共查询到20条相似文献，搜索用时 15 毫秒
1.
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
2.
High frequency ultrasonic nondestructive testing was conducted using a direct contact method for SUS306 stainless steel treated
by high temperature and fracture tensile tests. Reflected ultrasonic echoes were analyzed. The relationships between the ultrasonic
attenuation coefficient, strength of backscattering wave and the elongation at break of the samples were obtained. The damages
were evaluated by using these results together with the analysis of microstructure and mechanics of the tested material.
Project supported by the National Natural Science Foundation of China (Grant No.60472102), and the Innovative Program of Shanghai
Municipal Education Commission (Grant No.07ZZ03) 相似文献
3.
Two types of molecular and polymer devices employing (2-(4′-biphenyl)-5-(4““““““““-tert-butylphenyl)-1,3,4-oxadiazole) (PBD)and poly(N-vinylcarbazole) (PVK) as electron transport and hole transport materials, respectively, have been fabricated. The structures of these two devices are ITO/PVK( 70 nm)/PBD(60 nm)/A1 and ITO/PVK: PBD (1:1 by mass, 70 nm)/A1. The formation of exciplex is evident by comparing the electroluminescence (EL) of a bi-layer device and the photoluminescence (PL) of a PVK and PBD mixed film.The maximum emission energy of exciplex evaluated is consistent with the peak emission of EL. Blue emissions from both devices are obtained. The type of exicplex is interpreted based on the energy level diagram of the bi-layer device. 相似文献
4.
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
5.
n-soliton-like solutions of three non-isospectral equations, the non-isospectral mKdV equation, the non-isospectral sine-Gordon equation and the non-isospeetral nonlinear Schroedinger equation were obtained by using the Hirota method. 相似文献
6.
Construction simulation and real-time control for high arch dam 总被引：1，自引：0，他引：1
A method of combining dynamic simulation with real-time control was proposed to fit the randomness and uncertainty in the
high arch dam construction process. The mathematical logic model of high arch dam construction process was established. By
combining dynamic construction simulation with schedule analysis, the process of construction schedule forecasting and analysis
based on dynamic simulation was studied. The process of real-time schedule control was constructed and some measures for dynamic
adjustment and control of construction schedule were provided. A system developed with the method is utilized in a being constructed
hydroelectric project located at the Yellow River in northwest China, which can make the pouring plan of the dam in the next
stage (a month, quarter or year) to guide the practical construction. The application result shows that the system provides
an effective technical support for the construction and management of the dam.
ZHONG Denghua, born in 1963, male, Dr, Prof.
Supported by National Natural Science Foundation of China(No.50539120), National Basic Research Program of China(“973”Program,No.
2007 CB714101), National Science Fund for Distinguished Young Scholars of China(No.50525927), and National Natural Science
Foundation of China (No.50579045). 相似文献
7.
A rice mutant with Yaponica 9522 cultivar background Oryza sativa extraordinary glume 1 （Oseg 1） was identified from the M2 mutant pool mutagenized by ^60Co γ-ray. Compared with wild type plants, Oseg 1 developed longer empty glumes and rudimentary glumes. In some Oseg 1 mutants, the number of stamens of flowers was reduced and leaf-like lodicules occurred, and excessive lemma/palea-like organ could be observed in some mutant spikelets. This indicated that OsEG1 could regulate the development of rudimentary glumes, empty glumes, lemma/palea, lodicules, and stamens. Genetic analysis indicated that Oseg 1 came from a single recessive genetic locus. To clone OsEG1 gene, F2 population was constructed by a cross between Oseg 1 （Japonica） and Guangluai4 （Indica）. Using map-based cloning approach, OsEG1 was mapped on chromosome 4, between INDEL marker OS407 and WHM0466 with genetic distance of 2.0 cm and 1.0 cm, respectively. These results are useful for further cloning and functional analysis of the OsEG1 gene. 相似文献
8.
Particle swarm optimization （PSO） is an efficient, robust and simple optimization algorithm. Most studies are mainly concentrated on better understanding of the standard PSO control parameters, such as acceleration coefficients, etc. In this paper, a more simple strategy of PSO algorithm called θ-PSO is proposed. In θ-PSO, an increment of phase angle vector replaces the increment of velocity vector and the positions are decided by the mapping of phase angles. Benchmark testing of nonlinear functions is described and the results show that the performance of θ-PSO is much more effective than that of the standard PSO. 相似文献
9.
Reaction thrust of water jet for conical nozzles 总被引：1，自引：0，他引：1
Clear knowledge on the reaction thrust of water jet is valuable for better design of water jet propulsion system. In
this paper, theoretical, numerical and experimental studies were carried out to investigate the effects of the nozzle geometry
as well as the inlet conditions on the reaction thrust of water jet. Comparison analyses reveal that the reaction thrust has a
direct proportional relationship with the product of the inlet pressure, the square of flow rate and two-thirds power exponent
of the input power. The results also indicate that the diameter of the cylinder column for the conical nozzle has great influence
on the reaction thrust characteristics. In addition, the best values of the half cone angle and the cylinder column length exist
to make the reaction thrust reach its maximum under the same inlet conditions． 相似文献
this paper, theoretical, numerical and experimental studies were carried out to investigate the effects of the nozzle geometry
as well as the inlet conditions on the reaction thrust of water jet. Comparison analyses reveal that the reaction thrust has a
direct proportional relationship with the product of the inlet pressure, the square of flow rate and two-thirds power exponent
of the input power. The results also indicate that the diameter of the cylinder column for the conical nozzle has great influence
on the reaction thrust characteristics. In addition, the best values of the half cone angle and the cylinder column length exist
to make the reaction thrust reach its maximum under the same inlet conditions． 相似文献
10.
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
11.
Cluster parallel rendering based on encoded mesh 总被引：2，自引：0，他引：2
QIN Ai-hong XIONG Hua PENG Hao-yu LIU Zhen SHI Jiao-ying 《浙江大学学报(A卷英文版)》2006,7(7):1124-1133
INTRODUCTION Three dimensional (3D) meshes are widely used to represent 3D objects. With the rapid advances in digital acquisition technology, meshes with millions of vertices are becoming increasingly common. Be- cause of memory constraints and lack of graphics power, visualizations of this magnitude are difficult or impossible to perform even on the most powerful workstations. Therefore, the need for parallel im- plementation is clear. Most previous work in high performance rendering h… 相似文献
12.
Exchange coupling and magnetization reversal mechanism in two series of Co_xNi_(1-x)/CoO(30 nm)(x=0.2 and 0.4)bilayers are studied by vector magnetometer.Two components of magnetization are measured parallel and perpendicular to the applied field.At low temperatures,coercivity H_c∝(t_(FM))~(-n),n=1.5 and 1.38 for x=0.2 and 0.4,respectively,in agreement with the random field model.At room temperature,the coercivity is nearly proportional to the inverse FM layer thickness.In addition to the exchange field and the coercivity,the characteristic of the magnetization reversal mechanism was found to change with temperature.At temperatures below 180 K,magnetization reversal process along the unidirectional axis is accompanied only by nucleation and pinning of domain wall while magnetization rotation is also involved at high temperatures. 相似文献
13.
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
14.
In this paper, we prove that any polygon P in R2 containing a fixed smooth. strictly convex and origin-symmetric body Γ whose boundary is real analytic in its interior, can be determined by its Γ-section functions among the polygons. 相似文献
15.
1 Introduction Microactuators are the key devices of micro-electro-mechanical system( MEMS) . For many MEMS devicessuch as switches , optical attenuators , pumps andvalves to function, microactuators are required . Mo-tion of microactuators can be achieved by several kindsof actuation mechanisms . Electrostatic ,piezoelectric ,magnetostrictive, magnetic ,thermomechanical actua-tors have been reported[1-5].Among the different actu-ation principles ,the electrostatic actuationis predomi-nant… 相似文献
16.
用于通信的超宽带印刷天线 总被引：1，自引：1，他引：1
1IntroductionUltra-wideband(UWB)microwave antennas are ofinterest for a variety of applications such as electroniccountermeasure,transient radars,mine detection,andunexploded ordnance(UXO)location and identifica-tion.In the early2002,the release of the UWB forcommercial communications by the Federal Communi-cation Commission(FCC,USA)sparked renewed in-terest in the subject of UWB antennas.Conventional UWB antennas such as log-periodic orspiral antennas exhibit good UWB characteristi… 相似文献
17.
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
18.
In this paper we discuss a novel storage scheme for simultaneous memory access in parallel turbo decoder. The new scheme employs vertex coloring in graph theory. Compared to a similar method that also uses unnatural order in storage, our scheme requires 25 more memory blocks but allows a simpler configuration for variable sizes of code lengths that can be implemented on-chip. Experiment shows that for a moderate to high decoding throughput （40-100 Mbps）, the hardware cost is still affordable for 3GPP＇s （3rd generation partnership project） interleaver. 相似文献
19.
INTRODUCTION Image fusion can be defined as the process by which several images, or some of their features, are combined together to form different modalities or instruments, and is of great importance in many ap- plications (Hall and Llinas, 1997; Zhou et al., 1998), such as object detection, ATR (Automatic Target Recognition), remote sensing, computer vision, and robotics. Recently some researchers recognized that it seems more meaningful to combine objects/regions rather than pixels… 相似文献
20.
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