, and the boot code.
2. MFT (Master File Table): Contains information on files, directories, and available space.
3. MTT (Master File Table Mirror): A list of all the contents of the NTFS volume, organized as a set of rows in a structured relational database.
4. Archiving System: Contains MFT2, which is a mirror copy of the first three rows of the MFT to ensure access to the MFT in case of a sector failure. It also contains the bitmap (represented by the volume) showing which blocks are in use

Different Properties of Materials

The ability of a resistance material to resist forces without distorting excessively or breaking is a crucial property.

• Toughness

  Toughness is the property that some materials have to withstand forces repeatedly without breaking.

• Resilience

  Resilience is the property of a material to recover its original shape after being deformed by an effort.

• Ductility

  Ductility is the property of certain materials to deform permanently into a thin wire without breaking.

• Malleability

  Malleability is the property of certain materials to deform permanently in the form of a thin sheet without breaking.

• Hardness

  Hardness is the property that indicates the opposition a material offers to being penetrated or scratched.

Different Types of Stresses

• Traction

  Traction

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

Protection Systems in Wind Farms

A wind farm is composed of the following: installation of low-voltage generators, BT/MT transformation, a medium-voltage distribution network, a substation, and evacuation lines. Generally, the wind generator produces low voltage (690 V) and connects to a transformer that increases the voltage (20–30 kV) to minimize cable losses while evacuating the power produced to the substation.

Evacuation Line Protection

The most common method to connect the wind farm substation to the utility network is through a dedicated line. Protections assigned to this line include:

• Overvoltage protection
• Directional overcurrent protection
• Earth leakage protection

Substation Transformer Systems

Substation transformers utilize load-voltage... Continue reading "Wind Farm Electrical Protection Systems Explained" »

General Supply Lines

The general supply line links the main protection with the centralization of meters. It utilizes the following installation types:

• Cores inside embedded tubes
• Surface-mounted pipes
• Buried pipes
• Protective channels
• Ducting works designed for this purpose
• Busbar trunking

Note: Almost any driver will include the necessary protection.

Installation of LGA

The route must be as short and rectilinear as possible, utilizing areas of common usage. When installed in tubes, the outside diameter will depend on the cable section, ensuring 100% expansion capacity. Vertical installations should be placed in stairwells, with firewalls installed in garages every three floors.

LGA Cables

Cables consist of 3 phase wires, 1 neutral, and 1 protective conductor... Continue reading "Electrical Installation Standards for General and Individual Supply Lines" »