In order to obtain the life information of the vacuum fluorescent display (VFD) in a short time, a model of constant stress accelerated life tests (CSALT) is established with its filament temperature increased, an...In order to obtain the life information of the vacuum fluorescent display (VFD) in a short time, a model of constant stress accelerated life tests (CSALT) is established with its filament temperature increased, and four constant stress tests are conducted. The Weibull function is applied to describe the life distribution of the VFD, and the maximum likelihood estimation (MLE) and its iterative flow chart are used to calculate the shape parameters and the scale parameters. Furthermore, the accelerated life equation is determined by the least square method, the Kolmogorov-Smirnov test is performed to verify whether the VFD life meets the Weibull distribution or not, and selfdeveloped software is employed to predict the average life and the reliable life. Statistical data analysis results demonstrate that the test plans are feasible and versatile, that the VFD life follows the Weibull distribution, and that the VFD accelerated model satisfies the linear Arrhenius equation. The proposed method and the estimated life information of the VFD can provide some significant guideline to its manufacturers and customers.展开更多
To estimate percentiles of a response distribution, the transformed response rule of Wetherill and Robbins-Monro sequential design were proposed under Log-Logistic model. Based on responses data, a necessary and suffi...To estimate percentiles of a response distribution, the transformed response rule of Wetherill and Robbins-Monro sequential design were proposed under Log-Logistic model. Based on responses data, a necessary and sufficient condition for the existence of maximum likelihood estimators and then the calculating formula were presented. After a simulation study, the proposed approach was applied to 65# detonator. Numerical results showed that estimators of percentiles from the proposed approach are robust to the parametric models lacking information on the original response distribution.展开更多
The multiply type-I censoring represented that all units in life test were terminated at different times. For estimations of Weibull parameters, it was easy to compute the maximum likelihood estimation (MLE) and lea...The multiply type-I censoring represented that all units in life test were terminated at different times. For estimations of Weibull parameters, it was easy to compute the maximum likelihood estimation (MLE) and least-squares estimation (LSE) while it was hard to build confidence intervals (CI). The concept of generalized confidence interval (GCI) was introduced to build CIs of parameters under multiply type-I censoring. Further, GCI based on LSE and GCI based on MLE were proposed. It is mathematically proved that the former is exact and the latter is approximate. Besides, a Monte Carlo simulation study and an illustrative example also Ran out that the GCI method based on LSE yields rather satisfactory results by comparison with the ones based on MLE. It should be clear that the GCI method is a sensible choice to evaluate reliability under multiply type-I censoring.展开更多
Speckle degrades severely the quality of medical B-scan ultrasonic images, especiallyit blurs edges and details of images. An adaptive speckle suppression and edge enhancementmethod based on Nakagami distribution is p...Speckle degrades severely the quality of medical B-scan ultrasonic images, especiallyit blurs edges and details of images. An adaptive speckle suppression and edge enhancementmethod based on Nakagami distribution is presented. The statistics of log-compressed echo im-ages is derived for Nakagami distribution. An adaptive filter based on local statistical propertyof speckle is designed. The stick technique that utilizes sticks with different sizes and variousorientations is applied to locally approximate certain linear features of image. The local regionis a stick instead of a usual window, the orientation of sticks is decided by hypothesis test op-timizing method and the length of sticks is obtained by region growing technique. Performanceof the new method has been tested on the phantom and ultrasound images of pig muscle andechocardiographic. The results show that the technique effectively reduces the speckle noise whilepreserving and enhancing the tissue edge and resolvable details.展开更多
A manifestly gauge-invariant formulation of non-relativistic quantum mechanics is applied to the case of time-dependent harmonic oscillator in the magnetic dipole approximation. A general equation for obtaining gauge-...A manifestly gauge-invariant formulation of non-relativistic quantum mechanics is applied to the case of time-dependent harmonic oscillator in the magnetic dipole approximation. A general equation for obtaining gauge-invariant transition probability amplitudes is derived.展开更多
In Direct-Sequence Code Division Multiple Access(DS-CDMA) mobile communi-cation systems, it is very important to obtain accurate estimation of the channel parameters,especially that of the propagation delay. But the n...In Direct-Sequence Code Division Multiple Access(DS-CDMA) mobile communi-cation systems, it is very important to obtain accurate estimation of the channel parameters,especially that of the propagation delay. But the near-far problem may make the estimationcomplicated and can degrade the estimation performance significantly. In this paper, an efficientMaximum Likelihood (ML) method is presented for channel parameter estimation of multi-rateDS-CDMA systems in slow fading multipath channels in a near-far scenario. The algorithmextended the ML approach to multi-rate DS-CDMA systems, and proposes decomposing a multi-dimensional optimization problem into a series of one-dimensional optimization and has improvedcomputational efficiency. Theoretical analysis and numerical examples show that the estimatorproposed is effective and near-far resistant.展开更多
In this paper, to keep scale inveriance, we propose an approximate M-estrmation for the mixed regression model and show consistency of the estimation under weaker conditions than that in [1].
In order to consider the Wisdom of the Many, one has to reconsider Aristotle's statement about the source of a nation-state concerning political "gregarism"--how it is called today, and why this belongs to the esse...In order to consider the Wisdom of the Many, one has to reconsider Aristotle's statement about the source of a nation-state concerning political "gregarism"--how it is called today, and why this belongs to the essentials of political constitution. Beforehand, this concept should not provide an instance of theoretical indulgence for emotional concepts or alike. Then, this statement will have to be confronted with the core argument of the Wisdom of the Many, together with the interpretation of Waldron. It will be interpreted as the counterpart of gregarism: When several people find together a solution, which eventually overrules that of the (few) expert(s), they rely upon a common focus or an instance of polar consciousness. This includes the final question if the shared consciousness-or the polarity condition-is not able to also dominate and manifest within a group of experts, of those sufficiently erudite. As a token of possible evidence, the answer is given with Fichte, his lecture of the Science of Knowledge of 1804 by reason of the succinct reliance upon the plural "We."展开更多
Not much data are available regarding the electrical activity in the stomachs and intestines of elderly gastrectomized patients The purpose of this study was to determine the feasibility of using a complex dynamic met...Not much data are available regarding the electrical activity in the stomachs and intestines of elderly gastrectomized patients The purpose of this study was to determine the feasibility of using a complex dynamic method to analyze the electrogastrograms (EGGs) of healthy young, healthy elderly, and gastrectomized elderly male individuals. The authors analyzed the EGGs by using the maximum Lyapunov exponent (MLE), which is one of the indices of the chaotic characteristics of time series. Significant differences were observed between the MLEs estimated from the, EGGs of the young and elderly individuals for most of the temporal intervals. The authors' data indicate that the EGGs of elderly gastrectomized subjects might be distinguished from the EGGs of healthy elderly individuals on the basis of the MLE distribution.展开更多
The elastic property and sound velocity of FeaC under high pressure are investigated by using the spin-polarized generalized gradient approximation within density-functional theory. It is found that the magnetic phase...The elastic property and sound velocity of FeaC under high pressure are investigated by using the spin-polarized generalized gradient approximation within density-functional theory. It is found that the magnetic phase transition from the ground ferromagnetic (FM) state to the nonmagnetic (NM) state occurs at ~73 GPa. Based on the predicted Hugoniot of Fe3C, we calculate the sound velocities of FM-Fe3C and NM-Fe3C from elastic constants. Compared with pure iron, NM-FeaC provides a better match of compressional and shear sound velocities with the seismic data of the inner core, supporting carbon as one of the light elements in the inner core.展开更多
The electrode regulator system is a complex system with many variables, strong coupling and strong nonlinearity, while conventional control methods such as proportional integral derivative (PID) can not meet the req...The electrode regulator system is a complex system with many variables, strong coupling and strong nonlinearity, while conventional control methods such as proportional integral derivative (PID) can not meet the requirements. A robust adaptive neural network controller (RANNC) for electrode regulator system was proposed. Artificial neural networks were established to learn the system dynamics. The nonlinear control law was derived directly based on an input-output approximating method via the Taylor expansion, which avoids complex control development and intensive computation. The stability of the closed-loop system was established by the Lyapunov method. The current fluctuation relative percentage is less than ±8% and heating rate is up to 6.32 ℃/min when the proposed controller is used. The experiment results show that the proposed control scheme is better than inverse neural network controller (INNC) and PID controller (PIDC).展开更多
The seasonal signal and long-term trend in the height time series of 10 IGS sites in China are investigated in this paper. The offset detection and outlier removal as well as the removal of common mode error are perfo...The seasonal signal and long-term trend in the height time series of 10 IGS sites in China are investigated in this paper. The offset detection and outlier removal as well as the removal of common mode error are performed on the raw GPS time-series data developed by the Scripps Orbit and Permanent Array Center(SOPAC). The seasonal-trend decomposition procedure based on LOESS(STL) is utilized to extract precise seasonal signals, followed by an estimation of the long-term trend with the application of maximum likelihood estimation(MLE) to the seasonally adjusted time series. The Up-compo- nents of all sites are featured by obvious seasonal variations, with significant phase and amplitude modulation on some sites. After Kendall's tau test, a significant trend(99% confidence interval) for all sites is achieved. Furthermore, the trends at sites TCMS and TNML have significant changes at epochs 2009.5384 and 2009.1493(95% confidence interval), respectively, using the Breaks For Additive Seasonal and Trend test. Finally, the velocities and their uncertainties for all sites are estimated using MLE with the white noise plus flicker noise model. And the results are analyzed and compared with those announced by SOPAC. The results obtained in this paper have a higher precision than the SOPAC results.展开更多
To break through the limitations of traditional discriminators used in vector tracking loops, this paper presents an iterative maximum likelihood estimation(IMLE) method for extracting navigation state errors from mul...To break through the limitations of traditional discriminators used in vector tracking loops, this paper presents an iterative maximum likelihood estimation(IMLE) method for extracting navigation state errors from multi-satellite signals. The IMLE method takes into account both computational cost and estimation accuracy. The associated gradient vector and Hessian matrix of the MLE cost function are derived. The characteristics of the proposed joint discriminator are analyzed based on the properties of the MLE cost function,gradient vector, and Hessian matrix. The effectiveness of IMLE is verified by Monte Carlo simulation.展开更多
基金Undergraduate Education High land Construction Project of Shanghaithe Key Course Construction of Shanghai Education Committee (No.20075302)the Key Technology R&D Program of Shanghai Municipality (No.08160510600)
文摘In order to obtain the life information of the vacuum fluorescent display (VFD) in a short time, a model of constant stress accelerated life tests (CSALT) is established with its filament temperature increased, and four constant stress tests are conducted. The Weibull function is applied to describe the life distribution of the VFD, and the maximum likelihood estimation (MLE) and its iterative flow chart are used to calculate the shape parameters and the scale parameters. Furthermore, the accelerated life equation is determined by the least square method, the Kolmogorov-Smirnov test is performed to verify whether the VFD life meets the Weibull distribution or not, and selfdeveloped software is employed to predict the average life and the reliable life. Statistical data analysis results demonstrate that the test plans are feasible and versatile, that the VFD life follows the Weibull distribution, and that the VFD accelerated model satisfies the linear Arrhenius equation. The proposed method and the estimated life information of the VFD can provide some significant guideline to its manufacturers and customers.
文摘To estimate percentiles of a response distribution, the transformed response rule of Wetherill and Robbins-Monro sequential design were proposed under Log-Logistic model. Based on responses data, a necessary and sufficient condition for the existence of maximum likelihood estimators and then the calculating formula were presented. After a simulation study, the proposed approach was applied to 65# detonator. Numerical results showed that estimators of percentiles from the proposed approach are robust to the parametric models lacking information on the original response distribution.
基金Project(71371182) supported by the National Natural Science Foundation of China
文摘The multiply type-I censoring represented that all units in life test were terminated at different times. For estimations of Weibull parameters, it was easy to compute the maximum likelihood estimation (MLE) and least-squares estimation (LSE) while it was hard to build confidence intervals (CI). The concept of generalized confidence interval (GCI) was introduced to build CIs of parameters under multiply type-I censoring. Further, GCI based on LSE and GCI based on MLE were proposed. It is mathematically proved that the former is exact and the latter is approximate. Besides, a Monte Carlo simulation study and an illustrative example also Ran out that the GCI method based on LSE yields rather satisfactory results by comparison with the ones based on MLE. It should be clear that the GCI method is a sensible choice to evaluate reliability under multiply type-I censoring.
文摘Speckle degrades severely the quality of medical B-scan ultrasonic images, especiallyit blurs edges and details of images. An adaptive speckle suppression and edge enhancementmethod based on Nakagami distribution is presented. The statistics of log-compressed echo im-ages is derived for Nakagami distribution. An adaptive filter based on local statistical propertyof speckle is designed. The stick technique that utilizes sticks with different sizes and variousorientations is applied to locally approximate certain linear features of image. The local regionis a stick instead of a usual window, the orientation of sticks is decided by hypothesis test op-timizing method and the length of sticks is obtained by region growing technique. Performanceof the new method has been tested on the phantom and ultrasound images of pig muscle andechocardiographic. The results show that the technique effectively reduces the speckle noise whilepreserving and enhancing the tissue edge and resolvable details.
文摘A manifestly gauge-invariant formulation of non-relativistic quantum mechanics is applied to the case of time-dependent harmonic oscillator in the magnetic dipole approximation. A general equation for obtaining gauge-invariant transition probability amplitudes is derived.
基金the National Natural Science Foundation of China under Grant 60102005
文摘In Direct-Sequence Code Division Multiple Access(DS-CDMA) mobile communi-cation systems, it is very important to obtain accurate estimation of the channel parameters,especially that of the propagation delay. But the near-far problem may make the estimationcomplicated and can degrade the estimation performance significantly. In this paper, an efficientMaximum Likelihood (ML) method is presented for channel parameter estimation of multi-rateDS-CDMA systems in slow fading multipath channels in a near-far scenario. The algorithmextended the ML approach to multi-rate DS-CDMA systems, and proposes decomposing a multi-dimensional optimization problem into a series of one-dimensional optimization and has improvedcomputational efficiency. Theoretical analysis and numerical examples show that the estimatorproposed is effective and near-far resistant.
文摘In this paper, to keep scale inveriance, we propose an approximate M-estrmation for the mixed regression model and show consistency of the estimation under weaker conditions than that in [1].
文摘In order to consider the Wisdom of the Many, one has to reconsider Aristotle's statement about the source of a nation-state concerning political "gregarism"--how it is called today, and why this belongs to the essentials of political constitution. Beforehand, this concept should not provide an instance of theoretical indulgence for emotional concepts or alike. Then, this statement will have to be confronted with the core argument of the Wisdom of the Many, together with the interpretation of Waldron. It will be interpreted as the counterpart of gregarism: When several people find together a solution, which eventually overrules that of the (few) expert(s), they rely upon a common focus or an instance of polar consciousness. This includes the final question if the shared consciousness-or the polarity condition-is not able to also dominate and manifest within a group of experts, of those sufficiently erudite. As a token of possible evidence, the answer is given with Fichte, his lecture of the Science of Knowledge of 1804 by reason of the succinct reliance upon the plural "We."
文摘Not much data are available regarding the electrical activity in the stomachs and intestines of elderly gastrectomized patients The purpose of this study was to determine the feasibility of using a complex dynamic method to analyze the electrogastrograms (EGGs) of healthy young, healthy elderly, and gastrectomized elderly male individuals. The authors analyzed the EGGs by using the maximum Lyapunov exponent (MLE), which is one of the indices of the chaotic characteristics of time series. Significant differences were observed between the MLEs estimated from the, EGGs of the young and elderly individuals for most of the temporal intervals. The authors' data indicate that the EGGs of elderly gastrectomized subjects might be distinguished from the EGGs of healthy elderly individuals on the basis of the MLE distribution.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (No.11247316, No.11247317, No.11347019, No.11304408, and No.U1230201), the Science and Technology Research Project of Chongqing Education Committee (No.K J120613 and No.KJ130607), and the Natural Science Foundation of Chongqing City (No.cstc2012jjA50019 and No.cstc2013jcyjA0733).
文摘The elastic property and sound velocity of FeaC under high pressure are investigated by using the spin-polarized generalized gradient approximation within density-functional theory. It is found that the magnetic phase transition from the ground ferromagnetic (FM) state to the nonmagnetic (NM) state occurs at ~73 GPa. Based on the predicted Hugoniot of Fe3C, we calculate the sound velocities of FM-Fe3C and NM-Fe3C from elastic constants. Compared with pure iron, NM-FeaC provides a better match of compressional and shear sound velocities with the seismic data of the inner core, supporting carbon as one of the light elements in the inner core.
基金Project(N100604002) supported by the Fundamental Research Funds for Central Universities of ChinaProject(61074074) supported by the National Natural Science Foundation of China
文摘The electrode regulator system is a complex system with many variables, strong coupling and strong nonlinearity, while conventional control methods such as proportional integral derivative (PID) can not meet the requirements. A robust adaptive neural network controller (RANNC) for electrode regulator system was proposed. Artificial neural networks were established to learn the system dynamics. The nonlinear control law was derived directly based on an input-output approximating method via the Taylor expansion, which avoids complex control development and intensive computation. The stability of the closed-loop system was established by the Lyapunov method. The current fluctuation relative percentage is less than ±8% and heating rate is up to 6.32 ℃/min when the proposed controller is used. The experiment results show that the proposed control scheme is better than inverse neural network controller (INNC) and PID controller (PIDC).
基金supported by the National High Technology Research and Development Program of China(Grant No.2013AA122501-1)the National Natural Science Foundation of China(Grant Nos.41374019,41020144004,41474015,41274045,41574010)Funded by State Key Laboratory of Geo-information Engineering(Grant No.SKLGIE2015-Z-1-1)
文摘The seasonal signal and long-term trend in the height time series of 10 IGS sites in China are investigated in this paper. The offset detection and outlier removal as well as the removal of common mode error are performed on the raw GPS time-series data developed by the Scripps Orbit and Permanent Array Center(SOPAC). The seasonal-trend decomposition procedure based on LOESS(STL) is utilized to extract precise seasonal signals, followed by an estimation of the long-term trend with the application of maximum likelihood estimation(MLE) to the seasonally adjusted time series. The Up-compo- nents of all sites are featured by obvious seasonal variations, with significant phase and amplitude modulation on some sites. After Kendall's tau test, a significant trend(99% confidence interval) for all sites is achieved. Furthermore, the trends at sites TCMS and TNML have significant changes at epochs 2009.5384 and 2009.1493(95% confidence interval), respectively, using the Breaks For Additive Seasonal and Trend test. Finally, the velocities and their uncertainties for all sites are estimated using MLE with the white noise plus flicker noise model. And the results are analyzed and compared with those announced by SOPAC. The results obtained in this paper have a higher precision than the SOPAC results.
基金supported by National High Technology Research and Development Program of China(863)(Grant No.2013AA1548)
文摘To break through the limitations of traditional discriminators used in vector tracking loops, this paper presents an iterative maximum likelihood estimation(IMLE) method for extracting navigation state errors from multi-satellite signals. The IMLE method takes into account both computational cost and estimation accuracy. The associated gradient vector and Hessian matrix of the MLE cost function are derived. The characteristics of the proposed joint discriminator are analyzed based on the properties of the MLE cost function,gradient vector, and Hessian matrix. The effectiveness of IMLE is verified by Monte Carlo simulation.