2024

• Record 145 of
  
  Title:Three-dimensional crumpled d-Ti3C2Tx/PANI structure enabled by PANI interlayer spacing control for enhanced electrochemical performance
  
  Author(s):Zhao, Yuanbo(2); He, Weijun(2); Chen, Yanan(2); Liu, Yanan(2); Xing, Hongna(2); Zhu, Xiuhong(1,2); Feng, Juan(2); Liao, Chunyan(2); Zong, Yan(2); Li, Xinghua(2); Zheng, Xinliang(2)
  Source: Materials Today Communications  Volume: 39  Issue:   DOI: 10.1016/j.mtcomm.2024.108689  Published: June 2024  
  Abstract:The self-stacking and collapsing of few-layered Ti3C2Tx(d-Ti3C2Tx) results in its poor rate capability and cycle performance during charge/discharge processes. Constructing a three-dementional (3D) structure, introducing interlayer spacers and using alkaline electrolytes are effective and powerful strategies to resolve the problems. Herein, a 3D crumpled d-Ti3C2Tx/PANI composite was successfully prepared by HCl/LiF in-situ etching Ti3AlC2 to obtain d-Ti3C2Tx and polymerizing PANI onto its surface with ice-bath stirring. Benefiting from the synergistic effect of kinetically favorable structure, component and alkaline electrolytes, The PM-1 (d-Ti3C2Tx/PANI-1) as an electrode remarkably improves the electrochemical performances compared with the original d-Ti3C2Tx in 2 M KOH electrolyte. It exhibits a specific capacitance of 230 mF cm−2（115 F g−1）at 2 mA cm−2, high rate capability of 81.2% at 20 mA cm−2 and outstanding stability of 96.7% retention after 5000 cycles at 10 mA cm−2. Furthermore, an assembled symmetric supercapacitor (SSC) also presents an excellent stability performance with 82.4% retention after 5000 cycles at 8 mA cm−2 and a promising energy storage performance. The related work provides a good reference for the MXene-based electrode materials in the conditions of alkaline electrolytes. © 2024 Elsevier Ltd
  Accession Number: 20241315799736
• Record 146 of
  
  Title:Application of fine spectral detection and quantitative analysis technology in water quality and environmental monitoring of the Yangtze River main stream
  
  Author(s):Zhao, Yubo(1,2); Wang, Xueji(1); Liu, Xiao(1); Gong, Kaijie(3); Zou, Lei(4); Lin, Zhonghui(4); Yu, Tao(1); Yu, Weixing(1); Hu, Bingliang(1)
  Source: Dili Xuebao/Acta Geographica Sinica  Volume: 79  Issue: 1  DOI: 10.11821/dlxb202401004  Published: January 2024  
  Abstract:Water eco- environment monitoring is the premise and foundation of habitat protection. In view of the characteristics of the Yangtze River Basin's water system, which is diverse, complex, and ever- changing, higher requirements are put forward for monitoring methods. At present, the water quality monitoring methods for large surface water systems are still mainly based on manual sampling combined with laboratory chemical analysis or on-site hand-held instrumental analysis. There are problems such as method lag, single means, low frequency, and lack of non-point sources. Therefore, there is an urgent need for new system monitoring technology, which breaks through real-time, fast, non-point source quantitative and other practical needs, and provides a reliable data source for the comprehensive simulation of the Yangtze River water system. In this context, this paper proposes a fine spectral detection and quantitative analysis technology with completely independent intellectual property rights, and develops ground-based, space-based and other system technologies and equipment. With the support of the relevant projects, the demonstration application of systematic technology was carried out, and the space-ground stereoscopic monitoring was conducted in the key sections of the main stream of the Yangtze River, the Three Gorges Demonstration Area and the Poyang Lake Demonstration Area, and good results were achieved. The monitoring data are connected to the "Yangtze River Simulator" through the cloud platform, which provides fast real-time data support for its comprehensive operation, as well as a new method and application model for the comprehensive monitoring of large-scale water systems in the future. © 2024 Science Press. All rights reserved.
  Accession Number: 20240915663611
• Record 147 of
  
  Title:Influence of wavefront distortion on the measurement of pulse signal-to-noise ratio
  
  Author(s):Xing, Dingding(1,2); Yuan, Suochao(1); Kou, Jingwei(1); Da, Zhengshang(1)
  Source: Optics Communications  Volume: 554  Issue:   DOI: 10.1016/j.optcom.2023.130110  Published: March 1, 2024  
  Abstract:The high-fidelity measurement of the ultra-short and ultra-intense laser pulses' temporal signal-to-noise ratio (SNR) is of great significance. To the best of our knowledge, few studies have investigated the influence of wavefront distortion on the measurement of pulse SNR. In this work, a numerical model is constructed to study how wavefront distortion affects the measurement of ultra-short and ultra-intense pulse SNR by the single-shot third-order auto-correlation (TOAC) method. The nonlinear coupled-wave equations with wavefront distortion have been solved numerically by the split-step Fourier method and the fourth-order Runge-Kutta numerical algorithm. The wavefront distortion of the under-test fundamental wave will be transmitted to the second harmonic and third harmonic, leading to the phase mismatch in the second harmonic generation (SHG) and third harmonic generation (THG), further resulting in the deterioration of the measured SNR. We analyze the influence of different spatial frequencies and peak-to-valley (PV) values on the measurements of SNR. The larger the spatial frequency or PV value of the wavefront distortion, the more severe the degradation of the SNR. © 2023 Elsevier B.V.
  Accession Number: 20240215363991
• Record 148 of
  
  Title:On-orbit calibration of space camera lens distortion using a single image
  
  Author(s):Zhang, Gaopeng(1); Wang, Feng(1); Zhang, Guangdong(1,2); Zhang, Zhe(1); Du, Hubing(3); Zhao, Zixin(4); Wang, Changqing(2); Cao, Jianzhong(1); Zhao, Jingwei(3); Li, Yanjie(3); Lu, Rong(1)
  Source: Optics and Lasers in Engineering  Volume: 177  Issue:   DOI: 10.1016/j.optlaseng.2024.108140  Published: June 2024  
  Abstract:Since space cameras need to withstand the harsh mechanical and thermal conditions in the space environment for a long time, it is necessary to calibrate them in orbit. However, existing calibration methods have various disadvantages, making them impossible to use in orbit. To address this problem, we present an on-orbit calibration of space camera lens distortion with the vanishing points obtained from a single image of the solar panel. First, we propose a parallel-line-extraction method based on collinear constraints to obtain the parallel lines. Then, we train the optimal vanishing point using the common point constraint method. Using the optimal vanishing point, we establish the optimization function of lens distortion based on vanishing point consistency. Finally, we present an improved genetic algorithm to solve the optimization function. Simulations and experiments show that the proposed method is flexible and robust. © 2024 Elsevier Ltd
  Accession Number: 20241015672218
• Record 149 of
  
  Title:Accurate Real-Time Laser Spot Locating Based on Template Correlation in Intersatellite Laser Communications
  
  Author(s):Meng, Xiangsheng(1,2); Liu, Wen(1,2); Han, Junfeng(1,2); Tian, Yan(1,2); Liu, Jun(1,2); Ma, Caiwen(1,2)
  Source: IEEE Photonics Journal  Volume: 16  Issue: 1  DOI: 10.1109/JPHOT.2023.3335234  Published: February 1, 2024  
  Abstract:In intersatellite laser communications, the centroiding accuracy of a laser spot is crucial for maintaining steady communication links. However, the systematic error introduced by discrete sampling restricts further improvement of centroiding accuracy when choosing algorithms that are widely used in engineering. Additionally, the ultrahigh computational complexity and multiple-step iterations of the Gaussian fitting (GF) algorithm are unsuitable for real-time implementation, even though the algorithm can achieve the highest centroiding accuracy. In this study, we propose a laser spot centroiding algorithm based on template correlation to simultaneously satisfy the requirements of real-time performance and accuracy. The proposed algorithm evaluates the central location of a laser spot by obtaining the index of the maximum Pearson correlation coefficient (PCC). Simulations performed under different conditions reveal that the proposed algorithm is robust against the interference of background noise and the bad pixels. Moreover, experimental verification is performed based on the implementation on a Field-Programmable Gate Array (FPGA) in real-time, meanwhile its accuracy is on the same level as that of the GF algorithm and better than those of other widely-used algorithms. Therefore, the proposed algorithm is suitable for accurate real-time locating of laser spots in engineering applications of the intersatellite laser communications. © 2009-2012 IEEE.
  Accession Number: 20234915180528
• Record 150 of
  
  Title:Optimization of multilayer capacitive charge division anode for MCP imaging detectors
  
  Author(s):Yang, Kai(1,2); Bai, Yonglin(1); Wang, Bo(1); Cao, Weiwei(1); Zhu, Bingli(1); Bai, Xiaohong(1); Zheng, Jinkun(1); Zhang, Shengdan(1,2); Wang, Chao(1); Chen, Zhen(1); Yang, Yang(1)
  Source: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment  Volume: 1063  Issue:   DOI: 10.1016/j.nima.2024.169285  Published: June 2024  
  Abstract:A three-dimensional numerical model developed based on the finite element method to simulate the position-reconstruction performance of multilayer capacitive anodes is presented. The charge collection efficiency and position nonlinearity are calculated for different electrode layers, patterns, and sizes, as well as the distance between the bottom microchannel plate (MCP) and induction layer. The position nonlinearity exhibits an approximately linear relationship with the electrode size and the distance between the bottom MCP and induction layer. By increasing the electrode area in the perimeter region and designing 2.2 mm square electrodes in the central region, a position nonlinearity of 3.36% with a distance of 5 mm between the bottom MCP and induction layer is achieved. The imaging performance of the six multilayer capacitive anodes is evaluated using a custom-designed detector prototype, and the experimental results validate the simulation results. The comprehensively optimized capacitive anode shows an imaging nonlinearity of 0.91% in the experiment. © 2024
  Accession Number: 20241515861844
• Record 151 of
  
  Title:Detecting the Background-Similar Objects in Complex Transportation Scenes
  
  Author(s):Sun, Bangyong(1); Ma, Ming(1); Yuan, Nianzeng(2); Li, Junhuai(2); Yu, Tao(3)
  Source: IEEE Transactions on Intelligent Transportation Systems  Volume: 25  Issue: 3  DOI: 10.1109/TITS.2023.3268378  Published: March 1, 2024  
  Abstract:With the development of intelligent transportation systems, most human objects can be accurately detected in normal road scenes. However, the detection accuracy usually decreases sharply when the pedestrians are merged into the background with very similar colors or textures. In this paper, a camouflaged object detection method is proposed to detect the pedestrians or vehicles from the highly similar background. Specifically, we design a guide-learning-based multi-scale detection network (GLNet) to distinguish the weak semantic distinction between the pedestrian and its similar background, and output an accurate segmentation map to the autonomous driving system. The proposed GLNet mainly consists of a backbone network for basic feature extraction, a guide-learning module (GLM) to generate the principal prediction map, and a multi-scale feature enhancement module (MFEM) for prediction map refinement. Based on the guide learning and coarse-to-fine strategy, the final prediction map can be obtained with the proposed GLNet which precisely describes the position and contour information of the pedestrians or vehicles. Extensive experiments on four benchmark datasets, e.g., CHAMELEON, CAMO, COD10K, and NC4K, demonstrate the superiority of the proposed GLNet compared with several existing state-of-the-art methods. © 2000-2011 IEEE.
  Accession Number: 20232114129082
• Record 152 of
  
  Title:Multiple marine algae identification based on three-dimensional fluorescence spectroscopy and multi-label convolutional neural network
  
  Author(s):Li, Ruizhuo(1,2); Gao, Limin(1); Wu, Guojun(1,3); Dong, Jing(1,2)
  Source: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy  Volume: 311  Issue:   DOI: 10.1016/j.saa.2024.123938  Published: April 15, 2024  
  Abstract:Accurate identification of algal populations plays a pivotal role in monitoring seawater quality. Fluorescence-based techniques are effective tools for quickly identifying different algae. However, multiple coexisting algae and their similar photosynthetic pigments can constrain the efficacy of fluorescence methods. This study introduces a multi-label classification model that combines a specific Excitation-Emission matric convolutional neural network (EEM-CNN) with three-dimensional (3D) fluorescence spectroscopy to detect single and mixed algal samples. Spectral data can be input directly into the model without transforming into images. Rectangular convolutional kernels and double convolutional layers are applied to enhance the extraction of balanced and comprehensive spectral features for accurate classification. A dataset comprising 3D fluorescence spectra from eight distinct algae species representing six different algal classes was obtained, preprocessed, and augmented to create input data for the classification model. The classification model was trained and validated using 4448 sets of test samples and 60 sets of test samples, resulting in an accuracy of 0.883 and an F1 score of 0.925. This model exhibited the highest recognition accuracy in both single and mixed algae samples, outperforming comparative methods such as ML-kNN and N-PLS-DA. Furthermore, the classification results were extended to three different algae species and mixed samples of skeletonema costatum to assess the impact of spectral similarity on multi-label classification performance. The developed classification models demonstrated robust performance across samples with varying concentrations and growth stages, highlighting CNN's potential as a promising tool for the precise identification of marine algae. © 2024 Elsevier B.V.
  Accession Number: 20240815614850
• Record 153 of
  
  Title:Compensation control strategy for photoelectric stabilized platform based on disturbance observation
  
  Author(s):Chang, Sansan(1,2,5); Cao, Jianzhong(1,5); Pang, Ji(3); Zhou, Feihang(3); Chen, Weining(1,4,5)
  Source: Aerospace Science and Technology  Volume: 145  Issue:   DOI: 10.1016/j.ast.2024.108909  Published: February 2024  
  Abstract:The accuracy and stability of the photoelectric stabilized platform will be inevitably affected by the friction disturbance and the base platform disturbance in the actual operation. To improve the disturbance rejection performance, two kinds of the disturbance observers are employed and compared in this paper, including the adaptive proportion-integrator observer and the robust sliding mode observer. The disturbances of the friction torque and the moving base are observed, then these observed values are compensated to the voltage loop by the feedback and feedforward, respectively. While the disturbances of the friction torque and the shaking base are compensated, the parameters of the speed stability loop are also tuned to improve the performance of this photoelectric stabilized platform. Finally, the effectiveness of the proposed method is verified by both simulations and experiments. The results show that the proposed disturbance compensation control method based on the sliding mode observer has strong robustness and can effectively reduce the impact of system disturbances. © 2024
  Accession Number: 20240615508203
• Record 154 of
  
  Title:Design, Simulation, and Characterization of a Partial Negative Curvature Antiresonant Hollow-Core Fiber for Low Loss Terahertz Wave Transmission
  
  Author(s):Mu, Qiyuan(1); Zhu, Yuanfeng(2); Kong, Depeng(1); He, Zhengquan(1); Liu, Hongjun(1); Wang, Lili(1)
  Source: IEEE Transactions on Terahertz Science and Technology  Volume:   Issue:   DOI: 10.1109/TTHZ.2024.3393609  Published: 2024  
  Abstract:The present paper demonstrates a novel partial negative curvature hollow-core fiber for low-loss terahertz transmission. In the optimized fiber structure, the tubes in the vertical direction are replaced by plate-like dielectric sheets, thereby achieving low loss and low blocked risk of 3D printing, while retaining a small fiber hollow core and fiber diameter. The 3D printed fiber is characterized by a terahertz time-domain spectroscopy (THz-TDS) system. The obtained transmission spectrum demonstrates the mode beating phenomenon and its peak position varies periodically with fiber length at short distances. The thin antiresonant walls endow the fiber with two broad low-loss windows of 0.2–0.4 THz and 0.55–0.85 THz. Besides, the x-polarization and y-polarization waves achieve minimum losses of 16.2 dB/m@0.28 THz and 16.0 dB/m@0.29 THz, respectively. Furthermore, our fiber has low experimental dispersions, namely −0.18±1.1 ps/THz/cm (x-pol) and 0.67±0.77 ps/THz/cm (y-pol). The experimental losses and dispersions match well with the simulation results. Additionally, the simulation results reveal that the fiber has the potential to attain a high birefringence of 10−3. IEEE
  Accession Number: 20241816022823
• Record 155 of
  
  Title:Optical Design of High-compression Ratio and Low-wavefront Error Gravitational Wave Detection Telescope
  
  Author(s):Liang, Rong(1,2); Zhou, Xiaojun(1); Zou, Chunbo(3); Xu, Huangrong(1); Li, Chenxi(1); Yu, Tao(1,2); Yu, Weixing(1,2)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 53  Issue: 1  DOI: 10.3788/gzxb20245301.0122002  Published: January 2024  
  Abstract:Since the first detection of gravitational wave，gravitational wave astronomy has advanced swiftly. As a crucial component of the detection system，the gravitational wave telescope is obviously crucial. The highly stable laser telescope with a low wavefront error and a high suppression ratio of stray light is a crucial medium for the detection of gravitational waves，as it must not only transmit energy in the order of watt to distant spacecraft，but also receive weak laser signals in the order of picowatt from other satellite base station located millions of kilometers away. Therefore，the backward stray light of the local telescope is required to reach 10−10 orders of the incident laser power. Considering the requirements of small size，light weight，and high compactness，it is clear that the benefits of a reflective system cannot be compared to those of a transmission design. In general，the coaxial Cassegrain structure and off-axis multi-mirror structure are utilized. The off-axis design is preferred over the coaxial design for gravitational wave telescopes due to advantages such as the ability to optimize multiple parameters，the absence of a central obstruction，and the high energy collection capacity. In this paper，based on the design of off-axis four-mirror and the theory of coaxial reflection system，we designed and optimized the telescope combined with the characteristics of high magnification，low wavefront error and high suppression ratio of stray light. In the capture field of view of ±200 µrad，we realized the compression ratio of 100 of telescope，and the entrance pupil diameter of the principle system is 300 mm，whose design result of wavefront error is less than of λ/80 because the actual outgoing wavefront error must be less than λ/40. The system distortion of the edge field is less than 0.056 9%. In order to verify the processing and alignment of the principle system as well as the ability of stray light suppression of it，a 0.5 times scale system is established beneath the system with a wavefront error less than λ/175. Internal stray light is suppressed by increasing the light turning angle between the tertiary mirror and quaternary mirror on the condition of low wavefront error of λ/80. The optimized deflection angle of the tertiary mirror is 5.5 degrees，and the tertiary mirror is the plane surface，which can significantly reduce the difficulty of processing and alignment. A simulation of stray light is applied to analyze the stray light of our designed telescope. The steps of stray light analysis consist of the following steps：1）selection and optimization of the optical structure；2）model setting of the corresponding reflection，scattering，and absorption surfaces；3）stray light analysis of the entire system；4）iterative optimization design；5）fulfillment of the system's requirements. Therefore，we investigated the optical paths and power of the backscattered stray light. After positioning the field stop in the middle image plane between the secondary mirror and the tertiary mirror，the proportion of the stray light caused by the secondary mirror is the smallest. The stray light energy caused by the tertiary mirror and the quaternary mirror is the largest，which can reach more than 90%. The tolerance of the optical design is also analyzed，and the results of the analysis indicate that the tolerance of the parabolic primary mirror has the strongest impact on the wavefront error of the system. The principle system has a 90% cumulative probability wavefront error less than λ/40，which can satisfy the design requirement of gravitational wave detection and have the potential to play a significant role in future missions aimed at low wavefront error，high magnification and a high suppression ratio of stray light in the telescope while detecting gravitational waves. © 2024 Chinese Optical Society. All rights reserved.
  Accession Number: 20240815579474
• Record 156 of
  
  Title:Design of an Integrated Optical System for Detection and Imaging of Large Aperture and Long Focal Length Based on Continuous Zoom
  
  Author(s):Wei, Jinyang(2); Li, Xuyang(1,2); Tan, Longyu(2,3); Yuan, Hao(1); Ren, Zhiguang(1,2); Zhao, Jiawen(1,2); Yao, Kaizhong(1,2)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 53  Issue: 1  DOI: 10.3788/gzxb20245301.0122001  Published: January 2024  
  Abstract:In space target observation missions,there is a need for highly sensitive target detection and high-quality imaging. However,there is a significant disparity in the field of view between detection and imaging,and currently,two primary solutions are predominantly employed. One approach involves the design of two independent subsystems,while the other method utilizes a shared-aperture dual-channel design to integrate the functions of detection and imaging into a single system. However,designing two independent systems necessitates a substantial amount of space to accommodate these two subsystems, often exceeding the carrying capacity of most existing space optical payloads. On the other hand,adopting the shared-aperture dual-channel system requires additional electronic components and structural elements,with challenges during the assembly and calibration processes. This may potentially lead to uneven energy distribution issues. In order to achieve high sensitivity detection and precise identification of space targets,this paper introduces the design of an optical system based on a continuous zoom structure that balances a large aperture with a long focal length. This system aims to achieve short focal length and wide-field target detection,as well as long focal length and narrow-field target imaging. In terms of the design methodology,the inherent complexity of the system makes it challenging to obtain an ideal structure during the optimization process. Consequently,this system combines the structures of reflective mirrors and corrective lenses with a zoom structure through optical pupil matching. It employs two reflective mirrors to compress the optical path. During the zooming process,both the zooming components and compensating components move together to maintain the position of the image plane. At the intermediate zoom position,image quality is excellent,allowing for continuous target tracking. To address the issue of uneven energy distribution within the system,this optical system utilizes a shared-aperture detection and imaging integration structure. Furthermore,with an aperture size of 280 mm,the system can detect targets as faint as magnitude 14,effectively resolving the challenges associated with detecting faint and weak targets. The system operates within the spectral range of 450 nm to 850 nm and focal lengths ranging from 700 mm to 3 500 mm. At the detection end,the focal length is 700 mm,with an F-number of 2.5 and a field of view angle of 0.5°×0.5°. At the imaging end,the focal length varies from 1 400 mm to 3 500 mm, with F-numbers ranging from 5 to 12.5 and a field of view angle of 0.18° ×0.18° . At the detection end, 80% of the optical spot's encircled energy is concentrated within 17.4 μm. At the imaging end,the edge field MTF is 0.36,approaching the diffraction limit,while at the intermediate zoom position,MTF values range from 0.31 to 0.36,ensuring consistent image quality during the zooming process. This system integrates the detection and imaging systems into a single unit,achieving shared-aperture functionality. After conducting tolerance analysis on the system,it was observed that under relatively loose tolerances, MTF degradation in both the sagittal and tangential directions is minimal. Moreover, at an 80% probability,the optical spot diameter is smaller than 18.4 μm for each field of view,indicating that the system maintains excellent detection and imaging performance even under these relaxed tolerance conditions. The zoom cam curve is a critical design parameter for zoom systems,and in this system,the cam curves for both the zoom and compensator groups have an apex angle of less than 30°,meeting the design requirements. This system offers strong detection capabilities,excellent image quality,a compact overall length,and a minimal zoom cam curve apex angle. In terms of structure and design objectives,it provides valuable insights for the future development of continuous tracking integrated optical systems for the detection and imaging of targets. © 2024 Chinese Optical Society. All rights reserved.
  Accession Number: 20240815570755