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Optical Parameters and Electrical Transport Properties of Some Barium-Sodium-Borate Glasses Doped Bismuth Oxide
Sayed M. Salem,
Taha Z. Abou-Elnasr,
Wael A. El-Gammal,
Ahmed S. Mahmoud,
Heba A. Saudi,
Ahmed G. Mostafa
Issue:
Volume 5, Issue 1, June 2018
Pages:
1-8
Received:
4 January 2018
Accepted:
22 January 2018
Published:
7 February 2018
Abstract: Glasses having the composition, [(70-x) mol% B2O3- x mol% Bi2O3- 10 mol% BaO- 20 mol% Na2O, where 0≤ x ≤20], have been prepared by the melt quenching method. Density, molar volume, infrared analysis, optical parameters and Electrical properties have been thoroughly investigated. It was found that, both density and molar volume increased with the gradual replacement of B2O3 by Bi2O3 and the comparison between their experimental and empirical values confirm the amorphous nature and the random structure of all samples. The obtained infrared results indicated that different structural borate groups appeared such as BO4 units (in di-, tri- and penta-borate groups) and BO3 units (in meta- and ortho-borate chains). Also, both BiO3 and BiO6 are present in all Bi doped glasses, and the BiO3 / BiO6 ratio appeared to be approximately stable as Bi2O3 was increased to 15 mol%, then it showed a jump increase when BiO3 reached 20 mol%. The optical band gap energy and cut-off wavelength increased with the increase of Bi2O3 while Urbach energy decreased. On the other hand, the electrical conductivity decreased as Bi2O3 was gradually replaced by B2O3, while the activation energy increased and all samples exhibit semi-conductors behavior and the values of the exponent factor decreased gradually with temperature, which is compatible with the correlated barrier hopping conduction mechanism.
Abstract: Glasses having the composition, [(70-x) mol% B2O3- x mol% Bi2O3- 10 mol% BaO- 20 mol% Na2O, where 0≤ x ≤20], have been prepared by the melt quenching method. Density, molar volume, infrared analysis, optical parameters and Electrical properties have been thoroughly investigated. It was found that, both density and molar volume increased with the gr...
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Conventional and Advanced Composites in Aerospace Industry: Technologies Revisited
Meysam Toozandehjani,
Nuruldiyanah Kamarudin,
Zahra Dashtizadeh,
E. Yee Lim,
Ashen Gomes,
Chandima Gomes
Issue:
Volume 5, Issue 1, June 2018
Pages:
9-15
Received:
10 January 2018
Accepted:
26 January 2018
Published:
11 February 2018
Abstract: Composites as a separate class of engineering material have found many applications in aerospace industries where high performance and safety are a prime concern. A review has been done in order to provide a comprehensive analysis on various types of composites used in the aerospace industry, emphasizing on the features, properties, advantages, limitations, and emerging trends in the field.
Abstract: Composites as a separate class of engineering material have found many applications in aerospace industries where high performance and safety are a prime concern. A review has been done in order to provide a comprehensive analysis on various types of composites used in the aerospace industry, emphasizing on the features, properties, advantages, lim...
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Numerical Simulation of the Vortex Shedding Behind an Airfoil-Spoiler Configuration
Amr Guaily,
Mohamed Abdelrahman
Issue:
Volume 5, Issue 1, June 2018
Pages:
16-23
Received:
16 January 2018
Accepted:
31 January 2018
Published:
28 February 2018
Abstract: Spoilers are widely used on aircrafts as lateral control devices. Despite their wide usage, very little numerical and theoretical information exist. Numerical simulation of the full unsteady, compressible Euler’s equations over the NACA 23012 airfoil with spoiler is performed using a hybrid Least-Squares finite element/finite difference method coupled to the Newton-Raphson’s linearization technique. The flow patterns behind the spoiler are presented. The pressure coefficient over the upper and lower surfaces are successfully compared to previously published experimental work. The vortex shedding due to the existence of the spoiler is strong specially at high deflection angles. Convection of the vortices will affect the performance of the tail and so a future study of the wing-tail interaction is needed.
Abstract: Spoilers are widely used on aircrafts as lateral control devices. Despite their wide usage, very little numerical and theoretical information exist. Numerical simulation of the full unsteady, compressible Euler’s equations over the NACA 23012 airfoil with spoiler is performed using a hybrid Least-Squares finite element/finite difference method coup...
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Effect of Red Mud Particles on Scratch Resistance of Aluminum Based Metal Matrix Composites
Lokesh K. S.,
Bandu Ummaji,
Gururaj P.,
K. Rayappa,
Yashavantha J.
Issue:
Volume 5, Issue 1, June 2018
Pages:
24-29
Received:
19 January 2018
Accepted:
3 February 2018
Published:
28 February 2018
Abstract: Light weight structures reflect the most predictable aspects which are correlated with commercial usage in various applications where enhancing strength with lesser weight makes them measurable. Metals like aluminum with variety of grades acts as matrix to access the minute particles exhibits huge benefits once made by most convenient techniques to term them as metal matrix conjugates. Red mud emerges as the major waste material during production of alumina from bauxite by the Bayer’s process. It comprises of oxides of iron, titanium, aluminium and silica long with some other minor constituents. Based on economics as well as environmental related issues, enormous efforts have been directed worldwide towards red mud management issues i.e. of utilization, storage and disposal. Different avenues of red mud utilization are more or less known but none of them have so far proved to be economically viable. Hardness property is improved remarkably by introducing hard intermetallic compound into the aluminium matrix. Thereinforcing materials are generally contain Silicon carbide, alumina as constituents which are costly to inculcate as a major part so that introducing this composition in aluminium matrix leads to property enhancement for the prepared metal matrix composites. Keeping this aspect in mind the present research aim is to explore the use of red mud as a reinforcing material which contains the above said composition as well as low cost option when used with aluminium. Samples are prepared by stir casting technique. Castings are cut, turned and shaped into the required size to prepare the specimens for evaluation of hardness number of samples. It is observed that the inclusion of the red mud is drastically affecting the hardness factor of the composites. The increase of the red mud composite weight percentage has decreased the hardness indicating the formability of the material.
Abstract: Light weight structures reflect the most predictable aspects which are correlated with commercial usage in various applications where enhancing strength with lesser weight makes them measurable. Metals like aluminum with variety of grades acts as matrix to access the minute particles exhibits huge benefits once made by most convenient techniques to...
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Weibull Transformation Approach to Formulation of Reliability Model for Analysis of Filth Formation Using Zenith Grinding Machine
Casmir Onyeneke,
Samson Olorunju,
Udu Eta,
Cyril Nwaonu
Issue:
Volume 5, Issue 1, June 2018
Pages:
30-38
Received:
28 January 2018
Accepted:
8 February 2018
Published:
2 March 2018
Abstract: It is one of the major concerns of production industries to keep sustain quality products through maintenance of reliability goals which is capable of attaining to high demand of the competitive products in the societies. This is one of the motivations of using Weibull method to formulate a reliability model for grinding calcite and barite in production industries. The uniqueness of this work centers on the transformation of the Weibull cumulative function into a linear model which was used to check the level of reliability of the grinded chemicals using zenith grinding machines in manufacturing industries and to design the level of reliability suitable for further productions. These assumptions are in line with the linear transformation model following the aim of ascertaining efficiency of the grinding machines. The Weibull Cumulative distribution function was used to compare with a simple regression model to ascertain the parameter estimates which reflects the reliability levels of the production industries. When the Weibull transformation was compared to the linear model, the shape and scale parameters were estimated and used to establish the level of reliability. This research work described what happened at the various levels of production before felts started forming and developed a reliability model for the prevention of filth formation in grinding calcite and barite with zenith grinding machine in paper producing industries and other industries of similar products.
Abstract: It is one of the major concerns of production industries to keep sustain quality products through maintenance of reliability goals which is capable of attaining to high demand of the competitive products in the societies. This is one of the motivations of using Weibull method to formulate a reliability model for grinding calcite and barite in produ...
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Characteristics of the Vortical Structure in a Square Cavity with a Central Obstacle at Different Reynolds Numbers
Issue:
Volume 5, Issue 1, June 2018
Pages:
39-46
Received:
1 February 2018
Accepted:
16 February 2018
Published:
15 March 2018
Abstract: Many researchers investigated different ways of improving the mixing inside a square lid-driven cavity by proper modification of the cavity geometric configuration. The present paper investigates the characteristics of the vertical structure inside a lid-driven square cavity with a central obstacle at different Reynolds numbers. The Multiple-Relaxation-Time Lattice Boltzmann Method (MRTLBM) is used to model the flow at Reynolds numbers between 100 and 1000. The results show that the position and shape of the main cavity is highly sensitive to the flow Reynolds number while the two lower side vortices are not affected by the change of the Reynolds number or the presence of the obstacle compared to the standard lid-driven cavity case. The reported results were verified against the standard lid-driven cavity case and showed good agreement. The results also show that adding a central obstacle to the standard cavity configuration can dramatically enhance its mixing capability. The reported results have significant importance for the enhancement of the mixing mechanisms inside the cavity for heat and mass transfer applications.
Abstract: Many researchers investigated different ways of improving the mixing inside a square lid-driven cavity by proper modification of the cavity geometric configuration. The present paper investigates the characteristics of the vertical structure inside a lid-driven square cavity with a central obstacle at different Reynolds numbers. The Multiple-Relaxa...
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Reducing Viscosity of Ultra Low Sulfur Diesel with Electric Field
Enpeng Du,
Qian Zhao,
Yongxin Xiao,
Rongjia Tao
Issue:
Volume 5, Issue 1, June 2018
Pages:
56-62
Received:
5 February 2018
Accepted:
25 February 2018
Published:
16 August 2018
Abstract: Dr. Tao`s viscosity theory is a university theory can be applied to a lot of liquid suspensions with the discrepancy in permittivity or permeability between the suspended contents and the base liquid. Diesel is a mixture and can be considered as one of these liquid suspensions. We ever got pretty good test results with diesel by the electric field treatment.. But, as we know, the "2007 Highway Rule" is taking effect for a while, that is, the allowable sulfur content for ULSD (15 ppm) is much lower than the previous U.S. on-highway standard for low sulfur diesel (LSD, 500 ppm). With Dr. Tao`s theory, if the effect is only from nanoscale sulfur aggregate, once the sulfur was taken off, the effect will be decreased or even disappear. But our laboratory test shows that ULSD has 28.7% flow rate increased after we successfully chosen an optimal field strength and an optimal treatment time, which is even higher than high sulfur diesel. This makes Dr. Tao`s Viscosity Theory can be widely used and proofed it is a nanoscale structure changing reduced the viscosity which can reduce pollution and improve engine efficacy, too.
Abstract: Dr. Tao`s viscosity theory is a university theory can be applied to a lot of liquid suspensions with the discrepancy in permittivity or permeability between the suspended contents and the base liquid. Diesel is a mixture and can be considered as one of these liquid suspensions. We ever got pretty good test results with diesel by the electric field ...
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