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Aeroacoustic Investigation of Trailing-Edge Finlets

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Advances in Aerospace Science and Technology 2022年第1期7卷 1-24页

作者： yehia Salama Joana Rocha Department of Mechanical and Aerospace Engineering Carleton University Ottawa Canada

Wind tunnel testing and embedded large eddy simulations are employed to study the noise reduction of trailing-edge finlets on an airfoil. Trailing-edge finlets are shown to increase the distance between the highly energetic fluid particles and the sharp trailing edge. Experiments were conducted at different angles of attack. Wind tunnel measurements confirm that finlets reduce the broadband noise radiated by the airfoil. Results also reveal that the noise reduction of finlets is dependent on the airfoil angle of attack, and that the highest noise reduction is obtained at the largest angle of attack tested.

关键词： Wind Tunnel Testing Noise Trailing Edges Finlets Airfoil Design

Performance of Structures Exposed to Extreme High Temperature—An Overview

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Open Journal of Civil Engineering 2013年第3期3卷 154-161页

作者： Sherif yehia Ghanim Kashwani Department of Civil Engineering American University of Sharjah Sharjah UAE

Strength, durability and stability are the main criteria for material selection and design in the construction industry. Consequently, development and enhancement of construction materials is always an active and attractive field for engineers and researchers. Elevated temperature (fire) is a potential threat for any structural buildings that can cause a major damage. Response of construction materials exposed to elevated temperature or fire requires a full study and analysis with lessons learned from previous cases. In this paper, properties of the common construction materials such as concrete, steel and composite structures under high temperature events is presented and discussed. In addition, performance of advanced materials, such as Fiber Reinforced Polymer (FRP) and Concrete Filled Tubular (CFT) when exposed to high temperature was discussed. Recommendations from different design codes to increase fire resistance of structures are introduced. Finally, damage assessment of several bridges and buildings found in the literature exposed to fire events is summarized.

关键词： Construction Material Fire Resistance Impact of Fire on Structures Structural Performance

The Role Played by Blocking System over North America on the Development of Hurricane Ophelia over North Atlantic Ocean

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Journal of Geoscience and Environment Protection 2018年第12期6卷 1-20页

作者： yehia Hafez Abdulhaleem Labban Department of Meteorology King Abdulaziz University Jeddah KSA

As one of very rare and unusual tracks of hurricane Ophelia, it exists over the North Atlantic Ocean during the period of 9-17 October 2017. The present work investigates the role played by blocking system over North America on the development of hurricane Ophelia. The 6-hour daily data of NCEP/NCAR reanalysis composites for the meteorological parameters are used. The meteorological elements used in the present work are (geopotential height and meridional wind components at 500-hpa level). The domain of this data is the northern hemisphere domain. Moreover, the 6-hour data on the surface pressure at the center of hurricane Ophelia and its maximum wind through the period (9-17 October) have been used. The time series, anomaly and correlation coefficient methods have been used to analyze the meteorological data. The results revealed that the persistence of blocking high system over the North America during the period of 9-17 October 2017 controls the development, strength, and the track of hurricane Ophelia over the North Atlantic Ocean.

关键词： Blocking System North America North Atlantic Ocean Hurricane Ophelia

Characteristics and Risk Factors Attributed to Coronary Artery Disease in Women Attended Health Services in Gaza-Palestine Observational Study

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World Journal of Cardiovascular Diseases 2015年第1期5卷 9-18页

作者： yehia.a.ed Amal Jamee Faculty of Public Health Al Quds University Gaza Palestine Cardiology Department Al Shifa Hospital Gaza Palestine

Coronary artery disease (CAD) is the leading cause of death in both sexes worldwide, and becomes number one killer in women due to many factors including increase in traditional risk factors, delays in apparition of symptoms, under estimation of diagnosis test and treatment. Our study aims to identify risk factors for coronary artery disease among women with chest pain underwent coronary angiography during years (2010-2013) in cardiology center. The study design is an observational among 688 women-aged 32 - 96 years;the mean age of our study population is 61 years. Risk factors are abstracted from patients’ files. Women with documented coronaries disease tend to be older, have higher, systolic blood pressure, serum level of triglyceride, and impaired clearance creatinine. 59.4% of them are menopause with higher prevalence of hypertension and diabetes (58.6% and 63.6%). Significant positive association is found in women with myocardial infarction, unstable angina, stable angina and presence of obstructive coronary artery disease respectively (89.6%, 82.3%, 59.1%) in opposite women presented with atypical chest pain have high prevalence of normal coronaries (95.7%). About 57.6% have more than three risk factors, and 55.3% are obese or overweight. In addition, 42.1% of them have impaired systolic function. We conclude that cardiovascular risk factors are highly prevalent among Palestinians women in Gaza and the combination of risk factors is common. Interventions to minimize CAD in our population are needed.

关键词： Coronary Artery Disease Risk Factors Chest Pain Coronary Angiography Gaza Palestine

Rational Design of T-Girders via Finite Element Method

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Journal of Marine Science and Application 2021年第2期20卷 302-316页

作者： Ahmed Hammad yehia.a.del-Nasser Mohamed Shama Department of Naval Architecture and Marine Engineering Faculty of EngineeringAlexandria UniversityAlex andria 21544Egypt

The main configuration of ship construction consists of standard and fabricated stiffening members,such as T-sections,which are commonly used in *** the welding process,the nonuniform heating and rapid cooling lead to welding imperfections such as out-of-plane distortion and residual *** to these imperfections,the fabricated structural members may not attain their design load,and removing these imperfections will require extra *** present work investigated controlling these imperfections at both the design and fabrication stages.A typical fabricated T-girder was selected to investigate the problem of these imperfections using double-sided welding.A numerical simulation based on finite element modeling(FEM) was used to investigate the effects of geometrical properties and welding sequence on the magnitude of the welding imperfections of the *** FEM results were validated with the experimental measurements of a double-sided fillet *** the design stage,the optimum geometry of the fabricated T-girder was determined based on the minimum steel weight and out-of-plane ***,regarding the fabrication stage,a parametric study with two variables(geometrical properties and welding sequence)was conducted to determine the optimum geometry and welding sequence based on the minimum welding out-of-plane *** the flange thickness and reducing the breadth while keeping the T-girder section modulus constant reduced the T-girder weight and out-of-plane *** welding produced a significant reduction in the out-of-plane distortion,while an insignificant increase in the compressive residual stress occurred.

关键词： Out-of-plane distortion Finite element modeling Welding residual stresses Fabricated T-girder Section modulus

Drinking Water Treatment: pH Adjustment Using Natural Physical Field

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Journal of Biosciences and Medicines 2021年第6期9卷 55-66页

作者： Hesham Mohamed Abdal-Salam yehia Said Mahmoud Said Department of Biotechnology HST Company Cairo Egypt

Water has a pH of around (7.0), making it neither alkaline nor acidic. Alkaline is defined as a pH value greater than (7.0). The power of water to neutralize acids is measured by its alkalinity. The pH scale ranges from (pH = 0 to 14), with anything above (pH = 7.0) being alkaline, and anything below (7.0) being acidic. Much of the research up to now has been investigating the effect of adding alkaline substances to the water to increase the pH levels. Recent evidence suggests that using baking soda (sodium bicarbonate), which is an alkaline substance with a pH of about (9). While studies have shown that adding soda to water increases its alkalinity, it has a number of negative health consequences. For instance, Hypokalemia, Hypochloremia, High levels of sodium in the blood, Worsening kidney disease, Worsening heart failure, Muscle weakness and spasm, and Increased stomach acid production. The main aim of this study is to investigate a natural substance consisting of environmental elements i.e., it is derived from silica by the thermal fusion method (prepared by the authors) that raises the pH of water with a physical field of 80 cm without adding any components to the water. The results showed the effectiveness of this natural substance in its solid and liquid forms in raising the pH of water to reach 8.5 from a distance range = 80 cm, without any side effects on human health.

关键词： Alkaline Acidic Water pH Value Biotechnology Physical Field

Utilization of Recycled Coarse Aggregate in Concrete Mixes

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Journal of Civil Engineering and Architecture 2011年第6期5卷 562-566页

作者： Akmal a.delfatah Sami Tabsh Sherif yehia Civil Engineering Department American University of Sharjah UAE

In this paper, the effect of the source of recycled coarse aggregate on the properties of concrete is investigated. The tests were conducted on concrete made from three sources of recycled aggregates：（1） old concrete with unknown strength, （2） old concrete with a known compressive strength of 21 MPa, and （3） old concrete with a known strength of 42 MPa. The three sources of recycled aggregates were used to produce new concrete with a target compressive strength of 21 MPa. The first and third sources of recycled aggregates were used in producing concrete with target strength of 42 MPa. A control mix was designed with aggregates from natural sources. The research included two methods of making recycled concrete. One concrete mix was produced using the recycled aggregate and adding more water than the control mix, to reach the target slump, while the second concrete mix was produced using the same amount of water as the control mix but with additional superplasticizer to maintain the target slump. The results obtained in this research showed that the concrete compressive strength depends on the source of recycled aggregates; the stronger the source of recycled aggregate, the higher the compressive strength of the produced concrete. Furthermore, the compressive strength of the first concrete mix was about 10%-20% lower than the compressive strength of the control mix. However, when superplasticizers were used, the compressive strength was around the same value as the control mix.

关键词： Compressive strength concrete environment recycled concrete.

Hybrid Security Techniques for Internet of Things Healthcare Applications

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Advances in Internet of Things 2015年第3期5卷 21-25页

作者： Lobna yehia.a.man Khedr Ashraf Darwish Computer Science Department Faculty of Science Helwan University Cairo Egypt Information Systems Department Faculty of Computers & Information Helwan University Cairo Egypt

The Internet of Things (IoT) describes the future where every day physical objects will be connected to the internet and be able to identify themselves to other devices. IoT is a new revolution of the Internet and It will effect in a large number of applications such as smart living, smart home, healthcare systems, smart manufacturing, environment monitoring, and smart logistics. This paper provides integration, summarizes and surveys some of the security techniques especially hybrid techniques that can be applied with healthcare applications in IoT environment.

关键词： IoT Healthcare Applications Hybrid Security Techniques Body Area Networks

The Art of Talc Flotation for Different Industrial Applications

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Journal of Minerals and Materials Characterization and Engineering 2016年第3期4卷 218-227页

作者： Tawfik Refaat Boulos Suzan Sami Ibrahim Ahmed yehia Central Metallurgical Research and Development Institute (CMRDI) Cairo Egypt

Talc has found a steadily increasing number of uses such as cosmetics, steatite and cordierite ceramics, for pitch control in the paper industry and as a reinforcing filler in rubber, etc. In this research, the amenability of some Egyptian carboniferous finely disseminated talc ores to beneficiation by flotation was investigated on laboratory scale. The original talc sample is characterized by low MgO content (25.40%), low SiO2 (45.71%), high CaO content (6.32%) and high L.O.I. (11.35%), indicating its low grade. Attrition scrubbing of the crushed ores was found to be an unconventional process, not only for fine talc production, but also for proper separation of the harder carbonaceous gangue. Talc pre-concentrates, less than 0.074 μm, were prepared by attrition scrubbing in the laboratory having 8.40% L.O.I. with a yield reaching 74.70%. Cleaner talc concentrate with L.O.I. content averaging 6.70% was obtained by flotation in the presence of Aerofroth 71 with a yield reaching 64.71%. This was relatively improved by the use of a selective (quaternary amine) talc collector and in presence of a selective carbonate depressant (soda ash). Flotation of the fine ground talc (less than 22 μm) produced a talc concentrate assaying 6.90% L.O.I. with a yield recovery of 62.91%. However, different talc concentrates obtained by just natural floatability or by the use of small dose of Aerofroth 71, or by the application of quaternary amine in presence of carbonate depressant, satisfy the requirement of paper coating, ceramics production, functional filler, and pharmaceuticals applications. Tailings could also be used in carpets, roofs, and tiles production industries.

关键词： Flotation Depression Attrition Scrubbing Carbonate Separation