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Periodicals - LEBANESE SCIENCE JOURNAL VOL.5, NO.2, 2004
Natural and Environmental Sciences
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Empirical orthogonal function analysis of sea surface temperature
patterns in the Levantine basin
N. Kabbara and T. Courp
Empirical orthogonal function (EOF) analysis of a three years advanced
very high resolution radiometer (AVHRR) sea surface temperature
(SST) data set from the Levantine Basin are used to determine the
dominant patterns of sea surface temperature (SST) variance. Monthly
averaged AVHRR data, from January 1998 to December 2000, were used
in the study. Processed SST data were retrieved from the German
Remote Sensing Center. EOF analysis was used to decompose the time
series into its component parts. Empirical decomposition implies
the analysis of anomalies of a certain parameter with respect to
a certain mean value (temporal or spatial). The analysis of a decomposition
of the spatial variance and the temporal variance modes is done
in order to identify features in AVHRR data such as fronts, eddies,
and annual temperature cycles for the Levantine Basin. The analysis
of the spatial anomalies reveals that the first mode accounts for
67.12% of the total variance. It reveals the main features of SST
in the LB, and it shows a persistent front aligned northwest southeast
which separates the colder surface water to the west from the warmer
water to the east. The amplitudes time series show a seasonal modulation,
peaking in early summer. The second gradient mode (contributing
by 14.50%) shows the presence of gyres in the study area. The analysis
of temperal anomalies shows a predominance of the first mode (98%
variance), and represents the basin-wide seasonal warming and cooling.
This mode peaks in summer and lags by 30 days the first-mode time
series revealed by the spatial variance analysis. The first covariance
mode has a weak spatial variation in the eigenvectors, while the
second and the third modes show more spatial variation. The second
and third covariance modes (covariance) carry extremely low energies
(0.82% and 0.30% respectively) and therefore they do not contain
statistically significant information on the frontal and eddy patterns
evident in the AVHRR and in situ data. Higher modes are interpreted
as the results of spring heating and fall cooling of shallow river
and waters ahead of offshore waters. Back
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Spacing effects on corm and flower production of saffron (crocus sativus)
S.K. Yau and M. Nimah
Saffron is a valuable condiment that may have the potential to invigorate
economically the Bekaa Plain, especially the Baalbeck - Hermel area,
which has suffered after the crack down on illicit crops. However,
no research on the optimal cultural practices for saffron has been
conducted locally. The objective of this study is to investigate the
effects of spacing on saffron corm and flower production. Corms were
planted by hand at three spacing densities: 20 cm x 20 cm, 20 cm x
10 cm, and 10 cm x 10 cm in October of 2000 at the Agricultural Research
and Education Center (AREC). The field experiment was in a randomized
complete block design with three replicates. Flowers were counted
and picked in October and November, and the stigmas collected, dried,
and weighed. Corms were dug up in July 2002 and measured. Density
of planting had no effect on numbers of corms produced per corm cluster,
but it had a significant effect on corm weight, which had a large
effect on flower production. By 2002, the 20 cm x 20 cm spacing gave
heavier corms, and higher flower numbers and red stigma yield per
corm cluster than the 20 cm x 10 cm and 10 cm x 10 cm spacing. Unless
corms can be purchased at markedly lower prices, farmers are recommended
to maximize flower production per corm by planting at 20 cm x 20 cm
spacing. Back
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Monitoring of groundwater salination by seawater intrusion on the
Lebanese coast
El Moujabber M., Atallah T., Darwish
T and Bou Samra B.
In order to monitor the effects of the seawater intrusion on the groundwater
quality, the coastal region from Choueifat to Rmeyle located south
Mount - Lebanon had been chosen to be studied. Six wells have been
selected. Water samples have been collected for a period of three
years from 1999 to 2002, at the rate of one sample a month. A complete
physico-chemical analysis has been done in order to measure the increase
in salinity as well as the variation in piezometric level. The results
obtained from the study showed that the regions of Choueifat, Jiye
and Rmeyle are subject to seawater intrusion. This intrusion is directly
and simultaneously related to the pumping period and intensity but
poorly related to the amount of rainfall. It also depends on the geologic
nature of the study area. Furthermore, the actual intrusion in the
study zone aggravates the existing salinity problems. Indeed the salinity
rates of well water ranged between 0.7 dS/m and 5.5 dS/m (the majority
being above 2 dS/m) resulting in salinity rates not tolerable for
crops, thus threatening their growth and production. Back
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L’atlas des localités du liban : les apports d’une
base de données des unités cartographiques élémentaires
pour l’étude de la structuration territoriale du Liban
W. Bakhos, G. Faour, E. Huybrechts et E. Verdeil
La connaissance territoriale de l’ensemble du Liban se limite
jusqu’à présent soit à des analyses globales
réalisées à des échelles nationales, de
mohafazats ou de cazas, soit à des analyses locales très
ponctuelles. Les données produites récemment par différentes
administrations permettent de porter un nouveau regard sur l’ensemble
du territoire libanais à l’échelle des circonscriptions
foncières (CF). Celles-ci sont des espaces pertinents car elles
permettent de localiser les limites des municipalités et de
groupes de localités qui sont généralement calées
sur les emprises d’une ou plusieurs circonscriptions foncières.
D’autre part, les données statistiques les plus récentes
et les plus fiables qui couvrent l’ensemble du territoire national
sont déjà produites sur la base de ces entités
spatiales.
Cette étude fournit une nouvelle cartographie à l’échelle
des 1500 circonscriptions foncières du Liban qui incluent plus
de 700 municipalités. Elle a permis la mise au point d’un
système d’information géographique (SIG) national
incluant des données diverses produites par différentes
institutions publiques au Liban. En effet, la carte des circonscriptions
foncières a été un élément principal
avec la carte d’occupation du sol dans la réalisation
du schéma directeur d’aménagement du territoire
Libanais (SDATL). Back
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Basic Sciences, Engineering and Technology
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Effets des paramètres du cristal, de l'objet
émetteur et de l'activité de la source sur l'entropie
d'une acquisition scintigraphique
M.S. Bouhdima
et I. Elloumi
Les méthodes classiques d'estimation du bruit en imagerie d'émission
monophotonique ne permettent pas d'exprimer ce dernier en fonction
des paramètres d'acquisition.
L'entropie d'une acquisition scintigraphique, qui tient compte de
trois effets statistiques (effet multiplex, incertitude spatiale et
bruit de comptage) permet de simuler l'influence de la résolution
intrinsèque du détecteur (Ri), des paramètres
de l'objet émetteur (D,v) et de l'activité de la source
(n) sur la qualité de l'acquisition.
Une expression de l'entropie, fonction explicite de ces paramètres,
est élaborée. L'accord entre les valeurs simulées
et les valeurs calculées est satisfaisant.Back
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Etude de la persistance de
la couche de phosphate de sodium formée lors du traitement
de préphosphatation : apport de la technique PDMS
A. Bakkali, B. Nsouli, H. Allali, M. Ben Embarek, J.-P. Thomas
et A. Essaadani
La spectrométrie de masse par temps de vol (PDMS), basée
sur l’émission ionique secondaire (EIS) induite par des
ions primaires lourds et rapides (ici Ar3+, 9 MeV), a été
effectuée avec succès sur des aciers Fe-Si. Ces derniers
ont subi un traitement de préphosphatation permettant l’activation
de leur surface. Nous avons montré la persistance du phosphate
de sodium après rinçage de ce type de couches préphosphatées
en utilisant cette technique, très sensible à l’extrême
surface, ce qui n’est pas évident avec les deux techniques
largement utilisées dans ce domaine, à savoir la SDL(Spectrométrie
à Décharge Luminescente) et l’ESCA.Back
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Programmable generator dedicated to the preoperative cochlear stimulation
H. Ghariani, S. Zouari, A. Ben hamida, Gh. Besbes and M.
Ghorbel
This study is about specific signal generation useful for preoperative
electrical stimulation of the cochlea. The proposed generator was
intended to check the state of the cochlea's nervous zones of one
candidate to cochlear prosthesis apparatus. In fact, this cochlear
stimulator would allow the insertion of an electrode into the round
window to verify the state of intact nervous zones. Such clinical
diagnosis is a useful preoperative evaluation to assure the effectiveness
of this apparatus. Originalities in preoperative stimulation techniques
of the cochlea were then presented. The overall conceived system included
one electronic stage for signal generation dedicated to the stimulation
of the nervous zones, as well as a communication software offering
to clinicians the control by a graphical module displayed on a host-computer
screen. This study was based on a fundamental criterion that was the
flexibility and handiness during clinical experimentation. The system
for cochlear stimulation was henceforth an electronic apparatus driven
by a processor, a 'micro controller', which could be interfaced to
the host-computer. The latter displays a graphical module reassembling
all the stimulation possibilities around a great flexibility and handiness.
In fact, the 'micro controller' used has allowed the generation of
different forms of signals for stimulation: thanks to its programming,
it was also possible to adjust with great flexibility different parameters
such as the stimulation rhythm, the frequency, the amplitude and the
stimulation pulses' shape. The signals' shapes proposed here were
various: the rectangular shape frequently used, the triangular shape
in staircase with different orders and the serrated shape (saw teeth
shape) in staircase with different orders. The two latter shapes give
multiple forms when varying the order of the staircase evolution.
This great variety in the stimulation signals' shape as well as the
provided handiness would permit to clinicians better exploration of
the cochlea's nervous zones before chirurgical intervention. This
would give more information on hearing capacities of patients and
on the implant type (one electrode or multi-electrode). Back
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Coefficients aérodynamiques d'une éolienne Savonius
M. Kammoun Badreddine et A. Fungchui David
Cette étude présente l'évolution des coefficients
aérodynamiques (traînée, portance, résultante
d'efforts, couple) d'un rotor à axe vertical de type Savonius.
Ces évolutions sont données en régime dynamique,
en fonction d'une part de l'angle d'incidence et d'autre part de
la vitesse de l'écoulement amont et du coefficient de vitesse
périphérique.
Ce travail repose sur des résultats expérimentaux
(Chauvin et al., 1987 ; 1983), complétés par un lissage
numérique de type Spline.
La détermination de ces coefficients est essentielle pour
la compréhension du comportement mécanique de la machine.
Back
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A methodology for impervious cover estimation in urban development
using fuzzy set theory
A. Karnib
The amount of urban runoff and its impacts on stream conditions
and water quality are linked to the percent area of impervious surfaces
within a watershed. Principle of a new methodology for the estimation
of urban watershed imperviousness based on land use analysis is
presented. The proposed approach is able to take into account uncertainty
and fuzziness inherent in the available data used for impervious
surface estimation. The uncertainty and fuzziness modelling are
achieved by using if-then rules and fuzzy set analysis. Numerical
application is presented to show the applicability of the proposed
methodology. Back
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