Constraint-force-based approach of modelling compliant mechanisms: principle and application

Numerous works have been conducted on modelling basic compliant elements such as wire beams, and closed-form analytical models of most basic compliant elements have been well developed. However, the modelling of complex compliant mechanisms is still a challenging work. This paper proposes a constraint-force-based (CFB) modelling approach to model compliant mechanisms with a particular emphasis on modelling complex compliant mechanisms. The proposed CFB modelling approach can be regarded as an improved free-body- diagram (FBD) based modelling approach, and can be extended to a development of the screw-theory-based design approach. A compliant mechanism can be decomposed into rigid stages and compliant modules. A compliant module can offer elastic forces due to its deformation. Such elastic forces are regarded as variable constraint forces in the CFB modelling approach. Additionally, the CFB modelling approach defines external forces applied on a compliant mechanism as constant constraint forces. If a compliant mechanism is at static equilibrium, all the rigid stages are also at static equilibrium under the influence of the variable and constant constraint forces. Therefore, the constraint force equilibrium equations for all the rigid stages can be obtained, and the analytical model of the compliant mechanism can be derived based on the constraint force equilibrium equations. The CFB modelling approach can model a compliant mechanism linearly and nonlinearly, can obtain displacements of any points of the rigid stages, and allows external forces to be exerted on any positions of the rigid stages. Compared with the FBD based modelling approach, the CFB modelling approach does not need to identify the possible deformed configuration of a complex compliant mechanism to obtain the geometric compatibility conditions and the force equilibrium equations. Additionally, the mathematical expressions in the CFB approach have an easily understood physical meaning. Using the CFB modelling approach, the variable constraint forces of three compliant modules, a wire beam, a four-beam compliant module and an eight-beam compliant module, have been derived in this paper. Based on these variable constraint forces, the linear and non-linear models of a decoupled XYZ compliant parallel mechanism are derived, and verified by FEA simulations and experimental tests.

The value of peer support and a strengths-based approach in a groupwork programme for fathers in a family support setting

This paper seeks to share and critically explore the learning gained through the genesis, realisation, and facilitation process of Just for Dads, a groupwork programme for fathers, run in a family support setting. It highlights the importance of and challenges involved in engaging men in practice, and in groupwork aimed at fathers in particular. It recounts the significance of using a strengths perspective as a framework for engaging fathers in groupwork and highlights its value as experienced by participants and facilitators. The dynamic of peer learning which developed as a key part of the groupwork process is discussed, both in relation to how it was experienced by participants and also the degree to which the facilitators were part of that dynamic. Overall the paper aims to document and air key issues arising in this relatively unexplored arena of groupwork and family support practice.

Leveraging lessons learned in organizations through implementing practice-based organizational learning and performance improvement - An opportunity for context-based intelligent assistant support (CIAS)

Organizations that leverage lessons learned from their experience in the practice of complex real-world activities are faced with five difficult problems. First, how to represent the learning situation in a recognizable way. Second, how to represent what was actually done in terms of repeatable actions. Third, how to assess performance taking account of the particular circumstances. Fourth, how to abstract lessons learned that are re-usable on future occasions. Fifth, how to determine whether to pursue practice maturity or strategic relevance of activities. Here, organizational learning and performance improvement are investigated in a field study using the Context-based Intelligent Assistant Support (CIAS) approach. A new conceptual framework for practice-based organizational learning and performance improvement is presented that supports researchers and practitioners address the problems evoked and contributes to a practice-based approach to activity management. The novelty of the research lies in the simultaneous study of the different levels involved in the activity. Route selection in light rail infrastructure projects involves practices at both the strategic and operational levels; it is part managerial/political and part engineering. Aspectual comparison of practices represented in Contextual Graphs constitutes a new approach to the selection of Key Performance Indicators (KPIs). This approach is free from causality assumptions and forms the basis of a new approach to practice-based organizational learning and performance improvement. The evolution of practices in contextual graphs is shown to be an objective and measurable expression of organizational learning. This diachronic representation is interpreted using a practice-based organizational learning novelty typology. This dissertation shows how lessons learned when effectively leveraged by an organization lead to practice maturity. The practice maturity level of an activity in combination with an assessment of an activity’s strategic relevance can be used by management to prioritize improvement effort.

Reforming the legal framework for clinical trials with neonates in Ireland: a children’s rights approach

This thesis assesses the current regulatory framework regarding clinical trials with neonates in Ireland from a children’s rights perspective, as derived from the UN Convention on the Rights of the Child 1989 (UN CRC) and its supporting instruments. The focus on neonates in the thesis is due to the particular need for clinical research with this group of children, their dependency on others for their protection and the lack of attention which has been given to them in the regulatory framework. The importance of children’s rights in this area is linked to the role of human rights in the regulation of clinical research in general. A rights-based approach is of great practical relevance in reforming law, policy and practice. For example, the CRC contains a set of commonly agreed legal benchmarks which can be used to assess the current framework and shape recommendations for reform. In this way, it provides a set of binding norms under international law, which must be complied with by states and state actors in all law, policy and practice affecting children. However, the contribution which a children’s rights approach could make to the regulation of research with children has not, to date, been explored in detail. This thesis aims to address this gap by developing a set of children’s rights-based benchmarks, which are used to assess the Irish regulatory framework for clinical trials with neonates and to develop recommendations for reform. The purpose of the analysis and recommendations is to assess Ireland’s compliance with international children’s rights law in the area and to analyse the potential of children’s rights to effectively address inadequacies in the Irish framework. The recommendations ultimately aim to develop a framework which will enhance the protection of neonates’ rights in this important area of children’s lives.