| Abstract: | A navel ultra-thin radar-absorbing material (RAM) using metanwterials is presented and the absorption performance is examined. Due to the high-impedance property of the metamalerials. the thickness of the RAM is about several tenths of the center wavelength of the absorption band, which is considerably thinner than conventional absorbers. The absorption bandwidth of the RAM is about several hundred megahertz |
| URI: | http://dyuthi.cusat.ac.in/purl/1417 |
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| A novel radar-a ... based on EBG structure.PDF | (907.3Kb) |
| Abstract: | The main objectives of the present investigation were to evaluate the qualitative and quantitative distribution of natural cyanobacterial population and their ecobiological properties along the Cochin estuary and their application in aquaculture systems as a nutritional supplement due to their nutrient-rich biochemical composition and antioxidant potential. This thesis presents a detailed account of the distribution of cyanobacteria in Cochin estuary, an assessment of physico-chemical parameters and the nutrients of the study site, an evaluation of the effect of physico-chemical parameters on cyanobacterial distribution and abundance, isolation, identification and culturing of cyanobacteria, the biochemical composition an productivity of cyanobacteria, and an evaluation of the potential of the selected cyanobacteria as antioxidants against ethanol induced lipid peroxidation. The pH, salinity and nutritional requirements were optimized for low-cost production of the selected cyanobacterial strains. The present study provides an insight into the distribution, abundance, diversity and ecology of cyanobacteria of Cochin estuary. From the results, it is evident that the ecological conditions of Cochin estuary support a rich cyanobacterial growth. |
| URI: | http://dyuthi.cusat.ac.in/purl/914 |
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| Dyuthi-T0070.pdf | (4.047Mb) |
| Abstract: | In this paper, we introduce a novel feeding technique for bandwidth enhancement of a rectangular microstrip antenna This antenna offers an impedance bandwidth of 22% without degrading the effciencv. The effect of the feed parameters upon patch characteristics such as resonant frequency, impedance bandwidth, and radiation pattern are studied in detail. The experimental results are verified using the FDTD results |
| URI: | http://dyuthi.cusat.ac.in/purl/1415 |
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| Wideband micros ... using hook-shaped feed.PDF | (1.285Mb) |
| 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 |
| URI: | http://dyuthi.cusat.ac.in/purl/1420 |
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| A reconfigurati ... ntrolled by pin diodes.PDF | (1.097Mb) |
| Abstract: | The present study has been initiated to unravel the distribution of trace metals and its geochemical behavior in the Indian EEZ of the Arabian Sea and Bay of Bengal. Trace metal accumulation in aquatic consumers is of interest to ecologists and environmentalists so as to understand the fate and effect of contaminants in the food web dynamics and the biogeochemical cycling of trace metals. It is well established that oceanic distribution of macronutrients such as nitrate, phosphate and silicate provide critical to biological growth and related geochemical processes. In this study it can be inferred, that there is a need for a better understanding of background informations on trace metal concentrations with respect to space and time and their fluctuations in the Arabian Sea and Bay of Bengal zooplankton. Without a sound knowledge on spatio-temporal fluctuations, it will be impossible to differentiate anthropogenic metal inputs from natural background concentrations with a routine biomonitoring programme. Fe, Cu, Zn, Cd & Pb showed a slight enrichment in zooplankton from the Arabian Sea during spring intermonsoon compared to intermonsoon fall. The relative enrichment of Fe, Cu & Zn in zooplankton from the Arabian Sea during intermonsoon spring than intermonsoon fall was due to favourable bioaccumulation factors of these elements during this season. Nevertheless this study can be looked upon as a starting point for further investigations on these biogeochemically important processes, which are vital in addressing the dynamics of productivity of waters. |
| URI: | http://dyuthi.cusat.ac.in/purl/937 |
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| Dyuthi-T0030.pdf | (5.922Mb) |
| Abstract: | In this paper, microstrip lines magnetically coupled to splitring resonators (SRRs) are conquved to electromagnetic bundgup (EBG) nr,rrostrip lines in terns q/ their stop-heard penjbrnmrnce and dimensions. In bath types o/ trunsmis•siou lines, signal propagation is inhibited in it certain jequency bwuL For EBG microstrip lines, the central frequency of such a forbidden band is determined by the period of the structure, whereas in SRR-hased microstrip lines the position of the frequency gap depends on the quasi-static resonant frequency of the rings. The main relevant conrributiun of this paper is to provide a tuning procedure to control the gap width in SRR microstrip lines, and to show that by using SRRs, device dimensions ale much smaller than those required by EBGs in order to obtain similar stop-banal performance. This has been demonstrated by fill-wave electromagnetic simulations and experimentally verified from the characterization ql two fabricated microstrip lines: one with rectangular SRRs etched on the upper substrate side, and the other with a periodic perturbation cf'strip width. For similar rejection and 1-(;H,. gap width centered at 4.5 Gllz, it has been found that the SRR microstrip line is•,fve times shorter. In addition, no ripple is appreciable in the allowed band for the .SRR-hared structure, whereas due to dispersion, certain mismatch is expected in the EBG prototype. Due to the high-frequency selectivity, controllable gap width, and small dimensions, it is believed that SRR coupled to planar transmission lines can have an actual impact on the design of stop-band filters compatible with planar technology, and can be an alternative to present solutions based on distributed approaches or EBG |
| URI: | http://dyuthi.cusat.ac.in/purl/1421 |
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| Comparison of e ... s stop band structures.PDF | (686.9Kb) |
| Abstract: | A new photopolymerizable recording media is introduced based on poly (vinyl alcohol) and vinyl acetate sensitized with methylene blue. It is observed that this MBPVA/VAc system can be reused a number of times without significant decrease in diffraction efficiency. The PVA-VAc ratio was optimized at 2:1. Diffraction efcienc4y of 6.3% was obtained without any fixing at a dye concentration of 9.3 x 10- mol/l at an exposure of 750mJ/cm2. The material is attractive on account of its reusability. |
| URI: | http://dyuthi.cusat.ac.in/purl/872 |
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| Beena Mary John ... recording...,march2005.PDF | (7.043Mb) |
| Abstract: | nerv5o-HusT s ryescteempto. rTshaer oeb pjercetdiovme oinfa tnhtilsy s ltoucdaytewd ains ttoh ein bvreasitnig aanted tahree rionlveo olvf ehdy ipno tphaanlacrmeiact i5c- fHuTn,c t5i-oHn TaInAd acneldl p5r-HolTif2ercatrieocnepttohrr obuingdh isnygm apnadt hgeetniec pphtrqsHehepayaxuTevnepnpa cecIocnrhAirarettfyehilies pfceaasaai tdiolnetaoiae tcddnndmhc tr etab5aiueoncly-ggsamHr oermeHnndiaTasPeuituse2s rsLremdtca id oC tn[orri 3fegoa.5d H c n7t5-epseH.]2l- a mpHro nThtefeoTcv IsprrApeIueaAralga nesnaeterccninrdgrcrdeei e erntc aae5oeeettxg -pie.npHc ectTe rnotrTahoereersme2 rgas acseeiisthosnsxienaaoeprdmynrer a eicr wniestani pstalot iestrhsonov.aen r ted5u shloo-sm..yHifn nT pOe5RTgoh -u bINtH6iAhrys0AT a r%saluIe ta neussA mdxupidn plauya5tgnrnss - ei csHdssospr u sfT5teeg hia-s2cogHehticneef aT fisc.rmc it2teTr oacsc htmot gehr eppoteey oentc 5oh. rei -iarysTpdHsttpthee oTwonde[rt3I ,t ehp AgiH7rfaaeey2 ]lnnaa8 ce5nhmd-r O- doweaiHw caHn5atTnds-i sDc H I-ea7rAPrnT reodaA eg2atalguoyTncyelnz dan.sr eete5 ee5drrp-cdg a-HaebH itincpyTino Tc tr2nRore2cterThccaswee-r trpPe eahecctgCscyoet eRoeperpnmv tpo.feo autt5i rohlsen-ueraxHacdalpstaTtigsremor aeedcanynsuot asbs esnwli.y. o t er5e Ran5ex-nsgTH-pt Hudi-rTnPlwoeTa Csncatt sciohesRioo n oehnb ntna i ey7tgdn ne i huaundntel rs tywartii,nshn y ai5igngesss- |
| URI: | http://dyuthi.cusat.ac.in/purl/526 |
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| Valiyaveetil Mohanan and others(2005)july26.PDF | (6.367Mb) |
| Abstract: | A compact single –feed multiband planar antenna configuration Suitable for GPS, DCS. 2.4/5.8 GHz WLAN applications are presented. The antenna has dimensions 38 x 3 x 1.6 mm and offers good radiation and reflection characteristics in the above frequency bands. The antenna has a simple geometry and can be easily fed using a 50 coaxial probe |
| URI: | http://dyuthi.cusat.ac.in/purl/1357 |
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| Compact planar ... GHz WLAN applications.PDF | (1.032Mb) |
| Abstract: | A new photopolymerizable recording media is introduced based on poly (vinyl alcohol) and vinyl acetate sensitized with methylene blue. It is observed that this MBPVA/VAc system can be reused a number of times without significant decrease in diffraction efficiency. The PVA-VAc ratio was optimized at 2:1. Diffraction efcienc4y of 6.3% was obtained without any fixing at a dye concentration of 9.3 x 10- mol/l at an exposure of 750mJ/cm2. The material is attractive on account of its reusability. |
| URI: | http://dyuthi.cusat.ac.in/purl/796 |
| Files | Size |
|---|---|
| Beena Mary John ... recording...,march2005.PDF | (7.043Mb) |
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