A visual sensing system was established to monitor the weld pool in laser spot welding. The top-hat and bottom-hat transformation algorithms based on mathematical morphology were used to compensate for non-uniform con...A visual sensing system was established to monitor the weld pool in laser spot welding. The top-hat and bottom-hat transformation algorithms based on mathematical morphology were used to compensate for non-uniform contrast of weld pool edge. Moreover, the canny edge detector was applied to extract the weld paol profile. The edge detected results show that the morphological operation is obviously superior to the traditional contrast enhancement method. In addition, the combination of dilation and erosion was applied to eliminate the irrelevant edge details, and the smooth weld pool edge was acquired. Based on the image processing technology described above, the dynamic process of weld pool diameter during laser spot welding was obtained.展开更多
A visual sensing system was developed. The system is suitable for titanium-alloy electron-beam welding, and senses and detects molten-pool dynamic processes. A suite of processing programs for colored molten-pool imag...A visual sensing system was developed. The system is suitable for titanium-alloy electron-beam welding, and senses and detects molten-pool dynamic processes. A suite of processing programs for colored molten-pool images in titanium-alloy electron-beam welding was developed using Matlab software; molten-pool edge images are completely obtained using the program. The Matlab software was used to write a program which could extract the molten-pool width. The functional relationship between the molten-pool width and penetration under the experimental conditions was obtained by a curve-fitting method, and provided the theoretical basis for further penetration control.展开更多
Methods of arc length control and visual image based weld detection for precision pulse TIG welding were investigated. With a particular all hardware circuit, arc voltage during peak current stage is sampled and inte...Methods of arc length control and visual image based weld detection for precision pulse TIG welding were investigated. With a particular all hardware circuit, arc voltage during peak current stage is sampled and integrated to indicate arc length, deviation of arc length and adjusting parameters are calculated and output to drive a step motor directly. According to the features of welding image grabbed with CCD camera, a special algorithm was developed to detect the central line of weld fast and accurately. Then an application system were established, whose static arc length error is ±0.1 mm with 20 A average current and 1 mm given arc length, static detection precision of weld is 0.01 mm , processing time of each image is less than 120 ms . Precision pulse TIG welding of some given thin stainless steel components with complicated curved surface was successfully realized.展开更多
Color-changeable smart textiles capable of converting external stimulus into change in eye-perceptible colors are promising for visual sensor and wearable devices.However,conventional color-changeable smart textiles b...Color-changeable smart textiles capable of converting external stimulus into change in eye-perceptible colors are promising for visual sensor and wearable devices.However,conventional color-changeable smart textiles based on functional chemical dyes suffer the narrow-ranged color shifting and hence the bad visual interaction resolution.In this work,inspired by that chameleon rapidly tuning skin iridescence through active tuning of guanine nanocrystal spacing,a full-color-changeable textile equipped with a cholesteric photonic skin is developed via layer-by-layer assembly strategy by using sustainable nanocellulose as photonic ink to work with graphene oxide as light absorber and polyvinyl alcohol as plasticizer.After assembled,a multi-phase layered stacking coupled with Janus surface structure forms,hence generating structural synergic effects bringing multi functions for the resulting photonic textile,including flexible optical adjustability,strong-tough combination,hydration-setting formability,and progressive wettability.More impressively,resultant photonic textiles present wide-ranged color-shifting capability with a high identifiability outperforming most of conventional color-changeable textiles,demonstrating great feasibility to monitor the directional water transport process,diverse organic componence volatilization,and ambient humidity,in a naked-eye-readable,real-time,and quantifiable manner.展开更多
A passive visual sensing system is established in this research, and clear weld pool images in pulsed gas metal arc welding （ P-GMA W） can be captured with this system. The three-dimensional weld pool geometry, espe...A passive visual sensing system is established in this research, and clear weld pool images in pulsed gas metal arc welding （ P-GMA W） can be captured with this system. The three-dimensional weld pool geometry, especially the weld height, is not only a crucial factor in determining workpiece mechanical properties, but also an important parameter for reflecting the penetration. A new three-dimensional （3D） model is established to describe the weld pool geometry in P-GMAW. Then, a series of algorithms are developed to extract the model geometrical parameters from the weld pool images. Furthermore, the method to reconstruct the 3 D shape of weld pool boundary and weld bead from the two-dimensional images is investigated.展开更多
In the vision monitoring or controlling the arc welding process, it is a prerequisite to get a clear image of weld pool. However, the disturbance of arc radiation makes imaging of weld pool difficult and optical filte...In the vision monitoring or controlling the arc welding process, it is a prerequisite to get a clear image of weld pool. However, the disturbance of arc radiation makes imaging of weld pool difficult and optical filters are usually used to improve the image quality. In this paper, a radiometric imaging model is established to investigate the influence of the filter on the image quality of the weld pool, in which the spectral distribution of weld pool radiation, the spectral transmittance of the filter, the spectral sensitivity of the camera are all considered. With the proposed model, the influence of the factors on weld pool imaging can be inferred and the selection of optical filters is discussed.展开更多
Human visual sense has two aspects in our feeling for blurred image, that is, one is the amount of blur depending on object size, the other is the amount of blur independent of the object size. In the former for examp...Human visual sense has two aspects in our feeling for blurred image, that is, one is the amount of blur depending on object size, the other is the amount of blur independent of the object size. In the former for example, when the image size becomes larger, the author feels smaller amount blur. The quantitative evaluation based on entropy for blurred images is proposed in this paper. The author calls this metric ＂variation entropy＂. This metric has two kinds of aspects that coincide with the human visual sense. The first is the absolute evaluation of blur, and the second is the relative evaluation of blur. The former can be quantified by variation entropy for a unit boundary length （or L-type variation entropy： HL ）, which is dependent on resolution, and the latter can be quantified by variation entropy for a unit area （or A-type variation entropy： H^A ）, which is independent of resolution. These two metrics have complementary properties. At last, two variation entropies are applied to the standard kanji character database, and then the strong relation between variation entropy and accuracy of recognition is discussed. The tendency of writing skills for grades is evaluated by applying the metric to a database collected from school children.展开更多
Calcium ions(Ca^(2+))and manganese ions(Mn^(2+))are essential for sustaining life activities and are key monitoring indicators in drinking water.Developing highly sensitive,selective,and portable detection methods for...Calcium ions(Ca^(2+))and manganese ions(Mn^(2+))are essential for sustaining life activities and are key monitoring indicators in drinking water.Developing highly sensitive,selective,and portable detection methods for Ca^(2+)and Mn^(2+)is significant for water quality monitoring and human health.In this paper,blue fluorescent Ti3C2 MXene-based quantum dots(MQDs,λ_(em)=445 nm)are prepared using Ti_(3)C_(2)MXene as the precursor.Through the chelation effect of ethylene diamine tetraacetic acid(EDTA),a blue and red dual-emission fluorescent probe,MQDs-EDTA-Eu^(3+)-DPA,was constructed.Herein,dipicolinic acid(DPA)acts as an absorbing ligand and significantly enhances the red fluorescence of europium ions(Eu^(3+))at 616 nm through the“antenna effect”.The blue fluorescence of MQDs serves as an internal reference signal.High concentrations of Ca^(2+)can quench the red fluorescence of Eu^(3+)-DPA;Mn^(2+)can be excited to emit purple fluorescence at 380 nm after coordinating with DPA,red fluorescence of Eu^(3+)-DPA serves as the internal reference signal.Based on the above two fluorescence intensity changes,ratiometric fluorescence detection methods for Ca^(2+)and Mn^(2+)are established.The fluorescence intensity ratio(IF_(616)/IF_(445))exhibits a linear relationship with Ca^(2+)in the range of 35-120μmol/L,with a detection limit of 5.98μmol/L.The fluorescence intensity ratio(IF_(380)/IF_(616))shows good linearity with Mn^(2+)in the range of 0-14μmol/L,with a detection limit of 28.6 nmol/L.This method was successfully applied to the quantitative analysis of Ca^(2+)and Mn^(2+)in commercially available mineral water(Nongfu Spring,Ganten,and Evergrande),with recovery rates of 80.6%-117%and relative standard deviations(RSD)of 0.76%-4.6%.Additionally,by preparing MQD-based fluorescent test strips,visual detections of Ca^(2+)and Mn^(2+)are achieved.This work demonstrates the application potential of MQDs in the field of visual fluorescence sensing of ions in water quality.展开更多
文摘A visual sensing system was established to monitor the weld pool in laser spot welding. The top-hat and bottom-hat transformation algorithms based on mathematical morphology were used to compensate for non-uniform contrast of weld pool edge. Moreover, the canny edge detector was applied to extract the weld paol profile. The edge detected results show that the morphological operation is obviously superior to the traditional contrast enhancement method. In addition, the combination of dilation and erosion was applied to eliminate the irrelevant edge details, and the smooth weld pool edge was acquired. Based on the image processing technology described above, the dynamic process of weld pool diameter during laser spot welding was obtained.
文摘A visual sensing system was developed. The system is suitable for titanium-alloy electron-beam welding, and senses and detects molten-pool dynamic processes. A suite of processing programs for colored molten-pool images in titanium-alloy electron-beam welding was developed using Matlab software; molten-pool edge images are completely obtained using the program. The Matlab software was used to write a program which could extract the molten-pool width. The functional relationship between the molten-pool width and penetration under the experimental conditions was obtained by a curve-fitting method, and provided the theoretical basis for further penetration control.
文摘Methods of arc length control and visual image based weld detection for precision pulse TIG welding were investigated. With a particular all hardware circuit, arc voltage during peak current stage is sampled and integrated to indicate arc length, deviation of arc length and adjusting parameters are calculated and output to drive a step motor directly. According to the features of welding image grabbed with CCD camera, a special algorithm was developed to detect the central line of weld fast and accurately. Then an application system were established, whose static arc length error is ±0.1 mm with 20 A average current and 1 mm given arc length, static detection precision of weld is 0.01 mm , processing time of each image is less than 120 ms . Precision pulse TIG welding of some given thin stainless steel components with complicated curved surface was successfully realized.
基金supported by the National Natural Science Foundation of China(No.52373086)supported by the Opening Project of State Key Laboratory of Polymer Materials Engineering(Sichuan University)(No.sklpme2024-1-26).
文摘Color-changeable smart textiles capable of converting external stimulus into change in eye-perceptible colors are promising for visual sensor and wearable devices.However,conventional color-changeable smart textiles based on functional chemical dyes suffer the narrow-ranged color shifting and hence the bad visual interaction resolution.In this work,inspired by that chameleon rapidly tuning skin iridescence through active tuning of guanine nanocrystal spacing,a full-color-changeable textile equipped with a cholesteric photonic skin is developed via layer-by-layer assembly strategy by using sustainable nanocellulose as photonic ink to work with graphene oxide as light absorber and polyvinyl alcohol as plasticizer.After assembled,a multi-phase layered stacking coupled with Janus surface structure forms,hence generating structural synergic effects bringing multi functions for the resulting photonic textile,including flexible optical adjustability,strong-tough combination,hydration-setting formability,and progressive wettability.More impressively,resultant photonic textiles present wide-ranged color-shifting capability with a high identifiability outperforming most of conventional color-changeable textiles,demonstrating great feasibility to monitor the directional water transport process,diverse organic componence volatilization,and ambient humidity,in a naked-eye-readable,real-time,and quantifiable manner.
文摘A passive visual sensing system is established in this research, and clear weld pool images in pulsed gas metal arc welding （ P-GMA W） can be captured with this system. The three-dimensional weld pool geometry, especially the weld height, is not only a crucial factor in determining workpiece mechanical properties, but also an important parameter for reflecting the penetration. A new three-dimensional （3D） model is established to describe the weld pool geometry in P-GMAW. Then, a series of algorithms are developed to extract the model geometrical parameters from the weld pool images. Furthermore, the method to reconstruct the 3 D shape of weld pool boundary and weld bead from the two-dimensional images is investigated.
基金the financial support for this project from the National Natural Science Foundation of China under grant No.51205106the support from State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology
文摘In the vision monitoring or controlling the arc welding process, it is a prerequisite to get a clear image of weld pool. However, the disturbance of arc radiation makes imaging of weld pool difficult and optical filters are usually used to improve the image quality. In this paper, a radiometric imaging model is established to investigate the influence of the filter on the image quality of the weld pool, in which the spectral distribution of weld pool radiation, the spectral transmittance of the filter, the spectral sensitivity of the camera are all considered. With the proposed model, the influence of the factors on weld pool imaging can be inferred and the selection of optical filters is discussed.
文摘Human visual sense has two aspects in our feeling for blurred image, that is, one is the amount of blur depending on object size, the other is the amount of blur independent of the object size. In the former for example, when the image size becomes larger, the author feels smaller amount blur. The quantitative evaluation based on entropy for blurred images is proposed in this paper. The author calls this metric ＂variation entropy＂. This metric has two kinds of aspects that coincide with the human visual sense. The first is the absolute evaluation of blur, and the second is the relative evaluation of blur. The former can be quantified by variation entropy for a unit boundary length （or L-type variation entropy： HL ）, which is dependent on resolution, and the latter can be quantified by variation entropy for a unit area （or A-type variation entropy： H^A ）, which is independent of resolution. These two metrics have complementary properties. At last, two variation entropies are applied to the standard kanji character database, and then the strong relation between variation entropy and accuracy of recognition is discussed. The tendency of writing skills for grades is evaluated by applying the metric to a database collected from school children.
基金The Tertiary Education Scientific Research Project of the Guangzhou Municipal Education Bureau(2024312227)Innovative and Entrepreneurial Projects of Guangzhou University Students(202411078014)+2 种基金Guangzhou University Open Sharing Fund for Instruments and Equipment(2025)National Major Scientific Research Instrument Development Project(22227804)Sub-subject of the National Key Research Project(2023YFB3210100)。
文摘Calcium ions(Ca^(2+))and manganese ions(Mn^(2+))are essential for sustaining life activities and are key monitoring indicators in drinking water.Developing highly sensitive,selective,and portable detection methods for Ca^(2+)and Mn^(2+)is significant for water quality monitoring and human health.In this paper,blue fluorescent Ti3C2 MXene-based quantum dots(MQDs,λ_(em)=445 nm)are prepared using Ti_(3)C_(2)MXene as the precursor.Through the chelation effect of ethylene diamine tetraacetic acid(EDTA),a blue and red dual-emission fluorescent probe,MQDs-EDTA-Eu^(3+)-DPA,was constructed.Herein,dipicolinic acid(DPA)acts as an absorbing ligand and significantly enhances the red fluorescence of europium ions(Eu^(3+))at 616 nm through the“antenna effect”.The blue fluorescence of MQDs serves as an internal reference signal.High concentrations of Ca^(2+)can quench the red fluorescence of Eu^(3+)-DPA;Mn^(2+)can be excited to emit purple fluorescence at 380 nm after coordinating with DPA,red fluorescence of Eu^(3+)-DPA serves as the internal reference signal.Based on the above two fluorescence intensity changes,ratiometric fluorescence detection methods for Ca^(2+)and Mn^(2+)are established.The fluorescence intensity ratio(IF_(616)/IF_(445))exhibits a linear relationship with Ca^(2+)in the range of 35-120μmol/L,with a detection limit of 5.98μmol/L.The fluorescence intensity ratio(IF_(380)/IF_(616))shows good linearity with Mn^(2+)in the range of 0-14μmol/L,with a detection limit of 28.6 nmol/L.This method was successfully applied to the quantitative analysis of Ca^(2+)and Mn^(2+)in commercially available mineral water(Nongfu Spring,Ganten,and Evergrande),with recovery rates of 80.6%-117%and relative standard deviations(RSD)of 0.76%-4.6%.Additionally,by preparing MQD-based fluorescent test strips,visual detections of Ca^(2+)and Mn^(2+)are achieved.This work demonstrates the application potential of MQDs in the field of visual fluorescence sensing of ions in water quality.
