Extraction of potash values from pyrophyllite mine waste

A waste sample generated during the mining of pyrophyllite ore is characterized for the extraction of potash values. Mineral liberation analysis (MLA) reveals that the waste material consists of muscovite, K-Feldspar (orthoclase), and pyrophyllite as the major mineral phases. The sample contains 49.5% SiO_2, 23.9% Al₂O_3, 1.8% Fe₂O₃, and 9.8% K₂O as its prime constituents. An effort has been made for the extraction of potash value by physical and chemical beneficiation techniques. Beneficiation studies using magnetic separation, froth flotation, and even chemical leaching with inorganic acids could not extract any appreciable potash values. Finally, a roast leach method using calcium chloride followed by leaching in water has been employed. The process variables such as calcium chloride dosage, roasting time, and temperature are optimized using L9 Taguchi statistical design. It has been possible to achieve about 85% potash values at 900°C, 45 minutes of roasting time and calcium chloride dosage of 75% with respect to the ore. The change in mineral phases in the feed, roast, and leached residue has been characterized by X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), which shows the phase conversion into wollastonite and halite potassian.     

Performance analysis of distributed underwater wireless acoustic sensor networks systems in the presence of internal solitons

In this paper, we have analyzed the performance of distributed Underwater Wireless Acoustic Sensor Networks (UWASNs) in the presence of internal solitons in the ocean. Internal waves commonly occur in a layered oceanic environment having differential medium density. So, in a layered shallow oceanic region, the inclusion of the effect of internal solitons on the performance of the network is important. Based on various observations, it is proved that nonlinear internal waves, that is, solitons are one of the major scatterers of underwater sound. If sensor nodes are deployed in such type of environment, internode communication is affected because of the interaction of wireless acoustic signal with these solitons, as a result of which network performance is greatly affected. We have evaluated the performance of UWASNs in the 3‐D deployment scenario of nodes, in which source nodes are deployed in the ocean floor. In this paper, four performance metrics, namely, Signal‐to‐interference‐plus‐noise‐ratio (SINR), bit error rate (BER), Delay (DELAY), and energy consumption are introduced to assess the performance of UWASNs. Simulation studies show that in the presence of internal solitons, SINR decreases by approximately 10%, BER increases by 17%, delay increases by 0.24%, and energy consumption per node increases by 53.05%, approximately. Copyright © 2014 John Wiley & Sons, Ltd.     

Energy and exergy analyses of an integrated biomass gasification combined cycle employing solid oxide fuel cell and organic Rankine cycle

In this study, an advanced combined cycle-based power generation system, integrating biomass gasification with a solid oxide fuel cell (SOFC) module and an organic vapor turbine, has been modeled and analyzed. The thermodynamic model has been developed by integrating the component models through customized codes written using engineering equation solver software. Both energetic and exergetic analyses of the proposed system have been conducted under varying design and operating parameters to assess their effects on the performance of the proposed system. The study reveals that the integrated system yields a maximum overall energetic efficiency of 41.13%, occurring at a pressure ratio of 2.5 for the compressor. The gasifier is the component responsible for maximum exergy destruction (accounting for 32.36% of fuel exergy input), followed by the heat recovery vapor generator and the SOFC.     

Granular micromechanics model of anisotropic elasticity derived from Gibbs potential

This paper presents a Gibbs potential-based granular micromechanics approach capable of modelingmaterialswith complete anisotropy. The deformation energy of each grain–pair interaction is taken as a functionof the inter-granular forces. The overall classical Gibbs potential of a material point is then defined as thevolume average of the grain–pair deformation energy. As a first-order theory, the inter-granular forces arerelated to the Cauchy stress tensor using a modified static constraint that incorporates directional distributionof the grain–pair interactions. Further considering the conjugate relationship of the macroscale strain tensorand the Cauchy stress, a relationship between inter-granular displacement and the strain tensor is derived.To establish the constitutive relation, the inter-granular stiffness coefficients are introduced considering theconjugate relation of inter-granular displacement and forces. Notably, the inter-granular stiffness introducedin this manner is by definition different from that of the isolated grain–pair interactive. The integral formof the constitutive relation is then obtained by defining two directional density distribution functions; onerelated to the average grain–scale combined mechanical–geometrical properties and the other related to purelygeometrical properties. Finally, as the main contribution of this paper, the distribution density function isparameterized using spherical harmonics expansion with carefully selected terms that has the capability ofmodeling completely anisotropic (triclinic) materials. By systematic modification of this distribution function,different elastic symmetries ranging from isotropic to completely anisotropic (triclinic) materials are modeled.As a comparison, we discuss the results of the present method with those obtained using a kinematic assumptionfor the case of isotropy and transverse isotropy, wherein it is found that the velocity of surface quasi-shearwaves can show different trends for the two methods.     

Outdoor Path Loss Predictions Based on Extreme Learning Machine

Wireless Personal Communications - In a typical outdoor environment, the propagation of radio waves is usually random in nature, to the extent that the characterization of the wireless...     

Surface ultrastructure of larval mouthpart sensilla of the muga silkmoth,Antheraea assamensis,an endemic species of North‐East India

Scanning electron microscopy of different larval stages of the muga silk moth Antheraea assamensis revealed the presence of sensilla chaetica, sensilla trichoidea, sensilla styloconica, gustatory sensilla, sensory pegs, placoid sensilla, etc., on their mouth parts. Some variations were observed in the number and sub‐types of sensilla in certain larval stages indicating some differences in sensitivity of the worms in different instars to the food plant and microhabitat. Microsc. Res. Tech., 2010. © 2010 Wiley‐Liss, Inc.