Denis Kelliher

Structure, material characteristics and function of the upper respiratory tract of the pygmy sperm whale

SUMMARY Cetaceans are neckless, so the trachea is very short. The upper respiratory tract is separate from the mouth and pharynx, and the dorsal blowhole connects, via the vestibular and nasopalatine cavities, directly to the larynx. Toothed cetaceans (Odontoceti) are capable of producing sounds at depth, either for locating prey or for communication. It has been suggested that during dives, air from the lungs and upper respiratory tract can be moved to the vestibular and nasal cavities to permit sound generation to continue when air volume within these cavities decreases as ambient pressure rises. The pygmy sperm whale, Kogia breviceps, is a deep diver (500–1000 m) that is known to produce hunting clicks. Our study of an immature female shows that the upper respiratory tract is highly asymmetrical: the trachea and bronchi are extremely compressible, whereas the larynx is much more rigid. Laryngeal and tracheal volumes were established. Calculations based on Boyles Law imply that all air from the lungs and bronchi would be transferred to the larynx and trachea by a depth of 270 m and that the larynx itself could not accommodate all respiratory air mass at a depth of 1000 m. This suggests that no respiratory air would be available for vocalisation. However, the bronchi, trachea and part of the larynx have a thick vascular lining featuring large, thin-walled vessels. We propose that these vessels may become dilated during dives to reduce the volume of the upper respiratory tract, permitting forward transfer of air through the larynx.

Shape and material characteristics of the trachea in the leatherback sea turtle promote progressive collapse and reinflation during dives

SUMMARY The leatherback turtle regularly undertakes deep dives and has been recorded attaining depths in excess of 1200 m. Its trachea is an almost solid, elliptical-section tube of uncalcified hyaline cartilage with minimal connective tissue between successive rings. The structure appears to be advantageous for diving and perfectly designed for withstanding repeated collapse and reinflation. This study applies Boyles law to the respiratory system (lungs, trachea and larynx) and estimates the changes in tracheal volume during a dive. These changes are subsequently compared with the results predicted by a corresponding finite element (FE) structural model, itself based on laboratory studies of the trachea of an adult turtle. Boyles law predicts that the lungs will collapse first during the initial stages of a dive with tracheal compression beginning at much deeper depths after complete air mass expulsion from the lungs. The FE model reproduces the changes extremely well (agreeing closely with Boyles law estimations) and provides visual representation of the deformed tracheal luminal area. Initially, the trachea compresses both ventrally and dorsally before levelling ventrally. Bulges are subsequently formed laterally and become more pronounced at deeper depths. The geometric configuration of the tracheal structure confers both homogeneity and strength upon it, which makes it extremely well suited for enduring repeated collapse and re-expansion. The structure actually promotes collapse and is an adaptation to the turtles natural environment in which large numbers of deep dives are performed annually.

Design, Development and Evaluation of an Inflatable Retractor for Atraumatic Retraction in Laparoscopic Colectomy

Laparoscopic colectomy is the gold standard in the treatment of malignant tumours arising in the mucosa of the colon wall. The procedure is performed under general endotracheal anaesthesia and involves establishing a pneumoperitoneum with the patient in the Trendelenburg position. However this position can cause anaesthetic difficulties due to excess blood flow to the head and neck, increased pressure on the diaphragm and increased venous pressure. In the absence of steep head-down positioning, the bowels fall or “spill” into the operating field, obstructing the surgical space. The primary goal of this work is to design an atraumatic laparoscopic retractor to minimise the Trendelenburg position whilst effectively retracting the bowels from the operating field. This work details the design, evaluation and optimisation of a novel, hand held, inflatable, laparoscopic retractor, through physical experimentation, computer simulation, and pre-clinical animal investigation. The optimised design for the inflatable retractor performs in line with simulated expectations, and was successfully tested for safety and technical feasibility in vivo in a porcine model, where the bowels were effectively removed from the operating space whilst the model remained in the supine position. These initial results represent a promising approach for the mitigation of the Trendelenburg position, whilst effectively retracting the bowels during laparoscopic colectomy, using this atraumatic, inflatable retractor.

Endodontic access cavity simulation in ceramic dental crowns

OBJECTIVES It is proposed that a non-uniform rational B-spline (NURBS) based solid geometric model of a ceramic crown would be a flexible and quick approach to virtually simulate root canal access cavities. The computation of strain components orthogonal to surface flaws generated during the drilling would be an appropriate way of comparing different access cavity configurations. METHODS A μCT scan is used to develop a full 3D NURBS geometric solid model of a ceramic crown. Three different access cavity configurations are created virtually in the geometric model and there are then imported into proprietary finite element software. A linear analysis of the each crown is carried out under appropriate in vivo loading and the results are post-processed to carry out a quantitative comparison of the three configurations RESULTS The geometric model is shown to be a flexible and quick way of simulation access cavities. Preliminary indications are that post processed strain results from the finite element analysis are good comparators of competing access cavity configurations. SIGNIFICANCE The generation of geometric solid models of dental crowns from μCT scans is a flexible and efficient methodology to simulate a number of access cavity configurations. Furthermore, advanced post-processing of the primary finite element analysis results is worthwhile as preliminary results indicate that improved quantitative comparisons between different access cavity configurations are possible.

Spatial representation in product modelling

An unambiguous definition of space is necessary before any attempt is made to develop product or process models for concurrent engineering in the AEC Industry. The ambiguity is the result of different and even conflicting approaches to its definition in the various phases of the building life cycle for different stakeholders, e.g. architects, engineers, and building services engineer etc. Some researchers consider space as an abstract property of things, while others consider it as a thing itself. Regardless of the definition, the space can be referred to as a collector of material objects and also as an object itself. This paper investigates the existing concepts and criteria of definition in various phases, compares the factual and ontological meaning, and specifies conceptual schemas for representation of space, geometry, and buildings.

Interior point tracking in shape evolving unstructured finite element meshes

An algorithm is presented for the tracking of interior points in a shape evolving unstructured FE mesh. Evolution of the boundary shape may be associated with a governing equation, as in moving boundary problems, or may be prescribed, as in structural shape optimisation. In the latter SSO case the point tracking algorithm may be used in conjunction with a FD approximation to determine geometric sensitivities: in this case the boundary deformation is a small perturbation. For meshes undergoing gross deformations of the boundary an incremental method is used. Reversibility tests are undertaken to assess the robustness and accuracy of the algorithm and examples are given to illustrate the general utility of the method.

Principal Component Analysis for Condition Monitoring of a Network of Bridge Structures

The use of visual inspections as the primary data gathering tool for modern bridge management systems is widespread, and thus leads to the collection and storage of large amounts of data points. Consequently, there exists an opportunity to use multivariate techniques to analyse large scale data sets as a descriptive and predictive tool. One such technique for analysing large data sets is principal component analysis (PCA), which can reduce the dimensionality of a data set into its most important components, while retaining as much variation as possible. An example is applied to a network of bridges in order to demonstrate the utility of the technique as applied to bridge management systems.

Formulation of STEP compliant building product model data for CFD analysis

Computational modelling is a resource hungry discipline requiring extensive expertise and large amounts of time. The ISO-STEP (International Standards Organisation-Standard for the Exchange of Product Model data) is proposing an integrated product model for CFD applications. This paper presents a specification for a STEP compliant building product model for CFD analysis incorporating IBMs Open Source Visualisation.

Integrating multivariate techniques in bridge management systems

The use of bridge management systems (BMS) by infrastructure stakeholders has led to the collection and retention of large quantities of data concerning the condition states of bridges throughout national and regional networks. The database for the BMS is often populated by the results of routine visual inspections, based on a prescribed scale for defining the condition state of the bridge’s individual elements, and of the bridge structure as a whole. The populating of the database also leads to the storage of large quantities of so-called metadata; which can describe the physical parameters of the bridge. The availability of this data allows the assessment of the BMS using multivariate techniques to enhance the life-cycle assessment of bridge networks, through advanced descriptive and predictive techniques applied to deteriorating network assets. Multivariate techniques such as principal component analysis have been demonstrated by the authors to be effectively applied as a descriptive tool to an existing BMS, and the results of a case study of a large dataset of bridges indicate its viability to be integrated into data-based approaches to infrastructural asset management.

A strategic view of ICT supported cost management for green buildings in the quantity surveying practice

Purpose – This paper aims to highlight the availability and use of software systems in the Irish construction professional cost consultancy process. Also to gather the views from practising quantity surveying professionals as to how available systems could assist total cost management of green buildings throughout their lifespan.Design/methodology/approach – A questionnaire was given to a number of senior quantity surveyors throughout Ireland to ascertain the extent to which IT systems were being used as part of a total life cycle cost analysis and control procedure. Particular focus of questions related to the extent to which use of IT systems encouraged information sharing. Statistical analyses of results of same are given.Findings – Quantity surveying practice must adapt and integrate cost management systems within the life cycle cost plan of a building. Use of well‐designed IT systems should complement the existing knowledge base of traditional cost models.Originality/value – The extent to which life ...