基于半周期预测的减摇水舱控制方法及验证

可控被动式减摇水舱能够通过气阀控制空气连通道延长了水舱的固有周期,实现宽频船舶横摇减摇.关阀时刻和关阀时间与船体横摇运动规律相关,由于船体在海浪中的随机运动难以准确计算.小波神经网络的半周期预测控制方法,预测船体横摇的下一个半周期,实时计算控制参数,拓宽减摇频带.通过半实物仿真验证,较传统的方法减摇性能有明显提升.     

大型常压锥顶贮罐的设计

以工程实例为依据，论述国内以往较少采用的大型梁柱式支承锥顶贮罐的结构，介绍了国内外相关设计标准，给出了贮罐的典型结构－斜椽，横梁和立柱的计算公式，并用Excel电子表格编制了计算书。     

A Unified Model for the Mixing of Non‐Newtonian Fluids in the Laminar,Transition, and Turbulent Region

Summary: Non‐Newtonian fluid behavior has significant influence on quantities in chemical engineering like power input, mixing time, heat transfer etc. In the laminar flow region, the concept of effective viscosity by Metzner and Otto is well established. In the transition region between laminar and turbulent flow, the existing concepts use three and even more empirical parameters to determine the specific power input. Here, a unified and general but simple approach is introduced to calculate the power input for shear thinning fluids over the whole flow region using just one empirical parameter. The Metzner‐Otto relation is obtained as a limiting case for the laminar region. The empirical parameter of the new approach is related to the Metzner‐Otto constant. The concept is validated for eight different stirrer systems. Mixing time and maximum shear rate and heat transfer can also be calculated using this approach. The new concept presented should also be applicable for other apparatuses, e.g., static mixers.

Comparison of experimental data and a curve calculated according to the new method (solid line).     

Experimental and modelling study of gas dispersion in a double turbine stirred tank

Gas dispersion in a double turbine stirred tank is experimentally characterised by measuring local gas holdups and local bubble size distributions throughout the tank, for three liquid media: tap water, aqueous sulphate solution and aqueous sulphate solution with PEG. For all these media, bubble coalescence generally prevails over breakage. Where average bubble size decreases, this can be attributed to the difference in slip velocity between different sized bubbles. Most of the coalescence takes place in the turbine discharge stream.A compartment model that takes into account the combined effect of bubble coalescence and breakage is used to simulate gas dispersion. The model predicts spatial distribution of gas holdup and of average bubble size, with average bubble size at the turbines as an input. Reasonable agreement between experiment and simulation is achieved with optimisation of two parameters, one affecting mainly the slip velocity, the other related mainly to the bubble coalescence/breakage balance. Different sets of parameters are required for each of the three liquid systems under study, but are independent of stirring/aeration conditions. The model only fails to simulate the smaller average bubble diameters at the bottom of the tank.     

储罐地震易损性数值仿真分析

为了研究储罐的抗震性能,忽略储罐罐壁的质量,将储罐中的液体质量简化为三质点体系模型,地基土由两个弹簧和两个阻尼器模拟.考虑罐体的平动和转动,建立了在水平地震激励下储罐的动力方程;给出了随机变量的概率模型和基于易损性理论的失效概率计算方法.通过对大庆某油库2×104 m3和5×104m3两种大型储罐进行数值仿真方法的地震易损性分析.结果表明:随着地震烈度的增大,储罐的易损性逐渐增大;5×104 m3储罐的抗震性能要好于2×104 m3储罐;2×104 m3和5×104 m3储罐的主要失效模式分别是抗失稳和抗提离.由此可见从多个失效模式对储罐进行地震易损性研究比从单一失效模式进行易损性研究更加科学.     

内边群抱倒装法在某工程中的应用

主要叙述了某工程应用内边群抱吊装法进行现场组对储罐施工,并与几种常用的储罐施工方法进行比对,该方法所用吊装机具采购方便,制作简单,成本低,且可以重复利用;高空作业少,安全,质量易于保证;占地少,可在较狭小的空间施工,并且适用储罐类型广,从而得出内边群抱倒装法施工的适用性更强,技术、经济效果显著．     

Investigation of Flow Patterns in Continuous‐flow Stirred Vessels by Laser Doppler Velocimetry

The flow structure of a continuous‐flow reactor stirred by a Rushton turbine was investigated by laser Doppler velocimetry for two different mean residence time‐mixing time ratios. Velocity measurements were obtained for two inlet locations, corresponding to the incoming liquid stream being fed co‐currently or counter‐currently to the flow discharged by the turbine. In all investigated configurations and for all operating conditions, it was found that the flow disruption caused by the incoming liquid stream was observable mainly in the first vessel quarter, which followed the feed‐tube plane. From comparison of the velocities encountered in the various planes in the continuous‐flow reactor to the velocities of the batch reactor, it was also concluded that it may be possible to intensify the usage of the turbine‐stirred vessel by decreasing the characteristic times ratio, without considerable flow by‐pass and/or short‐circuiting problems.     

中国特色新型智库评价体系建设思考

随着全球化、国际竞争加剧,迫切需要从党和国家事业发展全局的战略高度,把中国特色新型智库建设作为一项重大而紧迫的任务。建设中国特色新型智库关键之一便是建设符合实际情况的中国特色新型智库评价体系,这对发挥评价排名对智库有效产出的促进作用,扩大中国智库国际影响力,提高中国智库在国际公共外交上的作用具有重大的意义。本文通过简要分析国内外智库评价基本情况,思考我国智库评价过程中存在的问题并尝试给出一些建设建议。