A. Sharshar - Academia.edu (original) (raw)

Papers by A. Sharshar

Journal of Luminescence, 2012

Abstract We present a detailed design method of quantum dot-organic light emitting devices (QD-OL... more Abstract We present a detailed design method of quantum dot-organic light emitting devices (QD-OLED) based on microcavity model. CdTe quantum dot is used as an emissive layer for blue, green and red emissions. We have simulated the internal photoluminescence emissions of the quantum dot layer by Gaussian function based on the published experimental results. Using these simulated internal photoluminescence emissions for different quantum dot sizes we have calculated the output emissions intensities of blue, green and red lights. We have investigated the effect of changing the device geometry on the emission intensity. We found that the emission intensity is highly depends on the device geometry. On the other hand, we found that the optimizations of the device structure are different for different emissions colors.

2009 3rd European Conference on Antennas and Propagation, 2009

A novel ultra wideband stacked microstrip patch antenna (MPA) is proposed. In the new design the ... more A novel ultra wideband stacked microstrip patch antenna (MPA) is proposed. In the new design the stacked patch is larger than the excited one. The thickness of the whole antenna is small as 5.5 mm. An impedance bandwidth (VSWR≪2) of about 2.5:1 is achieved between 5.6 – 14.2 GHz when the excited patch and stacked one are co-centered at (0,0). The impedance bandwidth is improved to a ratio of 3:1 in the frequency range 5.6 –17.2 GHz when the stacked patch center is shifted to (3, 3 mm).

Cooperative Cognitive Relay Network (CCRN) is a system that is used in Cognitive Radio Network (C... more Cooperative Cognitive Relay Network (CCRN) is a system that is used in Cognitive Radio Network (CRN) to improve the spectrum utilization in which Primary Users (PUs) exploit some Secondary Users (SUs) to relay the primary traffic cooperatively. The PU needs to give out a portion of channel access time to the selected SUs for transmitting secondary data in exchange for cooperation. The analyses for the primary and secondary transmission rate are evaluated using multiple antennas at SUs. Moreover, enhancement the throughput of the primary link is done by showing the effect of increasing the number of SUs and using different types of antennas. Optimum parameter will be investigated under using multi antennas to improve the performance of PUs and SUs. This parameter is the distance between antennas at SUs which is not clarified until now in this system. The simulation results show that by exploiting multiple antennas in CCRN, the transmission rates of both PUs and SUs can be significant...

International Journal of Speech Technology

Speaker recognition is one of several biometric recognition systems owing to its high importance ... more Speaker recognition is one of several biometric recognition systems owing to its high importance in numerous applications of security and telecommunications. The key aspiration of speaker recognition systems is to know who is speaking depending on voice characteristics. This paper presents an extensive study of speaker recognition in both text-dependent and text-independent cases. Convolutional Neural Network (CNN) based feature extraction is extended to the text-dependent and text-independent speaker recognition tasks. In addition, the effect of reverberation on the speaker recognition system is addressed. All speech signals are converted into images by obtaining their spectrograms. Two proposed CNN models are presented for efficient speaker recognition from clean and reverberant speech signals. They depend on image processing concepts applied on spectrograms of speech signals. One of the proposed models is compared with a conventional Benchmark model in the text-independent scenario. The performance of the recognition system is measured by the recognition rate in the cases of clean and reverberant speech.

Menoufia Journal of Electronic Engineering Research

Reverberation is one of the effects that occur regularly in closed room due to multiple reflectio... more Reverberation is one of the effects that occur regularly in closed room due to multiple reflections. This paper investigates the result of reverberation on both male and female speech signals. This effect is reflected in pitch frequency of speech signals. This parameter is important as it is usually used for speaker identification. Hence, several methods for pitch frequency estimation are investigated and compared on clear and reverberant male and female speech signals to select the one that is not affected so much by the reverberation effect.

Advances in nano research, 2013

The induced EMF method had been used to obtain a closed form solution for open straight thin wire... more The induced EMF method had been used to obtain a closed form solution for open straight thin wires assuming a sinusoidal current distribution. This assumption is true for infinitesimally thin wires. For actual antenna problems, where the wire radius is small but finite, the assumption of sinusoidal current distribution is no longer valid, therefore this method fails especially for antenna lengths near anti-resonance. In an endeavour to overcome the limitation of the EMF method, multi-term sinusoidal current distribution is introduced, where new sinusoidal terms are assumed in addition to the conventional one. The induced EMF method is introduced for first time to get a closed form for the input impedance of closed loops. A symmetrical quadrilateral loop is shown. The wire system of this loop antenna is considered to comprise a number of actual or virtual transmission line subsections, with a characteristic impedance assigned to each subsection

Microwave and Optical Technology Letters, 2007

In this paper, we have introduced a simple microstrip patch antenna in the Ultra Wideband (UWB) f... more In this paper, we have introduced a simple microstrip patch antenna in the Ultra Wideband (UWB) frequency range of 3-10.26 GHZ with a reduced return loss as low as-26 dB. The proposed antenna is simulated using ADS (Advanced Design System), an electronic design automation software for RF, microwave, and high speed digital applications and hardware fabrication of the same has been carried out. The simulation results shows the return loss of-30 dB which is in accordance with the return loss of fabricated antenna. The results of hardware fabrication and software simulation are compared and the other simulation results such as power radiation, effective angle, directivity, gain are also found out in this paper.

Journal of …, 2010

... Z. Atlasbaf, and K. Forooraghi, Two new loaded compact planar ultrawideband antennas using d... more ... Z. Atlasbaf, and K. Forooraghi, Two new loaded compact planar ultrawideband antennas using defected ... Wang, Two novel band-notched UWB slot antennas fed by microstrip line, Progress ... Chen, D. and CH Cheng, A novel compact ultra-wideband (UWB) wide slot antenna ...

In this paper a new wideband probe-fed printed antenna with two slits is proposed and experimenta... more In this paper a new wideband probe-fed printed antenna with two slits is proposed and experimentally tested. Good agreement between the measured and simulated results has been shown. An impedance bandwidth (VSWRLt2) of about 47.5% is obtained experimentally. Further simple modifications in the antenna structure have been made and the simulated results give an impedance bandwidth of about 62%.

IEEE Transactions on Antennas and Propagation, 1984

ABSTRACT Simple closed formula is given to determine the resistive part of the loop antenna input... more ABSTRACT Simple closed formula is given to determine the resistive part of the loop antenna input impedance. An equivalent transmission line is used to determine the reactive part of the input impedance for the same loop, and the antenna in both cases may have any regular configuration. This method has proved to be accurate for a loop perimeter up to 0.5 lambda for the resistive part and up to 0.8 lambda for the reactive part.