Use of waste hot water in double basin solar still

A periodic analysis of a double basin solar still is presented in this paper. In this still waste hot water is fed into the lower basin at a constant rate such as is available from power stations or other industries. The effect of various parameters on the distillate output of the still is also investigated.     

Ethylene glycol retention method for estimating specific surface area of adsorbent carbons

Ethylene glycol retention method, standardised by Dyal and Hendricks for clays and soils, has been used for determining specific surface areas of a large variety of adsorbent carbons differing widely in the extent as well as chemical nature of their surfaces. The proposed method yields values comparable with those obtained by the gaseous adsorption methods, irrespective of the oxygen contents of the carbons. A small amount of oxygen, probably within 0.2%, is essential to bring about proper wetting of the carbon by glycol.     

Serological study of Japanese encephalitis in Nepal

Antibodies against Japanese encephalitis virus (JEV) were examined in 356 serum samples from individuals visiting Tribhuvan University Teaching Hospital using neutralization test. A total of 13.2% (47/356) seropositivity was observed. Antibody positivity against both Nakayama-NIH and Beijing-1 strains was seen in 7.9% subjects. Infection by Nakayama-NIH strain alone was seen to be 4.2% while 1.1% of study populations were found to be infected only by Beijing-1 strain. High antibody titer was observed in the 20-40 years age-group and did not increase with age. Seropositivity was more common in zone-A (Tarai) area compared to zone-B (Hills) and zone-C (Mountains). Spectrum of antigenicity of JEV in zone-A as shown by neutralization test was identical to Indian isolates (strains). Difference in seropositivity was observed against Nakayama-NIH and Beijing-1 strain in zone-B and C indicating recent spread of JEV in these areas.     

Observations of grain boundary sliding during superplastic deformation

Flat test specimens of a 10-micron grain size Al-33 pct Cu alloy were deformed in air over a range of strains at 450 °C (723 K) and at 10^-5 strain per second, and examined by SEM. Direct observations and measurements were also made in a SEM during superplastic deformation of a 5-micron Pb-Sn eutectic alloy at room temperature at a strain rate of about 10^-5 s^-1. Extensive grain boundary sliding was noted. Microcreep curves were obtained between initially adjacent grains and showed that deformation is cyclical in nature and varies by several orders of magnitude locally from point to point. Many surface grains are observed to change neighbors many times, to undergo some rotation and tilt, to show little change in size or shape, and yet to avoid intergranular cracking. Superplastic deformation is a highly heterogeneous process, not unlike that observed in the creep of conventional types of alloys at elevated temperatures, but differing in the extent of plastic deformation free of intergranular cracking, combined with extensive recovery in the form of boundary migration. Formerly a Graduate Student in the Department of Materials Science and Engineering at Massachusetts Institute of Engineering, then Research Manager of SAIL in Ranchi, India     

Experimental results on preprocessing of path/cut terms in sim ofdisjoint products technique

Researchers have proposed cardinality-, lexicographic-, and Hamming-distance-order methods to preprocess the path terms in sum of disjoint products (SDP) techniques for network reliability analysis. For cutsets, an ordering based on the node partition associated with each cut is suggested. Experimental results showing the number of disjoint products and computer time involved in generating SDP terms are presented. Nineteen benchmark networks containing paths varying from 4 to 780, and cuts from 4 to 7376, are considered. Several SDP techniques are generalized into three propositions to find their inherent merits and drawbacks. An efficient SDP technique is then used to run input files of paths/cuts preprocesses using cardinality-, lexicographic-, and Hamming-distance-ordering, and their combinations. The results are analyzed, showing that preprocessing based on cardinality or its combinations with lexicographic-, and/or Hamming-distance-ordering performs better     

Water-table variation in a sloping aquifer due to random recharge

Variation in the level of the water table is closely linked with recharge. Therefore, any uncertainty associated with the recharge rate is bound to affect the nature of the water-table fluctuation. In this note, a ditch-drainage problem of a sloping aquifer is considered to investigate the effect of uncertainty in the recharge rate on water-table fluctuation. The rate of recharge is taken as an exponentially decaying function with its decay constant as a Gaussian random variable. Expressions for the first two moments of the water-table height, i.e. mean and standard deviation, are presented. By using these expressions, the effect of uncertainty in the recharge rate on the water-table fluctuation has been analyzed with the help of a numerical example.     

On the measurements of superplasticity in an Al-Cu alloy

The usual method of measuring the strain rate sensitive ‘m’ values of superplastic materials through differential cross-head speed is found to result in improperly definedm values;m is found to depend strongly on the strain to which the material is subjected, especially at low strains. In this connection, the shape of the log stress-log strain rate curve is examined for the Al-33 wt pct Cu eutectic alloy. The inherent grain growth of the very fine grains which occurs during deformation, and the strain dependence ofm at low strains, are shown to be the causes of the familiarS shape of the log stress-log strain rate curves for the Al-Cu alloy. At high strains (15 to 20 pct and higher) where the stress is no longer importantly strain sensitive, the log stress-log strain rate curve is a straight line of slope near 0.5. The elongation at fracture also does not go through a maximum but continues to increase slowly to the lowest strain rate examined: 10^-7 per s. Formerly Research Assistant, Department of Metallurgy and Materials Science, MIT.     

Reliability Education in India?Present and Future

This paper surveys the present status and efforts in formal and informal reliability education in India. Survey of important research activities as indicated by the published research papers in this Transactions for the last five years is also included. A three phase programme for future training in reliability for developing countries like India is suggested. Phase one consists of immediate introduction of an elective course for all disciplines of engineering at undergraduate level which should be gradually converted into a compulsory course. Phase two consists of introducing a specialized 2-year postgraduate programe in reliability engineering. Brief course details for both these phases are given. Phase three is the establishment of a National Reliability Research Centre to coordinate, direct, and advance research activities.