多级雾化超重力旋转床中气液传质实验研究

利用传热强化与过程节能教育部重点实验室开发的多级雾化超重力旋转床，采用化学吸收的方法测定了其在不同操作条件下的体积传质系数，并根据双膜理论建立了旋转床中气液两相之间的传质模型．实验结果表明，多级雾化超重力旋转床气液两相间的体积传质系数随气液流量的增加而增大．文中还从实验数据中归纳出了液滴内的传质系数方程，指出丝网层的雾化使液滴在离心力的作用下高速旋转进入雾化区，由于液滴内循环非常剧烈，从而使多级雾化旋转床的液滴内传质系数较高．     

宗法颠覆论纲——传媒对中国社会的影响

宗法制在中国盛行数千年,宗法思想则影响至今。传播媒介在宗法社会演变中一直有其不可忽视的作用。被纳入西方现代化进程以后,传媒潜在地扮演了颠覆宗法社会的角色。     

Seismogenesis and occurrence of earthquakes as observed by temporally continuous gravity variations in China

In the last decade and a half, a number of earthquakes of magnitude 4–5 have occurred in the Beijing-Tianjin-Tangshan-Zhangjiakou (BTTZ) region. On the basis of the analysis of the temporally continuous gravity variation data principally from the Baijiatuan (BJTN) semi-permanent gravity base station, a general picture of gravity variation related to the seismogenesis and occurrence of earthquakes has emerged. As gravity variation is generally observed on the earth’s surface, the predominant influence is that of the near-surface groundwater. The subsurface fluids are distributed throughout all depths in the crust and respond to the seismogenic processes of earthquakes as well. The influence of the subsurface fluid on gravity variation is, therefore, of equal importance. The fluids, which include the near-surface groundwater and the subsurface fluids distributed throughout all depths in the crust, play a more important role in the gravity variations in terms of the seismogenesis and occurrence of earthquakes than previously realized. The abundance of accumulated data shows that the dilatancy instability (IPE) model seems not applicable at least to the seismogenesis and occurrence of earthquakes in the BTTZ region. In order to reflect the physical reality, the earlier proposed combined dilatancy model requires modification. The seismogenic area in the BTTZ region may be modelled as a large pre-stressed volume of a fluid-filled poroelastic medium, including not only the pre-stressed volume surrounding the impending rupture zone but also the volume containing the rupture of the fault zone itself. The pre-stressed volume outside the impending rupture zone is under a state of relatively small change of the pre-existing regional tectonic stress, while the volume containing the impending rupture zone is an induced region of very high local stress concentration, and/or pore over-pressure. The calculated gravity variations based on the modified combined dilatancy model (MCDM) with the known physical parameters of the region resemble the observed residual gravity variations. Apparently the residual gravity variations, in addition to responding to the deep-seated seismogenesis and occurrence of earthquakes, predominantly respond to the near-surface groundwater, and the subsurface fluids, which themselves also respond to the seismogenesis and occurrence of earthquakes. On the basis of comparison between the calculated MCDM gravity variations and the observed residual gravity variations, the change of the regional tectonic stress field for the earthquakes of magnitude 4–5 in the BTTZ region could be approximately estimated to be in the neighbourhood of 5%–7%. It is apparent that simultaneously monitoring the temporally continuous variations of the near-surface groundwater, subsurface fluids, and gravity coupled with modelling would provide vital information on the history and evolution of the seismogenic processes about 10 months to 1 year prior to the occurrence of an earthquake of magnitude 4–5 and tens of years prior to that of an earthquake of magnitude 7–8 such as the Haicheng earthquake in 1975 and the Tangshan earthquake in 1976 in the BTTZ region. These earthquakes of magnitude 4–5, which so far have occurred in the BTTZ region, may well be the precursory events to a larger earthquake. L-DEO, Columbia University, Contribution No. 5613.     

东北地区农业适应气候变化技术体系框架研究

 随着气候变化及其所带来的影响日益显著,目前适应气候变化越来越成为全球关注的热点问题。东北地区是中国重要的粮食生产基地,气候变化影响下东北农业生产变化将直接引起中国粮食安全问题。从气候变化角度着手,梳理了气候变化对东北农业影响的关键问题,分析指出近年来气候变化对东北地区农业4个最突出的影响：热量资源呈现增加趋势,旱涝灾害频次与强度增大,极端低温冷害事件下降,农业病虫害损失显著加重。针对这4个关键问题,从作物抗逆品种选育、作物应变耕作栽培、农田基本建设、种植结构调整、病虫害防治、农业保险等不同方面形成东北农业适应技术体系框架。     

2070t/h超临界对冲火焰锅炉飞灰含碳量偏高原因分析

针对湖南某电厂2 070t/h超临界对冲火焰锅炉燃用运行煤种出现的飞灰含碳量偏高的现象,对其锅炉进行了热态调整试验,研究了炉膛氧量、负荷、燃尽风量和煤粉细度的变化对飞灰含碳量的影响。研究结果表明,炉膛氧量、负荷、燃尽风量和煤粉细度的变化对飞灰含碳量有较大影响。负荷增加、煤粉细度减小,飞灰含碳量降低;燃尽风量和炉膛氧量过低或过高都会使飞灰含碳量升高,运行中炉膛氧量和燃尽风量存在一个最佳值;而且,燃尽风对飞灰含碳量的影响与负荷有关。依此对该锅炉运行进行优化调整,使飞灰含碳量降低到4.5%以下。     

基于3DS Max的钻井设备仿真系统的开发

为提高钻井工技能培训效率, 避免时间地点的限制, 设计并制作了基于3DS Max的钻井设备仿真系统。以各种钻井设备为仿真对象, 通过精模与简模相结合的方式创建3D模型, 利用3D动画技术对模型添加动画, 对钻井设备进行分段分结构渲染, 三维仿真以AVI(Audio Video Interleaved)视频格式输出, 通过后期整合, 形成动画、 声音和文字一体的视频教程。该系统在一定程度上提升了钻井公司技术培训手段, 降低了钻井公司事故发生率。     

重力有压流长距离输水可靠性模拟

以重力有压流长距离输水系统为研究对象,采用水厂需水量满足程度作为系统可靠性的量化指标,建立输水系统可靠性模型,模拟分析了连通管间距对输水系统可靠性的影响.算例结果表明,随着连通管数目的增加,系统可靠度趋于稳定;同一连通管间距下,输水距离越大,系统可靠度越低;随连通管间距的减小,输水距离导致的可靠度差距逐渐减小.在保证输水系统可靠度要求的前提下,定量测算了不同输水距离下连通管间距的参考值,为科学设计长距离重力有压流输水系统,提高系统可靠性提供依据和参考.     

液压挖掘机自适应模糊滑模控制的研究与仿真

为了解决滑模控制中的抖振问题,设计了自适应模糊滑模变结构控制器.为了使滑模控制的等效控制不依赖于挖掘机工作装置的精确数学模型,引入自适应模糊控制连续逼近等效控制器,增强对不确定性控制系统的鲁棒性,并将其用于液压挖掘机工作装置的轨迹跟踪控制.控制规则包括等效控制、切换控制和调整控制三个部分.在Matlab7.4/Simulink环境下对自适应模糊滑模控制进行了挖掘轨迹的跟踪仿真,给出了跟踪性能及控制输入.     

基于SVM的在线无监督入侵检测系统

针对已有的审计日志, 在使用具有实时数据处理能力的频度加权算法计算私有程序运行时, 对每个进程中相异系统调用的频度取值. 将得到的进程向量集合进行线性扫描, 再根据向量间的距离关系为进程向量添加表示数据“正常”或“异常”标号, 在无人为干预的情况下取得SVM(Support Vector Machine)训练数据. 最后通过支持向量机计算用于监测目标系统的程序正常行为轮廓, 从而构造一个切实可行的在线且无 需人为干预的入侵检测系统.     

Augmented Half‐Life Estimation Based on High‐Frequency Data

Half‐life estimation has been widely used to evaluate the speed of mean reversion for various economic and financial variables. However, half‐life estimation for the same variable are often different due to the length of the annual time series data used in alternative studies. To solve this issue, this paper extends the ARMA model and derives the half‐life estimation formula for high‐frequency monthly data. Our results indicate that half‐life estimation using short‐period monthly data is an effective approximation for that using long‐period annual data. Furthermore, by applying high‐frequency data, the required effective sample size can be reduced by at least 40% at the 95% confidence level. Copyright © 2015 John Wiley & Sons, Ltd.