Experimental investigation of gas-liquid flow in a vertical venturi installed downstream of a horizontal blind tee flow conditioner and the flow regime transition

A venturi device is commonly used as an integral part of a multiphase flowmeter (MPFM) in real-time oil-gas production monitoring. Partial flow mixing is required by installing the venturi device vertically downstream of a blind tee pipework that conditions the incoming horizontal gas-liquid flow (for an accurate determination of individual phase fraction and flow rate). To study the flow-mixing effect of the blind tee, high-speed video flow visualization of gas-liquid flows has been performed at blind tee and venturi sections by using a purpose-built transparent test rig over a wide range of superficial liquid velocities (0.3–2.4 m/s) and gas volume fractions (10–95%). There is little ‘homogenization’ effect of the blind tee on the incoming intermittent horizontal flow regimes across the tested flow conditions, with the flow remaining intermittent but becoming more axis-symmetric and predictable in the venturi measurement section. A horizontal (blind tee) to vertical (venturi) flow-pattern transition map is proposed based on gas and liquid mass fluxes (weighted by the Baker parameters). Flow patterns can be identified from the mean and variance of a fast electrical capacitance holdup measured at the venturi throat.     

LNG冷量优化集成利用技术

我国将相继在沿海地区建成多个LNG接收站，每年将进口数以千万吨计的LNG，同时携带数着巨额冷量，而这些冷量可用于发电、空气分离、制造干冰、低温冷库等众多领域。基于国外LNG冷量利用现状，指出我国即将展开和实施此项技术还存在着：过程火用损较大，缺乏系统、全面的LNG冷量利用技术的研发指导机制，以及宏观调控力度薄弱等问题，进而提出了发展LNG冷量的集成利用方案，可为此类技术的研发利用提供新思路。以福建即将进口的LNG为例，模拟了空气分离与干冰制备的集成工艺流程，结果表明：福建每年进口的260×10⁴t LNG可以冷却290×10⁴t空气，相当于60000 m³/h的氧气制备规模，还可以生产100×10⁴t的干冰，其过程火用损较小；其剩余的高温位冷量可应用于低温冻结库或冰灯等项目，这对主体装置的实施效果和过程火用损的影响较小。该技术的优点在于可灵活控制冷却空气的液化率，基本不用冷却循环水，流程简单，设备投资少，能耗低等。     

Reciprocal Relationships Between Collective Efficacy and Team Performance in Women's Ice Hockey.

This study examined reciprocal relationships between collective efficacy and team performance over a season of competition in women's intercollegiate ice hockey within weekends where the opponent was constant for 2 games. Collective efficacy beliefs within 12 teams were assessed prior to both games for at least 7 weekends. Team performance indexes produced an overall measure of performance for each game. The average influence of Saturday collective efficacy on Saturday performance was moderate and positive after controlling for Friday performance. The average influence of Friday performance on Saturday collective efficacy was small and positive after removing the influence of Friday collective efficacy from Friday performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Critical-point drying versus freeze drying for scanning electron microscopy: a quantitative and qualitative study on isolated hepatocytes

Critical-point drying and freeze drying were compared both quantitatively and qualitatively as preparative procedures for scanning electron microscopy. Isolated hepatocytes were used as model cells. Nomarski differential interference contrast microscopy was used for light microscopic measurements of the hepatocytes in the unfixed, the glutaraldehyde fixed, the glutaraldehyde + OsO₄ fixed, the critical-point dried and the freeze dried states. Critical-point dried hepatocytes were found to shrink to 38% of glutaraldehyde + OsO₄ fixed volume, whereas optimal freeze dried hepatocytes (frozen in water saturated with chloroform and freeze dried at 183 K for 84 h) were found to shrink to 51% of glutaraldehyde + OsO₄ fixed volume. Transmission and scanning electron micrographs of the critical-point dried cells showed well-preserved ultrastructure and surface structure. Micrographs of the freeze dried cells showed ultrastructure destroyed by internal ice crystals and surface structure destroyed by external ice crystals. Double-fixed isolated hepatocytes were shown to swell during storage in buffer and to shrink during storage after critical-point drying. For low magnification scanning electron microscopy (up to about 3000 times) both critical-point drying and freeze drying can be used. However, for high magnification scanning electron microscopy, critical-point drying is superior to freeze drying.     

Characterization of dynamic behavior of a spout-fluid bed with Shannon entropy analysis

Differential pressure fluctuation time series were obtained at different locations in a two-dimensional spout-fluid bed with a cross section of 300 × 30 mm and height 2000 mm. Shannon entropy analysis of differential pressure fluctuations was developed to characterize the dynamic behavior. Effects of two important operating parameters (spouting gas velocity and fluidizing gas flow rate) on the Shannon entropy were examined. It was demonstrated that a spout-fluid bed at a high spouting gas velocity or fluidizing gas flow rate was a deterministic chaos system since the Shannon entropies at all bed locations increased sharply and asymmetric unstable flows occurred. Shannon entropies were found to be significantly different at various bed locations. Shannon entropies of different flow regimes were distinct, so they were used to identify the flow regimes. The results show that the Shannon entropy helps to grasp the complex characteristics of dynamic behavior in spout-fluid beds.     

黄河2007年汛前调水调沙生产运行分析

对黄河2007年调水调沙生产运行情况进行了分析,结果表明:本次调水调沙取得了下游河槽全线冲刷、主河槽最小平滩流量由调水调沙前的3 500 m3/s增大到3 630 m3/s和人工塑造异重流成功等良好效果。取得的主要收获有:①进一步积累了人工塑造异重流的经验;②加深了对下游河道水沙演进规律的认识;③为河道整治工程设计提供了原型观测数据;④再次证明调水调沙作为扩大下游河道排洪能力、处理黄河泥沙、维持黄河健康生命的措施之一是行之有效的。     

单桩腿有限元分析

为保证桩腿在冬季冰区海域的安全使用,对桩腿结构进行冰载荷作用下的强度分析。应用ANSYS软件建立桩腿、地基、冰相互作用的仿真计算模型,实现桩腿的力学分析。对桩腿进行了强度校核,计算出冰载荷作用下桩腿的变形及其应力状态。计算结果表明,桩腿在此冰载荷作用下强度满足安全要求。     

Satellite SAR Remote Sensing of Great Lakes Ice Cover,Part 2. Ice Classification and Mapping

During the 1997 winter season, shipborne polarimetric backscatter measurements of Great Lakes (freshwater) ice types using the Jet Propulsion Laboratory C-band scatterometer, together with surface-based ice physical characterization measurements and environmental parameters, were acquired concurrently with Earth Resource Satellite 2 (ERS-2) and RADARSAT Synthetic Aperture Radar (SAR) data. This polarimetric data set, composed of over 20 variations of different ice types measured at incident angles from 0° to 60° for all polarizations, was processed to radar cross-section to establish a library of signatures (look-up table) for different ice types. The library is used in the computer classification of calibrated satellite SAR data. Computer analysis of ERS-2 and RADARSAT ScanSAR images of Great Lakes ice cover using a supervised classification technique indicates that different ice types in the ice cover can be identified and mapped, and that wind speed and direction can have an influence on the classification of water as ice based on single frequency, single polarization data. Once satellite SAR data are classified into ice types, the ice map provides important and necessary input for environmental protection and management, ice control and ice breaking operations, and ice forecasting and modeling efforts.     

NUMERICAL SIMULATION OF STREAMBED HEAT TRANSFER

１．　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｓｉｍｕｌａｔｉｏｎｏｆｓｔｒｅａｍｗａｔｅｒｔｅｍｐｅｒａｔｕｒｅｉｓｓｉｇｎｉｆｉｃａｎｔｌｙｉｍｐｏｒｔａｎｔｆｏｒｔｈｅｓｔｕｄｙｏｆｎｕｍｅｒｉｃａｌｍｏｄｅｌｉｎｇｏｆｒｉｖｅｒｉｃｅｐｒｏｃｅｓｓｅｓ［１］　．Ｈｉｓｔｏｒｉｃａｌｌｙ，ｔｈｅｍａｔｈｅｍａｔｉｃａｌｍｏｄｅｌｉｎｇｏｆｔｈｅｔｒａｎｓｐｏｒｔａｎｄｆａｔｅｏｆｈｅａｔｉｎａｗａｔｅｒｂｏｄｙｈａｓｂｅｅｎｔｈｅｓｕｂｊｅｃｔｏｆｅｘｔｅｎｓｉｖｅｓｔｕｄｙｆｏｒｖａｒｉｏｕｓｒｅ…     

依靠弯道控导河势流路

在天然河道中，河势演变虽具有一定的随机性，但仍有一定的规律可循，在一个河段内，一般可归纳出2－3条基本流路，为控制河势变化，需要选择出一条基本流路进行河道整治，当连续发生枯水期或洪水期时，部分河段的河势可能出现大的变化，为防止不利河势向下游传播，可修建较长的龙头弯道工程，利用龙头弯道工程分段调整，控导河势，保持河势稳定。