| Abstract: | An ultra-wideband (UWB) printed slot antenna, suitable for integration with the printed circuit board (PCB) of a wireless universal serial-bus (WUSB) dongle is presented. The design comprises a near-rectangular slot fed by a coplanar waveguide printed on a PCB of width 20 mm. The proposed design has a large bandwidth covering the 3.1-10.6 GHz UWB band, unaffected by the ground length, and omnidirectional radiation patterns. A linear phase response throughout the band further confirms its suitability for high-speed wireless connectivity. |
| URI: | http://dyuthi.cusat.ac.in/purl/2723 |
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| Dyuthi-P00360.pdf | (240.7Kb) |
| Abstract: | A compact ultra-wideband (UWB) printed slot antenna is described, suitable for integration with the printed circuit board (PCB) of a wireless, universal, serial-bus dongle. The design comprises of a near-rectangular slot fed by a coplanar waveguide (CPW) printed on a PCB of size 20 × 30 mm2. It has a large bandwidth covering the 3.1–10.6 GHz UWB band, with omnidirectional radiation patterns. Further, a notched band centered at 5.45 GHz wireless local area network bands is obtained within the wide bandwidth by inserting a narrow slot inside the tuning stub. Details of the antenna design are described, and the experimental results of the constructed prototype are presented. The time domain studies on the antenna shows a linear phase response throughout the band except at the notched frequency. The transient analysis of the antenna indicates very little pulse distortion confirming its suitability for high speed wireless connectivity. |
| URI: | http://dyuthi.cusat.ac.in/purl/2719 |
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| Dyuthi-P00354.pdf | (401.1Kb) |
| Abstract: | We study the period-doubling bifurcations to chaos in a logistic map with a nonlinearly modulated parameter and show that the bifurcation structure is modified significantly. Using the renormalisation method due to Derrida et al. we establish the universal behaviour of the system at the onset of chaos. |
| URI: | http://dyuthi.cusat.ac.in/purl/2571 |
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| Dyuthi-P0130.pdf | (215.1Kb) |
| Abstract: | The thesis deals with a benchmark study of dissolved and sedimentary sulphur compounds which play prominent roles in the prevailing redox conditions in the selected sites of Cochin estuarine system. Sulphur and its analogues play prominent roles in estuarine biochemical processes. A complete knowledge on the sulphur involvement in these processes is restricted due to the lacking of data on the organic sulphur compounds. Sulphate and sulphide in surface and bottom water and Sulphate, acid volatile sulphide and total sulphur in sediments were studied and correlated to know their interrelations in determining the redox condition of the environment. It also characterises the sediments of the sites on the basis of total organic carbon: total sulphur ratio. The study had attempted to decrease the concentration levels of sulphur in the sedimentary environment by the application of a remedial measure. Knowledge of sulphur uptake by plants from prior literatures has prompted to use phytoremediation for decreasing the sulphur concentration. Phytoremediation is an emerging technology that uses plants to clean up or remediate contaminated soil, sludges, sediments, and ground water through contaminant removal, degradation or containment. The plant selected was wheat grass since earlier studies have shown that wheat grass is effective in remediating pollutants particularly trace metals. So reduction in the concentration of selected trace metals was also focussed. |
| Description: | Department of Chemical Oceanography, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2409 |
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| Dyuthi-T0657.pdf | (10.36Mb) |
| Abstract: | The red cells found in the red rain in Kerala, India are now considered as a possible case of extraterrestrial life form. These cells can undergo rapid replication even at an extreme high temperature of 300 deg C. They can also be cultured in diverse unconventional chemical substrates. The molecular composition of these cells is yet to be identified. This paper reports the unusual autofluorescence characteristic of the cultured red rain cells. A spectrofluorimetric study has been performed to investigate this, which shows a systematic shift of the fluorescence emission peak wavelength as the excitation wavelength is increased. Conventional biomolecules are not known to have this property. Details of this investigation and the results are discussed. |
| URI: | http://dyuthi.cusat.ac.in/xmlui/purl/1973 |
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| Godfry, Louis.pdf | (553.2Kb) |
| URI: | http://dyuthi.cusat.ac.in/purl/648 |
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| Dr.Jerry Ignatius and C S P(2006)april.PDF | (7.665Mb) |
| Abstract: | Amine Terminated Liquid Natural Rubber (ATNR) was used as a plasticiser in filled NR and NBR compounds replacing oil/DOP. The scorch time and cure time were found to be lowered when ATNR was used as the plasticiser. ATNR was found to improve the mechanical properties like tensile strength, tear strength and modulus of the vulcanizates . The ageing resistance of the vulcanizates containing ATNR was superior compared to the vulcanizates containing oil/DOP. |
| URI: | http://dyuthi.cusat.ac.in/purl/832 |
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| R Srilathakutty and others,Use of amine..,1996.PDF | (5.714Mb) |
| Abstract: | In this paper, we describe the use of an open cell photoacoustic configuration for the evaluation of the thermal effusivity of liquid crystals. The feasibility, precision and reliability of the method are initially established by measuring the thermal effusivities of water and glycerol, for which the effusivity values are known accurately. In order to demonstrate the use of the present method in the thermal characterization of liquid crystals, we have measured the thermal effusivity values in various mesophases of 4-cyano-4 - octyloxybiphenyl (8OCB) and 4-cyano-4 -heptyloxybiphenyl (7OCB) liquid crystals using a variable temperature open photoacoustic cell. A comparison of the measured values for the two liquid crystals shows that the thermal effusivities of 7OCB in the nematic and isotropic phases are slightly less than those of 8OCB in the corresponding phases |
| URI: | http://dyuthi.cusat.ac.in/purl/1835 |
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| Use of an open ... al characterisation of.pdf | (142.4Kb) |
| Abstract: | In this paper, we describe the use of an open cell photoacoustic configuration for the evaluation of the thermal effusivity of liquid crystals. The feasibility, precision and reliability of the method are initially established by measuring the thermal effusivities of water and glycerol, for which the effusivity values are known accurately. In order to demonstrate the use of the present method in the thermal characterization of liquid crystals, we have measured the thermal effusivity values in various mesophases of 4-cyano-4 - octyloxybiphenyl (8OCB) and 4-cyano-4 -heptyloxybiphenyl (7OCB) liquid crystals using a variable temperature open photoacoustic cell. A comparison of the measured values for the two liquid crystals shows that the thermal effusivities of 7OCB in the nematic and isotropic phases are slightly less than those of 8OCB in the corresponding phases |
| URI: | http://dyuthi.cusat.ac.in/purl/1834 |
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| Dyuthi-P0227.pdf | (142.4Kb) |
| Abstract: | In this paper, we describe the use of an open cell photoacoustic configuration for the evaluation of the thermal effusivity of liquid crystals. The feasibility, precision and reliability of the method are initially established by measuring the thermal effusivities of water and glycerol, for which the effusivity values are known accurately. In order to demonstrate the use of the present method in the thermal characterization of liquid crystals, we have measured the thermal effusivity values in various mesophases of 4-cyano-4 - octyloxybiphenyl (8OCB) and 4-cyano-4 -heptyloxybiphenyl (7OCB) liquid crystals using a variable temperature open photoacoustic cell. A comparison of the measured values for the two liquid crystals shows that the thermal effusivities of 7OCB in the nematic and isotropic phases are slightly less than those of 8OCB in the corresponding phases |
| URI: | http://dyuthi.cusat.ac.in/purl/1836 |
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| Use of an open ... al characterisation of.pdf | (142.4Kb) |
| Abstract: | Carboxy Terminated Liquid Natural Rubber (CTNR) was prepared by photochemical reaction using maleic anhydride and masticated natural rubber (NR). The use of CTNR as an adhesive in bonding rubber to rubber and rubber to metal was studied. The peel strengths and lap shear strengths of the adherends which were bonded using CTNR were determined. The effect of using a tri isocyanate with CTNR in rubber to metal bonding was also studied. It is found that CTNR can effectively be used in bonding rubber to rubber and rubber to mild steel. |
| URI: | http://dyuthi.cusat.ac.in/purl/851 |
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| Dileep U and others,the use of carboxy...,2003.PDF | (4.545Mb) |
| Abstract: | he phenomenon of single beam mirage effect, otherwise known as photothermal deflection (PTD) effect using a He–Ne laser beam has been employed to detect phase transitions in some liquid crystals. It has been observed that anomalous changes in amplitude occur in the PTD signal level near the transition temperature. The experimental details and the results of measurements made in liquid crystals E8, M21 and M24 are given in this paper. |
| URI: | http://dyuthi.cusat.ac.in/purl/2394 |
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| Dyuthi-P0203.pdf | (115.9Kb) |
| Abstract: | The phenomenon of mirage effect suffered by a He-Ne laser beam has been utilized to detect phase transitions in solids. It has been observed that anomalous fluctuations of large amplitude occur in the signal level near the transition temperature. The mean square value of the fluctuation is found to exhibit a well-defined peak at this point. Results of measurements made in the case of crystals of TGS ((NH2CH2COOH)3.H2SO4) and a ceramic sample (BaTiO3) are given to illustrate this technique. |
| URI: | http://dyuthi.cusat.ac.in/purl/2578 |
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| Dyuthi-P0138.pdf | (219.7Kb) |
| Abstract: | Extensive use of the Internet coupled with the marvelous growth in e-commerce and m-commerce has created a huge demand for information security. The Secure Socket Layer (SSL) protocol is the most widely used security protocol in the Internet which meets this demand. It provides protection against eaves droppings, tampering and forgery. The cryptographic algorithms RC4 and HMAC have been in use for achieving security services like confidentiality and authentication in the SSL. But recent attacks against RC4 and HMAC have raised questions in the confidence on these algorithms. Hence two novel cryptographic algorithms MAJE4 and MACJER-320 have been proposed as substitutes for them. The focus of this work is to demonstrate the performance of these new algorithms and suggest them as dependable alternatives to satisfy the need of security services in SSL. The performance evaluation has been done by using practical implementation method. |
| URI: | http://dyuthi.cusat.ac.in/xmlui/purl/2077 |
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| Use of novel algorithms MAJE4 and MACJER-320...pdf | (326.2Kb) |
| Abstract: | We report on a laser induced photoacoustic study of the nematic-to-isotropic transition in certain commercial nematic liquid crystal mixtures, namely BL001, BL002, BL032 and BL035. A simple analysis of the experimental data using the Rosencwaig–Gersho theory shows that the heat capacities of all these compounds exhibit a sharp peak as the temperature of the sample is varied across the transition region. Also, substantial differences in the photoacoustic signal amplitudes in nematic and isotropic phases have been noticed for all the mixtures. The increased light scattering property of the nematic phase may be the reason for the enhanced photoacoustic signal amplitude in this phase. |
| URI: | http://dyuthi.cusat.ac.in/purl/1837 |
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| Dyuthi-P0217.pdf | (152.8Kb) |
| Abstract: | We report on a laser induced photoacoustic study of the nematic-to-isotropic transition in certain commercial nematic liquid crystal mixtures, namely BL001, BL002, BL032 and BL035. A simple analysis of the experimental data using the Rosencwaig–Gersho theory shows that the heat capacities of all these compounds exhibit a sharp peak as the temperature of the sample is varied across the transition region. Also, substantial differences in the photoacoustic signal amplitudes in nematic and isotropic phases have been noticed for all the mixtures. The increased light scattering property of the nematic phase may be the reason for the enhanced photoacoustic signal amplitude in this phase. |
| URI: | http://dyuthi.cusat.ac.in/purl/1839 |
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| Use of photoaco ... iquid crystal mixtures.pdf | (152.8Kb) |
| Abstract: | We report on a laser induced photoacoustic study of the nematic-to-isotropic transition in certain commercial nematic liquid crystal mixtures, namely BL001, BL002, BL032 and BL035. A simple analysis of the experimental data using the Rosencwaig–Gersho theory shows that the heat capacities of all these compounds exhibit a sharp peak as the temperature of the sample is varied across the transition region. Also, substantial differences in the photoacoustic signal amplitudes in nematic and isotropic phases have been noticed for all the mixtures. The increased light scattering property of the nematic phase may be the reason for the enhanced photoacoustic signal amplitude in this phase |
| URI: | http://dyuthi.cusat.ac.in/purl/1838 |
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| Use of photoaco ... iquid crystal mixtures.pdf | (152.8Kb) |
| Abstract: | The increasing tempo of construction activity the world over creates heavy pressure on existing land space. The quest for new and competent site often points to the needs for improving existing sites, which are otherwise deemed unsuitable for adopting conventional foundations. This is accomplished by ground improvement methods, which are employed to improve the quality of soil incompetent in their natural state. Among the construction activities, a well-connected road network is one of the basic infrastructure requirements, which play a vital role for the fast and comfortable movement of inter- regional traffic in countries like India.One of the innovative ground improvement techniques practised all over the world is the use of geosynthetics, which include geotextiles, geomembranes, geogrids, etc . They offer the advantages such as space saving, enviromnental sensitivity, material availability, technical superiority, higher cost savings, less construction time, etc . Because of its fundamental properties, such as tensile strength, filtering and water permeability, a geotextile inserted between the base material and sub grade can function as reinforcement, a filter medium, a separation layer and as a drainage medium. Though polymeric geotextiles are used in abundant quantities, the use of natural geotextiles (like coir, jute, etc.) has yet to get momentum. This is primarily due to the lack of research work on natural geotextilcs for ground improvement, particularly in the areas of un paved roads. Coir geotextiles are best suited for low cost applications because of its availability at low prices compared to its synthetic counterparts. The proper utilisation of coir geotextilcs in various applications demands large quantities of the product, which in turn can create a boom in the coir industry. The present study aims at exploring the possibilities of utilising coir geotextiles for unpaved roads and embankments.The properties of coir geotextiles used have been evaluated. The properties studied include mass per unit area, puncture resistance, tensile strength, secant modulus, etc . The interfacial friction between soils and three types of coir geotextiles used was also evaluated. It was found that though the parameters evaluated for coir geotextiles have low values compared to polymeric geotextiles, the former are sufficient for use in unpaved roads and embankments. The frictional characteristics of coir geotextile - soil interfaces are extremely good and satisfy the condition set by the International Geosynthetic Society for varied applications.The performance of coir geotextiles reinforced subgrade was studied by conducting California Bearing Ratio (CBR) tests. Studies were made with coir geotextiles placed at different levels and also in multiple layers. The results have shown that the coir geotextile enhances the subgrade strength. A regression analysis was perfonned and a mathematical model was developed to predict the CBR of the coir geotextile reinforced subgrade soil as a function of the soil properties, coir geotextile properties, and placement depth of reinforcement.The effects of coir geotextiles on bearing capacity were studied by perfonning plate load tests in a test tan1e This helped to understand the functioning of geotextile as reinforcement in unpaved roads and embankments. The perfonnance of different types of coir geotextiles with respect to the placement depth in dry and saturated conditions was studied. The results revealed that the bearing capacity of coir-reinforced soil is increasing irrespective of the type of coir geotextiles and saturation condition.The rut behaviour of unreinforced and coir reinforced unpaved road sections were compared by conducting model static load tests in a test tank and also under repetitive loads in a wheel track test facility. The results showed that coir geotextiles could fulfill the functions as reinforcement and as a separator, both under static and repetitive loads. The rut depth was very much reduced whik placing coir geotextiles in between sub grade and sub base.In order to study the use of Coir geotextiles in improving the settlement characteristics, two types of prefabricated COlf geotextile vertical drains were developed and their time - settlement behaviour were studied. Three different dispositions were tried. It was found that the coir geotextile drains were very effective in reducing consolidation time due to radial drainage. The circular drains in triangular disposition gave maximum beneficial effect.In long run, the degradation of coir geotextile is expected, which results in a soil - fibre matrix. Hence, studies pertaining to strength and compressibility characteristics of soil - coir fibre composites were conducted. Experiments were done using coir fibres having different aspect ratios and in different proportions. The results revealed that the strength of the soil was increased by 150% to 200% when mixed with 2% of fibre having approximately 12mm length, at all compaction conditions. Also, the coefficient of consolidation increased and compression index decreased with the addition of coir fibre.Typical design charts were prepared for the design of coir geotextile reinforced unpaved roads. Some illustrative examples are also given. The results demonstrated that a considerable saving in subase / base thickness can he achieved with the use of eoir geotextiles, which in turn, would save large quantities of natural aggregates. |
| Description: | Division of Civil Engineering, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2816 |
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| Dyuthi-T0836.pdf | (11.46Mb) |
| Abstract: | Butyl (IIR) tube reclaim (RR) was mixed with carbon black filled natural rubber (NR) compounds at various percentages. The blend containing a low percentage of RR was found to show improved ageing resistance and improved processability with out much reduction in the mechanical properties. |
| URI: | http://dyuthi.cusat.ac.in/purl/830 |
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| N Suma and Rani ... lization of IIR..,1992.PDF | (4.222Mb) |
| Abstract: | Scrap latex products contain rubber hydrocarbon of very high quality, that is only slightly crosslinked. A novel economic technique for converting such latex waste into a processible material is developed. This paper reports the effect of adding this latex reclaim to natural rubber. It is shown that latex reclaim can replace raw natural rubber up to about 50 wt.% without affecting mechanical properties. |
| URI: | http://dyuthi.cusat.ac.in/purl/843 |
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| Reena Susan George and Rani Joseph,1993.PDF | (4.752Mb) |
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