On the Solutions of Linear, Maxilinear and Reciprocal Type Difference Equations

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Managing nitrate pollution in a Tunisian irrigated area: A multi-criteria analysis approach

In Tunisia, the extension of irrigated area is justified by its important role in the development and diversification of agricultural production. Nevertheless, the strong intensification of the agricultural activities may lead to the pollution of underground water resources due to an excess use of fertilisers and other chemical products. In fact, the high nitrate concentrations observed in some Tunisian irrigated areas, are related to the excessive use of nitrate fertilizers in intensive agriculture. The objective of the present study is to implement decision-making methods allowing a better combination of factors production by optimization of an economic objective and an environmental objective. This research is based on multi-criteria modelling through the optimization of two conflict objectives: an economic objective as settled by farmer in the short or medium-run (Gross margin), and an environmental objective (nitrate pollution reduction) as a long-run objective of the decision maker in order to ensure the continuity of agriculture activities and ecosystems sustainability. Data were collected through a survey conducted in the irrigated area of Kalaât El Andalous in Tunisia with a sample containing 57 farms. Efficient solutions were obtained and compared through the "constraints", "NISE" and "compromises" methods. Main results obtained indicate a significant degree of conflict between these two objectives. Indeed the maximization of the total gross margin involves an increase in the degrees of nitrate pollution and conversely. Finally, some policy implications are presented.Nitrate pollution, environmental impact, multicriteria analysis, Environmental Economics and Policy,

A Novel Small Sierpenski Antennas

In This paper, new small antenna is described and it is designed to be used in RFID applications at microwave frequencies. This structure represents a new version of sierpenski antenna. The reduction of size by more than 75% gives this patch a great inters.  Two equivalent resonant models are presented based on a model of triangular and sierpenski patch antennas.DOI:http://dx.doi.org/10.11591/ijece.v3i4.258

A Circuit Model to a Directive Triangular EBG Antenna

In This paper, we propose a directive triangular EBG antenna. This approach is derived from using an EBG surface near to a triangular patch with two grilles. The antenna frequency chosen is the 2.45GHz. The directive antenna is simulated by using HFSS and Electrical model. This proposed antenna presents a very high directivity

Caracteristiques et evolution des operations de fusions-acquisitions en tunisie

Cet article propose une analyse descriptive des Fusions et Acquisitions (F&A) opérées en Tunisie sur la période 1980-2009. Nous décrivons dans un premier temps l’évolution de l’économie tunisienne et la manière dont celle-ci a pu impacter la restructuration des entreprises dans ce pays. Apparu au début des années 1980, le phénomène des F&A s’est accéléré à partir de 1995 à la suite de la signature de l’accord d’association avec l’UE et l’adhésion à l’OMC. Ces opérations relèvent presque exclusivement d’une logique horizontale à finalité industrielle ou fiscale. Les parties prenantes sont dans l’écrasante majorité des entreprises locales. Les opérations de F&A sont plus fréquentes dans les secteurs industriels et ont lieu essentiellement dans le Grand Tunis et les régions côtières. Elles apparaissent enfin comme un moyen à la disposition des entreprises de grande taille afin de se développer en acquérant des PME.Mots clés : Fusions &Acquisitions, Tunisie, Industrie, Commerce

A Circuit Model to an Encoche Coplanar Antenna for a Radio Frequency Identification TAG

In this paper, Miniature Encoche Coplanar antennas are proposed. Tovalidate our structure and to develop an analytic method to determine thegeometry parameters, the Lumped theory is used. The proposed structure issimulated using ADS and then Compared to the electrical Model. Theproposed circuit has the same resonant aspect when comparing to theEncoche antenna with a much reduced simulation time. The compactcoplanar antenna has a box with a size of 36*52*0.2 mm3. This antenna willbe designed to an RFID TAG that resonates on 2.45 GHz.DOI:http://dx.doi.org/10.11591/ijece.v3i3.257

Caracteristiques et evolution des operations de fusions-acquisitions en tunisie

Cet article propose une analyse descriptive des Fusions et Acquisitions (F&A) opérées en Tunisie sur la période 1980-2009. Nous décrivons dans un premier temps l’évolution de l’économie tunisienne et la manière dont celle-ci a pu impacter la restructuration des entreprises dans ce pays. Apparu au début des années 1980, le phénomène des F&A s’est accéléré à partir de 1995 à la suite de la signature de l’accord d’association avec l’UE et l’adhésion à l’OMC. Ces opérations relèvent presque exclusivement d’une logique horizontale à finalité industrielle ou fiscale. Les parties prenantes sont dans l’écrasante majorité des entreprises locales. Les opérations de F&A sont plus fréquentes dans les secteurs industriels et ont lieu essentiellement dans le Grand Tunis et les régions côtières. Elles apparaissent enfin comme un moyen à la disposition des entreprises de grande taille afin de se développer en acquérant des PME.Mots clés : Fusions &Acquisitions, Tunisie, Industrie, Commerce

Shape sensitivity for the Laplace–Beltrami operator with singularities

AbstractThis paper considers shape sensitivity analysis for the Laplace–Beltrami operator formulated on a two-dimensional manifold with a fracture. We characterize the shape gradient of a functional as a bounded measure on the manifold and decompose it into a “distributed gradient” supported on the manifold, plus a singular part that we derive as the limit of a “jump” through the crack and Dirac measures at the crack extremities. The important point is that we introduce a technique that is not dimension dependent, and makes no use of classical arguments such as the maximum principle or continuation uniqueness. The technique makes use of a family of envelopes surrounding the fracture which enable us to relax certain terms and to overcome the lack of regularity resulting from the presence of the fracture. We use the min–max differentiation in order to avoid taking the derivative of the state equation and to manage the crack's singularities. Therefore, we write the functional in a min–max formulation on a space which takes into account the hidden boundary regularity established by the tangential extractor method