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Search Results: 1 - 10 of 118030 matches for " T Hassen "
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Effect of Fiber Weight Ratio and Fiber Modification on Flexural Properties of Posidonia-Polyester Composites  [PDF]
S. Zannen, L. Ghali, M. T. Halimi, M. Ben Hassen
Open Journal of Composite Materials (OJCM) , 2016, DOI: 10.4236/ojcm.2016.63007
Abstract: The main objective of this research is to study the effect of fiber weight ratio and chemical fiber modification on flexural properties of composites reinforced with Posidonia fiber. An unsaturated polyester matrix reinforced with untreated and treated Posidonia fibers was fabricated under various fiber weight ratios. Results showed that the combined chemical treatment provided better mechanical properties of composites in comparison with untreated fiber. The fiber weight ratio influenced the flexural properties of composites. Indeed, a maximum value of flexural modulus was observed for 10% fiber weight ratio for composites reinforced with treated fibers. SEM photographs revealed a different fracture surface between Posidonia fibers reinforced polyester composites.
Effect of the Doping Layer Concentration on Optical Absorption in Si δ-Doped GaAs Layer  [PDF]
Hassen Dakhlaoui
Optics and Photonics Journal (OPJ) , 2012, DOI: 10.4236/opj.2012.23020
Abstract: We study in this paper the intersubband optical absorption of Si doped GaAs layer for different applied electric fields and donors concentration. The electronic structure has been calculated by solving the Schr?dinger and Poisson equations self-consistently. From our results, it is clear that the subband energies and intersubband optical absorption are quite sensitive to the applied electric field. Also our results indicate that the optical absorption depends not only on the electric field but also on the donor’s concentration. The results of this work should provide useful guidance for the design of optically pumped quantum well lasers and quantum well infrared photo detectors (QWIPs).
Saudi Arabian Humanitarian Aid in Crises Management Periods  [PDF]
Hassen Altalhi
Open Journal of Political Science (OJPS) , 2017, DOI: 10.4236/ojps.2017.73031
Abstract: Saudi Arabia is among the first countries in the world to develop global programs for providing humanitarian aid of relief to communities stricken by natural and manmade disasters or regions severely impacted by catastrophic wars. The government of Saudi Arabia provides such humanitarian aid through the auspices of the United Nations and other official organizations such as the World Bank and nongovernmental organizations (NGOs). The Saudi humanitarian support is not limited only to Arab and Muslim countries, but is extended internationally regardless of nationality and cultural differences. Saudi Arabia does not merely provide humanitarian aid for recovery from natural disasters, but also supplies donations in the form of cash or developing projects to developing countries, impacted by critical disasters such as drought and poverty. Saudi Arabia performs or provides free medical assistance for children in various parts of the world and has earned the characterization “Kingdom of Humanity” due to these initiatives. The present study summarizes the contributions of Saudi Arabia to humanitarian relief.The study entailed the use of available data collected from various sources that have been used in former research for the period of (2005-2015).
Solar Thermal Aquaculture System Controller Based on Artificial Neural Network  [PDF]
Doaa M Atia, Faten H Fahmy, Ninet M Ahmed, Hassen T Dorrah
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.38099
Abstract: Temperature is one of the most principle factors affects aquaculture system. The water temperature is very important parameter for shrimp growth. It can cause stress and mortality or superior environment for growth and reproduction. The required temperature for optimal growth is 34oC, if temperature increase up to 38oC it causes death of the shrimp, so it is important to control water temperature. Solar thermal water heating system is designed to supply an aquaculture pond with the required hot water in Mersa Matruh in Egypt as presented in this paper. This paper introduces a complete mathematical modeling and MATLAB SIMULINK model for the solar thermal aquaculture system. Moreover the paper presents the control of pond water temperature using artificial intelligence technique. Neural networks are massively parallel processors that have the ability to learn patterns through a training experience. Because of this feature, they are often well suited for modeling complex and non-linear processes such as those commonly found in the heating system. They have been used to solve complicated practical problems. The simulation results indicate that, the control unit success in keeping water temperature constant at the desired temperature by controlling the hot water flow rate.
Ultraviolet Radiation for Microorganism Inactivation in Wastewater  [PDF]
Brahmi Mounaouer, Hassen Abdennaceur
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.32024
Abstract: The purpose of this research stream is to evaluate the kinetics of bacterial strains of Pseudomonas aeruginosa, to establish the influence of UV doses on the kinetics of disinfection, to study UV-resistant strains of Pseudomonas aeruginosa, and to underline the influence of suspended solids on the inactivation kinetics of these strains. Furthermore, and due to the lack of readily available information about the influence of temperature on microorganism inactivation processes subsequent to inactivation with UV radiation, a series of batch studies were performed at 5℃, 25?C, 37.5℃ and 50℃. This paper investigates the impact of UV irradiation on bacterial strains of P. aeruginosa inactivation in both primary and secondary wastewater effluents and to show the influence of filtration in the process of disinfection of water by UV irradiaton. Our results indicate that the effect of temperature within the normal operating range of most treatment plants, i.e., 25℃ to 37.5℃, was found to be not statistically significant on the kinetics of the UV disinfection process. However, the kinetics of the UV disinfection process was highly affected by system operating at extreme temperatures, i.e., at 10 and 50℃. In a temperature range of 25℃ to 37.5℃, the inactivation of P. aeruginosa strains varied according to the incubation time and did not exceed 4 U-Log. Consequently, having more than 102 organisms/100ml of P. aeruginosa in treated wastewater would cause serious health and environmental problems. Low inactivation was observed when the operating temperature was reduced to 10℃ regardless of the incubation time tested. In contrast, a considerable increase in the inactivation rate was noted when the temperature of the disinfected wastewater was increased to 50℃. Hence, as 5℃ and 50℃ are outside the operating range of most treatment plants, as in our country, Tunisia, it is reasonable to assume that the effect of temperature change on the kinetics of UV disinfection process is negligible.
Some Remarks on the Rights and Responsibilities of Founders under the Ethiopian Commercial Code  [PDF]
Sitelbenat Hassen Yahya
Beijing Law Review (BLR) , 2017, DOI: 10.4236/blr.2017.84026
Abstract: Companies do not suddenly come in to being. Rather they require the effort and struggle of some individuals which are in most cases called Founders. Therefore, we can say companies are formed by the voluntary act of founders conforming to the general norms established by Commercial laws. Accordingly, in order to bring the company into existent these individuals need to enter in to contract and to transact with third parties. As a result of these, rights, responsibilities and liabilities of these individuals may arise which in turn calls for a deeper thought from the eyes of the Law. Hence, the main thrust of this article is to identify the major rights and responsibilities of founders that are found under the Ethiopian commercial code. This being the aim it will also explore the various attempts made to define founder. In doing so, the paper finds out that the word founder has not been defined anywhere in the commercial code. Moreover, the paper will discuss the experience of other countries at a glance, in order to give some lesson for the country. Therefore, the writer based on the analyses of relevant literature and experiences of countries, argues that, the commercial code of Ethiopia is not comprehensive enough to regulate the rights and responsibilities of founders and to protect the interest of third parties as well. More importantly, the commercial code fails to clearly stipulate the specific rights and responsibilities of founders; because one can only be acquainted with all the rights and responsibilities after consulting other related laws/proclamations. Consequently, the writer recommends for the proper amendment of the commercial code on issues that relates to founders, considering the changes occurred from the time where the commercial code come in to effect.
Genetic variability of five indigenous Ethiopian cattle breeds using RAPD markers
F Hassen, E Bekele, W Ayalew, T Dessie
African Journal of Biotechnology , 2007,
Abstract: Genetic diversity is the basis for present day diversified living systems and future genetic improvement needs. This diversity should be properly utilized, improved and conserved. Conservation and improvement strategies ought to be based on proper genetic characterization in association with phenotypic characterization. The objective of this work was to assess between and within breed genetic variability of five indigenous Ethiopian cattle breeds (Horro, Sheko, Arsi, Abigar and Guraghe highland) using RAPD markers. The Guraghe highland and Arsi breeds fall under Zebu breed group, the Sheko come from Humpless Shorthorn, the Abigar from the Sanga group and the Horro from Zenga group. Genetic relationships were estimated using three primers which produced 33 loci. The gene diversity obtained in this study was found to be moderate and Analysis of Molecular Variance revealed that within breed genetic variation is much higher than that between breeds. Except few cases, genetic differentiation was highly significant. The smallest genetic divergence was between Guraghe highland and Abigar followed by Guraghe highland and Arsi. Sheko, historically considered to be humpless shorthorn, formed a distinct cluster whereas the remaining breeds formed another cluster. The RAPD markers were found to be useful to distinguish the breeds studied, but they failed to differentiate between Guraghe Highland and Abigar as they did the two zebu breeds -Guraghe Highland and Arsi. The Pearson’s correlation between genetic and geographic distances (r = 0.22) was found to be statistically insignificant (P > 0.05).
Spatial Analysis on the Concentrations of Air Pollutants in Basra Province (Southern Iraq)  [PDF]
Shukri I. Al-Hassen, Abdul Wahab A. Sultan, Adnan A. Ateek, Hamid T. Al-Saad, Salah Mahdi, Abdulzahra A. Alhello
Open Journal of Air Pollution (OJAP) , 2015, DOI: 10.4236/ojap.2015.43013
Abstract: This paper aims to analyze the geographic distribution of air pollutant concentrations in Basra Province, Southern Iraq, and to cartographically determine the spatial variation of air pollution levels as well as to recognize the hottest spots of air pollution within the study area, and conclude that the levels of air pollution in the study area are spatially varied, with an irregular spatial pattern and some hotspots.
Theoretical Study of Electronic Transmission in Resonant Tunneling Diodes Based on GaAs/AlGaAs Double Barriers under Bias Voltage  [PDF]
Shaffa Abdullah Almansour, Dakhlaoui Hassen
Optics and Photonics Journal (OPJ) , 2014, DOI: 10.4236/opj.2014.43006
Abstract:

In this paper, we theoretically study the quantum size effects on the electronic transmission and current density of the electrons in GaAs/AlGaAs resonant tunneling diodes by solving the coupled equations Schrodinger-Poisson self-consistently. It is found that the resonant peaks of the trans-mission coefficients shift towards the lower energy regions as the applied bias voltage increases. Our results indicate that the transmission coefficient depends strongly on the variation of the thickness of collector and emitter. We also study the effect of the doping concentration located in the emitter and collector regions on the transmission and current density. We found that the dop-ing concentration can greatly affect the transmission coefficient and the current density; in partic-ular it increases the peak of the current density and displaces the position of the maxima of the current dependence on the applied bias voltage.

Some Coupled Fixed Point Results on Partial Metric Spaces
Hassen Aydi
International Journal of Mathematics and Mathematical Sciences , 2011, DOI: 10.1155/2011/647091
Abstract: We give some coupled fixed point results for mappings satisfying different contractive conditions on complete partial metric spaces. 1. Introduction and Preliminaries For a given partially ordered set , Bhaskar and Lakshmikantham in [1] introduced the concept of coupled fixed point of a mapping . Later in [2], Círíc and Lakshmikantham investigated some more coupled fixed point theorems in partially ordered sets. The following is the corresponding definition of a coupled fixed point. Definition 1.1 (see [3]). An element is said to be a coupled fixed point of the mapping if and . Sabetghadam et al. [4] obtained the following. Theorem 1.2. Let be a complete cone metric space. Suppose that the mapping satisfies the following contractive condition for all where are nonnegative constants with . Then, has a unique coupled fixed point. In this paper, we give the analogous of this result (and some others in [4]) on partial metric spaces, and we establish some coupled fixed point results. The concept of partial metric space was introduced by Matthews in 1994. In such spaces, the distance of a point in the self may not be zero. First, we start with some preliminaries definitions on the partial metric spaces [3, 5–13]. Definition 1.3 (see ([6–8])). A partial metric on a nonempty set is a function such that for all :(p1) , (p2) , (p3) , (p4) . A partial metric space is a pair such that is a nonempty set and is a partial metric on . Remark 1.4. It is clear that if , then from (p1), (p2), and (p3), . But if , may not be 0. If is a partial metric on , then the function given by is a metric on . Definition 1.5 (see ([6–8])). Let be a partial metric space. Then, (i)a sequence in a partial metric space converges to a point if and only if ;(ii)a sequence in a partial metric space is called a Cauchy sequence if there exists (and is finite) ;(iii)a partial metric space is said to be complete if every Cauchy sequence in converges to a point , that is, . Lemma 1.6 (see ([6, 7, 9])). Let be a partial metric space;(a) is a Cauchy sequence in if and only if it is a Cauchy sequence in the metric space , (b)a partial metric space is complete if and only if the metric space is complete; furthermore, if and only if 2. Main Results Our first main result is the following. Theorem 2.1. Let be a complete partial metric space. Suppose that the mapping satisfies the following contractive condition for all where , are nonnegative constants with . Then, has a unique coupled fixed point. Proof. Choose and set and . Repeating this process, set and . Then, by (2.1), we have and similarly
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