基于HHT方法的矿井瓦斯体积分数预测

为有效分析煤矿瓦斯监测数据以实现较准确的瓦斯浓度预测,研究应用希尔伯特-黄变换(HHT)方法进行瓦斯浓度时间序列分析与预测的方法.应用经验模态分解(EMD)方法将瓦斯浓度时间序列分解成不同频率的固有模态函数(IMF)分量的叠加,以获取瓦斯浓度时间序列的瞬时特征;通过Hilbert变换求得各IMF分量的瞬时频率,依据各IMF分量瞬时频率的均值将分解得到的IMF划分成较高频和低频2类新的分量,选取适合于各分量特征的预测模型分别进行预测,以消除局部随机性对预测精度的影响,结合自回归(AR)、径向基函数(RBF)神经网络和支持向量机(SVM)3种预测模型实现瓦斯浓度预测.实例分析表明:应用该方法所得预测结果比较准确,降低了预测复杂度,提高了预测精度.     

FTABLE Generation Method Effects on Instream Fecal Bacteria Concentrations Simulated With HSPF1

Abstract: Computer simulation models are used extensively for the development of total maximum daily loads (TMDLs). Specifically, the Hydrological Simulation Program‐FORTRAN (HSPF) is used in Virginia for the development of TMDLs for bacteria impairments. HSPF estimates discharge from a reach using function tables (FTABLES). The FTABLE relates stream stage, surface area, and volume to discharge from a reach. In this study, five FTABLE estimation methods were assessed by comparing their effect on various simulation outputs. Four “field‐based” methods used detailed cross‐sectional data collected via site surveys. A fifth “digital‐based” method used digital elevation data in combination with the Natural Resources Conservation Service Regional Hydraulic Geometry Curves. Sets of FTABLEs created using each method were used in simulations of instream bacteria concentration for a Virginia watershed. Several statistics relating to instream bacteria including long‐term average concentration, die‐off, and the violation rate of Virginia’s bacteria criterion were compared. The pair‐wise Student’s t‐test was used for the comparison. The HSPF simulations that used FTABLES estimated from digitally based data consistently produced significantly higher long‐term average instream fecal bacteria concentrations, significantly lower instream fecal bacteria die‐off, which is related to differences in residence time in the streams, and significantly higher water quality criterion violation rates.     

从萘系高效减水剂中分离硫酸钠的清洁工艺

对萘系高效减水剂中硫酸钠的分离提出了一种用有机醇作为促析剂的分离工艺,在较高温度和较高的水剂总浓度下,按水剂质量的３０％加入促析剂,可使粉剂中硫酸钠的质量分数降至３％以下,促析剂可回收利用。该工艺无三废排放,工艺简单,可望取代传统的脱硫酸钙法。     

MULTIPLICATIVE,SEASONAL ARIMA MODELS FOR LAKE ERIE AND LAKE ONTARIO WATER LEVELS1

ABSTRACT: Federal agencies in the U.S. and Canada continuously examine methods to improve understanding and forecasting of Great Lakes water level dynamics in an effort to reduce the negative impacts of fluctuating levels incurred by interests using the lakes. The short term, seasonal and long term water level dynamics of lakes Erie and Ontario are discussed. Multiplicative, seasonal ARIMA models are developed for lakes Erie and Ontario using standardized, monthly mean level data for the period 1900 to 1986. The most appropriate model identified for each lake had the general form: (1 0 1)(0 1 1)₁₂. The data for each lake were subdivided by time periods (1900 to 1942;1 943 to 1986) and the model coefficients estimated for the subdivided data were similar, indicating general model stability for the entire period of record. The models estimated for the full data sets were used to forecast levels 1,2,3, and 6 months ahead for a period of high levels (1984 to 1986). The average absolute forecast error for Lake Erie was 0.049m, 0.076m, 0.091 m and 0.128m for the 1, 2,3, and 6 month forecasts, respectively. The average absolute forecast error for Lake Ontario was 0.058m, 0.095m, 0.120m and 0.136m for the 1,2,3, and 6 month forecasts, respectively. The ARIMA models provide additional information on water level time series structure and dynamics. The models also could be coordinated with current forecasting methods, possibly improving forecasting accuracy.     

某油田加油站作业人员职业健康状况分析

从加油站作业人员接触的主要职业病危害因素入手,重点对加油站油气防护设施、个人防护用品、工作制度等进行职业卫生现场调查,同时,根据对作业人员职业性健康检查结果和作业场所空气中汽油及苯的浓度检测结果,分析加油站作业人员的健康状况和长期接触成品汽油对作业人员健康的影响。结果表明,加油站人员作业过程中接触的汽油及苯系物对员工健康可能构成危害,但若加强职业健康监护及个体防护,就能有效预防汽油及苯系物所带来的职业危害。     

渔业资源动态的综合时序模型

渔业资源的变动是一个随机过程,它既有确定性趋势,又有随机波动的特性。论文把灰色系统方法和时序分析相结合,用灰色GM(1,1)模型提取渔业资源变动中的确定性趋势,用时序模型描写它的随机波动,从而建立渔业资源动态的灰色时序模型。考虑到渔业资源的变化受到捕捞强度的影响,同时建立渔获量和单位捕捞努力量的渔获量(CPUE)关于捕捞努力量的二元时序模型。利用灰色时序模型和多元时序模型,对舟山渔场渔业资源的动态变化进行分析和预测,结果表明灰色时序模型和多元时序模型能很好地拟合渔业资源的变动过程,精确地预测渔业资源未来的状况。     

SB-A型系列造纸白水回收塔应用研究

介绍SB -A型系列造纸白水回收塔的结构、性能及适用的工艺条件 ,实践表明 ,SB -A型系列造纸白水回收塔回收浆料效率高 ,效益显著     

遗传双线性模型在海洋冰情预测中的应用

提出了一套建立双线性模型（ＢＭ）的简便方案。用作者研制的加速遗传算法可同时估计ＢＭ模型各参数,成功地解决了ＢＭ建模这一难题,为ＢＭ模型的广泛应用提供了强有力的工具。实例的计算结果说明,这套方法在海洋冰情预测中是可行而有效的,通过利用预测过程中产生的残差信息进行反馈矫正,保证了ＢＭ模型高的拟合粗度和稳健的预测性能,增强了ＢＭ对复杂非线性动态系统的适应性。该方案具有一般性,在各种非线性时序动态预测中具