消除模糊区的同杆双回线自适应重合闸

常规单相重合闸方式无法识别线路瞬时故障与永久故障,当重合于永久故障时,将对系统或相关设备增加一次冲击,并有可能导致直流换相失败。文中提出了一种仅需本回线信息的同杆双回线自适应重合闸判据,工程实用性强。该判据采用故障相故障点恢复电压,通过线路电容参数和多种故障类型下电容耦合电压的大小关系实时计算动作门槛,消除由线路电容参数和故障类型造成的故障性质判别模糊区;引入辅助判据,合理设置重合闸时间,消除由异名相跨线不接地故障造成的模糊区。仿真实验表明文中提出的自适应重合闸判据适用于同杆双回线可能出现的多种故障类型。     

阻尼板对水下航行体的力学影响作用

为更加准确地分析阻尼板对航行体产生的力学影响,分析无界流场状态下无壁面与有壁面时的平板力学.首先建立阻尼板对航行体整体的作用力和力矩关系表达式;其次通过仿真分析阻尼板周边的流场变化,得出阻尼板受到的流体作用力矩随张开时间并不呈简单的线性关系;最后利用FLUENT软件对带阻尼板与不带阻尼板的水下航行体进行数值模拟.结果表明:阻尼板的存在会使水下航行体的轴向附加质量增加并且尾部流速降低,可为阻尼板对水下航行体的力学影响作用分析提供一种思路和方法.     

Maintenance planning using continuous-state partially observable Markov decision processes and non-linear action models

The signs of deterioration in worldwide infrastructure and the associated socio-economic and environmental losses call for sustainable resource management and policy-making. To this end, this work presents an enhanced variant of partially observable Markov decision processes (POMDPs) for the life cycle assessment and maintenance planning of infrastructure. POMDPs comprise a method, commonly employed in the field of robotics, for decision-making on the basis of uncertain observations. In the work presented herein, a continuous-state POMDP formulation is presented which is adapted to the problem of decision-making for optimal management of civil structures. The aforementioned problem may comprise non-linear and non-deterministic action and observation models. The continuous-state POMDP is herein coupled with a normalised unscented transform (NUT) in order to deliver a framework able to tackle non-linearities that likely characterise action models. The capabilities of this enhanced framework and its applicability to the maintenance planning problem are presented via two applications. In a first illustrative example, the use of the NUT is demonstrated within the framework of the value iteration algorithm. Next, the proposed continuous-state framework is compared against a discrete-state formulation for implementation on a life cycle assessment problem.     

区域能源互联网信息物理建模及控制策略

大力发展低碳经济是解决能源危机、环境污染、温室效应等问题的有效途径之一。在分析区域分布式能源系统一般结构的基础上,提出冷热电联供下基于多智能体系统的区域能源互联网架构模型。结合元胞自动机理论,给出考虑冷热电协同控制的能源路由器设计方案。提出一种集中分散相融合的分布式协调控制策略。仿真算例验证了所提模型和控制策略的有效性。     

深基坑桩锚支护体系的作用效应分析

该文结合实际工程,利用桩、锚相互作用的机理,对深基坑桩锚支护结构的受力和变形特性进行研究,结果表明施加锚索对结构的作用效应影响明显,最后结合监测数据对方案的可行性进行了分析。     

Theoretical investigations on load‐bearing capacity of RC flat‐plate framed structures subject to middle column loss

This paper presents theoretical studies on load‐bearing capacity of reinforced concrete flat‐plate framed structures. The existing methods for determining load‐bearing capacity of simply supported slabs are first reviewed, and their limitations are presented. An energy‐based refined method is then proposed to enhance the accuracy of the existing methods by considering the contributions to internal energy dissipation due to the extension of reinforcing bars along yield lines, the additional resultant bending moment from membrane forces, and the sectional bending moment along yield lines of slabs. The refined method for simply supported slabs is extended for fixed supported slabs, and thus, the load‐bearing capacity of reinforced concrete flat‐plate structures subject to a middle column loss is analytically determined. The performance of the proposed method is validated against test results and also verified against finite element analyses. Parametric studies are conducted to investigate the effect of reinforcement ratio, slab thickness and aspect ratio on the stiffness, and yield‐line resistance of structures. It is found that for the fixed supported slabs, it is reasonable to assume negative yield lines along the slab edges to consider the effect of obvious concrete crushing along the edge. Square slabs have higher ultimate loads than rectangular slabs, due to a longer horizontal yield line in the middle in the rectangular slab, which has detrimental effect on the sectional ultimate bending moment. The numerical results show that the reinforcement ratio has little effect on the initial bending stiffness and yield‐line resistance of slabs for a given slab thickness and aspect ratio. The initial stiffness and yield‐line resistance increase as the slab thickness increases. For the same reinforcement ratio and slab thickness, a larger aspect ratio leads to a lower initial bending stiffness, yield‐line resistance, and stiffness in tensile membrane action stage, due to a longer yield line along which tensile membrane forces have a detrimental effect on the sectional bending moment.     

Structural health monitoring of innovative bridge decks

For more than a century, important civil engineering structures such as bridges, high-rise buildings, dams and marine platforms have contained iron or steel as the reinforcement for concrete or wood. The useful lives of such structures have often been severely limited by the corrosion of this ferrous component. Much thought has been given in recent years to constructing structures that are lighter, stronger and non-corrosive. These innovative structures are new and for these to be accepted by the engineering community monitoring is mandatory. ISIS Canada has been developing such structures and monitoring them. In this paper, innovative bridge decks that have been implemented are described.     

Partnerships for disability-inclusive road development in Papua New Guinea: Unusual suspects and equivocal gains

This article examines how an action research partnership developed and then influenced social justice outcomes during a 3-year research project to promote disability-inclusive road development in Papua New Guinea. The purpose of this article is to reflect on possible reasons why this partnership obtained certain positive results and not others. By reflecting on how the partnership developed, transformed over time, engendered achievements and failures, and affected the individuals and organizations involved in it, I aim to contribute to the understanding of how collaborative research partnerships can better promote the rights of those who are often marginalized from public space and decision-making. In this case study, neo-colonialism and underlying tensions between engineering and social development “world views”, both within and between partners, affected both positive outcomes and lost opportunities in terms of improving the lives of people with disabilities.     

The challenges of creating actionable knowledge: an action research perspective

Academia has a critical role in developing new knowledge which construction industry practitioners need to envision, undertake and sustain successful innovation. The new knowledge produced by academia, however, often does not satisfy the needs of practitioners. This unsatisfactory state of affairs is frequently taken to be the consequence of the cultural, motivational and operational differences between the two communities. Actionable knowledge is presented as a useful concept which can fuse the expectations, contributions and outputs of academia and practitioners. Within this context, action research is argued to be an appropriate methodology to develop successful actionable knowledge. Results from an action research project are given which provide researchers and practitioners greater understanding of the key factors that shape the degree to which action research produces actionable knowledge: change focus, collaboration capabilities and systematic process. The criteria intrinsic to Mode 2 research (Gibbons et al., 1994 Gibbons, M., Limoges, C., Nowotny, H., Schwartz, S., Scott, P. and Trow, M. 1994. The New Production of Knowledge: The Dynamics of Science and Research in Contemporary Societies, London: Sage.  [Google Scholar]) are demonstrated to have utility in evidencing actionable knowledge. The implication for policy is that there is a need to develop and use appropriate actionable knowledge frameworks and measures to design funding calls, and to evaluate research proposals and outputs.     

Lawyering Landscapes: Lawyers as Constituents of Landscape

Landscape and law cross-influence each other. Legal rules shape landscapes, while landscapes shape the culture from which rules emerge. In describing this interplay, landscape can seem passive, as a canvas on which laws paint visions of society; or active, as a matrix for the creation of law and culture. An alternative view is suggested: landscapes are opportunities for action, fields within which individuals interact with context in a mutually adaptive relationship. Lawyers are specialized constituents of this adaptation. Lawyers' acts and practices help to constitute the adaptations that shape a given landscape. A teaching module in which it was sought to prompt law students to become aware of the adaptive role of lawyering in landscape is described. The results suggest useful theoretical and methodological insights into landscape as a field of human activity, and the need for further study of lawyering as a force in the construction of landscape.