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The explanation of resonance given in IEEE Std C57.149-2012 to define resonance during frequency response analysis (FRA) measurements on transformers implicitly uses the conditions prevalent during resonance in a series R – L – C circuit. This dependence is evident from the two assertions made in the definition, viz., resulting in zero net reactive impedance, and, accompanied by a zero value appearing in the phase angle of the frequency response function. These two conditions are satisfied (at resonance) only in a series R – L – C circuit and certainly not in a transformer, as has been assumed in the Standard. This can be proved by considering a ladder-network model. Circuit analysis of this ladder network reveals the origin of this fallacy and proves that, at resonance, neither is the ladder network purely resistive and nor is the phase angle (between input voltage and input current) always zero. Also, during FRA measurements, it is often seen that phase angle does not traverse the conventional cyclic path from +90 ° to −90 ° (or vice versa) at all resonant frequencies. This peculiar feature can also be explained using pole-zero maps. Simple derivations, simulations and experimental results on an actual winding are presented. In summary, authors believe that this study dispels existing misconceptions about definition of FRA resonance and provides material for its correction in IEEE Std C57.149-2012. [ABSTRACT FROM AUTHOR]

The present research paper discussed the utilization of plant waste materials such as blast furnace flue dust and sludge as macro pellets and use of these macro pellets in the production of sinter. Wastes addition as pellets to the sinter modifies the productivity of the laboratory grade sinter machine as well as the better mechanical strength of sinter. At the same it also decreases the coke rate for sinter production. The maximum productivity achieved is 5t/m 2 /day at basicity 2.2(super fluxed sinter). Microstructure of the sinter of basicity 2.2 revels that it consists of re-oxidized hematite (Fe 2 O 3 ) and few magnetite (Fe 3 O 4 ) phases with some slag phase of calcium silicate(CaSiO 3 ). X-ray diffraction also confirms the presence of hematite and magnetite as the main constituents of the sinter. Although using these waste made pellets in the sintering process leads to decrease the coke consumption, simultaneously it is used as secondary raw material and at the same time it is eco-friendly also due to recirculation of hazardous wastes. [ABSTRACT FROM AUTHOR]

Abstract: Zn(bdc)(ted)0.5 is a metal–organic framework with a 3D porous structure containing intersecting channels with two different size windows. Methane adsorption isotherms were measured on this MOF at several temperatures between 88 and 103K. Unlike all other previous studies conducted on this sorbent, we observed two very distinct substeps in the isotherms, while only one such feature is reported in other studies. Possible scenarios for explaining the origin of these newly observed features are proposed. We studied the kinetics of adsorption of methane on this sorbent for isotherms measured at four temperatures. These measurements provided us with information of how equilibrium is approached as gas was added to the sorbent. We have also calculated the pore volume and the effective specific surface area for this material and have obtained the isosteric heat values for methane on this sorbent from the adsorption data. [Copyright &y& Elsevier]