Miners in Australia frequently perform physically demanding work under high ambient temperatures and humidity, often whilst wearing personal protective equipment, leading to heat-related illnesses. This study investig...Miners in Australia frequently perform physically demanding work under high ambient temperatures and humidity, often whilst wearing personal protective equipment, leading to heat-related illnesses. This study investigated effects of replacing 100% and 50% sweat losses with 5% carbohydrate liquid or ice-slurry solution on core temperature during simulated mining conditions. Five randomized treadmill trials were performed with: no fluid replacement (NF), 100% (100 ICE) and 50% (50 ICE) sweat loss replaced with ice-slurry (~-1°C) solution and 100% (100 LIQ) and 50% (50 LIQ) sweat loss replaced with liquid (~+4°C) solution. Time to exhaustion was longer in 100 ICE followed by 100 LIQ, 50 ICE, 50 LIQ and NF. Change in rectal temperature was least in 100 ICE followed by 100 LIQ, 50 ICE, 50 LIQ and NF. Ingestion of ice-slurry resulted in longer time to exhaustion and slower rates of change in rectal temperature. It is recommended that ice-slurry drinks be provided to personnel to lower heat strain during hot working conditions.展开更多
A numerical approach to heat and mass transfer in a large water reservoir is presented. This water reservoir is likened to a parallelepiped reservoir whose vertical and lower walls are adiabatic and impermeable. The e...A numerical approach to heat and mass transfer in a large water reservoir is presented. This water reservoir is likened to a parallelepiped reservoir whose vertical and lower walls are adiabatic and impermeable. The equations that govern natural convection in water are solved by the finite volume method and Thomas’salgorithm. The adequacy between the velocity and pressure fields is ensured by the SIMPLE algorithm. We are going to evaluate the water losses by evaporation from three dams in the Nakanbé basin in Burkina Faso for a period of thirty years, that is to say from January 1, 1991, to March 15, 2020. The three dams have a rate of evaporation greater than 40% of the volume of water stored. Indeed the rate of evaporation in each dam increases with the water filling rate in the reservoir: we have observed the following results for each dam in the Nakanbé basin;for the date of 02/27/1988 to 03/13/2020., the Loumbila dam received a total volume of stored water of 22.02 Mm<sup>3</sup> and 10.57 Mm<sup>3</sup> as the total volume of water evaporated at the same date. At the Ouaga dam (2 + 3), it stored a water volume of 4.06 Mm<sup>3</sup> and evaporated 2.03 Mm<sup>3</sup> of its storage volume from 01/01/1988 to 05/07/2016. Finally, with regard to the Bagré dam, it stored 745.16 Mm<sup>3</sup> of water and 365.13 Mm<sup>3</sup> as the volume of water evaporated from 01/01/1993 to 03/31/2020.展开更多
This study focuses on the use of heavy fuel oil in construction material in Burkina Faso. Its mixture with silty or clayey soil is used as a coating to reinforce the walls of raw earth constructions which are very sen...This study focuses on the use of heavy fuel oil in construction material in Burkina Faso. Its mixture with silty or clayey soil is used as a coating to reinforce the walls of raw earth constructions which are very sensitive to water. The interest of this study is to determine erodibility, water content, while highlighting the influence of the porosity accessible by water on thermal diffusion in construction material containing heavy fuel oil. The heavy fuel oil was mixed with a silty-clayey soil, in different proportions, and water to make bricks samples on which tests were carried out. At the end of the experimental tests, it appears that the water content increases gradually, but not significantly with the addition of heavy fuel oil, which causes a slight increase in the speed of heat propagation through the material with reduced porosity, particularly those containing higher quantities of heavy fuel oil. Conversely, we note a good performance of heavy fuel oil in terms of water resistance properties such as porosity accessible by water and erodibility. This allows us to conclude that the mixture of heavy fuel oil and silty-clayey soil used as a coating material could greatly reduce water infiltration into the walls of housing constructions with raw earthen materials.展开更多
Knowledge of thermodynamic properties as well as parameters such as energy density and power flow isimportant for modeling thermal plasmas of fluoroalkylamine-air mixtures. In this paper, these thermodynamic prop...Knowledge of thermodynamic properties as well as parameters such as energy density and power flow isimportant for modeling thermal plasmas of fluoroalkylamine-air mixtures. In this paper, these thermodynamic properties of fluoroalkylamine-air mixture plasmas are calculated in a temperature range of 500 K to 20,000 K at atmospheric pressure and local thermodynamic equilibrium (LTE). The Gibbs free energy minimization method is used to determine the chemical equilibrium compositions of the plasmas that are needed to calculate the thermodynamic properties. These thermodynamic properties are then used to calculate the energy density and power flow of these plasmas. The variation of the energy density is related to the variations of the density and mass enthalpy. We notice that, this energy density increases with the percentage of air in the mixture for temperatures higher than 7000 K. The power flow, which depends also on density, enthalpy mass and sound speed, increases with the percentage of air in the same temperature range. Energy density and power flow results show that increasing air percentage in the mixture can be more interesting for damaging gaseous chemical species such as CF<sub>2</sub>, CO, HCN, and HF appearing at low temperatures with high concentrations.展开更多
Living in a habitat with comfort is requested by all. Cinder block bricks have poor thermal properties, leading people to use fan heaters and air conditioners to regain comfort. To overcome this problem of thermal dis...Living in a habitat with comfort is requested by all. Cinder block bricks have poor thermal properties, leading people to use fan heaters and air conditioners to regain comfort. To overcome this problem of thermal discomfort in buildings, we used lightweight concrete such as foamed concrete which is a material that has improved thermal properties for thermal comfort. In addition, this material was compared with local materials used for the construction of buildings such as BTC, adobe and BLT mixed with binders. The results showed that foamed concrete is a material that has good thermal and mechanical properties compared to local materials mixed with binders. The foamed concrete having acceptable thermo-mechanical properties was that having a density of 930 kg/m<sup>3</sup>. It has a thermal resistance of 0.4 m<sup>2</sup>·K/W for a thickness of 20 cm. The foamed concrete having acceptable thermo-mechanical properties was that having a density of 930 kg/m3</sup>. It has a thermal resistance of 0.4 m2</sup>·K/W for a thickness of 20 cm. For sunshine on a daily cycle equal to 12 hours, the characteristic thickness achieved by this material is 7.29 cm. It also has a shallow depth of heat diffusion having a lower thickness than other materials. This shows that foamed concrete is a promising material for the construction of buildings.展开更多
Peanut shells from Burkina Faso were characterized using mineralogical, microstructural and chemical methods to perform its possibility to be used as reinforce in adobe bricks. It consists of cellulose (48 wt%), hemic...Peanut shells from Burkina Faso were characterized using mineralogical, microstructural and chemical methods to perform its possibility to be used as reinforce in adobe bricks. It consists of cellulose (48 wt%), hemicellulose (3 wt%) and lignin (28 wt%). The peanut shells were characterized by high porosity and showed water absorption around 198% at 72 hours. Its chemical composition is essentially composed of silica, iron oxides, alumina and calcium oxide. Its microstructure showed that the peanut shells were a compilation of microfibers with high porous of borders. In watery solution, the peanut shells released polyphenols. Thermal conductivity of peanut at 25 °C was <span>0.155 ± 0.021 W/mK. The physico-chemical characteristics of peanut shells were similar to those found with agricultural by-products used in adobe reinforce.</span>展开更多
文摘Miners in Australia frequently perform physically demanding work under high ambient temperatures and humidity, often whilst wearing personal protective equipment, leading to heat-related illnesses. This study investigated effects of replacing 100% and 50% sweat losses with 5% carbohydrate liquid or ice-slurry solution on core temperature during simulated mining conditions. Five randomized treadmill trials were performed with: no fluid replacement (NF), 100% (100 ICE) and 50% (50 ICE) sweat loss replaced with ice-slurry (~-1°C) solution and 100% (100 LIQ) and 50% (50 LIQ) sweat loss replaced with liquid (~+4°C) solution. Time to exhaustion was longer in 100 ICE followed by 100 LIQ, 50 ICE, 50 LIQ and NF. Change in rectal temperature was least in 100 ICE followed by 100 LIQ, 50 ICE, 50 LIQ and NF. Ingestion of ice-slurry resulted in longer time to exhaustion and slower rates of change in rectal temperature. It is recommended that ice-slurry drinks be provided to personnel to lower heat strain during hot working conditions.
文摘A numerical approach to heat and mass transfer in a large water reservoir is presented. This water reservoir is likened to a parallelepiped reservoir whose vertical and lower walls are adiabatic and impermeable. The equations that govern natural convection in water are solved by the finite volume method and Thomas’salgorithm. The adequacy between the velocity and pressure fields is ensured by the SIMPLE algorithm. We are going to evaluate the water losses by evaporation from three dams in the Nakanbé basin in Burkina Faso for a period of thirty years, that is to say from January 1, 1991, to March 15, 2020. The three dams have a rate of evaporation greater than 40% of the volume of water stored. Indeed the rate of evaporation in each dam increases with the water filling rate in the reservoir: we have observed the following results for each dam in the Nakanbé basin;for the date of 02/27/1988 to 03/13/2020., the Loumbila dam received a total volume of stored water of 22.02 Mm<sup>3</sup> and 10.57 Mm<sup>3</sup> as the total volume of water evaporated at the same date. At the Ouaga dam (2 + 3), it stored a water volume of 4.06 Mm<sup>3</sup> and evaporated 2.03 Mm<sup>3</sup> of its storage volume from 01/01/1988 to 05/07/2016. Finally, with regard to the Bagré dam, it stored 745.16 Mm<sup>3</sup> of water and 365.13 Mm<sup>3</sup> as the volume of water evaporated from 01/01/1993 to 03/31/2020.
文摘This study focuses on the use of heavy fuel oil in construction material in Burkina Faso. Its mixture with silty or clayey soil is used as a coating to reinforce the walls of raw earth constructions which are very sensitive to water. The interest of this study is to determine erodibility, water content, while highlighting the influence of the porosity accessible by water on thermal diffusion in construction material containing heavy fuel oil. The heavy fuel oil was mixed with a silty-clayey soil, in different proportions, and water to make bricks samples on which tests were carried out. At the end of the experimental tests, it appears that the water content increases gradually, but not significantly with the addition of heavy fuel oil, which causes a slight increase in the speed of heat propagation through the material with reduced porosity, particularly those containing higher quantities of heavy fuel oil. Conversely, we note a good performance of heavy fuel oil in terms of water resistance properties such as porosity accessible by water and erodibility. This allows us to conclude that the mixture of heavy fuel oil and silty-clayey soil used as a coating material could greatly reduce water infiltration into the walls of housing constructions with raw earthen materials.
文摘Knowledge of thermodynamic properties as well as parameters such as energy density and power flow isimportant for modeling thermal plasmas of fluoroalkylamine-air mixtures. In this paper, these thermodynamic properties of fluoroalkylamine-air mixture plasmas are calculated in a temperature range of 500 K to 20,000 K at atmospheric pressure and local thermodynamic equilibrium (LTE). The Gibbs free energy minimization method is used to determine the chemical equilibrium compositions of the plasmas that are needed to calculate the thermodynamic properties. These thermodynamic properties are then used to calculate the energy density and power flow of these plasmas. The variation of the energy density is related to the variations of the density and mass enthalpy. We notice that, this energy density increases with the percentage of air in the mixture for temperatures higher than 7000 K. The power flow, which depends also on density, enthalpy mass and sound speed, increases with the percentage of air in the same temperature range. Energy density and power flow results show that increasing air percentage in the mixture can be more interesting for damaging gaseous chemical species such as CF<sub>2</sub>, CO, HCN, and HF appearing at low temperatures with high concentrations.
文摘Living in a habitat with comfort is requested by all. Cinder block bricks have poor thermal properties, leading people to use fan heaters and air conditioners to regain comfort. To overcome this problem of thermal discomfort in buildings, we used lightweight concrete such as foamed concrete which is a material that has improved thermal properties for thermal comfort. In addition, this material was compared with local materials used for the construction of buildings such as BTC, adobe and BLT mixed with binders. The results showed that foamed concrete is a material that has good thermal and mechanical properties compared to local materials mixed with binders. The foamed concrete having acceptable thermo-mechanical properties was that having a density of 930 kg/m<sup>3</sup>. It has a thermal resistance of 0.4 m<sup>2</sup>·K/W for a thickness of 20 cm. The foamed concrete having acceptable thermo-mechanical properties was that having a density of 930 kg/m3</sup>. It has a thermal resistance of 0.4 m2</sup>·K/W for a thickness of 20 cm. For sunshine on a daily cycle equal to 12 hours, the characteristic thickness achieved by this material is 7.29 cm. It also has a shallow depth of heat diffusion having a lower thickness than other materials. This shows that foamed concrete is a promising material for the construction of buildings.
文摘Peanut shells from Burkina Faso were characterized using mineralogical, microstructural and chemical methods to perform its possibility to be used as reinforce in adobe bricks. It consists of cellulose (48 wt%), hemicellulose (3 wt%) and lignin (28 wt%). The peanut shells were characterized by high porosity and showed water absorption around 198% at 72 hours. Its chemical composition is essentially composed of silica, iron oxides, alumina and calcium oxide. Its microstructure showed that the peanut shells were a compilation of microfibers with high porous of borders. In watery solution, the peanut shells released polyphenols. Thermal conductivity of peanut at 25 °C was <span>0.155 ± 0.021 W/mK. The physico-chemical characteristics of peanut shells were similar to those found with agricultural by-products used in adobe reinforce.</span>
