internet protocols

there are three layers of protocol

at the lowest level is IP (internet protocol) , which defines the
data grams or packets that carry blocks of data from one node to
another .the vast majority of today,s internet uses version four of
the IP protocol although IPv6 is standardised

next name is TCP (transmission control protocol0 , UDP (user datagram
protocol ), and ICMP (internet  control message protocol) – the
protocols by which data is transmitted. TCP makes a virtual
‘connection” which gives level of some guarantee of reliability . UDP
is a best effort, connectionless transport , in which data packets
that are lost in transit will not be resent.ICMP is a coneectionless,
it is used for control and signaling purposes.

on top comes the application protocol . this defines the specific
messages and data formats sent and understood by the applications
running at each end of the communication.

modern piston aero-engines

piston engines today are mainly used to power the vast numbers of
light aircraft and microlights , as well as crop sprayers and
crop-dusters, small helicopters, and fire bombers.virtually all
heavier aircraft are now powered by by jet engines. modern piston
aero-engines work on the same basic principles as the engine used by
the Wright brothers in the first powered flight in 1903. however,
today,s engines are more sophisticated than earlier engines. for
example , modern aero- engines may use a two stroke or a four stroke
combustion cycle : they may have from one to nine air – or water
cooled cylinders, which may be arranged horizontally , in a line , in
v formation or radially :and they may drive the aircraft,s propeller
either directly or through a reduction gearbox.