共查询到20条相似文献,搜索用时 15 毫秒
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The notion of a logically routed network was developed to overcome the bottlenecks encountered during the design of a large purely optical network. In the last few years, researchers have proposed the use of torus. Perfect shuffle, hypercube, de Bruijn graph, Kautz graph, and Cayley graph as an overlay structure on top of a purely optical network. All these networks have regular structures. Although regular structures have many virtues, it is often difficult in a realistic setting to meet these stringent structural requirements. In this paper, we propose generalized multimesh (GM), a semiregular structure, as an alternate to the proposed architectures. In terms of simplicity of interconnection and routing, this architecture is comparable to the torus network. However, the new architecture exhibits significantly superior topological properties to the torus. For example, whereas a two-dimensional (2-D) torus with N nodes has a diameter of Θ(N0.5), a generalized multimesh network with the same number of nodes and links has a diameter of Θ(N0.25). In this paper, we also introduce a new metric, flow number, that can be used to evaluate topologies for optical networks. For optical networks, a topology with a smaller flow number is preferable, as it is an indicator of the number of wavelengths necessary for full connectivity. We show that the flow numbers of a 2-D torus, a multimesh, and a de Bruijn network, are Θ(N1.5), Θ(N1.25), and Θ(N log N), respectively, where N is the number of nodes in the network. The advantage of the generalized multimesh over the de Bruijn network lies in the bet that, unlike the de Bruijn network, this network can be constructed for any number of nodes and is incrementally expandable 相似文献
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Knockaert L. Lippens G. De Zutter D. 《IEEE transactions on circuits and systems. I, Regular papers》2006,53(7):1544-1555
A new bandlimited two-parameter Kautz basis, for application to reduced-order modeling (ROM), is proposed. It is derived from the original Kautz basis by means of a pertinent rational frequency transformation, and is shown to be orthonormal over a narrowband frequency interval. By means of obliquely projecting a general Mth-order state space transfer function onto this bandlimited Kautz basis, we obtain a new ROM technique, which does not belong to the class of Krylov methods, but to the rather more general family of oblique projection techniques. Pertinent features of the new method are the reduction in computational effort and the fact that a more efficient ROM approach is obtained by focusing on the frequency band under scrutiny. The robustness and accuracy of the new method is illustrated by applying it to a number of benchmark examples. 相似文献
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I. Pastoriza–Santos A. Sánchez–Iglesias F. J. García de Abajo L. M. Liz–Marzán 《Advanced functional materials》2007,17(9):1443-1450
The sensitivity of localized surface plasmon resonances with respect to changes in the refractive index of the surrounding medium is measured for small (< 60 nm side length) and large (ca. 150 nm side length) regular gold nanodecahedra (pentagonal bipyramids), and compared to rigorous solutions of Maxwell's equations for bicones based upon the boundary element method (BEM). Small particles are prepared through ultrasound‐induced reduction of HAuCl4 by N,N‐dimethylformamide (DMF) on presynthesized penta‐twinned Au seeds, whereas large decahedra are grown using smaller ones as seeds. Excellent agreement between experimental and calculated spectra is found for dispersions and monolayers of particles in different solvents, as well as for the effect of uniform silica layers of various thicknesses grown on them. These results are expected to be useful for the development of novel biosensors. 相似文献
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本文描述了在我们开发的二维版图压缩器中使用的约束图模型,它按照版图中各掩模层和派生层在电学特性或设计规则上的互相影响,把版图划分成若干个逻辑平面。先由各逻辑平面生成相应的约束图,再根据各逻辑平面生成的子约束图形成整个版图的约束图。并利用改进的垂直平面扫描算法生成由约束图模型定义的约束图。 相似文献
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The number of stations attached to a single optical passive star is limited by current state of the art in optical technology. Also, the wavelength range of tunable optical transceivers is limited by current technology. Many high performance computing applications require the use of large size regular topologies for communication between computing nodes. Scalability of passive star networks built with these two limitations becomes an important issue for building larger networks. This is the subject of our study in this paper. In a previous related work we explored the design issues for networks built on a single passive star employing transceivers of a limited tuning range. Here we extend that study by considering the problem of connecting several optical passive stars, each embedded with a given virtual topology, to create larger aggregate networks. The design issues are analyzed and a number of design rules are proposed for building such aggregate networks. We study the scalability of embedded optical passive stars by considering the most commonly employed virtual topologies—complete graph, mesh and hypercube. 相似文献
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微结构聚合物光纤化学修饰的pH值传感探头 总被引:1,自引:0,他引:1
为了拓展微结构聚合物光纤(MPOF)在化学传感领域内的应用研究以及对MPOF孔道内壁功能化修饰技术的深入研究, 首先对36孔的MPOF孔道内壁进行酸催化水解处理, 随后采用化学键合的方式将荧光探针曙红通过偶联剂负载于MPOF孔道内壁, 从而制成用于pH值测定的传感探头。该传感探头被修饰后的多个孔道可以容纳微量的待测溶液, 待测物与孔道内壁的荧光探针作用后, 光信号将可以沿光纤传输, 并被检测。整个化学反应的传感过程是在孔道内进行的, 传导的光束能够和敏感材料相重叠, 利于微量分析同时避免了对敏感膜的损坏。实验结果显示pH值在2.0~4.4范围内与荧光强度呈线性关系, 该传感探头的重现性良好, 并且采用此修饰方法制备的MPOF传感探头对于荧光探针的固定性比较好, 无明显泄漏。 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》1987,33(5):721-723
Using the Goppa codes as outer codes in a construction devised by Kautz and Singleton, an improvement of the Gilbert bound for constant weight codes is obtained. 相似文献
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《Microwave Theory and Techniques》1980,28(3):235-238
Dispersion characteristics and radiation fields of an optical stripline waveguide radiating into free space are calculated. The waveguides are fabricated as multiple layers of differing dielectric materials. A top layer is etched to form a "cap" with an effective waveguide in a layer below the cap. Confinement of the fields to the waveguide is obtained in the vertical direction by dielectric discontinuities, while lateral confinement occurs because of spatial interference of a continuum of plane waves. The radiation field of the fundamental mode in a plane perpendicular to the waveguide layers is characterized by the layer widths and index discontinuities. Beamwidths of the fundamental mode in the plane parallel to the dielectric layers are developed in terms of the waveguide parameters. Values of these parameters which yield the best optical confinement under the stripe can be obtained. 相似文献
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The augmented UD identification (AUDI) method is used to simultaneously estimate parameters of all 1 to Nth-order discrete orthonormal function models in one computational step. This method is tested on different types of orthonormal functions such as the Laguerre, Kautz, FIR, and Markov-Laguerre models 相似文献
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Power law random graphs with infinite variance degree distribution are shown to possess a fascinating architecture with a softly hierarchical core network. The core provides loglog-scalable connectivity properties for the whole giant component of the graph. The core is also shown to be robust against attacks to the very heart of the architecture, the top layers of the hierarchy. The structure's similarities and dissimilarities with the Internet's autonomous system graph are discussed. The main significance of a soft hierarchy is seen, however, in the context of structural aspects of large future networks. 相似文献
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I. Pastoriza–Santos A. Sánchez–Iglesias F. J. García de Abajo L. M. Liz–Marzán 《Advanced functional materials》2007,17(9)
As reported on p. 1443 by Isabel Pastoriza‐Santos and Luis M. Liz‐Marzán, the high sensitivity of localized surface plasmon resonances towards changes in the refractive index of the surrounding medium for regular gold nanodecahedra render them strong candidates for (bio)sensing applications. Whereas a monolayer of decahedra deposited on a glass slide looks pink in air, it turns blue when immersed in isopropanol. The sensitivity of localized surface plasmon resonances with respect to changes in the refractive index of the surrounding medium is measured for small (< 60 nm side length) and large (ca. 150 nm side length) regular gold nanodecahedra (pentagonal bipyramids), and compared to rigorous solutions of Maxwell's equations for bicones based upon the boundary element method (BEM). Small particles are prepared through ultrasound‐induced reduction of HAuCl4 by N,N‐dimethylformamide (DMF) on presynthesized penta‐twinned Au seeds, whereas large decahedra are grown using smaller ones as seeds. Excellent agreement between experimental and calculated spectra is found for dispersions and monolayers of particles in different solvents, as well as for the effect of uniform silica layers of various thicknesses grown on them. These results are expected to be useful for the development of novel biosensors. 相似文献
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本文研究图频域内的多通道语音增强,利用图信号处理理论(GSP)构建一种时间-空间维度的联合图拓扑结构,在此基础上设计增强算法进行多通道语音消噪。具体而言,基于输入阵列某个麦克风输入帧间语音顶点信号的时间相关关系,构造时间维度上的一种图拓扑结构;同时针对多通道含噪语音,根据各通道接收信号的空间相关关系,构造空间维度上的一种图拓扑结构。基于时间和空间二种图拓扑构成的联合图拓扑结构,采用图频域内的最小方差无失真响应(MVDR)增强算法,进行多通道语音增强。仿真实验结果表明,在平均客观语音质量评估(PESQ)得分和平均拓展短时客观可懂度(ESTOI)评价指标下,本文所提出的基于联合图拓扑结构的MVDR波束形成(JG-MVDR)方法都优于常规图MVDR波束形成(GMVDR)方法和基于复高斯混合模型的MVDR波束形成(CGMM-MVDR)方法。 相似文献
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《Microwave Theory and Techniques》1975,23(1):57-70
A tutorial survey of recent work on optical waveguide modulators in electrooptic, acoustooptic, and magnetooptic materials is presented. Methods for realizing waveguiding layers in modulating materials and various modulator configurations are considered. 相似文献
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We consider maximal-length linear congruential sequences generated using a simple recursion to generate the bipartite graph of a low-density parity-check (LDPC) code. The main advantage is that the graph structure of the codes (edge connections) can be generated using a recursion, rather than having to store the graph connections in memory, which facilitates hardware implementation of the decoder. For this class of codes, sufficient conditions on the recursion parameters are derived, such that regular LDPC codes can be constructed with no cycles of length four or less. Simulation results show that these codes provide almost the same performance of a constrained pseudorandom construction that explicitly avoids cycles of length less than or equal to four. 相似文献
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一种设计光二分路器分光比的简便方法 总被引:8,自引:3,他引:5
对星形光纤传输网络中的光二分路器分光比的设计作了分析和研究,得到一种设计光二分路器分光比的简便方法--查表法和曲线图解法,并对相关函数关系及其曲线特征与规律作了分析,得出了5条结论. 相似文献
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本文引用文献[7]提出的多参数纤端光场场强分布表达式作为目标函数,结合实验中得到的实测数据,利用数据处理方法中的最小二乘拟合法的原理,采用三维极值的单形调优方法,给出调合参数的数值解,得到能准确反映实测数据的纤端光场场强分布表达式。并比较实验数据与拟会结果,最后给出纤端光场场强分布的三维图形。 相似文献