This paper investigates the characteristics of a non-stationary time series, which exists in mechanical fault diagnosis. Combining the characteristics with predictive efficiency, the limitation of the ARIMA model pred...This paper investigates the characteristics of a non-stationary time series, which exists in mechanical fault diagnosis. Combining the characteristics with predictive efficiency, the limitation of the ARIMA model prediction method is analyzed. This model often is applied in the prediction of a non-stationary times series in present. Thus, a wavelet prediction method is introduced to solve non-stationary problems. The Mallat method, often used in signal processing, results form the decimation or the retention of one out of every two samples. Its advantage is that just enough information is kept to allow the exact reconstruction of the input series, but the disadvantage is a time-varying series on line cannot be pursued. Therefore, the authors present another method, à Trous method, which can be applied for recursive prediction in real-time sampling procedure.展开更多
During the past research, Direct Sequence (DS) Spread Spectrum (SS) signal is modeled as stationary in most cases. Cyclostationary model for SS signal is introduced in this letter. Compared with stationary model, cycl...During the past research, Direct Sequence (DS) Spread Spectrum (SS) signal is modeled as stationary in most cases. Cyclostationary model for SS signal is introduced in this letter. Compared with stationary model, cyclostationary model can preserve more information,and its advantages are shown through example.展开更多
The combustion characteristics and particulate emission during combustion of Thai lignite with 30% of secondary air to total air （SA：TA） in a fixed bed combustor have been investigated in real-time. The results hav...The combustion characteristics and particulate emission during combustion of Thai lignite with 30% of secondary air to total air （SA：TA） in a fixed bed combustor have been investigated in real-time. The results have shown that particle formation is governed by competing reaction between the formation of the nucleated sized-particles （Dp 〈 0.1μm） and the coagulated particle （Dp 0.1-1 μm）. Temperature and burning rate are the highest priority factors to control the emission of particulate. Furthermore, the co-firing of coal/rice husks at 60：40% mass fraction with 10%SA：TA could be the alternative options to further reduction of particulate and to be recommended.展开更多
A series of experiments were performed on indigenously synthesized catalyst pallets of cobalt as a very active metal on ceramic support like SiC, A1203 ＆ TiO2 in a fixed bed reactor configuration with an aim to study...A series of experiments were performed on indigenously synthesized catalyst pallets of cobalt as a very active metal on ceramic support like SiC, A1203 ＆ TiO2 in a fixed bed reactor configuration with an aim to study the catalyst activity ＆ selectivity, chemical kinetics, design flexibility, temperature, pressure by characteristics diffusion distance. Catalyst pallets were prepared and then characterized by N2 adsorption, X-ray Diffraction, Scanning Electron Microscope, and Temperature Programmed Reduction. The results showed the Brunaner, Emmett and Teller area of SiC was the lowest among the three supports prepared for testing. However, its reducibility showed improvement with use of cobalt acetate, as a precursor, rather than cobalt nitrates. Mechanical strength and behavior was checked by the hardness testing machine. Fischer Tropsch （FT） synthesis experiments were performed in the fixed bed reactor set at 450-500 K and 2.3-2.5 MPa using synthetic gas having HJCO ration = 2.0. FT synthesis showed that cobalt/silicon carbide catalyst gives high CO conversion and lower methane selectivity, compared to Co/A1203 and Co/TiO2, as well as high C5＋ selectivity of almost 90%. Moreover, its stability was enhanced by the addition of Zr02, as without this addition, the Co/SiC interactions are weaker and can cause carbon sintering, and thus, the deactivation rate to increase.展开更多
In this paper, we propose a new smooth function that possesses a property not satisfied by the existing smooth functions. Based on this smooth function, we discuss the existence and continuity of the smoothing path fo...In this paper, we propose a new smooth function that possesses a property not satisfied by the existing smooth functions. Based on this smooth function, we discuss the existence and continuity of the smoothing path for solving the P0 function nonlinear complementarity problem (NCP). Using the characteristics of the new smooth function, we investigate the boundedness of the iteration sequence generated by the non-interior continuation methods for solving the P0 function NCP under the assumption that the solution set of the NCP is nonempty and bounded. We show that the assumption that the solution set of the NCP is nonempty and bounded is weaker than those required by a few existing continuation methods for solving the NCP.展开更多
Consider a semiparametric regression model with linear time series errors Y_k= x′ _kβ + g(t_k) + ε_k, 1 ≤ k ≤ n, where Y_k's are responses, x_k =(x_(k1),x_(k2),···,x_(kp))′ and t_k ∈ T is con...Consider a semiparametric regression model with linear time series errors Y_k= x′ _kβ + g(t_k) + ε_k, 1 ≤ k ≤ n, where Y_k's are responses, x_k =(x_(k1),x_(k2),···,x_(kp))′ and t_k ∈ T is contained in R are fixed design points, β =(β_1,β_2,···,β_p)′ is an unknown parameter vector, g(·) is an unknown bounded real-valuedfunction defined on a compact subset T of the real line R, and ε_k is a linear process given byε_k = ∑ from j=0 to ∞ of ψ_je_(k-j), ψ_0=1, where ∑ from j=0 to ∞ of |ψ_j| < ∞, and e_j,j=0, +-1, +-2,···, ard i.i.d. random variables. In this paper we establish the asymptoticnormality of the least squares estimator of β, a smooth estimator of g(·), and estimators of theautocovariance and autocorrelation functions of the linear process ε_k.展开更多
Objective： To study the effect of internal fixation performed at different times on therapeutic outcomes of Schatzker IV-VI tibial plateau fractureS. Methods： The clinical data of 42 cases ofSehatzker IV- VI tibial...Objective： To study the effect of internal fixation performed at different times on therapeutic outcomes of Schatzker IV-VI tibial plateau fractureS. Methods： The clinical data of 42 cases ofSehatzker IV- VI tibial plateau fractures treated in our department were analyzed retrospectively. Among these 42 patients, 21 re- ceived surgical treatment within 12 h after injury, （Group I）, the other 2 [ were first treated by traction or piaster fixation followed by a delayed internal fixation after soft tissue swell- i ing subsided （Group II）. The surgical time, comPlications, length of hospital stay, cost of hospitalization, and time for i fracture union, as well as functional recovery were analyzed and compared between the two groups. Results： After 10-28 months follow-up （mean 16.5 months）, except 5 cases who lost to follow-upl no differ-ences were found between the two groups regarding surgi- cal time, preoperative and postoperative complications, heal- ing time or the Hospital for Special Surgery （HSS） score at the end of follow-up, but significant differences were found in the length of hospital stay, cost of hospitalization and HSS score at 3 months after operation （P〈0.05）. Conclusion： Under certain conditions, early internal fixation for Schatzker IV-VI tibial plateau fracture is feasible, which can shorten the length of hospital stay, decrease the cost of hospitalization and promote early functional rehabilitation.展开更多
基金Sponsored by the National High Technology Research and Development Program of China (Grant No.2002AA721063).
文摘This paper investigates the characteristics of a non-stationary time series, which exists in mechanical fault diagnosis. Combining the characteristics with predictive efficiency, the limitation of the ARIMA model prediction method is analyzed. This model often is applied in the prediction of a non-stationary times series in present. Thus, a wavelet prediction method is introduced to solve non-stationary problems. The Mallat method, often used in signal processing, results form the decimation or the retention of one out of every two samples. Its advantage is that just enough information is kept to allow the exact reconstruction of the input series, but the disadvantage is a time-varying series on line cannot be pursued. Therefore, the authors present another method, à Trous method, which can be applied for recursive prediction in real-time sampling procedure.
文摘During the past research, Direct Sequence (DS) Spread Spectrum (SS) signal is modeled as stationary in most cases. Cyclostationary model for SS signal is introduced in this letter. Compared with stationary model, cyclostationary model can preserve more information,and its advantages are shown through example.
文摘The combustion characteristics and particulate emission during combustion of Thai lignite with 30% of secondary air to total air （SA：TA） in a fixed bed combustor have been investigated in real-time. The results have shown that particle formation is governed by competing reaction between the formation of the nucleated sized-particles （Dp 〈 0.1μm） and the coagulated particle （Dp 0.1-1 μm）. Temperature and burning rate are the highest priority factors to control the emission of particulate. Furthermore, the co-firing of coal/rice husks at 60：40% mass fraction with 10%SA：TA could be the alternative options to further reduction of particulate and to be recommended.
文摘A series of experiments were performed on indigenously synthesized catalyst pallets of cobalt as a very active metal on ceramic support like SiC, A1203 ＆ TiO2 in a fixed bed reactor configuration with an aim to study the catalyst activity ＆ selectivity, chemical kinetics, design flexibility, temperature, pressure by characteristics diffusion distance. Catalyst pallets were prepared and then characterized by N2 adsorption, X-ray Diffraction, Scanning Electron Microscope, and Temperature Programmed Reduction. The results showed the Brunaner, Emmett and Teller area of SiC was the lowest among the three supports prepared for testing. However, its reducibility showed improvement with use of cobalt acetate, as a precursor, rather than cobalt nitrates. Mechanical strength and behavior was checked by the hardness testing machine. Fischer Tropsch （FT） synthesis experiments were performed in the fixed bed reactor set at 450-500 K and 2.3-2.5 MPa using synthetic gas having HJCO ration = 2.0. FT synthesis showed that cobalt/silicon carbide catalyst gives high CO conversion and lower methane selectivity, compared to Co/A1203 and Co/TiO2, as well as high C5＋ selectivity of almost 90%. Moreover, its stability was enhanced by the addition of Zr02, as without this addition, the Co/SiC interactions are weaker and can cause carbon sintering, and thus, the deactivation rate to increase.
基金the National Natural Science Foundation of China (Grant Nos. 19871016 and 19731001).
文摘In this paper, we propose a new smooth function that possesses a property not satisfied by the existing smooth functions. Based on this smooth function, we discuss the existence and continuity of the smoothing path for solving the P0 function nonlinear complementarity problem (NCP). Using the characteristics of the new smooth function, we investigate the boundedness of the iteration sequence generated by the non-interior continuation methods for solving the P0 function NCP under the assumption that the solution set of the NCP is nonempty and bounded. We show that the assumption that the solution set of the NCP is nonempty and bounded is weaker than those required by a few existing continuation methods for solving the NCP.
基金CHEN Min's work is supported by Grant No. 70221001 and No. 70331001 from NNSFC and Grant No. KZCX2-SW-118 from CAS.
文摘Consider a semiparametric regression model with linear time series errors Y_k= x′ _kβ + g(t_k) + ε_k, 1 ≤ k ≤ n, where Y_k's are responses, x_k =(x_(k1),x_(k2),···,x_(kp))′ and t_k ∈ T is contained in R are fixed design points, β =(β_1,β_2,···,β_p)′ is an unknown parameter vector, g(·) is an unknown bounded real-valuedfunction defined on a compact subset T of the real line R, and ε_k is a linear process given byε_k = ∑ from j=0 to ∞ of ψ_je_(k-j), ψ_0=1, where ∑ from j=0 to ∞ of |ψ_j| < ∞, and e_j,j=0, +-1, +-2,···, ard i.i.d. random variables. In this paper we establish the asymptoticnormality of the least squares estimator of β, a smooth estimator of g(·), and estimators of theautocovariance and autocorrelation functions of the linear process ε_k.
文摘Objective： To study the effect of internal fixation performed at different times on therapeutic outcomes of Schatzker IV-VI tibial plateau fractureS. Methods： The clinical data of 42 cases ofSehatzker IV- VI tibial plateau fractures treated in our department were analyzed retrospectively. Among these 42 patients, 21 re- ceived surgical treatment within 12 h after injury, （Group I）, the other 2 [ were first treated by traction or piaster fixation followed by a delayed internal fixation after soft tissue swell- i ing subsided （Group II）. The surgical time, comPlications, length of hospital stay, cost of hospitalization, and time for i fracture union, as well as functional recovery were analyzed and compared between the two groups. Results： After 10-28 months follow-up （mean 16.5 months）, except 5 cases who lost to follow-upl no differ-ences were found between the two groups regarding surgi- cal time, preoperative and postoperative complications, heal- ing time or the Hospital for Special Surgery （HSS） score at the end of follow-up, but significant differences were found in the length of hospital stay, cost of hospitalization and HSS score at 3 months after operation （P〈0.05）. Conclusion： Under certain conditions, early internal fixation for Schatzker IV-VI tibial plateau fracture is feasible, which can shorten the length of hospital stay, decrease the cost of hospitalization and promote early functional rehabilitation.
