The motion of charged
particles of pigments suspended in a liquid under the influence of an electric
field is known as Electrophoresis. Electrophoretic image displays use this
phenomenon. The main parts of this display are dc voltage source, base plate,
electrode segments, coloured liquid, transparent electrode and electrophoretic
pigment particles. A liquid suspension consists of pigment particles are
sandwiched between a pair of electrodes. One among the two electrodes is
transparent and made as common electrode. On the application of dc electric
field, pigment particles move electrophoretically towards electrodes and this
motion is dependent on the polarity of the charge on the particles. The
transparent electrode is preferably maintained at ground potential and segment
electrodes at different potentials. Colour combinations of both the pigment
particles and the suspending liquid can be used to achieve a desired colour
display. Electrophoretic image displays are characterized by large character
size, low power dissipation and internal memory.
Thursday, June 20, 2013
Tuesday, May 7, 2013
Cryptography techniques
Cryptography is an art
of codifying messages to avoid possible attacks. Sniffing, Spoofing and
phishing are some common internet attacks. Attacks can be classified into two-
Passive attack where attacker does not modify the contents of a message and
Active attack where attacker modifies the content of the message. Cryptography
is an efficient method to increase the security of messages where some codes
are used to make message non-readable. The message in the non-readable format
can be decoded by a technique, Cryptanalysis. The combination of Cryptography
and Cryptanalysis is known as Cryptology. In the first step, plain text is
converted into Cipher text, a codified text. For this we can employ two
techniques- substitution techniques and transposition techniques. Caesar
cipher, modified version of Caesar cipher, mono-alphabetic cipher, homophonic
substitution cipher, polygram substitution cipher, poly-alphabetic substitution
cipher, playfair cipher and hill cipher are examples for substitution
techniques. Example for transposition techniques are Rail fence.
Tuesday, December 18, 2012
Computer vision
Computer vision is an
emerging technology. Here the reconstruction of explicit and meaningful
descriptions of physical objects from images is carried out using some
innovative techniques. Computer vision which is also known as machine vision
finds applications in many areas like military, medicine and manufacturing. Computer
aided tomographic scan (CT scan or CAT scan), a diagnostic tool used in
medicine is based on computer vision. Computer vision finds its military
application in aerial photography which helps to locate enemy naval vessels. In
manufacturing field, computer vision is applied in locating and modifying
different machine components such as conveyer belts, robotic mechanical parts
etc. Computer vision systems are classified into three. They are two-dimensional
system, stereo vision and structured light system. Two dimensional system is
just like an optical comparator. Stereo vision system uses two cameras. A laser
system is employed in structured light system.
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