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21.
João A. F. F. Dias Joel J. P. C. Rodrigues João N. G. Isento Jianwei Niu 《Mobile Networks and Applications》2013,18(6):867-878
Vehicular communications refer to a wide range of networks proposed for environments characterized by sparse connectivity, frequent network partitioning, intermittent connectivity, long propagation delays, asymmetric data rates, and high error rates. These environments may also be characterized by a potential non-available end-to-end path. To overcome these issues and improve the overall network performance, cooperation between network nodes must be severely considered. Nodes may cooperate by sharing their storage capacity, bandwidth, or even energy resources. However, nodes may be unwilling to cooperate due to a selfish behavior or to an intent to protect the integrity of their own resources. This selfish behavior significantly affects the functionality and performance of the network. This paper overviews the most recent advances related with cooperation on vehicular networks. It also studies the impact of different cooperation levels in the performance of Vehicular Delay-Tolerant Networks (VDTNs). It was shown that scenarios with a higher number of cooperative nodes present the best results in terms of bundle delivery delay. 相似文献
22.
新疆阿克苏河流域洪水危害比较严重,全流域有较大的河道防洪险工段50多处,主要集中在托什干河的阿合奇、上色来阿拉尔、联合渠龙口、空台、阿合雅、牙满苏,以及库玛拉克河、阿克苏河、塔里木河等处.河道洪水洪峰高,历时短,洪量小,并有突发性洪水,防洪规划的原则是以防为主,防治并重,全面规划和综合治理.近期河道防洪标准为20年一遇,一般防护工程防洪标准为5年一遇.河道防洪工程的结构形式,上游河段采用砌石混凝土结构,中游采用铅丝笼堆石和稍料三角架结构,下游及塔里木河采用混凝土井柱桩式的型式,以满足流砂游动性河床冲刷深的特点. 相似文献
23.
Brain sciences require tools that can noninvasively measure the blo-energy of Brain neurotransmitters (BNs). First we review the key models behind these tools, then to report one novel model OIIWA on otopoint's infrared image and wavelet analysis. Based on our model we provide a new investigative tool probe with 10-order wavelet coefficients corresponding to BNs in mHz level fluctuating, at last to select the medicament inducement as validity experiments for verifying the accuracy through the brain window of OIIWA. The data come from 10-subjective confirmed that our model validity be 90%. 相似文献
24.
基于数字水印的证件防伪技术 总被引:5,自引:0,他引:5
证件防伪是人们广泛关注的社会问题。本文提出了一种基于数字水印的证件防伪技术方案。该方案将水印嵌入到证件持有人的数字照片中,通过对数字照片边界的RADON变换来矫正图像在打印扫描(简称PS)过程中引入的几何失真,以证件号码为种子,产生具有良好自相关特性的随机序列作为水印信号,为提高水印的鲁棒性,采用强度自适应的DCT系数局部调整法,将水印重复多次嵌入到图像的分块DCT中频系数中。水印的提取采用相似度检测法,无需原始的图像。实验结果证明了该方案的可行性和有效性。与其他防伪技术相比,基于数字水印的证件防伪技术具有隐蔽性好,保密性强,技术容易更新,无需特殊材料和工艺,成本较低等突出的优点。 相似文献
25.
Mathew S.J. Guofu Niu Dubbelday W.B. Cressler J.D. 《Electron Devices, IEEE Transactions on》1999,46(12):2323-2332
We present the details of the fabrication, electrical characterization, and profile optimization of a SiGe pFET on silicon-on-sapphire (SOS) technology. The results show that the SiGe pFETs have higher low-field mobility (μeff), transconductance (gm), and cutoff frequency (fT) than a comparable Si pFET. At low temperature (85 K), a secondary peak is observed in the linear gm of the SiGe pFETs and is attributed to hole confinement in the SiGe channel. The effect of reducing the SOS film thickness on the mobility and short-channel performance is studied. A low-frequency noise study shows significant improvement in the SiGe pPETs over comparable Si pFETs, and is attributed to a lower sampling of interface trap density caused by the band offset at the oxide interface due to SiGe. Drain Induced Back Channel Inversion (DIBCI) is shown to occur in short gate length devices, resulting in high off-state leakage current through conduction at the back silicon-sapphire interface. The paper also discusses important optimization issues in the design of 0.25-μm gate length SiGe pFETs. A novel structure is proposed which optimizes the threshold voltage, maximizes hole confinement gate voltage range and cutoff frequency, while at the same time minimizing DIBCI to make the design usable to gate lengths as short as 0.25 μm 相似文献
26.
深圳DDV自开通后发展速度惊人,扩容工程面临许多问题。扩容方案确立后,按照网管结构优化、软件版本升级、节点机组网、时钟源、节点分流、传输测试、割接、网络优化等工作进程吩步骤完成,使得网络的结构、层次、布局更加合理,网络整体效能得以充分发挥。 相似文献
27.
Kaiyan Zhu Hongyu Wang Fanglin Niu Fengjiao Jiang 《International Journal of Wireless Information Networks》2014,21(4):317-324
In order to reduce computation complexity and latency in cooperative communication system based on fountain code, a decomposed LT codes (DLT) based cooperative transmission scheme was proposed. The scheme comprises of two layers of random encoding but only a single layer of decoding. A general decomposition technique for the decomposed LT codes construction is developed. The transmission latency for the proposed scheme was analyzed. Simulation results show that the total time consumed under the proposed scheme can be significantly reduced compared to direct transmission and conventional cooperative transmission based on LT codes in the medium to high packet erasure rate regimes. Moreover, With the increase of packet erasure rate, the advantage of the proposed scheme is more evident. 相似文献
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