检索结果-南通市图书馆

Research in Astronomy and Astrophysics 2024年第4期24卷 271-286页

作者： Yong-Xiong Zhang Wen-Xiu Guo xiao-ping lu Hua Zheng Hai-Bin Zhao Jun Tian Wei-Lin Wang School of Engineering Guangzhou College of Technology and BusinessGuangzhou 510850China School of Computer Science and Engineering Macao University of Science and TechnologyTaipaMacao 999078China School of Mathematics and Statistics Shaoguan UniversityShaoguan 512099China State Key Laboratory of lunar and Planetary Sciences Macao University of Science and TechnologyMacao 999078China Key Laboratory of Planetary Sciences Purple Mountain ObservatoryCASNanjing 210023China

Determining asteroid properties provides valuable physical insights but inverting them from photometric lightcurves remains computationally *** paper presents a new approach that combines a simplified Cellinoid shape model with the Parallel Differential Evolution(PDE)algorithm to accelerate *** PDE algorithm is more efficient than the Differential Evolution algorithm,achieving an extraordinary speedup of 37.983 with 64 workers on multicore *** PDE algorithm accurately derives period and pole values from simulated *** analysis of real asteroid lightcurves validates the method’s reliability:in comparison with results published elsewhere,the PDE algorithm accurately recovers the rotational periods and,given adequate viewing geometries,closely matches the pole *** PDE approach converges to solutions within 20,000 iterations and under one hour,demonstrating its potential for large-scale data *** work provides a promising new tool for unveiling asteroid physical properties by overcoming key computational bottlenecks.

关键词： methods:numerical minor planets asteroids:general techniques:photometric astrom

BGLS-based method of estimating the rotational periods of asteroids

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2021年第7期21卷 107-114页

作者： Yan-Qiong Ren xiao-ping lu Yong Liang School of Computer Science and Communication Engineering Jiangsu UniversityZhenjiang 212013China Macao University of Science and Technology Macao 999078China Guangdong-Hong Kong-Macao Joint Laboratory for Smart Discrete Manufacturing Guangzhou 510006China

As the asteroid rotational period is important to the study of the properties of asteroids(e.g.,super-fast rotators have structures owing an internal cohesion(rather than being rubble piles bounded by gravity only) so as not to fly apart), constructing an effective and fast method used to search the period attracts much researchers' attention. Recently, the Bayesian generalized Lomb–Scargle(BGLS)periodogram was developed to improve the convergence efficiency of the Lomb–Scargle method. However,the result of BGLS varies with the frequency range and cannot meet the two minimum/maximum requirements for a complete rotation of the asteroid. We propose a robust BGLS-based method that efficiently determines rotational periods. The proposed method employs a polynomial series to fit folded light curves with potential periods, initially calculated using the BGLS periodogram, and adopts a merit function to estimate and refine best-fit periods. We estimate the rotational periods of 30 asteroids applying the new method to light curves from the Palomar Transient Factory. Results confirm the effectiveness of the BGLS-based method in deriving rotational periods from ground-based observations of asteroids. Further application of the BGLS-based method to sparse light curves, such as Gaia data, is discussed.

关键词： methods:data analysis asteroids:general techniques:photometric

A fast ellipsoid model for asteroids inverted from lightcurves

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2013年第4期13卷 471-478页

作者： xiao-ping lu Hai-Bin Zhao Zhong You Faculty of Information Technology Macao University of Science and Technology Purple Mountain Observatory Chinese Academy of Sciences

Research about asteroids has recently attracted more and more attention, especially focusing on their physical structures, such as their spin axis, rotation period and shape. The long distance between observers on Earth and asteroids makes it impossible to directly calculate the shape and other parameters of asteroids, with the exception of Near Earth Asteroids and others that have passed by some spacecrafts. Photometric measurements are still generally the main way to obtain research data on asteroids, i.e. the lightcurves recording the brightness and positions of asteroids. Supposing that the shape of the asteroid is a triaxial ellipsoid with a stable spin, a new method is presented in this article to reconstruct the shape models of asteroids from the lightcurves, together with other physical parameters. By applying a special curvature function, the method calculates the brightness integration on a unit sphere and Lebedev quadrature is employed for the discretization. Finally, the method searches for the optimal solution by the Levenberg-Marquardt algorithm to minimize the residual of the brightness. By adopting this method, not only can related physical parameters of asteroids be obtained at a reasonable accuracy, but also a simple shape model of an ellipsoid can be generated for reconstructing a more sophisticated shape model.

关键词： ellipsoid model - lightcurves - photometric - shape: asteroids

Scattering Law Analysis Based on Hapke and Lommel-Seeliger Models for Asteroidal Taxonomy

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2017年第10期17卷 83-90页

作者： Xiang-Jie Huang xiao-ping lu Jian-Yang Li Bao Mei Chih-Hao Hsia Hai-Bin Zhao Macao University of Science and Technology lunar and Planetary Science Laboratory Macao University of Science and Technology - Partner Laboratory of Key Laboratory of Lunar and Deep Space Exploration Chinese Academy of Sciences Key Laboratory of Planetary Sciences Chinese Academy of Sciences Planetary Science Institute Purple Mountain Observatory Chinese Academy of Sciences

In deriving the physical properties of asteroids from their photometric data, the scattering law plays an important role, although the shape variations of asteroids result in the main variations in lightcurves. By following the physical behaviors of light reflections, Hapke et al. deduced complex functions to represent the scattering process, however, it is very hard to accurately simulate the surface scattering law in reality. For simplicity, other numerical scattering models are presented for efficiently calculating the physical properties of asteroids, such as the Lommel-Seeliger （LS） model. In this article, these two models are compared numerically. It is found that in some numerical applications the LS model in simple form with four parameters can be exploited to replace the Hapke model in complex form with five parameters. Furthermore, the generated synthetic lightcurves by the Cellinoid shape model also show that the LS model can perform as well as the Hapke model in the inversion process. Finally, by applying the Principal Component Analysis （PCA） technique to the parameters of the LS model, we present an efficient method to classify C and S type asteroids, instead of the conventional method using the parameters of the Hapke model.

关键词： scattering -- techniques: photometric -- minor planets -- asteroids: general

Feature Matching via Topology-Aware Graph Interaction Model

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第1期11卷 113-130页

作者： Yifan lu Jiayi Ma xiaoguang Mei Jun Huang xiao-ping Zhang the Electronic Information School Wuhan UniversityWuhan 430072China IEEE Tsinghua Berkeley Shenzhen Institute Shenzhen 518071China the Department of Electrical Computer and Biomedical EngineeringToronto Metropolitan UniversityToronto ON M5B 2K3Canada

Feature matching plays a key role in computer vision. However, due to the limitations of the descriptors, the putative matches are inevitably contaminated by massive *** paper attempts to tackle the outlier filtering problem from two aspects. First, a robust and efficient graph interaction model,is proposed, with the assumption that matches are correlated with each other rather than independently distributed. To this end, we construct a graph based on the local relationships of matches and formulate the outlier filtering task as a binary labeling energy minimization problem, where the pairwise term encodes the interaction between matches. We further show that this formulation can be solved globally by graph cut algorithm. Our new formulation always improves the performance of previous localitybased method without noticeable deterioration in processing time,adding a few milliseconds. Second, to construct a better graph structure, a robust and geometrically meaningful topology-aware relationship is developed to capture the topology relationship between matches. The two components in sum lead to topology interaction matching(TIM), an effective and efficient method for outlier filtering. Extensive experiments on several large and diverse datasets for multiple vision tasks including general feature matching, as well as relative pose estimation, homography and fundamental matrix estimation, loop-closure detection, and multi-modal image matching, demonstrate that our TIM is more competitive than current state-of-the-art methods, in terms of generality, efficiency, and effectiveness. The source code is publicly available at http://***/Yifanlu2000/TIM.

关键词： Feature matching graph cut outlier filtering topology preserving

Prediction of hepatic inflammation in chronic hepatitis B patients with a random forest-backward feature elimination algorithm

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2021年第21期27卷 2910-2920页

作者： Ji-Yuan Zhou Liu-Wei Song Rong Yuan xiao-ping lu Gui-Qiang Wang Department of Gastroenterology The Second Affiliated Hospital of Guangzhou Medical UniversityGuangzhou 510260Guangdong ProvinceChina School of Public Health Xiamen UniversityXiamen 361005Fujian ProvinceChina Intervention and Cell Therapy Center Peking University Shenzhen HospitalShenzhen 518036Guangdong ProvinceChina Department of Infectious Disease Peking University First HospitalBeijing 100034China

BACKGROUND Persistent liver inflammatory damage is the main risk factor for developing liver fibrosis,cirrhosis,and even hepatocellular carcinoma in chronic hepatitis B(CHB)***,accurate prediction of the degree of liver inflammation is a high priority and a growing medical *** To build an effective and robust non-invasive model for predicting hepatitis Brelated hepatic *** A total of 650 treatment-naïve CHB(402 HBeAg-positive and 248 HBeAgnegative)patients who underwent liver biopsy were enrolled in this *** inflammation grading was assessed by the Ishak scoring *** quantitative hepatitis B core antibody(qAnti-HBc)levels and 21 immunerelated inflammatory factors were measured quantitatively using a chemiluminescent microparticle immunoassay.A backward feature elimination(BFE)algorithm utilizing random forest(RF)was used to select optional features and construct a combined *** diagnostic abilities of the model or variables were evaluated based on the estimated area under the receiver operating characteristics curve(AUROC)and compared using the DeLong *** Four features were selected to predict moderate-to-severe inflammation in CHB patients using the RF-BFE *** predictive features included qAnti-HBc,ALT,AST,and ***’s correlation analysis indicated that serum qAnti-HBc,ALT,AST,and CXCL11 levels were positively correlated with the histology activity index(HAI)*** selected features were incorporated into the model to establish a novel model named I-3A *** AUROC[0.822;95%confidence interval(CI):0.790-0.851]of the I-3A index was significantly increased compared with qAnti-HBc alone(0.760,95%CI:0.724-0.792,Plue of 0.41 produced a sensitivity of 69.17%,specificity of 81.44%,and accuracy of 73.8%.Additionally,the I-3A index showed significantly improved diagnostic performance for predicting moderate-to-severe i

关键词： Hepatic inflammation Machine learning Quantitative hepatitis B core antibody CXCL11 Diagnostic efficiency

Study of the Modified Gaussian Model on olivine diagnostic spectral features and its applications in space weathering experiments

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2020年第8期20卷 261-279页

作者： Hui-Jie Han xiao-ping lu Ya-Zhou Yang Hao Zhang Admire Muchimamui Mutelo State Key Laboratory of lunar and Planetary Sciences Macao University of Science and TechnologyTaipa 999078MacaoChina State Key Laboratory of Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Planetary Science Institute School of Earth SciencesChina University of GeosciencesWuhan 430074China CAS Center for Excellence in Comparative Planetology Hefei 230026China School of Earth Science and Resources China University of GeosciencesBeijing 100083China

The absorption features of olivine in visible and near-infrared(VNIR)reflectance spectra are the key spectral parameters in its mineralogical ***,these spectral parameters can be obtained by exploiting the Modified Gaussian Model(MGM)with a proper continuum ***,different continua may change the deconvolution results of these *** paper investigates the diagnostic spectral features of olivine with diverse chemical *** different continuum removal methods with MGM for getting the deconvolution results are presented and the regression equations for predicting the Mg-number(Fo#)are *** results show that different continua superimposed on the mineral absorption features will make the absorption center shift,as well as the obvious alterations in shape,width and strength of the absorption ***,it is also found that the logarithm of a second-order polynomial continuum can match the overall shape of the spectrum in logarithmic space,and the improved regression equations applied to estimate the chemical composition of olivine-dominated spectra also have a better *** an application example,the improved approach is applied to pulse laser irradiated olivine grains to simulate and study the space weathering effects on olivine diagnostic spectral *** experiments confirm that space weathering can make the absorption band center shift toward longer ***,the Fo#estimated from remote sensing spectra may be less than its actual chemical *** results may provide valuable information for revealing the difference between the spectra of olivine grains and olivine-dominated asteroids.

关键词： techniques:spectroscopic instrumentation:spectrographs methods:statistical minor planets asteroids:general

On the Monge–Kantorovich Mass Transfer Problem in Higher Dimensions

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2024年第8期40卷 1989-2004页

作者： xiao Jun lu School of Mathematics Southeast UniversityNanjing 210096P.R.China

This paper mainly investigates the approximation of a global maximizer of the Monge–Kantorovich mass transfer problem in higher dimensions through the approach of nonlinear partial differential equations with Dirichlet *** an approximation mechanism,the primal maximization problem can be transformed into a sequence of minimization *** applying the systematic canonical duality theory,one is able to derive a sequence of analytic solutions for the minimization *** the final analysis,the convergence of the sequence to an analytical global maximizer of the primal Monge–Kantorovich problem will be demonstrated.

关键词： Monge-Kantorovich mass transfer singular variational problem canonical duality theory

Decentralized Optimal Control and Stabilization of Interconnected Systems With Asymmetric Information

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 698-707页

作者： Na Wang xiao Liang Hongdan Li xiao lu the College of Electrical Engineering and Automation Shandong University of Science and TechnologyQingdao 266000China the School of Automation and Electrical Engineering Linyi UniversityLinyi 276000China the College of Energy Storage Technology Shandong University of Science and TechnologyQingdao 266000China

The paper addresses the decentralized optimal control and stabilization problems for interconnected systems subject to asymmetric *** with previous work,a closed-loop optimal solution to the control problem and sufficient and necessary conditions for the stabilization problem of the interconnected systems are given for the first *** main challenge lies in three aspects:Firstly,the asymmetric information results in coupling between control and estimation and failure of the separation ***,two extra unknown variables are generated by asymmetric information(different information filtration)when solving forward-backward stochastic difference ***,the existence of additive noise makes the study of mean-square boundedness an *** adopted technique is proving and assuming the linear form of controllers and establishing the equivalence between the two systems with and without additive noise.A dual-motor parallel drive system is presented to demonstrate the validity of the proposed algorithm.

关键词： Asymmetric information decentralized control forwardbackward stochastic difference equations interconnected system stalibization

On Minor Left Prime Factorization Problem for Multivariate Polynomial Matrices

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2024年第3期37卷 1295-1307页

作者： lu Dong WANG Dingkang xiao Fanghui School of Mathematics Southwest Jiaotong UniversityChengdu 610031China KLMM Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China MOE-LCSM School of Mathematics and StatisticsHunan Normal UniversityChangsha 410081China

A new necessary and sufficient condition for the existence of minor left prime factorizations of multivariate polynomial matrices without full row rank is *** key idea is to establish a relationship between a matrix and any of its full row rank *** on the new result,the authors propose an algorithm for factorizing matrices and have implemented it on the computer algebra system *** examples are given to illustrate the effectiveness of the algorithm,and experimental data shows that the algorithm is efficient.

关键词： Free modules Grobner bases minor left prime(MLP) multivariate polynomial matrices polynomial matrix factorizations