检索结果-南通市图书馆

Plasma Science and Technology 2024年第7期26卷 93-107页

作者：雷清雲杨雄程谋森张帆郭大伟李小康肖文杰 National University of Defense Technology Changsha 410073People’s Republic of China Bejing Institute of Tracking and Telecommunications Technology Beijing 100094People’s Republic of China

Laser-induced fluorescence(LIF)spectroscopy is employed for plasma diagnosis,necessitating the utilization of deconvolution algorithms to isolate the Doppler effect from the raw spectral ***,direct deconvolution becomes invalid in the presence of noise as it leads to infinite amplification of high-frequency noise *** address this issue,we propose a deconvolution algorithm based on the maximum entropy *** validate the effectiveness of the proposed algorithm by utilizing simulated LIF spectra at various noise levels(signal-to-noise ratio,SNR=20–80 d B)and measured LIF spectra with Xe as the working *** the typical measured spectrum(SNR=26.23 d B)experiment,compared with the Gaussian filter and the Richardson–Lucy(R-L)algorithm,the proposed algorithm demonstrates an increase in SNR of 1.39 d B and 4.66 d B,respectively,along with a reduction in the root-meansquare error(RMSE)of 35%and 64%,***,there is a decrease in the spectral angle(SA)of 0.05 and 0.11,*** the high-quality spectrum(SNR=43.96 d B)experiment,the results show that the running time of the proposed algorithm is reduced by about98%compared with the R-L iterative ***,the maximum entropy algorithm avoids parameter optimization settings and is more suitable for automatic *** conclusion,the proposed algorithm can accurately resolve Doppler spectrum details while effectively suppressing noise,thus highlighting its advantage in LIF spectral deconvolution applications.

关键词： maximum entropy spectral deconvolution laser-induced fluorescence spectrum

maximum entropy Distribution Function and Uncertainty Evaluation Criteria

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2021年第2期35卷 238-249页

作者： CHEN Bai-yu KOU Yi ZHAO Daniel WU Fang WANG Li-ping LIU Gui-lin College of Engineering University of California BerkeleyBerkeley 94720USA Dornsife College University of Southern CaliforniaLos Angeles 90007USA Department of Mathematics Harvard UniversityCambridge 02138USA Statistics and applied probability University of California Santa BabaraSanta Babara 93106USA School of Mathematical Sciences Ocean University of ChinaQingdao 266100China College of Engineering Ocean University of ChinaQingdao 266100China

Marine environmental design parameter extrapolation has important applications in marine engineering and coastal disaster *** distribution models used for environmental design parameter usually pass the hypothesis tests in statistical analysis,but the calculation results of different distribution models often vary *** this paper,based on the information entropy,the overall uncertainty test criteria were studied for commonly used distributions including Gumbel,Weibull,and Pearson-III *** improved method for parameter estimation of the maximum entropy distribution model is proposed on the basis of moment *** study in this paper shows that the number of sample data and the degree of dispersion are proportional to the information entropy,and the overall uncertainty of the maximum entropy distribution model is minimal compared with other models.

关键词： maximum entropy distribution model uncertainty information entropy evaluation criterion

maximum entropy Estimation of n-Year Extreme Waveheights

在线全文

学校读者我要写书评

暂无评论

海洋工程：英文版 2004年第2期18卷 307-314页

作者：徐德伦张军郑桂珍 Physical Oceanography Laboratory

A new method for estimating the n (50 or 100) -year return-period waveheight, namely, the extreme waveheight expected to occur in n years, is presented on the basis of the maximum entropy principle. The main points of the method are as follows: (1) based on the Hamiltonian principle, a maximum entropy probability density function for the extreme waveheight H, f(H)=αHγ e -βH4 is derived from a Lagrangian function subject to some necessary and rational constraints; (2) the parameters α, β, and γ in the function are expressed in terms of the mean , variance V= (H-)2 and bias B= (H-)3 ; and (3) with , V and B estimated from observed data, the n -year return-period wave height H n is computed in accordance with the formula 11-F(H n)=n , where F(H n) is defined as F(H n)=∫ H n 0f(H) d H. Examples of estimating the 50 and 100-year return period waveheights by the present method and by some currently used method from observed data acquired from two hydrographic stations are given. A comparison of the estimated results shows that the present method is superior to the others.

关键词： maximum entropy n-year return-period waveheights Lagrangian function

A New maximum entropy Probability Function for the Surface Elevation of Nonlinear Sea Waves

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2005年第4期19卷 637-646页

作者：张立振徐德伦 Department of Applied Mathematics Ocean University of China Qingdao266071China Physical Oceanography Laboratory Ocean University of China Qingdao266003China

Based on the maximum entropy principle a new probability density function （PDF） f（x） for the surface elevation of nonlinear sea waves, X, is derived through performing a coordinate transform of X and solving a variation problem subject to three constraint conditions of f（ x ）. Compared with the maximum entropy PDFs presented previously, the new PDF has the following merits：（1） it has four parameters to be determined and hence can give more refined fit to observed data and has wider suitability for nonlinear waves in different conditions; （2） these parameters are expressed in terms of distribution moments of X in a relatively simple form and hence are easy to be determined from observed data; （3） the PDF is free of the restriction of weak nonlinearity and possible to be used for sea waves in complicated conditions, such as those in shallow waters with complicated topography; and （4） the PDF is simple in form and hence convenient for theoretical and practical uses. *** wind-wave experiments have been conducted to test the competence of the new PDF for the surface elevation of nonlinear waves. The experimental results manifest that the new PDF gives somewhat better fit to the laboratory wind-wave data than the well-known Gram-Charlier PDF and beta PDF.

关键词： maximum entropy probability density function (PDF) Gram-Charlier PDF beta PDF

Constructing maximum entropy Language Models for Movie Review Subjectivity Analysis

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2008年第2期23卷 231-239页

作者：陈博何慧郭军 Pattern Recognition and Intelligent System Laboratory School of Information Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China

Document subjectivity analysis has become an important aspect of web text content mining. This problem is similar to traditional text categorization, thus many related classification techniques can be adapted here. However, there is one significant difference that more language or semantic information is required for better estimating the subjectivity of a document. Therefore, in this paper, our focuses are mainly on two aspects. One is how to extract useful and meaningful language features, and the other is how to construct appropriate language models efficiently for this special task. For the first issue, we conduct a Global-Filtering and Local-Weighting strategy to select and evaluate language features in a series of n-grams with different orders and within various distance-windows. For the second issue, we adopt maximum entropy （MaxEnt） modeling methods to construct our language model framework. Besides the classical MaxEnt models, we have also constructed two kinds of improved models with Gaussian and exponential priors respectively. Detailed experiments given in this paper show that with well selected and weighted language features, MaxEnt models with exponential priors are significantly more suitable for the text subjectivity analysis task.

关键词： exponential prior language model maximum entropy n-gram subjectivity analysis

Scatter factor confidence interval estimate of least square maximum entropy quantile function for small samples

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2016年第5期29卷 1285-1293页

作者： Wu Fuxian Wen Weidong Jiangsu Province Key Laboratory of Aerospace Power System College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics

Classic maximum entropy quantile function method （CMEQFM） based on the probability weighted moments （PWMs） can accurately estimate the quantile function of random variable on small samples, but inaccurately on the very small samples. To overcome this weakness, least square maximum entropy quantile function method （LSMEQFM） and that with constraint condition （LSMEQFMCC） are proposed. To improve the confidence level of quantile function estimation, scatter factor method is combined with maximum entropy method to estimate the confidence interval of quantile function. From the comparisons of these methods about two common probability distributions and one engineering application, it is showed that CMEQFM can estimate the quantile function accurately on the small samples but inaccurately on the very small samples （10 samples）; LSMEQFM and LSMEQFMCC can be successfully applied to the very small samples; with consideration of the constraint condition on quantile function, LSMEQFMCC is more stable and computationally accurate than LSMEQFM; scatter factor confidence interval estimation method based on LSMEQFM or LSMEQFMCC has good estimation accuracy on the confidence interval of quantile function, and that based on LSMEQFMCC is the most stable and accurate method on the very small samples （10 samples）.

关键词： Confidence intervals maximum entropy Quantile function Reliability Scatter factor Small samples

Incorporating Linguistic Structure into maximum entropy Language Models

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2003年第1期18卷 131-136页

作者：方高林高文王兆其 Department of Computer Science and Engineering Harbin Institute of Technology Harbin 150001 P.R. China Department of Computer Science and Engineering Harbin Institute of Technology Harbin 150001 P.R. ChinaInstitute of Computing Technology The Chinese Academy of Sciences Beijing 100080 P.R. China Institute of Computing Technology The Chinese Academy of Sciences Beijing 100080 P.R. China

In statistical language models, how to integrate diverse linguistic knowledge in a general framework for long-distance dependencies is a challenging issue. In this paper, an improved language model incorporating linguistic structure into maximum entropy framework is *** proposed model combines trigram with the structure knowledge of base phrase in which trigram is used to capture the local relation between words, while the structure knowledge of base phrase is considered to represent the long-distance relations between syntactical structures. The knowledge of syntax, semantics and vocabulary is integrated into the maximum entropy *** results show that the proposed model improves by 24% for language model perplexity and increases about 3% for sign language recognition rate compared with the trigram model.

关键词： maximum entropy language model base phrase identification sign language recognition

TW-Co-MFC:Two-Level Weighted Collaborative Fuzzy Clustering Based on maximum entropy for Multi-View Data

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

Tsinghua Science and Technology 2021年第2期26卷 185-198页

作者： Jie Hu Yi Pan Tianrui Li Yan Yang School of Information Science and Technology Southwest Jiaotong UniversityChengdu 611756China Department of Computer Science Georgia State UniversityAtlantaGA 30302-3994USA

In recent years,multi-view clustering research has attracted considerable attention because of the rapidly growing demand for unsupervised analysis of multi-view data in practical *** the significant advances in multi-view clustering,two challenges still need to be addressed,i.e.,how to make full use of the consistent and complementary information in multiple views and how to discriminate the contributions of different views and features in the same view to efficiently reveal the latent cluster structure of multi-view data for *** this study,we propose a novel Two-level Weighted Collaborative Multi-view Fuzzy Clustering(TW-Co-MFC)approach to address the aforementioned *** TW-Co-MFC,a two-level weighting strategy is devised to measure the importance of views and features,and a collaborative working mechanism is introduced to balance the within-view clustering quality and the cross-view clustering *** an iterative optimization objective function based on the maximum entropy principle is designed for multi-view *** on real-world datasets show the effectiveness of the proposed approach.

关键词： multi-view clustering fuzzy clustering collaborative weighting maximum entropy

A Value Classification of Electronic Product Reviews Based on maximum entropy

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2016年第6期25卷 1071-1078页

作者： ZUO Yayao LI Jiejun TANG Yong SHU Zhongmei Faculty of Computer Guangdong University of Technology School of Computer Science South China Normal University School of Education Sun Yat-sen University

Reviews of electronic product are important resources for manufacturers to gather feedbacks from customers. They provide an important reference for customers to make a decision on product purchase. Electronic product reviews with high quality is valuable, and reviews analysis is becoming an open issue. Based on the binary feature function, a maximum entropy classification of electronic product reviews is proposed to identify the valuable reviews. Considering the simpleness of the theme in reviews, a text classifier integrated with the features of descriptive anaphor is provided to enhance the model’s fitting degree. Furthermore, the feature library is constructed by the Term frequency-inverse document frequency(TF-IDF)algorithm to locate the description, and the descriptive anaphors are identified by means of the minimum Inflectional phrase(IP) parsing tree. The experiment shows the proposed classifier has the relatively high stability and precision, which makes the reviews much more usable for manufacturers to make product strategy and for customers to make a decision.

关键词： maximum entropy Binary feature function Electronic product reviews Review classification Anaphor identification

OIL MONITORING DIAGNOSTIC CRITERIONS BASED ON maximum entropy PRINCIPLE

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2005年第2期18卷 255-258页

作者： HuoHua LiZhuguo XiaYanchun SchoolofMechanicalEngineering ShanghaiJiaotongUniversityShanghai200030China

A method of applying maximum entropy probability density estimation approachto constituting diagnostic criterions of oil monitoring data is presented. The method promotes theprecision of diagnostic criterions for evaluating the wear state of mechanical facilities, andjudging abnormal data. According to the critical boundary points defined, a new measure onmonitoring wear state and identifying probable wear faults can be got. The method can be applied tospectrometric analysis and direct reading ferrographic analysis. On the basis of the analysis anddiscussion of two examples of 8NVD48A-2U diesel engines, the practicality is proved to be aneffective method in oil monitoring.

关键词： maximum entropy Diagnostic standard Oil monitoring Wear condition