Premnath, R; Dr. Madhu, G(Cochin University of Science & Technology, November , 2011)
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Abstract:
Data centre is a centralized repository,either physical or virtual,for the storage,management and dissemination of data and information organized around a particular body and nerve centre of the present IT revolution.Data centre are expected to serve uniinterruptedly round the year enabling them to perform their functions,it consumes enormous energy in the present scenario.Tremendous growth in the demand from IT Industry made it customary to develop newer technologies for the better operation of data centre.Energy conservation activities in data centre mainly concentrate on the air conditioning system since it is the major mechanical sub-system which consumes considerable share of the total power consumption of the data centre.The data centre energy matrix is best represented by power utilization efficiency(PUE),which is defined as the ratio of the total facility power to the IT equipment power.Its value will be greater than one and a large value of PUE indicates that the sub-systems draw more power from the facility and the performance of the data will be poor from the stand point of energy conservation. PUE values of 1.4 to 1.6 are acievable by proper design and management techniques.Optimizing the air conditioning systems brings enormous opportunity in bringing down the PUE value.The air conditioning system can be optimized by two approaches namely,thermal management and air flow management.thermal management systems are now introduced by some companies but they are highly sophisticated and costly and do not catch much attention in the thumb rules.
Description:
Division of Safety and Fire Engineering,School of Engineering,Cochin University of Science and Technology
A dynamical system with a damping that is quadratic in velocity is converted into the Hamiltonian format using a nonlinear transformation. Its quantum mechanical behaviour is then analysed by invoking the Gaussian effective potential technique. The method is worked out explicitly for the Duffing oscillator potential.
Bybi, P C; Jitha, B; Aanandan, C K; Vasudevan, K; Mohanan, P; Gijo, Augustin(Antennas and Wireless Propagation Letters, IEEE, 2008)
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Abstract:
A compact, planar, wideband antenna designed by modifying the coplanar waveguide is presented in this letter. The proposed antenna finds a wide range of applications including advanced wireless systems (AWS), DCS-1800, DCS-1900/PCS/PHS, WiBro, BlueTooth/WLAN/WiBree/ZigBee, DMB, Global Star Satellite Phones, and digital cordless phones. Wide bandwidth > 75% centered at 2.50 GHz, quasi-omnidirectional radiation coverage along with moderate gain and efficiency are the salient features of the antenna. A prototype fabricated on a substrate with dielectric constant 4.4 and thickness 1.6 mm occupies an area of (31times 64) mm2. Details of antenna design and discussions on the effect of various antenna parameters on the radiation characteristics are presented.
Viswanath C Narayanan; Krishnamoorthy,A(Department of Mathematics, 2005)
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Abstract:
Application of Queueing theory in areas like Computer networking, ATM facilities, Telecommunications and to many other numerous situation made people study Queueing models extensively and it has become an ever expanding branch of applied probability. The thesis discusses Reliability of a ‘k-out-of-n system’ where the server also attends external customers when there are no failed components (main customers), under a retrial policy, which can be explained in detail. It explains the reliability of a ‘K-out-of-n-system’ where the server also attends external customers and studies a multi-server infinite capacity Queueing system where each customer arrives as ordinary but can generate into priority customer which waiting in the queue. The study gives details on a finite capacity multi-server queueing system with self-generation of priority customers and also on a single server infinite capacity retrial Queue where the customer in the orbit can generate into a priority customer and leaves the system if the server is already busy with a priority generated customer; else he is taken for service immediately. Arrival process is according to a MAP and service times follow MSP.
Chandran, A R; Gopikrishna, M; Aanandan, C K; Mohanan, P; Vasudevan, K(IEEE, September 28, 2006)
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Abstract:
Effective use of fractal-based metallo-dielectric structures for enhancing the radar cross-section (RCS) of dihedral corner reflectors is reported. RCS enhancement of about 30 dBsm is obtained for corner reflectors with corner angles other than 90deg. This may find application in remote sensing and synthetic aperture radar.
Nisha, V S; Rani, Joseph(Dept. of Polymer Science and Rubber Technology, May , 2006)
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Abstract:
The present work is to impart radiopacity in various natural polymers like chitosan, natural rubber and derivatives of chitosan and to characterize it. This thesis collated the radiopaque properties of these radiopaque polymers and various technological applications in the medical field. The applications of radiopaque polymers leads to an exploitation of radiopaque properties like X-ray visibility, optical density, effective atomic number, attenuation coefficient of biopolymers like chitosan, chitosan formate, chitosan acetate, carboxy methyl chitosan and natural rubber. The radiopaqe properties of these materials highly depend upon the size, shape, amount of radiopacifier and crystallinity of the radiopaque material. Radiopaque chitosan microspheres were prepared by cross linking with glutaraldehyde followed by the encapsulation of barium sulpahte. The effect of different emulsion systems on the morphology of chitosan microspheres were studied. The study concentrates radiopaque natural rubber for shielding applications. It reveals that to improve the particle size, morphology and crystalline phase of the zinc oxide particles, a novel method for the preparation of zinc oxide is adopted. A detailed radiopacity study was done in natural rubber containing 100phr precipitated zinc oxide prepared from different zinc salts. One of the significant findings of this investigation is that NR vulcanizates containing precipitated zinc oxide (from zinc acetate) shows higher attenuation coefficient. These interesting findings reveal the applications of these natural radiopaque systems in various fields like surgical tools, medical tubings, catheters, radiation shielding,etc.
V P N Nampoori; Girijavallabhan, C P; Radhakrishnan, P; Thomas, K J; Sheeba, M(Journal of Optics A: Pure and Applied Optics, March 27, 2008)
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Abstract:
Polymethyl methacrylate (PMMA) optical fibres are fabricated by a preform drawing process.
The Raman spectra of PMMA fibres are recorded using a diode pumped solid state laser
emitting at 532 nm and a CCD-spectrograph in the 400–3800 cm−1 range. The variation of the
Raman intensity with the length of the optical fibre is studied. Investigations are carried out on
the variation of FWHM of the Raman peak at 2957 cm−1 with the length of the optical fibre and
pump power. The differential scattering cross section and gain coefficient of the Raman peak at
2957 cm−1 in PMMA are calculated in relation to that of toluene
Radhakrishnan, P; Girijavallabhan, C P; V P N Nampoori; Thomas, K J; Sheeba, M(Journal of Optics A: Pure and Applied Optics, March 27, 2008)
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Abstract:
Polymethyl methacrylate (PMMA) optical fibres are fabricated by a preform drawing process.
The Raman spectra of PMMA fibres are recorded using a diode pumped solid state laser
emitting at 532 nm and a CCD-spectrograph in the 400–3800 cm−1 range. The variation of the
Raman intensity with the length of the optical fibre is studied. Investigations are carried out on
the variation of FWHM of the Raman peak at 2957 cm−1 with the length of the optical fibre and
pump power. The differential scattering cross section and gain coefficient of the Raman peak at
2957 cm−1 in PMMA are calculated in relation to that of toluene.
Gijo, Augustin; Shynu, S V; Mohanan, P; Anandan, C K; Vasudevan, K(John Wiley & Sons, November , 2006)
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Abstract:
A novel fixed frequency beam scanning microstrip leaky wave antenna is reported. The beam scanning at fixed frequency is achieved by reactive loading. Simulation and measured results shows frequency scanability of 80° as well as fixed frequency beam steering of 68° over the −10 dB impedance band of 4.56–5.06 GHz.
Supriya, M H; Dr.Pillai, P R S(Cochin University of Science & Technology, October , 2007)
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Abstract:
This thesis addresses one of the emerging topics in Sonar Signal Processing.,viz.the implementation of a target classifier for the noise sources in the ocean, as the operator assisted classification turns out to be tedious,laborious and time consuming.In the work reported in this thesis,various judiciously chosen components of the feature vector are used for realizing the newly proposed Hierarchical Target Trimming Model.The performance of the proposed classifier has been compared with the Euclidean distance and Fuzzy K-Nearest Neighbour Model classifiers and is found to have better success rates.The procedures for generating the Target Feature Record or the Feature vector from the spectral,cepstral and bispectral features have also been suggested.The Feature vector ,so generated from the noise data waveform is compared with the feature vectors available in the knowledge base and the most matching pattern is identified,for the purpose of target classification.In an attempt to improve the success rate of the Feature Vector based classifier,the proposed system has been augmented with the HMM based Classifier.Institutions where both the classifier decisions disagree,a contention resolving mechanism built around the DUET algorithm has been suggested.
Description:
Departement of Electronics,Cochin University of Science and Technology
Raghu, O; Dr. Jacob, Philip(Cochin University of Science and Technology, February , 2007)
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Abstract:
Among the large number of photothcrmal techniques available, photoacoustics
assumes a very significant place because of its essential simplicity and the variety of
applications it finds in science and technology. The photoacoustic (PA) effect is the
generation of an acoustic signal when a sample, kept inside an enclosed volume, is
irradiated by an intensity modulated beam of radiation. The radiation absorbed by the
sample is converted into thermal waves by nonradiative de-excitation processes. The
propagating thermal waves cause a corresponding expansion and contraction of the
gas medium surrounding the sample, which in tum can be detected as sound waves by
a sensitive microphone. These sound waves have the same frequency as the initial
modulation frequency of light. Lock-in detection method enables one to have a
sufficiently high signal to noise ratio for the detected signal. The PA signal amplitude
depends on the optical absorption coefficient of the sample and its thermal properties.
The PA signal phase is a function of the thermal diffusivity of the sample.Measurement of the PA amplitude and phase enables one to get valuable information
about the thermal and optical properties of the sample.
Since the PA signal depends on the optical and thennal properties of the
sample, their variation will get reflected in the PA signal. Therefore, if the PA signal
is collected from various points on a sample surface it will give a profile of the
variations in the optical/thennal properties across the sample surface. Since the optical
and thermal properties are affected by the presence of defects, interfaces, change of
material etc. these will get reflected in the PA signal. By varying the modulation
frequency, we can get information about the subsurface features also. This is the basic
principle of PA imaging or PA depth profiling. It is a quickly expanding field with
potential applications in thin film technology, chemical engineering, biology, medical
diagnosis etc. Since it is a non-destructive method, PA imaging has added advantages
over some of the other imaging techniques. A major part of the work presented in this
thesis is concemed with the development of a PA imaging setup that can be used to
detect the presence of surface and subsmface defects in solid samples.Determination of thermal transport properties such as thermal diffusivity,
effusivity, conductivity and heat capacity of materials is another application of
photothennal effect. There are various methods, depending on the nature of the
sample, to determine these properties. However, there are only a few methods
developed to determine all these properties simultaneously. Even though a few
techniques to determine the above thermal properties individually for a coating can be
found in literature, no technique is available for the simultaneous measurement of
these parameters for a coating. We have developed a scanning photoacoustic technique that can be used to determine all the above thermal transport properties
simultaneously in the case of opaque coatings such as paints. Another work that we
have presented in this thesis is the determination of thermal effusivity of many bulk
solids by a scanning photoacoustic technique. This is one of the very few methods
developed to determine thermal effiisivity directly.
Description:
Dept.of Instrumentation,Cochin University of Science and Technology
Achamma, Kurian; Unnikrishnan, K P; Thomas Lee, S; V P N Nampoori; Vallabhan, C P G(Taylor & Francis, 2002)
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Abstract:
A sensitive method based on the principle of photothermal phenomena to realize optical
logic gates is presented. A dual beam thermal lens method using low power cw lasers in a
dye-doped polymer can be very effectively used as an alternate technique to perform the
logical function such as NAND, AND and OR.
Shynu,S V; Gijo,Augustin; Aanandan,C K; Mohanan,P; Vasudevan,K(Microwave and Optical Technology Letters, February 4, 2005)
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Abstract:
A novel reconfigurable, single feed, dual frequency, dualpolarized
operation of a hexagonal slot-loaded square mwrostrip antenna
is presented in this paper. A pin diode incorporated in the slot is
used to switch the two operating frequencies considerably, without significantly
affecting the radiation characteristics and gain. The proposed
antenna provides a size reduction up to 61% and 26% Jor the two resonating
frequencies, compared to standard rectangular patches. This design
also gives considerable bandwidth up to 3.3% and 4.27%, for the two
frequencies with a low operating frequency ratio