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

Cloud Computing: An Overview

Cloud computing allows access to data and software over the internet, eliminating reliance on hard drives or SSDs. This facilitates convenient online backups of photos and private data, mitigating concerns about hardware crashes or viruses.

Cloud Provisioning

Cloud service providers invest heavily in storage hardware, data centers, and their maintenance, addressing temperature, security, humidity, hardware obsolescence, and more. Cloud provisioning encompasses various methods:

• Advance Provisioning: Clients contact providers, resources are prepared in advance, and fees are charged annually or monthly.
• Dynamic Provisioning: Resources are assigned as needed, often on a pay-per-use basis.
• User Self-Provisioning: Users purchase

Creating a User

SQL Command

CREATE USER <nombre_usuario> IDENTIFIED BY <password>;

Granting Privileges

SQL Command

GRANT CONNECT TO <nombre_usuario>;

Creating a Profile

SQL Command

CREATE PROFILE profile_name LIMIT limit(s) range;

Limits

• SESSIONS_PER_USER
• CPU_PER_SESSION
• CPU_PER_CALL
• CONNECT_TIME
• IDLE_TIME
• LOGICAL_READS_PER_SESSION
• LOGICAL_READS_PER_CALL
• COMPOSITE_LIMIT
• PRIVATE_SGA

Range Options

• UNLIMITED
• DEFAULT
• Integer value

Example Profile Creation

CREATE PROFILE MyProfile LIMIT PRIVATE_SGA 50K;

CREATE PROFILE app_user LIMIT

• SESSIONS_PER_USER UNLIMITED
• CPU_PER_SESSION UNLIMITED
• CPU_PER_CALL 3000
• CONNECT_TIME 45
• LOGICAL_READS_PER_SESSION DEFAULT
• LOGICAL_READS_PER_CALL 1000
• PRIVATE_SGA 15K
• COMPOSITE_LIMIT 5000000;

Creating Additional Profiles

CREATE PROFILE

Functions of the Drillstring:

• Transmits rotation to the drillbit
• Exerts weight on the bit; the compressive force necessary to break the rock
• Guides and controls the trajectory of the bit
• Allows fluid circulation for cooling and cleaning

Components of the Drillstring:

• Drillpipe
• Drillcollars
• Accessories including:

• Heavy-walled drillpipe (HWDP)
• Stabilisers
• Reamers
• Directional control equipment

The Kelly:

• Transmits rotation and weight-on-bit to the drillbit
• Supports the weight of the drillstring
• Connects the swivel to the uppermost length of drillpipe
• Transmits drilling fluid from the swivel into the drill string

The Top Drive:

A combined rotary table and Kelly mounted on the rig's swivel, assisting in pipe handling during operations.

Drilling Problems:

• Pipe Sticking
• Lost

Mechanism Classification

Mechanisms can be classified based on their function:

• Transmission of Motion:
  • Linear transmission (lever, pulley)
  • Rotatory transmission (gears and belt drive)
• Transformation of Motion:
  • Rotatory-linear (wheel, crank)
  • Reciprocating rotatory-linear (cam, crank and rod)
• Motion Control:
  • Direction control (ratchet and freewheel)
  • Speed reduction (brake)
• Energy Accumulation:
  • Absorption/dissipation (spring)
• Connection:
  • Linkage (clutch)
  • Support (plain bearing)

Energy and Work in Mechanisms

Mechanisms seem to increase force, but they cannot create energy on their own. All mechanisms produce the same amount of work that is done to them, including energy that is lost to friction and heat. If a mechanism increases force, it must decrease motion.... Continue reading "Principles of Mechanism and Motion Transfer" »

Understanding Material Properties and Types

Material Classification by Origin

• Raw Materials: Substances used for crafting objects or other materials.
• Natural Materials: Found in nature.
• Manufactured Materials: Obtained after an industrial process.
• Recycled Materials: Can be reused after initial use.

Material Families: A Technological Perspective

From a technological point of view, materials are categorized into five main families:

• Wood: Includes all types of wood, paper, and cardboard.
• Metals:
  • Natural: Such as iron (Fe), tin (Sn), aluminum (Al), copper (Cu), gold (Au), silver (Ag), platinum (Pt), lead (Pb), and zinc (Zn).
  • Artificial (Alloys): Like steel (Fe+C), bronze (Cu+Sn), or brass (Cu+Zn).
• Plastics: Mostly artificial, with exceptions like natural

Basic SQL Statements: DDL and DML Commands

Data Definition Language (DDL) Commands

DDL commands are used to define or modify the structure of database objects. All DDL commands are auto-committed, meaning they save all changes permanently in the database immediately after execution.

The primary DDL commands are:

• CREATE
• ALTER
• TRUNCATE
• DROP
• RENAME

CREATE Command

The CREATE command is used to define a new table structure. It uniquely defines each column, specifying its name and data type. Each column definition is separated by a comma, and the SQL statement is terminated with a semicolon.

Syntax:

CREATE TABLE table_name (
    column_name1 datatype1,
    column_name2 datatype2,
    ...
    column_namen datatypen
);

Example:

CREATE TABLE Student (
    reg_no

Electrical Resistivity of Materials

Materials are classified as conductors, semiconductors, and insulators depending on their resistivities, in an increasing order of their values.

• Conductors (e.g., Metals): Have low resistivities, typically in the range of 10^–8 Ωm to 10^–6 Ωm.
• Insulators (e.g., Ceramic, Rubber, Plastics): Have resistivities 10¹⁸ times greater than metals or more.
• Semiconductors: Fall in between conductors and insulators. Their resistivities characteristically decrease with a rise in temperature. The presence of small amounts of impurities also affects their resistivities. This last feature is exploited in the use of semiconductors for electronic devices.

Kirchhoff's Rules for Electric Circuit Analysis

Electric circuits generally... Continue reading "Electrical Properties of Materials and Circuit Analysis" »

Timber as a Construction Material

1. Types of Construction Timber

Hardwoods (e.g., Mvuli, Meru Oak, Mahogany, Eucalyptus)

• Difficult to work because of hardness; may require pre-drilled holes for jointing with nails.
• Useful for severe environmental exposure conditions, offering better resistance to wear, insect, and fungal attack than softwoods.
• Valued for aesthetic appeal.

Softwoods (e.g., Cedar, Podo, Pine, Cypress, Grevillea Robusta)

• Some types are commonly available in stockyards and are generally cheaper than hardwoods.
• Preferred in construction because they are easier to work and joint with nails.
• Have straighter grains than hardwoods.
• More liable to insect and fungal attack than hardwoods and require intensive preservation treatment.

Available Sizes:

What is Computer-Aided Engineering (CAE)?

CAE formalizes ideas through computer modeling and then fabricates the models into real-world objects through CAD and CAM.

What is Computer-Aided Reverse Engineering (CARE)?

CARE works in the opposite direction. CARE creates a computer model of an object through measurements of the object as it exists in the real world. CARE is the reversal of CAE.

What is a Coordinate Measuring Machine (CMM)?

• Coordinate Measuring Machines (CMMs) are a practical means for characterizing and inspecting free-form surfaces.
• Coordinate Measuring Machines (CMMs) first appeared in the early 1960s.
• A CMM consists of a probe supported on three mutually perpendicular (x, y, and z) axes, and each axis has a built-in reference standard.

Traffic Light with Arduino

This code simulates a traffic light using an Arduino.

int led_rojo = 3;
int led_verde = 4;
int led_amarillo = 5;

void setup() {
  pinMode(led_rojo, OUTPUT);  // PIN 3 as output
  pinMode(led_verde, OUTPUT); // PIN 4 as output
  pinMode(led_amarillo, OUTPUT); // PIN 5 as output
}

void loop() {
  digitalWrite(led_verde, HIGH); // Turn on green LED
  delay(2000);
  digitalWrite(led_verde, LOW);  // Turn off green LED
  delay(500);
  digitalWrite(led_amarillo, HIGH); // Turn on yellow LED
  delay(2000);
  digitalWrite(led_amarillo, LOW);  // Turn off yellow LED
  delay(500);
  digitalWrite(led_rojo, HIGH);   // Turn on red LED
  delay(2000);
  digitalWrite(led_rojo, LOW);    // Turn off red LED
  delay(500);
}

Button