排序方式: 共有40条查询结果,搜索用时 343 毫秒
1.
Multimedia Tools and Applications - Since Noar and Shamir introduced visual cryptography scheme (VCS), the cheating problem of VCS has absorbed much attention of scholars. The current researches on... 相似文献
2.
3.
4.
Shu-Tao Xia Fang-Wei Fu 《Communications Letters, IEEE》2006,10(5):363-365
In this letter, we study the minimum pseudo-codewords of low-density parity-check (LDPC) codes under linear programming (LP) decoding. We show that a lower bound of Chaichanavong and Siegel on the pseudo-weight of a pseudo-codeword is tight if and only if this pseudo-codeword is a real multiple of a codeword. Using this result we further show that for some LDPC codes, e.g., Euclidean plane and projective plane LDPC codes, there are no other minimum pseudo-codewords except the real multiples of minimum codewords. 相似文献
5.
Shu-Tao Xia Fang-Wei Fu 《Communications Letters, IEEE》2006,10(5):381-383
In this letter, the stopping sets and stopping distance of finite geometry LDPC (FG-LDPC) codes are studied. It is known that FG-LDPC codes are majority-logic decodable and a lower bound on the minimum distance can be thus obtained. It is shown in this letter that this lower bound on the minimum distance of FG-LDPC codes is also a lower bound on the stopping distance of FG-LDPC codes, which implies that FG-LDPC codes have considerably large stopping distance. This may explain in one respect why some FG-LDPC codes perform well with iterative decoding in spite of having many cycles of length 4 in their Tanner graphs. 相似文献
6.
Rei-Heng Cheng Chang Wu Yu Tung-Kuang Wu Fang-Wei Jin 《Wireless Personal Communications》2013,68(4):1493-1523
One of the fundamental issues of wireless sensor networks is that an event can be detected by some sensor nodes and delivered to the query devices. This kind of queries and events can be happening anytime and anywhere. Due to the battery constrained nature of sensor nodes, it is important to design routing protocols that are efficient and power saving. In this work, we propose a new routing protocol, the small-world routing protocol (SWRP), which is at the same time a generalization of both flooding and rumor routing and can be operating in between both extremes. With the idea originating from the small-world theory, the proposed protocol finds paths between the queries and events through recurrent propagations of strong and weak links. The operation of the protocol is simple, flexible and requires not much computational power. The SWRP may also minimize the pass-over problem, which occurs when a query agent passes over an event agent even though the two lines cross each other and thus prevents a query from finding the event. It has been shown that by increasing the number of strong links of the SWRP within a controlled area, we may be able to reduce the occurrences of pass-over. Accordingly, the proposed SWRP may achieve much better successful rate in routing as well as cut the number of hop-count at the same time. In particular, our simulation results show that with approximately the same routing overhead (in term of number of routing messages), our protocol may achieve up to 22% more in success rate and 10-hop less in average path length. To reach a 100% successful routing rate, our protocol may save up to 41.2% additional routing overhead as compared to the rumor routing. Most important of all, the SWRP makes the improvements without sacrificing the power consumption of each individual sensor node as the average inter-hop distance for discovered routing paths does not increase as a result of shorter path length. 相似文献
7.
8.
针对权重信息完全未知的多属性决策问题,利用超立方体分割的思想,给出数值模拟决策方法.该方法易于在计算机上实现,并且利用该方法得到的评价结果客观可靠,不具有主观随意性.最后,给出一个实际应用的例子. 相似文献
9.
基于STC89C52单片机设计电风扇的控制系统,首先进行总体设计,然后进行硬件电路设计与软件设计,最后试制出电风扇原型机.设计的电风扇能根据环境温度自动调节风速大小,能模拟自然风、阵风、睡眠风等,还具有摇控、能根据人来人往来开启或关闭等智能功能.实践证明该电风扇工作稳定且成本低,具有一定的推广应用价值. 相似文献
10.
Yuan Luo Fang-Wei Fu Han Vinck A.J. Wende Chen 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2003,49(11):3010-3016
A constant-composition code is a special constant-weight code under the restriction that each symbol should appear a given number of times in each codeword. In this correspondence, we give a lower bound for the maximum size of the q-ary constant-composition codes with minimum distance at least 3. This bound is asymptotically optimal and generalizes the Graham-Sloane bound for binary constant-weight codes. In addition, three construction methods of constant-composition codes are presented, and a number of optimum constant-composition codes are obtained by using these constructions. 相似文献