2024

• Record 157 of
  
  Title:Fabricating S-scheme Sb2S3@CdSexS1–x quasi-one-dimensional heterojunction photoanodes by in-situ growth strategy towards photoelectrochemical water splitting
  
  Author(s):Liu, Dekang(1); Zhang, Dekai(1); Wang, Yishan(2); Liu, Enzhou(3); Miao, Hui(1)
  Source: Journal of Materials Science and Technology  Volume: 201  Issue:   DOI: 10.1016/j.jmst.2024.02.049  Published: December 1, 2024  
  Abstract:Nowadays, energy and environmental problems are becoming increasingly prominent in society, the development of clean and environmentally friendly energy is in line with the construction of ecological civilization and energy, which have attracted the attention of many researchers over the past decades. Narrow band gap semiconductor Sb2S3 is widely used in the area of solar cells because of its high light absorption coefficient and suitable bandgap width. However, numerous deep-level defects provide plentiful photogenerated carrier recombination sites, which restricts the improvement of photoelectrochemical properties seriously. In this work, S-scheme Sb2S3@CdSexS1–x core-shell quasi-one-dimensional heterojunction photoanodes were prepared on the FTO substrate by a two-step vapor transport deposition (VTD) method, chemical bath deposition (CBD) and in-situ selenization method. The results showed that CdSexS1–x nanoparticles (NPs) were tightly coated on the Sb2S3 nanorods (NRs). The photocurrent density of the Sb2S3@CdSexS1–x photoanodes was 1.61 mA cm–2 under 1.23 VRHE. Compared with the Sb2S3 photoanodes (0.61 mA cm–2), Sb2S3@CdSexS1–x photoanodes obtained a 2.64-fold improvement, and the dark current was effectively reduced. It showed excellent stability and fast photocurrent response in a 600 s optical stability test. It was concluded that: (1) The charge transfer mechanism of the S-scheme can avoid the problem of high recombination rate of photogenerated charge carriers due to the defects of Sb2S3 effectively, and realized spatial separation of photogenerated carriers. (2) The [hk1] oriented Sb2S3 NRs and the formed quasi-one-dimensional heterostructures promote efficient carrier transport. (3) The introduction of Se effectively regulated the band structure of CdS, slowed down the photocorrosion of S, and improved the stability of the photoelectrodes significantly. © 2024
  Accession Number: 20241916035918
• Record 158 of
  
  Title:Environmentally stable all-fiber femtosecond laser for industrial application based on a SESAM mode-locked ytterbium-doped laser
  
  Author(s):Cao, Xue(1,2,3); Li, Feng(1); Song, Dongdong(1); Wang, Yishan(1); Li, Qianglong(1,2,3); Zhao, Hualong(1); Zhao, Wei(1); Wen, Wenlong(1); Si, Jinhai(2)
  Source: Microwave and Optical Technology Letters  Volume: 66  Issue: 4  DOI: 10.1002/mop.34119  Published: April 2024  
  Abstract:We demonstrate an environmentally stable femtosecond laser for industrial application based on all polarization-maintaining Yb-doped laser and experimentally explore the effect of the net cavity dispersion (NCD) on output characteristics. The oscillator emits pulses with 5.1 ps and a 23 nm spectral bandwidth, then the pulse is compressed to 88 fs. The instabilities over 120 h gives 0.32% relative root mean square noise, indicating high stability of the pulse laser. With effective regulation of NCD, we obtained the maximum spectral bandwidth of 27 nm. Such broadband oscillator with compact all-fiber configurations provide extremely high stability should be very attractive for long-term industrial application. © 2024 Wiley Periodicals LLC.
  Accession Number: 20241315798070
• Record 159 of
  
  Title:Study on Stray Light Testing and Suppression Techniques for Large-Field of View Multispectral Space Optical Systems
  
  Author(s):Lu, Yi(1); Xu, Xiping(1); Zhang, Ning(1); Lv, Yaowen(1); Xu, Liang(2)
  Source: IEEE Access  Volume: 12  Issue:   DOI: 10.1109/ACCESS.2024.3369471  Published: 2024  
  Abstract:To evaluate the ability of space optical systems to suppress off-axis stray light, this paper proposes a stray light testing method for large-field of view, multispectral spatial optical systems based on point source transmittance (PST). And a stray light testing platform was developed using a high-brightness simulated light source, large-aperture off-axis reflective collimator, high-precision positioning mechanism and a double column tank to evaluate the stray light PST index of spatial optical system. On the basis of theoretical analyses, a set of calibration lenses and stray light elimination structures such as hoods, baffle and stop are designed for the accuracy calibration of stray light testing systems. The theoretical PST values of the calibration lens at different off-axis angles are analyzed by Trace Pro software simulation and compared with the measured values to calibrate the accuracy of the system. The testing results show that the PST measurement range of the system reaches 10-3 ~10-10 when the off-axis angles of the calibration lens are in the range of ±5? ~ ±60?. The stray light test system has the advantages of wide working band, high automation and large dynamic range, and its test results can be used in the correction of lens hood and other applications. © 2013 IEEE.
  Accession Number: 20240915654572
• Record 160 of
  
  Title:Effective correction of dissolved organic carbon interference in nitrate detection using ultraviolet spectroscopy combined with the equivalent concentration offset method
  
  Author(s):Dong, Jing(1,2); Tang, Junwu(1,3); Wu, Guojun(1,3); Xin, Yu(4); Li, Ruizhuo(1,2); Li, Yahui(3)
  Source: RSC Advances  Volume: 14  Issue: 8  DOI: 10.1039/d3ra08000e  Published: February 12, 2024  
  Abstract:Nitrate contamination in water sources poses a substantial environmental and health risk. However, accurate detection of nitrate in water, particularly in the presence of dissolved organic carbon (DOC) interference, remains a significant analytical challenge. This study investigates a novel approach for the reliable detection of nitrate in water samples with varying levels of DOC interference based on the equivalent concentration offset method. The characteristic wavelengths of DOC were determined based on the first-order derivatives, and a nitrate concentration prediction model based on partial least squares (PLS) was established using the absorption spectra of nitrate solutions. Subsequently, the absorption spectra of the nitrate solutions were subtracted from that of the nitrate-DOC mixed solutions to obtain the difference spectra. These difference spectra were introduced into the nitrate prediction model to calculate the equivalent concentration offset values caused by DOC. Finally, a DOC interference correction model was established based on a binary linear regression between the absorbances at the DOC characteristic wavelengths and the DOC-induced equivalent concentration offset values of nitrate. Additionally, a modeling wavelength selection algorithm based on a sliding window was proposed to ensure the accuracy of the nitrate concentration prediction model and the equivalent concentration offset model. The experimental results demonstrated that by correcting the DOC-induced offsets, the relative error of nitrate prediction was reduced from 94.44% to 3.36%, and the root mean square error of prediction was reduced from 1.6108 mg L−1 to 0.1037 mg L−1, which is a significant correction effect. The proposed method applied to predict nitrate concentrations in samples from two different water sources shows a certain degree of comparability with the standard method. It proves that this method can effectively correct the deviations in nitrate measurements caused by DOC and improve the accuracy of nitrate measurement. © 2024 The Royal Society of Chemistry.
  Accession Number: 20240815567105
• Record 161 of
  
  Title:A semi-supervised cross-modal memory bank for cross-modal retrieval
  
  Author(s):Huang, Yingying(1,2,3); Hu, Bingliang(3); Zhang, Yipeng(1,2,3); Gao, Chi(1,2,3); Wang, Quan(1,3)
  Source: Neurocomputing  Volume: 579  Issue:   DOI: 10.1016/j.neucom.2024.127430  Published: April 28, 2024  
  Abstract:The core of semi-supervised cross-modal retrieval tasks lies in leveraging limited supervised information to measure the similarity between cross-modal data. Current approaches assume an association between unlabelled data and pre-defined k-nearest neighbour data, relying on classifier performance for this selection. With diminishing labelled data, classifier performance weakens, resulting in erroneous associations among unlabelled instances. Moreover, the lack of interpretability in class probabilities of unlabelled data hinders classifier learning. Thus, this paper focuses on learning pseudo-labels for unlabelled data, providing pseudo-supervision to aid classifier learning. Specifically, a cross-modal memory bank is proposed, dynamically storing feature representations in a common space and class probability representations in a label space for each cross-modal data. Pseudo-labels are derived by computing feature representation similarity and adjusting class probabilities. During this process, imposing constraints on the classification loss between labelled data and contrastive losses between paired cross-modal data is a prerequisite for the successful learning of pseudo-labels. This procedure significantly contributes to enhancing the credibility of these pseudo-labels. Empirical findings demonstrate that using only 10% labelled data, compared to prevailing semi-supervised techniques, this method achieves improvements of 2.6%, 1.8%, and 4.9% in MAP@50 on the Wikipedia, NUS-WIDE, and MS-COCO datasets, respectively. © 2024
  Accession Number: 20241015679996
• Record 162 of
  
  Title:Satellite Pose Measurement Using an Improving SIFT Algorithm
  
  Author(s):Zhang, Renhao(1,2); Zhou, Zuofeng(1,3)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 13063  Issue:   DOI: 10.1117/12.3021301  Published: 2024  
  Abstract:Due to the strong reflective properties of the spacecraft surface coatings, there are significant challenges in processing images from outer space. Furthermore, the volume of data for image feature processing and matching is immense, and existing algorithms are insufficient for aerospace system applications. Therefore, this paper proposes a three-dimensional pose measurement algorithm based on binocular vision. The binocular vision-based three-dimensional pose measurement system consists of four main components: camera calibration, camera rectification, stereo matching, and pose determination. Traditional image processing algorithms are employed for satellite image processing. Camera calibration is performed using M software, and the calibration results are further optimized. Due to real-time requirements, an improved SIFT algorithm is used to detect local features in the images, extract feature points, and perform feature point matching under epipolar constraints. Experimental results demonstrate that this algorithm can achieve accurate and fast three-dimensional pose measurement. © 2024 SPIE.
  Accession Number: 20241115744309
• Record 163 of
  
  Title:Fractional Fourier-Based Frequency-Spatial-Spectral Prototype Network for Agricultural Hyperspectral Image Open-Set Classification
  
  Author(s):Chen, Maoyang(1,2); Feng, Shou(1,2,3); Zhao, Chunhui(1); Qu, Bo(2,4,5); Su, Nan(1); Li, Wei(3); Tao, Ran(3)
  Source: IEEE Transactions on Geoscience and Remote Sensing  Volume: 62  Issue:   DOI: 10.1109/TGRS.2024.3386566  Published: 2024  
  Abstract:At present, hyperspectral image classification (HSIC) technology has been warmly concerned in all walks of life, especially in agriculture. However, existing classification methods operate under the closed-set assumption, which deviates from the real world with open properties. At the same time, there are more serious phenomena of different crops with similar spectrums and the same crops with different spectrum in agricultural hyperspectral data, which is also a great challenge to existing methods. In this work, a fractional Fourier-based frequency-spatial-spectral prototype network (FrFSSPN) is proposed to address the challenges of open-set HSIC in agricultural scenarios. First, fractional Fourier transform (FrFT) is introduced into the network to combine the information in the frequency domain with the spatial-spectral information, so as to expand the difference between different classes on the premise of ensuring the similarity between classes. Then, the prototype learning strategy is introduced into the network to improve the feature recognition capability of the network through prototype loss. Finally, in order to break the stubbornly closed-set property of the closed-set classification (CSC) method, the open-set recognition module is proposed. The difference between the prototype vector and the feature vector is used to judge the unknown class. Experiments on three agricultural hyperspectral datasets show that this method can effectively identify unknown classes without sacrificing the classification accuracy of closed-set, and has satisfactory classification performance. © 1980-2012 IEEE.
  Accession Number: 20241615917288
• Record 164 of
  
  Title:Luminescence properties of ZnSxO1-x:Ce3+ phosphors with tunable short fluorescence lifetime
  
  Author(s):Xing, Xue(1,2,3); Cao, Weiwei(1,3,4); Wu, Zhaoxin(2); Bai, Xiaohong(1); Gao, Jiarui(1); Liang, Xiaozhen(1); Wang, Bo(1); Wang, Chao(1); Shi, Dalian(1); Lv, Linwei(1); Bai, Yonglin(1)
  Source: Materials Letters  Volume: 355  Issue:   DOI: 10.1016/j.matlet.2023.135472  Published: January 15, 2024  
  Abstract:Fluorescence lifetime of phosphors is a critical index in the field of high energy physics and astrophysical detection. A series of ZnSxO1-x:0.05Ce3+ phosphors with tunable short fluorescence lifetime were prepared by performing high temperature solid state reaction method. The phosphors exhibited two mixed phases consisting of the hexagonal phase ZnO and the hexagonal phase ZnS. They are spherical and the average particle size is 2.24 μm. As the component content of the ZnS in ZnSxO1-x:0.05Ce3+ phosphors varies, the emission wavelength can be tuned from 448 nm to 495 nm, the short fluorescence lifetime can be tuned within the range of 6 μs–200 μs. By performing exponential fitting, we obtained the equation for the variation of fluorescence lifetime of ZnSxO1-x:0.05Ce3+ phosphors with ZnS fraction. © 2023 Elsevier B.V.
  Accession Number: 20234414987304
• Record 165 of
  
  Title:Design of multi-channel sequential front light imaging system for transient condition
  
  Author(s):Zhang, Zhanfei(1); Huang, Jie(2); Song, Qiang(2); Feng, Fei(1); Ding, Jianwen(2)
  Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering  Volume: 32  Issue: 4  DOI: 10.37188/OPE.20243204.0478  Published: February 2024  
  Abstract:In order to obtain stable and high-quality sequential images under transient condition and different object distances, a four-channel sequential front light high-speed imaging system was designed. The system used image space parallel light splitting, taking the imaging principle as the starting point to analyze the key design elements of system. Based on the theoretical calculation parameters, the sub-lens groups (objective lens group, field mirror and collimating lens group, converging lens group) was designed and aberrations were independently corrected. Adding field mirror to reduce the size and weight of system and improve light energy utilization. The transmission effect of beam was improved by accurate connection of field of view and pupil. On this basis, the sub lens groups were integrated and optimized, and beam splitters were added to form the final four-channel sequential front light imaging system. The object distance adjustable optical path was designed, and the image quality of system at the object distance of 0.5 m~∞ was guaranteed by adjusting the handwheel of objective lens group in use, while keeping the position of primary image plane unchanged, enhancing the stability of system performance stability and reducing the difficulty of installation and adjustment. The receiving part of system can be replaced according to actual needs, and the system can be expanded to eight-channel system after adding splitters in the beam splitting region. The installed and adjusted sequential front-light imaging system is used for laboratory testing and field tests, and main optical performance is good. the resolution of each channel can reach 72 lp/mm, and imaging consistency is greater than 98%. Field test results show that the optical system can meet the requirements for shooting sequence images under transient condition. © 2024 Chinese Academy of Sciences. All rights reserved.
  Accession Number: 20241115748899
• Record 166 of
  
  Title:Scintillation Index and Bit Error Rate of Double Laguerre-Gaussian Vortex Beams under Ocean Turbulence
  
  Author(s):Diao, Luxin(1); Wang, Mingjun(1,2,3); Huang, Chaojun(3); Wu, Xiaohu(4); Wang, Wei(5)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 53  Issue: 2  DOI: 10.3788/gzxb20245302.0201002  Published: February 2024  
  Abstract:The oceans have a large amount of unexplored resources，so the exploration area of human beings is moving towards the unknown ocean as land resources are getting scarce. Underwater wireless optical communication technology with higher rates and better security has become the key to underwater environmental monitoring，wireless sensor networks，offshore exploration and communication between submarines. Vortex beams are a class of beams with helical phase wavefront carrying Orbital Angular Momentum（OAM），which have been widely used in the fields of optical communication，remote sensing and super-resolution imaging due to their specific helical phase structure and dark hollow ring light intensity distribution. The transmission of vortex beams in seawater environments is interfered by ocean turbulence，which results in light intensity scintillation，phase undulation and spot drift，which can degrade the communication quality. However，as human activities extend from free space to the marine environment，the demand for the communication capacity of underwater optical communication systems is increasing，so it is of great significance to study the coded communication of underwater vortex beams and their superposition states，and to further explore methods to suppress the effect of ocean turbulence on the transmission of the beams，for the underwater vortex optical communication systems. In this paper，power spectrum inversion method are used to establish a phase screen model of ocean turbulence，simulate real ocean turbulence，and study the light intensity and phase characteristics of Double Laguerre-Gaussian Vortex Beam （DLGVB） generated by coaxial superposition during transmission in ocean turbulence. The scintillation index of DLVGB beam under different ocean turbulence parameters and topological charge difference is simulated and analyzed. According to the scintillation index，the bit error rate of the underwater optical communication system based on On-off Keying（OOK）modulation under different ocean turbulence parameters is further calculated， and the bit error rate of the optical communication system under different topological charge difference is simulated and analyzed. The results show that the scintillation index of Double Laguerre-Gaussian Vortex Beam（DLGVB）increases with the decrease of turbulent kinetic energy dissipation rate，the increase of transmission distance，salinity temperature fluctuation equilibrium parameter and temperature variance dissipation rate. The main reason is that the intensity of ocean turbulence will gradually increase with the decrease of turbulent kinetic energy dissipation rate and the increase of salinity temperature fluctuation equilibrium parameter and temperature variance dissipation rate. Compared with the traditional Laguerre Gaussian vortex beam，the DLGVB beam with lower topological charge difference（v © 2024 Chinese Optical Society. All rights reserved.
  Accession Number: 20240715561741
• Record 167 of
  
  Title:Feasible spindle speed interval identification method for large aeronautical component robotic milling system
  
  Author(s):Wang, Zhanxi(1); Zhang, Banghai(1); Gao, Wei(2); Qin, Xiansheng(1); Zhang, Yicha(3); Zheng, Chen(1)
  Source: Mechatronics  Volume: 99  Issue:   DOI: 10.1016/j.mechatronics.2024.103143  Published: May 2024  
  Abstract:Robotic machining systems have been widely implemented in the assembly sites of large components of aircraft, such as wings, aircraft engine rooms, and wing boxes. Milling is the first step in aircraft assembly. It is considered one of the most significant processes because the quality of the subsequent drilling, broaching, and riveting steps depend strongly on the milling accuracy. However, the chatter phenomenon may occur during the milling process because of the low rigidity of the components of the robotic milling system (i.e., robots, shape-preserving holders, and rod parts). This may result in milling failure or even fracture of the robotic milling system. This paper presents a feasible spindle speed interval identification method for large aeronautical component milling systems to eliminate the chatter phenomenon. It is based on the chatter stability model and the analysis results of natural frequency and harmonic response. Firstly, the natural frequencies and harmonics of the main components of the robot milling system are analyzed, and the spindle speed that the milling system needs to avoid is obtained. Then, a flutter stability model considering the instantaneous cutting thickness is established, from which the critical cutting depth corresponding to the spindle speed can be obtained. Finally, the spindle speed interval of the robotic milling system could be optimized based on the results obtained from the chatter stability model and the analysis result of the natural frequency and harmonic response of the milling system. The effectiveness of the proposed spindle speed interval identification method is validated through time-domain simulation and experimental results of the large aeronautical component milling system. © 2024 Elsevier Ltd
  Accession Number: 20240715537558
• Record 168 of
  
  Title:Influencing mechanisms of hot isostatic pressing on surface properties of additively manufactured AlSi10Mg alloy
  
  Author(s):Sun, Lijun(1,2); Yang, Yulei(3); Li, Siyuan(2); Chen, Wencong(2); Wang, Yichun(2); Yan, Peng(2); Zhu, Yueqi(2); Wu, Weichao(1); Hu, Bingliang(2)
  Source: Journal of Materials Processing Technology  Volume: 329  Issue:   DOI: 10.1016/j.jmatprotec.2024.118426  Published: August 2024  
  Abstract:Additively manufactured AlSi10Mg alloys have received considerable attention due to the prospectives in light-weight structural applications. Hot isostatic pressing (HIP) is widely utilized to minimize internal pores and enhance mechanical properties in terms of fatigue strength and ductility. Whereas the influence and mechanisms of HIP on surface properties, which is of crucial importance for aerospace optical components, remain to be further clarified. In the present study, systematic surface and subsurface analysis were conducted to unveil the underlying mechanisms of HIP on the surface qualities of an additively manufactured AlSi10Mg alloy. Three-dimensional white-light interfering profilometer, high-resolution X-ray micro computed tomography, X-ray diffraction, scanning electron microscope and transmission electron microscope were exploited to characterize the surface and subsurface alterations induced by HIP. The results demonstrate that, although remarkable reduction in the amount and size of internal pores can be achieved, sharp increase in the surface defects and roughness occurred for the precisely machined surface of the HIP treated alloy. Surface and subsurface analysis reveal that the deterioration in surface properties results from the establishment of micron Si particles and the reduction in nanohardness induced by HIP treatment. © 2024 Elsevier B.V.
  Accession Number: 20241916054071