共查询到20条相似文献，搜索用时 15 毫秒
1.
A fast integration method for translating-pulsating source Green’s function in Bessho form简 总被引：1，自引：0，他引：1
The singularities and oscillatory performance of translating-pulsating source Green＇s function in Bessho form were analyzed. Relative numerical integration methods such as Gaussian quadrature rule, variable substitution method （VSM）, and steepest descent integration method （SDIM） were used to evaluate this type of Green＇s function. For SDIM, the complex domain was restricted only on the 0-plane. Meanwhile, the integral along the real axis was computed by use of the VSM to avoid the complication of a numerical search of the steepest descent line. Furthermore, the steepest descent line was represented by the B-spline function. Based on this representation, a new self-compatible integration method corresponding to parametric t was established. The numerical method was validated through comparison with other existing results, and was shown to be efficient and reliable in the calculation of the velocity potentials for the 3D seakeeping and hydrodynamic performance of floating struc- tures moving in waves. 相似文献
2.
LIGui－zhi LIUYong－ming 《上海大学学报(英文版)》2001,5(4):334-337
A study on the sorption of monocrotophos and parathion-methyl on Yellow River‘s sediments was performed.The influence of some factors,such as pH value and ionic strength,on the sorption was investigated and first order kinetics mode for the sorption of monocrophos was shown.Freundlich isotherm was suggested as the most appropriate type for monocrophos an parathion-methyl.But the sorption isotherms of monocrotophos and parathion-methyl are also in conformity with Langmuir equation.Both partition and adsorption occur to the sorption of monocrophos to Yellow River‘s sediments.but partition is the predominant for that of parathionmethyl. 相似文献
3.
This paper first introduces a way to improve interactivity with high polygon count virtual objects through the ＂mixed＂ use of image-based representation within one object. That is, both 3D polygonal and image-based representations are maintained for an object, and switched for rendering depending on the functional requirement of the object. Furthermore, in order to reduce the popping effect and provide smooth and gradual transition during the object representation switch, the object is subdivided with the subdivided parts possibly represented differently, i.e., using 3D models or images. As for the image-based representation, the relief texture （RT） method is used. In particular, through the use of the mixed representation, a new way called TangibleScreen is proposed to provide object tangibility by associating the image-based representation with a physical prop （projecting the RTs） in a selective and flexible way. Overall, the proposed method provides a way to maintain an interactive frame rate with selective perceptual details in a large-scale virtual environment, while allowing the user to interact with virtual objects in a tangible way. 相似文献
4.
数字图像分析方法在螺纹检测中的应用 总被引：3，自引：0，他引：3
This paper describes the use of computer-aided measurement for external metric screw threads.Thread parameters,including thread pitch,thread angle,pitch giameter and major diameter,were measured with CCD cameras and image analysis software.New technologies such as digital image processing were used to increase the efficiency of measurements.In this study,by reconstructing the toolmaker‘s microscope,the computer-aided semi-automated measuring system was developed,which could evaluate the accuracy of screw thread fpofile.It is concluded that the measuement accuracy is comparable to that of traditional toolmaker‘s microscope method. 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.
Interactive transport of multi-view videos for 3DTV applications 总被引：1，自引：0，他引：1
The authors propose a novel method for transporting multi-view videos that aims to keep the bandwidth requirements on both end-users and servers as low as possible. The method is based on application layer multicast, where each end point receives only a selected number of views required for rendering video from its current viewpoint at any given time. The set of selected videos changes in real time as the user‘s viewpoint changes because of head or eye movements. Techniques for reducing the black-outs during fast viewpoint changes were investigated. The performance of the approach was studied through network experiments. 相似文献
7.
A direct method for obtaining the expanding integrable models of the hierarchies of evolution equations was proposed. By using the equivalent transformation between the matrices, a new isospectral problem was directly established according to the known isospectral problem, which can be used to obtain the expanding integrable model of the known hierarchy. 相似文献
8.
考虑剪切效应弹性板弯曲问题的DQ分析方法 总被引：4，自引：0，他引：4
A differential quadrature (DQ) method for orthotropic plates was proposed based on Reddy' s theory of plates with the effects of the higher-order transverse shear deformations. Wang-Bert's DQ approach was also further extended to handle the boundary conditions of plates. The computational convergence was studied, and the numerical results were obtained for different grid spacings and compared with the existing results. The results show that the DQ method is fairly reliable and effective. 相似文献
9.
考虑剪切效应有限变形粘弹性板的动力稳定性 总被引：4，自引：0，他引：4
Based on Reddy‘s theory of plates with higher-order shear deformations and the Boltzmann superposition principles,the governing equations were established for dynamic stability of viscoelastic plates with finite deformations taking account of shear effects,The Galerkin method was applied to simplify the set of equations.The numerical methods in nonlinear dynamics were used to solve the simplified system.It could e seen that there are plenty of dynamic properties for this kind of viscoelastic plates under transverse harmonic loads.The influences of the transverse shear deformations and material parameter on the dynamic behavior of nonlinear viscoelatic plates were investigated. 相似文献
10.
Improved response surface method for anti-slide reliability analysis of gravity dam based on weighted regression 总被引：1，自引：0，他引：1
The aim of this study was to design and construct an improved response surface method （RSM） based on weighted regression for the anti-slide reliability analysis of concrete gravity dam. The limitation and lacuna of the traditional RSM were briefly analyzed. Firstly, based on small experimental points, research was devoted to an improved RSM with singular value decomposition techniques. Then, the method was used on the basis of weighted regression and deviation coefficient correction to reduce iteration times and experimental points and improve the calculation method of checking point. Finally, a test example was given to verify this method. Compared with other conventional algorithms, this method has some strong advantages： this algorithm not only saves the arithmetic operations but also greatly enhances the calculation efficiency and the storage efficiency. 相似文献
11.
Samuel Johnson (1709----1784) is a famous English essayist, literary critic and dictionary compiler. In 1747, when Johnson began his ““Dietionary of the English Language““, Chesterfield had at first indieated that he could be his patron, but when Johnson came to him for conerete help, Chesterfield neglected him to the point of ignoring him. Johnson was insulted and furious. In 1755, when Johnson‘s Dictionary was published and acclaimed after seven years of hard work, Chesterfield openly recommended it, hoping to get some credit for it as Johnson‘s patron. Johnson at once wrote his famous letter in a sharp style, openly denying Chesterfield‘s patronage, and attacking him outright for his behaviour. The attack, however, was made in a cireumloeutious way. 相似文献
12.
WANG Xin XU Liang-jun 《浙江大学学报(A卷英文版)》2007,8(3):397-402
Thermal analysis and thermal diagnose are important for small power connector especially in electronic devices since their structure is usually compact. In this paper thermal behavior of small power connector was investigated. It was found that the contact resistance increased due to the Joule heating, and that increased contact resistance produced more Joule heating; this mutual action causes the connector to lose efficiency. The thermal distribution in the connector was analyzed using finite element method (FEM). The failure mechanism is discussed. It provides basis for improving the structure. The conclusion was verified by experimental results. 相似文献
13.
ZHUHuai－liang 《上海大学学报(英文版)》2001,5(1):35-39
In this paper ,a hybrid approach was developed to investigate the transient responses of a multi-span non-uniform flexble spinning shaft with nonlinear and asymmetric supports.The non-uniform spinning shaft with variable parmeters was modeled as a Bernoulli-Euler beam column with sectional constant cross-section properties by the finite element method.The supporting stiffness behavior of the nonlinear supports was described as a piecewise-linear and asymmetric model.The equations of motion in the matrix form of a multi-span non-uniform spinning shaft with nonlinear and asymmetric supports were formulated using Hamilton‘s principle and the assumed mode method.As an example,a spinning rocket with many variable stiffness supports was numerically simulated by the direct integration method.The transient response and dynamic behavior of this rotate-dynamic system are analyzed. 相似文献
14.
基于自适应控制的非线性系统的滞后同步 总被引：2，自引：0，他引：2
Active control is an effective method for synchronizing two identical chaotic systems. However, this method works only for a certain class of chaotic systems with known parameters. An improvement method was proposed in order to overcome this limitation in this paper. A classical example was used to demonstrate the method. Finally, numerical examples were given to validate the efficiency of the method. 相似文献
15.
In China,English language skills learned in high school make students very incapable of universy’s oral English course,especially for those who want to study abroad to further their education. The data collection procedure of this study was carried out during my one year study in Canada. This study conducted the method of interview to the oversea students from Saint Mary’s University in order to provide some useful suggestions for the EFL learners who are planning to study abroad or want to improve their English speaking skill. 相似文献
16.
The representation method of heterogeneous material information is one of the key technologies of het-erogeneous object modeling, but almost all the existing methods cannot represent non-uniform rational B-spline (NURBS) entity. According to the characteristics of NURBS, a novel data structure, named NURBS material data structure, is proposed, in which the geometrical coordinates, weights and material coordinates of NURBS heterogeneous objects can be represented simultaneously. Based on this data structure, both direct representation method and inverse construction method of heterogeneous NURBS objects are introduced. In the direct representation method, three forms of NURBS heterogeneous objects are introduced by giving the geometry and material information of control points, among which the homogeneous coordinates form is employed for its brevity and easy programming. In the inverse construction method, continuous heterogeneous curves and surfaces can be obtained by interpolating discrete points and curves with specified material information. Some examples are given to show the effectiveness of the proposed methods. 相似文献
17.
In this paper,a system of complex matrix equations was studied.Necessary and sufficient conditions for the existence and the expression of generalized bipositive semidefinite solution to the system were given.In addition,a criterion for a matrix to be generalized bipositive semitic.finite was determined. 相似文献
18.
It was Sunday morning.Mary Bruce was looking out of the win-dow of her flat. In the distance she could see the trees in the park. Ithad been freezing for several days and the trees were covered with frost.Jim Bruce entered the room. ‘What are we going to do today, Mary?’he asked. ‘Let’s go for a walk in the park,’ Mary answered. ‘I believethe lake is frozen. Let’s go and feed the ducks. The poor creature 相似文献
19.
To develop a measurement system for monitoring partial discharge （PD） without the effect of external interferences,an algorithm of PD signal extraction based on wavelet transform with Teager＇s energy operators was presented. Acoustic signal generated by PD was selected to remove excessive interfering signals and electromagnetic interferences. Acoustic signals were collected and decomposed into I0 levels by wavelet transform into approximation and detail components. “Daubechies 25” was proved to be the most suitable mother wavelet for the extraction of PD acoustic signals. Compared with conventional wavelet denoising method, Teager＇s energy operators were adopted to the PD signal reconstruction and the signal to noise ratio was in creased by 20%-25% inthe experiment,without lost in energy and pulse amplitude. 相似文献
20.
A new framework for free-surface design is proposed.Using Manifolds can generalize the spline scheme to surfaces of arbitrary topology,Physics-based modeling incorporate physical laws into shape representation to provide direct shape interaction.The combination presents a new method inherits the attractive properties of the manifold surface as well as that of the physcis-based models. 相似文献