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991.
多粒度粗糙集和决策论粗糙集是Pawlak粗糙集的重要推广,目前已成为人工智能研究的热点.然而,它们大多处理的都是单值信息系统中的问题.而实际生活中绝大多数都是处理多值问题,为了解决这一问题,在多集值信息表中将多粒粗糙集与模糊决策论粗糙集相结合进行研究,提出了其在乐观,悲观情形下的上下近似,研究了一些相关性质并给出了多集值信息表中的多粒度模糊决策论粗糙集精度、粗度的概念,最后通过一个具体例子验证其有效性. 相似文献
992.
根据某市自来水有限责任公司第二水厂的历史矾耗数据,建立矾耗流量关于原水浊度、温度等的动态矾耗模型. 通过对数据进行处理得到10900个合格且净水效果高效的数据,将筛选出的数据分为训练样本集和测试样本集. 在回归拟合中,通过拟合R2的大小将原水浊度划分为“低浊”“中浊”“高浊”3个区间,利用泰勒展开公式的非线性变量代换分别对3个区间建立不同的多项式回归模型,得到预测正确率约为72%,总的矾耗流量值约减少了9.6%的结果;在随机森林模型中,使用10900个合格数据,利用训练样本集,以“原水浊度”“pH值”“原水流量”和“水温”为输入变量,建立包含2000棵决策树的随机森林模型,得到预测正确率约为44. 21%,总的矾耗流量值增加了0.04%的结果. 从模型对合格数据的拟合优度看,随机森林模型比非线性回归模型效果更好;在平均绝对误差、平均绝对偏差百分比等评价指标上,前者均优于后者;但从历史数据检验的结果,模型的可解读性,模型的操作难度和推广角度看,分段二元非线性回归模型的优势更为突出. 相似文献
993.
994.
Hong Huang 《Journal of Geometric Analysis》2013,23(3):1213-1235
In this note we prove the following result: Let X be a complete, connected 4-manifold with uniformly positive isotropic curvature, with bounded geometry, and with no essential incompressible space form. Then X is diffeomorphic to $\mathbb{S}^{4}$ , or $\mathbb{RP}^{4}$ , or $\mathbb{S}^{3}\times\mathbb {S}^{1}$ , or $\mathbb{S}^{3}\widetilde{\times} \mathbb{S}^{1}$ , or a possibly infinite connected sum of them. This extends work of Hamilton and Chen–Zhu to the noncompact case. The proof uses Ricci flow with surgery on complete 4-manifolds, and is inspired by recent work of Bessières, Besson, and Maillot. 相似文献
995.
DING GuoJian GUO LiWei XING ZhiGang CHEN Yao XU PeiQiang JIA HaiQiang ZHOU JunMing & CHEN Hong Beijing National Laboratory of Condensed Matter Physics 《中国科学:物理学 力学 天文学(英文版)》2010,(1)
Al x Ga 1-x N/GaN high-electron-mobility transistor (HEMT) structures with Al composition ranging from x = 0.13 to 0.36 are grown on sapphire substrates by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The effects of Al content on crystal quality, surface morphology, optical and electrical characteristics of the AlGaN/GaN heterostructures have been analyzed. Although high Al-content (36%) heterostructure exhibits a distinguished photoluminescence peak related to recombination between the two-dimensional electron gas and photoexcited holes (2DEG-h), its crystal quality and rough surface morphology are poor. 2DEG mobility increases with the Al content up to 26% and then it apparently decreases for high Al-content (36%) AlGaN/GaN heterostructure. The increase of sheet carrier density with the increase of Al content has been observed. A high mobility at room temperature of 2105 cm 2 /V s with a sheet carrier density of n s = 1.10 × 10 13 cm -2 , for a 26% Al-content AlGaN/GaN heterostructure has been obtained, which is approaching state-of-the-art for HEMT grown on SiC. Sheet resistance as low as 274 Ω/□ has also been achieved. 相似文献
996.
The purpose of this paper is to develop an effective methodology for solving constrained matrix games with payoffs of trapezoidal fuzzy numbers (TrFNs), which are a type of two-person non-cooperative games with payoffs expressed by TrFNs and players’ strategies being constrained. In this methodology, it is proven that any Alfa-constrained matrix game has an interval-type value and hereby any constrained matrix game with payoffs of TrFNs has a TrFN-type value. The auxiliary linear programming models are derived to compute the interval-type value of any Alfa-constrained matrix game and players’ optimal strategies. Thereby the TrFN-type value of any constrained matrix game with payoffs of TrFNs can be directly obtained through solving the derived four linear programming models with data taken from only 1-cut and 0-cut of TrFN-type payoffs. Validity and applicability of the models and method proposed in this paper are demonstrated with a numerical example of the market share game problem. 相似文献
997.
In this paper, we propose, analyze and test primal and dual versions of the alternating direction algorithm for the sparse signal reconstruction from its major noise contained observation data. The algorithm minimizes a convex non-smooth function consisting of the sum of ? 1-norm regularization term and ? 1-norm data fidelity term. We minimize the corresponding augmented Lagrangian function alternatively from either primal or dual forms. Both of the resulting subproblems admit explicit solutions either by using a one-dimensional shrinkage or by an efficient Euclidean projection. The algorithm is easily implementable and it requires only two matrix-vector multiplications per-iteration. The global convergence of the proposed algorithm is established under some technical conditions. The extensions to the non-negative signal recovery problem and the weighted regularization minimization problem are also discussed and tested. Numerical results illustrate that the proposed algorithm performs better than the state-of-the-art algorithm YALL1. 相似文献
998.
在超短超强飞秒SILEX-Ⅰ激光装置上,开展了薄膜靶激光质子加速的实验研究。实验发现激光预脉冲、靶厚度对质子加速有很大的影响。在激光强度3×1018~3×1019W/cm2条件下,采用前表面厚度为3μm铜、后表面镀4μm厚CH靶,质子的最大能量达到3.15 MeV。而对190 nm厚CH膜靶,质子的最大能量为0.54 MeV。初步研究了激光偏振对质子加速的影响,相同激光功率条件下,圆偏振激光加速产生的质子最大能量略低于P偏振打靶。这些结果与靶后鞘层加速机制相一致。 相似文献
999.
利用分形结构的自相似性将分形理论应用于频率选择表面(FSS)领域即可使在单屏FSS上具有多频段带通滤波的特性,结合Floquet周期边界条件,采用矩量法研究了二阶Y环分形FSS在不同入射角度下迭代比例因子F及单元排布方式对频率响应特性的影响规律,给出谐振频率的经验估算值.计算及实验结果表明,FSS的谐振频率主要由迭代比例因子及起始单元尺寸决定,而透过率及-3 dB带宽则对排布方式的改变较敏感.实验结果与理论分析一致. 相似文献
1000.
Yang Liu Zhichao Fang Hong Li Siriguleng He Wei Gao 《Journal of Applied Mathematics and Computing》2013,43(1-2):249-269
In this article, a coupling method of new mixed finite element (MFE) and finite element (FE) is proposed and analyzed for fourth-order parabolic partial differential equation. First, the fourth-order parabolic equation is split into the coupled system of second-order equations. Then, an equation is solved by finite element method, the other equation is approximated by the new mixed finite element method, whose flux belongs to the square integrable space replacing the classical H(div;Ω) space. The stability for fully discrete scheme is derived, and both semi-discrete and fully discrete error estimates are obtained. Moreover, the optimal a priori error estimates in L 2 and H 1-norm for both the scalar unknown u and the diffusion term γ and a priori error estimate in (L 2)2-norm for its flux σ are derived. Finally, some numerical results are provided to validate our theoretical analysis. 相似文献