Scheduling a system of nonsingular affine recurrence equations onto a processor array

Most work on the problem of scheduling computations onto a systolic array is restricted to systems of uniform recurrence equations. In this paper, this restriction is relaxed to include systems of affine recurrence equations. In this broader class, a sufficient condition is given for the system to be computable. Necessary and sufficient conditions are given for the existence of an affine schedule, along with a procedure that constructs the schedule vector, when one exists. This material is based upon work supported by the Office of Naval Research under contract nos. N00014-84-K-0664 and N00014-85-K-0553.     

A parallel algorithm for evaluating general linear recurrence equations

A block parallel partitioning method for evaluating general linearmth order recurrence equations is presented and applied to solve the eigenvalues of symmetric tridiagonal matrices. The algorithm is based on partitioning, in a way that ensures load balance during computation. This method is applicable to both shared memory and distributed memory MIMD systems. The algorithm achieves a speedup ofO(p) on a parallel computer withp-fold parallelism, which is linear and is greater than the existing results, and the data communication between processors is less than that required for other methods. For solving symmetric tridiagonal eigenvalue problems, our method is faster than the best previous results. The results were tested and evaluated on an MIMD machine, and were within 79% to 96% of the predicted performance for the second order linear recurrence problem.Supported by the Texas Advanced Technology Program under Grant No. 999903-165 and the National Science Foundation under Grant No. MIP8809328.     

The mapping of linear recurrence equations on regular arrays

The parallelization of many algorithms can be obtained using space-time transformations which are applied on nested do-loops or on recurrence equations. In this paper, we analyze systems of linear recurrence equations, a generalization of uniform recurrence equations. The first part of the paper describes a method for finding automatically whether such a system can be scheduled by an affine timing function, independent of the size parameter of the algorithm. In the second part, we describe a powerful method that makes it possible to transform linear recurrences into uniform recurrence equations. Both parts rely on results on integral convex polyhedra. Our results are illustrated on the Gauss elimination algorithm and on the Gauss-Jordan diagonalization algorithm. This work was partially funded by the French Coordinated Research ProgramC ³ and by a Grant from the SOREP company     

从FPGA转换到门阵列

概述从FPGA或CPLD转换到门阵列是经济高效的,有时甚至只需几百个单元就能完成。这种转换设计需要什么后续技术？事实上转换到门阵列面临着电路的许多时序问题,这在FPGA设计中是不被注意的。本文论述了转换时遇到的几种由于设计不当所造成的时序问题,提出了避免这些问题的解决方案。同时对时序变化的部分原因及如何充分利用门阵列技术也进行了讨论。时序上的差异如果知道原始设计电路工作中每一步时序上的裕量,orbit半导体公司保证无论FPGA是否模拟过,都可以成功完成转换,其ATPG和结合缺省模拟分级确保了这一点。在转换完成前…     

应用CPLD实现ASI-SPI接口转换的方法

遵照国家的DVB标准及SPI接口标准,提出一种不需要使用FIFO,就能恢复出SPI接口的PSYNC、DAVLID信号的方案.经硬件实现,仅使用CPLD芯片就能完成该功能,实时稳定地产生出PSYNC、DAVLID信号,避免了使用FPGA芯片及FIFO带来的高成本问题.对SPI时钟的恢复提出一种新的解决方法,简化了ASI-SPI转换卡的硬件设计.     

抵抗仿射变换攻击的多比特图像水印

目前,大多数鲁棒图像水印所面临的最大问题就是几何攻击,而几何攻击又以仿射变换为主,攻击者只需对目标图像做轻微的几何形变就可以使嵌入其中的水印信息失效。本文在Ping Dong等人提出的基于图像归一化方法的抵抗任意仿射交换攻击的鲁棒数字水印的基础上,改进了原有的归一化方法,去掉了归一化过程中的约束条件,简化了归一化的过程。并且在此基础上提出一种新的水印嵌入方案,克服了文献[1]中水印方案水印不可见性较差的问题。实验证明,本文提出的方案对仿射变换攻击具有很好的鲁棒性,嵌入的水印容量较大且水印图像的质量较高。     

将TIF图像文件转换为BMP图像文件的方法

分析了可识别TIF和BMP图像文件格式，描述了直接将可识别TIF图像文件转换为BMP图像文件的过程，显然，本文所介绍的方法是相当实用的。     

雷达显示信号向电视信号的转换

本文介绍了将雷达显示器非标准视频信号转换为ＰＡＬ－Ｄ标准电视信号的工作原理及用异步ＦＩＦＯ进行电路实现的方法。     

靶场坐标转换方法

详细介绍了由发射坐标系统转为当前的极坐标的方法，测控系统常用坐标极其转换方式，通过坐标变换，取得当前方位，俯仰角参与控制过程。     

液位变送器输出的变换

介绍了液位传感器调理电路的设计及变送器在不同应用场合所需的不同的输出形式     

光域OOK到电域QPSK直接转换方法

基于光子矢量调制技术,首次提出了光域OOK到电域QPSK的直接转换方法.在提出的方案中,传送到宽带无线接入网中心站的光OOK信号无需光电转换成二进制基带信号,而是在光域直接进行转换,这样就避免了光-电-光转换,降低了系统的复杂性,并且克服了电子瓶颈问题.另外,使用了低硬件要求的PVM方案,降低了系统成本.理论与仿真分析...     

Motion segmentation by multistage affine classification

We present a multistage affine motion segmentation method that combines the benefits of the dominant motion and block-based affine modeling approaches. In particular, we propose two key modifications to a recent motion segmentation algorithm developed by Wang and Adelson (1994). 1) The adaptive k-means clustering step is replaced by a merging step, whereby the affine parameters of a block which has the smallest representation error, rather than the respective cluster center, is used to represent each layer; and 2) we implement it in multiple stages, where pixels belonging to a single motion model are labeled at each stage. Performance improvement due to the proposed modifications is demonstrated on real video frames.     

基于CPLD的二进制码转换为二-十进制(BCD)码的电路

介绍了基于Altera公司的CPLD芯片FLEXl0K，以及利用VHDL语言实现多位二进制码转换成8421BCD码的原理、设计思路和软件实现。     

Convergence behavior of affine projection algorithms

A class of equivalent algorithms that accelerate the convergence of the normalized LMS (NLMS) algorithm, especially for colored inputs, has previously been discovered independently. The affine projection algorithm (APA) is the earliest and most popular algorithm in this class that inherits its name. The usual APA algorithms update weight estimates on the basis of multiple, unit delayed, input signal vectors. We analyze the convergence behavior of the generalized APA class of algorithms (allowing for arbitrary delay between input vectors) using a simple model for the input signal vectors. Conditions for convergence of the APA class are derived. It is shown that the convergence rate is exponential and that it improves as the number of input signal vectors used for adaptation is increased. However, the rate of improvement in performance (time-to-steady-state) diminishes as the number of input signal vectors increases. For a given convergence rate, APA algorithms are shown to exhibit less misadjustment (steady-state error) than NLMS. Simulation results are provided to corroborate the analytical results     

Plane curve matching under affine transformations

It is common to use an affine transformation to approximate the plane curve matching problem under a projective transformation. The plane curve itself can be used as an identity to solve the parameters of an affine transformation. The objective of the paper is to obtain a closed form solution to the transformation parameters using lower order derivatives of a plane curve. A unique solution to the parameters of an affine transformation with up to second order derivatives is presented using differential invariants as well as the available global information. In discrete space, derivatives are obtained by numerical means. Achieving accurate numerical derivatives is always a crucial application issue. Different differentiation filters were experimented with in calculating derivatives of discrete plane curves. The ICP (iterative closest point) method was employed to improve the results obtained by the proposed invariant scheme, which was believed to be an important step towards the practical use of differential invariant schemes.     

Two-dimensional affine generalized fractional Fourier transform

As the one-dimensional (1-D) Fourier transform can be extended into the 1-D fractional Fourier transform (FRFT), we can also generalize the two-dimensional (2-D) Fourier transform. Sahin et al. (see Appl. Opt., vol.37, no. 11, p.2130-41, 1998) have generalized the 2-D Fourier transform into the 2-D separable FRFT (which replaces each variable 1-D Fourier transform by the 1-D FRFT, respectively) and the 2-D separable canonical transform (further replaces FRFT by the canonical transform). Sahin et al., (see Appl. Opt., vol.31, no.23, p.5444-53, 1998), have also generalized it into the 2-D unseparable FRFT with four parameters. In this paper, we introduce the 1-D affine generalized fractional Fourier transform (AGFFT). It has even further extended the 2-D transforms described above. It is unseparable, and has, in total, ten degrees of freedom. We show that the 2-D AGFFT has many wonderful properties, such as the relations with the Wigner distribution, shifting-modulation operation, and the differentiation-multiplication operation. Although the 2-D AGFFT form seems very complex, in fact, the complexity of the implementation will not be more than the implementation of the 2-D separable FRFT. Besides, we also show that the 2-D AGFFT extends many of the applications for the 1-D FRFT, such as the filter design, optical system analysis, image processing, and pattern recognition and will be a very useful tool for 2-D signal processing     

Difference triangle sets from affine planes

This article obtains new difference triangle sets using affine planes. Difference triangle sets have a number of interesting applications in data communications. In these applications, it is desirable to have difference triangle sets with small scopes.     

网络文件转换利器Workslink

过去我们要想通过互联网与朋友们交换文件恐怕并不是一件容易的事情，个头小一点儿的文件E-mail倒是可以轻松搞定，要是碰到10MB、8MB的大块头那就难办了。通过个人主页和网络磁盘也许可以解决这个问题，但操作起来实在是不够方便。现在有了Workslink，和朋友随时都可以通过互联网交换文件了，而且在交换文件的时候，你还可以和朋友聊聊天，这样一来各自有什么新的需求也好及时通知对方；更酷的是Workslink不但支持多任务（同时可以执行三项下载任务），而且还支持断点续传。这里将它介绍给大家。1软件的下载安装和注册Workslink是深圳…     

直接变频接收机性能分析

本文对直接变频接收机中正交矢量检测法进行了误差分析，讨论了由于接收机同相与正交两支路的增益差异、相位误差、本振泄漏及直流偏置导致其性能恶化的结果。为了实现ＧＭＳＫ信号解调，接收机中ＤＳＰ实现了调制信号的误差频谱估计、位同步恢复及译码。最后，用计算机模拟方法对该接收机性能进行了比较评价。     

A multichannel hierarchical approach to adaptive Volterra filters employing filtered-X affine projection algorithms

It is shown in this paper how the use of a recently introduced algebra, called V-vector algebra, can directly lead to the implementation of Volterra filters of any order P in the form of a multichannel filterbank. Each channel in this approach is modeled as a finite impulse response (FIR) filter, and the channels are hierarchically arranged according to the number of the filter coefficients. In such a way, it is also possible to devise models of reduced complexity by cutting the less relevant channels. This model is then used to derive efficient adaptation algorithms in the context of nonlinear active noise control. In particular, it is shown how the affine projection (AP) algorithms used in the linear case can be extended to a Volterra filter of any order P. The derivation of the so-called Filtered-X AP algorithms for nonlinear active noise controllers is easily obtained using the elements of the V-vector algebra. These algorithms can efficiently replace the standard LMS and NLMS algorithms usually applied in this field, especially when, in practical applications, a reduced-complexity multichannel structure can be exploited.