Lookup Table Optimization for Sensor Linearization in Small Embedded Systems

This paper treats the problem of designing an optimal size for a lookup table used for sensor linearization. In small embedded systems the lookup table must be reduced to a minimum in order to reduce the memory footprint and intermediate table values are estimated by linear interpolation. Since interpolation introduces an estimation uncertainty that increases with the sparseness of the lookup table there is a trade-off between lookup table size and estimation precision. This work will present a theory for finding the minimum allowed size of a lookup table that does not affect the overall precision, i.e. the overall precision is determined by the lookup table entries’ precision, not by the interpolation error.

A Topology-Aware Relay Lookup Scheme for P2P VoIP System

Because of the best-effort service in Internet, direct routing path of Internet may not always meet the VoIP quality requirements. Thus, many researches proposed Peer-to-Peer VoIP systems such as SIP+P2P system, which uses relay node to relay RTP stream from the source node to the destination node and uses application-layer routing scheme to lookup the best relay nodes. The key of those systems is how to lookup the appropriate relay nodes, which we call relay lookup problem. This paper presents a novel peer relay lookup scheme based on SIP+P2P system. The main ideas are to organize the P2P network using a Cluster overlay and to use topology-aware to optimize relay selection. We introduce the mechanism in detail, and then evaluate this mechanism in NS2 network simulation environment. The results show that our scheme is scalable and can get high relay hit ratio, which confirm the feasibility of a real system. We also make comparison with traditional schemes and the results show that our scheme has good path quality.

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。

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.

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.

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。

LPR-Trie: A Fast IPv6 Routing Lookup Algorithm with Virtual Nodes

The number of IPv6 routes in todays backbone routers has grown rapidly,which has put tremendous pressure on route lookup and storage.Based on the analysis of IPv6 address prefix length and distribution characteristics,this paper proposes an IPv6 route lookup architecture called LPR-Trie.The core idea of the algorithm is to utilize more spaces and accelerate routing lookup.Moreover,we put forward the concept of virtual nodes,and leverage the link between virtual nodes and ordinary nodes to accelerate routing lookup.We provide the longest prefix routing entry(LPR)calculation algorithm to achieve the longest prefix match.The experimental results show that the virtual node mechanism increases the search speed up to 244%,and the virtual nodes have better stability by setting an appropriate keep-alive time according to the characteristics of actual traffic.This paper shows that our design improves the routing lookup speed and have better memory utilization.

Quick Web Services Lookup Model Based on Hierarchical Registration

Quick Web Services Lookup (Q-WSL) is a new model to registration and lookup of complex services in the Internet. The model is designed to quickly find complex Web services by using hierarchical registration method. The basic concepts of Web services system are introduced and presented, and then the method of hierarchical registration of services is described. In particular, service query document description and service lookup procedure are concentrated, and it addresses how to lookup these services which are registered in the Web services system. Furthermore, an example design and an evaluation of its performance are presented.Specifically, it shows that the using of attributionbased service query document design and contentbased hierarchical registration in Q-WSL allows service requesters to discover needed services more flexibly and rapidly. It is confirmed that Q-WSL is very suitable for Web services system.

Scalable Multi-Hash Name Lookup Method for Named Data Networking

A Scalable Multi-Hash( SMH) name lookup method is proposed,which is based on hierarchical name decomposition to aggregate names sharing common prefixes and multiple scalable hash tables to minimize collisions among prefixes. We take the component instead of the entire name as a key in the hash functions. The SMH method achieves lookup speeds of 21. 45 and 20. 87 Mbps on prefix table with 2 million and 3. 6 million names,respectively. The proposed method is the fastest of the four methods considered and requires 61.63 and 89.17 Mb of memory on the prefix tables with 2 million and 3. 6 million names,respectively. The required memory is slightly larger than the best method. The scalability of SMH outperforms that of the other two methods.

Hybrid Key Duplication Hashing Techniques for IP Address Lookup

This In the past decade there has been an increasing need for designs to address the time and cost efficiency issues from various computer network applications such as general IP address lookup and specific network intrusion detection. Hashing techniques have been widely adopted for this purpose, among which XOR-operation-based hashing is one of most popular techniques due to its relatively small hash process delay. In most current commonly used XOR-hashing algorithms, each of the hash key bits is usually explicitly XORed only at most once in the hash process, which may limit the amount of potential randomness that can be introduced by the hashing process. In [1] a series of bit duplication techniques are proposed by systematically duplicating one row of key bits. This paper further looks into various ways in duplicating and reusing key bits to maximize randomness needed in the hashing process so as to enhance the overall performance further. Our simulation results show that, even with a slight increase in hardware requirement, a very significant reduction in the amount of hash collision can be obtained by the proposed technique.

An architecture and algorithm for green router IP lookup

Today,backbone networks deploy a large number of devices and links.This is mainly due to both redundancy purposes for network service reliability,and resource over-dimensioning for maintaining quality of service during rush hours.Unfortunately,current routers do not have power management primitives,and have constant energy consumption independent of their actual workloads.How to implement a low power and multi-stage switch forwarding for IP lookup is a challenge in high-performance green routers design.A forwarding information base multi-stage mapping routing lookup architecture is presented,and the dynamic routing table mapping algorithm is designed to determine the optimal strides for building tree bitmap tries which lead the worst-case power consumption of the IP lookup engine to be minimized.Experimental results show that the application of reallife routing tables demonstrates that the proposed method could reduce power consumption of routing lookup by 30%.

Hardware Routing Lookup with SDRAMT

The authors present a routing lookup architecture, SDIR(SDRAM based Direct Index Routing). With pipeline and interleaving access technique, SDIR can provide scalable lookup speed from 16 7 MPPS(mega packet per second) to 133 MPPS with SDRAM running at 133MHz frequency.

A Wire-speed Routing Lookup Algorithm Based on TCAM

An internal structure of Ternary Content Addressable Memory (TCAM) is designed and a Sorting Prefix Block (SPB) algorithm is presented, which is a wire-speed routing lookup algorithm based on TCAM. SPB algorithm makes use of the parallelism of TCAM adequately, and improves the utilization of TCAM by optimum partitions. With the aid of effective management algorithm and memory image, SPB separates critical searching from assistant searching, and improves the searching effect. One performance test indicates that this algorithm can work with different TCAM to meet the requirement of wire-speed routing lookup.

ARRANGING MULTICAST FORWARDING TABLE IN CLASS SEQUENCE IN TERNARY-CAM FOR LINE-SPEED LOOKUP

PIM-SM(Protocol Independent Multicast-Sparse Mode) is a main multicast routing pro-tocol in the IPv6(Internet Protocol version 6).It can use either a shared tree or a shortest path tree to deliver data packets,consequently the multicast IP lookup engine requires,in some cases,two searches to get a correct lookup result according to its multicast forwarding rule,and it may result in a new requirement of doubling the lookup speed of the lookup engine.The ordinary method to satisfy this requirement in TCAM(Ternary Content Addressable Memory) based lookup engines is to exploit parallelism among multiple TCAMs.However,traditional parallel methods always induce more re-sources and higher design difficulty.We propose in this paper a novel approach to solve this problem.By arranging multicast forwarding table in class sequence in TCAM and making full use of the intrinsic characteristic of the TCAM,our approach can get the right lookup result with just one search and a single TCAM,while keeping the hardware of lookup engine unchanged.Experimental results have shown that the approach make it possible to satisfy forwarding IPv6 multicast packets at the full link rate of 20 Gb/s with just one TCAM with the current TCAM chip.

Power and Time Efficient IP Lookup Table Design Using Partitioned TCAMs

This paper proposes a power and time efficient scheme for designing IP lookup tables. The proposed scheme uses partitioned Ternary Content Addressable Memories (TCAMs) that store IP lookup tables. The proposed scheme enables O(1) time penalty for updating an IP lookup table. The partitioned TCAMs allow an update done by a simple insertion without the need for routing table sorting. The organization of the routing table of the proposed scheme is based on a partition with respect to the output port for routing with a smaller priority encoder. The proposed scheme still preserves a similar storage requirement and clock rate to those of existing designs. Furthermore, this scheme reduces power consumption due to using a partitioned routing table.

巧用“IF、LOOKUP函数”进行体育成绩的统计

近年来，本人在体育教学管理中，巧用Microsoft Excel工作表来科学管理学生的体育成绩，取得了显著效果。现以体质健康标准成绩的统计工作为例，浅谈应用Microsoft Excel工作表科学管理学生体育成绩档案的尝试经验，与大家共同探讨和学习。

lookup函数的应用

本文结合实例,详细介绍了通过lookup函数在ONU巡检表里添加一列的方法。

巧用Lookup函数解决名称转代码的问题

上级部门要求报送2012届毕业生的信息，信息包括毕业生的姓名、性别、身份证号、专业、生源所在地等，其中生源所在地要求用行政区域代码来表示。我们从各系获得的毕业生信息中生源所在地一栏填写的是具体的县市（区），如淄博市张店区、肃宁县等。