共查询到20条相似文献，搜索用时 140 毫秒
1.
This paper studies the effect of sample size on the stress-strain behavior and strength characteristics of geotextile reinforced sand using the finite element numerical analysis. The effect of sample size was investigated by studying the effects of varying the number of geotextile layers, the confining pressure and the type of geotextile. Modeling was performed on samples with five different diameters： 38, 100, 200, 500 and 600 mm. The elastic-plastic Mohr-Coulomb model was used to simulate sand behavior. Results showed that small-sized samples show higher values of peak strength and higher axial strain at failure in comparison with large-sized samples. The size effect on the behavior of samples became further apparent when the number of geotextile layers was increased or the confining pressure was decreased. In addition, the results indicated that the magnitude of the size effect on the mechanical behavior of reinforced sand decreases with an increase in the sample size. 相似文献
2.
The water mitigation effect on the propagation of shock wave was investigated numerically. The traditional smoothed particle hydrodynamics (SPH) method was modified based on Riemann solution. The comparison of numerical results with the analytical solution indicated that the modified SPH method has more advantages than the traditional SPH method. Using the modified SPH algorithm, a series of one-dimensional planar wave propagation problems were investigated, focusing on the influence of the air-gap between the high-pressure air and water and the thickness of water. The numerical results showed that water mitigation effect is significant. Up to 60% shock wave pressure reduction could be achieved with the existence of water, and the shape of shock wave was also changed greatly. It is seemly that the small air-gap between the high-pressure air and water has more influence on water mitigation effect. 相似文献
3.
Based on the Leaderman constitutive relations in nonlinear viscoelasticity and the linear geometrical assumption, a mathematical model for the bending of nonlinear viscoelastic beams was established in this paper. The Laplace transformation method and the Titchmarsh theorem were used to prove that some relations exist between solutions to bending problems of visco- and elastic beams, which reveals the fugue effect of viscoelastic materials. The high-order Galerkin approximate solution to the quasi-static response of nonlinear viscoelastic beams under a step load was obtained by using the new method suggested in this paper as well as the Mathematica software and the Newton iteration technique. 相似文献
4.
The effect of support calcination temperature on the benzene selective hydrogenation performance of the Ru-Ce-B/ZrO2 catalysts was investigated.It was found that with increasing calcination temperature,the surface area decreased,on the contrary,the pore size and the amount of monoclinic phase increased.With increasing support calcination temperature,the activity of the catalyst roughly decreased and cyclohexene selectivity increased.The activity decreased due to the decrease of the surface areas.The increase of the cyclohexene selectivity was correlated not only with the decrease of the surface areas but also with the increase of monoclinic phases,rich in surface hydroxyl,and the enlarged pore size of zirconia.This suggests the monoclinic zirconia with a medium surface area,rather than a big one,and a mesoporous structure,even including some macropores,is an ideal support of the catalyst for benzene selective hydrogenation. 相似文献
5.
The recently developed elastic-viscoplastic self-consistent model with various self-consistent schemes was applied to study the effect of basal texture on the mechanical behavior of magnesium alloy AZ31B sheet. The influence of the basal texture was investigated using various initial textures generated by artificially tilting the measured texture of the reference AZ31B sheet around in a transverse direction. The material parameters for the various models were fitted to experimental uniaxial tension and compression along the rolling direction and were then used to study the effects of the basal texture on the yield stress, R value, ultimate stress and uniform strain under uniaxial tension. The effect of the basal texture on sheet metal forming was further assessed by calculating the limit strain under in-plane plane strain tension. An assessment of the predictive capability of polycrystal plasticity models was made based on comparisons of predictions and experimental observations. Among the available self-consistent approaches, the Affine self-consistent scheme resulted in the best overall performance. 相似文献
6.
The displacements and geometry of the rock blocks and the properties of the rock struc-ture play an important role in the stability of tunnels.Based on the key block model,the dynamic instability analysis of underground tunnel subjected to intensive short-time compressional wave was conducted.The instability of the tunnel caused by the spallation and the inertial effect was distin-guished.And the influence of the roof contour curvature of tunnel was also determined. 相似文献
7.
Tomoko Tode 《通化师范学院学报》2008,(5)
The purpose of this study is to investigate the durabilityof the effect of explicit and implicit instructions on beginningEFL learners' learning of the copula be.The study intends toexamine whether or not the effect remains after the auxiliarybe of the progressive is introduced.Three groups of 89Japanese junior high school students participated in thequasi-experiment.One group was given explicit instruction on 相似文献
8.
LIGui－zhi LIUYong－ming 《上海大学学报(英文版)》2001,5(4):334-337
A study on the sorption of monocrotophos and parathion-methyl on Yellow River‘s sediments was performed.The influence of some factors,such as pH value and ionic strength,on the sorption was investigated and first order kinetics mode for the sorption of monocrophos was shown.Freundlich isotherm was suggested as the most appropriate type for monocrophos an parathion-methyl.But the sorption isotherms of monocrotophos and parathion-methyl are also in conformity with Langmuir equation.Both partition and adsorption occur to the sorption of monocrophos to Yellow River‘s sediments.but partition is the predominant for that of parathionmethyl. 相似文献
9.
This paper presents the results of an investigation to use arc-length mesh generation and finite volume TVD scheme to calculate Euler equations for predicting the effect of geometry parameters in reducing the drag force and improving the lift-drag ratio of grid fin in the supersonic flow regime. The effects of frame and web, whose cross section shape and thickness and spacing, on the aerodynamic character of the grid fin were studied. Calculations were made at Mach 2.5 and several angles of attack. The results were validated by comparing the computed aerodynamic coefficients against wind tunnel experimental data. Good agreement was found between computed and experimental results. The computed results suggest that parameters of the grid fin's frame have the greatest effect on the grid fin aerodynamic character, especially on its drag force. It was concluded proper choice of appropriate grid fin geometry parameters could reduce the drag force and improve the lift-drag ratios. 相似文献
10.
The objective of the study is the cytocidal and inhibitory effect of energy-controllable pulse on ovarian cancer cell line SKOV3.Ovarian cancer cell suspension were treated by electric pulse with different parameters,.The inhibitory rate(IR) was assayed by modified colorimetric MTT methods,the growth curves of two test groups and one control group were also measured.and the ultrasturctureal changes were observed under electron microscopy(EM) and scan electron microscopy (SEM),It was found that the treated SKOV3 cell proliferated more slowly.IR was increased with the enhancement of pulse paramters,The ultrastructural study showed that morphological changes occured obviously.Swollen mitochondria,fracutured ridges,cytoplasmic vacuoles and membrane holes appeard in most of the processed cells,and a part of bilayer membrane was ruptured.It is indicated that irreversible electric breakdown occurred in some of the treated cells,and the electric pulse could kill cancer cell and inhibit its recovery and growth. 相似文献
11.
针对校园网络对大学生文化素养的正面和负面影响作了相应的探讨，并提出了一些改进措施。[第一段] 相似文献
12.
13.
本文运用人种志方法对一所高中的主题班会开展情况进行了研究。研究发现,学生期望的班会主题与学校想法不同,各班的主题班会氛围或凝重或轻松。全班学生的参与度也有所不同。班会的主题要有现实针对性,也应反映学生的兴趣和需求。充分调动起班级里每位学生参与积极性的班会才引导学生自主管理,增强学校教育实效。 相似文献
14.
Yona Leyser Tali Zeiger 《International Journal of Disability, Development & Education》2011,58(3):241-255
The impact of three variables on the self-efficacy of 992 general and special education preservice teachers was examined. These variables were years of preservice education, experience with children with special educational needs, and training in inclusion or exceptional education. All participants responded to a teacher self-efficacy scale that measured four factors. Findings revealed a main effect for years of preservice education and for major of the academic degree. The main effect for years of preservice education was found only for efficacy for social relations. The main effect for degree major revealed that special education majors had significantly higher scores than regular education majors, on all four factors. A significant main effect for experience and major was also found. Students with much and some experience had significantly higher scores than students with no experience on two factors. Intensity of training was associated with self-efficacy. Students with much and some training had significantly higher scores than students with no training on all four factors. Implications for research and practice are discussed. 相似文献
15.
In this experiment we studied the effect of goal setting on the strategies used to perform a block design task called SAMUEL. SAMUEL can measure many indicators, which are then combined to determine the strategies used by participants when solving SAMUEL problems. Two experimental groups were created: one group was given an explicit, difficult goal and the other was not given a goal. The two groups were comparable in their average visual–spatial ability. The results indicated no goal effect on the strategies, defined in terms of the combined indicators. However, the goal did have an effect on some of the indicators taken alone (total problem-solving time, total viewing time, and model-viewing frequency) but this was true only for subjects with a low cognitive ability. These findings demonstrate that setting a goal can have an effect on some strategy indexes used to assess performance on a visual-intelligence design task. This research has implications for defining intelligence-test instructions and educational requirements in school. 相似文献
16.
沿明月山景区登山路径,在山脚、半山腰和山顶各区分剐采集混合土壤样品,并对其理化性质及重金属含量进行了监测,重点分析了旅游活动对景区土壤的pH值、有机质、全氮、全磷、以及Fe、Cu、Zn、Pb、Cr等重金属元素含量的影响。结果表明,旅游活动已对明月山森林景区的土壤造成了一定程度的负面影响,应采取有效措施减少其对景区土壤的影响,维护景区良好的生态环境,以实现明月山森林景区旅游业的可持续发展。 相似文献
17.
农村远程教育条件下中小学教师的信息化教学能力培训的探讨 总被引：2，自引：1，他引：1
山西省农村远程教育实施3年内,教师信息技术能力得到不同程度的发展,但也存在一些问题。在对山西省12个行政辖区中小学信息化教学能力培训现状及培训后实施效果进行了调研,分析了信息化教学能力培训存在的问题及成因,并结合调研对象的实际状况,有针对性提出了改进的建议和对策。 相似文献
18.
Marcy Perkins Driscoll 《Contemporary educational psychology》1985,10(1):38-51
One purpose of this study was to determine whether cognitive structure, assessed by psychometric measures of concept interrelatedness, can be developed when the students initially do not know what concept relationships exist and what they mean. The second purpose was to apply those measures to a learning situation that has produced a nonspecific transfer effect, i.e., the facilitative effect of concrete examples on learning abstract passages, to attempt to explain this effect more completely. Five groups of 20 students each read two prose passages and took recall and structure assessment tests on the second passage. Results (1) indicated that the nonspecific facilitative transfer effect was replicated and (2) offered some support for the contention that the cognitive structure which proximity measures assess can be trained to correspond to content structure, but that related recall remains low. With resolution of some of the methodological issues surrounding these measures, however, clearer explanation of transfer effects and assessment of higher order learning may be facilitated. 相似文献
19.
144只一日龄的AA肉仔鸡随机分为4组(n=36),预饲一周后分别在试验组基础日粮中添加50mg/kg、100mg/kg、150mg/kg的半胱胺,分别于2、4、6周龄采颈静脉血,分离血清,测定四组血清钙、磷和葡萄糖含量及ALT、AST、ALP活性,研究半胱胺对肉鸡部分血清化学参数及酶活性的影响.结果表明,饲料中添加适量的Cs能升高AA肉鸡的血钙水平,而对鸡血清磷、葡萄糖含量没有明显影响;添加50～100mg/kg的Cs对ALT、AST活性没有明显的影响;而饲料中添加Cs对ALP活性有一定影响. 相似文献
20.
European Journal of Psychology of Education - The main purpose of this study was to shed some light on the effect of socialization context (home vs. orphanage) on gender-specific value acquisition.... 相似文献