Dielectric behaviour of nano-crystalline spinel Ni0·2Ca0·8Fe2O4 and their nano-composite with polypyrrole

The spinel ferrite nano-particles of chemical composition Ni_0·2Ca_0·8Fe₂O₄ have been prepared by sol-gel method. Subsequently, the nanoparticles are encapsulated with the intrinsically conducting polymer shell of polypyrrole. The X-ray diffraction patterns confirm the single phase cubic spinel structure of the materials. To understand the dielectric properties of the materials, frequency-dependent dielectric measurement has been performed at 300 K in the range of 100 mHz to 2 MHz. On polymerization, both the dielectric strength as well the dielectric loss is significantly increased. Also, the dielectric conductivity, which arises from the electron hopping mechanism, is considerably increased on polymerization.     

Further evaluation of boric acid vis-à-vis other lubricants for cold forming applications

The effectiveness of boric acid as lubricant has been evaluated in ring forging and deep drawing operations. The elapsed lay-by time between boric acid coating preparation and forming operation has significant influence on the friction factor. Fresh surfaces provide least friction since longer lay-by time permits absorption of moisture from the environment and tend to increase friction. Forging speed has no effect on the performance of boric acid lubricant. The average of peak forces obtained with tools having different surface coatings indicated that the hardness of the coating also has no effect on the effectiveness of the boric acid lubricant.     

Performance divergence with data discrepancy: a review

With rapid increase in disease variety, the role of image segmentation has been crucial in image guided surgery. Despite having a lot of existing methods, the robustness of an algorithm remains a concern with respect to the input image variety. This paper presents a state of art segmentation algorithms of “MICCAI Grand Challenge and Conference 2007, 2008 and 2009”. These algorithms are reported to have tested on real datasets used in “MICCAI Grand Challenge 2007, 2008 and 2009”. Due to the page constraint, selected papers based on some criteria are included in this review. In this work, we have implemented and evaluated all these methods on a particular data. The objective of this paper is to exhibit the divergence in performance if the input data is varied.     

Control of ferroelectric phase transition in nano particulate NBT–BT based ceramics

Lead free relaxor NBT–BT based ceramic compositions were prepared using sol–gel method. The samples were sintered around 1140 °C for 3–4 h in the air. The characterization was done using X-ray diffraction (XRD), filed emission scanning electron microscope (FESEM), energy dispersive spectrometry (EDS), Raman, Fourier transform infrared (FTIR), dielectric and P–E loop measurements. The XRD patterns recorded at room temperature confirmed the phase formation of the samples. From FESEM micrographs, the particle sizes were estimated for calcined powders and are found to be in the range of 50–70 nm. The analysis of both Raman and FTIR spectral data of the samples also indicated the distortion of NBT lattice with the addition of Ba²⁺ and Nd³⁺ ions. It was found that the dielectric and piezoelectric properties of NBT–BT compositions beyond the morphotrophic phase boundary (MPB) are rather sensitive to the presence of tetragonal phase in addition to the rhombohedral phase. NBT ceramics exhibit a decrease in diffusive factor with increasing BT content, implying a degradation of relaxor feature leading to the normal ferroelectric nature. The ceramic samples employed in the present study exhibited variation in P–E hysteresis loops.     

Reduced Complexity Dynamic Systems Using Approximate Control Moments

This paper deals with reduction of computational complexities in dynamic systems. This paper develops a novel method of reducing complexities with use of control moments of the system. Though the proposed method is validated through channel estimation in this paper, the same can be equally applied to any other dynamic systems. Encouraging results given in this paper prove that the computational complexities can be reduced up to 10⁴ with a marginal affordable loss of performance.     

External Refining of Molten Cast Iron

Abstract

The feasibility of removing manganese and phosphorus from molten iron by treatment with polyvinyl chloride and straight hydrocarbons (paraffin wax/polythene) respectively has been examined. Simultaneous dephosphorisation and desulphurisation of cast iron melts has been tried by combined addition of polythene granules and sodium carbonate. Appreciable refining of cast iron melts occured in each of these experiments.     

The Challenges Facing Global E-Commerce

The power of Web enablement is that geographical boundaries disappear for an enterprise. Thus, an E-commerce initiative can easily become a global E-commerce initiative. Nevertheless, before conducting E-business globally, Web-enabled enterprises must consider an array of international economic, technological, social, and legal issues, which this article examines.