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

Common Fabrics and Materials

Textiles and Clothing Fabrics

• Terciopelo (Velvet): Gloves, dresses, costumes, and scarves.
• Seda (Silk): Scarves, bed sheets, and handkerchiefs.
• Cotele (Corduroy): Pants, coats, vests, and scarves.
• Lana (Wool): Caps, vests, dresses, and scarves.
• Algodón (Cotton): Vests, jackets, pants, and shirts.
• Lino (Linen): Tablecloths, bedspreads, and shawls.
• Poliéster (Polyester): Bags, coats, hoodies, socks, and jackets.

Durable and Industrial Materials

• Cuero (Leather): Jackets, suits, bags, sneakers, wallets, and shirts.
• Goma (Rubber): Boots, jackets, ponchos, and gloves.
• Plástico (Plastic): Pens, bottles, toys, and boots.
• Gamuza (Suede): Sneakers, boots, belts, and bags.
• Acero (Steel): Screws, chairs, sculptures, and bowls.
• Papel (Paper)

Fundamental Concepts of Forces and Structures

A force is anything that can deform a body (static effect) or change its state of movement or rest (dynamic effect).

Examples of Forces

• Gravity: Pulls us towards the Earth and gives us weight.
• The force of the wind.
• Mechanical forces that move machines.
• Pressures of gases in closed containers.
• The force created by the effects of heat.

A structure is the set of elements in a body that are intended to resist the effects of the forces that act on it. A structure prevents a body from breaking or becoming too deformed.

Loads and Internal Stresses

The forces that act on a structure are called loads.

Types of Loads

• Fixed or Permanent Loads: Do not vary over time.
• Variable Loads: Are occasional and changeable.

Loads... Continue reading "Principles of Structural Mechanics and Applied Forces" »

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

Linux 根目錄結構說明

/bin/：基本程式。

/boot/：Kali Linux 核心及早期啟動過程所需的其他檔案。

/dev/：設備檔案。

/etc/：設定檔。

/home/：使用者的個人檔案。

/lib/：基礎函式庫。

/media/：可移除裝置（CD/DVD-ROM、USB 隨身碟等）的掛載點。

/mnt/：臨時掛載點。

/opt/：第三方提供的額外應用程式。

/run/：易失性執行時資料，重新開機後不會保留（尚未包含在 FHS 中）。

/sbin/：系統程式。

/srv/：該系統上所託管伺服器使用的資料。

/usr/：應用程式。此目錄依照與根目錄相同的邏輯進一步細分為 bin、lib 等子目錄。

/var/：服務處理的可變資料，包括日誌檔、佇列、假脫機及快取。

Linux 核心專用目錄

/

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" »