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101.
The equation of state(EOS)for square-well chain fluid with variable range(SWCF-VR) developed in our previous work based on statistical mechanical theory for chemical association is employed for the correlations of surface tension and viscosity of common fluids and ionic liquids(ILs).A model of surface tension for multi-component mixtures is presented by combining the SWCF-VR EOS and the scaled particle theory and used to produce the surface tension of binary and ternary mixtures.The predicted surface tensions are in excellent agreement with the experimental data with an overall average absolute relative deviation(AAD)of 0.36%.A method for the calculation of dynamic viscosity of common fluids and ILs at high pressure is presented by combining Eyring’s rate theory of viscosity and the SWCF-VR EOS.The calculated viscosities are in good agreement with the experimental data with the overall AAD of 1.44% for 14 fluids in 84 cases.The salient feature is that the molecular parameters used in these models are self-consistent and can be applied to calculate different thermodynamic properties such as pVT,vapor-liquid equilibrium,caloric properties,surface tension,and viscosity. 相似文献
102.
R. Behnke M. Mundil C. Birk M. Kaliske 《International journal for numerical methods in engineering》2014,99(13):966-999
This paper is devoted to the formulation of a plane scaled boundary finite element with initially constant thickness for physically and geometrically nonlinear material behavior. Special two‐dimensional element shape functions are derived by using the analytical displacement solution of the standard scaled boundary finite element method, which is originally based on linear material behavior and small strains. These 2D shape functions can be constructed for an arbitrary number of element nodes and allow to capture singularities (e.g., at a plane crack tip) analytically, without extensive mesh refinement. Mapping these proposed 2D shape functions to the 3D case, a formulation that is compatible with standard finite elements is obtained. The resulting physically and geometrically nonlinear scaled boundary finite element formulation is implemented into the framework of the finite element method for bounded plane domains with and without geometrical singularities. The numerical realization is shown in detail. To represent the physically and geometrically nonlinear material and structural behavior of elastomer specimens, the extended tube model and the Yeoh model are used. Numerical studies on the convergence behavior and comparisons with standard Q1P0 finite elements demonstrate the correct implementation and the advantages of the developed scaled boundary finite element. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
103.
D. Chen C. Birk C. Song C. Du 《International journal for numerical methods in engineering》2014,97(13):937-959
A high‐order time‐domain approach for wave propagation in bounded and unbounded domains is proposed. It is based on the scaled boundary FEM, which excels in modelling unbounded domains and singularities. The dynamic stiffness matrices of bounded and unbounded domains are expressed as continued‐fraction expansions, which leads to accurate results with only about three terms per wavelength. An improved continued‐fraction approach for bounded domains is proposed, which yields numerically more robust time‐domain formulations. The coefficient matrices of the corresponding continued‐fraction expansion are determined recursively. The resulting solution is suitable for systems with many DOFs as it converges over the whole frequency range, even for high orders of expansion. A scheme for coupling the proposed improved high‐order time‐domain formulation for bounded domains with a high‐order transmitting boundary suggested previously is also proposed. In the time‐domain, the coupled model corresponds to equations of motion with symmetric, banded and frequency‐independent coefficient matrices, which can be solved efficiently using standard time‐integration schemes. Numerical examples for modal and time‐domain analysis are presented to demonstrate the increased robustness, efficiency and accuracy of the proposed method. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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纳米远红外保健异形锦纶的研究 总被引:3,自引:1,他引:2
采用特殊的表面修饰技术,制备了纳米级新型远红外辐射材料(Nano-FIRM),并将其与聚酰胺-6(PA6)复合制得PA6/Nano-FIRM复合物,研究了复合物的可纺性,通过设计纺丝成形工艺制备了异形远红外保健锦纶长丝。研究发现:纤维的法向比辐射率(远红外辐射率)达86%,纤维横截面异形度达59.8%,纤维的力学性能比纯的聚酰胺-6纤维有所提高。通过SEM研究了复合物的两相结构,复合物中纳米单元尺寸为64.2 nm,功能性纤维中纳米单元尺寸为68.4 nm。 相似文献
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在实验室环境下进行非球面镜离心熔铸实验,研究大口径非球面镜的离心熔铸技术,并验证研究方法的可行性。通过对大口径非球面镜离心熔铸工艺的温度场相似准则和缩比模型参数匹配方法的研究,设计1∶80离心熔铸环境相似缩比实验机,进行物理模拟实验。测量了缩比实验的温度场、应力场以及最终的镜胚面形偏差。实验结果与仿真结果对比显示,温度场测量结果与仿真结果的相对误差在1.0%~1.4%之间。非球面镜在转变温度附近采取适当保温工艺后,最大压应力降为0.98 MPa. 通过轮廓仪检测制得的非球面镜面形偏差为-83.823 3 μm,与仿真结果相符。采用仿真联合缩比实验的方法对离心熔铸工艺中的不可观测量进行研究,为离心熔铸工艺提供了理论参考依据和实验指导。 相似文献
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110.
基于SUKF算法的组合导航方法 总被引:1,自引:0,他引:1
合成孔径声纳(SAS)运动补偿是其信号处理的重要环节,运动补偿需要水下导航数据,文中研究了基于捷联惯导(SINS)和多普勒声速剖面仪(ADCP)等设备的水下导航方法。针对大姿态误差角情况下的导航,论文建立了基于四元数的SINS/ADCP的非线性误差模型,并采用比例无迹卡尔曼滤波(SUKF)滤波算法进行了仿真。仿真结果表明,在SAS复杂运动情况下,采用非线性误差模型的SUKF方法优于传统线性误差模型的卡尔曼滤波方法,在一定程度上提高了SAS的导航精度。 相似文献