基于模糊产生式规则的企业供电网谐振故障诊断研究与仿真

针对大型企业供配电网随机谐振故障问题进行分析研究。建立了某企业供电网铁磁谐振非线性框图模型,仿真表明系统会产生铁磁谐振。由于谐振表现形式具有一定的模糊性,引入模糊方法,建立了故障征兆的模糊隶属度函数。提出了一种故障诊断的模糊表达式,及基于模糊产生式规则的故障     

井筒气液两相流对致密气压裂水平井试井的影响

多段压裂水平井技术是目前开采致密气最常用的方法之一,在致密气压裂水平井试井测试中常常伴随着一定的产水量,井筒气液两相流会增加井筒流体的流动阻力,加大井筒流体流动对试井解释的影响.为了明确井筒气液两相流对致密气藏压裂水平井试井的影响,提高产水致密气压裂水平井的试井解释精度,建立了一种井筒气液两相流与地层渗流耦合的试井模型,采用数值方法对模型进行求解,获得了考虑井筒气液两相流的压裂水平井试井理论曲线、压力场分布及裂缝产量分布.研究结果表明:井筒气液两相流会增加试井理论曲线中压力和压力导数值,造成靠近入窗点的压力扩散要快于远离入窗点的压力扩散,引起靠近入窗点的裂缝产量要高于远离入窗点的裂缝产量.现场实例分析进一步说明,不考虑井筒两相流可能会对产水压裂水平井的试井解释结果产生很大误差,主要表现为水平井筒假设为无限大导流能力会使得拟合得到的表皮系数偏大,将测试点视为入窗点会使得拟合得到的原始地层压力偏小.所建立的考虑井筒两相流的压裂水平井试井模型为产水致密气井试井资料的正确解释提供了重要技术保障.      

Numerical well test for well with finite conductivity vertical fracture in coalbed

A new well test model is developed for the hydraulic fractured well in coalbed by considering the following aspects： methane desorption phenomena, finite conductivity vertical fractures, and asymmetry of the fracture about the well. A new parameter is introduced to describe the storage of the fracture, which is named as a combined fracture storage. Another new concept called the fracture asymmetry coefficient is used to define the asymmetry of the fracture about the well. Finite element method （FEM） is used to solve the new mathematical model. The well test type curves and pressure fields are obtained and analyzed. The effects of the combined fracture storage, desorption factor, fracture conductivity, and fracture asymmetry coefficient on the well test type curves are discussed in detail. In order to verify the new model, a set of field well test data is analyzed.     

污染区对部分打开井井底压力响应的影响

钻井造成的污染区对部分打开井的影响不同于裸眼井. 为了分析污染区对部分打开井井底压力响应的影响,建立了一种部分打开井的二维轴对称渗流模型,模型考虑了真实的污染区以及储层渗透率各向异性特征.利用有限元数值方法对模型进行求解,获得了部分打开井的井底压力响应及储层压力分布. 根据压力响应及压力分布特征,将部分打开井的压力响应过程划分为5 个流动阶段,其中早期局部径向流动和椭球流动是该类井最典型的特征. 对污染区的影响分析表明:传统方法中的表皮系数S 并不等于污染区引起的机械表皮系数S_d;无量纲井筒储存系数不能与机械表皮系数组合. 修正了传统方法中部分打开井的井底压力公式,验证了部分打开井的总表皮计算公式,为该类井的井底压力响应解释及产能预测提供理论指导.      

Magnetic-mediated hyperthermia for cancer treatment:Research progress and clinical trials

Research progress and frontiers of magnetic-mediated hyperthermia （MMH） are presented, along with clinical trials in Germany, the US, Japan, and China. Special attention is focused on MMH mediated by magnetic nanoparticles, and multifunctional magnetic devices for cancer multimodality treatment are also introduced.