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

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

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

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

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

The Effect of Directional Tactile Memory of the Back of the User on Reaction Time and Accuracy

Tactile memory is the cognitive process of storing and recalling information that has been perceived through the sense of touch. Directional tactile memory involves the encoding and retrieval of sensory data associated with a tactile experience, allowing individuals to remember and recognize directional information encoded through the sense of touch. A new method for providing directional tactile feedback, at the back of the user, has been developed to investigate the efficacy of directional tactile memory, its decay over time, and its impact during a concurrent cognitive task. Two experiments were presented. In the first experiment, tactile memory deterioration, with a visual or a tactile cue, was tested with different action-cue latencies (10 s and 20 s). In the second experiment, we considered tactile memory deterioration when there was an increased cognitive load as the participants played Tetris. Forty volunteers participated in the two experiments using purpose-built tactile seats with nine motors controlled by an Arduino. The performance data (error and reaction times) were analyzed statistically, and a NASA task load index (NASA-TLX) questionnaire was administered to measure the subjective workload after each of the two experiments. The findings highlighted that the directional tactile memory of the back can guide individuals to the correct point on the screen and that it can be maintained for at least 20 s. There was no statistically significant difference in the number of errors or reaction time with a visual or tactile action cue. However, being involved in a concurrent cognitive task (playing Tetris) adversely affected the reaction time, the number of errors, and the directional tactile memory, which degraded as the time between the directional cue and the action cue increased. Participants perceived the performance while playing Tetris as significantly more mentally and perceptually demanding, requiring more mental and physical effort and being more frustrating. These trials revealed a new potential for a human–machine interface system, leveraging directional tactile memory, which might be utilized to increase the safety of autonomous vehicles

Effective detection of quantum discord by using Convolutional Neural Networks

Quantum discord is a form of correlation that is defined as the difference between quantum and classical mutual information of two parties. Due to the optimization involved in the definition of classical mutual information of quantum systems, calculating and distinguishing between discordant and non-discordant states is not a trivial task. Additionally, complete tomography of a quantum state is the prerequisite for the calculation of its quantum discord, and it is indeed resource consuming. Here, by using the relation between the kernels of the convolutional layers of an artificial neural network and the expectation value of operators in quantum mechanical measurements, we design a Convolutional Neural Network (CNN) that uses 16 kernels to completely distinguish between the discordant and non-discordant general two-qubit states. We have also designed a Branching Convolutional Neural Network (BCNN) that can effectively detect quantum discord. Our BCNN achieves an accuracy of around 85% or 99%, by utilizing only 5 or 8 kernels, respectively. Our results show that to detect the existence of quantum discord up to the desired accuracy, instead of complete tomography, one can use suitable quantum circuits to directly measure the expectation values of the kernels, and then a fully connected network will solve the detection problem.Comment: Minor revisions, two references adde

Peripheral fundus findings in X-linked retinoschisis

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

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