不同进水流速对泵站进水池漩涡的影响

为探究泵站进水流速大小与泵站进水池水流流态、漩涡的产生与发展变化规律,结合泵站实际运行情况,建立引渠、前池、进水池和进水管的泵站物理模型和湍流数学模型,采用VOF模型和非定常的SST k-ω湍流模型对9种不同流速的泵站进水水流特性进行数值模拟,分析不同进水流速的泵站进水池水流流场分布、漩涡涡量的变化及分布规律。研究结果表明:当进水流速为0.322 2～0.564 2 m/s时,泵站表面漩涡的强度随进水流速的增大而增强:当进水流速为0.322 2～0.401 6 m/s时,进水池出现Ⅲ、Ⅳ型漩涡;当进水流速为0.483 5 m/s时,进水池出现Ⅴ型漩涡;当进水流速为0.520 8～0.564 2 m/s时,进水池出现Ⅵ型漩涡。将数值计算结果与模型试验结果进行对比,两者基本吻合。研究结果可为泵站工程设计提供参考。     

地表径流速度对城市内涝影响规律

为分析地表径流速度对城市内涝的影响,采用一维地下排水管网与二维城区地形的动态耦合模型,选取大连市某排水区块作为研究区域,设置4种地表径流速度10种设计降雨场景,模拟分析在不同重现期设计降雨及不同地表径流速度下研究区的内涝积水特性。结果表明:随着地表径流速度降低,管道排水压力变小,管道排水达标率最高可提升48.05%,且降雨重现期越短,地表径流流速对管道排水压力的削减效果越明显;地表径流流速对检查井溢流量影响显著,随着地表径流速度降低,检查井溢流量峰值最高可减小2 750 m~3,峰现时间最长可滞后56 min,同时随着降雨重现期增长,地表径流流速对检查井溢流量的削减效果减弱;研究区低、高风险区淹没面积随地表径流速度降低,最高可分别减小1.64万、8.37万m~2,但中风险区淹没面积变化反复。     

Bayesian Nonparametric Joint Mixture Model for Clustering Spatially Correlated Time Series

Abstract

We develop a Bayesian nonparametric joint mixture model for clustering spatially correlated time series based on both spatial and temporal similarities. In the temporal perspective, the pattern of a time series is flexibly modeled as a mixture of Gaussian processes, with a Dirichlet process (DP) prior over mixture components. In the spatial perspective, the spatial location is incorporated as a feature for clustering, like a time series being incorporated as a feature. Namely, we model the spatial distribution of each cluster as a DP Gaussian mixture density. For the proposed model, the number of clusters does not need to be specified in advance, but rather is automatically determined during the clustering procedure. Moreover, the spatial distribution of each cluster can be flexibly modeled with multiple modes, without determining the number of modes or specifying spatial neighborhood structures in advance. Variational inference is employed for the efficient posterior computation of the proposed model. We validate the proposed model using simulated and real-data examples. Supplementary materials for the article are available online.     

Hybrid-triggered fault detection filter design for networked Takagi–Sugeno fuzzy systems subject to persistent heavy noise disturbance

In the network environment, the single time-triggered scheme wastes limited bandwidth resources due to all the sampled data are transmitted to the networks, and the single event-triggered scheme may increase system error because of ignoring factors such as changes in network utilization. To reduce the design conservatism, this paper is concerned with the hybrid-triggered L₁ fault detection filter design for a class of nonlinear networked control systems (NCSs) described by Takagi–Sugeno (T-S) fuzzy model. Taking the effects of time-triggered scheme and event-triggered scheme into consideration simultaneously, we construct a fuzzy fault detection system. New results on stability and L₁ performance are proposed for fuzzy fault detection system by exploiting the Lyapunov–Krasovskii functional and by means of the integral inequality method. Specially, attention is focused on the design of fault detection filter that guarantees a prescribed L₁ noise attenuation level . Finally, two examples are presented to demonstrate the effectiveness of the proposed method.     

综放开采最大导水裂隙带高度的应力法预测

在重点模拟大采高条件下覆岩低抗拉特性的基础上，建立了“大采高ＦＥＭ－ＮＴＡ耦合模型”．选择了合适的屈服准则、流动法则及应力应变本构关系，综合优选输入参数，于淮南矿务局新集矿实施了该“耦合模型”．预测裂采比为１０．６０～１０．８５倍．经钻探验证，取得了较为理想的预测精度．     

羧甲基纤维素在铌矿物选别中抑制行为的研究

讨论了弱磁尾矿中的铌矿物浮选产物中羧甲基纤雏素对各种脉石矿物的抑制行为，建立了铌矿物选别的脉石抑制剂——羧甲基纤维素的吸附模型。     

矿产资源形势分析与预测的理论与方法

结合矿产资源形势分析与预测的基本理论，综合介绍了目前比较流行的几种分析与预测的方法，旨在为政府和企业提供预测方法和决策依据，以促进资源的合理开发和利用。     

回归方程在煤灰成分分析数理统计中的应用

在煤灰成分分析检测项目中有一些通常采用光电比色法进行检验.为了提高数据处理的准确度,采用一元线性回归方程对数据进行数理统计的方法,建立简单的数学模型,可快速、准确地获得计算结果.     

Estimate of Stress-Strain State of Rocks in the Area of Drilling Kola Ultradeep Well

The values of horizontal tectonic stresses are estimated up to depth of 11 500 m by the measurement of velocities of longitudinal and transverse waves in rock samples extracted from various depths when drilling Kola Ultradeep Well.