Category Science

WHAT IS SMELTING?

Smelting is what is known as a reduction reaction. It is a method of extracting iron from iron ore. Iron ore, or haematite, is a rock that contains iron and oxygen. The process of smelting takes place in a blast furnace, where iron ore, limestone and coke (a form of carbon) are heated together while hot air is blasted into the furnace. The carbon in the coke reacts with the oxygen in the air to form carbon monoxide. This is turn takes oxygen from the iron ore, leaving behind iron mixed with a little carbon.

The majority of Earth’s iron, however, exists in iron ore. Mined right out of the ground, raw ore is mix of ore proper and loose earth called gangue. The ore proper can usually be separated by crushing the raw ore and simply washing away the lighter soil. Breaking down the ore proper is more difficult, however, as it is a chemical compound of carbonates, hydrates, oxides, silicates, sulfides and various impurities.

To get to the bits of iron in the ore, you have to smelt it out. Smelting involves heating up ore until the metal becomes spongy and the chemical compounds in the ore begin to break down. Most important, it releases oxygen from the iron ore, which makes up a high percentage of common iron ores.

The most primitive facility used to smelt iron is a bloomery. There, a blacksmith burns charcoal with iron ore and a good supply of oxygen (provided by a bellows or blower). Charcoal is essentially pure carbon. The carbon combines with oxygen to create carbon dioxide and carbon monoxide (releasing lots of heat in the process). Carbon and carbon monoxide combine with the oxygen in the iron ore and carry it away, leaving iron metal.

In a bloomery, the fire doesn’t get hot enough to melt the iron completely. Instead, the iron heats up into a spongy mass containing iron and silicates from the ore. Heating and hammering this mass (called the bloom) forces impurities out and mixes the glassy silicates into the iron metal to create wrought iron. Wrought iron is hardy and easy to work, making it perfect for creating tools.

Tool and weapon makers learned to smelt copper long before iron became the dominant metal. Archeological evidence suggests that blacksmiths in the Middle East were smelting iron as early as 2500 B.C., though it would be more than a thousand years before iron became the dominant metal in the region.

­To create higher qualities of iron, blacksmiths would require better furnaces. The technology gradually developed over the centuries. By the mid-1300s, taller furnaces and manually operated bellows allowed European furnaces to burn hot enough to not just soften iron, but actually melt it.

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WHAT IS A ROBOT?

A robot is a machine—especially one programmable by a computer— capable of carrying out a complex series of actions automatically. Robots can be guided by an external control device or the control may be embedded within. Robots may be constructed on the lines of human form, but most robots are machines designed to perform a task with no regard to their aesthetics.

Robots that resemble humans are known as androids; however, many robots aren’t built on the human model. Industrial robots, for example, are often designed to perform repetitive tasks that aren’t facilitated by a human-like construction. A robot can be remotely controlled by a human operator, sometimes from a great distance. A telechir is a complex robot that is remotely controlled by a human operator for a telepresence system, which gives that individual the sense of being on location in a remote, dangerous or alien environment and the ability to interact with it. Telepresence robots, which simulate the experience and some of the capabilities of being physically present, can enable remote business consultations, healthcare, home monitoring and childcare, among many other possibilities.

An autonomous robot acts as a stand-alone system, complete with its own computer (called the controller). The most advanced example is the smart robot, which has a built-in artificial intelligence (Al) system that can learn from its environment and its experience and build on its capabilities based on that knowledge.

Swarm robots, sometimes referred to as insect robots, work in fleets ranging in number from a few to thousands, with all fleet members under the supervision of a single controller. The term arises from the similarity of the system to a colony of insects, where the individuals and behaviors are simple but the fleet as a whole can be sophisticated.

Robots are sometimes grouped according to the time frame in which they were first widely used. First-generation robots date from the 1970s and consist of stationary, nonprogrammable, electromechanical devices without sensors. Second-generation robots were developed in the 1980s and can contain sensors and programmable controllers. Third-generation robots were developed between approximately 1990 and the present. These machines can be stationary or mobile, autonomous or insect type, with sophisticated programming, speech recognition and/or synthesis, and other advanced features. Fourth-generation robots are in the research-and-development phase, and include features such as artificial intelligence, self-replication, self-assembly, and nanoscale size (physical dimensions on the order of nanometers, or units of 10- meter).

Some advanced robots are called androids because of their superficial resemblance to human beings. Androids are mobile, usually moving around on wheels or a track drive (robots legs are unstable and difficult to engineer). The android is not necessarily the end point of robot evolution. Some of the most esoteric and powerful robots do not look or behave anything like humans. The ultimate in robotic intelligence and sophistication might take on forms yet to be imagined.

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HOW ARE ROBOTS USED FOR DANGEROUS JOBS?

There are many situations in which human beings can operate safely only by wearing bulky protective clothing and working for short periods at a time. Sometimes even that is not enough to protect them. If it is suspected that a booby-trapped bomb has been left in an abandoned vehicle, for example, a controlled explosion may be the only way of deactivating it. No matter how much protection a bomb disposal expert has, the explosion could be fatal if he or she is nearby. The answer is to use a robot carrying an explosive charge. The robot can be sent into the danger zone while experts remain at a safe distance. Although no one wants to destroy an expensive machine, the alternative is much worse.

Dirty jobs are often unsanitary or hazardous work that can impact human health. Even though these jobs are unfavorable, someone has to do them. They include waste management, livestock nurturing, and mine exploration. The robot can take away the risk from humans and keep them safe from harm.

One example is the need for sewer scrapers. When there is a problem with a sewer pipe, a crew shuts it off, digs to access the pipe, then fixes the infrastructure. But a robot can clean, map, and inspect pipes before the problems arise. Robots can also collect data like distance, pressure, temperature, and composition to get visibility of pollutants, infectious diseases, and drug use.

Dangerous jobs put humans in harmful situations. To prevent the loss of human life, robots can be used. They are able to measure and detect variables beyond human perception. Robots can defuse bombs, traverse distant planets, and inspect unstable structures. Robots are being used to inspect bridges. A high degree of expertise, risk, and cost is associated with manned bridge inspections. Multirotor drones are able to completely remove humans from dangerous situations. They inspect hard-to-access areas with advanced speed and maneuverability.

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HOW ARE ANGLES MEASURED?

Angles are measured in degrees, using a protractor. There are 360° in a circle, and 90° in a right angle. A triangle has a total of 180° in its three inner angles, so that if the size of two angles is known, it is always possible to work out the third. Since pairs of inner and outer angles must add up to 360°, it is also possible to work out the inner angles if two of the outer angles are known.

The concept of angle is one of the most important concepts in geometry. The concepts of equality, sums, and differences of angles are important and used throughout geometry, but the subject of trigonometry is based on the measurement of angles.

Angles: 15, 30, 45 degrees.

There are two commonly used units of measurement for angles. The more familiar unit of measurement is that of degrees. A circle is divided into 360 equal degrees, so that a right angle is 90°. we’ll only consider angles between 0° and 360°.

Degrees may be further divided into minutes and seconds, but that division is not as universal as it used to be. Each degree is divided into 60 equal parts called minutes. So seven and a half degrees can be called 7 degrees and 30 minutes, written 7° 30′. Each minute is further divided into 60 equal parts called seconds, and, for instance, 2 degrees 5 minutes 30 seconds is written 2° 5′ 30″. The division of degrees into minutes and seconds of angle is analogous to the division of hours into minutes and seconds of time.

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HOW CAN STANDARD UNITS BE USED FOR VERY SMALL AND VERY LARGE MEASUREMENTS?

Metric units can be multiplied or divided by 10 as often as is needed to create units of a useful size for measuring the object under consideration. For example, a unit of 1000 metres, which is the same as 10 x 10 metres, and can be written as 102 metres, is called a kilometre. The prefix “kilo”, meaning one thousand, can be applied to other units. A kilogram (kg) is equal to one thousand grams. Similarly, there is a prefix meaning one thousandth (10-3): milli. So one milligram is the same as a thousandth of a gram. On the right is a list of other prefixes and their meanings.

Length is the measurement of the extent of something along its greatest dimension. The SI basic unit of length, or linear measure, is the meter (m). All measurements of length may be made in meters, though the prefixes listed in various tables will often be more convenient. The width of a room may be expressed as about 5 meters (m), whereas a large distance, such as the distance between New York City and Chicago, is better expressed as 1150 kilometers (km). Very small distances can be expressed in units such as the millimeter or the micrometer. The width of a typical human hair is about 20 micrometers (?m).

Volume is the amount of space occupied by a sample of matter. The volume of a regular object can be calculated by multiplying its length by its width by its height. Since each of those is a linear measurement, we say that units of volume are derived from units of length. The SI unit of volume is the cubic meter (m 3 ), which is the volume occupied by a cube that measures 1 m on each side. This very large volume is not very convenient for typical use in a chemistry laboratory. A liter (L) is the volume of a cube that measures 10 cm (1 dm) on each side. A liter is thus equal to both 1000 cm3 (10 cm × 10 cm × 10 cm) and to 1 dm3. A smaller unit of volume that is commonly used is the milliliter (mL—note the capital L which is a standard practice). A milliliter is the volume of a cube that measures 1 cm on each side. Therefore, a milliliter is equal to a cubic centimeter (cm3). There are 1000 mL in 1 L, which is the same as saying that there are 1000 cm3 in 1 dm3.

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HOW ARE LATITUDE AND LONGITUDE MEASURED?

To pinpoint your position on a map of the world you need to work out your co-ordinates, known as latitude and longitude. Latitude is your position north or south of the Equator. Lines, or parallels, are drawn around the Earth at intervals. The North Pole is assigned the latitude 90º north and the South Pole latitude 90º south.

Lines of longitude, or meridians, are drawn a little differently. The line of longitude corresponding to 0º, which passes through Greenwich in London, is called the Prime (or Greenwich) Meridian. Longitude lines run along the Earth’s surface in a north–south direction, and unlike latitude lines, they divide the globe into segments like those of an orange, rather than regular strips.

It’s possible to measure latitude by comparing your position on Earth with the position of either the sun or the North Star (Polaris). Measurements using the sun are possible on a clear day in the northern or southern hemispheres, when the sun is easy to find. However, measurement of latitude isn’t as straightforward as you might think. Accurate readings can only be taken at noon, when the sun is at its highest in the sky. To complicate matters further, the sun rises higher in summer than in winter, and this must be allowed for in any calculation.

Being so far away and only one of a myriad stars visible to the naked eye, the North Star isn’t as easy to find as the sun. Furthermore, you can only see it at night, which isn’t always convenient. Its major limitation, however, is that it isn’t visible from the southern hemisphere.

For our purposes, we shall therefore assume that we’re in the northern hemisphere. You can use a simple quadrant to measure latitude using either the sun or the North Star.

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