Recently, the phase compensation technique has allowed the ultrasound to propagate through the skull and focus into the brain. However, the temperature evolution during treatment is hard to control to achieve effectiv...Recently, the phase compensation technique has allowed the ultrasound to propagate through the skull and focus into the brain. However, the temperature evolution during treatment is hard to control to achieve effective treatment and avoid over-high temperature. Proposed in this paper is a method to modulate the temperature distribution in the focal region. It superimposes two signals which focus on two preset different targets with a certain distance. Then the temperature distribution is modulated by changing triggering time delay and amplitudes of the two signals. The simulation model is established based on an 82-element transducer and computed tomography （CT） data of a volunteer＇s head. A finite- difference time-domain （FDTD） method is used to calculate the temperature distributions. The results show that when the distances between the two targets respectively are 7.5-12.5 mm on the acoustic axis and 2.0-3.0 mm in the direction perpendicular to the acoustic axis, a focal region with a uniform temperature distribution （64-65 ℃） can be created. Moreover, the volume of the focal region formed by one irradiation can be adjusted （26.8-266.7 mm3） along with the uniform temperature distribution. This method may ensure the safety and efficacy of HIFU brain tumor therapy.展开更多
Based on the vector diffraction theory, the effect of complex phase filters on intensity distribution of a radially polarized multi Gaussian beam in the focal region of high NA lens is theoretically investigated. It i...Based on the vector diffraction theory, the effect of complex phase filters on intensity distribution of a radially polarized multi Gaussian beam in the focal region of high NA lens is theoretically investigated. It is observed that a properly designed multi belt complex phase filter can generate subwavelength novel focal patterns including splitting of focal spots and generation of multiple focal spot segments such as eight, six and four focal spots along the optical axis are obtained. We expect that such an investigation is useful for optical manipulation and material processing, multiple high refractive index particle trapping technologies.展开更多
Optical microscopy has become an indispensable tool for visualizing sub-cellular structures andbiological processes.However,scattering in biological tissues is a major obstacle that preventshigh-resolution images from...Optical microscopy has become an indispensable tool for visualizing sub-cellular structures andbiological processes.However,scattering in biological tissues is a major obstacle that preventshigh-resolution images from being obtained from deep regions of tissue.We review commontechniques,such as multiphoton microscopy(MPM)and optical coherence microscopy(OCM),for diffraction limited imaging beyond an imaging depth of 0.5 mm.Novel implementations havebeen emerging in recent years giving higher imaging speed,deeper penetration,and better imagequality.Focal modulation microscopy(FMM)is a novel method that combines confocal spatialfltering with focal modulation to reject out-of-focus background.FMM has demonstrated animaging depth comparable to those of MPM and OCM,near-real-time image acquisition,and thecapability for multiple contrast mechanisms.展开更多
Detecting surface defects on steel,especially in complex loading environments,poses significant challenges.In response,we introduce EDFW-YOLO,an algorithm built upon you only look once version 8(YOLOv8)specifically de...Detecting surface defects on steel,especially in complex loading environments,poses significant challenges.In response,we introduce EDFW-YOLO,an algorithm built upon you only look once version 8(YOLOv8)specifically designed for detecting surface defects on hot-rolled steel strips.Our method enhances multi-scale feature fusion through the incorporation of the multi-scale conversion module(C2f-EMSC).Additionally,we elevate detection accuracy by integrating the dynamic head target detection head,the focal modulation module,and the WIoU_Loss bounding box regression function.Experimental results on the NEU-DET dataset demonstrate that our optimized YOLOv8 model achieves the mean average precision(mAP)of 77.7%,with a 5.2%increase in network constraint rate.To adapt to different operating environments,it further improved the mAP to 78.5%through data enhancement.Verification results on PCB defect data show that the algorithm has excellent generalization ability.This optimized algorithm significantly improves the extraction and fusion of surface defect features on hot-rolled strip steel and serves as a valuable reference for surface defect detection in alloy materials.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.81272495)the Natural Science Foundation of Tianjin,China(Grant No.16JC2DJC32200)
文摘Recently, the phase compensation technique has allowed the ultrasound to propagate through the skull and focus into the brain. However, the temperature evolution during treatment is hard to control to achieve effective treatment and avoid over-high temperature. Proposed in this paper is a method to modulate the temperature distribution in the focal region. It superimposes two signals which focus on two preset different targets with a certain distance. Then the temperature distribution is modulated by changing triggering time delay and amplitudes of the two signals. The simulation model is established based on an 82-element transducer and computed tomography （CT） data of a volunteer＇s head. A finite- difference time-domain （FDTD） method is used to calculate the temperature distributions. The results show that when the distances between the two targets respectively are 7.5-12.5 mm on the acoustic axis and 2.0-3.0 mm in the direction perpendicular to the acoustic axis, a focal region with a uniform temperature distribution （64-65 ℃） can be created. Moreover, the volume of the focal region formed by one irradiation can be adjusted （26.8-266.7 mm3） along with the uniform temperature distribution. This method may ensure the safety and efficacy of HIFU brain tumor therapy.
文摘Based on the vector diffraction theory, the effect of complex phase filters on intensity distribution of a radially polarized multi Gaussian beam in the focal region of high NA lens is theoretically investigated. It is observed that a properly designed multi belt complex phase filter can generate subwavelength novel focal patterns including splitting of focal spots and generation of multiple focal spot segments such as eight, six and four focal spots along the optical axis are obtained. We expect that such an investigation is useful for optical manipulation and material processing, multiple high refractive index particle trapping technologies.
文摘Optical microscopy has become an indispensable tool for visualizing sub-cellular structures andbiological processes.However,scattering in biological tissues is a major obstacle that preventshigh-resolution images from being obtained from deep regions of tissue.We review commontechniques,such as multiphoton microscopy(MPM)and optical coherence microscopy(OCM),for diffraction limited imaging beyond an imaging depth of 0.5 mm.Novel implementations havebeen emerging in recent years giving higher imaging speed,deeper penetration,and better imagequality.Focal modulation microscopy(FMM)is a novel method that combines confocal spatialfltering with focal modulation to reject out-of-focus background.FMM has demonstrated animaging depth comparable to those of MPM and OCM,near-real-time image acquisition,and thecapability for multiple contrast mechanisms.
基金supported by the National Natural Science Foundation of China(No.61961037).
文摘Detecting surface defects on steel,especially in complex loading environments,poses significant challenges.In response,we introduce EDFW-YOLO,an algorithm built upon you only look once version 8(YOLOv8)specifically designed for detecting surface defects on hot-rolled steel strips.Our method enhances multi-scale feature fusion through the incorporation of the multi-scale conversion module(C2f-EMSC).Additionally,we elevate detection accuracy by integrating the dynamic head target detection head,the focal modulation module,and the WIoU_Loss bounding box regression function.Experimental results on the NEU-DET dataset demonstrate that our optimized YOLOv8 model achieves the mean average precision(mAP)of 77.7%,with a 5.2%increase in network constraint rate.To adapt to different operating environments,it further improved the mAP to 78.5%through data enhancement.Verification results on PCB defect data show that the algorithm has excellent generalization ability.This optimized algorithm significantly improves the extraction and fusion of surface defect features on hot-rolled strip steel and serves as a valuable reference for surface defect detection in alloy materials.
