Department of Chemistry
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Item A methodology for building neural networks models from empirical engineering data(Elsiever, 2000-12) Barai, Sudhir KumarNeural networks (NN) are general tools for modeling functional relationships in engineering. They are used to model the behavior of products and the properties of processes. Nevertheless, their use is often ad hoc. This paper provides a sound basis for using NN as tools for modeling functional relationships implicit in empirical engineering data. First, a clear definition of a modeling task is given, followed by reviewing the theoretical modeling capabilities of NN and NN model estimation. Subsequently, a procedure for using NN in engineering practice is described and illustrated with an example of modeling marine propeller behavior. Particular attention is devoted to better estimation of model quality, insight into the influence of measurement errors on model quality, and the use of advanced methods such as stacked generalization and ensemble modeling to further improve model quality. Using a new method of ensemble of SG(k-NN), one could improve the quality of models even if they are close to being optimal.Item Influence of specimen geometry on determination of double-K fracture parameters of concrete: a comparative study(Springer, 2008-07-03) Barai, Sudhir KumarComparative study on analytical method, simplified method and weight function approach for determination the double-K fracture parameters using three-point bend and compact tension tests specimen geometries is presented in the paper. The input data required for numerical calculations are obtained using Fictitious Crack Model. The study reports that the double-K fracture parameters computed depends on factors such as initial-notch length/depth ratios, specimen geometry and size-effect. In addition, it is demonstrated that the use of weight function will further improve the computational efficiency without loss of accuracy.Item Neural Network Models for Air Quality Prediction: A Comparative Study(Springer, 2007) Barai, Sudhir KumarThe present paper aims to find neural network based air quality predictors, which can work with limited number of data sets and are robust enough to handle data with noise and errors. A number of available variations of neural network models such as Recurrent Network Model (RNM), Change Point detection Model with RNM (CPDM), Sequential Network Construction Model (SNCM), and Self Organizing Feature Maps (SOFM) are implemented for predicting air quality. Developed models are applied to simulate and forecast based on the long-term (annual) and short-term (daily) data. The models, in general, could predict air quality patterns with modest accuracy. However, SOFM model performed extremely well in comparison to other models for predicting long-term (annual) data as well as short-term (daily) data.Item Determining double-K fracture parameters of concrete for compact tension and wedge splitting tests using weight function(Elsiever, 2009-05) Barai, Sudhir KumarThe paper presents use of universal form of weight functions for determining the double-K fracture parameters and on compact test and wedge splitting test specimens. The proposed method enables to obtain a closed form expression of cohesion toughness of concrete specimens. A comparison with existing analytical method shows that the weight function method for determination of double-K fracture parameters yields results without any appreciable error. Significant influence of initial notch to depth (a0/D) ratio on the double-K fracture parameters is not also observed. Finally, a possible definition of brittleness of concrete using double-K fracture parameters is proposed.Item AN INVESTIGATION INTO THE USE OF ICT IN THE NIGERIAN CONSTRUCTION INDUSTRY (2005)(2005) Barai, Sudhir KumarThe 2002 global ICT rankings by the International Telecommunications Union (ITU) ranked Nigeria 27th among 51 African countries and 153rd among 178 countries in the world. It was against this background that the paper investigated the state of ICT in the Nigerian construction industry to highlight the level of ICT penetration, its impact in the industry and the constraints to its adoption. The study identified the factors significantly impacting the level of ICT use, grouping them into those internal to the industry and those external to it. A total of 136 respondents to a questionnaire survey, comprising, contractors, consultants and academic researchers, provided empirical data for the analysis. The results showed that some internal factors, i.e., the type of business (whether contracting, consulting or academic), chief executive officers (CEOs)/senior managers’ perception of the benefits of ICT and the years of computer literacy of the CEOs/senior managers were significantly correlated with the level of ICT use in the industry. However, none of the external factors were significantly correlated with the level of ICT use. The main uses of ICT in the industry are word processing, Internet communications, costing and work scheduling. The top five constraints to the use of ICT are insufficient/irregular power supply, high cost of ICT software and hardware, low job order for firms, fear of virus attacks and high rate of obsolescence of ICT software and hardware. A comparison with the results of similar studies in some industrialised and newly industrialised countries indicated that the proportion of firms using the computer is quite high for a developing like Nigeria. It also highlighted the large gap in access to electricity and other communications infrastructure between developed and developing countriesItem Studies on recycled aggregates-based concrete(Sage, 2006-06-01) Barai, Sudhir KumarReduced extraction of raw materials, reduced transportation cost, improved profits, reduced environmental impact and fast-depleting reserves of conventional natural aggregates has necessitated the use of recycling, in order to be able to conserve conventional natural aggregate. In this study various physical and mechanical properties of recycled concrete aggregates were examined. Recycled concrete aggregates are different from natural aggregates and concrete made from them has specific properties. The percentages of recycled concrete aggregates were varied and it was observed that properties such as compressive strength showed a decrease of up to 10% as the percentage of recycled concrete aggregates increased. Water absorption of recycled aggregates was found to be greater than natural aggregates, and this needs to be compensated during mix design.Item Characterization of stainless steel pickling bath sludge and its solidification/stabilization(Elsiever, 2008-06) Singhal, AnupamX-ray diffractometer analysis of stainless steel sulfuric acid pickling bath sludge shows that it contains FeCr2O4, NiCr2O4, NiCrO4, and Cr2O3, which do not dissolve in the acids. X-ray fluorescent spectroscopy (XRF) study reveals that chromium concentration in the sludge is as high as in stainless steel, whereas nickel concentration is on lower side and iron is the major constituent of the sludge. Cement-sludge sand mortar cubes have been prepared in the laboratory. Compressive strength of these cubes decreases linearly with increase in sludge content. As per US EPA TCLP test, heavy metal (Cr and Ni) concentrations are negligible in leachate of cement-sludge sand mortar cubes at 28 days of curing. Hence, cement-sludge sand mortar cubes can be made for safe disposal of sludge.Item Utilization of treated spent liquor sludge with fly ash in cement and concrete(Elsiever, 2008-06) Singhal, AnupamDesign mix of M-20 concrete was prepared in the laboratory by substituting cement with the treated spent liquor sludge (TSLS) and fly ash. During the study, TSLS is fixed at 7.5% by weight, and fly ash is varied as 5%, 10%, 15%, 20% and 25% to study the possibility of replacement of cement. A 15% fly ash gives the optimum compressive strength. Addition of fly ash has resulted in complete removal of toxicity as per US EPA toxicity characteristic leaching procedure (TCLP) test. A total of 7.5% sludge and 15% fly ash in M-20 concrete is expected to save Rs. 252/m3 (≈USD 5.3/m3) of concrete.Item Trials on sludge of lime treated spent liquor of pickling unit for use in the cement concrete and its leaching characteristics(Elsiever, 2007-01) Singhal, AnupamDisposal of sludge of lime treated spent liquor pickling unit, as per the Act of Hazardous Waste (Management and Handling) Rules, 1989 is not easy. Its transportation and construction of lined disposal sites pose very severe problem. In the normal practice, sludge is being disposed off on sides of roads and railway tracks to generally fill the low-lying areas. This may cause severe health hazards. An attempt has therefore been made to utilize the treated spent liquor sludge in cement concrete. Design mix M20 has been prepared with varying concentration of sludge in the laboratory. Toxicity characteristics leaching procedure (TCLP) test as per USEPA has been carried out on cement concrete cubes.Item A study on sludge minimization during the treatment of pickling effluent(NEERI, 2006-04) Singhal, AnupamIn pickling industries, a lot of sludge is generated during the treatment of pickling effluent and there is severe problem of its disposal. Disposal of this sludge as per the Hazardous Waste (Management & Handling) Rules, 1989 is not easy. Its transportation and construction of lined disposal sites pose very severe problems. In the normal practice, the sludge is being disposed of at the sides of roads and railway tracks to fill low lying areas. This may cause serious health hazards. Considering these problems, a study has been undertaken to minimize the sludge generation during the treatment of pickling effluent by neutralizing it with lime, sodium hydroxide and combination of both. An attempt has been made to do an economic evaluation of the above process.