Effect of Receiver Bandwidth on Waveforms and Time Characteristics of Atmospheric Radio Noise Bursts

Several investigators have presented the results of their experimental investigations and theoretical expectations on the effect of receiver bandwidth on the time characteristics and waveforms of atmospheric radio noise bursts. The experimental and theoretical findings do not appear to agree with each other. This communication offers a possible explanation for this "discrepancy" with support from experimental evidence, drawn from a large number of references included in this communication.     

On profit evaluation in a two-unit maintained redundant system

A two-unit redundant system is considered and analytic expression for total expected profit earned in a given time is obtained after writing basic cost equations governing the behaviour of the system.A procedure is suggested to obtain optimal failure and repair rates so that expected steady state profit is maximum.     

The component fatty acids of chaulmoogra oil

The fatty acid composition of the seed oils of the species, Hydnocarpus kurzii, H. wightiana and H. odorata were determined by gas-liquid chromatographic (g.l.c.) analysis. The percentages of individual fatty acids were found to be: hydnocarpic 23.0, 33.9, -; chaulmoogric 29.6, 35.0, -; gorlic 25.1, 12.8, -; lower cyclic homologues 0.3, 4.6, -; myristic 0.6, 0.8, 0.4; palmitic 8.4, 5.6, 11.8; stearic -, 0.6, 4.7; palmitoleic 6.0, 1.3, 0.5; oleic 5.4, 3.6, 21.8; linoleic 1.6, 1.8, 29.3; linolenic -, -, 31.2; respectively.     

Solution of eigenvalue problems by sturm sequence method

A generalized eigenvalue algorithm is presented herein along with the complete listing of the associated computer program, which may be conveniently utilized for the efficient solution of certain broad classes of eigenvalue problems. Extensive applications of the procedure are envisaged in the analysis of many important engineering problems, such as stability and natural frequency analysis of practical discrete structural systems, idealized by the finite element technique. The procedure based on the Sturm sequence method is accurate and fast, possessing several significant advantages over other known methods of such analysis. Numerical results are also presented for two representative structural engineering problems.     

Thermoluminescence and triboluminescence in trioxane crystals

Polymerised trioxane crystals, irradiated at liquid nitrogen temperature show a single thermoluminescence peak on warming. Corresponding trioxane monomer crystals show a thermoluminescence spectrum of five peaks, and a series of sharp spikes at irregular intervals. On warming an unirradiated crystal, a two-peak spectrum plus spikes is obtained. The spikes are associated with strong electrical discharges and tentatively ascribed to dislocation of crystals under thermal stress.     

Communication scheduling to minimize thermal effects of implanted biosensor networks in homogeneous tissue

A network of biosensors can be implanted in a human body for health monitoring, diagnostics, or as a prosthetic device. Biosensors can be organized into clusters where most of the communication takes place within the clusters, and long range transmissions to the base station are performed by the cluster leader to reduce the energy cost. In some applications, the tissues are sensitive to temperature increase and may be damaged by the heat resulting from normal operations and the recharging of sensor nodes. Our work is the first to consider rotating the cluster leadership to minimize the heating effects on human tissues. We explore the factors that lead to temperature increase, and the process for calculating the specific absorption rate (SAR) and temperature increase of implanted biosensors by using the finite-difference time-domain (FDTD) method. We improve performance by rotating the cluster leader based on the leadership history and the sensor locations. We propose a simplified scheme, temperature increase potential, to efficiently predict the temperature increase in tissues surrounding implanted sensors. Finally, a genetic algorithm is proposed to exploit the search for an optimal temperature increase sequence.     

Use of waste materials--Bottom Ash and De-Oiled Soya, as potential adsorbents for the removal of Amaranth from aqueous solutions

Bottom Ash, a power plan t waste material and De-Oiled Soya, an agriculture waste product were successfully utilized in removing trisodium 2-hydroxy-1-(4-sulphonato-1-naphthylazo)naphthalene-3,6-disulphonate--a water-soluble hazardous azo dye (Amaranth). The paper incorporates thermodynamic and kinetic studies for the adsorption of the dye on these two waste materials as adsorbents. Characterization of each adsorbent was carried out by I.R. and D.T.A. curves. Batch adsorption studies were made by measuring effects of pH, adsorbate concentration, sieve size, adsorbent dosage, contact time, temperature etc. Specific rate constants for the processes were calculated by kinetic measurements and a first order adsorption kinetics was observed in each case. Langmuir and Freundlich adsorption isotherms were applied to calculate thermodynamic parameters. The adsorption on Bottom Ash takes place via film diffusion process at lower concentrations and via particle diffusion process at higher concentrations, while in the case of De-Oiled Soya process only particle diffusion takes place in the entire concentration range.     

Acousto-optic tunable filter sidelobe analysis and reduction with telecentric confocal optics

The acousto-optic tunable filter (AOTF) has optical sidelobes that are due to the acoustic field produced by the transducer. These sidelobes were analyzed by wave-vector phase matching between the optical and acoustic fields, which correlated with measurements made with a TeO2 AOTF. A white-light point source was filtered and imaged, showing reasonably large and slowly decreasing sidelobes covering a large spectral range. This effect reduces the image quality of an AOTF system by producing faint secondary images of bright objects. The image quality can be improved with a telecentric confocal optical arrangement in which the angular shift of the sidelobes is greatly reduced, producing a much sharper image. This effect was also demonstrated experimentally with the point source.     

Detection of photothermal deflection signals with conjugate masks

A new detection technique for photothermal deflection spectroscopy and photoacoustic deflection spectroscopy is presented. The technique uses a pair of matched multiple slits placed in the path of the probe beam and oriented to block the probe light from the detector in the absence of a deflection signal. Significant improvement in the signal-to-noise ratio and in the frequency bandwidth compared with those available with current techniques is demonstrated.     

Novel carbon nanotube-polystyrene foam composites for electromagnetic interference shielding

A novel carbon nanotube-polystyrene foam composite has been fabricated successfully. The electromagnetic interference (EMI) shielding effectiveness measurements indicated that such foam composites can be used as very effective, lightweight shielding materials. The correlation between the shielding effectiveness and electrical conductivity and the EMI shielding mechanism of such foam composites are also discussed.