Relationship between EMR and dissipated energy of coal rock mass during cyclic loading process

Dynamic collapses of deeply mined coal rocks are severe threats to miners. In order to predict the collapses more accurately using electromagnetic radiation (EMR), this paper researched the energy conversion mechanism in the damage process of coal rock mass, analysed its EMR and dissipated energy, and a relationship between which was established using the voltage amplitude of EMR signal and hysteresis loop generated in the loading and unloading cycles as a bridge; then a series of cyclic loading experiments using coal samples of Junde and Xinlu coal mines from Heilongjiang province were carried out, and EMR signal released during these cycles were collected. Results show that during a whole damage process of a sample, the cumulative values of EMR energy and corresponding dissipated energy (hysteresis loop area) well subject to the form of y=aln(x)+b, whose correlation coefficients are above 0.90, and EMR signals received by different frequency antenna seldom impacted on this relationship; the total EMR energy released from the whole failure process of the samples obtained from adjacent sampling point in same mining area are different to some extent, so are the dissipated energy; compared with cyclic loading for coal rock mass orderly with the peak loads of 5 kN and 10 kN previously, the dissipated energy of direct using that of 15 kN increase 17.8%, and EMR signal is more abundant; EMR energy received in each cycle increase steadily with the improvement of load level, and in a single loading and unloading cycle, sometimes it is very rich in the unloading phase, even more than the loading one.     

PAC和PAFC对内循环连续砂滤器处理石化二级出水的影响

采用PAC（聚合氯化铝）和PAFC（聚合氯化铝铁）作为絮凝剂,探讨不同絮凝剂及其投量对于内循环连续砂滤器处理效果和滤料板结潜在趋势的影响.结果表明,PAC和PAFC投量由5mg/L升至30mg/L时,COD和SS的去除率随着投加量的增大均呈现出先升高后降低的趋势.10mg/L为试验水质下的最佳投量,在该投量下,PAC对SS和COD去除率为分别为49.7%和12.9%;PAFC对SS和COD去除率分别为50.6%和13.8%.内循环连续砂滤器主要去除的是相对分子量在3k以上的溶解性有机物,但对相对分子量1k以下的溶解性有机物去除效果不好,总DOC去除率低于5%,需进一步深度处理以满足最新的排放标准.PAFC混合液比PAC混合液黏度低,有利于缓解滤料板结.总体来看,更适合于石化二级出水的混凝剂为PAFC,最佳投量为10-15mg/L,可保障对SS高效去除同时并使内循环连续砂滤器运行更加稳定.     

Abusive supervision and feedback avoidance: The mediating role of emotional exhaustion

The occurrence of abusive supervision is steadily rising. Extant literature continues to expand the number of destructive consequences linked to such improper workplace behavior. This study tested a model linking abusive supervision to feedback avoidance through emotional exhaustion. We invoked conservation of resources theory in our examination of the role that the loss of valued resources plays in instances where abuse is perceived. Results from three rounds of matched data from 460 nurses and 220 working adults demonstrated support for our model, suggesting a mediating effect for exhaustion on the relationship between abuse and feedback avoidance. Findings also revealed that feedback avoidance was associated with subsequent exhaustion, representing a loss spiral. These findings are important as they reveal the link between a subordinate's reactions (exhaustion) and coping behavior (feedback avoidance) when supervisory abuse is perceived. Theoretical and practical implications, limitations, and directions for future research are offered. Copyright © 2012 John Wiley & Sons, Ltd.     

2种基于模式识别的环状燃气管网泄漏检测方法

为了将模式识别技术应用于环状燃气管网泄漏检测并找到合适的特征提取方法,以天津城建大学实验室环状燃气管网泄漏为例,将实验的28种工况作为测试样本,与之对应的模拟工况作为训练样本,采用提取压力图像特征向量法和节点压力矩阵法分别进行环状燃气管网的泄漏检测,采用支持向量机分类器将2种方法获得的特征向量进行训练与分类检验,进而将其分类准确率进行对比分析。研究结果表明:该2种方法均可用于环状燃气管网泄漏检测,提取压力图像特征向量法因有效地降低了特征向量的维度和数据波动的干扰,其结果更优。结合SCADA和GIS系统,可将该法应用于实际水、气、油管网泄漏检测和定位,有助于降低成本,提高检测效果。     

湿法烟气脱硫pH值闭环控制系统优化

分析了控制pH值在湿法脱硫系统运行过程中的重要性,针对部分电厂存在pH值测量误差大的问题,在研究比较各种测量方式优缺点的基础上,提出了一种改进的pH测量方式。实际应用结果表明,测量方式的改进对于优化pH值闭环控制具有重要的意义。     

COMPUTATION OF STAGE-DISCHARGE RELATIONSHIPS AFFECTED BY UNSTEADY FLOW1

ABSTRACT: The dynamic relationship between stage and discharge which is unique to a particular flood for a selected station along the river can be determined via a mathematical model based on the complete one-dimensional equations of unsteady flow, i.e., the equations for the conservation of mass and momentum of the flood wave, and the Manning equation which accounts for energy losses. By assuming the bulk of the flood wave moves as a kinematic wave, the need for spatial resolution of the flood can be eliminated, and only the time variation of either the discharge or stage at the selected station is necessary for the computation of the other. The mathematical model can be used in river forecasting to convert the forecast discharge hydrograph into a stage hydrograph which properly reflects the unique dynamic stage-discharge relationship produced by the variable energy slope of the flood discharge. The model can be used also in stream gaging to convert a recorded stage hydrograph into a discharge hydrograph which properly accounts for the effects of unsteady flow. The model is applied to several observed floods at selected stations along the Lower Mississippi, Red, and Atchafalaya Rivers. The root mean square errors between observed and computed discharges are in the range of 3 to 7 percent, values well within the accuracy of the observations. A simple, easily-applied graphical procedure is also provided for estimating the magnitude of the effect of the unsteady flow on stage-discharge ratings. As a general rule, the dynamic effect may be significant if the channel bottom slope is less than 0.001 ft/ft (about 5 ft/mi) when the rate of change of stage is greater than about 0.10 ft/hr.     

数字PID整定在环境试验设备控制过程中的应用研究

针对环境试验设备在高精度控制过程中难以达到要求，需与人工控制相结合才能精确调试的问题，提出了数字PID整定在环境试验设备控制的应用。通过比例、积分、微分三部分综合控制，以精确调试环境试验设备。     

油田污染源在线监测中反馈控制系统的设计讨论

针对油田污染源在线监测系统自动化程度不高,提出了一种基于反馈控制的在线监测系统,讨论了其在油田污染源在线监测中的应用价值,并给出控制简图和设计中可能遇到的难点。最后指出,该方法将在一定程度上提高油田污染源在线监测系统的自动化程度。     

战略环境影响评价中公众参与方法研究与案例分析

公众参与有效性是衡量战略环境影响评价质量的一个重要指标,它对于提高环境管理水平具有重要的意义。本文在对比项目环境影响评价的基础上,系统阐述了战略环境影响评价公众参与的内容、对象、方式、时机、实施主体、数据处理及信息反馈,初步建立了战略环境影响评价公众参与的方法与体系,并结合典型案例进行了战略环境影响评价公众参与的过程分析。     

基于结构参数响应的内循环流化床流体特性优化数值模拟

流化床是一种结构复杂而能量转化高效的反应器型式,为了实现系统化的内循环流化床优化设计,利用欧拉-欧拉双流体模型构建了不同结构的CFD流化床模型,在分别改变高径比、导流筒与反应器的直径比和底隙高度3个结构因素的情况下,考察流化床内全流场、局部流场、液相运动速度及气含率等气液两相流的响应特性,分析结构因素及操作因素对流体运动的内在影响,阐明工程优化设计的方向.数值模拟结果表明:高径比主要影响气液流动型态,低高径比时容易出现漩涡和返混,工程中应采用导流内构件并重视气体分布装置的合理设计;导流筒与反应器的直径比主要影响液体循环速度,存在一个合理的区间,考虑流动速度与气含率,流化床直径比可取0.6～0.8,最佳取值为0.7;底隙高度影响流化床底泥区的流体运动,应约等于流化床下降区的缝隙长度.CFD模拟可作为污染控制技术工业放大和优化设计的辅助工具.