Bernoulli’s principle states that an increase in the speed of a fluid is directly related to the decrease in the fluid’s potential energy. Many engineers refer to Bernoulli’s equations to calculate the pressure of ...Bernoulli’s principle states that an increase in the speed of a fluid is directly related to the decrease in the fluid’s potential energy. Many engineers refer to Bernoulli’s equations to calculate the pressure of a system. The objective of this undergraduate research endeavor is to illustrate the accuracy of his theory and apply it to one of the most common fluid systems in residential homes, a pump pipe system. The research team consisted of a diverse body of undergraduate students with different educational and cultural backgrounds. Completing this objective further improved every member’s problem solving, communication skills, self-confidence, ability to rationalize and transcribe physical phenomena as well visually express them to rest of the engineering community. The findings of this research showed a relationship between various parameters such as, pipe length, pipe roughness, diameter, and specific gravity of the liquid.展开更多
The objective of reliability-based design optimization(RBDO)is to minimize the optimization objective while satisfying the corresponding reliability requirements.However,the nested loop characteristic reduces the effi...The objective of reliability-based design optimization(RBDO)is to minimize the optimization objective while satisfying the corresponding reliability requirements.However,the nested loop characteristic reduces the efficiency of RBDO algorithm,which hinders their application to high-dimensional engineering problems.To address these issues,this paper proposes an efficient decoupled RBDO method combining high dimensional model representation(HDMR)and the weight-point estimation method(WPEM).First,we decouple the RBDO model using HDMR and WPEM.Second,Lagrange interpolation is used to approximate a univariate function.Finally,based on the results of the first two steps,the original nested loop reliability optimization model is completely transformed into a deterministic design optimization model that can be solved by a series of mature constrained optimization methods without any additional calculations.Two numerical examples of a planar 10-bar structure and an aviation hydraulic piping system with 28 design variables are analyzed to illustrate the performance and practicability of the proposed method.展开更多
Water shortage is one of the major water related problems for many cities in the world.The planning for utilization of reclaimed water has been or would be drafted in these cities.For using the reclaimed water soundly...Water shortage is one of the major water related problems for many cities in the world.The planning for utilization of reclaimed water has been or would be drafted in these cities.For using the reclaimed water soundly,Beijing planned to build a large scale reclaimed water pipe networks with multi-sources.In order to support the plan,the integrated hydraulic model of planning pipe network was developed based on EPANET supported by geographic information system(GIS).The complicated pipe network was divided into four weak conjunction subzones according to the distribution of reclaimed water plants and the elevation.It could provide a better solution for the problem of overhigh pressure in several regions of the network.Through the scenarios analy-sis in different subzones,some of the initial diameter of pipes in the network was adjusted.At last the pipe network planning scheme of reclaimed water was proposed.The proposed planning scheme could reach the balances between reclaimed water requirements and reclaimed water supplies,and provided a scientific basis for the reclaimed water utilization in Beijing.Now the scheme had been adopted by Beijing municipal government.展开更多
In the paper, the hydraulic architecture parameters of Pinus tabulaeformis seedlings (4 years old)were measured by improved flushing method under normal water condition in the green house and the basictheory of hydrau...In the paper, the hydraulic architecture parameters of Pinus tabulaeformis seedlings (4 years old)were measured by improved flushing method under normal water condition in the green house and the basictheory of hydraulic architecture is used to discuss the rationality of the pipe model. The results of theexperiment and simulation show that the differences of hydraulic conductivity, specific conductivity and leafspecific conductivity is great in different stems and branches of Pinus tabulaeformis seedlings. The hydraulicconductivity of non-constriction area is higher than that of constriction area. The devotion of functionalxylem of stem to unit leaf growth is not a constant, namely, the Huber value is diverse. Even though the pipemodel has been accepted in some areas, its precondition is not perfect, and it is helpless in correctlyunderstanding the essence of water transport in seedlings from the prospective of water physiology.展开更多
机场跑道排水是保障飞机运行安全和飞机品质的关键因素之一,良好的排水系统能够有效排除雨水,减少积水和滞留水的影响。为了探讨现有机场跑道排水系统排水能力,以及降雨与排水系统的演化过程,以中国南方某机场跑道为研究对象,将丹麦水...机场跑道排水是保障飞机运行安全和飞机品质的关键因素之一,良好的排水系统能够有效排除雨水,减少积水和滞留水的影响。为了探讨现有机场跑道排水系统排水能力,以及降雨与排水系统的演化过程,以中国南方某机场跑道为研究对象,将丹麦水利研究所开发的集成的水文水质量模型(Danish Hydraulic Institute model integrated computing,DHI MIKE)模型应用于机场跑道,构建耦合雨洪模型。根据研究区域的降雨特性以及现有排水系统,设计4种不同重现期的降雨情景,从管道充满度、地表淹没结果、跑道积水演化过程3个方面进行模拟分析。结果表明:管道满管数量与降雨强度呈正比关系,不同重现期下研究区域水深的空间分布大体呈一致状态,集中在集水浅沟周围。重现期越大,积水深度越高;出现积水时间和跑道关闭时间提前。跑道排水能力基本能够满足5年一遇的降雨标准。展开更多
文摘Bernoulli’s principle states that an increase in the speed of a fluid is directly related to the decrease in the fluid’s potential energy. Many engineers refer to Bernoulli’s equations to calculate the pressure of a system. The objective of this undergraduate research endeavor is to illustrate the accuracy of his theory and apply it to one of the most common fluid systems in residential homes, a pump pipe system. The research team consisted of a diverse body of undergraduate students with different educational and cultural backgrounds. Completing this objective further improved every member’s problem solving, communication skills, self-confidence, ability to rationalize and transcribe physical phenomena as well visually express them to rest of the engineering community. The findings of this research showed a relationship between various parameters such as, pipe length, pipe roughness, diameter, and specific gravity of the liquid.
基金supported by the Innovation Fund Project of the Gansu Education Department(Grant No.2021B-099).
文摘The objective of reliability-based design optimization(RBDO)is to minimize the optimization objective while satisfying the corresponding reliability requirements.However,the nested loop characteristic reduces the efficiency of RBDO algorithm,which hinders their application to high-dimensional engineering problems.To address these issues,this paper proposes an efficient decoupled RBDO method combining high dimensional model representation(HDMR)and the weight-point estimation method(WPEM).First,we decouple the RBDO model using HDMR and WPEM.Second,Lagrange interpolation is used to approximate a univariate function.Finally,based on the results of the first two steps,the original nested loop reliability optimization model is completely transformed into a deterministic design optimization model that can be solved by a series of mature constrained optimization methods without any additional calculations.Two numerical examples of a planar 10-bar structure and an aviation hydraulic piping system with 28 design variables are analyzed to illustrate the performance and practicability of the proposed method.
基金This work was supported by the Beijing Municipal Planning Committee.The authors thank Mr.Wang Jun and Mr.Liu Jing for their helps.
文摘Water shortage is one of the major water related problems for many cities in the world.The planning for utilization of reclaimed water has been or would be drafted in these cities.For using the reclaimed water soundly,Beijing planned to build a large scale reclaimed water pipe networks with multi-sources.In order to support the plan,the integrated hydraulic model of planning pipe network was developed based on EPANET supported by geographic information system(GIS).The complicated pipe network was divided into four weak conjunction subzones according to the distribution of reclaimed water plants and the elevation.It could provide a better solution for the problem of overhigh pressure in several regions of the network.Through the scenarios analy-sis in different subzones,some of the initial diameter of pipes in the network was adjusted.At last the pipe network planning scheme of reclaimed water was proposed.The proposed planning scheme could reach the balances between reclaimed water requirements and reclaimed water supplies,and provided a scientific basis for the reclaimed water utilization in Beijing.Now the scheme had been adopted by Beijing municipal government.
文摘In the paper, the hydraulic architecture parameters of Pinus tabulaeformis seedlings (4 years old)were measured by improved flushing method under normal water condition in the green house and the basictheory of hydraulic architecture is used to discuss the rationality of the pipe model. The results of theexperiment and simulation show that the differences of hydraulic conductivity, specific conductivity and leafspecific conductivity is great in different stems and branches of Pinus tabulaeformis seedlings. The hydraulicconductivity of non-constriction area is higher than that of constriction area. The devotion of functionalxylem of stem to unit leaf growth is not a constant, namely, the Huber value is diverse. Even though the pipemodel has been accepted in some areas, its precondition is not perfect, and it is helpless in correctlyunderstanding the essence of water transport in seedlings from the prospective of water physiology.
文摘机场跑道排水是保障飞机运行安全和飞机品质的关键因素之一,良好的排水系统能够有效排除雨水,减少积水和滞留水的影响。为了探讨现有机场跑道排水系统排水能力,以及降雨与排水系统的演化过程,以中国南方某机场跑道为研究对象,将丹麦水利研究所开发的集成的水文水质量模型(Danish Hydraulic Institute model integrated computing,DHI MIKE)模型应用于机场跑道,构建耦合雨洪模型。根据研究区域的降雨特性以及现有排水系统,设计4种不同重现期的降雨情景,从管道充满度、地表淹没结果、跑道积水演化过程3个方面进行模拟分析。结果表明:管道满管数量与降雨强度呈正比关系,不同重现期下研究区域水深的空间分布大体呈一致状态,集中在集水浅沟周围。重现期越大,积水深度越高;出现积水时间和跑道关闭时间提前。跑道排水能力基本能够满足5年一遇的降雨标准。
