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The Active Compensation Technique for Large Reflector Antennas Based on Quadratic Curve Fitting

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Research in Astronomy and Astrophysics 2024年第7期24卷 229-237页

作者： Tian-Xiang Zheng Bin-Bin Xiang Han-Wei Cui Wei Wang Pei-Yuan Lian Shang-Ming Lin Yang Zhang Jian-Ping Zhou Kai Li School of Mechanical Engineering Xinjiang University School of Mechano-Electronic Engineering Xidian University Xi'an Institute of Optics and precision mechanics Chinese Academy of Sciences

Active reflectors are often used to compensate the surface distortion caused by environmental factors that degrade the electromagnetic performance of large high-frequency reflector antennas. This is crucial for maintaining high gain operation in antennas. A distortion compensation method for the active reflector of a large dual-reflector antenna is proposed. A relationship is established between the surface deformation and the optical path difference for the primary reflector by geometric optics. Subsequently, employing finite element analysis, a polynomial fitting approach is used to describe the impact of adjusting points on the reflector surface based on the coordinates of each node. By standardizing the positions of various panels on the reflector, the fitting ns can be applied to the reflector panels of similar shapes. Then, based on the distribution characteristics of the primary reflector panels, the adjustment equation for the actuators is derived by the influence matrix method. It can be used to determine the adjustment amount of actuators to reduce the rms of the optical path difference. And, the least squares method is employed to resolve the matrix equation. The example of a 110 m aperture dual-reflector antenna is carried out by finite element analysis and the proposed method. The results show that the optical path difference is reduced significantly at various elevation cases, which indicates that the proposed method is effective.

关键词： Methods: analytical Methods: numerical Telescopes

Multilevel Attention Unet Segmentation Algorithmfor Lung Cancer Based on CT Images

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Computers, Materials & Continua 2024年第2期78卷 1569-1589页

作者： Huan Wang Shi Qiu Benyue Zhang Lixuan Xiao Xi’an Institute of Optics and precision mechanics Chinese Academy of SciencesXi’anChina School of Biomedical Engineering Fourth Military Medical UniversityXi’anChina University of Illinois at Urbana Champion ChampaignUSA

Lung cancer is a malady of the lungs that gravely jeopardizes human ***,early detection and treatment are paramount for the preservation of human *** computed tomography(CT)image sequences can explicitly delineate the pathological condition of the *** meet the imperative for accurate diagnosis by physicians,expeditious segmentation of the region harboring lung cancer is of utmost *** utilize computer-aided methods to emulate the diagnostic process in which physicians concentrate on lung cancer in a sequential manner,erect an interpretable model,and attain segmentation of lung *** specific advancements can be encapsulated as follows:1)Concentration on the lung parenchyma region:Based on 16-bit CT image capturing and the luminance characteristics of lung cancer,we proffer an intercept histogram algorithm.2)Focus on the specific locus of lung malignancy:Utilizing the spatial interrelation of lung cancer,we propose a memory-based Unet architecture and incorporate skip connections.3)Data Imbalance:In accordance with the prevalent situation of an overabundance of negative samples and a paucity of positive samples,we scrutinize the existing loss function and suggest a mixed loss *** results with pre-existing publicly available datasets and assembled datasets demonstrate that the segmentation efficacy,measured as Area Overlap Measure(AOM)is superior to 0.81,which markedly ameliorates in comparison with conventional algorithms,thereby facilitating physicians in diagnosis.

关键词： Lung cancer computed tomography computer-aided diagnosis Unet segmentation

Hyperspectral Image Based Interpretable Feature Clustering Algorithm

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Computers, Materials & Continua 2024年第5期79卷 2151-2168页

作者： Yaming Kang PeishunYe Yuxiu Bai Shi Qiu School of Information Engineering Yulin UniversityYulin719000China Key Laboratory of Spectral Imaging Technology CAS Xi’an Institute of Optics and Precision MechanicsChinese Academy of SciencesXi’an710119China

Hyperspectral imagery encompasses spectral and spatial dimensions,reflecting the material properties of *** application proves crucial in search and rescue,concealed target identification,and crop growth *** is an important method of hyperspectral *** vast data volume of hyperspectral imagery,coupled with redundant information,poses significant challenges in swiftly and accurately extracting features for subsequent *** current hyperspectral feature clustering methods,which are mostly studied from space or spectrum,do not have strong interpretability,resulting in poor comprehensibility of the ***,this research introduces a feature clustering algorithm for hyperspectral imagery from an interpretability *** commences with a simulated perception process,proposing an interpretable band selection algorithm to reduce data *** this,amulti-dimensional clustering algorithm,rooted in fuzzy and kernel clustering,is developed to highlight intra-class similarities and inter-class *** optimized P systemis then introduced to enhance computational *** system coordinates all cells within a mapping space to compute optimal cluster centers,facilitating parallel *** approach diminishes sensitivity to initial cluster centers and augments global search capabilities,thus preventing entrapment in local minima and enhancing clustering *** conducted on 300 datasets,comprising both real and simulated *** results show that the average accuracy(ACC)of the proposed algorithm is 0.86 and the combination measure(CM)is 0.81.

关键词： Hyperspectral fuzzy clustering tissue P system band selection interpretable

Aerosol jet printing of surface acoustic wave microfluidic devices

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Microsystems & Nanoengineering 2024年第1期10卷 231-242页

作者： Joseph Rich Brian Cole Teng Li Brandon Lu Hanyu Fu Brittany N.Smith Jianping Xia Shujie Yang Ruoyu Zhong James L.Doherty Kanji Kaneko Hiroaki Suzuki Zhenhua Tian Aaron D.Franklin Tony Jun Huang Department of Biomedical Engineering Duke UniversityDurhamNC 27708USA Department of Electrical and Computer Engineering Duke UniversityDurhamNC 27708USA Department of Mechanical Engineering Virginia Polytechnic Institute and State UniversityBlacksburgVA 24061USA Thomas Lord Department of Mechanical Engineering and Materials Science Duke UniversityDurhamNC 27708USA deptartment of precision mechanics Faculty of Science and EngineeringChuo UniversityTokyo 112-8551Japan Department of Chemistry Duke UniversityDurhamNC 27708USA

The addition of surface acoustic wave(SAW)technologies to microfluidics has greatly advanced lab-on-a-chip applications due to their unique and powerful attributes,including high-precision manipulation,versatility,integrability,biocompatibility,contactless nature,and rapid ***,the development of SAW microfluidic devices is limited by complex and time-consuming micro/nanofabrication techniques and access to cleanroom facilities for multistep photolithography and vacuum-based *** simplify the fabrication of SAW microfluidic devices with customizable dimensions and functions,we utilized the additive manufacturing technique of aerosol jet *** successfully fabricated customized SAW microfluidic devices of varying materials,including silver nanowires,graphene,and poly(3,4-ethylenedioxythiophene)polystyrene sulfonate(PEDOT:PSS).To characterize and compare the acoustic actuation performance of these aerosol jet printed SAW microfluidic devices with their cleanroom-fabricated counterparts,the wave displacements and resonant frequencies of the different fabricated devices were directly measured through scanning laser Doppler ***,to exhibit the capability of the aerosol jet printed devices for lab-on-a-chip applications,we successfully conducted acoustic streaming and particle concentration ***,we demonstrated a novel solution-based,direct-write,single-step,cleanroom-free additive manufacturing technique to rapidly develop SAW microfluidic devices that shows viability for applications in the fields of biology,chemistry,engineering,and medicine.

关键词： printing wave fluid

O-band reconfigurable silicon polarization rotator

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Chinese Optics Letters 2024年第1期22卷 65-70页

作者：白雅文王鹏飞彭波储涛 State Key Laboratory of Transient Optics and Photonics Xi’an Institute of Optics and Precision MechanicsChinese Academy of Sciences(CAS)Xi’an 710119China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China College of Information Science and Electronic Engineering Zhejiang UniversityHangzhou 310027China

Silicon waveguides typically exhibit optical anisotropy,which leads to polarization correlation and single-polarization *** consequently creates a demand for polarization-control *** paper introduces a CMOS-compatible O-band reconfigurable TE/TM polarization rotator comprising two symmetrical polarization rotator-splitters and phase *** configuration enables dynamic conversion of any linear polarization to its quadratic *** results indicate that the reconfigurable polarization rotator exhibits an insertion loss of less than 1.5 ***,the bandwidth for a polarization extinction ratio beyond 15 dB exceeds 60 nm.

关键词： silicon-based optoelectronics polarization rotation polarization switch

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Dynamic analysis of a novel multilink-spring mechanism for vibration isolation and energy harvesting

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Chinese Physics B 2024年第5期33卷 366-379页

作者：谢佳衡杨涛唐介 Research & Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China Department of Engineering mechanics Northwest Polytechnical UniversityXi'an 710072China Applied mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and AerospaceSouthwest Jiaotong UniversityChengdu 610031China

Due to technical limitations,existing vibration isolation and energy harvesting(VIEH)devices have poor performance at low *** paper proposes a new multilink-spring mechanism(MLSM)that can be used to solve this *** VIEH performance of the MLSM under harmonic excitation and Gaussian white noise was *** was found that the MLSM has good vibration isolation performance for low-frequency isolation and the frequency band can be widened by adjusting parameters to achieve a higher energy harvesting *** comparison with two special cases,the results show that the MLSM is basically the same as the other two oscillators in terms of vibration isolation but has better energy harvesting performance under multistable *** MLSM is expected to reduce the impact of vibration on high-precision sensitive equipment in some special sites such as subways and mines,and at the same time supply power to structural health monitoring devices.

关键词： multilink-spring mechanism nonlinear dynamics vibration isolation energy harvester

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Two-dimensional localized modes in nonlinear systems with linear nonlocality and moiré lattices

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Frontiers of physics 2024年第4期19卷 265-273页

作者： Xiuye Liu Jianhua Zeng Center for Attosecond Science and Technology State Key Laboratory of Transient Optics and PhotonicsXi’an Institute of Optics and Precision Mechanics of Chinese Academy of SciencesXi’an 710119China University of Chinese Academy of Sciences Beijing 100049China Collaborative lnnovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Periodic structures structured as photonic crystals and optical lattices are fascinating for nonlinear waves engineering in the optics and ultracold atoms ***éphotonic and optical lattices—two-dimensional twisted patterns lie somewhere in between perfect periodic structures and aperiodic ones—are a new emerging investigative tool for studying nonlinear localized waves of diverse ***,a theory of two-dimensional spatial localization in nonlinear periodic systems with fractional-order diffraction(linear nonlocality)and moiréoptical lattices is ***,the flat-band feature is well preserved in shallow moiréoptical lattices which,interact with the defocusing nonlinearity of the media,can support fundamental gap solitons,bound states composed of several fundamental solitons,and topological states(gap vortices)with vortex charge s=1 and 2,all populated inside the finite gaps of the linear Bloch-wave *** the linear-stability analysis and direct perturbed simulations,the stability and instability properties of all the localized gap modes are surveyed,highlighting a wide stability region within the first gap and a limited one(to the central part)for the third *** findings enable insightful studies of highly localized gap modes in linear nonlocality(fractional)physical systems with shallow moirépatterns that exhibit extremely flat bands.

关键词： moiréoptical lattices gap solitons and vortices ultracold atoms Gross-Pitaevskii/nonlinear fractional Schrödinger equation nonlinear fractional systems

A low-frequency pure metal metamaterial absorber with continuously tunable stiffness

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Applied Mathematics and mechanics(English Edition) 2024年第7期45卷 1209-1224页

作者： Xingzhong WANG Shiteng RUI Shaokun YANG Weiquan ZHANG Fuyin MA School of Mechanical Engineering Xi'an Jiaotong University Xi'an precision Machinery Research Institute

To address the incompatibility between high environmental adaptability and deep subwavelength characteristics in conventional local resonance metamaterials,and overcome the deficiencies in the stability of existing active control techniques for band gaps, this paper proposes a design method of pure metal vibration damping metamaterial with continuously tunable stiffness for wideband elastic wave absorption. We design a dual-helix narrow-slit pure metal metamaterial unit, which possesses the triple advantage of high spatial compactness, low stiffness characteristics, and high structural stability, enabling the opening of elastic flexural band gaps in the low-frequency *** to the principle of a sliding rheostat, the introduction of continuously sliding plug-ins into the helical slits enables the continuous variation of the stiffness of the metamaterial unit, achieving a continuously tunable band gap effect. This successfully extends the effective band gap by more than ten times. The experimental results indicate that this metamaterial unit can be used as an additional vibration absorber to absorb the low-frequency vibration energy effectively. Furthermore, it advances the metamaterial absorbers from a purely passive narrowband design to a wideband tunable one. The pure metal double-helix metamaterials retain the subwavelength properties of metamaterials and are suitable for deployment in harsh environments. Simultaneously, by adjusting its stiffness, it substantially broadens the effective band gap range, presenting promising potential applications in various mechanical equipment operating under adverse conditions.

关键词： elastic metamaterial absorber continuously tunable stiffness low-frequency vibration damping variable stiffness design pure metal structure O343 74G60

Specifications and control of spatial frequency errors of components in two-beam laser static holographic exposure for pulse compression grating fabrication

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High Power Laser Science and Engineering 2024年第1期12卷 1-12页

作者： Chen Hu Songlin Wan Guochang Jiang Haojin Gu Yibin Zhang Yunxia Jin Shijie Liu Chengqiang Zhao Hongchao Cao Chaoyang Wei Jianda Shao precision Optical Manufacturing and Testing Center Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences(CAS)ShanghaiChina Key Laboratory for High Power Laser Material of Chinese Academy of Sciences Shanghai Institute of Optics and Fine MechanicsCASShanghaiChina Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijingChina Hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhouChina China-Russian Belt and Road Joint Laboratory on Laser Science ShanghaiChina

The large-aperture pulse compression grating(PCG) is a critical component in generating an ultra-high-intensity, ultra-short-pulse laser;however, the size of the PCG manufactured by transmission holographic exposure is limited to large-scale high-quality materials. The reflective method is a potential way for solving the size limitation, but there is still no successful precedent due to the lack of scientific specifications and advanced processing technology of exposure mirrors. In this paper, an analytical model is developed to clarify the specifications of components, and advanced processing technology is adopted to control the spatial frequency errors. Hereafter, we have successfully fabricated a multilayer dielectric grating of 200 mm × 150 mm by using an off-axis reflective exposure system with Φ300 mm. This demonstration proves that PCGs can be manufactured by using the reflection holographic exposure method and shows the potential for manufacturing the meter-level gratings used in 100 petawatt class high-power lasers.

关键词： high-power laser off-axis reflective exposure system pulse compression grating spatial frequency errors specifications

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