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平面湍流混合层的准相似性理论 被引量:10
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作者 周培源 黄永念 孟庆国 《力学学报》 EI CSCD 北大核心 1990年第1期1-8,共8页
本文应用周培源的理论,给出了不可压缩平面湍流混合层的一级近似解,我们考虑连续性方程,平均运动方程和二阶脉动速度关联方程,忽略二阶脉动速度关联方程中的三阶关联项,并引进自模拟假设,得到了和实验符合的平均速度,二阶脉动速度关联... 本文应用周培源的理论,给出了不可压缩平面湍流混合层的一级近似解,我们考虑连续性方程,平均运动方程和二阶脉动速度关联方程,忽略二阶脉动速度关联方程中的三阶关联项,并引进自模拟假设,得到了和实验符合的平均速度,二阶脉动速度关联项和湍流微尺度等的理论计算结果。 展开更多
关键词 湍流 平面 混合层 准相 自模似
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Classification of forearm action surface EMG signals based on fractal dimension 被引量:1
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作者 胡晓 王志中 任小梅 《Journal of Southeast University(English Edition)》 EI CAS 2005年第3期324-329,共6页
Surface electromyogram (EMG) signals were identified by fractal dimension.Two patterns of surface EMG signals were acquired from 30 healthy volunteers' right forearm flexor respectively in the process of forearm su... Surface electromyogram (EMG) signals were identified by fractal dimension.Two patterns of surface EMG signals were acquired from 30 healthy volunteers' right forearm flexor respectively in the process of forearm supination (FS) and forearm pronation (FP).After the raw action surface EMG (ASEMG) signal was decomposed into several sub-signals with wavelet packet transform (WPT),five fractal dimensions were respectively calculated from the raw signal and four sub-signals by the method based on fuzzy self-similarity.The results show that calculated from the sub-signal in the band 0 to 125 Hz,the fractal dimensions of FS ASEMG signals and FP ASEMG signals distributed in two different regions,and its error rate based on Bayes decision was no more than 2.26%.Therefore,the fractal dimension is an appropriate feature by which an FS ASEMG signal is distinguished from an FP ASEMG signal. 展开更多
关键词 action surface electrolnyogram (ASEMG) signal: fractal dimension: wavelet packet transform(WPT) fuzzy self-similarity Bayes decision
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Solutions to a Novel Casimir Equation for the Ito System 被引量:1
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作者 Robert A.Van Gorder 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第11期801-804,共4页
We discuss two classes of solutions to a novel Casimir equation associated with the Ito system,a couplednonlinear wave equation.Both travelling wave solutions and separable self-similar solutions are discussed.In a nu... We discuss two classes of solutions to a novel Casimir equation associated with the Ito system,a couplednonlinear wave equation.Both travelling wave solutions and separable self-similar solutions are discussed.In a numberof cases,explicit exact solutions are found.Such results,particularly the exact solutions,are useful in that they provideus a baseline of comparison to any numerical simulations.Besides,such solutions provide us a glimpse of the behaviorof the Ito system,and hence the behavior of a type of nonlinear wave equation,for certain parameter regimes. 展开更多
关键词 nonlinear wave equation Ito system travelling waves self-similar solutions
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Hybrid scheduling model and analysis of performance for switched industrial Ethernet 被引量:1
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作者 胡春华 吴敏 +1 位作者 刘国平 王四春 《Journal of Central South University of Technology》 EI 2007年第2期271-277,共7页
The fact that outburst traffic in industrial Ethemet was focused on that would bring self-similar phenomenon leading to the delay increase of the cyclical data, and a hybrid priority queue schedule model was proposed ... The fact that outburst traffic in industrial Ethemet was focused on that would bring self-similar phenomenon leading to the delay increase of the cyclical data, and a hybrid priority queue schedule model was proposed in which the outburst data was given the highest priority. Some properties of the self-similar outburst data were proved by network calculus, and its service curve scheduled by the switch was gained. And then the performance of the scheduling algorithm was obtained. The simulation results are close to those calculated by using network calculus model. Some results are of actual significance to the construction of switched industrial Ethernet. 展开更多
关键词 switched industrial Ethemet scheduling model SELF-SIMILAR network calculus
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RESEARCH ON SOME THEORETICAL PROBLEMS OF MAP DATA HANDLING USING FRACTAL APPROACH
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作者 WANG Qiao 《Geo-Spatial Information Science》 2000年第1期34-38,共5页
Some theoretical problems of fractal geographical map data handling are dis- cussed and some new methods about fractal dimension introducing, developing, comparing and estimating are proposed in this paper.
关键词 fractals fractal dimension SELF-SIMILARITY scale interval
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A Common Fixed Point Theorem for Weakly Compatible Mappingsin Fuzzy Semi-Metric Space
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作者 U. Rajopadhyaya K. Jha P. Kumam 《Journal of Mathematics and System Science》 2014年第11期720-724,共5页
In this paper, we establish a common fixed pointtheorem for three pairs of self-mappings in fuzzy semi-metric space which improves and extends similar known results in the literature.
关键词 Fuzzy Semi-metric space weakly compatible mapping common fixed point.
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Two-Dimensional Spatial Solitons in Nematic Liquid Crystals
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作者 ZHONG Wei-Ping YANG Zheng-Ping +2 位作者 XIE Rui-Hua Milivoj Beliè Goong Chen 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第2期324-330,共7页
We study the propagation of spatial solitons in nematic liquid crystals, using the self-similar method. Analytical solutions in the form of self-similar solitons are obtained exactly. We confirm the stability of these... We study the propagation of spatial solitons in nematic liquid crystals, using the self-similar method. Analytical solutions in the form of self-similar solitons are obtained exactly. We confirm the stability of these solutions by direct numerical simulation, and find that the stable spatial solitons can exist in various forms, such as Oaussian solitons, radially symmetric solitons, multipole solitons, and soliton vortices. 展开更多
关键词 nonlinear optics spatial solitons self-similar method nematic liquid crystals
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A SELF-SIMILAR LOCAL NEURO-FUZZY MODEL FOR SHORT-TERM DEMAND FORECASTING 被引量:2
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作者 HASSANI Hossein ABDOLLAHZADEH Majid +1 位作者 IRANMANESH Hossein MIRANIAN Arash 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2014年第1期3-20,共18页
This paper proposes a selfsimilar local neurofuzzy (SSLNF) model with mutual informati onbased input selection algorithm for the shortterm electricity demand forecasting. The proposed self similar model is composed ... This paper proposes a selfsimilar local neurofuzzy (SSLNF) model with mutual informati onbased input selection algorithm for the shortterm electricity demand forecasting. The proposed self similar model is composed of a number of local models, each being a local linear neurofuzzy (LLNF) model, and their associated validity functions and can be interpreted itself as an LLNF model. The proposed model is trained by a nested local liner model tree (NLOLIMOT) learning algorithm which partitions the input space into axisorthogonal subdomains and then fits an LLNF model and its associated validity function on each subdomain. Furthermore, the proposed approach allows different input spaces for rule premises (validity functions) and consequents (local models). This appealing property is employed to assign the candidate input variables (i.e., previous load and temperature) which influence shortterm electricity demand in linear and nonlinear ways to local models and validity functions, respectively. Numerical results from shortterm load forecasting in the New England in 2002 demonstrated the accuracy of the SSLNF model for the STLF applications. 展开更多
关键词 Mutual information self-similar local neuro-fuzzy model short-term load forecasting.
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A Lower Bound on Longitudinal Structure Function at Small x from a Self-Similarity Based Model of Proton
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作者 Akbari Jahan D.K.Choudhury 《Communications in Theoretical Physics》 SCIE CAS CSCD 2014年第5期654-658,共5页
Self-similarity based model of proton structure function at small x was reported in the literature sometime back. The phenomenological validity of the model is in the kinematical region 6.2 × 10-7 ≤ x ≤ 10-2 an... Self-similarity based model of proton structure function at small x was reported in the literature sometime back. The phenomenological validity of the model is in the kinematical region 6.2 × 10-7 ≤ x ≤ 10-2 and 0.045 ≤ Q2 ≤ 120 GeV2. We use momentum sum rule to pin down the corresponding self-similarity-based gluon distribution function valid in the same kinematical region. The model is then used to compute bound on the longitudinal structure function FL(X, Q2) for A1tarelli-Martinelli equation in QCD and is compared with the recent HERA data. 展开更多
关键词 SELF-SIMILARITY small x longitudinal structure function QCD
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Two-direction nonlocal model for image interpolation 被引量:4
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作者 ZHANG XuanDe FENG XiangChu +1 位作者 WANG WeiWei LIU GuoJun 《Science China(Technological Sciences)》 SCIE EI CAS 2013年第4期930-939,共10页
How to sufficiently exploit the self-similarity of natural images for image restoration has attracted extensive interest in the field of image processing in recent years.In fact,the self-similarity implies two-directi... How to sufficiently exploit the self-similarity of natural images for image restoration has attracted extensive interest in the field of image processing in recent years.In fact,the self-similarity implies two-direction similarity structures inherent in images,when a group of similar patches are rearranged to form a matrix,there exists similarity between both columns and rows of this matrix.In this paper,we propose a two-direction nonlocal model (TDNL) to symmetrically exploit the two-direction similarity structures in images,the model directly takes the similar patches as local adaptive dictionary to represent each patch in the image and constrain the representation coefficients by Tikhonov regularization.TDNL can achieve the best results so far and obtain significant gains over the existing methods,in terms of both peak signal to noise ratio (PSNR) measure and the visual quality when it is applied to the problem of image interpolation. 展开更多
关键词 solar energy image interpolation image priors two-direction similarity structure two-direction nonlocal model
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Solutions to Forced and Unforced Lin–Reissner–Tsien Equations for Transonic Gas Flows on Various Length Scales
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作者 Kyle A.Theaker Robert A.Van Gorder 《Communications in Theoretical Physics》 SCIE CAS CSCD 2017年第3期309-316,共8页
The Lin–Reissner–Tsien equation is useful for studying transonic gas flows, and has appeared in both forced and unforced forms in the literature. Defining arbitrary spatial scalings, we are able to obtain a family o... The Lin–Reissner–Tsien equation is useful for studying transonic gas flows, and has appeared in both forced and unforced forms in the literature. Defining arbitrary spatial scalings, we are able to obtain a family of exact similarity solutions depending on one free parameter in addition to the model parameter holding the scalings. Numerical solutions compare favorably with the exact solutions in regions where the exact solutions are valid. Mixed wave-similarity solutions, which describe wave propagation in one variable and self-similar scaling of the entire solution, are also given,and we show that such solutions can only exist when the wave propagation is sufficiently slow. We also extend the Lin–Reissner–Tsien equation to have a forcing term, as such equations have entered the physics literature recently. We obtain both wave and self-similar solutions for the forced equations, and we are able to give conditions under which the force function allows for exact solutions. We then demonstrate how to obtain these exact solutions in both the traveling wave and self-similar cases. There results constitute new and potentially physically interesting exact solutions of the Lin–Reissner–Tsien equation and in particular suggest that the forced Lin–Reissner–Tsien equation warrants further study. 展开更多
关键词 Lin-Reissner-Tsien equation similarity transform nonlinear waves exact solutions
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Degrees of freedom in low rank matrix estimation
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作者 YUAN Ming 《Science China Mathematics》 SCIE CSCD 2016年第12期2485-2502,共18页
The objective of this paper is to quantify the complexity of rank and nuclear norm constrained methods for low rank matrix estimation problems. Specifically, we derive analytic forms of the degrees of freedom for thes... The objective of this paper is to quantify the complexity of rank and nuclear norm constrained methods for low rank matrix estimation problems. Specifically, we derive analytic forms of the degrees of freedom for these types of estimators in several common settings. These results provide efficient ways of comparing different estimators and eliciting tuning parameters. Moreover, our analyses reveal new insights on the behavior of these low rank matrix estimators. These observations are of great theoretical and practical importance. In particular, they suggest that, contrary to conventional wisdom, for rank constrained estimators the total number of free parameters underestimates the degrees of freedom, whereas for nuclear norm penalization, it overestimates the degrees of freedom. In addition, when using most model selection criteria to choose the tuning parameter for nuclear norm penalization, it oftentimes suffices to entertain a finite number of candidates as opposed to a continuum of choices. Numerical examples are also presented to illustrate the practical implications of our results. 展开更多
关键词 degrees of freedom low rank matrix approximation model selection nuclear norm penalization reduced rank regression Stein's unbiased risk estimator
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