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1.
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
2.
This paper presents a nonlinear dynamic model for simulation and analysis of a kind of parametrically excited vibration of
stay cable caused by support motion in cable-stayed bridges. The sag, inclination angle of the stay cable are considered in
the model, based on which, the oscillation mechanism and dynamic response characteristics of this kind of vibration are analyzed
through numerical, calculation. It is noted that parametrically excited oscillation of a stay cable with certain, sag, inclination
angle and initial static tension force may occur in cable-stayed bridges due to deck vibration under the condition that the
natural frequency of a cable approaches to about half of the, first model frequency of the bridge deck system. A new vibration
control system installed on the cable anchorage is proposed as a possible damping system to suppress, the cable parametric
oscillation. The numerical calculation results showed that with the use of this damping system, the cable oscillation due
to the vibration of the deck and/or towers will be considerably reduced.
Project supported by National Natural Science Foundation of China (No. 59978044) 相似文献
3.
INTRODUCTION Monocrystalline SBN (Strontium barium nio-bium, SrxBa1?xNb2O6, denoted SBNx?100, where 0.25≤x≤0.75) solid solution, is currently being inves-tigated as potential material for many micro-device applications, such as piezoelectric infrared detectors, piezoelectric, electro-optic modulators, and holo-graphic storage (Koch et al., 1998), because SBN has one of the largest known linear electro-optic coeffi-cients (r33=1300 pm/V for SBN75), two orders of magnitude larger th… 相似文献
4.
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
5.
The nonlinear predator-prey reaction diffusion systems for singularly perturbed Robin Problems are considered. Under suitable
conditions, the theory of differential inequalities can be used to study the asymptotic behavior of the solution for initial
boundary value problems.
Project supported by the National Natural Science Foundation of China (No. 10071048), and by the “Hundred Talents Project”
of the Chinese Academy of Sciences 相似文献
6.
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
7.
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
8.
The technique of real-time digital speckle pattern interferometry is proposed to study diffusion of surfactants in hydrogel.
The diffusion coefficient is simply and directly determined from the interferograms. An example of diffusion coefficient measurement
of surfactant in agarose gel demonstrates the usefulness of the method. The results obtained are compared with the theoretical
simulating values.
Project Supported by National Natural Science Foundation of China (No. 29904007), Zhejiang Provincial Natural Science Foundation
of China (No. 699031), and SRF for ROCS, SEM, China 相似文献
9.
Unbalanced vibration in dual-rotor rotating machinery was studied with numerical simulations and experiments. A new method
is proposed to separate vibration signals of inner and outer rotors for a system with very little difference in rotating speeds.
Magnitudes and phase values of unbalance defects can be obtained directly by sampling the vibration signal synchronized with
reference signal. The balancing process is completed by the reciprocity influence coefficients of inner and outer rotors method.
Results showed the advantage of such method for a dual-rotor system as compared with conventional balancing.
Project supported by the National Natural Science Foundation of China (No. 59875078), and Zhejiang Provincial Natural Science
Foundation of China (No. 502092) 相似文献
10.
This paper proposes novel multi-layer neural networks based on Independent Component Analysis for feature extraction of fault
modes. By the use of ICA, invariable features embedded in multi-channel vibration measurements under different operating conditions
(rotating speed and/or load) can be captured together. Thus, stable MLP classifiers insensitive to the variation of operation
conditions are constructed. The successful results achieved by selected experiments indicate great potential of ICA in health
condition monitoring of rotating machines.
Project supported by the National Natural Science Foundation (No. 50205025) and the Natural Science Foundation of Zhejiang
Province (No. 5001004). 相似文献
11.
关于混沌洛伦兹系统和陈系统中的广义投影同步 总被引：1，自引：1，他引：1
1 Introduction Since Pecora and Carroll[1]showed that it is possibleto synchronize two identical chaotic systems , chaossynchronization has been intensively and extensivelystudied due to its potential applications in secure com-munication,ecological systems ,systemidentification,etc.(see [2] and a huge volume of references citedtherein) . Among all kinds of chaos synchronizations ,projec-tive synchronization is one of the most noticeableones .This kind of synchronization was first observedin … 相似文献
12.
A new algorithm is presented that generates developable Bézier surfaces through a Bézier curve called a directrix. The algorithm
is based on differential geometry theory on necessary and sufficient conditions for a surface which is developable, and on
degree evaluation formula for parameter curves and linear independence for Bernstein basis. No nonlinear characteristic equations
have to be solved. Moreover the vertex for a cone and the edge of regression for a tangent surface can be obtained easily.
Aumann’s algorithm for developable surfaces is a special case of this paper.
Project supported by the National Basic Research Program (973) of China (No. 2004CB719400), the National Natural Science Foundation
of China (Nos. 60373033 and 60333010) and the National Natural Science Foundation for Innovative Research Groups (No. 60021201),
China 相似文献
13.
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
14.
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
15.
Nonlinear dynamics analysis of a new autonomous chaotic system 总被引：2，自引：0，他引：2
CHU Yan-dong LI Xian-feng ZHANG Jian-gang CHANG Ying-xiang 《浙江大学学报(A卷英文版)》2007,8(9):1408-1413
In this paper,a new nonlinear autonomous system introduced by Chlouverakis and Sprott is studied further,to present very rich and complex nonlinear dynamical behaviors. Some basic dynamical properties are studied either analytically or nu-merically,such as Poincaré map,Lyapunov exponents and Lyapunov dimension. Based on this flow,a new almost-Hamilton chaotic system with very high Lyapunov dimensions is constructed and investigated. Two new nonlinear autonomous systems can be changed into one another by adding or omitting some constant coefficients. 相似文献
16.
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
17.
HAN Shu-guang JIANG Yi-wei HU Jue-liang 《浙江大学学报(A卷英文版)》2007,8(1):127-133
INTRODUCTION In this paper we investigate the uniform ma-chines scheduling problem with machine activationcost. This problem has application in garment pro-duction of international trade and is motivated by thefollowing scenario. Import-export company is com-pared to scheduler in this model, and orders are jobs,which arrive one by one. And garment factories canbe regarded as machines. Since jobs should be fin-ished on time, scheduler will choose a reasonablenumber of machines to make the… 相似文献
18.
Samarium and a catalytic amount of iodine were used to obtain functionalized cyclopentenes by reductive dimerization followed
by intramolecular cyclization of 1,1-dicyanoalkenes under mild conditions.
Preject (No. 20072033) supported by the National Natural Science Foundation of China, and Zhejiang Provincial Natural Science
Foundation of China 相似文献
19.
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
20.
A new generalized inverse function-valued Padé approximation (GIFPA) was defined. Existence condition of GIFPA was given and
its uniqueness theorem was proved. All possible degeneracy cases of GIFPA were discussed and constructed. An example was given
to illustrate its application.
Project supported by the National Natural Science Foundation of China (Grant No. 10271074) 相似文献