Papers by Keyword: Fitting

Abstract: The logistic model and the four-parameter logistic model have been very effective in forecasting many technological forecasting patterns. However, they have the characteristic of symmetry and cannot effectively model asymmetric data. This paper proposes a new asymmetric five-parameter logistic model for forecasting petroleum consumption in China. The logistic, four-parameter logistic and the newly proposed five-parameter logistic model are applied to the historical data on petroleum consumption in China. The good model fit has indicated that the five-parameter logistic model has performed better than the logistic model and the four-parameter logistic model for forecasting petroleum consumption in China. The forecasted results, based on the five-parameter logistic model, have shown that the petroleum consumption-production gap in China will become larger in the future and the gap will reach over 400 million tons after the year 2033.

Abstract: Measurement of curved surface having large radius of curvature is still a problem for the modern industry measurement. The method of measurement based on laser range finder is a method commonly used in modern industry measurement, which can solve this problem. The system has larger measurement range and higher precision, it belongs to the non-contact measurement systems, so the measured piece could be freely set. Establish an appropriate measurement system based on surface features; obtain the spatial coordinate of the detection points of the measured curved surface through laser ranging; acquire the three-dimensional diagram of the surface features of the curved surface with matlab-based curved surface fitting software; automate the detecting system via the singlechip-based automatic control system. The present device had advantages of high accuracy, convenience and shortcut, low cost and strong adaptability to environmental conditions, which can effectively compensate for the present vacant situation of the portable large curved surface measuring device and have wide applications.

Abstract: Taking roller coaster as the research object, select segmentation fitting to get the curve equation of the track based on the discrete points on the track, use Solidworks and Eon Studio to make model and simulation. Providing a reference for the modeling and simulation of reptile rides by studying track modeling and motion simulation of roller coaster.

Abstract: The accuracy and stability of circular conical surface is easily influenced by the different distribution of noise and points in point cloud, when 3D point cloud data fits conical surface. For this reason, this paper proposes a novel method of establishing and optimizing the objective function with conical vertex. First, calculate the axis direction and half-apex angle of the cone; second, calculate conical vertex according to the result got in the first step; third, establish objective function with axis direction and half-apex angle and vertex, and optimize it with Levenberg-Marquardt. The method’s feasibility and robustness are verified by simulating and real experiments. The proposed algorithm has been successfully applied to a self-development 3D measuring system (TN 3DOMS) of Mianyang Saint Buffalo Technologies Limited Company.

Abstract: For rotational parts with irregular curve profile, in order to achieve its manual programming and machining, we need to segment the contour curve according to the change of curvature. Through the calculation, we can get the minimum arc to fit the segments, and calculate the circular endpoint coordinates and radius by using the drawing methods. Finally, we develop the NC program. By the analysis of the result, we find the method can simplify the programming and improve machining efficiency.

Abstract: A partial discharge (PD) signal processing method based on dynamic measurement theory and wavelet transform is proposed in this paper. The deterministic component was separated by polynomial fitting, and the random component of the remaining residual after the separation was estimated using autoregressive (AR) model; The true value estimate and dynamic measurement uncertainty of noisy signal were obtained by the deterministic component and random component;Db8 wavelet and the soft threshold based on Stein’s Unbiased Estimate of Risk were used to smoothly denoise for better PD signal processing. Finally, the effectiveness of the method was verified by MATLAB simulation and experimental noisy PD signal extraction.

Abstract: To address the fitting spherical surface and evaluating sphericity error, a mathematical model based on the minimum zone principle is presented. And the presented model is answered by GA. An example shows the performance of the proposed method by comparison with the methods based on the least square principle.

Abstract: The physical and chemical characteristics of suspended sediment in Waizhou reach are studied.The particle size is between 0.005-0.75mm.The pH value of sediment sample is 7.1.The desorption experiment after adsorbing total nitrogen(TN) and total phosphorus(TP) saturated was carried out.The experimental results show the desorption of sediment on TN and TP reaches basic equilibrium about 8h.Desorption capacity decreases with the increase of sediment concentration.Desorption process is completed by two steps.The first step is physical desorption process quickly.The second step is chemical desorption and belongs to the process of slow response.Using the Langmuir model can better simulate the process of desorbing.The correlation coefficients of fitting with TN and TP are above 0.8 and 0.75 respectively.The higher the sediment concentration, the better fitting effect.

Abstract: The deformation monitoring data of the dam has the typical characters of instability and nonlinearity after being completed and impounding water. To solve the problems, this paper introduces the time series model and BP neural network model to analysis the dam monitoring data. Firstly, time series model was applied to fit and predict and then used the BP neural network model to correct the nonlinear part of residuals. Finally, we can get a series of fitting and predictive value of the monitoring data by combining of above both models. Taking the certain radial displacement value of a measuring point of a certain dam as an example, ARIMA-BP model was established to analyze the data. The result shows: fitting and predictive accuracy of ARIMA-BP model is relatively high and closed to the measured value.

Abstract: Characteristics of cumulative absolute velocity parameter (CAV) of Lushan earthquake is discussed and presented in this paper. Based on a brief analysis of the background information of the Lushan earthquake, the value of CAV which is calculated from the recorded data of the Lushan earthquake is compared with the commonly used value peak ground acceleration (PGA). Accordingly, the relationship between the CAV and the PGA is studied, and 3 CAV/PGA ratio charts in 3 different sub-directions are obtained. Then the linear fitting operation and the polynomial fitting operation are performed to analyze the potential discipline and characteristics thereof. The applicability of utilizing the CAV parameter in earthquake observation systems is further studied in this paper, and the CAV parameter is cooperated with the currently used value PGA to provide the work of earthquake observation and emergency response with corresponding theoretical basis.