63 research outputs found
Analisis pelaksanaan konsep hisbah dalam pentadbiran audit syariah di Bank Islam Malaysia Berhad / Sanusi Abdul Manaf
No full textShariah audit administration of Islamic Financial Institutions (IFIs) face several challenges when addressing various issues related to the implementation of Shariah compliance. Key issues include auditor qualifications, Shariah compliance in the development and promotion of products and services, and policies for addressing the issue of Shariah non-compliance. Addressing these issues requires consideration of the concept of Íisbah in the history of Islamic administration. In relation to this, the primary purpose of this study is an examination of theories of Íisbah found in both classical and modern references. Additionally, the study aims to compare elements of contemporary Shariah audit practices in such contexts as the Shariah Governance Framework for Financial Institutions (SGF) to determine similarities and differences among such frameworks to assist in the proposed consolidation of Shariah audit administration in IFIs. The importance of this study is in helping strengthen elements of Íisbah to act as a value-added feature of Shariah administrative audit systems in Malaysia. A qualitative methodology was adopted for this qualitative field study. To obtain information and data, the author examined a number of classic and modern works, as well as examining documentation and conducting interviews. Data from these three methods were analysed to accurately address the research questions. The study found that within the concept of Íisbah, elements of muÍtasib, muÍtasab fih, muÍtasab alaih and nafs al-iÍtisab are considered in the audit system of Bank Islam Malaysia Berhad (BIMB) and the SGF framework. It is hoped that the presence of elements of Íisbah will lead BIMB to seriously promote a Sharia administrative audit system which correctly carries out the functions of Íisbah elements in the context of the Íisbah concept
Ice Accretion on Fixed-Wing Unmanned Aerial Vehicle—A Review Study
No full textIce accretion on commercial aircraft operating at high Reynolds numbers has been extensively studied in the literature, but a direct transformation of these results to an Unmanned Aerial Vehicle (UAV) operating at low Reynolds numbers is not straightforward. Changes in Reynolds number have a significant impact on the ice accretion physics. Previously, only a few researchers worked in this area, but it is now gaining more attention due to the increasing applications of UAVs in the modern world. As a result, an attempt is made to review existing scientific knowledge and identify the knowledge gaps in this field of research. Ice accretion can deteriorate the aerodynamic performance, structural integrity, and aircraft stability, necessitating optimal ice mitigation techniques. This paper provides a comprehensive review of ice accretion on fixed-wing UAVs. It includes various methodologies for studying and comprehending the physics of ice accretion on UAVs. The impact of various environmental and geometric factors on ice accretion physics is reviewed, and knowledge gaps are identified. The pros and cons of various ice detection and mitigation techniques developed for UAVs are also discussed
On the Fidelity of RANS-Based Turbulence Models in Modeling the Laminar Separation Bubble and Ice-Induced Separation Bubble at Low Reynolds Numbers on Unmanned Aerial Vehicle Airfoil
No full textThe operational regime of Unmanned Aerial Vehicles (UAVs) is distinguished by the dominance of laminar flow and the flow field is characterized by the appearance of Laminar Separation Bubbles (LSBs). Ice accretion on the leading side of the airfoil leads to the formation of an Ice-induced Separation Bubble (ISB). These separation bubbles have a considerable influence on the pressure, heat flux, and shear stress distribution on the surface of airfoils and can affect the prediction of aerodynamic coefficients. Therefore, it is necessary to capture these separation bubbles in the numerical simulations. Previous studies have shown that these bubbles can be modeled successfully using the Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS) but are computationally costly. Also, for numerical modeling of ice accretion, the flow field needs to be recomputed at specific intervals, thus making LES and DNS unsuitable for ice accretion simulations. Thus, it is necessary to come up with a Reynolds-Averaged Navier–Stokes (RANS) equation-based model that can predict the LSBs and ISBs as accurately as possible. Numerical studies were performed to assess the fidelity of various RANS turbulence models in predicting LSBs and ISBs. The findings are compared with the experimental and LES data available in the literature. The structure of these bubbles is only studied from a pressure coefficient perspective, so an attempt is made in these studies to explain it using the skin friction coefficient distribution. The results indicate the importance of the use of transition-based models when dealing with low-Reynolds-number applications that involve LSB. ISB can be predicted by conventional RANS models but are subjected to high levels of uncertainty. Possible recommendations were made with respect to turbulence models when dealing with flows involving LSBs and ISBs, especially for ice accretion simulations
Ice Accretion on Rotary-Wing Unmanned Aerial Vehicles—A Review Study
No full textIce accretion on rotary-wing unmanned aerial vehicles (RWUAVs) needs to be studied separately from the fixed-wing UAVs because of the additional flow complexities induced by the propeller rotation. The aerodynamics of rotatory wings are extremely challenging compared to the fixed-wing configuration. Atmospheric icing can be considered a hazard that can plague the operation of UAVs, especially in the Arctic region, as it can impose severe aerodynamic penalties on the performance of propellers. Rotary-wing structures are more prone to ice accretion and ice shedding because of the centrifugal force due to rotational motion, whereby the shedding of the ice can lead to mass imbalance and vibration. The nature of ice accretion on rotatory wings and associated performance degradation need to be understood in detail to aid in the optimum design of rotary-wing UAVs, as well as to develop adequate ice mitigation techniques. Limited research studies are available about icing on rotary wings, and no mature ice mitigation technique exists. Currently, there is an increasing interest in research on these topics. This paper provides a comprehensive review of studies related to icing on RWUAVs, and potential knowledge gaps are also identified
Improved magnetic properties of barium hexaferrite by CoFe2O4 nanoparticles prepared by ultrasonic irradiation
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The effect of milling time and sintering temperature on Mn, Ti substituted barium hexaferrite nanoparticle
No full textCorrigendum: Performance evaluation of five commercial assays in assessing seroprevalence of HEV antibodies among blood donors
No full textThe affiliation for author Lukman Thalib was incorrectly listed as number 5. It should have been listed as number 3. Please see corrected author and affiliation list below:
Enas S. Al-Absi,1,2 Duaa W. Al- Sadeq,1 Manaf H. Younis,3 Hadi M. Yassine,2 Omnya M. Abdalla,1 Areej G. Mesleh,1 Tameem A. Hadwan,1 Joshua O. Amimo,4,5 Lukman Thalib,3 and Gheyath K. Nasrallah1,2,*
1 Department of Biomedical Science, College of Health Sciences, Qatar University, Doha, Qatar
2 Biomedical Research Center, Qatar University, Doha, Qatar
3 Department of Public Health, College of Health Sciences, Qatar University, Doha, Qatar
4 Department of Animal Production, Faculty of Veterinary Medicine University of Nairobi, Nairobi, Kenya
5 Biosciences of Eastern and Central Africa-International Livestock Research Institute (BecA-ILRI), Nairobi, Kenya
The authors apologize for any inconvenience caused.
© 2019 The AuthorsNo Full Tex
Steady and Time Dependent Study of Laminar Separation Bubble (LSB) behavior along UAV Airfoil RG-15
No full textThe flow around the Unmanned Arial Vehicle (UAV) operating at a low Reynolds number regime of the O() is predominantly laminar and it leads to the formation of Laminar Separation Bubble (LSB). The pressure, shear stress, and heat flux distribution are considerably affected by LSB, which affects lift, drag, and pitching moment values. Most existing RANS (Reynolds-Averaged Navier-Stokes) turbulence models are built on the assumption of fully turbulent flow. Therefore, these models require additional transport equations or reformulations or specific transition information to predict the LSB observed in low Reynolds number transition flows. Steady and transient computational fluid dynamics simulations were done using the RANS based transition turbulence model to study the behavior of LSB on UAV airfoil RG-15. The transition turbulence model can predict the LSB with considerable accuracy. The steady state and time averaged simulation results are matching in the pre stall region but deviates after stalling. High amplitude velocity fluctuations were observed near regions of transition and separation
Structural and magnetic properties of (Ba1-xLax)Fe12O19 obtained by mechanical alloying and ultrasonic irradiation
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