2023
2023
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Record 145 of
Title:A Model of Honeybee Population Dynamics and Pollination Prediction
Author(s):Jing, Kaifeng(1); Liu, Zhenpeng(1); Liu, Zihan(1); Yang, Jingtong(1); Yang, Kai(2,3)Source: Proceedings - 2023 3rd Asia-Pacific Conference on Communications Technology and Computer Science, ACCTCS 2023 Volume: null Issue: null Article Number: null DOI: 10.1109/ACCTCS58815.2023.00051 Published: 2023Abstract:Honeybee population dynamics and prediction is the core content of honeybee population ecology research, which is closely related to the development of agriculture, economy and other industries. This paper aims to study honeybee population dynamics and pollination prediction. Firstly, a differential equation model is proposed to analyze the number of bees in a single beehive in detail, and the Elman model is used to further validate it. Then, through a sensitivity analysis of bee colony size, the main factors affecting hive colony size were identified: the egg-laying rate and the number of varroa mites. Furthermore, combined with the differential equation model, a beehive prediction model for crop pollination was constructed, which can predict the number of beehives required for crop pollination on a 20-acre (81,000) land. At the same time, the effect of initial beehive colony size on the number of beehives required for pollination of different plants in a given area was studied in depth. The usefulness and applicability of our model is well demonstrated by the reasonable trend and prediction results of colony size obtained by applying the model to real data. Finally, the paper provides an outlook on future research and improvement directions in this field. ? 2023 IEEE.Accession Number: 20232714347091 -
Record 146 of
Title:Correlation filter tracking algorithms against interference of similar object and fast motion
Author(s):Ren, Sixi(1,2,3); Tian, Yan(1,3); Xu, Zhaohui(1,3); Guo, Min(1,3)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12557 Issue: null Article Number: 125570Y DOI: 10.1117/12.2649713 Published: 2023Abstract:fDSST (fast Discriminative Scale Space Tracking) belongs to correlation filter tracking algorithm, which has high success rate and precision, also runs at a fast speed. However, it is still a huge challenge for the tracking scene of fast motion and similar object interference. In order to improve the performance of fDSST on the challenges above, this paper proposed fDSSTs algorithm and fDSSTss algorithm respectively. fDSSTs increases the response scores near the object location by fusing the fhog feature and the color statistical feature, so improved the tracking performance of fDSST in the fast moving scene. fDSSTss adds a multi-feature object association module on the basis of fDSST, which distinguishes the real object and the interference object from the object feature level, thereby maintaining the tracking of the real object. The fDSSTs is tested on the OTB50 dataset, in fast-moving scenarios, the success rate of fDSST is improved by 20.5% and the precision is improved by 22.8% compared with fDSST. The fDSSTss is tested on the test sequences of similar object interference, and the result shows that fDSSTss has better anti-similar object interference ability than fDSST, while meeting the real-time requirements. The experiments show that the improvements improve the success rate and precision of fDSST in fast object moving scenes, as well as the ability to resist similar object interference. ? 2023 SPIE.Accession Number: 20230813600595 -
Record 147 of
Title:Routing to mid-infrared microcomb via near-infrared direct pump
Author(s):Shi, Lei(1,2); Ming, Xianshun(1); Ma, Kai(1); Sun, Qibing(1,2); Wang, Leiran(1,2); Zhao, Wei(1,2); Zhang, Wenfu(1,2)Source: Optics Express Volume: 31 Issue: 13 Article Number: null DOI: 10.1364/OE.494515 Published: June 19, 2023Abstract:Mid-infrared (MIR) microcomb provides a new way into the "molecular fingerprint" region. However, it remains rather a challenge to realize the broadband mode-locked soliton microcomb, which is often limited by the performance of available MIR pump sources and coupling devices. Here, we propose an effective approach towards broadband MIR soliton microcombs generation via a direct pump in the near-infrared (NIR) region, through full utilization of the second- and third-order nonlinearities in a thin-film lithium niobate microresonator. The optical parametric oscillation process contributes to conversion from the pump at 1550 nm to the signal around 3100 nm, and the four-wave mixing effect promotes spectrum expansion and mode-locking process. While the second-harmonic and sum-frequency generation effects facilitate simultaneous emission of the NIR comb teeth. Both the continuous wave and pulse pump sources with relatively low power can support a MIR soliton with a bandwidth over 600 nm and a concomitant NIR microcomb with a bandwidth of 100 nm. This work can provide a promising solution for broadband MIR microcombs by breaking through the limitation of available MIR pump sources, and can deepen the understanding of the physical mechanism of the quadratic soliton assisted by the Kerr effect. ? 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.Accession Number: 20232814370439 -
Record 148 of
Title:A Hybrid Mathematical Models for Predicting Global Climate Change
Author(s):Chen, Taoyue(1); Zhang, Zhaoyue(1); Yi, Zilu(1); Xu, Wenxi(1); Yang, Kai(2,3)Source: Proceedings - 2023 3rd Asia-Pacific Conference on Communications Technology and Computer Science, ACCTCS 2023 Volume: null Issue: null Article Number: null DOI: 10.1109/ACCTCS58815.2023.00052 Published: 2023Abstract:The industrial revolution marked the beginning of modernization in human civilization, and also marked the sharp rise in greenhouse gas emissions and global temperatures. To better understand trends in global climate change, we aim to utilize data on carbon dioxide levels and land-ocean temperatures to learn past trends and predict future changes. First, the CO2 concentration dataset, using statistical methods, is analyzed and visualized. From the statistical summary and graphs, it can be concluded that the global CO2 level has been constantly increasing since the 1960s. Based on the dataset, three models were constructed to analyze the changing trend of CO2 levels in the past and extrapolate the future: Autoregressive Integrated Moving Average (ARIMA), grey forecast, and a more refined prediction model that considers factors affecting CO2 levels with Long Short Term Memory (LSTM). All three models disagree that the CO2 level will reach 685 PPM by 2050. And each model predicts CO2 level of 685 PPM will be reached by the end of the century and when. Afterward, the pros and cons of the models are compared. Second, the model of the changes in global land-ocean temperature is constructed. ARIMA is used to model and predict the upcoming temperature and the time when it is going to reach certain designated points. Pearson's correlation shows a strong correlation between global temperature and CO2 level. Hence, these two variables are modeled with linear regression. However, the regression-based predictions did not match the forecast from earlier models, so an refined model incorporating more variables and perspectives was built. The refined model is a more bottom-up approach. It quantifies the radiative forcing of individual factors and makes predictions based on the predicted outcomes of each factor. The model predicts the temperature difference of 3.55 °C from the base period, 1.25 °C in 2031, 1.5 °C in 2039, and 2 °C in 2052. ? 2023 IEEE.Accession Number: 20232714347029 -
Record 149 of
Title:Flexible dynamic quantitative phase imaging based on division of focal plane polarization imaging technique
Author(s):Fan, Chen(1); Li, Junxiang(1); Du, Yijun(1); Hu, Zirui(1); Chen, Huan(1); Yang, Zewen(1); Zhang, Gaopeng(2); Zhang, Lu(1); Zhao, Zixin(1); Zhao, Hong(1)Source: Optics Express Volume: 31 Issue: 21 Article Number: null DOI: 10.1364/OE.498239 Published: October 9, 2023Abstract:This paper proposes a flexible and accurate dynamic quantitative phase imaging (QPI) method using single-shot transport of intensity equation (TIE) phase retrieval achieved by division of focal plane (DoFP) polarization imaging technique. By exploiting the polarization property of the liquid crystal spatial light modulator (LC-SLM), two intensity images of different defocus distances contained in orthogonal polarization directions can be generated simultaneously. Then, with the help of the DoFP polarization imaging, these images can be captured with single exposure, enabling accurate dynamic QPI by solving the TIE. In addition, our approach gains great flexibility in defocus distance adjustment by adjusting the pattern loaded on the LC-SLM. Experiments on microlens array, phase plate, and living human gastric cancer cells demonstrate the accuracy, flexibility, and dynamic measurement performance for various objects. The proposed method provides a simple, flexible, and accurate approach for real-time QPI without sacrificing the field of view. ? 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.Accession Number: 20234314949549 -
Record 150 of
Title:Polarization-multiplexed metasurface enabled tri-functional imaging
Author(s):Ge, Suyang(1,2); Li, Xingyi(1); Liu, Zilei(1,2); Zhao, Jiaqi(1,2); Wang, Wanjun(1,2); Li, Siqi(1); Zhang, Wenfu(1,2)Source: Optics Letters Volume: 48 Issue: 21 Article Number: null DOI: 10.1364/OL.502632 Published: 2023Abstract:Diffraction-limited focusing imaging, edge-enhanced imaging, and long depth of focus imaging offer crucial technical capabilities for applications such as biological microscopy and surface topography detection. To conveniently and quickly realize the microscopy imaging of different functions, the multifunctional integrated system of microscopy imaging has become an increasingly important research direction. However, conventional microscopes necessitate bulky optical components to switch between these functionalities, suffering from the system’s complexity and unstability. Hence, solving the problem of integrating multiple functions within an optical system is a pressing need. In this work, we present an approach using a polarization-multiplexed tri-functional metasurface, capable of realizing the aforementioned imaging functions simply by changing the polarization state of the input and output light, enhancing the system structure’s compactness and flexibility. This work offers a new avenue for multifunctional imaging, with potential applications in biomedicine and microscopy imaging. ? 2023 Optica Publishing Group.Accession Number: 20234515021759 -
Record 151 of
Title:Femtosecond Time?Resolved Electronic States in Femtosecond Laser Multipulse Ablation
Author(s):Wang, Qianhao(1,2); Zhao, Hualong(1); Yang, Xiaojun(1); Wen, Wenlong(1); Li, Yi(1,2)Source: Zhongguo Jiguang/Chinese Journal of Lasers Volume: 50 Issue: 24 Article Number: 2402101 DOI: 10.3788/CJL230834 Published: December 2023Abstract:Objective This study investigates the prevalent process problems, such as"microcracking"and"induced streaking,"in the femtosecond laser processing of hard and brittle transparent materials. The study employs the femtosecond time-resolved pump-probe shadow imaging technique to visualize the electron dynamics during the femtosecond laser multi-pulse ablation of quartz glass. Particularly, the plasma filament evolution at the early stage of laser pulse ionization (before 700 fs) is analyzed. The multi-pulseinduced microstructures distribute the filament formation regions on both sides of the microstructure with respect to the axial direction of the light pulse propagation. The distribution on both sides is primarily due to the refraction of the light pulse by the sidewalls of the microstructure, while that on the axis is caused by the difference in the shape of the bottom and sidewalls of the microstructure, creating the light range difference. The empirical results show that the pulse train induces a remodeling effect of the microstructure on the subsequent light field during multi-pulse processing, affecting the distribution of the plasma filament formation region and energy deposition—the core mechanism responsible for common process problems. Methods A femtosecond time-resolved pump-probe shadow imaging setup was built to capture the propagation and ionization process of a single subsequent pulse beneath the microstructure induced by irradiating the material with 219 fs pulses. First, the actual spatial location of the focus was determined by imaging the shadow of the air- ionized plasma at the focus. After that, the power density at the material surface was obtained for different focus positions. The distinctive"V"and"inverted trapezoid"shapes were obtained after controlling the relative positions of the laser focus and the material. Second, the ionization process of femtosecond timeresolved propagation of the 220th pulse under different microstructures was obtained by modulating the time delay between pump and probe beams. Finally, the ionized filament- forming regions in the transient ionization images were compared with the process defects to reveal the formation mechanism of the process defects. Results and Discussions The propagation and ionization process of the 220th pulse is observed using femtosecond time- resolved pump- probe shadow imaging (Figs. 5. 6. 9. 10). The physical mechanisms governing process problems such as"microcracking"in micromachining of hard and brittle materials are revealed. The light- field remodeling effect, guided by various morphology microstructures, leads to energy deposition and the mechanism of generating common process problems. In the context of multi- pulse processing, the influence of energy deposition (propagation and ionization) is determined by the linear refractive index of the material, a nonlinear refractive index that varies with the light intensity, plasma defocusing effect, microstructure morphology, and the focusing conditions in conjunction with the laser fluence on the material surface. Moreover, the relaxation time of ionized free electron number density during light field propagation is determined to be less than 300 fs across diverse microstructures. Conclusions Under multi- pulse irradiation, the remodeling effect of different microstructural morphologies on the subsequent light field orchestrates the nonlinear ionization process. In the case of the V- shaped structure, the formation process is accompanied by decreasing tilt angle of the sidewalls, guiding the ionization filamentation direction of the subsequent light field and sweeping across the sidewall region. It corresponds to the areas of "microcracks" and "induced stripes" on both sides of the microstructure. Conversely, the"inverted trapezoidal"structure yields strong ionization filament formation at its relatively flat bottom center region owing to the ionization effect at the bottom of the structure. For the"inverted trapezoidal"structure, a strong ionization effect occurs at the center of the relatively flat bottom, which is the root cause of the fragmentation at the bottom. Overall, the light- field remodeling effect, facilitated by different morphology microstructures, plays a crucial role in energy deposition and governing the common process problems. This result offers directions for optimizing machining processes, such as selecting the number of pulses and controlling the focal feed. Additionally, the high- temporal- resolution pump- probe shadow imaging technique holds promise for predicting fragmentation regions in different morphologies of hard and brittle transparent materials, serving as a powerful tool for online monitoring of high- end processing equipment. ? 2023 Science Press. All rights reserved.Accession Number: 20235115228548 -
Record 152 of
Title:Research on spatial frequency shift super-resolution imaging based on evanescent wave illumination
Author(s):Ling, Jin-Zhong(1,2); Guo, Jin-Kun(1); Wang, Yu-Cheng(1); Liu, Xin(1); Wang, Xiao-Rui(1)Source: Wuli Xuebao/Acta Physica Sinica Volume: 72 Issue: 22 Article Number: 224202 DOI: 10.7498/aps.72.20230934 Published: November 20, 2023Abstract:In spite of the success of fluorescence microscopes (such as stimulated emission depletion microscopy, stochastic optical reconstruction microscopy and photoactivated localization microscopy) in biomedical field, which have realized nanometer scale imaging resolution and promoted the great development of bio-medicine, the super-resolution imaging method for non-fluorescent sample is still scarce, and the resolution still has a big gap to nanometer scale. Among existing methods, structured illumination microscopy, PSF engineering, super-oscillatory lens and microsphere assisted nanoscopy are more mature and widely used. However, limited by the theory itself or engineering practice, the resolutions of these methods are hard to exceed 50 nm, which limits their applications in many fields. Enlightened by synthetic aperture technique, researchers have proposed spatial frequency shift super-resolution microscopy through shifting and combining the spatial frequency spectrum of imaging target, which is a promising super-resolution imaging scheme, for its resolution limit can be broken through continually. Currently, owing to the limitation of the refractive index of optical material, the wavelength of illumination evanescent wave is hard to shorten when this wave is generated at prism surface via total internal reflection, which determines the highest resolution of this spatial frequency shift super-resolution imaging system. Another deficiency of this scheme is the difference in imaging resolution among different directions, for the image has the highest resolution only in the direction along the wave vector of illumination evanescent wave; while, the image has the lowest resolution in the direction perpendicular to the wave vector, which is the same as that obtained by far-field illumination. In order to solve the above thorny questions, a new model of generating the evanescent wave is proposed, which can generates an omnidirectional evanescent wave with arbitrary wavelength based on the phase modulation of nano-structure, and solve the both problem in imaging system at the same time. To verify the our scheme, we set up a complete simulation model for spatial frequency shift imaging scheme, which includes three parts: the generation of evanescent wave and the interaction of the evanescent wave with the nano-structures at imaging target, which can be simulated with FDTD algorithm; the propagation of light field from near-field to far-field region, from the sample surface to the focal plane of objective lens, which can be calculated with angular spectrum theory; the propagation of light field from the focal place to the image plane, which can be worked out with Chirp-Z transform. Firstly, with this complete simulation model, we compare the resolution of microscopy illuminated by evanescent wave with that by propagating wave. The experimental results verify the super-resolution imaging ability of evanescent wave illumination and the influence of prism refractive index. The higher the refractive index, the shorter the wavelength of evanescent wave is and the higher the resolution of spatial frequency shift imaging system. Secondly, we demonstrate the resolution difference in a series of directions with a three-bar imaging target rotated to different directions. The result shows that the highest imaging resolution occurs in the direction of illumination evanescent wave vector, and the lowest resolution appears in the direction perpendicular to the wave vector. Finally, we simulate the evanescent wave generated by nano-strcuture and demonstrate its properties of wavelength and vector direction. When applied to near-field illumination super-resolution imaging, the omnidirectional evanescent wave solves the both problems in the model of total internal reflection from the prism surface. Therefore, the advantages of our scheme are higher imaging resolution and faster imaging speed, no need for multi-direction and multiple imaging, and also image post-processing. In this study, a new spatial frequency shift super-resolution imaging method is proposed, which lays a theoretical foundation for its applications. ? 2023 Chinese Physical Society.Accession Number: 20234815132784 -
Record 153 of
Title:Characterization of the angular memory effect of dynamic turbid media
Author(s):Li, Runze(1); Peng, Tong(1); Bai, Chen(1); Wang, Ping(1); Zhou, Meiling(1); Yu, Xianghua(1); Min, Junwei(1); Yao, Baoli(1,2)Source: Optics Express Volume: 31 Issue: 17 Article Number: 27594 DOI: 10.1364/OE.495970 Published: August 14, 2023Abstract:The optical angular memory effect (AME) is a basic feature of turbid media and defines the correlation of speckles when the incident light is tilted. AME based imaging through solid scattering media such as ground glass and biomedical tissue has been recently developed. However, in the case of liquid media such as turbid water or blood, the speckle pattern exhibits dynamic time-varying characteristics, which introduces several challenges. The AME of the thick volume dynamic media is particularly different from the layer scatterers. In practice, there are more parameters, e.g., scattering particle size, shape, density, or even the illuminating beam aperture that can influence the AME range. Experimental demonstration of AME phenomenon in liquid dynamic media and confirm the distinctions will contribution to complete the AME theory. In this paper, a dual-polarization speckle detection setup was developed to characterize the AME of dynamic turbid media, where two orthogonal polarized beams were employed for simultaneous detection by a single CCD. The AME of turbid water, milk and blood were measured. The influence of thickness, concentration, particle size and shape, and beam diameter were analyzed. The AME increasement of upon the decrease of beam diameter was tested and verified. The results demonstrate the feasibility of this method for investigating the AME phenomenon and provide guidance for AME based imaging through scattering media. ? 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.Accession Number: 20233614674264 -
Record 154 of
Title:Cascaded transfer of optical frequency with a relay station over a 224 km deployed fiber link
Author(s):Zang, Qi(1,3,4); Deng, Xue(1,2,3); Zhang, Xiang(1,3); Wang, Dan(1,2,3); Zhou, Qian(1,2,3); Jiao, Dongdong(1,3); Xu, Guanjun(1,3); Gao, Jing(1,3); Liu, Jie(1,3); Liu, Tao(1,2,3); Dong, Ruifang(1,2,3); Zhang, Shougang(1,2,3)Source: Infrared Physics and Technology Volume: 128 Issue: null Article Number: 104511 DOI: 10.1016/j.infrared.2022.104511 Published: January 2023Abstract:In this paper, we demonstrate a cascaded transfer of optical frequency with a relay station over a fiber link. The station is outfitted to cascade numerous lines with independent phase locking and provide high optical gain. The relay station receives the signal from the former link and compensates for the power loss with a two-stage EDFA (erbium-doped fiber amplification), and seeds the amplified signal into the next fiber link. By actively suppressing the parasitic noise with a two-stage EDFA, low-noise optical amplification with 50 dB gain is achieved. The two-stage EDFA's simple phase-locking structure also guarantees the system's long-term stability and reliable operation. With this relay station, we transfer a laser frequency along with a 224 km deployed fiber link, and the frequency at the remote end achieves a fractional instability of 3.39×10?16 at 1 s averaging time on a 2 Hz measurement bandwidth, reaching 8.36×10?19 at 10,000 s. This work paves a way for the future fiber optical frequency transfer network across the nationwide area and it has the potential to be an important part of the cascaded transfer network. ? 2022 Elsevier B.V.Accession Number: 20225213300071 -
Record 155 of
Title:Lifetime prediction method for high-power laser diodes under double-stress cross-step accelerated degradation test
Author(s):Zhang, Yeqi(1,2); Wang, Zhenfu(1); Li, Te(1); Chen, Lang(1); Zhang, Jiachen(1); Wu, Shunhua(1,2); Liu, Jiachen(1,2); Yang, Guowen(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 52 Issue: 5 Article Number: 20220592 DOI: 10.3788/IRLA20220592 Published: May 2023Abstract:Objective High reliability becomes very important for the application of high-power laser diodes, and lifetime prediction is the primary aspect of reliability assessment of high-power laser diodes. Accelerated degradation test is a test method to accelerate the degradation process in the laboratory in accordance with the degradation model, which can obtain statistically significant lifetime prediction in a short time. With the advancement of device technology and its reliability, single-stress accelerated degradation test faces problems such as long test time, high cost, and excessive stress application in the degradation mechanism. Therefore, it is necessary to propose an accelerated degradation test for lifetime prediction of highly reliable and long-lived devices. For this purpose, a double-stress cross-step accelerated degradation technological method is designed in this paper. Methods A double-stress cross-step accelerated degradation test is proposed. Aging test platform for high-power laser diodes was built (Fig.5). The device (Fig.4) was subjected to 1600 h accelerated degradation test, and the accelerated degradation data of optical output power under different stress conditions were collected (Tab.1). Performance degradation model was established to analyze the data with the accelerated model to obtain the lifetime prediction values, and the accuracy of the model was tested for significance (Tab.5). Results and Discussions The overall scheme of high-power laser diodes lifetime prediction (Fig.1) has three main steps of bringing degradation data into the model, fitting the lifetime probability density distribution function, and checking accuracy. The double-stress cross-step accelerated degradation test sets the temperature and current as the stress conditions, and the two stress conditions are cross-stepped to form a total of four different stress conditions (Fig.2) as A [22 ℃, 1.4 A], B [42 ℃, 1.4 A], C [42 ℃, 1.8 A], and D [62 ℃, 1.8 A], respectively. The performance degradation model is built according to the YamaKoshi equation and the laser optical output power failure threshold is set. The acceleration model is established according to the generalized Irene model, and the degradation track of the optical output power during the accelerated degradation test is expressed as a segmentation function. After the estimation of the model conversion parameters, the lifetime prediction results were obtained and the parameter errors were compared (Tab.5), and they were all below 10%, which verified the accuracy of the model. Conclusions The accelerated degradation test of 12 830 nm F-mount single-emitter device was conducted for 1600 h using four different current-temperature double-stress conditions in cross-step by self-designed experimental platform. The MTTF of the device is 5 811 h. The accelerated test method used in this paper saves at least 57.7% of the test time compared with the conventional single-stress constant accelerated lifetime test method, and has the advantages of less sample size and more flexibility in stress conditions. The method has been experimentally validated to provide statistically significant results for device lifetime prediction with experimental cost savings for different high-power laser diodes. ? 2023 Chinese Society of Astronautics. All rights reserved.Accession Number: 20232814374566 -
Record 156 of
Title:Influence of airborne LiDAR wavelength on the detection distance of clear air turbulence
Author(s):Zhao, Jing(1,2,3); Luo, Xiujuan(1,3); Liu, Zhaohui(1,3); Liu, Hui(1,2,3); Chen, Minglai(1,2,3); Zhang, Yu(1,3); Yue, Zelin(1,2,3)Source: Optical Engineering Volume: 62 Issue: 11 Article Number: null DOI: 10.1117/1.OE.62.11.114101 Published: November 1, 2023Abstract:We comprehensively investigated the influence of laser wavelength on the detection distance at different clear air turbulence (CAT) intensities, distance resolutions, and Brunt-V?is?l? frequency theoretically. It is found that there exists the optimal wavelength for maximal detection distance. When the distance resolution is fixed, the detection distance of 532 nm LiDAR is further compared with the 355 and 1064 nm counterparts and is more suitable under moderate to severe CAT. Our findings break the traditional cognition that "ultraviolet wavelength LiDAR is the most suitable for CAT detection"and may promote the remote detection research of CAT. ? 2023 SPIE.Accession Number: 20235015221355