École Supérieure des Ingénieurs de l'Équipement Rural

In Tunisia, the availability of water resources is an important issue in agriculture, drinking water and industry. It is important to note that agriculture is the most water consuming activity. However, the scarcity of water resources, both in quality and quantity, and its geographical distribution are among the main factors limiting the development of Tunisian agriculture. It is clear that the magnetic device influences the characteristics of limestone. On the other hand, there is variation in the physico-chemical characteristics of water which improves productivity and crop performance. The performance of irrigation by magnetized water is greater than irrigation by raw water. In this context, we examine the effects of magnetic treatment of irrigation water on surface tension and evaporation. As a result, four apparatuses with different characteristics were used. The application of a magnetic field influenced the water parameters, decreasing its surface tension by up to 24 % and increasing its volume evaporated in relation to the raw water. Statistical analysis showed that our experimental results are significant.

The method of Gardner was used to estimate the evaporation rate from bare soils under high water table conditions, at Ichkeul marshes, of northern Tunisia. For this purpose, water content, soil-water suction, and water table depth were measured at three sites. Other common approaches that provide estimates of water table evaporation such as the Averianov and Coudrain-Ribstein et al. empirical formulas and the approach used by the U.S. Geological Survey's groundwater flow model MODFLOW were also evaluated. Next, a 2D groundwater simulation model, using the Gardner equations for computing evaporation rate, was developed to quantify the aquifer budget and groundwater losses via evaporation at the total area of the marshes. The model was calibrated in a steady-state condition. The results indicated significant groundwater losses by water table evaporation. The sensitivity of the groundwater model to the Averianov and MODFLOW approaches was analyzed. The best results (piezometric head and the area distribution of the evaporation discharge) were obtained with the Averianov formula.

Pumped storage is generally viewed as the most promising technology to increase renewable energy source penetration levels in power systems and particularly in small autonomous systems. Combined battery and pump constitute a realistic and feasible option to achieve high penetrations. This paper focuses on dynamic modeling, simulation, control and energy management in an isolated integrated power generation system consisting of a 2 kW PV and 100 Ah lead acid battery storage. A supervisory controller is designed for energy management between the maximum energy captured from the PV and consumed energies of the load. Dynamic modeling and simulation are fulfilled using MATLAB Simulink™7.2.

Rainfall data are an essential input for many simulation models. In fact, these latter have a decisive role in the development and application of rational water policies. Since the accuracy of the simulation depends strongly on the available data, the task of optimizing the monitoring network is of great importance. In this paper, an application is presented aiming at the evaluation of a precipitation monitoring network by predicting monthly, seasonal, and interannual average rainfall. The method given here is based on the theory of the regionalized variables using the well-known geostatistical variance reduction method. The procedure, which involves different analysis methods of the available data, such as estimation of the interpolation uncertainty and data cross validation, is applied to a case study data set in Tunisia in order to demonstrate the potential for improvement of the observation network quality. Root mean square error values are the criteria for evaluating rainfall estimation, and network performance is discussed based on kriging variance reduction. Based on this study, it was concluded that some sites should be dropped to eliminate redundancy and some others need to be added to the existing network, essentially in the center and the south, to have a more informative network.

Abstract A new high‐resolution (5 km) gridded daily precipitation dataset for Tunisia between 1979 and 2015 is introduced. This product combines 960 rain gauges with the SAFRAN analysis to produce the precipitation gridded data. A validation approach on two different datasets reveals that the SAFRAN analysis outperforms other standard interpolation methods such as Inverse Distance, Nearest Neighbors, Ordinary Kriging or Residual Kriging with altitude. When compared to EOBS, a widely used gridded dataset over Europe, a strong negative bias in EOBS precipitation is found. However due to the aridity and the low density of rain gauges in south Tunisia, results in this region must be analyzed with care. The SAFRAN product could be useful for various purposes such as climate model evaluation, climate studies, hydrological modelling to support the planning and management of surface water resources in Tunisia.

Abstract This paper refers to the quantification and prediction of the sedimentation rate of 26 hillside-dam reservoirs in Central Tunisia. The objectives of the study are to develop a simple and practical methodology to identify controlling factors of sedimentation, and to propose a regionalization from the study sites. Principal component analysis (PCA) and complementary multi-dimensional statistical methods are used to relate highly variable area-specific sediment yield to hydro-morphometric, lithological, geomorphological and anthropogenic characteristics of catchments. It appears that catchment area is not the main controlling factor of sedimentation in the studied area. The overall slope index, drainage network characteristics and runoff parameters are also important in characterizing sediment yield. Applied to the annual sedimentation rate series, PCA resulted in retaining the first three principal axes, explaining 65% of the total variance. Statistical methods showed that the overall slope index, the total drainage length, the compacity index and the runoff parameters are as important for the sedimentation quantification. This allowed a graphical clustering of the study zone into three distinct groups having similar behaviours: (i) watersheds characterized by high sediment transport rates and high runoff coefficients, (ii) basins distinguished by relatively low values of both flow discharge and sediment transport rates, and (iii) watersheds with an intermediate sediment yield, especially characterized by relatively high relief. In a second step, a multiple regression model including the four characteristic catchment properties was developed, presenting a valuable tool to predict area-specific sediment yield from catchments in central Tunisia. This model shows reasonable efficiency with an absolute prediction error of 81%. Citation Ayadi, I., Abida, H., Djebbar, Y. & Mahjoub, M. R. (2010) Sediment yield variability in central Tunisia: a quantitative analysis of its controlling factors. Hydrol. Sci. J. 55(3), 446–458.

The Particle Swarm Optimization (PSO) is one of the most utilized algorithm in swarm intelligence to deal with different optimization tasks, such as photovoltaic maximum power point tracking (MPPT). In this paper, an improved variant of the PSO is proposed including a nonlinear decreasing inertia weight in order to enhance the search process of the particles. A comparative study among the PSO with a linear and a nonlinear weight is carried out for MPPT under different partial shading conditions. The simulation results confirm that the developed algorithm is faster and more accurate.

In this article, the dynamic responses of wind turbine systems are analytically and numerically investigated. For this purpose, analytic differential equations of motion of wind turbine components subjected to vibration (the blades, the nacelle, and the tower) are solved. This allows determining their dynamic characteristics, mode shapes, and natural frequencies. Two models of two three-dimensional (3D) micro-turbine that are created by the finite element method are set up using the new version of the academic finite element analysis software ANSYS. The first wind turbine is a standard micro three-bladed turbine and the second one is a micro six-bladed Rutland 504. Their natural frequencies and mode shapes are identified based on the modal analysis principle to check the validity of designed models. Dynamic behaviors at several operating conditions of wind turbines are established. Then, spectrum graphs of the structures along x-, y- and z-axis are analyzed.

This paper investigates the classification of a valve clearance fault in an internal combustion diesel engine using vibration time domain features extracted from signal segments measured at several points on the engine bloc. Signals containing a large number of engine cycles are used to obtain a number of observations of each feature. The set of features is thus considered a set of variables. A stepwise variable selection algorithm based on univariate and multivariate analysis of variance is then used to sort the variables according to their diagnostic ability. The algorithm is also used to construct sets of variables of increasing size used to improve fault classification. Four commonly used supervised classifiers are trained and then tested, giving roughly the same percentage of correct classification. The tested classifiers confirmed that the use of more variables selected by the stepwise variable selection algorithm increases the percentage of correct classification.

Geomorphology-based rainfall–runoff models are particularly helpful for predicting hydrology in ungauged basins. The robustness, generality and flexibility of the modelling approach make it able to deal with a wide variety of processes, events and scales. It allows a rainfall–runoff transfer function to be estimated for any basin without needing to measure discharge. The aim of this study is to transpose hydrological observations from gauged to ungauged basins to predict streamflow hydrographs. It considers pairs of nested and neighbouring basins, the first one providing information for the second ungauged one. A time-series of the donor basin's discharge is deconvoluted by inverting its geomorphology-based transfer function to assess the time-series of net rainfall. The latter is then transposed to the receiver basin, where it is convoluted with the reciever basin's transfer function to predict the hydrograph therein. The methodology was implemented with virtual and real rainfall–runoff events on a set of basins in temperate Brittany, France. Different time scales and spatial configurations were tested. Goodness-of-fit of model predictions varied by basin pair. High prediction accuracy was observed when transposing hydrographs between nested basins differing greatly in size. Several ways to improve the approach are identified by relaxing simplifying assumptions.

) fruits. The chemical composition of acorn flour showed its richness in carbohydrates (64.43%), proteins (8%), and fat (10%). The extraction yield of acorn starch was about 34.5%. Thus, the composition of extracted acorn starch and its physical and functional properties were studied. Acorn starch had high purity represented by low proportions of proteins (0.92%) and lipids (0.51%) with a pH of 5.3. The swelling power was 20.76 g/g, while the solubility was about 64.22% at 90°C which suggests that acorn starch has potential for use in food industries. The FT-IR spectra of isolated native starches have shown the main bands characterizing the starch. However, X-ray diffractograms exhibited an A- and B-type diffraction pattern. Furthermore, the effect of acorn starch incorporation at different levels (0.5%, 1%, 1.5%, and 2%) on the quality parameters of a fermented dairy product was investigated at the beginning of storage. The results demonstrated that the most suitable dose of acorn starch to be incorporated in the fermented dairy product was lower than 1%. This low concentration reduced syneresis, improved functional properties, and enhanced the viscosity of the fermented dairy product.

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This paper deals with the modeling and simulation of a permanent magnet synchronous generator (PMSG)-based marine current turbine (MCT) under faulty rectifier conditions. The modeling of the generator is established in the synchronous rotating d-q reference frame. The control of the speed, the d-axis current, and the q-axis current are achieved using proportional integral (PI) correctors. The faulty mode deals with the study of single and multiple open-switch damages appearing in the pulse width modulation (PWM) power rectifier. Simulations are carried out to highlight the proposed PMSG-based MCT performance in both cases using MATLAB/Simulink environment.

This paper addresses the stability analysis problem for a class of discrete-time switched nonlinear time-delay systems with polytopic uncertainties. These considered systems are characterized by delayed difference nonlinear equations which are given in the state form representation. Then, a transformation under the arrow form is employed. Indeed, by constructing an appropriated common Lyapunov function, and also by resorting to the Kotelyanski lemma and the M-matrix proprieties, new delay-independent stability conditions under arbitrary switching law are deduced. Compared with the existing results of switched systems, those obtained results are formulated in terms of the unknown polytopic uncertain parameters, explicit and easy to apply. Moreover, this method allows us to avoid the search for a common Lyapunov function which is a difficult matter. Finally, a numerical example is presented to illustrate the effectiveness of the proposed approach.

The degradation of water quality in Tunisia is mainly due to the overexploitation of groundwater, pollution and especially mismanagement in the different areas. Magnetic treatment methods can be used in the field of agriculture to alleviate salinity problems of irrigation. It is clear that the magnetic device influences the characteristics of limestone. On the other hand, there is variation in the physico-chemical characteristics of water which improves productivity and crop performance. The performance of irrigation by magnetized water is greater than irrigation by raw water. In this context, we examine the existence of the beneficial effects of the magnetic treatment of irrigation water on its quality and on the yield of the melon culture. As a result, a permanent magnet apparatus (Magneteau) installed on the irrigation line was used. The application of a magnetic field showed an influence on the water parameters, decreasing its electrical conductivity (EC) by 5.2% and increasing its pH by 5.6%. In addition, the effect of this magnetic device showed an increase in melon cultivation of 39%. Statistical analysis showed that our experimental results are very significant.

In this paper, an interconnected grid hybrid renewable energy system, HRES, (wind/PV) is studied. The wind energy conversion system, WECS, is constructed aroud a wind turbine coupled to a double fed induction generator, DFIG. The stator of DFIG is directly connected to the grid and the rotor is connected to the grid through back-to-back power converters. To control the wind system, we have applied the adaptive backstepping control strategy for both converters. The PV energy system is composed by PV cell energy and the DC-DC boost converter. To control the DC-DC boost converter, we have applied tow cascade PI control loop. The first one is used to regulate the output current or the second one is used to control the output voltage. We have considered in both control structure the MPPT algorithm. To study the comportment of the HRES against the environment changes, we have considered some simulations scenarios for the wind speed, the irradiance and the temperature. We have studied the dynamic performances of the proposed control strategy.

River networks are structural and functional backbones of river basins. They frequently display general scaling properties through their hierarchical topology. Their mathematical description further feeds geomorphology-based hydrological analyses and modelling approaches that require little calibration. Nevertheless, particular river basins display widely diverse geomorphometric structures in relation to relief, geology, climate and anthropogenic constraints, as well as various hydrological structure-function relationships. A robust, flexible and systematic approach is thus needed to allow for joint spatial, topological and scaling analyses, in order to explore the hydro-geomorphological diversity. The HydroStruct software application is dedicated to such analyses, and to easily link geomorphometric observations with hydrological analysis and modelling approaches, such as geomorphology-based transfer functions, accounting for rainfall variability within rainfall-runoff modelling, and impact assessment of landscape and hydraulic changes. HydroStruct was developed within the generic OdefiX framework, which provides Java software components to allow co-development and interfacing of object-oriented models.

The study of nitrogen organic matter is of great importance for both economic and environmental reasons. Thus, seven soils developed under different pedogenetic and bioclimatic conditions in Tunisia were selected to investigate the distribution of organic nitrogen (ON). Our results showed an enrichment in ON of superficial horizons to the detriment of the deep horizons. Nevertheless, this decrease in ON contents with depth occurred following different patterns according to soil type. Moreover, the investigation of ON distribution in clay- and silt-sized particles (below 50 µm) indicated a considerable contribution of the fine fraction (65–98% of the soil total ON) to the ON immobilization in soils, especially in the deep horizons, while the coarse fraction (>50 µm) seems to play a less important role. The isolation of humic substances (Humic Acids, Fulvic Acids and Humin (H)) from the fine fraction and the analysis of the ON in each of these organic fractions permitted to conclude the majority of soil ON is incorporated within the H, thus suggesting a low bioavailability of nitrogen in the studied soils.

Abstract This article analyses the ethno-politics of water in Argentina at the high point of European immigration, the first three decades of the twentieth century. Focusing on the drying of the Guanacache wetlands, located in the wine-producing region of Cuyo, we show how national and provincial ideologies based on ‘whitening’ and ‘civilisation’ shaped policies that favoured European immigrants at the expense of autochthonous populations in the geographic and social struggle for irrigation water. A large-scale redistribution of water resources drove the indigenisation of indigenous and criollo populations and the desertification of their land.

To evaluate the effects of tillage systems on soil bulk density, yield and quality of potato crop (Solanum tuberosum L.), three different tillage techniques were studied: reduced tillage using discs harrow (RT), medium tillage depth using discs plow (MT) and conventional deep tillage using moldboard plowing (CT) with three working depths of 10, 20 and 30 cm respectively. Tillage was followed by a first resumption after 10 days and a second one after 20 days. Soil structure was characterized by its bulk density and potato quality by tubers size and yield. Samples were collected from tilled plots at different dates spaced of 20 days. The obtained data were tabulated and analysed using IBM SPSS 17.0 version and Tukey test. Compared to MT and RT, CT decreased bulk density to 1.16 g cm-3 against 1.23 and 1.4 g cm-3 60 days after tillage respectively for the two previous tillage systems and increased tubers size and consequently the potato yield to an average of 11 Mg ha-1 compared to 9 and 7 Mg ha-1 respectively for MT and RT. The statistical analyses of the data showed significant effects of the treatments and the measurement date on soil bulk density.