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硬X射线暂现源的偶发性星风增强模型  [PDF]
宓国柱
空间科学学报 , 1982,
Abstract: 本文讨论了硬X射线暂现源的偶发性星风增强模型,计算了爆发期间光学光度的变化,解释了光学光度和X射线光度变化的不同步现象,结果表明这种模型可能是比较合理的。
REVIEW OF CORDIC ARCHITECTURES
T.SUBHA SRI,K.SESHU KUMAR,R. MUTTAIAH
International Journal of Engineering and Technology , 2013,
Abstract: Coordinate Rotation Digital Computer (CORDIC) first introduced by volder and Jack E. The consequence is lies on reality i.e., Small operations of shift-add and it also perform numerous computation operations. CORDIC used in various applications like image and signal processing, robotics systems and also communication systems and technical totalling. In this paper we presenting a brief outline and also growth in the CORDIC algorithm and architectures.
CORDIC Architectures: A Survey
B. Lakshmi,A. S. Dhar
VLSI Design , 2010, DOI: 10.1155/2010/794891
Abstract: In the last decade, CORDIC algorithm has drawn wide attention from academia and industry for various applications such as DSP, biomedical signal processing, software defined radio, neural networks, and MIMO systems to mention just a few. It is an iterative algorithm, requiring simple shift and addition operations, for hardware realization of basic elementary functions. Since CORDIC is used as a building block in various single chip solutions, the critical aspects to be considered are high speed, low power, and low area, for achieving reasonable overall performance. In this paper, we first classify the CORDIC algorithm based on the number system and discuss its importance in the implementation of CORDIC algorithm. Then, we present systematic and comprehensive taxonomy of rotational CORDIC algorithms, which are subsequently discussed in depth. Special attention has been devoted to the higher radix and flat techniques proposed in the literature for reducing the latency. Finally, detailed comparison of various algorithms is presented, which can provide a first-order information to designers looking for either further improvement of performance or selection of rotational CORDIC for a specific application.
P-CORDIC: A Precomputation Based Rotation CORDIC Algorithm  [cached]
Kuhlmann Martin,Parhi Keshab K
EURASIP Journal on Advances in Signal Processing , 2002,
Abstract: This paper presents a CORDIC (coordinate rotation digital computer) algorithm and architecture for the rotation mode in which the directions of all micro-rotations are precomputed while maintaining a constant scale factor. Thus, an examination of the sign of the angle after each iteration is no longer required. The algorithm is capable to perform the CORDIC computation for an operand word-length of 54 bits. Additionally, there is a higher degree of freedom in choosing the pipeline cutsets due to the novel feature of independence of the iterations and in the CORDIC rotation.
CORDIC Based FFT for Signal Processing System  [PDF]
KARTHICK S,PRIYA P,VALARMATHY S
International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering , 2013,
Abstract: A pure CORDIC based architecture is used to calculate the FFT in signal processing. Though many hardware efficientalgorithms exist, but these are not generally known due to the dominance of software systems. Among these algorithm isa set of shift and add operation collectively known as CORDIC used for computing a wide range of function includingcertain hyperbolic, trigonometric, logarithmic and linear functions. The CORDIC is used in many digital signalsprocessing application in which FFT is designed in this. The performance of this approach can compete with theordinary MAC based FFT. With the presented pure CORDIC based FFT it is now possible to replace the mainprocessing blocks of the WLAN and UMTS baseband by this programmable architecture.
The Extraordinary SVD  [PDF]
Carla D. Martin,Mason A. Porter
Physics , 2011,
Abstract: The singular value decomposition (SVD) is a popular matrix factorization that has been used widely in applications ever since an efficient algorithm for its computation was developed in the 1970s. In recent years, the SVD has become even more prominent due to a surge in applications and increased computational memory and speed. To illustrate the vitality of the SVD in data analysis, we highlight three of its lesser-known yet fascinating applications: the SVD can be used to characterize political positions of Congressmen, measure the growth rate of crystals in igneous rock, and examine entanglement in quantum computation. We also discuss higher-dimensional generalizations of the SVD, which have become increasingly crucial with the newfound wealth of multidimensional data and have launched new research initiatives in both theoretical and applied mathematics. With its bountiful theory and applications, the SVD is truly extraordinary.
CORDIC算法的优化及实现  [PDF]
刘小宁,谢宜壮,陈禾,闫雯,陈冬
北京理工大学学报 , 2015, DOI: 10.15918/j.tbit1001-0645.2015.11.012
Abstract: 为提高坐标旋转数字计算(CORDIC)算法的精度并降低硬件资源消耗,对CORDIC算法收敛性以及旋转序列的选取进行了研究.针对圆周系统下CORDIC算法的角度覆盖范围、硬件资源和运算精度等问题提出了进一步的优化措施.利用经过优化后的CORDIC算法,在FPGA中实现了流水线结构的正余弦函数和反正切函数,并把运算精度与硬件资源消耗与XilinxIP核进行了比较.比较结果表明该优化算法在提高运算精度的同时能够有效降低硬件资源消耗.
Design and Simulation of Cordic Co-Processor and Its Application in Avionics  [PDF]
Chowdi Ravitej,,Elphesj Churchill,,Kishore Sonti
International Journal of Innovative Technology and Exploring Engineering , 2013,
Abstract: A technique is allocated going to discuss the application of cordic algorithm in avionics. Actually here the process is dealing with avionics so, the smart application of cordic algorithm is in ARM processor. In GNSS (global navigation satellite system) receiver make use of ARM processor floating point instruction (FPI) are there to calculate the FPI. It contains floating point unit (FPU). So, to make easy calculation in FPU have implemented cordic algorithm here cordic calculation means calculating trigonometric values. In this way FPU has implemented. Here trigonometric values means sin, cosine, tangent after getting tangent values have to see timing response of the binary output. So, in navigation system. Now, accurate signals have been sensed. Without any critical path delay then automatically speed will increase delay will reduce this is more advantage in avionics system. For floating point addition, exponent matching and shifting of 24 bit mantissa and sign logic are coded in behavioral style. Prototypes are implemented on Xilinx vertex-4 and 5. By designing pipelining in cordic and wave pipelining in cordic is implemented in cordic algorithm to reduce the timing response in the navigation system.
低消耗免查找表CORDIC算法  [PDF]
姚亚峰,邹凌志,王巍,钟梁
- , 2017, DOI: 10.11918/j.issn.0367-6234.201704019
Abstract: 为减少传统流水线型CORDIC(Coordinate Rotation Digital Computer)算法的硬件资源消耗和输出时延,在包含查找表的三阶段CORDIC算法实现基础上,提出一种免去查找表环节的CORDIC算法实现方法.提出的改进算法直接使用四次移位相加的迭代运算替换查找表结构从而显著降低寄存器消耗,同时通过合并迭代降低迭代次数进而有效减少最大输出时延,并综合运用角度二极化重编码(Binary To Bipolar Recoding, BBR)方法和角度区间折叠技术保证了输出精度.使用Verilog HDL语言在ISE14.2软件平台上对三种算法进行具体实现,利用XST工具对其进行综合,并通过MATLAB建模计算得到算法的正余弦值输出误差.仿真实验结果表明:在输出位宽均设置为16位的情况下,免查找表CORDIC算法能够有效地输出正余弦值;与传统流水线型算法相比,免查找表算法的寄存器资源消耗减少大约74.42%,计算所需的时钟周期降低68.75%,其输出精度也有明显改善;与三阶段算法相比,免查找表算法的寄存器消耗减少大约43.3%.本文提出的免查找表CORDIC算法具有实时性强、输出精度高、硬件资源消耗少等优势,更适用于高速实时的现代数字通信系统应用.
In order to reduce the hardware resource consumption and output delay in the conventional pipeline CORDIC (Coordinate Rotation Digital Computer) algorithm, a LUT-omitted CORDIC algorithm is proposed on the basis of the three-stage CORDIC with look-up table (LUT). The proposed new algorithm adopts 4 iterations of shifter-adder instead of LUT to reduce the register consumption apparently, and merges some iterations to decrease the output delay effectively, and guarantees the output resolution by using a combination of Binary to Bipolar Recoding (BBR) and angle range folding. The improved algorithm is specifically implemented using Verilog HDL on ISE 14.2 software platform and synthesized using XST tools, and is modeled to analyze the output errors through MATLAB. Simulation experiment results show that the register resource consumption of the new algorithm, producing sine/cosine effectively, is reduced by about 74.42% compared with the conventional one, while the output width is set to 16 equally. The computing clock periods are decreased by 68.75%, and the resolution is also improved obviously. Compared with the three-stage algorithm, the consumption of register is reduced by about 43.3%. The proposed algorithm has some advantages such as brilliant real-time performance, high resolution, and low consumption. And it is more applicable for modern digital communication systems that demand for high speed and promising real-time performance.
Cordic based algorithms for software defined radio (SDR) baseband processing  [PDF]
B. Heyne,J. G?tze
Advances in Radio Science : Kleinheubacher Berichte , 2006,
Abstract: This paper presents two Cordic based algorithms which may be used for digital baseband processing in OFDM and/or CDMA based communication systems. The first one is a linear least squares based multiuser detector for CDMA incorporating descrambling and despreading. The second algorithm is a pure Cordic based FFT implementation. Both algorithms can be implemented using solely Cordic based architectures (e.g. coprocessors or ASIPs). The algorithms exactly fit the needs of a multistandard terminal as they both are freely parameterizable. This regards to the accuracy of the results as well as to the parameters of the performed function (e.g. size of the FFT).
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