5 critical quality characteristics must be controlled in the surface mount and wire-bond process in semiconductor packaging. And these characteristics are correlated with each other. So the principal components analy...5 critical quality characteristics must be controlled in the surface mount and wire-bond process in semiconductor packaging. And these characteristics are correlated with each other. So the principal components analysis（PCA） is used in the analysis of the sample data firstly. And then the process is controlled with hotelling T^2 control chart for the first several principal components which contain sufficient information. Furthermore, a software tool is developed for this kind of problems. And with sample data from a surface mounting device（SMD） process, it is demonstrated that the T^2 control chart with PCA gets the same conclusion as without PCA, but the problem is transformed from high-dimensional one to a lower dimensional one, i.e., from 5 to 2 in this demonstration.展开更多
The Hangzhou Bay（HZB） and Xiangshan Bay（XSB）, in northern Zhejiang Province and connect to the East China Sea（ECS） were considerably affected by the consequence of water quality degradation. In this study, we an...The Hangzhou Bay（HZB） and Xiangshan Bay（XSB）, in northern Zhejiang Province and connect to the East China Sea（ECS） were considerably affected by the consequence of water quality degradation. In this study, we analyzed physical and biogeochemical properties of water quality via multivariate statistical techniques. Hierarchical cluster analysis（HCA） grouped HZB and XSB into two subareas of different pollution sources based on similar physical and biogeochemical properties. Principal component analysis（PCA） identified three latent pollution sources in HZB and XSB respectively and emphasized the importance of terrestrial inputs, coastal industries as well as natural processes in determining the water quality of the two bays. Therefore, proper measurement for the protection of aquatic ecoenvironment in HZB and XSB were of great urgency.展开更多
As a natural product with health benefits,tea powder(TP)is widely used in food processing field.In order to explore sensory evaluation,quality components and antioxidant activities among different types of TP,matcha T...As a natural product with health benefits,tea powder(TP)is widely used in food processing field.In order to explore sensory evaluation,quality components and antioxidant activities among different types of TP,matcha TP,Huangjinya green TP,oolong TP,black TP and Pu-erh TP were used as the research objects.Our results showed that total scores of sensory evaluation of unfermented TPs were higher than those of fermented TPs,whilst the colour of those unfermented TPs was more bright.Furthermore,taste attributes showed that sweetness was conducive to the formation of the taste of black TP,and aftertaste-bitterness was beneficial to matcha and Pu-erh TP.Umami was suggested as a vital contributing factor to the mellow taste of Huangjinya green TP,while sourness and bitterness were not propitious to form the taste quality of tea powder.The non-volatile quality components analysis revealed that tea powders with more fermentation usually contained fewer amino acids and catechins,but glutamate and gamma-aminobutyric acid were higher in black TP than in oolong TP.Theanine,glutamic acid and arginine were the main iconic components affecting the amino acid composition of different types of tea powder in our study.Meanwhile,the contents of ester catechins(ECG,EGC,EGCG)in black TP and Pu-erh TP were significantly lower than those in green TP and oolong TP.In addition,the free radical scavenging ability of unfermented TPs were stronger than that of fermented TPs.Therefore,to maximize the health benefits and sensory attributes of different types of TP,the use of unfermented tea powder is recommended.However,different manufacturing process of tea powder can enrich the taste of tea foods,thus giving people more choices.展开更多
Operations in assembling and joining large size aircraft components are changed to novel digital and flexible ways by digital measurement assisted alignment.Positions and orientations（P＆O）of aligned components are ...Operations in assembling and joining large size aircraft components are changed to novel digital and flexible ways by digital measurement assisted alignment.Positions and orientations（P＆O）of aligned components are critical characters which assure geometrical positions and relationships of those components.Therefore,evaluating the P＆O of a component is considered necessary and critical for ensuring accuracy in aircraft assembly.Uncertainty of position and orientation（U-P＆O）,as a part of the evaluating result of P＆O,needs to be given for ensuring the integrity and credibility of the result;furthermore,U-P＆O is necessary for error tracing and quality evaluating of measurement assisted aircraft assembly.However,current research mainly focuses on the process integration of measurement with assembly,and usually ignores the uncertainty of measured result and its influence on quality evaluation.This paper focuses on the expression,analysis,and application of U-P＆O in measurement assisted alignment.The geometrical and algebraical connotations of U-P＆O are presented.Then,an analytical algorithm for evaluating the multi-dimensional U-P＆O is given,and the effect factors and characteristics of U-P＆O are discussed.Finally,U-P＆O is used to evaluate alignment in aircraft assembly for quality evaluating and improving.Cases are introduced with the methodology.展开更多
In recent years, the increasing application of nonlinear and unbalanced electronic equipment and large single phase loads have made voltage imbalance a serious problem in power distribution systems. A novel approach h...In recent years, the increasing application of nonlinear and unbalanced electronic equipment and large single phase loads have made voltage imbalance a serious problem in power distribution systems. A novel approach has been proposed to eliminate voltage imbalance and disturbances. The main strategy of this scheme is based on series active filter. By improving control circuit toward existing schemes and proposing a new strategy to control the voltage amplitude, simultaneous elimination of voltage imbalance, faults, voltage harmonics and also compensation of voltage drop in transmission lines become possible. Eventually, the voltage on the load side is a perfectly balanced three phase voltage with specific proper amplitude. The proposed scheme has been simulated in a test network and the results show high capability of this scheme for the complete elimination of imbalance without phase shift.展开更多
基金This project is supported by National Natural Science Foundation of China (No.70372062)Hi-Tech Program of Tianjin city,China (No.04310881R).
文摘5 critical quality characteristics must be controlled in the surface mount and wire-bond process in semiconductor packaging. And these characteristics are correlated with each other. So the principal components analysis（PCA） is used in the analysis of the sample data firstly. And then the process is controlled with hotelling T^2 control chart for the first several principal components which contain sufficient information. Furthermore, a software tool is developed for this kind of problems. And with sample data from a surface mounting device（SMD） process, it is demonstrated that the T^2 control chart with PCA gets the same conclusion as without PCA, but the problem is transformed from high-dimensional one to a lower dimensional one, i.e., from 5 to 2 in this demonstration.
基金The National Marine Ecoenvironment Assessment Program of State Oceanic Administration
文摘The Hangzhou Bay（HZB） and Xiangshan Bay（XSB）, in northern Zhejiang Province and connect to the East China Sea（ECS） were considerably affected by the consequence of water quality degradation. In this study, we analyzed physical and biogeochemical properties of water quality via multivariate statistical techniques. Hierarchical cluster analysis（HCA） grouped HZB and XSB into two subareas of different pollution sources based on similar physical and biogeochemical properties. Principal component analysis（PCA） identified three latent pollution sources in HZB and XSB respectively and emphasized the importance of terrestrial inputs, coastal industries as well as natural processes in determining the water quality of the two bays. Therefore, proper measurement for the protection of aquatic ecoenvironment in HZB and XSB were of great urgency.
基金Supported by the Jiangsu Agricultural Science and Technology Independent Innovation Fund(CX(22)2008)Jiangsu Province modern agricultural industrial technology system(JATS[2022]275).
文摘As a natural product with health benefits,tea powder(TP)is widely used in food processing field.In order to explore sensory evaluation,quality components and antioxidant activities among different types of TP,matcha TP,Huangjinya green TP,oolong TP,black TP and Pu-erh TP were used as the research objects.Our results showed that total scores of sensory evaluation of unfermented TPs were higher than those of fermented TPs,whilst the colour of those unfermented TPs was more bright.Furthermore,taste attributes showed that sweetness was conducive to the formation of the taste of black TP,and aftertaste-bitterness was beneficial to matcha and Pu-erh TP.Umami was suggested as a vital contributing factor to the mellow taste of Huangjinya green TP,while sourness and bitterness were not propitious to form the taste quality of tea powder.The non-volatile quality components analysis revealed that tea powders with more fermentation usually contained fewer amino acids and catechins,but glutamate and gamma-aminobutyric acid were higher in black TP than in oolong TP.Theanine,glutamic acid and arginine were the main iconic components affecting the amino acid composition of different types of tea powder in our study.Meanwhile,the contents of ester catechins(ECG,EGC,EGCG)in black TP and Pu-erh TP were significantly lower than those in green TP and oolong TP.In addition,the free radical scavenging ability of unfermented TPs were stronger than that of fermented TPs.Therefore,to maximize the health benefits and sensory attributes of different types of TP,the use of unfermented tea powder is recommended.However,different manufacturing process of tea powder can enrich the taste of tea foods,thus giving people more choices.
基金support of National Natural Science Foundation of China (No.50905010)Fund of National Engineering and Research Center for Commercial Aircraft Manufacturing (No.SAMC12-JS-15-044)
文摘Operations in assembling and joining large size aircraft components are changed to novel digital and flexible ways by digital measurement assisted alignment.Positions and orientations（P＆O）of aligned components are critical characters which assure geometrical positions and relationships of those components.Therefore,evaluating the P＆O of a component is considered necessary and critical for ensuring accuracy in aircraft assembly.Uncertainty of position and orientation（U-P＆O）,as a part of the evaluating result of P＆O,needs to be given for ensuring the integrity and credibility of the result;furthermore,U-P＆O is necessary for error tracing and quality evaluating of measurement assisted aircraft assembly.However,current research mainly focuses on the process integration of measurement with assembly,and usually ignores the uncertainty of measured result and its influence on quality evaluation.This paper focuses on the expression,analysis,and application of U-P＆O in measurement assisted alignment.The geometrical and algebraical connotations of U-P＆O are presented.Then,an analytical algorithm for evaluating the multi-dimensional U-P＆O is given,and the effect factors and characteristics of U-P＆O are discussed.Finally,U-P＆O is used to evaluate alignment in aircraft assembly for quality evaluating and improving.Cases are introduced with the methodology.
文摘In recent years, the increasing application of nonlinear and unbalanced electronic equipment and large single phase loads have made voltage imbalance a serious problem in power distribution systems. A novel approach has been proposed to eliminate voltage imbalance and disturbances. The main strategy of this scheme is based on series active filter. By improving control circuit toward existing schemes and proposing a new strategy to control the voltage amplitude, simultaneous elimination of voltage imbalance, faults, voltage harmonics and also compensation of voltage drop in transmission lines become possible. Eventually, the voltage on the load side is a perfectly balanced three phase voltage with specific proper amplitude. The proposed scheme has been simulated in a test network and the results show high capability of this scheme for the complete elimination of imbalance without phase shift.
