AM-FM算子分解方法在滚动轴承故障诊断中的应用

基于算子的零空间追踪算法能够实现复杂信号的自适应分解,其关键在于信号模型的构造与求解。通过定义一种新的可完全消除调幅调频信号的调幅调频算子(AFO),进一步建立了一种基于AFO的信号分解新模型。为了提高参数对信号分解的鲁棒性,将非参数正则化(NPR)方法用于解决上述模型的约束优化问题,提出了一种基于NPR的自适应信号分解方法——NPR-AFO。论文将NPR-AFO方法引入到机械故障诊断中,并通过仿真和滚动轴承局部故障实测数据分析,与现有的其他分解方法进行了对比。结果表明:所提方法不仅可以有效的提取故障特征,而且状态故障特征更加明显。

信号重构中l_(1)-l_(2)极小化的等价模型理论研究

非凸l_(1)-l_(2)极小化方法是信号重构中最有效、最重要的模型之一,为研究信号恢复中极小化l_(1)-l_(2)重构的条件,从极小化l_(1)-l_(2)的定义出发,结合零空间的性质,基于对原优化模型中的目标函数进行松弛并利用相干性函数,推导出与原优化问题等价的新目标函数。结合信号重构中限制等距性的充分性条件,得到了极小化l_(1)-l_(2)完全重构的充分性条件,并证明了在噪声情形下两类条件的等价性。

Low-complexity transceiver design scheme based on channel null-space feedback

To reduce the negative impact of channel quantization errors, a low-complexity transceiver joint design scheme for both the transmit beamformers and receive combining vectors is proposed in the two-user multiple-input multiple-output （MIMO） system. In the scheme, the channel nullspace quantization vector is used as the transmit beamformer of the interference user directly based on channel null-space feedback. Since the interference can be determined at the receiver, interference rejection combining （IRC） is jointly utilized to cancel the inter-user interference. Simulation re- sults show that the proposed scheme can provide substantial sum-rate improvement especially at high SNR.

NULL-SPACE PROJECTION AND WATERFILLING RESOURCE ALLOCATION IN MULTI-ANTENNA COGNITIVE RADIO NETWORKS

Cognitive Radio(CR) is a promising technique for the next generation mobile communi-cation system for its capability to solve the conflicts between the scarcity and underutilization of spectrum.In this paper,aiming at maximizing the system capacity of a multi-antenna CR system on the premise that avoid interference to the primary system in the same band simultaneously,a resource allocation method which is able to avoid interference between PRimary(PR) and CR users by pro-jecting the transmit signals of CR users on the null space of the PR users' channels is proposed.CR users with better channel condition are selected,and the interference from CR system to PR users can be removed completely by projecting the transmit signals of CR system on the null-space of PR users' channels.Parallel sub-channels are constructed for CR users through Singular Value Decomposition(SVD).At last,waterfilling is also adopted to increase the CR users' capacity.Simulation result demonstrates that compared with existing methods,our method can improve the achievable sum rate of CR users as well as reduce the outage probability of PR users.

A Perturbation Analysis of Low-Rank Matrix Recovery by Schatten p-Minimization

A number of previous papers have studied the problem of recovering low-rank matrices with noise, further combining the noisy and perturbed cases, we propose a nonconvex Schatten p-norm minimization method to deal with the recovery of fully perturbed low-rank matrices. By utilizing the p-null space property (p-NSP) and the p-restricted isometry property (p-RIP) of the matrix, sufficient conditions to ensure that the stable and accurate reconstruction for low-rank matrix in the case of full perturbation are derived, and two upper bound recovery error estimation ns are given. These estimations are characterized by two vital aspects, one involving the best r-approximation error and the other concerning the overall noise. Specifically, this paper obtains two new error upper bounds based on the fact that p-RIP and p-NSP are able to recover accurately and stably low-rank matrix, and to some extent improve the conditions corresponding to RIP.

SPHERICAL SYMMETRIC SOLUTIONS FOR THE MOTION OF RELATIVISTIC MEMBRANES AND NULL MEMBRANES IN THE REISSNER-NORDSTRM SPACE-TIME

In this article, we concern the motion of relativistic membranes and null mem- branes in the Reissner-Nordstrom space-time. The equation of relativistic membranes moving in the Reissner-Nordstrom space-time is derived and some properties are discussed. Spherical symmetric solutions for the motion are illustrated and some interesting physical phenomena are discovered. The equations of the null membranes are derived and the exact solutions are also given. Spherical symmetric solutions for null membranes are just the two horizons of Reissner-NordstrSm space-time.

Dynamics and adaptive control of a dual-arm space robot with closed-loop constraints and uncertain inertial parameters

A dynamics-based adaptive control approach is proposed for a planar dual-arm space robot in the presence of closed-loop constraints and uncertain inertial parameters of the payload. The controller is capable of controlling the po- sition and attitude of both the satellite base and the payload grasped by the manipulator end effectors. The equations of motion in reduced-order form for the constrained system are derived by incorporating the constraint equations in terms of accelerations into Kane＇s equations of the unconstrained system. Model analysis shows that the resulting equations perfectly meet the requirement of adaptive controller design. Consequently, by using an indirect approach, an adaptive control scheme is proposed to accomplish position/attitude trajectory tracking control with the uncertain parameters be- ing estimated on-line. The actuator redundancy due to the closed-loop constraints is utilized to minimize a weighted norm of the joint torques. Global asymptotic stability is proven by using Lyapunov＇s method, and simulation results are also presented to demonstrate the effectiveness of the proposed approach.

Balance recovery control for biped robot based on reaction null space method

A biped walking robot should be able to keep balance even in the presence of disturbing forces. This paper presents a step strategy concept of biped walking robot that is stabilized by using reaction null space method. The called ＂step strategy＂ can be modeled by means of the reaction null space method that introduced earlier to tackle dynamic interaction problems of free-floating robots, or moving base robots in general. 6-DOF biped robot model simulations are used to confirm the validity.

Application of Null Space Based Behavior Control to the Swarm Robot’s Control

This paper proposes a solution to controls warm robots in an effort to avoid obstacles, moving to the goal by the method of Null Space based Behavior (NSB) control of an individual in the swarm. This paper also provides the stability analysis of the converging process by investigating the relationship between single agents, and the analysis result is proved by using the Lyapunov theory. Finally, the simulation results in two-dimensional space have confirmed the obtained theoretical results.

Eigen-Space Decomposition(ESD)Method for the Design of Internal Model Controller(IMC)from Noisy Input and Output Plant Data

A novel approach to design Internal Model Controller(IMC)is proposed in this paper directly from measuredinput and output plant data,which are assumed to becontaminated by measurement noise.In order to avoidthe complicated structure-identification problem inmost cases,two Finite Impulse Response(FIR)modelsare taken to represent the plant model and the internalmodel controller respectively.Taking account of mea-surement noise both in the plant input and its output,anESD based Total Least Squares(TLS)solution is appliedfor the unbiased identification of the plant model and itsinverse model,the latter constitutes the internal modelcontroller according to the principle that the internalmodel controller approximates the inverse dynamics ofthe plant model.Simulations are given for a testifica-tion.

Use Elementary Column Operations to Calculate the Basis of the Null Space of a Matrix

This paper gives and proofs a theorem, for any matrix A, do elementary column operations, change it to a matrix which is partitioned to two blocks which left one is column full rank and right one is zero matrix. That is, use a invertible matrix P to let AP = （B,O）, O is zero matrix with n-r columns, r and n is rank and column number of A, so the P＇s right n-r columns is just the basis of the null space of the matrix A. On the basis of the theorem, lots of problems of linear algebra can be resolved and lots of theorems can be proofed by elementary column operations. Perhaps the textbooks used in universities will have a lot of change with the result of the paper. This result is first found by author in 2010.12.8 in http：//www.paper.edu.cn/index.php/default/releasepaper/content/201012-232, but is not formal published.

Suppressive Influence of Time- Space White Noise on the Explosion of Solutions of Stochastic Fokker- Planck Delay Differential Equations

It is generally known that the solutions of deterministic and stochastic differential equations （SDEs） usually grow linearly at such a rate that they may become unbounded after a small lapse of time and may eventually blow up or explode in finite time. If the drift and diffusion functions are globally Lipschitz, linear growth may still be experienced, as well as a possible blow-up of solutions in finite time. In this paper, a nonlinear scalar delay differential equation with a constant time lag is perturbed by a multiplicative Ito-type time - space white noise to form a stochastic Fokker-Planck delay differential equation. It is established that no explosion is possible in the presence of any intrinsically slow time - space white noise of Ito - type as manifested in the resulting stochastic Fokker- Planck delay differential equation. Time - space white noise has a role to play since the solution of the classical nonlinear equation without it still exhibits explosion.

LOFT L9-3 Experiment Simulation Using the SPACE Code

The KHNP （Korea Hydro ＆ Nuclear Power Co.） has developed a multipurpose nuclear safety analysis code called SPACE （the safety and performance analysis code） for nuclear power plants. SPACE code is a best-estimated two-phase three-field thermal-hydraulic analysis code used to analyze the safety and performance of pressurized water reactors. In this paper, LOFT （loss of fluid test） L9-3 experiment using the SPACE code was selected to confirm the capability of SPACE code and the results calculated by the SPACE code are compared with those measured through the experiment. The results were compared with the experimental data and those of the other code simulations. Throughout the simulation result, it was concluded that the SPACE code can effectively simulate LOFT L9-3 experiment.

2×2分块对角算子矩阵拟谱的精细刻画

设A,B为可分Hilbert空间X中的稠定闭线性算子,M_(0)=(A00B)表示2×2分块算子矩阵.文中精细刻画算子矩阵M0在对角扰动情形下的拟点谱、拟剩余谱与拟连续谱,所得结论与点谱、剩余谱和连续谱的结果进行了比较,并用例子进行了辅证.最后,采用空间分解技巧,用主对角元的信息刻画M0在上三角扰动情形下的拟点谱分布.

基于零空间行为融合的多智能体编队控制综述

针对单智能体在民用和军用领域无法完成现实场景下复杂任务的问题,本文综述了零空间行为融合算法。阐述零空间行为融合算法的设计思想与数学模型,介绍零空间行为融合算法的文献计量分析。综述了零空间算法的研究进展,包括编队速度饱和、行为转换不连续、行为优先级分配和多种算法结合方面的改进工作,并分析当前研究存在的问题。研究表明:零空间行为融合算法在多智能体编队控制领域,提高算法的自适应性、考虑动力学特性、异构编队和行为函数优化是该算法未来的发展方向。

机器人用同轴磁性齿轮若干基本特性分析及其数值计算

机器人用同轴磁性齿轮受其固有特性的限制,目前难以直接应用于工业机器人,其力矩密度、传动比、空程、背隙和扭转刚度、稳定工作区等关键基本特性的研究尚存不足。为此,以国家标准规定的型14谐波齿轮性能为参考对象,采用类比的方法,运用相关电磁学理论,对与其同等空间大小的同轴磁性齿轮相关性能及其数值计算方法、稳定性以及伺服电动机和同轴磁性齿轮的一体化集成技术进行了研究和对比,指出了扭转刚度不足是制约同轴磁性齿轮用于机器人的关键因素,明确了未来机器人同轴磁性齿轮伺服控制的研究重点。

基于零空间的船舶自主靠泊自抗扰控制分配

[目的]针对船舶自主靠泊过程中遇到的环境载荷、岸壁效应、模型不确定以及控制分配误差等多源干扰的影响,提出一种基于零空间的自抗扰控制(ADRC)分配方法。[方法]首先,建立船舶靠泊运动数学模型、多源干扰模型和控制分配模型,并据此设计神经网络扩张状态观测器(NNESO)实时估计船舶运动及其所受到的多源干扰;然后,引入零空间技术设计控制分配算法,并基于该方法实现先泊位外镇定再平行靠泊方案;最后,证明船舶自主靠泊系统在所提方法下所有误差信号一致最终有界,保证船舶自主靠泊过程的安全性。[结果]仿真对比结果表明,所提方法在轨迹跟踪效果与二次规划(QP)法近似的情况下,求解所需时间为其1.3%,艏向最大分配误差为伪逆法(PI)的36.51%。[结论]所提方法在满足靠泊运动控制精度的同时,求解所需时间明显缩短,最大分配误差显著降低,保证了控制分配的实时性与精确性。

MIMO NC-OFDM系统的半盲信道估计算法研究

提出了一种基于零空间的多输入多输出不连续正交频分复用(MIMO NC-OFDM)系统的半盲信道估计的新方法。该方法利用线性预测得到信道矩阵的零空间作为LS算法的盲约束,对MIMO NC-OFDM时域信道脉冲响应进行估计。通过大量仿真表明,与传统的最小二乘算法比较,该方法可以在使用较少导频的条件下获得很好的信道估计性能,从而可以提高系统频谱有效性。

结合零空间法和F-LDA的人脸识别算法

线性判别分析(LDA)是一种常用的线性特征提取方法。传统LDA应用于人脸识别时主要存在两个问题:1)小样本问题,即由于训练样本不足引起矩阵奇异;2)优化准则函数并不直接与识别率相关。提出了一种新的能同时解决以上两个问题的基于LDA的人脸识别算法。首先,通过重新定义样本的类内散布矩阵和类间散布矩阵,提出了一种新的零空间法。然后把这种新的零空间法与F-LDA(Fractional LDA)算法相结合,得到一种对人脸识别更有效的特征提取方法。实验结果表明,这种新算法具有较高的识别率。

I-VLDNS:一种改进的线性判别子空间模式识别算法

针对现有模式判别分析方法中普遍存在的子空间优化与"小样本"问题,首先剖析总体、类内以及类间三种散布矩阵的零空间的物理含义,深入阐释有效零空间与有效线性判别零空间核心原理;其次,研究始空间中总体、类间散布矩阵与有效零空间、有效值域空间上的总体、类间散布矩阵关于特征值与特征向量之间的关联关系,并且获取类内散布矩阵零空间、值域空间上关于Fisher线性判别率的关键结论;最后,基于有效线性判别零空间理论,设计出一种改进的线性判别子空间模式识别算法,即I-VLDNS。通过相关数据集模拟实验表明,I-VLDNS算法在模式识别分析性能、精确度以及鲁棒性上均得到进一步优化与提高。