Knowledge-Based Approach Using Support Vector Machine for Transmission Line Distance Relay Co-ordination

In this paper, knowledge-based approach using Support Vector Machines (SVMs) are used for estimating the coordinated zonal settings of a distance relay. The approach depends on the detailed simulation studies of apparent impedance loci as seen by distance relay during disturbance, considering various operating conditions including fault resistance. In a distance relay, the impedance loci given at the relay location is obtained from extensive transient stability studies. SVMs are used as a pattern classifier for obtaining distance relay co-ordination. The scheme utilizes the apparent impedance values observed during a fault as inputs. An improved performance with the use of SVMs, keeping the reach when faced with different fault conditions as well as system power flow changes, are illustrated with an equivalent 265 bus system of a practical Indian Western Grid.

Ferrocene-Conjugated Oxidovanadium(IV) Complexes as Potent Near-IR Light Photocytotoxic Agents

Ferrocene-conjugated oxidovanadium(IV) complexes [VO(Fc-tpy)(B)](ClO4)(2) (1-4) and [VO(Ph-tpy)(dppz)](ClO4)(2) (5) as a control [Fc = (eta(5)-C5H4)Fe-II(eta(5)-C5H5), Fc-tpy = 4'-ferrocenyl-2,2':6',2 `'-terpyridine, Ph-tpy = 4'-phenyl-2,2':6',2 `'-terpyridine, B = heterocyclic base: 2,2'-bipyridine (bpy in 1), 1,10-phenanthroline (phen in 2), dipyridoquinoxaline (dpq in 3), dipyridophenazine (dppz in 4)] were prepared and their DNA binding, DNA photocleavage activity and photocytotoxicity studied. The crystal structure of [VO(Fc-tpy)(bpy)](PF6)(2)center dot 3Me(2)CO shows a vanadyl group in six-coordinate (VON5)-O-IV coordination geometry, in which Fc-tpy and bpy display tridentate meridional and bidentate N-donor axial-equatorial binding modes, respectively. The one-electron paramagnetic complexes exhibit a charge-transfer band near 590 nm in DMF. The V-IV/V-III redox couple in 1-4 appears near -0.7 V, whereas the Fc moiety shows a response near 0.6 V vs. SCE in DMF/0.1 M TBAP. The complexes are good binders to calf thymus DNA with K-b values of 10(4)-10(6) M-1. DNA melting and viscometric data suggest groove and/or partial intercalative DNA binding of the complexes. Complexes 3-5 display DNA photocleavage activity in nearIR light of 785 nm. Complex 4 shows significant photocytotoxicity in visible light (400-700 nm) in HeLa cells with low dark toxicity.

Enhanced efficiency of tri-layered dye solar cells with hydrothermally synthesized titania nanotubes as light scattering outer layer

In the present study dye sensitized solar cells (DSSCs) have been fabricated with a tri-layer photo anode consisting of hydrothermally prepared titania nano tubes (TNT) having a diameter of 9-10 nm and length of several micrometers as outer layer, P25 TiO2 powder as transparent light absorbing middle layer and a compact TiO2 inner layer to improve the adhesion of different layers on a transparent conducting oxide coated substrate. In comparison to cells fabricated using TNTs or P25 alone, the tri-layer DSSCs exhibit an enhanced efficiency of 7.15% with a current density of 17.12 mA cm(-2) under AM 1.5 illumination. The enhancement is attributed to the light scattering generated by TNTs aggregates, reduction in electron transport resistance at the TiO2/dye/electrolyte interface and an improvement in electron life-time. (c) 2012 Elsevier B.V. All rights reserved.

Switching and fault transient analysis of 765 kV transmission systems

The analysis of electromagnetic transients arising in EHV/UHV power networks gives necessary information about the possible stresses on the different network components, which will determine their proper design, limits of operation as well as their pertinent protection strategies. This paper describes the transient analysis of 765 kV EHV transmission system which is a typical expansion in Indian power grid system. Considering various conditions, switching transient and fault transient studies are carried out. A FORTRAN version of EMTP is developed, to study a practical example, then a comparison with the results available in the literature is made.

Simulation of Potential and Electric Field Profiles for transmission line Insulators

Since the end of second world war, extra high voltage ac transmission has seen its development. The distances between generating and load centres as well as the amount of power to be handled increased tremendously for last 50 years. The highest commercial voltage has increased to 765 kV in India and 1,200 kV in many other countries. The bulk power transmission has been mostly performed by overhead transmission lines. The dual task of mechanically supporting and electrically isolating the live phase conductors from the support tower is performed by string insulators. Whether in clean condition or under polluted conditions, the electrical stress distribution along the insulators governs the possible flashover, which is quite detrimental to the system. Hence the present investigation aims to study accurately, the field distribution for various types of porcelain/ceramic insulators (Normal and Antifog discs) used for high-voltage transmission. The surface charge simulation method is employed for the field computation. A comparison on normalised surface resistance, which is an indicator for the stress concentration under polluted condition, is also attempted.

Simulation of surface and volume stress for high voltage transmission insulators

The bulk of power transmission from the generating stations to the load centres is carried through overhead lines. The distances involved could span several hundreds of kilometres. To minimize line losses, power transmission over such long distances is carried out at high voltages (several hundreds of kV). A network of outdoor lines operating at different voltages has been found to be the most economical method of power delivery. The disc insulators perform dual task of mechanically supporting and electrically isolating the live phase conductors from the support tower. These insulators have to perform under various environmental conditions; hence the electrical stress distribution along the insulators governs the possible flashover, which is quite detrimental to the system. In view of this the present investigation aims to simulate the surface electric field stress on different types of porcelain/ceramic insulators; both normal and anti-fog type discs which are used for high voltage transmission/distribution systems are considered. The surface charge simulation method is employed for the field computation to simulate potential, electric field, surface and bulk/volume stress.

Enhancement of circular differential deflection of light in an optically active medium

In this letter, we investigate the circular differential deflection of a light beam refracted at the interface of an optically active medium. We show that the difference between the angles of deviation of the two circularly polarized components of the transmitted beam is enhanced manyfold near total internal reflection, which suggests a simple way of increasing the limit of detection of chiro-optical measurements. (C) 2012 Optical Society of America

Synthesis and characterization of carbon-covered alumina (CCA) supported TiO2 nanocatalysts with enhanced visible light photodegradation of Rhodamine B

The anatase phase of titania (TiO2) nano-photocatalysts was prepared using a modified sol gel process and thereafter embedded on carbon-covered alumina supports. The carbon-covered alumina (CCA) supports were prepared via the adsorption of toluene 2,4-diisocyanate (TDI) on the surface of the alumina. TDI was used as the carbon source for the first time for the carbon-covered alumina support system. The adsorption of TDI on alumina is irreversible; hence, the resulting organic moiety can undergo pyrolysis at high temperatures resulting in the formation of a carbon coating on the surface of the alumina. The TiO2 catalysts were impregnated on the CCA supports. X-ray diffraction analysis indicated that the carbon deposited on the alumina was not crystalline and also showed the successful impregnation of TiO2 on the CCA supports. In the Raman spectra, it could be deduced that the carbon was rather a conjugated olefinic or polycyclic hydrocarbons which can be considered as molecular units of a graphitic plane. The Raman analysis of the catalysed CCAs showed the presence of both the anatase titania and D and G band associated with the carbon of the CCAs. The scanning electron microscope micrographs indicated that the alumina was coated by a carbon layer and the energy dispersive X-ray spectra showed the presence of Al, O and C in the CCA samples, with the addition of Ti for the catalyst impregnated supports. The Brunauer Emmet and Teller surface area analysis showed that the incorporating of carbon on the alumina surface resulted in an increase in surface area, while the impregnation with TiO2 resulted in a further increase in surface area. However, a decrease in the pore volume and diameter was observed. The photocatalytic activity of the nanocatalysts was studied for the degradation of Rhodamine B dye. The CCA-TiO2 nanocatalysts were found to be more photocatalytically active under both visible and UV light irradiation compared to the free TIO2 nanocatalysts.

Surface electrode switching of a 16-electrode wireless EIT system using RF-based digital data transmission scheme with 8 channel encoder/decoder ICs

A Radio Frequency (RF) based digital data transmission scheme with 8 channel encoder/decoder ICs is proposed for surface electrode switching of a 16-electrode wireless Electrical Impedance Tomography (EIT) system. A RF based wireless digital data transmission module (WDDTM) is developed and the electrode switching of a EIT system is studied by analyzing the boundary data collected and the resistivity images of practical phantoms. An analog multiplexers based electrode switching module (ESM) is developed with analog multiplexers and switched with parallel digital data transmitted by a wireless transmitter/receiver (T-x/R-x) module working with radio frequency technology. Parallel digital bits are generated using NI USB 6251 card working in LabVIEW platform and sent to transmission module to transmit the digital data to the receiver end. The transmitter/receiver module developed is properly interfaced with the personal computer (PC) and practical phantoms through the ESM and USB based DAQ system respectively. It is observed that the digital bits required for multiplexer operation are sequentially generated by the digital output (D/O) ports of the DAQ card. Parallel to serial and serial to parallel conversion of digital data are suitably done by encoder and decoder ICs. Wireless digital data transmission module successfully transmitted and received the parallel data required for switching the current and voltage electrodes wirelessly. 1 mA, 50 kHz sinusoidal constant current is injected at the phantom boundary using common ground current injection protocol and the boundary potentials developed at the voltage electrodes are measured. Resistivity images of the practical phantoms are reconstructed from boundary data using EIDORS. Boundary data and the resistivity images reconstructed from the surface potentials are studied to assess the wireless digital data transmission system. Boundary data profiles of the practical phantom with different configurations show that the multiplexers are operating in the required sequence for common ground current injection protocol. The voltage peaks obtained at the proper positions in the boundary data profiles proved the sequential operation of multiplexers and successful wireless transmission of digital bits. Reconstructed images and their image parameters proved that the boundary data are successfully acquired by the DAQ system which in turn again indicates a sequential and proper operation of multiplexers as well as the successful wireless transmission of digital bits. Hence the developed RF based wireless digital data transmission module (WDDTM) is found suitable for transmitting digital bits required for electrode switching in wireless EIT data acquisition system. (C) 2011 Elsevier Ltd. All rights reserved.

Influence of anion on the quadratic nonlinearity and depolarization ratios of scattered second harmonic light from cation-pi complexes

We have investigated quadratic nonlinearity (beta(HRS)) and linear and circular depolarization ratios (D and D', respectively) of a series of 1:1 complexes of tropyliumtetrafluoroborate as a cation and methyl-substituted benzenes as pi-donors by making polarization resolved hyper-Rayleigh scattering measurements in solution. The measured D and D' values are much lower than the values expected from a typical sandwich or a T-shaped geometry of a complex. In the cation-pi complexes studied here, the D value varies from 1.36 to 1.46 and D' from 1.62 to 1.72 depending on the number of methyl substitutions on the benzene ring. In order to probe it further, beta, D and D' were computed using the Zerner intermediate neglect of differential overlap-correction vector self-consistent reaction field technique including single and double configuration interactions in the absence and presence of BF4- anion. In the absence of the anion, the calculated value of D varies from 4.20 to 4.60 and that of D' from 2.45 to 2.72 which disagree with experimental values. However, by arranging three cation-pi BF4- complexes in a trigonal symmetry, the computed values are brought to agreement with experiments. When such an arrangement was not considered, the calculated beta values were lower than the experimental values by more than a factor of two. This unprecedented influence of the otherwise ``unimportant'' anion in solution on the beta value and depolarization ratios of these cation-pi complexes is highlighted and emphasized in this paper. (C) 2012 American Institute of Physics. http://dx.doi.org/10.1063/1.4716020]