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.

α-Tocopherol induces proatherogenic changes to HDL2 & HDL3: An in vitro and ex vivo investigation

Introduction: High density lipoproteins (HDL) have considerable potential for improving cardiovascular health. Additionally, epidemiological studies have identified an inverse relationship between a-tocopherol intake and cardiovascular disease, which has not been translated in randomised controlled trials. Objectives: This study assessed if increased α-tocopherol within HDL2 and HDL3 (HDL2&3) influenced their antiatherogenic potential. In the first of two in vitro investigations, the oxidation potential of HDL2&3 was assessed when α-tocopherol was added following their isolation. In the second, their oxidation potential was assessed when HDL2&3 were isolated from serum pre-incubated with α-tocopherol. Additionally, a 6-week placebo-controlled intervention with α-tocopherol assessed if α-tocopherol influenced the oxidation potential and activities of HDL2&3-associated enzymes, paraoxonase-1 (PON-1) and lecithin cholesteryl acyltransferase (LCAT). Results: Conflicting results arose from the in vitro investigations, whereby increasing concentrations of α-tocopherol protected HDL2&3 against oxidation in the post-incubated HDL2&3, and promoted HDL2&3-oxidation when they were isolated from serum pre-incubated with α-tocopherol. Following the 6-week placebo-controlled investigation, α-tocopherol increased in HDL2&3, while HDL2&3 became more susceptible to oxidation, additionally the activities of HDL2&3-PON-1 and HDL2-LCAT decreased. Conclusion: These results have shown for the first time that α-tocopherol induces changes to HDL2&3, which could contribute to the pathophysiology of cardiovascular disease.

Pioglitazone protects HDL(2&3) against oxidation in overweight and obese men

The worldwide epidemic of obesity is a major public health concern and is persuasively linked to the rising prevalence of diabetes and cardiovascular disease. Obesity is often associated with an abnormal lipoprotein profile, which may be partly negated by pioglitazone intervention, as this can influence the composition and oxidation characteristics of low-density lipoprotein (LDL). However, as pioglitazone's impact on these parameters within high-density lipoprotein (HDL), specifically HDL(2&3), is absent from the literature, this study was performed to address this shortcoming.

Chiton phylogeny (Mollusca Polyplacophora) and the placement of the enigmatic species Choriplax grayi (H. Adams & Angas)

Shallow marine chitons (Mollusca:Polyplacophora:Chitonida) are widespread and well described from established morphoanatomical characters, yet key aspects of polyplacophoran phylogeny have remained unresolved. Several species, including Hemiarthrum setulosum Carpenter in Dall, 1876, and especially the rare and enigmatic Choriplax grayi (Adams & Angas, 1864), defy systematic placement. Choriplax is known from only a handful of specimens and its morphology is a mosaic of key taxonomic features from two different clades. Here, new molecular evidence provides robust support for its correct association with a third different clade: Choriplax is placed in the superfamily Mopalioidea. Hemiarthrum is included in Cryptoplacoidea, as predicted from morphological evidence. Our multigene analysis of standard nuclear and mitochondrial markers demonstrates that the topology of the order Chitonida is divided into four clades, which have also been recovered in previous studies: Mopalioidea is sister to Cryptoplacoidea, forming a clade Acanthochitonina. The family Callochitonidae is sister to Acanthochitonina. Chitonoidea is resolved as the earliest diverging group within Chitonida. Consideration of this unexpected result for Choriplax and our well-supported phylogeny has revealed differing patterns of shell reduction separating the two superfamilies within Acanthochitonina. As in many molluscs, shell reduction as well as the de novo development of key shell features has occurred using different mechanisms, in multiple lineages of chitons.