Assessing the Impact of Gold Mining on the Quality of Water Resources in the Commune of Meguet, Burkina Faso

Despite its often illegal nature, artisanal gold mining in Burkina Faso contributes to the economic and social development of the country. However, the rudimentary techniques used in gold panning have a significant impact on the environment due to inappropriate practices and the use of various chemical substances. This study aims to assess the impact of artisanal gold mining on the quality of water resources in a rural community at Méguet, Burkina Faso. To this end, surface and groundwater samples were collected and analyzed at the BUMIGEB laboratory. Field results show that the waters are slightly alkaline (6.97 < pH < 8.1), weakly mineralized and conductive (124 < EC < 543 μS/cm), with temperatures ranging from 24.6˚C to 31.6˚C. In addition, trace metals (TMEs) analyzed from surface and subsurface waters show very high levels, generally deviating from the levels recommended by WHO guidelines for Burkina Faso. Trace metals contamination of water resources in the commune of Méguet is mainly due to Fe (3.78 - 11.12 mg/kg), Hg (0.03 - 0.29 mg/kg), As (0.01- 6.31 mg/kg) and Pb (0.01 - 3.8 mg/kg). This study can serve as a basis for guiding national environmental policies to protect the water resources of the Méguet mine.

Impacts of Agricultural Activities on Land Degradation along the Bomboré River in Burkina Faso

Land along the Bomboré River in the rural commune of Mogtédo in Burkina Faso is experiencing degradation. The explanatory causes of this degradation constitute the subject of this study. To do this, a survey was conducted among agricultural producers deployed along the watercourse. Soil profiles were described and samples were taken to analyze pH, soil organic carbon, soil organic matter, total nitrogen, and texture. The RUSLE model approach based on landstat8 OLI/TIRS and SRTM satellite images dated December 17, 2021 with fairly good radiometric, spatial, and spectral resolution was used to calculate the land loss rate. In terms of results, the potentially irrigable areas that spread out on both sides of the banks of the river cover 209.23 ha with a perimeter of 6.16 km. The number of irrigators is 26 producers and they grow 17.92 ha of vegetables. Soil analyzes indicate the presence of a moderate acid on the vertisol with a pH between 5.57 and 5.86. On the depth 0 - 30 cm of the horizon, the color of the horizons ranges from 5YR4/2 on the talweg and on the right bank to 7.5YR3/2 on the left bank and presents no risk of salinity because the electrical conductivity measured is less than 1dS/cm. The diagnosis of hydromechanical equipment shows that producers use 46 motor pumps for irrigation, of which 15 motor pumps run on gasoline and 31 motor pumps on butane gas with a ratio of 1.7 motor pumps per producer. The number of Polyvinyl Chloride (PVC) pipes used by producers in combination with a motor pump gives an average of 44 per farmer. In terms of mineral fertilization, the gross doses used by producers are 415.53 kg/ha of NPK and 201.55 kg/ha of urea, while the quantities of phytosanitary products are 3.99 l/ha of pesticides and 1.42 l/ha of herbicides. Agricultural activities emit about 222,436.66 kgCO2eq into the atmosphere, whose emissions from motor pumps represent 84.52% of these total emissions. The land loss estimate gives an average rate of 2.30 t/ha/year of land loss. This loss is due to the effects of poor agricultural practices, water erosion, and the drainage channels and gullies created by the anarchic installation of dwellings around the edges of the river. This study calls for more monitoring actions to sustainably safeguard the soil and water resources of this river which contribute to the survival of more than 73,214 inhabitants.

Parameter Estimations for Some Modifications of the Weibull Distribution

Proposed by the Swedish engineer and mathematician Ernst Hjalmar Waloddi Weibull (1887-1979), the Weibull distribution is a probability distribution that is widely used to model lifetime data. Because of its flexibility, some modifications of the Weibull distribution have been made from several researches in order to best adjust the non-monotonic shapes. This paper gives a study on the performance of two specific modifications of the Weibull distribution which are the exponentiated Weibull distribution and the additive Weibull distribution.

Efficiency Evaluation of Continuously Variable Transmissions Including a Planetary Gear Train

With their advantages, continuously variable transmissions have gained more popularity in the last decade by their use in mechanical transmission systems. The present paper aims to analysis the efficiency of the transmission based on the mechanical efficiency of the planetary gear train integrated in such transmission. In this analysis, we consider the mechanical efficiency of the transmission has been determined considering how the efficiency of the CVT members changes as a function of the operating conditions. The efficiency of the planetary gear train as a function of the configuration, speeds in his three input/output shafts, and also with respect to the power flow type. Results are compared with those obtained from other methods performance evaluation of the transmission, available in the literature.

Altitudinal differentiation of Quercus robur in Bosnia and Herzegovina

Morphological variation based on eight measured and four derived traits was studied to establish whether there was significant variation between populations and to identify the influence of the altitude on morphological differentiation among 44 natural stands of common oak（Quercus robur L.） in Bosnia and Herzegovina,ranging from 82 to 860 m.The results point to significant intra-and inter-population differences.Elevation-related variation is less pronounced and determined largely by microclimatic factors.The results could provide management strategies for species reintroduction in the study area.There are no differences in leaf morphology between the different branches of individual trees.However,there are important variations between the altitudinal groups and closely linked to environmental factors in all traits.An important recommendation is to use seeds from oak with attention to their altitudinal origin.

Predictive Models for the Ultimate Tensile and Yield Stresses Occurring in Joints of Untreated Friction Stir Welded 2017AA (ENAW-AlCu4MgSi) Plates

Friction Stir Welding (FSW) processes have been applied in numerous industrial fields and broadly embraced by the research community. In this paper, given three FSW process parameters, namely, the tool rotation speed N (rpm), the tool traverse feed F(mm/min) and the tool pin/shoulder diameters ratio (r%), we purpose to ascertain their impact on joints Ultimate Tensile Stress (UTS) and joints Yield Stress (YS). The FSW has been executed using 6 mm thick rolled plate in 2017AA. For the design of experiments strategy, we conducted a face centered central composite strategy through which 18 trials have been executed. Then, we utilized the RSM technique to formulate the predictive models which are relevant to the (UTS) and (YS) outputs. Accordingly, the study has pointed out the prevalence of the tool rotation speed and the tool diameters ratio factors;however, the tool traverse feed (F) was found trivial and statistically insignificant. Likewise, the sensitivity analysis regarding factors N, F and r% on both (UTS) and (YS) has exhibited the dominance of the tool diameters ratio (r%), indistinctively.

Numerical Study of a Cylindro-Parabolic Cooker “Blazing Tube”

The objective of this work is to numerically determine the thermal performance of the parabolic cylinder cooker commonly “blazing tube”. These performances were determined by establishing heat balances at the different levels of the system. The equations obtained have been discretized;simplifying assumptions have been made to facilitate their resolution. We adopted Gauss Seidel’s method using MATLAB software to solve these equations. The temperatures of the coolant, the glass and the absorber were determined as a function of time and along the tube. The thermal efficiency was also determined. It emerged that the different temperatures evolve linearly as a function of the length of the tube. Yield and temperatures depend on the amount of sunshine.

The Environmental Impact of Polycyclic Aromatic Hydrocarbons: Mechanism of Extraction by Bio-Surfactant in a Microwave

In N’Djaména, the use and marketing of certain hydrocarbons does not comply with any standard in force or with regulations provided for this purpose. Their evaporation and unregulated release into the wild significantly affects the ecosystem. The present work consists in developing a method of extraction from sediments polluted by bio surfactant (rhamnolipid) assisted by microwaves. The goal here is to look for the presence of polycyclic aromatic hydrocarbons in polluted sediments. The rhamnolipid used consists of monorhamnolipids and di-rhamnolipids, its emulsion index is 64.66% and is composed of saturated and unsaturated fatty acids having carbon numbers ranging from 12 to 18. We used the microwave micellar extraction process. It was made by keeping the concentration values fixed at 0.15 g/L and the power at 400 W and more. We observed a positive interaction of the rhamnolipid concentration factors and the power of the microwave to obtain the optimal conditions at the time of 50 S, at the concentration of 0.16 g/L and at the power of 443 W for a rate of optimal extraction of 0.91%. Chromatographic analysis by GC-MS of the optimum extracts allowed us to identify twelve (12) C10 to C43 n-alkanes and eight (8) PAHs. It emerges from this analysis that the rhamnolipid extracts seven (7) Polycyclic Aromatic Hydrocarbons in equivalent proportions while the tween 80 extracts only four (4) Polycyclic Aromatic Hydrocarbons with a high proportion (80.02%) of benzo [a] antracene.

纳米流体在平板上的湍流边界层和流体流动分析

对分别浸入3种纳米流体(ZnO-水,SiO_(2)-水,TiO_(2)-水)的平板近壁面流动的湍流边界层的对数规律进行数值分析。采用CFD程序对边界层和流体动力流动进行数值模拟。使用已发表的测量点对数值模型进行验证,结果表明一致性较好。对流速0.04 m/s,0.4 m/s,4 m/s以及纳米颗粒浓度0.1%和5%的情况进行模拟。研究了纳米颗粒浓度对速度、温度分布、壁面剪切应力和湍流强度的影响。结果表明:沿势流层的黏性亚层、缓冲层和对数律层可以基于具有单壁距离区域的弯曲质量进行分析。可见,与其他区域相比,黏性亚层面积最大。另一方面,温度变化与热边界层厚度有关的区域在流速减小时也减小,热边界层离前缘越来越深,而纳米颗粒体积分数的增加对壁面剪切应力的影响较小。在所有情况下,边界层的厚度都随着流速的增加而减小,而纳米颗粒浓度的增加会使边界层的厚度增加。更准确地说,对数层在Y^(+)=50和Y^(+)=95之间最小。在所研究的纳米流体中,φ=5%时的边界层温度高于φ=0.1%时的边界层温度。而Y^(+)=1时,结果正好相反,φ=0.1%时的温度比φ=5%的更高。当流速分别为v=4,0.4,0.04 m/s时,湍流强度峰值分别出现在Y^(+)=100,Y^(+)=10和Y^(+)=8时。

All-optical generation of static electric field in a single metal-semiconductor nanoantenna

Electric field is a powerful instrument in nanoscale engineering,providing wide functionalities for control in various optical and solid-state nanodevices.The development of a single optically resonant nanostructure operating with a charge-induced electrical field is challenging,but it could be extremely useful for novel nanophotonic horizons.Here,we show a resonant metal-semiconductor nanostructure with a static electric field created at the interface between its components by charge carriers generated via femtosecond laser irradiation.We study this field experimentally,probing it by second-harmonic generation signal,which,in our system,is time-dependent and has a non-quadratic signal/excitation power dependence.The developed numerical models reveal the influence of the optically induced static electric field on the second harmonic generation signal.We also show how metal work function and silicon surface defect density for different charge carrier concentrations affect the formation of this field.We estimate the value of optically-generated static electric field in this nanoantenna to achieve≈10^(8)V/m.These findings pave the way for the creation of nanoantenna-based optical memory,programmable logic and neuromorphic devices.

Effects of the nitrification inhibitor nitrapyrin and tillage practices on yield-scaled nitrous oxide emission from a maize field in Iran

Nitrification inhibitors can effectively decrease nitrification rates and nitrous oxide(N_(2)O)emission while increasing crop yield under certain conditions.However,there is no information available on the effects of nitrification inhibitors and tillage practices on N_(2)O emissions from maize cropping in Iran.To study how tillage practices and nitrapyrin(a nitrification inhibitor)affect N_(2)O emission,a split factorial experiment using a completely randomized block design with three replications was carried out in Northeast Iran,which has a cold semiarid climate.Two main plots were created with conventional tillage and minimum tillage levels,and two nitrogen(N)fertilizer(urea)management systems(with and without nitrapyrin application)were created as subplots.Tillage level did not have any significant effect on soil ammonium(NH_(4)^(+))and nitrate(NO_(3)^(-))concentrations,cumulative amount and yield-scaled N_(2)O emission,and aboveground biomass of maize,whereas nitrapyrin application showed significant effect.Nitrapyrin application significantly reduced the cumulative amount of N_(2)O emission by 41%and 32%in conventional tillage and minimum tillage practices,respectively.A reduction in soil NO_(3)^(-)concentration by nitrapyrin was also observed.The average yield-scaled N_(2)O emission was 13.6 g N_(2)O-N kg^(-1)N uptake in both tillage systems without nitrapyrin application and was significantly reduced to 7.9 and 8.2 g N_(2)O-N kg^(-1)N uptake upon the application of nitrapyrin in minimum tillage and conventional tillage practices,respectively.Additionally,nitrapyrin application increased maize biomass yield by 4%and 13%in the minimum tillage and conventional tillage systems,respectively.Our results indicate that nitrapyrin has a potential role in reducing N_(2)O emission from agricultural systems where urea fertilizers are broadcasted,which is common in Iran due to the practice of traditional farming.

State Feedback Tracking Control for Indirect Field-oriented Induction Motor Using Fuzzy Approach

This paper deals with the synthesis of fuzzy controller applied to the induction motor with a guaranteed model reference tracking performance. First, the Takagi-Sugeno （T-S） fuzzy model is used to approximate the nonlinear system in the synchronous d-q frame rotating with field-oriented control strategy. Then, a fuzzy state feedback controller is designed to reduce the tracking error by minimizing the disturbance level. The proposed controller is based on a T-S reference model in which the desired trajectory has been specified. The inaccessible rotor flux is estimated by a T-S fuzzy observer. The developed approach for the controller design is based on the synthesis of an augmented fuzzy model which regroups the model of induction machine, fuzzy observer, and reference model. The gains of the observer and controller are obtained by solving a set of linear matrix inequalities （LMIs）. Finally, simulation and experimental results are given to show the performance of the observer-based tracking controller.