Design and Analysis of Metamaterial Absorber using Split Ring Resonator for Dual Band Terahertz Applications

There are numerous applications for microwave absorbers in the L, S, C, X, and Ku bands. Creating a terahertz absorber, on the other hand, has proven difficult. This paper presents a metamaterial absorber operates at terahertz frequencies. It has a square shaped outer ring and a circle shaped inner ring unit cell split ring resonator. The substrate is dielectric material and the ground is metallic. According to the simulation results, the unit cell resonates at two frequencies that is at 1.3027THz and 1.7853THz with absorptivity  is greater than 90% at normal incidence .The main cause of high absorbance is due to strong electromagnetic field. The proposed structure in this paper is useful for terahertz imaging, detection of malignant tumors and stealth technology

Free-standing arrays of BaTiO3 nanotubes for non-enzymatic glucose sensing & hydrophobic coating applications

BaTiO _3 nanostructures have been considered as a promising candidates in recent past for energy and biomedical sectors owing to their excellent physiochemical properties, such as high dielectric constant, excellent piezoelectric property, good biocompatibility, non-linear optical characteristics etc. Present study reveals on free-standing arrays of BaTiO _3 nanostructures, were fabricated by hydrothermal conversion of anodic TiO _2 nanotubes. Morphological and structural information of the BaTiO _3 nanotubes were done using FESEM and XRD studies. FESEM analysis revealed that the fabricated samples were having tubular morphology of average length and pore diameter of 4.63 μ m and 290 nm respectively. Cubical perovskite crystalline phase of BaTiO _3 was confirmed through XRD analysis. The BaTiO _3 nanotube samples had shown a higher sensitivity of 44.43 μ A mM ^−1 cm ^−2 and a faster response of 0.1 s for glucose detection. The fabricated BaTiO _3 nanotubes film also showed a higher contact angle of 122.70°. Therefore, our present fabrication on Titanium foil study emphasizes on arrays of BaTiO _3 nanotubes which will open up a new window in the development of various types of sensing and hydrophobic coating applications

Growth studies on <i>Clypeomorus clypeomorus</i> Jousseaume (Gastropoda: Cerithiidae) from the Visakhapatnam Coast

12-15Growth rate of C. clypeomorus has been measured employing analysis of population sampling and calculation of absolute growth rate. Height and age relationships of the snail are studied. Results show clear seasonal variation in growth rate of the snail, maximum shell height of 18 mm and survival period of 1 yr. It attains sexual maturity at shell height of 11-12 mm and breeding is continuous. The small size and relatively short life span may be due to early attainment of maturity and continuous reproductive activity

Distribution, characters and habits of <i>Clypeomorus clypeomorus</i> Jousseaume (Gastropoda: Cerithiidae) of the Visakhapatnam Coast

50-53Distribution and density of C. clypeomorus at different stations on the Visakhapatnam Coast, Andhra Pradesh, India and at different tide levels are reported. The characters of the shell, operculum, jaws, radula and foot are given. The moving habits of the snail and the organisms associated with C. clypeomorus are described

Performance evaluation of acoustic signals for underwater applications in high-frequency range

252-258Performance evaluation of high frequency (20-24 kHz) underwater acoustic waveforms such as CW, LFM and HFM was carried out theoretically in the presence of white Gaussian noise, multipath and Doppler. Measured sound speed profiles off Indian coast were used in ray based models Bellhop and VirTEX to mimic the environment with multipath and Doppler. The source signals were convolved with channel impulse response function to predict the received signal. Correlation between the transmitted and received signal was used to evaluate the performance of waveforms. Performance evaluation studies have revealed that LFM and HFM have better resistance to additive white Gaussian noise than CW. Similarly multipath has affected CW the most while HFM and LFM are resistant to it. The Doppler imposed by the source/receiver motion has very little effect on HFM followed by LFM and CW. It was also found that both LFM and HFM have shown greater resistance to Doppler when the receiver is close to the surface.</span

Autoclave leaching of refractory uranium minerals

Hydrometallurgy is the predominant process route used for the recovery of uranium values from its ores and leaching is the critical step amongst the various unit operations involved. Although simple uranium minerals like uraninite and pitchblende are readily leached with acid or alkali leachants under atmospheric pressure conditions, however refractory phases of uranium are very difficult for dissolution. In addition, some uranium ores yield low leach recovery due to the physical nature of uranium mineralization. Autoclave circuits have been proven as reliable unit processes that increase leach efficiencies resulting in stabilized and environmentally least harmful leach residues. Sustained R & D efforts in BARC have resulted in possibility of applying autoclave-leaching for the dissolution of uranium from refractory minerals (viz. betafite, liandratite) and ores with extremely fine dissemination of uranium phases, using both acid and alkaline leaching technology. An overview of these results is discussed in this paper