Character encoding

Character encoding is the process of assigning numbers to graphical characters, especially the written characters of human language, allowing them to be stored, transmitted, and transformed using digital computers. The numerical values that make up a character encoding are known as "code points" and collectively comprise a "code space", a "code page", or a "character map". Early character codes associated with the optical or electrical telegraph could only represent a subset of the characters used in written languages, sometimes restricted to upper case letters, numerals and some punctuation only. The low cost of digital representation of data in modern computer systems allows more elaborate character codes (such as Unicode) which represent most of the characters used in many written languages. Character encoding using internationally accepted standards permits worldwide interchange of text in electronic form. The history of character codes illustrates the evolving need for machine-mediated character-based symbolic information over a distance, using once-novel electrical means. The earliest codes were based upon manual and hand-written encoding and cyphering systems, such as Bacon's cipher, Braille, international maritime signal flags, and the 4-digit encoding of Chinese characters for a Chinese telegraph code (Hans Schjellerup, 1869). With the adoption of electrical and electro-mechanical techniques these earliest codes were adapted to the new capabilities and limitations of the early machines. The earliest well-known electrically transmitted character code, Morse code, introduced in the 1840s, used a system of four "symbols" (short signal, long signal, short space, long space) to generate codes of variable length. Though some commercial use of Morse code was via machinery, it was often used as a manual code, generated by hand on a telegraph key and decipherable by ear, and persists in amateur radio and aeronautical use. Most codes are of fixed per-character length or variable-length sequences of fixed-length codes (e.

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Related exercises (25)

Spring Oscillator

A block of mass m is connected to the floor and the ceiling of a room of height h by two springs. The springs have elastic constants k₁ and k₂ and null rest lengths, as indicated on the diagram. Gravity acts on the block. We only consider the block’s vertical motion, along an x-axis pointing downwards with its origin on the ceiling. We neglect the block’s shape, as well as any friction.

Draw, on a diagram, all the forces acting on the block and give their expressions.
Find the differential equ

Car suspension problem

A car’s suspension is comfortable when it has a vertical oscillation period that our bodies are used to: the oscillation period of walking, Tu2004=u20040.8u2005s.

Find the spring constant k of the suspension in a car of mass $M = 1540\,{\rm kg}$ .
The car lowers when we place a trunk of mass $m = 70\,{\rm kg}$ in it. Find its vertical displacement.

To make the car more comfortable, we add a shock absorber/dampener that creates a friction force F⃗u2004=u2004u2005−u2005bv⃗_(z), where v⃗_(z)

Loop the loop

A stuntwoman attempts to drive her car weighing mg around a vertical looping track of radius R. She enters the track at point P with velocity V⃗_(P) and we assume that she then free-wheels around the track without either braking or accelerating. There is no friction.

Write the car’s equations of motion for the entire loop.
Express the car’s mechanical energy at all points of the loop, and show that the mechanical energy is a simple integral of the motion.
Compute the reaction force from t

Spring in a box

A closed box of mass M is resting on a table. Inside the box is a marble of mass m, attached to the lid by a spring with spring constant k and rest length l₀. What’s the minimal amplitude A of the marble’s vertical oscillation for the box to lift from the table? We assume l₀ and k to be large enough for the marble to avoid hitting the lid or the table before the box takes off. u2005 Indication: treat both the box and the marble as material points. The box will take of if its bonding force with the table

Stable equilibrium

A solide is made up of a truncated straight homogeneous cone, with a circular base of radius R, set on a homogenous half-sphere of radius R and with the same density ρ, as shown on the diagram. The cone opens downwards with an apex half-angle α. Show that the solid is in a stable equilibrium on the horizontal plane if, and only if αu2004>u200430^(o). Hint: With origin O at the junction between both solids on axis z, the center of mass of the cone with volume

\frac{1}{3}\pi hR^2

is at height $z_{G_c}=\fr

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