Complex thin-walled titanium alloy components play a key role in the aircraft,aerospace and marine industries,offering the advantages of reduced weight and increased thermal resistance.The geometrical complexity,dimen...Complex thin-walled titanium alloy components play a key role in the aircraft,aerospace and marine industries,offering the advantages of reduced weight and increased thermal resistance.The geometrical complexity,dimensional accuracy and in-service properties are essential to fulfill the high-performance standards required in new transportation systems,which brings new challenges to titanium alloy forming technologies.Traditional forming processes,such as superplastic forming or hot pressing,cannot meet all demands of modern applications due to their limited properties,low productivity and high cost.This has encouraged industry and research groups to develop novel high-efficiency forming processes.Hot gas pressure forming and hot stamping-quenching technologies have been developed for the manufacture of tubular and panel components,and are believed to be the cut-edge processes guaranteeing dimensional accuracy,microstructure and mechanical properties.This article intends to provide a critical review of high-efficiency titanium alloy forming processes,concentrating on latest investigations of controlling dimensional accuracy,microstructure and properties.The advantages and limitations of individual forming process are comprehensively analyzed,through which,future research trends of high-efficiency forming are identified including trends in process integration,processing window design,full cycle and multi-objective optimization.This review aims to provide a guide for researchers and process designers on the manufacture of thin-walled titanium alloy components whilst achieving high dimensional accuracy and satisfying performance properties with high efficiency and low cost.展开更多
Sheet metal forming,as a typical energy-intensive process,consumes massive energy.Due to the significant difference between sheet metal forming and machining,manufacturers still lack an effective method to monitor and...Sheet metal forming,as a typical energy-intensive process,consumes massive energy.Due to the significant difference between sheet metal forming and machining,manufacturers still lack an effective method to monitor and analyze the energy efficiency in the sheet metal forming workshop.To this end,an energy efficiency monitoring and analysis(EEMA)method,which is supported by Internet of Things(IoT),is proposed.The characteristics in a forming workshop are first analyzed,and then the architecture of the method is expatiated-detailedly.Energy efficiency indicators at machine level,process level,and workshop level are defined,respectively.Finally,a sheet metal forming workshop for the deformation of panels of forklift was investigated to validate the effectiveness and benefits of the proposed method.With the application of the IoT-enabled method,various energy-saving decisions can be made by the management of the enterprises for energy efficiency improvement and energy consumption reduction(EEIECR)in the sheet metal forming workshop.展开更多
This paper investigates the empirical validity of the Weak Form Efficient Market Hypothesis for American, European and Asian stock markets. Random Walk Hypothesis is used to prove weak form efficiency in American, Eur...This paper investigates the empirical validity of the Weak Form Efficient Market Hypothesis for American, European and Asian stock markets. Random Walk Hypothesis is used to prove weak form efficiency in American, European and Asian stock indices. ADF and PP Unit Root Tests have been used to test unit root in time series of daily data of American, European and Asian stock indices. Results show that sample of stock markets are weak-form efficient in terms of the Random Walk Hypothesis.展开更多
The authors of this article are interested in characterization of efficient solutions for special classes of problems. These classes consider semi-strong E-convexity of involved functions. Sufficient and necessary con...The authors of this article are interested in characterization of efficient solutions for special classes of problems. These classes consider semi-strong E-convexity of involved functions. Sufficient and necessary conditions for a feasible solution to be an efficient or properly efficient solution are obtained.展开更多
Through concluding landscape form and its development process,the paper analyzed the value of landscape form and proposed that the study on landscape form should be conducted from the perspective of final cause,effici...Through concluding landscape form and its development process,the paper analyzed the value of landscape form and proposed that the study on landscape form should be conducted from the perspective of final cause,efficient cause and material cause.Finally,it discussed the fashion trend of modern landscape design and put forward the tendency and strategies of correction of landscape form.展开更多
基金This work was financially supported by the Program of National Natural Science Foundation of China(Nos.U1937204 and 51905124)China Postdoctoral Science Foundation(2019M661278).
文摘Complex thin-walled titanium alloy components play a key role in the aircraft,aerospace and marine industries,offering the advantages of reduced weight and increased thermal resistance.The geometrical complexity,dimensional accuracy and in-service properties are essential to fulfill the high-performance standards required in new transportation systems,which brings new challenges to titanium alloy forming technologies.Traditional forming processes,such as superplastic forming or hot pressing,cannot meet all demands of modern applications due to their limited properties,low productivity and high cost.This has encouraged industry and research groups to develop novel high-efficiency forming processes.Hot gas pressure forming and hot stamping-quenching technologies have been developed for the manufacture of tubular and panel components,and are believed to be the cut-edge processes guaranteeing dimensional accuracy,microstructure and mechanical properties.This article intends to provide a critical review of high-efficiency titanium alloy forming processes,concentrating on latest investigations of controlling dimensional accuracy,microstructure and properties.The advantages and limitations of individual forming process are comprehensively analyzed,through which,future research trends of high-efficiency forming are identified including trends in process integration,processing window design,full cycle and multi-objective optimization.This review aims to provide a guide for researchers and process designers on the manufacture of thin-walled titanium alloy components whilst achieving high dimensional accuracy and satisfying performance properties with high efficiency and low cost.
基金Projects(U20A20295,52005146)supported by the National Natural Science Foundation of ChinaProject(PA2019GDQT 0024)supported by Fundamental Research Funds for the Central Universities,China。
文摘Sheet metal forming,as a typical energy-intensive process,consumes massive energy.Due to the significant difference between sheet metal forming and machining,manufacturers still lack an effective method to monitor and analyze the energy efficiency in the sheet metal forming workshop.To this end,an energy efficiency monitoring and analysis(EEMA)method,which is supported by Internet of Things(IoT),is proposed.The characteristics in a forming workshop are first analyzed,and then the architecture of the method is expatiated-detailedly.Energy efficiency indicators at machine level,process level,and workshop level are defined,respectively.Finally,a sheet metal forming workshop for the deformation of panels of forklift was investigated to validate the effectiveness and benefits of the proposed method.With the application of the IoT-enabled method,various energy-saving decisions can be made by the management of the enterprises for energy efficiency improvement and energy consumption reduction(EEIECR)in the sheet metal forming workshop.
文摘This paper investigates the empirical validity of the Weak Form Efficient Market Hypothesis for American, European and Asian stock markets. Random Walk Hypothesis is used to prove weak form efficiency in American, European and Asian stock indices. ADF and PP Unit Root Tests have been used to test unit root in time series of daily data of American, European and Asian stock indices. Results show that sample of stock markets are weak-form efficient in terms of the Random Walk Hypothesis.
文摘The authors of this article are interested in characterization of efficient solutions for special classes of problems. These classes consider semi-strong E-convexity of involved functions. Sufficient and necessary conditions for a feasible solution to be an efficient or properly efficient solution are obtained.
文摘Through concluding landscape form and its development process,the paper analyzed the value of landscape form and proposed that the study on landscape form should be conducted from the perspective of final cause,efficient cause and material cause.Finally,it discussed the fashion trend of modern landscape design and put forward the tendency and strategies of correction of landscape form.
