Quantification of crustal geotherms along with their error bounds for seismically active regions of India: A Matlab toolbox

Determination of the thermo-mechanical structure of the crust for seismically active regions using available geophysical and geological data is of great importance. The most important feature of the intraplate earthquakes in the Indian region are that the seismicity occurs within the entire crust. In Latur region of India an earthquake occurred in the upper crust. In such situations, quantifying the uncertainties in seismogenic depths becomes very important. The stochastic heat conduction equation has been solved for different sets of boundary conditions, an exponentially decreasing radiogenic heat generation and randomness in thermal conductivity. Closed form analytical expressions for mean and variance in the temperature depth distribution have been used and an automatic formulation has been developed in Matlab for computing and plotting the thermal structure. The Matlab toolbox presented allows us to display the controlling thermal parameters on the screen directly, and plot the subsurface thermal structure along with its error bounds. The software can be used to quantify the thermal structure for any given region and is applied here to the Latur earthquake region of India.     

Enhancement of properties of recycled coarse aggregate concrete using bacteria

Due to rapid construction, necessity for raw materials of concrete, especially coarse aggregate, tends to increase the danger of early exhaustion of the natural resources. An alternative source of raw materials would perhaps delay the advent of this early exhaustion. Recycled coarse aggregate (RCA) plays a great role as an alternative raw material that can replace the natural coarse aggregate (NCA) for concrete. Previous studies show that the properties of RCA concrete are inferior in quality compared to NCA concrete. This article attempts to study the improvement of properties of RCA concrete with the addition of bacteria named as Bacillus subtilis. The experimental investigation was carried out to evaluate the improvement of the compressive strength, capillary water absorption, and drying shrinkage of RCA concrete incorporating bacteria. The compressive strength of RCA concrete is found to be increased by about 20% when the cell concentration of B. subtilis is 10⁶ cells/ml. The capillary water absorption as well as drying shrinkage of RCA are reduced when bacteria is incorporated. The improvement of RCA concrete is confirmed to be due to the calcium carbonate precipitation as observed from the microstructure studies carried out on it such as EDX, SEM, and XRD.     

Hindu temples: Models of a fractal universe

Hindu philosophy views the cosmos to be holonomic and self-similar in nature. According to ancient architectural tradition, Hindu temples are symbols of models of the cosmos and their form represents the cosmos symbolically.The procedures and methods used in the construction of Hindu temples bear a striking resemblance to the procedures of computer graphics, including discretization, fractalization and extensive use of recursive procedures, including self-similar iteration. The instructions given in ancient Vastu shastras (texts on architecture) work like general programmes to generate various types of temples.The paper is an attempt to draw attention to the similarities between the procedures and resulting forms in computer graphics and Hindu temple architecture and to explain the relationship that exists between the form of the temple and the concepts of Hindu philosophy. It is proposed that Hindu temples may be viewed as threedimensional fractal models and that the use of fractal geometry procedures has a special symbolic meaning in the generation of the forms of Hindu temples.     

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.     

The P-graph approach for systematic synthesis of wastewater treatment networks

Wastewater treatment consists of three or four sequential stages: preliminary, primary, secondary, and tertiary. Each stage can comprise multiple alternative technologies that can perform the same tasks with different efficiencies, operating times, and costs. Thus, we propose a systematic approach for designing wastewater treatment networks by utilizing principles of mathematical modeling and generating an exhaustive enumeration of all the possible technologies and their connections during the early stages of designing a treatment facility. Some of these structures are nonintuitive and include recycling, reprocessing, bypasses, and multiple technologies in parallel or series to remove the same contaminant. The nonintuitive structures with multiple technologies may provide a measure of resilience compared to typical heuristic designs. Thus, the combination of P-graph methodology and the sequence of treatment technologies predicted via the optimization algorithm from the maximal structure is based on holistic considerations and does not lead to suboptimal solutions.     

Enhanced photovoltaic performance of a dye sensitized solar cell with Cu/N Co-doped TiO<Subscript>2</Subscript> nanoparticles

Pure and Copper/Nitrogen (Cu/N)-codoped TiO₂ photoanodes with various Cu concentrations are prepared via sol–gel route for the photoanode application in dye-sensitized solar cells (DSSCs). All the prepared samples are characterized by X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), UV–Vis spectroscopy (UV–VIS) and Electrochemical Impedance Spectroscopy (EIS). Addition of suitable amount of Cu and N content in TiO₂ can alter its optical and electrical properties by extending absorption in the visible region and band gap reduction. The results show that some of the Ti sites are replaced by Cu atoms while O sites are occupied by N atoms. Upon adequate addition of Cu/N could lead to smaller particle size, higher specific surface area, increased dye adsorption and retarded charge carrier recombination. A significant improvement in the power conversion efficiency is observed in case of optimized 0.3 mol% Cu/N-doped TiO₂ nanoparticles (NPs) based DSSC. This optimized 0.3 mol% Cu/N-doped photoanode accomplished a best power conversion efficiency of 11.70% with a short circuit current density of 23.41 mA cm^?2 which is 41% higher than that of the pure TiO₂ photoanode based DSSC (6.82%).     

Electrochemical,Morphological and Anti-corrosive Characteristics of Pyrazine Derivatives for Mild Steel Corrosion in Aggressive Medium: A Comparative Study

The anti-corrosive characteristics of 2,5-dimethylpyrazine (2,5-DMP) and 2,6-dimethylpyrazine (2,6-DMP) on the corrosion of mild steel in 0.5 M sulfuric acid have been studied by gravimetric method and electrochemical techniques (potentiodynamic polarization, linear polarization resistance and electrochemical impedance measurement) to observe the adsorption of these pyrazine derivatives at the metal/solution interface. The results obtained have revealed that 2,5-DMP performs more efficiently in comparison with 2,6-DMP showing an efficiency of 97.12% at a concentration of 10^?2 M. The polarization curves clearly indicate that both chemicals act as a mixed-type inhibitors showing a predominance toward the cathodic reaction. Langmuir’s isotherm model was found to adequately describe the adsorption of both these inhibitors onto the mild steel surface. The calculated value of the free energy for the adsorption process, \(\Delta G^\circ_{\text{ads}}\), reveals a strong chemisorbed bond as well as a spontaneous adsorption process between the tested inhibitors and the mild steel surface. Surface morphological analysis of the MS specimens treated with these inhibitors has been conducted using energy-sispersive atomic X-ray spectroscopy. The results obtained have shown a good agreement with the results obtained from electrochemical techniques. Quantum chemical calculations have also been performed using hyperchem 8.0.6 package to supplement the findings from the preceding techniques.