The vibration rheometer: the effect of vibration on fresh concrete and similar materials

The use of the newly‐designed electronic accelerometer as an integral part of the vibration rheometer, for the first time made it possible to continuously and accurately record the acceleration of an apparatus piston as a solid mass oscillating in the test specimen of the material under sub‐base excitation. The research is focused on plastic concrete, mortar and appropriate reference materials whose behavior was approximated to a pseudoplastic fluid. An analytical solution to the oscillation of the piston in the specimen is also provided. The research showed that a layer of the material with the properties close to the ideal Newtonian fluid forms around each particle exceeding 0.25 mm causing a reduction in resistance to deformation and compression in a specimen. The effect of vibrations on plastic concrete and similar materials is also described.     

The viscous dissipation effect on heat transfer and fluid flow in micro-tubes

The numerical modeling of the conjugate heat transfer and fluid flow through the micro-tube was presented in the paper, considering the viscous dissipation effect. Three different fluids with temperature dependent fluid properties are considered: water and two dielectric fluids, HFE-7600 and FC-70. The diameter ratio of the micro-tube was D_i/D_o = 0.1/0.3 mm with a tube length L = 100 mm. The laminar fluid flow regime is analyzed. Two different heat transfer conditions are considered: heating and cooling and three different Br = 0.01, 0.1 and 0.5. The influence of the viscous heating on Nu and Po is analyzed and compared with Br = 0.     

Viscous and elastic properties of poly(methyl methacrylate) melts filled with silica nanoparticles

In this paper it is shown that elastic properties of a poly(methyl methacrylate) melt in the linear range of deformation are more significantly influenced by the addition of silica nanoparticles than viscous ones. The effect is the strongest in the steady-state which is reached at several thousand seconds. That is the reason why the often used dynamic-mechanical experiments are not a very suitable method for investigations of that kind. Therefore, creep and creep-recovery tests were applied for the characterisation of the filled materials. The linear steady-state recoverable compliances following from the recovery experiments increase by a factor of 6 at the highest measured volume content of 2.1%. This finding is explained by the existence of long retardation times in the filled materials resulting from interactions between the fillers and matrix molecules attached to their surfaces which reduce their molecular mobility. Retardation spectra calculated from the recovery curves quantify these assumptions. The model is supported by the experimental finding that the recoverable compliance becomes smaller above a certain stress applied and approaches that of the matrix as such a behaviour could be explained by a detachment of the molecules from the particle surface. The paper demonstrates that investigations of elastic properties of nanoparticle filled polymers in the molten state at long experimental times are a very sensitive tool to get an insight into interactions between particles and macromolecules of such systems.     

A note on the thermal stability of a reactive non-Newtonian flow in a cylindrical pipe

The effect of variable viscosity and viscous dissipation on the thermal stability of a one-step exothermic, reactive non-Newtonian flow in a cylindrical pipe was considered assuming negligible reactant consumption. The governing equations; momentum and energy equations, which are coupled due to the dissipative term in the energy equation, were solved by closed-form and approximate techniques respectively. We obtained closed-form solutions for the momentum equation via the Homotopy analysis method(HAM), while the resulting energy equation was analysed for thermal stability via the variational technique. Parametric analysis of the solutions were conducted on the dimensionless velocity (v(r)), the critical Frank-Kamenetskii parameter(δ_cr) and the critical temperature(θ_cr) and expressed graphically and in tabular forms.     

螺杆泵在稠油出砂井中的应用

本文介绍了螺杆泵采油系统基本结构和工作原理，根据螺杆泵在稠油出砂井中的现场应用，分析了螺杆泵现场应用效果以及现场施工时要求，展现了螺杆泵采油系统在高粘稠油和出砂井等方面良好的现场应用前景。     

侧钻井防砂工艺技术

针对铡钻井井身结构的特点，简要介绍了两种稠油侧钻井防砂技术的机理和内容。其中，在小直径筛管防砂技术中，防砂筛管和封隔器的设计是主要的；而通过室内试验证明，高温人工井壁完全能够满足现场防砂要求。     

稠油油藏蒸汽吞吐年油汽比的变化规律及其预测方法

以辽河油区已投入吞吐开采稠油油藏实际一切数据为基础，总结了年油汽比变化规律，建立其动态预测的数学模型，并用推广递推梯度方法，对模型中的参数进行了估计。     

Analytical and numerical studies on viscous energy dissipation in laterally driven microcomb structures

Numerical and analytical studies on viscous air damping in laterally oscillating microcomb structures are discussed in this work. Previous investigators modeled this type of flow field using Couette and Stokes flow models. The numerical simulation results demonstrate that the flow is much more complex and quite different from the Couette or Stokes flow. The pumping and sucking motions at the edges of the oscillating electrode create a fluid brake. This fluid brake retards the horizontal movement of the flow and generates a strong vortex in the region between the oscillating electrode and the base material, which has not been reported before. The deceleration of the fluid also increases the velocity gradient on the surfaces of the oscillating electrode, which gives rise to a higher damping. The numerically predicted damping is about 2.8 times larger than that predicted by the Stokes flow model.     

Real-time dynamic substructuring testing of viscous seismic protective devices for bridge structures

This paper presents a real-time dynamic substructuring (RTDS) test program carried out on bridge structures equipped with two innovative viscous seismic protective devices: a seismic damping unit and a shock transmission unit. In the RTDS tests, the seismic protective units were physically tested in the laboratory using a high performance dynamic actuator imposing, in real time, the displacement time histories obtained from numerical simulations being run in parallel. The integration scheme used in the test program was the Rosenbrock-W variant, and the integration was performed using The MathWorks’ Simulink and XPC target computer environment. The numerical counterpart included the bridge columns and the additional energy dissipation properties. The nonlinear response of these components was accounted for in the numerical models. The tests were run under various ground motions, and the influence of modeling assumptions such as damping and initial stiffness was investigated. Finally, the test results are compared to the predictions from nonlinear dynamic time history analyses performed using commercially available computer programs. The results indicate that simple numerical modeling techniques can lead to accurate prediction of the displacement response of bridge structures equipped with the seismic protective systems studied.