Journal of Engineering and Thermal Sciences
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Optimization of lubrication characteristics of wind turbine’s transmission system based on Newton Raphson method
Get PDFTo improve the reliability and lifespan of wind turbines, this paper takes the two-stage fixed shaft gearbox experimental platform of wind turbines as the research object. Based on Hertz contact theory, the oil film pressure and thickness in the contact area are solved by combining the equations of elastohydrodynamic lubrication and the Newton Raphson method; And the lubrication characteristics of the transmission system were analyzed to verify the correctness of the method; At the same time, in response to partial load phenomenon caused by system coupling deformation, genetic algorithm was selected to modify the gear teeth. The results show that the max unit load on the tooth face and the maximum stress of tooth root decreased by up to 26.48 % and up to 20.35 % respectively after modification which can improve the uneven distribution of oil film and the lubrication performance of the tooth surface
A ball screw all-round error compensation technology based on novel hybrid deep learning for CNC machine tool
Get PDFConsidering the detrimental impact of thermal phenomena on the geometric precision of machine tools, a machine tool ball screw’s omni-directional error model is created using the LSTM neural network algorithm. Subsequently, the machine tool ball screw's omni-directional error compensation module is devised by combining the core functions of the Huazhong numerical control system with the visual programming environment of QT and the numerical computation capability of Matlab. To enhance the practicality and accuracy of the compensation model, this study has employed the Whale Optimization Algorithm (WOA) to optimize the parameters of the LSTM model. This has resulted in an improvement in the model's generalization ability and prediction performance, making it more effective. During the experimental validation phase, the Z-axis error of the machine tool was practically operated and analyzed using the compensation method. Results manifestly show that, after employing the compensation method, the peak amplitude of the Z-axis error fluctuations have been notably curtailed to ±0.006 mm – a considerable reduction compared to the initial error bandwidth of ±0.0145 mm. These empirical findings substantiate the efficacy of the proposed compensation strategy in substantially boosting the machining precision of products, thus furnishing a substantial and instructive benchmark for future inquiries into CNC machine tool error compensation technologies
Analysis of a bus vertical dynamic performances – a comparison between linear and nonlinear suspension systems
Get PDFThis paper mainly focuses on the numerical calculation to determine the vertical evaluation indexes with all three types of typical harmonic, transient and random road excitations. The effects of linear and nonlinear suspension characteristics on the vertical evaluation indexes are fully understood systematically. The ride comfort, suspension working space, and road holding are analyzed for both two cases of linear and nonlinear suspension systems. The improvement of the vertical stability and road holding in the case of nonlinear suspension subjected under three different excitations could be characterized most meaningfully. The obtained results help to systematically get full understanding of the investigated problem nature. It also should guide interested readers in suspension design to improve the stability, safety, and ride comfort of buses
The system for adaptive control of axial tool oscillations in vibratory drilling: description and experimental study
Get PDFChips must be reliably segmented and evacuated from the cutting zone for effective deep hole drilling. Drilling with low-frequency axial vibrations ensures these useful effects because cutting edges periodically leave the cutting zone. Useful tool vibrations can be maintained using a special self-vibratory drilling head. The drilling head has an elastic element and ensures the self-excitation of vibrations due to the regenerative effect. However, high damping in the cutting zone suppresses axial self-vibrations and renders such a drilling head inexpedient for industry. This study develops a novel system of adaptive control for the vibration drilling process. The control objective is to maintain a specified peak-to-peak (PTP) value of vibration displacements. Due to the in-process adaptation of the feedback gain, the control system supplies additional energy if vibrations are not self-excited and removes energy if the PTP vibration displacements are greater than the specified value. To test the workability of the system, an experimental setup was made. In the setup, the actuator force acts on an elastically fixed workpiece. The dynamic properties of the setup are equivalent to those of the vibration drilling head. The algorithm of feedback gain adaptation was implemented with a microcontroller. A number of experiments for different drilling regimes revealed that the control system successfully maintains the specified PTP value of displacements. The developed control system can be implemented on a vibration drilling head because only an accelerometer is required for control and the required actuator force is under 100 N
Seismic performance of building structures based on improved viscous damper seismic design
Get PDFEarthquakes have serious destructive effects on building structures, and effective seismic design is the key to building design. In order to reduce the damage of earthquakes to building structures, seismic design of buildings is based on improved viscous dampers. First, the displacement seismic design was studied and a displacement-based structural seismic model was constructed. In addition, analyzing traditional viscous dampers, an improved viscous damper is adopted based on it. Through equivalent damping expression, a displacement seismic model based on the improved viscous damper is constructed. Finally, two targets, frequent and rare earthquakes, were selected for experimental analysis. In frequent earthquake experiments, the improved viscous damper structure increased the shock absorption rate by 35.65 % compared to the no-structure design. In the shear force comparison, the maximum shear force of the improved viscous damper structure in the HB wave X direction is 2186 KN, which is the smallest shear force among the three structural designs. In a rare earthquake experiment, the maximum value of the floor shear force in the X-direction of the Humbolt bay wave of the proposed improved viscous damper structure was 8696 KN. Compared with other structures, the floor shear force was the smallest. In the comparison of floor displacements, the maximum inter-story displacement in the Humbolt bay wave Y-direction of the proposed improved viscous damper structure is 162 mm, which is the smallest inter-story displacement compared with other structures. In addition, the structure apex displacement was also compared. The structure apex displacement value of the improved viscous damper structure was lower than that of other structures and was in the slight damage range. The overall seismic effect was significantly better than other structural designs. The research content is conducive to optimizing the application effect of viscous dampers and provides technical reference for the seismic design of building structures
Research on modulation recognition method of electromagnetic signal based on wavelet transform convolutional neural network
Get PDFThe method of electromagnetic signal modulation recognition based on wavelet transform convolutional neural network is studied to improve the effect of electromagnetic signal modulation recognition. By analyzing the electromagnetic signal modulation model, the original electromagnetic signal is preprocessed by wavelet transform to remove the noise of the original electromagnetic signal. The processed electromagnetic signal is used as the input of convolutional neural network, and the electromagnetic signal feature vector is extracted through the convolution layer of convolutional neural network. By using full connection operation, the advanced feature vector of electromagnetic signal is integrated, and the electromagnetic signal is classified by softmax function, and the electromagnetic signal modulation recognition result is output, thus realizing the electromagnetic signal modulation recognition. The experimental results show that when the number of layers of wavelet decomposition is 7 and the wavelet function is Db9, the wavelet transform has the best denoising effect on electromagnetic signal data. At the same time, the network training efficiency of this method is high, and the accuracy of electromagnetic signal modulation recognition is as high as 97.2 %, which improves the effect of electromagnetic signal modulation recognition and is suitable for various types of electromagnetic signal modulation recognition
Development of a rotation and swing torque detection system after bearing installation
Get PDFThe swing torque and rotational torque after the spherical bearing is installed directly affect the performance of the spherical bearing. At this stage, the friction torque detection equipment of the spherical bearing is mainly used to detect uninstalled bearings. A set of rotation and swing after the bearing is installed is designed. Torque detection system. The detection principles of rotational torque and swing torque required for flexibility detection were analyzed, the functional design requirements and main technical indicators of the detection system were clarified, and the overall design plan of the detection system was established; the host structure of the detection system was designed, including rotational torque detection system, swing torque detection system, clamping system and calibration system; completed the scheme design of the detection control system, selected the torque sensor and servo motor, designed the main electrical control circuit of the detector; conducted error analysis of the detector
Common fixed-point theorem for commuting maps on a metric space
Get PDFSeveral novel uses of theorems for fixed points in commuting mapping in a fully metric domain are presented. Several conclusions from full metric fixed point theory are improved and extended by our work. Our proofs are inspired by the study of commuting mappings [B. Fisher and S. Sessa, on a fixed point theorem of Gregus, 1986] and [P. Sumati Kumari, Fixed and periodic point theory in certain spaces, 2013]
Analysis of compression deformation of water-lubricated bearing material based on rigid and flexible substances coupled with microstructure
Get PDFWater-lubricated bearings are pivotal components in ship propulsion shafting, The mechanical properties of composite materials serve as the foundation for water-lubricated bearing materials. In this paper, taking the 3D composite structure material of arthropod outer carapace as a biological model, a bionic design of a water-lubricated bearing composite material based on rigid and flexible substances coupled with microstructure is proposed, and its load-carrying properties are analyzed through simulation and experimentation. The research results showed that the rigid fiber helix angle of 30° would be better for enhancing mechanical performance. When the basic parameters of the RVE (representative volume elements) are determined, the arrangement of it will also affect the mechanical properties of the composite material to a certain extent, and from the test results, the three RVEs combination mode can obtain better bearing capacity
Crack recognition and defect detection of assembly building constructions for intelligent construction
Get PDFVision-assisted surface defect detection technology is shallowly applied in crack identification of assembly building components, for this reason, the study proposes a crack identification and defect detection method for assembly building components oriented to intelligent construction. An image preprocessing algorithm is designed by improving bilateral filtering, on the basis of which an image classification model is constructed using the GhostNet algorithm, and the cracks are localized and measured using the 2D pixel positioning technique. Algorithm validation showed that the processed image denoising is better, and the peak signal-to-noise ratio of the image of the proposed algorithm is improved by 15.701 % and 2.395 %, respectively, compared to other algorithms. The F1 value of the proposed model after 50 training rounds increased by 20.970 % on average compared to other models, and the detection accuracy was as high as 0.990. The actual measurements of cracks in concrete wall panels revealed that the research-proposed method has better results compared to the traditional manual measurements, and is not subject to the limitations and interferences of factors such as manual experience, and it is more effective in the recognition of crack images. Overall, the detection method proposed by the study has high accuracy and small error, can meet the needs and standards of crack detection in assembly building components, and can intelligently locate the maximum length and width coordinates of the cracks, which is of high value in the application of crack detection in assembly building components