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

Mechanisms

Mechanisms are devices that transform movement. They can change the speed, direction, force, or type of movement.

Belts and Pulleys

A belt passes around two pulley wheels. If the driver wheel moves, it moves the belt, and the belt moves the driven wheel.

A pulley is a wheel that turns when a rope, belt, or chain passes through it.

Levers

The lever is a basic mechanism. It's typically made of a bar of wood or metal that pivots around a fixed point called a fulcrum.

• First-type lever Examples: Scissors, pliers, bottle opener, seesaw.
• Second-type lever Examples: Wheelbarrow, paint chippers, nutcrackers.
• Third-type lever Examples: Catapult, baseball bat, human arm.

Effort x Effort arm = Load x Load arm

Questions about levers and pulleys

1. What does

Nickel Steels

Nickel steels are known for their stainless and electrical properties. Nickel increases the tensile strength, yield stress, elongation, and impact strength or resilience of steel, while simultaneously reducing the influence of heat expansion. Steels containing 10 to 15% nickel can be hardened even with slow cooling.

Chromium Steels

Chromium imparts hardness and deeper penetration of the temper, allowing for oil hardening. Steels with 1.15 to 1.30% carbon and 0.80 to 1% chromium are used for film production due to their hardness. Smaller-scale applications use steels with 0.3-0.4% carbon and 1% chromium.

Chrome-Nickel Steels

More commonly used than chromium steels alone, chrome-nickel steels are employed in various ratios. Examples...

The Internet: A Global Network

The Internet is a global network of interconnected computer networks, linking billions of devices worldwide using TCP/IP. It comprises millions of networks, including private, public, academic, business, and government, and provides extensive information resources.

The History of the Internet

The Internet, originating from ARPANet, an experimental network created in the 1960s by the US military, was launched online in 1969 under a contract by ARPA, connecting four US universities. The history of the Internet reflects the continuous growth of this network, connecting millions of people, businesses, governments, schools, and universities.

The ARPANet

The ARPAnet, created in 1969, began with four computers connecting....

Classification of Technical Drawings

Technical drawings, as defined by standards like UNE 1 to 166 - 1:1996, ISO 10209 - 1:92, or DIN 199, are classified into different types based on their representation, form, content, and purpose.

Technical Drawings by Representation

• Sketch: Freehand representations used for initial product development.
• Scale Drawing: Accurate representations drawn to scale, including all necessary technical details.

Technical Drawings by Form

• Original Drawing: The initial drawing, created manually or using CAD software, typically on transparent paper.
• Reproduction: A copy of the original drawing, produced through printing, photography, or blueprinting.

Technical Drawings by Content

• Assembly Drawing: A comprehensive drawing showing

**Protection and Indirect Contacts**

Luminaires shall be Class I or Class II. Accessible metal parts of the luminaires will be connected to the ground. Excluded from this requirement are those metal parts with double insulation that are not accessible to the general public. For access to the interior of luminaires installed at a height less than 3 meters above the ground or in a publicly accessible space, the use of special tools will be required. All metal structures within a distance of less than 2 meters from the metal parts of the exterior lighting installation shall be joined together equipotentially. It must be ascertained whether these metallic elements can transfer dangerous voltage points to a distance (e.g., metallic). In which case,...

Solid Bulk Terminals

As the name implies, solid bulk terminals handle bulk cargo and are typically located near port entrances.

Design

These terminals don't require a continuous berth. The current trend is to construct them with a light working platform.

Goods

Solid bulk terminals handle various goods, categorized as follows:

• Primary Bulk Cargo: Iron ore, cereals, coal, bauxite, and phosphates.
• Secondary Bulk Cargo: Metals, minerals for construction (coke, cast iron, cement, magnesium ore, scrap), and other agricultural products.

Storage

Storage methods depend on the cargo type:

• Clean Bulk: Products for human or animal consumption (cereals, flour, animal feed) require specific handling and storage facilities.
• Dirty Bulk: Materials from mining and steel

Electronic Components Guide

Basic Components

Battery

A device consisting of one or more electrochemical cells with external connections for powering electrical devices. Power supply.

Light Bulb

An electric light with a wire filament heated until it glows. The filament is enclosed in a bulb to protect it from oxidation. Load device.

Motor

An electrical machine that converts electrical energy into mechanical energy. Load device.

Buzzer

A device that makes a buzzing noise and is used for signaling. May be mechanical, electromechanical, or piezoelectric. Load device.

Semiconductor Components

Diode

Formed by the union of two semiconductors: P-type (anode) and N-type (cathode). Load device.

Light-Emitting Diode (LED)

An electronic device that emits light when...

Moulds for Casting

Mould made of ceramic material e.g. sand particles, bound together with a BINDER which may be:

• Clay: 90% sand, 8% clay, 2% water - green sand mould.
• Thermosetting resin system - coat sand with two or more reactants which cure to form a resin (typically 1 - 2 parts binder to 100 parts sand):
  • Curing begins immediately components are combined, for a period of time after initial mixing the sand is workable and flowable to allow filling of mould - No bake systems.
  • Phenolic - urethane no bake is most common.
  • Curing occurs upon application of heat – heat cured binder system.
  • Liquid thermosetting binder and a catalyst are mixed with dry sand. Upon heating the catalyst releases acid which induces a rapid cure in 10 – 15 s. Pattern is

Classification of Consumption Sites

Consumption sites are primarily classified as:

• Residential or Commercial: Buildings intended for living or business purposes.
• Office: Buildings specifically designed for office use.
• Industry-Specific: Facilities tailored to the needs of a particular industry.
• Industrial Concentration: Areas designated for a cluster of industries.

Load Forecasting

Load forecasting considerations for different building types:

• Housing: Residential buildings.
• General Services: Common areas and shared facilities.
• Shops and Offices: Commercial spaces and office buildings.
• Garages: Parking facilities.

Degree of Electrification

• Basic Electrification: Designed to meet primary usage needs, allowing for common household equipment (5750 W).
• High Electrification:

SQL Cheat Sheet

Insert Data

INSERT INTO tabla(col1,col2) VALUES(val2,val2)
INSERT INTO tabla SET col1='va1',col2='val2'
INSERT INTO ON DUPLICATE KEY UPDATE ...
REPLACE INTO tabla VALUES ...

Update Data

UPDATE tabla SET col1='val1' WHERE ...
UPDATE tabla SET col1=(SELECT ...)

Delete Data

DELETE FROM tabla WHERE cond

Transactions

TRANSACTIONS:
START TRANSACTION;
INSERT INTO ...;
SAVEPOINT prueba;
INSERT INTO ...;
ROLLBACK TO SAVEPOINT prueba;
SET autocommit=0;
COMMIT;

Locking

LOCK TABLES tabla1 WRITE, tabla2 WRITE;
UNLOCK TABLES;

Stored Procedures

CREATE PROCEDURE nombre()
BEGIN
DECLARE a INT;
SELECT x INTO a ...;
END;
CALL procedure();

Functions

CREATE FUNCTION nombre(m VARCHAR(255))
RETURNS INT
BEGIN
DECLARE existe INT DEFAULT 1;
DECLARE tot, k INT;
DECLARE cur_1 CURSOR...