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.

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.

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.

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.

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.

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 entrepreneurs’ motivator 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.

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.

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 } .

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