Design, Development & Performance Evaluation of an Anechoic Chamber for

The design, erection and evalution procedures for it microwave anechuic chamber competed at Cochin University for antenna studies are presented the chamber has an average reflectivity level of - 32 dB on at X-band frequencies, and it i, comparable to international standards.

Optical Emission Diagnostics Of Laser Produced Plasma From Graphite And Yba2cu3o7

This thesis is entitled “OPTICAL EMISSION DIAGNOSTICS OF LASER PRODUCED PLASMA FROM GRAPHITE AND YBa2Cu3O7. The work presented in this thesis covers the experimental results on the plasma produced with moderately high power laser with irradiance range in between 10 GW cm 2 to 100 GW cm -2. The characterization of laser produced plasma from solid targets viz. graphite and high temperature superconducting material like YBa2Cu3O7 have been carried out. The fundamental frequency from a Q - switched Nd: YAG laser with 9 ns pulse duration is used for the present studies. Various optical emission emission diagnostic techniques were employed for the the characterization of the LPP which include emission spectroscopy, time resolved studies, line broadening method etc. In order to understand the physical nature of the LPP like recombination, collisional excitation and the laser interaction with plasma, the time resolved studies offer the most logical approach

Comparative Studies on the Abundance of Zooplankton in the Surrounding Sea & Lagoons in the Lakshadweep

Composition and distribution of various groups and species of zooplankton at Kavaratti, Agatti and Suhelipar atolls of the Lakshadweep group of islands are reported . Higher biomass and diversity occur in the sea surrounding atolls compared to lagoons . Copepoda forms the dominant component of zooplankton . Zooplankton washed across the reef into the lagoon may be serving as food to the reef community . No fauna endemic to lagoons are encountered.

Toxicity of Effluent from a Titanium Dioxide Factory on some Marine Animals

Toxicity of effluent from a titanium dioxide factory containing sulphuric acid residue with soluble iron metallic salts and insoluble material such as silica, etc. on fishes, decapods and molluscs was studied. The effluent caused changes in pH and oxygen depletion of the sea water. Sublethal effects of the precipitate of ferrous salts were also studied. Dilutions of effluent up to 1:150 were LC100 for all organisms used while 1:200 dilution was LC50 for fishes at 36 hr and for other organisms at 48 hr. But death of organisms at this concentration was caused by pH changes and oxygen depletion and did not account for the effects of the precipitate. Below this level precipitation started soon after mixing with sea water causing death of organisms by choking their gills and siphons. Dilutions,< 1:1000 were 96 hr LCO.

Incidence of Red Water Along South Kerala Coast

Incidence of red water along the Kerala coast at 2 localities, off Quilon and Cochin, in August 1976 and 1977 is reported. High concentrations of Noctiluca miliaris (up to 7.71 x 105/m3 in 1977) are associated with these occurrences. They completely dominate the plankton community contributing > 90 % of the numbers. High production of diatoms initiated by nutrient-rich and fairly high saline upwelled waters appears to cause the bloom of the dinoflagellate Noctiluca

A Circularly Polarized Corrugated Flanged Feed Horn

Design and development of a circularly polarized and matched H-plane sectorial horn antenna have been reported By proper trimming of the flange parameters any desired polarization can be obtained from the horn

A Compact Electronically Reconfigurable Dual Frequency Microstrip Antenna for L-Band Applications

A novel design of a computer electronically reconfigurable dual frequency dual polarized single feed hexagonal slot loaded microstrip antenna in L-band is introduced in this chapter. pin diodes are used to switch the operating frequencies considerably without much affecting the radiation characteristics and gain. the antenna can work with a frequency ratio varying in the wide range from 1.2 to 1.4. the proposed design has an added advantage of size reduction up to 72.21% and 46.84% for the two resonating frequencies compared to standard rectangular patches. the design also gives considerable bandwidth of up to 2.82% and 2.42 % for the operating frequencies.

A New Broadband Circular Patch Antenna

A simple technique to improve the impedance bandwidth of a circular microstrip patch antenna using two sectorial slots is proposed. Using this design more than 5% impedance bandwidth is obtained. The added advantage of this new antenna is that it can be fed by a 50 microstrip line.

A Strip-Loaded Feed-Horn antenna

Design and development of a new feed -horn antenna with low sidelobe levels is reported . The E-walls of this antenna are fabricated with low -loss dielectric substrate , periodically loaded with thin conducting strips . The antenna is found to be simulating the radiation characteristics of metallic corrugated horns . This can be an ideal substitute for metallic corrugated horns with added advantages like light -weight and low production cost.

A Strip-Loaded Feed-Horn antenna

Design and development of a new feed -horn antenna with low sidelobe levels is reported . The E-walls of this antenna are fabricated with low -loss dielectric substrate , periodically loaded with thin conducting strips . The antenna is found to be simulating the radiation characteristics of metallic corrugated horns . This can be an ideal substitute for metallic corrugated horns with added advantages like light -weight and low production cost.

Analysis of a New Compact Microstrip

A new compact microstrip antenna element is analyzed. The analysis can accurately predict the resonant frequency, input impedance, and radiation patterns. The predicted results are compared with experimental results and excellent agreement is observed . These antenna elements are more suitable in applications where limited antenna real estate is available

Land Transfers and Peasant Mobility

It is hoped that the present study by analysing the dynamics of agrarian change and peasant mobility may contribute to the on-going debate on this issue in India and other developing countries. It may also help to throw light on the validity of some of the theories formulated on the basis of experience in different regions and at different times. The study is likely to be of special importance as it covers an area which has one of the highest densities of population. The area has also witnessed sweeping changes in agrarian structure as a result of the most radical land reforms among the Indian states.