2020
2020
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Record 313 of
Title:Under-oil self-driven and directional transport of water on a femtosecond laser-processed superhydrophilic geometry-gradient structure
Author(s):Wu, Junrui(1); Yin, Kai(1,2); Li, Ming(3); Wu, Zhipeng(1); Xiao, Si(1); Wang, Hua(1); Duan, Ji-An(2); He, Jun(1)Source: Nanoscale Volume: 12 Issue: 6 DOI: 10.1039/c9nr09902f Published: February 14, 2020Abstract:Self-driven and continuous directional transport of water droplets in an oil environment has great potential applications in microfluidics, oil-water separation, etc. Nevertheless, most current studies exploit water behaviors occurring in air, and the directional regulation of water in a viscous oil medium remains a challenge. In this work, a superhydrophilic geometry-gradient stainless steel platform with nanoparticle-covered nanoripple structures is proposed using femtosecond laser direct writing technology. The as-prepared platform spontaneously and directionally transported water droplets in the oil environment from the minor side to the large side of the trapezoidal platform surface, but not in the opposite direction. The transport velocity of water droplets as a function of trapezoid angle and tilt angle of the as-prepared platform was investigated in detail. In addition, a pumpless under-oil water transport platform was successfully prepared on other substrates including Ti and Ni sheets, polyimide film, and C cloth, and exhibited transport capabilities when the platform was flexed and combined into various shapes. This work offers insight into the simple fabrication of a flexible and substrate-independent pumpless under-oil directional transport device for water. ? The Royal Society of Chemistry 2020.Accession Number: 20200808206148 -
Record 314 of
Title:Catadioptric optical system design of 15-magnitude star sensor with large entrance pupil diameter
Author(s):Bai, Yang(1); Li, Jianlin(1,2); Zha, Rongwei(1); Wang, Ying(1); Lei, Guangzhi(2)Source: Sensors (Switzerland) Volume: 20 Issue: 19 DOI: 10.3390/s20195501 Published: October 1, 2020Abstract:The optical system is one of the core components for star sensors, whose imaging quality directly influences the performance of star sensors for star detection, thereby determining the attitude control accuracy of spacecrafts. Here, we report a new type of optical system with a catadioptric structure and a large entrance pupil diameter for a 15-magnitude star sensor. It consists of an improved Cassegrain system (R-C system), an aperture correction spherical lens group and a field of view correction spherical lens group. By embedding the secondary mirror of the R-C system into the output surface of the negative spherical lens of the aperture correction spherical lens group, the blocking of incident light is eliminated from the secondary mirror holder. After the structure optimization, the catadioptric optical system (COS) had a spectral range of 450 nm950 nm, an entrance pupil diameter of 250 mm, a half-diagonal field of view of 1.4? and a focal length of 390 mm. By using theoretical calculations and experimental measurements, it was verified that the COS, with the ability to correct astigmatism, lateral color and distortion, can fulfill the detection of 15-magnitude dark stars. ? 2020 by the authors. Licensee MDPI, Basel, Switzerland.Accession Number: 20204109323818 -
Record 315 of
Title:A color correction method in uniform color space
Author(s):Chu, Nanqing(1,2); Li, Xuyang(1,2); Yi, Hongwei(1,2); Ren, Zhiguang(1,3); Ma, Zixuan(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11567 Issue: DOI: 10.1117/12.2580277 Published: 2020Abstract:In the process of restoring the image of space optical camera, it is necessary to use the standard 24 color card to correct the image. In order to improve the accuracy of the mapping function in the process of color correction and prevent the occurrence of overfitting at the same time, a neural network correction method with comprehensive objective function is proposed. Using the idea of regularization as a reference, a constraint term with smooth performance is added to the objective function of the neural network to improve the generalization ability of the network map to data. The experimental results on the dataset of the real color card of the space camera sho-ore the correction. ? 2020 SPIE.Accession Number: 20205009602470 -
Record 316 of
Title:Design of optical system for laser removal of foreign bodies in high voltage transmission line
Author(s):Cai, Yong(1); Xiao, Maosen(1); Liu, Yang(2); Liu, Aimin(1); Gao, Peng(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11455 Issue: DOI: 10.1117/12.2565342 Published: 2020Abstract:High-voltage and ultra-high-voltage transmission cables are exposed to natural environment all the year round. Plastic and other non-metallic foreign bodies are often overlapped on cables, towers, insulators and other power grid facility, which leads to poor insulation among high-voltage power cables, and becomes one of the major threats to the normal operation of power systems. As a new light source, laser has a good application prospect in the removal of non-metallic foreign bodies such as polymers because of its high energy, strong monochromatic and good coherence. The use of laser to remove non-metallic foreign bodies such as plastics winding on transmission lines has the advantages of fastness, high efficiency, safety, so it has been widely used in the removal of foreign bodies in high-voltage and ultra-high voltage power lines. In this paper, the mechanism of laser ablation is analyzed and the optical system of laser ablation unit is designed. According to the actual situation of laser ablation of polymer for transmission line, the diameter of laser spot at 10-180m is determined to be 32mm. In the consideration of the error factors, the imaging quality of the optical focusing unit for the designed optical system is simulated. At the same time, the far-field characteristics of the laser are simulated and studied. The results show that the range of RMS SPOT radius change is less than the diffraction limit radius by sensitivity analysis of laser ablation unit considering errors. The designed optical focusing unit has good imaging quality and meets the requirements. With the increase of laser transmission distance, the diameter of laser spot increases slightly. The maximum spot diameter at 180m is 29mm, which is less than the design value. The designed optical system can meet the needs for laser ablation of polymer and has good effect. ? 2020 SPIE.Accession Number: 20203709173676 -
Record 317 of
Title:Research and Progress of Low-expansion β-eucryptite Composites
Author(s):Xue, Yaohui(1); Jiang, Junbiao(1); Zhang, Hui(1); Wen, Changxiu(2); Su, Zongfeng(1); Cui, Xiaoxia(2); Guo, Haitao(2)Source: Cailiao Daobao/Materials Reports Volume: 34 Issue: 3 DOI: 10.11896/cldb.18100095 Published: March 10, 2020Abstract:Thermal expansion coefficient is one of the important parameters of materials. In nature, most materials exhibit high thermal expansion coefficient which would lead to the phenomenon of thermal-expansion and cold-contraction. Therefore, these materials usually have poor thermal shock resistance and cannot be used in the environment with great temperature changes. The signal distortion usually occurs because of the destruction of aerospace components and the deformation of electronic device resulted from the uneven temperature distribution. It is exciting that there are a few materials with negative thermal expansion coefficient, and their volume decreases with the increase of temperature. Based on the additivity of the expansion coefficient, the compounds with low coefficient of thermal expansion can be obtained by introducing the material with low or negative coefficient of thermal expansion into the high ones, which can remarkably improve their thermal shock resistance. Negative thermal expansion materials include isotropic negative thermal expansion materials and anisotropic negative thermal expansion mate-rials. Isotropic negative thermal expansion materials are mainly ZrV2-xPxO7 and ZrW2O8 series. Anisotropic negative thermal expansion materials mainly include β-eucryptite, perovskite series, A2M3O12series, M(CN)2 (M=Zn, Cd) series, oxides, zeolite series and metal organic frameworks (MOFs), etc. The β-eucryptite is usually used to adjust the thermal expansion coefficient of composite materials owing to its negative thermal expansion coefficient (α=-6.1×10-6 K-1), low density (2.67 g/cm3), good thermal shock resistance, dielectric properties and infrared radiation. Composite materials with negative thermal expansion or near zero thermal expansion can be fabricated by compounding with other materials, which can greatly improve the thermal shock resistance and dimensional stability of the materials, and thus prolong the life of the materials. Therefore, β-eucryptite has been used to manufacture low expansion ceramics, glass-ceramics, metal matrix composites applied as fillers for electrical equipment, electronic components, device sealants, aircraft high precision components, humidity sensor sensitive materials and lithium ion battery so-lid electrolytes. At the same time, due to the anisotropic thermal expansion property of β-eucryptite, the composites will have more residual stress and lower mechanical strength. In order to solve this problem, fibers or whiskers with high mechanical strength can be introduced to form three-phase composites with low expansion and high mechanical strength, which is beneficial to expand the application of materials in inertial missiles, optic fiber gyro and other aerospace applications. In this paper, the research status and progress of the low expansion two-phase or three-phase composites of metals, glass and ceramics are reviewed. The preparation method, thermal properties and application fields of these low expansion coefficient composites are summarized. The future development trends and application prospects of the composites are also discussed. ? 2020, Materials Review Magazine. All right reserved.Accession Number: 20201408379534 -
Record 318 of
Title:Edge effect removal in Fourier ptychographic microscopy via periodic plus smooth image decomposition
Author(s):Pan, An(1,2); Wang, Aiye(1,2,4); Zheng, Junfu(3); Gao, Yuting(1,2,4); Ma, Caiwen(1,2,4); Yao, Baoli(1,2)Source: arXiv Volume: Issue: DOI: 10.48550/arXiv.2009.03138 Published: September 7, 2020Abstract:Fourier ptychographic microscopy (FPM) is a promising computational imaging technique with high resolution, wide field-of-view (FOV) and quantitative phase recovery. So far, a series of system errors that may corrupt the image quality of FPM has been reported. However, an imperceptible artifact caused by edge effect caught our attention and may also degrade the precision of phase imaging in FPM with a cross-shape artifact in the Fourier space. We found that the precision of reconstructed phase at the same subregion depends on the different sizes of block processing as a result of different edge conditions, which limits the quantitative phase measurements via FPM. And this artifact is caused by the aperiodic image extension of fast Fourier transform (FFT). Herein, to remove the edge effect and improve the accuracy, two classes of opposite algorithms termed discrete cosine transform (DCT) and periodic plus smooth image decomposition (PPSID) were reported respectively and discussed systematically. Although both approaches can remove the artifacts in FPM and may be extended to other Fourier analysis techniques, PPSID-FPM has a comparable efficiency to conventional FPM algorithm. The PPSID-FPM algorithm improves the standard deviation of phase accuracy as a factor of 4 from 0.08 radians to 0.02 radians. Finally, we summarized and discussed all the reported system errors of FPM within a generalized model. Copyright ? 2020, The Authors. All rights reserved.Accession Number: 20200597014 -
Record 319 of
Title:Research on Gait Planning Algorithm of Quadruped Robot Based on Central Pattern Generator
Author(s):Ma, Zihan(1); Liang, Yanbing(1); Tian, Hua(1)Source: Chinese Control Conference, CCC Volume: 2020-July Issue: DOI: 10.23919/CCC50068.2020.9188942 Published: July 2020Abstract:The characteristics of Hopf oscillator are analyzed, and the feasibility of its application in gait generation of quadruped robot is discussed. Two kinds of CPG control networks are constructed by using Hopf oscillator and the structures of the two networks are analyzed and modeled. These two CPG can produce stable gait with strict phase relationship. The robot simulation software Webots and MATLAB are used for co-simulation. According to the output control signal of CPG network, each joint of quadruped robot is controlled and trot gait planning is realized. The simulation results show that the CPG network constructed by Hopf oscillator can achieve good gait planning for quadruped robot, which has the advantages of simple model and clear thinking. ? 2020 Technical Committee on Control Theory, Chinese Association of Automation.Accession Number: 20203909242335 -
Record 320 of
Title:Calculation of verticality in large-aperture optical centering machinery turning
Author(s):Yu, Lei(1); Xing, Fu(1); Shifa, Kang(1); Xihong, Fu(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11568 Issue: DOI: 10.1117/12.2579432 Published: 2020Abstract:Large-Aperture Optical Centering Machinery Turning technology has been widely used in precision optical machine assembly. The main principle is to make optical axis and machine axis coincide by maintaining the collimation image and structural end face unchanged when rotating. Structural parts are fabricated precisely after than. This process requires good verticality between the end face of the optical element and its optical axis. A specific method is required to calculate the verticality of the end face and the optical axis. This paper proposed a method based on self-collimated image deviation control and least squares fitting. Combining with an example, numerical calculation is carried out with error analysis. Finally the verticality is 21um which provides reliable data guarantee for the selection of the reference during optical centering fabricating processing. ? 2020 SPIE. All rights reserved.Accession Number: 20204909580545 -
Record 321 of
Title:Latest research progress in zinc anode of secondary Zn-air batteries
Author(s):Zhang, Xing(1); Zhu, Li-Xia(1); Wang, Xiao-Cong(1); Li, Shu-Ping(1); Wang, Hong-Fei(2); Su, Zhou(2)Source: Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals Volume: 30 Issue: 8 DOI: 10.11817/j.ysxb.1004.0609.2020-35842 Published: August 1, 2020Abstract:Zinc-air battery has attracted widespread attention due to the high theoretical energy, excellent safety and low cost, which is hopeful to be a candidate for energy storage devices in applications like electric vehicles and portable electronic devices. Zinc anode, as the key part of zinc-air battery, has many disadvantages, such as dendrite growth, shape change, passivation and hydrogen evolution etc, which limits the further development and commercialization of secondary zinc-air battery. Thus, how to solve above problems existing in zinc anode has become an research focus of zinc-air battery. The key to develop zinc-air battery includes the design and preparation of zinc anode materials with outstanding reversibility and long cycle life, which mainly concentrates on the additives, alloying, coating of zinc anode and hybrid battery. In this context, some new findings and the latest progress on the anode of zinc-based battery in recent years are introduced, which can be applied to secondary zinc-air battery. ? 2020, Science Press. All right reserved.Accession Number: 20204209362295 -
Record 322 of
Title:Measurement of moisture content in lubricating oils of high-speed rail gearbox by Vis-NIR spectroscopy
Author(s):Liu, Chenyang(1,2); Tang, Xingjia(3); Yu, Tao(3); Wang, Taisheng(1); Lu, Zhenwu(1); Yu, Weixing(3)Source: Optik Volume: 224 Issue: DOI: 10.1016/j.ijleo.2020.165694 Published: December 2020Abstract:The moisture content in lubricating oil is one of the most important factors to reflect the health and effectiveness of it, thus to monitor the moisture content in lubricating oil in real time is crucial for high speed rail. In this paper, we developed a compact moisture-content monitoring system based on the visible-near-infrared (Vis-NIR) spectroscopy technology, which was shown to be able to determine the moisture content in lubricating oil in a fast, simple and accurate way. In this system, a reflection mode optical probe was developed for sending and receiving optical signals through the viewport of gear box. By employing the reflection optical probe, one can measure the spectrum of the lubricating oil in a fast way by simply putting the probe on viewport of gear box, and therefore has the potential to realize the real-time monitoring of the status of the lubricating oil. In order to verify the feasibility of the system, both reflection and transmission spectral of lubricating oil were taken. Partial least square regression (PLS) and back propagation neural network (BPNN) algorithms were used to establish the processing model. Modelling results show a good agreement in between two different probing modes. As a result, the effectiveness and reliability of the system have been proved, which provides a simple yet accurate method for real time monitoring the healthy status of the lubricating oil for the safe operation of the high-speed rail. ? 2020 Elsevier GmbHAccession Number: 20204109332448 -
Record 323 of
Title:Thermal Infrared Tracking using Multi-stages Deep Features Fusion
Author(s):Zhang, Ximing(1); Chen, Rongli(1); Liu, Gang(1); Li, Xuyang(1); Luo, Shujuan(2); Fan, Xuewu(1)Source: Proceedings of the 32nd Chinese Control and Decision Conference, CCDC 2020 Volume: Issue: DOI: 10.1109/CCDC49329.2020.9164750 Published: August 2020Abstract:Thermal infrared (TIR) tracking can be utilized to track the target in the images generated by thermal infrared sensors due to the weak influence by illumination changes. However, there are still some challenges to do thermal infrared tracking when suffering drastic appearance variation, heavy occlusion and background clutters. The absence of RGB patterns and low resolution also constrain the tracking performance in complex scenarios. The deep convolutional features are widely utilized to solve visual tracking problems which successfully extracted the spatial and semantic information though object representation. Motivated by these methods, we firstly propose to combine multi-stages cascaded Siamese networks to achieve deep features fusion in three stages, then achieve the tracking procedure by candidates matching strategy. The final results are obtained by non-maximum suppression and scale penalty. The proposed method can inherit the advantages by fusing multi-stages deep features and achieve end-to-end learning simultaneously. The experiments are evaluated with state-of-the-art methods on VOT-TIR2016 benchmark and attributes based comparison. The tracking results demonstrate that our proposed method outperforms the compared methods in terms of accuracy and robustness. ? 2020 IEEE.Accession Number: 20204009255169 -
Record 324 of
Title:High power 250W CW conductively cooled diode laser arrays with low-smile
Author(s):Zhang, Hongyou(1,2,4); Zhu, Pengfei(4); Fu, Tuanwei(4); Li, Meiqin(4); Lv, Ning(4); Li, Wenwei(4); Zah, Chung-En(4); Liu, Xingsheng(2,3,4)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11261 Issue: DOI: 10.1117/12.2540399 Published: 2020Abstract:We have simulated and optimized a conductive cooling structure including the distribution of temperature in active layer, and the deformation of laser to achieve high power operation with low SMILE value. Unlike the traditional conductive cooling structure, our structure improves the heat dissipation efficiency from three aspects: with angle structure in the front of heat sink; double side heat dissipation and without submount packaging technology. In this report, an output power of more than 250W CW from a 4 mm long laser bar with a filling factor of 50% is shown at 240A driving current with a power conversion efficiency of 65%. The thermal rollover of this packaging conductive cooling device can reach 385W at 400A driving current. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20201708569509