Optimal transportation meshfree method in geotechnical engineering problems under large deformation regime

Meshfree methods have been demonstrated as suitable and strong alternatives to the more standard numerical schemes such as finite elements or finite differences. Moreover, when formulated in a Lagrangian approach, they are appropriate for capturing soil behavior under high‐strain levels. In this paper, the optimal transportation meshfree method has been applied for the first time to geotechnical problems undergoing large deformations. All the features employed in the current methodology (ie, F‐bar, explicit viscoplastic integration, and master‐slave contact) are described and validated separately. Finally, the model is applied to the particular case of shallow foundations by using von Mises and Drucker‐Prager yield criteria to find the load at failure in the. The presented methodology is demonstrated to be robust and accurate when solving this type of problems.     

求解声波动方程的隐格式有限体积法

为研究声传播问题,提出一种声波动方程的隐格式有限体积法,该方法将格点型有限体积法与Newmark格式相结合.模拟平面波的传播过程,对比分析隐格式有限体积法和文献中显格式有限体积法的精度、稳定性及计算消耗等方面的性能.数值结果表明:当λ/Δx≥10时,两种算法均能得到满足精度要求的解;采用无条件稳定的隐格式算法,当满足ω0Δt≤0.3时,预测声压的相对峰值误差1%;当采用相同时间、空间步长时,隐格式算法精度高于显格式算法;隐格式算法对吸收边界的处理精度高于显格式算法,但对全反射边界的处理精度低于显格式算法;两种算法内存消耗比较接近,显格式算法的CPU耗时较少.     

彼得·纽马克的交际翻译和语义翻译述析

彼得·纽马克的交际翻译和语义翻译为不同种类的文本翻译提供了理想的翻译方法。两者的区别主要体现在译语的表达形式上。语义翻译要求译文接近原文的形式,在结构和词序安排上力求贴近原文;交际翻译则注重译文读者的理解和反应,即信息传递的效果。交际翻译要求译者重新组织语言结构,以使译文地道顺畅。     

西藏某水电站高边坡地震永久位移分析

西藏某水电站位于喜马拉雅地震带和藏中地震带交汇处,岸坡陡峭,坝址区某高边坡对枢纽工程的安全影响最大。为尽快消除该边坡的安全隐患,本文基于Slide软件选用了3条不同类型的地震波,采用Newmark滑块分析方法计算了该边坡在不同地震峰值加速度作用下的动力反应和永久位移,并采用拟静力法对该边坡在设计地震动作用下的稳定性进行了验算。计算结果表明,在设计地震动作用下该边坡是稳定的,随着地震波幅值的增加该边坡产生的总滑移量也在不断的增加;对于不同类型的地震波,虽然输入的地震峰值加速度相同,但地震动参数的差异会影响边坡产生的永久位移。研究结果可为工程单位进行类似边坡工程稳定性分析提供参考依据。     

时变结构动力响应分析的粗粒度并行算法

在线性时变以及非线性周期时变系统的响应计算问题中,由于在每个时间步上都需要更新系统矩阵、形成等效矩阵并对其进行三角分解,相对定常系统响应逐步积分,时变系统的计算量成倍增加。本文针对工程中的线性时变系统以及非线性周期系统,在分布式网络并行计算机群环境下设计并实现了一个粗粒度并行Ｎｅｗｍａｒｋ法,并将其应用于大型岸边起重机／运行小车系统以及直升机旋翼／机身耦合气弹响应问题,获得了较高的并行效率。     

分数阶Duffing振子的动力学研究

在经典Dtfffing振子中引入分数微分型阻尼项,推导了高效率的数值计算格式,对其表现出来的特有的非线性现象进行讨论．研究表明：分数微分型阻尼的分数阶值较小时,振子将出现倍周期分岔并导致混沌．在不同的外激励频率下,分数微分型Duffing振子会呈现对称性破缺、分岔、混沌等强烈的非线性现象;在一定参数范围内,分数微分型Duffing振子较经典Duffing振子,在较小的激励下即可进入混沌．     

Evaluating Earthquake-Triggered Landslide Hazard at the Basin Scale Through Gis in the Upper Sele River Valley

To evaluate techniques for assessing earthquake-triggeredlandslide hazard in the Southern Apennines (Italy), a GIS-based analysis was used to modelseismically induced slope deformations. Geological, geotechnical, geomorphological and seismologicaldata were integrated into a standard earthquake slope stability model. The model assessed thelandslide potential that existed during the 1980 Irpinian earthquake in the Upper Sele river Valley.The standard Newmark displacement analysis, widely used for predicting the location of shallowunstable slopes, does not take into account errors and/or uncertainties in the input parameters.Therefore, a probabilistic Newmark displacement analysis technique has been used. Probabilistictechniques allow, e.g., an estimation of the probability that a slope will exceed a certain criticalvalue of Newmark displacement. In our probabilistic method, a Monte-Carlo based simulation modelis used in conjunction with a GIS. The random variability of geotechnical data is modelled by probabilitydensity functions (pdfs), while for the seismic input three different regression laws wereconsidered. Input probability distributions are sampled and the resulting values input into empiricalrelations for estimating Newmark displacement. The outcome is a map in which to each siteis related a spatial probability distribution for the expected displacement in response to seismic loading.Results of the experiments show a high grade of uncertainty in the application of the Newmarkanalysis both for the deterministic and probabilistic approach in a complex geological setting suchas the high Sele valley, quite common in the Southern Apennines. They show a strong dependence onthe reliability of the spatial data used in input, so that, when the model is used at basin scale,results are strongly influenced by local environmental condition (e.g., topography, lithology, groundwatercondition) and decrease the model performance.     

拱脚开裂对拱桥动力特征影响的分析

在移动荷载作用下桥梁运动方程的基础上,采用Newmark法对拱脚不同开裂状态下的动态响应进行了研究,结果表明:拱脚开裂对桥结构的动态特征是有一定影响的,随着拱脚开裂程度的加大,桥面各控制截面的挠度振动频率逐渐加大.     

译者职责的翻译伦理解读

中西方翻译伦理模式的表述虽然不同,但从整体性要求来看,都可以归结到＂忠实性翻译伦理＂,隐藏在纷繁复杂的学术术语与学术框架之后的乃是传统一元化的＂忠实＂伦理的现代变体与多元呈现。基于这种认识,Chesterman的圣哲罗姆誓约为评价Newmark的观点提供了参照依据：译者应该以忠实再现原文为目标,奉行圣哲罗姆誓约说规约的职业伦理,这样才能不辱译者的使命。     

尤金·奈达和彼得·纽马克翻译思想之对比探讨

尤金·奈迭和彼得·纽马克是在被介绍到中国的西方翻译理论家中影响最大的两位。国内已有很多关于他们翻译思想的比较研究,但比较范围只局限于个别方面。为更加全面客观地认识这两位翻译理论家的翻译思想,本文从翻译的定义、性质、方法及翻译的评价等九个方面对这两位翻译家的翻译理论进行了综合对比研究,发现二者既有相似之处,也有很多差异。概括起来说,奈达的理论为功能论,而纽马克的理论则是文本论。