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The in-cylinder airflow motion is an important factor that severely affects combustion efficiency and emissions in diesel engines. It is greatly affected by the inlet port and valve geometries. A diesel engine cylinder with a helical–spiral inlet port is used in this study. An ordinary inlet valve and shrouded inlet valve having different shroud and orientation angles are used to study the shroud effect on the swirl and tumble motion inside the engine cylinder. Four shroud angles of 90 deg, 120 deg, 150 deg, and 180 deg are used. With each shroud angle, four orientation angles of 0 deg, 30 deg, 60 deg, and 90 deg are also used. Three-dimensional simulation model using the shear stress transport (SST) k–ω model is used for simulating air flow through the inlet port, inlet valve, and engine cylinder during both the intake and compression strokes. The results showed that increasing the valve shroud angle increases the swirl, and the maximum increase occurs at a valve shroud angle of 180 deg and orientation angle of 0 deg with a value of 80% with respect to the ordinary valve. But it decreases the volumetric efficiency, and the maximum decrement occurs at valve shroud of 180 deg and orientation angle of 90 deg with a value of 5.98%. Variations of the shroud and orientation angles have very small effect on the tumble inside the engine cylinder.

The in-cylinder airflow motion is an important factor that severely affects combustion efficiency and emissions in diesel engines. It is greatly affected by the inlet port and valve geometries. A diesel engine cylinder with a helical–spiral inlet port is used in this study. An ordinary inlet valve and shrouded inlet valve having different shroud and orientation angles are used to study the shroud effect on the swirl and tumble motion inside the engine cylinder. Four shroud angles of 90 deg, 120 deg, 150 deg, and 180 deg are used. With each shroud angle, four orientation angles of 0 deg, 30 deg, 60 deg, and 90 deg are also used. Three-dimensional simulation model using the shear stress transport (SST) k–ω model is used for simulating air flow through the inlet port, inlet valve, and engine cylinder during both the intake and compression strokes. The results showed that increasing the valve shroud angle increases the swirl, and the maximum increase occurs at a valve shroud angle of 180 deg and orientation angle of 0 deg with a value of 80% with respect to the ordinary valve. But it decreases the volumetric efficiency, and the maximum decrement occurs at valve shroud of 180 deg and orientation angle of 90 deg with a value of 5.98%. Variations of the shroud and orientation angles have very small effect on the tumble inside the engine cylinder.

Mining industry is generally classified as the most hazardous industrial sector. Mining activities usually emit physical and chemical hazards in the workplaces and impose negative effects on the workers' health. Sukari Gold Mine (SGM) is located in the south of Eastern Desert in Egypt and is considered as the largest and modernized gold mine in the country. Occupational exposure and health risk assessment were evaluated in SGM by measuring the hazardous substances in different workplaces of the project. Noise, Particulate Matters (PM10), harmful gases such as carbon monoxide (CO), Sulfur dioxide (SO2), nitrogen dioxide (NO2), Hydrogen cyanide (HCN), and ammonia (NH3) were measured in workplaces and ambient environment. Maximum noise levels were 112 dBA and 103.5 dBA in the two power generators. Values of PM10 in the most working sites were less than the permissible levels (3 mg/m3) except in underground access, which recorded 4.9 mg/ m3. Measurements of chemical gases in the workplaces showed that most of the concentrations are less than the permissible limits except hydrogen cyanide. HCN recorded high levels in Carbon In Leach Tanks with a value of 10 ppm. Risk assessment of occupational health hazards of the SGM was applied in this study using Hazard Index and a simple modified model. The two methods enhanced each other and gave same results that two workplaces have High Risk, five cases have Moderate Risk and the rest places are Low Risk on the workers' Health. The study concluded that the modern mining and extraction methods applied in SGM have reduced the severity of occupational exposure to physical and chemical hazards in workplaces.

Mining industry is generally classified as the most hazardous industrial sector. Mining activities usually emit physical and chemical hazards in the workplaces and impose negative effects on the workers' health. Sukari Gold Mine (SGM) is located in the south of Eastern Desert in Egypt and is considered as the largest and modernized gold mine in the country. Occupational exposure and health risk assessment were evaluated in SGM by measuring the hazardous substances in different workplaces of the project. Noise, Particulate Matters (PM10), harmful gases such as carbon monoxide (CO), Sulfur dioxide (SO2), nitrogen dioxide (NO2), Hydrogen cyanide (HCN), and ammonia (NH3) were measured in workplaces and ambient environment. Maximum noise levels were 112 dBA and 103.5 dBA in the two power generators. Values of PM10 in the most working sites were less than the permissible levels (3 mg/m3) except in underground access, which recorded 4.9 mg/ m3. Measurements of chemical gases in the workplaces showed that most of the concentrations are less than the permissible limits except hydrogen cyanide. HCN recorded high levels in Carbon In Leach Tanks with a value of 10 ppm. Risk assessment of occupational health hazards of the SGM was applied in this study using Hazard Index and a simple modified model. The two methods enhanced each other and gave same results that two workplaces have High Risk, five cases have Moderate Risk and the rest places are Low Risk on the workers' Health. The study concluded that the modern mining and extraction methods applied in SGM have reduced the severity of occupational exposure to physical and chemical hazards in workplaces.

Mining industry is generally classified as the most hazardous industrial sector. Mining activities usually emit physical and chemical hazards in the workplaces and impose negative effects on the workers' health. Sukari Gold Mine (SGM) is located in the south of Eastern Desert in Egypt and is considered as the largest and modernized gold mine in the country. Occupational exposure and health risk assessment were evaluated in SGM by measuring the hazardous substances in different workplaces of the project. Noise, Particulate Matters (PM10), harmful gases such as carbon monoxide (CO), Sulfur dioxide (SO2), nitrogen dioxide (NO2), Hydrogen cyanide (HCN), and ammonia (NH3) were measured in workplaces and ambient environment. Maximum noise levels were 112 dBA and 103.5 dBA in the two power generators. Values of PM10 in the most working sites were less than the permissible levels (3 mg/m3) except in underground access, which recorded 4.9 mg/ m3. Measurements of chemical gases in the workplaces showed that most of the concentrations are less than the permissible limits except hydrogen cyanide. HCN recorded high levels in Carbon In Leach Tanks with a value of 10 ppm. Risk assessment of occupational health hazards of the SGM was applied in this study using Hazard Index and a simple modified model. The two methods enhanced each other and gave same results that two workplaces have High Risk, five cases have Moderate Risk and the rest places are Low Risk on the workers' Health. The study concluded that the modern mining and extraction methods applied in SGM have reduced the severity of occupational exposure to physical and chemical hazards in workplaces.

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