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Je crois devoir vous donner connaissance dès l'abord, de la façon dont un groupe d'experts fran‐çais a voulu traiter le rapport de base que je leur avais fait réserver.

The purpose of this paper is to find approximate solutions for a general class of fractional order boundary value problems that arise in engineering applications.

A newly developed semi-analytical scheme will be applied to find approximate solutions for fractional order boundary value problems. The technique is regarded as an extension of the well-established variation iteration method, which was originally proposed for initial value problems, to cover a class of boundary value problems.

It has been demonstrated that the method yields approximations that are extremely accurate and have uniform distributions of error throughout their domain. The numerical examples confirm the method’s validity and relatively fast convergence.

The generalized variational iteration method that is presented in this study is a novel strategy that can handle fractional boundary value problem more effectively than the classical variational iteration method, which was designed for initial value problems.

The economic value of tourism in developing countries — an issue? Kenya, as other developing countries, develops its tourism, principally to take advantage of its economic benefits. So far Kenya is convinced about these benefits. More doubts, however, have been raised elsewhere, including certain industrialized donor countries. One objection bases on the opinion that developing countries would obtain only minor returns from tourism. This pre‐occupancy confuses the whole travel package (which includes air‐fare, services rendered in the countries of origin and the margin for foreign tour operators) and services rendered in Kenya. As has been shown in this Ministry even for travel packages Kenya receives some 57 % of net returns (value added) in foreign exchange (F.E.). Hotel services in Kenya alone account for some 85 % of net receipts in F.E. In the particular case of imported wines and liquors it could be proved that one Shilling spent for imports yields eight Shillings in F.E.

It has become accepted, almost as an article of faith in the tourism industry, that a major option, open to both large cities and traditional resorts which wish to maintain or increase their tourism earnings, is the generation of large scale conference tourism through the construction of large convention or congress centres. Implicit in this assumption is a belief that large scale conventions will continue to occupy an important place in the tourism industry.

We have developed a two‐dimensional model for quantum‐well lasers which solves, self‐consistently, the semiconductor equations together with the complex scalar wave equation and the photon rate equation. To predict the threshold current accurately we have included the wavelength‐ and position‐dependence of the gain and the spontaneous emission. For the complex wave equation successive over relaxation (SOR) is used with two adaptive acceleration parameters for the complex wave amplitude and for the eigenvalue. Since the rate equation near threshold can be driven into divergence during iteration for a steady state solution, we have introduced a special damping technique to overcome this problem. Our model enables us to predict the characteristics of a quantum‐well laser with a minimal number of empirical constants. The output of the model includes light‐current characteristics, and the current and optical field intensity distributions. We show the results of a calculation for a graded‐index separate‐confinement heterostructure single quantum‐well (GRIN‐SCH SQW) laser.

Nombre de mots français évoquant l'accueil touristique tirent leurs racines du latin et sont, par là même, porteurs de symboles qui perdurent audelà des évolutions étymologiques.

The marketing strategy begins with the identification of human needs and discharges into the application of a combination of marketing variables (product, price, distribution, sales promotion and publicity). Motivations for buying a tourist product in an affluent society are not only the reflection of a person's physical needs. They also arise from social‐psychological needs. With the ‘erosion of traditional class‐determined patterns of behavior’, even the usual social‐class variables are losing their importance in explaining buying behavior.

First I would like to thank you for the great honour of being allowed to state my point of view on some, in my opinion very important, problems of tourism to‐day.