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

Classifying Intermittent Injection Systems

Sequential: Fuel injectors provide fuel in a synchronized manner when the valve is open.

Semisecuencial: Fuel injectors trigger in couples every turn of the motor.

Simultaneous: Fuel injectors provide fuel at all times.

Accumulator Functions in NMEC Fuel Injection System

The accumulator keeps fuel pressure in the circuit after the engine stops, and it dampens the noise produced by the fuel pump.

Difference between Injection and Sequential Semisecuencial

The sequential injection fuel injectors provide fuel in a synchronized manner when the intake valve is open. The injection nozzles are driven by semisecuencial couples every turn of the motor.

No Combined Injections System

The combined injection systems are... Continue reading "Fuel Injection Systems: Operation and Functionality" »

What is Computer Security?

Security is the set of actions, tools, and devices whose purpose is to provide a computer system with integrity, confidentiality, and availability.

• Integrity: Prevents the modification of information by any user who has not been previously authorized.
• Confidentiality: Prevents data visualization by users who have no privileges on the system.
• Availability: Ensures that authorized users have access to the system and its resources when needed.

What Must We Protect Against?

We must protect against ourselves, accidents, breakdowns, malicious intruders, and malware.

Active Security

Active security is designed to prevent damage to computer systems:

1. Appropriate passwords
2. Data encryption
3. Computer security software

Passive Security

Passive

Character Devices and Block Devices

Character devices read and write data as a byte stream. Examples of character devices are printers and keyboards that allow the handling of a single byte at a time.

Block devices read and write information in fragments ("blocks") to the block device at a time. Examples include hard drives, floppy disks, and CD/ROM drives.

Locate Command

The locate command writes the names of files and directories that match a given pattern. It is the fastest of the two commands because it depends on a database (updated daily by default) instead of looking in real-time. It finds files that have been deleted since the last update of the database.

bzip2 Command

The bzip2 command tends to generate more compact compressed files but... Continue reading "Character & Block Devices, bzip2, Inodes, Links, Find & Mount" »

Hydraulic Systems

Storage

Fluid storage tanks are constructed of steel plates and brackets to contain fluid, sediment, and contaminants, and to dissipate generated heat. These tanks are typically coated with water-resistant paint. The bottom of the tank should be sloped with a drain plug for vacuum cleaning. Lids, vents, and air filters prevent the entry of impurities. Baffles within the tank prevent turbulent flow, allowing sediment to settle, separating air from the fluid, preventing foaming, and dissipating heat. Tank capacity should be 2-3 times the pump supply group capacity. Tanks should also have a sight glass, suction line, return line, and drainage.

Filtration

Filtration is the mechanical or physical process of separating materials using... Continue reading "Hydraulic Systems: Components, Functionality, and Maintenance" »

Force

Force is an action capable of producing or modifying the state of motion or deformation. It can be observed through the effects produced by contact or distance between two bodies. Forces are represented by arrows indicating direction and sense. They are measured using a dynamometer, with the unit being Newton.

Mechanical Properties

Mechanical properties determine the behavior of materials when subjected to forces.

Resistance

The ability of a material to resist forces without distorting or breaking.

• Tenacity and Fragility: Tenacity is the property of a material to withstand forces and shocks without breaking, while fragility is the opposite.
• Elasticity: The property of a material to recover its original shape after being deformed by a force.
• Plasticity:

Composite Materials

Selection Criteria of the Method to Use

1. Specified technology
2. Production parameters

Cost per Piece

• Preparation and setup time
• Tooling needs, equipment, and human resources
• Production rates
• Material cost
• Size range

Ranking Methods

Contact Molding

Molded fiber-matrix (of the piece). Starting material:

1. In situ dry fiber impregnated with resin. Wet process.
2. Fiber resin impregnated with cure retardant.

Prepregs: Mat and mixed. 70% fiber, guidance! Cut pollution, not very expensive, 10 layers, vacuum autoclave, existing alternatives.

Variants

(Increase production rates when structural requirements are not high):

1. Projection Method: Mix by air pressure. Reduces production time by 30%.

2. Centrifuge Method: The projection of the mixing is done inside a

Otto Engine Characteristics

The Otto engine is an internal combustion engine that utilizes a pre-mixed fuel-air mixture. Key characteristics include:

• Internal Combustion: Consumes a fuel-air mixture.
• Electric Ignition: Employs an electric system to ignite the compressed mixture.
• Valve Control: Intake and exhaust valves are precisely controlled by the engine's operating system.

Otto Cycle

The Otto cycle consists of four strokes, equivalent to two crankshaft revolutions:

1. Intake: Admission of the air-fuel mixture.
2. Compression and Ignition: Compression of the mixture followed by spark ignition.
3. Combustion and Expansion: Burning and expansion of the mixture, generating power.
4. Exhaust: Expulsion of combustion byproducts.

Fuel

The Otto engine typically uses petroleum-... Continue reading "Otto Engine: Characteristics, Combustion, and Components" »

Semiconductors

The simplest elements used in making semiconductors are silicon and germanium. In their pure state, silicon and germanium are insulators.

Diodes

By attaching a positive (+) semiconductor and a negative (-) semiconductor, we obtain the simplest electronic device called a diode: (+)--->|---(-). During the operation of a diode, there is a loss of electrical energy that is converted into heat. This is the weak point of devices employing semiconductors.

Application as a Protection Diode

A diode can be used as protection for electronic equipment, preventing a change in the polarity of the power connection.

Application of Diodes as a Circuit Breaker

The function of the diode as a circuit breaker, in this case, is to allow current to pass... Continue reading "Semiconductors, Diodes, Thyristors, Triacs, and Transistors" »

What is a Car Battery?

The battery is a crucial power supply component in a vehicle. It provides the necessary electrical current to the starter motor, enabling the engine to start. Think of it like a water pump in a water circuit: the pump forces water through pipes to consumers. When the pump sends more water than is consumed, the excess goes into a reservoir, which can then supply consumers. Similarly, a battery provides a consistent power supply, preventing shocks or fluctuations.

Most cars use lead-acid batteries, which convert chemical energy into electrical energy through a process called electrolysis.

Electrolysis Explained

If you immerse two electrodes in distilled water and connect them to a power source with a lamp, the lamp won't light,... Continue reading "Car Batteries: Structure, Function, and Capacity" »

Machine Tools: Function and Basic Components

Machine tools substitute manual action with a series of mechanical movements, reducing and simplifying human effort.

Basic Machine Tool Components

1. Motor: Converts electrical energy into rotary motion, imparting it to the working axis/axes through transmission systems.
2. Bed: The machine's base, supporting and assembling various components. Typically made of cast iron, it usually has guidelines for the movement of kinematic parts.
3. Kinematic Chain: Includes elements providing transmission and advancement of the workpiece or tool movement.
4. Headstock: Incorporates the work axis/axes and a gearbox to regulate speeds and movements of the tool or workpiece.
5. Spindle: Holds the tools or machined parts, using appropriate