FAST UPDATE ALGORITHM FOR TCAM-BASED ROUTING LOOKUPS

Routing technology has been forced to evolve towards higher capacity and per port packet processing speed. The ability to achieve high forwarding speed is due to either software or hardware technology. TCAM (Ternary Content Addressable Memory) provides a performance advantage over other software or hardware search algorithms, often resulting in an order of magnitude reduction of search time. But slow updates may affect the performance of TCAM based routing lookup. So the key is to design a table management algorithm, which supports high speed updates in TCAMs. This paper presented three table management algorithms, and then compared their performance. Finally, the optimal one after comparing was given.

基于Matlab模糊控制器HDL代码的自动生成

以水箱液位控制为例,提出了一种基于Matlab的模糊控制器HDL代码自动生成方法,生成的代码可以移植到FPGA控制系统上。该方法分4个步骤:(1)利用Matlab的Fuzzy Logic工具箱设计模糊控制器。(2)将模糊控制器转换为Lookup Table的形式。(3)将制作好的控制器查找表用状态机实现。(4)用HDL Coder将状态机实现的模糊控制器翻译成HDL代码。

Accelerating Packet Classification with Counting Bloom Filters for Virtual Open Flow Switching

The growing trend of network virtualization results in a widespread adoption of virtual switches in virtualized environments. However, virtual switching is confronted with great performance challenges regarding packet classification especially in Open Flow-based software defined networks. This paper first takes an insight into packet classification in virtual Open Flow switching, and points out that its performance bottleneck is dominated by flow table traversals of multiple failed mask probing for each arrived packet. Then we are motivated to propose an efficient packet classification algorithm based on counting bloom filters. In particular, counting bloom filters are applied to predict the failures of flow table lookups with great possibilities, and bypass flow table traversals for failed mask probing. Finally, our proposed packet classification algorithm is evaluated with real network traffic traces by experiments. The experimental results indicate that our proposed algorithm outperforms the classical one in Open v Switch in terms of average search length, and contributes to promote virtual Open Flow switching performance.

体育成绩计算机评分系统的开发与应用

根据体育专业的特点,将EXCEL中的IF函数、LOOKUP函数、VLOOKUP函数综合到一起,结合VBA编辑技术开发出体育成绩计算机评分系统。该系统经过对商洛学院2008级学生期末体育成绩进行了试验性评价,取得了非常好的效果。

GPSOne精定位的最优MAR值迭代算法

在CDMA GPSOne定位环境下,影响定位成功率的2个关键指标Pn Lookup和Bs Lookup的环节包括核心网、无线侧分组网、业务平台、终端等,各个环节彼此衔接,任何环节出错均有可能引起定位结果偏差.针对原有精定位传统算法中的最大天线范围(MAR)值优化概率算法,提出了改进的MAR(NEW-MAR)值优化算法.该算法从统计分析角度切入,通过无线定位用户接入数据关联分析来优化MAR值,从而减少定位问题中人工分析挖掘过程的相关判断的工作量和失误率,并将该优化算法应用于GPSOne定位数据分析平台系统,进行智能解析基站历书(BSA)数据及指标预警.通过真实定位数据分析对比可以看出,该优化算法比传统精定位优化算法在提高Pn Lookup指标效率和减小优化时间周期上有较大的优势.投入实际运用后,大幅提高Pn Lookup成功率,确保用户GPSOne精定位精确性,较好地提升了用户定位感知的能力.

基于Java的一种新型的分布式计算环境——Jini

Jini是Sun公司的一个研究计划所取得的最新成果,此计划由Sun公司主管技术的副总裁Bill Joy所倡导,它的目的是在Java技术的基础上进一步提高其能力,向用户提供一种实用的分布式计算环境。Jini技术为多数的软件和硬件,包括几乎所有可以连接上网络的资源提供自主的网络连接。Jini的目标就是最大限度地简化对网络的操作。

A Scalable and Robust DHT Protocol for Structured P2P Network

Distributed Hash Tables (DHTs) were originated from the design of structured peer-to-peer (P2P) systems. A DHT provides a key-based lookup service similar to a hash table. In this paper, we present the detailed design of a new DHT protocol, Tambour. The novelty of the protocol is that it uses parallel lookup to reduce retrive latency and bounds communication overhead to a dynamically adjusted routing table. Tambour estimates the probabilities of routing entries' liveness based on statistics of node lifetime history and evicts dead entries after lookup failures. When the network is unstable, more routing entries will be evicted in a given period of time, and the routing tables will be getting smaller which minimize the number of timeouts for later lookup requests. An experimental prototype of Tambour has been simulated and compared against two popular DHT protocols. Results show that Tambour outperforms the compared systems in terms of bandwith cost, lookup latency and the overall efficiency.

一个提高机群文件系统吞吐率的方法及其实现

随着工作站机群系统的迅猛发展,I/O瓶颈问题也日益严重。性能优良的机群文件系统对机群系统而言至关重要。吞吐率是指在单位时间内所处理的作业数,它是评价系统性能的一个重要指标。论文提出用路径名的多成分查找来提高文件系统的创建删除吞吐率,给出并在PVFS上实现了一个路径名多成分查找方法。文章的最后对PVFS进行了优化前后的性能比较,并给出了自己的结论。

运用Excel函数快速计算高校公体成绩探析

Excel对数据的自动处理和计算有着强大功能。在体育教学管理中运用Excel表格管理学生体育成绩可以取得显著成效。

CIFLog-Smart生产测井解释系统在大庆油田的开发及应用

基于一体化网络测井处理解释软件平台(CIFLog)开发的生产测井处理解释系统,采用LookUp机制实现模块化开发,支持动态挂接功能模块,新的功能可以随时加入。系统通过缓存技术与UndoManager相结合开发了无限次的撤销恢复技术,解决了交互处理技术中误操作无法撤销的问题。通过扩展功能说明,系统支持二次开发,可扩展性较强。在大庆油田10万井次的推广应用,证明系统性能稳定,能够满足大庆油田生产测井资料解释的要求。

浅谈LOOKUP等函数的实际应用

Microsoft Excel是最优秀的电子表格软件之一,但其不仅仅是电子表格,其具有强大的数据处理和数据分析能力。在销售、工资核算等工作中经常用到多表联合查询与计算等操作,使用Excel内置的LOOKUP和VLOOKUP等函数可以产生类似操作数据库的效果,轻松地完成工作。

Enhanced Portable LUT Multiplier with Gated Power Optimization for Biomedical Therapeutic Devices

Digital design of a digital signal processor involves accurate and high-speed mathematical computation units.DSP units are one of the most power consuming and memory occupying devices.Multipliers are the common building blocks in most of the DSP units which demands low power and area constraints in the field of portable biomedical devices.This research works attempts multiple power reduction technique to limit the power dissipation of the proposed LUT multiplier unit.A lookup table-based multiplier has the advantage of almost constant area requirement’s irrespective to the increase in bit size of multiplier.Clock gating is usually used to reduce the unnecessary switching activities in idle circlet components.A clock tree structure is employed to enhance the SRAM based lookup table memory architecture.The LUT memory access operation is sequential in nature and instead of address decoder a ring counter is used to scan the memory contents and gated driver tree structure is implemented to control the clock and data switching activities.The proposed algorithm yields 20%of power reduction than existing.

Adaptive Digital Predistortion Schemes to Linearize RF Power Amplifiers with Memory Effects

To compensate for nonlinear distortion introduced by RF power amplifiers （PAs） with memory effects, two correlated models, namely an extended memory polynomial （EMP） model and a memory lookup table （LUT） model, are proposed for predistorter design. Two adaptive digital predistortion （ADPD） schemes with indirect learning architecture are presented. One adopts the EMP model and the recursive least square （RLS） algorithm, and the other utilizes the memory LUT model and the least mean square （LMS） algorithm. Simulation results demonstrate that the EMP-based ADPD yields the best linearization performance in terms of suppressing spectral regrowth. It is also shown that the ADPD based on memory LUT makes optimum tradeoff between performance and computational complexity.

刍议Lookup函数在体育成绩评分上的应用

本文通过对Lookup函数进行体育成绩评定方法的论述,使体育教师对学生体育成绩的统计从以往手工操作转向函数换算。不但解决了体育教师在体育成绩评定上效率不高、容易出错的问题,并且对当前体育教师的办公现代化有积极地促进作用。

Robust Watermarking with Kernels-Alternated Error Diffusion and Weighted Lookup Table in Halftone Images

A halftone watermarking method of high quality, robustness, and capacity flexibility is presented in this paper. An objective halftone image quality evaluation method based on the human visual system obtained by a least-mean-square algorithm is also introduced. In the encoder, the kernels-alternated error diffusion （KAEDF） is applied. It is able to maintain the computational complexity at the same level as ordinary error diffusion. Compared with Hel-Or using ordered dithering, the proposed KAEDF yields a better image quality through using error diffusion. We also propose a weighted lookup table （WLUT） in the decoder instead of lookup table （LUT）, as proposed by Pei and Guo, so as to achieve a higher decoded rate. As the experimental results demonstrate, this technique is able to guard against degradation due to tampering, cropping, rotation, and print-and-scan processes in error-diffused halftone images.

Using bidirectional links to improve peer-to-peer lookup performance

Efficient lookup is essential for peer-to-peer networks and Chord is a representative peer-to-peer lookup scheme based on distributed hash table (DHT). In peer-to-peer networks, each node maintains several unidirectional application layer links to other nodes and forwards lookup messages through such links. This paper proposes use of bidirectional links to improve the lookup performance in Chord. Every original unidirectional link is replaced by a bidirectional link, and accordingly every node becomes an anti-finger of all its finger nodes. Both theoretical analyses and experimental results indicate that these anti-fingers can help improve the lookup performance greatly with very low overhead.

Real-Time Implementation for Reduced-Complexity LDPC Decoder in Satellite Communication

In this paper,it has proposed a realtime implementation of low-density paritycheck(LDPC) decoder with less complexity used for satellite communication on FPGA platform.By adopting a(2048.4096)irregular quasi-cyclic(QC) LDPC code,the proposed partly parallel decoding structure balances the complexity between the check node unit(CNU) and the variable node unit(VNU) based on min-sum(MS) algorithm,thereby achieving less Slice resources and superior clock performance.Moreover,as a lookup table(LUT) is utilized in this paper to search the node message stored in timeshare memory unit,it is simple to reuse and save large amount of storage resources.The implementation results on Xilinx FPGA chip illustrate that,compared with conventional structure,the proposed scheme can achieve at last 28.6%and 8%cost reduction in RAM and Slice respectively.The clock frequency is also increased to 280 MHz without decoding performance deterioration and convergence speed reduction.

A Discrete Newton's Method for Gain Based Predistorter

Gain based predistorter (PD) is a highly effective and simple digital baseband predistorter which compensates for the nonlinear distortion of PAs. Lookup table (LUT) is the core of the gain based PD. This paper presents a discrete Newton’s method based adaptive technique to modify LUT. We simplify and convert the hardship of adaptive updating LUT to the roots finding problem for a system of two element real equations on athematics. And we deduce discrete Newton’s method based adaptive iterative formula used for updating LUT. The iterative formula of the proposed method is in real number field, but secant method previously published is in complex number field. So the proposed method reduces the number of real multiplications and is implemented with ease by hardware. Furthermore, computer simulation results verify gain based PD using discrete Newton’s method could rectify nonlinear distortion and improve system performance. Also, the simulation results reveal the proposed method reaches to the stable statement in fewer iteration times and less runtime than secant method.

Excel中的Lookup函数

Excel提供了多种表间搜索的命令和方式,其中最常用的当数LOOKUP,VLOOKUP,HLOOKUP,和多重IF流程命令这几种方式。很难说这几种方式当中哪种效果更好,哪种更适合你的情况,更何况在大型数据表格的搜索进程中我们往往要混合使用这几种方法才能达到最佳效果。本文在此仅就EXCEL中进行搜索的三种方法进行介绍,希望对你能有所帮助。

低压配电系统自动选型研究

通过低压配电系统负荷计算书,结合Excel办公软件自动选择低压配电系统中各元件参数及型号,从而减少设计人员的重复繁琐工作,将低压配电系统按通用标准自动选择设计出来,为设计人员争取更多时间优化项目。在建筑电气设计过程中,由于各种原因,各回路的负荷容量改动较多,自动选择通过改变负荷联动所有关联的设计参数,进一步提高了设计的效率。