共查询到20条相似文献，搜索用时 46 毫秒
1.
A method was presented to implement the detecting and tracking of moving targets through omnidirectional vision. The method
combined optical flow with particle filter arithmetic, in which optical flow field was used to detect and locate moving targets
and particle filter was used to track the detected moving objects. According to the circular image character of omnidirectional
vision, the calculation equation of optical flow field and the tracking arithmetic of particle filter were improved based
on the polar coordinates at the omnidirectional center. The edge of a randomly moving object could be detected by optical
flow field and was surrounded by a reference region in the particle filter. A dynamic motion model was established to predict
particle state. Histograms were used as the features in the reference region and candidate regions. The mutual information
(MI) and Gaussian function were combined to calculate particle weights. Finally, the state of tracked object was computed
by the total particle states with weights. Experiment results show that the proposed method could detect and track moving
objects with better real-time performance and accuracy.
Supported by Tianjin Higher Education Technology Development Foundation (No.20071308), Tianjin Natural Science Foundation
(06YFJMJC03600) and National Natural Science Foundation of China (No.60773073).
YANG Shuying, born in 1964, female, Dr, Prof. 相似文献
2.
GUO Rong-hua QIN Zheng 《浙江大学学报(A卷英文版)》2007,8(10):1588-1595
In this study, an unscented particle filtering method based on an interacting multiple model (IMM) frame for a Markovian switching system is presented. The method integrates the multiple model (MM) filter with an unscented particle filter (UPF) by an interaction step at the beginning. The framework (interaction/mixing, filtering, and combination) is similar to that in a standard IMM filter, but an UPF is adopted in each model. Therefore, the filtering performance and degeneracy phenomenon of particles are improved. The filtering method addresses nonlinear and/or non-Gaussian tracking problems. Simulation results show that the method has better tracking performance compared with the standard IMM-type filter and IMM particle filter. 相似文献
3.
Stabilization for a class of second-order switched systems with saturation constrains 总被引：1，自引：0，他引：1
This paper proposes a global stabilization method for a class of planar switched systems with input saturation constrains
by using a state feedback and switching strategy. This method is proved to be effective by analyzing the characteristics of
the trajectory of second-order linear systems with input saturation.
Project supported by the China Postdoctoral Science Foundation (Grant No.20070420643), the National Natural Science Foundation
of China (Grant No.60774059), and the Innovation Program of the Shanghai Municipal Science and Technology Commission (Grant
No.08DZ2272400) 相似文献
4.
Xiao-li ZHAN ;Bi CHEN ;Qing-hua ZHANG ;Ling-min YI ;Bo JIANG ;Feng-qiu CHEN 《浙江大学学报(A卷英文版)》2008,9(9):1304-1308
A series of new amphiphilic poly[methyl（3,3,3-trifluoropropyl）siloxane]-b-poly（ethylene oxide） （PMTFPS-b-PEO） diblock copolymers with different ratios of hydrophobic segment to hydrophilic segment were prepared by coupling reactions of end-functlonal PMTFPS and PEO homopolymers. Copolymers were shown to be well defined and narrow molecular weight distribution （MWD） （1.07-1.3） by characterizations such as gel permeation chromatography （GPC） and ^1H-nudear magnetic resonance （^1H-NMR）. 相似文献
5.
In this work, the aerodynamic stability of the Yichang Suspension Bridge over Yangtze River during erection was determined
by three-dimensional nonlinear flutter analysis, in which the nonlinearities of structural dynamic characteristics and aeroelastic
forces caused by large deformation are fully considered. An interesting result obtained was that the bridge was more stable
when the stiffening girders were erected in a non-symmetrical manner as opposed to the traditional symmetrical erection schedule.
It was also found that the severe decrease in the aerodynamic stability was due to the nonlinear effects. Therefore, the nonlinear
factors should be considered accurately in aerodynamic stability analysis of long-span suspension bridges during erection.
Project supported by National Natural Science Foundation of China(No. 598954410), and China Postdoctoral Science Foundation
(No. 2002031245) 相似文献
6.
Different classes of first-principle pseudopotentials are compared and various schemes for pseudopotential generation based
on norm conservation are discussed in this paper. BHS (Bachelet, Hamann, and Schlüter)-scheme and V (Vanderbilt)-modifications
are used to derive the KB (Kleinman and Bylander)-pseudopotentials and pseudo wave functions of bismuth. Quality test of pseudopotentials
shows that no ghost states occur in the logarithmic derivatives of pseudo wave functions of Bismuth. The obtained bond length
of bismuth dimer with this type of pseudopotentials is in good agreement with previous accurately calculatedab initio quantum chemical result.
Project supported by the Ministry of Science and Technology of China (NKBRSF-G19990646), the Postdoctoral Science Foundation
of China, and the Scientific Research Foundation of State Education Ministry for Returned Overseas Chinese Scholars 相似文献
7.
HUANG Wen-liang LI Shi-jian LIU Duo 《浙江大学学报(A卷英文版)》2007,8(12):1971-1982
Localization is one of the substantial issues in wireless sensor networks. The key problem for the mobile beacon localization is how to choose the appropriate beacon trajectory. However, little research has been done on it. In this paper, firstly, we deduce the number of positions for a beacon to send a packet according to the acreage of ROI （region of interest）; and next we present a novel method based on virtual force to arrange the positions in arbitrary ROI; then we apply TSP （travelling salesman problem） algorithm to the positions sequence to obtain the optimal touring path, i.e. the reduced beacon trajectory. When a mobile beacon moves along the touring path, sending RF signals at every position, the sensors in ROI can work out their position with trilateration. Experimental results demonstrate that the localization method, based on the beacon reduced path, is efficient and has flexible accuracy. 相似文献
8.
Influence of input acoustic power on regenerator＇s performance 总被引：2，自引：0，他引：2
TANG Ke HUANG Zhong-jie JIN Tao BAO Rui CHEN Guo-bang 《浙江大学学报(A卷英文版)》2007,8(9):1452-1456
Performance of a pulse tube cooler significantly depends on the efficient operation ofits regenerator. Influence of input acoustic power on regenerator＇s performance is simulated and analyzed with simple harmonic analysis method. Given regenerator＇s dimensions and pressure ratio, there is an optimal input acoustic power for achieving a highest coefficient of performance, due to a compromise between relative time-averaged total energy flux in regenerator and relative acoustic power at regenerator＇s cold end. Additionally, optimal dimensions of regenerator are also estimated and presented for different input acoustic powers. The computed optimal diameter obviously increases with increase of input acoustic power, while the optimal length decreases slightly, and as a result, a larger input acoustic power requires a smaller aspect ratio （length over diameter）. 相似文献
9.
JIN Tao ZHANG Bao-sen TANG Ke BAO Rui CHEN Guo-bang 《浙江大学学报(A卷英文版)》2007,8(2):205-209
INTRODUCTION In the past 30 years, much progress has been achieved in thermoacoustic research (Backhaus and Swift, 1999; Garrett et al., 1993; Zhou and Matsubara,1998). However, most of them were still at laboratory scale. Aiming for industrial applications, recent re-searches began to pay attention to larger or smaller scale systems. The problem of heat dissipation from miniature high-tech products (say ICs, MEMS) at-tracts more attention due to the higher heat flux ac-companying th… 相似文献
10.
Stress analysis of anisotropic thick laminates in cylindrical bending using a semi-analytical approach 总被引：1，自引：0，他引：1
LU Chao-feng LIM C.W. XU Feng 《浙江大学学报(A卷英文版)》2007,8(11):1740-1745
Semi-analytical elasticity solutions for bending of angle-ply laminates in cylindrical bending are presented using the state-space-based differential quadrature method (SSDQM). Partial differential state equation is derived from the basic equations of elasticity based on the state space concept. Then, the differential quadrature (DQ) technique is introduced to discretize the longitu- dinal domain of the plate so that a series of ordinary differential state equations are obtained at the discrete points. Meanwhile, the edge constrained conditions are handled directly using the stress and displacement components without the Saint-Venant principle. The thickness domain is solved analytically based on the state space formalism along with the continuity conditions at interfaces. The present method is validated by comparing the results to the exact solutions of Pagano’s problem. Numerical results for fully clamped thick laminates are presented, and the influences of ply angle on stress distributions are discussed. 相似文献
11.
将交互式多模型(IMM)算法应用到分布式多传感器融合跟踪系统中,代替原有系统的单模型Kalman滤波,推导出了分布式多传感器交互式多模型信息融合算法,并通过仿真实例验证了算法的效果。 相似文献
12.
In this paper, dynamics in the oscillations of the relative atomic population in two periodically driven and weakly coupled Bose-Einstein eondensates (BECs) was qualitatively studied. Using the well-known Melnikov method, the conditions of existence of the periodic and chaotic coherent atomic tunnellings were given in the model. Our results indicate the typical route from bifurcation of the limited circles to chaos, and are in agreement with the previous numerical results. 相似文献
13.
A novel asymmetrical pitch system for rotary wing is presented. The pitch control characteristics are studied and analyzed.
Because elastic linkage is a key part in whole asymmetrical pitch system, in order to obtain the variation of the elastic
linkage deformation, an experimental platform mainly based on the device of micro aerial vehicles (MAVs) and a new control
system mounted on TMS320LF2407 are designed. This control system has its compacted configuration and reliability. Finally,
using this system to control the MAV for simulating the flying forward, experimental results show the MAV’s flight attitude
can be controlled based on the variation of the elastic linkage.
Project supported by the National Natural Science Foundation of China (Grant No.60605028), the National High-Technology Research
and Development Program of China (Grant No.2007AA04Z225), the Shanghai Rising-Star Program (Grant Nos.07QA14024, 07QH14006),
the Shanghai Shuguang Program (Grant No.07SG47), and the Shanghai Leading Key Laboratory of Mechanical Automation and Robotics
Science Foundation (Grant No.ZZ0805) 相似文献
14.
A repulsive vortex-vortex interaction model was used to numerically study the melting transition of the two-dimensional vortex
system with Monte Carlo method. Then a δ-function-like peak in the specific heat was observed and the internal energy showed
a sharp drop at the melting temperature, which indicated that there exists a first-order melting transition at finite temperatures.
The Lindemann criterion was also investigated and valid, but different from previous simulation results.
Project supported by the Science and Technology Ministry of China (No. NKBRST-G19990646) and Zhejiang Provincial Natural Science
Foundation (No. 199031) 相似文献
15.
He Li Xiao-qing Ma Fan Ye Jing Zhang Xin Zhou Zhi-hong Wang Yu-ming Li Guo-yuan Zhang 《Journal of Zhejiang University. Science. B》2009,10(3):203-210
Evidence suggests that the deterioration of communication between the sympathetic nervous system and cardiovascular system
always accompanies the aging of human and animals. Cardiac sympathetic norepinephrine (NE) transporter (NET) on presynaptic
membrane is a predominant component to eliminate released NE in the synaptic cleft and maintains the sensitivity of the β-adrenergic
receptor (β-AR). In the present study, we investigated NET and β1-AR mRNA levels and sympathetic nerve density in cardiac
sympathetic ganglion and left ventricular myocardium in 2- and 16-month-old rats with Northern blot analysis and immunohistochemistry.
The expression levels of NET mRNA, NET protein and β1-AR mRNA in the ganglia or myocardia of 16-month-old rats were markedly reduced by 67%, 26%, and 43%, respectively, in comparison
with those in 2-month-old rats. Our results also show that aging induces a strong decrease of the catecholaminergic nerve
fiber density.
Project supported by the Postdoctoral Fellow Foundation of the Science and Technology Committee of Shanghai (No. 98–10) and
the Natural Science Foundation of Chinese People’s Armed Police Force (Nos. WKH2006-5 and WKH2008ZO4), China 相似文献
16.
FANG You-tong YAO Ying-ying 《浙江大学学报(A卷英文版)》2007,8(3):412-415
In this paper, a modified transient finite element (FE) algorithm for the performance analysis of magnetically levitated vehicles of electromagnetic type is presented. The algorithm incorporates the external power system and vehicle’s movement equations into FE model of transient magnetic field computation directly. Sliding interface between stationary and moving region is used during the transient analysis. The periodic boundaries are implemented in an easy way to reduce the computation scale. It is proved that this method can be used for both electro-motional static and dynamic cases. The test of a transformer and an EMS-Maglev system reveals that the method generates reasonable results at very low computational costs comparing with the transient FE analysis. 相似文献
17.
In this paper, we discuss a class of piecewise linear hyperbolic maps on the 2-torus. These maps arise in the second-order digital fdter with two＇ s complement arithmetic. By introducing codings underlying the map operations, we give some admissibility conditions for symbolic sequences and find some periodic properties of these symbolic sequences. Then we use these conditions to check the admissibility of periodic symbol sequences. 相似文献
18.
A system dynamics approach to urban water demand forecasting was developed based on the analysis of urban water resources
system, which was characterized by multi-feedback and nonlinear interactions among system elements. As an example, Tianjin
water resources system dynamic model was set up to forecast water resources demand of the planning years. The practical verification
showed that the relative error was lower than 10%. Furthermore, through the comparison and analysis of the simulation results
under different development modes presented in this paper, the forecasting results of the water resources demand of Tianjin
was achieved based on sustainable utilization strategy of water resources.
Supported by National Natural Science Foundation of China (No.50578108), Doctoral Programs Foundation of Ministry of Education
of China (No.20050056016), National Key Program for Basic Research (“973” Program, No.2007CB407306-1), Science and Technology
Development Foundation of Tianjin (No.033113811 and No.05YFSYSF032), Educational Commission of Hebei Province (No.2008324)
and Tianjin Social Key Foundation (No.tjyy08-01-078).
ZHANG Hongwei, born in 1956, male, Dr. Prof. 相似文献
19.
20.
We establish an exchange rate determination model for central banks’ interventions in financial markets. The model shows that
central banks can adjust exchange rate by several policy instruments and that different instruments may have different effects
on exchange rate determination. It specifies potential policy instruments for central banks as well as their policy effects.
Based on these effects, feasible matches of policy instruments in contingent intervention are put forth.
Project supported by the National Natural Science Foundation of China (No. 79870074) 相似文献