Effects of Single Phase ACDC Converter Drive on the[taliem.ir]

Effects of Single Phase AC/DC Converter Drive on the Torque-Speed Characteristic of DC Motor

This paper describes a MATLAB/Simulink realization of the DC motor speed control method by controlling the voltage applied to the armature circuit using single phase AC/DC converter drive. A comparison between the application of single phase semi converter and single phase full converter is presented. Torque-speed characteristics are obtained for different values of firing angle to demonstrate its effect on the linearity of the characteristic.
Asymmetric gain-saturated spectrum in fiber[taliem.ir]

Asymmetric gain-saturated spectrum in fiber optical parametric amplifiers

We demonstrate experimentally and numerically an unexpected spectral asymmetry in the saturated-gain spectrum of single-pump fiber optical parametric amplifiers. The interaction between higher-order fourwave mixing products and dispersive waves radiated as an effect of thirdorder dispersion influences the energy transfer to the signal, depending on its detuning with respect to the pump, and breaks the symmetry of the gain expected from phase-matching considerations in unsaturated amplifiers. The asymmetry feature of the saturated spectrum is shown to particularly depend on the dispersion characteristics of the amplifier and shows local maxima for specific dispersion values .

Dynamic Voltage Restorer Based on Load Condition

Dynamic voltage restorers (DVR) can provide the most commercial solution to mitigation voltage sag by injecting voltage as well as power into the system. The mitigation capability of these devices is mainly influenced by the maximum load; power factor and maximum voltage dip to be compensated. Maximum load on a feeder is an important task for DVR system operation and appropriate desired voltage sag compensation. This paper is intended to assimilate the amount of DC energy storage depends on the installed load. It is available in a convenient manner for DVR power circuit.
Low Thermal Budget Monolithic Integration of[taliem.ir]

Low Thermal Budget Monolithic Integration of Evanescent-Coupled Ge-on-SOI Photodetector on Si CMOS Platform

The design and fabrication of a monolithically integrated evanescent-coupled Ge-on-silicon-on-insulator (SOI) photodetector and CMOS circuits were realized on common SOI platform using an “electronic-first and photonic-last” integration approach. High-performance detector with an integrated Si waveguide was demonstrated on epitaxial Ge-absorbing layer selectively grown on an ultrathin SOI substrate. Performance metrics of photodetector designs featuring vertical and lateral PIN configurations were investigated. When operated at a bias of -1.0 V, a vertical PIN detector achieved a lower Idark of ∼0.57 µA as compared to a lateral PIN detector, a value that is below the typical ∼1 µA upper limit acceptable for high-speed-receiver design. Very high responsivity of ∼0.92 A/W was obtained in both detector designs for a wavelength of 1550 nm, which corresponds to a quantum efficiency of ∼73%. Impulse response measurements showed that the vertical PIN detector gives rise to a smaller full-width at half-maximum of ∼24.4 ps over a lateral PIN detector, which corresponds to a -3 dB bandwidth of ∼11.3 GHz. RC time delay is shown to be the dominant factor limiting the speed performance. Eye patterns (pseudorandom binary sequence 27–1) measurement further confirms the achievement of high-speed and low-noise photodetection at a bit rate of 8.5 Gb/s. Excellent transfer and output characteristics have also been achieved by the integrated CMOS inverter circuits in addition to the well-behaved logic functions. The introduction of an additional thermal budget (800 ◦C) arising from the Ge epitaxy growth has no observable detrimental impact on the short-channel control of the CMOS inverter circuit. In addition, we describe the issues associated with monolithic integration and discuss the potential of Ge-detector/Si CMOS receiver for future optical communication applications.
Experimental and Theoretical Analysis of Vacuum[taliem.ir]

Experimental and Theoretical Analysis of Vacuum Circuit Breaker Prestrike Effect on a Transformer

The work presented in this paper deals with the investigation of circuit breaker prestrike effect that occurs during energizing a distribution transformer. An experimental test setup that consists of a supply transformer, a vacuum circuit breaker (VCB), a cable and a test transformer is built, and the prestrikes in the VCB are recorded. The test transformer is a prototype distribution transformer, with installed measuring points along transformer windings in each phase. Voltage oscillations are measured along the windings and transformer terminals. The transformer is modeled by lumped parameters extracted from telegrapher’s equations in discrete form. Voltage oscillations during switching-in operations are recorded and calculated with and without a cable installed between the VCB and the transformer. Computed voltages show good agreement with the measured voltages. Described method can be used by transformer manufacturers to estimate voltage wave forms during switching or lightning, to provide useful information for insulation coordination studies, and to investigate resonance effects in transformer windings.
Efficient Design of a Hybrid Adder Using[taliem.ir]

Efficient Design of a Hybrid Adder Using Quantum-Dot Cellular Automata

The saying goes that if you can count, you can control. Addition is a fundamental operation for any digital system, digital signal processing or a control system. A fast and accurate operation of a digital system is greatly influenced by the performance of resident adders. In this regard, an efficient hybrid adder that combines a carry select adder and a ripple carry adder using QCA technology is designed to meet all the needs that is indispensable for a digital circuitry. QCA is an emerging nanotechnology, with the potential for higher speed, smaller size, and lower power consumption than transistor-based technology. Recent development in nano electronics provides a good introduction to the quantum mechanics of electrons, notions of free and confined electrons. Hence, with the help of QCA technology, the proposed hybrid adder produces a lesser area-delay product when compared to the previous adders and this proposed adder is also applied to a Wallace tree multiplier, here the area-delay product is reduced and speed of the multiplier is augmented.
Optimized Design Considering the Mass Influence of an Axial[taliem.ir]

Optimized Design Considering the Mass Influence of an Axial Flux Permanent-Magnet Synchronous Generator With Concentrated Pole Windings

In this paper, the efficiency optimization of an axial flux permanent-magnet synchronous generator with concentrated pole windings is examined for a 3.6 kW/2000 rpm combined heat and power application. Because the efficiency of the machine is important, specific measures are taken in order to reduce losses in the machine: thin laminated grain oriented material in the teeth, concentrated pole windings, and segmented magnets. A study of the influence of a limited set of geometry parameters on the efficiency of this type of machine is done, using both analytical and finite-element methods. In the analytical as well as in the finite- element model, the inherent 3-D geometry of the axial flux machine is approximated by multiple 2-D models at different radii in circumferential direction. Afterwards, the influence of mass on the optimal values of the geometry parameters and the efficiency is considered, and it is found that mass can be seriously decreased with only a small reduction in efficiency. Finally, the results of both methods are compared with measurements on a prototype to evaluate their validity.
Direct Active and Reactive Power Regulation of[taliem.ir]

Direct Active and Reactive Power Regulation of DFIG Using Sliding-Mode Control Approach

This paper presents a new direct active and reactive power control (DPC) of grid-connected doubly fed induction generator (DFIG)-based wind turbine systems. The proposed DPC strategy employs a nonlinear sliding-mode control scheme to directly calculate the required rotor control voltage so as to eliminate the instantaneous errors of active and reactive powers without involving any synchronous coordinate transformations. Thus, no extra current control loops are required, thereby simplifying the system design and enhancing the transient performance. Constant converter switching frequency is achieved by using space vector modulation, which eases the designs of the power converter and the ac harmonic filter. Simulation results on a 2-MW grid-connected DFIG system are provided and compared with those of classic voltage-oriented vector control (VC) and conventional lookup table (LUT) DPC. The proposed DPC provides enhanced transient performance similar to the LUT DPC and keeps the steady-state harmonic spectra at the same level as the VC strategy.
Transmission and Generation Expansion Planning[taliem.ir]

Transmission and Generation Expansion Planning Considering Loadability Limit Using Game Theory & ANN

Transmission and generation expansion planning (TEP and GEP) considering loadability limit of power system is studied in this paper. Artificial neural network (ANN) technique is used to evaluate loadability limit of the power system because of its sensitivity characteristic. Power system restructuring and separation of decision-making organizations of transmission and generation expansion, make coordination between generation and transmission companies more crucial. On the other hand, voltage stability is one of the indicators of power system security level. In this paper, first the load pattern of a six-bus power system is improved and then the best bus for load increment is determined using sensitivity characteristic of ANN. Afterwards the strategic interaction between transmission company (TransCo) and generation company (GenCo) for TEP and GEP in a competitive electricity market is proposed using Game Theory (GT). The proposed algorithm comprises three optimization levels to determine Nash equilibrium such that the most profitable strategy for both sides of the game can be found out in an expansion planning game.
Development of a generic multipurpose tokamak plasma discharge flight simulator[taliem.ir]

Development of a generic multipurpose tokamak plasma discharge flight simulator

The operation of present day tokamak and future machine like ITER is more and more demanding in terms of plasma control both for increasing plasma performance, stability and ensuring machine protection. Additionally saving experimental time by validating the pre-programmed plasma scenario through a simulator is also of major importance. These issues highlight the necessity to build new tools such as a generic multipurpose plasma discharge flight simulator. Such a project has been recently started at CEA and is based on the integrated tokamak modeling task force formalism and simulation platform. The paper reports on the present status of the project, reviewing in particular the needs for new tool development, the architecture of the generic multipurpose tokamak plasma discharge flight simulator, with the different software/hardware interfaces. A first test case of this tool in the “full simulation” modes and using the European simulation platform is discussed.