共查询到18条相似文献,搜索用时 140 毫秒
1.
以山东莱钢1号高炉和山西临钢6号高炉在线采集的铁水含硅量([Si])的时间序列为样本, 利用重标级差分析(R/S)和盒维数计算方法, 得出两座高炉[Si]时间序列的Hurst指数H分别约为0.257和0.224, 盒维数DB分别约为1.712和1.724, 完成了对[Si]值波动复杂程度的定量估计, 证明两者的时间序列均为长程负相关的分形时间序列.随后根据分形迭代函数的理论与方法,确定相关参数,迭代生成模拟的[Si]时间序列, 拟合效果较好.
关键词:
铁水含硅量
重标级差分析
Hurst指数
分形拟合 相似文献
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以包钢6号高炉、邯钢7号高炉和莱钢1号高炉在线采集的铁水含硅量([Si])的时间序列为样本, 利用多分辨分析剔除样本的长期趋势,对样本保留的波动趋势进行多重分形特征辨识. 通过计算广义Hurst指数、尺度函数、多重分形谱, 全面、细致量化了序列的局部及不同层次的波动奇异性. 计算结果表明: 去除长期趋势后, 三座高炉[Si]序列的波动呈现显著多重分形特征, 这样的波动过程仅用单一的Hurst指数或box维数来描述是不够的.
关键词:
多分辨分析
铁水含硅量
波动
多重分形 相似文献
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根据Grassberger和Procaccia提出的Kolmogorov熵计算方法,以山东莱芜钢铁集团公司1号 高炉和山西临汾钢铁集团公司6号高炉测得的铁水硅含量时间序列为样本,计算了各自的Kol mogorov熵分别为(01453±00151)nats·h-1-1和(01553±0014 0)nats·h-1-1,并估计了两座高炉铁水硅含量可预测的时间尺度分别约为6 88和644h.由Kolmogorov熵均为大于零的有限值,定量地说明了这两座高炉
关键词:
混沌
Kolmogorov熵
高炉冶炼过程
铁水硅含量 相似文献
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高炉炼铁是一个复杂的多变量系统,而现行的操作制度是基于炉长经验的参数设置模式,导致能源尤其是煤粉的消耗常常处于“盲目”状态。本文综合炼铁工艺理论和高炉专家经验,针对白云鄂博矿石冶炼的特殊性,采用筛选出的优化数据,利用遗传算法所固有的全局搜索性能优化BP神经网络模型的权值和阈值,分别建立了基于遗传算法优化BP神经网络的高炉喷煤量优化预测模型以及工艺指标(铁水[Si]含量及入炉焦比)预测模型。优化数据的利用使得上述模型可以根据高炉当前炉况输出喷煤量的最佳优化设定值,并预测出相对应的工艺指标变化趋势。实际应用表明,本方法能够给现场操作人员提供操作指导,实现高炉稳定顺行、提高经济效益的目的。 相似文献
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通过使用自适应预报模型与时差方法相结合的方法对铁水含硅量进行预测,模型所需的工艺参数的原始数据经采集后需使用OPC技术标准进行传输以存入数据库系统中。硅预测程序通过对数据库查询得到所需的操作数据,由于生产环境对数据的干扰,需对其作均值滤波和插值运算的一次处理,然后进行求平均值、梯度和标准差统计学运算的二次处理,之后运用模糊理论将各个工艺参数归一化以提取参数特征值,作为铁水含硅量预测模型的输入参数,在预测过程中使用多元线性回归不断修正模型中的权重系数,以提高数学模型预测的准确率。 相似文献
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利用Si(001)向[110]方向偏4°角的斜切表面作为衬底,成功地制备了分布均匀的单畴的单原子In链阵列.扫描隧道显微镜分析表明,沉积的In原子优先吸附在台面上沿着台阶内边缘的位置,并在两个Si的二聚体链之间形成稳定的In二聚体.In二聚体组成直的单原子链,其生长机理与Car提出的“表面聚合反应”相一致.另外,衬底具有非常窄的台面和双原子层台阶边的特殊结构是形成单畴的单原子链的关键.
关键词:
铟单原子链
硅邻近面
扫描隧道显微镜 相似文献
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采用Tersoff势,修正试用不同的粒子间相互作用距离R,S的取值,进行了液态硅的分子动力学模拟.模拟的结果表明,修正Tersoff势下得到的径向分布函数能与X射线衍射、中子散射实验相一致.模拟得到在液态硅中,Si的配位数为6.9,键长为0.254nm.分子动力学模拟表明,液态硅中Si原子间联接成一种网络状结构,但大多数Si原子与其近邻Si原子仍保持近似于正四面体的局部构型.键角概率分布出现两个峰值~57°和~102°.通过键序参量分析,得到在液态硅近邻结构中,正四面体构型约占82%,键取向波动方差为5.
关键词: 相似文献
11.
The backscattering factor for systems with a non-uniform surface region: Definition and calculations
A. Jablonski 《Surface science》2009,603(13):2047-640
It has been recently shown that the backscattering factor (BF) in Auger electron spectroscopy (AES) noticeably depends on the in-depth structure of the surface region. This is a particularly important problem in sputter depth profiling monitored by AES since the signal intensity cannot be described with a single BF value. The BF depends on the removed amount of material and thus varies with sputtering time.In the present work, the definition of the BF is generalized to extend its applicability to systems with an in-depth composition profile. The generalized definition of the BF was applied to the special case of a depth profile, i.e. a buried thin layer. It has been shown that the BF for this case is expressed by the excitation depth distribution function (EXDDF) which is equivalent to the “Phi-Rho-Z” function used in electron probe microanalysis (EPMA). Different algorithms for calculating the BF are discussed. Calculations of the BF for buried layer were performed for the Ag M4N45N45 Auger transition in a thin layer of silver located at different depths in three matrix materials: Si, Cu, and Au. It was found that, indeed, the BF noticeably varies with the depth of the layer in the analyzed volume, although the extent of this variation depends on the matrix material. For Si, the variation is observed for the lowest primary beam energies considered, i.e., 1 and 2 keV. For Cu, a distinct depth dependence of the BF is visible at 10 keV and lower energies, while for Au, the BF varies with depth even at the highest considered energy, i.e. 30 keV. 相似文献
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标度指数计算的即时性与准确性对相关时间序列的动力学结构突变分析至关重要,然而现有方法在即时性与准确性上一直无法兼顾.将小波分析方法与滑动移除窗口技术相融合,提出一种新的动力学结构突变检测方法——滑动移除小波分析法.通过选取不同的滑动移除窗口,分别对构建的线性、非线性理想时间序列进行动力学结构突变分析,结果表明不论是线性时间序列还是非线性时间序列,滑动移除小波分析能够准确地检测到序列的动力学结构突变点及突变区间,对于滑动移除窗口长度依赖性较小,具有很强的稳定性,而且在计算速度上明显优于滑动移除重标极差和滑动移除方差分析方法,将在大数据处理中具有一定的优势.同时分别对线性、非线性理想时间序列添加高斯白噪声,结果表明滑动移除小波分析具有很强的抗噪能力,能够准确地检测到加噪后序列的突变点.对佛坪站日最高温度实测资料的动力学结构突变的准确检测进一步验证了该方法的有效性.滑动移除小波分析法可为具有相关性的系统动力学结构突变的快速、准确检测提供一种途径. 相似文献
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An instantaneous time series distance is defined through the equal time correlation coefficient. The idea is applied to the Gross Domestic Product (GDP) yearly increments of 21 rich countries between 1950 and 2005 in order to test the process of economic globalisation. Some data discussion is first presented to decide what (EKS, GK, or derived) GDP series should be studied. Distances are then calculated from the correlation coefficient values between pairs of series. The role of time averaging of the distances over finite size windows is discussed. Three network structures are next constructed based on the hierarchy of distances. It is shown that the mean distance between the most developed countries on several networks actually decreases in time, —which we consider as a proof of globalization. An empirical law is found for the evolution after 1990, similar to that found in flux creep. The optimal observation time window size is found ?15 years. 相似文献
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A. Ishii J. Yamazoe T. Aisaka 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):578
The nanometer-scale selective growth of Si islands on Si(0 0 1) windows in ultrathin SiO2 films are studied using the kinetic Monte Carlo simulation. The growth of Si islands is reproduced in simulation where we assume that the migration barrier energy for Si adatom on SiO2 film is far lower than that on the Si surface at the window. 相似文献
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We derive a dynamical mean‐field theory for mixtures of interacting bosons and fermions on a lattice (BF‐DMFT). The BF‐DMFT is a comprehensive, thermodynamically consistent framework for the theoretical investigation of Bose‐Fermi mixtures and is applicable for arbitrary values of the coupling parameters and temperatures. It becomes exact in the limit of high spatial dimensions d or coordination number Z of the lattice. In particular, the BF‐DMFT treats normal and condensed bosons on equal footing and thus includes the effects caused by their dynamic coupling. Using the BF‐DMFT we investigate two different interaction models of correlated lattice bosons and fermions, one where all particles are spinless (model I) and one where fermions carry a spin one‐half (model II). In model I the local, repulsive interaction between bosons and fermions can give rise to an attractive effective interaction between the bosons. In model II it can also lead to an attraction between the fermions. 相似文献
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Janusz Mi?kiewicz 《Physica A》2008,387(26):6595-6604
A time series is remapped onto an entropy concept, based on the Theil index. The Manhattan distance between these surrogate series is calculated, and contrasted to the usual correlation distance measure. The idea is applied to several Gross Domestic Product (relative increments) of rich countries. Such distances are calculated for various time window sizes. The role of time averaging in such finite size windows is discussed. We construct the locally minimum spanning tree (LMST) corresponding to the distance matrix. Another hierarchical network structure (Unidirectional Minimal Length Path) is compared with the LMST for confirming that the mean distance between the most developed countries on different networks actually decreases in time, — which we consider as a proof of economy globalization. It is stressed that this entropy distance measure seems more suitable in detecting some “phase transition” in time series, like a globalization process than the usual correlation based measure. 相似文献
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We have studied the in situ HCl etching of Si active areas on patterned wafers. After some in situ HCl etching at 20 Torr of Si(1 0 0), we have locally obtained 2 μm long areas with misorientation angles around 4.5° towards 〈1 1 0〉. Furthermore, we have evidenced a recess shape transition from convex (T ≤ 865 °C) to concave (T ≥ 895 °C) as the etch temperature increases, with a nearly flat surface with no facets at T = 880 °C. The morphology of the etched structures at a given time, temperature and PHCl/PH2 ratio will be a function of the slope lengths and the pattern dimensions. Different kinds of surfaces (rounded areas, facets) were obtained in 3.5 μm × 3.5 μm Si windows after HCl etching at 850 °C during 300 s, depending on the stress within. Thermal oxidations can indeed be used to increase by 65 MPa up to 110 MPa the compressive stress in those Si windows which are bordered by SiO2 shallow trench isolation. An increase of the misorientation angle from 4.5° up to 6° occurred after the above-mentioned HCl etch when switching from conventional to highly strained Si windows. For the shortest etching times studied here (150 s), a selective etching of 3.5 μm × 3.5 μm Si windows edges is responsible for the misorientation. The etch is then more uniform. Stress gradients might consequently be one of the main misorientation causes. We have also probed the influence of the shallow trench isolation (STI) thickness on the misorientation. A morphological difference before HCl etching has been shown to be responsible for the transition from sloped to rounded areas. A local loading effect may prevail in this case. 相似文献