Scientists trying to determine the mass of galaxies have found a consistent discrepancy which suggests that 90% of the universe is in the form of dark matter that cannot be seen. The last few decades have witnessed the development of various theories of dark matter. The paper, "Nature of Dark Matter in the Context of Recent Experiments and Observations", by R Sharma, G K Upadhyaya and M Thakre, has chronicled all the important theories of dark matter. Both the direct and indirect methods for the detection of Weakly Interacting Massive Particles (WIMPs) and a comparison of the sensitivity limits of various important experiments have been reported. Results of the experiments have been juxtaposed against the results obtained from some popular WIMP detection theories. Most of the experiments and theories discussed showed consistency in predicting WIMP mass.

Band width limitations, multipath fading and Intersymbol Interference (ISI) are some problems encountered in a communication system. While equalizers are used to remove the ISI, Multi-Input Multi-Output (MIMO) diversity techniques are used to encounter the problem of multipath fading and minimize Bit Error Rate (BER). In the paper, "Interference Mitigation-Based Space Time Equalizers for MIMO Wireless Communication System", Syed A Imam and Vibhav Kumar Sachan, have proposed a combined system using equalization and diversity. A space time equalizer in multiple transmitter-multiple receiver (MIMO) wireless communication system has been modeled. Simulations have been used to study the performance of the proposed system. The authors concluded that the MIMO diversity improves significantly, the signal-noise ratio for a given value of BER.

Ogwueleka Toochukwu Chibueze and Ogwueleka Francisca Nonyeluma team of researchers from the Department of Computer Science, University of Abuja, Nigeria, have consistently shown their aptitude to employ Artificial Neural Network (ANN) as a tool to manage social issues like waste water management and predicting malaria endemic zones in the city of Abuja. The paper, "Prediction of Solid Waste Generation Using Self-Organizing Map and Multilayer Perceptron Neural Networks", by Ogwueleka Toochukwu Chibueze and Ogwueleka Francisca Nonyelum used ANN to find a solution that could provide a near precise information on the municipal solid waste generation in the city. The significance of this study lies in the fact that an accurate estimation and the prediction of municipal solid waste generation are important in efficient solid waste management.

According to a report from The Energy and Resources Institute (TERI), of the 575,000 Indian villages, about 162,000 face problems of brackish or contaminated water and scarcity of fresh water. With limited stock of fresh water and an ever-increasing demand for it, the urgent need for desalinating water in India cannot be stressed more. Factors like absence of electricity, heavy investment, and the polluting nature of conventional fuels rule out the possibility of working with regular desalination technologies in rural India. Solar desalination plants are therefore the most practical solution. The paper, "The Effect of Coupling a Flat Plate Collector on the Single Slope Basin Solar Still Productivity", by Jadhav Madhav V, is an experimental investigation to study the effect of coupling a flat plate solar collector on the productivity of simple basin solar stills. Optimal values of parameters like water depth, sun energy, day time wind speed, day time ambient temperature, temperature of basin water and temperature below glass cover required to enhance the productivity is also reported.

Decision Support Systems (DSS) support decision-making activities that would be very useful in the comparative evaluation of maintenance strategies. The paper, "Decision Support System for Butter Oil System of a Dairy Plant at NDRI", by Sanjay Kajal, P C Tewari and Deepak Kausik, discusses a DSS for butter oil unit of a dairy plant at the National Dairy Research Institute (NDRI). The mathematical model of the unit has been developed using Markov birth-death process using probabilistic approach. The differential equations developed are solved to develop the steady state availability and the system performance has been studied for various availability levels for different combinations of failures and repair rates of the subsystems making up the system.

Fossil energy, particularly derived from coal, doesn't find favor with the environmentalists who see coal as inherently dirty. The inorganic minerals present in the mined coal are desired up to certain levels due to their catalytic effects in gasification and liquefaction. The mineral contents in the mined coal are normally more than this desired level and reduce the energy efficiency of the fuel besides contributing to the pollution. Demineralization prior to utilization to reduce the ash forming inorganic elements is an effective way to ensure environment friendly combustion of coal. Concerted efforts are on to use less time-consuming and cost-effective techniques for removal of ash forming minerals from coal. Forced leaching of coal using acids is one of the popular techniques. The paper, "Leaching of Minerals in Sub-Bituminous Indian Coal and Characterization of the Products", by Manoj B, Kunjomana A G and Mansoor Ahmed, demonstrates the use of FTIR and ultimate analysis to evaluate the ability of some leachants in demineralizing the coal. The results of their study revealed that from among the various types of leachants used, HF (used in isolation) and acid mixture (HF + HCl) give the best results for the removal of silicate, calcium and aluminium minerals.

-- Elizabeth Zacharias
Consulting Editor