Passive micromixer with baffles distributed on both sides of microchannels based on the Koch fractal principle

Since the beginning of the 21st Century, the development of microfluidic chip technology has been very rapid and has attracted the attention of more and more scholars. As an important part of the microfluidic chip, the performance of the micromixer is critical. The fractal structure in the microchannels helps to improve the mixing performance of the micromixer and improve the mixing efficiency of the micromixer. The research results of other scholars are of great significance to the research of the present paper, which mainly studies the effect of changing the baffle state on the mixing efficiency of the micromixer based on the Koch fractal principle. Through simulation analysis, it was found that the mixing efficiency of the baffles distributed on both sides of the microchannel was higher than the mixing efficiency of the baffles distributed on the microchannel side. When the distance between adjacent baffles was divided into 0.15, 0.25 and 0.35 mm, simulated data suggested that the baffle distance of 0.15 mm was best. Increasing the number of baffles from six to eight groups increased the mixing path of the fluid in the microchannel and improved mixing efficiency. A comparison of mixing efficiencies of the 0°, 15° and 30° baffle angles revealed that very significant improvement in mixing efficiency was obtained at 30°. © 2019 Society of Chemical Industry     

Calorimetric study and thermodynamic description of Ga-Ge-Li liquid alloys

This publication contains the thermodynamic results received by the drop calorimetry method. The experiments were conducted for four different cross sections, at the temperature of 1080 K. The investigated alloys were as follows: (Ga_0.75Li_0.25)_1-xGe_x, (Ge_0.50Li_0.50)_1-xGa_x, (Ga_0.50Li_0.50)_1-xGe_x, (Ga_0.25Li_0.75)_1-xGe_x. The mixing enthalpy changes measured for all four cross sections of the Ga-Ge-Li system are characterized by negative deviations from the ideal solutions. The Muggianu model with the ternary interaction parameters was applied to elaborate the experimental data of the mixing enthalpy change with the use of the optimized thermodynamic parameters of the binary systems available in the literature.     

CFD Modeling of Active Volume Creation in a Non‐Newtonian Fluid Agitated by Submerged Recirculating Jets

Computational fluid dynamics (CFD) models were employed to investigate flow conditions inside a model reactor in which yield stress non‐Newtonian liquid is mobilized using submerged recirculating jets. The simulation results agree well with the experimental results of active volume in the reactor obtained using flow visualization by the authors in a previous study. The models developed are capable of predicting a critical jet velocity (v_c) that determines the extent of active volume obtained due to jet mixing. The v_c values are influenced both by the rheological properties of the liquid and the nozzle orientation. The liquid with higher effective viscosity leads to higher v_c for a downward facing injection nozzle. However, an upward facing injection nozzle along with a downward facing suction nozzle generates enhanced complementary flow fields which overcome the rheological constraints of the liquid and lead to lower v_c.     

双排桩门架—锚杆新型组合支护体系的应用研究

本文分析了双排桩门架支护结构的受力机理。针对工程实际进行变形分析,提出增设锚杆形成锚杆———双排桩门架式组合支护体系的方法,并与监测数据对比、验证。     

一种估算单桩经济直径的方法

在滩海油田开发过程中,经常需要设立立管桩,在环境荷载的作用下,立管桩顶部会发生位移,较大的位移对立管及栈桥的安全很不利,因此需要合理确定单桩的直径。埕岛油田在确定单桩直径时引入了经济直径的概念,文章对经济直径的原理进行了分析,给出了桩顶位移和桩径经济指数计算公式,并举例进行了计算,得出了桩径与桩顶位移及桩径经济指数的关系曲线, 进而求得经济桩径的取值范围。文章还对该方法的优缺点进行了分析。     

双频抽运提高SBS相位共轭保真度

相位共轭保真度是相位共轭镜技术用于强激光系统中的一个重要指标。采用四波混频加强SBS的方法 ,其相干拍频驱动声子场 ,能提高SBS相位共轭保真度。对于双频单池结构 ,使用列阵相机测量激光束能量远场角分布 ,在SBS转换效率最佳时 ,对相干驱动SBS相位共轭保真度进行了实验研究     

引入激光回馈的双光束干涉效应的研究

提出了一种引入He-Ne激光回馈的双光束干涉系统,并在理论和实验两方面进行了研究。实验中对系统中的干涉信号及激光器尾光功率变化同时进行探测。发现当干涉仪的主回馈镜移动时,激光器尾光信号是正弦形波形,而干涉仪输出的是以双峰为一个周期的信号,双峰中一峰总是高于另一峰,并且当主回馈镜移动方向改变时,同一周期中两峰出现的顺序也随之改变。对实验现象进行了理论分析,并模拟出干涉信号及激光自身功率的变化曲线。理论分析及模拟结果与实验结果完全吻合。讨论了利用发现的现象进行测量的可行性,所提出的测量方法易于实现。     

Non-equilibrium particle motion in the vicinity of a single blade

The motion of sand particles close to a single moving blade was investigated using Positron Emission Particle Tracking (PEPT) during the period in which the free bed surface profile was evolving to an equilibrium shape. The area affected by the blade was divided into active and inactive regions and these were analysed separately. The characteristic heart-shape of the active region in the plan view was determined. An approximately 10-particle-diameter wide velocity transition zone is found between the two regions. While the tracer particle is in the inactive region moving away from the blade, the time dependence of the axial displacement is well described by a logarithmic relationship. The probability of particle movement towards the centre of the blade was quantified using a “central tendency” index. The calculated central tendency shows maxima at each side of the blade. The separation of the two maxima, which indicates the width of the active region, increases with fill level but is independent of rotational speed.     

挤扩支盘桩在湿陷性黄土地基中的应用

湿陷性黄土具有遇水发生湿陷、承载力大幅度降低的性质,这种性质直接影响到基础的承载力。为了研究支盘桩在湿陷性黄土地基中的承载性状,对湿陷性黄土中的3根支盘桩进行预浸水静载荷试验,结果表明,支盘桩荷载—沉降曲线为缓变型,具有较好的承载性能,荷载传递规律与在非湿陷性黄土地基中具有相似的性质,桩身各段承载力的发挥具有明显的顺序性,其结果为挤扩支盘桩在湿陷性黄土地基中的应用提供了依据。     

粉喷桩处理软弱地基在祁临高速公路的应用

结合工程实例，介绍了粉喷桩的所属类型，粉喷桩对软弱地基加固的原因，所适应土质及加固特点，阐述了祁临十八合同段的粉喷桩施工过程及施工中应注意的若干问题，得出粉喷桩处理不良地基效果良好。