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  • Author: P. Venkatesh x
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The operating cost of a radial distribution system may be minimized by reducing the amount of real power and reactive power drawn from the transmission system. Presently, real power is being priced through a market clearing scheme all over North America. Reactive power is an ancillary service and its supply would be priced appropriately in the near future through a clearing market structure. A recent US Federal Energy Regulatory Commission staff report [1] has initiated a discussion on the formulation of a reactive power market. When such a market is designed and operated, large customers (distribution corporations) will have to purchase reactive power along with real power from the transmission corporation through an independent system operator. Envisaging such a prospect, this paper proposes a new method of reconfiguring radial systems considering costs of real and reactive power while maintaining an appropriate voltage profile and level of reliable power supply. The proposed method is tested on sample test systems and reported.

Reactive power compensation is an important issue in the control of electric power system. Reactive power from the source increases the transmission losses and reduces the power transmission capability of the transmission lines. Moreover, reactive power should not be transmitted through the transmission line to a longer distance. Hence Flexible AC Transmission Systems (FACTS) devices such as static compensator (STATCOM) unified power flow controller (UPFC) and static volt-ampere compensator (SVC) are used to alleviate these problems. In this paper, a voltage source converter (VSC) based STATCOM is developed with Artificial Neural Network Controller (ANNC) and Adaptive Neuro Fuzzy Inference System(ANFIS) controllers. The conventional PI controller has more tuning difficulties while the system parameter changes, whereas a trained neural network and ANFIS controllers requires less computation time. They have the ability to generalize and can interpolate in between the training data. The ANNC and ANFIS controllers designed were tested on a 75 V, 100 VA STATCOM in real time environment via state-of-the-art of digital signal processor advanced control engineering (dSPACE) DS1104 board and it was found that ANFIS controller was producing better results than the ANNC.

Abstract

Numerical investigation for the effect of thermal stratification on MHD flow and heat transfer of dusty fluid over a vertical stretching sheet embedded in a thermally stratified porous medium in the presence of uniform heat source and thermal radiation. The governing equations for the problem were reduced in to dimensionless ordinary differential equations using suitable similarity transformations. The transformed nonlinear ordinary differential equations are numerically solved by applying efficient RungeKutta Fehlberg-45 Method with shooting technique. The effects of various flow controlling parameters such as Prandtl number, heat source/sink parameter, fluid particle interaction parameter, heat source parameter, radiation parameter on velocity and temperature distributions of both fluid and dust phases are depicted graphically. Finally, the numerical results are compared and found to be in good agreement with previously published results under special cases. The results indicate that the fluid phase velocity is always greater than that of the particle phase and thermal stratification significantly affects the surface shear stress as well as the surface heat transfer.

Abstract

An analysis has been carried out to study the effect of nonlinear thermal radiation on slip flow and heat transfer of fluid particle suspension with nanoparticles over a nonlinear stretching sheet immersed in a porous medium. Water is considered as a base fluid with dust particles along with suspended Aluminum Oxide (Al2O3) nanoparticles. Using appropriate similarity transformations, the coupled nonlinear partial differential equations are reduced into a set of coupled nonlinear ordinary differential equations. The reduced equations are then solved numerically using Runge-Kutta-Fehlberg45 order method with the help of shooting technique to investigate the impact of various pertinent parameters for the velocity and temperature fields. The obtained results are presented in tabular form as well as graphically and discussed in detail. Effect of different parameters on skin friction coefficient and Nusselt number are also discussed.

Abstract

Machining is the most widely used process in manufacturing, and tool wear plays a significant role in machining efficiency and effectiveness. There is a continuous requirement to manufacture high-quality products at a lower cost. Many past researches show that variations in tool geometry affect the cutting forces significantly. The increase in cutting forces leads to excessive vibrations in the system, giving a poor surface finish to the machined product. In this work, a 2D coupled thermo-mechanical model is developed using Abaqus/Explicit to predict the cutting forces during turning of mild steel. Johnson–Cook material model along with damage model has been used to define the material behavior. Coulomb’s friction model is considered for defining the interaction between the tool and the work piece. Metal cutting process is simulated for different sets of cutting conditions and compared with experimental results. The finite element method results correlate well with the experimental results.

Abstract

This paper aims in assessing the effect of biofuel blend such as butanol, jatropha methyl ester, soya methyl ester and rapeseed methyl ester as an additive for the aviation fuel. In addition to the blends, the nanoparticle TiO2 of 3 % is added to the biofuel. The nanoparticle mixed at the concentration of 300ppm by ultrasonication process. The fuel Jet A, B27T, J27T, S27T and R27T are investigated for combustion and emission characteristics for various throttle settings in micro gas turbine engine. Addition of additives improves the ultimate property of the fuel by reducing the kinematic viscosity. The fuel blend B27T reports 25 % increase in total static thrust and 22 % reduction in thrust specific fuel consumption. From the results it is evident that, all fuel blends showed a significant reduction in emission values owing to high oxygen content. In addition, the thermal efficiency of the B27T and J27T is improved appreciably to 30 % and 10 % higher than Jet A fuel owing to the influence of the nanoparticle TiO2. On the other hand, the emissions like CO and NOx reduced drastically up to 70 % and 45 % respectively.

Some features of a novel 90Sr-90Y generator which employs supported liquid membrane (SLM) to separate carrier-free 90Y from 90Sr present in the high level waste of the spent fuel of reactor are described. After ascertaining the purity of 90Y particularly with respect to 90Sr breakthrough, its complexation was studied with a few oxo/aza donor ligands, such as DTPA, EDTMP, DOTA, TETA and a cyclic phosphonate, CTMP. These studies were primarily carried out to adjudge the quality of the 90Y obtained from a novel 90Sr-90Y generator and ascertain its usability for labelling biomolecules such as antibodies and peptides. The DOTA complexes are most stable at 37 C in human serum; they appear to be ideal bifunctional chelating agent for use in radioimmunotherapy with 90Y.

Abstract

In this paper, two models of fiber-to-the-x (FTTx) networks are provided, one of hybrid dense wavelength division multiplexing/coarse wavelength division multiplexing (DWDM/CWDM) with high subscriber’s allocated bandwidth, and the other of hybrid ultra-dense wavelength division multiplexing/coarse wavelength division multiplexing (UDWDM/CWDM) with high network capacity. The effect of the fiber chromatic dispersion on the signal quality was demonstrated. The behavior of the network with respect to the changing of the DWDM channel spacing and the relation between the channel spacing and the system bit rate was discussed.