Owing to the dependence of algorithms on the measurement of ship soundings and geophysical parameters, the accuracy and coverage of topography still need to be improved. Previous studies have mostly predicted topograp...
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Owing to the dependence of algorithms on the measurement of ship soundings and geophysical parameters, the accuracy and coverage of topography still need to be improved. Previous studies have mostly predicted topography using gravity or gravity gradient, However, there is a relative lack of integrated research combining or comparing gravity and gravity gradient. In this study, we develop observation equations to predict topography based on vertical gravity anomalies (VG;also called gravity anomalies) and vertical gravity gradient (VGG) anomalies generated by a rectangular prism. The sources of interference are divided into medium- to high-frequency errors and low-frequency errors, and these new methods reduce these errors through regularization and error equations. We also use numerical simulations to test the efficiency of the algorithm and error-reduction method. Statistics show that VGG anomalies are more sensitive to topographic fluctuations;however, the linear correlation between VG anomalies and topography is stronger. Additionally, we use the EIGEN-6C4 model of VG and VGG anomalies to predict topography in shallow and deep-sea areas, with maximum depths of 2 km and 5 km, respectively. In the shallow and deep-sea areas, the root mean square (RMS) errors of VGG anomalies prediction are 93.8 m and 233.8 m, and the corresponding accuracies improved by 7.3% and 2.3% compared with those of VG anomaly prediction, respectively. Furthermore, we use cubic spline interpolation to fuse ship soundings and improve the accuracy of the final topography results. We develop a novel analytical algorithm by constructing an observation equation system applicable to VG and VGG anomalies. This will provide new insights and directions to refine topography prediction based on VG and VGG anomalies.
Many assembly modes exist due to multi-solutions for forward kinematics of 6-UPS parallel robot. However, the existing theoretical research results have not been well applied to the real-time control, because of the c...
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Many assembly modes exist due to multi-solutions for forward kinematics of 6-UPS parallel robot. However, the existing theoretical research results have not been well applied to the real-time control, because of the complexity of the forward kinematics. This paper proposes an analytic algorithm to establish the forward kinematics model of a 6-UPS parallel robot with an extra displacement sensor mounted on the centers of upper and lower platform ((6+1)-UPS). Based on the unit quaternion method, the improved forward kinematics model of the proposed (6+1)-UPS system is theoretically derived to be four equations about four components of unit quaternion. The whole computation process is analytical. The method of measurement of the 7th link length and the utilization of unit quaternion reduces the complexity of computation process of forward kinematics, avoids the computer memory spillover and increases the computation efficiency to be suitable for the real-time control application. Then, the analytical solution of the position vector and orientation matrix of the (6+1)-UPS parallel robot are obtained. Finally, the correctness and effectiveness of the proposed approach are illustrated with a numerical example.
This paper proposes a simple analytical method for determining the viscosity index (VI) that effectively aligns with results obtained from the applicable standards. This method simply needs the kinematic viscosity of ...
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This paper proposes a simple analytical method for determining the viscosity index (VI) that effectively aligns with results obtained from the applicable standards. This method simply needs the kinematic viscosity of the tested oil at 40 and 100 degrees C as input parameters and does not need to use tables that are an integral part of the mentioned standards. This work presents a method and evaluates the accuracy of determining auxiliary parameters in the form of kinematic viscosity values at 40 degrees C for two hypothetical oils. These oils have a kinematic viscosity at 100 degrees C equal to that of the oil under testing and have VI = 0 and 100. The relative fitting error percentage and the coefficient of determination are found for the specified auxiliary indicators. The method is validated using data obtained from previous studies in the form of the kinematic viscosity of lubricating oil-diesel mixtures. The mixtures of viscosity grades SAE 30 and SAE 40 lubricating oil with diesel oil at concentrations of 0, 1, 2, 5, 10, 20, and 50% w/w are tested. The viscosity index for each mixture is determined using a standard-based manual calculation using the Anton Paar viscosity index calculator and the proposed method. The results obtained from the proposed analytical method are compared with those from two other methods. The maximum percentage relative fitting error (delta(max) approximate to 1%) and the coefficient of determination (R-2 > 0.999) are determined. The obtained results demonstrate a very good fit and, thus, confirm the usefulness of the proposed approach.
In order to provide a complete solution for designing and analyzing the axial flux permanent magnet synchronous motor (AFPMSM) for electric vehicles, this paper covers the electromagnetic design and multi-physics anal...
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In order to provide a complete solution for designing and analyzing the axial flux permanent magnet synchronous motor (AFPMSM) for electric vehicles, this paper covers the electromagnetic design and multi-physics analysis technology of AFPMSM in depth. Firstly, an electromagnetic evaluation method based on an analytical algorithm for efficient evaluation of AFPMSM was studied. The simulation results were compared with the 3D electromagnetic field simulation results to verify the correctness of the analytical algorithm. Secondly, the stator core was used to open the auxiliary slot to optimize the torque ripple of the AFPMSM, which reduced the torque ripple peak-to-peak value by 2%. From the perspective of ensuring the reliability, safety, and driving comfort of the traction motor in-vehicle working conditions, multi-physics analysis software was used to analyze and check the vibration and noise characteristics and temperature rise of several key operating conditions of the automotive AFPMSM. The analysis results showed that the motor designed in this paper can operate reliably.
The deterioration due to surface cracks-like flaws is an important phenomenon for the safety point of view. Thus, the main aim of the present research work is to investigate the plate failure caused by a quarter-ellip...
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The deterioration due to surface cracks-like flaws is an important phenomenon for the safety point of view. Thus, the main aim of the present research work is to investigate the plate failure caused by a quarter-elliptical corner crack under cyclic loading. A developed analytical algorithm integrates fracture-mechanics-based formulae, and allows to relate the crack growth rate together with the stress intensity at the crack tip and to estimate the fatigue life of structural components. Experimentally verified outcomes show that the proposed computational algorithm represents a powerful tool in the fatigue failure design.
The fan-beam short-scan filtered backprojection (FBP) algorithm is popular in the computed tomography (CT) industry and in clinical applications. This paper points out that the fan-beam short-scan FBP algorithm is not...
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The fan-beam short-scan filtered backprojection (FBP) algorithm is popular in the computed tomography (CT) industry and in clinical applications. This paper points out that the fan-beam short-scan FBP algorithm is not exact, even in an ideal noiseless situation. The error depends on the focal length of the imaging geometry. When the focal length is long enough, the error is small and can therefore be ignored.
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