Construction of unpaved rural road using jute–synthetic blended woven geotextile – A case study

Jute–high density polyethylene (HDPE) blended geotextile samples produced using HDPE slit-film in the machine direction and jute yarn in the cross direction for use in the construction of unpaved rural roads. Use of HDPE slit-film resulted in high productivity of jute-based geotextiles in modern high-speed machines, while jute (≈85%) in cross direction resulted in notable increase in modulus, breaking strength, CBR puncture resistance of the blended geotextile as compared to 100% HDPE geotextile. The optimized geotextile (plain-weave fabric with 111 tex HDPE in machine direction, 2 × 360 tex jute yarn in cross direction having area density, 316 g/m²) was used in a field trial. During road construction, the geotextile was covered with a layer of 10 cm thick laterite gravels as the sub-grade, compacted by rolling, and then finally covered with 10 cm small granular lateritic stones, and rolled again. The field trial showed that the monitored section where geotextile was used showed an even surface without any notable subsidence or rutting after 18 months. However in sections of the road constructed without the geotextile, 5–35 mm deep ruts were observed. CBR tests (carried out 11 months and 18 months after construction) showed a 67–73% improvement in the road due to the use of jute–HDPE blended geotextile than that obtained for the part of the road where geotextiles were not used.     

Radar cross section of a finite planar structure coated with a lossy dielectric

An asymptotic high frequency estimation of monostatic radar cross section (RCS) of a finite planar metallic structure coated with a lossy dielectric is made theoretically and compared with experiments in theX- band. An expression for RCS is obtained by using a diffraction coefficient involving Maliuzhinets' function. A closed form expression of the Maliuzhinets' function has been developed. Corner diffraction effects are not considered. A continuous wave (CW) monostatic RCS measurement set up has been used to verify the theoretical results experimentally. A typical reduction with a single coating of epoxy resin of thickness equal tolambda /20is of the order of 5 dB for normal incidence compared to a conducting plate of the same size.     

Resonant length of a linearly polarised microstrip radiator

A method for altering the resonant length of a square micro-strip antenna is described. The relevant analysis and computations have been carried out to propose a possibility of realising a microstrip antenna having comparatively smaller dimensions and larger bandwidth.     

Hydrogenation of Peanut and Sesame Oils in Hexane

The various parameters of hydrogenation of peanut and sesame oils in hexane have been investigated. At 140°C, 100 p. s. i. g. total pressure and 200 shakes/min. agitation the rate and selectivity of hydrogenation of peanut oil in hexane increased with increase in catalyst concentration from 0.1 to 0.3% Ni, beyond which (0.5 and 1.0%) the rate remained practically same and the selectivity decreased. The rate and selectivity decreased with decrease in total pressure of the system from 100 to 85 and 70 p. s. i. g. at 140°C and 0.3% Ni. The trans isomer formation was almost similar to that observed at 100 p. s. i. g. The reaction appeared to be of first order for certain period of hydrogenation at all catalyst concentrations. The temperature was the most important variable in controlling rate and selectivity. Both selectivity and the trans isomer formation increased from 115° to 140°C. These experiments demonstrated the commercial feasibility of the solvent (miscella) hydrogenation process.     

Foam separation of complexed cyanide: Studies of rate and of pulsed addition of surfactant

An experimental investigation is presented of the foam separation of cyanide complexed with ferrous iron, using a cationic surfactant, ethylhexadecyldimethylammonium bromide. With a 25 min. foaming time, an initial iron to total cyanide ratio of 0·351:1 and an initial surfactant to complexed cyanide ratio of about 0·34:1 suspensions containing from 1·54 to 3·08 mM total cyanide can be reduced to about 0·11 mM in complexed cyanide and 0·29 mM in non-complexed cyanide. The rate of surfactant removal was satisfied by a first-order relationship, similar to that obtained with colloidal ferric oxide. The rate of complexed cyanide removal was satisfied by a reversible, approximately first-order relationship eliminating the residual surfactant concentration. The pulsed addition of surfactant in three dosages during the course of an experiment, compared with a single dose at the beginning of an experiment, produced lower residual concentrations of complexed cyanide and higher foam volumes. At an iron to total cyanide ratio of 0·351:1,90% of the complexed cyanide concentration could be removed by one fifth less surfactant, using pulsed addition, compared with a single dose.     

The effect of high temperature annealing on the spatial variation of bulk lifetime near the SiSiO2 interface

In this paper, the effect of high temperature N₂ annealing at 1100°C on the minority carrier lifetime in the bulk of the silicon close to the SiSiO₂ interface has been investigated for dry thermal oxides and TCE oxides. This annealing results in substantial reduction of lifetime for dry thermal oxides and the same annealing process enhances the lifetime for TCE oxides. The annealing-affected region in silicon near the interface was scanned by computing lifetime as a function of distance from the SiSiO₂ interface, using the Zerbst method with a suitable modification. The smaller values of lifetime observed near the SiSiO₂ interface have been correlated with stacking faults whose electrical activity seems to be significantly controlled by metallic impurities. A mechanism (supported by the experimental results) is suggested for the lifetime change due to annealing. The influx of metallic impurities coming from the annealing ambient seems to be decreasing the lifetime of carriers in silicon under dry thermal oxides, whereas, for the TCE oxides, we postulate that chlorine incorporated in the oxides prevents this influx and further also helps in the deactivation of existing metallic impurities in the silicon.     

Thermal power generation and environment: A review of the Indian case

Thermal power has emerged as the major source of electric power in lndia over the years and is expected to rise further. The environmental effects of thermal power generation are becoming a major concern. A review of the status at present, in terms of regulations and their application in the power industry, is presented here.     

Studies on poly(vinyl chloride)-copper composites. Part 1: State of segregation of filler particles,electrical and mechanical properties in presence of plasticizer and stabilizer

The presence of additives influences the state of segregation of filler particles in the polymer matrix which in turn controls the electrical and mechanical properties of poly(vinyl chloride)-copper composites. The liquid plasticizer seems to form a coating on the filler surface which introduces quasirandomness in the segregated network. In accordance with the mathematical model proposed earlier, the strength properties were found to be proportional to d_m^?½ where d_m is the mean free path between the filler particles. Calculations of d_m were based on two different models, one for segregated network (unplasticized and low plasticized composites) and the other for quasi-random distribution of filler particles (plasticized composites). Extruded samples in general show more randomness in the filler distribution than the compression molded samples.