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Search Results: 1 - 10 of 132 matches for " Jamel Orfi "
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Evaporation of Water by Natural Convection in Partially Wetted Heated Vertical Plates: Effect of the Number of the Wetted Zone
Abdelaziz Nasr,Chokri Debissi,Amine Belhadj Mohamed,Jamel Orfi,Sassi Ben Nasrallah
Journal of Engineering and Applied Sciences , 2012,
Abstract: This research consists of a numerical investigation of coupled heat and mass transfers by natural convection during water evaporation in a vertical channel. The two channel walls were symmetrically heated by a uniform flux density. One wall is partially wetted by an extremely thin water film and the other is dry. The partially humid plate is divided into 2N with equal lengths being alternatively wet and dry zones. The results are reported in terms of local Sherwood number, the inlet velocity and evaporative rate for different wet zone position and for different wet number zones. However, the mass transfer is extremely influenced by the number of the wetted zones and their positions. The evaporative rate is more intense when the wetted zone is situated at the channel exit. Finally, it is observed that the evaporation is intensified by increasing the number of wetted zones.
Numerical Analysis of the Evaporation of Water by Forced Convection into Humid Air in Partially Wetted Vertical Plates
Chokri Debissi Hfaiedh,Abdelaziz Nasr,Jamel Orfi,Amine Belhadj Mohamed,Sassi Ben Nasrallah
Journal of Engineering and Applied Sciences , 2012,
Abstract: The present study focuses on a numerical investigation of steady conjugated heat and mass transfers by forced convection in an externally heated or insulated channel. One wall is partially wetted by an extremely thin water film, while the other is dry and impermeable. The partially humid plate is divided into 2.n equal regions, which are alternately humid and dry zones. The effect of the number of wetted zones and their positions on the flow, on the heat and mass transfers is analysed. The results are reported in terms of axial distribution of wall temperature, relative heat fluxes and evaporative rate for different wetted zone positions. It is noticed that the change of the wetted zone position has no significant effect on the moist air flow. However, the heat and mass transfers are extremely influenced by the presence of the wetted zones and their positions. As the condition of an insulated channel, the evaporative rate is more intense when the wetted zone is situated at the channel entrance. In case of the condition of a heated wall channel, the situation is generally inversed. It is also shown that there exists a critical value for the density heat flux from which the behaviour of the evaporative rate is reversed. Finally, it is noticed that the evaporation is intensified by increasing the number of humid zones.
Groups of order 2048 with three generators and three relations
S. Fouladi,R. Orfi
International Journal of Group Theory , 2012,
Abstract: It is shown that there are exactly seventy-eight 3-generator 2-groups of order $2^{11}$ with trivial Schur multiplier. We then give 3-generator, 3-relation presentations for forty-eight of them proving that these groups have deficiency zero.
Noninner automorphisms of order p in finite p-groups of coclass 2, when p > 2
S. Fouladi,R. Orfi
Mathematics , 2013, DOI: 10.1017/S0004972714000331
Abstract: It is shown that if G is a finite p-group of coclass 2 with p > 2, then G has a noninner automorphism of order p.
Groups of Order 2048 with Three Generators and Three Relations
Shirin Fouladi,Reza Orfi
Mathematics , 2011,
Abstract: It is shown that there are exactly seventy-eight 3-generator 2- groups of order 2^11 with trivial Schur multiplier. We then give 3-generator, 3-relation presentations for forty-eight of them proving that these groups have deficiency zero.
Enhancement of Characteristics of Antenna Arrays Employing S-Shaped Resonators  [PDF]
Belgacem Aouadi, Jamel Belhaj Tahar
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2012, DOI: 10.4236/jemaa.2012.48045
Abstract: This paper illustrates a simple kind of tri-band printed G-shaped monopole antenna for Multiple-Input-Multiple-Output (MIMO) systems. The proposed antenna is used to achieve three operating frequencies, 2.45 GHz, 5.2 GHz and 8.2 GHz for wireless communications. To improve the isolation between the two radiating elements, we use left-handed materials composed of only S-shaped resonators to get negative refractive index at the three operating frequencies. When one layer of S-shaped resonators is employed, the antenna correlation, the diversity gain and the bandwidth are also enhanced. The simulated results are presented and evaluated with and without left-handed materials.
Entrepreneurship Motivation: Tunisian Case  [PDF]
Jamel Choukir, Mouna Baccour Hentati
American Journal of Industrial and Business Management (AJIBM) , 2013, DOI: 10.4236/ajibm.2013.38085
Abstract:

The entrepreneurship option was launched in Tunisia nearly one decade ago. The firm creation process seemed to be initiated especially to absorb the increasing number of undergraduates and graduates. Therefore, the main aim of the present research is to highlight the entrepreneurship motivation as a social issue and to understand the link existing between motivator factors and economic and social success. Hence, a survey by questionnaire was conducted based on 100 respondents representing Tunisian entrepreneurs. The results revealed that there are links between motivator factors and entrepreneurship as well as some ties between entrepreneurship, motivator factors and the antecedents, especially concerning gender, age and family background. The results have shown some differences existing between male and female entrepreneurs. Male entrepreneursmotivator factors are in the same importance with push and pull ones. Female entrepreneurs’ motivator factors are rather emotional. These results are statistically significance. Thus, the finding would be useful for the stakeholders to understand the entrepreneurship dynamic.

 

CARACTERISATION DES RELATIONS BINAIRES FINIES D-DEMI-RECONSTRUCTIBLES
DAMMAK,JAMEL;
Proyecciones (Antofagasta) , 2003, DOI: 10.4067/S0716-09172003000100003
Abstract: given a binary relation r of basis e, we define its dual r*by r* (x, y) = r(y, x). a relation r is self-dual if it is isomorphic to r*. a binary relation r' is hemimorphic to r, if it is isomorphic to r or to r*. a binary relation r is d-half-reconstructible if it is determined by its restrictions of cardinality d, up to hemimorphism. in this paper we characterize the finite binary relations d-half-reconstructibile for every d ?í7, 8, 9, 10, 11y.
LE SEUIL DE RECONSTRUCTIBILITé PAR LE HAUT MODULO LA DUALITé DES RELATIONS BINAIRES FINIES
DAMMAK,JAMEL;
Proyecciones (Antofagasta) , 2003, DOI: 10.4067/S0716-09172003000300004
Abstract: given a binary relation r of basis e ,wedefine its dual r by r (x,y )=r (y,x ).arelation r is self-dual if it is isomorphic to r .abinaryrelation r 0 is hemimorphic to r ,ifitisisomor-phic to r or to r .arelation r defined on n elements is ( ?k )-half - reconstructible if it is determined, up to hemimorphism, by its restrictions of cardinality (n ?k ). from [8] follows the ( ?d )-half-reconstructibility of finite binary relations, for all d 312.weestab-lish the ( ?d )-half-reconstructibility of finite binary relations, for all d ?{ 11 ,10 ,9 ,8 ,7 ,6 } .
LA (-5)-DEMI-RECONSTRUCTIBILITéDES RELATIONS BINAIRES CONNEXES FINIES
DAMMAK,JAMEL;
Proyecciones (Antofagasta) , 2003, DOI: 10.4067/S0716-09172003000300002
Abstract: given a binary relation r of basis e ,wedefine its dual r *by r *(x,y )=r (y,x ).arelation r is self-dual if it is isomorphic to r *. a binary relation r 0 is hemimorphic to r ,ifitisisomorphicto r or to r *. a binary relation r is d -half-reconstructible if it is determined by its restrictions of cardinality d , up to hemimorphism. in this paper we obtain : the finite connected binary relations of cardinality n =12 are (n -5)-half -reconstructible
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