连轧张力公式的实验验证和分析

连轧张力公式是连轧理论和实践的核心问题,该问题国内外都有大量的研究,20世纪60年代笔者推导了连轧张力微分方程、多机架动态张力公式、稳态张力公式,理论上已作过深入、广泛的分析讨论.日本在20世纪70年代对连轧张力公式进行了理论上的推导和实验验证,特别是浅川基男等人的连轧实验结果更为重要.为此引用了浅川基男的实验数据和宝钢2050 mm热连轧机上的实测数据,验证了连轧张力公式.     

基于确定性测量矩阵与变阈值SAMP的超高次谐波检测算法

随着电网中采用高频电力电子器件制造的设备逐渐增多,配电网中的超高次谐波现象已经成为了一种亟需解决的新型电能质量问题。相较于传统谐波检测方法采样超高次谐波信号时产生的巨大数据量,压缩感知作为一种新型信号处理方法,在使用测量矩阵对稀疏信号进行亚采样后通过重构算法用较少的数据就能精确地恢复原始信号,有效降低了对采样端硬件的要求。提出了一种基于确定性测量矩阵与变阈值SAMP算法的压缩感知超高次谐波检测算法。首先该方法采用了一种由确定性随机序列构造的测量矩阵,这种确定性测量矩阵的结构与随机测量矩阵相比更易于传输与存储,同时具有和高斯随机矩阵相同的重构性能。其次,针对SAMP重构算法在频谱泄露时易发生稀疏度过估计的问题,提出了一种改进的变阈值SAMP算法,设置一个动态的阈值来控制算法中内积的选取,减少迭代中的误选。改进算法提高了超高次谐波检测的精度,降低了因频谱泄露和噪声造成的误差且更容易硬件实现。最后,通过仿真和实测结果证明了改进算法的准确性和有效性。     

两种反演方法在NP-4号构造区的联合应用

NP-4号构造区主要发育扇三角洲沉积体系,储层物性较好,但储层横向变化快、厚度薄,单一的反演方法无法同时满足储层预测的精度要求。在做好测井曲线标准化等准备工作的基础上,先利用确定性反演确定储层的大致展布范围和横向变程,再利用地质统计学反演中的随机反演和序贯高斯配置协模拟得到纵向分辨率更高的波阻抗体和伽马体。此方法可以逐步提高反演的精度,在实际应用中取得了较好的效果。     

基于Verilog HDL的流水线模型机的设计与实现

为了提高模型机指令执行的并行性,使用Verilog HDL并采取top-down设计方法,利用确定的有限状态自动机(DFA)理论,设计并实现了一台具有指令级并行性的流水线模型机的方案.阐述了该流水线模型机的DFA设计算法与Verilog HDL的实现方法,并给出了相应的仿真测试.测试结果证明,该模型机能并行处理4条指令,并具有预取指令和旁路功能.     

Investigating soil and groundwater quality at different scales in a forested catchment: the Waldstein case study

The impact of anthropogenic depositions on soil and groundwater quality has been the subject of numerous studies in the last two decades. However, the problem of linking results and models at different scales remains to be solved. A case study has been performed in the Fichtelgebirge region in South-East Germany. Data from this case study has been used to analyse scale dependences of spatial variance, autocorrelation lengths, and the interdependence of soil hydrological and soil chemical parameters. For soil suction, spatial variability increases stepwise with scale. Three different sources of variation could be identified, predominating at different ranges of scale, making a deterministic mapping feasible. Local SO₄ deposition explained much of the spatial pattern of SO₄ concentration in soil solution and in catchment runoff observed at different scales. This is mainly due to the fact that the sorption capacity of the soils in this region has been exceeded. Decreasing SO₄ deposition in the long term run is likely to enhance the influence of the soil, and reduces the correlation between deposition and soil solution concentration. NO₃ showed minimum variation at the county scale. This seems to be a reasonable representative elementary area for mapping regional NO₃ concentration patterns. For protons and Cl, neither observed spatial patterns nor the scale dependence of spatial heterogeneity could be explained adequately.     

点接触混合润滑中两种求解模型的比较

混合润滑是典型零部件主要的润滑状态,根据表面形貌表征方式的不同,混合润滑模型一般分为统计学模型和确定性模型两类.为研究2种模型求解粗糙表面点接触混合润滑性能的差异,通过基于平均流量模型和GW模型的统计模型、基于统一Reynolds方程的确定性模型,分析并比较不同表面粗糙度、卷吸速度、载荷以及润滑油环境黏度时2种模型预测...     

圈的优美性

本文得到了圈Ｃｎ为优美图的充要条件,并给出了圈Ｃ４ｋ,Ｃ４ｋ－１的优美标号。     

High-velocity fluidization of solid particles in a liquid-solid circulating fluidized bed system

Particulate and aggregative fluidizations in a liquid-solid circulating fluidized bed system are characterized by chaotic time series analysis of local voidage and heat transfer fluctuations in terms of the correlation dimension and Kolmogorov entropy. Both correlation dimension and Komogorov entropy of the voidate fluctuation are found to decrease with decreasing bed voidage in both fluidization regimes, suggesting the suppression of chaotic motion of individual particles due to high solid concentration. The correlation dimension of the heat transfer fluctation in the aggregative fluidization regime is higher than that in the particulate fluidization regime. This reflects the complex convective motion of liquid and solid phases induced by the formation of the liquid streaks and aggregates of particles.     

基于图像分析的视频监控系统的设计

针对工业现场视频监控的需求特点,提出了一个两级的计算机监控系统的设计方案。第一级应用图像分析对生产线进行状态监测,并对异常情况进行报警;第二级对生产线进行不间断的录像．并能根据报警信息生成异常状态发生前后的视频录像,进行事故过程回放。分析了系统的一般设计思想及其组成,及在线异常报警、事故回放等功能实现的方法。讨论了在工业现场的实现中应该注意的问题。实践结果表明,该系统安全有效,实用性高,监测过程不影响生产的进行,提高了产品质量控制水平和生产效率。     

NUMERICAL SOLUTIONS OF LINEAR MIXED BOUNDARY VALUE PROBLEMS USING STOCHASTIC REPRESENTATIONS

The application of Itô's formula induces some probabilistic representations of solutions of deterministic linear problems with boundary conditions of Dirichlet, Neumann, Fourier and mixed types. These representations are used to establish some easily implementable algorithms which compute an approximate solution by means of simulation of reflected random walks. They do not require selected configurations at the neighbourhood of the domain boundary, nor a discretization mesh. The associated simulation methods are obtained and applied to problems for each class of boundary conditions. Numerical experiments with distributed source in two- or three-dimensional geometries, and computational results with estimation of error, are reported. © 1997 by John Wiley & Sons, Ltd.