采场通风方式与瓦斯运移规律研究

采场是煤矿生产的核心地带,而采场通风系统是确保采场作业安全,创造良好生产环境的重要环节。本文以采场风流流动及瓦斯运移理论为基础,通过现场试验、模型模拟试验及计算机模拟研究等方法,着重研究了中国常用的和有发展前途的走向长壁后退式U型通风方式、U+L型通曲方式、后退式Y型通风方式条件下采场风流流动及瓦斯运移规律。     

基于BP神经网络的矿车运行时矿井摩擦阻力的预测*

为了快速有效地确定矿车等运输设备在巷道内运行时矿井摩擦阻力的变化情况,克服模拟软件计算量和现场实测工作量大的问题,以巷道风流速度、矿车运行速度、阻塞比、矿车长度4个矿车运行时巷道摩擦阻力的影响因素作为切入点,采用动网格技术模拟得到矿车在巷道内运行时有关矿井摩擦阻力的数据,以此为样本构建基于BP神经网络的矿井摩擦阻力预测模型,运用MATLAB软件进行网络训练,并将BP神经网络预测值与FLUENT模拟值进行对比。研究结果表明:BP神经网络结构比较简单,能以较快速度收敛,预测值与模拟值最大误差在7%以内,该神经网络模型用于求解矿车等运输设备在巷道内运行时摩擦阻力的变化情况是可行的。     

磁絮凝预处理景观湖泊的补水试验研究

为了快速净化景观湖泊的补水,采用磁絮凝法对Ⅴ类甚至劣Ⅴ类河道水体进行预处理,设计正交试验,分析了絮凝剂(PAC)、助凝剂(PAM)以及磁铁粉的投加量对预处理效果的影响,并利用正交试验法和多指标综合评分法进一步优化磁絮凝预处理工艺参数,结果表明最佳工艺参数为:磁铁粉加入量100 mg/L,PAC投加量150 mg/L,PAM投加量2 mg/L。在此最佳工艺参数下,进行验证试验,COD去除率达到50.39%,TP去除率为96.65%,浊度去除率为91.59%,氨氮去除率为6.31%,除氨氮外,其他各指标基本均能达到地表水环境Ⅲ类水体标准,达到了预处理目的,为后续深度净化减轻负荷压力。     

A numerical study on the feasibility and efficiency of point smoke extraction strategies in large cross-section shield tunnel fires using CFD modeling

The strategy of smoke control is of high importance for the design process of tunnels, especially for long and large cross-section tunnels. The South Hongmei Rd. Tunnel (SHT) located in Shanghai, China, is a 3.39 km long shield TBM (tunnel boring machine) tunnel with an external diameter of 14.5 m. The point smoke extraction system was proposed initially as the main ventilation strategy during a tunnel fire. To investigate the fire characteristics in the tunnel and develop appropriate smoke control strategies, a series of numerical 3D Computation Fluid Dynamics (CFD) simulations were conducted. Three fire scenarios, namely 5 MW, 20 MW and 50 MW, were modeled to evaluate the point extraction system. The gas temperatures, the stratification of the smoke, air temperature, minimum visibility etc., during the smoke spreading of a fire were analyzed. Based on the results of the simulation, the smoke extraction strategies according to fire scale and fire location were proposed for fire extinguishing. It was found that the three-point extraction opening strategy can control the smoke better than two-point extraction opening strategy under various fire scales, especially under serious fire scenario. From the results, damper openings ranged at closer intervals were found more efficient in two-point extraction system. Besides, placing the damper openings in the longitudinal direction can improve the efficiency of smoke extraction. It also results in reduction of the quantity of prefabricated members of duct slab and the process of assembly will be simplified during the construction.     

火电厂FGD装置性能试验有关问题的探讨

针对目前我国还没有专门针对烟气脱硫(FGD)装置性能试验规程的情况,对于火电厂FGD性能试验的内容和标准、现场测量的特点、测点布置和测量方法的选择、试验工况和试验时间的要求等问题,进行了介绍和探讨,以期为脱硫装置性能试验的实践提供一些建议和参考.     

The Relation Between Sandstorms and Strong Winds in Xinjiang,China

With observational data spanning 1961–1999 from 90 meteorological stations in Xinjiang, China, the spatial and temporal characteristics of sandstorms and strong winds, and the contribution of strong winds to the occurrence of sandstormsare analyzed. Moreover, the dominant wind direction and minimumwind speeds during sandstorm periods are discussed. The research shows that although possessing similar climatic trends, sandstorms and strong winds in Xinjiang have opposite geographical distributions, i.e. places with more sandstorms show fewer strong winds. The contribution of strongwinds to sandstorms in northern Xinjiang is larger than that insouthern Xinjiang. The dominant wind directions clearly indicatethe paths of the weather systems that introduced the sandstorms.The minimum wind speeds in the sandstorms were over 10 ms^-1in northern and eastern Xinjiang and in the Turpan and Yanqi Basins of southern Xinjiang. In Tarim Basin of southern Xinjiang,however, the minimum wind speed was about 6–8 ms^-1, and even 6 ms^-1 at its southern edge.     

QUALITY OF HYDROMETEOROLOGICAL DATA IN COLD REGIONS1

ABSTRACT: Many users of hydrometeorological records are not aware of the number of inconsistencies and biases that occur in hydrometeorological records. Examples are presented illustrating how the exposures of sites for measurement of precipitation, wind, snow on the ground, and evaporation determine to a large extent how useful the records are for estimating areal conditions. For areas where precipitation in the form of snow produces a significant portion of the runoff, a smaller number of quality records may be more valuable for modeling than a much larger number of records of lower quality. Information is presented to show that the overall value of an operational hydrometeorological network is dependent upon how consistent and representative of average conditions the collected records are, especially for mountainous areas in cold regions.     

一个研究街道峡谷流场及浓度场特征的三维数值模式

目前，研究街道峡谷内流场及机动车排放污染物的扩散行为特征所采用的主要方法为：采用野外测试法和物理模拟法，而采用三维数值模拟方法研究此问题的工作很少。本文创建了一个研究微尺度街道峡谷内流场及机动车排放污染物扩散特征的三维数值模式，即首次采用伪不定常方法，利用K——E闭合方案，建立了一个模拟城市街道峡谷内流场及污染物扩散特征与街道峡谷风场、街道几何结构及两侧建筑物高度对称性之间的复杂关系的三维数值模式。经过与实际监测资料及风洞实验对比，结果表明此三维模式具有较好的模拟精度，能够很好模拟峡谷内的风场及街谷几何结构对街道峡谷内流场及浓度场特征的影响，有很强的实用性。     

基于非线性屈服准则及主应力判据的圆形巷道围岩岩爆过程的数值模拟

鉴于考虑拉伸截断的线性莫尔-库仑屈服准则不能考虑岩石在高应力条件下的非线性屈服特征,根据虎克-布朗本构模型,将上述屈服准则在受压区的线性屈服函数修改为非线性形式。采用3种岩爆的主应力判据,判别圆形巷道开挖之后围岩中各种级别岩爆的分布及演变规律。计算采用"先加载,后挖洞"的方式,岩石服从弹—脆—塑性本构模型。研究发现,发生高级别岩爆的单元数少于发生低级别岩爆的单元数;轻微岩爆区的形态更接近于塑性区及剪切应变增量的高值区。根据巴顿判据,发生重岩爆的单元数较多,而且主要发生的是拉伸岩爆;根据陶振宇判据,发生轻微及中等岩爆的单元数均多于根据谷明成-陶振宇判据判别的结果。上述两种判据判别的结果均表明,在不考虑拉伸岩爆的条件下,只有位于围岩内部的单元才有可能发生高级别的岩爆,而位于巷道表面的单元一般仅发生轻微岩爆。     

Stand-alone wind power system with battery/supercapacitor hybrid energy storage

This paper presents a stand-alone wind power system with battery/supercapacitor hybrid energy storage. A stand-alone wind power system mainly consists of a wind turbine, a permanent magnet synchronous generator, hybrid energy storage devices based on a vanadium redox flow battery and a supercapacitor, an AC/DC converter, two bidirectional DC/DC converters, a DC/AC converter and a variable load. Several control strategies for the stand-alone wind power system are involved such as a maximum power point tracking (MPPT) control, a vanadium redox flow battery charge/discharge control and a supercapacitor charge/discharge control. The proposed MPPT control combines a sliding mode control with an extreme search control to capture maximum wind energy. This strategy avoids the necessity of measuring wind velocity, obtaining models or parameters of the wind turbine and calculating the differentials of the power generated from the wind power system and from the speed of the generator. The battery charge/discharge control maintains a constant DC bus voltage. When the battery charging/discharging current reaches the setting threshold, the charge/discharge control of the supercapacitor is triggered to limit the charging/discharging current of the battery. The simulation results show that the proposed method can rapidly respond to variations in wind velocity and load power.