The height anomaly surface is fitt and the quasi-geoid can be obtained when the height anomaly is determined with the geometric analytic method.Therefore,some mathematical models to fit height anomaly surface using GP...The height anomaly surface is fitt and the quasi-geoid can be obtained when the height anomaly is determined with the geometric analytic method.Therefore,some mathematical models to fit height anomaly surface using GPS,leveling and terrain data in a local area,including the polynomial fitting model,the multi-surface function fitting model,the motion surface fitting model and the fitting model of little flexibility deformation of thin board,are given.Then the digital characteristics are analyzed with the curved surface theory.The General curvature and the mean curvature of surface are concluded.The advantage,disadvantage and application of the above models are discussed.The effect of terrain undulation on height anomaly is considered in the surface fitting models.The practical case indicates that these models are of validity and practicability.It is concluded that the above models can give the good fitting results at the centimeter level.But the polynomial fitting model is worse than the other models.展开更多
Based on the theory of adaptive time-frequency decomposition and Time-Frequency Dis- tribution Series (TFDS), this paper presents a novel denoising method for non-stationary signal. Ac- cording to the input signal fea...Based on the theory of adaptive time-frequency decomposition and Time-Frequency Dis- tribution Series (TFDS), this paper presents a novel denoising method for non-stationary signal. Ac- cording to the input signal features, an appropriate kind of elementary functions with great concen- tration in the Time-Frequency (TF) plane is selected. Then the input signal is decomposed into a linear combination of these functions. The elementary function parameters are determined by using ele- mentary function TF curve surface to fit the input signal’s TFDS. The process of curved surface fitting corresponds to the signal structure matching process. The input signal’s dominating component whose structure has the resemblance with elementary function is fitted out firstly. Repeating the fitting process, the residue can be regarded as noises, which are greatly different from the function. Selecting the functions fitted out initially for reconstruction, the denoised signal is obtained. The performance of the proposed method is assessed by means of several tests on an emulated signal and a gearbox vi- brating signal.展开更多
This paper presents an automatic programming system on PC, it has also solved the technic problem in the combination of different curves or surfaces. The NURBS is applied to modeling and fitting complicated curves a...This paper presents an automatic programming system on PC, it has also solved the technic problem in the combination of different curves or surfaces. The NURBS is applied to modeling and fitting complicated curves and surfaces. The circular spline is combined with the NURBS to determine the cutter path in accordance with the features of the interpolation movement of NC machine tool. Three methods have been developed to solve the overcutting problems.展开更多
基金Project(02-09-13)supported by Open Research Fund Programof the Key Laboratory of Geospace Environment and Geodesy,Ministryof Education,ChinaProject(SD2003-4)supported by Open Research Fund Programof the Key Laboratory of Geomatice Digital Tech-nology,Shandong Province,ChinaProject supported by FIG Foundation
文摘The height anomaly surface is fitt and the quasi-geoid can be obtained when the height anomaly is determined with the geometric analytic method.Therefore,some mathematical models to fit height anomaly surface using GPS,leveling and terrain data in a local area,including the polynomial fitting model,the multi-surface function fitting model,the motion surface fitting model and the fitting model of little flexibility deformation of thin board,are given.Then the digital characteristics are analyzed with the curved surface theory.The General curvature and the mean curvature of surface are concluded.The advantage,disadvantage and application of the above models are discussed.The effect of terrain undulation on height anomaly is considered in the surface fitting models.The practical case indicates that these models are of validity and practicability.It is concluded that the above models can give the good fitting results at the centimeter level.But the polynomial fitting model is worse than the other models.
基金Supported by National Natural Science Foundation of China(No.50605065).
文摘Based on the theory of adaptive time-frequency decomposition and Time-Frequency Dis- tribution Series (TFDS), this paper presents a novel denoising method for non-stationary signal. Ac- cording to the input signal features, an appropriate kind of elementary functions with great concen- tration in the Time-Frequency (TF) plane is selected. Then the input signal is decomposed into a linear combination of these functions. The elementary function parameters are determined by using ele- mentary function TF curve surface to fit the input signal’s TFDS. The process of curved surface fitting corresponds to the signal structure matching process. The input signal’s dominating component whose structure has the resemblance with elementary function is fitted out firstly. Repeating the fitting process, the residue can be regarded as noises, which are greatly different from the function. Selecting the functions fitted out initially for reconstruction, the denoised signal is obtained. The performance of the proposed method is assessed by means of several tests on an emulated signal and a gearbox vi- brating signal.
文摘This paper presents an automatic programming system on PC, it has also solved the technic problem in the combination of different curves or surfaces. The NURBS is applied to modeling and fitting complicated curves and surfaces. The circular spline is combined with the NURBS to determine the cutter path in accordance with the features of the interpolation movement of NC machine tool. Three methods have been developed to solve the overcutting problems.
