66 research outputs found

    Power Transfer Capability & Reliability Improvement in a Transmission Line using Distributed Power- Flow Controller

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    The Distributed Power Flow Controller (DPFC) is derived from the Unified power-flow controller (UPFC).The DPFC is a solution to control the power flow in a single transmission line. By eliminating the common DC link and distributing the three phase series converters of the UPFC, a new concept of the Distributed Power Flow Controller (DPFC) is achieved. The active power exchange between the two converters, which is through the common dc link in the UPFC, is now through the transmission lines at the third-harmonic frequency in the DPFC. It inherits the advantages of the UPFC and the DFACTS concept, which allow power flow control for multi-line systems with relatively low cost and high reliability without additional cost. This paper presents two types of DPFCs; one is one three phase shunt converter and four three phase series converters. Another model is one three phase shunt converter and nine single phase series converters. By using three phase series converters, no common dc link between shunt and series converters but cost will increases. By using single phase series converters, no common dc link between shunt and series converters and cost also decreases. Detailed simulations are carried out on two- machine systems to illustrate the control features of these devices and their influence to increase power transfer capability and every series converter consists of D-FACTS concept so Reliability also improves because failure of series converters does not effect.DOI:http://dx.doi.org/10.11591/ijece.v2i4.35

    N-{1-[(3-Bromo­prop­yl)amino­carbon­yl]eth­yl}-2-(2-nitro­benzene­sulfonamido)propionamide

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    In the title compound, C15H21BrN4O6S, all three NH groups are involved in inter­molecular N—H⋯O inter­actions which, together with two inter­molecular C—H⋯O contacts, lead to a continuous anti­parallel β-sheet structure. There are no π–π inter­actions between mol­ecules, and two C—H⋯π inter­actions primarily govern the linkage between sheets

    Kinetic nanofriction: a mechanism transition from quasi-continuous to ballistic-like Brownian regime

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    Surface diffusion of mobile adsorbates is not only the key to control the rate of dynamical processes on solid surfaces, e.g. epitaxial growth, but also of fundamental importance for recent technological applications, such as nanoscale electro-mechanical, tribological, and surface probing devices. Though several possible regimes of surface diffusion have been suggested, the nanoscale surface Brownian motion, especially in the technologically important low friction regimes, remains largely unexplored. Using molecular dynamics simulations, we show for the first time, that a C60 admolecule on a graphene substrate exhibits two distinct regimes of nanoscale Brownian motion: a quasi-continuous and a ballistic-like. A crossover between these two regimes is realized by changing the temperature of the system. We reveal that the underlying physical origin for this crossover is a mechanism transition of kinetic nanofriction arising from distinctive ways of interaction between the admolecule and the graphene substrate in these two regimes due to the temperature change. Our findings provide insight into surface mass transport and kinetic friction control at the nanoscale

    Rock Magnetic properties of Proterozoic mafic dykes from the Southern margin of Cuddapah Basin

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    Seventeen basic dykes of Proterozoic age intruding the Archaean basement from the Southern margin of the Cuddapah Basin were studied from five sites for their magnetic characters. NRM intensity (Jn) of the dykes range between 1793 and 57×10−3 Am−1 while magnetic susceptibility (χ) ranges from 31 to 303×10−6 CGS units. Koenigsberger's ratio (Qn) varies from 1 to 55 for most of the specimens. All the above parameters are indicative of retaining the original magnetization in most of the dykes sampled. Based on the above mentioned rock magnetic properties along with hysterisis studies and low temperature (−196°C) magnetic studies, it is inferred that the main magnetic carrier in these dykes is magnetite in multi domain and mixed domain states. Dykes from Tirupati area seems to be magnetically altered

    Aegle marmelos fruit extract attenuates isoproterenol-induced oxidative stress in rats

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    Myocardial infarction is a major public health concern and the leading cause of death throughout the world. The present study investigates the ability of Aegle marmelos fruit extract to prevent pathological changes and oxidative stress after isoproterenol induced myocardial infarction in rats. In vitro studies showed that Aegle marmelos fruit extract possesses antioxidant activity. Administration of isoproterenol (85 mg/kg body weight) to rats resulted in significantly elevated plasma transaminases, lactate dehydrogenase and creatine kinase, however, cardiac tissue analyses showed decreased activity of the above enzymes compared to experimental control rats. Further, isoproterenol administration significantly increased plasma and cardiac tissue thiobarbituric acid reactive substances and lowered the activities of cardiac tissue superoxide dismutase, catalase, reduced glutathione, glutathione peroxidase and glutathione-S-transferase when compared to control groups. Pretreatment with Aegle marmelos fruit extract at a dose of 150 mg/kg body weight for a period of 45 days significantly prevented the observed alterations. Our data suggest that Aegle marmelos fruit extract exerts its protective effect by decreasing thiobarbituric acid reactive substances and elevating antioxidants status in isoproterenol treated rats. Both biochemical and histopathological results in the isoproterenol-induced myocardial infarction model emphasize the beneficial action of Aegle marmelos fruit extract as a cardioprotective agent

    Numerical studies on elastic properties of graphene sheets and free vibration of carbon nanotubes by atomistic simulation and equivalent continuum modelling

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    The present research deals with determination of elastic properties of finite graphene sheets and CNTs by equivalent continuum modelling, and free vibration analysis of plain as well as fluid conveying CNTs by atomistic modelling of stiffness and mass properties.DOCTOR OF PHILOSOPHY (MPE

    Behavior of continuous filament advanced composite isogrid structure

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    Ph.D.Lawrence W. Rehfiel

    Synthesis and Isolation of 5,6-Dihydro-4H-1,3-Oxazine Hydrobromides by Autocyclization of N-(3-Bromopropyl)amides

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    5,6-Dihydro-4H-1,3-oxazine hydrobromides have been synthesized by the nucleophilic autocyclo-O-alkylation of N-(3-bromopropyl)amides under neutral conditions in chloroform. It is found that electron-donating amide alpha-substituents influence the autocyclization efficiency

    Steric and Electronic Interactions Controlling the cis/trans Isomer Equilibrium at X-Pro Tertiary Amide Motifs in Solution

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    A systematic understanding of the noncovalent interactions that influence the structures of the cis conformers and the equilibrium between the cis and the trans conformers, of the X-Pro tertiary amide motifs, is presented based on analyses of H-1-, C-13-NMR and FTIR absorption spectra of two sets of homologous peptides, X-Pro-Aib-OMe and X-Pro-NH-Me (where X is acetyl, propionyl, isobutyryl and pivaloyl), in solvents of varying polarities. First, this work shows that the cis conformers of any X-Pro tertiary amide motif, including Piv-Pro, are accessible in the new motifs X-Pro-Aib-OMe, in solution. These conformers are uniquely observable by FTIR spectroscopy at ambient temperatures and by NMR spectroscopy from temperatures as high as 273 K. This is made possible by the persistent presence of n(i-1i)* interactions at Aib, which also influence the disappearance of steric effects at these cis X-Pro rotamers. Second, contrary to conventional understanding, the energy contribution of steric effects to the cis/trans equilibrium at the X-Pro motifs is found to be nonvariant (0.54 +/- 0.02 kcal/mol) with increase in steric bulk on the X group. Third, the current studies provide direct evidence for the weak intramolecular interactions namely the n(i-1i)*, the N-Pro center dot center dot center dot Hi+1 (C(5)a), and the C-7 hydrogen bond that operate and influence the structures, stabilities, and dynamics between different conformational states of X-Pro tertiary amide motifs. NMR and IR spectral data suggest that the cis conformers of X-Pro motifs are ensembles of short-lived rotamers about the C-X-N-Pro bond. (c) 2013 Wiley Periodicals, Inc. Biopolymers 101: 66-77, 2014
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