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RISS 인기검색어
- 검색키워드
- 저자 : R.M. El-Kady (검색결과 2 건)
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Effect of perforation patterns on the fundamental natural frequency of microsatellite structure
Ahmad M. Baiomy,M. Kassab,B.M. El-Sehily,R.M. El-Kady Techno-Press 2023 Advances in aircraft and spacecraft science Vol.10 No.3
There is a burgeoning demand for minimizing the mass of satellites because of its direct impact on reducing launch-to-orbit cost. This must be done without compromising the structure's efficiency. The present paper introduces a relatively low-cost and easily implementable approach for optimizing structural mass to a maximum natural frequency. The natural frequencies of the satellite are of utmost pertinence to the application requirements, as the sensitive electronic instrumentation and onboard computers should not be affected by the vibrations of the satellite structure. This methodology is applied to a realistic model of Al-Azhar University micro-satellite in partnership with the Egyptian Space Agency. The procedure used in structural design can be summarized in two steps. The first step is to select the most favorable primary structural configuration among several different candidate variants. The nominated variant is selected as the one scoring maximum relative dynamic stiffness. The second step is to use perforation patterns reduce the overall mass of structural elements in the selected variant without changing the weight. The results of the presented procedure demonstrate that the mass reduction percentage was found to be 39% when compared to the unperforated configuration that had the same plate thickness. The findings of this study challenge the commonly accepted notion that isogrid perforations are the most effective means of achieving the goal of reducing mass while maintaining stiffness. Rather, the study highlights the potential benefits of exploring a wider range of perforation unit cells during the design process. The study revealed that rectangular perforation patterns had the lowest efficiency in terms of modal stiffness, while triangular patterns resulted in the highest efficiency. These results suggest that there may be significant gains to be made by considering a broader range of perforation shapes and configurations in the design of lightweight structures.
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Accuracy of Sentinel Node in Detecting Lymph Node Metastasis in Primary Endometrial Carcinoma
Farghali, Mohamed M,Allam, Ihab S,Abdelazim, Ibrahim A,El-Kady, Osama S,Rashed, Ahmed R,Gareer, Waheed Y,Sweed, Mohammed S Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.15
Background: Endometrial carcinoma is the most common gynecological cancer and its treatment is still controversial, especially in its early stages. There are conflicting data about the efficacy of retroperitoneal lymphadenectomy during abdominal hysterectomy and bilateral salpingoophrectomy treatment. Lymphadenectomy carries a risk of severe complications, especially in women with co-morbidities. Selective lymphadenectomy has been widely employed for staging evaluation of endometrial carcinoma because it is simple and seems to provide reliable data regarding nodal metastasis. This study was designed to evaluate accuracy of sentinel node sampling in detecting lymph node metastasis in primary endometrial carcinoma during staging laparotomy. Materials and Methods: Ninety-three women with endometrial carcinoma at high-risk for nodal metastasis were studied. During laparotomy, methylene blue dye was injected into sub-serosal myometrium, then retroperitoneal spaces were opened and blue lymph nodes within pelvic and para-aortic regions were removed as separate specimens for histopathological examination (sentinel lymph nodes = SLNs). Hysterectomy and selective lymphadenectomy then performed for all women included in this study. Results: Deposition of methylene dye into at least one lymph node was observed in 73.1% (68/93) of studied cases. 18.3% (17/93) of studied women had positive lymph node metastasis and 94.1% (16/17) of them had positive metastasis in SLNs. In this study, SNLs had 94.4% sensitivity and 100% specificity in prediction of lymph node metastasis. Mean number of lymph nodes removed from each case decreased when SLNs biopsy were taken. Conclusions: SLNs are the key lymph nodes in endometrial tumor metastasis and their involvement could be an indicator for whether or not complete systematic lymphadenectomy is needed during staging laparotomy.
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