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Wide-Angle Scanning Antennas for Millimeter-Wave 5G Applications 被引量:2
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作者 Raj Mittra Abdelkhalek Nasri Ravi Kumar Arya 《Engineering》 SCIE EI 2022年第4期60-71,共12页
The fifth generation(5G)network communication systems operate in the millimeter waves and are expected to provide a much higher data rate in the multi-gigabit range,which is impossible to achieve using current wireles... The fifth generation(5G)network communication systems operate in the millimeter waves and are expected to provide a much higher data rate in the multi-gigabit range,which is impossible to achieve using current wireless services,including the sub-6 GHz band.In this work,we briefly review several existing designs of millimeter-wave phased arrays for 5G applications,beginning with the low-profile antenna array designs that either are fixed beam or scan the beam only in one plane.We then move on to array systems that offer two-dimensional(2D)scan capability,which is highly desirable for a majority of 5G applications.Next,in the main body of the paper,we discuss two different strategies for designing scanning arrays,both of which circumvent the use of conventional phase shifters to achieve beam scanning.We note that it is highly desirable to search for alternatives to conventional phase shifters in the millimeter-wave range because legacy phase shifters are both lossy and costly;furthermore,alternatives such as active phase shifters,which include radio frequency amplifiers,are both expensive and power-hungry.Given this backdrop,we propose two different antenna systems with potential for the desired 2D scan performance in the millimeter-wave range.The first of these is a Luneburg lens,which is excited either by a 2D waveguide array or by a microstrip patch antenna array to realize 2D scan capability.Next,for second design,we turn to phased-array designs in which the conventional phase shifter is replaced by switchable PIN diodes or varactor diodes,inserted between radiating slots in a waveguide to provide the desired phase shifts for scanning.Finally,we discuss several approaches to enhance the gain of the array by modifying the conventional array configurations.We describe novel techniques for realizing both one-dimensional(1D)and 2D scans by using a reconfigurable metasurface type of panels. 展开更多
关键词 Luneburg lens scanning arrays Millimeter-wave antennas Switchable phase shifters Reconfigurable metasurfaces
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A Review of Wideband Wide-Angle Scanning 2-D Phased Array and Its Applications in Satellite Communication 被引量:2
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作者 Yan Li Shaoqiu Xiao Jiajia Guo 《Journal of Communications and Information Networks》 2018年第1期21-30,共10页
In this review,research progress on the wideband wide-angle scanning two-dimensional phased arrays is summarized.The importance of the wideband and the wide-angle scanning characteristics for satellite communication i... In this review,research progress on the wideband wide-angle scanning two-dimensional phased arrays is summarized.The importance of the wideband and the wide-angle scanning characteristics for satellite communication is discussed.Issues like grating lobe avoidance,active reflection coefficient suppression and gain fluctuation reduction are emphasized in this review.Besides,techniques to address these issues and methods to realize the wideband wide-angle scanning phased array are reviewed. 展开更多
关键词 WIDEBAND wide-angle scanning twodimensional phased array satellite communication
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Acousto-optic scanning multi-photon lithography with high printing rate
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作者 Minghui Hong 《Opto-Electronic Advances》 SCIE EI CAS CSCD 2024年第2期1-3,共3页
As a manufacturing method that is focused on end-users,3D printing has gained a lot of attention in recent years due to its unique advantages in fabricating complex three-dimensional structures.Various new micro-nano ... As a manufacturing method that is focused on end-users,3D printing has gained a lot of attention in recent years due to its unique advantages in fabricating complex three-dimensional structures.Various new micro-nano 3D printing methods have been developed to meet the demand for high-precision and high-yield manufacturing1-9.Among them,multi-photon-photon lithography(MPL) is a promising 3D nanofabrication technology due to its capability of true 3D digital processing and nanoscale processing resolution beyond the diffraction limit.It has been widely used to fabricate microoptics10,11,photonic crystals12,microfluidics13,meta-surfaces14,and mechanical metamaterials15. 展开更多
关键词 PHOTON Acous scanning
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Investigation of reflection anisotropy induced by micropipe defects on the surface of a 4H-SiC single crystal using scanning anisotropy microscopy
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作者 黄威 俞金玲 +7 位作者 刘雨 彭燕 王利军 梁平 陈堂胜 徐现刚 刘峰奇 陈涌海 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第3期630-637,共8页
Optical reflection anisotropy microscopy mappings of micropipe defects on the surface of a 4H-SiC single crystal are studied by the scanning anisotropy microscopy(SAM)system.The reflection anisotropy(RA)image with a&#... Optical reflection anisotropy microscopy mappings of micropipe defects on the surface of a 4H-SiC single crystal are studied by the scanning anisotropy microscopy(SAM)system.The reflection anisotropy(RA)image with a'butterfly pattern'is obtained around the micropipes by SAM.The RA image of the edge dislocations is theoretically simulated based on dislocation theory and the photoelastic principle.By comparing with the Raman spectrum,it is verified that the micropipes consist of edge dislocations.The different patterns of the RA images are due to the different orientations of the Burgers vectors.Besides,the strain distribution of the micropipes is also deduced.One can identify the dislocation type,the direction of the Burgers vector and the optical anisotropy from the RA image by using SAM.Therefore,SAM is an ideal tool to measure the optical anisotropy induced by the strain field around a defect. 展开更多
关键词 scanning anisotropy microscopy SiC reflection anisotropy edge dislocation
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A review of understanding electrocatalytic reactions in energy conversion and energy storage systems via scanning electrochemical microscopy
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作者 Jihye Park Jong Hwan Lim +4 位作者 Jin-Hyuk Kang Jiheon Lim Ho Won Jang Hosun Shin Sun Hwa Park 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第4期155-177,共23页
To address climate change and promote environmental sustainability,electrochemical energy conversion and storage systems emerge as promising alternative to fossil fuels,catering to the escalating demand for energy.Ach... To address climate change and promote environmental sustainability,electrochemical energy conversion and storage systems emerge as promising alternative to fossil fuels,catering to the escalating demand for energy.Achieving optimal energy efficiency and cost competitiveness in these systems requires the strategic design of electrocatalysts,coupled with a thorough comprehension of the underlying mechanisms and degradation behavior occurring during the electrocatalysis processes.Scanning electrochemical microscopy(SECM),an analytical technique for studying surface electrochemically,stands out as a powerful tool offering electrochemical insights.It possesses remarkable spatiotemporal resolution,enabling the visualization of the localized electrochemical activity and surface topography.This review compiles crucial research findings and recent breakthroughs in electrocatalytic processes utilizing the SECM methodology,specifically focusing on applications in electrolysis,fuel cells,and metal–oxygen batteries within the realm of energy conversion and storage systems.Commencing with an overview of each energy system,the review introduces the fundamental principles of SECM,and aiming to provide new perspectives and broadening the scope of applied research by describing the major research categories within SECM. 展开更多
关键词 scanning electrochemical microscopy ELECTROCATALYST ELECTROCATALYSIS Water splitting Fuel cell Metal-oxygen battery
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Fatigue properties and damage constitutive model of salt rock based on CT scanning
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作者 Junbao Wang Xiao Liu +3 位作者 Qiang Zhang Xinrong Liu Zhanping Song Shijin Feng 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第2期245-259,共15页
To investigate the macroscopic fatigue properties and the mesoscopic pore evolution characteristics of salt rock under cyclic loading,fatigue tests under different upper-limit stresses were carried out on salt rock,an... To investigate the macroscopic fatigue properties and the mesoscopic pore evolution characteristics of salt rock under cyclic loading,fatigue tests under different upper-limit stresses were carried out on salt rock,and the mesoscopic pore structures of salt rock before and after fatigue tests and under different cycle numbers were measured using CT scanning instrument.Based on the test results,the effects of the cycle number and the upper-limit stress on the evolution of cracks,pore morphology,pore number,pore volume,pore size,plane porosity,and volume porosity of salt rock were analyzed.The failure path of salt rock specimens under cyclic loading was analyzed using the distribution law of plane porosity.The damage variable of salt rock under cyclic loading was defined on basis of the variation of volume porosity with cycle number.In order to describe the fatigue deformation behavior of salt rock under cyclic loading,the nonlinear Burgers damage constitutive model was further established.The results show that the model established can better reflect the whole development process of fatigue deformation of salt rock under cyclic loading. 展开更多
关键词 Salt rock Cyclic loading CT scanning Mesoscopic pore evolution Constitutive model
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Algorithm of automatic identification of diabetic retinopathy foci based on ultra-widefield scanning laser ophthalmoscopy
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作者 Jie Wang Su-Zhen Wang +7 位作者 Xiao-Lin Qin Meng Chen Heng-Ming Zhang Xin Liu Meng-Jun Xiang Jian-Bin Hu Hai-Yu Huang Chang-Jun Lan 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2024年第4期610-615,共6页
AIM:To propose an algorithm for automatic detection of diabetic retinopathy(DR)lesions based on ultra-widefield scanning laser ophthalmoscopy(SLO).METHODS:The algorithm utilized the FasterRCNN(Faster Regions with CNN ... AIM:To propose an algorithm for automatic detection of diabetic retinopathy(DR)lesions based on ultra-widefield scanning laser ophthalmoscopy(SLO).METHODS:The algorithm utilized the FasterRCNN(Faster Regions with CNN features)+ResNet50(Residua Network 50)+FPN(Feature Pyramid Networks)method for detecting hemorrhagic spots,cotton wool spots,exudates,and microaneurysms in DR ultra-widefield SLO.Subimage segmentation combined with a deeper residual network FasterRCNN+ResNet50 was employed for feature extraction to enhance intelligent learning rate.Feature fusion was carried out by the feature pyramid network FPN,which significantly improved lesion detection rates in SLO fundus images.RESULTS:By analyzing 1076 ultra-widefield SLO images provided by our hospital,with a resolution of 2600×2048 dpi,the accuracy rates for hemorrhagic spots,cotton wool spots,exudates,and microaneurysms were found to be 87.23%,83.57%,86.75%,and 54.94%,respectively.CONCLUSION:The proposed algorithm demonstrates intelligent detection of DR lesions in ultra-widefield SLO,providing significant advantages over traditional fundus color imaging intelligent diagnosis algorithms. 展开更多
关键词 diabetic retinopathy ultra-widefield scanning laser ophthalmoscopy intelligent diagnosis system
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Phase behavior of gas condensate in porous media using real-time computed tomography scanning
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作者 Wen-Long Jing Lei Zhang +5 位作者 Ai-Fen Li Jun-Jie Zhong Hai Sun Yong-Fei Yang Yu-Long Cheng Jun Yao 《Petroleum Science》 SCIE EI CAS CSCD 2024年第2期1032-1043,共12页
The phase behavior of gas condensate in reservoir formations differs from that in pressure-volume-temperature(PVT)cells because it is influenced by porous media in the reservoir formations.Sandstone was used as a samp... The phase behavior of gas condensate in reservoir formations differs from that in pressure-volume-temperature(PVT)cells because it is influenced by porous media in the reservoir formations.Sandstone was used as a sample to investigate the influence of porous media on the phase behavior of the gas condensate.The pore structure was first analyzed using computed tomography(CT)scanning,digital core technology,and a pore network model.The sandstone core sample was then saturated with gas condensate for the pressure depletion experiment.After each pressure-depletion state was stable,realtime CT scanning was performed on the sample.The scanning results of the sample were reconstructed into three-dimensional grayscale images,and the gas condensate and condensate liquid were segmented based on gray value discrepancy to dynamically characterize the phase behavior of the gas condensate in porous media.Pore network models of the condensate liquid ganglia under different pressures were built to calculate the characteristic parameters,including the average radius,coordination number,and tortuosity,and to analyze the changing mechanism caused by the phase behavior change of the gas condensate.Four types of condensate liquid(clustered,branched,membranous,and droplet ganglia)were then classified by shape factor and Euler number to investigate their morphological changes dynamically and elaborately.The results show that the dew point pressure of the gas condensate in porous media is 12.7 MPa,which is 0.7 MPa higher than 12.0 MPa in PVT cells.The average radius,volume,and coordination number of the condensate liquid ganglia increased when the system pressure was between the dew point pressure(12.7 MPa)and the pressure for the maximum liquid dropout,Pmax(10.0 MPa),and decreased when it was below Pmax.The volume proportion of clustered ganglia was the highest,followed by branched,membranous,and droplet ganglia.This study provides crucial experimental evidence for the phase behavior changing process of gas condensate in porous media during the depletion production of gas condensate reservoirs. 展开更多
关键词 Gas condensate Pressure depletion Real-time micro-computed tomography scanning Distribution of condensate liquid
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Optical scanning endoscope via a single multimode optical fiber
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作者 Guangxing Wu Runze Zhu +2 位作者 Yanqing Lu Minghui Hong Fei Xu 《Opto-Electronic Science》 2024年第3期1-32,共32页
Optical endoscopy has become an essential diagnostic and therapeutic approach in modern biomedicine for directly observing organs and tissues deep inside the human body,enabling non-invasive,rapid diagnosis and treatm... Optical endoscopy has become an essential diagnostic and therapeutic approach in modern biomedicine for directly observing organs and tissues deep inside the human body,enabling non-invasive,rapid diagnosis and treatment.Optical fiber endoscopy is highly competitive among various endoscopic imaging techniques due to its high flexibility,compact structure,excellent resolution,and resistance to electromagnetic interference.Over the past decade,endoscopes based on a single multimode optical fiber(MMF)have attracted widespread research interest due to their potential to significantly reduce the footprint of optical fiber endoscopes and enhance imaging capabilities.In comparison with other imaging principles of MMF endoscopes,the scanning imaging method based on the wavefront shaping technique is highly developed and provides benefits including excellent imaging contrast,broad applicability to complex imaging scenarios,and good compatibility with various well-established scanning imaging modalities.In this review,various technical routes to achieve light focusing through MMF and procedures to conduct the scanning imaging of MMF endoscopes are introduced.The advancements in imaging performance enhancements,integrations of various imaging modalities with MMF scanning endoscopes,and applications are summarized.Challenges specific to this endoscopic imaging technology are analyzed,and potential remedies and avenues for future developments are discussed. 展开更多
关键词 multimode optical fiber ENDOSCOPE scanning imaging FOCUSING wavefront shaping
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Three-dimensional finite element simulation and reconstruction of jointed rock models using CT scanning and photogrammetry
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作者 Yingxian Lang Zhengzhao Liang Zhuo Dong 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第4期1348-1361,共14页
The geometry of joints has a significant influence on the mechanical properties of rocks.To simplify the curved joint shapes in rocks,the joint shape is usually treated as straight lines or planes in most laboratory e... The geometry of joints has a significant influence on the mechanical properties of rocks.To simplify the curved joint shapes in rocks,the joint shape is usually treated as straight lines or planes in most laboratory experiments and numerical simulations.In this study,the computerized tomography (CT) scanning and photogrammetry were employed to obtain the internal and surface joint structures of a limestone sample,respectively.To describe the joint geometry,the edge detection algorithms and a three-dimensional (3D) matrix mapping method were applied to reconstruct CT-based and photogrammetry-based jointed rock models.For comparison tests,the numerical uniaxial compression tests were conducted on an intact rock sample and a sample with a joint simplified to a plane using the parallel computing method.The results indicate that the mechanical characteristics and failure process of jointed rocks are significantly affected by the geometry of joints.The presence of joints reduces the uniaxial compressive strength (UCS),elastic modulus,and released acoustic emission (AE) energy of rocks by 37%–67%,21%–24%,and 52%–90%,respectively.Compared to the simplified joint sample,the proposed photogrammetry-based numerical model makes the most of the limited geometry information of joints.The UCS,accumulative released AE energy,and elastic modulus of the photogrammetry-based sample were found to be very close to those of the CT-based sample.The UCS value of the simplified joint sample (i.e.38.5 MPa) is much lower than that of the CT-based sample (i.e.72.3 MPa).Additionally,the accumulative released AE energy observed in the simplified joint sample is 3.899 times lower than that observed in the CT-based sample.CT scanning provides a reliable means to visualize the joints in rocks,which can be used to verify the reliability of photogrammetry techniques.The application of the photogrammetry-based sample enables detailed analysis for estimating the mechanical properties of jointed rocks. 展开更多
关键词 X-ray computerized tomography(CT)scanning PHOTOGRAMMETRY Parallel computing Numerical simulation Uniaxial compression test Digital image processing
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In situ observation of the dissolution kinetics of Al_(2)O_(3) particles in CaO–Al_(2)O_(3)–SiO_(2) slags using laser confocal scanning microscopy 被引量:2
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作者 Changyu Ren Caide Huang +1 位作者 Lifeng Zhang Ying Ren 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2023年第2期345-353,共9页
The dissolution kinetics of Al_(2)O_(3) in CaO-Al_(2)O_(3) SiOslags was studied using a high-temperature confocal scanning laser microscope at 1773 to 1873 K.The results show that the controlling step during the Al_(2... The dissolution kinetics of Al_(2)O_(3) in CaO-Al_(2)O_(3) SiOslags was studied using a high-temperature confocal scanning laser microscope at 1773 to 1873 K.The results show that the controlling step during the Al_(2)O_(3) dissolution was the diffusionin molten slag.It was found that the dissolution curves of Al_(2)O_(3) particles were hardly agreed with the traditional boundary layer diffusion model with the increase of the CaO/Al_(2)O_(3) ratio of slag.A modified diffusion equation considering slag viscosity was developed to study the dissolution mechanism of Al_(2)O_(3) in slag.Diffusion coefficients of Al_(2)O_(3) in slag were calculated as 2.8×10to 4.1×10m~2/s at the temperature of 1773-1873 K.The dissolution rate of Al_(2)O_(3) increased with higher temperature,CaO/Al_(2)O_(3),and particle size.A new model was shown to be v_(Al_(2)O_(3))=0.16×r_(0)^(1.58)×x^(3.52)×(T-T_(mp))^(1.11)to predict the dissolution rate and the total dissolution time of Al_(2)O_(3) inclusions with various sizes,where vAl_(2)O_(3) is the dissolution rate of Al_(2)O_(3) in volume,μm^(3)/s;x is the value of CaO/Al_(2)O_(3) mass ratio;R_(0) is the initial radius of Al_(2)O_(3),μm;T is the temperature,K;T_(mp) is the melting point of slag,K. 展开更多
关键词 INCLUSION dissolution kinetics confocal scanning laser microscope refining slag
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Velocity structure in the South Yellow Sea basin based on first-arrival tomography of wide-angle seismic data and its geological implications 被引量:1
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作者 Weina Zhao Zhiqiang Wu +6 位作者 Fanghui Hou Xunhua Zhang Tianyao Hao Hanjoon Kim Yanpeng Zheng Shanshan Chen Huigang Wang 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2023年第2期104-119,共16页
The South Yellow Sea basin is filled with Mesozoic-Cenozoic continental sediments overlying pre-Palaeozoic and Mesozoic-Palaeozoic marine sediments.Conventional multi-channel seismic data cannot describe the velocity ... The South Yellow Sea basin is filled with Mesozoic-Cenozoic continental sediments overlying pre-Palaeozoic and Mesozoic-Palaeozoic marine sediments.Conventional multi-channel seismic data cannot describe the velocity structure of the marine residual basin in detail,leading to the lack of a deeper understanding of the distribution and lithology owing to strong energy shielding on the top interface of marine sediments.In this study,we present seismic tomography data from ocean bottom seismographs that describe the NEE-trending velocity distributions of the basin.The results indicate that strong velocity variations occur at shallow crustal levels.Horizontal velocity bodies show good correlation with surface geological features,and multi-layer features exist in the vertical velocity framework(depth:0–10 km).The analyses of the velocity model,gravity data,magnetic data,multichannel seismic profiles,and drilling data showed that high-velocity anomalies(>6.5 km/s)of small(thickness:1–2 km)and large(thickness:>5 km)scales were caused by igneous complexes in the multi-layer structure,which were active during the Palaeogene.Possible locations of good Mesozoic and Palaeozoic marine strata are limited to the Central Uplift and the western part of the Northern Depression along the wide-angle ocean bottom seismograph array.Following the Indosinian movement,a strong compression existed in the Northern Depression during the extensional phase that caused the formation of folds in the middle of the survey line.This study is useful for reconstructing the regional tectonic evolution and delineating the distribution of the marine residual basin in the South Yellow Sea basin. 展开更多
关键词 ocean bottom seismograph South Yellow Sea basin strata velocity structure wide-angle seismic data CSDP-2
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Acousto-optic scanning spatial-switching multiphoton lithography 被引量:1
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作者 Binzhang Jiao Fayu Chen +6 位作者 Yuncheng Liu Xuhao Fan Shaoqun Zeng Qi Dong Leimin Deng Hui Gao Wei Xiong 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2023年第3期597-606,共10页
Nano-3D printing has obtained widespread attention owing to its capacity to manufacture end-use components with nano-scale features in recent years.Multiphoton lithography(MPL)is one of the most promising 3D nanomanuf... Nano-3D printing has obtained widespread attention owing to its capacity to manufacture end-use components with nano-scale features in recent years.Multiphoton lithography(MPL)is one of the most promising 3D nanomanufacturing technologies,which has been widely used in manufacturing micro-optics,photonic crystals,microfluidics,meta-surface,and mechanical metamaterials.Despite of tremendous potential of MPL in laboratorial and industrial applications,simultaneous achievement of high throughput,high accuracy,high design freedom,and a broad range of material structuring capabilities remains a long-pending challenge.To address the issue,we propose an acousto-optic scanning with spatial-switching multispots(AOSS)method.Inertia-free acousto-optic scanning and nonlinear swept techniques have been developed for achieving ultrahigh-speed and aberration-free scanning.Moreover,a spatial optical switch concept has been implemented to significantly boost the lithography throughput while maintaining high resolution and high design freedom.An eight-foci AOSS system has demonstrated a record-high 3D printing rate of 7.6×10^(7)voxel s^(-1),which is nearly one order of magnitude higher than earlier scanning MPL,exhibiting its promise for future scalable 3D nanomanufacturing. 展开更多
关键词 3D nano-printing acousto-optic scanning aberration-free wavefront spatial-switching
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Automatic identification of rock discontinuity and stability analysis of tunnel rock blocks using terrestrial laser scanning 被引量:1
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作者 Meng Wang Jiawen Zhou +3 位作者 Junlin Chen Nan Jiang Puwen Zhang Haibo Li 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第7期1810-1825,共16页
Local geometric information and discontinuity features are key aspects of the analysis of the evolution and failure mechanisms of unstable rock blocks in rock tunnels.This study demonstrates the integration of terrest... Local geometric information and discontinuity features are key aspects of the analysis of the evolution and failure mechanisms of unstable rock blocks in rock tunnels.This study demonstrates the integration of terrestrial laser scanning(TLS)with distinct element method for rock mass characterization and stability analysis in tunnels.TLS records detailed geometric information of the surrounding rock mass by scanning and collecting the positions of millions of rock surface points without contact.By conducting a fuzzy K-means method,a discontinuity automatic identification algorithm was developed,and a method for obtaining the geometric parameters of discontinuities was proposed.This method permits the user to visually identify each discontinuity and acquire its spatial distribution features(e.g.occurrences,spac-ings,trace lengths)in great detail.Compared with hand mapping in conventional geotechnical surveys,the geometric information of discontinuities obtained by this approach is more accurate and the iden-tification is more efficient.Then,a discrete fracture network with the same statistical characteristics as the actual discontinuities was generated with the distinct element method,and a representative nu-merical model of the jointed surrounding rock mass was established.By means of numerical simulation,potential unstable rock blocks were assessed,and failure mechanisms were analyzed.This method was applied to detection and assessment of unstable rock blocks in the spillway and sand flushing tunnel of the Hongshiyan hydropower project after a collapse.The results show that the noncontact detection of blocks was more labor-saving with lower safety risks compared with manual surveys,and the stability assessment was more reliable since the numerical model built by this method was more consistent with the distribution characteristics of actual joints.This study can provide a reference for geological survey and unstable rock block hazard mitigation in tunnels subjected to complex geology and active rockfalls. 展开更多
关键词 Rock tunnel Terrestrial laser scanning(TLS) Discontinuity automatic identification Distinct element method Rock block stability assessment
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Application of Scanning Acoustic Microscopy for Detection of Dental Caries Lesion
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作者 Yukihiro Naganuma Kouki Hatori +7 位作者 Masahiro Iikubo Masatoshi Takahashi Yoshihiro Hagiwara Kazuto Kobayashi Atsushi Takahashi Kumi Hoshi Yoshifumi Saijo Keiichi Sasaki 《Open Journal of Stomatology》 2023年第1期12-24,共13页
Introduction: A scanning acoustic microscope (SAM) is an apparatus for imaging acoustic properties. This apparatus can non-invasively and rapidly evaluate the hardness of materials in the elastic region. This device s... Introduction: A scanning acoustic microscope (SAM) is an apparatus for imaging acoustic properties. This apparatus can non-invasively and rapidly evaluate the hardness of materials in the elastic region. This device shows great potential for the diagnosis of dental caries in the clinical setting. However, since the tissue elastic modulus measured using a SAM is a property of the elastic region and the Knoop hardness is a property of the plastic region, the hardness properties differ completely. Therefore, we investigated whether the acoustic impedance measured using a SAM is related to the Knoop hardness, which is used as the standard for removal of carious dentin. Method: Polished sections were prepared from 20 extracted carious wisdom teeth. The acoustic impedance and Knoop hardness were measured for each section. In addition to comparing carious and healthy dentin in SAM images, we evaluated the difference between the carious and healthy dentin in terms of the acoustic impedance and Knoop hardness. We also evaluated the correlation between the Knoop hardness and acoustic impedance. Results: The SAM images were visualized as two-dimensional color images based on the acoustic impedance values. The mean acoustic impedance of carious dentin was significantly lower than that of healthy dentin, showing a similar trend as Knoop hardness. A strong correlation was observed between the two. Discussion: The acoustic impedance values obtained through acoustic microscopy differed significantly between carious and sound dentin. Both types of dentins were visualized using two-dimensional color images. A strong correlation was observed between the acoustic impedance value, which indicates the hardness of the elastic region, and the Knoop hardness, which indicates the hardness of the plastic region. The results of the present study indicate that acoustic impedance accurately reflects the hardness of dentin. 展开更多
关键词 scanning Acoustic Microscope Acoustic Impedance CARIES Knoop Hardness
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Study on the LAI Single Tree Model Based on Terrestrial Laser Scanning
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作者 Zhaohua Pan Genshen Fu 《Open Journal of Geology》 CAS 2023年第5期431-448,共18页
Leaf area index (LAI) is a key parameter for studying global terrestrial ecology and environment and has great ecological significance. How to accurately measure and calculate structural parameters of trees has become... Leaf area index (LAI) is a key parameter for studying global terrestrial ecology and environment and has great ecological significance. How to accurately measure and calculate structural parameters of trees has become an urgent matter. This paper reports the use of terrestrial laser scanning (TLS) as a measurement tool to achieve accurate LAI estimation through point cloud preprocessing measures, the LeWos algorithm, and voxel methods. The accuracy and feasibility of this indirect measurement method were explored. It is found that the single wood structure parameters extracted from TLS have a good linear relationship with manual measurement, and the extraction errors meet the requirements of real-scene conversion. The study also found when the voxel size is consistent with the minimum distance of the point cloud set by TLS instrument, it has a strong correlation with the measured value of canopy analyser. These results lay the foundation for conveniently and quickly obtaining structural parameters of trees, tree growth state detection, and canopy ecological benefit assessment. 展开更多
关键词 Leaf Area Index Terrestrial Laser scanning Branch-Leaf Separation Point Cloud Voxelization
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Thermoacoustic imaging:From single-element scanning to portable and array-based imaging
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作者 Yi-Jie Huang Qi-Kai-Yu Feng Lin Huang 《Journal of Electronic Science and Technology》 EI CAS CSCD 2023年第3期1-20,共20页
The microwave-induced thermoacoustic imaging(TAI)technology has both the advantages of high contrast of microwave imaging and high resolution of ultrasound imaging(UI),so it has carried out exploratory application res... The microwave-induced thermoacoustic imaging(TAI)technology has both the advantages of high contrast of microwave imaging and high resolution of ultrasound imaging(UI),so it has carried out exploratory application research in various areas,such as the early detection of breast tumors and cerebrovascular diseases.However,the microwave generator used in the traditional TAI technology is huge and expensive,and the temporal resolution is also too low due to the single-element scanning mechanism.Thus,it is difficult to meet the needs of clinical applications.In this paper,the iterative process and the analysis of related application scenarios from single-element scanning to portable and array-based TAI,such as the miniaturized microwave generator,handheld antenna,multi-channel data acquisition,and UI/TAIdual-modality imaging,are reviewed,and the future trends of this technology are discussed.This review helps researchers in the field of TAI learn the technological development process and future trends.It also deepens clinicians’understanding of TAI so as to put forward more application requirements. 展开更多
关键词 Array-based PORTABLE Single-element scanning Thermoacoustic imaging(TAI)
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Correlating the Interfacial Polar-Phase Structure to the Local Chemistry in Ferroelectric Polymer Nanocomposites by Combined Scanning Probe Microscopy
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作者 Jiajie Liang Shaojie Wang +4 位作者 Zhen Luo Jing Fu Jun Hu Jinliang He Qi Li 《Nano-Micro Letters》 SCIE EI CAS CSCD 2023年第1期80-93,共14页
Ferroelectric polymer nanocomposites possess exceptional electric properties with respect to the two otherwise uniform phases,which is commonly attributed to the critical role of the matrix-particle interfacial region... Ferroelectric polymer nanocomposites possess exceptional electric properties with respect to the two otherwise uniform phases,which is commonly attributed to the critical role of the matrix-particle interfacial region.However,the structure-property correlation of the interface remains unestablished,and thus,the design of ferroelectric polymer nanocompos-ite has largely relied on the trial-and-error method.Here,a strategy that combines multi-mode scanning probe microscopy-based electrical charac-terization and nano-infrared spectroscopy is developed to unveil the local structure-property correlation of the interface in ferroelectric polymer nano-composites.The results show that the type of surface modifiers decorated on the nanoparticles can significantly influence the local polar-phase content and the piezoelectric effect of the polymer matrix surrounding the nano-particles.The strongly coupled polar-phase content and piezoelectric effect measured directly in the interfacial region as well as the computed bonding energy suggest that the property enhancement originates from the formation of hydrogen bond between the surface modifiers and the ferroelectric polymer.It is also directly detected that the local domain size of the ferroelectric polymer can impact the energy level and distribution of charge traps in the interfacial region and eventually influence the local dielectric strength. 展开更多
关键词 INTERFACES Ferroelectric polymers NANOCOMPOSITES scanning probe microscopy Nano-infrared spectroscopy
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Temperature Field in Laser Line Scanning Thermography: Analytical Calculation and Experiment
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作者 Yin Li Yuanjia Song +2 位作者 Zhengwei Yang Haijun Jiang Bowen Liu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第10期1001-1018,共18页
The temperature field in laser line scanning thermography is investigated comprehensively in this work,including analytical calculation and experiment.Firstly,the principle of laser line scanning thermography is analy... The temperature field in laser line scanning thermography is investigated comprehensively in this work,including analytical calculation and experiment.Firstly,the principle of laser line scanning thermography is analyzed.On this basis,a physical laser line scanning model is proposed.Afterwards,based on Fourier transform(FT)and segregation variablemethod(SVM),the heat conduction differential equation in laser line scanning thermography is derived in detail.The temperature field of the composite-based coatings model with defects is simulated numerically.The results show that the laser line scanning thermography can effectively detect the defects in the model.The correctness of the analytical calculation is verified by comparing the surface temperature distribution obtained by analytical calculation and numerical simulation.Additionally,an experiment is carried out and the changeable surface temperature obtained by analytical calculation is compared with the experimental results.It shows that the error of maximum temperature obtained by analytical calculation and by experiment is 8%with high accuracy,which proves the correctness of analytical calculation and enriches the theoretical foundation of laser line scanning thermography. 展开更多
关键词 Temperature field laser line scanning thermography analytical calculation numerical simulation EXPERIMENT
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Fault Diagnosis and Separation for a Distributed Rotary-laser Scanning System
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作者 Siyang GUO Yin GUO +2 位作者 Shibin YIN Hongbo XIE Jigui ZHU 《Journal of Geodesy and Geoinformation Science》 CSCD 2023年第4期70-78,共9页
The wMPS is a laser-based measurement system used for large scale metrology.However,it is susceptible to external factors such as vibrations,which can lead to unreliable measurements.This paper presents a fault diagno... The wMPS is a laser-based measurement system used for large scale metrology.However,it is susceptible to external factors such as vibrations,which can lead to unreliable measurements.This paper presents a fault diagnosis and separation method which can counter this problem.To begin with,the paper uses simple models to explain the fault diagnosis and separation methods.These methods are then mathematically derived using statistical analysis and the principles of the wMPS.A comprehensive solution for fault diagnosis and separation is proposed,considering the characteristics of the wMPS.The effectiveness of this solution is verified through experimental observations.It can be concluded that this approach can detect and separate false observations,thereby enhancing the reliability of the wMPS. 展开更多
关键词 rotary-laser scanning measurement system least square method fault diagnosis fault separation
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