取样扰动对土的工程性质指标影响的试验研究

本文报道了取样扰动对土的工程性质指标影响的一批研究成果。采用100mm和75mm两种直径的取土器取样作对比试验以研究取土器扰动的影响。试验证明取土器直径对试样的孔隙比、压缩系数、超固结比和天然强度等指标都有明显的影响。采用两种预固结处理的方法以恢复原生应力状态,用不固结不排水试验比较了应力状态对天然强度的影响。对取土过程中土体应变的分布及其对土样扰动的影响用有限元方法进行了模拟。     

Facilitating project management education through groups as systems

Project management education is currently facing several challenges to help people deal more effectively with the complexities of their future work. Students' exposure to ‘real’ project situations in which they can use, develop, and reflect on their skills as well as learn from each other has become essential and in need of further improvements. This paper presents a group-based approach to project management education which uses the notion of a ‘group’ as a system in order to develop students' individual awareness of and abilities to deal with both expected and unexpected project situations. The approach aims at nurturing and fostering students' involvement in project situations whilst challenging them to go beyond their own learning comfort zones. Reflections from our experience of using this approach in several courses in UK higher education institutions lead us to identify its benefits, different strategies that students use to respond to challenges, and new possibilities to continue improving project management education.     

盾构施工引起地表变形的人工神经网络研究

讨论了地铁区间隧道盾构施工引起的地表变形机理,并结合某地铁工程的实践,利用神经网络技术处理非线性问题的优势,应用人工神经网络对地表沉降进行了预测,经与现场实测值作对比分析,证实该方法具有较高的准确性.研究表明,该方法对处理此类非结构性规律的多因素综合影响问题较一般方法具有更强的适应性.     

打桩对周围黄土的扰动特性影响

在饱和软土小孔扩张理论的基础上 ,推导了非饱和土 ( φ≠ 0 )的弹塑性解 ,主要包括弹性区、塑性区任一点的应力增量、塑性区边界上径向位移、塑性区半径及桩土间的挤压应力 ,分析了非饱和土层中沉桩挤土效应及扰动特性 ;通过模型试验 ,研究了打桩引起的侧向挤压应力变化 ,打桩对桩周土体的密实度与变形的影响等扰动特性 ,并划分了不同的扰动区域     

国有土地的房屋拆迁补偿之研究

近年来．国有土地上房屋拆迁中的被拆迁人和拆迁人常常对拆迁补偿难以达成协议．拆迁纠纷不断。本文从纠纷焦点出发，分析了拆迁中的土地使用权的价值问题和装修补偿问题．研讨了房地分离的估价理论和方法，提出相应的建议和解决问题的方法。     

顶管施工引起的土体扰动理论分析及试验研究

近年来，顶管施工技术在中国得到迅速发展，并广泛应用于给排水管道工程，但顶管施工中土体的扰动机理及土体性状的变化有待深入研究与探讨。在前人的基础上，研究了顶管施工引起土体扰动的机理，提出了更加准确的土体扰动分区图。对某顶管工程进行了现场监测，内容包括地面变形、深层土体移动、孔隙水压力、土压力、地下水位以及顶管施工现场记录。测试结果表明土体扰动受土质条件、施工技术和现场控制程度的影响，其中现场控制程度(包括顶力、土压力、管线纠偏和注浆压力)的影响最大。土压力、孔隙水压力、地下水位、地面变形及深层土体移动的变化都跟掘进机与测试断面之间的距离有直接关系。当掘进机离测点还有一段距离(6～7m)时，土压力、孔隙水压力和地下水位上升达到峰值。地面隆起及深层土体移动则是在掘进机尾部离开测点时达到最大，随后总体上呈下降趋势。现场测试结果很好地验证了土体扰动理论。     

Theorizing Inside Activism: Understanding Policymaking and Policy Change from Below

To further our understanding on policymaking and policy change we need to recognize the significance of individual key actors in policy and planning processes. This article theorizes on the characteristics and policy influence of inside activism in which individual public officials act strategically from inside public administration to change government policy and action in line with a civic engagement and value commitment. Based on initial empirical findings from Swedish local government, we argue that inside activism is empirically relevant but not satisfactorily covered by other key actor concepts. We theorize that inside activism is 1) dualistic: open, deliberative, consensus-seeking and tacit, tactical, power-driven; 2) influential through informal networking inside and outside of government; and 3) dynamic as it varies over time and between critical situations. Due to current trends in society and public administration (e.g. governance), we expect inside activism to be increasingly relevant and we encourage further theoretical, empirical as well as normative research and discussion on this phenomenon.     

顶管施工引起土体变形机理分析

从顶管施工的整个施工工艺过程出发,详细分析了顶管施工引起地面沉降的变形机理,找出引起地面变形的相关因素,并指出顶管施工对土体扰动最大的位置应在开挖工作面及以后的位置。     

一种自适应扰动观测器的机械手滑模控制研究

针对在未知载荷下的机械手控制不确定性问题,基于非线性扰动观测器与滑模控制方法,提出一种非线性观测器增益的通用设计方法。通过设计一种自适应算法的非线性扰动观测器,逼近机械手的未知载荷引起的不确定性,来估计由未知恒定载荷所引起的外力,扩大了观测器扰动的适用范围。在一定条件下,利用Lyapunov方法证明了观测器的稳定性。通过算例仿真验证了所提出的自适应非线性观测器的滑模控制方法,在受载荷变化的非线性机械手控制系统等方面,能够有效缓解机械手控制的抖振问题。     

典型汽车电器电磁干扰及其对抗措施研究

随着汽车电子技术的迅猛发展,汽车电磁环境越来越复杂。汽车电器零部件在此环境下不仅要能够可靠工作,而且要保证不对周围电器造成明显的影响。以国家强制检验的典型汽车电器——汽车闪光器为例,深入分析了汽车电器的电磁干扰机制,并且通过采用几种实用的电磁干扰对抗性措施,最终通过了相关的国际电磁兼容标准,对汽车电器的电磁兼容设计有较高的参考价值。