Sunandakumari,V M; Dr.Ramanujam, N(Cochin University of Science And Technology, May , 1988)
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Abstract:
During recent years, the theory of differential inequalities has been extensively used to discuss singular perturbation problems and method of lines to partial differential equations. The present thesis deals with some differential inequality theorems and their applications to singularly perturbed initial value problems, boundary value problems for ordinary differential equations
in Banach space and initial boundary value problems for parabolic differential equations. The method of lines to parabolic and elliptic differential equations are also dealt The thesis is organised into nine chapters
Description:
Department of mathematics, Cochin University of Science And Technology
Sajan, D George; Achamma, Kurian; Martin, Lase; Nampoori, V P N; Vallabhan, C P G(SPIE, 2001)
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Abstract:
An open cell photoacoustic configuration has been employed to evaluate the thermal diffusivity of pure InP as well as InP doped with sulphur and iron. Chopped optical radiation at 488 nm from an Ar-ion laser has been used to excite photoacoustic signals which been detected by a sensitive electret microphone. Thermal diffusivity value have been calculated from phase versus chopping frequency plots. Doped sample are found to show a reduced value for thermal diffusivity in comparison with intrinsically pure sample. The results have been interpreted in terms of the mechanisms of heat generation and transmission in semiconductors.
Sugunan, S; Suja, H; Sanjay, G; Joseph, L K; Nampoori, V P N; Radhakrishnan, P(Taylor & Francis, April 1, 2009)
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Abstract:
Thermal diffusivity (TD) measurements were performed on some industrially
important dyes – auramine O (AO), malachite green and methylene blue (MB) –
adsorbed K-10 montmorillonites using photoacoustic method. The TD value for
the dye-adsorbed clay mineral was observed to change with a variation in dye
concentration. The contribution of the dye towards TD was also determined. The
repeatedly adsorbed samples with MB and AO exhibited a lower TD than the
single-adsorbed samples. TD values of sintered MB samples were also obtained
experimentally. These sintered samples exhibit a higher TD, although they show
a trend similar to that of non-sintered pellets. A variation in dye concentration
and sintering temperature can be used for tuning the TD value of the clay mineral
to the desired level
Description:
Philosophical Magazine
Vol. 89, No. 10, 1 April 2009, 895–905
Joseph, L K; Sanjay, G; Suja, H; Sugunan, S; Nampoori, V P N; Radhakrishnan, P(Taylor & Francis, April 1, 2009)
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Abstract:
Thermal diffusivity (TD) measurements were performed on some industrially
important dyes – auramine O (AO), malachite green and methylene blue (MB) –
adsorbed K-10 montmorillonites using photoacoustic method. The TD value for
the dye-adsorbed clay mineral was observed to change with a variation in dye
concentration. The contribution of the dye towards TD was also determined. The
repeatedly adsorbed samples with MB and AO exhibited a lower TD than the
single-adsorbed samples. TD values of sintered MB samples were also obtained
experimentally. These sintered samples exhibit a higher TD, although they show
a trend similar to that of non-sintered pellets. A variation in dye concentration
and sintering temperature can be used for tuning the TD value of the clay mineral
to the desired level.
Annieta, Philip K; Lyjo, Joseph K; Litty, Irimpan M; Bindu, Krishnan; Radhakrishnan, P; Nampoori, V P N; Raghu, Natarajan(WILEY-VCH Verlag, 2007)
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Abstract:
Thermal characterization of alumina–zirconia and zirconia ceramic tapes using a photoacoustic technique is presented. A transmission-mode geometry is employed for the measurement of thermal diffusivity while a reflection-mode geometry is used for the measurement of thermal effusivity. In both these geometries, the same open photoacoustic cell is used. From the measured values of thermal diffusivity and thermal effusivity, the thermal conductivity value has also been evaluated.
Anantharaman, M R; V P N Nampoori; Radhakrishnan, P; Girijavallabhan, C P; Sajan, D George; Saravanan, S; Venkatachalam, S(Physical Review, American Physical Society, June 8, 2004)
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Abstract:
Thermal diffusivity of the composites of camphor sulphonic acid (CSA) doped polyaniline (PANI) and its
composites with cobalt phthalocyanine (CoPc) has been measured using open cell photoacoustic technique.
Analysis of the data shows that the effective thermal diffusivity value can be tuned by varying the relative
volume fraction of the constituents. It is seen that polaron assisted heat transfer mechanism is dominant in CSA
doped PANI and these composites exhibit a thermal diffusivity value which is intermediate to that of CSA
doped PANI and CoPc. The results obtained are correlated with the electrical conductivity and hardness
measurements carried out on the samples
Girijavallabhan, C P; Radhakrishnan, P; Nampoori, V P N; Sajan, D George; Saravanan, S; Venkatachalam, S(Physical Review, American Physical Society, June 8, 2004)
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Abstract:
Thermal diffusivity of the composites of camphor sulphonic acid (CSA) doped polyaniline (PANI) and its
composites with cobalt phthalocyanine (CoPc) has been measured using open cell photoacoustic technique.
Analysis of the data shows that the effective thermal diffusivity value can be tuned by varying the relative
volume fraction of the constituents. It is seen that polaron assisted heat transfer mechanism is dominant in CSA
doped PANI and these composites exhibit a thermal diffusivity value which is intermediate to that of CSA
doped PANI and CoPc. The results obtained are correlated with the electrical conductivity and hardness
measurements carried out on the samples.
Nampoori, V P N; Radhakrishnan, P; Girijavallabhan, C P; Sajan, D George(Journal of Physics D : Applied Physics, Institute of Physics Publishing, April 2, 2003)
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Abstract:
An open photoacoustic cell operating in the low range of chopping
frequency has been employed to evaluate the thermal diffusivity values of
intrinsic InP and InP doped with S, Sn and Fe. The experimental set-up is
calibrated by the evaluation of thermal diffusivity value of pure Si and
GaAs. The present investigation shows that doped samples show a reduced
value for thermal diffusivity compared to intrinsic sample. From the
analysis of data it is also seen that nature of dopant clearly influences the
thermal diffusivity value of semiconductors. The results are explained in
terms of phonon assisted heat transfer mechanism in semiconductors
Girijavallabhan, C P; Radhakrishnan, P; V P N Nampoori; Sajan, D George(Journal of Physics D : Applied Physics, Institute of Physics Publishing, April 2, 2003)
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Abstract:
An open photoacoustic cell operating in the low range of chopping
frequency has been employed to evaluate the thermal diffusivity values of
intrinsic InP and InP doped with S, Sn and Fe. The experimental set-up is
calibrated by the evaluation of thermal diffusivity value of pure Si and
GaAs. The present investigation shows that doped samples show a reduced
value for thermal diffusivity compared to intrinsic sample. From the
analysis of data it is also seen that nature of dopant clearly influences the
thermal diffusivity value of semiconductors. The results are explained in
terms of phonon assisted heat transfer mechanism in semiconductors
Radhakrishnan, P; V P N Nampoori; Girijavallabhan, C P; Sajan, D George(Journal of Physics D : Applied Physics, Institute of Physics Publishing, April 2, 2003)
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Abstract:
An open photoacoustic cell operating in the low range of chopping
frequency has been employed to evaluate the thermal diffusivity values of
intrinsic InP and InP doped with S, Sn and Fe. The experimental set-up is
calibrated by the evaluation of thermal diffusivity value of pure Si and
GaAs. The present investigation shows that doped samples show a reduced
value for thermal diffusivity compared to intrinsic sample. From the
analysis of data it is also seen that nature of dopant clearly influences the
thermal diffusivity value of semiconductors. The results are explained in
terms of phonon assisted heat transfer mechanism in semiconductors
Sugunan, S; Nampoori, V P N; Radhakrishnan, P; Sanjay, G; Suja, H; Lyjo, Joseph K(Elsevier, June 28, 2008)
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Abstract:
Thermal diffusivity (TD) measurement on commercial K-10 and KSF montmorillonites was carried out by
photoacoustic technique. The TD of the montmorillonites after methylene blue adsorption changed with the
dye concentration. The repeatedly adsorbed samples showed a lesser TD than the single adsorbed samples.
After methylene blue adsorption the acid leached K-10 samples showed well defined changes in TD when
compared to the ordered KSF samples
Nampoori, V P N; Lyjo, Joseph K; Suja, H; Sanjay, G; Sugunan, S; Radhakrishnan, P(Elsevier, Journal of Applied Clay Science, June 28, 2008)
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Abstract:
Thermal diffusivity (TD) measurement on commercial K-10 and KSF montmorillonites was carried out by
photoacoustic technique. The TD of the montmorillonites after methylene blue adsorption changed with the
dye concentration. The repeatedly adsorbed samples showed a lesser TD than the single adsorbed samples.
After methylene blue adsorption the acid leached K-10 samples showed well defined changes in TD when
compared to the ordered KSF samples.
Sajan, D George; Rajesh, Komban; Warrier, K G K; Radhakrishnan, P; Nampoori, V P N; Vallabhan, C P G(Taylor & Francis, February , 2010)
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Abstract:
A laser-induced photoacoustic technique was employed to investigate
thermal transport through nanocrystalline CePO4 samples prepared via the
sol–gel route. Evaluation of thermal diffusivity was carried out using the
one-dimensional model of Rosencwaig and Gersho for the reflection
configuration of the photoacoustic method. Structural analyses of samples
revealed that they are nanoporous in nature, possessing micron-sized
grains. Analysis of results shows that thermal diffusivity value varies with
sintering temperature. Results are explained in terms of the variation in
porosity with sintering temperature and the effects of various scattering
mechanisms on the propagation of phonons through the nanoporous
ceramic matrix. Further analyses confirm that apart from porosity, grain
boundary resistance and interface thermal resistance influence the effective
value of thermal diffusivity of the samples under investigation.
Sunil,K Narayanankutty(Elsevier Science Publishers Ltd., August 29, 1991)
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Abstract:
The thermal degradation of short kevlar fibre-thermoplastic polyurethane
(TPU) composites has been studied by Thermogravimetric Analysis (TGA)
and Differential Scanning Calorimetry (DSC). TGA showed that the thermal
degradation of TPU takes place in two steps with peak maxima (T1max and
T2ma,) at 383°C and 448°C, respectively. In the presence of 10-40 phr of short
kevlar fibres, T1_ and T2max were shifted to lower temperatures. The
temperature of onset of degradation was increased from 245 to 255°C at 40
parts per hundred rubber (phr) fibre loading. Kinetic studies showed that the
degradation of TPU and kevlar-TPU composite follows first-order reaction
kinetics. The DSC study showed that there is an improvement in thermal
stability of TPU in the presence of 20 phr of short kevlar fibres.
Sunil,K Narayanankutty(Taylor & Francis Inc., October 28, 2004)
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Abstract:
The thermal properties of short Nylon-6 fiber-reinforced Styrene butadiene rubber
(SBR) composites were studied by Thermogravimetric Analysis (TGA). The effect
of epoxy-based bonding agent on thermal degradation of the gum and the composites
was also studied. The thermal stability of the SBR was enhanced in the presence
of Nylon-6 fibers and the stability of the composites increased in the presence
of bonding agent. The epoxy resin did not significantly change the thermal stability
of SBR gum vulcanizate. Results of kinetic studies showed that the degradation
of SBR and the short nylon fiber-reinforced composites with and without
bonding agents followed first-order kinetics.