基于相关函数的二进制偏移载波调制信号无模糊捕获模型

针对二进制偏移载波(BOC)调制信号捕获模糊问题,提出了一种基于本地BOC信号分解-合成的算法。首先,将副载波按照本地BOC信号的阶数n进行分解;其次,把分解得到的函数分别与伪随机码相乘,得到2n个 BOC信号子函数,再分别与接收BOC信号作互相关得到2n个互相关函数;最后,将上一步得到的2n个互相关函数按照分解-合成算法进一步处理。理论分析和仿真结果表明,与OQCC算法相比,在捕获BOC(1,1)和BOC(2,1)信号时,该分解-合成算法的主副峰分离度(ASDMSP)有21.51 dB和3.4 dB的提高。实验结果表明,该分解-合成算法能够有效解决BOC信号捕获模糊问题。     

A parallel residue-to-binary conversion algorithm without trial division

In recent years, the conversion of residue numbers to a binary integer has been intensively studied. The Chinese Remainder Theorem (CRT) is a solution to this conversion problem of a number to the Residue Number System with a general moduli set. This paper presents a new division-free conversion approach for the conversion of residue numbers to a binary integer. The algorithm differs from others employing a great number of division instructions by using shift instructions instead. These simple instructions keep the power consumption lower. This algorithm can also be implemented with a lookup table or upon a vector machine. Both make the conversion process efficient. This division-free algorithm employs the concept of Montgomery multiplication algorithm. There are two variations of Montgomery algorithm proposed, which are algorithms MMA and IMA. The algorithm MMA is to transform the input number into the output presentation of Montgomery algorithm. Algorithm IMA is therefore inverse the computation of Montgomery algorithm to obtain the multiplicand. These two algorithms are in the complexity of O(n), where n is log₂ q_i. q_i is a modulus. The proposed algorithm for converting the residues to a binary integer therefore runs on O(n × log m) times on O(m) processors. There are O(log m) iterations of O(n) complexity. Compared with the traditional conversion algorithm, the advantages of this proposed algorithm are not only in employing simpler operations but also in performing fewer iterations.     

Parallel sorting with cooperating heaps in a linear array of processors

A parallel sorting algorithm using cooperating heaps in a linear array of processors is presented. It can sort a sequence whose length is much larger than the number of processors. Because the output begins one step after all the items have been input, sorting n items requires 2n + 1 steps. Two independent modifications of the algorithm are possible; one tries to reduce the number of processors used, and the other can sort more items on the same array.     

An optimal distributed algorithm for finding articulation points in a network

This paper presents a distributed algorithm for finding the articulation points in an n node communication network represented by a connected undirected graph. For a given graph if the deletion of a node splits the graph into two or more components then that node is called an articulation point. The output of the algorithm is available in a distributed manner, i.e., when the algorithm terminates each node knows whether it is an articulation point or not. It is shown that the algorithm requires O(n) messages and O(n) units of time and is optimal in communication complexity to within a constant factor.     

A new routing algorithm for multirate rearrangeable Clos networks

In this paper, we study the problem of finding routing algorithms on the multirate rearrangeable Clos networks which use as few number of middle-stage switches as possible. We propose a new routing algorithm called the “grouping algorithm”. This is a simple algorithm which uses fewer middle-stage switches than all known strategies, given that the number of input-stage switches and output-stage switches are relatively small compared to the size of input and output switches. In particular, the grouping algorithm implies that m = 2n+(n−1)/2^k is a sufficient number of middle-stage switches for the symmetric three-stage Clos network C(n,m,r) to be multirate rearrangeable, where k is any positive integer and rn/(2^k−1).     

Generalized pole placement via static output feedback: A methodology based on projections

This paper presents an algorithm for solving static output feedback pole placement problems of the following rather general form: given n subsets of the complex plane, find a static output feedback that places in each of these subsets a pole of the closed-loop system. The algorithm presented is iterative in nature and is based on alternating projection ideas. Each iteration of the algorithm involves a Schur matrix decomposition, a standard least-squares problem and a combinatorial least-squares problem. While the algorithm is not guaranteed to always find a solution, computational results are presented demonstrating the effectiveness of the algorithm.     

A novel adaptive image zooming scheme via weighted least-squares estimation

A critical issue in image interpolation is preserving edge detail and texture information in images when zooming. In this paper, we propose a novel adaptive image zooming algorithm using weighted least-square estimation that can achieve arbitrary integer-ratio zoom (WLS-AIZ) For a given zooming ratio n, every pixel in a low-resolution (LR) image is associated with an n × n block of high-resolution (HR) pixels in the HR image. In WLS-AIZ, the LR image is interpolated using the bilinear method in advance. Model parameters of every n × n block are worked out throughweighted least-square estimation. Subsequently, each pixel in the n × n block is substituted by a combination of its eight neighboring HR pixels using estimated parameters. Finally, a refinement strategy is adopted to obtain the ultimate HR pixel values. The proposed algorithm has significant adaptability to local image structure. Extensive experiments comparingWLS-AIZ with other state of the art image zooming methods demonstrate the superiority of WLS-AIZ. In terms of peak signal to noise ratio (PSNR), structural similarity index (SSIM) and feature similarity index (FSIM), WLS-AIZ produces better results than all other image integer-ratio zoom algorithms.     

A Simple Robust Controller for the Approximate Regulation of Almost Periodic Signals for Linear Systems

By using a delay line as a signal generator, we design a simple robust controller for the approximate regulation (i.e., approximate asymptotic tracking and rejection) of almost periodic signals for linear systems. As opposed to the related existing results, our controller design does not require online parameter tuning. Besides the usual assumptions about stabilizability, detectability, and nonexistence of transmission zeros for the plant, the controller design algorithm of this paper only requires knowledge of the desired tracking accuracy . Based on this information alone, we can only design a robust controller achieving, in the presence of unknown trigonometric polynomial disturbances and additive perturbations to the plant and the controller, . Here, is the output of the plant and is an arbitrary almost periodic reference signal taken from an infinite-dimensional generalized Sobolev space of almost periodic functions. In this paper, we also study robust output regulation in the limiting case where . It turns out that, due to the general loss of exponential closed loop stability, asymptotic tracking/rejection can also be lost as , unless the exogenous signals are smooth enough. This last result extends some recent theorems on (nonrobust) open loop output regulation for infinite-dimensional exosystems. The results of this paper are new and potentially useful for finite-dimensional plants, but the main results are also true for infinite-dimensional systems with bounded control and observation operators.     

Rational functions and pseudo-Newton algorithms

Newton's method for calculating the zeros of a polynomial almost always has periodic orbits or even stable periodic orbits. We identify a rational algorithm that converges globally to a root of the polynomial. We then proceed to examine the topology of the class of all rational functions T that have the property that for a given polynomial p(x), T(x) = x iff p(x) = 0. The topology of this set of rational functions is more complicated than the topology of Rat(n).     

Properties and calculation of transmission zeros of linear multivariable systems

A new definition of transmission zeros for a linear, multivariable, time-invariant system is made which is shown to be equivalent to previous definitions. Based on this new definition of transmission zeros, new properties of transmission zeros of a system are then obtained; in particular, it is shown that a system with an unequal number of inputs and outputs almost always has no transmission zeros and that a system with an equal number of inputs and outputs almost always has either n−1 or n transmission zeros, where n is the order of the system; transmission zeros of cascade systems are then studied, and it is shown how the transmission zeros of a system relate to the poles of a closed loop system subject to high gain output feedback. An application of transmission zeros to the servomechanism problem is also included. A fast, efficient, numerically stable algorithm is then obtained which enables the transmission zeros of high order multivariable systems to be readily obtained. Some numerical examples for a 9th order system are given to illustrate the algorithm.     

谐波法复杂周期信号周期测量

利用复杂周期信号频谱存在大量等间隔幅度起伏的谐波分量.提出了复杂周期信号的谐波法周期测量.谐波法之FT-Abs-IFT(FAIF)是周期信号频谱包络的反傅里叶变换,输出为频谱包络对应时域信号与周期冲击信号的卷积.其最大值是等幅度或起伏幅度(噪声条件下)的周期冲击信号,通过门限栓测和周期测量得到信号周期(或频率).最后通过与常用周期信号测量方法(同态滤波法、自相关法和AMDF)的仿真比较,表明对于复杂周期信号,谐波法之FAIF测量精度高,误差率低和良好的抗噪性能.     

A systolic algorithm for solving dense linear systems

For an arbitrary n × n matrix A and an n × 1 column vector b, we present a systolic algorithm to solve the dense linear equations Ax = b. An important consideration is that the pivot row can be changed during the execution of our systolic algorithm. The computational model consists of n linear systolic arrays. For 1 ≤ i ≤ n, the i^th linear array is responsible to eliminate the i^th unknown variable x_i of x. This algorithm requires 4n time steps to solve the linear system. The elapsed time unit within a time step is independent of the problem size n. Since the structure of a PE is simple and the same type PE executes the identical instructions, it is very suitable for VLSI implementation. The design process and correctness proof are considered in detail. Moreover, this algorithm can detect whether A is singular or not.     

遗传算法在周期信号傅立叶变换中的应用

为了克服周期信号进行傅立叶变换时各次谐波幅度值需要进行复杂的理论计算问题,提出一种利用遗传算法进行周期信号傅立叶变换的方法,介绍了周期信号傅立叶变换和遗传算法的基本原理;给出了使用遗传算法对周期信号进行分解适应度函数的实现方法和确定各次谐波幅值计算的方法。并提供使用遗传算法对周期信号进行分解的具体步骤。仿真实验结果表明:该方法能够满足周期信号傅立叶变换的要求,与周期信号傅立叶变换理论计算方法相比,其突出优点是算法简单,易于实现。     

Data-driven algorithm to estimate friction in automobile engine

Algorithms based on the oscillations of the engine angular rotational speed under fuel cutoff and no-load were proposed for estimation of the engine friction torque. The recursive algorithm to restore the periodic signal is used to calculate the amplitude of the engine speed signal at fuel cutoff. The values of the friction torque in the corresponding table entries are updated at acquiring new measurements of the friction moment. A new, data-driven algorithm for table adaptation on the basis of stepwise regression was developed and verified using the six-cylinder Volvo engine.     

Iterative learning control of molten steel level in a continuous casting process

In this paper, an iterative learning control (ILC) method is introduced to control molten steel level in a continuous casting process, in the presence of disturbance, noise and initial errors. The general ILC method was originally developed for processes that perform tasks repetitively but it can also be applied to periodic time-domain signals. To propose a more realistic algorithm, an ILC algorithm that consists of a P-type learning rule with a forgetting factor and a switching mechanism is introduced. Then it is proved that the input signal error, the state error and the output error are ultimately bounded in the presence of model uncertainties, periodic bulging disturbances, measurement noises and initial state errors. Computer simulation and experimental results establish the validity of the proposed control method.     

Adaptive Learning Control of Nonlinear Systems by Output Error Feedback

This paper addresses the problem of designing an output error feedback control for single-input, single-output nonlinear systems with uncertain, smooth, output-dependent nonlinearities whose local Lipschitz constants are known. The considered systems are required to be observable, minimum phase with known relative degree and known high frequency gain sign: linear systems are included. The reference output signal is assumed to be smooth and periodic with known period. By developing in Fourier series expansion a suitable periodic input reference signal, an output error feedback adaptive learning control is designed which ldquolearnsrdquo the input reference signal by identifying its Fourier coefficients: bounded closed loop signals and exponential tracking of both input and output reference signals are obtained when the Fourier series expansion is finite, while arbitrary small tracking errors are exponentially achieved otherwise. The resulting control is not model based, is independent of the system order and depends only on the relative degree, the reference signal period and the high frequency gain sign.     

A new phase extraction algorithm for phase profilometry

This paper describes a new phase extraction algorithm for 3D optical profilometry based on the projection of a periodic light pattern and phase measurement (phase profilometry). The algorithm uses a square wave to demodulate phase and moving averages and comb-shaped filters to extract the phase information from low frequency. The proposed algorithm is compared with the two major profilometry techniques, namely Fourier domain profilometry and signal domain profilometry based on FIR low-pass filtering. Comparison is focused on adaptiveness to changes of the pattern frequency, ability to deal with nonuniform surfaces and computational complexity. Adaptiveness analysis is carried out by means of simulations. The issue of nonuniform surfaces is discussed on the basis of experimental results obtained from application of phase profilometry to on-line 3D printed circuit board inspection. With regard to complexity, theoretical estimates are verified by means of actual computation time measurements. Received: 30 November 1996 / Accepted: 6 June 1997     

A magnitude/phase-locked loop approach to parameter estimation of periodic signals

Presents a parameter estimator that is designed to estimate the frequencies, magnitudes, and phases of the components of a periodic signal. The structure of the algorithm is reminiscent of a phase-locked loop, although significant differences can be observed. The performance of the estimator is analyzed, and useful design guidelines are provided. A version of the algorithm is presented that combines different components of the signal and/or signals from multiple sensors in order to estimate the fundamental frequency. In this manner, the algorithm is able to maintain tracking of the fundamental frequency despite changes in signal characteristics. The results are verified in simulations and the algorithms are found to be simple and effective for estimation and tracking of time-varying parameters. Experimental results are reported where periodic signals are collected from an active noise control testbed.     

Parallel generation of permutations on systolic arrays

We present a systolic algorithm to generate all the n! permutations of n given items. The computational model used is a linear systolic array consisting of n identical PEs. This algorithm requires n! time steps to solve this problem. Since any PE is identical and executes the same program, it is suitable for VLSI implementation. The correctness of the algorithm is proved. We also consider the ranking and unranking functions of permutations in this parallel algorithm     

基于最佳路径搜索的二进制协议格式关键词边界确定方法

针对二进制协议报文格式逆向分析中字段切分问题，提出以格式关键词为逆向分析目标，通过改进的n-gram算法和最佳路径搜索算法实现对二进制协议格式关键词的最优定界。首先，将位置因素引入n-gram算法，提出基于迭代n-gram-position的格式关键词边界提取算法，有效解决了n-gram算法中n值不易确定和固定偏移位置格式关键词的边界提取问题；然后，定义了频繁项边界命中率和左右分支信息熵为基础的分支度量，以关键词和非关键词的n-gram-position取值变化率存在差异为基础构造约束条件，提出基于最佳路径搜索的格式关键词边界选择算法，实现了对格式关键词的联合最优定界。在AIS1、AIS18、ICMP00、ICMP03和NetBios五种不同类型协议报文数据集上的测试结果表明，所提算法能够准确确定不同协议格式关键词的边界，F值均在83%以上。与VDV和AutoReEngine经典算法相比，所提算法的F值平均提升约8个百分点。