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179 tulosta hakusanalla Atef a. Zaki

Electromagnetic Scattering using the Iterative Multi-Region Technique

Electromagnetic Scattering using the Iterative Multi-Region Technique

Mohamed H Al Sharkawy; Veysel Demir; Atef Z. Elsherbeni

Springer International Publishing AG
2007
nidottu
In this work, an iterative approach using the finite difference frequency domain method is presented to solve the problem of scattering from large-scale electromagnetic structures. The idea of the proposed iterative approach is to divide one computational domain into smaller subregions and solve each subregion separately. Then the subregion solutions are combined iteratively to obtain a solution for the complete domain. As a result, a considerable reduction in the computation time and memory is achieved. This procedure is referred to as the iterative multiregion (IMR) technique. Different enhancement procedures are investigated and introduced toward the construction of this technique. These procedures are the following: 1) a hybrid technique combining the IMR technique and a method of moment technique is found to be efficient in producing accurate results with a remarkable computer memory saving; 2) the IMR technique is implemented on a parallel platform that led to a tremendous computational time saving; 3) together, the multigrid technique and the incomplete lower and upper preconditioner are used with the IMR technique to speed up the convergence rate of the final solution, which reduces the total computational time. Thus, the proposed iterative technique, in conjunction with the enhancement procedures, introduces a novel approach to solving large open-boundary electromagnetic problems including unconnected objects in an efficient and robust way. Contents: Basics of the FDFD Method / IMR Technique for Large-Scale Electromagnetic Scattering Problems: 3D Case / IMR Technique for Large-Scale Electromagnetic Scattering Problems: 2D Case / The IMR Algorithm Using a Hybrid FDFD and Method of Moments Technique / Parallelization of the Iterative Multiregion Technique / Combined Multigrid Technique and IMR Algorithm / Concluding Remarks / Appendices
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Scattering Analysis of Periodic Structures using Finite-Difference Time-Domain Method

Scattering Analysis of Periodic Structures using Finite-Difference Time-Domain Method

Khaled ElMahgoub; Fan Yang; Atef Elsherbeni

Springer International Publishing AG
2012
nidottu
Periodic structures are of great importance in electromagnetics due to their wide range of applications such as frequency selective surfaces (FSS), electromagnetic band gap (EBG) structures, periodic absorbers, meta-materials, and many others. The aim of this book is to develop efficient computational algorithms to analyze the scattering properties of various electromagnetic periodic structures using the finite-difference time-domain periodic boundary condition (FDTD/PBC) method. A new FDTD/PBC-based algorithm is introduced to analyze general skewed grid periodic structures while another algorithm is developed to analyze dispersive periodic structures. Moreover, the proposed algorithms are successfully integrated with the generalized scattering matrix (GSM) technique, identified as the hybrid FDTD-GSM algorithm, to efficiently analyze multilayer periodic structures. All the developed algorithms are easy to implement and are efficient in both computational time and memory usage. These algorithms are validated through several numerical test cases. The computational methods presented in this book will help scientists and engineers to investigate and design novel periodic structures and to explore other research frontiers in electromagnetics. Table of Contents: Introduction / FDTD Method and Periodic Boundary Conditions / Skewed Grid Periodic Structures / Dispersive Periodic Structures / Multilayered Periodic Structures / Conclusions
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Double-Grid Finite-Difference Frequency-Domain (DG-FDFD) Method for Scattering from Chiral Objects

Double-Grid Finite-Difference Frequency-Domain (DG-FDFD) Method for Scattering from Chiral Objects

Erdogan Alkan; Veysel Demir; Atef Elsherbeni; Ercument Arvas

Springer International Publishing AG
2013
nidottu
This book presents the application of the overlapping grids approach to solve chiral material problems using the FDFD method. Due to the two grids being used in the technique, we will name this method as Double-Grid Finite Difference Frequency-Domain (DG-FDFD) method. As a result of this new approach the electric and magnetic field components are defined at every node in the computation space. Thus, there is no need to perform averaging during the calculations as in the aforementioned FDFD technique [16]. We formulate general 3D frequency-domain numerical methods based on double-grid (DG-FDFD) approach for general bianisotropic materials. The validity of the derived formulations for different scattering problems has been shown by comparing the obtained results to exact and other solutions obtained using different numerical methods. Table of Contents: Introduction / Chiral Media / Basics of the Finite-Difference Frequency-Domain (FDFD) Method / The Double-Grid Finite-Difference Frequency-Domain (DG-FDFD) Method for Bianisotropic Medium / Scattering FromThree Dimensional Chiral Structures / ImprovingTime and Memory Efficiencies of FDFD Methods / Conclusions / Appendix A: Notations / Appendix B: Near to Far FieldTransformation
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Schmerzen nach einer Bauchoperation

Schmerzen nach einer Bauchoperation

Salma Ketata; Imene Zouche; Atef Laraiedh

Verlag Unser Wissen
2023
pokkari
Die postoperative Analgesie (PAO) nimmt einen wichtigen Platz in der Bewertung der beruflichen Praxis ein und spielt eine Schl sselrolle bei der Senkung der postoperativen Morbidit t und Mortalit t.Wir f hrten eine prospektive Beobachtungsstudie durch, um die postoperative Analgesie bei Patienten zu bewerten, die in der Abteilung f r Viszeralchirurgie des CHU Habib Bourguiba Sfax Tunesien operiert wurden.Wir schlossen 60 Patienten im Alter von ber 18 Jahren ber einen Zeitraum von 15 Tagen ein.Postoperativ wurde die monomodale Analgesie am h ufigsten angewendet, wobei haupts chlich intraven s verabreichtes Paracetamol zum Einsatz kam. Bei gro en Bauchoperationen wurde die postoperative Epiduralanalgesie systematisch durchgef hrt. Die Patienten, die diese Technik erhielten, waren rundum zufrieden. Am Ende des Krankenhausaufenthalts war der schwache Schmerz am st rksten ausgepr gt und die Mehrheit der Patienten war mit der Betreuung in der Abteilung zufrieden.
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Pain following abdominal surgery

Pain following abdominal surgery

Salma Ketata; Imene Zouche; Atef Laraiedh

Our Knowledge Publishing
2023
pokkari
Postoperative analgesia (PSA) plays an important role in the evaluation of professional practices, and plays a key role in reducing postoperative morbidity and mortality.We conducted a prospective observational study evaluating postoperative analgesia in patients operated on in the visceral surgery department of CHU Habib Bourguiba Sfax Tunisia.We included 60 patients aged over 18 years over a 15-day period.Postoperatively, monomodal analgesia was most commonly used, mainly intravenous paracetamol. In major abdominal surgery, postoperative epidural analgesia was used systematically. Patients who benefited from this technique were entirely satisfied. At the end of the hospital stay, pain was least marked, and the majority of patients were satisfied with their care in the department.
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Dolore dopo un intervento chirurgico all'addome

Dolore dopo un intervento chirurgico all'addome

Salma Ketata; Imene Zouche; Atef Laraiedh

Edizioni Sapienza
2023
pokkari
L'analgesia postoperatoria (PSA) riveste un ruolo importante nella valutazione delle pratiche professionali e gioca un ruolo chiave nella riduzione della morbilit e della mortalit postoperatoria.Abbiamo condotto uno studio prospettico osservazionale per valutare l'analgesia postoperatoria nei pazienti operati nel reparto di chirurgia viscerale dell'Ospedale Universitario Habib Bourguiba, Sfax, Tunisia.We included 60 patients aged over 18 years over a period of 15 days.Nel periodo postoperatorio stata utilizzata soprattutto l'analgesia monomodale, principalmente il paracetamolo per via endovenosa. Nella chirurgia addominale maggiore stata utilizzata sistematicamente l'analgesia epidurale postoperatoria. Patients who benefited from this technique were completely satisfied. Al termine della degenza, il dolore minore era quello pi marcato e la maggior parte dei pazienti era soddisfatta dell'assistenza ricevuta in reparto.
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Die Rolle der Pflege bei der Früherkennung vonHals- und Gebärmutterkrebs

Die Rolle der Pflege bei der Früherkennung vonHals- und Gebärmutterkrebs

Howieda Fouly; Marilyn Stringer; Atef Darwish

Verlag Unser Wissen
2025
nidottu
In dieser Studie haben wir die Rolle der Krankenschwestern bewertet. Diese Rolle umfasste zwei Prinzipien: als Beraterin und als Anbieterin von Vorsorgeuntersuchungen zur Fr herkennung von Geb rmutterhalskrebs. In der ersten Rolle gelang es den Krankenschwestern, Frauen ber die Vorteile der Vorsorgeuntersuchungen zur Fr herkennung von Geb rmutterhalskrebs aufzukl ren, indem sie ihnen die mit diesen Untersuchungen verbundenen Vorurteile nahmen. Diese Aufkl rung f hrte dazu, dass die Frauen die Vorsorgeuntersuchungen zur Fr herkennung von Geb rmutterhalskrebs mittels visueller Untersuchung mit Essigs ure akzeptierten. Die Krankenschwestern zeigten sich kompetent in der Durchf hrung der VIA- und Pap-Abstrich-Untersuchungen. Diese Studie zeigt auch, dass die VIA eine Rolle bei der Erkennung von Geb rmutterhalsl sionen spielt, die derzeit in gypten nicht ohne Weiteres verf gbar ist. Durch den Vergleich von VIA und Pap-Abstrich haben wir festgestellt, dass die VIA eine wirksame Methode zur Erkennung von pr kanzer sen/kanzer sen Geb rmutterhalsl sionen in einem ressourcenarmen Umfeld mit begrenzter Verf gbarkeit von Geb rmutterhalskrebsvorsorgeuntersuchungen ist.
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Rola pielęgniarstwa we wczesnym wykrywaniu raka szyjki macicy

Rola pielęgniarstwa we wczesnym wykrywaniu raka szyjki macicy

Howieda Fouly; Marilyn Stringer; Atef Darwish

Wydawnictwo Nasza Wiedza
2025
nidottu
W niniejszym badaniu oceniliśmy rolę pielęgniarek. Role te opieraly się na dw ch zasadach: jako doradcy i jako osoby przeprowadzające badania przesiewowe w kierunku raka szyjki macicy. W pierwszej roli pielęgniarki skutecznie doradzaly kobietom na temat korzyści plynących z badań przesiewowych w kierunku raka szyjki macicy, lagodząc piętno związane z tymi badaniami. Doradztwo to zaowocowalo akceptacją badań przesiewowych w kierunku wczesnego wykrywania raka szyjki macicy za pomocą oględzin z użyciem kwasu octowego. Pielęgniarki wykazaly się bieglością w wykonywaniu badań VIA i cytologii. Badanie to wskazuje r wnież, że badanie VIA odgrywa rolę w wykrywaniu zmian szyjki macicy, kt re obecnie nie są latwo dostępne w Egipcie. Por wnując badanie VIA z cytologią, odkryliśmy, że badanie VIA jest skuteczną metodą wykrywania przedrakowych/rakowych zmian szyjki macicy w warunkach ograniczonych zasob w i ograniczonej dostępności badań przesiewowych w kierunku raka szyjki macicy.
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Analysis and Design of Transmitarray Antennas

Analysis and Design of Transmitarray Antennas

Ahmed H. Abdelrahman; Fan Yang; Atef Z. Elsherbeni; Payam Nayeri

Springer International Publishing AG
2017
nidottu
In recent years, transmitarray antennas have attracted growing interest with many antenna researchers. Transmitarrays combines both optical and antenna array theory, leading to a low profile design with high gain, high radiation efficiency, and versatile radiation performance for many wireless communication systems. In this book, comprehensive analysis, new methodologies, and novel designs of transmitarray antennas are presented. Detailed analysis for the design of planar space-fed array antennas is presented. The basics of aperture field distribution and the analysis of the array elements are described. The radiation performances (directivity and gain) are discussed using array theory approach, and the impacts of element phase errors are demonstrated.The performance of transmitarray design using multilayer frequency selective surfaces (M-FSS) approach is carefully studied, and the transmission phase limit which are generally independent from the selection ofa specific element shape is revealed. The maximum transmission phase range is determined based on the number of layers, substrate permittivity, and the separations between layers.In order to reduce the transmitarray design complexity and cost, three different methods have been investigated. As a result, one design is performed using quad-layer cross-slot elements with no dielectric material and another using triple-layer spiral dipole elements. Both designs were fabricated and tested at X-Band for deep space communications. Furthermore, the radiation pattern characteristics were studied under different feed polarization conditions and oblique angles of incident field from the feed.New design methodologies are proposed to improve the bandwidth of transmitarray antennas through the control of the transmission phase range of the elements. These design techniques are validated through the fabrication and testing of two quad-layer transmitarray antennas at Ku-band.A single-feed quad-beam transmitarray antenna with 50 degrees elevation separation between the beams is investigated, designed, fabricated, and tested at Ku-band. In summary, various challenges in the analysis and design of transmitarray antennas are addressed in this book. New methodologies to improve the bandwidth of transmitarray antennas have been demonstrated. Several prototypes have been fabricated and tested, demonstrating the desirable features and potential new applications of transmitarray antennas.
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