Automated Methods for Virtual Maintainability & Aerospace Maintenance Planning

Abstract. Modern business practices in engineering are increasingly turning to post manufacture service provision in an attempt to generate additional revenue streams and ensure commercial sustainability. Maintainability has always been a consideration during the design process but in the past it has been generally considered to be of tertiary importance behind manufacturability and primary product function in terms of design priorities. The need to draw whole life considerations into concurrent engineering (CE) practice has encouraged companies to address issues such as maintenance, earlier in the design process giving equal importance to all aspects of the product lifecycle. The consideration of design for maintainability (DFM) early in the design process has the potential to significantly reduce maintenance costs, and improve overall running efficiencies as well as safety levels. However a lack of simulation tools still hinders the adaptation of CE to include practical elements of design and therefore further research is required to develop methods by which ‘hands on’ activities such as maintenance can be fully assessed and optimised as concepts develop. Virtual Reality (VR) has the potential to address this issue but the application of these traditionally high cost systems can require complex infrastructure and their use has typically focused on aesthetic aspects of mature designs. This paper examines the application of cost effective VR technology to the rapid assessment of aircraft interior inspection during conceptual design. It focuses on the integration of VR hardware with a typical desktop engineering system and examines the challenges with data transfer, graphics quality and the development of practical user functions within the VR environment. Conclusions drawn to date indicate that the system has the potential to improve maintenance planning through the provision of a usable environment for inspection which is available as soon as preliminary structural models are generated as part of the conceptual design process. Challenges still exist in the efficient transfer of data between the CAD and VR environments as well as the quantification of any benefits that result from the proposed approach. The result of this research will help to improve product maintainability, reduce product development cycle times and lower maintenance costs.

Risk assessment of neonatal excipient exposure:Lessons from food safety and other areas

Newborn babies can require significant amounts of medication containing excipients intended to improve the drug formulation. Most medicines given to neonates have been developed for adults or older children and contain excipients thought to be safe in these age groups. Many excipients have been used widely in neonates without obvious adverse effects. Some excipients may be toxic in high amounts in which case they need careful risk assessment. Alternatively, it is conceivable that ill-founded fears about excipients mean that potentially useful medicines are not made available to newborn babies. Choices about excipient exposure can occur at several stages throughout the lifecycle of a medicine, from product development through to clinical use. Making these choices requires a scalable approach to analysing the overall risk. In this contribution we examine these issues.

Multibody modelling of a TB31 and a TB32 crash test with vertical portable concrete barriers: model verification and sensitivity analysis.

In this article the multibody simulation software package MADYMO for analysing and optimizing occupant safety design was used to model crash tests for Normal Containment barriers in accordance with EN 1317. The verification process was carried out by simulating a TB31 and a TB32 crash test performed on vertical portable concrete barriers and by comparing the numerical results to those obtained experimentally. The same modelling approach was applied to both tests to evaluate the predictive capacity of the modelling at two different impact speeds. A sensitivity analysis of the vehicle stiffness was also carried out. The capacity to predict all of the principal EN1317 criteria was assessed for the first time: the acceleration severity index, the theoretical head impact velocity, the barrier working width and the vehicle exit box. Results showed a maximum error of 6% for the acceleration severity index and 21% for theoretical head impact velocity for the numerical simulation in comparison to the recorded data. The exit box position was predicted with a maximum error of 4°. For the working width, a large percentage difference was observed for test TB31 due to the small absolute value of the barrier deflection but the results were well within the limit value from the standard for both tests. The sensitivity analysis showed the robustness of the modelling with respect to contact stiffness increase of ±20% and ±40%. This is the first multibody model of portable concrete barriers that can reproduce not only the acceleration severity index but all the test criteria of EN 1317 and is therefore a valuable tool for new product development and for injury biomechanics research.

Automated Methods for Aircraft Design Integrated with Manufacturing

Aircraft design is a complex, long and iterative process that requires the use of various specialties and optimization tools. However these tools and specialities do not include manufacturing, which is often considered later in the product development process leading to higher cost and time delays. This work focuses on the development of an automated design tool that accounts for manufacture during the design process focusing on early geometry definition which in turn informs assembly planning. To accomplish this task the design process needs to be open to any variation in structural configuration while maintaining the design intent. Redefining design intent as a map which links a set of requirements to a set of functions using a numerical approach enables the design process itself to be considered as a mathematical function. This definition enables the design process to utilise captured design knowledge and translate it into a set of mathematical equations that design the structure. This process is articulated in this paper using the structural design and definition for an aircraft fuselage section as an exemplar.

Design of a Virtual Reality Framework for Maintainability and assemblability test of complex systems

This paper presents a unique environment whose features are able to satisfy requirements for both virtual maintenance and virtual manufacturing through the conception of original virtual reality (VR) architecture. Virtual Reality for the Maintainability and Assemblability Tests (VR_MATE) encompasses VR hardware and software and a simulation manager which allows customisation of the architecture itself as well as interfacing with a wide range of devices employed in the simulations. Two case studies are presented to illustrate VR_MATE's unique ability to allow for both maintainability tests and assembly analysis of an aircraft carriage and a railway coach cooling system respectively. The key impact of this research is the demonstration of the potentialities of using VR techniques in industry and its multiple applications despite the subjective character within the simulation. VR_MATE has been presented as a framework to support the strategic and operative objectives of companies to reduce product development time and costs whilst maintaining product quality for applications which would be too expensive to simulate and evaluate in the real world.

Current status of gene therapy for breast cancer: progress and challenges

Breast cancer is characterized by a series of genetic mutations and is therefore ideally placed for gene therapy intervention. The aim of gene therapy is to deliver a nucleic acid-based drug to either correct or destroy the cells harboring the genetic aberration. More recently, cancer gene therapy has evolved to also encompass delivery of RNA interference technologies, as well as cancer DNA vaccines. However, the bottleneck in creating such nucleic acid pharmaceuticals lies in the delivery. Deliverability of DNA is limited as it is prone to circulating nucleases; therefore, numerous strategies have been employed to aid with biological transport. This review will discuss some of the viral and nonviral approaches to breast cancer gene therapy, and present the findings of clinical trials of these therapies in breast cancer patients. Also detailed are some of the most recent developments in nonviral approaches to targeting in breast cancer gene therapy, including transcriptional control, and the development of recombinant, multifunctional bio-inspired systems. Lastly, DNA vaccines for breast cancer are documented, with comment on requirements for successful pharmaceutical product development.

Intelligent DMU creation: Nominal CAD model preparation for automated tolerance allocation

This paper examines the integration of a tolerance design process within the Computer-Aided Design (CAD) environment having identified the potential to create an intelligent Digital Mock-Up [1]. The tolerancing process is complex in nature and as such reliance on Computer-Aided Tolerancing (CAT) software and domain experts can create a disconnect between the design and manufacturing disciplines It is necessary to implement the tolerance design procedure at the earliest opportunity to integrate both disciplines and to reduce workload in tolerance analysis and allocation at critical stages in product development when production is imminent.
The work seeks to develop a methodology that will allow for a preliminary tolerance allocation procedure within CAD. An approach to tolerance allocation based on sensitivity analysis is implemented on a simple assembly to review its contribution to an intelligent DMU. The procedure is developed using Python scripting for CATIA V5, with analysis results aligning with those in literature. A review of its implementation and requirements is presented.

Group Design-Build-Test Projects as the Core of an Integrated Curriculum in Product Design and Development

The School of Mechanical and Aerospace Engineering at Queen’s University Belfast introduced a new degree programme in Product Design and Development (PDD) in 2004. As well as setting out to meet all UK-SPEC requirements, the entirely new curriculum was developed in line with the syllabus and standards defined by the CDIO Initiative, an international collaboration of universities aiming to improve the education of engineering students. The CDIO ethos is that students are taught in the context of conceiving, designing, implementing and operating a product or system. Fundamental to this is an integrated curriculum with multiple Design-Build-Test (DBT) experiences at the core. Unlike most traditional engineering courses the PDD degree features group DBT projects in all years of the programme. The projects increase in complexity and challenge in a staged manner, with learning outcomes guided by Bloom’s taxonomy of learning domains. The integrated course structure enables the immediate application of disciplinary knowledge, gained from other modules, as well as development of professional skills and attributes in the context of the DBT activity. This has a positive impact on student engagement and the embedding of these relevant skills, identified from a stakeholder survey, has also been shown to better prepare students for professional practice. This paper will detail the methodology used in the development of the curriculum, refinements that have been made during the first five years of operation and discuss the resource and staffing issues raised in facilitating such a learning environment.

The efficacy of a CDIO based integrated curriculum as preparation for professional practice in product design and development

The School of Mechanical and Aerospace Engineering at Queen’s University Belfast started BEng and MEng degree programmes in Product Design and Development (PDD) in 2004. Intended from the outset to be significantly different from the existing programmes within the School the PDD degrees used the syllabus and standards defined by the CDIO Initiative as the basis for an integrated curriculum. Students are taught in the context of conceiving, designing, implementing and operating a product. Fundamental to this approach is a core sequence of Design-Build-Test (DBT) experiences which facilitates the development of a range of professional skills as well as the immediate application of technical knowledge gained in strategically aligned supporting modules.
The key objective of the degree programmes is to better prepare students for professional practice. PDD graduates were surveyed using a questionnaire developed by the CDIO founders and interviewed to examine the efficacy of these degree programmes, particularly in this key objective. Graduate employment rates, self assessment of graduate attributes and examples of work produced by MEng graduates provided positive evidence that their capabilities met the requirements of the profession. The 24% questionnaire response rate from the 96 graduates to date did not however facilitate statistically significant conclusions to be drawn and particularly not for BEng graduates who were under represented in the response group. While not providing proof of efficacy the investigation did provide a good amount of useful data for consideration as part of a continuous improvement process.

Mammalian cell production of a respiratory syncytial virus (RSV) candidate vaccine recovered using a product-specific affinity column

The recombinant production of a respiratory syncytial virus (RSV) candidate vaccine BBG2Na in baby hamster kidney cells (BHK-21 cells) was investigated. BBG2Na consists of a serum-albumin-binding region (BB) fused to a 101-amino-acid fragment of the RSV G-protein. Semliki Forest virus-based expression vectors encoding both intracellular and secreted forms of BBG2Na were constructed and found to be functional. Affinity recovery of BBG2Na employing human serum albumin columns was found to be inefficient due to the abundance of BSA in the applied samples. Instead, a strategy using a tailor-made affinity ligand based on a combinatorially engineered Staphylococcus aureus protein A domain, showing specific binding to the G-protein part of the product, was evaluated. In conclusion, a strategy for production and successful recovery of BBG2Na in mammalian cells was created, through the development of a product-specific affinity column.

Advanced glycation end product (AGE) accumulation on Bruch's membrane: links to age-related RPE dysfunction.

PURPOSE: Advanced glycation end products (AGEs) accumulate during aging and have been observed in postmortem eyes within the retinal pigment epithelium (RPE), Bruch's membrane, and subcellular deposits (drusen). AGEs have been associated with age-related dysfunction of the RPE-in particular with development and progression to age-related macular degeneration (AMD). In the present study the impact of AGEs at the RPE-Bruch's membrane interface was evaluated, to establish how these modifications may contribute to age-related disease. METHODS: AGEs on Bruch's membrane were evaluated using immunohistochemistry. A clinically relevant in vitro model of substrate AGE accumulation was established to mimic Bruch's membrane ageing. Responses of ARPE-19 growing on AGE-modified basement membrane (AGE-BM) for 1 month were investigated by using a microarray approach and validated by quantitative (q)RT-PCR. In addition to identified AGE-related mRNA alterations, lysosomal enzyme activity and lipofuscin accumulation were also studied in ARPE-19 grown on AGE-BM. RESULTS: Autofluorescent and glycolaldehyde-derived AGEs were observed in clinical specimens on Bruch's membrane and choroidal extracellular matrix. In vitro analysis identified a range of dysregulated mRNAs in ARPE-19 exposed to AGE-BM. Altered ARPE-19 degradative enzyme mRNA expression was observed on exposure to AGE-BM. AGE-BM caused a significant reduction in cathepsin-D activity in ARPE-19 (P

Development of a novel PCR assay for the identification of the black yeast, Exophiala (Wangiella) dermatitidis from adult patients with cystic fibrosis (CF)

Cystic fibrosis (CF) patients may suffer increased morbidity and mortality through colonisation, allergy and invasive infection from fungi. The black yeast, Exophiala dermatitidis (synonym Wangiella dermatitidis) has been found with increasing frequency in sputum specimens of CF patients, with reported isolation rates ranging from 1.1 to 15.7%. At present, no diagnostic PCR exists to aid with the clinical laboratory detection and identification of this organism. A novel species-specific PCR-based assay was developed for the detection of E. dermatitidis, based on employment of rDNA operons and interspacer (ITS) regions between these rDNA operons. Two novel primers, (designated ExdF & ExdR) were designed in silico with the aid of computer-aided alignment software and with the alignment of multiple species of Exophiala, as well as with other commonly described yeasts and filamentous fungi within CF sputum, including Candida. Aspergillus and Scedosporium. An amplicon of approximately 455 by was generated, spanning the partial ITS I region - the complete 5.8S rDNA region - partial ITS2 region, employing ExdF (forward primer [16-mer], 5'-CCG CCT ATT CAG GTC C-3' and ExdR (reverse primer [16-mer], 5'-TCT CTC CCA CTC CCG C-3', was employed and optimised on extracted genomic DNA from a well characterised culture of E. dermatitidis, as well as with high quality genomic DNA template from a further 16 unrelated fungi, including Candida albicans, C. dubliniensis, C. parapsilosis, C. glabrata, Scedosporium apiospermum, Penicillium sp., Aspergillus fumigatus, Aspergillus versicolor, Pichia guilliermondii, Rhodotorula sp., Trichosporon sp., Aureobasidium pullulans, Fusarium sp., Mucor hiemalis, Bionectria ochroleuca, Gibberella pulicaris. Results demonstrated that only DNA from E. dermatitidis gave an amplification product of the expected sire, whilst none of the other fungi were amplifiable. Subsequent employment of this primer pair detected this yeast from mycological cultures from 2/50 (4%) adult CF patients. These two patients were the only patients who were previously shown to have a cultural history of E. dermatitidis from their sputum. E. dermatitidis is a slow-growing fungus, which usually takes up to two weeks to culture in the microbiology laboratory and therefore is slow to detect conventionally, with the risk of bacterial overgrowth from common co-habiting pan- and multiresistant bacterial pathogens from sputum. namely Pseudomonas aeruginosa and Burkholderia cepacia complex organisms, hence this species-specific PCR assay may help detect this organism from CF sputum more specifically and rapidly. Overall, employment of this novel assay nay help in the understanding of the occurrence. aetiology and epidemiology of E. dermatitidis, as an emerging fungal agent in patients with CF. (C) 2008 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

Development of a novel DNA microarray to detect bacterial pathogens in patients with chronic obstructive pulmonary disease (COPD)

A novel microarray was constructed with DNA PCR product probes targeting species specific functional genes of nine clinically significant respiratory pathogens, including the Gram-positive organisms (Streptococcus pneumoniae, Streptococcus pyogenes), the Gram-negative organisms (Chlamydia pneumoniae, Coxiella burnetii Haemophilus spp., Legionella pneumophila, Moraxella catarrhalis, and Pseudomonas aeruginosa), as well as the atypical bacterium, Mycoplasma pneumoniae. In a "proof-of-concept" evaluation of the developed microarray, the microarray was compared with real-time PCR from 14 sputum specimens from COPD patients. All of the samples positive for bacterial species in real-time PCR were also positive for the same bacterial species using the microarray. This study shows that a microarray using PCR probes is a potentially useful method to monitor the populations of bacteria in respiratory specimens and can be tailored to specific clinical needs such as respiratory infections of particular patient populations, including patients with cystic fibrosis and bronchiectasis. (C) 2010 Elsevier B.V. All rights reserved.