Optical spectroscopic identification of X-ray selected WTTS candidates in the Taurus-Auriga outskirts on the basis of ROSAT pointing observations, has resulted in the discovery of 4 WTTS and several other Li-rich sour...Optical spectroscopic identification of X-ray selected WTTS candidates in the Taurus-Auriga outskirts on the basis of ROSAT pointing observations, has resulted in the discovery of 4 WTTS and several other Li-rich sources. This paper gives the R magnitudes, coordinates (J2000) from USNO (V1.0), spectral type classifications, equivalent widths of Li I absorption and H. emission lines of all the X-ray sources investigated, and the proper motions and parallaxes of some of them, as well as the spectra of the newly discovered WTTS. For the first time, the spatial distribution of a rather complete, ROSAT-discovered sample of WTTS, including those identified from the ROSAT All-Sky Survey and PSPC pointing observations around one of the nearby star-forming regions has been provided, together with a preliminary analysis.展开更多
It is difficult to predict wind speed series accurately due to the instability and randomness of the wind speed series.In order to predict wind speed,authors propose a hybrid model which combines the wavelet transform...It is difficult to predict wind speed series accurately due to the instability and randomness of the wind speed series.In order to predict wind speed,authors propose a hybrid model which combines the wavelet transform technique(WTT),the exponential smoothing(ES)method and the back propagation neural network(BPNN),and is termed as WTT-ES-BPNN.Firstly,WTT is applied to the raw wind speed series for removing the useless information.Secondly,the hybrid model integrating the ES method and the BPNN is used to forecast the de-noising data.Finally,the prediction of raw wind speed series is caught.Real data sets of daily mean wind speed in Hebei Province are used to evaluate the forecasting accuracy of the proposed model.Numerical results indicate that the WTT-ES-BPNN is an effective way to improve the accuracy of wind speed prediction.展开更多
In this paper, we prove that every p-generic r.e. degree is noncontiguous, and then, by the density of p-generic degrees, the noncontiguous degrees are dense in the r.e. degrees.
Jockusch and Ingrassia introduced notions of e-genericity, s-genericity and p-genericity for recursively enumerable sets in 1985 and 1980 respectively. It has been shown that there are many important properties of rec...Jockusch and Ingrassia introduced notions of e-genericity, s-genericity and p-genericity for recursively enumerable sets in 1985 and 1980 respectively. It has been shown that there are many important properties of recursively enumerable generic sets and degrees. We have investigated the structures of wtt-degrees inside recursively enumerable p-generic Turing degrees and proved that every r.e. p-generic degree is noncontiguous. In this note, we展开更多
文摘Optical spectroscopic identification of X-ray selected WTTS candidates in the Taurus-Auriga outskirts on the basis of ROSAT pointing observations, has resulted in the discovery of 4 WTTS and several other Li-rich sources. This paper gives the R magnitudes, coordinates (J2000) from USNO (V1.0), spectral type classifications, equivalent widths of Li I absorption and H. emission lines of all the X-ray sources investigated, and the proper motions and parallaxes of some of them, as well as the spectra of the newly discovered WTTS. For the first time, the spatial distribution of a rather complete, ROSAT-discovered sample of WTTS, including those identified from the ROSAT All-Sky Survey and PSPC pointing observations around one of the nearby star-forming regions has been provided, together with a preliminary analysis.
文摘It is difficult to predict wind speed series accurately due to the instability and randomness of the wind speed series.In order to predict wind speed,authors propose a hybrid model which combines the wavelet transform technique(WTT),the exponential smoothing(ES)method and the back propagation neural network(BPNN),and is termed as WTT-ES-BPNN.Firstly,WTT is applied to the raw wind speed series for removing the useless information.Secondly,the hybrid model integrating the ES method and the BPNN is used to forecast the de-noising data.Finally,the prediction of raw wind speed series is caught.Real data sets of daily mean wind speed in Hebei Province are used to evaluate the forecasting accuracy of the proposed model.Numerical results indicate that the WTT-ES-BPNN is an effective way to improve the accuracy of wind speed prediction.
基金Project supported by the National Natural Science Foundation of China and by a Grant by the Volkswagen Foundation of Germany for a Chinese-German Binational Research Project in Recursion Theory and Complexity Theory
文摘In this paper, we prove that every p-generic r.e. degree is noncontiguous, and then, by the density of p-generic degrees, the noncontiguous degrees are dense in the r.e. degrees.
基金Project supported by the National Natural Science Foundation of China.
文摘Jockusch and Ingrassia introduced notions of e-genericity, s-genericity and p-genericity for recursively enumerable sets in 1985 and 1980 respectively. It has been shown that there are many important properties of recursively enumerable generic sets and degrees. We have investigated the structures of wtt-degrees inside recursively enumerable p-generic Turing degrees and proved that every r.e. p-generic degree is noncontiguous. In this note, we
