In the context of transitioning toward more sustainable construction materials,this study explores the impact of incorporating millet husks as an alternative to sand on the physical,mechanical,and thermal performance ...In the context of transitioning toward more sustainable construction materials,this study explores the impact of incorporating millet husks as an alternative to sand on the physical,mechanical,and thermal performance of lightweight concrete.Through a mixture design approach,five formulations were selected and thoroughly characterized.The analysis of iso-response curves enabled an in-depth assessment of the cross-effects between formulation parameters and their interactions on the final properties of the material.The results show that integrating millet husks leads to a significant reduction in density,reaching up to 21%,while maintaining notable mechanical performance.A balanced formulation of sand and fibers achieved a maximum compressive strength of 12.11 MPa,demonstrating that,under specific conditions,plant fibers actively contribute to the structural integrity of the composite.In tensile strength,the positive influence of fibers is even more pronounced,with a maximum resistance of 8.62 MPa,highlighting their role in enhancing material cohesion.From a thermal perspective,millet husks reduce both thermal conductivity and effusivity,thereby limiting heat transfer and accumulation within the composite.Iso-response curve analysis reveals that these effects are directly linked to the proportions of the constituents and that achieving an optimal balance between sand,fibers,and cement is key to maximizing performance.These findings demonstrate that the adopted approach allows moving beyond conventional substitution methods by identifying optimal configurations for the design of lightweight bio-based concretes that are both strong and insulating,thereby confirming the potential of millet husks in developing lightweight concretes suitable for sustainable construction applications.展开更多
Irrigated agriculture in Cameroon is practiced on a large scale by large private firms and parastatals, and on a small scale by individual producers in different production areas of the country. Although small-scale i...Irrigated agriculture in Cameroon is practiced on a large scale by large private firms and parastatals, and on a small scale by individual producers in different production areas of the country. Although small-scale irrigation can supply local and sub-regional markets with food in the off-season, it has received little research and its challenges are therefore rarely addressed. In order to contribute to the knowledge of these small-scale irrigation systems, with a view to improving their structure and the management of irrigation water and energy, an assessment of small-scale irrigation in the southern slopes of the Bamboutos Mountains has been done. After direct observations, field measurements, surveys of 100 irrigators with questionnaires and interviews with administrative managers, analyses were carried out using Xlstat software. It was found out that about 226 small-scale irrigation systems designed and managed by producers have been installed on this slope between the end of December 2022 and mid-March 2023. Intended for market garden crops, 84.96% of these irrigation systems use sprinklers and 15.04% surface irrigation (furrow irrigation). Surface or underground water is mobilized using gravity (50%), fossil fuels (34.51%), electricity (14.6%) or solar energy (0.9%). Sprinkler irrigation is mainly carried out using locally manufactured hydraulic turnstiles. There is a lack of formal associations of irrigators in an environment marked by conflicts between water users, when there is not allocation for water withdrawal. Apart from the high cost of pumping energy ($1.32 per liter of fuel), the main constraint identified, which has become more acute over the years, is the lack of irrigation water during the water shortage period (from mid-January to mid-March). These constraints have led to a transition from surface irrigation to sprinkler irrigation, and the adoption of new energy supply and water mobilization technologies. The construction of collective surface and groundwater catchment structures with solar-powered pumping systems, the setting up of formal irrigators’ associations and an irrigation support service, could improve the availability of water throughout the irrigation season, thereby helping to improve the income generated by irrigated market-garden farming on the southern slopes of the Bamboutos Mountains.展开更多
Expansive soils, prone to being influenced by the environmental conditions, undergo expansion when water is introduced and shrinkage upon drying. This persistent volumetric fluctuation can induce differential movement...Expansive soils, prone to being influenced by the environmental conditions, undergo expansion when water is introduced and shrinkage upon drying. This persistent volumetric fluctuation can induce differential movements and result in cracking of structures erected upon them. The present research focuses on characterizing the behavior of pavements erected on expansive clays subjected to swelling and shrinkage cycles. Direct shear tests and oedometer tests were conducted in the laboratory on samples of expansive soils undergoing swelling-shrinkage cycles. The experimental data reveal a significant decrease in shear strength, evidenced by a reduction in shear parameters (internal friction angle, cohesion) and a decrease in the modulus of elasticity as the number of cycles increases. A numerical model based on the finite element method was developed to simulate the behavior of a pavement on an expansive clay substrate. The model results indicate an increase in total displacements with the increase in the number of shrinkage-swelling cycles, demonstrating a progressive degradation of the soil’s mechanical behavior. This study contributes to a better understanding of the complex phenomena governing the behavior of expansive soils and serves as a foundation for developing effective management and mitigation strategies for road infrastructures.展开更多
Sorghum breeding significantly relies on the understanding of genetic diversity dynamics. Despite its importance, research on the geographical distribution of essential agro-morphological and phenological traits for a...Sorghum breeding significantly relies on the understanding of genetic diversity dynamics. Despite its importance, research on the geographical distribution of essential agro-morphological and phenological traits for achieving targeted breeding outcomes has been limited. This paper presents an analysis of five key traits—stem flavor, days to 50% maturity, plant height, grain color, and grain size—across 483 germplasm samples from 71 villages in Niger, based on data collected during a 2003 survey. The primary aim is to map the geographical distribution of these traits. The findings, illustrated on a map of Niger, provide insights into the regional distribution of these characteristics, aiding breeders and agronomists in understanding trait combinations for developing new sorghum varieties.展开更多
The distribution networks sometimes suffer from excessive losses and voltage violations in densely populated areas. The aim of the present study is to improve the performance of a distribution network by successively ...The distribution networks sometimes suffer from excessive losses and voltage violations in densely populated areas. The aim of the present study is to improve the performance of a distribution network by successively applying mono-capacitor positioning, multiple positioning and reconfiguration processes using GA-based algorithms implemented in a Matlab environment. From the diagnostic study of this network, it was observed that a minimum voltage of 0.90 pu induces a voltage deviation of 5.26%, followed by active and reactive losses of 425.08 kW and 435.09 kVAR, respectively. Single placement with the NSGAII resulted in the placement of a 3000 kVAR capacitor at node 128, which proved to be the invariably neuralgic point. Multiple placements resulted in a 21.55% reduction in losses and a 0.74% regression in voltage profile performance. After topology optimization, the loss profile improved by 65.08% and the voltage profile improved by 1.05%. Genetic algorithms are efficient and effective tools for improving the performance of distribution networks, whose degradation is often dynamic due to the natural variability of loads.展开更多
Room-temperature sodium-sulfur batteries are promising grid-scale energy storage systems owing to their high energy density and low cost.However,their application is limited by the dissolution of long-chain sodium pol...Room-temperature sodium-sulfur batteries are promising grid-scale energy storage systems owing to their high energy density and low cost.However,their application is limited by the dissolution of long-chain sodium polysulfides and slow redox kinetics.To address these issues,a cobalt single-atom catalyst with N/O dual coordination was derived from a metal-organic framework precursor(denoted as Co-N_(2)O_(2)/MOFc)for sulfur storage.Theoretical analysis demonstrates that,compared with the Co-N4 structure,the introduction of oxygen atoms can further tune the d-electron density of Co atoms via the coordinative effect,which enhances d-p hybridization after Na_(2)Sx adsorption on Co-N_(2)O_(2)/MOFc.This leads to higher adsorption energy for Na_(2)Sx,lower Gibbs free energy for the rate-limiting process and a decreased Na_(2)S decomposition energy barrier,thereby promoting the polysulfide conversion reaction kinetics.When used as a sulfur host,the Co-N_(2)O_(2)/MOFc/S cathode exhibits excellent performance with a capacity of 590 mAh·g^(-2)(983 mAh·g^(-2)normalized by the sulfur mass)after 100 cycles at 0.1 A·g^(-2)and an excellent rate capability of 350 mAh·g^(-2)at 10 A·g^(-2).展开更多
The construction industry continues to rely on conventional materials like cement,which often can come with a high cost and significant environmental impact,particularly in terms of greenhouse gas emissions.To tackle ...The construction industry continues to rely on conventional materials like cement,which often can come with a high cost and significant environmental impact,particularly in terms of greenhouse gas emissions.To tackle the challenges of sustainable development,there is growing interest in using local available materials with low environmental impact.This study primarily focuses on synthesizing and characterizing a geopolymer binder made from local materials found in Benin to stabilize CEB(compressed earth brick).The synthesis involves combining amorphous aluminosilicate powder with a highly concentrated alkaline solution.Local calcined kaolinite clay(metakaolin)and corn cob ash obtained after calcination at 600°C were used with a 12 M sodium hydroxide(NaOH)solution.Different mixtures of geopolymer were formulated substituting metakaolin by corn cob ash at rates of 0%,5%,10%,and 15%of the dry weight of the mixture.Thereafter physical and mechanical characterization tests were conducted on each formulation.Results showed that geopolymer binders containing 85%metakaolin and 15%corn cob ash exhibited the best physical and mechanical performance(e.g.12.08 MPa for compression strength).Subsequently,this geopolymer formulation was used to stabilize CEB.Characterization revealed that CEBs stabilized with 10%geopolymer exhibit good mechanical properties(6.93 MPa),comparable to those of CEBs stabilized with 10%cement(7.40 MPa),justifying their use as load-bearing walls in construction.展开更多
Under the current context of climate change, supplementary irrigation may be needed for crop production resilience. We determined the effects of supplementary irrigation on sorghum grain yield in the dry Savannah regi...Under the current context of climate change, supplementary irrigation may be needed for crop production resilience. We determined the effects of supplementary irrigation on sorghum grain yield in the dry Savannah region of Togo. A two-year trial was conducted in a controlled environment at AREJ, an agro-ecological center in Cinkassé. The plant material was sorghum variety Sorvato 28. The experimental design was a Completely Randomized Block with three replications and three treatments as follows: T0 control plot (rainfed conditions);T1 (supplementary irrigation from flowering to grain filling stage) and T2 (supplementary irrigation from planting to grain filling stage). Two irrigation techniques (furrow and Californian system) were used under each watering treatment. The results showed that irrigation technique significantly affected panicle length with no effect on 1000 grains mass. Panicle length and grain yields varied from 15.59 to 25.71 cm and 0.0 to 2.06 t∙h−1, respectively, with the highest values (25.66 cm and 2.06 t∙h−1, respectively) under the T2 treatment with the California system-based supplementary irrigation. The comparison of results obtained on treatment T0 and T2, shows that supplementary irrigation increased the yields by at least 68.62%. Supplementary irrigation during sowing and growing season (T2) improved sorghum yields in the dry savannahs of Togo, with a better performance of the California irrigation system.展开更多
This study tackles current environmental challenges by developing innovative and eco-friendly particle boards utilizing sorghum husk, combined with recycled expanded polystyrene (EPS). This dual eco-responsible approa...This study tackles current environmental challenges by developing innovative and eco-friendly particle boards utilizing sorghum husk, combined with recycled expanded polystyrene (EPS). This dual eco-responsible approach valorizes sorghum husk, often deemed agricultural waste, and repurposes EPS, a plastic waste, thus contributing to CO2 emission reduction and effective waste management. The manufacturing process involves dissolving recycled polystyrene within a solvent to create a binder, which is then mixed with sorghum husk and cold-pressed into composite boards. The study explores the impact of two particle sizes (fine and coarse) and two different concentrations of the recycled EPS binder. Results demonstrate significant variations in the boards’ mechanical properties, displaying a range of Modulus of Rupture (MOR) from 0.84 MPa to 3.85 MPa, and Modulus of Elasticity (MOE) spanning from 658.13 MPa to 1313.25 MPa, influenced by the binder concentration and particle size. These characteristics suggest that the boards can be effectively used in various construction applications, including interior decoration, false ceilings, and potentially for furniture and door manufacturing when combined with appropriate coatings. This study not only exemplifies the valorization of plastic and agricultural wastes but also offers a practical, localized solution to global climate change challenges by promoting sustainable construction materials.展开更多
Managing agricultural waste and expanded polystyrene (EPS) poses significant environmental and economic challenges. This study aims to create composites from millet husks, rice husks, and recycled EPS, using a manufac...Managing agricultural waste and expanded polystyrene (EPS) poses significant environmental and economic challenges. This study aims to create composites from millet husks, rice husks, and recycled EPS, using a manufacturing method that involves dissolving the polystyrene in a solvent followed by cold pressing. Various particle sizes and two binder dosages were investigated to assess their influence on the physico-mechanical properties of the composites. The mechanical properties obtained range from 2.54 to 4.47 MPa for the Modulus of Rupture (MOR) and from 686 to 1400 MPa for the Modulus of Elasticity in Bending (MOE). The results indicate that these composites have potential for applications in the construction sector, particularly for wood structures and interior decoration. Moreover, surface treatments could enhance their durability and mechanical properties. This research contributes to the valorization of agricultural and plastic waste as eco-friendly and economical construction materials.展开更多
This study explores the development of WPCs(wood-plastic composites)using waste LDPE(low-density polyethylene)and ebony wood sawdust to propose a sustainable solution to waste accumulation.The effect of sawdust partic...This study explores the development of WPCs(wood-plastic composites)using waste LDPE(low-density polyethylene)and ebony wood sawdust to propose a sustainable solution to waste accumulation.The effect of sawdust particle size and the addition of talc as a coupling agent on the mechanical properties of the composites was examined in detail.The results show that increasing the particle size of the sawdust enhances the MOE(modulus of elasticity)and MOR(modulus of rupture)of the composites.The flexural MOE increases by 195%from the PM(plastic matrix)to composites with the coarsest sawdust,the compressive MOE by 72%,and the tensile MOE by 205%.Similarly,the flexural MOR increases by 28%,the tensile MOR by 42%,but the compressive MOR decreases slightly by 7%.The introduction of talc consistently increased the MOE,with an average improvement of 14%in flexion and 10%in tension for the various composite formulations,although it led to a decrease in compression.The MOR was also enhanced by the addition of talc,with an average increase of 16%across all tested loadings.These improvements suggest that talc can effectively serve as a coupling agent,optimizing the mechanical properties of WPCs for better use of recycled materials.展开更多
In this present study, we analyzed the effects of Prandtl and Jacob numbers and dimensionless thermal conductivity on the velocity profiles in media (porous and liquid). The transfers in the porous medium and the liqu...In this present study, we analyzed the effects of Prandtl and Jacob numbers and dimensionless thermal conductivity on the velocity profiles in media (porous and liquid). The transfers in the porous medium and the liquid film are described respectively by the improved Wooding model and the classical boundary layer equations. The mesh of the digital domain is considered uniform in the transverse and longitudinal directions. The advection and diffusion terms are discretized with a back-centered and centered scheme respectively. The coupled systems of algebraic equations thus obtained are solved numerically using an iterative line-by-line relaxation method of the Gauss-Seidel type. The results show that the parameters relating to the thermal problem (the dimensionless thermal conductivity, the Prandtl (Pr) and Jacob (Ja) numbers) have no influence on the dimensionless speed, although the thermal and hydrodynamic problems are coupled. Via the heat balance equation. The results obtained show that the parameters relating to the thermal problem have no influence on the dimensionless speed, although the thermal and hydrodynamic problems are coupled via the heat balance equation. So, at first approximation with the chosen constants, we can solve the hydrodynamic problem independently of the thermal problem.展开更多
In the current context of environmental challenges, this study focuses on developing innovative and eco-friendly composites using rice husk and recycled expanded polystyrene. This dual-responsibility approach valorize...In the current context of environmental challenges, this study focuses on developing innovative and eco-friendly composites using rice husk and recycled expanded polystyrene. This dual-responsibility approach valorizes a by-product like rice husk, often considered waste, and reuses polystyrene, a plastic waste, thereby contributing to CO2 emission reduction and effective waste management. The manufacturing process involves dissolving recycled polystyrene into a solvent to create a binder, which is then mixed with rice husk and cold-compacted into composite materials. The study examines the impact of two particle sizes (fine and coarse) and different proportions of recycled polystyrene binder. The results show significant variations in the mechanical characteristics of the composites, with Modulus of Rupture (MOR) values varying from 2.41 to 3.47 MPa, Modulus of Elasticity (MOE) ranging from 223.41 to 1497.2 MPa, and Stiffness Coefficient (K) from 5.04 to 33.96 N/mm. These characteristics demonstrate that these composites are appropriate for various construction applications, including interior decoration, panel claddings, and potentially for furniture and door manufacturing when combined with appropriate coatings. This study not only highlights the recycling of agricultural and plastic waste but also provides a localized approach to addressing global climate change challenges through the adoption of sustainable building materials.展开更多
The building sector significantly influences the environment, notably through resource consumption and waste production. Evaluating locally available resources and adopting sustainable development practices are essent...The building sector significantly influences the environment, notably through resource consumption and waste production. Evaluating locally available resources and adopting sustainable development practices are essential to mitigate this impact. This study proposes the fabrication of a wood-polymer composite by recycling polystyrene and wood sawdust. Polystyrene was dissolved in a solvent to obtain a polymer matrix, which was then reinforced with recycled wood sawdust. The mixture was cold-pressed to form composite panels. Physical properties such as density and absorption, as well as mechanical properties like the modulus of elasticity and flexural strength, were examined. Results show that the physical and mechanical properties of the composites vary with the particle size distribution of the wood particles. The modulus of elasticity and flexural strength increase with particle size. The maximum values obtained for the modulus of elasticity and flexural strength are 842 MPa and 3.16 MPa, respectively. These physical and mechanical characteristics indicate that the developed composite material can be used to manufacture elements such as furniture, false ceilings, and lightweight partitions, thereby contributing to more sustainable construction practices.展开更多
Acetic acid and furfural are known as prevalent inhibitors deriving from pretreatment during lignocellulosic ethanol production.They negatively impact cell growth,glucose uptake and ethanol biosynthesis of Saccharomyc...Acetic acid and furfural are known as prevalent inhibitors deriving from pretreatment during lignocellulosic ethanol production.They negatively impact cell growth,glucose uptake and ethanol biosynthesis of Saccharomyces cerevisiae strains.Development of industrial S.cerevisiae strains with high tolerance towards these inhibitors is thus critical for efficient lignocellulosic ethanol production.In this study,the acetic acid or furfural tolerance of different S.cerevisiae strains could be significantly enhanced after adaptive evolution via serial cultivation for 40 generations under stress conditions.The acetic acid-based adaptive strain SPSC01-TA9 produced 30.5 g·L^(-1)ethanol with a yield of 0.46 g·g^(-1)in the presence of 9 g·L^(-1)acetic acid,while the acetic acid/furfural-based adaptive strain SPSC01-TAF94 produced more ethanol of 36.2 g·L^(-1)with increased yield up to 0.49 g·g^(-1)in the presence of both 9 g·L^(-1)acetic acid and 4 g·L^(-1)furfural.Significant improvements were also observed during non-detoxified corn stover hydrolysate culture by SPSC01-TAF94,which achieved ethanol production and yield of 29.1 g·L^(-1)and 0.49 g·g^(-1),respectively,the growth and fermentation efficiency of acetic acid/furfural-based adaptive strain in hydrolysate was 95%higher than those of wildtype strains,indicating the acetic acid-and furfural-based adaptive evolution strategy could be an effective approach for improving lignocellulosic ethanol production.The adapted strains developed in this study with enhanced tolerance against acetic acid and furfural could be potentially contribute to economically feasible and sustainable lignocellulosic biorefinery.展开更多
In the contemporary world, there are three interconnected global environmental crises (climate change, biodiversity loss, and pollution). The common thread is the unsustainable pattern of production and consumption, w...In the contemporary world, there are three interconnected global environmental crises (climate change, biodiversity loss, and pollution). The common thread is the unsustainable pattern of production and consumption, which leads to international and local socio-environmental injustices. Seeking environmental justice in Brazil, the success of the rubber tapper social movement stands out, culminating in the Chico Mendes Extractive Reserve (RESEX) implementation in the Brazilian Amazon. However, the residents have struggled to generate income to help their families’ social reproduction. Conventional payment instruments for environmental services have failed to remunerate the socio-environmental attributes of sustainable products adequately. This paper aims to carry out a socio-environmental economic-ecological valuation of the main extractive products of the RESEX in 2021/2022. To this end, a methodology calculates the cost of social reproduction of rural family production, being a non-market price index reference for monetary valuation. The results indicate the acceptability of the socio-environmental valuation of native rubber and Brazil nuts, as they can guarantee environmental conservation, improve the families’ well-being with adequate income for their social reproduction, as well as value attributes outside the market, which helps in the fight against further expropriation or enclosure of rural families in the Amazon.展开更多
The use of groundwater for drinking water supply to the population is increasingly practiced in the rice cultivation area of Maga. However, there is a lack of knowledge about the hydrochemical characteristics of this ...The use of groundwater for drinking water supply to the population is increasingly practiced in the rice cultivation area of Maga. However, there is a lack of knowledge about the hydrochemical characteristics of this water due to a lack of quality control. This study aims to contribute to the understanding of mineralization processes in order to establish the hydrochemical profile of the water in the area. The methodological approach consisted of collecting fifteen water samples from wells and boreholes during six campaigns for physicochemical analysis, and studying them through methods of interpreting hydrochemical data. The analysis results show that these waters are moderately mineralized. The water facies are mainly of the bicarbonate sodium and potassium type, as well as the bicarbonate calcium and magnesium type. Calculation of saturation indices demonstrates that evaporite minerals show lower degrees of saturation than carbonate minerals, with gypsum, anhydrite, and halite being in a highly undersaturated state. The mineralization of groundwater originates from the dissolution of surrounding rocks on the one hand, and anthropogenic activities involving exchanges between alkalis (Na+ and K+) in the aquifer and alkaline earth (Ca2+ and Mg2+), resulting in the fixation of alkaline earth and the dissolution of alkalis.展开更多
This study evaluated the reduction effect of non-point source pollution by applying best management practices （BMPs） to a 1.21 km^2 small agricultural watershed using a SWAT （Soil and Water Assessment Tool） model....This study evaluated the reduction effect of non-point source pollution by applying best management practices （BMPs） to a 1.21 km^2 small agricultural watershed using a SWAT （Soil and Water Assessment Tool） model. Two meter QuickBird land use data were prepared for the watershed. The SWAT was calibrated and validated using dally streamflow and monthly water quality （total phosphorus （TP）, total nitrogen （TN）, and suspended solids （SS）） records from 1999 to 2000 and from 2001 to 2002. The average Nash and Sutcliffe model efficiency was 0.63 for the streamflow and the coefficients of determination were 0.88, 0.72, and 0.68 for SS, TN, and TP, respectively. Four BMP scenarios viz. the application of vegetation filter strip and riparian buffer system, the regulation of Universal Soil Loss Equation P factor, and the fertilizing control amount for crops were applied and analyzed.展开更多
The purpose of this work is to study the effect of a type of water-saving irrigation （WSI） on nutrient runoff of paddy field. The volume of surface drainage was maintained low by WSI. In particular, WSI effectively ...The purpose of this work is to study the effect of a type of water-saving irrigation （WSI） on nutrient runoff of paddy field. The volume of surface drainage was maintained low by WSI. In particular, WSI effectively reduced surface drainage in rain events. Model simulation indicated that net runoff load of total nitrogen （TN） from the paddy field was increased by WSI. Meanwhile, net runoff loads of total phosphorus （TP） and total organic carbon （TOC） from the paddy field was decreased by WSI. Because ponding waters of the study fields were enriched with TP and TOC, WSI reduced runoff of these nutrients by controlling the volume of surface drainage. WSI could be considered an efficient method for reducing runoff loads and could conserve water quality in an agricultural watershed.展开更多
A model in which a river model was layered on a distributed model （double-layered model） was developed to analyse the transport of water and pollutants （nitrogen, phosphorus, and BOD as organic matter） in watershe...A model in which a river model was layered on a distributed model （double-layered model） was developed to analyse the transport of water and pollutants （nitrogen, phosphorus, and BOD as organic matter） in watersheds and rivers. The model was applied to the watershed of Abragafuchi Lake, Japan, where serious water pollution has occurred over three decades, and the applicability of the model was demonstrated. Scenarios of recycling of sewage treated-water into agriculture to reduce pollutant load discharged into the lake were analysed. The results showed that irrigating paddy fields with the sewage-treated water could contribute to conserving water and reducing pollutant load, with reduction rate in BOD, nitrogen, and phosphorus ranging from 6%-36%, 16%-46%, and 18%-51%, respectively. Particularly, the results indicated that, irrigating paddy fields with the treated water during non-cropping periods and the accompanying reduction in withdrawn water from the river were more effective in reducing pollutant loads discharged into the lake. Further study is required on the effect of recycled water on crop cultivation and soil conditions for safe implementation.展开更多
文摘In the context of transitioning toward more sustainable construction materials,this study explores the impact of incorporating millet husks as an alternative to sand on the physical,mechanical,and thermal performance of lightweight concrete.Through a mixture design approach,five formulations were selected and thoroughly characterized.The analysis of iso-response curves enabled an in-depth assessment of the cross-effects between formulation parameters and their interactions on the final properties of the material.The results show that integrating millet husks leads to a significant reduction in density,reaching up to 21%,while maintaining notable mechanical performance.A balanced formulation of sand and fibers achieved a maximum compressive strength of 12.11 MPa,demonstrating that,under specific conditions,plant fibers actively contribute to the structural integrity of the composite.In tensile strength,the positive influence of fibers is even more pronounced,with a maximum resistance of 8.62 MPa,highlighting their role in enhancing material cohesion.From a thermal perspective,millet husks reduce both thermal conductivity and effusivity,thereby limiting heat transfer and accumulation within the composite.Iso-response curve analysis reveals that these effects are directly linked to the proportions of the constituents and that achieving an optimal balance between sand,fibers,and cement is key to maximizing performance.These findings demonstrate that the adopted approach allows moving beyond conventional substitution methods by identifying optimal configurations for the design of lightweight bio-based concretes that are both strong and insulating,thereby confirming the potential of millet husks in developing lightweight concretes suitable for sustainable construction applications.
文摘Irrigated agriculture in Cameroon is practiced on a large scale by large private firms and parastatals, and on a small scale by individual producers in different production areas of the country. Although small-scale irrigation can supply local and sub-regional markets with food in the off-season, it has received little research and its challenges are therefore rarely addressed. In order to contribute to the knowledge of these small-scale irrigation systems, with a view to improving their structure and the management of irrigation water and energy, an assessment of small-scale irrigation in the southern slopes of the Bamboutos Mountains has been done. After direct observations, field measurements, surveys of 100 irrigators with questionnaires and interviews with administrative managers, analyses were carried out using Xlstat software. It was found out that about 226 small-scale irrigation systems designed and managed by producers have been installed on this slope between the end of December 2022 and mid-March 2023. Intended for market garden crops, 84.96% of these irrigation systems use sprinklers and 15.04% surface irrigation (furrow irrigation). Surface or underground water is mobilized using gravity (50%), fossil fuels (34.51%), electricity (14.6%) or solar energy (0.9%). Sprinkler irrigation is mainly carried out using locally manufactured hydraulic turnstiles. There is a lack of formal associations of irrigators in an environment marked by conflicts between water users, when there is not allocation for water withdrawal. Apart from the high cost of pumping energy ($1.32 per liter of fuel), the main constraint identified, which has become more acute over the years, is the lack of irrigation water during the water shortage period (from mid-January to mid-March). These constraints have led to a transition from surface irrigation to sprinkler irrigation, and the adoption of new energy supply and water mobilization technologies. The construction of collective surface and groundwater catchment structures with solar-powered pumping systems, the setting up of formal irrigators’ associations and an irrigation support service, could improve the availability of water throughout the irrigation season, thereby helping to improve the income generated by irrigated market-garden farming on the southern slopes of the Bamboutos Mountains.
文摘Expansive soils, prone to being influenced by the environmental conditions, undergo expansion when water is introduced and shrinkage upon drying. This persistent volumetric fluctuation can induce differential movements and result in cracking of structures erected upon them. The present research focuses on characterizing the behavior of pavements erected on expansive clays subjected to swelling and shrinkage cycles. Direct shear tests and oedometer tests were conducted in the laboratory on samples of expansive soils undergoing swelling-shrinkage cycles. The experimental data reveal a significant decrease in shear strength, evidenced by a reduction in shear parameters (internal friction angle, cohesion) and a decrease in the modulus of elasticity as the number of cycles increases. A numerical model based on the finite element method was developed to simulate the behavior of a pavement on an expansive clay substrate. The model results indicate an increase in total displacements with the increase in the number of shrinkage-swelling cycles, demonstrating a progressive degradation of the soil’s mechanical behavior. This study contributes to a better understanding of the complex phenomena governing the behavior of expansive soils and serves as a foundation for developing effective management and mitigation strategies for road infrastructures.
文摘Sorghum breeding significantly relies on the understanding of genetic diversity dynamics. Despite its importance, research on the geographical distribution of essential agro-morphological and phenological traits for achieving targeted breeding outcomes has been limited. This paper presents an analysis of five key traits—stem flavor, days to 50% maturity, plant height, grain color, and grain size—across 483 germplasm samples from 71 villages in Niger, based on data collected during a 2003 survey. The primary aim is to map the geographical distribution of these traits. The findings, illustrated on a map of Niger, provide insights into the regional distribution of these characteristics, aiding breeders and agronomists in understanding trait combinations for developing new sorghum varieties.
文摘The distribution networks sometimes suffer from excessive losses and voltage violations in densely populated areas. The aim of the present study is to improve the performance of a distribution network by successively applying mono-capacitor positioning, multiple positioning and reconfiguration processes using GA-based algorithms implemented in a Matlab environment. From the diagnostic study of this network, it was observed that a minimum voltage of 0.90 pu induces a voltage deviation of 5.26%, followed by active and reactive losses of 425.08 kW and 435.09 kVAR, respectively. Single placement with the NSGAII resulted in the placement of a 3000 kVAR capacitor at node 128, which proved to be the invariably neuralgic point. Multiple placements resulted in a 21.55% reduction in losses and a 0.74% regression in voltage profile performance. After topology optimization, the loss profile improved by 65.08% and the voltage profile improved by 1.05%. Genetic algorithms are efficient and effective tools for improving the performance of distribution networks, whose degradation is often dynamic due to the natural variability of loads.
基金supported by the National Natural Science Foundation of China(Nos.22369026 and 22362031)the Basic Research Project General Program of Yunnan Province(No.202401CF070025)the Sichuan Science and Technology Program(No.24NSFSC3150).
文摘Room-temperature sodium-sulfur batteries are promising grid-scale energy storage systems owing to their high energy density and low cost.However,their application is limited by the dissolution of long-chain sodium polysulfides and slow redox kinetics.To address these issues,a cobalt single-atom catalyst with N/O dual coordination was derived from a metal-organic framework precursor(denoted as Co-N_(2)O_(2)/MOFc)for sulfur storage.Theoretical analysis demonstrates that,compared with the Co-N4 structure,the introduction of oxygen atoms can further tune the d-electron density of Co atoms via the coordinative effect,which enhances d-p hybridization after Na_(2)Sx adsorption on Co-N_(2)O_(2)/MOFc.This leads to higher adsorption energy for Na_(2)Sx,lower Gibbs free energy for the rate-limiting process and a decreased Na_(2)S decomposition energy barrier,thereby promoting the polysulfide conversion reaction kinetics.When used as a sulfur host,the Co-N_(2)O_(2)/MOFc/S cathode exhibits excellent performance with a capacity of 590 mAh·g^(-2)(983 mAh·g^(-2)normalized by the sulfur mass)after 100 cycles at 0.1 A·g^(-2)and an excellent rate capability of 350 mAh·g^(-2)at 10 A·g^(-2).
基金support received for this work from the UNSTIM Competitive Funds,2023 edition of the University of Science,Technology,Engineering,and Mathematics(UNSTIM).
文摘The construction industry continues to rely on conventional materials like cement,which often can come with a high cost and significant environmental impact,particularly in terms of greenhouse gas emissions.To tackle the challenges of sustainable development,there is growing interest in using local available materials with low environmental impact.This study primarily focuses on synthesizing and characterizing a geopolymer binder made from local materials found in Benin to stabilize CEB(compressed earth brick).The synthesis involves combining amorphous aluminosilicate powder with a highly concentrated alkaline solution.Local calcined kaolinite clay(metakaolin)and corn cob ash obtained after calcination at 600°C were used with a 12 M sodium hydroxide(NaOH)solution.Different mixtures of geopolymer were formulated substituting metakaolin by corn cob ash at rates of 0%,5%,10%,and 15%of the dry weight of the mixture.Thereafter physical and mechanical characterization tests were conducted on each formulation.Results showed that geopolymer binders containing 85%metakaolin and 15%corn cob ash exhibited the best physical and mechanical performance(e.g.12.08 MPa for compression strength).Subsequently,this geopolymer formulation was used to stabilize CEB.Characterization revealed that CEBs stabilized with 10%geopolymer exhibit good mechanical properties(6.93 MPa),comparable to those of CEBs stabilized with 10%cement(7.40 MPa),justifying their use as load-bearing walls in construction.
文摘Under the current context of climate change, supplementary irrigation may be needed for crop production resilience. We determined the effects of supplementary irrigation on sorghum grain yield in the dry Savannah region of Togo. A two-year trial was conducted in a controlled environment at AREJ, an agro-ecological center in Cinkassé. The plant material was sorghum variety Sorvato 28. The experimental design was a Completely Randomized Block with three replications and three treatments as follows: T0 control plot (rainfed conditions);T1 (supplementary irrigation from flowering to grain filling stage) and T2 (supplementary irrigation from planting to grain filling stage). Two irrigation techniques (furrow and Californian system) were used under each watering treatment. The results showed that irrigation technique significantly affected panicle length with no effect on 1000 grains mass. Panicle length and grain yields varied from 15.59 to 25.71 cm and 0.0 to 2.06 t∙h−1, respectively, with the highest values (25.66 cm and 2.06 t∙h−1, respectively) under the T2 treatment with the California system-based supplementary irrigation. The comparison of results obtained on treatment T0 and T2, shows that supplementary irrigation increased the yields by at least 68.62%. Supplementary irrigation during sowing and growing season (T2) improved sorghum yields in the dry savannahs of Togo, with a better performance of the California irrigation system.
文摘This study tackles current environmental challenges by developing innovative and eco-friendly particle boards utilizing sorghum husk, combined with recycled expanded polystyrene (EPS). This dual eco-responsible approach valorizes sorghum husk, often deemed agricultural waste, and repurposes EPS, a plastic waste, thus contributing to CO2 emission reduction and effective waste management. The manufacturing process involves dissolving recycled polystyrene within a solvent to create a binder, which is then mixed with sorghum husk and cold-pressed into composite boards. The study explores the impact of two particle sizes (fine and coarse) and two different concentrations of the recycled EPS binder. Results demonstrate significant variations in the boards’ mechanical properties, displaying a range of Modulus of Rupture (MOR) from 0.84 MPa to 3.85 MPa, and Modulus of Elasticity (MOE) spanning from 658.13 MPa to 1313.25 MPa, influenced by the binder concentration and particle size. These characteristics suggest that the boards can be effectively used in various construction applications, including interior decoration, false ceilings, and potentially for furniture and door manufacturing when combined with appropriate coatings. This study not only exemplifies the valorization of plastic and agricultural wastes but also offers a practical, localized solution to global climate change challenges by promoting sustainable construction materials.
文摘Managing agricultural waste and expanded polystyrene (EPS) poses significant environmental and economic challenges. This study aims to create composites from millet husks, rice husks, and recycled EPS, using a manufacturing method that involves dissolving the polystyrene in a solvent followed by cold pressing. Various particle sizes and two binder dosages were investigated to assess their influence on the physico-mechanical properties of the composites. The mechanical properties obtained range from 2.54 to 4.47 MPa for the Modulus of Rupture (MOR) and from 686 to 1400 MPa for the Modulus of Elasticity in Bending (MOE). The results indicate that these composites have potential for applications in the construction sector, particularly for wood structures and interior decoration. Moreover, surface treatments could enhance their durability and mechanical properties. This research contributes to the valorization of agricultural and plastic waste as eco-friendly and economical construction materials.
文摘This study explores the development of WPCs(wood-plastic composites)using waste LDPE(low-density polyethylene)and ebony wood sawdust to propose a sustainable solution to waste accumulation.The effect of sawdust particle size and the addition of talc as a coupling agent on the mechanical properties of the composites was examined in detail.The results show that increasing the particle size of the sawdust enhances the MOE(modulus of elasticity)and MOR(modulus of rupture)of the composites.The flexural MOE increases by 195%from the PM(plastic matrix)to composites with the coarsest sawdust,the compressive MOE by 72%,and the tensile MOE by 205%.Similarly,the flexural MOR increases by 28%,the tensile MOR by 42%,but the compressive MOR decreases slightly by 7%.The introduction of talc consistently increased the MOE,with an average improvement of 14%in flexion and 10%in tension for the various composite formulations,although it led to a decrease in compression.The MOR was also enhanced by the addition of talc,with an average increase of 16%across all tested loadings.These improvements suggest that talc can effectively serve as a coupling agent,optimizing the mechanical properties of WPCs for better use of recycled materials.
文摘In this present study, we analyzed the effects of Prandtl and Jacob numbers and dimensionless thermal conductivity on the velocity profiles in media (porous and liquid). The transfers in the porous medium and the liquid film are described respectively by the improved Wooding model and the classical boundary layer equations. The mesh of the digital domain is considered uniform in the transverse and longitudinal directions. The advection and diffusion terms are discretized with a back-centered and centered scheme respectively. The coupled systems of algebraic equations thus obtained are solved numerically using an iterative line-by-line relaxation method of the Gauss-Seidel type. The results show that the parameters relating to the thermal problem (the dimensionless thermal conductivity, the Prandtl (Pr) and Jacob (Ja) numbers) have no influence on the dimensionless speed, although the thermal and hydrodynamic problems are coupled. Via the heat balance equation. The results obtained show that the parameters relating to the thermal problem have no influence on the dimensionless speed, although the thermal and hydrodynamic problems are coupled via the heat balance equation. So, at first approximation with the chosen constants, we can solve the hydrodynamic problem independently of the thermal problem.
文摘In the current context of environmental challenges, this study focuses on developing innovative and eco-friendly composites using rice husk and recycled expanded polystyrene. This dual-responsibility approach valorizes a by-product like rice husk, often considered waste, and reuses polystyrene, a plastic waste, thereby contributing to CO2 emission reduction and effective waste management. The manufacturing process involves dissolving recycled polystyrene into a solvent to create a binder, which is then mixed with rice husk and cold-compacted into composite materials. The study examines the impact of two particle sizes (fine and coarse) and different proportions of recycled polystyrene binder. The results show significant variations in the mechanical characteristics of the composites, with Modulus of Rupture (MOR) values varying from 2.41 to 3.47 MPa, Modulus of Elasticity (MOE) ranging from 223.41 to 1497.2 MPa, and Stiffness Coefficient (K) from 5.04 to 33.96 N/mm. These characteristics demonstrate that these composites are appropriate for various construction applications, including interior decoration, panel claddings, and potentially for furniture and door manufacturing when combined with appropriate coatings. This study not only highlights the recycling of agricultural and plastic waste but also provides a localized approach to addressing global climate change challenges through the adoption of sustainable building materials.
文摘The building sector significantly influences the environment, notably through resource consumption and waste production. Evaluating locally available resources and adopting sustainable development practices are essential to mitigate this impact. This study proposes the fabrication of a wood-polymer composite by recycling polystyrene and wood sawdust. Polystyrene was dissolved in a solvent to obtain a polymer matrix, which was then reinforced with recycled wood sawdust. The mixture was cold-pressed to form composite panels. Physical properties such as density and absorption, as well as mechanical properties like the modulus of elasticity and flexural strength, were examined. Results show that the physical and mechanical properties of the composites vary with the particle size distribution of the wood particles. The modulus of elasticity and flexural strength increase with particle size. The maximum values obtained for the modulus of elasticity and flexural strength are 842 MPa and 3.16 MPa, respectively. These physical and mechanical characteristics indicate that the developed composite material can be used to manufacture elements such as furniture, false ceilings, and lightweight partitions, thereby contributing to more sustainable construction practices.
基金supported by the National Key Research and Development Program of China(2021YFC2101303)the National Natural Science Foundation of China(U22A20424 and 22378048)+6 种基金the Major Scientific and Technological Projects of Sinopecthe Dalian Technology Talents Project for Distinguished Young Scholars(2021RJ03)the Yunnan Provincial Rural Energy Engineering Key Laboratory(2022KF003)the National Natural Science Foundation of Liaoning Province(2023-MS-110)the Liaoning Revitalization Talents Program(XLYC2202049)the Fundamental Research Funds for the Central Universities(DUT22LK22)the CAS Key Laboratory of Renewable Energy,Guangzhou Institute of Energy Conversion(E229kf0401)。
文摘Acetic acid and furfural are known as prevalent inhibitors deriving from pretreatment during lignocellulosic ethanol production.They negatively impact cell growth,glucose uptake and ethanol biosynthesis of Saccharomyces cerevisiae strains.Development of industrial S.cerevisiae strains with high tolerance towards these inhibitors is thus critical for efficient lignocellulosic ethanol production.In this study,the acetic acid or furfural tolerance of different S.cerevisiae strains could be significantly enhanced after adaptive evolution via serial cultivation for 40 generations under stress conditions.The acetic acid-based adaptive strain SPSC01-TA9 produced 30.5 g·L^(-1)ethanol with a yield of 0.46 g·g^(-1)in the presence of 9 g·L^(-1)acetic acid,while the acetic acid/furfural-based adaptive strain SPSC01-TAF94 produced more ethanol of 36.2 g·L^(-1)with increased yield up to 0.49 g·g^(-1)in the presence of both 9 g·L^(-1)acetic acid and 4 g·L^(-1)furfural.Significant improvements were also observed during non-detoxified corn stover hydrolysate culture by SPSC01-TAF94,which achieved ethanol production and yield of 29.1 g·L^(-1)and 0.49 g·g^(-1),respectively,the growth and fermentation efficiency of acetic acid/furfural-based adaptive strain in hydrolysate was 95%higher than those of wildtype strains,indicating the acetic acid-and furfural-based adaptive evolution strategy could be an effective approach for improving lignocellulosic ethanol production.The adapted strains developed in this study with enhanced tolerance against acetic acid and furfural could be potentially contribute to economically feasible and sustainable lignocellulosic biorefinery.
文摘In the contemporary world, there are three interconnected global environmental crises (climate change, biodiversity loss, and pollution). The common thread is the unsustainable pattern of production and consumption, which leads to international and local socio-environmental injustices. Seeking environmental justice in Brazil, the success of the rubber tapper social movement stands out, culminating in the Chico Mendes Extractive Reserve (RESEX) implementation in the Brazilian Amazon. However, the residents have struggled to generate income to help their families’ social reproduction. Conventional payment instruments for environmental services have failed to remunerate the socio-environmental attributes of sustainable products adequately. This paper aims to carry out a socio-environmental economic-ecological valuation of the main extractive products of the RESEX in 2021/2022. To this end, a methodology calculates the cost of social reproduction of rural family production, being a non-market price index reference for monetary valuation. The results indicate the acceptability of the socio-environmental valuation of native rubber and Brazil nuts, as they can guarantee environmental conservation, improve the families’ well-being with adequate income for their social reproduction, as well as value attributes outside the market, which helps in the fight against further expropriation or enclosure of rural families in the Amazon.
文摘The use of groundwater for drinking water supply to the population is increasingly practiced in the rice cultivation area of Maga. However, there is a lack of knowledge about the hydrochemical characteristics of this water due to a lack of quality control. This study aims to contribute to the understanding of mineralization processes in order to establish the hydrochemical profile of the water in the area. The methodological approach consisted of collecting fifteen water samples from wells and boreholes during six campaigns for physicochemical analysis, and studying them through methods of interpreting hydrochemical data. The analysis results show that these waters are moderately mineralized. The water facies are mainly of the bicarbonate sodium and potassium type, as well as the bicarbonate calcium and magnesium type. Calculation of saturation indices demonstrates that evaporite minerals show lower degrees of saturation than carbonate minerals, with gypsum, anhydrite, and halite being in a highly undersaturated state. The mineralization of groundwater originates from the dissolution of surrounding rocks on the one hand, and anthropogenic activities involving exchanges between alkalis (Na+ and K+) in the aquifer and alkaline earth (Ca2+ and Mg2+), resulting in the fixation of alkaline earth and the dissolution of alkalis.
基金supported by a grant (code # 2-2-3) from Sustainable Water Resources Research Center of 21st Century Frontier Research Programthe Development of The Third Korea Multe-Purpose Satellite funded by Ministry of Education Science
文摘This study evaluated the reduction effect of non-point source pollution by applying best management practices （BMPs） to a 1.21 km^2 small agricultural watershed using a SWAT （Soil and Water Assessment Tool） model. Two meter QuickBird land use data were prepared for the watershed. The SWAT was calibrated and validated using dally streamflow and monthly water quality （total phosphorus （TP）, total nitrogen （TN）, and suspended solids （SS）） records from 1999 to 2000 and from 2001 to 2002. The average Nash and Sutcliffe model efficiency was 0.63 for the streamflow and the coefficients of determination were 0.88, 0.72, and 0.68 for SS, TN, and TP, respectively. Four BMP scenarios viz. the application of vegetation filter strip and riparian buffer system, the regulation of Universal Soil Loss Equation P factor, and the fertilizing control amount for crops were applied and analyzed.
文摘The purpose of this work is to study the effect of a type of water-saving irrigation （WSI） on nutrient runoff of paddy field. The volume of surface drainage was maintained low by WSI. In particular, WSI effectively reduced surface drainage in rain events. Model simulation indicated that net runoff load of total nitrogen （TN） from the paddy field was increased by WSI. Meanwhile, net runoff loads of total phosphorus （TP） and total organic carbon （TOC） from the paddy field was decreased by WSI. Because ponding waters of the study fields were enriched with TP and TOC, WSI reduced runoff of these nutrients by controlling the volume of surface drainage. WSI could be considered an efficient method for reducing runoff loads and could conserve water quality in an agricultural watershed.
文摘A model in which a river model was layered on a distributed model （double-layered model） was developed to analyse the transport of water and pollutants （nitrogen, phosphorus, and BOD as organic matter） in watersheds and rivers. The model was applied to the watershed of Abragafuchi Lake, Japan, where serious water pollution has occurred over three decades, and the applicability of the model was demonstrated. Scenarios of recycling of sewage treated-water into agriculture to reduce pollutant load discharged into the lake were analysed. The results showed that irrigating paddy fields with the sewage-treated water could contribute to conserving water and reducing pollutant load, with reduction rate in BOD, nitrogen, and phosphorus ranging from 6%-36%, 16%-46%, and 18%-51%, respectively. Particularly, the results indicated that, irrigating paddy fields with the treated water during non-cropping periods and the accompanying reduction in withdrawn water from the river were more effective in reducing pollutant loads discharged into the lake. Further study is required on the effect of recycled water on crop cultivation and soil conditions for safe implementation.
