Comparative Analysis of Statistical Thickness Models for the Determination of the External Specific Surface and the Surface of the Micropores of Materials: The Case of a Clay Concrete Stabilized Using Sugar Cane Molasses

In this work, four empirical models of statistical thickness, namely the models of Harkins and Jura, Hasley, Carbon Black and Jaroniec, were compared in order to determine the textural properties (external surface and surface of micropores) of a clay concrete without molasses and clay concretes stabilized with 8%, 12% and 16% molasses. The results obtained show that Hasley’s model can be used to obtain the external surfaces. However, it does not allow the surface of the micropores to be obtained, and is not suitable for the case of simple clay concrete (without molasses) and for clay concretes stabilized with molasses. The Carbon Black, Jaroniec and Harkins and Jura models can be used for clay concrete and stabilized clay concrete. However, the Carbon Black model is the most relevant for clay concrete and the Harkins and Jura model is for molasses-stabilized clay concrete. These last two models augur well for future research.

Modeling and Optimization of Two Clays Acidic Activation for Phosphate Ions Removal in Aqueous Solution by Response Surface Methodology

This work deals with phosphate ions removal in aqueous solution by adsorption carried out using two clays, both in activated form. One, non-swelling clay, rich in kaolinite, is associated with illite and quartz. The other, swelling, richer in montmorillonite, is associated with kaolinite, illite and quartz. Seven factors including these two clays were taken into account in a series of experimental designs in order to model and optimize the acidic activation process favoring a better phosphate removal. In addition to the choice of clay nature, the study was also interested in the identification of the mineral acid, between hydrochloric acid and sulfuric acid, which would promote this acidic activation. Response Surface Methodology (RSM) was used for this purpose by sequentially applying Plackett and Burman Design and Full Factorial Design (FD) for screening. Then, a central composite design (CCD) was used for modeling the activation process. A mathematical surface model has been successfully established. Thus, the best acidic activation conditions were obtained by activating the montmorillonite clay with a 2N sulfuric acid solution, in an acid/clay mass ratio of 7.5 at 100°C for 16H. The phosphate removal maximum rate obtained was estimated at 89.32% ± 0.86%.

Improved shape hardening function for bounding surface model for cohesive soils

A shape hardening function is developed that improves the predictive capabilities of the generalized bounding surface model for cohesive soils, especially when applied to overconsolidated specimens. This improvement is realized without any changes to the simple elliptical shape of the bounding surface, and actually reduces the number of parameters associated with the model by one.

Comparison Study of Constitutive Models for Overconsolidated Clays

Widely distributed in natural deposits,the overconsolidated(OC)clays have attracted extensive experimental investigations on their mechanical behaviors,especially in the 1960s and 1970s.Based on these results,numerous constitutive models have also been established.These models generally fall into two categories:one based on the classical plasticity theory and the other the bounding surface(BS)plasticity theory,with the latter being more popular and successful.The BS concept and the subloading surface(SS)concept are the two major BS plasticity theories.The features of these two concepts and the representative models based on them are introduced,respectively.The unified hardening(UH)model for OC clays is also based on the BS plasticity theory but distinguishes itself from other models by the integration of the reference yield surface,unified hardening parameter,potential failure stress ratio,arid transformed stress tensor.Modification is made to the Hvorslev envelop employed in the UH model to improve its capability of describing the behaviors of clays with extremely high overconsolidation ratio in this paper.The comparison among the BS model,SS model,and UH model is performed.Evidence shows that all these three models can characterize the fundamental behaviors of OC clays,such as the stress dilatancy,strain softening and attainment of the critical state.The UH model with the revised Hvorslev envelop has the fewest parameters which are identical to those of the modified Cam-Clay model.

摩托车油泥模型的制作

摩托车覆盖件油泥模型的制作是摩托车整车设计开发中的重要环节。合格的油泥模型不仅是对二维效果图的完美诠释,还给后面阶段的三维测量、模具制作提供了具体的数据。所以说,油泥模型制作与整车设计开发的成功与否关系密切。本文拟对摩托车油泥模型制作的相关过程做一简单介绍。

基于Motion的摩托车多体动力学建模和仿真

为了从整体上研究摩托车的振动特性,采用Virtual lab/motion软件建立摩托车多刚体动力学仿真模型,并在施加外部激励(发动机激励和路面激励)的条件下对其进行动力学仿真。通过对模型施加不同工况下的发动机激励来比较车架质心处的加速度;通过Virtual lab/motion仿真摩托车通过凸块的运动过程,计算得到车架质心处的加速度。计算结果表明,该摩托车的振动特性良好。

CLAY MINERALS IN THE CHINA SEA AND ADJACENT SEAS

The clay minerals in the surface sediments from 354 stations have been analyzed qualita-tively and semiquantitatively. The obtained data are dealt mathematically. According to thecalculated results, the distribution laws and the trends of content changes of clay mineralsare discussed. The studied area is divided into four main provinces of sediments with differ-ent sources. Finally the author approached the laws of the migration and dispersal of thefine-grained matter carried into the seas by the Huanghe River, the Changjiang River, theZhujiang River and the Philippine Archipelagoes, and set up the transport model of the fine-grained matter in the China Sea and adjacent seas.

摩托车发动机主要参数对峰值扭矩的影响分析

考虑发动机制造过程中随机误差的因素,研究了各主要参数对发动机峰值扭矩的影响。首先,基于GT-Power搭建了发动机性能仿真分析模型,对影响发动机性能的主要参数进行正交试验,并利用极差法明确了滤芯流阻和进、排气门最大升程对应曲轴转角为发动机峰值扭矩的主要影响因素;其次,利用响应面实验分析,得出滤芯流阻和进、排气门最大升程对应曲轴转角,三者两两之间基本无相互作用;最终的研究结果表明,排气门最大升程对应曲轴转角对发动机峰值扭矩的影响最大。