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Many recent studies have convincingly demonstrated that network traffic exhibits a noticeable self-similar nature, which has a considerable impact on network performance, and most studies of optical burst switching (OBS) networks are under a fundamental assumption that full wavelength conversion is available throughout the network. In practice, however, economic and technical considerations are likely to dictate a more limited and sparse deployment of wavelength converters in the optical network. Therefore, we present a novel scheme for OBS networks, called logical cascaded private subnet (LCPN) with start wavelength assignment policy. We define the concept of canoe relative to cluster in self-similar traffic, and introduce a new device named payload segregator at the edge node as a gateway to the core node in OBS Networks. According to the changes in the edge node framework, we put forward the concept of cluster private subnet and canoe private subnet in the core node correspondingly. A new start wavelength assignment policy is proposed for the absence of (full) wavelength conversion capabilities in the core node of OBS Networks. The performance study indicates that, our new scheme is robust under self-similar traffic and wavelength continuity constraint. 相似文献
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In this paper we propose a new protocol called time-space label switching protocol (TSL-SP) in optical burst switching (OBS), and define the terms time-space label (TSL) and time-space routing (TSR). An important concept of response time is introduced in the time label mechanism. The TSL-SP is a new technology that can quickly and efficiently forward data with a label on the optical networks. A two-dimension label switched path (TD-LSP) can be set up, that is maintained and deleted by the TSL-SP. For clearly illuminating the operation principles of the TSL-SP, we propose a new approach of orthogonal time-space coordinates in which the vertical coordinate is the space label and the horizontal coordinate is the time label. The proposed TD-LSP can dramatically reduce the routing failure probability and greatly improve the link network efficiency compared with other signaling protocols. Moreover, we define the time-space label control plane that can achieve the higher efficiency. When the TSL-SP is applied to networks, switching performance can be improved by two orders compared to the switching performance with the conventional OBS signaling protocols. The fundamental goal of TSL-SP is to band the signaling and routing functions together closely. Also, the TSL-SP can reduce the complexity of the network, support automatic service offering, and provide traffic engineering. 相似文献
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Junsheng Chang Zhengbin Pang Weixia Xu Huaimin Wang Gang Yin 《The Journal of supercomputing》2014,69(3):1382-1409
In peer-to-peer (P2P) systems, peers often must interact with unknown or unfamiliar peers without the benefit of trusted third parties or authorities to mediate the interactions. Trust management through reputation mechanism to facilitate such interactions is recognized as an important element of P2P systems. It is, however, faced by the problems of how to stimulate reputation information sharing and honest recommendation elicitation. This paper presents an incentive compatible reputation mechanism for P2P systems. It has two unique features: (1) a recommender’s trustworthiness and level of confidence about the recommendation is considered for a more accurate calculation of reputations and fair evaluation of recommendations. (2) Incentive for participation and honest recommendation is implemented through a fair differential service mechanism. It relies on peer’s level of participation and on the recommendation credibility. Theoretic analysis and simulation show that the reputation mechanism we propose can help peers effectively detect dishonest recommendations in a variety of scenarios where more complex malicious strategies are introduced. Moreover, it can also stimulate peers to send sufficiently honest recommendations. The latter is realized by ensuring that active and honest recommenders, compared to inactive or dishonest ones, can elicit the most honest (helpful) recommendations and thus suffer the least number of wrong trust decisions. 相似文献
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在星载方位多通道SAR斜视模式下,方位斜视角度和运动目标的速度分别导致回波多普勒频谱发生2次混叠和通道失衡,影响运动目标方位多通道信号重建.针对该问题,该文提出一种适用于多通道斜视模式下的运动目标的重建方法.首先通过方位向去斜预处理消除了斜视导致的2次多普勒混叠,然后通过修正的多通道重建矩阵来解决目标速度导致的通道失衡.此外,该文还研究了通道冗余情况下的杂波抑制能力,分析了估计速度误差带来的残余相位误差,给出了一种星载方位多通道SAR斜视模式下的运动目标速度快速估计搜索方法.最后,通过点目标仿真验证了方法的有效性. 相似文献
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本文阐述了WCDMA无线网络规划的整体流程,并重点分析了WCDMA系统中容量与覆盖的关系及平衡二者的流程. 相似文献
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Synthesis and adhesion properties of waterborne polyurethane dispersions with long‐branched aliphatic chains 下载免费PDF全文
In this study, a series of waterborne polyurethanes (WPUs) with different contents of long‐branched aliphatic chains were synthesized through variation of the amount of diol chain extender trimethylol propane monooleate (TMPM). The effects of the TMPM content on the adhesion properties of the WPUs were investigated in terms of their surface tension, interfacial tension, contact angle, and adhesion strength. Fourier transform infrared and 1H‐NMR spectra demonstrated the successful incorporation of TMPM into the polyurethanes. An increase in the TMPM content produced decreases in the surface tension of the WPUs and the interfacial tension and contact angle between the WPUs and plastic films. This indicated that the wetting properties of the WPUs on the plastic films was improved. The improved wettability enhanced the adhesion strength of the WPUs, and this showed that the long‐branched aliphatic chains could effectively improve the adhesion performance of the WPUs on the plastic films. Moreover, TMPM, with its hydrophobic aliphatic chains, increased the hydrophobicity and thermal stability of the WPU films. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41688. 相似文献
8.
Industrial wood is typically dried artificially after felling. The drying process is often very lengthy and consumes a large amount of energy, however, and inappropriate drying schedule can cause defects in the wood. Pretreatments such as ultrasound show the potential to reduce wood drying time without impacting quality. This study investigated the influence of ultrasound pretreatment on vacuum drying behavior, hydroxyl content, and microstructural properties of fast-growing wood samples. Pretreatments were performed at ultrasound intensity of 10 W cm?2 and frequencies of 28 and 40 kHz, respectively, for 30, 60, and 90 min, respectively, then pretreated samples were dried at 40°C temperature under absolute pressure of 0.08 MPa. Results showed that ultrasound pretreatment did shorten the wood vacuum drying time, increase effective water diffusivity, open water channels, decompose wood extractives, and decrease hydroxyl content. In effect, ultrasound pretreatment can be applied to successful reduce wood drying time. 相似文献
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Recovery and characterization of lignin from alkaline straw pulping black liquor: As feedstock for bio‐oil research 下载免费PDF全文
Conversion of lignin derived from lignocellulosic biomass to bio‐oil has the promising potential to significantly reduce petroleum dependence. For that purpose, it is necessary to search for a low‐cost lignin source. In this study, lignin sample was separated from straw pulping black liquor by HCl‐precipitation, followed by extraction with a mixture of dioxane and water. The content of lignin in the total black liquor solid reached up to 34.8%, determined by UV spectroscopy, and the yield could account for 74.4% of the total lignin composition. The structure of lignin was investigated by various spectroscopic techniques such as FTIR, 1H‐NMR, XRD, and XPS. The structural analysis revealed that recovered lignin preserved basic lignin structure, but had relatively lower amount of β‐O‐4 linkages. The molecular weights were studied through THF‐eluted GPC showing that separated lignin had the low Mn, which was favorable for the full degradation process during conversion of lignin to bio‐oil. Therefore, a feasible solution for effective utilization of lignin in straw pulping black liquor as feedstock for bio‐oil was proposed in the study. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42057. 相似文献