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Open access

Ahmed S.F. Ahmed and Vijaya Raghavan

Abstract

Amendment of soil with biochar has been shown to enhance fertility and increase crop productivity, but the specific influence of biochar on soil workability remains unclear. Select physico-mechanical and chemical properties of clay loam and sandy loam soils were measured after amendment with wood-derived biochar of two particle size ranges (0.5-425 and 425-850 µm) at five dosages ranging from 0.5 to 10% dry weight. Whereas the clay loam soil workability decreased when the finer wood-derived biochar was applied at rates of 6 or 10%, soil fertility was not enhanced. The sandy loam soil, due to Proctor compaction, significantly decreased in bulk density with 6 and 10% wood-derived biochar amendments indicating higher soil resistance to compaction.

Open access

A. Ahmed Shata, S. Abdelaty and R. Hanitsch

Potential of Electricity Generation on the Western Coast of Mediterranean Sea in Egypt

A technical and economic assessment has been made of the electricity generation by wind turbines located at three promising potential wind sites: Sidi Barrani, Mersa Matruh and El Dabaa in the extreme northwest of Egypt along the Mediterranean Sea. These contiguous stations along the coast have an annual mean wind speed greater than 5.0 m/s at a height of 10 m. Weibull's parameters and the power law coefficient for all seasons have been estimated and used to describe the distribution and behavior of seasonal winds at these stations. The annual values of wind potential at the heights of 70-100 m above the ground level were obtained by extrapolation of the 10 m data from the results of our previous work using the power law. The three stations have a high wind power density, ranging from 340-425 to 450-555 W/m2 at the heights of 70-100 m, respectively. In this paper, an analysis of the cost per kWh of electricity generated by two different systems has been made: one using a relatively large single 2 MW wind turbine and the other - 25 small wind turbines (80 kW, total 2 MW) arranged in a wind farm. The yearly energy output of each system at each site was determined, and the electricity generation costs in each case were also calculated and compared with those at using diesel oil, natural gas and photovoltaic systems furnished by the Egyptian Electricity Authority. The single 2 MW wind turbine was found to be more efficient than the wind farm. For all the three considered stations the electricity production cost was found to be less than 2 ϵ cent/kWh, which is about half the specific cost of the wind farm.

Open access

S. Ahmed Shah and S. Javvad Hussaini

Abstract

The present paper is devoted to the study of phase velocity and attenuation of longitudinal shear vibrations of hollow poroelastic circular cylinders in the presence of dissipation. The explicit expressions for phase velocity and attenuation of longitudinal shear vibrations are derived. The frequency equation of longitudinal shear vibrations and modes obtained in a previous paper are used to compute the phase velocity and attenuation for different dissipations for thin and thick poroelastic cylindrical shells and poroelastic solid cylinder. The physical parameters of sandstone saturated with kerosene and sandstone saturated with water are used for the purpose of computation. It is found that the phase velocity is linear beyond certain frequency. Phase velocity is smaller for a typical anti-symmetric mode compared to the flexural mode. It is greater for the second mode than that of the first mode. Also the phase velocity is larger for a thin poroelastic cylindrical shell than that of a thick poroelastic cylindrical shell. The same is true for attenuation also. Attenuation is very high for the considered dissipations and it increases with the increase in dissipation.

Open access

Zahra S. Ahmed and Ahmed M.S. Hussein

Abstract The effect of using tiger nut flour to improve the functional properties of gluten-free biscuit was explored. Corn flour in the biscuit formulation was replaced at three levels, 10, 20, and 30% with tiger nut flour (TNF). Biscuit containing only corn flour was used as control. Prepared biscuits were analyzed for their proximate composition, physical properties, diameter, thickness, color, texture, and were subjected to measurements using differential scanning calorimetery (DSC) and scanning electron microscopy (SEM).

Incorporation of tiger nut flour resulted in a significant increase in fibre and ash contents and in a decrease in protein content. The spread ratio of the biscuits increased significantly by increasing TNF content, which is considered a desirable quality attribute. Tiger nut-containing biscuits exhibited lower total color difference ΔE value compared to the control sample.

Thermal characteristics of TNF-containing biscuits differed significantly (P≤0.05) from the control where TNF resulted in decreased onset gelatinization temperature (To) and peak temperature (Tp). Furthermore, enthalpies of control biscuits were significantly higher than of those containing TNF; that might be due to partial gelatinization since their enthalpies were smaller than in control biscuits.

Measurement of baked biscuits texture showed that hardness and resilience values decreased when TNF content in the biscuit formulation increased. Microscopic observation revealed that TNF-containing biscuits had the most uniform and homogeneous pore distributions. These attributes probably positively influenced the quality with better surface characteristics. The results of this study revealed that incorporating TNF at the ration of 20% resulted in biscuits of superior technological quality expressed in shape, cross section structure, hardness, and surface appearance

Open access

Ahmed H. Abdel-Kareem, Hala Abousafa and Omaia S. El-Hadidi

Abstract

The results of an experimental program conducted on seventeen simply supported concrete beams to study the effect of transverse reinforcement on the behavior of the lap splice of a steel reinforcement in tension zones in high-strength concrete beams are presented. The parameters included in the experimental program were the concrete compressive strength, the lap splice length, the amount of transverse reinforcement provided within the splice region, and the shape of the transverse reinforcement around the spliced bars. The experimental results showed that the displacement ductility increased and the mode of failure changed from a splitting bond failure to a flexural failure when the amount of the transverse reinforcement in the splice region increased, and the compressive strength increased up to 100 MPa. The presence of the transverse reinforcement around the spliced bars had a pronounced effect on increasing the ultimate load, the ultimate deflection, and the displacement ductility. The prediction of maximum steel stresses for spliced bars using the ACI 318-05 building code was compared with the experimental results. The comparison showed that the effect of the transverse reinforcement around spliced bars has to be considered into the design equations for lap splice length in high-strength concrete beams.

Open access

S.A. Shah and G. Apsar

Abstract

The present paper investigates the propagation of time harmonic circumferential waves in a two-dimensional hollow poroelastic cylinder with an inner shaft (shaft-bearing assembly). The hollow poroelastic cylinder and inner shaft are assumed to be infinite in axial direction. The outer surface of the cylinder is stress free and at the interface, between the inner shaft and the outer cylinder, it is assumed to be free sliding and the interfacial shear stresses are zero, also the normal stress and radial displacements are continuous. The frequency equation of guided circumferential waves for a permeable and an impermeable surface is obtained. When the angular wave number vanish the frequency equation of guided circumferential waves for a permeable and an impermeable surface degenerates and the dilatational and shear waves are uncoupled. Shear waves are independent of the nature of surface. The frequency equation of a permeable and an impermeable surface for bore-piston assembly is obtained as a particular case of the model under consideration when the outer radius of the hollow poroelastic cylinder tends to infinity. Results of previous studies are obtained as a particular case of the present study. Nondimensional frequency as a function of wave number is presented graphically for two types of models and discussed. Numerical results show that, in general, the first modes are linear for permeable and impermeable surfaces and the frequency of a permeable surface is more than that of an impermeable surface.

Open access

S.A. Shah

Abstract

Employing Biot’s theory of wave propagation in liquid saturated porous media, waves propagating in a hollow poroelastic circular cylinder of infinite extent are investigated. General frequency equations for propagation of waves are obtained each for a pervious and an impervious surface. Degenerate cases of the general frequency equations of pervious and impervious surfaces, when the longitudinal wavenumber k and angular wavenumber n are zero, are considered. When k=0, the plane-strain vibrations and longitudinal shear vibrations are uncoupled and when k0 these are coupled. It is seen that the frequency equation of longitudinal shear vibrations is independent of the nature of the surface. When the angular (or circumferential) wavenumber is zero, i.e., n=0, axially symmetric vibrations and torsional vibrations are uncoupled. For n0 these vibrations are coupled. The frequency equation of torsional vibrations is independent of the nature of the surface. By ignoring liquid effects, the results of a purely elastic solid are obtained as a special case.

Open access

A Saeed, Malik. S. Raza and Ahmed Mohsin Khalil

Abstract

Air travelling is the second largest travelling medium used by people. In future it is expected to be the first choice for the travellers. As increase in the price of oil cost of air travelling is getting higher. Engineers are forced to find the cheaper means of travelling by innovating new techniques. This paper presents the new idea to reduce air travelling cost by reducing drag, which is major driving factor of high fuel consumption. Two-dimensional and three-dimensional shock control contour bumps have been designed and analysed for a supercritical wing section with the aim of transonic wave drag reduction. A supercritical airfoil (NACA SC (02)-0714) has been selected for this study considering the fact that most modern jet transport aircraft that operate in the transonic flow regime (cruise at transonic speeds) employ supercritical airfoil sections. It is to be noted that a decrease in the transonic wave drag without loss in lift would result in an increased lift to drag ratio, which being a key range parameter could potentially increase both the range and endurance of the aircraft. The major geometric bump parameters such as length, height, crest and span have been altered for both the two-dimensional and three-dimensional bumps in order to obtain the optimum location and shape of the bump. Once an optimum standalone three-dimensional bump has been acquired an array of bumps has been manually placed spanwise of an unswept supercritical wing and analysed under fully turbulent flow conditions. Different configurations have been tested with varying three-dimensional bump spacing in order to determine the contribution of bump spacing on overall performance. The results show a 14 percent drag reduction and a consequent 16 percent lift to drag ratio rise at the design Mach number for the optimum arrangement of bumps along the wing span. This innovative technique proves to be a bridge between economical problems and engineering solutions and a milestone for aviation engineering.

Open access

Mohmed S. Shaheen, Hamdy A. Shaaban, Ahmed M.S. Hussein, Mohamed B.M. Ahmed, Khaled El-Massry and Ahmed El-Ghorab

Abstract

In the present study the effect of chitosan/fructose Maillard reaction products (CF-MRPs) as antioxidant and antimicrobial agents was evaluated and applied on minced beef meat during frozen storage. Antioxidant and antimicrobial properties of chitosan-fructose complexes were tested. Anti-oxidant properties were measured by the DPPH, β-carotene and ABTS methods. These three methods showed the same profile of antioxidant activity. Chitosan with 4% fructose autoclaved for 45 min (CF9) showed to have the most effective antioxidant activity. It was demonstrated that the browning product exhibited antioxidant activity. For antimicrobial activity, most chitosan-fructose complexes were less effective than chitosan. Thus, MRPs derived from chitosan-sugar model system can be promoted as a novel antioxidant to prevent lipid oxidation in minced beef. Chitosan-sugar complex could be a potential alternative natural product for synthetic food additive replacement that would additionally meet consumer safety requirement.

Open access

Ahmed Ansari, Akhilesh Jain, R.S. Mittal, Achal Sharma, Anand Sharma and I. D. Gupta

Abstract

Traumatic brain injury (TBI) is a major cause of disability (1, 2). Sleep disturbances, such as insomnia, are very common following traumatic brain injury and have been reported in frequencies from 40% (3) to as high as 84% (4). Sleep disruption can be related to the TBI itself but may also be secondary to neuropsychiatric (e.g., depression) or neuromuscular (e.g., pain) conditions associated with TBI or to the pharmacological management of the injury and its consequences. Post-TBI insomnia has been associated with numerous negative outcomes including daytime fatigue, tiredness, difficulty functioning: impaired performance at work, memory problems, mood problems, greater functional disability, reduced participation in activities of daily living, less social and recreational activity, less employment potential, increased caregiver burden, greater sexual dysfunction, and also lower ratings of health, poor subjective wellbeing. These negative consequences can hamper the person’s reintegration into the community, adjustment after injury, and overall QOL. (5) The connection between depression and insomnia has not been investigated within the post TBI population to a great extent. For the general population, clinically significant insomnia is often associated with the presence of an emotional disorder (6). Fichtenberg et al. (2002) (7), in his study established that the strongest relationship with the diagnosis of insomnia belonged to depression. Given the high prevalence of depression during the first 2 years following TBI (8), a link between depression and insomnia among TBI patients makes innate sense. The present study aims at assessing role of sertralline in post TBI insomnia associated with depression.