Computational fluid dynamics study of dusty air flow over NACA 63415 airfoil for wind turbine applications

Gulf and South African countries have enormous potential for wind energy. However, the emergence of sand storms in this region postulates performance and reliability challenges on wind turbines. This study investigates the effects of debris flow on wind turbine blade performance. In this paper, two-dimensional incompressible Navier-Stokes equations and the transition SST turbulence model are used to analyze the aerodynamic performance of NACA 63415 airfoil under clean and sandy conditions. The numerical simulation of the airfoil under clean surface condition is performed at Reynolds number 460×103, and the numerical results have a good consistency with the experimental data. The Discrete Phase Model has been used to investigate the role sand particles play in the aerodynamic performance degradation. The pressure and lift coefficients of the airfoil have been computed under different sand particles flow rates. The performance of the airfoil under different angle of attacks has been studied. Results showed that the blade lift coefficient can deteriorate by 28% in conditions relevant to the Gulf and South African countries sand storms. As a result, the numerical simulation method has been verified to be economically available for accurate estimation of the sand particles effect on the wind turbine blades

دور المرأة المسلمة في بناء المجتمع الإنساني في ضوء جائحة كوفيد - 19: المجتمع الصيني نموذجا

إن جائحة كوفيد-19 تؤثر على المجتمع الإنساني عميقا واسعا، وهي تغير طريقة حياة الناس شديدا. تقدم المسلمة الصينية التي تعتير جزء مهما من المجتمع الصيني مساهمات كبيرة في دفع تطور البلاد ومكافحة فيروس كورونا والسيطرة عليه. تركز هذه الدراسة على أدوار المسلمة الصينية التي تؤديها في بناء المجتمع في ظل جائحة كوفيد-19. الكلمات الدليلية: جائحة كوفيد-19، دور المسلمات الصينية، المجتمع الصيني Abstract: The COVID-19 pandemic is affecting the human community profoundly and broadly, and it is changing the way of people's lives severely. The Chinese Muslim Women which is an important part of Chinese society, make significant contributions to promote the country's development and combating and controlling the Corona virus. The study focuses on the roles of the Chinese Muslim Woman in building society in light of the COVID-19 pandemic. Key words: COVID-19 pandemic, the role of Chinese Muslim Women, Chinese societ

اللغة الاجتماعي وآثاره في تعليم اللغة العربية للناطقين بالصينية: الحياة الاجتماعية أنموذجا = Sociolinguistics and its effects on teaching Arabic to Chinese speakers: social life as a model

علم اللغة الاجتماعي هو العلم الذى يدرس اللغة من حيث علاقتها بالمجتمع، أو العلم الذى يحاول الكشف عن القوانين والمعايير الاجتماعية التى توضح وتنظم سلوك اللغة وسلوك الأفراد نحو اللغة فى المجتمع. تختلف الحياة الاجتماعية (نحو عناصر البيئة الطبيعية والثقافة) في الدول العربية عنها في الصين كبيرا ظاهرا بينا. وقد أثرت هذه الاختلافات على عملية تعليم اللغة العربية للطلبة الصينيين بشكل مباشر شديد واسع. يركز هذا البحث على آثار الحياة الاجتماعية العادية والحياة الاجتماعية الدينية في تعليم اللغة العربية للناطقين بالصينية، كما نقدم بعض المقترحات للمعلم والمتعلم، لإصلاح عملية التعليم والتعلم، وتحسين كفاءة ونوعية التدريس، وتقوية التحصيل الدراسي، وإثارة دافعية الطلبة للتعلم، وتعزيز مبادرتهم الذاتية وميولهم ورغباتهم في الدراسة، وتوطد معرفتهم الخلفية وتوسيع آفاقهم الثقافية. الكلمات المفتاحية: علم اللغة الاجتماعي وآثاره، تعليم العربية للناطقين بالصينية، الحياة الاجتماعية Sociolinguistics is the science that studies language in terms of its relationship to society, or the science that tries to find the laws and social norms that clarify and regulate the behavior of language and the behavior of individuals towards language the social life (towards the elements of the natural environment and culture) differs in the Arab countries from the obvious in China greatly. These differences have affected the process of teaching Arabic to Chinese students directly and widely. This research focuses on the effects of normal social life and socio-religious life in teaching Arabic to Chinese speakers, and we also present some proposals to the teacher and the learner, to reform the teaching and learning process, improve the efficiency and quality of teaching, strengthen academic achievement, and raise students ’motivation to learn. And to enhance their self-initiative, tendencies, and desires to study, consolidate their background knowledge and broaden their cultural horizons. Key words: sociolinguistics and its effects, teaching Arabic to Chinese speakers, social life

The effect of temperature on the elastic precursor decay in shock loaded FCC aluminium and BCC iron

EPSRC under Established Career Fellowship grant EP/N025954/1. Trinity College Cambridge Institute of Shock Physics Research Board and the Faculty of Engineering Dean’s office at the American University of Beiru

Performance of a Wind Turbine Blade in Sandstorms Using a CFD-BEM Based Neural Network

In arid regions, such as the North African desert, sandstorms impose considerable restrictions on horizontal axis wind turbines (HAWTs), which have not been thoroughly investigated. This paper examines the effects of debris flow on the power generation of the HAWT. Computational Fluid Dynamics (CFD) models were established and validated to provide novel insight into the effects of debris on the aerodynamic characteristics of NACA 63415. To account for the change in the chord length and Reynolds number along the span of the blade and the 3D flow patterns, the power curves for a wind turbine were obtained using the Blade Element Momentum (BEM) method. We present a novel coupled application of the neural network, CFD, and BEM to investigate the erosion rates of the blade due to different sandstorm conditions. The proposed model can be scaled and developed to assist in monitoring and prediction of HAWT blade conditions. This work shows that HAWT performance can be significantly diminished due to the aerodynamic losses under sandstorm conditions. The power generated under debris flow conditions can decrease from 10 to 30% compared to clean conditions

Tixagevimab–cilgavimab for treatment of patients hospitalised with COVID-19: a randomised, double-blind, phase 3 trial

Background: Tixagevimab–cilgavimab is a neutralising monoclonal antibody combination hypothesised to improve outcomes for patients hospitalised with COVID-19. We aimed to compare tixagevimab–cilgavimab versus placebo, in patients receiving remdesivir and other standard care. Methods: In a randomised, double-blind, phase 3, placebo-controlled trial, adults with symptoms for up to 12 days and hospitalised for COVID-19 at 81 sites in the USA, Europe, Uganda, and Singapore were randomly assigned in a 1:1 ratio to receive intravenous tixagevimab 300 mg–cilgavimab 300 mg or placebo, in addition to remdesivir and other standard care. Patients were excluded if they had acute organ failure including receipt of invasive mechanical ventilation, extracorporeal membrane oxygenation, vasopressor therapy, mechanical circulatory support, or new renal replacement therapy. The study drug was prepared by an unmasked pharmacist; study participants, site study staff, investigators, and clinical providers were masked to study assignment. The primary outcome was time to sustained recovery up to day 90, defined as 14 consecutive days at home after hospital discharge, with co-primary analyses for the full cohort and for participants who were neutralising antibody-negative at baseline. Efficacy and safety analyses were done in the modified intention-to-treat population, defined as participants who received a complete or partial infusion of tixagevimab–cilgavimab or placebo. This study is registered with ClinicalTrials.gov, NCT04501978 and the participant follow-up is ongoing. Findings: From Feb 10 to Sept 30, 2021, 1455 patients were randomly assigned and 1417 in the primary modified intention-to-treat population were infused with tixagevimab–cilgavimab (n=710) or placebo (n=707). The estimated cumulative incidence of sustained recovery was 89% for tixagevimab–cilgavimab and 86% for placebo group participants at day 90 in the full cohort (recovery rate ratio [RRR] 1·08 [95% CI 0·97–1·20]; p=0·21). Results were similar in the seronegative subgroup (RRR 1·14 [0·97–1·34]; p=0·13). Mortality was lower in the tixagevimab–cilgavimab group (61 [9%]) versus placebo group (86 [12%]; hazard ratio [HR] 0·70 [95% CI 0·50–0·97]; p=0·032). The composite safety outcome occurred in 178 (25%) tixagevimab–cilgavimab and 212 (30%) placebo group participants (HR 0·83 [0·68–1·01]; p=0·059). Serious adverse events occurred in 34 (5%) participants in the tixagevimab–cilgavimab group and 38 (5%) in the placebo group. Interpretation: Among patients hospitalised with COVID-19 receiving remdesivir and other standard care, tixagevimab–cilgavimab did not improve the primary outcome of time to sustained recovery but was safe and mortality was lower. Funding: US National Institutes of Health (NIH) and Operation Warp Speed

A randomized, controlled trial of 3.0 mg of liraglutide in weight management

BACKGROUND Obesity is a chronic disease with serious health consequences, but weight loss is difficult to maintain through lifestyle intervention alone. Liraglutide, a glucagonlike peptide-1 analogue, has been shown to have potential benefit for weight management at a once-daily dose of 3.0 mg, injected subcutaneously. METHODS We conducted a 56-week, double-blind trial involving 3731 patients who did not have type 2 diabetes and who had a body-mass index (BMI; the weight in kilograms divided by the square of the height in meters) of at least 30 or a BMI of at least 27 if they had treated or untreated dyslipidemia or hypertension. We randomly assigned patients in a 2:1 ratio to receive once-daily subcutaneous injections of liraglutide at a dose of 3.0 mg (2487 patients) or placebo (1244 patients); both groups received counseling on lifestyle modification. The coprimary end points were the change in body weight and the proportions of patients losing at least 5% and more than 10% of their initial body weight. RESULTS At baseline, the mean (±SD) age of the patients was 45.1±12.0 years, the mean weight was 106.2±21.4 kg, and the mean BMI was 38.3±6.4; a total of 78.5% of the patients were women and 61.2% had prediabetes. At week 56, patients in the liraglutide group had lost a mean of 8.4±7.3 kg of body weight, and those in the placebo group had lost a mean of 2.8±6.5 kg (a difference of -5.6 kg; 95% confidence interval, -6.0 to -5.1; P<0.001, with last-observation-carried-forward imputation). A total of 63.2% of the patients in the liraglutide group as compared with 27.1% in the placebo group lost at least 5% of their body weight (P<0.001), and 33.1% and 10.6%, respectively, lost more than 10% of their body weight (P<0.001). The most frequently reported adverse events with liraglutide were mild or moderate nausea and diarrhea. Serious events occurred in 6.2% of the patients in the liraglutide group and in 5.0% of the patients in the placebo group. CONCLUSIONS In this study, 3.0 mg of liraglutide, as an adjunct to diet and exercise, was associated with reduced body weight and improved metabolic control. (Funded by Novo Nordisk; SCALE Obesity and Prediabetes NN8022-1839 ClinicalTrials.gov number, NCT01272219.)

Expression of the Argonaute protein PiwiL2 and piRNAs in adult mouse mesenchymal stem cells

Piwi (P-element-induced wimpy testis) first discovered in Drosophila is a member of the Argonaute family of micro-RNA binding proteins with essential roles in germ-cell development. The murine homologue of PiwiL2, also known as Mili is selectively expressed in the testes, and mice bearing targeted mutations of the PiwiL2 gene are male-sterile. PiwiL2 proteins are thought to protect the germ line genome by suppressing retrotransposons, stabilizing heterochromatin structure, and regulating target genes during meiosis and mitosis. Here, we report that PiwiL2 and associated piRNAs (piRs) may play similar roles in adult mouse mesenchymal stem cells. We found that PiwiL2 is expressed in the cytoplasm of metaphase mesenchymal stem cells from the bone marrow of adult and aged mice. Knockdown of PiwiL2 with a specific siRNA enhanced cell proliferation, significantly increased the number of cells in G1/S and G2/M cell cycle phases and was associated with increased expression of cell cycle genes CCND1, CDK8, microtubule regulation genes, and decreased expression of tumor suppressors Cables 1, LATS, and Cxxc4. The results suggest broader roles for Piwi in genome surveillance beyond the germ line and a possible role in regulating the cell cycle of mesenchymal stem cells