Poulose Jacob, K; Dr. Sridhar, C S(Cochin University of Science & Technology, 1991)
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Abstract:
One of the fastest expanding areas of computer exploitation
is in embedded systems, whose prime function is not that of
computing, but which nevertheless require information
processing in order to carry out their prime function.
Advances in hardware technology have made multi
microprocessor systems a viable alternative to uniprocessor
systems in many embedded application areas.
This thesis reports the results of investigations carried out
on multi microprocessors oriented towards embedded
applications, with a view to enhancing throughput and
reliability.
An ideal controller for multiprocessor operation is developed
which would smoothen sharing of routines and enable more
powerful and efficient code I data interchange. Results of
performance evaluation are appended.A typical application scenario is presented, which calls for
classifying tasks based on characteristic features that were
identified. The different classes are introduced along with
a partitioned storage scheme. Theoretical analysis is also
given.
A review of schemes available for reducing disc access time
is carried out and a new scheme presented. This is found to
speed up data base transactions in embedded systems.
The significance of software maintenance and adaptation in
such applications is highlighted. A novel scheme of
prov1d1ng a maintenance folio to system firmware is
presented, alongwith experimental results.
Processing reliability can be enhanced if facility exists to
check if a particular instruction in a stream is appropriate.
Likelihood of occurrence of a particular instruction would be
more prudent if number of instructions in the set is less. A
new organisation is derived to form the basement for further
work. Some early results that would help steer the course of
the work are presented.
Description:
Department of Electronics,Cochin University of Science and Technology
Ramakrishnan, K; Dr. Balakrishnan, K G(Cochin University of Science & Technology, 1991)
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Abstract:
Remote Data acquisition and analysing systems
developed for fisheries and related environmental studies
have been reported. It consists of three units. The first
one namely multichannel remote data acquisition system is
installed at the remote place powered by a rechargeable
battery. It acquires and stores the 16 channel environmental
data on a battery backed up RAM. The second unit
called the Field data analyser is used for insitue display
and analysis of the data stored in the backed up RAM. The
third unit namely Laboratory data analyser is an IBM
compatible PC based unit for detailed analysis and interpretation
of the data after bringing the RAM unit to the
laboratory. The data collected using the system has been
analysed and presented in the form of a graph. The system
timer operated at negligibly low current, switches on the
power to the entire remote operated system at prefixed time
interval of 2 hours.Data storage at remote site on low power battery
backedupRAM and retrieval and analysis of data using PC are
the special i ty of the system. The remote operated system takes about 7 seconds including the 5 second stabilization
time to acquire and store data and is very ideal for remote
operation on rechargeable bat tery. The system can store
16 channel data scanned at 2 hour interval for 10 days on
2K backed up RAM with memory expansion facility for 8K RAM.
Description:
Department of Electronics,
Cochin University of Science and Technology
Ravindranathan, S; Dr.Unnikrishnan, A(Cochin University of Science & Technology, October , 1991)
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Abstract:
Neural Network has emerged as the topic of the day.
The spectrum of its application is as wide as from ECG noise
filtering to seismic data analysis and from elementary
particle detection to electronic music composition. The
focal point of the proposed work is an application of a
massively parallel connectionist model network for detection
of a sonar target. This task is segmented into: (i) generation of training patterns from sea noise that
contains radiated noise of a target, for teaching the
network;(ii) selection of suitable network topology and learning
algorithm and (iii) training of the network and its subsequent testing
where the network detects, in unknown patterns applied
to it, the presence of the features it has already
learned in. A three-layer perceptron using backpropagation
learning is initially subjected to a recursive training
with example patterns (derived from sea ambient noise with
and without the radiated noise of a target). On every
presentation, the error in the output of the network is
propagated back and the weights and the bias associated with
each neuron in the network are modified in proportion to
this error measure. During this iterative process, the network converges and extracts the target features which get
encoded into its generalized weights and biases.In every unknown pattern that the converged
network subsequently confronts with, it searches for the
features already learned and outputs an indication for their
presence or absence. This capability for target detection is
exhibited by the response of the network to various test
patterns presented to it.Three network topologies are tried with two
variants of backpropagation learning and a grading of the
performance of each combination is subsequently made.
Description:
Department of Electronics, Cochin University of Science and Technology
Joseph, P M; Dr.Saseendran Pillai, P R(Cochin University of Science & Technology, May , 1992)
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Abstract:
Systems which employ underwater acoustic energy
for observation or communication are called sonar systems. The active and passive sonars are the two
types of systems used for the detection and localisation
of targets in underwater. Active sonar involves the
transmission of an acoustic signal which, when reflected
from a target, provides the sonar receiver with a basis
for the detection and estimation. Passive sonar bases
its detection and estimation on sounds which emanate
from the target itself--Machinery noise, flow noise,
transmission from its own active sonar etc.Electroacoustic transducers are used in sonar
systems for the transmission and detection of acoustic
energy. The transducer which is used for the transmission
of acoustic energy is called projector and the
one used for reception is called hydrophone. Since a
single transducer is not sufficient enough for long
range and directional transmission, a properly distributed
array of transducers are to be used [9-11].The need and requirement for spatial processing
to generate the most favourable directivity patterns for
transducer systems used in underwater applications have
already been analysed by several investigators [12-21].The desired directivity pattern can be either generated
by the use of suitable focussing techniques or by an
array of non-directional sensor elements, whose arrangements,
spacing and the mode of excitation provide the
required radiation pattern or by the combination of
these.While computing
that
the directivity pattern, it is
assumed strength of the elements are
unaffected by
the
the
source
acoustic pressure at each source.
However, in closely packed a r r a y s , the acoustic interaction
effects experienced among the elements will
modify the behaviour of individual elements and in turn
will reduce the acoust ic source leve 1 wi t h respect to
the maximum t heoret i cal va 1ue a s well as degrade the
beam pa t tern. Th i s ef fect shou 1d be reduced in systems
that are intended to generate high acoustic power output
and unperturbed beam patterns [2,22-31].The work herein presented includes an approach
for designing efficient and well behaved underwater
transd~cer arrays, taking into account the acoustic
interaction effect experienced among the closely packed
multielement arrays.Architectural modifications
reducing the interaction effect
different radiating apertures.
Description:
Department of Electronics, Cochin University
of Science and Technology.