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基于边缘的SSIM图像质量客观评价方法

光子学报 2013年第1期42卷 110-114页

作者：田浩南李素梅天津大学电子信息工程学院天津300072

在图像处理领域中,准确判断所处理图像的质量是一项关键技术.本文在基于结构相似度的图像质量评价方法的基础上,考虑了边缘信息对人眼感知结构的重要性,提出了基于边缘结构相似度的图像质量评价方法.实验中,对实验图像进行客观指标的提... 详细信息

在图像处理领域中,准确判断所处理图像的质量是一项关键技术.本文在基于结构相似度的图像质量评价方法的基础上,考虑了边缘信息对人眼感知结构的重要性,提出了基于边缘结构相似度的图像质量评价方法.实验中,对实验图像进行客观指标的提取与计算,最后统计分析实验数据.结果表明,该方法对图像质量的评价结果优于基于结构相似度的图像质量评价方法,能够正确反映图像质量且更加符合人眼的主观感受.

关键词：图像处理质量评价边缘结构相似度

Multi-carrier Tb/s silicon photonic coherent receiver

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Science China(Information Sciences) 2024年第1期67卷 284-291页

作者： Zhen WANG Xingfeng li Jingchi li Jian SHEN Yong ZHANG Yikai su State Key Lab of Advanced Optical Communication Systems and Networks Department of Electronic EngineeringShanghai Jiao Tong University

We propose a silicon polarization-diversity coherent receiver for wavelength-multiplexing transmission without using the large-footprint arrayed waveguide grating(AWG).We have integrated our proposed coherent receiver on the silicon-on-insulator(SOI) platform for high-capacity *** the proposed coherent receiver,high-frequency photocurrent signals from other wavelengths are suppressed by electrical low-pass ***,the signal-signal beat interference(SSBI) generated from each wavelength is eliminated by the balanced *** two features lend to the proposed coherent receiver being free of the mm-scale *** have demonstrated our proposed coherent receiver to detect a 1.12-Tb/s wavelength-division-multiplexed and polarization-division-multiplexed 16-ary quadrature amplitude modulation(PDM-16-QAM) *** compact footprint of the silicon chip promises small-form-factor receivers for future ultra-high-capacity coherent communication systems that require a high integration level and low fabrication cost.

关键词： silicon photonics optical receivers coherent communication wavelength-division-multiplexing(WDM) polarization-division-multiplexing(PDM)

Preparation and performance improvement of a dual-component microcapsule self-healing system for silicone rubber insulating material

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High Voltage 2024年第2期9卷 453-465页

作者： Mingzhe li Bin Cao Fanghui Yin Hongwei mei liming Wang Engineering Laboratory of Power Equipment Reliability in Complicated Coastal Environments Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhenChina

A key factor limiting the development of silicone rubber insulating materials is their short service life in harsh operating *** establishment of a self-healing system is desired to improve the long-term operational performance of silicone rubber and effectively extend its service *** this study,poly(urea-formaldehyde)microcapsules containing polydimethylsiloxane healing agents are prepared and a dual-component microcapsule self-healing system for silicone rubber material is established and *** addition,the key factors affecting the self-healing performance(such as microcapsule size,rupture rate,and microcapsule doping amount)are *** is found that when SYLGARDTM 184 is used as the healing agent and matrix,with a 4:6(A:B)doping ratio of dual-component microcapsules and 20 phr doping amount,the self-healing efficiency is approximately 51%.Furthermore,increasing the microcapsule rupture rate and the interface strength between the healing agent and the matrix can effectively improve the self-healing *** relationships between key factors and self-healing performance are theoretically *** on the relationships,the microcapsule self-healing system can be appropriately *** results of this paper can provide a reference for the development of long-life silicone rubber insulating materials.

关键词： service rubber performance

Study on detecting main ingredients of silicone rubber based on terahertz spectrum

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High Voltage 2024年第3期9卷 518-527页

作者： Hongwei mei Lanxin li Fanghui Yin liming Wang Masoud Farzaneh Shenzhen International Graduate School(SIGS) Tsinghua UniversityShenzhenGuangdongChina Kunming Power Exchange Center KunmingYunnanChina Department of Applied Sciences(DSA) University of Quebec at ChicoutimiChicoutimiQuebecCanada

The authors investigated the ingredient detection technique of silicone rubber based on the Terahertz *** this purpose,18 diverse high-temperature vulcanised silicone rubber(HTVSR)formulations were customised,8 of which are used as calibration set while the rest 10 as prediction *** on the Beer-Lambert Law,the partial-least-square(PLS)regression model and the least-squares support-vector machines(LS-SVM)regression model were used to yield the relationships between the absorption spectrums and the content percentages of polydimethylsiloxane(PDMS),alumina tri-hydrate(ATH),and silica in *** results showed that for the formulations tested,the prediction accuracy of all three main ingredients by the PLS regression model could be improved by changing the spectrum range from 0.2–4 to 0.5–2 *** the data were pre-processed by the Savitzky–Golay smoothing method or multiplicative scatter correction method,the prediction accuracy of PDMS could be further ***,this would lead to a slight decrease in the prediction accuracy of *** the LS-SVM regression model,the radial basis function(RBF)kernel and the linear kernel were *** was found that the prediction accuracy of both kernels was better than that of the PLS regression *** the LS-SVM regression model using the RBF kernel,the correlated coefficients of PDMS and ATH in the prediction set could be up to 0.9915 and 0.9742,respectively.

关键词： rubber spectrum kernel

Reconstructing historical forest fire risk in the non-satellite era using the improved forest fire danger index and long short-term memory deep learning-a case study in Sichuan Province,southwestern China

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Forest Ecosystems 2024年第1期11卷 87-99页

作者： Yuwen Peng Huiyi su Min sun Mingshi li Co-Innovation Center for sustainable Forestry in Southern China Nanjing Forestry UniversityNanjing 210037China College of Forestry Nanjing Forestry UniversityNanjing 210037China

Historical forest fire risk databases are vital for evaluating the effectiveness of past forest management approaches,enhancing forest fire warnings and emergency response capabilities,and accurately budgeting potential carbon emissions resulting from ***,due to the unavailability of spatial information technology,such databases are extremely difficult to build reliably and completely in the non-satellite *** study presented an improved forest fire risk reconstruction framework that integrates a deep learning-based time series prediction model and spatial interpolation to address the challenge in Sichuan Province,southwestern ***,the forest fire danger index(FFDI)was improved by supplementing slope and aspect *** compared the performances of three time series models,namely,the autoregressive integrated moving average(ARIMA),Prophet and long short-term memory(LSTM)in predicting the modified forest fire danger index(MFFDI).The bestperforming model was used to retrace the MFFDI of individual stations from 1941 to *** this,the Anusplin spatial interpolation method was used to map the distributions of the MFFDI at five-year intervals,which were then subjected to weighted overlay with the distance-to-river layer to generate forest fire risk maps for reconstructing the forest fire danger *** results revealed LSTM as the most accurate in fitting and predicting the historical MFFDI,with a fitting determination coefficient(R^2)of 0.709,mean square error(MSE)of0.047,and validation R^2 and MSE of 0.508 and 0.11,*** validation of the predicted forest fire risk maps indicated that 5 out of 7 historical forest fire events were located in forest fire-prone areas,which is higher than the results determined from the original FFDI(2 out of 7).This proves the effectiveness of the improved MFFDI and indicates a high level of reliability of the historical forest fire risk reconstruction method proposed in this stu

关键词： Forest fire risk reconstruction MFFDI Time series models LSTM ARIMA Prophet Anusplin

Engineering particles towards 3D supraballs-based passive cooling via grafting CDs onto colloidal photonic crystals

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Chinese Chemical Letters 2024年第4期35卷 457-463页

作者： Jie Wu Xiaoqing Yu Guoxing li su Chen State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 210009China

Particle engineering has opened the floodgates to material science in both fundamental and application field. However, covalent interactions have not yet been adequately designed in the particle engineering for functional colloidal photonic crystals(CPCs). Herein, we achieved covalent coupling between carboxylrich poly(styrene-acrylic acid)(P(St-AA)) monodispersed colloidal particles and amine-rich carbon dots(CDs) based on an feasible and universal particle engineering strategy. The designed CDs-grafted P(St-AA)monodispersed colloidal particles initiate a hydrogen bond-driven assembly mode and ensure the construction of large-scale crack-free CPCs. Moreover, the CDs equipped with selective broad-band absorption capacity could improve the saturation of structural colors for high-visibility CPCs. Furthermore, an injectable photonic hydrogel(IPH) is developed to design CPC supraball hydrogel via integrating the CDsgrafted P(St-AA) CPC supraballs with supramolecular hydrogel. Combining superior flexibility, sufficient self-healing capacity of supramolecular hydrogel with visual optical information of our CPC supraballs, a cyclically reversible coding and decoding system was developed. Meanwhile, we firstly demonstrated the novel strategy of 3D supraballs-based passive cooling. The designed 3D CPC supraball hydrogel presents nearly full observation angle reflections behavior and excellent water evaporation capacity and achieves3.6 ℃ temperature drops, showing the application advantages in 3D thermal management. This work not only provides a new insight for manipulating optical properties of CPCs, but also demonstrates an easyto-perform platform, as well as indicates the direction for the promising application of CPCs.

关键词： Particle engineering Carbon dots Colloidal photonic crystals Passive cooling Digital coding

Mobility and dynamic erosion process of granular flow:insights from numerical investigation using material point method

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Journal of Mountain Science 2024年第8期21卷 2713-2738页

作者： YU Fangwei su lijun li Xinpo ZHAO Yu Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610299China University of Chinese Academy of Sciences Beijing 100049China China-Pakistan Joint Research Center on Earth Sciences Islamabad 45320Pakistan Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of SciencesBeijing 100101China College of Civil Engineering and Architecture Zhejiang UniversityHangzhou 310058China MOE Key Laboratory of Soft Soil and Geoenvironmental Engineering Zhejiang UniversityHangzhou 310058China

In order to understand the dynamics of granular flow on an erodible base soil,in this paper,a series of material point method-based granular column collapse tests were conducted to investigate numerically the mobility and dynamic erosion process of granular flow subjected to the complex settings,i.e.,the aspect ratio,granular mass,friction and dilatancy resistance,gravity and presence of water.A set of power scaling laws were proposed to describe the final deposit characteristics of granular flow by the relations of the normalized run-out distance and the normalized final height of granular flow against the aspect ratio,being greatly affected by the complex geological settings,e.g.,granular mass,the friction and dilatancy resistance of granular soil,and presence of water in granular *** index of the coefficient of friction of granular soil was defined as a ratio of the target coefficient of friction over the initial coefficient of friction to quantify the scaling extent of friction change(i.e.,friction strengthening or weakening).There is a characteristic aspect ratio of granular column corresponding to the maximum mobility of granular flow with the minimum index of the apparent coefficient of *** index of the repose coefficient of friction of granular flow decreased gradually with the increase in aspect ratio because higher potential energy of granular column at a larger aspect ratio causes a larger kinetic energy of granular soil to weaken the friction of granular soil as a kind of velocity-related friction *** increase in granular mass reduces gradually the indexes of the apparent and repose coefficients of friction of granular soil to enhance the mobility of granular *** mobility of granular flow increases gradually with the decrease in friction angle or increase in dilatancy angle of granular ***,the increase of gravity accelerates granular flow but showing the same final deposit profile without any dependence on ***

关键词： Column collapse Granular flow Granular soil Material point method Mobility Numerical tests

Promoted hydrogenation of CO2 to methanol over single-atom Cu sites with Na+-decorated microenvironment

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National Science Review 2024年第6期11卷 264-272页

作者： li-li ling Xinyu Guan Xiaoshuo liu Xiao-mei Lei Zhongyuan lin Hai-Long Jiang Hefei National Research Center for Physical Sciences at the Microscale Department of Chemistry University of Science and Technology of China School of Energy and Power Engineering North China Electric Power University School of Energy and Environment Southeast University

Although single-atom Cu sites exhibit high efficiency in CO2hydrogenation to methanol,they are prone to forming Cu nanoparticles due to reduction and aggregation under reaction conditions,especially at high ***,single-atom Cu sites stabilized by adjacent Na+ions have been successfully constructed within a metal-organic framework（MOF）-based catalyst,namely *** is found that the electrostatic interaction between the Na+and Hδ-species plays a pivotal role in upholding the atomic dispersion of Cu in MOF-808-NaCu during CO2hydrogenation,even at temperatures of up to 275℃.This exceptional stabilization effect endows the catalyst with excellent activity(306 g·kgcat-1·h-1),high selectivity to methanol（93%） and long-term stability at elevated reaction temperatures,far surpassing the counterpart in the absence of Na+（denoted as MOF-808-Cu）.This work develops an effective strategy for the fabrication of stable single-atom sites for advanced catalysis by creating an alkali-decorated microenvironment in close proximity.

关键词： single-atom sites metal–organic framework CO2 hydrogenation heterogeneous catalysis alkali-metal decoration

Strain Gradient Finite Element Formulation of Flexoelectricity in Ferroelectric Material Based on Phase-Field Method

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Acta Mechanica Solida Sinica 2024年第4期37卷 570-579页

作者： Shuai Wang Hengchang su Min Yi li-Hua Shao National Key Laboratory of Strength and Structural Integrity Institute of Solid MechanicsSchool of Aeronautic Science and EngineeringBeihang UniversityBeijing100191People’s Republic of China State Key Laboratory of Mechanics and Control for Aerospace Structures and Institute for Frontier Science and Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education and College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing210016People’s Republic of China

Flexoelectricity is a two-way coupling effect between the strain gradient and electric field that exists in all dielectrics,regardless of point group ***,the high-order derivatives of displacements involved in the strain gradient pose challenges in solving electromechanical coupling problems incorporating the flexoelectric *** this study,we formulate a phase-field model for ferroelectric materials considering the flexoelectric effect.A four-node quadrilateral element with 20 degrees of freedom is constructed without introducing high-order shape *** microstructure evolution of domains is described by an independent order parameter,namely the spontaneous polarization governed by the time-dependent Ginzburg–Landau *** model is developed based on a thermodynamic framework,in which a set of microforces is introduced to construct the constitutive relation and evolution *** the flexoelectric part of electric enthalpy,the strain gradient is determined by interpolating the mechanical strain at the node via the values of Gaussian integration points in the isoparametric *** model is shown to be capable of reproducing the classic analytical solution of dielectric materials incorporating the flexoelectric *** model is verified by duplicating some typical phenomena in flexoelectricity in cylindrical tubes and truncated pyramids.A comparison is made between the polarization distribution in dielectrics and *** model can reproduce the solution to the boundary value problem of the cylindrical flexoelectric tube,and demonstrate domain twisting at domain walls in ferroelectrics considering the flexoelectric effect.

关键词： Flexoelectricity Phase-field method Ferroelectrics Domain configuration