Lateral earth pressure of granular backfills on retaining walls with expanded polystyrene geofoam inclusions under limited surcharge loading

Existing studies have focused on the behavior of the retaining wall equipped with expanded polystyrene(EPS)geofoam inclusions under semi-infinite surcharge loading rather than limited surcharge loading.In this paper,the failure mode and the earth pressure acting on the rigid retaining wall with EPS geofoam inclusions and granular backfills(henceforth referred to as EPS-wall),under limited surcharge loading are investigated through two-and three-dimensional model tests.The testing results show that different from the sliding of almost all the backfill in the EPS-wall under semi-infinite surcharge loading,only an approximately triangular backfill slides in the wall under limited surcharge loading.The distribution of the lateral earth pressure on the EPS-wall under limited surcharge loading is non-linear,and the distribution changes from the increase of the wall depth to the decrease with the increase of the limited surcharge loading.An approach based on the force equilibrium of a differential element is developed to predict the lateral earth pressure behind the EPS-wall subjected to limited surcharge loading,and its performance was fully validated by the three-dimensional model tests.

Equivalent transformation between the matrices for expanding integrable model of the hierarchy of evolution equation

A direct method for obtaining the expanding integrable models of the hierarchies of evolution equations was proposed. By using the equivalent transformation between the matrices, a new isospectral problem was directly established according to the known isospectral problem, which can be used to obtain the expanding integrable model of the known hierarchy.

Strain rate dependency and fragmentation pattern of expanding warheads

For the characterization of the behaviors of a metal material in events like expanding warheads, it is necessary to know its strength and ductility at high strain rates, around 104e105/s. The flyer plate impact testing produces the uniform stress and strain rates but the testing is expensive. The Taylor test is relatively inexpensive but produces non-uniform stress and strain fields, and the results are not so easily inferred for material modeling. In the split-Hopkinson bar(SHB), which may be used in compression, tension and torsion testing, the strain rates never exceeds 103/s. In the present work, we use the expanding ring test where the strain rate is 104e105/s. A streak camera is used to examine the expanding ring velocity, and a water tank is used to collect the fragments. The experimental results are compared with the numerical simulations using the hydrocodes AUTODYN, IMPETUS Afea and a regularized smooth particle(RSPH) software. The number of fragments increases with the increase in the expansion velocity of the rings. The number of fragments is similar to the experimental results. The RSPH software shows much the same results as the AUTODYN where the Lagrangian solver is used for the ring. The IMPETUS Afea solver shows a somewhat different fragmentation characteristic due to the node splitting algorithm that induces pronounced tensile splitting.

Multi-scale elastoplastic mechanical model and microstructure damage analysis of solid expandable tubular

We present an in-depth study of the failure phenomenon of solid expandable tubular (SET) due to large expansion ratio in open holes of deep and ultra-deep wells. By examining the post-expansion SET, lots of microcracks are found on the inner surface of SET. Their morphology and parameters such as length and depth are investigated by use of metallographic microscope and scanning electron microscope (SEM). In addition, the Voronoi cell technique is adopted to characterize the multi-phase material microstructure of the SET. By using the anisotropic elastoplastic material constitutive model and macro/microscopic multi-dimensional cross-scale coupled boundary conditions, a sophisticated and multi-scale finite element model (FEM) of the SET is built successfully to simulate the material microstructure damage for different expansion ratios. The microcrack initiation and growth is simulated, and the structural integrity of the SET is discussed. It is concluded that this multi-scale finite element modeling method could effectively predict the elastoplastic deformation and the microscopic damage initiation and evolution of the SET. It is of great significance as a theoretical analysis tool to optimize the selection of appropriate tubular materials and it could be also used to substantially reduce costly failures of expandable tubulars in the field. This numerical analysis is not only beneficial for understanding the damage process of tubular materials but also effectively guides the engineering application of the SET technology.

Expanded models of the project portfolio selection problem with learning effect

This research develops two new models for project portfolio selection, in which the candidate projects are composed of multiple repetitive units. To reflect some real situations, the learning effect is considered in the project portfolio selection problem for the first time. The mathematical representations of the relationship between learning experience and investment cost are provided. One numerical example under different scenarios is demonstrated and the impact of considering learning effect is then discussed.

扩底桩竖向承载特性及群桩效应研究

为探明扩底群桩竖向承载特性,采用扩底桩筏结构,开展单桩(扩径比分别为1.5、2.0、2.5、3.0)和桩筏(扩径比为2)基础静载模型试验,分析其荷载传递规律,并建立桩间距为3.75、4.00、4.50、5.00倍桩直径时扩底桩筏基础有限元模型,研究桩间距对群桩效应影响。结果表明:扩底单桩和扩底桩筏结构荷载沉降曲线均为缓变型;扩底桩极限承载力随扩径比增大而逐渐增大,扩径比2.5~3.0时极限承载力增幅变缓,建议扩底桩扩径比取2.5~3.0;由于桩土共同沉降,桩间土压缩,桩土作用更充分,扩底桩筏基础中心桩侧摩阻力荷载分担比比扩底单桩增大了17.71%;群桩效应系数随桩间距增大而逐渐增大,桩间距为4.5~5.0倍桩直径时群桩效应系数增幅较小,群桩效应较弱,建议扩底桩筏基础桩间距取值不小于4.5倍桩直径。

基于随机森林模型的造纸废水出水质量预测方法

为提升造纸企业废水出水质量预测的自动化水平,强化废水处理能力,研究采用增广矩阵对造纸废水原始数据实施升维处理,进而通过动态慢性特征分析方法确定最佳特征数量。在此基础上,通过随机森林模型对当前特征数量下的样本数据进行回归预测分析。为验证动态慢性特征-随机森林复合模型的有效性,统计分析了该模型的预测误差并与其他模型进行对比,发现动态慢性特征-随机森林复合模型预测结果的平均绝对百分比误差(MAPE)、均方根误差(RMSE)和决定系数R^(2)分别为0.02、2.88、0.81,显著优于传统的慢性特征-支持向量回归复合模型,显示出了较为理想的造纸废水出水质量预测准确度水平,具有一定的应用价值。

气虚血瘀证小鼠模型拓展望诊指标的应用与评价

目的 以气虚血瘀证为代表,探索拓展望诊指标,为开展模型动物证候诊断的可行性提供依据。方法 将30只小鼠分为空白对照组、气虚血瘀组、中药反证组,每组10只。气虚血瘀组与中药反证组小鼠采用饥饿、疲劳、寒湿法进行造模,持续20 d;中药反证组自造模第3天开始每日予中药黄芪-莪术浓煎液灌胃,空白对照组和气虚血瘀组同期每日予相同容积蒸馏水灌胃,连续18 d。持续观测小鼠一般状态和体质量变化;于造模结束后检测粪便含水率、觅食欲,并通过避风实验、机械痛阈、旷场实验观察各组小鼠行为特点,拍照并利用图片分析软件对小鼠舌色进行分析。结果 与空白对照组比较,气虚血瘀组与中药反证组体质量低(P<0.01);避风实验中,2、3区域停留时间短、跨域次数少(P<0.01);旷场实验中,总路程短、平均速度低、跨格次数少、静止时间长(P<0.01);舌色R、G、B值均低(P<0.01)。与气虚血瘀组比较,中药反证组体质量高(P<0.01);避风实验中,2、3区域停留时间长、跨域次数多(P<0.01);旷场实验中,总路程长、平均速度高、跨格次数多、静止时间短(P<0.01);舌色R、G、B值均高(P<0.05)。气虚血瘀组、中药反证组机械痛阈均低于空白对照组(P<0.01),2组间差异无统计学意义(P>0.05);气虚血瘀组、中药反证组粪便颗粒稀软、易夹断,含水率高于空白对照组(P<0.01),2组间差异有统计学意义(P<0.05)。结论 避风实验和机械痛阈指标,以及旷场实验、粪便含水率和舌色检测指标,可作为诊断小鼠气虚血瘀证的拓展望诊指标,而觅食欲不可作为其有效指标。

混凝土三点弯曲梁随机骨料模型的开裂模拟

在试验表征及工程实践中,仿真可以准确反映裂缝的发展规律.采用内聚力模型来研究混凝土梁三点弯曲试验的宏观力学性能和细观开裂损伤破坏行为.在三点弯曲试验中的受力破坏的全过程研究中,对I型断裂能、II型断裂能、抗剪强度、抗拉强度及弹性模量(刚度)这5个控制单元开裂的关键参数进行了反演研究.通过宏观力学性能和细观开裂的试验结果,对一组试件的试验结果与参数化模型结果进行逆推分析,得到了控制因素在模拟中适用的参数范围.然后结合不同配合比试件的骨料定量化信息,对3个骨料面积不同的模型,应用已得到的参数范围中值来模拟获得裂缝扩展的定量结果,并对照模拟与试验的力学性能和裂缝量化结果验证参数范围的准确性.

教师情绪调节:内在机理、价值意蕴与提升策略

课堂教学成效深受教师情绪状态的影响。教师对自身情绪的敏锐觉察、精准调控与高效管理,无疑是营造积极向上课堂氛围不可或缺的重要因素。教师情绪调节是一个融合价值审视与策略部署的细腻心理过程,其遵循识别、选择、行动的递进逻辑,帮助教师准确标记自身情绪状态、有效激活并践行具体的情绪调节策略。教师情绪调节的各个阶段,在教育情境的动态变化与时间的悄然流逝中,不断经历迭代与优化。教师情绪调节的价值意蕴体现为:在工具价值上能够有效提升教学效能;在内生价值上能够增强教师职业幸福感;在交际价值上能够促进师生友好互动。展望未来,为了提升教师情绪调节能力,在职前阶段应高度重视并切实加强情绪教育,在职后阶段应对教师进行系统的情绪技能培训。在此基础上,还要对教师情绪调节能力培养进行持续探索,以构建长效化的发展机制。

Huadong sintering model about expansion and shrinkage

The whole sintering course from the beginning of heating to the end of heat preservation stage was studied by taking into account the influence of pressing. It was found that there exist expanding mechanism and shrinking mechanism in the sintering process, and the expanding mechanism is always acting before the shrinking mechanism. Whether the sintering body shrinks or expands depends on the interaction between the two mechanisms. And according to this, the Huadong sintering model in account of expansion and shrinkage mechanism was given. [

Combinatorial model of solute transport in porous media

Modeling of solute transport is a key issue in the area of soil physics and hydrogeology. The most common approach (the convection-dispersion equation) considers an average convection flow rate and Fickian-like dispersion. Here,we propose a solute transport model in porous media of continuously expanding scale, according to the combinatorics principle. The model supposed actual porous media as a combinative body of many basic segments. First, we studied the solute transport process in each basic segment body, and then deduced the distribution of pore velocity in each basic segment body by difference approximation, finally assembled the solute transport process of each basic segment body into one of the combinative body. The simulation result coincided with the solute transport process observed in test. The model provides useful insight into the solute transport process of the non-Fickian dispersion in continuously expanding scale.

Liver, biliary and pancreatic injuries in pancreaticobiliary maljunction model in cats

BACKGROUND： Pancreaticobiliary maljunction is a high risk factor of pancreatitis and biliary tract cancer. How this maljunction affects the liver remains obscure. This study aimed to examine the effects of pancreaticobiliary maljunction on the liver, pancreas and gallbladder in a cat model.METHODS： A model of choledocho-pancreatic side-to-side ductal anastomosis was created in ten cats. Before the procedure,a small piece of tissue from the liver, pancreas and gallbladder was collected as a control. The common channel formation was checked by cholecystography. The livers, pancreases and gallbladders of these cats were harvested for histological examination. The expression of proliferating cell nuclear antigen in the gallbladder was examined with immunohistochemistry. RESULTS： Seven of the 10 cats survived for 6 months after surgery. The color of the liver was darker in the PBM model than the control specimen, with nodules on the surface. Histological examination showed ballooning changes and inflammatory infiltrations and the histopathological score increased significantly（P〈0.05）. Also, mitochondria swelling and lipid droplet in cytoplasm were observed under an electron microscope. The pancreas also appeared darker in the PBM model than the control specimen and dilated pancreatic ducts were found in three cats. Histopathological examination revealed vascular proliferation and inflammatory infiltration with numerous neutrophils. Gallbladder epithelial cells were featured by expanded endoplasmic reticulum, increased intercellular space and cellular nucleus deformation. The positive cells ofproliferating cell nuclear antigen were increased significantly（P〈0.05）. CONCLUSION： The present study demonstrated that pancreaticobiliary maljunction can lead to the injuries of the liver, pancreas and gallbladder.

An Expanded Optimal Control Policy for a Coupled Tanks System with Random Disturbance

In this paper, an expanded optimal control policy is proposed to study the coupled tanks system, where the random disturbance is added into the system. Since the dynamics of the coupled tanks system can be formulated as a nonlinear system, determination of the optimal water level in the tanks is useful for the operation decision. On this point of view, the coupled tanks system dynamics is usually linearized to give the steady state operating height. In our approach, a model-based optimal control problem, which is adding with adjusted parameters, is considered to obtain the true operating height of the real coupled tanks system. During the computation procedure, the differences between the real plant and the model used are measured repeatedly, where the optimal solution of the model used is updated. On this basis, system optimization and parameter estimation are integrated. At the end of the iteration, the iterative solution approximates to the correct optimal solution of the original optimal control problem, in spite of model-reality differences. In conclusion, the efficiency of the approach proposed is shown.

Measurement on soil deformation caused by expanded-base pile in transparent soil using particle image velocimetry (PIV)

A new small-scale geotechnical physical model in 1-g and unconfined condition, combining the transparent soil, close-range photogrammetry and particle image velocimetry(PIV), was employed, which provides a non-intrusively internal deformation measurement approach to monitor the internal deformation of soil caused by expanded-base pile jacking with casing. The transparent soil was made of fused quartz and its refractive index matched blended oil, adding reflective particles(glass beads). Closerange photogrammetry was employed to record the images of the process of casing jacking and extraction in transparent soil, allowing the use of Matlab-based Geo-PIV to figure out the displacement field converted from image space to object space. Analysis of test results indicates that the maximum displacement caused by casing jacking for expandedconical-base pile is decreased by 29% compared with that for expanded-flat-base pile. The main movement happens at the early stage of casing extraction. The maximum displacement caused by casing extraction for the conical base is about 43% of that for the flatbase, while the affected zone caused by casing extraction for the conical base accounts for about 1/3 of that for the flat base. The contraction for horizontal displacements tends to decrease with the depth increasing. By contrast, the contraction under pile base decreases with the increasing of displacement. The displacements generated by jacking a conventional pile having a diameter equal to the casing diameter of the expanded-base pile were comparable to the net displacement taking place due to expanded-base pile installation for the conical base pile.

Correlation and Prediction of the Solubility of Solid Solutes in Chemically Diverse Supercritical Fluids Based on the Expanded Liquid Theory

For the proper design of any extraction procedure based on supercritical solvents, it is essential to have a sound knowledge of the solubility data of different compounds and the accurate way to represent it. The solute’s solubility in a supercritical solvent is dependent on the solute, the solvent, and the operating conditions (temperature and pressure). Developing a comprehensive experimental data set is an onerous task and time consuming and, thus, the incentive to develop predictive tools is substantial. In this paper, a technique is presented and tested to correlate and predict solute’s solubility in different supercritical fluids with a methodology based on the expanded liquid theory, in which the solid-fluid equilibrium is modeled using the local composition model of UNIQUAC in which the interaction parameters are related to the solvent reduced density with empiric equations. The most advantages of this model include: it does not require the knowledge of critical properties and sublimation pressure of solid solutes and does take into account the binary interaction between solid solute and solvent. The evaluation of the proposed model capabilities is done by testing it on a large data base consisting of experimental solubility data taken from literature of 33 binary systems solid-SC fluid. The results obtained for both correlation and prediction show good agreement with the experimental data used. For the comparison we have considered some literature models that account for effect of the system conditions (temperature and pressure) in addition to the sublimation pressure of the solute through their introduction of the enhancement factor and a model based on a modified Peng-Robinson equation of state.

Expanded Barro Regression in Studying Convergence Problem

This study develops the approach by Minh & Khanh [1] to the classic Barro and Sala-i-Martin method [2], [3] named “expanded Barro regression method”, and applies this approach in analyzing the convergence of provincial per capita GDP in Vietnam over the period of 1991-2007. Different aspects of provincial convergence are considered in this paper. The estimated result on conver-gence from our model is compared to other models.

有机朗肯循环无油涡旋膨胀机热力学特性研究及试验验证

为详细研究无油涡旋膨胀机的热力学特性,基于热力学第一定律、能量和质量平衡方程建立了泄漏模型和热力学模型,并进一步改变不同的工况参数来研究涡旋膨胀机泄漏量的变化情况。在综合考虑传热与泄漏对热力学模型的影响下,采用欧拉法对建立的热力学模型进行求解,得到并分析了涡旋膨胀机在运行1个周期内工质的压力、温度、质量随主轴转角变化情况。最后,通过搭建试验平台,对所建立的涡旋膨胀机热力学模型进行试验验证,并为涡旋膨胀机的性能分析提供一定的借鉴作用。

变截面涡旋膨胀机几何模型分析

提出一种由不同基圆半径的圆渐开线组成的新型变截面涡旋膨胀机,论述型线的生成方法,给出型线的一般方程,建立一系列圆渐开线变截面涡旋膨胀机的几何模型,并分析控制系数对变截面涡旋膨胀机容积变化的影响.构建传统等截面、变截面涡旋膨胀机的几何模型,对比分析几何模型的优劣.结果表明:提出的新型变截面涡旋膨胀机模型不但具有传统变截面模型的优点,而且可以大幅度减少计算量,并在一定程度上丰富了变截面涡旋膨胀机的种类,为开发高性能的涡旋膨胀机提供借鉴.

土工泡沫减压膨胀土挡墙侧向压力及影响因素分析

墙后膨胀性填土在吸水膨胀后,将对挡墙产生较大的侧向压力,严重时可能引起挡墙失稳。在墙背与膨胀性填土之间铺设可发性聚苯乙烯土工泡沫(expanded polystyrene geofoam,简称EPS)缓冲层,利用EPS的高压缩特性,为填土的侧向变形提供空间,可有效减小作用于挡墙的侧向压力。为了探明墙后铺设EPS的膨胀土挡墙在膨胀土浸润至饱和状态时,侧向压力沿墙高的分布规律及影响因素,开展了EPS减压膨胀土挡墙模型试验和相应的理论分析。结果表明:(1)当膨胀土浸润至饱和时,铺设密度为12 kg/m3的EPS可减小膨胀土挡墙约50%的总侧向压力;(2)无EPS的膨胀土挡墙的侧向压力沿墙深逐渐增大,而含EPS的膨胀土挡墙的侧向压力沿墙深基本相同;(3)EPS厚度越大,密度越小,对挡墙侧向压力的减压效果越好。