Modelling the FEBEX THM experiment using a state surface approach

Buffer materials being considered as engineered barriers in nuclear fuel waste (NFW) disposal systems possess a pronounced nonlinear behaviour in the unsaturated state. In order to simulate such non-linear responses,the authors adopted an incrementally nonlinear poro-elastic approach where the coefficients of the governing equations are assumed to be functions of suction and the void ratio. These functions are in turn developed from a state-surface equation obtained from suction-controlled oedometric tests. In this paper we show the derivation of the governing equations of the poro-elastic model. A finite element computer code, FRACON, was developed by the authors to numerically solve the above equations. We first use the code to simulate laboratory tests to characterize the swelling properties of a typical bentonite. That same bentonite was used in the FEBEX in-situ heater experiment, conducted at the Grimsel site, Switzerland. The FRACON code was also used to perform blind predictions of the FEBEX heater experiment. It is shown that the model correctly predicts drying of the bentonite near the heaters and re-saturation near the rock interface. The evolution of temperature and the heater thermal output were also reasonably well predicted by the model. The trends in the total stresses developed in the bentonite were correctly predicted; the absolute values however were underestimated probably due to the omission of pore pressure build-up in the rock mass.     

试论小城镇规划的特色营造——以平利县长安镇镇区规划为例

极富地域特色的小城镇在规划、建设过程中,由于人们对地方特色及资源的认识、理解不够,缺乏必要的特色规划手段,导致城镇特色缺失、文化缺失、千镇一貌等现象,这有悖于城镇特色发展战略的实施。本文以陕西省安康市平利县长安镇镇区规划为例,提出了在城镇特色营造中规划应该遵循的原则及理念,旨在阐明城镇特色规划应从实际出发制定内容框架,提出规划设计思路。     

植入光纤光栅复合材料横担的应力监测可行性分析

对聚氨酯复合材料横担进行了受力分析,指出需要重点关注的受力关键部位,然后分析了在应力应变条件下光纤光栅的光谱特征变化,指出了利用光纤光栅来监测复合材料横担应力变化的可行性,试验研究了植入复合材料横担前不同中心波长的光纤光栅应变传感特性,最后初步设计了基于光纤光栅复合材料横担应力监测系统。     

浅析朝鲜族文化中的设计观念

朝鲜族文化深受中国的汉文化以及日本、西方等文化的影响,但在周围大国环饲的情况下,发展出自己独特的个性和气质。文章尝试对朝鲜族文化中的设计观念从文化背景、来源和基本特征等方面进行简要的梳理和分析。     

钢结构滑移施工技术研究及工程应用

滑移施工技术是解决大跨度空间钢结构施工的有效方法。滑移施工技术是一个较大的范畴,按照不同的分类标准,可分为多种方法。详细介绍了滑移施工技术的分类、特点、基本原理及应用中应注意的事项。最后介绍了四个工程应用实例,来增强对滑移施工技术的理解。     

某城乡一体化开发项目投融资方案设计

基于京津冀地区某城乡一体化开发项目的实际需求,分析了其区域特点,并对其以“宅基地换房”模式进行的城乡一体化开发项目规划进行了详细解读,提出了房地产企业参与投资的几种投融资方案。在深入探讨各方案适用性及其特点的基础上,提出了一种“村民安置房建设与土地一、二级开发捆绑进行”的推荐模式。在此基础上,对该模式的操作流程和项目结构进行了详细设计,并提出了项目的关键成功因素,以期为我国城乡一体化开发项目提供一定参考。     

恒荷载作用下复合地基非线性分析

从桩周土体径竖向渗流方程出发,采用土体e–logσ和e–logk半对数模型,对于排水桩桩体仅考虑竖向渗流并考虑涂抹区影响,建立恒荷载作用下复合地基非线性固结方程。通过与已有解的对比,证明此解析解的正确性。根据对复合地基非线性固结分析发现:复合地基固结速率随土体非线性参数Cc/Ck和荷载增量σ0/σsi的增大而减小,但相比Cc/Ck,荷载增量σ0/σsi对固结速率影响很小;随着桩土模量比增大,复合地基固结速率加快,且非线性参数Cc/Ck对固结速率的影响程度减小;排水桩复合地基固结速率受kh/kc即桩体渗透性影响很大。     

浅谈市政工程量清单与标底中的几点问题

针对市政工程工程量清单和标底编制过程中出现的一些问题做了分析,并对土方工程和技术措施、材差等特殊项目处理提出了几点建议,以期推广和完善清单计价模式的应用。     

Adaptive calibration of a capacitance tomography system for imaging water droplet distribution

A highly sensitive electrical capacitance tomography (ECT) system based on an HP4284 impedance analyser has been developed and used to quantify low concentration multi-phase flows in wet gas separation processes. The system hardware provides high accuracy (0.05%) and high resolution (10⁻¹⁷ F). The sensor was calibrated in an environmental chamber with solid samples of known permittivity over ranges of temperature and humidity. Adaptive calibration and adjacent electrode pair correction techniques were applied to image very low concentration profiles. This paper describes the techniques used and presents the experimental results obtained from a test flow rig called Twister, which has been designed to separate liquid droplets from wet gas streams. The test results over a range of operating conditions (20–95% humidity) demonstrate that the ECT system is capable of reconstructing clear images of the droplet distribution inside Twister. Changes as small as 1 gWater/kgAir in the form of liquid droplets were detectable. It has also been shown that the concentration of the condensable phase can be estimated quantitatively within 20% in comparison with the reference measurements.     

Wall-following control of a two-wheeled mobile robot

Wall-following control problem for a mobile robot is to move it along a wall at a constant speed and keep a specified distance to the wall.This paper proposes wall-following controllers based on Lyapunov function candidate for a two-wheeled mobile robot (MR) to follow an unknown wall. The mobile robot is considered in terms of kinematic model in Cartesian coordinate system. Two wall-following feedback controllers are designed: full state feedback controller and observer-based controller. To design the former controller, the errors of distance and orientation of the mobile robot to the wall are defined, and the feedback controller based on Lyapunov function candidate is designed to guarantee that the errors converge to zero asymptotically. The latter controller is designed based on Busawon’s observer as only the distance error is measured. Additionally, the simulation and experimental results are included to illustrate the effectiveness of the proposed controllers.