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Investigation of strengthening mechanism of commercially pure titanium joints fabricated by autogenously laser beam welding and laser-MIG hybrid welding processes
摘要： In this study, in order to achieve a better understanding of the strengthening mechanism in the commercially pure (CP) Ti welds, autogenously laser beam and laser-MIG hybrid welding of 4.2 mm thick CP-Ti plates were performed and the correlation between microstructure, texture distribution and the mechanical properties were systematically investigated. Microstructural coarsening and increase in microhardness were observed in the HAZ and WZ. The tensile test results suggested the base metal was the weak point of the joint for both welding conditions. The EBSD observations confirmed that a large number of 1012 and 1122 twin grains occurred in the HAZ and WZ of both welded joints, while a higher concentration of these twin grains were found in the laser-MIG hybrid joints. High concentration of the twin grain boundaries can act as barrier to stop dislocation slip during deformation and therefore contribute to the strengthening of the welds. The existence of very small twin grains and acicular α phase in HAZ and WZ would equivalently reduce the averaged grain size and therefore induce an increase in strength based on Hall-Petch’s law. In addition, the averaged Schmid factor of BM is higher than that of the WZ and HAZ in both welding joints suggesting that the grain boundary sliding will take place preferably in BM during deformation so that the necking and fracture occurred in base metal during tensile tests of both welding joint specimens.
关键词： Texture,Mechanical property,Laser-MIG hybrid welding,Strengthening mechanism,Commercially pure titanium,Laser beam welding,Microstructure
更新于2025-11-28 14:24:20
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High-performance potassium-sodium niobate lead-free piezoelectric ceramics based on polymorphic phase boundary and crystallographic texture
摘要： Lead-free piezoelectric ceramics are urgently needed in the field of electromechanical conversion devices due to the restriction on the use of lead-based ceramics. In this study, the polymorphic phase boundary (PPB) were tuned by incorporating different concentration of (Bi0.5K0.5)HfO3 into the matrix (K0.5Na0.5)(Nb0.965Sb0.035)O3-CaZrO3, and the <00l>c crystallographic texture was realized by templated grain growth method. The maximal d33 (~550 pC/N) and kp (~72%) were achieved in the <00l>c textured ceramics with composition around rhombohedral-orthorhombic-tetragonal (R-O-T) phase boundary. It is proposed that the enhanced piezoelectricity should be ascribed to several combined effects, which primarily contain the R-O-T phase boundary facilitating polarization rotation, the crystallographic orientation induced intrinsic piezoelectric anisotropy, electric-field-induced lattice distortion and phase transitions, and NaNbO3 seed-crystal-driven nanodomain structures. This work provides an effective solution to enhance piezoelectric properties by simultaneous tailoring polymorphic phase boundary and using crystallographic texture in potassium-sodium niobate based piezoelectric ceramics. We believe that the simple solution and design principle can also be applied to other piezoelectric ceramic systems, no matter lead-based or lead-free.
关键词： polymorphic phase boundary,piezoelectricity,potassium-sodium niobate,crystallographic texture
更新于2025-11-14 17:28:48
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Texture features analysis on micro-structure of paste backfill based on image analysis technology; 基于图像识别技术的膏体微观结构纹理特征分析;
摘要： The strength of cement-based materials, such as mortar, concrete and cement paste backfill (CPB), depends on its microstructures (e.g. pore structure and arrangement of particles and skeleton). Numerous studies on the relationship between strength and pore structure (e.g., pore size and its distribution) were performed, but the micro-morphology characteristics have been rarely concerned. Texture describing the surface properties of the sample is a global feature, which is an effective way to quantify the micro-morphological properties. In statistical analysis, GLCM features and Tamura texture are the most representative methods for characterizing the texture features. The mechanical strength and section image of the backfill sample prepared from three different solid concentrations of paste were obtained by uniaxial compressive strength test and scanning electron microscope, respectively. The texture features of different SEM images were calculated based on image analysis technology, and then the correlation between these parameters and the strength was analyzed. It was proved that the method is effective in the quantitative analysis on the micro-morphology characteristics of CPB. There is a significant correlation between the texture features and the unconfined compressive strength, and the prediction of strength is feasible using texture parameters of the CPB microstructure.
关键词： cement paste backfill,unconfined compressive strength,Tamura texture,microstructure,quantitative analysis,texture feature,GLCM feature
更新于2025-09-23 15:23:52
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[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - Tree-Shaped Sampling Based Hybrid Multi-Scale Feature Extraction for Texture Classification
摘要： Efficiency, distinctiveness and robustness are three main goals for feature extractors in application of texture classification. In this paper, a new feature extractor is designed which aims to achieve these three goals simultaneously. The contributions are threefold. Firstly, a tree-shaped multi-scale sampling structure is proposed to acquire points distributed along two circles and one octagon. Secondly, four histogram vectors are obtained by quantizing the sampling values through a hybrid strategy. In order to suppress the noise, mean filtering is used as a preprocessing step and the four vectors are concatenated to form the discriminant vector. Thirdly, experiments are conducted on different datasets with several well-known feature extractors. The results show that the proposed method improves the classification accuracy effectively and robustly, while has a moderate complexity. The source code is available at: https://github.com/madd2014/TSSHM.
关键词： texture classification,Feature extraction,multi-scale structure,tree-shaped sampling
更新于2025-09-23 15:23:52
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Tailoring metal film texture by use of high atomic mobility at metal-semiconductor interfaces
摘要： The difference in the microstructural and texture evolution of Al films grown on amorphous SiO2 (a-SiO2) and amorphous Ge (a-Ge) substrates have been investigated. Surprisingly, the a-Ge substrate was found to change the preferred orientation of Al grains from the conventional (1 1 1) to the unconventional (1 1 0). The effect of the high mobility of Ge atoms at the metal-semiconductor interface on the microstructural and texture evolution of the metal thin film was studied. The diffusion of the Al adatoms on the a-Ge substrate was suppressed owing to the segregation of Ge atoms at the film surface. The mobility of Al grain boundaries was also suppressed because of grain-boundary wetting by the Ge atoms. It is concluded that the a-Ge substrate could tailor the Al grain orientation from (1 1 1) to (1 1 0) owing to the change in the film-growth mode from three-dimensional to two-dimensional nucleation. The concept of interaction-induced island-growth model, which is based on the Volmer–Weber growth model, is also discussed here. This work thus demonstrates how the atomic mobility at the interface of the metal thin film and the semiconductor substrate controls the film microstructure and texture during deposition.
关键词： Substrate,Microstructure,Surface diffusion,Texture,Metal thin film,Grain-boundary wetting
更新于2025-09-23 15:23:52
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A novel adaptive image zooming method based on nonlocal Cahn–Hilliard equation
摘要： Recently, nonlocal operator has become a very hot topic in image processing. For nonlocal partial differential equations (PDEs) methods, almost existed models are based on second order. In this paper, a novel image zooming method based on nonlocal fourth-order PDEs is proposed. The proposed method comprehensively utilizes the characteristic of the higher order PDEs-Cahn-Hilliard equation and the nonlocal operator. Higher order PDEs can well alleviate blocking artifacts and decrease the influence of the noise, and the nonlocal operator has a good performance on texture preserving and can reduce Gaussian noise. In the proposed model, a control parameter is introduced, which can control the speed of the model diffusion. Experimental results show that the proposed method has a good ability for de-noising and texture preserving.
关键词： Cahn-Hilliard equation,fourth-order,texture preserving,nonlocal operator
更新于2025-09-23 15:23:52
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Optimal target sputtering mode for aluminum nitride thin film deposition by high power pulsed magnetron sputtering
摘要： Low surface roughness, low residual stress, and (002) textured aluminum nitride (AlN) thin films are favored for applications in microelectronic and optoelectronic devices. In this paper, AlN thin films were deposited by reactive high power pulsed magnetron sputtering (HPPMS). The effect of aluminum target sputtering mode and sputtering power on thin film residual stress, crystalline structure, surface roughness, and morphology of AlN thin films was studied. The results indicate that, with Al target sputtering mode transfer from metallic mode to transitional and compound modes, respectively, the number of Al species decrease, and ion-to-neutral ratio of Al species increase. Comparing the AlN thin film deposited in compound mode with that deposited in transitional mode, the latter exhibited lower surface roughness and residual stress. In addition, AlN thin film with (002) texture and lower residual stress is obtained by increasing sputtering power in transitional mode. For fabricating AlN film via reactive HPPMS with a particular (002) texture, low surface roughness, and residual stress, sputtering the target in the transitional mode with high sputtering power is optimal.
关键词： Aluminum nitride,Microstructure,Texture,High power pulsed magnetron sputtering,Sputtering modes,Sputtering power
更新于2025-09-23 15:23:52
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Breast tumor classification using different features of quantitative ultrasound parametric images
摘要： Rationale and objectives The ultrasound B-mode-based morphological and texture analysis and Nakagami parametric imaging have been proposed to characterize breast tumors. Since these three feature categories of ultrasonic tissue characterization supply information on different physical characteristics of breast tumors, by combining the above methods is expected to provide more clues for classifying breast tumors. Materials and methods To verify the validity of the concept, raw data were obtained from 160 clinical cases. Six different types of morphological-feature parameters, four texture features, and the Nakagami parameter of benignancy and malignancy were extracted for evaluation. The Pearson’s correlation matrix was used to calculate the correlation between different feature parameters. The fuzzy c-means clustering and stepwise regression techniques were utilized to determine the optimal feature set, respectively. The logistic regression, receiver operating characteristic curve, and support vector machine were used to estimate the diagnostic ability. Results The best performance was obtained by combining morphological-feature parameter (e.g., standard deviation of the shortest distance), texture feature (e.g., variance), and the Nakagami parameter, with an accuracy of 89.4%, a specificity of 86.3%, a sensitivity of 92.5%, and an area under receiver operating characteristic curve of 0.96. There was no significant difference between using fuzzy c-means clustering, logistic regression, and support vector machine based on the optimal feature set for breast tumors classification. Conclusion Therefore, we verified that different physical ultrasonic features are functionally complementary and thus improve the performance in diagnosing breast tumors. Moreover, the optimal feature set had the maximum discriminating performance should be irrelative to the power of classifiers.
关键词： Morphological features,Breast ultrasound,Nakagami parameter,Texture features,Classification
更新于2025-09-23 15:23:52
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Determination of diffraction time and influence of strip moving speeds on texture measurement using X-ray area detector
摘要： In this study, the two most important factors, diffraction time and the influence of the strip moving speed on diffraction accuracy, are analyzed using a laboratory two-dimensional X-ray diffraction system. The results indicate that 2 s is a diffraction time that satisfies both requirements of detection speed and accuracy. The strip moving speed has a certain influence on the detection accuracy, but the influence of the strip moving speed on the diffraction accuracy can be neglected within a strip moving speed of 0.65 m/s. The measurement of online texture and mechanical properties, combined with the fast texture detection theory and mechanical properties calculation model, can be realized in a steel production factory.
关键词： fast texture detection,diffraction time,X-ray area detector,strip moving speeds
更新于2025-09-23 15:23:52
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A Novel Method for Compensating Temperature Measurement Error Caused by Dust Using Infrared Thermal Imager
摘要： The dust generated in industrial processes has a serious impact on the accuracy of infrared thermometry, which is also the main reason for the limited use of infrared industrial temperature measurement methods applications. To reduce the influence of dust on infrared temperature measurement, this paper proposes a new method for compensating measurement error caused by dust. Firstly, the source of temperature measurement error caused by dust is analyzed, and a compensation method, in which the dust transmittance is important but difficult to determine, is proposed based on the principle of infrared temperature measurement. Then, to solve the difficulty of determining dust transmittance, we define a spatial temperature level co-occurrence matrix and a neighboring temperature level dependence matrix which can be utilized to extract the infrared thermal image’s texture features affected by dust. Finally, by integrating stacked denoising auto-encoder with optimized parameters and support vector regression, a dust transmittance model is established to determine dust transmittance based on the extracted features. Experimental results indicate that the proposed compensation method can reduce the influence of dust on infrared thermal imager’s accuracy effectively.
关键词： temperature measurement,dust transmittance,dust,texture feature,Compensation model,infrared thermal imager
更新于2025-09-23 15:23:52