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排序方式: 共有54条查询结果,搜索用时 15 毫秒
1.
ABSTRACTModified coupled-cluster (CC) methods such as linearized coupled-cluster doubles (LinCCD), approximate coupled pair (ACP D14), 2CC (from nCC family), parameterized CCSD (pCCSD) and distinguishable cluster (DCSD) can have their advantages over general CC methods. Though these methods include connected clusters of single and double excitations at most, distinguishable cluster, parameterized CC and approximate coupled pair methods, in particular, have been shown to produce quantitatively correct results in benchmark studies. To put these methods on a stronger foothold, it is essential to understand the rationale for their success: mimicking the effect of connected triple excitations. We exploit the relation between CC and many body perturbation theory (MBPT) in general, and between CCSD and MBPT(4)/MP4 in particular, to take a step towards bringing clarity to this persisting conundrum. Our aim here is to look for numerical signs of ‘addition by subtraction’ or ‘inclusion by deletion’ effect that is likely behind the success of these modified CCD or CCSD methods. We achieve this by revisiting well-studied examples of single and multiple bond dissociation and comparing the performance of these modified CCSD methods with higher-level CC methods. Though our results are qualitative in nature, we hope this would lead to more rigorous analysis in future studies. 相似文献
2.
针对一类直流电机系统,设计基于性能的未知推力波动的自适应补偿控制器.由于推力波动中含有非线性化的未知参数,因此无法利用常规的自适应方法,通过直接估计这些参数对其影响进行补偿.根据未知推力波动的结构特性,基于Lipshitz条件引入推力波动项的放大技术,设计其内部非线性化未知参数的自适应估计律,精确补偿其影响,从而避免了简单的把波动看作未知扰动所造成的系统性能的损失.有别于现有模型,在模型变换中并未忽略微小等效电感的影响,使得系统模型更具一般性.仿真结果表明该自适应控制器可有效补偿推力波动的影响,实现对指令信号的高精度快速跟踪且具有较强的抗干扰性和鲁棒性. 相似文献
3.
氧化铟锡薄膜的椭偏光谱研究 总被引:3,自引:0,他引:3
用溅射法在Si片上制备了厚度为140nm的氧化铟锡(ITO)薄膜。X射线衍射研究表明所制备的薄膜为多晶结构。在1.5~4.5eV范围内对ITO薄膜进行了椭偏测量。分别用德鲁德-洛伦茨谐振子(Drude Lorenz oscillators)模型、层进模型结合有效介质近似模型对椭偏参量ψ、Δ进行了拟合,得到ITO薄膜的折射指数n的变化范围在1.8~2.6之间,可见光范围内消光系数k接近于零,在350nm波长附近开始明显变化,且随着波长的减小k迅速增加。计算得到直接和间接光学带隙分别是3.8eV和4.2eV。并在1.5~4.5eV段给出一套较为可靠的、具有实用价值的ITO介电常量和光学常量。 相似文献
4.
ZHOU Li-Juan GU Yun-Ting MA Wei-Xing MENG Cheng-Ju PAN Ji-Huan 《理论物理通讯》2008,49(1):181-188
Based on the Global Color Symmetry Model, the non-perturbative Q, CD vacuum is investigated in the parameterized fully dressed quark propagator. Our theoretical predictions for various quantities characterized the QCD vacuum are in agreement with those predicted by many other phenomenologieal QCD inspired models. The successful predictions clearly indicate the extensive validity of our parameterized quark propagator used here. A detailed discussion on the arbitrariness in determining the integration cut-off parameter ofμ in calculating QCD vacuum condensates and a good method, which avoided the dependence of calculating results on the cut-off parameter is also strongly recommended to readers. 相似文献
5.
A.B. Levy 《Mathematical Programming》1999,85(2):397-406
n such that x≥0, F(x,u)-v≥0 , and F(x,u)-v T·x=0 where these are vector inequalities. We characterize the local upper Lipschitz continuity of the (possibly set-valued)
solution mapping which assigns solutions x to each parameter pair (v,u). We also characterize when this solution mapping is
locally a single-valued Lipschitzian mapping (so solutions exist, are unique, and depend Lipschitz continuously on the parameters).
These characterizations are automatically sufficient conditions for the more general (and usual) case where v=0. Finally,
we study the differentiability properties of the solution mapping in both the single-valued and set-valued cases, in particular
obtaining a new characterization of B-differentiability in the single-valued case, along with a formula for the B-derivative.
Though these results cover a broad range of stability properties, they are all derived from similar fundamental principles
of variational analysis.
Received March 30, 1998 / Revised version received July 21, 1998
Published online January 20, 1999 相似文献
6.
7.
张雷 《浙江大学学报(理学版)》1989,16(4):418-425
软件能重用性是提高软件开发生产率和质量的关键之一。本文研究了C语言中有利于软件成分重用的特点和不利于软件成分重用的因素,提出了判断C语言模块能重用性的准则和提高其重用性的技术,并给出了典型的实例加以说明。 相似文献
8.
Bai-min Yu 《应用数学学报(英文版)》2012,28(4):643-652
In this paper, we derive two general parameterized boundaries of finite difference scheme for Ve?e???s PDE which is used to price both fixed and floating strike Asian options. Using these two boundaries, we can deal with all kinds of situations, especially, some extreme cases, like overhigh volatility, very small volatility, etc, under which the Asian option is usually mispriced in many existing numerical methods. Numerical results show that our boundaries are pretty efficient. 相似文献
9.
In this paper,we establish the boundedness of parameterized Littlewood-Paley operator μ*,ρλ and parameterized area integral μΩρ,S with kernel satisfying the logarithmic type Lipschitz condition on the weak Hardy space. 相似文献
10.