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Numerical Investigation of Rotating Stall in Centrifugal Compressor with Vaned and Vaneless Diffuser

Journal of Thermal Science 2015年第4期24卷 323-333页

作者： Taher Halawa Mohamed Alqaradawi Mohamed S.Gadala ibrahim shahin Osama Badr Mechanical Engineering Department UBC-University of British ColumbiaVancouverB.C.Canada Mechanical Engineering Department Cairo University Mechanical & Industrial Engineering Department Qatar University Mechanical Engineering Department Abu Dhabi University Mechanical and Industrial Engineering Department Qatar UniversityDohaQatar Mechanical Engineering Department Benha University Mechanical Engineering Department British University

This study presents a numerical simulation of the stall and surge in a centrifugal compressor and presents a description of the stall development in two different *** first case is for a compressor with vaneless diffuser and the second is for a compressor with vaned diffuser of the vane island *** main aim of this study is to compare the flow characteristics and behavior for the two compressors near the surge operating condition and provide further understanding of the diffuser role when back flow occurs at *** showed that for a location near the diffuser entrance,the amplitude of the static pressure fluctuations for the vaneless diffuser case is higher than that for the vaned diffuser case near surge *** pressure fluctuations in the case of the vaneless diffuser appear with a gradual decrease of the mean pressure value as a part of the surge *** for the case of the vaned diffuser,the pressure drop during surge occurs faster than the case of the vaneless ***,results indicated that during surge in the case of vaneless diffuser,there is a region with low velocity and back flow that appears as a layer connecting all impeller passages near shroud surface and this layer develops in size with *** the other hand,for the case of vaned diffuser during surge,the low velocity regions appear in random locations in some passages and these regions expand with time towards the shroud *** showed that during stall,the impeller passages are exposed to identical impact from stall cells in the case of vaneless diffuser while the stall effect varies from passage to another in the case of the vaned diffuser.

关键词： centrifugal compressors rotating stall surge vaneless diffuser vaned diffuser

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Professional identity, wellness, and future hope among nurse interns in Egypt

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Frontiers of Nursing 2021年第3期8卷 279-290页

作者： Rasha Mohammed Hussien Mahmoud Abdul Hameed shahin Mervat Elshahat ibrahim Department of Psychiatric Health Nursing Faculty of NursingZagazig UniversityZagazig 423423Egypt Critical Care Nursing Department Mohammed Al-Mana College for Medical SciencesDammam 34222Saudi Arabia Department of Family and Community Health Nursing Faculty of NursingSuez Canal UniversityIsmailia 545345Egypt

Objective:Since nursing is a performance-based profession,clinical learning environments play an important role in the acquisition of professional abilities and train nursing students to enter the nursing profession and become a registered *** study aimed to investigate the relations among professional identity,wellness,and future hope in nurse ***:A cross-sectional,analytic,descriptive,correlational study design was used to test these relations in the study where 210 nurse interns’students were selected using a convenience sampling from Zagazig University hospitals and Suez Canal University hospitals in *** questionnaires consisted of 4 parts,namely demographic characteristics,Professional Identity Scale for Nursing Students(PISNS),Holistic Health and Wellness Survey,and Hope ***:Less than half of the study sample had chosen nursing specialty by own will(43.8%),while slightly more than half of them had a"very good"graduation level,and had no nursing role *** lowest mean professional identity score was for independence in career choice while the highest was for social *** repor ted physical wellness mean-score was the least,while social wellness was the *** identity,wellness,and future hope scores differed significantly based on nurse interns’personal *** were statistically significant,positive,weak-to-moderate correlations among the scores of professional identity,wellness,and future hope;however,the"choice of nursing study by own will"was a statistically significant independent positive predictor of the scores of professional identity,wellness,and future ***:Nurse interns’professional identity,wellness,and future hope were positively ***,nurse interns’wellness was the lowest,and it should be fostered as it was the main predictor for future *** internship programs should be modulated to improve nurse interns’professional identity,par ticularly

关键词： hope identity independence internship nurse interns professional wellness

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The Effect of Absorbed Dose to Organs at Risk Following Craniospinal Irradiation Using Different Radiotherapy Techniques

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International Journal of Medical Physics, Clinical Engineering and Radiation Oncology 2020年第2期9卷 73-85页

作者： Hadeer A. shahin Ehab M. Attalla H. S. Abou-Elenien Hussein Elsayed ibrahim Bashter Marwa A. Suliman Physics Department Faculty of Science Zagazig University Zagazig Egypt Radiotherapy Department National Cancer Institute Cairo Egypt Radiotherapy Department Children’s Cancer Hospital Cairo Egypt Clinical Oncology & Nuclear Medicine Department Faculty of Medicine Suez Canal University Ismailia Egypt

Introduction: In medulloblastoma patients craniospinal irradiation is an important element the treatment. Our study aimed to evaluate the effect of absorbed dose to organs at risk using the hybrid intensity-modulated radiation therapy (IMRT) versus three-dimensional conformal radiotherapy (3DCRT) for craniospinal irradiation (CSI) in average risk medulloblastoma patients. Materials and Methods: In this study, thirteen medulloblastoma patients were included. The prescribed total dose to the planning target volume (PTV) was 23, 40 Gy in 13 fractions. Two radiotherapy techniques, three dimensional conformal radiotherapy (3DCRT) and hybrid intensity modulated radiotherapy (IMRT) were used to treat these patients. The coverage of the Target was evaluated using the D mean, D95%, D2%, D98% and V95%. Other parameters were also compared such as Integral dose (ID), Homogeneity index (HI) and doses to the organs at risk (OARs). Results: There was no significant difference in the mean dose received by the PTV-Brain or the dose received by 95% and 98% of PTV volume using the two techniques. For PTV-Spine, the percentage volume receiving 95% of the total dose increased significantly in the hybrid IMRT technique compared to the conformal technique. So, hybrid IMRT plan achieved the best coverage for PTV spine. Lower dose for OAR was delivered by 3DCRT, except the heart and thyroid, hybrid IMRT achieved better sparing. All plans resulted in the same dose homogeneity index (DHI) for PTV-Brain. For PTV-Spine, hybrid IMRT technique achieved better dose homogeneity compared to 3DCRT technique (1.09 vs. 1.12;p > 0.05). Conclusions: hybrid IMRT technique can be realized on conformal technique because it achieved better dose coverage for the (PTV) and organ at risk (OAR). 3DCRT reduced mean dose to most OARS, except the heart and thyroid. Therefore, the hybrid IMRT technique may be a CSI treatment alternative to 3DCRT.

关键词： Craniospinal Irradiation Three-Dimensional Conformal Radiotherapy Intensity-Modulated Radiation Therapy Medulloblastoma Organs at Risk Homogeneity Index

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Infantile Hemangiopericytoma: Two Cases Report and Literature Review

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Surgical Science 2011年第7期2卷 379-384页

作者： Gamal Al-Saied Amin Abokifa Mohamed Al-Saeed Mohamed Abdul Aziz Medhat ibrahim Moemen Hafez Tharwat Hussain Mohamed shahin Dalal Nemenqani Naglaa Fawzy 不详

Hemangiopericytoma is a rare vascular tumour of infants. Although generally considered to be benign, local recurrence and metastases can occur. Herein, we report on two full term girls, delivered with lumbosacral swelling and left thigh swelling respectively. Complete surgical excision with safety margins was performed for each lesion. Histologic examination of both lesions showed picture of infantile hemangiopericytoma. There is no evidence of local recurrence or distant metastasis during last 20 and 17 months for 1st case and 2nd case respectively. In conclusion;most infantile hemangiopericytoma follow a benign course. Rarely these tumours behave aggressively with local infiltration, recurrences and even distant metastases. Careful follow up is therefore essential.

关键词： Infantile Hemangiopericytoma Vascular Tumour

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Professional identity, wellness, and future hope among nurse interns in Egypt

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Frontiers of nursing 2021年第3期

作者： Rasha Mohammed Hussien Mahmoud Abdul Hameed shahin Mervat Elshahat ibrahim

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Infantile Hemangiopericytoma: Two Cases Report and Literature Review

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Surgical Science（外科学） 2011年第7期

作者： Gamal Al-Saied Amin Abokifa Mohamed Al-Saeed Mohamed Abdul Aziz Medhat ibrahim Moemen Hafez Tharwat Hussain Mohamed shahin Dalal Nemenqani Naglaa Fawzy

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