共查询到20条相似文献,搜索用时 31 毫秒
1.
An ultra-massive distributed virtual environment generally consists of ultra-massive terrain data and a large quantity of
objects and their attribute data, such as 2D/3D geometric models, audio/video, images, vectors, characteristics, etc. In this
paper, we propose a novel method for constructing distributed scene graphs with high extensibility. Thismethod can support
high concurrent interaction of clients and implement various tasks such as editing, querying, accessing and motion controlling.
Some application experiments are performed to demonstrate its efficiency and soundness.
Supported by the National Basic Research Program of China (Grant No. 2004CB719403), the National High-Tech Research & Development
Program of China (Grant Nos. 2006AA01Z334, 2007AA01Z318, 2009AA01Z324), the National Natural Science Foundation of China (Grant
Nos. 60573151, 60703062, 60833007), and the Marine 908-03-01-10 Project 相似文献
2.
This paper investigates the problem of receding horizon state estimation for networked control systems (NCSs) with random
network-induced delays less than one sample period, which are formulated as multirate control systems. Based on a batch of
recent past slow rate measurements in a finite horizon window, the initial state estimation in this window is solved by minimizing
a receding-horizon objective function, and then the fast rate state estimations are calculated by the prediction of dynamic
equation to compensate for the network-induced time delays. Furthermore, convergence results and unbiasedness properties are
analyzed. An upper bound of estimation error is presented under the assumption of bounded disturbances acting on the system
and measurement equations. A simulation example shows the effectiveness of the proposed method.
Supported by the National Natural Science Foundation of China (Grant Nos. 60774015, 60674018, 60825302), the National High-Tech
Research & Development Program of China (Grant No. 2006AA04Z173), the Specialized Research Fund for the Doctoral Program of
Higher Education of China (Grant No. 20060248001), and partly by Shanghai Natural Science Foundation (Grant No. 07JC14016) 相似文献
3.
The highlight line model is a powerful tool in assessing the quality of a surface. It increases the flexibility of an interactive
design environment. In this paper, a method to generate a highlight line model on an arbitrary triangular mesh is presented.
Based on the highlight line model, a technique to remove local shape irregularities of a triangular mesh is then presented.
The shape modification is done by solving a minimization problem and performing an iterative procedure. The new technique
improves not only the shape quality of the mesh surface, but also the shape of the highlight line model. It provides an intuitive
and yet suitable method for locally optimizing the shape of a triangular mesh.
Supported by National Science Foundation of China (Grant Nos. 60533070, 60625202), National Basic Research Program of China
(Grant No. 2004CB719400), National High-Tech Research & Development Program of China (Grant No. 2007AA040401), Fok Ying Tung
Education Foundation (Grant No. 111070), National Science Foundation of USA (Grant Nos. DMI-0422126, DMS-0310645), and Kentucky
Science & Technology Corporation (Grant No. COMM-Fund-712) 相似文献
4.
A min-max model predictive control strategy is proposed for a class of constrained nonlinear system whose trajectories can
be embedded within those of a bank of linear parameter varying (LPV) models. The embedding LPV models can yield much better
approximation of the nonlinear system dynamics than a single LTV model. For each LPV model, a parameter-dependent Lyapunov
function is introduced to obtain poly-quadratically stable control law and to guarantee the feasibility and stability of the
original nonlinear system. This approach can greatly reduce computational burden in traditional nonlinear predictive control
strategy. Finally a simulation example illustrating the strategy is presented.
Supported by the National Natural Science Foundation of China (Grant Nos. 60774015, 60825302, 60674018), the National High-Tech
Research & Development Program of China (Grant No. 2007AA041403), the Specialized Research Fund for the Doctoral Program of
Higher Education of China (Grant No. 20060248001), and partly by Shanghai Natural Science Foundation (Grant No. 07JC14016) 相似文献
5.
New delay-dependent criterion for the stability of recurrent neural networks with time-varying delay
This paper is concerned with the global asymptotic stability of a class of recurrent neural networks with interval time-varying
delay. By constructing a suitable Lyapunov functional, a new criterion is established to ensure the global asymptotic stability
of the concerned neural networks, which can be expressed in the form of linear matrix inequality and independent of the size
of derivative of time varying delay. Two numerical examples show the effectiveness of the obtained results.
Supported by the National Natural Science Foundation of China (Grant Nos. 60534010, 60728307, 60774048, 60774093), the Program
for Cheung Kong Scholars and Innovative Research Groups of China (Grant No. 60521003) and the National High-Tech Research
& Development Program of China (Grant No. 2006AA04Z183), China Postdoctoral Sciencer Foundation (Grant No. 20080431150), and
the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 200801451096) 相似文献
6.
Dan Hao Member CCF Lu Zhang Senior Member CCF Ming-Hao Liu He Li and Jia-Su Sun Senior Member CCF 《计算机科学技术学报》2009,24(2):284-293
Software testing is an important technique to assure the quality of software systems, especially high-confidence systems. To automate the process of software testing, many automatic test-data generation techniques have been proposed. To generate e?ective test data, we propose a test-data generation technique guided by static defect detection in this paper. Using static defect detection analysis, our approach first identifies a set of suspicious statements which are likely to contain faults, then generates t... 相似文献
7.
Ji Wang Senior Member CCF Xiao-Dong Ma Wei Dong Hou-Feng Xu and Wan-Wei Liu Member CCF 《计算机科学技术学报》2009,24(2):347-356
We present a demand-driven approach to memory leak detection algorithm based on flow- and context-sensitive pointer analysis.
The detection algorithm firstly assumes the presence of a memory leak at some program point and then runs a backward analysis
to see if this assumption can be disproved. Our algorithm computes the memory abstraction of programs based on points-to graph
resulting from flow- and context-sensitive pointer analysis. We have implemented the algorithm in the SUIF2 compiler infrastructure
and used the implementation to analyze a set of C benchmark programs. The experimental results show that the approach has
better precision with satisfied scalability as expected.
This work is supported by the National Natural Science Foundation of China under Grant Nos. 60725206, 60673118, and 90612009,
the National High-Tech Research and Development 863 Program of China under Grant No. 2006AA01Z429, the National Basic Research
973 Program of China under Grant No. 2005CB321802, the Program for New Century Excellent Talents in University under Grant
No. NCET-04-0996, and the Hunan Natural Science Foundation under Grant No. 07JJ1011. 相似文献
8.
A Trust-Based Approach to Estimating the Confidence of the Software System in Open Environments 总被引:1,自引:0,他引:1 下载免费PDF全文
Emerging with open environments, the software paradigms, such as open resource coalition and Internetware, present several novel characteristics including user-centric, non-central control, and continual evolution. The goal of obtaining high confidence on such systems is more di?cult to achieve. The general developer-oriented metrics and testing-based methods which are adopted in the traditional measurement for high confidence software seem to be infeasible in the new situation. Firstly, the software develo... 相似文献
9.
10.
Estimation of differential geometric properties on a discrete surface is a fundamental work in computer graphics and computer
vision. In this paper, we present an accurate and robust method for estimating differential quantities from unorganized point
cloud. The principal curvatures and principal directions at each point are computed with the help of partial derivatives of
the unit normal vector at that point, where the normal derivatives are estimated by fitting a linear function to each component
of the normal vectors in a neighborhood. This method takes into account the normal information of all neighboring points and
computes curvatures directly from the variation of unit normal vectors, which improves the accuracy and robustness of curvature
estimation on irregular sampled noisy data. The main advantage of our approach is that the estimation of curvatures at a point
does not rely on the accuracy of the normal vector at that point, and the normal vectors can be refined in the process of
curvature estimation. Compared with the state of the art methods for estimating curvatures and Darboux frames on both synthetic
and real point clouds, the approach is shown to be more accurate and robust for noisy and unorganized point cloud data.
Supported in part by the National Natural Science Foundation of China (Grant Nos. 60672148, 60872120), the National High-Tech
Research & Development Program of China (Grant Nos. 2006AA01Z301, 2008AA01Z301), and Beijing Municipal Natural Science Foundation
(Grant No. 4062033) 相似文献
11.
This paper presents the definition of multi-dimensional scalability of the Internet architecture, and puts forward a mathematical method to evaluate Internet scalability based on a variety of constraints. Then, the method is employed to study the Internet scalability problem in performance, scale and service scalability. Based on the examples, theoretical analysis and experimental simulation are conducted to address the scalability issue. The results show that the proposed definition and evaluation method of multi-dimensional Internet scalability can effectively evaluate the scalability of the Internet in every aspect, thus providing rational suggestions and methods for evaluation of the next generation Internet architecture. 相似文献
12.
In this paper, the concept of globally exponentially attractive set is proposed and used to consider the ultimate bounds of the family of Lorenz systems with varying parameters. Explicit estimations of the ultimate bounds are derived. The results presented in this paper contain all the existing results as special cases. In particular, the critical cases, b→ 1^+ and a→0^+, for which the previous methods failed, have been solved using a unified formula. 相似文献
13.
FAN JianCun YIN QinYe & WANG WenJie School of Electronic Information Engineering Xi’an Jiaotong University Xi’an China 《中国科学F辑(英文版)》2009,52(6):1067-1074
Focusing on space-time block code (STBC) systems with unknown co-channel interference, an oblique projection-based robust
linear receiver is proposed in this paper. Based on the oblique projection, the desired signal subspace and interference-plus-noise
subspace are first identified from the received signal. Then the matched filter receiver is used to decode the STBC encoded
signals in the desired signal subspace. Simulation results show that the proposed linear receiver obtains significant performance
improvement over conventional Capon-type receivers under finite sample-size situations and in the presence of channel estimation
errors.
Supported partially by the National Natural Science Foundation of China (Grant Nos. 60572046, 60502022, 60772095), and the
National High-Tech Research & Development Program of China (Grant No. 2006AA01Z220) 相似文献
14.
This paper presents an optimized 64-bit parallel adder. Sparse-tree architecture enables low carry-merge fan-outs and inter-stage wiring complexity. Single-rail and semi-dynamic circuit improves operation speed. Simulation results show that the proposed adder can operate at 485ps with power of 25.6mW in 0.18μm CMOS process. It achieves the goal of higher speed and lower power. 相似文献
15.
In this paper, a multivariable direct adaptive controller using multiple models without minimum phase assumption is presented
to improve the transient response when the parameters of the system jump abruptly. The controller is composed of multiple
fixed controller models, a free-running adaptive controller model and a re-initialized adaptive controller model. The fixed
controller models are derived from the corresponding fixed system models directly. The adaptive controller models adopt the
direct adaptive algorithm to reduce the design calculation. At every instant, the optimal controller is chosen out according
to the switching index. The interaction of the system is viewed as the measured disturbance which is eliminated by the choice
of the weighing polynomial matrix. The global convergence is obtained. Finally, several simulation examples in a wind tunnel
experiment are given to show both effectiveness and practicality of the proposed method. The significance of the proposed
method is that it is applicable to a non-minimum phase system, adopting direct adaptive algorithm to overcome the singularity
problem during the matrix calculation and realizing decoupling control for a multivariable system.
Supported by the National Natural Science Foundation of China (Grant Nos. 60504010, 60864004), the National High-Tech Research
and Development Program of China (Grant No. 2008AA04Z129), the Key Project of Chinese Ministry of Education (Grant No. 208071),
and the Natural Science Foundation of Jiangxi Province (Grant No. 0611006) 相似文献
16.
Neural Network Algorithm for Designing FIR Filters Utilizing Frequency-Response Masking Technique 下载免费PDF全文
Xiao-Hua Wang 《计算机科学技术学报》2009,24(3):463-471
This paper presents a new joint optimization method for the design of sharp linear-phase finite-impulse response (FIR) digital filters which are synthesized by using basic and multistage frequency-response-masking(FRM) techniques.The method is based on a batch back-propagation neural network algorithm with a variable learning rate mode.We propose the following two-step optimization technique in order to reduce the complexity.At the first step,an initial FRM filter is designed by alternately optimizing th... 相似文献
17.
A survey on virtual reality 总被引:2,自引:0,他引:2
QinPing Zhao 《中国科学F辑(英文版)》2009,52(3):348-400
Virtual reality (VR) is a scientific method and technology created during the exploration of the nature by human beings to
understand, simulate, and better adapt and use the nature. Based on the analysis on the whole process of VR, this paper presents
different categories of VR problems and a type of theoretical expression, and abstracts three kinds of scientific and technical
problems in VR field. On the basis of foresaid content, this paper also studies current major research objectives, research
results and development trend of VR in the aspects of VR modeling method, VR representation technology, human-machine interaction
and devices, VR development suites and supporting infrastructure, as well as VR applications. Finally, several theoretical
and technical problems that need to be further studied and solved are addressed.
Supported by the National Basic Research Program of China (Grant No. 2009CB320805), the National Natural Science Foundation
of China (Grant Nos. 60533070, 60503066), and the National High-Tech Research & Development Program of China (Grant Nos. 2006AA01Z333,
2006AA01Z311) 相似文献
18.
This paper addresses the mathematical relation on a set of periods and temporal indexing constructions as well as their applications.
First we introduce two concepts, i.e. the temporal connection and temporal inclusion, which are equivalence relation and preorder
relation respectively. Second, by studying some basic topics such as the division of “large” equivalence classes and the overlaps
of preorder relational sets, we propose a temporal data index model (TDIM) with a tree-structure consisting of a root node,
equivalence class nodes and linearly ordered branch nodes. Third, we study algorithms for the temporal querying and incremental
updating as well as dynamical management within the framework of TDIM. Based on a proper mathematical supporting, TDIM can
be applied to researching some significant practical cases such as temporal relational and temporal XML data and so on.
Supported by the National Natural Science Foundation of China (Grant Nos. 60373081, 60673135), the Natural Science Foundation
of Guangdong Province (Grant No. 05003348), the Program of New Century Excellent Person Supporting of Ministery of Education
of China (Grant No. NCET-04-0805) 相似文献
19.
Virtual human is a digital representation of the geometric and behavioral property of human beings in the virtual environment
generated by computer. The research goal of virtual human synthesis is to generate realistic human bodymodels and natural
human motion behavior. This paper introduces the development of the related researches on these two topics, and some progresses
on example based human modeling and motion synthesis, and their applications in Chinese sign language teaching, computeraided
sports training and public safety problem studying. Finally, some hot research topics in virtual human synthesis are presented.
Supported partially by the National High-Tech Research & Development Program of China (Grant Nos. 2006AA01Z336, 2007AA01Z320),
and the National Natural Science Foundation of China (Grant No. 60533070) 相似文献
20.
An optimal iterative learning control (ILC) strategy of improving endpoint products in semi-batch processes is presented by
combining a neural network model. Control affine feed-forward neural network (CAFNN) is proposed to build a model of semi-batch
process. The main advantage of CAFNN is to obtain analytically its gradient of endpoint products with respect to input. Therefore,
an optimal ILC law with direct error feedback is obtained explicitly, and the convergence of tracking error can be analyzed
theoretically. It has been proved that the tracking errors may converge to small values. The proposed modeling and control
strategy is illustrated on a simulated isothermal semi-batch reactor, and the results show that the endpoint products can
be improved gradually from batch to batch.
Supported by the National Natural Science Foundation of China (Grant Nos. 60404012, 60874049), the National High-Tech Research
& Development Program of China (Grant No. 2007AA041402), the New Star of Science and Technology of Beijing City (Grant No.
2006A62), and the IBM China Research Lab 2008 UR-Program 相似文献