On Advances in Statistical Modeling of Natural Images

Statistical analysis of images reveals two interesting properties: (i) invariance of image statistics to scaling of images, and (ii) non-Gaussian behavior of image statistics, i.e. high kurtosis, heavy tails, and sharp central cusps. In this paper we review some recent results in statistical modeling of natural images that attempt to explain these patterns. Two categories of results are considered: (i) studies of probability models of images or image decompositions (such as Fourier or wavelet decompositions), and (ii) discoveries of underlying image manifolds while restricting to natural images. Applications of these models in areas such as texture analysis, image classification, compression, and denoising are also considered.     

Breaking Symmetries and Constraints: Transitions from 2D to 3D in Passive Walkers

The inherent dynamics of bipedal, passive mechanisms are studiedto investigate the relation between motions constrained to two-dimensional (2D)planes and those free to move in a three-dimensional (3D) environment. Inparticular, we develop numerical and analytical techniques usingdynamical-systems methodology to address the persistence and stabilitychanges of periodic, gait-like motions due to the relaxation ofconfiguration constraints and the breaking of problem symmetries. Theresults indicate the limitations of a 2D analysis to predictthe dynamics in the 3D environment. For example, it is shownhow the loss of constraints may introduce characteristically non-2Dinstability mechanisms, and how small symmetry-breaking terms may result inthe termination of solution branches.     

含二维临界部分系统的李亚普诺夫函数构造

含二维临界部分系统的李亚普诺夫函数构造苗原（清华大学计算机系北京１０００８４）李春文（清华大学自动化系北京１０００８４）关键词中心流形，稳定性，非线性系统，李亚普诺夫函数．收稿日期１９９５－１０－０６１引言李亚普诺夫函数不仅是重要的判稳工具，还与使系...     

Feedback stabilization via designed planar centre manifold

This paper addresses the problem of local state feedback stabilization of a class of nonlinear systems, which have planar centre manifold. A new technique for designing centre manifold has been developed. Using this approach, a sufficient condition for stabilization of a class of nonlinear system is obtained. The approach has been specified for two particular critical cases: ‘zero centre’ with zero eigenvalue of multiplicity 2 and ‘oscillatory centre’ with a pair of pure imaginary eigenvalues. The control law, which stabilizes the overall system, is also presented. Some examples are presented to indicate how the present theorem may be implemented. Copyright © 2003 John Wiley & Sons, Ltd.     

深海油气输送用X70厚壁直缝埋弧焊钢管的耐蚀性

开发试制了深海油气输送用X70厚壁直缝埋弧焊(LSAW)钢管(1 016mm,壁厚36.5mm),对管线钢的化学成分、组织和力学性能进行了分析,并通过氢致开裂(HIC)、硫化物应力腐蚀(SSC)、腐蚀浸泡等试验研究了钢管管体及焊接接头的耐腐蚀性能。结果表明:该试验钢管的管体及焊接接头具有良好的抗氢致开裂和抗硫化物应力腐蚀开裂性能,腐蚀速率小于0.09mm/a,可用于具有腐蚀性的海洋环境中。     

A geometric approach for adaptive estimation of unknown growth kinetics in bioreactors

This paper proposes a new approach for the estimation of unknown and time-varying specific growth rate in fed-batch bioprocess. A novel adaptive estimation technique based on the concept of invariant manifold is proposed as an effective approach to estimate growth kinetic parameters. An asymptotic nonlinear observer is used to provide simultaneous on-line estimation of biomass concentration and growth kinetic. The method is easy to implement and requires only one tuning parameter. The effectiveness of the proposed algorithm is illustrated with representative bioreactor simulation examples.     

On the design of suboptimal sliding manifold for a class of nonlinear uncertain time-delay systems

This paper proposes a new method to design suboptimal sliding manifolds for a class of nonlinear uncertain systems with state and input delays. A switching control law is obtained based on the designed suboptimal sliding manifold. It is proved that the proposed method is able to guarantee the stability of the closed-loop system in the presence of uncertainty. Three numerical simulations are given to illustrate the effectiveness of the proposed method.     

高SiMo道依茨排气管的研制

对可耐受800℃的高SiMo道依茨排气管进行了合金化试验和浇铸试验,总结认为:(1)w(C)、w(Si)、w(Mo)量对铸件力学性能和铸造性能影响较大;(2)铁液的出炉温度应不低于1 520℃,浇注温度应不低于1 410℃;(3)合理选用球化剂,同时应加强瞬时孕育;(4)应注重铁液净化及排气、补缩等工艺的合理设计。     

Manifold label prediction for low dimensional palmprint recognition

Minimum Squared Error Classification (MSEC) is a learning method for predicting the class labels of samples in real time. However, as a regression algorithm, MSEC tries its best to map the training samples into their class labels using a linear projection without considering the manifold structure of the data. In this paper, we introduce a supervised label learning framework using an effective manifold learning strategy. This method which is referred to as Manifold Supervised Label Prediction (MSLP) generalizes MSEC objective function to incorporate intra-class relationships of data. Thus, in addition to relying on the relationship between a training sample and its label, we propose to also learn the relationship between the training samples while transforming them. As a testbed for MSLP, we apply it to an image identification venue in which image samples with a very low spatial resolution (16 × 16) are used. These images have been dramatically influenced by a down-sampling process in order to reduce their size and hence, improving over computation time. We also show that the blurring process for reducing the artifacts introduced by down-sampling serendipitously results in better identification accuracies. Finally, unlike MSEC that classifies a query sample based on the deviation between the predicted and the true class labels, we compare both the training and the query samples in the label prediction space. A set of comprehensive experiments on benchmark palmprint databases including Multispectral PolyU, PolyU 2D/3D, and PolyU Contact-free I shows meaningful improvements over existing state-of-the-art algorithms.