Iranian Journal of Electrical and Electronic Engineering
Volume:2 Issue: 2, Apr 2006

The development of numerical techniques now permits us to analyze complex structures such as dielectric resonator filters and planar passive elements for coplanar monolithic microwave integrated circuits. In this paper, we describe a novel method for designing dielectric resonator filters. Then a Chebychev band pass filter is designed by coaxially placing high-Q TM01Q dielectric resonators in a cutoff circular waveguide. In the present work, discussions are made regarding high-Q resonators and inter-resonator coupling.

In this paper a new approach for design of class-AB current-mode square-root domain filters based on the electronically simulated translinear loop principle is presented. FG-MOS transistors that operate in strong inverted saturation region are employed for implementation of translinear loop circuit. The filter achieves immunity to body effect, low circuit complexity, large input dynamic range, and also works in low voltage compared to those reported before. With supply voltage 1.2V a dynamic range of 46dB at 1% THD is achieved. Simulation results by HSPICE confirm the validity of the proposed design technique and show high performance of the filter.

Contrast resolution and detail resolution are two important parameters in ultrasound imaging. This paper presents a new method to enhance these parameters, simultaneously. A parallel auxiliary beamformer has been employed whose weightings are such that an estimation of the leaked signal through the main beamformer is obtained. Then the output of main beamformer is modified according to the estimated leaked signal. The efficiency of our adaptive method is demonstrated by applying it over an experimental data set and provided an enhancement of about 22 percent in lateral resolution and 15-20 dB in contrast resolution. This method also has the advantages of simplicity and possibility of real time implementation.

In this paper a hybrid active DC line conditioner for fluctuations and ripples reduction in voltage and current of DC power systems is proposed. Malfunctions in operation of equipments and systems which are supplied by low quality distribution power systems are one of the main effects of DC voltage ripple. In the proposed configuration a hybrid system including series and shunt active line conditioners for ripple reduction of load voltage and source current is used. Simulation and experimental results are provided to show the performance of the proposed configuration in different states.

Medium-term modeling of electricity market has essential role in generation expansion planning. On the other hand, uncertainties strongly affect modeling and consequently, strategic analysis of generation firms in the medium term. Therefore, models considering these uncertainties are highly required. Among uncertain variables considered in the medium term generation planning, demand and hydro inflows are of the greatest importance. This paper proposes a new approach for simulating the operation of power market in medium-term, taking into account demand and hydro inflows uncertainties. The demand uncertainty is considered using Monte-Carlo simulations. Standard Deviation over Expected Profit (SDEP) of generation firms based on simulation results is introduced as a new index for analyzing the influence of the demand uncertainty on the behavior of market players. The correlation between capacity share of market players and their SDEP is also demonstrated. The uncertainty of inflow as a stochastic variable is dealt using scenario tree representation. Rational uncertainties as strategic behavior of generation firms, intending to maximize their expected profit, is considered and Nash-Equilibrium is determined using the Cournot model game. Market power mitigation effects through financial bilateral contracts as well as demand elasticity are also investigated. Case studies confirm that this representation of electricity market provides robust decisions and precise information about electricity market for market players which can be used in the generation expansion planning framework.