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991.
粗集理论原型系统的集成与实现 总被引:1,自引:1,他引:0
粗集理论主要基于集合近似的概念,给出了知识划分和规则提取的一套方法.主要有不可分辨类的数据划分定义、上下近似和相对正区域求解方法、最小决策规则生成等。针对粗集中这些重要理论.文章主要介绍开发粗集理论原型系统的设计要求、系统组成以及实现粗集理论中相关算法理论依据,并包含有通用数据库接口.因此有着一定的应用价值。 相似文献
992.
简要介绍公司承建的某一国家级实验动物生产环境设施的应用、要求和技术实施情况及其指标控制,供相关人员参考和交流。 相似文献
993.
本文应用符号(文字)系数多项式的安全判别系统来研究四元齐次多项式或三元非齐次多项式的正半定性质,我们采用计算机代数软件MAPLE和图形软件,将整个平面划分成有限个区域,有每个区域里通过代表确定多项式的正定性质。本方法直观,可靠,易于理解,并有助于对多项工的进一步研究,本文给出一个具有实例。 相似文献
994.
K. R. Kim 《塑料、橡胶和复合材料》2016,45(3):118-126
Electro-conductive poly(vinyl alcohol)/multi-walled carbon nanotube (PVOH/MWNT) and poly(ethylene-co-vinyl alcohol) (EVOH)/MWNT nanocomposites were prepared by precipitation saponification method. The MWNT was functionalised by electron beam irradiation in air at 1200?kGy doses. The electrical resistivity, thermal and mechanical properties, and positive temperature coefficient (PTC) behaviour of these nanocomposites were investigated. The melting and crystallisation peak temperatures of both nanocomposite systems were shifted at a higher temperature with the increase in saponification time. Their crystallinity and mechanical strength also increased with saponification time, indicating an increase in intermolecular hydrogen bond between vinyl alcohol groups. With the saponification time, PTC peak temperature of EVA28/MWNT and EVA40/MWNT nanocomposites was shifted at a higher temperature and followed by a negative temperature coefficient (NTC) of resistivity. However, the saponified PVAc/MWNT nanocomposites showed only NTC behaviour over a temperature range of 30–140°C. 相似文献
995.
为了解决页岩气开采用螺杆钻具双等壁厚定子内螺旋曲面难加工的问题,建立双等壁厚定子的外高压成形数值模拟模型,研究管坯几何尺寸、液压力大小和回弹对定子成形质量的影响规律,通过实验和三维测量验证了数值模拟模型的准确性。结果表明:管坯几何尺寸与壁厚、等效塑性应变、位移、残余应力和间隙值成正比;成形液压力达到150 MPa及以上对等效塑性应变、壁厚几乎没有影响;定子胀型区域的回弹量大于过渡区域和接触区域;当成形液压力为210 MPa,管坯内径为88 mm,定子成形质量最优。 相似文献
996.
Achievable rate region with secrecy constraints for secure communication in two‐way relay networks 下载免费PDF全文
Yunchuan Yang Wenbo Wang Hui Zhao 《International Journal of Communication Systems》2015,28(2):231-249
In this paper, we consider a two‐way relay network consisted of two sources and multiple relays in the presence of an eavesdropper, where the cooperative beamforming strategy is applied to exploit the cooperative diversity to support the secure communication as illustrated in Figure 1. Naturally, we are interested in the beamforming strategy and power allocation to maximize the achievable sum secrecy rate. However, the corresponding problem is equivalent to solve a product of three correlated generalized Rayleigh quotients problem and difficult to solve in general. Because of the openness of wireless medium, the information rate leakage to the eavesdropper cannot be canceled perfectly. To some extent, ‘almost perfect secrecy’, where the rate leakage to the eavesdropper is limited, is more interesting from the practical point of view. In this case, we concern ourself mainly the achievable rate region for general case where the rate at the eavesdropper is regarded as the measurement of secrecy level. Two beamforming approaches, optimal beamforming and null space beamforming, are applied to investigate the achievable rate region with total power constraint and the rate constraint at the eavesdropper, which can be obtained by solving a sequence of the weighted sum inverse‐signal‐to‐noise‐ratio minimization (WSISM) problem. Because of the non‐convexity of WSISM problem, an alternating iteration algorithm is proposed to optimize the relay beamforming vector and two sources' transmit power, where two subproblems need to be solved in each iteration. Meanwhile, we provide the convergence analysis of proposed algorithm. Through the numerical simulations, we verify the effectiveness of proposed algorithm. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
997.
《国际计算机数学杂志》2012,89(13):3079-3093
The cyclic reduction method is a direct method for solving tridiagonal linear systems. At the first step of this method, a tridiagonal coefficient matrix is transformed into a pentadiagonal form. In this article, we prove that the condition number for eigenvalues of some classes of coefficient matrices always decreases after the first step of the cyclic reduction method. 相似文献
998.
The diffusive predator–prey system with modified Leslie–Gower and Holling-type III schemes is considered here. Firstly, stability analysis of the equilibrium for a reduced ODE system is discussed. Secondly, we obtain that the system is permanent. Thirdly, sufficient conditions for the global asymptotical stability of the unique positive equilibrium of the system are derived by using the method of Lyapunov function. Finally, we establish the existence and nonexistence of nonconstant positive steady states of this reaction–diffusion system, which indicates the effect of large diffusivity. 相似文献
999.
Alexis Bienvenu Béléké 《Journal of power sources》2010,195(22):7669-8290
Nickel-aluminum layered double hydroxide/carbon (Ni-Al LDH/C) composites have been fabricated using a mixed solution of {Al(NO3)3·9H2O and H3BO3} as fluoride scavengers in the liquid phase deposition (LPD) process. The amount of divalent Ni2+ substituted by trivalent Al3+ within the lattice of α-Ni(OH)2 was controlled by the concentration of Al(NO3)3·9H2O solution. X-ray diffraction studies reveal pure phase Ni-Al LDH, isostructural and isomorphic to α-Ni(OH)2 with higher interlayer distance. The electrochemical properties of the cathode materials containing 0, 8.6, 13.8, 17.8, 21.3 and 23.4 Al% were evaluated by the means of charge-discharge and cyclic voltammetry measurements. The overall comparison indicates that Ni-Al LDH/C composites have higher electrochemical performance than pure α-Ni(OH)2/C composite. The cathode with 17.8 Al% exhibits the best performance at 1 C compared to other Al3+ contents; a much lower voltage plateau, well separated from the oxygen evolution at the end of the charging as well as a single flat and high discharge plateau with a discharge capacity of 376.9 mAh gcomp−1. Short term durability test for 80 cycles showed that the electrode containing 13.8 Al% has the highest discharge rate at 2 C. The range of Al substitution 13.8-17.8 Al% provides a good electrochemical response. 相似文献
1000.
Shodhan Rao 《Systems & Control Letters》2011,60(11):892-899
In this paper, a new test of stability for scalar autonomous systems known as Nevanlinna test of stability is introduced. This test can be derived using the Bézoutian of the characteristic polynomial of a given system. It is shown in this paper that an associated quadratic differential form called the Bézoutian functional is positive if and only if the given system is asymptotically stable. Nevanlinna test of stability proceeds by checking if the Bézoutian functional associated with a given system is positive. 相似文献