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Numerical Simulation of Turbulent Diffusion Flames of a Biogas Enriched with Hydrogen

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Fluid Dynamics & Materials Processing 2024年第1期20卷 79-96页

作者： Naima Krarraz Amina Sabeur Khadidja Safer Ahmed Ouadha Laboratoire des Science et Ingénierie Maritimes Facultéde Génie MécaniqueUniversitédes Sciences et de la Technologie d’Oran Mohamed BoudiafOranAlgérie Laboratoire des Carburants Gazeux et de l’Environnement Facultéde Génie MécaniqueUniversitédes Sciences et de la Laboratoire des Carburants Gazeux et de l’Environneme

Any biogas produced by the anaerobic fermentation of organic materials has the advantage of being an environmentally friendly ***,the relatively low calorific value of such gases makes their effective utilization in practical applications relatively *** present study considers the addition of hydrogen as a potential solution to mitigate this *** particular,the properties of turbulent diffusion jet flames and the related pollutant emissions are investigated numerically for different operating *** related numerical simulations are conducted by solving the RANS equations in the frame of the Reynolds Stress Model in combination with the flamelet *** effects are also taken into account and the combustion kinetics are described via the GRI-Mech 3.0 reaction *** considered hydrogen fuel enrichment spans the range from 0%to 50%in terms of *** varies between 1 and 10 *** results show that both hydrogen addition and pressure increase lead to an improvement in terms of mixing quality and have a significant effect on flame temperature and *** also reduce CO_(2) emissions but increase NOx *** NO is shown to be the predominant NO formation mechanism.

关键词： Biogas hydrogen diffusion flame turbulence NO formation route pressure

Drought events influence nutrient canopy exchanges and green leaf partitioning during senescence in a deciduous forest

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Forest Ecosystems 2024年第1期11卷 110-119页

作者： J.Touche C.Calvaruso P.De Donato M.-P.Turpault INRAE BEFF-54000NancyFrance UMR 7359 GeoRessourcesFaculte des Sciences-Campus des Aiguillettes54506Vandoeuvre Les NancyFrance EcoSustain Environmental Engineering OfficeResearch and DevelopmentKanfen57330France

The increase in the frequency and intensity of drought events expected in the coming decades in Western Europe may disturb forest biogeochemical cycles and create nutrient deficiencies in *** possible origin of nutrient deficiency is the disturbance of the partitioning of the green leaf pool during the leaf senescence period between resorption,foliar leaching and senesced ***,the effects of drought events on this partitioning and the consequences for the maintenance of tree nutrition are poorly *** experiment in a beech forest in Meuse(France)was conducted to assess the effect of drought events on nutrient canopy exchanges and on the partitioning of the green leaf pool during the leaf senescence *** aim was to identify potential nutritional consequences of droughts for *** nutrient dynamics,including resorption,chemistry of green and senesced leaves,foliar absorption and leaching in mature beech stands from 2012 to 2019 allowed us to compare the nutrient exchanges for three nondry and three dry years(i.e.,with an intense drought event during the growing season).During dry years,we observed a decrease by almost a third of the potassium(K)partitioning to resorption(*** efficiency),thus reducing the K reserve in trees for the next growing *** result suggests that with the increased drought frequency and intensity expected for the coming decades,there will be a risk of potassium deficiency in trees,as already observed in a rainfall exclusion experiment on the same study *** foliar leaching and higher parititioning to the senesced leaves for K and phosphorus(P)were also *** addition,a slight increase in nitrogen(N)resorption efficiency occurred during dry years which is more likely to improve tree *** calcium(Ca)negative resorption decreased,with no apparent consequence in our study *** results show that nutrient exchanges in the canopy and the partitioning of the green leaf

关键词： Natural drought Beech forest Canopy Resorption Foliar leaching Senesced leaves Nutrition

Evaluation of the Level of Pollution by Heavy Metals of Market Garden Soils along the Chari River in Ndjamena: Case of the 9th and 7th Districts

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Agricultural sciences 2024年第8期15卷 939-961页

作者： Kotva Wana Mackaye Hassane Taisso Likius Andossa Béral Djétenbé Laboratoire Gosciences Dpartement des Sciences de la Terre Facult des Sciences Universit de NDjamena NDjamena Chad Laboratoire Gosciences Dpartement des Sciences de la Terre Facult des Sciences Universit de Mongo Mongo Chad Laboratoire Sol et Environnement (LASEN) Dpartement des Sciences de la Terre Facult des Sciences Universit de Ngaoundr Ngaoundr Cameroun

The main aim of this study was to characterize the metal content of soils used for market gardening along the Chari river: the 7th and 9th districts of NDjaména. To achieve this, two sites were selected: Gassi and Walia, and two control sites (Gassi and Walia). A total of fifty (50) soil samples were taken (24 from the Gassi site, 24 from the Walia site and 2 as control soils) and then analyzed to determine a number of physico-chemical parameters (pH, OM and electrical conductivity) and heavy metal concentrations in the various soils. The TME content (As, Cd, Cu, Cr, Ni, Pb, Hg and Zn) of the soils was determined by plasma-coupled Atomic Emission Spectrometry. In order to assess the level of contamination in Gassi and Walia soils, the geoaccumulation index (GeoIndex), contamination factor and degree of contamination were calculated. Results for physico-chemical parameters revealed that pH ranged from acidic (4.6) to moderately neutral (6.5), electrical conductivity was higher in cultivated soils (mean 292.14 μs/cm) than in control soils (mean 149.33 μs/cm), and soils were rich in organic matter. Overall, heavy metal concentrations in cultivated soils were higher than in control soils. The pollution estimate shows that soils in the area have no moderate contamination. The increase in TME concentrations in cultivated soils is thought to be due to the input of agricultural inputs to the soil. However, these levels are below the Average shale reference and Canadian guidelines for agricultural soil quality. Principal component analysis shows that metals are positively and significantly correlated with each other, and negatively and moderately significantly correlated with each other.

关键词： Contamination Agricultural Soils City of N’Djaména ETM Gassi Walia

Tissages de destins Le Xinjiang dans le tissu dela modernité chinoise

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中国与非洲（法文版） 2024年第3期16卷 18-19页

作者： LIU HUAWEN I'lnstitut de droit international de I'Academie des sciences sociales I'Academie des sciences sociales du Xinjiang

Situe au nord-ouest de la Chine,au coeur de I'Eurasie,le Xinjiang se distingue comme la plus grande region administrative provinciale de *** carrefour de ressources et d'opportunites,ce territoire riche et diversifiéjoue un role crucial dans la reforme chinoise et agit comme un pivot majeur pour I'exploitation vers I'ouest du *** occupe une position strategique dans le développement de la Ceintureéconomique de la Route de la soie,consolidant son statut de zone essentielle pour I'initiative.

关键词： des dis pour

A New Multiobjective Particle Swarm Optimization Using Local Displacement and Local Guides

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Open Journal of Optimization 2024年第2期13卷 31-49页

作者： Saïd Charriffaini Rawhoudine Abdoulhafar Halassi Bacar Laboratoire des Mathmatiques Statistiques Informatique et Applications (LMSIA) Dpartement des Mathmatiques Physique-Chimie et Informatique Facult des Sciences et Techniques Universit des Comores Moroni Comoros

This paper introduces a novel variant of particle swarm optimization that leverages local displacements through attractors for addressing multiobjective optimization problems. The method incorporates a square root distance mechanism into the external archives to enhance the diversity. We evaluate the performance of the proposed approach on a set of constrained and unconstrained multiobjective test functions, establishing a benchmark for comparison. In order to gauge its effectiveness relative to established techniques, we conduct a comprehensive comparison with well-known approaches such as SMPSO, NSGA2 and SPEA2. The numerical results demonstrate that our method not only achieves efficiency but also exhibits competitiveness when compared to evolutionary algorithms. Particularly noteworthy is its superior performance in terms of convergence and diversification, surpassing the capabilities of its predecessors.

关键词： Particle Swarm Optimization Multiobjective Optimization Attractor-Based Displacement Square Root Distance Crowding Distance

Land Use and Gully Dynamics in the Kourfa Watershed, Matankari (Southwest Niger)

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Journal of Geographic Information System 2024年第4期16卷 306-320页

作者： Bachirou Hamadou Younoussa Tahirou Hassane Yaou Bouba Hassane Abass Kadade Sabou Abdoulkader Moussa Issaka Amadou Abdourhamane Toure Zibo Garba Facult des sciences et Techniques Universit de Dosso Dosso Niger Facult des sciences et Techniques Universit Abdou Moumouni de Niamey Niamey Niger Facult des sciences et Techniques Universit Andr Salifou de Zinder Zinder Niger

The main consequences of climate change in the Sahel have been the metamorphosis of surface conditions. These metamorphoses have resulted in surface degradation, of which silting up of watersheds is the main phenomenon. The objective of this study is to assess the environmental trends of the Kourfa pond watershed. The study is based on diachronic mapping with Landsat satellite images and Google Earth images, over the period 1986 to 2021. The study reveals that vegetation (whose rate of regression doubled between 1986 and 2021) has decreased to the benefit of crop areas (whose rate of increase multiplied by 3.61 between 1986 and 2021). Bare soil and encrusted areas have also decreased, with regression rates almost double than those of 1986. In addition, the Kourfa waterholes have experienced two types of changes over 35 years: one progressive between 2011 and 2016 and the other regressive between 2001 and 2021 compared to 1986. The ravine network has been multiplied by a factor of 2.4, with density more than doubled and the connectivity of the hydrographic networks has risen from 2 to 4, with significant bank recession. This dynamic of the Kourfa pond is linked to the high drainage, the increasing complexity of the gully network and the erosion due to the retreat of the watershed banks, all of which contribute to the silting-up of the Kourfa watershed.

关键词： Kourfa Pond Dynamics Watershed Dosso Niger

Influence of the Nature of the Incoming Sludge on the Performance of a Vertical Flow Reed Beds in Dakar-Senegal

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Journal of Water Resource and Protection 2024年第6期16卷 429-449页

作者： Elhadji Mamadou Sonko Diomaye Dieng Maïmouna Lo Cheikh Diop Laboratoire dEtude Environnemental des Milieux Urbains (LEEMUR) Institut des Sciences de lEnvironnement (ISE) Facult des Sciences et Technique (FST) Universit Cheikh Anta Diop de Dakar (UCAD) Dakar-Fann Sngal

This work investigates the influence of the type sludge on drainage, plant development, purification performances and biosolids quality. Drainage properties were measured through the frequency of clogging, the percentage of leachate recovered and the dryness of accumulated sludge. Plant development was measured through the density, the height and the stem diameter. Purification performance was evaluated from the reduction rate. Biosolids quality was measured after 3 months of maturation. The results show that the clogging frequencies were 9.5%;0% and 3.7%;the volume of leachate recovered was 42.2%;20.4% and 24.7% and, the dryness was 33.4%;61.1% and 52.4% for FS-ST, FS-STT and SS respectively. Plants densities were about, with densities 197.1, 171.3 and 178.3 plants/m2 in beds fed respectively with FS-ST, FS-STT and SS. despite the high removal rates, the concentrations of pollutants in the leachates are above the Senegalese standard NS 05-061 for discharge into the environment. The biosolids are all mature with C/N and NH4+/NO3?ratios lower than 12 and 1 respectively. The biosolids are also rich in organic and mineral elements. The concentrations of Ascaris eggs are higher than the WHO recommendations. These biosolids should be stored for additional time or composted.

关键词： Biosolid Quality Dewatering Performance Planted Drying Beds Purification Performance Sludge Type

Coupling Aquaculture—Crop Productions and Using of Water Drained from Ponds Rearing Clarias gariepinus as Fertilizer for Okra Production (Abelmoschus esculentus var. Clemson spineless, L. Moench)

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Open Journal of Applied sciences 2024年第9期14卷 2628-2647页

作者： Louis Dossou Magblénou Justin Kantoussan César Bassène Dieynaba Yacine Mar Gueye Hamath Sy Laboratoire des sciences Biologiques Agronomiques et de Modlisation des Systmes Complexes (LaBAM) UFR des Sciences Agronomiques de lAquaculture et des Technologies Alimentaires (UFR S2ATA) Dpartement Aquaculture Universit Gaston Berger (UGB) Saint-Louis Senegal Laboratoire des sciences Biologiques Agronomiques et de Modlisation des Systmes Complexes (LaBAM) UFR des Sciences Agronomiques de lAquaculture et des Technologies Alimentaires (UFR S2ATA) Dpartement Productions Vgtales et Agronomie (PVA) Universit Gaston Berger (UGB) Saint-Louis Senegal

The present study concerns the revalorization of drained water from aquaculture ponds rearing Clarias gariepinus on okra crops. The rearing was carried out at the farm of Gaston Berger University in 100 m2 ponds. In each pond, the individuals of C. garipinus with an average weight of 6 ± 0.3 g were stocked at a density of 11 per m2. The water temperature and pH were measured during the experiment. The control fishing is carried out every month to monitor variations in the weight and size of reared individuals. The plant production is carried out in elementary plots measuring 3 m × 1.5 m. Each plot was fertilized with either: drained water from C. gariepinus rearing (DWC), poultry droppings (PD), cow dung (CD) and mineral fertilizer (NPK). Treatments are carried out in tripliqua with either river water (RW), RW + the recommended dose of NPK (RD-NPK), RW + RD-PD, RW + RD-CD, DWC, DWC + 25% RD-NPK, DWC + 50% RD-NPK, DWC + 75% RD-NPK, DWC + 25% RD-PD, DWC + 50% RD-PD, DWC + 75% RD-PD, DWC + 25% RD-CD, DWC + 50% RD-CD, DWC + 75% RD-CD. Growth parameters and yield of okra were determined. The average temperature in the rearing environment was 27.6 ± 1.5˚C and pH 7.9 ± 1.1. After six (06) months of rearing, C. gariepinus individuals reached an average weight of 850.12 ± 1.3 g and an average height of 52.44 ± 1.1 cm. The daily weight gain and specific growth rates over this period were 3.9 g per day and 2.8% per day, respectively. The treatment T1 (RW + DR-NPK) gave the highest mean collar diameter and mean plant height with 2.3 ± 0.9 cm and 61.6 ± 32 cm, respectively. In T4 (DWC), the mean height of plants was 38.8 ± 23.5 cm and mean collar diameter 1.4 ± 0.8 cm. The growth performance in T4 was comparable to that of RD-CD (T3), but different from RD-NPK (T1) and RD-PD (T2). The highest average number, average weight, average length and average diameter of fruits were noted in treatments T13 (RW + RD-75%CD) and T7 (DWC + 75% RD-NPK). The best yields were noted in T1 (RW +

关键词： Integrated Aquaculture Drained Water Fertilization C. gariepinus Okra

Numerical Simulation of Dam-Break Flows Using Radial Basis Functions: Application to Urban Flood Inundation

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American Journal of Computational Mathematics 2024年第3期14卷 318-332页

作者： Abdoulhafar Halassi Bacar Said Charriffaini Rawhoudine Laboratoire des Mathmatiques Statistiques Informatique et Applications (LMSIA) Dpartement des Mathmatiques Physique-Chimie et Informatique (MPCI) Facult des Sciences et Techniques Universit des Comores Moroni Comoros

Dam-break flows pose significant threats to urban areas due to their potential for causing rapid and extensive flooding. Traditional numerical methods for simulating these events struggle with complex urban landscapes. This paper presents an alternative approach using Radial Basis Functions to simulate dam-break flows and their impact on urban flood inundation. The proposed method adapts a new strategy based on Particle Swarm Optimization for variable shape parameter selection on meshfree formulation to enhance the numerical stability and convergence of the simulation. The method’s accuracy and efficiency are demonstrated through numerical experiments, including well-known partial and circular dam-break problems and an idealized city with a single building, highlighting its potential as a valuable tool for urban flood risk management.

关键词： Dam-Break Flows Numerical Simulation Shallow Water Equations Radial Basis Functions Urban Flood Inundation