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

Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM)

Scanning Tunneling Microscopy (STM)

Scanning Tunneling Microscopy (STM) is an instrument used for imaging surfaces at the atomic level, revealing the topography of conductive specimens. It measures tunneling current and can be used in air, water, and various gas environments, at temperatures ranging from near zero Kelvin to a few hundred degrees Celsius. STM operates in two modes: constant interaction mode and constant height mode.

Advantages of STM

• High resolution, not limited by diffraction
• Small sample size
• Can modify samples to create small structures
• Does not require a partial vacuum

Disadvantages of STM

• Difficult to determine detailed shapes
• Slow scanning speed
• Small image sizes
• Not

A file is a set of ordered documents that are related by some circumstance or event. It is essential for a company to have a file, that is to sort and classify documentation in a particular way.

Why Document Management is Important

• It allows to keep, store, and safeguard information
• Information can be easily and quickly found
• To comply with the law
• It can help in the decision-making process

Types of Files

1. Active: Documents that are currently being used and queried
2. Semi-active: Documents no longer effective but kept for legal reasons
3. Inactive: Documents not valid but with a historical or documentary value

File Systems

The file system is the criterion used for ordering information.

• Alphabetical: Information classified in the order of the alphabet. The ordering

What is Gas Used for in a Residential Building?

Gas provides the energy needed for a comfortable home, powering systems like:

• Heating systems
• Water heating systems
• Kitchen stoves

Gas Supply Methods and Types

How is Gas Supplied?

Gas can be supplied through:

• Pipelines: Natural gas is transported via an underground network.
• Cylinders: Butane and propane are commonly transported in cylinders.

Which Gases are Used?

Common residential gases include:

• Natural gas (pipelines)
• Butane (cylinders)
• Propane (cylinders and pipes)

Gas System Components

General Valve

The general valve controls the entire gas supply to the building.

Main Gas Supply Unit

The main gas supply unit, typically located in the street, connects the main gas line to the individual property line. It's... Continue reading "Residential Gas Systems: A Comprehensive Guide" »

Seed Drill - Jethro Tull

He perfected a horse-drawn seed drill in 1700 that economically sowed the seeds in neat rows (1714). He later developed a horse-drawn hoe.

Four Crop Rotation - Lord Townshend

Flying Shuttle - John Kay

The flying shuttle was one of the key developments in the industrialization of weaving during the early Industrial Revolution. It allowed a single weaver to weave much wider fabrics, and it could be mechanized, allowing for automatic machine looms.

Spinning Jenny - James Hargreaves

The spinning jenny is a multi-spindle spinning frame and was one of the key developments in the industrialization of weaving during the early Industrial Revolution. It was invented in 1764 by James Hargreaves in Stanhill, Oswaldtwistle, Lancashire,... Continue reading "Key Inventions of the Industrial Revolution" »

Essential Electronic Components

Relays

Relays are components used to control a high voltage current by means of a small current applied to a coil. When an electric current passes through the coil, it acts like an electromagnet and attracts a movable piece of metal that closes two contacts. If an electric current doesn't flow through the coil, the central contact stays joined to the contact on the left.

Capacitors

These are components that can store electric charge. They are made of two conductive plates separated by a non-conductive material called a dielectric. There are two kinds of capacitors: electrolytic and non-electrolytic capacitors. Electrolytic capacitors have terminals of different lengths, while non-electrolytic capacitors have terminals... Continue reading "Essential Electronic Components: Relays, Capacitors, and More" »

Gears: Basic Concepts

1. What are gears and what are they used for?

They are mechanical elements designed to transmit turning movements.

2. What does it mean when two gears "engage"?

It means their teeth fit into those of another similar wheel.

3. What are the two main characteristics of gears? How are they represented?

The two main characteristics are the number of teeth (Z) and the rotational speed (N).

4. What happens if two gears have a different number of teeth? And if they have the same number?

• If they have a different number of teeth, the smaller gear rotates faster than the larger gear.
• If they have the same number of teeth, they rotate at the same speed.

5. In a pair of gears, what role does the motor gear have? And the output gear?

• The motor

Understanding Levers: Simple Machines

What is a Lever?

Levers are simple machines. They are made up of a rigid bar and a point of support, which is also called a fulcrum. They are normally used to exert a large force using only a small force; they are a type of force multiplier.

Key Elements of a Lever

Resistance is the force that must be overcome by the applied force. The point of support, or fulcrum, is the point about which the lever swings. The arms, the force arm and the resistance arm, correspond to the distance between the fulcrum and the applied force or resistance, respectively.

• The force arm is the distance between the fulcrum and the applied force.
• The resistance arm is the distance between the fulcrum and the resistance.

The Law of the

Feasible (Factible)

Possible to do. Example: With the extra resources, the scheme now seems feasible.

Forklift (Máquina elevadora)

A small vehicle with two strong metal bars on the front, used for lifting heavy goods.

Full-scale Drawing (Dibujo a gran escala)

A drawing where the dimensions are the same as the real size of the object.

General Arrangement Drawing (Plano de disposición general)

Shows the layout of an entire assembly or structure, but does not provide details of smaller individual components.

Grid D14 (Cuadrícula D14)

In the designs of large structures, a grid is often superimposed on plan drawings to allow elements and installations to be located relative to the gridlines.

High Bay Warehouse (Almacén alto)

A tall warehouse, approximately

Computer Hardware and Usage: Q&A

Basic Computer Knowledge

1. What is a Bus?

   A bus is a device that determines how much data can be transmitted.

2. What Does She Look Like?

   She is beautiful, medium tall, with brown hair.

3. How Tall Are You?

   I am tall, one meter and seventy-four centimeters.

4. What is a Motherboard?

   The motherboard is the hub used to connect all the essential components of a computer.

Input and Output Devices

5) Define input and output device

An input device is a peripheral used to provide data and control signals to an information processing system.

An output device is any piece of computer hardware used to communicate the results of data processing.

RAM vs. ROM

6) What is the difference between ROM and RAM?

ROM: Access to memory information... Continue reading "Computer Hardware and Usage: Q&A for Students" »

Twisted Pair Cable Subclassifications

Unshielded Twisted Pair (UTP)

• They do not have a conducting screen.
• Advantage: Very flexible.
• Disadvantage: Very sensitive to interference.

Shielded Twisted Pair (STP)

• Each pair is surrounded by a protective mesh.
• Disadvantage: Less flexible.
• Advantage: Improved immunity to noise, reducing interference.

Shielded/Foiled Twisted Pair (S/FTP)

• An overall screen is added to all cables.
• Advantage: Enhanced noise immunity (even better than STP).

Foiled Twisted Pair (FTP)

• They have an overall conducting screen in the form of a braid.
• Advantage: Reduces interference.
• Disadvantage: More expensive than STP.

Analog vs. Digital Signals

• Analog signals represent continuous functions and can take any value within a range.
• Digital signals