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Erratum:Bone Regeneration Eff cacy and Applicability of Defect-Fitting 4D Scaffolds Based on Shape Conformity in Three-dimensional Curved Bone Defects 认领 引用
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作者 Min-Soo Ghim Se-Jin Jang +3 位作者 Eun-Yong Choi Meiling Quan Young-Yul Kim Young-Sam Cho 《Journal of Bionic Engineering》 SCIE EI CSCD 2026年第1期550-550,共1页
The original online version of this article was revised:The layout update for Article 758 has impacted the page range in the published issue,but did not affect the scholarly content.To ensure consistency with the orig... The original online version of this article was revised:The layout update for Article 758 has impacted the page range in the published issue,but did not affect the scholarly content.To ensure consistency with the originally assigned pages(2595-2614),we will need to publish an erratum to correct the article and restore the original page range.The original article has been corrected. 展开更多
关键词 defect fitting D scaffolds layout update shape conformity three dimensional curved bone defects bone regeneration
Fitting equations for the sorption isotherms of cement mortar with salt spray deposition 认领 引用
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作者 Bing Li Roberto Giordano +3 位作者 Jean-Marc Tulliani Saierjiang Halike Wanjiang Wang Qinglin Meng 《Frontiers of Architectural Research》 EI CSCD 2026年第3期845-857,共13页
The sorption isotherm of porous building materials serves as a critical hygrothermal property that regulates coupled heat and moisture transfer and influences the energy effi-ciency of building envelopes.Coastal build... The sorption isotherm of porous building materials serves as a critical hygrothermal property that regulates coupled heat and moisture transfer and influences the energy effi-ciency of building envelopes.Coastal buildings endure chronic salt spray exposure,yet clas-sical fitting equations neglect salt deposition effects.This study investigates cement mortar specimens subjected to accelerated salt spray tests(0—35 cycles).The salt content of the specimens was quantified via chloride ion analysis,and isothermal sorption tests were con-ducted under 33%—93%relative humidity(RH)using a static equilibrium method.A modified model integrating a salt influence factor(ηu)into classical equations was developed.Addition-ally,dual-regime sorption isotherm models were formulated based on deliquescence mecha-nisms of salt crystals above critical humidity,governed by the Robinson equation and Nielsen model,respectively.This framework enables accurate prediction of equilibrium mois-ture content under varying coupled humidity-salt conditions,significantly enhancing the reli-ability of hygrothermal simulations for coastal buildings in salt spray climates. 展开更多
关键词 Salt spray climate Cement mortar Sorption isotherm Fitting equations
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Multichannel seismic resolution enhancement via spectral fitting for thin reservoir characterization 认领 引用 被引量：1
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作者 Si-Yuan Wang Hui Chen +1 位作者 Ying Hu Xu-Ping Chen 《Petroleum Science》 SCIE EI CAS CSCD 2025年第7期2818-2827,共10页
As seismic signals propagate underground,the subsurface media absorb high-frequency components,decreasing seismic resolution and limiting the identification and characterization of thin reservoirs.To address the limit... As seismic signals propagate underground,the subsurface media absorb high-frequency components,decreasing seismic resolution and limiting the identification and characterization of thin reservoirs.To address the limitation,this paper proposes a multichannel spectral fitting(MSF)method.The MSF method aims to enhance seismic resolution by considering the spectral characteristics and the correlations between adjacent seismic traces.The key to the MSF method involves utilizing the amplitude spectrum of the attenuated Ricker wavelet to construct an objective function for spectral fitting,leading to improved seismic resolution.Furthermore,the MSF method establishes the correlation between adjacent seismic traces as a constraint to stably solve the target parameters based on the entire seismic spectrum,which helps obtain horizontally consistent and more realistic seismic signals.Synthetic and field seismic examples demonstrate that the proposed method not only provides higher-resolution seismic signals but also reveals more fine details of thin reservoirs compared to the time-variant spectral whitening method.It is concluded that the MSF method is a promising tool for seismic signal processing. 展开更多
关键词 Seismic processing High-resolution Spectral fitting Multichannel processing
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Pressure drop force due to a non-closely fitting sphere settling along the central line in long rectangular tubes 认领 引用
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作者 Yelong Wang Zhaosheng Yu Jianzhong Lin 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2025年第6期165-175,共11页
The ratio of the pressure drop force to the drag force,CP,is concerned for a non-closely fitting spherical particle settling along the central line in long rectangular tubes with different Ar(Aris W/H,where W... The ratio of the pressure drop force to the drag force,CP,is concerned for a non-closely fitting spherical particle settling along the central line in long rectangular tubes with different Ar(Aris W/H,where W,H is length of the longer and shorter side of the rectangle respectively).Under Stokes flow conditions,CP0for an infinitely small sphere in long rectangular tubes and CPfor a sphere in a long channel between two parallel layered barriers are both calculated.Then CPof a sphere settling in long rectangular tubes are conducted with the direct-forcing fictitious domain(DF/FD)method.At large Reynolds number,the sphere settles unstably with a fluctuating velocity and CP.The fluctuation of Cp is much stronger than that of velocity and both fluctuations are stronger for less confined sphere.The influences of the particle Reynolds number(Rep)on CPis similar to the existing experimental results in long circular tubes.At low Rep,CPis a determined value and is calculated.For a given d/H(d sphere diameter),Cp gets its maximum value at one Arin the range of[1,1.5].For a given Ar,CPis a quadratic function of d/H similar to that in a circular tube,and parameters of the quadratic function are got by curve fitting from numerical data.The constant term coefficients got have almost no difference with CP0and are furtherly replaced by the latter to get new quadratic coefficients CP1.Lastly,an algebraic correlation of CP1to Aris developed.The predictions of Cp are good with a maximum relative error about 1.5%for a sphere with d/H not greater than0.7,compared to numerical results. 展开更多
关键词 Pressure drop Numerical simulation Stokes flow Non-closely fitting Sedimentation Particle
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Extended pan-spectrum fitting of energetic particle spectra 认领 引用
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作者 WenYan Li LingHua Wang +2 位作者 YongFu Wang XinNian Guo QianYi Ma 《Earth and Planetary Physics》 EI CSCD 2025年第2期366-374,共9页
The energy spectrum of energetic particles in space often shows a non-thermal spectral shape with two spectral transitions/breaks over a wide energy range, carrying crucial information about their acceleration, releas... The energy spectrum of energetic particles in space often shows a non-thermal spectral shape with two spectral transitions/breaks over a wide energy range, carrying crucial information about their acceleration, release and transportation process. To self-consistently characterize the spectral features of energetic particles, here we propose a novel extended pan-spectrum(EPS) formula to fit the particle energy-flux spectrum, which has the merit that can incorporate many commonly used spectrum functions with one spectral transition, including the pan-spectrum, double-power-law, Kappa, Ellison-Ramaty(ER) functions, etc. The formula can also determine the spectral shape with two spectral transitions, including the triple-power-law function, Kappa distribution(at low energy)plus power law(at high energy), power law(at low energy) plus ER function, etc. Considering the uncertainties in both J and E, we can fit this EPS formula well to the representative energy spectra of various particle phenomena in space, including solar energetic particles(electrons, protons, ~3He and heavier ions), anomalous cosmic rays, solar wind suprathermal particles(halo and superhalo electrons;pick-up ions and the suprathermal tail), etc. Therefore, the EPS fitting can help us self-consistently determine the spectral features of different particle phenomena, and improve our understanding of the physical nature of the origin, acceleration, and transportation of energetic particles in space. 展开更多
关键词 energy spectrum fitting solar energetic particle solar wind suprathermal particle anomalous cosmic ray pick-up ion
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Fault Detection for Split Pins of Power Transmission Fittings in UAV Inspections via Automatic Image Cropping-based Super-Resolution Reconstruction and Enhanced YOLOv8 认领 引用 被引量：1
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作者 Shihao Cui Zhengyu Hu +1 位作者 Fangcheng Qiu Qinglong Wang 《Journal of Electronic Research and Application》 2025年第3期222-234,共13页
In modern industrial applications,ensuring the reliability of mechanical fittings is critical for maintaining operational safety and efficiency,particularly in power grid systems where split pins serve a pivotal role ... In modern industrial applications,ensuring the reliability of mechanical fittings is critical for maintaining operational safety and efficiency,particularly in power grid systems where split pins serve a pivotal role despite being susceptible to environmental degradation and failure.Existing UAV-based inspection systems are hampered by a low representation of split pin elements and complex backgrounds,leading to challenges in accurate fault detection and timely maintenance.To address this pressing issue,our study proposes an innovative fault detection method for split pins.The approach employs a three-step process:first,cropping operations are used to accurately isolate the fittings containing split pins;second,super-resolution reconstruction is applied to enhance image clarity and detail;and finally,an improved YOLOv8 network,augmented with inner-shape IoU and local window attention mechanisms,is utilized to refine local feature extraction and annotation accuracy.Experimental evaluations on a split pin defect dataset demonstrate robust performance,achieving an accuracy rate of 72.1%and a mean average precision(mAP)of 67.7%,thereby validating the method’s effectiveness under challenging conditions.The proposed approach contributes to the field by specifically targeting the challenges associated with split pin detection in UAV-based inspections,offering a practically applicable and reliably precise method. 展开更多
关键词 Split pins Fault detection Power transmission fittings YOLO Deep learning
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Fitting analysis and optimization of MIG welding current for stainless steel 认领 引用
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作者 Quanyong Wang Xiaojuan Wu 《China Welding》 CAS 2025年第4期82-86,共5页
In order to rationally select the welding current of stainless steel during metal inert gas(MIG)welding,its welding current under different plate thicknesses was taken as the object of study.The scatter function provi... In order to rationally select the welding current of stainless steel during metal inert gas(MIG)welding,its welding current under different plate thicknesses was taken as the object of study.The scatter function provided by the data fitting software was used to draw scatter plots for the welding current data from two different sources,the polynomial fit(polyfit)function and the curve fitting toolbox were used to fit polynomial curves and perform optimality analysis on the fitted equations.Scatter plots and first-,second-,and third-order curve fitting equations for welding currents at different plate thicknesses were obtained,as well as curve equations for the optimum order of welding current data from two different sources.The results show that the optimization effect of the third-order curve is superior to that of the first-order and second-order curves.Finally,through the experiment,it is verified that the curve equation has some guiding significance in determining the welding current range of stainless steel MIG welding. 展开更多
关键词 MIG welding Welding current Curve fitting Least squares method Mechanical properties
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Gaussian fitting in gamma-ray spectral decomposition 认领 引用 被引量：8
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作者 FU Chen WANG Nanping 《Nuclear Science and Techniques》 SCIE CAS 2010年第4期214-217,共4页
In order to extract the information of 662-keV 137Cs spectra from the overlapping peaks with 583-keV 208Tl,609-keV 214Bi,the overlapping peaks are measured by in-situγ-ray spectrometer using a NaI(Tl)detector.The spe... In order to extract the information of 662-keV 137Cs spectra from the overlapping peaks with 583-keV 208Tl,609-keV 214Bi,the overlapping peaks are measured by in-situγ-ray spectrometer using a NaI(Tl)detector.The spectral model is optimized by the Gaussian fitting algorithm,and the optimized fitting indexes for fitting/original value are from 0.96 to 0.99.Gaussian fitting verified by experiment is feasible forγ-ray spectrum analysis.The full energy peak of 137Cs is extracted correctly from the overlapping peaks,it is important for in-situγ-ray spectrometer to estimate contamination of 137Cs in radiated environment and nuclear accident. 展开更多
关键词 Gamma-ray spectrum Gaussian fitting Overlapping peaks Decomposition and fitting
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Iterative circle fitting based on circular attracting factor 认领 引用 被引量：1
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作者 王恒升 张强 王福亮 《Journal of Central South University》 SCIE EI CAS 2013年第10期2663-2675,共13页
An intuitive method for circle fitting is proposed. Assuming an approximate circle(CA,n) for the fitting of some scattered points, it can be imagined that every point would apply a force to CA,n, which all together fo... An intuitive method for circle fitting is proposed. Assuming an approximate circle(CA,n) for the fitting of some scattered points, it can be imagined that every point would apply a force to CA,n, which all together form an overall effect that "draws" CA,n towards best fitting to the group of points. The basic element of the force is called circular attracting factor(CAF) which is defined as a real scalar in a radial direction of CA,n. An iterative algorithm based on this idea is proposed, and the convergence and accuracy are analyzed. The algorithm converges uniformly which is proved by the analysis of Lyapunov function, and the accuracy of the algorithm is in accord with that of geometric least squares of circle fitting. The algorithm is adopted to circle detection in grayscale images, in which the transferring to binary images is not required, and thus the algorithm is less sensitive to lightening and background noise. The main point for the adaption is the calculation of CAF which is extended in radial directions of CA,n for the whole image. All pixels would apply forces to CA,n, and the overall effect of forces would be equivalent to a force from the centroid of pixels to CA,n. The forces from would-be edge pixels would overweigh that from noisy pixels, so the following approximate circle would be of better fitting. To reduce the amount of calculation, pixels are only used in an annular area including the boundary of CA,n just in between for the calculation of CAF. Examples are given, showing the process of circle fitting of scattered points around a circle from an initial assuming circle, comparing the fitting results for scattered points from some related literature, applying the method proposed for circular edge detection in grayscale images with noise, and/or with only partial arc of a circle, and for circle detection in BGA inspection. 展开更多
关键词 circle detection circle fitting grayscale image iterative algorithm least squares fitting(LSF) circular attracting factor(CAF) BGA inspection
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Road Alignment Fitting Method Evaluation Based on Multi-factor Method 认领 引用
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作者 ZHANG Chi MA Xiong-ying +1 位作者 WANG Shi-wei GONG Quan-li 《Journal of Highway and Transportation Research and Development(English Edition)》 2017年第3期16-23,共8页
Multi-factor evaluation was established based on the analytic hierarchy process(AHP)to analyze the advantages of different road alignment fitting methods and provide guidance on selecting linear fitting methods for ro... Multi-factor evaluation was established based on the analytic hierarchy process(AHP)to analyze the advantages of different road alignment fitting methods and provide guidance on selecting linear fitting methods for road reconstruction and extension engineering.Through this evaluation system,the reliability,precision,and difficulty degree of the least squares,MATLAB,and cubic spline curve methods were evaluated.Results show that the least squares method exhibits the highest precision;the MATLAB method achieves the strongest stability;and in terms of difficulty degree,the cubic spline curve method is the simplest method.AHP is adopted to calculate the scores of the three methods.The least squares method has the highest score.The score of the MATLAB method is 61.05%that of the least squares method,whereas that of the cubic spline curve method is only 42.72%that of the least squares method.The results quantify the evaluation factors and provide suggestions for selecting an appropriate and effective road fitting method under different conditions.The results also provide a reference for evaluating road alignment fitting methods. 展开更多
关键词 road engineering fitting method evaluation multi-factor evaluation system,road alignment fitting methods AHP
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基于Vector Fitting的光伏并网逆变器控制器参数频域辨识方法 认领 引用 被引量：22
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作者 王哲 吕敬 +3 位作者 吴林林 王潇 宗皓翔 蔡旭 《电力自动化设备》 EI CSCD 北大核心 2022年第5期118-124,共7页
光伏并网逆变器通常含有内外环、锁相环等不同带宽控制环节,且控制器参数往往并不可知,即存在“灰箱”问题。为准确辨识不同带宽控制器参数,提出一种基于端口导纳特性的光伏并网逆变器控制器参数频域辨识方法。首先,建立典型控制下光伏... 光伏并网逆变器通常含有内外环、锁相环等不同带宽控制环节,且控制器参数往往并不可知,即存在“灰箱”问题。为准确辨识不同带宽控制器参数,提出一种基于端口导纳特性的光伏并网逆变器控制器参数频域辨识方法。首先,建立典型控制下光伏并网逆变器交流端口的dq理论导纳模型,得到其理论导纳标准式;然后,通过扫频手段获得光伏并网逆变器交流端口的测量导纳数据,并采用Vector Fitting算法对测量的端口导纳数据进行矢量拟合,得到拟合导纳标准式;最后,运用最小二乘原理使理论导纳标准式与拟合导纳标准式对应项系数差值的平方和最小,从而辨识得到光伏并网逆变器控制器参数的估计值。参数辨识实例表明,所提方法能够同时准确辨识出不同带宽控制器参数。 展开更多
关键词 光伏并网逆变器 参数辨识 导纳特性 Vector Fitting算法 多带宽控制
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Seismic noise attenuation using nonstationary polynomial fitting 认领 引用 被引量：15
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作者 Liu Guo-Chang Chen Xiao-Hong +2 位作者 Li Jing-Ye Du Jing Song Jia-Wen 《Applied Geophysics》 SCIE CSCD 2011年第1期18-26,94,共9页
We propose a novel method for seismic noise attenuation by applying nonstationary polynomial fitting （NPF）, which can estimate coherent components with amplitude variation along the event. The NPF with time-varying ... We propose a novel method for seismic noise attenuation by applying nonstationary polynomial fitting （NPF）, which can estimate coherent components with amplitude variation along the event. The NPF with time-varying coefficients can adaptively estimate the coherent components. The smoothness of the polynomial coefficients is controlled by shaping regularization. The signal is coherent along the offset axis in a common midpoint （CMP） gather after normal moveout （NMO）. We use NPF to estimate the effective signal and thereby to attenuate the random noise. For radial events-like noise such as ground roll, we first employ a radial trace （RT） transform to transform the data to the time-velocity domain. Then the NPF is used to estimate coherent noise in the RT domain. Finally, the coherent noise is adaptively subtracted from the noisy dataset. The proposed method can effectively estimate coherent noise with amplitude variations along the event and there is no need to propose that noise amplitude is constant. Results of synthetic and field data examples show that, compared with conventional methods such as stationary polynomial fitting and low cut filters, the proposed method can effectively suppress seismic noise and preserve the signals. 展开更多
关键词 Polynomial fitting noise attenuation radial trace transform nonstationary regression
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Prediction of DOM removal of low specific UV absorbance surface waters using HPSEC combined with peak fitting 认领 引用 被引量：5
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作者 Linan Xing Rolando Fabris +3 位作者 W.K.Chow John van Leeuwen Mary Drikas Dongsheng Wang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2012年第7期1174-1180,共7页
High performance size exclusion chromatography （HPSEC） is used in water quality research primarily to determine the molecular weight distribution of the dissolved organic matter （DOM）, but by applying peak fitting... High performance size exclusion chromatography （HPSEC） is used in water quality research primarily to determine the molecular weight distribution of the dissolved organic matter （DOM）, but by applying peak fitting to the chromatogram, this technique can also be used as a tool to model and predict DOM removal. Six low specific UV absorbance （SUVA） source waters were treated using coagulation with alum and both the source and treated water samples were analysed using HPSEC. By comparing the molecular weight profiles of the source and treated waters, it was established that several DOM components were not effectively removed by alum coagulation even after high dosage alum treatment. A peak-fitting technique was applied based on the concept of linking the character （molecular weight profile） of the recalcitrant organics in the treated water with those of the source water. This was then applied to predict DOM treatability by determining the areas of the peaks which were assigned to removable organics from the source water molecular weight profile after peak fitting, and this technique quantified the removable and non-removable organics. The prediction was compared with the actual dissolved organic carbon （DOC） removal determined from jar testing and showed good agreement, with variance between 2% and 10%. This confirmed that this prediction approach, which was originally developed for high SUVA waters, can also be applied successfully to predict DOC removal in low SUVA waters. 展开更多
关键词 DOM high performance size exclusion chromatography peak fitting water treatment
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An effective fractal image compression algorithm based on plane fitting 认领 引用 被引量：5
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作者 王兴元 国兴 张丹丹 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第9期149-155,共7页
A new method using plane fitting to decide whether a domain block is similar enough to a given range block is proposed in this paper. First, three coefficients are computed for describing each range and domain block. ... A new method using plane fitting to decide whether a domain block is similar enough to a given range block is proposed in this paper. First, three coefficients are computed for describing each range and domain block. Then, the best-matched one for every range block is obtained by analysing the relation between their coefficients. Experimental results show that the proposed method can shorten encoding time markedly, while the retrieved image quality is still acceptable. In the decoding step, a kind of simple line fitting on block boundaries is used to reduce blocking effects. At the same time, the proposed method can also achieve a high compression ratio. 展开更多
关键词 fractal image compression plane fitting peak signal to noise ratio gray image
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ANNUAL VARIATIONS OF TEMPERATURE ON FOUR URBAN UNDERLYING SURFACES AND FITTING ANALYSIS 认领 引用 被引量：4
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作者 刘霞 王春林 +1 位作者 景元书 麦博儒 《Journal of Tropical Meteorology》 SCIE 2013年第2期138-144,共7页
Based on the observed 2-year temperature data for four kinds of typical urban underlying surfaces,including asphalt, cement, bare land and grass land, the annual variations and influencing factors of landsurface tempe... Based on the observed 2-year temperature data for four kinds of typical urban underlying surfaces,including asphalt, cement, bare land and grass land, the annual variations and influencing factors of landsurface temperature are analyzed. Then fitting equations for surface temperature are established. It is shownthat the annual variation of daily average, maximum and minimum temperature and daily temperature rangeon the four urban underlying surfaces is consistent with the change in air temperature. The difference oftemperature on different underlying surfaces in the summer half year (May to October) is much moreevident than that in the winter half year (December to the following April). The daily average and maximumtemperatures of asphalt, cement, bare land and grass land are higher than air temperature due to theatmospheric heating in the daytime, with that of asphalt being the highest, followed in turn by cement, bareland and grass land. Moreover, the daily average, maximum and minimum temperature on the four urbanunderlying surfaces are strongly impacted by total cloud amount, daily average relative humidity andsunshine hours. The land surface can be cooled (warmed) by increased total cloud amount (relativehumidity). The changes in temperature on bare land and grass land are influenced by both the total cloudamount and the daily average relative humidity. The temperature parameters of the four land surfaces aresignificantly correlated with daily average, maximum and minimum temperature, sunshine hours, dailyaverage relative humidity and total cloud amount, respectively. The analysis also indicates that the range offitting parameter of a linear regression equation between the surface temperature of the four kinds of typicalland surface and the air temperature is from 0.809 to 0.971, passing the F-test with a confidence level of 0.99. 展开更多
关键词 fitting analysis urban underlying surface land surface temperature
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Fish-Eye Image Distortion Correction Based on Adaptive Partition Fitting 认领 引用 被引量：3
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作者 Yibin He Wenhao Xiong +4 位作者 Hanxin Chen Yuchen Chen Qiaosen Dai Panpan Tu Gaorui Hu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2021年第1期379-396,共18页
The acquisition of images with a fish-eye lens can cause serious image distortion because of the short focal length of the lens.As a result,it is difficult to use the obtained image information.To make use of the effe... The acquisition of images with a fish-eye lens can cause serious image distortion because of the short focal length of the lens.As a result,it is difficult to use the obtained image information.To make use of the effective information in the image,these distorted imagesmust first be corrected into the perspective of projection images in accordance with the human eye’s observation abilities.To solve this problem,this study presents an adaptive classification fitting method for fish-eye image correction.The degree of distortion in the image is represented by the difference value of the distances fromthe distorted point and undistorted point to the center of the image.The target points selected in the image are classified by the difference value.In the areas classified by different distortion differences,different parameter curves were used for fitting and correction.The algorithm was verified through experiments.The results showed that this method has a substantial correction effect on fish-eye images taken by different fish-eye lenses. 展开更多
关键词 Fish-eye lens image distortion distortion difference adaptive partition fitting
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Solving single-frequency phase ambiguity using parameter weights fitting and constrained equation ambiguity resolution methods 认领 引用 被引量：6
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作者 阳仁贵 欧吉坤 +3 位作者 袁运斌 张克非 闻德保 Ron Grenfell 《Journal of Central South University of Technology》 2006年第1期93-98,共6页
Based on the structural characteristics of the double-differenced normal equation, a new method was proposed to resolve the ambiguity float solution through a selection of parameter weights to construct an appropriate... Based on the structural characteristics of the double-differenced normal equation, a new method was proposed to resolve the ambiguity float solution through a selection of parameter weights to construct an appropriate regularized matrix, and a singular decomposition method was used to generate regularization parameters. Numerical test results suggest that the regularized ambiguity float solution is more stable and reliable than the least-squares float solution. The mean square error matrix of the new method possesses a lower correlation than the variancecovariance matrix of the least-squares estimation. The size of the ambiguity search space is reduced and the search efficiency is improved. The success rate of the integer ambiguity searching process is improved significantly when the ambiguity resolution by using constraint equation method is used to determine the correct ambiguity integervector. The ambiguity resolution by using constraint equation method requires an initial input of the ambiguity float solution candidates which are obtained from the LAMBDA method in the new method. In addition, the observation time required to fix reliable integer ambiguities can he significantly reduced. 展开更多
关键词 global position system ill-conditioned state parameter weight fitting method constraint equation integer ambiguity
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A Robust Indoor Localization Algorithm Based on Polynomial Fitting and Gaussian Mixed Model 认领 引用 被引量：3
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作者 Long Cheng Peng Zhao +1 位作者 Dacheng Wei Yan Wang 《China Communications》 SCIE CSCD 2023年第2期179-197,共19页
Wireless sensor network(WSN)positioning has a good effect on indoor positioning,so it has received extensive attention in the field of positioning.Non-line-of sight(NLOS)is a primary challenge in indoor complex enviro... Wireless sensor network(WSN)positioning has a good effect on indoor positioning,so it has received extensive attention in the field of positioning.Non-line-of sight(NLOS)is a primary challenge in indoor complex environment.In this paper,a robust localization algorithm based on Gaussian mixture model and fitting polynomial is proposed to solve the problem of NLOS error.Firstly,fitting polynomials are used to predict the measured values.The residuals of predicted and measured values are clustered by Gaussian mixture model(GMM).The LOS probability and NLOS probability are calculated according to the clustering centers.The measured values are filtered by Kalman filter(KF),variable parameter unscented Kalman filter(VPUKF)and variable parameter particle filter(VPPF)in turn.The distance value processed by KF and VPUKF and the distance value processed by KF,VPUKF and VPPF are combined according to probability.Finally,the maximum likelihood method is used to calculate the position coordinate estimation.Through simulation comparison,the proposed algorithm has better positioning accuracy than several comparison algorithms in this paper.And it shows strong robustness in strong NLOS environment. 展开更多
关键词 wireless sensor network indoor localization NLOS environment gaussian mixture model(GMM) fitting polynomial
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Splitting and Merging Based Multi-model Fitting for Point Cloud Segmentation 认领 引用 被引量：8
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作者 Liangpei ZHANG Yun ZHANG +2 位作者 Zhenzhong CHEN Peipei XIAO Bin LUO 《Journal of Geodesy and Geoinformation Science》 2019年第2期78-89,共12页
This paper deals with the massive point cloud segmentation processing technology on the basis of machine vision, which is the second essential factor for the intelligent data processing of three dimensional conformati... This paper deals with the massive point cloud segmentation processing technology on the basis of machine vision, which is the second essential factor for the intelligent data processing of three dimensional conformation in digital photogrammetry. In this paper, multi-model fitting method is used to segment the point cloud according to the spatial distribution and spatial geometric structure of point clouds by fitting the point cloud into different geometric primitives models. Because point cloud usually possesses large amount of 3D points, which are uneven distributed over various complex structures, this paper proposes a point cloud segmentation method based on multi-model fitting. Firstly, the pre-segmentation of point cloud is conducted by using the clustering method based on density distribution. And then the follow fitting and segmentation are carried out by using the multi-model fitting method based on split and merging. For the plane and the arc surface, this paper uses different fitting methods, and finally realizing the indoor dense point cloud segmentation. The experimental results show that this method can achieve the automatic segmentation of the point cloud without setting the number of models in advance. Compared with the existing point cloud segmentation methods, this method has obvious advantages in segmentation effect and time cost, and can achieve higher segmentation accuracy. After processed by method proposed in this paper, the point cloud even with large-scale and complex structures can often be segmented into 3D geometric elements with finer and accurate model parameters, which can give rise to an accurate 3D conformation. 展开更多
关键词 machine vision 3D conformation point cloud segmentation splitting and merging multi-model fitting
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A NURBS Fitting Optimization Method for High⁃Speed Five⁃Axis NC Machining Path Based on Curvature Smoothing Preset Point Constraint 认领 引用 被引量：3
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作者 YANG Gaojie XU Xiang +1 位作者 SHI Zhongquan YE Wenhua 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2021年第3期404-414,共11页
Existing curve fitting algorithms of NC machining path mainly focus on the control of fitting error,but ignore the problem that the original discrete cutter position points are not enough in the high curvature area of... Existing curve fitting algorithms of NC machining path mainly focus on the control of fitting error,but ignore the problem that the original discrete cutter position points are not enough in the high curvature area of the tool path.It may cause a sudden change in the drive force of the feed axis,resulting in a large fluctuation in the feed speed.This paper proposes a new non-uniform rational B-spline(NURBS)curve fitting optimization method based on curvature smoothing preset point constraints.First,the short line segments generated by the CAM software are optimally divided into different segment regions,and then the curvature of the short line segments in each region is adjusted to make it smoother.Secondly,a set of characteristic points reflecting the change of the curvature of the fitted curve is constructed as the control apex of the fitted curve,and the curve is fitted using the NURBS curve fitting optimization method based on the curvature smoothing preset point constraint.Finally,the curve fitting error and curve volatility are analyzed with an example,which verifies that the method can significantly improve the curvature smoothness of the high-curvature tool path,reduce the fitting error,and improve the feed speed. 展开更多
关键词 curvature smoothing NC machining path NURBS curve fitting weighted constraint
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