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In order to solve the problem of optimizing the test stress points of the ladder three stress accelerated degradation test plan with stress coupling for motorized spindles, an optimization design method of non-cube test area is proposed based on Escobar Meeker design method. Firstly, the performance index monitored in the test is determined according to the self-structure and fault data of the motorized spindle. The specific expression of the accelerated degradation model of the motorized spindle is determined by using the Pearson correlation coefficient and the Akaike information criterion, and then the three stress accelerated degradation model of the motorized spindle with stress coupling term is established. Based on the limit stress test and the real working conditions, the establishment method of the non-cube test area of the motorized spindle is proposed; and based on this test area, the properties of the Escobar Meeker design method are improved, so as to put forward the optimization design method of the ladder three stress accelerated degradation test plan of the motorized spindle with stress coupling under this test area. Finally, the availability of the method is verified by the optimization design of the test plan of motorized spindle made in China, and the optimization results are compared with the optimization results of uniform design to verify the effectiveness of the method. [ABSTRACT FROM AUTHOR]

Photometric camera calibration is often required in physics-based computer vision. There have been a number of studies to estimate camera response functions (gamma function), and vignetting effect from images. However less attention has been paid to camera spectral sensitivities and white balance settings. This is unfortunate, since those two properties significantly affect image colors. Motivated by this, a method to estimate camera spectral sensitivities and white balance setting jointly from images with sky regions is introduced. The basic idea is to use the sky regions to infer the sky spectra. Given sky images as the input and assuming the sun direction with respect to the camera viewing direction can be extracted, the proposed method estimates the turbidity of the sky by fitting the image intensities to a sky model. Subsequently, it calculates the sky spectra from the estimated turbidity. Having the sky $$RGB$$ values and their corresponding spectra, the method estimates the camera spectral sensitivities together with the white balance setting. Precomputed basis functions of camera spectral sensitivities are used in the method for robust estimation. The whole method is novel and practical since, unlike existing methods, it uses sky images without additional hardware, assuming the geolocation of the captured sky is known. Experimental results using various real images show the effectiveness of the method. [ABSTRACT FROM AUTHOR]

The thermal error is a significant factor that influences the machining accuracy of machine tools, and error compensation is an economical and effective method for enhancing the accuracy of machine tools. However, establishing a precise thermal error prediction model is crucial for thermal error compensation. In this paper, the subtraction-average-based optimizer-based CNN-GRU neural network (SABO-CNN-GRU) is applied to integrated thermal error modeling. Through conducting a thermal characteristic experiment, temperature rise data and thermal error data were collected from the linear feed system of LXK300X helical groove CNC machine tool. The fuzzy c-means clustering and grey correlation analysis are employed to identify temperature-sensitive points in the linear feed system. By utilizing the temperature rise data from these sensitive points along with feed shaft thermal errors as data samples, and using the SABO algorithm to optimize the CNN-GRU prediction model, the thermal error prediction model of SABO-CNN-GRU is established. To validate its superiority and practicality, a comparative analysis is conducted with traditional thermal error prediction models based on CNN-GRU and SO-ELM. The results demonstrate that SABO-CNN-GRU model outperforms both models in terms of mean absolute error (MAE), root mean square error (RMSE), remaining prediction deviation (RPD), mean square error (MSE), and determination coefficient (R2) in accurately predicting results. Building upon this achievement, this paper develops a real-time thermal error compensation system which effectively reduces maximum thermal errors from 80.5 to 17.6 μm after implementing compensation measures. Effectively reducing the influence of thermal errors and improving the machining accuracy of machine tools. [ABSTRACT FROM AUTHOR]

To investigate the machining mechanism of silicon carbide (SiC) ceramic materials, this study utilized sintered diamond tools to perform drilling and grinding simulations on the material and developed a drilling model for SiC ceramic materials. By analyzing parameters such as surface morphology, stress, and cutting force, the material removal mechanism of SiC ceramic materials was revealed, and the effects of drilling parameters on cutting force, torque, and residual stress were studied. Experimental results indicate that during the abrasive cutting process, the hard contact behavior of irregular abrasive grains significantly affects material removal, leading to failure forms such as chip collapse, hole and groove cracking, and crack propagation. With an increase in the feed rate of the abrasive grains, the drilling force shows a certain range of growth patterns. The axial force is positively correlated with spindle speed and feed rate, with the feed rate having a more significant impact on the magnitude of the axial force. Additionally, as the feed rate increases, the torque also increases. The radial residual stress mainly manifests as residual tensile stress. [ABSTRACT FROM AUTHOR]

The nano-cutting process of metallic glass (Zr52Cu20Ni16Ni12) processed at room temperature was studied by molecular dynamics simulation in this paper. At different cutting speeds, the microstructure of metallic glass, cutting force, strain morphology of cutting zone, temperature change of cutting zone and its influence on the quality of machined surface were analyzed. The simulation results show that the cutting speed has little effect on the content of Voronoi polyhedron in the cutting area of metallic glass. The cutting force increases significantly with the increase of cutting speed. The shape of strain deformation in the cutting zone of metallic glass material is significantly affected by the cutting speed, and the influence depth of strain is deepened with the increase of cutting speed. The increase of cutting speed has a significant effect on the temperature of the cutting zone of metallic glass, and the temperature of atoms in the cutting zone increases rapidly. The cutting speed has a significant impact on the surface quality of metal glass cutting. The surface quality of metal glass cutting becomes worse with the increase of cutting speed. In particular, the initial stage of plastic deformation in metal glass cutting process is simulated and analyzed, and the formation and evolution of its shear band and free volume are simulated and studied. [ABSTRACT FROM AUTHOR]

To investigate the effect of microscale grinding on the quality of ITO conductive glass, this paper conducted microscale grinding experiments on ITO conductive glass. The influence of process parameters on machining quality was analyzed using microgrinding force, surface roughness, and sheet resistance as indicators. Meanwhile, soda-lime glass was set as the control group to analyze the effect of ITO film. The results indicate that brittle fracture is the main removal method for ITO films, and the glass substrate exhibits two different removal methods, brittle and ductile, depending on the process parameters. The ITO thin film layer suppresses the sheet deformation of the glass substrate, increasing the grinding force and reducing the processing quality. Increasing the spindle speed, reducing the feed speed, and reducing the cutting depth can improve the machining quality. The spindle speed has a significant impact on surface roughness, while the cutting depth has a significant impact on the sheet resistance of the thin film. In addition, soda-lime glass chips mainly appear in powder and granular form, while ITO conductive glass also has flaky thin film chips generated by interlayer fracture. [ABSTRACT FROM AUTHOR]