The electromagnetic spectrum

Different forms of energy spread across a range called the electromagnetic spectrum. Energy forms in this spectrum have both electrical and magneticcharacteristics. They travel as electromagnetic waves. All waves have wavelength and frequency. A wave has an uppermost crest and a bottommost trough.

Wavelength is the distance between the crest of one wave and the next (or between the trough of one wave and the next). Wavelength may be expressed in millimicrones. Frequency is the number of waves that pass a given point in a given time. Frequency is expressed in hertz, or cycles per second. An inverse relationship exists in the electromagnetic spectrum. As the wavelengths of energy forms grow longer, their frequencies diminish. Gamma rays have the shortest wavelengths and the highest frequencies; long radio waves have the longest wavelengths and the lowest frequencies. We can directly sense only a small portion of the electromagnetic spectrum. We can see visible light and feel the heat of infrared rays. Other forms require instruments that convert the energy into perceptible forms, such as gamma ray counters or radio receivers.

 

THE ROBOT’S DESIGN

What are industrial robots and how do they work? Although they vary widely in shape, size and capability, industrial robots are made up of several basic components: the manipulator, the control and the power supply.

The manipulator is the mechanical device, which actually performs the useful functions of the robot. It is a hydraulically, pneumatically or electrically driven jointed mechanism capable of number independent coordinated motions. Feedback devices on the manipulator’s joints or actuators provide information regarding its motions and positions to the robot control. A gripping device or tool, designed for the specific tasks to be done by the robot, is mounted on the outermost joint of the manipulator. Its function is directed by the robots control system.

The control stores the desired motions of the robot and their sequence in its memory; directs the manipulator through this sequence or “program” upon command; and interacts with the machines, conveyors and tools with which the robot works. Controls range in complexity from simple stepping switches to minicomputers.

 

GENERATING X-RAYS

X-rays are forms of radiation higher on the electro-magnetic spectrum than closely related ultraviolet waves. X-rays have great penetrating power because their short wavelength and high frequency let them travel easily between the atoms of a substance. X-rays are emitted from many sources in the universe. They can also be generated for medical and industrial uses. When photographic film is placed behind an object being X-rayed, the developed roentgenogram reveals a shadow picture of the object. For instance, when a hand is X-rayed, the roentgenogram shows the bones of the hand as white shapes against a black background. This is because X-rays do not penetrate the dense flesh and thus do not expose (darken) the areas of the film covered by the bones. X-rays can be produced by high-vacuum X-ray tubes.

Such tubes consist of an airtight glass container with two electrodes – one positive and one negative – sealed inside. The cathode, or negative electrode, has a small coil of wire. The anode, or positive electrode, consists of a block of metal. An electric current flows through the cathode, causing it to become extremely hot. The heat releases electrons from the cathode. At the same time, a high voltage is applied across the cathode and the anode. This voltage forces the electrons to travel at high speeds towards the tungsten target. When the electrons strike the target, X-rays are produced.

 

HISTORY OF THE COMPUTER

For a long time a man has been looking for ways of increasing the speed of computations. The history of computers starts out about 3000 B.C. at the birth of the abacus, a wooden rack holding two horizontal wires with beads which are moved around according to programming rules memorized by the user, so all regular arithmetic problems can be done. It is still in existence and used by some part of the world’s population. It made valuable contributions, including positional notation. Another important invention around the same time was the Astrolabe, used for navigation.

The achievements in this field which step by step led to the computer as we know it today include such names as Napier (1612) – the inventor of logarithms; Pascal (1642) – the creator of the first gear-driven calculating machine. It added numbers entered with dials. Calculating devices in use today closely resemble Pascal’s machine.

In 1671 Gottfried Wilhelm von Leibniz improved on Pascal’s machine. He invented a special mechanism, which is still used in many modern day calculators.

Ch.X. Thomas created the first successful mechanical calculator that could add, subtract, multiply and divide. Jacquard (1801) developed the punched-card principle followed by Hollerith’s (1800) “unit record” principle by which data were coded and represented by holes in cards. He developed an automatic sorting machine, a cardpunch machine and semiautomatic tabulating machine. He organized “The Tabulating Machine Company” which with some other companies became the International Business Machines Corporation in 1924 (the famous IBM).

By 1890 the range of improvements included accumulation of partial results, storage and automatic reentry of past results (a memory function), printing of the results.

Ch. Babbage (1850) a mathematics professor in Cambridge constructed large-scale calculating machines when he realized that many long calculations were really a series of predictable actions that were constantly repeated. He called his automatic mechanical calculating machine a difference machine. The difference machine was really a great advance. Babbage continued to work on it for 10 years but then he started to work at the construction of a fully program-controlled, automatic mechanical digital computer. He called this idea an Analytical Engine, but failed because the necessary parts couldn’t be manufactured precisely in his time. Despite failures, his work made a valuable contribution to the later engineering of calculating machines.

Between 1850 and 1900 great advances were made in mathematical physics and it came to be known that most observable dynamic phenomena can be identified by different equations (which meant that most events occurring in nature can be measured or described in one equation or another).