共查询到20条相似文献，搜索用时 312 毫秒
1.
A novel time-frequency domain interference excision technique is proposed. The technique is based on adaptive biorthogonal local discrete cosine transform (BLDCT). It uses a redundant library of biorthogonal local discrete cosine bases and an efficient concave cost function to match the transform basis to the interfering signal. The main advantage of the algorithm over conventional transform domain excision algorithms is that the basis functions are not fixed but can be adapted to the time-frequency structure of the interfering signal. It is well suited to transform domain compression and suppression of various types of interference. Compared to the discrete wavelet transform (DWT) that provides logarithmic division of the frequency bands, the adaptive BLDCT can provide more flexible frequency resolution. Thus it is more insensitive to variations of jamming frequency. Simulation results demonstrate the improved bit error rate (BER) performance and the increased robustness of the receiver. 相似文献
2.
In this paper we propse a semi-fragile watermarking scheme,which can be used for image authentication.Let the original image be performed by l-level discrete wavelet transformation.An approximate wavelet coefficient matrix of the original image and real-value chaotic sequences are than used to generate the content-based and secure watermark.The watermark is embedded into original image by using by using HVS.The tamper detection can idantify the tampered region of the received watermarked image,Experimental results are given. 相似文献
3.
A neural-statistical approach to the reconstruction of novel viewpoint image general regression neural networks(GRNN) is presented.Different color value will be obtained by watching the same surface point of an abject from different viewpoints due to specular reflection,and the difference is related to the position of viewpoint.The relationship between the position of vewpoint and the color of image is non-linear,neural network is introduced to make curve fitting,where the inputs of neural network are only a few calibrated images with obvious specular reflection.By training the neural network,network model is obtained.By inputing an arbitrary virtual viewpoint to the model,the image of the virtual viewpoint can be computed.By using the method presented here,novel viewpoint image with photo-realistic property can be obtained,especially images with obvious specular reflection can accurately be generated.The method is an image-based rendering method,geometric model of the scene and position of lighting are not needed. 相似文献
4.
毕金钵 《上海大学学报(英文版)》2004,8(3):286-288
AA modified version of the bilinear Baecklund transformation for the MKdV equation was given, with which some new solutions of the MKdV equation are obtained. The approach used here is general and can be applied to other soliton equations. 相似文献
5.
ZHAO Yong-jie 《重庆大学学报(英文版)》2011,10(2):60-67
The paper presents a new solution of inverse displacement analysis of the general six degree-of-freedom serial robot. The inverse displacement analysis of the general serial robot is transformed into a minimization problem and then the optimization method is adopted to solve the nonlinear least squares problem with the analytic form of new Jacobian matrix. In this way, joint variables of the general serial robot can be searched out quickly under the desired precision when positions of the three non-collinear end effector points are given. Compared with the general Newton iterative method, the proposed algorithm can search out the solution when the robot is at the singular configuration and the initial configuration used in the optimization method may also be the singular configuration. So the convergence domain is bigger than that of the general Newton iterative method. Another advantage of the proposed algorithm is that positions of the three non-collinear end effector points are usually much easier to be measured than the orientation of the end effector. The inverse displacement analysis of the general 6R (six-revolute-joint) serial robot is illustrated as an example and the simulation results verify the efficiency of the proposed algorithm. Because the three non-collinear points can be selected at random, the method can be applied to any other types of serial robots. 相似文献
6.
Design of general multivariable process controllers is an attractive and practical alternative to optimizing design by evolutionary algorithms （EAs） since it can be formulated as an optimization problem. A closed-loop particle swarm optimization （CLPSO） algorithm is proposed by mapping PSO elements into the closed-loop system based on control theories. At each time step, a proportional integral （PI） controller is used to calculate an updated inertia weight for each particle in swarms from its last fitness. With this modification, limitations caused by a uniform inertia weight for the whole population are avoided, and the particles have enough diversity. After the effectiveness, efficiency and robustness are tested by benchmark functions, CLPSO is applied to design a multivariable proportional-integral-derivative （PID） controller for a solvent dehydration tower in a chemical plant and has improved its performances. 相似文献
7.
Multi-objective optimization of water supply network rehabilitation with non-dominated sorting Genetic Algorithm-II 总被引：2，自引：0，他引：2
Xi JIN Jie ZHANG Jin-liang GAO Wen-yan WU 《浙江大学学报(A卷英文版)》2008,9(3):391-400
Through the transformation of hydraulic constraints into the objective functions associated with a water supply network rehabilitation problem, a non-dominated sorting Genetic Algorithm-II （NSGA-II） can be used to solve the altered multi-objective optimization model. The introduction of NSGA-II into water supply network optimal rehabilitation problem solves the conflict between one fitness value of standard genetic algorithm （SGA） and multi-objectives of rehabilitation problem. And the uncertainties brought by using weight coefficients or punish functions in conventional methods are controlled. And also by in- troduction of artificial inducement mutation （AIM） operation, the convergence speed of population is accelerated; this operation not only improves the convergence speed, but also improves the rationality and feasibility of solutions. 相似文献
8.
YU Bin TIAN Feng-chun HE Qing-hu RAN Jian LV Bo HONG Xin LIU Tao BI Yu-tian 《重庆大学学报(英文版)》2016,15(4):127-138
In this paper, a wavelet packet feature selection method for lung sounds based on optimization is proposed to obtain the best feature set which maximizes the differences between normal lung sounds and abnormal lung sounds (sounds with wheezes or rales). The proposed method includes two main steps: Firstly, the wavelet packet transform (WPT) is used to extract the original features of lung sounds; then the genetic algorithm (GA) is used to select the best feature set. The obtained optimal feature set is sent to four different classifiers to evaluate the performance of the proposed method. Experimental results show that the feature set obtained by the proposed method provides a higher classification accuracy of 94.6% in comparison with the best wavelet packet basis approach and multi-scale principal component analysis (PCA) approach. Meanwhile, the proposed method has effective generalization performance and can obtain the best feature set without priori knowledge of lung sounds. 相似文献
9.
RAHIMI N SADEGHI M. H. MAHJOOB M.J. 《浙江大学学报(A卷英文版)》2007,8(9):1443-1451
In this paper,a geometric approach to fault detection and isolation (FDI) is applied to a Multiple-Input Multi-ple-Output (MIMO) model of a frame and the FDI results are compared to the ones obtained in the Single-Input Single-Output (SISO),Multiple-Input Single-Output (MISO),and Single-Input Multiple-Output (SIMO) cases. A proper distance function based on parameters obtained from parametric system identification method is used in the geometric approach. ARX (Auto Regressive with eXogenous input) and VARX (Vector ARX) models with 12 parameters are used in all of the above-mentioned models. The obtained results reveal that by increasing the number of inputs,the classification errors reduce,even in the case of applying only one of the inputs in the computations. Furthermore,increasing the number of measured outputs in the FDI scheme results in decreasing classification errors. Also,it is shown that by using probabilistic space in the distance function,fault diagnosis scheme has better performance in comparison with the deterministic one. 相似文献
10.
A robust face pose estimation approach is proposed by using face shape statistical model approach and pose parameters are represented by trigonometric functions. The face shape statistical model is firstly built by analyzing the face shapes from different people under varying poses. The shape alignment is vital in the process of building the statistical model. Then, six trigonometric functions are employed to represent the face pose parameters. Lastly, the mapping function is constructed between face image and face pose by linearly relating different parameters. The proposed approach is able to estimate different face poses using a few face training samples. Experimental results are provided to demonstrate its efficiency and accuracy. 相似文献
11.
基于数据融合的多小波基联合图像去噪 总被引：1，自引：0，他引：1
提出了一种基于数据融合的多小波基联合图像去噪新方法．该方法首先用多个小波基分别对含噪图像进行分解、阈值处理和恢复,得到多幅恢复图像,然后根据像素点邻域的方差对这些图像进行加权融合获得最终去噪图像。该方法充分体现小波基的多样性和图像的局部特性。实验结果表明,该方法去噪效果比单一小波基方法和已有的多小波基联合方法都有明显的改善。 相似文献
12.
薛明志 《商丘师范学院学报》2001,17(2):43-48
利用转移算子和一致可积性的有关知识，讨论了周期小波分析中高维周期尺度函数的双正交性，得到了尺度函双正交的充要条件，所得结果推广了尺度函数正交性的某些结果，在周期小波分析理论及应用的研究中，具有重要意义。 相似文献
13.
提出一种将前馈神经网络用于非线性时变系统辩识的学习算法 ,其要点是把网络权值看作时变系统的一个状态 ,用卡尔曼滤波估计此状态 ,于是网络实现了非线性和时变的映射 .文中推导了该算法 ,仿真结果证实了它的有效性 相似文献
14.
在Piella G等人提出的自适应提升小波变换的基础上,提出了有效分析电能质量信号扰动检测与定位的改进的自适应提升小波预测算法;根据改进的自适应提升小波对信号的极强分类能力,将经过派克变换后的电能质量信号分为正常区与扰动区以及间断点区与非间断点区,再对各不同的区运用不同的更新算法与预测算法,能够快速准确地对电能质量信号作出扰动检测定位以及扰动程度的定量刻划;并且根据测出的扰动时间及扰动方向可以对扰动类型做出准确的分类;运用该算法对电压凸起、电压凹陷、电压暂态中断、电压瞬时脉冲、电压暂态振荡的检测与定位以及电压谐波的分析都证实了该算法的准确性和有效性。 相似文献
15.
张树忠 《福建工程学院学报》2018,(6):516-519
针对风力发电机关键部件齿轮箱故障频率高、诊断难的问题,开发了包含传统时频域分析和现代分析模块的故障诊断系统。该系统对所采集的振动信号进行了小波去噪、小波包分解并重构后得到各频段能量占比的特征向量,将该特征向量输入到Back Propagation（BP）神经网络模型进行振动信号与正常或各故障状态之间映射,从而智能识别运行状态。应用Matlab和Labview开发系统,输入齿轮箱的4种典型运行状态进行验证,结果表明,所设计的系统可较好地对风机齿轮箱的故障进行诊断。 相似文献
16.
Many educational and psychological tests are inherently multidimensional, meaning these tests measure two or more dimensions or constructs. The purpose of this module is to illustrate how test practitioners and researchers can apply multidimensional item response theory (MIRT) to understand better what their tests are measuring, how accurately the different composites of ability are being assessed, and how this information can be cycled back into the test development process. Procedures for conducting MIRT analyses–from obtaining evidence that the test is multidimensional, to modeling the test as multidimensional, to illustrating the properties of multidimensional items graphically-are described from both a theoretical and a substantive basis. This module also illustrates these procedures using data from a ninth-grade mathematics achievement test. It concludes with a discussion of future directions in MIRT research. 相似文献
17.
为提高基于表面肌电信号的人体腰背动作识别率,提出一种基于小波包能量与改进NARX神经网络的分类识别新方法。利用小波包变换对动作部位进行表面肌电信号特征提取,并采用改进NARX神经网络进行分类识别。选取8名实验者分别在扭腰、弯腰、侧弯腰3种动作下进行表面肌电信号数据采集,选择db4小波包函数对信号进行6层分解,得到第6层64个频带的小波包分解系数,代表各个动作信息的特征向量,作为改进NARX神经网络的输入进行分类识别。对照实验组中,改进NARX神经网络的识别率较高,总体识别率达到96.7%。实验结果表明,利用该识别方法对腰部动作进行分类识别,分类准确,且识别率更高。 相似文献
18.
从多维角度评估全新版大学英语教材 总被引：1，自引：0，他引：1
从多维角度对全新版大学英语综合教程和听力教程进行了评估。首先运用Tomlinson的教材评估模式制定了该教材评估的标准,然后通过问卷和访谈获得了使用教材师生的意见,对教材本身的特点进行了评估,并对如何更好地使用教材和改编教材提出了建议。 相似文献
19.
林宇飞 《宁波大学学报(教育科学版)》2013,(1):106-110
跨文化交际能力的培养是英语教学改革的方向。项目组将原有的Moodle网络学习平台的基础上进行移动化改造,增设文化教学动态管理模块,构建职业英语跨文化交际泛在学习环境。以系统而丰富的文化资源的输入,培养学生对英语语言及文化的认知能力;通过教学引导、激发学生非言语交际意识,提高学生的跨文化交际敏感度;采用综合文化教学法,提高学生的跨文化交际宽容度;运用英语在线互动功能,提高学生的跨文化教学灵活度。 相似文献
20.
付丽辉 《中国现代教育装备》2010,(13):60-62
利用一种改进的BP神经网络（PSO-BP）建立的教学成绩给定模型,在教学过程中所涉及的平时成绩给定的指标体系基础上,利用给定指标值作为输入,成绩估算值作为输出,通过PSO对BP神经网络的参数进行训练和学习,并利用Matlab软件建立实验平台。实验结果表明：新算法充分利用了神经计算的快速性以及粒子群算法的全局寻优能力,使得模型具有良好的辨识精度,可以较好地解决教学过程中平时成绩给定的动态问题。 相似文献