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991.
Several direct constructions via skew starters and Weil's theorem on character sum estimates are given in this paper for optimal (gv, 5, 1) optical orthogonal codes (OOCs) where 60 ≤ g ≤ 180 satisfying g ≡ 0 (mod 20) and v is a product of primes greater than 5. These improve the known existence results on optimal OOCs. Especially, we provide an optimal (v, 5, 1)‐OOC for any integer v ≡ 60, 420, 660, 780, 1020, 1140, 1380, 1740 (mod 1800). © 2004 Wiley Periodicals, Inc. J Combin Designs 13: 54–69, 2005. 相似文献
992.
YIN JianxingDepartment of Mathematics Suzhou University Suzhou China 《中国科学A辑(英文版)》2004,47(4):566-577
In this paper, a type of combinatorial design (called difference packing array) is proposed and used to give a construction of systematic authentication codes. Taking advantage of this construction, some new series of systematic authentication codes are obtainable in terms of existing difference packing arrays. 相似文献
993.
994.
Luc Oger Chrystèle Annic Daniel Bideau Rongqing Dai Stuart B. Savage 《Journal of statistical physics》1996,82(3-4):1047-1061
Rapid granular flow is diffusive in character. This diffusive nature is important in the generation of constitutive properties such as effective shear and bulk viscosities, effective conductivity of particle fluctuation energy, and self-diffusion coefficients. Experiments were performed in a large air-table apparatus that can sustain up to a few thousand small, light disks just above a horizontal porous plane. Experiments on 2D diffusion processes were performed using this apparatus. Measurements of self-diffusion coefficients and granular temperature in systems having different areal concentrations are in good agreement with predictions based on the kinetic theory and on numerical simulations. 相似文献
995.
QIAN Shang-Wu GU Zhi-Yu 《理论物理通讯》2005,44(9)
This article discusses the role of covariance correlation tensor in the establishment of the criterion of quantum entanglement. It gives a simple example to show the powerfulness in the treatment of quantum dense coding,and illustrates the fact that this method also provides theoretical basis for establishing corresponding knotted pictures. 相似文献
996.
从理论上分析了单一膜料倾斜入射沉积时的折射率与填充密度的关系,给出了三种不同的表达式;然后从正变和负变、完整周期和存在半周期以及不同的周期数等几个方面探讨了膜层的填充密度按照线性变化时的渐变折射率薄膜的光学特性,并将折射率的不同理论表达式对光学特性的影响进行了对比,最后讨论了单一膜料倾斜入射沉积渐变折射率薄膜的方法、填充密度线性变化时的渐变折射率薄膜的应用及制备中需要进一步解决和处理的问题.
关键词:
斜角入射沉积
渐变
填充密度 相似文献
997.
998.
999.
K.M.J. De Bontridder B.V. Halldórsson M.M. Halldórsson C.A.J. Hurkens J.K. Lenstra R. Ravi L. Stougie 《Mathematical Programming》2003,98(1-3):477-491
In the test cover problem a set of m items is given together with a collection of subsets, called tests. A smallest subcollection of tests is to be selected such that for each pair of items there is a test in the selection that contains exactly one of the two items. It is known that the problem is NP-hard and that the greedy algorithm has a performance ratio O(log m). We observe that, unless P=NP, no polynomial-time algorithm can do essentially better. For the case that each test contains at most k items, we give an O(log k)-approximation algorithm. We pay special attention to the case that each test contains at most two items. A strong relation with a problem of packing paths in a graph is established, which implies that even this special case is NP-hard. We prove APX-hardness of both problems, derive performance guarantees for greedy algorithms, and discuss the performance of a series of local improvement heuristics.
Partially supported by the Future and Emerging Technologies Programme of the EU under contract number IST-1999-14186 (ALCOM-FT).Partially supported by a Merck Computational Biology and Chemistry Program Graduate Fellowship from the Merck Company Foundation.Also Iceland Genomics CorporationPartially supported by subcontract No. 16082-RFP-00-2C in the area of ``Combinatorial Optimization in Biology (XAXE),' Los Alamos National Laboratories, and NSF grant CCR-0105548.Mathematics Subject Classification: 90B27 相似文献
1000.
Several different divergences are tested in the several internal wavelength locker schemes for 10 Gbps electro-absorption modulated laser (EML) module. A 10 Gbps EML module with a simple and robust internal wavelength locker for metro dense WDM application is successfully demonstrated. The wavelength aging over 2000 h is done at elevated temperature of 70°C. The average wavelength drift of 10 modules is measured to be ± 5 pm. These modules can be successfully applied to the 10 Gbps DWDM systems with 50 GHz channel spacing. 相似文献