Process Selection Using Variation and Cost Relations

Variations are inherent in all manufacturing processes and can significantly affect the quality of a final assembly, particularly in multistage assembly systems. Existing research in variation management has primarily focused on incorporating GD&T factors into variation propagation models in order to predict product quality and allocate tolerances. However, process induced variation, which has a key influence on process planning, has not been fully studied. Furthermore, the link between variation and cost has not been well established, in particular the effect that assembly process selection has on the final quality and cost of a product. To overcome these barriers, this paper proposes a novel method utilizing process capabilities to establish the relationship between variation and cost. The methodology is discussed using a real industrial case study. The benefits include determining the optimum configuration of an assembly system and facilitating rapid introduction of novel assembly techniques to achieve a competitive edge.

An Integration Methodology for Automated Recurring Cost Prediction using Digital Manufacturing Technology

The need to account for the effect of design decisions on manufacture and the impact of manufacturing cost on the life cycle cost of any product are well established. In this context, digital design and manufacturing solutions have to be further developed to facilitate and automate the integration of cost as one of the major driver in the product life cycle management. This article is to present an integration methodology for implementing cost estimation capability within a digital manufacturing environment. A digital manufacturing structure of knowledge databases are set out and the ontology of assembly and part costing that is consistent with the structure is provided. Although the methodology is currently used for recurring cost prediction, it can be well applied to other functional developments, such as process planning. A prototype tool is developed to integrate both assembly time cost and parts manufacturing costs within the same digital environment. An industrial example is used to validate this approach.

Resource Efficient Configuration of an Aircraft Assembly Line

The design of efficient assembly systems can significantly contribute to the profitability of products and the competitiveness of manufacturing industries. The configuration of a an efficient assembly line can be supported by suitable methodologies and techniques, such as design for manufacture and assembly, assembly sequence planning, assembly line balancing, lean manufacturing and optimization techniques. In this paper, these methods are applied with reference to the industrial case study of the assembly line of a Skycar light aircraft. The assembly process sequence is identified taking into account the analysis of the assembly structure and the required precedence constraints, and diverse techniques are applied to optimize the assembly line performance. Different line configurations are verified through discrete event simulation to assess the potential increase of efficiency and throughput in a digital environment and propose the most suitable configuration of the assembly line.

Parametric CAD model based shape optimization using adjoint functions

Adjoint methods have proven to be an efficient way of calculating the gradient of an objective function with respect to a shape parameter for optimisation, with a computational cost nearly independent of the number of the design variables [1]. The approach in this paper links the adjoint surface sensitivities (gradient of objective function with respect to the surface movement) with the parametric design velocities (movement of the surface due to a CAD parameter perturbation) in order to compute the gradient of the objective function with respect to CAD variables.
For a successful implementation of shape optimization strategies in practical industrial cases, the choice of design variables or parameterisation scheme used for the model to be optimized plays a vital role. Where the goal is to base the optimization on a CAD model the choices are to use a NURBS geometry generated from CAD modelling software, where the position of the NURBS control points are the optimisation variables [2] or to use the feature based CAD model with all of the construction history to preserve the design intent [3]. The main advantage of using the feature based model is that the optimized model produced can be directly used for the downstream applications including manufacturing and process planning.
This paper presents an approach for optimization based on the feature based CAD model, which uses CAD parameters defining the features in the model geometry as the design variables. In order to capture the CAD surface movement with respect to the change in design variable, the “Parametric Design Velocity” is calculated, which is defined as the movement of the CAD model boundary in the normal direction due to a change in the parameter value.
The approach presented here for calculating the design velocities represents an advancement in terms of capability and robustness of that described by Robinson et al. [3]. The process can be easily integrated to most industrial optimisation workflows and is immune to the topology and labelling issues highlighted by other CAD based optimisation processes. It considers every continuous (“real value”) parameter type as an optimisation variable, and it can be adapted to work with any CAD modelling software, as long as it has an API which provides access to the values of the parameters which control the model shape and allows the model geometry to be exported. To calculate the movement of the boundary the methodology employs finite differences on the shape of the 3D CAD models before and after the parameter perturbation. The implementation procedure includes calculating the geometrical movement along a normal direction between two discrete representations of the original and perturbed geometry respectively. Parametric design velocities can then be directly linked with adjoint surface sensitivities to extract the gradients to use in a gradient-based optimization algorithm.
The optimisation of a flow optimisation problem is presented, in which the power dissipation of the flow in an automotive air duct is to be reduced by changing the parameters of the CAD geometry created in CATIA V5. The flow sensitivities are computed with the continuous adjoint method for a laminar and turbulent flow [4] and are combined with the parametric design velocities to compute the cost function gradients. A line-search algorithm is then used to update the design variables and proceed further with optimisation process.

From the Land to Sea and Back Again? Using Terrestrial Planning to Understand the Process of Marine Spatial Planning

Over the last 5–10 years, marine spatial planning (MSP) has emerged as a new management regime for national and international waters and has already attracted a substantial body of multi-disciplinary research on its goals and policy processes. This paper argues that this literature has generally lacked deeper reflexive engagement with the emerging system of governance for our seas that has meant that many of MSP’s core concepts, assumptions and institutional arrangements have not been subject rigorous intellectual debate. In an attempt to initiate such an approach, this article explores the relationship between MSP and its land-based cousin, terrestrial spatial planning (TSP). While it is recognized that there are inherent limitations to a comparison of these two systems, it is argued that the tradition of social science debate over the purpose and processes of TSP can be used as a useful stimulus for a more rigorous reflection of such issues as they relate to MSP. The article therefore explores some of the parallels between MSP and TSP and then discusses some of the key intellectual traditions that have shaped TSP and the implications these may have for future marine planning practice. The article concludes with a number of potentially useful new avenues that may form the basis of a critical research agenda for MSP.

The impact of peer review on the radiotherapy treatment planning process in the treatment of lung cancer

Background:
Advanced radiotherapy techniques permit accurate delivery of radiotherapy to lung tumours. Improved accuracy increases the possibility of radiotherapy field geographic miss of the tumour. One source of error is the accuracy of target volume (TV) delineation by the clinical oncologist. Colleague peer review of all curative intent lung cancer plans has been mandatory in our institution since May 2013. At least 2 clinical oncologists review plans checking treatment paradigm, TV delineated, dose to tumour and dose to critical organs. We report the impact of peer review on the radiotherapy planning process for lung cancer.

Methods:
The radiotherapy treatment plans of all patients receiving radical radiotherapy were presented at weekly peer review meetings after their TVs volumes were provisionally signed off by the treating consultant or post-fellowship registrar. All cases and any resultant change to the treatment plan were recorded in our prospective peer review database. We present the summary of changes agreed following the peer review process for a 6 month period.

Results:
Fifteen peer review sessions, including 46 patients (36 NSCLC, 10 SCLC) were analysed. An average of 3 cases were discussed per meeting (range 1 5). 24% of treatment courses were changed. In 4% there was a complete change in paradigm
of treatment (1 patient proceeded to induction chemotherapy, 1 patient had high dose palliative radiotherapy). In 16% there was a change in TV delineated and in 9% a change in dose (2 dose reductions and 2 alterations to post-operative dose fractionations).

Conclusions:
Consultant led peer review resulted in a change in a component of the treatment plan for 28% of patients that would not otherwise have taken place. Given this impact, consultant led peer review should be considered as an essential component in the radiotherapy planning process for all patients treated with curative radiotherapy.

Consideration of coastal risk in the Irish spatial planning process

The vulnerability of coastal areas to associated hazards is increasing due to population growth, development pressure and climate change. It is incumbent on coastal governance regimes to address the vulnerability of coastal inhabitants to these hazards. This is especially so at the local level where development planning and control has a direct impact on the vulnerability of coastal communities. To reduce the vulnerability of coastal populations, risk mitigation and adaptation strategies need to be built into local spatial planning processes. Local government, however, operates within a complex hierarchal governance framework which may promote or limit particular actions. It is important, therefore, to understand how local coastal planning practices are shaped by national and supranational entities. Local governments also have to respond to the demands of local populations. Consequently, it is important to understand local populations’ perceptions of coastal risk and its management. Adopting an in-depth study of coastal planning in County Mayo, Ireland, this paper evaluates: (a) how European and national policies and legislation shape coastal risk management at local level; (b) the incorporation of risk management strategies into local plans; and (c) local perception of coastal risks and risk management. Despite a strong steer from supranational and national legislation and policy, statutory local plans are found to be lacking in appropriate risk mitigation or adaptation strategies. Local residents appear to be lulled into a sense of complacency towards these risks because of the low level of attention afforded to them by the local planning authorities. To avoid potentially disastrous consequences for local residents and businesses, it is imperative that this situation is redressed urgently. Based on our analysis, we recommend: the development and implementation of a national ICZM strategy, supported by detailed local ICZM plans; and obliging local government to address known risks in their plans rather than defer them to project level decision making.

The Impact of Colleague Peer Review on the Radiotherapy Treatment Planning Process in the Radical Treatment of Lung Cancer

AIMS: Modern radiotherapy uses techniques to reliably identify tumour and reduce target volume margins. However, this can potentially lead to an increased risk of geographic miss. One source of error is the accuracy of target volume delineation (TVD). Colleague peer review (CPR) of all curative-intent lung cancer plans has been mandatory in our institution since May 2013. At least two clinical oncologists review plans, checking treatment paradigm, TVD, prescription dose tumour and critical organ tolerances. We report the impact of CPR in our institution.

MATERIALS AND METHODS: Radiotherapy treatment plans of all patients receiving radical radiotherapy were presented at weekly CPR meetings after their target volumes were reviewed and signed off by the treating consultant. All cases and any resultant change to TVD (including organs at risk) or treatment intent were recorded in our prospective CPR database. The impact of CPR over a 13 month period from May 2013 to June 2014 is reported.

RESULTS: One hundred and twenty-two patients (63% non-small cell lung carcinoma, 17% small cell lung carcinoma and 20% 'clinical diagnosis') were analysed. On average, 3.2 cases were discussed per meeting (range 1-8). CPR resulted in a change in treatment paradigm in 3% (one patient proceeded to induction chemotherapy, two patients had high-dose palliative radiotherapy). Twenty-one (17%) had a change in TVD and one (1%) patient had a change in dose prescription. In total, 6% of patients had plan adjustment after review of dose volume histogram.

CONCLUSION: The introduction of CPR in our centre has resulted in a change in a component of the treatment plan for 27% of patients receiving curative-intent lung radiotherapy. We recommend CPR as a mandatory quality assurance step in the planning process of all radical lung plans.