A risk assessment based adaptive ultra-short-term wind power prediction(USTWPP)method is proposed in this paper.In this method,features are first extracted from the historical data,and then each wind power time series...A risk assessment based adaptive ultra-short-term wind power prediction(USTWPP)method is proposed in this paper.In this method,features are first extracted from the historical data,and then each wind power time series(WPTS)is split into several subsets defined by their stationary patterns.A WPTS that does not match any of the stationary patterns is then included in a subset of non-stationary patterns.Each WPTS subset is then related to a USTWPP model that is specially selected and optimized offline based on the proposed risk assessment index.For online applications,the pattern of the last short WPTS is first recognized,and the relevant prediction model is then applied for USTWPP.Experimental results confirm the efficacy of the proposed method.展开更多
When the beam in BEPCII storage ring aborts suddenly, the measured pressure of cold cathode gauges and ion pumps will drop suddenly and decrease to the base pressure gradually. This shows that there is a beam induced ...When the beam in BEPCII storage ring aborts suddenly, the measured pressure of cold cathode gauges and ion pumps will drop suddenly and decrease to the base pressure gradually. This shows that there is a beam induced positive error in the pressure measurement during beam operation. The error is the difference between measured and real pressures. Right after the beam aborts, the error will disappear immediately and the measured pressure will then be equal to real pressure. For one gauge, we can fit a non-linear pressure-time curve with its measured pressure data 20 seconds after a sudden beam abortion. From this negative exponential decay pumping-down curve, real pressure at the time when the beam starts aborting is extrapolated. With the data of several sudden beam abortions we have got the errors of that gauge in different beam currents and found that the error is directly proportional to the beam current, as expected. And a linear data-fitting gives the proportion coefficient of the equation, which we derived to evaluate the real pressure all the time when the beam with varied currents is on.展开更多
According to an error analysis on Chinese college students' writing,the native language and culture have great influence onsecond-language writing.On the basis of error analysis,this paper put forward some counter...According to an error analysis on Chinese college students' writing,the native language and culture have great influence onsecond-language writing.On the basis of error analysis,this paper put forward some countermeasures to improve Chinese students' Eng-lish writing skill.展开更多
Based on the Error Analysis theory and Contrastive Analysis theory,this thesis aims to investigate the phenomenon of negative transfer of mother tongue at the levels of substance,lexis and syntax by taking advantage o...Based on the Error Analysis theory and Contrastive Analysis theory,this thesis aims to investigate the phenomenon of negative transfer of mother tongue at the levels of substance,lexis and syntax by taking advantage of quantitative analysis method,and an attempt is made to analyze and classify writing errors in L2 writings by English majors.Anyhow,it is hoped that current research can achieve the purpose of avoiding the negative transfer of mother tongue and to improve English majors’writing capability accordingly.展开更多
基金supported in part by Special Fund of the National Basic Research Program of China(2013CB228204)NSFCNRCT Collaborative Project(No.51561145011)+1 种基金Australian Research Council Project(DP120101345)State Grid Corporation of China.
文摘A risk assessment based adaptive ultra-short-term wind power prediction(USTWPP)method is proposed in this paper.In this method,features are first extracted from the historical data,and then each wind power time series(WPTS)is split into several subsets defined by their stationary patterns.A WPTS that does not match any of the stationary patterns is then included in a subset of non-stationary patterns.Each WPTS subset is then related to a USTWPP model that is specially selected and optimized offline based on the proposed risk assessment index.For online applications,the pattern of the last short WPTS is first recognized,and the relevant prediction model is then applied for USTWPP.Experimental results confirm the efficacy of the proposed method.
基金supported by the Beijing Electron Positron Collider Upgrade Project Funding Issues
文摘When the beam in BEPCII storage ring aborts suddenly, the measured pressure of cold cathode gauges and ion pumps will drop suddenly and decrease to the base pressure gradually. This shows that there is a beam induced positive error in the pressure measurement during beam operation. The error is the difference between measured and real pressures. Right after the beam aborts, the error will disappear immediately and the measured pressure will then be equal to real pressure. For one gauge, we can fit a non-linear pressure-time curve with its measured pressure data 20 seconds after a sudden beam abortion. From this negative exponential decay pumping-down curve, real pressure at the time when the beam starts aborting is extrapolated. With the data of several sudden beam abortions we have got the errors of that gauge in different beam currents and found that the error is directly proportional to the beam current, as expected. And a linear data-fitting gives the proportion coefficient of the equation, which we derived to evaluate the real pressure all the time when the beam with varied currents is on.
文摘According to an error analysis on Chinese college students' writing,the native language and culture have great influence onsecond-language writing.On the basis of error analysis,this paper put forward some countermeasures to improve Chinese students' Eng-lish writing skill.
文摘Based on the Error Analysis theory and Contrastive Analysis theory,this thesis aims to investigate the phenomenon of negative transfer of mother tongue at the levels of substance,lexis and syntax by taking advantage of quantitative analysis method,and an attempt is made to analyze and classify writing errors in L2 writings by English majors.Anyhow,it is hoped that current research can achieve the purpose of avoiding the negative transfer of mother tongue and to improve English majors’writing capability accordingly.
