最新刊期
卷 32 ， 期 18 ， 2024
- “在零碳燃料领域，研究人员开发了基于中红外层析吸收光谱技术的测量系统，实现了不同掺氨比燃烧工况下火焰温度的免标定、定量测量。”摘要：Ammonia （NH3） is a representative carbon-free fuel， with its primary combustion products being water and nitrogen gas. Due to its unique advantage of zero carbon emissions， high proportions of ammonia co-firing strategy have been successfully implemented in decarbonization of thermal power boilers， internal combustion engines， and industrial furnace. As flame temperature is closely related to combustion efficiency and pollutant generation， it necessitates precise measurements for active control of low-pollution combustion processes. This paper presented the development of a measurement system based on mid-infrared tomographic absorption spectroscopy. By comprehensive analysis of absorption lines， we optimized the selection of absorption lines and finally selected the transitions near 2 482 nm within the fundamental band （v3） of H2O. By employing the multiple Voigt profile function， we achieved accurate fitting of the overlapping absorption features of H2O spectra. Combining Abel inversion and regularization techniques， we realized calibration-free and quantitative measurements of flame temperature under different proportions of ammonia blending. The experimental results indicate that the flame sheet positions are located between 0.5 and 2 mm above the burner for pure ammonia flame and methane/ammonia co-fire flame. As the proportion of ammonia increases from 20% to 100%， the flame sheet gradually moves away from the burner， while the maximum flame temperature rises from approximately 1 600 K to 2 000 K. The proposed measurement technique and system developed in this study not only capture the non-uniform temperature distribution of laminar premixed flames along the axial and radial directions but also discern subtle differences in flame temperature under various combustion conditions. This system is particularly suitable for measuring the flame temperature of zero-carbon ammonia fuels.关键词：mid-infrared tomographic absorption spectroscopy;temperature measurement;ammonia-fueled laminar premixed flame;temperature distributions
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发布时间：2024-10-28 - “在活体小动物荧光成像领域，研究者提出了一种全玻璃球面透镜光学设计方案，有效解决了宽谱段内多种波长同时复用问题，满足了低探测阈值高质量成像需求。”摘要：To address the demand for in vivo small animal fluorescence imaging in the near-infrared II （NIR-II） window， as well as solve the problem of simultaneous reuse of multiple wavelengths within a wide spectral range. This study took the perspective of aberration correction and designed an optical system by iteratively refining the lens group structure based on aberration curves. The working distance was increased through reasonable focal length distribution， and the glass material selection was optimized to balance chromatic aberration control and energy transmittance within the wide spectral range. The final optical structure ended up with a focal length of 40 mm， capable of ensuring MTF>0.6@34 lp/mm for the NIR-II spectral band （0.9~2.3 μm） within the working distance range （200~600 mm）， with RMS spot size smaller than the pixel size （15 μm） and distortion less than 1% across the entire field of view. Real-shot tests with resolution targets demonstrate a resolution capability of 50 μm. This optical design provides a solution based on all-glass spherical lenses capable of meeting the requirements for high-quality， low detection threshold in vivo small animal fluorescence imaging in the NIR-II window.关键词：NIR-II vivo imaging;optical design;aberration curves;bokeh
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发布时间：2024-10-28 - “在中红外超连续谱领域，研究者提出了一种新型光子晶体光纤，通过外加轴向电场实现了谱宽和相干性的连续可调谐，为传感检测与生物医学等领域提供了新的解决方案。”摘要：In order to make the spectral width of the mid-infrared supercontinuum spectrum continuously tunable， a chalcogenide photonic crystal fiber （PCF） with As2S3 matrix material and LiNbO3 crystal auxiliary rods， whose optical axis was running along the axial direction of the fiber， was proposed. The influence of the adding electric field with parallel direction of the axis of the fiber on the dispersion， effective mode field area， and non-linearity coefficient was simulated by using the finite element method （FEM）， the evolution of optical pulse transmission in optical fiber was investigated， and the tunability of the axial electric field on the spectral width and coherence of the supercontinuum spectrum was analyzed. The results reveal that the spectral width and tunable range of the supercontinuum spectrum in the fiber with a filling factor of 0.6 is greater than that with other filling factors at the same pump. When injecting a pump pulse with a peak power of 5 kW， a pulse width of 100 fs， and a central wavelength of 3.5 μm into the fiber， the output supercontinuum spectral width reaches 2.242 0 μm for an electric field strength of 40×108 V/m， an increase of 176.30 nm over that without the electric field. As the adding electric field causes the coherence factor of the supercontinuum to converge to 1 at longer wavelengths， it also contributes to the coherence of the supercontinuum. Mid-infrared supercontinuum light sources with continuously tunable spectral width can be obtained and have potential applications in fields such as sensing detection and biomedicine.关键词：photonic crystal fiber;supercontinuum;tunable spectrum;LiNbO3;As2S3
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发布时间：2024-10-28
Modern Applied Optics
- “在高功率激光远场传输特性研究领域，专家建立了性能通用模型，确定了核心指标设计方法，为高功率激光系统工程化设计提供参考。”摘要：In this paper， we’ve made a deep research on the far-field propagation of high-power lasers， and a general far-field performance model is derived， which is concerned with multiple factors， including atmosphere turbulence， diffraction effects and etc. Meanwhile for better field application， further amendment suggestions are proposed. Based on this model， we presented the optimal design method and principles by defining index weight factors used as evaluation parameters. The simulation results indicated that both of the beam quality and output power were the key elements that influence the far-field laser irradiance， between them beam quality has a higher weight， about 30%-79%， and needed to be decided first， in fact the ideal case was that beam quality was infinitely close the the diffraction limit. The laser emission aperture weights the lowest， about 4%-24%， and does a little favour to the system performance， so it needs a trade-off design with other functions such as tracking ability. Finally， analysis of the example verify the scientificity of the index weight factors， and verify the validity of the optimal design principles， which have great reference value for engineering design of high power laser systems.关键词：high-power laser;far-field performance;optimal design;weight factor
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发布时间：2024-10-28 - “在惯性导航系统领域，专家研制了摆式加速度计自动装配系统，实现了高精度装配，为批量化生产提供保障。”摘要：Pendulum accelerometer is widely used in inertial navigation systems of aerospace， shipping and other fields. Its assembly operation currently relies mainly on manual operation， making it difficult to ensure product consistency. In view of this， this article has developed an automatic assembly system for a certain type of pendulum accelerometer. Based on the design strategy of macro-micro combination， a micro-motion platform based on a high-precision motion slide table and a macro-motion platform based on a single-axis robot were built. A assembly mechanism was established with the micro-motion platform as the precision adjustment core and the macro-motion platform assisting in pressing and realizing the adjustment of the working positions of different functional modules. At the same time， a three-layer stacked vertical layered structure was designed for the functional modules to ensure precision while avoiding congestion in the workspace. A six-axis collaborative robot and an integrated vision system were introduced to achieve full-coverage recognition and automatic loading and unloading functions in the workspace. Aiming at the influence of magnetic force of magnetic steel parts on assembly accuracy， the method of auxiliary limiting inside the parts was adopted to maintain the assembly accuracy of parts. Based on rigid body transformation， error analysis of the system is carried out and an error compensation model was derived. Experimental results verify that the angle assembly accuracy of the assembly system is better than ±0.03°， the pressing force accuracy is better than ±0.5 N， and the torque accuracy is better than ±0.003 N·m， meeting the assembly requirements and providing strong support for the mass production of this type of pendulum accelerometer.关键词：micro assembly;pendulum accelerometer;assembly system;error analysis
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发布时间：2024-10-28 - “在高端智能制造领域，针对工业机器人绝对定位精度的高要求，研究了基于支持向量回归模型的机器人空间误差预测方法。通过实验验证，机器人位置和姿态误差显著降低，为提高工业机器人精度提供了有效解决方案。”摘要：The high-end intelligent manufacturing field has put forward higher requirements for the absolute pose accuracy of industrial robots in high-accuracy application scenarios. This paper investigated the improvement of robot accuracy performance based on Support Vector Regression （SVR）. Kinematic modeling and error analysis were performed on the Staubli TX60 series industrial robot. A robot measurement experiment platform was established based on the Leica AT960 laser tracker， and a large number of spatial position points were measured. The SVR model was trained and optimized based on real data sets. The actual pose error of the robot is predicted by Support Vector Regression Model， which avoids the complicated error modeling in the model-based robot accuracy improvement method. The average position error and average attitude error of the robot are reduced from （0.706 1 mm，0.174 2°） to （0.055 6 mm，0.024 6°） before compensation， respectively， and the position error is reduced by 92.12% and the attitude error is reduced by 85.88%. Finally, the comparison with BP neural network, Elman neural network and traditional LM geometric parameter calibration method verified the effectiveness and balance of spatial error prediction based on SVR model in reducing robot position and attitude errors.关键词：Support vector regression （SVR）;non-model calibration;industrial robots;error prediction;Robot calibration
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发布时间：2024-10-28
Micro/Nano Technology and Fine Mechanics
- “在机器人视觉抓取领域，研究者提出了一种基于空间信息聚合的遮挡目标抓取位姿检测方法，有效提高了遮挡目标的检测准确率。该方法通过坐标卷积和空间信息聚合模块，增强了网络对目标结构和形状的理解能力。在多个数据集上的实验验证表明，该方法检测准确率最高，且在实际场景中检测效果更优。”摘要：Aiming at the problem of low accuracy of occlusion target grasping position detection when the robot relies on vision grasping， we proposed an occlusion target grasping position detection method based on spatial information aggregation. Occlusion led to the change of the target's intrinsic features in the camera's field of view， which affected the target's positional information and shape-structural features. First， coordinate convolution was used instead of traditional convolution for feature extraction， and a new coordinate channel was added after the input feature map to improve the network's ability to perceive position information. Second， the spatial information aggregation module was designed， which adopted a parallel structure to increase the local sensing field and encoded the channels along the spatial direction to obtain multi-scale spatial information， and then aggregated the information through nonlinear fitting to make the model better understand the target structure and shape. Finally， the grasping position detection network outputted the grasping mass， angle and width， and calculated the optimal grasping position to establish the optimal grasping rectangular box. Validated on the Cornell Grasping dataset， the self-constructed occlusion dataset， and the Jacquard dataset， the detection accuracies reach 98.9%， 94.7%， and 96.0%， respectively， and the success rate is 93% in 100 real grasping experiments on the target in the experimental platform. The proposed method achieves the highest detection accuracy on all three datasets， and the detection effect is better in real scenes.关键词：grasping detection;occluded target;spatial information aggregation module;CoordConv
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发布时间：2024-10-28 - “在传感器测量精度提升领域，专家提出了一种自标定方法，有效补偿周期性误差，显著提升标定精度，为传感器测量精度提升提供新方案。”摘要：Comparison calibration is of great significance for the maintenance and improvement of sensor measurement accuracy， but it is easy to be limited by the field environment， and the cost is expensive. The accuracy of electric grid is constantly updated， and it is increasingly difficult to find an external reference. In order to solve this problem， a self-calibration method of sensor error function was proposed based on the principle of circular closure and the translation law of Fourier series. The error sequence values of electric field time-grating were shifted by 2π/n angular displacement， error sequence values with different phase shift times were used for spectrum analysis to compensate each other for missing harmonic components， finally， the sensor error function was reconstructed using each harmonic component. Accordingly， a self-calibration application platform was designed and built. The experimental results show that the self-calibration method is effective in compensating the periodic errors contained in the electric field time-grating angular displacement sensor. measurement period， the calibration accuracy obtained by using the self-calibration method is similar to that obtained by using the grating as the reference， the measurement error of two different self-calibration methods is 0.05"， and the measurement period error is reduced by 67%. Over the full measurement range， the measurement error of two different self-calibration methods is 0.15"， and the full measurement error dropped by 80%. Compared with the conventional comparison and self-calibration method， the self-calibration method has significant advantages in efficiency， application range and calibration cost.关键词：electric field type;angular displacement sensor;self-calibration;error phase shift;harmonic component
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发布时间：2024-10-28 - “在SAR图像目标检测领域，研究人员设计了基于多标签分配的DETR网络，有效提高了目标检测精度，减少了训练周期。”摘要：Target detection in SAR images has been a research hotspot in recent years， but the characteristics of unclear imaging also make the DETR network model unable to extract its potential features well. At the same time， the DETR network also has the problems of long training cycle and slow convergence. To this end， a Multi-label Assignment DETR （MA-DETR） network was designed for aircraft target detection in SAR images. In this paper， we used a data augmentation module with Large Scale Jittering （LSJ） to enhance the training effect of the network， and then designed a multi-label assignment supervision module to process the data output from the encoder. Among them， multiple supervised auxiliary heads extract potential features and inputted them to the decoder to improve the defects of the one-to-one label assignment method of DETR network. Finally， a matching enhancement module was designed to be added to the decoder to alleviate the matching discreteness caused by the Hungarian matching algorithm and improve the convergence speed of network training loss. The experimental results on the SAR AIRcraft dataset show that， compared with the original method， the proposed method improves the AP0.5 and AP0.75 accuracy by 7.9% and 7.4% respectively， and reduces the training cycle by 3.3 times based on the same training network. The new network structure effectively improves the target detection accuracy of SAR images and reduces the training cycle of DETR network.关键词：object detection;Synthetic Aperture Radar（SAR) image;Detection Transformer(DETR) network;attention mechanism
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发布时间：2024-10-28 - “在点云分类分割领域，研究者提出了结合双注意力和加权动态图卷积网络的算法，有效提取上下文信息和增强近邻点特征表达。”摘要：In response to the deficiencies in local context information extraction and neighboring point feature expression in deep learning-based point cloud classification and segmentation networks， as well as the problem of maxpooling leading to the loss of suboptimal information， a point cloud classification and segmentation algorithm that combines dual attention and weighted dynamic graph convolutional networks was proposed. Firstly， the weighted dynamic graph convolution used a weighted k-nearest neighbor algorithm to construct a robust local structure and introduced an enhanced edge convolution module to apply weights to point features， thereby obtaining enhanced edge features. Then， channel attention was used to construct channel correlations and unleash the potential of each channel， followed by spatial attention to perceive the spatial structure of 3D point clouds， enhancing the expression of local semantic features and extracting effective contextual and deep semantic information. Finally， TopK pooling was employed to add suboptimal features. Experimental results show that the algorithm achieves an overall classification accuracy of 93.36% on the ModelNet40 classification dataset and an average intersection over union of 85.96% on the ShapeNet Part segmentation dataset， effectively extracting contextual information and enhanced neighboring point feature expression， demonstrating the effectiveness of the algorithm.关键词：classification and segmentation;3D point cloud;attention mechanism;weighted dynamic graph convolution;K-nearest neighbor
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发布时间：2024-10-28 - “在小鼠脑电镜图像处理领域，研究人员提出了EM-SAM分割模型，准确识别物体形态结构，为神经分割任务提供高准确性、鲁棒性解决方案。”摘要：The accuracy and robustness of segmentation models are critical considerations in the processing of mouse brain electron microscopy images. We proposed a highly robust two-dimensional segmentation algorithm tailored to the technical characteristics of electron microscopy images， aiming to accurately delineate the morphological structure of cells in each slice. Aiming at accurately delineate the morphological structure of cells in each section，a highly robust two-dimensional segmentation algorithm based on natural image model tailored to the technical characteristics of electron microscopy images was proposed. EM-SAM was based on fine-tuning the backbone network of pre-trained large natural image model SAM for maximizing the capability of features extraction. The model employed the image encoder from the SAM architecture， augmented with a U-shaped decoder， and was fine-tuned specifically for the segmentation of mouse brain electron microscopy images. Experimental results demonstrate that A-Rand achieves 0.054 on public dataset SNEMI3D. Additionally， AP-50 and AP-75 reach 0.883 and 0.604， respectively， on public dataset MitoEM. EM-SAM exhibits high accuracy and robustness in neural segmentation tasks of electron microscopy images， and it can be fine-tuned for different tasks.关键词：computer vision;segmentation;large-scale models;electron microscopy images;mouse brain
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发布时间：2024-10-28 - “在结直肠息肉分割领域，研究人员设计了多尺度网络，通过级联策略融合边界特征，有效提高了分割精度和泛化能力。”摘要：Colorectal polyp segmentation can effectively assist doctors in screening for colorectal adenomas， but polyp segmentation has problems such as more noise and insufficient boundary distinguishability. In response to these issues， this paper designed a multi-scale polyp segmentation network that adopts cascaded strategy to fuse boundary features. Firstly， this paper proposed an improved channel grouping spatial enhancement module to enhance the image features extracted by the backbone network， thereby improving the correlation between channels and spatial positions. Secondly， considering the insufficient boundary distinction， a cascaded feature fusion network was designed to better retain boundary information and improve boundary distinction， so as improve the segmentation accuracy. Finally， a dual-branch hybrid upsampling module was introduced to obtain more detail feature information， so as to realize the complementarity of features and capture more complete and effective features. Tested on the CVC-ClinicDB and Kvasir datasets， our algorithm achieves mean Dice coefficients of 0.944 and 0.920， and mean Intersection over Union of 0.900 and 0.869 respectively， compared to the M2SNet algorithm with average Dice coefficients of 0.922 and 0.912， and mean IoU of 0.880 and 0.861 respectively. Tested on the ETIS-LaribPolypDB， CVC-300， and CVC-ColonDB datasets， our algorithm achieves mean Dice coefficients of 0.776， 0.915， and 0.782 respectively， while the M2SNet algorithm achieves mean Dice coefficients of 0.749， 0.903， and 0.758 respectively. Experimental results show that the proposed algorithm has high segmentation accuracy and strong generalization ability.关键词：multi-scale polyp segmentation;channel group spatial enhancement;boundary feature enhancement;cascade feature fusion;dual-branch upsampling
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发布时间：2024-10-28
Information Sciences
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