中国东南部深源铀成矿与找矿:南岭铀成矿带讨论

对前人深源热液金属元素(包括铀)和铀成矿文献的综述可以得出:地幔流体-重大地质事件-成矿构造是深源铀成矿靶区勘查模式。探讨了南岭铀成矿带的成矿潜景和深层勘查方法,提示构造地球化学、金属活动态提取技术作为该区深源找铀矿方法所起的重要作用。     

Characteristic properties of cutting fluid additives derived from the adducts of diamines and acid chlorides

A number of N,N′-diacylalkyldiamines were prepared from the reaction of acid chlorides with 1,8-diaminooctane and 1,12-diaminododecane and screened for anti-rust properties and antimicrobial activity in spent coolants of water-based cutting fluids. Aqueous solutions of N,N′-dihexanoyl-1,8-diaminooctane and N,N′-isobutyroyl-1,12-diaminododecane showed good anti-rust properties for water-based cutting fluids. Aqueous emulsions of N,N′-dibutyroyl-, dipentanoyl-, dihexanoyl- and dioctanoyl-1,12-diaminododecane showed good lubricities and antimicrobial activity for water-based cutting fluids.     

UCM流体的最小二乘有限元解法

提出了求解UCM流体的最小二乘有限元方法。将稳态不可压缩蠕动流的UCM本构方程,利用速度和应力的近似值进行线性化。建立由所有方程残量的L2范数加权和构造的目标泛函,将微分方程组的求解转化为目标泛函的极小化问题。利用目标泛函对应的欧拉-拉格朗日方程建立迭代格式,最后使用有限元方法求解迭代方程。     

腈纶皂化制备电流变液悬浮粒子的研究

为了制备无水电流变液用悬浮粒子,研究了腈纶在碱性条件下的多相水解。详细考察了皂化试剂氢氧化钾的用量,皂化时间和温度等皂化条件对皂化程度的影响;讨论了氰基转化过程。研究结果表明,在皂化初期,腈纶分子链上的氰基转化为酰胺基,然后缓慢转化为羧基。给出了一条制备无水电流变液用悬浮粒子的方法,并初步考察了该类电流变液的控光特性。     

温度和应变频率对电流变体（ER）的力学参数的影响

通过对玉米粉／玉米油电流变体（ＥＲ）的力学参数测试，研究了电场强度（Ｅ）、温度（Ｔ）和应变频率（ｆ）对ＥＲ储能模量（Ｇ′）、耗散模量（Ｇ＂）及粘度系数（η′、η＂）的影响。实验结果表明：Ｇ′随Ｅ和ｆ的增大而增大；Ｇ＂随Ｅ的增大而增大，而随ｆ的变化具有峰值特征，最大值发生在１５～３０Ｈｚ之间；η′、η＂随Ｅ和ｆ的变化与Ｇ′、Ｇ＂的变化趋势相同；而温度的升高均使Ｇ′、Ｇ＂、η′和η＂值降低。     

Forced convection in cross flow of power law fluids over a tube bank

The forced convective heat transfer characteristics for incompressible power-law fluids past a bundle of circular cylinders have been investigated numerically. The cylinder-to-cylinder hydrodynamic interactions have been approximated via a simple cell model. The momentum and energy equations have been solved using a finite difference based numerical method for a range of physical and kinematic conditions. The role of the two commonly used thermal boundary conditions, namely, constant temperature or constant heat flux, on heat transfer characteristics has also been studied. Extensive numerical results elucidating the effect of shear-thinning viscosity on the values of Nusselt number have been obtained for Peclet numbers ranging from 1 to 5000, Reynolds number in the range 1-500, flow behaviour index 1?n?0.5 and three values of voidages, namely, 0.4, 0.5 and 0.6, typical of tubular heat exchangers and tube banks. Under all conditions, varying levels of enhancement in Nusselt number are observed due to shear-thinning behaviour. The surface averaged Nusselt number shows strong dependence on the values of voidage, power-law index, Reynolds and Peclet numbers. The paper is concluded by presenting comparisons with the scant experimental results available in the literature.     

超临界条件下化学反应最新研究进展

Chemical reactions (such as hydrogenation, hydroformylation, alkylation, esterification, etc.) at supercritical conditions afford opportunities to manipulate the solubility of reactants and products, to eliminate interphase transport limitations in the reaction systems, and to be beneficial to the environment. This review concentrates on the most recent developments after 2001 with only a brief summary of pioneering research work before 2001.     

Using CFD to predict the behavior of power law fluids near axial-flow impellers operating in the transitional flow regime

A computational fluid dynamics (CFD) model of flow in a mixing tank with a single axial-flow impeller was developed with the Fluent^TM software. The model consists of an unstructured hexagonal mesh (158,000 total cells), dense in the region from the surface of the impeller. The flow was modeled as laminar and a multiple reference frame approach was used to solve the discretized equations of motion in one-quarter of a baffled tank. A solution of 0.1% Carbopol in water, a shear-thinning fluid, was found to be clear enough to measure impeller discharge angles using laser Doppler velocimetry. This is the first time that impeller discharge angles have been reported in the literature for a shear-thinning fluid with a hydrofoil impeller. Rheological measurements indicated that the Carbopol solution can be characterized by the power law (K=9,n=0.2) under the range of shear conditions (0.1- expected near the impeller in the mixing tank. The CFD model accurately predicted the dependence of power number and discharge angle on Reynolds number (as predicted by Metzner and Otto), for an A200 (pitched blade turbine or PBT) and an A315 (Hydrofoil) impeller operating in the transitional flow regime (Reynolds numbers: 25-400) with glycerin and 0.1% Carbopol solutions. Subsequently, the results of a systematic CFD study with power law fluids indicated that the power number and discharge angle of an axial-flow impeller in the transitional flow regime depends not only on the Reynolds number (as determined by Metzner and Otto's method) but also on the flow behavior index n. Consequently, an alternative to Metzner and Otto's method was pursued. The results of converged CFD simulations indicate that the near-impeller “average shear rate” increases not only with increasing RPM (as proposed by Metzner and Otto), but also with decreasing flow behavior index (n) and discharge angle in the transitional flow regime. Considering this result, an improved method of estimating the power number and discharge angle for power law fluids in the transitional flow regime is proposed.     

Multicomponent diffusion in phase-separating polymer blends with different frictional interactions: a mean-friction model

We present a compact formula for describing the mean frictional forces acting on a molecule in multicomponent systems. The friction-based diffusion theory of Zielinski and Hanley was extended to newly include the friction-average molar velocity as a reference frame. The results showed that the previous diffusion theories are unified by the friction-average concept by properly choosing the average velocity. The present model based on the diffusivity-related molar average velocity provides better predictions for the diffusive flux in a ternary miscible liquid compared to the other existing theories. The application of the model in phase-separating ternary systems revealed that the introduction of a highly diffusive third component into demixing polymer blends promotes a particular enhancement of the spinodal decomposition due to the difference in the frictional interactions between polymers.     

Shear rates investigation in a scraped surface heat exchanger

The electrodiffusion technique was performed in order to investigate the shear rate on a scraped surface heat exchanger. Microelectrodes were placed inside: the walls of the outer cylinder; the inlet and outlet bowls; the rotor and the blades. Highly viscous Newtonian fluid (Emkarox HV45 solutions) and non-Newtonian model fluid (aqueous solutions of CMC) were used. The electrodiffusion method allowed us to measure wall shear rates. Maximum shear rate was observed at the scraping surface and caused by blades scraping, high shear rate was also measured on the leading edge of the blades. In the other parts of the exchanger, shear rate remained low but the development of Taylor vortices completely modified the scraped surface heat exchangers behaviour inside the surface of the bowls. A dimensionless representation of the friction factor was established for the inner and outer wall surface of the exchanger.