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

Mechanisms: Transmitting Force and Motion

Mechanisms are devices used to transmit and convert forces and motion from a driving force or input to an output.

a) Levers

A lever is a rigid bar that is supported by a fulcrum. When a lever is balanced, it complies with the Law of the Lever:

F × d = R × r

Force (F) and Resistance (R) can be measured in Newton [N] or kilograms [Kg], but both must always be in the same unit.

There are 3 kinds of levers according to the position of the Force (F), Resistance (R or Load), and Fulcrum (P or pivot):

• Class 1: Force – Fulcrum – Resistance
• Class 2: Force – Resistance – Fulcrum
• Class 3: Fulcrum – Force - Resistance

b) Pulleys

We will study three kinds of pulleys:

Fixed Pulley

A fixed pulley is a wheel that has... Continue reading "Mechanical Motion and Force Conversion Systems" »

Fossil Fuel Power Stations

Fossil fuels, such as coal, oil, and natural gas, are used to heat water in a boiler. Steam from the boiler turns a turbine, which is connected to the rotor of a generator. The generator produces electricity, which is transported by a network of high voltage power lines. After that, the steam goes to a condenser where it cools and becomes liquid water again. Finally, the water is pumped back to the boiler.

Combined Cycle Power Stations

Electricity is generated in two systems. In the first, natural gas is burned with compressed air. This produces superheated gases which turn a turbine to generate electricity. In the second, the hot gases from the first system are used to produce steam in a heat recovery boiler. Then the... Continue reading "Types of Power Stations: Fossil Fuels, Combined Cycle, Hydroelectric, Geothermal, and Solar" »

Tracking website user behavior doesn't happen automatically. The web developer needs to install a web analytics program into every page of the website they wish to track.

The Web Analytics Data Collection Process

1. An internet user takes an action that results in a request for a page on a website.

2. When the user navigates to the webpage, the web server receives a request for the information. The server sends this information across the internet to the requesting computer. The web server will then pass on some information about this server request to a data collection center run by the analytics package.

3. The data collection center stores data about this server request and all other server requests until a user requests this data through the analytics

Java Book Class Example

Sorting and Displaying Books by Price

This code defines a simple Book class in Java and demonstrates how to sort and display a list of books by price in ascending order.

Book Class

The Book class has the following attributes:

• bookId: Unique identifier for each book.
• title: Title of the book.
• author: Author of the book.
• publisher: Publisher of the book.
• price: Price of the book.

The class provides a constructor to initialize these attributes, getters to access them, setters to modify them, and a toString() method to represent a Book object as a string.

Program3 Class

The Program3 class contains the main method, which performs the following actions:

1. Creates a list of Book objects.
2. Adds several book instances to the list.
3. Sorts the bookList

ICT Facilities and Distribution Systems

ICT Definition

ICT: Facilities for the distribution of telecommunication signals to a group of users who share a common building or facility. Types include:

• Television and satellite reception
• Basic telephony and ISDN-PSTN
• Telecommunications broadband
• Cable services operated by one or more operators

General Scheme: Feeder Network

General scheme of an ICT facility, "Feeder Network": This consists of the entry of external signals of different types into the telecommunications facility.

Point of Interconnection

"Point of Interconnection": The enclosure in which all the connections in the ICT are consolidated; it is the link between the incoming supply and the internal distribution.

Distribution Network

"Distribution

Effects of Electric Current

The movement of electrons through conductive materials produces effects that have useful applications.

• Heat: The Joule Effect

  The movement of electrons through an electrical wire is slow and disorderly. Electrons often collide, increasing the temperature of the wire itself. The energy that an electrical current produces in the form of heat is called the Joule effect.

• Light Production from Electricity

  There are several ways that electricity can be used to produce light:

  • Incandescent Bulbs

    When an electrical current passes through the metallic filament of a bulb, it produces light. This phenomenon is called incandescence.

  • Fluorescent Tubes

    Inside a fluorescent tube, there is a metallic filament, usually tungsten. There is also

Plastics

Plastics are materials formed by chains of carbon and hydrogen atoms. We call the chains polymers, while the atoms that form them are called monomers.

Thermoplastics

Thermoplastic materials are plastics that are softened by heating and can be formed and melted as many times as we want. This is because their polymers have weak bonds. (Polyethylene (PE), Polystyrene (PS), PVC (polyvinyl chloride))

Thermoset Plastics

The polymers of thermoset plastics criss-cross to form networks. Because of this bond, the plastics can be shaped using heat; however, once they have been formed, they cannot be re-melted to create different forms. (Melamine, Bakelite, Polyester resins)

Elastomers

Elastomers are very flexible materials that recover their shape and... Continue reading "Understanding Plastics: Types and Manufacturing Processes" »

Configuración Esencial de Switches Cisco

Acceso Remoto VTY: Configuración Telnet

Pasos para habilitar el acceso remoto mediante Telnet:

Switch(config)#line vty 0 15
Switch(config-line)#password cisco
Switch(config-line)#login
Switch(config-line)#exit

Configuración de Acceso Remoto Seguro (SSH)

Para configurar SSH, primero se debe asignar una dirección IP a la interfaz VLAN y configurar el nombre de host y el dominio.

Configuración de Interfaz VLAN

Switch(config)#interface vlan 1
Switch(config-if)#ip address 192.168.20.1 255.255.255.0
Switch(config-if)#no shutdown

Generación de Claves RSA y Usuario

Switch(config)#hostname S1
S1(config)#ip domain-name cisco.com
S1(config)#crypto key generate rsa

El nombre para las claves será: S1.cisco.com. Elija... Continue reading "Configuración Esencial de Switches Cisco: Comandos y Seguridad" »

Cloud Platforms

Cloud platforms enable outsourcing much of a company's IT department. This pushes knowledge workers out and often automates their work. Data analysis, customer information storage, and server maintenance can be moved to the cloud, providing the capitalist rationale for using these platforms.

Amazon Web Services (AWS) was developed internally to handle the company's increasingly complex logistics while building a massive logistical network.

Industrial Platforms

As data collection, storage, and analysis become cheaper, more companies bring platforms into traditional manufacturing. The most significant attempt is the 'industrial internet of things' or 'industrial internet'. As factories implement industrial internet components, a major... Continue reading "Platform Capitalism: Data as Raw Material" »

Series Circuits

1. Connecting Generators in Series

How are two or more generators connected in series?
They are connected one after the other. Draw a wiring diagram showing three batteries connected in series.

Examples of portable devices using series batteries:

• Flashlight
• Remote control car
• TV remote control

2. Calculating Total Voltage

How is the total resulting voltage calculated when generators are connected in series?
The formula is: V = V1 + V2 + ... + Vn

• V: Total voltage
• V1: First generator
• V2: Second generator
• Vn: Last generator

Note: Refer to page 3 for specific flashlight bulb voltage requirements.

3. Light Intensity in Series

Which flashlights produce more light: those with two batteries or three?
Typically, those with three batteries produce more... Continue reading "Understanding Series Circuits: Principles and Applications" »