基于HHT的煤岩破裂微震信号分析

微震信号处理是目前研究微震监测技术应用领域中的一个重要课题,应用ESG微震监测系统采集煤巷炮掘过程中产生的煤岩破裂微震信号,针对所采集微震信号具有明显的持续时间短、突变快等特点,选用希尔伯特黄变换(HHT)对其进行处理。HHT包括EMD分解和Hillert变换两部分,微震信号经过EMD自适应分解得出9个IMF分量和一个残余分量,对各IMF分量进行Hillert变换做出Hillert谱,从Hillert谱中得出煤岩破裂微震信号频率响应主要集中在500-800Hz,用边际能量谱加以验证得出Hillert谱在应用中的准确性,为进一步认识煤岩破裂的机理和预测煤岩动力灾害提供了有效的技术途径。     

有约束应力高温全过程后混凝土轴压力学性能试验研究

采用高温抗压试验炉进行了有约束应力作用下混凝土在经历升温、降温及冷却全过程作用后的轴压力学性能试验研究,主要研究约束应力水平和温度等级对升降温及冷却全过程中的混凝土高温变形特性与高温后混凝土强度、弹性模量和应力-应变关系等性能的影响规律。结果表明:约束应力使混凝土产生明显的残余压缩变形,且对高温后混凝土抗压强度和弹性模量有显著影响;无约束应力高温后混凝土的抗压强度随着温度的升高经历低温衰退、强度恢复、高温衰退3个阶段,n≤0.4时有约束应力混凝土也表现出相同的规律;约束应力可提高高温后混凝土的弹性模量,但其值仍明显低于常温弹性模量;有约束应力高温全过程后混凝土破坏突然,明显变脆。     

中国城市工业污染强度与经济增长耦合关系

利用幂函数模型对中国46个重点城市1993-2006年人均GDP和7项工业污染强度指标进行曲线拟合,用于描述和分析我国城市经济发展与工业污染强度的耦合状态,经模型推导提出了“效率弹性系数”,作为度量城市经济与工业污染控制协调发展程度的指标。拟合统计结果显示,中国城市工业污染强度与经济增长的关系曲线形状有明显的幂函数特征。样本城市在“曲线簇”中的位置能揭示“后发优势”以及经济-环境耦合水平优劣的信息。对样本城市效率弹性系数的统计分析证明,该系数可以作为城市经济环境管理的决策依据。     

CONSERVATION PRACTICES AND ATTITUDES AMONG MARYLAND WATER SUPPLY MANAGERS1

ABSTRACT: In addition to offsetting water supply shortages, water conservation is recognized as serving many purposes, ranging from reduced energy consumption to lower capital costs. Since the discussion of these benefits has been a recent development and has generally excluded local water supply managers, a question arises as to whether supply managers are implementing conservation programs to exploit these benefits. A survey of the managers at 35 Maryland water utilities provides insight into the prevailing attitude toward conservation in a water rich eastern state. The results indicate that most managers continue to view conservation only as a short term response to temporary supply shortages. Only 12 Maryland utilities have undertaken any form of water conservation activity and just two systems have ongoing, comprehensive conservation programs. Institutional, perceptual, economic, political, and time constraints all contribute to the managers’attitudes and general inaction. If water conservation is to be widely practiced, these issues must be addressed and the benefits attributed to conservation must be better documented and articulated to supply managers.     

A MONTHLY TIME SERIES MODEL OF MUNICIPAL WATER DEMAND1

A multivariate time series model is formulated to study monthly variations in municipal water demand. The left hand side variable in the multivariate regression model is municipal water demand (gallons per connection per day) and the right hand side contains (explanatory) variables which include price (constant dollars), average temperature, total precipitation, and percentage of daylight hours. The application of the regression model to Salt Lake City Water Department data produced a high multiple correlation coefficient and F-statistic. The regression coefficients for the right hand side variables all have the appropriate sign. In an ex post forecast, the model accurately predicts monthly variations in municipal water demand. The proposed monthly multivariate model is not only found useful for forecasting water demand, but also useful for predicting and studying the impact of nonstructural management decisions such as the effect of price changes, peak load pricing methods, and other water conservation programs.     

CO2收集封存战略及其对我国远期减缓CO2排放的潜在作用

碳收集封存(CCS)已被广泛地认为是一种潜在的、可供选择的CO₂减排方案,以稳定大气中CO₂浓度、减缓气候变化.本文介绍了CCS的3大环节：碳的捕获、运输与储存,对不同捕获技术及其技术经济参数进行分析评价,介绍了不同碳地质储存的机理、潜力与成本, 以及CCS的应用对全球减缓碳排放的作用.更新中国MARKAL模型,加入各种可能的CCS技术,特别是考虑CCS的煤间接液化以及多联产技术,以同时考虑石油安全与CO₂减排.通过设置不同的情景,应用中国MARKAL模型研究了CCS对我国远期（到2050年）减缓CO₂排放的潜在作用,结果表明,CCS技术的应用不仅可能减少我国的碳排放,降低边际碳减排成本（碳减排率50%时,下降率达45%）,减轻高减排率时对核电的高度依赖,还可能使我国更长时间地清洁利用煤炭资源（在C70情景下,2050年煤在一次能源消费中的比例可从10%增到30%）.我国应重视对CCS技术的研发以及示范项目的建设.     

青岛大气气溶胶中水溶性有机氮对总氮的贡献

有机氮是大气气溶胶中重要的氮组分,其沉降入海后不仅能够促进海洋初级生产力的增长,还可能影响海洋生态系统的群落结构.利用2008年1～12月在青岛采集的64个总悬浮颗粒物样品,分析了其中水溶性有机氮的浓度.气溶胶中有机氮的浓度为30～2 073 nmol·m-3(100～12 157 μmol·g-1),以12月浓度最高...