共查询到20条相似文献，搜索用时 842 毫秒
1.
GUO Chao ZHANG Yong-xing LUO Jun-cai ZHOU Zhi-ming ZHANG bo-hu LI Jin-long XIE Wen-ting WU De-jun 《保鲜与加工》2011,(4):106-112
By using near crack line analysis method and Mohr-Coulomb strength criterion,the elastic-plastic solution for near crack line of an eccentric cracks loaded by the pore water pressure under large scale yielding condition is analyzed.The elastic stress fields,the plastic stress field,the unit normal vector of the elastic-plastic boundary near the crack line,the elastic-plastic stress fields near crack line are identified.The change pattern of the length of the plastic zone and the pore water pressure is presented.Besides,the elastic-plastic analytical solution for an eccentric cracks loaded by the pore water pressure is obtained. 相似文献
2.
Investigation on flow and heat transfer characteristics in capillary porous wick based on alkali metal thermal-to-electric converter (AMTEC) 总被引：1，自引：0，他引：1
An axial symmetric invariable temperature phase change interface model of capillary porous wick based on alkali metal thermal-to-electric converter (AMTEC) is established to simulate flow and heat transfer characteristics in capillary porous wick and liquid channel by solving the mass and heat transport controlling equations. The effects of the working fluid flow rate, inlet temperature, porous wick thickness, porosity and effective pore diameter on the distributions of pressure, velocity and temperature are analyzed. In addition, the available effective pore size of the porous wick and the measures to improve the performance of the porous wick are given by analyzing the relationship between the maximum available capillary pressure and the loop pressure drop. The results show that the model presented in gives a good agreement with the three dimensional two-phase evaporation model. The flow and heat transfer characteristics of the capillary porous wick with the alkali metal liquid as working fluid are different from that with the traditional working fluid in some ways. 相似文献
3.
Biphasic porous medium model,based on the mixture theory in continuum mechanics frame,is used to depict the distributing disciplinarian of sclerotin's stress field,distortion field and pore pressure when the bone tissue is subjected to various dynamic loadings.The coupling relationship among the distortion,fluid flow and the streaming potential is studied.The penalty finite element formulation for streaming potential is studied.The penalty finite element formulation for streaming potential distributing in bone tissue is obtained by using Galerkin weighted residual method for the biphasic porous medium model with corresponding initial and boundary conditions,in this modeling,the solid phase is assumed to be isotropic elastic medium,and the fluid phase is ideal fluid.The computational results show that because of the distortion of bone tissue the marrow's flow is raised,then the electriferous partical moves in the porous and the streaming potential appears. 相似文献
4.
弹性波作用下渗流多孔介质微粒运移分析是对目前静态流体或稳态多相渗流中微粒运移/捕集的补充,通过分析弹性波对微粒剥离运移捕集过程的影响,建立弹性波作用下微粒运移模型,得到对微粒运移效果和储层物性变化的影响规律。由推导得到的弹性波作用下微粒剥离临界速度可知,当微粒与孔喉半径的比值越小时弹性波导致的振荡附加力影响越大,临界速度与流体粘度、微粒/孔喉半径比成负相关,与基质胶结程度、结构力、微粒半径、微粒密度成正相关。弹性波作用下微粒运移模型需同时考虑多孔介质渗流速度的变化,此时微粒剥离释放速率增加,但随着波衰减和时间延长而降低,微粒在孔隙表面沉积滞留速率先上升后下降,喉道堵塞的速率有所上升,说明弹性波作用下微粒的剥离和悬浮能力增加,但亦增加了微粒在微细孔喉"架桥"堵塞的可能性。研究结论对岩石物理学和工业化波动处理涉及的储层物性研究具有一定指导意义。 相似文献
5.
For the quasi static problems of two phase porous media,the velocity variable of fluid phase can be eliminated as the viscosity of fluid is neglected.The corresponding governing equations,with displacement of solid phase and pore pressure as basic variables,as well as the boundary and initial conditions are given out.Finally a mixed finite element formula with u S-p variables is obtained with weighted residual method.This method has lesser nodal variables and higher accuracy of pressure distribution. 相似文献
6.
Articular cartilage, which is composed with a solid phase of collagen fibers and proteoglycan and a pore fluid phase, can be depicted with two-phase porous medium model based on mixture theory. This paper analyzed the creep and stress relaxation responses of confined compression problems of articular cartilage with the developed finite element method. The obtained responses of velocities of both solid and fluid phases and the effective stresses of solid phase as well as the pore pressures during the creep and stress relaxation processes of articular cartilage tissues under confined compression can be used as a theoretical reference for man-made cartilage materials, and behave important significance for the research in bio-mechanical engineering area. 相似文献
7.
Isotropic and anisotropic porous medium with the same porosity, different pore size distributions and pore surface fractal dimensions were constructed by random growth method, and the impact of microscopic pore structure on moisture migration process in pores of porous medium was theoretically studied. The results show that the internal transport properties of porous medium are not only determinded by porosity, but also greatly influenced by pore size distribution and pore surface fractal dimension. The biggest water vapor diffusion concentration differences of three kinds of isotropic and three kinds of anisotropic porous medium with the same porosity, different pore size distributions and pore surface fractal dimensions are 30.6% and 23.3%, respectively. Better water vapor diffusion properties in pores of isotropic porous medium demands for bigger tiny pore size distribution rate and larger pore surface fractal dimension, which means the pore connectivity is better. While better water vapor diffusion properties in pores of anisotropic porous medium(water vapor diffusion direction is perpendicular to the direction of larger growth rate of anisotropic porous medium) demands for more big pore size distribution and smaller pore surface fractal dimension. The method lays a theoretical foundation for preparing indoor humidity control of building materials. 相似文献
8.
Considering the compression of medium and fluid, coupled vibration of saturated fractional derivative type viscoelastic soil and a circular tunnel with partially sealed shell lining in the frequency domain is investigated according to theories of Biot and elastic shell. The stress and displacement constitutive behavior of the soil skeleton is described by fractional derivative model which reflects the rheological properties of the medium while regarding soil as a liquid-solid saturated porous medium. The expressions of displacement, stress and pore water pressure are obtained while the inner boundary of circular tunnel is subjected to axially symmetric radial traction and axially symmetric fluid pressure respectively by introducing a partially permeable boundary condition. With the parameter analysis, it is revealed that the order of fractional derivative model on the responses for the system subjected to the symmetric radial traction is much greater than that of the system under the axially symmetric fluid pressure. And resonance phenomenon occurs obviously. Nevertheless the system responses do not have remarkable resonance phenomenon under axially symmetric fluid pressure. 相似文献
9.
By analyzing heat and mass transport process and transport properties of moist porous media, this paper established a computational model for one dimensional field of heat and moisture transport process. Based on the distinguishing characteristic functions, the inner temperature and humidity distribution of porous media was worked out. With the actual spot measurement, the heat and moisture properties were obtained by nonlinear least square method. 相似文献
10.
以榨汁后的沙棘果皮为原料,采用丙酮为萃取剂并以超声波为辅助条件,提取沙棘黄色素。经单因素和响应面优化设计试验,确定最佳提取工艺参数为:以丙酮为萃取剂,料液比为1∶20,超声时间32 min,超声功率385 W,粉碎度60目,此时吸光度达到最大值1.182,沙棘黄色素(以β-胡萝卜素计)得率达到163 mg/kg。 相似文献
11.
为揭示机体弹性变形对曲轴主轴承润滑特性的影响,在考虑整机体和曲轴弹性的条件下,建立发动机曲柄连杆机构多柔体动力学模型,耦合基于质量守恒边界条件的广义雷诺方程和Greenwood/Tripp接触模型,分析机体弹性变形对曲轴主轴承润滑特性的影响。结果表明：与刚性机体相比,计入机体弹性变形后,各主轴承的润滑特性随曲轴转角的变化趋势与将缸体处理为刚性时基本一致;润滑油平均端泄量和总摩擦功耗在一个工作循环内均变化较小;润滑油最小油膜厚度、最大油膜压力和轴承的最大粗糙接触压力在一个工作循环内的某些时刻变化明显。 相似文献
12.
Coal is a non-uniform porous medium. The degree of porous development is closely related to absorption-desorption characteristics and flow characteristics of coal seam gas. In order to investigate pore structure of briquette, it is studied the characteristics of porous development of briquette with different coal particle sizes like 4.00~1.70 mm, 1.70~0.38 mm and 0.38~0.18 mm by using CF-2000P polarization analysis software and Fractalfox2.0 fractal analysis software. Testing result shows that with the decrease of coal particle size, briquette pore radius decreases, the total number of pores and fractal dimension increase. And the more the pore develops, the more uniform the pore distributes. 相似文献
13.
After coal mined, the balance of original stress state is to be broken. In the course of retribution, displacement and deformation in the overburden takes place with the working face advancing. The article points out that overburden can be divided into, in ascending, caving zone, fractured zone, bending zone and loose alluvium zone. The extracting space can be prevented from transferring to ground with injection material into bed-separation gap. Applying both mining subsidence theory and elastic thin plate theory, the computational model of subsidence control technology of grouting is worked out. The model can get rid of blindness of determining the position of separated strata, forecast the surface subsidence and provide the basis of theory for forecasting surface subsidence control technology of grouting. 相似文献
14.
超声波联合混凝法处理制药废水的研究 总被引：1，自引：1，他引：0
为了探讨单独超声波降解法、混凝法及2种方法联合处理制药废水的可行性,研究了超声波辐射时间、功率以及混凝剂的种类、浓度对制药废水中COD和NH3-N去除的影响。结果表明：（1）超声波单独处理制药废水时,COD和NH3-N去除率先随着超声波辐射时间(200~1000 s)的增大而增大,最佳时间为1000 s,COD和NH3-N的最大去除率分别为27.80%、45.34%;超声波辐射时间为1000 s,COD和NH3-N去除率随着超声波辐射功率的增大而先增大后减小。（2）单独用混凝剂处理制药废水时,COD的去除率随着混凝剂的浓度(0.1~0.6 g/L)的增大而先增大后减小,PAC在0.3 g/L时为最佳,COD的去除率为40.10%,NH3-N的平均去除率保持在5%左右。（3）在各自的最佳状态下,先用超声波处理后加混凝剂比先加混凝剂后用超声波处理的COD和NH3-N的去除率高,分别为61.24%、58.63%。试验表明,先用超声波处理后加混凝剂比先加混凝剂后用超声波处理对COD和NH3-N的去除率高。 相似文献
15.
超声波辅助萃取毛葱油工艺的响应面法优化 总被引：1，自引：0，他引：1
采用有机溶剂为载体对毛葱油进行超声波辅助萃取。在单因素和响应面优化设计试验的基础上,确定了最佳提取工艺条件:以二氯甲烷为萃取剂,料液比1:3,超声功率209W,超声时间37 min,超声温度31℃,在此条件下,毛葱油得率可达4.45g/kg。得到的毛葱油为棕色黏稠液体。 相似文献
16.
To explore the characteristics of deformation of sandstone under cyclic pore water pressure, the experiments with different axial stresses (60%, 70% and 80% of peak intensity) of sandstone subjected to cyclic pore water loading are investigated by using MTS815 rock mechanics testing system, and irregular small deformation in deformation curve of sandstone are also processed by wavelet transformation of Matlab. The results show that with the increase of constant axial stress, fatigue deformation under cyclic pore water pressure will accelerate the failure of the sandstone. With the increase of the number of cyclic pore water pressure, the deformation evolution of the plastic-loop is illustrated as sparse-dense-sparse. The deformation curves of sandstone under cyclic pore water pressure affected by many factors are decomposed, reconfigurable processed and evaluated by using wavelet transformation, which indicates that the basic curve with optimal decomposition scale fits well with the experimental curves and reveals the deformation evolution of sandstone. 相似文献
17.
探讨了溶剂种类、超声频率、超声时间、超声功率及料液比对玉米胚芽油油脂提取效果的影响,并通过正交试验确定其最佳提取工艺。结果表明,乙醚为最佳提取溶剂,最佳提取条件为:提取频率高频(70 kHz),提取时间20 min,料液比1∶7,超声功率600 W。在此条件下,玉米胚芽油的出油率达44.34%。 相似文献
18.
利用CFD模型研究苹果冷藏库内的空气流动 总被引：1，自引：0，他引：1
苹果冷藏库内的空气流动可调节库内环境,且气流速度对改善果实品质具有重要的作用,因此有必要研究苹果贮藏库内的空气流动特性。本研究采用CFD（Computational Fluid Dynamics）方法,运用大型计算流体动力学软件Fluent建立模型,以标准湍流模型对苹果冷藏库内的空气流动做三维模拟。模拟时以苹果堆码区作为多孔介质,研究库内堆码苹果时的空气流动状况,并对库内的空气流速进行试验测定和验证。结果表明,通过气流场模拟能较为直观地显示冷库内部的流场特征和流动状态,气流从风扇流出,在风机与货物堆码区形成明显的涡流;气流在货物堆码区分布较为均匀,靠近风机的货物堆码区气流速度均高于远离风机的货物堆码区气流速度。冷库流场的测量值与CFD模拟的结果进行对比,最大误差在10%以内,测量值和模拟值之间的相关系数在0.9以上,说明了CFD模拟的可靠性。该模拟结果可为商用苹果冷藏库的优化和库内环境调节提供一定的理论依据。 相似文献
19.
超声波辅助浸提木枣多糖优化工艺的研究 总被引：2，自引：0，他引：2
通过正交试验,研究了超声波功率、提取温度、提取时间、料液比和提取液pH值对木枣多糖得率的影响。结果表明,各因素影响程度依次为:提取液pH值>料液比>提取时间>提取温度>超声波功率;得到最佳工艺参数为:超声波功率为200W,料液pH值为9,料液比为1∶12,温度为50℃,提取时间为15min。在此参数条件下,木枣多糖提取得率为1.81%。 相似文献
20.
叶类蔬菜中氨基甲酸酯类农药残留的超声波清洗条件优化 总被引：1，自引：0，他引：1
研究旨在通过优化超声波清洗条件降低叶类蔬菜中氨基甲酸酯类农药的残留量,研究高效、安全的农药去除方法,以期为叶类蔬菜的采后超声波清洗产业化发展提供技术支持。通过比较超声波处理与清水漂洗处理在农药去除率中的差异性,并且从超声波功率、清洗时间和清洗温度等方面探究超声波处理对果蔬中氨基甲酸酯类农药残留的清除效果,然后通过正交试验得出超声波清洗条件的最佳组合,最后结合超声波清洗对叶类蔬菜中营养成分的影响,从而得出叶类蔬菜中氨基甲酸酯类农药残留的超声波清洗最佳条件。实验结果显示：当超声波功率为100 W,清洗时间为5 min,清洗温度为19℃时,得到菠菜的最佳清洗效果,农药去除率可以达到92.7%;当超声波功率70 W,清洗时间5 min,清洗温度19℃时,得到小白菜的最佳清洗效果,农药去除率达到92.1%。而且菠菜、小白菜经超声波清洗的去除效果要显著优于清水浸泡去除效果。根据不同清洗条件下抗坏血酸保留率的比较分析,得出：在使用超声波清洗叶类蔬菜时,超声波功率不应超过100 W,清洗时间控制在5 min内,清洗温度不超过25℃,这样既能够有效地去除叶类蔬菜中的农药残留,同时对营养成分也具有较高的保留率。 相似文献