R. Dehghanian

[ 1 ] - A Hysteretic Two-phase Supply Modulator for Envelope Tracking RF Power Amplifiers

In this paper a two-phase supply modulator suitable for envelope tracking power amplifier is presented. The designed supply modulator has the linear assisted switching architecture. Two-phase architecture is used in order to reduce the output switching ripples. The proposed architecture uses hysteretic control instead of pulse width modulation (PWM) which significantly reduces the circuit compl...

[ 2 ] - Theorical Investigation of Linear Response for Passivated Metallic Electrode Under Potential Step (RESEARCH NOTE)

The transient response of passivated metallic electrode system under potential step was analyzed based on a linear model, and a technique for calculating the parameters characterizing the growth and dissolution of passive film was proposed. It is believed that the information which is expected to be gained from the impedance measurement can be obtained by this technique and that this technique ...

[ 3 ] - Evidence of the Potential Shift Mechanism in Crevice Corrosion (RESEARCH NOTES)

Previous research has indicated a qualitative resemblance between the current distribution along actively corroding crevice walls and currents measured in corresponding anodic polarization plots. Using detailed measurements of the potential gradient along the crevice, a semi-quantitative current distribution was calculated for the crevice wall using a double numerical differentiation method. Th...

[ 4 ] - Effect of Impressed Current on Bond Strength Between Steel Rebar and Concrete

The deterioration of bond strength between reinforcing steel and concrete as a result of impressed cathodic current with respect to the exposure time was investigated. A current in the magnitude of 3ma/ft2 (based on reinforcing rebar area) was used for a period of five years. Chemical analyses for sodium (Na+), potassium (K+) and chloride (Cl-) ions in concrete cylinders were performed as a fun...

[ 5 ] - Determination of Permeability of Concrete to Chloride Ions by Rapid Test Procedures

Methods which can be used to assess the chloride permeability of various types of concrete in a relatively short time are described. An electrical potential from 60-80 volt DC is applied either between a chloride solution ponded on a slab surface and the top of rebar mat, or between two faces at a core taken from a structure. The amount of chloride and sum of the electrical current which passes...

[ 6 ] - Polymer Impregnation of Concrete by Methyl Methacrylate and its Effects on Mechanical Properties and Corrosion of Steel in Concrete

Freezing and thawing resulting from the ingression of water into concrete causes cracking or spalling. Corrosive ions such as chloride or sulfate penetrate the concrete surface and eventually reach the reinforcing steel. This causes the steel to corrode. Because of the high maintenance and replacement costs, responsible officials should be increasingly concerned about the growing number...