When designing large-sized complex machinery products, the design focus is always on the overall per- formance; however, there exist no design theory and method based on performance driven. In view of the defi- ciency...When designing large-sized complex machinery products, the design focus is always on the overall per- formance; however, there exist no design theory and method based on performance driven. In view of the defi- ciency of the existing design theory, according to the performance features of complex mechanical products, the performance indices are introduced into the traditional design theory of ＂Requirement-Function-Structure＂ to construct a new five-domain design theory of ＂Client Requirement-Function-Performance-Structure-Design Parameter＂. To support design practice based on this new theory, a product data model is established by using per- formance indices and the mapping relationship between them and the other four domains. When the product data model is applied to high-speed train design and combining the existing research result and relevant standards, the corresponding data model and its structure involving five domains of high-speed trains are established, which can provide technical support for studying the relationships between typical performance indices and design parame- ters and the fast achievement of a high-speed train scheme design. The five domains provide a reference for the design specification and evaluation criteria of high speed train and a new idea for the train＇s parameter design.展开更多
Calcium,as the most abundant mineral in human body,is involved in many physiological and pathological processes.Here,we reviewed the key mechanisms of calcium homeostasis,including calcium sensing receptor regulation,...Calcium,as the most abundant mineral in human body,is involved in many physiological and pathological processes.Here,we reviewed the key mechanisms of calcium homeostasis,including calcium sensing receptor regulation,intestinal calcium absorption,renal calcium reabsorption and bone calcium resorption.We further discussed the roles of dietary calcium and vitamin D in diseases associated with dysfunctional regulation of calcium.However,the over-dosed consumption of calcium could increase the risks for a series of diseases,such as kidney stone,myocardial infarction and stroke.展开更多
Prediction of critical heat flux(CHF)in annular flow is important for the safety of once-through steam generator and the reactor core under accident conditions.The dryout in annular flow occurs at the point where the ...Prediction of critical heat flux(CHF)in annular flow is important for the safety of once-through steam generator and the reactor core under accident conditions.The dryout in annular flow occurs at the point where the film is depleted due to entrainment,deposition,and evaporation.The film thickness,film mass flow rate along axial distribution,and CHF are calculated in vertical upward round tube on the basis of a separated flow model of annular flow.The theoretical CHF values are higher than those derived from experimental data,with error being within 30%.展开更多
The technology of passive safety is the current trend among safety systems in nuclear power plant. Pas- sive residual heat removal system (PRHRS), a major part of passive safety systems of Chinese advanced PWR, is a n...The technology of passive safety is the current trend among safety systems in nuclear power plant. Pas- sive residual heat removal system (PRHRS), a major part of passive safety systems of Chinese advanced PWR, is a novel design with three-fold natural circulation. On the basis of reasonable physics and mathematics models, MI- TAP-PRHRS code was developed to analyze steady and transient characteristics of the PRHRS. The calculation and analysis show that the code simulates steady characteristics of the PRHRS very well, and it is able to simulate tran- sient characteristics of all startup modes of the PRHRS. However, the quantitative description is poor during the ini- tial stages of the transition process when water hammer occurs.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51275432,51505390)Sichuan Application Foundation Projects(Grant No.2016JY0098)Independent Research Project of TPL(Grant No.TPL1501)
文摘When designing large-sized complex machinery products, the design focus is always on the overall per- formance; however, there exist no design theory and method based on performance driven. In view of the defi- ciency of the existing design theory, according to the performance features of complex mechanical products, the performance indices are introduced into the traditional design theory of ＂Requirement-Function-Structure＂ to construct a new five-domain design theory of ＂Client Requirement-Function-Performance-Structure-Design Parameter＂. To support design practice based on this new theory, a product data model is established by using per- formance indices and the mapping relationship between them and the other four domains. When the product data model is applied to high-speed train design and combining the existing research result and relevant standards, the corresponding data model and its structure involving five domains of high-speed trains are established, which can provide technical support for studying the relationships between typical performance indices and design parame- ters and the fast achievement of a high-speed train scheme design. The five domains provide a reference for the design specification and evaluation criteria of high speed train and a new idea for the train＇s parameter design.
基金the National Natural Science Foundation of China(No.31571228)。
文摘Calcium,as the most abundant mineral in human body,is involved in many physiological and pathological processes.Here,we reviewed the key mechanisms of calcium homeostasis,including calcium sensing receptor regulation,intestinal calcium absorption,renal calcium reabsorption and bone calcium resorption.We further discussed the roles of dietary calcium and vitamin D in diseases associated with dysfunctional regulation of calcium.However,the over-dosed consumption of calcium could increase the risks for a series of diseases,such as kidney stone,myocardial infarction and stroke.
文摘Prediction of critical heat flux(CHF)in annular flow is important for the safety of once-through steam generator and the reactor core under accident conditions.The dryout in annular flow occurs at the point where the film is depleted due to entrainment,deposition,and evaporation.The film thickness,film mass flow rate along axial distribution,and CHF are calculated in vertical upward round tube on the basis of a separated flow model of annular flow.The theoretical CHF values are higher than those derived from experimental data,with error being within 30%.
文摘The technology of passive safety is the current trend among safety systems in nuclear power plant. Pas- sive residual heat removal system (PRHRS), a major part of passive safety systems of Chinese advanced PWR, is a novel design with three-fold natural circulation. On the basis of reasonable physics and mathematics models, MI- TAP-PRHRS code was developed to analyze steady and transient characteristics of the PRHRS. The calculation and analysis show that the code simulates steady characteristics of the PRHRS very well, and it is able to simulate tran- sient characteristics of all startup modes of the PRHRS. However, the quantitative description is poor during the ini- tial stages of the transition process when water hammer occurs.
