Solids Friction Factors for Fluidized Dense-Phase Conveying

There have been numerous correlations proposed for determining a solids friction factor ( λs ) for fully suspended (dilute phase) pneumatic conveying. Currently, there are no equivalent correlations that predict λs in nonsuspension dense-phase flows. In dense-phase conveying there are two basic modes of flow: plug/slug flow, which is predominantly based on granular products, and fluidized dense-phase flow, which is more suited to fine powders exhibiting good air retention capabilities. In plug/slug type flow, the stresses between the moving plug of material and the pipe wall dominate the solid-phase frictional losses. In fluidized dense-phase flow the frictional losses are characterized as a mixture of particle-wall and particle-particle losses but are heavily influenced by the gas-solid interactions. In this paper, a series of calculations were performed on experimental data in order to estimate λs for four types of material conveyed in the fluidized dense-phase flow regime. The solids frictional factors were found to be relatively independent of particle properties for varying air and solid mass flow rates and pressure drops. The resultant pressure drop from the empirical model showed good agreement with the experimental data.     

浅淡FONST W1600系列在东北环工程中的应用

结合中国电信东北环工程的应用实践，对烽火通信FONSTW1600系列产品进行了介绍。     

城域DWDM光网络技术方案研究

主要论述了DWDM光复用、DWDM可配置光环和DWDM网状网等3种主要的DWDM城域核心组网方案，分析了各种方案的特点和应用范围。     

Friction measurement in dense phase plug flow analysis

Pneumatic conveying, employing the dense phase plug flow regimen, is largely used to transport bulk solids. This process permits the conveying of large amounts of material in economical manner with less particle and pipe degradation compared to dilute phase conveying. By using an experimental system with special measurement devices and different materials of construction and transport, the friction between the material being transported and the pipe wall, the actual motion of the particles was determined, and the degree of fluidization were estimated. This information permits more accurate modeling of dense phase plug flow providing basic parameters to insert in existing and developing models.     

点对点CWDM光纤传输系统中监控方案的实现

针对城域光纤传输网的特点，首先提出了稀疏波分复用的解决方案，并在此基础上介绍了点对点城域网CWDM光纤传输系统设备的基本结构。然后重点介绍了本系统监控方案的实现，包括系统的硬件实现和软件实现。最后对城域网光纤传输系统设备的市场前景提出了大胆的预测。     

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现代管材技术为富气密相输送工艺打开了应用的大门。在正常操作条件下，富气密相输送工艺避开了富气两相输送所带来的问题。与传统压力下的干气输送工艺相比，富气密相输送工艺的管路压降小，压缩机表现出更高的效率。富气密相输送工艺对富气的烃露点要求不高，在矿场或采油平台，一般通过常温分离得到的富气就能满足密相输送的要求，因而可以简化油田、凝析气田的气体处理工艺，节省天然气凝析液储运费用。然而，富气中较高的重烃含量也给富气脱硫、脱水带来了困难。文中分析了富气的特性，讨论了富气处理与密相输送工艺技术，简述了国外富气密相输送技术应用概况。     

Cooling of a heated surface with an impinging water spray

Several important parameters, such as liquid mass flux, droplet size distribution, droplet velocity, and heating target conditions (roughness and surface temperature) are involved in the industrial spray cooling heat transfer process. In this study, we investigated the effect of liquid mass flux, heating target roughness, and the droplet size on the droplet wall direct contact heat transfer in spray cooling phenomena. Three different conditions of surface roughness were investigated. The measurement of test surface temperature was performed using a non-intrusive method, i. e., using an infrared thermometer. The droplet size distribution of water spray was measured with Malvern 2600. The results indicated that the most influential parameters were the liquid mass flux and the surface roughness. The droplet size and the velocity played a less important role in the direct contact heat transfer because the interactions between droplets were very strong in a dense spray. The smooth surface showed the highest heat transfer among the surfaces tested. At high air pressure ([7] kPa), however, the degree of roughness did not affect much the heat transfer rate.     

融合多特征信息的密集场景人群分群检测算法

针对存在更复杂运动模式的无序运动人群密集场景,提出了一种有监督的密集场景人群分群检测算法,不仅能够实现运动前景的自动定位和跟踪,而且还能够在有先验信息的条件下准确定位分群区域。结合个体之间运动轨迹时空距离特征、运动方向特征、格兰杰因果性特征、热能图特征以及运动相关性特征,采用结构化支持向量机在训练集上进行训练,对测试集人群进行了分组测试。选用了大量真实室内外密集人群无序运动场景视频进行测试,试验结果表明,该方法对密集人群分组有较好的处理效果。     

基于整体特征的人群聚集和奔跑行为检测

建立高效完备的智能视频监控系统已经成为当今社 会的迫切需求。针对公共场所人群聚集和奔跑的两类异常行为,提出一种基于分布熵和平均 运动速度的检测方法。一方面,根据前景图像的空间分布情况,采用分布熵衡量场景中人 群的集中程度,实 现对场景中人群聚集行为的检测;另一方面,检测图像上的角点,采用光流法对这些角点进 行跟踪并提取出产 生运动的角点,进而获得运动角点在视频序列中连续两帧间的运动向量,计算出人群整体的 运动速度,从而检 测人群的奔跑行为。所提出的方法不需要对单个行人进行分割以及样本的训练。采用不同场 景和不同人群密度 下的视频对所提出算法进行验证的结果表明,本文方法可以快速、准确地进行人群异常行为 检测。     

Fluctuations in dense phase pneumatic conveying of pulverised coal measured using electrical capacitance tomography

A twin-plane electrical capacitance tomography (ECT) system has been employed to monitor the flow rate of fine coal transported by air in a 36.8 mm diameter pipe at mass fluxes of 1680 kg/m² s. The mean mass flow rate was obtained to be within <1% of the value determined from load cells. The ECT output indicated that there were two types of systematic fluctuations in the time series of mass flow rate and concentration. The frequencies of these have been obtained from power spectral density analyses. For the higher frequency fluctuations, the Strouhal number (fD_t/u_gs) was found to depend on the square root of the solids/gas momentum flux ratio. An examination of the cross-sectional distribution of solids showed that the coal was concentrated around the wall of the pipe and that the concentration fluctuated as noted above.