This study utilizes empirical equations to describe the propagation of vibrations induced by blasting, with the goal of predicting the attenuation of Peak Particle Velocity (PPV) at the Yaramoko mine in Bagassi, Burki...This study utilizes empirical equations to describe the propagation of vibrations induced by blasting, with the goal of predicting the attenuation of Peak Particle Velocity (PPV) at the Yaramoko mine in Bagassi, Burkina Faso, a site characterized by granitoid rock. Four empirical PPV prediction equations were employed, so-called Duvall & Fogelson (or the United States Bureau of Mines “USBM”), Langefors and Kihlstrom, Ambressys-Hendron, and the Bureau of Indian Standard. The constant parameters for each of these equations, referred to as site constants, were derived from linear regression curves. The results show that the site constants k, a, and b of 4762, 0.869, and 1.737, respectively, derived from the general prediction equation by Davies, PPV = kQaD−b, based on Duvall & Fogelson, are in good agreement with values of 4690, 0.9, and 1.69, respectively, for similar rock types in Spain. Regarding the impacts of blasting on houses, the findings indicate that houses built from laterite-block bricks in the village of Bagassi are the most vulnerable to vibration waves, followed by those constructed with cinder-block bricks. In contrast, houses made of banco bricks are the most resilient. Additionally, it was determined that during blasting operations, adjusting the blasting parameters to ensure the PPV does not exceed 2 mm/s at the level of nearby dwellings can minimize the appearance of cracks in houses.展开更多
In the present work, the mass transfer characteristics, namely moisture diffusivity and moisture transfer coefficient of “Violet de Galmi” variety of onions were evaluated using the analytical model. Onions were dri...In the present work, the mass transfer characteristics, namely moisture diffusivity and moisture transfer coefficient of “Violet de Galmi” variety of onions were evaluated using the analytical model. Onions were dried in a single layer at different temperatures (40℃, 50℃, 60℃, and 70℃) and for a relative humidity of drying air of 20%. The results showed a reasonably good agreement between the values predicted by the correlation and the experimental observations. This model computed the Biot number, effective moisture diffusivity, and mass transfer coefficient. Effective diffusion coefficient values are obtained between 0.2578 × 10<sup>-9</sup> m<sup>2</sup>·s<sup>-1</sup> and 0.5460 × 10<sup>-9</sup> m<sup>2</sup>·s<sup>-1</sup>. Mass transfer coefficients of “Violet de Galmi” onion drying vary between 3.37 × 10<sup>-7</sup> m·s<sup>-1</sup> and 13.38 × 10<sup>-7</sup> m·s<sup>-1</sup>. Numbers of mass transfer Biot are found between 0.9797 and 2.9397. The activation energy E<sub>a</sub> is 31.73 kJ·mol<sup>-1</sup>.展开更多
In Western countries, research works on air quality have reinforced in recent years because of the links between the level of particulate pollution in numerous cities and the appearing of various health disorders incl...In Western countries, research works on air quality have reinforced in recent years because of the links between the level of particulate pollution in numerous cities and the appearing of various health disorders including cardio-respiratory pathologies, acute bronchopneumonia, lung cancer, etc. In sub-Saharan Africa countries, particularly Burkina Faso, there is very few similar research. In the present work, the pollution levels of airborne particle in the city of Ouagadougou have been assessed through two campaigns of in situ measurements of suspended particulate matter concentrations. These measurements which have concerned PM<sub>1</sub>, PM<sub>2.5</sub> and PM<sub>10</sub> were performed using a portable device (AEROCET531S) at nine sites in 2018 and at ten sites in 2019. These sites are located on roadside, administrative services, secondary education establishments and outlying districts. The results show that: 1) the PM1 concentrations values presented no significant variation between days, seasons or sampling sites;2) the 24-hour PM<sub>2.5</sub> concentrations often exceeding WHO recommended concentrations and, 3) the 24-hour PM<sub>10</sub> concentrations exceed WHO recommended concentrations regardless of the season or the sampling site. In indeed, the average 24-hour concentrations are 20 ± 4, 87 ± 16 and 951 ± 266 μg<span style="white-space:nowrap;">·</span>m<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>3</sup> for the PM1, PM<sub>2.5</sub> and PM<sub>10</sub>, respectively. They are 17 ± 3, 29 ± 5 and 158 ± 43 μg<span style="white-space:nowrap;">·</span>m<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>3</sup>, respectively, in 2018 dry season and, 12 ± 1, 22 ± 9 and 187 ± 67 μg<span style="white-space:nowrap;">·</span>m<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>3</sup>, respectively, in 2019 rainy season.展开更多
Air pollution is one of the major global threats to human health. In Burkina Faso, more than 80% of the population uses solid fuels as the main source of cooking energy. This paper reports a comparative study on the e...Air pollution is one of the major global threats to human health. In Burkina Faso, more than 80% of the population uses solid fuels as the main source of cooking energy. This paper reports a comparative study on the exposure of household to the carbon monoxide (CO) and particulate matter (PM<sub>2.5</sub>) emitted by improved cookstoves (ICS) or traditional cookstoves (TCS). A cross-sectional study was conducted in the city of Ouagadougou for 4 months during the rainy season (July to October) in households with an outdoor kitchen. The investigation involved 92 households where air pollutants, such as PM<sub>2.5</sub> and CO were measured with Indoor Air Pollution Meters (IAP meter). These measurements were focused on the concentration levels of the pollutants during cooking. The results of this study show high levels of PM<sub>2.5</sub> and CO for all type of stoves. Wood stoves led to higher PM<sub>2.5</sub> and lower CO emissions than charcoal stoves. ICS reduce emissions of indoor air pollutants compared to TCS. This reduction raised up to 82% for PM<sub>2.5</sub> and 37% for CO. The analysis of the data measured with the student test (t-test) shows that there is a statistically significant difference between the average values of the concentrations of the pollutants emitted with the TCS compared to ICS, except for CO emissions measured on multi-pot sizes cookstoves (MM). This study shows that the concentrations of indoor air pollutants are very high regardless of the type of cookstoves used. The CO exposure obtained varies from 119.10 to 362.72 μg/m<sup>3</sup> for 15-minute and 10.83 - 55.11 μg/m<sup>3</sup> for 1-hour exposure. The exposure in PM<sub>2.5</sub> varies from 4762 to 16,257 μg/m<sup>3</sup> for 15-minute and 106.63 to 1597 μg/m<sup>3</sup> for 1-hour of exposure. It was noted that the CO exposure levels obtained over 15-minute of exposure are 1.36 to 4.15 times higher than the WHO recommendation and 1.8 times higher for an exposure time of one hour. This means that women in charge of cookin展开更多
Solar cookers are a good option in developing countries with high solar potential for environmentally friendly cooking and reduced pressure on forests. However, they are still affected by the intermittency of the sun....Solar cookers are a good option in developing countries with high solar potential for environmentally friendly cooking and reduced pressure on forests. However, they are still affected by the intermittency of the sun. In order to overcome this problem, in this work, a box type solar cooker integrated Jatropha oil as a heat storage material is fabricated and experimented with. The design was examined with a maximum stagnation temperature of 157.7°C. The recorded cooking power vanished between 78.4 and 103.6 W, while thermal efficiency varied from 41.26% to 58.78%. The energy transfer cycle test, including charge and discharge revealed that 91.18% of the heat lost through the cooker could be recovered by the heat storage unit and a large amount is restored to the system during cloudiness or a temperature perturbation.展开更多
This work focuses on blending Jatropha oil with diesel fuel and heptane to improve its physico-chemical characteristics for production of blends and their use as fuel in a diesel engine. The influence of the heptane c...This work focuses on blending Jatropha oil with diesel fuel and heptane to improve its physico-chemical characteristics for production of blends and their use as fuel in a diesel engine. The influence of the heptane content was evaluated by comparing the results obtained from the engine (performance and combustion parameters) with those of the diesel fuel and straight Jatropha oil. The results obtained show an improvement in engine performance especially at low loads. Specifically, a reduction in the specific fuel consumption of the engine is obtained when the heptane content in the mixture is around 10% compared to that obtained with pure Jatropha oil. The best results were obtained with the blend containing 70% Jatropha oil, 20% diesel fuel and 10% heptane (J70G20H10). Overall engine efficiency and exhaust gas temperatures are comparable for all fuels tested. Engine combustion parameters are improved with J70G20H10. The results obtained with J70G20H10 are close to those of the engine operating on diesel fuel. The cyclic dispersion is low with coefficients of variation of the indicated mean effective pressure (COV<sub>IMEP</sub>) whose values are less than 10%. The lowest values of the COV<sub>IMEP</sub> are obtained with the blend J70G20H10.展开更多
文摘This study utilizes empirical equations to describe the propagation of vibrations induced by blasting, with the goal of predicting the attenuation of Peak Particle Velocity (PPV) at the Yaramoko mine in Bagassi, Burkina Faso, a site characterized by granitoid rock. Four empirical PPV prediction equations were employed, so-called Duvall & Fogelson (or the United States Bureau of Mines “USBM”), Langefors and Kihlstrom, Ambressys-Hendron, and the Bureau of Indian Standard. The constant parameters for each of these equations, referred to as site constants, were derived from linear regression curves. The results show that the site constants k, a, and b of 4762, 0.869, and 1.737, respectively, derived from the general prediction equation by Davies, PPV = kQaD−b, based on Duvall & Fogelson, are in good agreement with values of 4690, 0.9, and 1.69, respectively, for similar rock types in Spain. Regarding the impacts of blasting on houses, the findings indicate that houses built from laterite-block bricks in the village of Bagassi are the most vulnerable to vibration waves, followed by those constructed with cinder-block bricks. In contrast, houses made of banco bricks are the most resilient. Additionally, it was determined that during blasting operations, adjusting the blasting parameters to ensure the PPV does not exceed 2 mm/s at the level of nearby dwellings can minimize the appearance of cracks in houses.
文摘In the present work, the mass transfer characteristics, namely moisture diffusivity and moisture transfer coefficient of “Violet de Galmi” variety of onions were evaluated using the analytical model. Onions were dried in a single layer at different temperatures (40℃, 50℃, 60℃, and 70℃) and for a relative humidity of drying air of 20%. The results showed a reasonably good agreement between the values predicted by the correlation and the experimental observations. This model computed the Biot number, effective moisture diffusivity, and mass transfer coefficient. Effective diffusion coefficient values are obtained between 0.2578 × 10<sup>-9</sup> m<sup>2</sup>·s<sup>-1</sup> and 0.5460 × 10<sup>-9</sup> m<sup>2</sup>·s<sup>-1</sup>. Mass transfer coefficients of “Violet de Galmi” onion drying vary between 3.37 × 10<sup>-7</sup> m·s<sup>-1</sup> and 13.38 × 10<sup>-7</sup> m·s<sup>-1</sup>. Numbers of mass transfer Biot are found between 0.9797 and 2.9397. The activation energy E<sub>a</sub> is 31.73 kJ·mol<sup>-1</sup>.
文摘In Western countries, research works on air quality have reinforced in recent years because of the links between the level of particulate pollution in numerous cities and the appearing of various health disorders including cardio-respiratory pathologies, acute bronchopneumonia, lung cancer, etc. In sub-Saharan Africa countries, particularly Burkina Faso, there is very few similar research. In the present work, the pollution levels of airborne particle in the city of Ouagadougou have been assessed through two campaigns of in situ measurements of suspended particulate matter concentrations. These measurements which have concerned PM<sub>1</sub>, PM<sub>2.5</sub> and PM<sub>10</sub> were performed using a portable device (AEROCET531S) at nine sites in 2018 and at ten sites in 2019. These sites are located on roadside, administrative services, secondary education establishments and outlying districts. The results show that: 1) the PM1 concentrations values presented no significant variation between days, seasons or sampling sites;2) the 24-hour PM<sub>2.5</sub> concentrations often exceeding WHO recommended concentrations and, 3) the 24-hour PM<sub>10</sub> concentrations exceed WHO recommended concentrations regardless of the season or the sampling site. In indeed, the average 24-hour concentrations are 20 ± 4, 87 ± 16 and 951 ± 266 μg<span style="white-space:nowrap;">·</span>m<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>3</sup> for the PM1, PM<sub>2.5</sub> and PM<sub>10</sub>, respectively. They are 17 ± 3, 29 ± 5 and 158 ± 43 μg<span style="white-space:nowrap;">·</span>m<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>3</sup>, respectively, in 2018 dry season and, 12 ± 1, 22 ± 9 and 187 ± 67 μg<span style="white-space:nowrap;">·</span>m<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>3</sup>, respectively, in 2019 rainy season.
文摘Air pollution is one of the major global threats to human health. In Burkina Faso, more than 80% of the population uses solid fuels as the main source of cooking energy. This paper reports a comparative study on the exposure of household to the carbon monoxide (CO) and particulate matter (PM<sub>2.5</sub>) emitted by improved cookstoves (ICS) or traditional cookstoves (TCS). A cross-sectional study was conducted in the city of Ouagadougou for 4 months during the rainy season (July to October) in households with an outdoor kitchen. The investigation involved 92 households where air pollutants, such as PM<sub>2.5</sub> and CO were measured with Indoor Air Pollution Meters (IAP meter). These measurements were focused on the concentration levels of the pollutants during cooking. The results of this study show high levels of PM<sub>2.5</sub> and CO for all type of stoves. Wood stoves led to higher PM<sub>2.5</sub> and lower CO emissions than charcoal stoves. ICS reduce emissions of indoor air pollutants compared to TCS. This reduction raised up to 82% for PM<sub>2.5</sub> and 37% for CO. The analysis of the data measured with the student test (t-test) shows that there is a statistically significant difference between the average values of the concentrations of the pollutants emitted with the TCS compared to ICS, except for CO emissions measured on multi-pot sizes cookstoves (MM). This study shows that the concentrations of indoor air pollutants are very high regardless of the type of cookstoves used. The CO exposure obtained varies from 119.10 to 362.72 μg/m<sup>3</sup> for 15-minute and 10.83 - 55.11 μg/m<sup>3</sup> for 1-hour exposure. The exposure in PM<sub>2.5</sub> varies from 4762 to 16,257 μg/m<sup>3</sup> for 15-minute and 106.63 to 1597 μg/m<sup>3</sup> for 1-hour of exposure. It was noted that the CO exposure levels obtained over 15-minute of exposure are 1.36 to 4.15 times higher than the WHO recommendation and 1.8 times higher for an exposure time of one hour. This means that women in charge of cookin
文摘Solar cookers are a good option in developing countries with high solar potential for environmentally friendly cooking and reduced pressure on forests. However, they are still affected by the intermittency of the sun. In order to overcome this problem, in this work, a box type solar cooker integrated Jatropha oil as a heat storage material is fabricated and experimented with. The design was examined with a maximum stagnation temperature of 157.7°C. The recorded cooking power vanished between 78.4 and 103.6 W, while thermal efficiency varied from 41.26% to 58.78%. The energy transfer cycle test, including charge and discharge revealed that 91.18% of the heat lost through the cooker could be recovered by the heat storage unit and a large amount is restored to the system during cloudiness or a temperature perturbation.
文摘This work focuses on blending Jatropha oil with diesel fuel and heptane to improve its physico-chemical characteristics for production of blends and their use as fuel in a diesel engine. The influence of the heptane content was evaluated by comparing the results obtained from the engine (performance and combustion parameters) with those of the diesel fuel and straight Jatropha oil. The results obtained show an improvement in engine performance especially at low loads. Specifically, a reduction in the specific fuel consumption of the engine is obtained when the heptane content in the mixture is around 10% compared to that obtained with pure Jatropha oil. The best results were obtained with the blend containing 70% Jatropha oil, 20% diesel fuel and 10% heptane (J70G20H10). Overall engine efficiency and exhaust gas temperatures are comparable for all fuels tested. Engine combustion parameters are improved with J70G20H10. The results obtained with J70G20H10 are close to those of the engine operating on diesel fuel. The cyclic dispersion is low with coefficients of variation of the indicated mean effective pressure (COV<sub>IMEP</sub>) whose values are less than 10%. The lowest values of the COV<sub>IMEP</sub> are obtained with the blend J70G20H10.
