Sony, George; Ajai, Kumar; Singh, R K; Nampoori, V P N(American Institute of Physics, 2009)
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Abstract:
The dynamics of plasma plume, formed by the laser-blow-off of multicomponent LiF-C thin film
under various ambient pressures ranging from high vacuum to argon pressure of 3 Torr, has been
studied using fast imaging technique. In vacuum, the plume has ellipsoidal shape. With the increase
in the ambient pressure, sharp plume boundary is developed showing a focusing-like confinement
in the lateral space behavior in the front end, which persists for long times. At higher ambient
pressure (> 10−1 Torr ), structures are developed in the plasma plume due to hydrodynamic
instability/turbulences.
Manju, Mary Joseph; Dr.Chandramohanakumar, N(Cochin University of Science and Technology, October , 2009)
[+]
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Abstract:
The biogeochemistry of mangroves are the least understood ecological properties because of their sediment complexicity due to the tidal influx of allochthonous organic matter and the autochthonous inputs.In order to understand the relative importance of biogeochemical processes,it is necessary not only to characterise and qualify the organic matter but also to identify its major sources .The present study is a preliminary investigation to identify the sources of organic matter in three mangrove systems of Cochin Estuary using fatty acid biomarkers,δ13 C of total organic matter,elemental composition and biochemical composition.
Description:
Department of Chemical Oceanography,Cochin University of Science and
Technology
Poulose Jacob,K; Rekha, James K; Shahana, T K; Sreela Sasi(IEEE, October 30, 2007)
[+]
[-]
Abstract:
In recent years, reversible logic has emerged as one
of the most important approaches for power optimization
with its application in low power CMOS, quantum computing
and nanotechnology. Low power circuits implemented using
reversible logic that provides single error correction – double
error detection (SEC-DED) is proposed in this paper. The
design is done using a new 4 x 4 reversible gate called ‘HCG’
for implementing hamming error coding and detection
circuits. A parity preserving HCG (PPHCG) that preserves
the input parity at the output bits is used for achieving fault
tolerance for the hamming error coding and detection circuits.
Lethakumary,B; Sreedevi, Menon K; Aanandan,C K; Vasudevan, K; Mohanan, P(Microwave and Optical Technology Letters, November 20, 2004)
[+]
[-]
Abstract:
A theoretical analysis of a symmetric T-shaped rnicrostripfed
rectangular microstrip antenna using the finite-difference titnedoniain
(FDTD) method is presented in this paper. The resonant frequency,
return loss, impedance bandwidth, and radiation patterns are
predicted and are in good agreement with the measured results
Poulose Jacob,K; Sonia, Sunny; David, Peter S(IEEE, August 9, 2012)
[+]
[-]
Abstract:
Speech signals are one of the most important means
of communication among the human beings. In this paper, a
comparative study of two feature extraction techniques are
carried out for recognizing speaker independent spoken
isolated words. First one is a hybrid approach with Linear
Predictive Coding (LPC) and Artificial Neural Networks
(ANN) and the second method uses a combination of Wavelet
Packet Decomposition (WPD) and Artificial Neural Networks.
Voice signals are sampled directly from the microphone and
then they are processed using these two techniques for
extracting the features. Words from Malayalam, one of the
four major Dravidian languages of southern India are chosen
for recognition. Training, testing and pattern recognition are
performed using Artificial Neural Networks. Back propagation
method is used to train the ANN. The proposed method is
implemented for 50 speakers uttering 20 isolated words each.
Both the methods produce good recognition accuracy. But
Wavelet Packet Decomposition is found to be more suitable for
recognizing speech because of its multi-resolution
characteristics and efficient time frequency localizations
Description:
Advances in Computing and Communications (ICACC), 2012 International Conference on
Poulose Jacob,K; Supriya, M H; Liny, Varghese(International Journal of Computer Science and Communication, June , 2012)
[+]
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Abstract:
Treating e-mail filtering as a binary text classification problem, researchers have applied several statistical learning
algorithms to email corpora with promising results. This paper examines the performance of a Naive Bayes classifier
using different approaches to feature selection and tokenization on different email corpora
Description:
International Journal of Computer Science and Communication Vol. 3, No. 1, January-June 2012, pp. 81-84
Jiji, K S; Jayadas, N H; Babu, C A(Cochin University Of Science And Technology, May , 2015)
[+]
[-]
Abstract:
Salient pole brushless alternators coupled to IC engines are
extensively used as stand-by power supply units for meeting in-
dustrial power demands. Design of such generators demands high
power to weight ratio, high e ciency and low cost per KVA out-
put. Moreover, the performance characteristics of such machines
like voltage regulation and short circuit ratio (SCR) are critical
when these machines are put into parallel operation and alterna-
tors for critical applications like defence and aerospace demand
very low harmonic content in the output voltage. While designing
such alternators, accurate prediction of machine characteristics,
including total harmonic distortion (THD) is essential to mini-
mize development cost and time.
Total harmonic distortion in the output voltage of alternators
should be as low as possible especially when powering very sophis-
ticated and critical applications. The output voltage waveform
of a practical AC generator is replica of the space distribution of
the
ux density in the air gap and several factors such as shape
of the rotor pole face, core saturation, slotting and style of coil
disposition make the realization of a sinusoidal air gap
ux wave
impossible. These
ux harmonics introduce undesirable e ects on
the alternator performance like high neutral current due to triplen
harmonics, voltage distortion, noise, vibration, excessive heating
and also extra losses resulting in poor e ciency, which in turn
necessitate de-rating of the machine especially when connected
to non-linear loads. As an important control unit of brushless
alternator, the excitation system and its dynamic performance
has a direct impact on alternator's stability and reliability.
The thesis explores design and implementation of an excitation
i
system utilizing third harmonic
ux in the air gap of brushless al-
ternators, using an additional auxiliary winding, wound for 1=3rd
pole pitch, embedded into the stator slots and electrically iso-
lated from the main winding. In the third harmonic excitation
system, the combined e ect of two auxiliary windings, one with
2=3rd pitch and another third harmonic winding with 1=3rd pitch,
are used to ensure good voltage regulation without an electronic
automatic voltage regulator (AVR) and also reduces the total
harmonic content in the output voltage, cost e ectively.
The design of the third harmonic winding by analytic methods
demands accurate calculation of third harmonic
ux density in
the air gap of the machine. However, precise estimation of the
amplitude of third harmonic
ux in the air gap of a machine by
conventional design procedures is di cult due to complex geome-
try of the machine and non-linear characteristics of the magnetic
materials. As such, prediction of the eld parameters by conven-
tional design methods is unreliable and hence virtual prototyping
of the machine is done to enable accurate design of the third har-
monic excitation system.
In the design and development cycle of electrical machines, it is
recognized that the use of analytical and experimental methods
followed by expensive and in
exible prototyping is time consum-
ing and no longer cost e ective. Due to advancements in com-
putational capabilities over recent years, nite element method
(FEM) based virtual prototyping has become an attractive al-
ternative to well established semi-analytical and empirical design
methods as well as to the still popular trial and error approach
followed by the costly and time consuming prototyping. Hence,
by virtually prototyping the alternator using FEM, the important
performance characteristics of the machine are predicted.
Design of third harmonic excitation system is done with the help
of results obtained from virtual prototype of the machine. Third
harmonic excitation (THE) system is implemented in a 45 KVA
ii
experimental machine and experiments are conducted to validate
the simulation results. Simulation and experimental results show
that by utilizing third harmonic
ux in the air gap of the ma-
chine for excitation purposes during loaded conditions, triplen
harmonic content in the output phase voltage is signi cantly re-
duced. The prototype machine with third harmonic excitation
system designed and developed based on FEM analysis proved
to be economical due to its simplicity and has the added advan-
tage of reduced harmonics in the output phase voltage.
Rosamma, Philip; Bright Singh, I S; Manjusha, M; Somnath Pai, S(Inter-Research, September 23, 2005)
[+]
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Abstract:
Fenneropenaeus indicus could be protected from white spot disease (WSD) caused by
white spot syndrome virus (WSSV) using a formalin-inactivated viral preparation (IVP) derived from
WSSV-infected shrimp tissue. The lowest test quantity of lyophilized IVP coated onto feed at 0.025 g–1
(dry weight) and administered at a rate of 0.035 g feed g–1 body weight d–1 for 7 consecutive days was
sufficient to provide protection from WSD for a short period (10 d after cessation of IVP administration).
Shrimp that survived challenges on the 5th and 10th days after cessation of IVP administration
survived repeated challenges although they were sometimes positive for the presence of WSSV
by a polymerase chain reaction (PCR) assay specific for WSSV. These results suggest that F. indicus
can be protected from WSD by simple oral administration of IVP
Description:
DISEASES OF AQUATIC ORGANISMS,Vol. 66: 265–270, 2005
Beatrice,Amar; Rosamma, Philip(MARINE BIOLOGY, MICROBIOLOGY AND BIOCHEMISTRY, SCHOOL OF MARINE SCIENCES, 2001)
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Abstract:
This work envisages the fermentation of prawn shell waste into a more nutritious product with simpler components for application as a feed ingredient in aquaculture. This product would be a rich source of protein along with chitin, minerals, vitamins and N-acetyl glucosamine. A brief description of the various processing (chemical and bioprocess) methods employed for chitin, chitosan and single sell protein preparations from shell waste. It deals with the isolation of micro flora associated with prawn shell degradation. It describes the methods adopted for fermentation of prawn shell degradation and fermentation of prawn shell waste with the selected highly chitinoclastic strains. The comparison of SSF and SmF for each selected strain in terms of enrichment of protein, lipid and carbohydrate in the fermented product was done. Detailed analysis of product quality is discussed. The feed for mulation and feeding experiment explained in detail. Statistical analysis of various biogrowth parameters was done with Duncan’s multiple range test. Very briefly explains 28 days of feeding experiment. A method for the complete utilization of shell waste explains with the help of experiments.
Nandakumar, M P; Dr.Chandrasekaran,M(Cochin University Of Science And Technology, January 17, 1991)
[+]
[-]
Abstract:
Recently’ recognition cnf immobilization ‘technology
for the rapid conversion of several substrates into metabolites
and repeated reuse of the biocatalysts have drawn the
attention of the fermentation scientists and technologists to
try these new technologies for the rapid production of pnxkmt
and enhancement of the efficiencies of the systems
Hence in the present study rice was selected,as a
substrate since it is a rich source of starch, available and
cultivated throughout the year almost in all part of our
country. Rice although known for its use as a staple food in
many forms as rice, idli, dosai etc., has not been used in
industry extensively. However, it ii; a potential resource
for’ the production of alcohol, high protein food anui for
sugar and sugar syrups as it is evidenced by the few reports
mentioned in the review of literature.
Of the several microorganisms available, Bacillus sp,
is a known candidate for the production of amylases. Hence
in the present study Bacillus sp, was desired for its known
efficiencies in starch conversion
Description:
Department
of Applied Chemistry, Cochin University of Science and
Technology
Swapna, Nair S; Rajesh, S; Abraham, V S; Anantharaman, M R(Springer, April , 2011)
[+]
[-]
Abstract:
Ferrofluids belonging to the series, Ni x Fe1-x Fe2O4 and Zn x Fe1-x Fe2O4, were synthesized using cold co-precipitation. Liquid films of these ferrofluids were prepared by encapsulating the ferrofluids in between two optically smooth and ultrasonically cleaned glass plates. Magnetic field induced laser transmission through these ferrofluid films has been investigated. Magnetic field values can be calibrated in terms of output laser power in the low field region in which the variation is linear. This set up can be used as a cheap optical gaussmeter in the low field regime. Using the same set-up, the saturation magnetization of the sample used can also be calculated with a sample that is pre-characterized. Hence both magnetization of the sample, as well as applied magnetic field can be sensed and calculated with a precalibrated sample.
Radhakrishnan, P; Nampoori, V P N; Vallabhan, C P G(Indian Journal of Physics, 1992)
[+]
[-]
Abstract:
A simple fiber optic concentration sensor based on the coupling of light f rom one
fiber to another through a solution is discussed. The operational characteristics of the sensor are
illustrated by taking the solutions of potassium permanganate and fast green dye as samples.The extrinsic type sensor described here shows linearity at lower concentrations.
Rajesh, M; Geetha, K; Sheeba, M; Radhakrishnan, P; Vallabhan, C P G; Nampoori, V P N(Elsevier, May , 2006)
[+]
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Abstract:
A simple, effective and inexpensive fiber optic sensor for investigating the setting characteristics of various grades of cement is described. A finite length of unsheathed multimode optical fiber laid inside the cement mix, is subjected to stress during the setting process. The microbends created on the fiber due to this stress directly influence the intensity of light propagating through the fiber. Continuous monitoring of such variations in the light output transmitted through the fiber gives a clear measure of the setting characteristics of the cement mix, thus providing a simple and elegant technique of great practical importance in the field of civil engineering. The smart fiber optic sensor described above can be incorporated into a building during the construction process itself so that continuous monitoring of the deterioration process for the entire life time of the building can be carried out.
Radhakrishnan, P; Nampoori, V P N; Girijavallabhan, C P; Shelly John, M(Measurement Science and Technology, UK, November 12, 1998)
[+]
[-]
Abstract:
A novel sensing technique for the in situ monitoring of the rate of pulsed laser
deposition (PLD) of metal thin films has been developed. This optical fibre based sensor
works on the principle of the evanescent wave penetration of waveguide modes into the
uncladded portion of a multimode fibre. The utility of this optical fibre sensor is
demonstrated in the case of PLD of silver thin films obtained by a Q-switched Nd:YAG laser
which is used to irradiate a silver target at the required conditions for the preparation of thin
films. This paper describes the performance and characteristics of the sensor and shows how
the device can be used as an effective tool for the monitoring of the deposition rate of silver
thin films. The fibre optic sensor is very simple, inexpensive and highly sensitive compared
with existing techniques for thin film deposition rate measurements
Nampoori, V P N; Radhakrishnan, P; Girijavallabhan, C P; Shelly John, M(Measurement Science and Technology, UK, November 12, 1998)
[+]
[-]
Abstract:
A novel sensing technique for the in situ monitoring of the rate of pulsed laser
deposition (PLD) of metal thin films has been developed. This optical fibre based sensor
works on the principle of the evanescent wave penetration of waveguide modes into the
uncladded portion of a multimode fibre. The utility of this optical fibre sensor is
demonstrated in the case of PLD of silver thin films obtained by a Q-switched Nd:YAG laser
which is used to irradiate a silver target at the required conditions for the preparation of thin
films. This paper describes the performance and characteristics of the sensor and shows how
the device can be used as an effective tool for the monitoring of the deposition rate of silver
thin films. The fibre optic sensor is very simple, inexpensive and highly sensitive compared
with existing techniques for thin film deposition rate measurements.
Sivasankara Pillai,V N; Radhakrishnan, P; Nampoori, V P N; Girijavallabhan, C P; Suresh, Kumar P(Journal of Optics : A Pure and Applied Optics, March 8, 2002)
[+]
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Abstract:
A fibre optic technique for detecting trace amounts of nitrite compounds in
water is described. The off-line fibre optic sensor outlined here is based on
evanescent field absorption in a test solution formed by the reaction of nitrite
compounds in water with suitable chemical reagents. A short unclad portion
of a plastic clad silica fibre acts as the sensing region. The experimental
results clearly establish the usefulness of the present technique for detecting
very low concentrations of the order of 1 ppb (parts per billion) of nitrite
compounds with a large dynamic range of 1–1000 ppb. Such a high
sensitivity enables the present device to be used for measuring the nitrite
content in drinking water.