1,603 research outputs found

    Application of numerical method to investigation of fatigue crack behavior through the friction stir welding

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    Fatigue crack propagation through a friction stir welded (FSW) joint of 2024-T351 Al alloy is investigated numerically. The governing relationships for predicting the crack behavior including incremental crack length, crack growth rate, and crack growth direction are presented. Stress intensity is calculated based on displacement correlation technique, and fatigue crack growth through the FSW joint is investigated under linear elastic fracture mechanics (LEFM) using the Paris model. The concepts of crack closure, residual stress, and stress relaxation are incorporated into the Paris model to support the final results. Maximum circumferential tensile stress method is applied to predict the crack growth direction. Finally, the numerical approaches are employed to the high number of elements in the framework of Fracture Analysis Code (FRANC2D/L) to simulate the fatigue crack propagation through the FSW joint including various zones with different material properties. Fatigue lifetime of the welded joint is predicted by implementing the same procedure for various loading values. The obtained numerical results are validated with the experimental work (Ali et al., Int J Fatigue 30:2030–2043, 2008)

    Validity of capital asset pricing model: evidence from Karachi stock exchange

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    This study investigates the validity of Capital Asset Pricing (CAP) Model in Karachi stock exchange (KSE). The data of 387 companies of 30 different sectors on monthly, quarterly and semiannual basis are used. The Paired sample t- test is applied to find the difference between actual and expected returns. Results show that capital asset pricing model (CAPM) predict more accurately the expected return on a short term investment as compare to long term investment. It is recommended that the investors should more focus on CAPM results for short term as compare to long term investments in KSE.Portfolio choice, Investment Decisions, Capital Assets Pricing Model, Risk

    The Status and dignity of Women in Islam and Hinduism

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    The heavenly religions have spoken much about the creation of man and his place in the world of creation. The position of women in these religions, known as the revelation religions, is very high. In the ancient Hindus, woman was not dignified and regarded as much as men, although in the Upanishads the woman was intrinsically valued, and man and woman are half halves that complement each other. There is no legal difference between men and women in India today, and women can engage in political, economic, and cultural activities as men. In Hinduism, woman holds a high position as a mother, from the point of view of Hinduism, the ideal woman is a woman who loves her husband and provides his with comfort. But the Hindu girl is far less valuable than the Hindu boy, and many Hindus do not generally favor the girl child. From the Islamic point of view, men and women have equal value in terms of humanity, and no one has superiority over others in their humanity. But this does not mean that any physical and mental differences between the two are denied. The holy religion of Islam considers women the first and foremost task of marrying and raising children, by assigning specific duties to women that are commensurate with their type of creation, but at the same time permits women to adhere to the principles of a Muslim woman participate in the community and engage in social and economic activities

    A Hierarchical Approach for Investigating Social Features of a City from Mobile Phone Call Detail Records

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    Cellphone service-providers continuously collect Call Detail Records (CDR) as a usage log containing spatio-temporal traces of phone users. We proposed a multi-layered hierarchical analytical model for large spatio-temporal datasets and applied that for the progressive exploration of social features of a city, e.g., social activities, relationships, and groups, from CDR. This approach utilizes CDR as the preliminary input for the initial layer, and analytical results from consecutive layers are added to the knowledge-base to be used in the subsequent layers to explore more detailed social features. Each subsequent layer uses the results from previous layers, facilitating the discovery of more in-depth social features not predictable in a single-layered approach using only raw CDR. This model starts with exploring aggregated overviews of the social features and gradually focuses on comprehensive details of social relationships and groups, which facilitates a novel approach for investigating CDR datasets for the progressive exploration of social features in a densely-populated city

    Peripheral fundus findings in X-linked retinoschisis

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    BACKGROUND/AIMS: Vitreous haemorrhage (VH) and retinal detachment (RD) cause a precipitous decline in vision in a subset of patients with X-linked retinoschisis (XLRS), an otherwise a slowly progressive condition. This study aims to report the frequency of macular and peripheral retinal findings in a large cohort of patients with XLRS and to determine whether peripheral retinal findings are associated with VH and RD. METHODS: A retrospective observational case series was performed in 65 patients with XLRS with a pathogenic variant in retinoschisin 1. Chart review included examination notes, fundus photographs and optical coherence tomography (OCT). Fisher exact tests and univariable logistic regression analysis were used to determine the association between peripheral retinal findings (including retinoschisis, metallic sheen, vascular sheathing, pigmentary changes, white spiculations and vitreous veils) and complications (including VH and RD). RESULTS: Seven eyes (8%) showed normal macular structure on OCT. Peripheral retinoschisis was significantly associated with both VH and RD. Out of 10 eyes with complications, 9 (90%) had peripheral retinoschisis, compared with 33 out of 116 eyes (28%) without complications (p=0.0014). In addition, each additional peripheral finding increased the odds of RD by a factor of 4.06 (95% CI 1.58 to 10.39, p=0.028). There were no complications in the 28 eyes with a normal periphery (p=0.84) or in the 35 eyes with metallic sheen (p=0.42). CONCLUSION: The data suggest that patients with peripheral retinoschisis are at increased risk for VH and RD. Furthermore, patients with additional peripheral retinal findings together with peripheral schisis may carry additional risk for RD

    Modelling the fatigue crack growth in friction stir welded joint of 2024-T351 Al alloy

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    In this work the fatigue crack propagation within the friction stir welded (FSW) joint of 2024-T351 Al alloy is studied as well as fatigue lifetime of the joint using Walker and Nicholls models. The FSW joint is characterised in terms of the residual stress (using the hole drilling technique), material, and cyclic properties. The material surface is polished in order to avoid any surface irregularities. The crack initiation is detected applying scanning electron microscopy (SEM), however plastic replication technique is used to monitor the crack propagation. The concepts of crack closure, residual stress and stress relaxation are incorporated into both models. Finally the results are validated and compared together regarding to the experiments

    The study of stability and changes poly unsaturated fatty acid (PUFA), coefficient of the (Polyen Index) in burger production of Kilka (Clupeonella cultriventris) and Silver carp (Hypophthalmichthys molitrix) during storage at - 18 °C

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    Berger is one of the most significant products as fish paste, now produced of red meat and red meat waste with different qualities, does not have much nutritional value .Using fish as an alternative to red meat, diversify and enhance the quality of nutritional value and the ability to use for all ages in the community of the aims of this study were , in addition the combined use of a cultured marine species is effective and to raise the index of unsaturated fatty acids and amino acids in the final product .In this study the effects of different replacement of kilka meat instead of Silver carp in the preparation of the consolidated burger on the acceptance, as well as changes unsaturated fatty acids and poly factor that it considered during 5 months of the best treatment choice for industrial production to be introduced industry Therefore 4 treatments Burger compilation as follows: Treatment (control), combination of burger with %100 Silver carp meat , treatment 1, combination of burger with %100 Kilka meat, treatment 2, combination of burger with %75 + 25 Kilka and Silver carp meat , treatment 3, combination of burger with %50 + 50 Kilka and Silver carp meat , after adding the %5.6 flour and breadcrumbs, %6 onions, %5soy, %3.25tomato paste,% 0.15 lemon juice,%2.1 garlic and egg powder and spices and %1.2salt to treatments , after preparation and packaging of the kept at cold room(-18o c )was evaluated . According to treatment 3 test (50% Kilka meat and 50% Silver carp meat) with the other treatments had significant difference (p <0.05) and had higher levels of unsaturated fatty acid. Also the treatment2, control and 1 respectively are secondary priorities. According to the goals of this project that combine Kilka and Silver crap meat on preparation of fusion burger is to economies the final product , results within 5 months of product storage at - 18 ° C reflects the fact that product quality in the long term preservation of unsaturated fatty acids has been accepted

    Towards Extended Bit Tracking for Scalable and Robust RFID Tag Identification Systems

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    The surge in demand for Internet of Things (IoT) systems and applications has motivated a paradigm shift in the development of viable radio frequency identification technology (RFID)-based solutions for ubiquitous real-Time monitoring and tracking. Bit tracking-based anti-collision algorithms have attracted considerable attention, recently, due to its positive impact on decreasing the identification time. We aim to extend bit tracking to work effectively over erroneous channels and scalable multi RFID readers systems. Towards this objective, we extend the bit tracking technique along two dimensions. First, we introduce and evaluate a type of bit errors that appears only in bit tracking-based anti-collision algorithms called false collided bit error in single reader RFID systems. A false collided bit error occurs when a reader perceives a bit sent by tag as an erroneous bit due to channel imperfection and not because of a physical collision. This phenomenon results in a significant increase in the identification delay. We introduce a novel, zero overhead algorithm called false collided bit error selective recovery tackling the error. There is a repetition gain in bit tracking-based anti-collision algorithms due to their nature, which can be utilized to detect and correct false collided bit errors without adding extra coding bits. Second, we extend bit tracking to 'error-free' scalable mutli-reader systems, while leaving the study of multi-readers tag identification over imperfect channels for future work. We propose the multi-reader RFID tag identification using bit tracking (MRTI-BT) algorithm which allows concurrent tag identification, by neighboring RFID readers, as opposed to time-consuming scheduling. MRTI-BT identifies tags exclusive to different RFIDs, concurrently. The concept of bit tracking and the proposed parallel identification property are leveraged to reduce the identification time compared to the state-of-The-Art. 2013 IEEE.This work was supported by the Qatar National Research Fund (a member of Qatar Foundation) through NPRP under Grant 7-684-1-127. The work of A. Fahim and T. ElBatt was supported by the Vodafone Egypt Foundation.Scopu