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  • Author: Mohamed A. Youssef x
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Ahmed A. Elashiry, Mohamed A. Youssef and Mohamed A. Abdel Hamid

Abstract

There are three well-established detecting methods for cycle slip error, which are: Doppler measurement method, Phase-Code differencing method, and Phase-Phase Differencing Method. The first method depends on the comparison between observables and the fact that Doppler measurements are immune to cycle slip error. This method is considered as the most precise method for cycle slip detecting, because it succeed in detecting and predicting the smallest cycle slip size (1 cycle) in case the local oscillator has low bias. The second method depends on the comparison between observables (phase and code) and the code measurements are immune to the cycle slip error. But this method can’t detect or predict cycle slip size smaller than 10 cycles, because the code measurements have high noise. The third method depends on the comparison between observables (phase 1 and phase 2) and the phases measurements that have low noise. But this method can’t detect or predict cycle slip size smaller than 5 cycles, because the ionospheric change might have a high variation.

For enhancing the precision of the last two methods in detecting the smallest cycle slip which size reaches 1 cycle, a new algorithm was developed in this research to determine the change in the ionospheric values and the code bias from epoch to epoch. That is done by solving all observables equations by least square technique. This modification on these methods succeed in detecting and predicting cycle slips of size of 1 cycle.

Open access

Ahmed Youssef Altonbary, Gamal Elsayed Shiha, Monir Hussein Bahgat and Seham Mohamed Seif

Abstract

Thoracic aortic thrombus is a rare condition with only approximately 100 cases reported. Typically, this phenomenon is only diagnosed after symptomatic embolization. A 70 years old male was presented to our hospital with obstructing pancreatic head mass for endoscopic ultrasound (EUS). At the time of hospitalization there were no symptoms or signs suggesting thrombo-embolism or organ ischemia. During EUS examination, asymptomatic descending thoracic aorta thrombosis was discovered accidentally.

Open access

M. Abo-Youssef, A. El Sabagh, G. Abo-Gendy and A. Mohamed

Abstract

The purpose of this study was to identify the optimum levels of gibberellic acid and suitable row ratio for maximization the seed yield of hybrid rice. An experiment was conducted at the experimental farm of Rice Research and Training Center, Egypt, during 2013 and 2014 growing seasons. The material under this study included the parental lines of IR69625A (Female lines) and Giza 179 R (Restorer line) to produce F0 hybrid seeds. A split-plot design with three replications was used. The main plot was row ratio (2R:8A, 2R:10A and 2R:12A) and sub plots was the doses of gibberellic acid (g/ha) (control, 300, 350, 400). The results indicated that, Application of GA3 and row ratio had significant effect on different traits of seed yield and hybrid seed production. The highest values of flag leaf area, panicle length, seed set, panicle weight, panicle exsertion and seed yield were acheived by using 2R: 8A row ratio and was observed the lowest values were obtained at the 2:12 row ratio. Acoording to gibberellic acid application, the highest values for panicle length (cm), seed set (%), panicle weight (g), panicle exertion (%), harvest index and seed yield were recorded by using 400 g /ha gibberellic acid. Accordingly, the highest net economic return from seed yield was obtained with the treatment combination of 400 g/ha GA3 x 2:8 (R: A) row ratio.