Showing papers by "Nitte Meenakshi Institute of Technology published in 2009"

Investigation of Subsynchronous Resonance With VSC-Based HVDC Transmission Systems

Abstract: The HVDC converter control can destabilize torsional modes of nearby turbogenerators. The first experience of HVDC-turbine generator torsional interaction was observed in 1977 during field tests at Square Butte. The development of power semiconductors, specially insulated-gate bipolar transistors and gate turnoff thyristors (GTOs) has led to the small power HVDC transmission based on voltage-source converters (VSCs). The self-commutated VSC-based HVDC installations have several advantages compared to conventional HVDC-based online-commutated current source converter. The main objective of this paper is to investigate and present the detailed analysis of subsynchronous resonance (SSR), arising from a VSC-based HVDC system connected close to generating units. The analysis considers different operating modes of the converters. Based on a case study, it is shown that the dc voltage control mode of VSC operation (rectifier/inverter) close to the generator units can contribute positive damping in the torsional-mode frequency range of interest. The investigations of SSR with VSC-based HVDC is carried out based on linear (damping torque and eigenvalue) analysis and nonlinear transient simulation. While the damping torque, eigenvalue analysis, and controller design are based on the D-Q model, the transient simulation considers the D-Q model and the three-phase detailed model of VSC using switching functions. The influence of the operating modes of the converters and effects of some important parameters, such as effective short circuit ratio and generator rating are investigated.

Influence of rotational speed during centrifugal casting on sliding wear behaviour of the Al-2Si alloy

Abstract: The microstructures and dry sliding wear behaviour of an Al-2Si alloy cast centrifugally are studied. Results indicate that at optimum speed the cast has a microstructure consisting of uniformly distributed α-Al grains and fine eutectic silicon grains. The cast exhibited better wear resistance compared to the same cast prepared at different rpms. This paper attempts to investigate the influence of the microstructural changes in the Al-2Si alloy by varying the rotational speed of the mould and its combined action on the dry sliding wear behaviour.

Adhesion behavior of plasma sprayed thermal barrier coatings on Al-6061 and cast iron substrates

Abstract: In this work an investigation was carried out on adhesion strength and micro-hardness of plasma sprayed coatings on Al-6061 and cast iron substrate materials. For the adhesion test, ASTM C633, and for the micro hardness, ASTM E384 standards were used. From the results obtained it was found that the main failure locations were in the bond coat-substrate interface, which is considered as adhesion strength. The various parameters affecting adhesion strength are also discussed.

Shooting Method for Good Estimates of the Eigenvalue in the Rayleigh-Be´nard-Marangoni Convection Problem With General Boundary Conditions on Velocity and Temperature

Abstract: The paper presents a numerical study of RayleighBA©nard-Marangoni convection in a Newtonian liquid that is bounded on the underside by a permeable boundary and on the upperside by a free boundary. General boundary conditions arise in the study on both the velocity and temperature and hence the problem is not amenable to analytical treatment. First the singleterm Galerkin technique is used to obtain an estimate of the critical value of the Marangoni and wave numbers as a function of Rayleigh, Darcy and Biot numbers. The estimates are then improved upon by the shooting method which is based on the Runge-KuttaFehlberg and Newton-Raphson methods. The results are documented in 4 figures and a table, and some conclusions are made on comparing the present results with those of the classical Rayleigh-BA©nard, BA© nardMarangoni and Rayleigh-BA©nard-Marangoni convection problems. Copyright © 2010 by ASME.

Design of a Generic Network on Chip Frame Work Using Wormhole Routing for 2D Mesh

Abstract: The requirements of high performance mega functional solutions are becoming important day by day. With the advancement in semi conductor devices and fabrication technology, it is possible to pack more logic in smaller area of silicon. But the implementation of these mega functional modules using common bus architecture, parallel bus architecture, pipelining are becoming ineffective and posing a bottleneck in terms of performance and throughput in this billion transistor era. To overcome these performance issues, a new paradigm in interconnect technology was proposed. The proposal is to implant the concept of data transfer in data communication networks providing advantages of low power scalable high performance architecture. This can be achieved with a small increase in silicon area, for routing resources. This paper discusses the design of a generic frame work for wormhole routing strategy for 2D mesh topology. It also discusses the data transfer operation and other aspects of this frame work.

Optimizing BitTorrent performance to enable real-time downloads

Abstract: BitTorrent(BT) in recent years has emerged as the de facto protocol for sharing content over P2P networks. Although BitTorrent was created for purposes of sharing time-insensitive content, streaming is not supported. In this paper, we propose minimal changes to BT's mechanisms for supporting real-time downloads. The significance of adding such a capability to BT is that the peer will have an ability to start enjoying the video before complete download of the video files. In a nutshell, our conceptual solution-based paper modifies slightly the original BT protocol, where pieces are downloaded in an out-of-order manner based on their rareness. Our approach deals with downloading pieces in their playing order by indexing them sequentially, thus ensuring smooth playback.

Design of a generic network on chip frame work for store & forward routing for 2D mesh topology

Abstract: The need of high performaning, mega functionality solutions are becoming important day by day. The implementation of these mega functional modules which was done using common bus architecture, parallel bus architecture, pipelining are becoming ineffective and posing a bottleneck in terms of performance and throughput in this billion transistor era. To overcome these performance issues, a new paradigm in interconnect technology was proposed. The idea was to implant the concept of data transfer in data communication networks into silicon thus providing advantages of low power scalable high performing architecture with a small increase in die area for routing resources. This paper discusses the design of a generic frame work for network on chip based systems using store and forward strategy.

Ethyl 2-[(2,6-dimethyl-phen-yl)hydrazono]-3-oxobutanoate.

Abstract: The title compound, C14H18N2O3, crystallizes with two independent mol­ecules in the asymmetric unit, having closely comparable geometries. Both mol­ecules are essentially planar [maximum deviations from the mean plane of 0.069 (1) and 0.068 (1) A for the two mol­ecules] and contain an intra­molecular N—H⋯O hydrogen bond which generates a ring with graph-set motif S(6). In the crystal, the mol­ecules are linked into chains along the c axis by inter­molecular C—H⋯O hydrogen bonds, and inter­molecular C—H⋯π inter­actions are also present.