653 research outputs found
Notch Sensitivity of Fiber Reinforced Composite
No full textA Master of Science thesis in Mechanical Engineering by Mostafa Elyoussef entitled, “Notch Sensitivity of Fiber Reinforced Composite”, submitted in April 2019. Thesis advisor is Dr. Maen Alkhader and thesis co-advisor Dr. Wael Abuzaid. Soft and hard copy available.In most applications, structures made of composite materials involve features such as drilled assembly holes, which induce stress concentrations in their vicinities resulting in a reduction in the load carrying capacity of the structure. The nature of the damage resulting from such geometric features in orthotropic CFRP composites has been the subject of extensive research. Nevertheless, few works have investigated the behavior of notched CFRP composites exposed to elevated temperatures. Accordingly, the aim of this research is to investigate the effect of elevated temperatures on the notch sensitivity of CFRP composites. To achieve the goal of this study, both the nominal and local responses of woven CFRP samples were experimentally investigated, with the aid of Digital Image Correlation technique (DIC). Tensile tests were conducted on notched (i.e. with circular hole) and un-notched samples at 25°C, 50°C, 75°C, and 100°C. The experimental results obtained from the global stress-strain response of un-notched samples showed a decreasing trend in the mechanical properties with increasing temperatures. However, the global response of notched samples at 50°C surprisingly deviated from the expected trend and exhibited higher tensile strength than that at 25°C. Moreover, the notch sensitivity, assessed through un-notched to notched strength ratio, was found to decrease with increasing temperatures. Fractured surface examination showed two different damage mechanisms: Transverse cracks and axial splitting. It was noticed that transverse cracks was evident at the four temperature levels, while axial splitting was absent at room temperature. Measuring the local axial strains at the transverse crack initiation site showed a clear deviation from the linear response at the onset of transverse cracking. Moreover, investigating the local response at the axial splitting initiation site revealed a sudden change in the transverse and shear strain evolution. The blunting effect of axial splitting was found to become more significant at higher temperatures. Furthermore, residual shear strains were measured at the end of loading-unloading cycle for different temperature levels. It was found that residual strains are negligible at room temperatures and become more significant at higher loading temperatures.College of EngineeringDepartment of Mechanical EngineeringMaster of Science in Mechanical Engineering (MSME
The Decline of Salafism: Causes and Future Trajectories
No full textThe article examines the decline of traditional Salafism, analyzing its causes and potential future trajectories. The author identifies key factors such as internal fragmentation, failure in power management, and the rise of traditional institutions like Ash'arism. The author also discusses the impact of information and communication technology, societal rejection of jihadist violence, and the decrease in financial support. Finally, he explores the phenomenon of "new Salafism" and movements like Salafyo Costa, which aim to reform Salafi thought and promote openness towards others
Shari'ah, Fiqh and Egyptian Law
No full textThe article examines the inclusion of the principles of Islamic Shari'ah in Egyptian legislation, highlighting the confusion between Shari'ah and Fiqh (Islamic jurisprudence). It analyzes how Shari'ah, originally understood as "path" or "way," has been reinterpreted to include legal and jurisprudential regulations. The author criticizes the ambiguous use of the term "principles of Islamic Shari'ah" in Egyptian legislation, emphasizing the negative consequences of this confusion. The article concludes that the call for the codification of Shari'ah actually implies the codification of Fiqh, leading to potential conflicts and misunderstandings in Egyptian society
Mann und Frau und ein Leben voller Bedeutung
No full textThe article explores the equality between men and women in the Quran, emphasizing how the sacred text asserts that everything exists in pairs and that both genders are equal in rights and religious duties. By citing various verses, the author demonstrates that the Quran acknowledges the merits of both men and women, promoting justice and equality. Additionally, the article discusses the interpretation of scriptures and how it can adapt to modern contexts, highlighting that a person's superiority over another is determined solely by devotion and moral conduct, not by gender or social status
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Authority, continuity, and change in Islamic law /
No full textWael B. Hallaq is regarded as one of the leading scholars in the field of Islamic law. In a path-breaking new book, the author shows how authority guaranteed both continuity and change in Islamic law. While the role of the law schools in augmenting these processes was of the essence, the author demonstrates that it was the construction of the absolutist authority of the school founder, an image which he suggests was actually developed later in history, that maintained the foundations of school methodology and hermeneutics. The defence of that methodology gave rise to an infinite variety of individual legal opinions, ultimately accommodating changes in the law. Thus the author concludes that the mechanisms of change were embedded in the very structure of Islamic law, despite its essentially conservative nature. This book will be welcomed by specialists and scholars in Islamic law for its rigour and innovation
Heat Transfer Enhancement from a Horizontal Cylinder Wrapped with a Porous Layer of Metal Foam: Experimental and Numerical Studies
No full textThis thesis presents experimental and numerical studies to investigate the heat transfer enhancement from a horizontal cylinder wrapped with metal foam layer in forced flow. Two configurations are investigated, whole and segmented metal foam layers of two different thicknesses but same porous material properties. For the experimental study, the metal foam configurations are tested at Reynolds number range of 7500 – 18000. Numerical CFD studies were conducted using ANSYS Fluent software and calibrated against the experimental data to provide a path for future numerical parametric analysis. The thermohydraulic characteristics of the metal foam configurations were obtained experimentally, along with an overall performance factor parameter. The segmented configuration at an optimum orientation angle proved to have the best overall performance of high heat transfer enhancement and lower pressure drop. The results of this thesis are of great value to many industries concerned with the thermohydraulic enhancement of heat transfer from tubes such as heat exchangers.2021-05-0
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A history of Islamic legal theories ::an introduction to Sunnī uṣūl al-fiqh /
No full textWael B. Hallaq has already established himself as one of the most eminent scholars in the field of Islamic law. In this book, first published in 1997, the author traces the history of Islamic legal theory from its early beginnings until the modern period. Initially, he focuses on the early formation of this theory, analysing its central themes and examining the developments which gave rise to a variety of doctrines. He concludes with a discussion of modern thinking about the theoretical foundations and methodology of Islamic law. In organisation, approach to the subject and critical apparatus, the book will be an essential tool for the understanding of Islamic legal theory in particular and Islamic law in general. This, in combination with an accessibility of language and style, will guarantee a readership among students and scholars and anyone interested in Islam and its evolution
L’engagement numérique comme acte créatif : le cas de Wael Ghonim pendant la révolution égyptienne de 2011
No full textPendant la révolution égyptienne de 2011, les réseaux sociaux ont accompagné et structuré la mobilisation – à la fois en tant qu'outils efficaces de coordination en vue de grands rassemblements et comme moyen incomparable de transmettre une parole non censurée. Cet article tente de répondre à la question suivante : à partir d’un usage novateur et élargi des réseaux sociaux dans un contexte révolutionnaire, peut-on parler de l’émergence d'une nouvelle forme d’engagement politique ? Notre analyse s'appuiera sur l’autobiographie al-Thawrah 2.0 (Révolution 2.0) de Wael Ghonim, qui retrace le parcours de son auteur, de l’opposition passive à l’avant-garde révolutionnaire. Ce livre se distingue par son style composite, notamment par l’insertion de slogans, chattings, courriers électroniques et de nombreux fragments tirés de Facebook – notre attention se portera plus particulièrement sur ces éléments d'un genre nouveau. À travers une approche pluridisciplinaire, littéraire, sociolinguistique et politique, nous nous interrogerons sur le rôle de ces passages, comme forces perturbatrices ou équilibrantes, dans le contexte de la lutte contre le régime répressif égyptien.During the Egyptian Revolution of 2011, social networks structured and accompanied mobilization because of their efficacy in disseminating information on the organization of mass gatherings and of their ability to transmit uncensored speech. This article attempts to answer this question: when it comes to an increased and innovative use of social networks in a revolutionary context, can we speak of the emergence of a new political commitment? The autobiography al-Thawrah 2.0 (Revolution 2.0) of Wael Ghonim will be a central support in this article. It traces the career of the author of passive opposition to the revolutionary vanguard. This book is distinguished by its composite style, including the insertion of slogans, chattings, emails, and numerous fragments drawn from Facebook which will be used specifically for the analysis. Through a multidisciplinary approach: literary, sociolinguistic and political, I will question the status of these passages as disruptive or balancing forces in a fight against the repressive Egyptian regime
Sharīʻa : theory, practice, transformations /
No full textIn recent years, Islamic law, or Shari'a, has been appropriated as a tool of modernity in the Muslim world and in the West and has become highly politicised in consequence. Wael Hallaq's magisterial overview of Shari'a sets the record straight by examining the doctrines and practices of Islamic law within the context of its history, and by showing how it functioned within pre-modern Islamic societies as a moral imperative. In so doing, Hallaq takes the reader on an epic journey tracing the history of Islamic law from its beginnings in seventh-century Arabia, through its development and transformation under the Ottomans, and across lands as diverse as India, Africa and South-East Asia, to the present. In a remarkably fluent narrative, the author unravels the complexities of his subject to reveal a love and deep knowledge of the law which will inform, engage and challenge the reader.Title from publisher's bibliographic system (viewed on 05 Oct 2015).The formative period -- Legal theory : epistemology, language and legal reasoning -- Legal education and the politics of law -- Law and society -- The circle of justice and later dynasties -- The legal pillars of religion -- Contracts and othe obligations -- Family law and succession -- Property and ownership -- Offenses -- Jihād -- Courts of justice, suits and evidence -- The conceptual framework : an introduction -- The jural colonization of India and South-East-Asia -- Hegemonic modernity : the Middle East and North Africa during the nineteenth and early twentieth centuries -- Modernizing the law in the age of nation-states -- In search of a legal methodology -- Repercussions: concluding notes.In recent years, Islamic law, or Shari'a, has been appropriated as a tool of modernity in the Muslim world and in the West and has become highly politicised in consequence. Wael Hallaq's magisterial overview of Shari'a sets the record straight by examining the doctrines and practices of Islamic law within the context of its history, and by showing how it functioned within pre-modern Islamic societies as a moral imperative. In so doing, Hallaq takes the reader on an epic journey tracing the history of Islamic law from its beginnings in seventh-century Arabia, through its development and transformation under the Ottomans, and across lands as diverse as India, Africa and South-East Asia, to the present. In a remarkably fluent narrative, the author unravels the complexities of his subject to reveal a love and deep knowledge of the law which will inform, engage and challenge the reader
A Low-Cost Technique for improving Angular Scan Range of Phased Array Antennas
No full textWith the emergence of modern communication technologies, there has been an increasing
demand for faster and higher-quality communication, which necessitates higher bit
rates and, consequently, greater bandwidth. This shift has driven the adoption of higher
operational frequencies, such as millimeter-wave bands. For instance, 5G mobile communications
operate in the K band (18–27 GHz) and Ka band (27–40 GHz), while satellite
communications often use the Ku band (12–18 GHz) and Ka band. However, as the operational
frequency increases, path loss becomes significantly higher, requiring the use of
higher-gain antennas to compensate for this loss. A key drawback of using high-gain antennas,
such as parabolic reflectors, is the difficulty in steering the beam to cover a wider
angular range.
Phased array antennas provide an excellent solution as transmitting or receiving antennas
for that reason, as they provide a high gain with the ability to electronically steer
the beam to other directions by changing the progressive phase shift between the array
elements.
Designing a high-performance broadband phased array antenna with a wide angular
scanning range is challenging, as the antenna parameters are interrelated and require tradeoffs.
For example, increasing the distance between elements reduces mutual coupling and
increases the effective aperture of the array, thereby enhancing its gain. However, this also
causes grating lobes to appear at lower scan angles, thereby limiting the angular scanning
range. Additionally, a larger element spacing necessitates a wider electronic phase shift
range, requiring a more linear phase shifter with frequency, which complicates the design
of the feeding network.
The focus of this research is to investigate a low-cost approach to improving the angular
scanning range of phased array antennas through the use of a wide angle impedance
matching layer (WAIM), employing two techniques. First, A general analytical method is
provided to characterize the array’s scan impedance variation in the presence of nearby
reflecting surfaces, such as a ground plane or WAIM layers. Second, the generalized Smatrix
technique is used to model the array unit cell and transmission line (TL) models
for WAIM layers. The WAIM layer offers a low-cost, scalable solution to increase the angular
scanning range of phased array antennas without altering their lattice configuration
or feeding network. This makes it a modular solution, simpler than other techniques.
In this thesis, Both main WAIM modeling techniques are investigated, applied to different
array examples (slot and dipole arrays). Then, the GSM method is used to design
a fully dielectric WAIM laye
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