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1.
主流形和非线性维数化简的切向空间校正 总被引：8，自引：0，他引：8
We present a new algorithm for manifold learning and nonlinear dimensionality reduction. Based on a set of unorganized da-ta points sampled with noise from a parameterized manifold, the local geometry of the manifold is learned by constructing an approxi-mation for the tangent space at each point, and those tangent spaces are then aligned to give the global coordinates of the data pointswith respect to the underlying manifold. We also present an error analysis of our algorithm showing that reconstruction errors can bequite small in some cases. We illustrate our algorithm using curves and surfaces both in 2D/3D Euclidean spaces and higher dimension-al Euclidean spaces. We also address several theoretical and algorithmic issues for further research and improvements. 相似文献
2.
WANG Yuan-jun CAO Yuan 《浙江大学学报(A卷英文版)》2006,7(9):1572-1577
INTRODUCTION In Computer Aided Design, fairness is one of the basic requirements for designing curves. If the curves are not fair, the design will be unsatisfactory and the producing process will be discommodious. In practice, there are all kinds of errors such as modelling error and measuring error. It means that the information on the data points may not be accurate. In order to obtain fair curves by interpolating these data points, we should fair the data points first. This is the so… 相似文献
3.
LI Jun HAO Peng-wei 《浙江大学学报(A卷英文版)》2006,7(7):1168-1177
INTRODUCTION Homogeneous matrices are matrices used to represent geometric transformations for homogene- ous coordinates. Because they provide uniform rep- resentation for various transformations, they are widely used in the computer graphics community. As a homogeneous matrix corresponds to a geometric transformation, a curve on the set of homogeneous matrices can be taken as a piece of motion. Thus interpolation between those matrices is of high in- terest in many applications such as c… 相似文献
4.
We begin by briefly motivating the idea of a manifold and then discuss the embedding theorems of Whitney and Nash that allow us to view these objects inside appropriately large Euclidean spaces. 相似文献
5.
LEE Jaeho PARK Joonyoung LEE Hyunchan 《浙江大学学报(A卷英文版)》2006,7(9):1508-1515
3D shape searching is a problem of current interest in several different fields. Most techniques are developed for a particular domain and used to reduce a shape into a simpler shape representation. The techniques developed for a particular domain will also find application in other domains. We propose a new shape matching method. The SSRD （spherical sectioning railroad diagram） algorithm has the general shape distribution＇s properties and overall features of the original model. The SSRD＇s useful properties are discussed. We show the experimental results for the validity of our method. 相似文献
6.
WANG Yu-shun ZHUANG Yue-ting WU Fei 《浙江大学学报(A卷英文版)》2006,7(4):556-563
INTRODUCTION Realistic facial animation is highly important in the computer graphics field as it is an essential facility for human-computer interface and virtual reality and is also a difficult task because there are so many non-rigid motions besides rigid motion of heads as expression changes. Instead of modelling all the complicated facial motions, data-driven facial ani- mation just exploits facial motion data captured in real scenes. Most motion capture systems rely upon the placement… 相似文献
7.
Image feature optimization is an important means to deal with high-dimensional image data in image semantic un- derstanding and its applications. We formulate image feature optimization as the establishment of a mapping between high- and low-dimensional space via a five-tuple model. Nonlinear dimensionality reduction based on manifold learning provides a feasible way for solving such a problem. We propose a novel globular neighborhood based locally linear embedding （GNLLE） algorithm using neighborhood update and an incremental neighbor search scheme, which not only can handle sparse datasets but also has strong anti-noise capability and good topological stability. Given that the distance measure adopted in nonlinear dimensionality reduction is usually based on pairwise similarity calculation, we also present a globular neighborhood and path clustering based locally linear embedding （GNPCLLE） algorithm based on path-based clustering. Due to its full consideration of correlations between image data, GNPCLLE can eliminate the distortion of the overall topological structure within the dataset on the manifold. Experimental results on two image sets show the effectiveness and efficiency of the proposed algorithms. 相似文献
8.
This paper is concerned with a control method for an exoskeleton ankle with electromyography (EMG) signals. The EMG signals
of human ankle and the exoskeleton ankle are introduced. Then a control method is proposed to control the exoskeleton ankle
using the EMG signals. The feed-forward neural network model applied here is composed of four layers and uses the back-propagation
training algorithm. The output signals from neural network are processed by the wavelet transform. Finally the control orders
generated from the output signals are passed to the motor controller and drive the exoskeleton to move. Through experiments,
the equality of neural network prediction of ankle movement is evaluated by giving the correlation coefficient. It is shown
from the experimental results that the proposed method can accurately control the movement of ankle joint.
Project supported by the National High-Tech R&D Program (Grant No.2006AA04Z224), the Innovation Program of Shanghai Municipal
Education Commission (Grant No.08ZZ48), and the Shanghai Leading Academic Discipline Project (Grant No.Y0102) 相似文献
9.
The choice of self-concordant functions is the key to efficient algorithms for linear and quadratic convex optimizations,
which provide a method with polynomial-time iterations to solve linear and quadratic convex optimization problems. The parameters
of a self-concordant barrier function can be used to compute the complexity bound of the proposed algorithm. In this paper,
it is proved that the finite barrier function is a local self-concordant barrier function. By deriving the local values of
parameters of this barrier function, the desired complexity bound of an interior-point algorithm based on this local self-concordant
function for linear optimization problem is obtained. The bound matches the best known bound for small-update methods.
Project supported by the National Natural Science Foundation of China (Grant No.10771133), the Shanghai Leading Academic Discipline
Project (Grant No.S30101), and the Research Foundation for the Doctoral Program of Higher Education (Grant No.200802800010) 相似文献
10.
Sludge blanket height (SBH) is an important parameter in the clarifier design, operation and control. Based on an overview
and classification of SBH algorithms, a modified SBH algorithm is proposed by incorporating a threshold concentration limit
into a relative concentration sharp change algorithm to eliminate the disturbance of compression interfaces on the correct
simulation of SBH. Pilot-scale test data are adopted to compare reliability of three SBH algorithms reported in literature
and the modified SBH algorithm developed in this paper. Calculated results demonstrate that the three SBH algorithms give
results with large deviation (> 50%) from measured SBH, especially under low solid flux conditions. The modified algorithm
is computationally efficient and reliable in matching the measured data. It is incorporated into a one-dimensional clarifier
model for stable simulation of pilot-scale experimental clarifier data and into dynamic simulation of a full-scale wastewater
treatment plant (WWTP) clarifier data.
Project supported by the National Natural Science Foundation of China (Grant No.501380107) 相似文献
11.
We present a derived grid-based model for the simulation of pedestrian flow. Interactions among pedestrians are considered as the result of forces within a certain neighbourhood. Unlike the social force model, the forces here, as in Newtonian physics, are proportional to the inverse of the square of the distance. Despite the notion ofneighbourhood and the underlying grid, this model differs from the existing cellular automaton （CA） models in that the pedestrians are treated as individuals. Bresenham＇s algorithm for line rastering is applied in the step calculation. 相似文献
12.
Sample based 3D face reconstruction from a single frontal image by adaptive locally linear embedding 总被引：1，自引：0，他引：1
ZHANG Jian ZHUANG Yue-ting 《浙江大学学报(A卷英文版)》2007,8(4):550-558
In this paper, we propose a highly automatic approach for 3D photorealistic face reconstruction from a single frontal image. The key point of our work is the implementation of adaptive manifold learning approach. Beforehand, an active appearance model (AAM) is trained for automatic feature extraction and adaptive locally linear embedding (ALLE) algorithm is utilized to reduce the dimensionality of the 3D database. Then, given an input frontal face image, the corresponding weights between 3D samples and the image are synthesized adaptively according to the AAM selected facial features. Finally, geometry reconstruction is achieved by linear weighted combination of adaptively selected samples. Radial basis function (RBF) is adopted to map facial texture from the frontal image to the reconstructed face geometry. The texture of invisible regions between the face and the ears is interpolated by sampling from the frontal image. This approach has several advantages: (1) Only a single frontal face image is needed for highly automatic face reconstruction; (2) Compared with former works, our reconstruction approach provides higher accuracy; (3) Constraint based RBF texture mapping provides natural appearance for reconstructed face. 相似文献
13.
Recently a new clustering algorithm called ＇affinity propagation＇ （AP） has been proposed, which efficiently clustered sparsely related data by passing messages between data points. However, we want to cluster large scale data where the similarities are not sparse in many cases. This paper presents two variants of AP for grouping large scale data with a dense similarity matrix. The local approach is partition affinity propagation （PAP） and the global method is landmark affinity propagation （LAP）. PAP passes messages in the subsets of data first and then merges them as the number of initial step of iterations; it can effectively reduce the number of iterations of clustering. LAP passes messages between the landmark data points first and then clusters non-landmark data points; it is a large global approximation method to speed up clustering. Experiments are conducted on many datasets, such as random data points, manifold subspaces, images of faces and Chinese calligraphy, and the results demonstrate that the two approaches are feasible and practicable. 相似文献
14.
Robust video foreground segmentation and face recognition 总被引：1，自引：0，他引：1
管业鹏 《上海大学学报(英文版)》2009,13(4):311-315
Face recognition provides a natural visual interface for human computer interaction (HCI) applications. The process of face
recognition, however, is inhibited by variations in the appearance of face images caused by changes in lighting, expression,
viewpoint, aging and introduction of occlusion. Although various algorithms have been presented for face recognition, face
recognition is still a very challenging topic. A novel approach of real time face recognition for HCI is proposed in the paper.
In view of the limits of the popular approaches to foreground segmentation, wavelet multi-scale transform based background
subtraction is developed to extract foreground objects. The optimal selection of the threshold is automatically determined,
which does not require any complex supervised training or manual experimental calibration. A robust real time face recognition
algorithm is presented, which combines the projection matrixes without iteration and kernel Fisher discriminant analysis (KFDA)
to overcome some difficulties existing in the real face recognition. Superior performance of the proposed algorithm is demonstrated
by comparing with other algorithms through experiments. The proposed algorithm can also be applied to the video image sequences
of natural HCI.
Project supported by the National Natural Science Foundation of China (Grant No.60872117), and the Leading Academic Discipline
Project of Shanghai Municipal Education Commission (Grant No.J50104) 相似文献
15.
This paper explores brain CT slices segmentation technique and some related problems, including contours segmentation algorithms,
edge detector, algorithm evaluation and experimental results. This article describes a method for contour-based segmentation
of anatomical structures in 3D medical data sets. With this method, the user manually traces one or more 2D contours of an
anatomical structure of interest on parallel planes arbitrarily cutting the data set. The experimental results showed the
segmentation based on 3D brain volume and 2D CT slices. The main creative contributions in this paper are: (1) contours segmentation
algorithm; (2) edge detector; (3) algorithm evaluation.
Project (No.69931010) supported by the National Natural Science Foundation of China 相似文献
16.
Let K be a 1-unconditional convex bodies in Euclidean spaces. We study the asymptotic properties of two affine invariants m2(K) and S2(K) for a random simplex inside K. As an application, we discuss the asymptotic properties of two affine invariants m2(Bnp) and S2(Bnp), where Bnp = {χ∈ Rn: ‖χ‖p ≤ 1}. 相似文献
17.
To find the optimal routing is always an important topic in wireless sensor networks （WSNs）. Considering a WSN where the nodes have limited energy, we propose a novel Energy^＊Delay model based on ant algorithms （＂E＆D ANTS＂ for short） to minimize the time delay in transferring a fixed number of data packets in an energy-constrained manner in one round. Our goal is not only to maximize the lifetime of the network but also to provide real-time data transmission services. However, because of the tradeoff of energy and delay in wireless network systems, the reinforcement learning （RL） algorithm is introduced to train the model. In this survey, the paradigm of E＆D ANTS is explicated and compared to other ant-based routing algorithms like AntNet and AntChain about the issues of routing information, routing overhead and adaptation. Simulation results show that our method performs about seven times better than AntNet and also outperforms AntChain by more than 150% in terms of energy cost and delay per round. 相似文献
18.
The eigenface method that uses principal component analysis （PCA） has been the standard and popular method used in face recognition. This paper presents a PCA - memetic algorithm （PCA-MA） approach for feature selection. PCA has been extended by MAs where the former was used for feature extraction/dimensionality reduction and the latter exploited for feature selection. Simulations were performed over ORL and YaleB face databases using Euclidean norm as the classifier. It was found that as far as the recognition rate is concerned, PCA-MA completely outperforms the eigenface method. We compared the performance of PCA extended with genetic algorithm （PCA-GA） with our proposed PCA-MA method. The results also clearly established the supremacy of the PCA-MA method over the PCA-GA method. We further extended linear discriminant analysis （LDA） and kernel principal component analysis （KPCA） approaches with the MA and observed significant improvement in recognition rate with fewer features. This paper also compares the performance of PCA-MA, LDA-MA and KPCA-MA approaches. 相似文献
19.
An efficient enhanced k-means clustering algorithm 总被引：9，自引：0，他引：9
FAHIM A.M SALEM A.M. TORKEY F.A. RAMADAN M.A. 《浙江大学学报(A卷英文版)》2006,7(10):1626-1633
INTRODUCTION The huge amount of data collected and stored in databases increases the need for effective analysis methods to use the information contained implicitly there. One of the primary data analysis tasks is cluster analysis, intended to help a user understand the natural grouping or structure in a dataset. Therefore, the development of improved clustering algorithms has received much attention. The goal of a clustering algorithm is to group the objects of a database into a set of m… 相似文献
20.
The sufficient and necessary conditions of the Bochner-Orlicz sequence spaces equipped with the Luxemburg norm,which have λ property,are given.The result shows,which is not as usual,that the λ property of the Bochner-Orlicz seauence spaces can not be lift from X. 相似文献