Countries in Middle East and North Africa (MENA region) are considered as arid and semi-arid areas that are suffering from water scarcity. They are expected to have more water shortages problem due to climatic change....Countries in Middle East and North Africa (MENA region) are considered as arid and semi-arid areas that are suffering from water scarcity. They are expected to have more water shortages problem due to climatic change. Iraq is located in the Middle East covering an area of 433,970 square kilometers populated by 31 million inhabitants. One of the solutions suggested to overcome water scarcity is Rainwater Harvesting (RWH). In this study Macro rainwater harvesting technique had been tested for future rainfall data that were predicted by two emission scenarios of climatic change (A2 and B2) for the period 2020-2099 at Sulaimaniyah Governorate north east of Iraq. Future volumes of total runoff that might be harvested for different conditions of maximum, average, and minimum future rainfall seasons under both scenarios (A2 and B2) were calculated. The results indicate that the volumes of average harvested runoff will be reduced when average rainfall seasons are considered due to the effect of climatic change on future rainfall. The reduction reached 10.82 % and 43.0% when scenarios A2 and B2 are considered respectively.展开更多
The hydrodynamic efficiency of the vertical porous structures is investigated under regular waves by use of physical models. The hydrodynamic efficiency of the breakwater is presented in terms of the wave transmission...The hydrodynamic efficiency of the vertical porous structures is investigated under regular waves by use of physical models. The hydrodynamic efficiency of the breakwater is presented in terms of the wave transmission （kt）, reflection （kr） and energy dissipation （ka） coefficients. Different wave and structural parameters affecting the breakwater efficiency are tested. It is found that, the transmission coefficient （kt） decreases with the increase of the relative water depth （h/L）, the wave steepness （Hi^L）, the relative breakwater widths （B/L, B/h）, the relative breakwater height （D/h）, and the breakwater porosity （n）. The reflection coefficient （kr） takes the opposite trend of kt when D/h=l.25 and it decreases with the increasing h/L, HJL and B/L when D/h〈1.0. The dissipation coefficient （kd） increases with the increasing h/L, HilL and B/L when D/h〈_l.O and it decreases when D/h=l.25. In which, it is possible to achieve values ofkt smaller than 0.3, k~ larger than 0.5, and kd larger than 0.6 when D/h=1.25, B/h=0.6, h/L〉0.22, B/L〉O. 13, and H/L 〉0.04. Empirical equations are developed for the estimation of the transmission and reflection coefficients. The results of these equations are compared with other experimental and theoretical results and a reasonable agreement is obtained.展开更多
提出了适用于铁路隧道的QRA方法论,基于事件树方法对各种场景进行组合,然后采用蒙特卡罗方法(MCS Monte Carlo Simulation)进行分析,该方法能够有效地量化铁路隧道中可能发生的伤亡风险,可以从安全角度评估和比较候选基础设施类型或解...提出了适用于铁路隧道的QRA方法论,基于事件树方法对各种场景进行组合,然后采用蒙特卡罗方法(MCS Monte Carlo Simulation)进行分析,该方法能够有效地量化铁路隧道中可能发生的伤亡风险,可以从安全角度评估和比较候选基础设施类型或解决方案,以便选择最终实施的隧道系统。展开更多
Some concepts related to sediment transport in rivers with overbank flow are described.Following a description of the physical processes that are involved when a river inundates its floodplains,some simple com- putati...Some concepts related to sediment transport in rivers with overbank flow are described.Following a description of the physical processes that are involved when a river inundates its floodplains,some simple com- putational methods are presented which permit the depth-averaged velocity and boundary shear stress to be pre- dicted within a cross section of variable,but prismatic shape.The methoda account for the strong transverse shear in velocity that occurs when the stage is just above bankfull,as well as ...展开更多
Numerous gravel-bed rivers are affected by unceasing degradation problems,mostly caused or in- creased by technical measures upstream.In Germany removing the bank fixations is regarded as a concept to dissolve the pro...Numerous gravel-bed rivers are affected by unceasing degradation problems,mostly caused or in- creased by technical measures upstream.In Germany removing the bank fixations is regarded as a concept to dissolve the problem.By allowing lateral erosion and in consequence river widening the bed load transport ca- pacity will be decreased.Additionally the eroded bank material will serve as additional sediment influx. Nevertheless in some cases additional measures are required for a sustainable stabilization o...展开更多
The k-Ε turbulence model is used to establish a mathematical model of a vertical round jet with negative buoyancy in a static homogeneous ambient. The hybrid finite analytic method, with a non-uniform staggered grid,...The k-Ε turbulence model is used to establish a mathematical model of a vertical round jet with negative buoyancy in a static homogeneous ambient. The hybrid finite analytic method, with a non-uniform staggered grid, is used to calculate the whole flow field. The variations of centerline velocity, density and turbulent kinetic energy along the axial line for a given exit densimetric Froude number are found to converge to single curves under the unified scaling law derived by Chen and Rodi. The profiles of mean velocities, mean density difference and the half-width of negative buoyant jets for velocity and density are given. The calculation confirmed that the maximum height of rise is proportional to M03/4 B0-1/2, where M0 and B0 are the momentum flux and the buoyancy flux at the source, respectively.展开更多
The algorithm of the Hybrid Finite Analytic Method (HFAM) was used to simulate the fully developed turbulent flows in non-circular ducts and open channels. The turbulent flow fields in a square duct and a rectangular ...The algorithm of the Hybrid Finite Analytic Method (HFAM) was used to simulate the fully developed turbulent flows in non-circular ducts and open channels. The turbulent flow fields in a square duct and a rectangular open channels were calculated by the Naot and Rodi's model, and that in a compound channel was calculated by Speaizle's non-linear eddy-viscosity model with this algorithm. The results show that the HFAM is suitable for calculating these complicated turbulent flows.展开更多
文摘Countries in Middle East and North Africa (MENA region) are considered as arid and semi-arid areas that are suffering from water scarcity. They are expected to have more water shortages problem due to climatic change. Iraq is located in the Middle East covering an area of 433,970 square kilometers populated by 31 million inhabitants. One of the solutions suggested to overcome water scarcity is Rainwater Harvesting (RWH). In this study Macro rainwater harvesting technique had been tested for future rainfall data that were predicted by two emission scenarios of climatic change (A2 and B2) for the period 2020-2099 at Sulaimaniyah Governorate north east of Iraq. Future volumes of total runoff that might be harvested for different conditions of maximum, average, and minimum future rainfall seasons under both scenarios (A2 and B2) were calculated. The results indicate that the volumes of average harvested runoff will be reduced when average rainfall seasons are considered due to the effect of climatic change on future rainfall. The reduction reached 10.82 % and 43.0% when scenarios A2 and B2 are considered respectively.
文摘The hydrodynamic efficiency of the vertical porous structures is investigated under regular waves by use of physical models. The hydrodynamic efficiency of the breakwater is presented in terms of the wave transmission （kt）, reflection （kr） and energy dissipation （ka） coefficients. Different wave and structural parameters affecting the breakwater efficiency are tested. It is found that, the transmission coefficient （kt） decreases with the increase of the relative water depth （h/L）, the wave steepness （Hi^L）, the relative breakwater widths （B/L, B/h）, the relative breakwater height （D/h）, and the breakwater porosity （n）. The reflection coefficient （kr） takes the opposite trend of kt when D/h=l.25 and it decreases with the increasing h/L, HJL and B/L when D/h〈1.0. The dissipation coefficient （kd） increases with the increasing h/L, HilL and B/L when D/h〈_l.O and it decreases when D/h=l.25. In which, it is possible to achieve values ofkt smaller than 0.3, k~ larger than 0.5, and kd larger than 0.6 when D/h=1.25, B/h=0.6, h/L〉0.22, B/L〉O. 13, and H/L 〉0.04. Empirical equations are developed for the estimation of the transmission and reflection coefficients. The results of these equations are compared with other experimental and theoretical results and a reasonable agreement is obtained.
文摘Some concepts related to sediment transport in rivers with overbank flow are described.Following a description of the physical processes that are involved when a river inundates its floodplains,some simple com- putational methods are presented which permit the depth-averaged velocity and boundary shear stress to be pre- dicted within a cross section of variable,but prismatic shape.The methoda account for the strong transverse shear in velocity that occurs when the stage is just above bankfull,as well as ...
文摘Numerous gravel-bed rivers are affected by unceasing degradation problems,mostly caused or in- creased by technical measures upstream.In Germany removing the bank fixations is regarded as a concept to dissolve the problem.By allowing lateral erosion and in consequence river widening the bed load transport ca- pacity will be decreased.Additionally the eroded bank material will serve as additional sediment influx. Nevertheless in some cases additional measures are required for a sustainable stabilization o...
文摘The k-Ε turbulence model is used to establish a mathematical model of a vertical round jet with negative buoyancy in a static homogeneous ambient. The hybrid finite analytic method, with a non-uniform staggered grid, is used to calculate the whole flow field. The variations of centerline velocity, density and turbulent kinetic energy along the axial line for a given exit densimetric Froude number are found to converge to single curves under the unified scaling law derived by Chen and Rodi. The profiles of mean velocities, mean density difference and the half-width of negative buoyant jets for velocity and density are given. The calculation confirmed that the maximum height of rise is proportional to M03/4 B0-1/2, where M0 and B0 are the momentum flux and the buoyancy flux at the source, respectively.
文摘The algorithm of the Hybrid Finite Analytic Method (HFAM) was used to simulate the fully developed turbulent flows in non-circular ducts and open channels. The turbulent flow fields in a square duct and a rectangular open channels were calculated by the Naot and Rodi's model, and that in a compound channel was calculated by Speaizle's non-linear eddy-viscosity model with this algorithm. The results show that the HFAM is suitable for calculating these complicated turbulent flows.
