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61.
针对采用传统参数估计方法得到的模型拟合误差较大的问题,建立多重威布尔混合分布参数估计的非线性最小二乘模型,并提出基于模拟退火(SA)思想的自适应粒子群(PSO)算法进行求解。在PSO算法优化过程中,采用自适应方法调整惯性权重和加速因子,加快其收敛速度;引入模拟退火机制,根据Metropolis准则确定最优粒子的取舍,改善其全局搜索能力。将该方法应用到某型柴油机喷油器失效分布的参数估计中,并与图解法、基于Levenberg-Marquardt的非线性最小二乘法、标准PSO算法、自适应PSO算法求解的结果进行比较,分析所提方法的优化性能及精度。结果表明,该方法能够有效提高多重威布尔混合分布模型参数估计的精度和效率。 相似文献
62.
离子液体是近年来发展起来的一种绿色介质,在化工反应和分离过程中具有广泛的应用前景。离子液体的溶液热力学性质和相平衡数据是其相关工艺过程设计的基础。本文从如下几个方面综述了离子液体溶液热力学模型的研究进展,即溶液热力学研究方法、溶液热力学模型的构建、离子液体的结构和分子间作用力、离子液体的溶液热力学模型及其在相平衡计算中的应用。重点分析了适用于离子液体溶液热力学性质计算的状态方程模型和过量Gibbs自由能模型或活度系数模型,离子液体的电解质和非电解质溶液模型,以及这些模型对ILs结构、氢键和静电作用的处理方法。分析了这些模型的优缺点,并对今后离子液体的溶液热力学研究提出了建议。 相似文献
63.
Shape from focus (SFF) is a widely used passive optical method for 3D shape reconstruction. In SFF, a focus measure, which is used to estimate the relative focus level, plays a critical role in depth estimation. In this article, we present a new focus measure for accurate 3D shape estimation in optical microscopy based on the analysis of 3D structure tensor. First, the 3D tensors are computed from the input image sequence for each pixel. Then, each tensor is decomposed into point, curve, and surface tensors by decomposing tensors into eigenvalues and eigenvectors. Finally, the surfaceness is used to measure the quality of sharpness. The proposed focus measure provides accurate focus values and better resistance against noise. The proposed measure is evaluated by conducting experiments using image sequences of simulated and microscopic real objects. The comparative analysis demonstrates the effectiveness of the proposed focus measure in recovering 3D shape. 相似文献
64.
Qianchen YU Zhiwen YU Zhu WANG Xiaofeng WANG Yongzhi WANG 《Frontiers of Computer Science》2020,14(6):146323
Overlapping community detection has become a very hot research topic in recent decades, and a plethora of methods have been proposed. But, a common challenge in many existing overlapping community detection approaches is that the number of communities K must be predefinedmanually. We propose a flexible nonparametric Bayesian generative model for count-value networks, which can allow K to increase as more and more data are encountered instead of to be fixed in advance. The Indian buffet process was used to model the community assignment matrix Z, and an uncollapsed Gibbs sampler has been derived.However, as the community assignment matrix Z is a structured multi-variable parameter, how to summarize the posterior inference results and estimate the inference quality about Z, is still a considerable challenge in the literature. In this paper, a graph convolutional neural network based graph classifier was utilized to help to summarize the results and to estimate the inference quality about Z. We conduct extensive experiments on synthetic data and real data, and find that empirically, the traditional posterior summarization strategy is reliable. 相似文献
65.
66.
This paper is concerned with the problem of joint input and state estimation for linear stochastic systems with direct feedthrough. Based on the fact that each unknown input between any two time steps is always bounded, a novel improved algorithm is proposed. Compared with existing results, this algorithm can effectively enhance estimation accuracy. Moreover, the stability of the algorithm is also discussed. Finally, an illustrative example is given to demonstrate the effectiveness of the proposed approach. 相似文献
67.
68.
O.N. Kondrateva G.E. Nikiforova A.V. Tyurin M.A. Ryumin V.M. Gurevich A.P. Kritskaya K.S. Gavrichev 《Ceramics International》2018,44(15):18103-18107
The heat capacity of ytterbium orthovanadate was first measured by adiabatic calorimetry in the temperature range T?=?12.28–344.06?K. No obvious anomalies were observed on the curve obtained. The values of standard thermodynamic functions in the temperature range T?=?0–400 K were calculated. Based on low-temperature calorimetry data obtained, previously published data on the high-temperature heat capacity of ytterbium orthovanadate were corrected. The anomalous contribution to heat capacity for YbVO4 was compared with the data known for YbPO4. 相似文献
69.
Thermodynamically stable (Hf1–xTax)C (x?=?0.1–0.3) compositions were selected by First Principle Calculation and synthesized in nanopowders via high-energy ball milling and carbothermal reduction of commercial oxides at 1450?°C. The formation of a solid solution during powder synthesis was investigated. The solid solution carbide powders were sintered at 1900?°C by spark plasma sintering without a sintering aid. As a result, the (Hf1–xTax)C solid solution carbides exhibited high densities, excellent hardness and fracture toughness (ρ: 98.7–100.0%, HVN: 19.69–19.98?GPa, KIC: 5.09–5.15?MPa?m1/2) compared with previously reported HfC and HfC–TaC solid solution carbides. 相似文献
70.
Y.F. Gomes Jun Li K.F. Silva A.A.G. Santiago M.R.D. Bomio C.A. Paskocimas M.A. Subramanian F.V. Motta 《Ceramics International》2018,44(11):11932-11939
In this paper, a new synthetic pathway is proposed for the system YIn1-xMnxO3, a bright blue inorganic pigment, discovered in 2009. Blue pigment samples with increasing concentration of Mn3+ (x?=?0.08, 0.12 and 0.16) were prepared using the complex polymerization method (CPM) and compared with those synthesized via solid state reaction. All powders, the amorphous precursor from CPM and the starting materials for solid state method, were calcined at 1000, 1100, 1200 and 1300?°C for 12?h, and the resulting blue pigments were characterized by X-ray diffraction (XRD), colorimetric system CIE L*a*b* and Near infrared (NIR) reflectance measurements. XRD patterns and Rietveld Refinement show that the lowest temperature at which single hexagonal phase (isostructural to YInO3) is formed is 1000?°C for CPM method and 1300?°C for conventional solid state method, respectively. The L*a*b* values demonstrate that the coloration of powders prepared by CPM exhibit temperature dependence below 1300?°C, a color shade shift from grayish blue to intense deep blue is observed when heating the samples from 1000 to 1300?°C. Blue pigments obtained by CPM have smaller particle size due to low temperatures and excellent near-infrared reflectance comparable to those by solid state method. Thus, providing advantages for application process and energy efficiency. 相似文献