M. Elkordy

Laboratory experiments and modeling for industrial radiotracer applications

This paper presents three laboratory experiments, which have been carried out using the Molybdenum-99 (Mo(99)) radiotracer to measure the residence time distribution (RTD), the mixing time and the flow rate in a water flow rig. The results of the RTD measurement experiment are preprocessed using the MATLAB software for background correction, radioactive decay correction, starting point correction, filtering, and data extrapolation. After preprocessing, six mathematical models are investigated on this data using the International Atomic Energy Agency (IAEA) RTD software. The parameters of each model are optimized to calculate the value of the RTD, and to determine the model, which gives the best match with the practical data. The selected model with the best match is used to calculate the RTD in this experiment. The mixing time experiment is carried out for different rotation speeds and repeated three times in each case. The results show that the mixing time is inversely proportional to the rotation speed. The flow rate experiment is carried out to measure the flow rate in the flow rig. The experimental results show a high reliability of the radiotracer used in the RTD, mixing time and flow rate measurements.

Automatic segmentation of industrial radiographic images

Gamma radiography plays an important role in checking the quality of welded components in many industries. Determination of the region of interest (ROI) which contains only the welding area from the whole radiography image is important process for elimination of irrelevant information, leaving only the area of interest in the image. This paper presents proposed method for automatic segmentation (ROI determination) of radiographic image based on image processing techniques. ROI is determined by thresholding the image with a threshold obtained automatically. The size matrix which represents the dimensions of the weld area is automatically calculated. Grayscale, intensity, and their variances of the radiographic images are used and compared from the points of the probability of correct detection and the positive false alarm rate. Morphological operations and wavelet transform have been used for increasing the probability of detection and decreasing the false alarm. The results of the proposed method are comparing with the results of the other common methods. The results show that the proposed method is promising for automatic segmentation of welding from the radiographic image.

Enhancement of Infrared Images Based on Efficient Histogram Processing

The objective of any night vision system is to enable a person to see in the dark. A low-contrast image puts a contrast constraint on the human observer visibility at night. This is the basic reason for the large number of accidents at night. This research presents two proposed approaches to enhance the visibility of the infrared (IR) night vision images through an efficient histogram processing. The first approach is based on contrast limited adaptive histogram equalization. The second proposed approach depends on histogram matching. The histogram matching uses a reference visual image for converting night vision images into good quality images. The obtained results are evaluated with quality metrics such as entropy, average gradient, contrast improvement factor and sobel edge magnitude.

Analysis of Conductor-Backed Coplanar Waveguide using Integral Method

In this paper, an integral method for evaluating the propagation characteristics of conductor-backed coplanar wave guide structure is presented. In this method, the Helmholtez equation has been converted into integral equation using Greens second identity. The propagation constant is determined by using some basis functions. The obtained results are found to be very accurate when compared with experimental published data available in the literature. The effects of the ground metallizations on the propagation characteristics is analyzed in compared with the conventional coplanar waveguide structure

Study of Biasing Effects on Coupled Microstrip Lines Characteristics

An accurate method for evaluating the effects of biasing potential on the quasi-static even and odd mode propagation characteristics of coupled microstrip lines is given. In this method, the equivalent circuit theory simulates the quasi-static theory for the coupled microstrip lines. The depletion layer capacitance is determined using parallel plate waveguide model. The techniques used here are constructed from the standard transmission line model voltage and current as well as field lines distribution. The elements of the series branch impedance of the equivalent circuit can be found by solving for the current distribution on the conductor given the magnetic potential. The shunt admittance components are determined by using conformal transformation formulas. It is found that the bias potential has great effects on the propagation characteristics of coupled microstrip lines as well as the phase angle of microstrip phase shifter.

Study of voltage tunable SAW hybrid devices

A theoretical study of voltage tunable hybrid surface acoustic wave (SAW) devices is presented. In this study the voltage tunable carrier concentration as well as conductivity have been calculated using least square method. The piezoelectric fields of the SAW are coupled to the free carrier in the semiconductor and induced this interaction. The carrier concentration in the semiconductor is varied by biasing potential. The control of carrier concentration leads to voltage control conductivity. The tunability of the conductivity in the semiconductor results in a large change of the SAW velocity and phase. The attenuation of the SAW can be calculated in terms of the tunable conductivity. A voltage control SAW oscillators, delay line and SAW voltage sensor can be realized.

Analysis of coupled microstrip lines using integral method

In this paper, an integral method for evaluating the propagation even and odd mode characteristics of coupled microstrip lines is presented. In this method, the Helmholtez equation has been converted into integral equation using Greens second identity. The propagation constant for both modes of propagation is determined by using some basis functions. The obtained results are found to be very accurate when compared with published data available in the literature.

Characterization of Quaternary Chalcogenide As-Ge-Te-Si Thin Films

In the present paper have investigated the effect of replacement of Te by Si on the optical gap and some other physical operating parameters of a quaternary chalcogenide As 30 Ge 10 Te 60-x Si x (where x = 0, 5, 10, 12 and 20 at %) thin films. Thin films with thickness 100-200 nm of As30Ge10Te 60-xSix were prepared by thermal evaporation of the bulk samples. Increasing Si content was found to affect average heat of atomization, the average coordination number, number of constraints and cohesive energy of the As 30 Ge 10 Te 60-x Si x alloys. Optical absorption is due to allowed non-direct transition and the energy gap increases with increasing Si content. The chemical bond approach has been applied successfully to interpret the increase in the optical gap with increasing silicon content.

A space harmonic analysis of semiconductor coupled SAW convolver

We present the space harmonic analysis of the monolithic surface acoustic wave (SAW) coupled conductor convolver. In our study a moment method has been used to solve the electric field as well as charge density equations. Detailed operating characteristics of the convolver are presented. The output convolver level and efficiency are examined as a function of input signal. The optimum output level could be determining using bias potential, the obtained value shifted by 0.01V compared with published value. A comparison with published theoretical and experimental data available in the literature gives good agreement.

Study of high temperature superconducting thin film with application in microwave circuits

In this paper a numerical solution to the estimation of superconducting thin film surface impedance is presented. Integral equations are developed on the basis of Maxwell equation, Green function and two-fluid model. The solution of the integral equations gives the surface impedance of the superconducting thin film, which can be used in many applications in microwave circuits. It is found that the thin film surface impedance at microwave frequency dependent on the thickness of the substrate. A comparison with published experimental results for surface resistance is included to check the accuracy of this technique. The interaction of superconducting thin film with surface acoustic wave (SAW) in hybrid layer structure is studied as one application in microwave circuits. It is found that the results of the attenuation of SAW follow the experimental published results at the temperature transition to normal region.