基于FPGA的基8-FFT处理器设计

 ^{提出了在现场可编程门阵列（FPGA）上实现4096点基8快速傅里叶变换（FFT）算法的设计方案。方案对蝶形器、旋转因子产生器和输入/输出接口进行了分析和优化,整个算法的流程采用了流水线的工作方式,提高了运算速度并减小了FPGA内部资源的占用。通过仿真测试,并同Matlab定点模型进行了对比。本设计方案在100MHz的时钟下,完成4096点基8-FFT运算需要2.048?滋s,完全满足高速数字信号处理的要求。}     

专用FFT实时信号处理器的硬件实现研究

在选择并具体分析FFT基4-DIT算法流程结构基础上，利用现场可编程门阵列(FPGA)设计开发了实时FFT信号处理器。全部设计方案采用VHDL描述，并在Xilinx公司的大规模可编程逻辑器件XC4085VL上实现。运行速度达到实时要求。     

专用FFT实时信号处理器的硬件实现研究

在选择并具体分析 FFT基 4—DIT算法流程结构基础上 ,利用现场可编程门阵列( FPGA)设计开发了实时 FFT信号处理器。全部设计方案采用 VHDL描述 ,并在 Xilinx公司的大规模可编程逻辑器件 XC40 85 VL上实现。运行速度达到实时要求。     

FPGA实现流水线结构的FFT处理器

针对高速实时信号处理的要求,介绍了用现场可编程逻辑阵列(FPGA)实现的一种流水线结构的FFT处理器方案.该FFT处理器能够对信号进行实时频谱分析,最高工作频率达到75 MHz.通过对采样数据进行加窗处理来减少了频谱泄漏产生的误差.为了提高FFT工作频率和节省FPGA资源,采用了由1 024点复数FFT计算2048点实数FFT的算法.此外还介绍了一种计算复数模值的近似算法.     

基于FPGA的R-64 FFT处理器的实现

快速傅里叶变换(FFT)处理器是大多数数字信号处理和数字通信系统的关键部件.文章实现了一种4 k(4 096)点改进的R-64(基-64)FFT处理器,相对于其他 R-4的流水线结构,具有占用资源更少、控制更简单等特点.该FFT处理器采用浮点数制流水线结构,能够连续处理输入数据,对R-4处理单元的改进减少了62.5%的复数加法器;该FFT处理器基于FPGA的系统时钟能够达到89 MHz,数据吞吐量为4 096 point/46 μs.     

快速傅里叶变换(FFT)的ASIC实现及现场可编辑门阵列(FPGA)验证

通过对FFT(fast fourier transformation),即快速傅里叶变换的一般算法的研究对比,确定合理可行的基2方法处理1024点FFT。在ASIC(application specific integrated circuit)专用集成电路上实现FFT硬件模块,并将该模块在FPGA(field programmable gate array)上进行原型验证。采用级联结构设计FFT模块,在尽量减小资源消耗的同时,提高FFT的运算速度。设计采用两组四个深度为256的双口RAM,乒乓结构处理,完成整个运算仅用了1 320个周期。最后用Xilinx公司的Vertex7-XC7VX690T芯片做FPGA原型验证,在时钟频率为50 MHz时,完成1 024点FFT仅用了26.2μs。     

FFT的ASIC实现及FPGA验证

通过对FFT(fast fourier transformation),即快速傅里叶变换的一般算法的研究对比,确定合理可行的基2方法处理1024点FFT。在ASIC(application specific integrated circuit)专用集成电路上实现FFT硬件模块,并将该模块在FPGA(Field Programmable Gate Array)上进行原型验证。本文采用级联结构设计FFT模块,在尽量减小资源消耗的同时,提高FFT的运算速度。设计采用两组四个深度为256的双口RAM,乒乓结构处理,完成整个运算仅用了1320个周期。最后用Xilinx公司的Vertex7-XC7VX690T芯片做FPGA原型验证,在时钟频率为50MHz时,完成1024点FFT仅用了26.2us。     

基于ASIC的128点FFT处理器的设计

所研究的芯片是128点定点FFT处理器,该处理器主要应用于超宽带无线通信系统.采用一种适合于128点快速傅里叶变换(FFT)的混合基-22/2的按频率抽取算法,并在此基础上设计一种并行运算与流水线结构相结合的硬件系统.详细描述了系统状态机的设计,最终实现了一个满足时序和设计工艺要求,达到了以下指标:工作频率66 MHz,芯片面积3.54 mm2,功耗为71.6 mW的高性能的FFT的IP处理器核.     

现代雷达中的高速FFT设计

针对FFT专用处理器无法满足现代雷达高速实时信号处理的要求,提出了四种高速FFT的设计方案。方案在分析比较各种FFT算法的基础上,兼顾速度、资源和复杂度三个方面,选用基4算法,利用CORDIC算法产生旋转因子,点数和字长均可灵活配置,工程可实现性强。设计方案的性能分析和硬件实现验证了设计方案的有效性,适应现代雷达的不同处理要求。     

基于FPGA与以太网接口的FFT数据处理系统

本文设计了一种基于FPGA和以太网口的FFT数据处理系统,可用于雷达信号的处理.FFT计算通过FPGA硬件实现,经过FFT计算以后的数据再传输给MATLAB作进一步数据处理,MATLAB与FPGA之间的通讯是基于TCP/IP协议.本设计兼顾了FPGA并行高速计算和MATLAB灵活可扩展的优点,可满足不同应用场景的要求.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that